US20030010286A1 - Conveyorized vacuum injection system - Google Patents
Conveyorized vacuum injection system Download PDFInfo
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- US20030010286A1 US20030010286A1 US10/233,746 US23374602A US2003010286A1 US 20030010286 A1 US20030010286 A1 US 20030010286A1 US 23374602 A US23374602 A US 23374602A US 2003010286 A1 US2003010286 A1 US 2003010286A1
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- Prior art keywords
- substrate
- dispensing
- vacuum
- controller
- process area
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/67—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere
- H01L21/67005—Apparatus not specifically provided for elsewhere
- H01L21/67011—Apparatus for manufacture or treatment
- H01L21/67126—Apparatus for sealing, encapsulating, glassing, decapsulating or the like
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C39/00—Shaping by casting, i.e. introducing the moulding material into a mould or between confining surfaces without significant moulding pressure; Apparatus therefor
- B29C39/02—Shaping by casting, i.e. introducing the moulding material into a mould or between confining surfaces without significant moulding pressure; Apparatus therefor for making articles of definite length, i.e. discrete articles
- B29C39/10—Shaping by casting, i.e. introducing the moulding material into a mould or between confining surfaces without significant moulding pressure; Apparatus therefor for making articles of definite length, i.e. discrete articles incorporating preformed parts or layers, e.g. casting around inserts or for coating articles
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C39/00—Shaping by casting, i.e. introducing the moulding material into a mould or between confining surfaces without significant moulding pressure; Apparatus therefor
- B29C39/22—Component parts, details or accessories; Auxiliary operations
- B29C39/24—Feeding the material into the mould
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C39/00—Shaping by casting, i.e. introducing the moulding material into a mould or between confining surfaces without significant moulding pressure; Apparatus therefor
- B29C39/22—Component parts, details or accessories; Auxiliary operations
- B29C39/42—Casting under special conditions, e.g. vacuum
Definitions
- the present invention relates to an apparatus, process, and system for encapsulating electronic parts, and more specifically to an apparatus and process which uses changes in air pressure to force material under and around an electronic integrated circuit chip.
- a typical flip chip integrated circuit utilizes a solder ball grid array to provide electrical connections between a die of the flip chip and a substrate.
- a liquid dispensing system is used to apply an underfill encapsulant material between the die and the substrate.
- the flip chip underfill material is used to reduce mechanical and thermal stress on the electrical connections and to protect the electrical connections against atmospheric conditions.
- the underfill material provides stability and rigidity to the assembled flip chip and may also be used as a heat conductor to improve thermal performance of the flip chip.
- a dispenser system is used to dispense underfill material around the sides of the flip chip and the underfill material spreads under the flip chip and around the solder balls of the grid array via capillary action or “wicking”.
- the substrate is typically heated prior to, during, and after dispensing of the underfill material to a temperature ranging from ambient conditions to approximately 120° C. The heating of the substrate increases the capillary action causing the underfill material to flow further under the die of the flip chip.
- a final fillet of underfill material is applied around the sides of the flip chip after the wicking action has occurred.
- a drawback associated with such underfilling processes is that the underfill material may not completely fill all voids between a die and a substrate in a flip chip. For example, the underfill material can fail to fill spaces between the contacts of a die.
- one prior art dispensing system developed by Tessera of San Jose, Calif. utilizes a vacuum approach to completely underfill flip chips.
- the dispensing system including one or more flip chips that are to receive underfill material, is enclosed within an air tight chamber, and prior to the dispensing of underfill material, a vacuum pump is used to purge all air from the chamber to create a vacuum.
- the underfill material is then dispensed around all sides of the flip chips, and the chamber is returned to ambient pressure. When the chamber is returned to ambient air pressure, the underfill material is forced under the flip chips by the difference in air pressure outside the flip chips and under the flip chips.
- the present invention overcomes disadvantages of the prior art by providing a system, apparatus and process for encapsulating flip chips using dispensing systems having fixtures operating cooperatively with injection and vacuum valves to overcome drawbacks of the prior art systems.
- a dispensing system includes a controller, a vacuum source in electrical communication with the controller, the vacuum source applying a vacuum to at least a portion of the substrate in response to an instruction from the controller, and an injector in electrical communication with the controller and having a vacuum port in communication with the vacuum source, the injector comprising a valve in communication with a pressure source and a material source, the valve permitting material to be dispensed from the material source onto a substrate in accordance with an instruction from the controller.
- FIG. 1 illustrates a workpiece usable in accordance with the invention and shows the flow of encapsulating material at the workpiece in accordance with an embodiment of the invention.
- FIG. 2 is a block diagram illustration of a vacuum injection system, in accordance with one embodiment of the invention.
- FIG. 3 is flow chart representation of a vacuum injection process, in accordance with one embodiment of the present invention.
- FIG. 4 is a perspective view of a vacuum injection system, in accordance with one embodiment of the invention.
- FIG. 5 is a perspective view of the conveyorized portion of the vacuum injection system of FIG. 4.
- FIG. 6 is a side view of the conveyorized portion of FIG. 5, viewed along the AA axis.
- FIG. 7 is a side view of the conveyorized portion of FIG. 5, viewed along the BB axis.
- FIG. 8 is another side view of the conveyorized portion of FIG. 5, viewed along the BB axis, illustrating the conveyorized portion in more detail.
- FIGS. 9 A- 9 B are front and exploded views, respectively, of the injection valve of FIGS. 1 - 8 , in accordance with one embodiment of the invention.
- FIG. 10 is an exploded view of the vacuum nozzle FIGS. 1 - 8 , in accordance with one embodiment of the invention.
- vacuum does not necessarily refer only to producing a space entirely devoid of matter, but rather is intended also to encompass producing a space from which matter, especially air, has been partially or substantially removed.
- FIG. 1 illustrates a workpiece 27 , such as a substrate, having components 28 that may receive encapsulant material 24 using processes and apparatuses of the present invention.
- material 24 is shown flowing through the workpiece during an encapsulation process.
- the workpiece 27 includes a hollow area 26 , in which several components to be encapsulated, namely electronic components 28 having leads 30 , are disposed.
- the hollow area 26 of workpiece 27 in FIG. 1 can be formed between a top coverlay tape 34 disposed on the “die side” (i.e., the top of the components 24 ) and a bottom coverlay tape 32 disposed on the “contact side” (i.e., the bottom of the components 28 ).
- An injection hole 33 is formed in the top coverlay tape 34 at a first side of the hollow area 26 to permit encapsulation material 24 to be injected.
- a vacuum hole 35 is formed in the top coverlay tape 24 to permit a vacuum to be drawn on the hollow area 26 .
- FIG. 1 illustrates, the material 24 not only flows around the components 24 but also flows around the leads 30 of the components 28 , thereby helping to prevent voids in the encapsulant.
- FIG. 2 shows a block diagram of one embodiment of a vacuum injection system 10 in accordance with the invention, for dispensing media such as underfill material along the sides, underneath, and between components such as flip chip integrated circuits (not shown) disposed on a workpiece 27 or carrier (not shown).
- the vacuum injection system 10 includes a controller 12 , a vacuum source 14 having a nozzle 16 , an injector 18 having an injector valve 20 , and a trap 22 .
- the injector 18 injects underfill material 24 receiving force from a pressure source 23 .
- the vacuum nozzle 16 connects to the vacuum hole 35 on one side of the hollow area 26 in the workpiece 37 so that the vacuum source 14 to draw a vacuum on the hollow area 26 , while the injector valve 20 permits the injector 18 to inject encapsulating material 24 into the injection hole 33 .
- the vacuum applied by vacuum source 14 draws the encapsulating material 24 from the injection hole 33 towards the vacuum source 14 , so that the encapsulating material 24 can encapsulate and underfill all of the components in the hollow area 26 while substantially eliminating voids. This is explained more fully below.
- the controller 12 can be any system or processor capable of controlling the vacuum injection processes described herein.
- the controller 12 can be a programmable logic controller (PLC), a general purpose digital computer running one or more programs relating to control of the vacuum injection processes, or a proprietary processor system board.
- the controller 12 is a proprietary processor system board having a plurality of input/output (I/O) control points.
- the controller 12 can further include or access one or more daughter boards that can provide other circuit functions, such as analog I/O, high power switching, communications to peripherals, video display, and the like.
- the controller 12 is a computer having a PENTIUM microprocessor (manufactured by Intel Corporation of Santa Clara, Calif.) and storing and running a plurality of process instructions and associated software relating to control of the system 10 .
- the controller 12 can be a stand-alone computer, such as a personal computer, or can be networked to one or more other computers.
- the controller 12 stores a plurality of process “recipes” relating to encapsulating components and/or assemblies on the workpiece 27 .
- a process recipe may include all instructions and control programs necessary to encapsulate a predetermined quantity of a predetermined component disposed on a fixture having a predetermined size.
- the controller 12 can program either or both of these elements to operate in accordance with a particular process for a particular component or material.
- the controller 12 can monitor the vacuum level at the vacuum source 14 and adjust it as necessary.
- the controller 12 can control the injector 18 to inject material 24 for a predetermined time by enabling and disabling the injector valve 20 .
- the controller 12 can instruct the vacuum source 14 to apply a predetermined vacuum level (e.g., 5 inches of mercury (in./Hg)) to the workpiece 27 and to maintain this vacuum level for a predetermined time. While the vacuum level is maintained, the controller 12 directs the injector 18 to configure the injector valve 20 to inject a specific quantity (e.g., 1 cubic centimeter (cc)) of a material 24 , for example silicone encapsulant, from a particular source of material 24 , such as a particular cartridge or syringe of material 24 .
- a predetermined vacuum level e.g., 5 inches of mercury (in./Hg)
- the controller 12 directs the injector 18 to configure the injector valve 20 to inject a specific quantity (e.g., 1 cubic centimeter (cc)) of a material 24 , for example silicone encapsulant, from a particular source of material 24 , such as a particular cartridge or syringe of material 24 .
- Vacuum source 14 can be a pump, such as an oil-free vacuum pump, capable of reaching a predetermined vacuum level within a predetermined time.
- the vacuum pump is a diaphragm-style pump manufactured by Varian Associates of Lexington Md.
- the vacuum source 14 can reach a maximum vacuum of 28 in./Hg within 5 seconds.
- the vacuum level and time during which vacuum is applied can be set; for example, they can be programmed by controller 12 or set manually using one or more switches.
- the vacuum source 14 can apply a vacuum at its nozzle 16 to the hollow area 26 before, during, and/or after injection of the material 24 .
- the vacuum source 24 to “draw” injected material 24 through the hollow area 26 after the material 24 has been injected, thereby encapsulating components therein without voids.
- the material 24 can be drawn through the hollow area 26 faster than the material 24 flows without the vacuum being applied.
- the trap 22 is disposed between the vacuum source 14 and the vacuum nozzle 16 to trap possible excess material 24 injected into the hollow area 26 of the workpiece 27 , to prevent contamination of the vacuum source 14 .
- the trap 22 can be a jar having a removable reservoir, so that material 24 in the trap 22 can be removed easily.
- the trap 22 includes a disposable and easily removed reservoir. Many different types and styles of reservoir-type devices are usable in accordance with this aspect of the invention, as those skilled in the art will recognize.
- the trap 22 can include a level sensor (not shown) capable of detecting the level of material 24 in the trap 22 .
- the level sensor can stop the injection process if the material 24 in the trap 22 reaches a predetermined level, such as if the trap 22 becomes three quarters full.
- the controller 12 can monitor the level of material 24 and stop the injection process if the material 24 in the trap 22 reaches a predetermined level.
- the vacuum source 14 is coupled to a vacuum nozzle 16 adapted to fit tightly to the vacuum hole 35 on the workpiece 27 .
- the injector 18 can accommodate workpieces 27 and/or hollow areas having differing sizes.
- the injector 18 can include an injection port 21 that fits tightly to (or within) the injection hole 33 on the workpiece 27 to inject material 24 into the hollow area 26 after the vacuum source 14 has evacuated air from the hollow area 26 .
- the injector 18 can begin injecting material 24 into the hollow area 26 while the vacuum source 14 is evacuating air from the hollow area 26 .
- a pressure source 23 such as a cartridge assembly manufactured by EFD Inc. of Buffalo, R.I., uses pressure to force the material 24 out of the injection port 21 and into the hollow area 26 .
- the material 24 is stored in a cartridge or syringe and pressure is applied to the cartridge to force material 24 from the cartridge out through the injection port 21 .
- the pressure source 23 can be an air-driven or mechanical ram.
- the injector 18 provides a positive shut-off, which can help to prevent material 24 from dripping out of the injection port 21 after pressure on the material 24 is released or after injection of a predetermined quantity of material 24 is complete.
- the positive shut-off is provided using a valve 20 that is precisely controlled by controller 12 . This aspect is described more fully below.
- the injector 18 can include one or more ports (not shown) accepting syringes and/or cartridges containing material 24 to be injected.
- the injector 18 can be supplied with material 24 from a bulk feeding device such as a ram pail pump, such as the DynaMite 190 manufactured by Graco, Inc. of Minneapolis Minn.
- the controller 12 can communicate with the injector valve 20 to control operation of the injector 18 , when injection occurs, to control the level of pressure applied at the pressure source 23 , to release the pressure on the pressure source 23 , to select the source of material 24 , and to control the flow of material 24 into the injector 18 .
- the material 24 can be any material used for encapsulating articles.
- some materials such as silicone chip encapsulant material, can be used as a compliant layer to decouple the mismatched thermal expansion rates of silicon and common printed circuit board (PCB) laminates (to which a silicon electronic component being encapsulated may later be attached).
- Silicone chip encapsulant material can also increase the solvent resistance of the article being encapsulated.
- the workpiece 27 , integrated circuits or other substrates that are to receive dispensing material in the system 10 can be transported as individual units on conveyors, multiple units in a common carrier, or using a continuous tape feeder system.
- the workpiece 27 can, in one embodiment, include such individual units, multiple units on a common carrier, or a continuous tape feeder system.
- the system 10 may include a conveyor (not shown in FIG. 1, but illustrated in FIGS. 4 - 8 ) for loading and unloading integrated circuits or multiple unit common carriers into the dispensing system.
- the system 10 may be configured as known in the art for receiving a continuous tape having integrated circuits that are to receive encapsulant material bonded to the top surface of the tape.
- FIG. 3 illustrates a flow chart of a process for encapsulating components using the system 10 of FIG. 1, in accordance with an embodiment of the invention.
- the chip or component 28 is aligned on the workpiece 27 or carrier and is sealed, such as by the top and bottom coverlay tapes 34 , 32 of FIG. 2 (step 40 ).
- the carrier or workpiece 27 at an injection point in the system 10 is positioned on a conveyor (step 42 ).
- the vacuum and encapsulation holes 35 , 33 also referred to as vacuum input and injection input, respectively
- the vacuum source 14 draws a vacuum at a first side of the workpiece 27 (step 46 ) to evacuate air from the hollow area 26 containing the components 28 to be encapsulated while simultaneously drawing encapsulant material 24 through the hollow area 26 .
- the workpiece 27 may be lifted off of the conveyor to place the vacuum and injection ports 35 , 33 in contact with the vacuum nozzle 16 and a nozzle at the injector 18 .
- the injector valve 20 opens to begin dispensing material 24 into the hollow area 24 (step 48 ). Because the material 24 is at a pressure higher than that in the hollow area 26 , the material 24 , after being injected from the injector valve 20 is drawn through the hollow area 26 , towards the vacuum hole 35 . In addition, because the vacuum source 14 is applying a vacuum to the hollow area 26 , the material 24 will flow through the hollow area 26 faster than if the hollow area 26 were evacuated then the vacuum was removed.
- the controller 12 determines how long the vacuum source 14 applies the vacuum and how long the injector 18 can inject material based on a number of factors, which can include the size of the hollow area 26 , the number of components 28 , the type of material 24 , the level of the vacuum being applied, and the amount of material in the trap 22 . Those skilled in the art will recognize that other factors may affect the time for encapsulation.
- the injection valve 20 is closed at a predetermined time to stop the injection of material 24 into the hollow area 26 (step 50 ), and the vacuum is released at a predetermined time. Any excess material 24 that flows out of the vacuum hole 35 flows into the trap 22 and is contained in the trap 22 , instead of contaminating the vacuum source 14 (step 52 ). Then, the injector 18 and vacuum source 14 are be removed from the injection and vacuum holes 33 , 35 (step 54 ), and the next encapsulation step (such as curing of the encapsulant) can proceed.
- a number of factors can include the size of the hollow area 26 , the number
- the automated system 100 includes encapsulation assemblies 102 , a conveyor 104 , and a display and control panel 106 .
- the panel 106 includes various indicators and switches permitting operators to monitor or control at least a portion of the encapsulation process being run at the system 100 .
- the panel 106 can include indicators informing an operator the status of the trap 22 (e.g., empty, quarter-full, three quarters full, etc.) or that the trap 22 must be emptied to avoid a shutdown of the system 100 .
- control electronics for the vacuum encapsulation process such as a controller 12 , power circuitry (not shown), air sources (not shown), control pneumatics for the injectors 18 and other devices, cooling fans, and the like.
- the control electronics includes a controller 12 having a microprocessor such as a PENTIUM processor, which can be programmed to control the dispensing system, to control the flow of workpieces 27 such as integrated circuits into and out of the dispensing system, and to operate some or all of the other control electronics.
- the conveyor 104 of the encapsulation system 100 flows from left to right and is manually adjustable to accommodate parts of varying widths.
- the conveyor 104 can be adjusted from 50 mm to 180 mm between its rails 104 ′, 104 ′′.
- a plurality of sensors are operable with the conveyor 104 to sense when a workpiece 27 (FIG. 1) has been placed at the entrance end (left side) of the conveyor 104 and to sense when a workpiece 27 has reached an injector assembly 102 .
- the conveyor 104 is made from materials that are safe from electrostatic discharge (ESD).
- Each injector assembly 102 includes a material assembly 108 dispensing material 24 used for encapsulation.
- the material assembly 108 accepts 80 cc syringes and 150 cc cartridges as reservoirs for material 24 .
- the locations of the material assemblies 108 ensure that they can be easily accessed and maintained by operators of the system. If the system 100 is running in a continuous high volume environment, however, the materials assembly 108 can be coupled to a bulk material feeding device to avoid frequent replenishment of material 24 while running.
- a pneumatic assembly 109 helps to lifts the workpiece 27 off of the conveyor 104 and towards the injector assembly 102 (this is shown in greater detail in FIG. 8).
- the workpiece 27 is disposed to contact its injection hole 33 and vacuum hole 35 with a nozzle of the injector valve 20 (not shown in FIG. 5) of the injector 18 , and the vacuum nozzle 16 coupled to the vacuum source 14 (not shown in FIG. 5), respectively.
- FIG. 6 illustrates a side view of an injector assembly 102 of FIG. 5 taken along the AA line. This view illustrates the relative physical locations of the injector valve 20 and the pneumatic assembly 109 to the conveyor 104 .
- FIG. 7 illustrates another side view of the injector assemblies 102 of FIG. 5 taken along the B-B line.
- alignment pins are 110 , 112 are shown projecting from a top fixture element 114 in the injector assembly 102 .
- the alignment pins 110 , 112 mate with corresponding alignment holes in the workpiece 27 , to ensure that the vacuum nozzle 16 and the injector 18 can make proper contact with the injection hole 35 and the vacuum hole 33 .
- the alignment holes in the workpiece 27 are not illustrated, those skilled in the art will recognize that conventional alignment pins and alignment holes can be used to align the workpiece 27 .
- FIG. 8 illustrates still another side view of the injector assemblies 102 of FIG. 5 taken along the B-B line.
- the injector nozzle 20 and the vacuum nozzle 18 pass through the top fixture element 114 , from which alignment pins 110 , 112 project.
- the workpiece 27 is disposed on a movable bottom fixture element 116 , which has been raised a predetermined distance above the conveyor 104 , to bring the workpiece 27 towards the injector nozzle 20 and vacuum nozzle 18 at the top fixture element 114 .
- the alignment pins 110 , 112 are engageable with corresponding alignment holes in the workpiece 27 and in the bottom fixture element 112 , to hold the workpiece 27 and the top and bottom fixture elements 114 , 116 at a predetermined alignment.
- the top face of the bottom fixture element 116 is urged towards the bottom face of the top fixture element 114 , until the injector nozzle 20 and vacuum nozzle 16 engage the injection hole 33 and vacuum hole 35 of the workpiece 27 .
- the top fixture element 114 may be in contact with the bottom fixture element 116 when the vacuum nozzle 16 and injector nozzle 20 are in proper engagement with the vacuum hole 35 and injector hole 33 .
- FIGS. 6 - 8 illustrate that the bottom fixture element 116 has alignment holes and the top fixture element 113 has alignment pins 110 , 112 , those skilled in the art will recognize that the top fixture element 114 could instead have the alignment holes and the bottom fixture element 116 could have the alignment pins.
- FIGS. 6 - 8 illustrate that the bottom fixture element 116 is lifted vertically above the conveyor 104 towards the top fixture element 114 , it is possible to instead move the top fixture element 114 towards the bottom fixture element 116 , or to move both the top fixture element 114 and the bottom fixture element 116 towards each other.
- fixture element that contacts that contacts the workpiece 27 surface can be adjustable to compensate for variations in the thickness of the workpiece 27 or die thickness. This compensation allows proper clamping and fixturing of the components being processed due to lot variations.
- FIGS. 9 A- 9 B illustrate an example of an injector valve 20 usable in accordance with an embodiment of the invention.
- the injector valve 20 includes a stroke cylinder 66 , stopper rod assembly 60 , and nozzle assembly 82 , along with various fitting and hardware components, which operate together to provide a positive shut-off function that the controller 12 (FIG. 2) can control with precision.
- controller 12 FIG. 2
- the nozzle assembly 82 includes a flexible nozzle tip 83 that forms a tight seal to the injection hole 33 of a workpiece 27 (FIGS. 1 and 2).
- the nozzle tip 83 is “doughnut” shaped and has an opening in the center therein through which material 24 to be injected can flow and which can receive the rod tip 61 of a stopper rod assembly 60 (described more fully below) to block the hole in the nozzle tip 83 and prevent material 24 from escaping.
- the nozzle assembly 82 is coupled to a first end of an upper body assembly 78 to which a nipple assembly 76 attaches.
- the nipple assembly 76 couples to a source of material 24 , such as the material assembly 108 (FIGS. 4 - 7 ), for receiving material to be injected.
- An O-ring 80 helps to form a tight seal between the nozzle assembly 82 and the upper body assembly 78 .
- a piston seal 74 couples the second end of the upper body 78 to a first side of a bushing assembly 70 via a first retainer nut 72 .
- a second retainer nut 68 couples the second side of the bushing assembly 70 to a stroke cylinder 66 and a stopper rod assembly 60 .
- the stroke cylinder 66 is coupled via a length of tubing 62 and first, second, and third fittings 56 , 58 , 64 , to a pressure source 23 (FIG. 2).
- the stroke cylinder 66 can be an SMC Cylinder manufactured by Kinequip Inc., Buffalo, N.Y., such as Model. No. NCJ2B16-050T. This model can operate with a maximum pressure of 100 pounds per square inch (PSI), and those skilled in the art will recognize that other stroke cylinders having comparable specifications can be used in accordance with the invention.
- PSI pounds per square inch
- the stopper rod assembly 60 is movably coupled to the stroke cylinder 66 , such as by spring loading.
- pressure from a pressure source 23 (FIG. 1) can be applied and removed from the stroke cylinder 66 .
- the pressure compresses the spring biasing within the stroke cylinder 66 , thereby holding the stopper rod assembly 60 back from the nozzle tip 83 .
- the stopper rod assembly 60 is disposed within the upper body 78 and nozzle assembly 82 to permit material 24 to flow through the nozzle tip 83 of the nozzle assembly 82 , through an injection hole 33 (FIG. 1) and into the hollow area 26 of a workpiece 27 (FIG. 1).
- FIG. 10 illustrates an example of a vacuum nozzle 16 usable in accordance with an embodiment of the invention.
- a nozzle body 88 has a seal 86 at one end and a fitting 90 at the other end.
- the fitting 90 and seal 86 are structured and arranged to be operable with the vacuum source 14 (FIG. 1) and to be coupled closely to the vacuum hole 35 .
- the types of vacuum nozzles that may be usable in accordance with the invention.
- the present invention provides improved systems, methods, and apparatuses for encapsulation of articles such as electronic components.
- the controller and injector valve precisely control the flow of encapsulant into the workpiece, which ensures that a proper quantity of encapsulant is applied to the articles, improves the yield of the encapsulation process, and decreases waste of encapsulant.
- Having the controller control operation of the vacuum source provides precise control of the vacuum being applied to the workpiece. This permits the time and magnitude of the applied vacuum to vary based on the encapsulant used and the number and size of articles to be encapsulated.
- a vacuum source applying a vacuum directly to the area containing articles to be encapsulated provides advantages over the prior art.
- First, applying a vacuum only to that area helps to reduce the size of the vacuum source required, thereby reducing the size of the dispensing system overall.
- Second, applying a vacuum to the area in which encapsulant is being injected at the same time that the encapsulant is being injected speeds the flow of encapsulant through the workpiece and helps ensure that the encapsulant thoroughly contacts all the articles to be encapsulated.
- use of a trap in connection with the vacuum source helps prevent encapsulant being drawn through the workpiece from contaminating the vacuum source or other areas outside of the workpiece.
Abstract
Description
- This application is related to U.S. Utility application Ser. No. 09/168,536, filed Oct. 10, 1998, which is incorporated by reference herein.
- The present invention relates to an apparatus, process, and system for encapsulating electronic parts, and more specifically to an apparatus and process which uses changes in air pressure to force material under and around an electronic integrated circuit chip.
- The need for denser, larger and more durable chip assemblies has broadened the use of Direct Chip Attach (DCA) technology to include flip chip integrated circuits. A typical flip chip integrated circuit utilizes a solder ball grid array to provide electrical connections between a die of the flip chip and a substrate. During manufacturing of a typical flip chip, after the flip chip is assembled on a substrate, a liquid dispensing system is used to apply an underfill encapsulant material between the die and the substrate. The flip chip underfill material is used to reduce mechanical and thermal stress on the electrical connections and to protect the electrical connections against atmospheric conditions. The underfill material provides stability and rigidity to the assembled flip chip and may also be used as a heat conductor to improve thermal performance of the flip chip.
- In typical prior art flip chip underfilling processes, a dispenser system is used to dispense underfill material around the sides of the flip chip and the underfill material spreads under the flip chip and around the solder balls of the grid array via capillary action or “wicking”. During the assembly process, the substrate is typically heated prior to, during, and after dispensing of the underfill material to a temperature ranging from ambient conditions to approximately 120° C. The heating of the substrate increases the capillary action causing the underfill material to flow further under the die of the flip chip. A final fillet of underfill material is applied around the sides of the flip chip after the wicking action has occurred. A drawback associated with such underfilling processes is that the underfill material may not completely fill all voids between a die and a substrate in a flip chip. For example, the underfill material can fail to fill spaces between the contacts of a die.
- To overcome the problem of voids or air gaps, one prior art dispensing system developed by Tessera of San Jose, Calif. utilizes a vacuum approach to completely underfill flip chips. In this prior art system, the dispensing system, including one or more flip chips that are to receive underfill material, is enclosed within an air tight chamber, and prior to the dispensing of underfill material, a vacuum pump is used to purge all air from the chamber to create a vacuum. The underfill material is then dispensed around all sides of the flip chips, and the chamber is returned to ambient pressure. When the chamber is returned to ambient air pressure, the underfill material is forced under the flip chips by the difference in air pressure outside the flip chips and under the flip chips.
- While the above described prior art system is effective in preventing voids in underfill material in flip chips, the system is relatively large and the time required to purge air from the air tight chamber is rather long. Further, because the airtight chamber is so large, it is difficult to effectively purge air from the chamber. In addition, the air tight chamber of the prior art accommodates only manual loading of the flip chips into the chamber, preventing the dispensing system contained within the chamber from being effectively used in an automated assembly line. Moreover, the large size of the airtight chamber often precludes it from easy integration into automated manufacturing processes.
- The present invention overcomes disadvantages of the prior art by providing a system, apparatus and process for encapsulating flip chips using dispensing systems having fixtures operating cooperatively with injection and vacuum valves to overcome drawbacks of the prior art systems.
- In one embodiment, a dispensing system includes a controller, a vacuum source in electrical communication with the controller, the vacuum source applying a vacuum to at least a portion of the substrate in response to an instruction from the controller, and an injector in electrical communication with the controller and having a vacuum port in communication with the vacuum source, the injector comprising a valve in communication with a pressure source and a material source, the valve permitting material to be dispensed from the material source onto a substrate in accordance with an instruction from the controller.
- For a better understanding of the present invention, reference is made to the drawings, which are incorporated herein by reference, and in which:
- FIG. 1 illustrates a workpiece usable in accordance with the invention and shows the flow of encapsulating material at the workpiece in accordance with an embodiment of the invention.
- FIG. 2 is a block diagram illustration of a vacuum injection system, in accordance with one embodiment of the invention.
- FIG. 3 is flow chart representation of a vacuum injection process, in accordance with one embodiment of the present invention.
- FIG. 4 is a perspective view of a vacuum injection system, in accordance with one embodiment of the invention.
- FIG. 5 is a perspective view of the conveyorized portion of the vacuum injection system of FIG. 4.
- FIG. 6 is a side view of the conveyorized portion of FIG. 5, viewed along the AA axis.
- FIG. 7 is a side view of the conveyorized portion of FIG. 5, viewed along the BB axis.
- FIG. 8 is another side view of the conveyorized portion of FIG. 5, viewed along the BB axis, illustrating the conveyorized portion in more detail.
- FIGS.9A-9B are front and exploded views, respectively, of the injection valve of FIGS. 1-8, in accordance with one embodiment of the invention.
- FIG. 10 is an exploded view of the vacuum nozzle FIGS.1-8, in accordance with one embodiment of the invention.
- For purposes of illustration, embodiments of the present invention will now be described with reference to a dispensing system used to dispense underfill material beneath and around electronic components such as flip chip integrated circuits. One skilled in the art will appreciate, however, that embodiments of the present invention are not limited to dispensing underfill materials for flip chip integrated circuits, but may be used in other applications.
- As used in this description, the term “vacuum” does not necessarily refer only to producing a space entirely devoid of matter, but rather is intended also to encompass producing a space from which matter, especially air, has been partially or substantially removed.
- One technique for encapsulating electronic components is described in an application filed under the Patent Cooperation Treaty (PCT) having Publication Number WO 99/53616, the contents of which are incorporated herein by reference. In the described method, electronic components are disposed in an assembly having top and bottom sealing layers defining an enclosed space containing the components. The assembly is engaged in a test fixture, and the enclosed space is evacuated by applying a vacuum to a hole in one of the sealing layers. Then, the vacuum is removed from the hole, a needle is advanced into that hole, and a liquid encapsulant is injected through the needle into the enclosed space around the electronic components. The encapsulant flows into the enclosed space, where it is free to flow around the components.
- One disadvantage of this method, however, is that the vacuum and encapsulant flowing through the needle must be precisely controlled to ensure proper flow. Another disadvantage is that the injected liquid encapsulant may not flow sufficiently around and under all of the components to properly encapsulate each component. Still another disadvantage is that excess encapsulant can flow back out of the hole and contaminate the assembly, text fixture, vacuum, or other elements. Yet another disadvantage is that waiting for the liquid encapsulant to flow around each component increases the process time for encapsulating the components.
- FIG. 1 illustrates a
workpiece 27, such as a substrate, havingcomponents 28 that may receiveencapsulant material 24 using processes and apparatuses of the present invention. In FIG. 1,material 24 is shown flowing through the workpiece during an encapsulation process. Theworkpiece 27 includes ahollow area 26, in which several components to be encapsulated, namelyelectronic components 28 having leads 30, are disposed. Thehollow area 26 ofworkpiece 27 in FIG. 1 can be formed between atop coverlay tape 34 disposed on the “die side” (i.e., the top of the components 24) and abottom coverlay tape 32 disposed on the “contact side” (i.e., the bottom of the components 28). Aninjection hole 33 is formed in thetop coverlay tape 34 at a first side of thehollow area 26 to permitencapsulation material 24 to be injected. Similarly, avacuum hole 35 is formed in thetop coverlay tape 24 to permit a vacuum to be drawn on thehollow area 26. Having theinjection hole 33 andvacuum hole 35 as separate holes, disposed on opposite sides of thehollow area 26, is advantageous because the vacuum being pulled at thevacuum hole 35 helps to rapidly draw thematerial 24 through thehollow area 26 and around thecomponents 28 and also helps to ensure that thematerial 24 flows around, over, and under all of thecomponents 28. - It should be understood that illustration of three
electronic components 28 is not intended to be limiting; any number of components can be disposed in thehollow area 26. Further, the articles disposed in thehollow area 26 need not be electronic or other types of components, but rather can include any articles to be encapsulated. As FIG. 1 illustrates, thematerial 24 not only flows around thecomponents 24 but also flows around theleads 30 of thecomponents 28, thereby helping to prevent voids in the encapsulant. - FIG. 2 shows a block diagram of one embodiment of a
vacuum injection system 10 in accordance with the invention, for dispensing media such as underfill material along the sides, underneath, and between components such as flip chip integrated circuits (not shown) disposed on aworkpiece 27 or carrier (not shown). Thevacuum injection system 10 includes acontroller 12, avacuum source 14 having anozzle 16, aninjector 18 having aninjector valve 20, and atrap 22. Theinjector 18 injectsunderfill material 24 receiving force from apressure source 23. During operation of thevacuum injection system 10, thevacuum nozzle 16 connects to thevacuum hole 35 on one side of thehollow area 26 in the workpiece 37 so that thevacuum source 14 to draw a vacuum on thehollow area 26, while theinjector valve 20 permits theinjector 18 to inject encapsulatingmaterial 24 into theinjection hole 33. The vacuum applied byvacuum source 14 draws the encapsulatingmaterial 24 from theinjection hole 33 towards thevacuum source 14, so that the encapsulatingmaterial 24 can encapsulate and underfill all of the components in thehollow area 26 while substantially eliminating voids. This is explained more fully below. - The
controller 12 can be any system or processor capable of controlling the vacuum injection processes described herein. For example, thecontroller 12 can be a programmable logic controller (PLC), a general purpose digital computer running one or more programs relating to control of the vacuum injection processes, or a proprietary processor system board. In one embodiment, thecontroller 12 is a proprietary processor system board having a plurality of input/output (I/O) control points. In another embodiment, thecontroller 12 can further include or access one or more daughter boards that can provide other circuit functions, such as analog I/O, high power switching, communications to peripherals, video display, and the like. In still another embodiment, thecontroller 12 is a computer having a PENTIUM microprocessor (manufactured by Intel Corporation of Santa Clara, Calif.) and storing and running a plurality of process instructions and associated software relating to control of thesystem 10. Thecontroller 12 can be a stand-alone computer, such as a personal computer, or can be networked to one or more other computers. - In one embodiment, the
controller 12 stores a plurality of process “recipes” relating to encapsulating components and/or assemblies on theworkpiece 27. For example, a process recipe may include all instructions and control programs necessary to encapsulate a predetermined quantity of a predetermined component disposed on a fixture having a predetermined size. Because thecontroller 12 is in communication with theinjector 18 and thevacuum source 14, it can program either or both of these elements to operate in accordance with a particular process for a particular component or material. In another embodiment, thecontroller 12 can monitor the vacuum level at thevacuum source 14 and adjust it as necessary. In another example, thecontroller 12 can control theinjector 18 to injectmaterial 24 for a predetermined time by enabling and disabling theinjector valve 20. - For example, the
controller 12 can instruct thevacuum source 14 to apply a predetermined vacuum level (e.g., 5 inches of mercury (in./Hg)) to theworkpiece 27 and to maintain this vacuum level for a predetermined time. While the vacuum level is maintained, thecontroller 12 directs theinjector 18 to configure theinjector valve 20 to inject a specific quantity (e.g., 1 cubic centimeter (cc)) of amaterial 24, for example silicone encapsulant, from a particular source ofmaterial 24, such as a particular cartridge or syringe ofmaterial 24. - Vacuum
source 14 can be a pump, such as an oil-free vacuum pump, capable of reaching a predetermined vacuum level within a predetermined time. In one embodiment, the vacuum pump is a diaphragm-style pump manufactured by Varian Associates of Lexington Md. For example, in one embodiment, thevacuum source 14 can reach a maximum vacuum of 28 in./Hg within 5 seconds. The vacuum level and time during which vacuum is applied can be set; for example, they can be programmed bycontroller 12 or set manually using one or more switches. Depending on how it is programmed, thevacuum source 14 can apply a vacuum at itsnozzle 16 to thehollow area 26 before, during, and/or after injection of thematerial 24. This permits thevacuum source 24 to “draw” injectedmaterial 24 through thehollow area 26 after thematerial 24 has been injected, thereby encapsulating components therein without voids. In addition, by continuing to apply a vacuum to thehollow area 26 after injection of thematerial 24, thematerial 24 can be drawn through thehollow area 26 faster than the material 24 flows without the vacuum being applied. - The
trap 22 is disposed between thevacuum source 14 and thevacuum nozzle 16 to trap possibleexcess material 24 injected into thehollow area 26 of theworkpiece 27, to prevent contamination of thevacuum source 14. For example, thetrap 22 can be a jar having a removable reservoir, so thatmaterial 24 in thetrap 22 can be removed easily. In one embodiment, thetrap 22 includes a disposable and easily removed reservoir. Many different types and styles of reservoir-type devices are usable in accordance with this aspect of the invention, as those skilled in the art will recognize. - In one embodiment, the
trap 22 can include a level sensor (not shown) capable of detecting the level ofmaterial 24 in thetrap 22. Those skilled in the art will recognize that many different types of sensing devices are usable to detect the level ofmaterial 24 in thetrap 22. The level sensor can stop the injection process if the material 24 in thetrap 22 reaches a predetermined level, such as if thetrap 22 becomes three quarters full. Alternately, thecontroller 12 can monitor the level ofmaterial 24 and stop the injection process if the material 24 in thetrap 22 reaches a predetermined level. Thevacuum source 14 is coupled to avacuum nozzle 16 adapted to fit tightly to thevacuum hole 35 on theworkpiece 27. - The
injector 18 can accommodateworkpieces 27 and/or hollow areas having differing sizes. Theinjector 18 can include aninjection port 21 that fits tightly to (or within) theinjection hole 33 on theworkpiece 27 to injectmaterial 24 into thehollow area 26 after thevacuum source 14 has evacuated air from thehollow area 26. In another embodiment, theinjector 18 can begin injectingmaterial 24 into thehollow area 26 while thevacuum source 14 is evacuating air from thehollow area 26. Apressure source 23, such as a cartridge assembly manufactured by EFD Inc. of Providence, R.I., uses pressure to force the material 24 out of theinjection port 21 and into thehollow area 26. In one example, thematerial 24 is stored in a cartridge or syringe and pressure is applied to the cartridge to forcematerial 24 from the cartridge out through theinjection port 21. In one embodiment, thepressure source 23 can be an air-driven or mechanical ram. - The
injector 18 provides a positive shut-off, which can help to prevent material 24 from dripping out of theinjection port 21 after pressure on thematerial 24 is released or after injection of a predetermined quantity ofmaterial 24 is complete. In one embodiment, the positive shut-off is provided using avalve 20 that is precisely controlled bycontroller 12. This aspect is described more fully below. In another embodiment, theinjector 18 can include one or more ports (not shown) accepting syringes and/orcartridges containing material 24 to be injected. In still another embodiment, theinjector 18 can be supplied withmaterial 24 from a bulk feeding device such as a ram pail pump, such as the DynaMite 190 manufactured by Graco, Inc. of Minneapolis Minn. Thecontroller 12 can communicate with theinjector valve 20 to control operation of theinjector 18, when injection occurs, to control the level of pressure applied at thepressure source 23, to release the pressure on thepressure source 23, to select the source ofmaterial 24, and to control the flow ofmaterial 24 into theinjector 18. - The
material 24 can be any material used for encapsulating articles. For example, some materials, such as silicone chip encapsulant material, can be used as a compliant layer to decouple the mismatched thermal expansion rates of silicon and common printed circuit board (PCB) laminates (to which a silicon electronic component being encapsulated may later be attached). Silicone chip encapsulant material can also increase the solvent resistance of the article being encapsulated. - The
workpiece 27, integrated circuits or other substrates that are to receive dispensing material in thesystem 10 can be transported as individual units on conveyors, multiple units in a common carrier, or using a continuous tape feeder system. Theworkpiece 27 can, in one embodiment, include such individual units, multiple units on a common carrier, or a continuous tape feeder system. Thesystem 10 may include a conveyor (not shown in FIG. 1, but illustrated in FIGS. 4-8) for loading and unloading integrated circuits or multiple unit common carriers into the dispensing system. Alternatively, thesystem 10 may be configured as known in the art for receiving a continuous tape having integrated circuits that are to receive encapsulant material bonded to the top surface of the tape. - FIG. 3 illustrates a flow chart of a process for encapsulating components using the
system 10 of FIG. 1, in accordance with an embodiment of the invention. In a first step of the process, the chip orcomponent 28 is aligned on theworkpiece 27 or carrier and is sealed, such as by the top andbottom coverlay tapes workpiece 27 at an injection point in thesystem 10 is positioned on a conveyor (step 42). The vacuum and encapsulation holes 35, 33 (also referred to as vacuum input and injection input, respectively) are contacted by the vacuum and injection ports (step 44). Thevacuum source 14 draws a vacuum at a first side of the workpiece 27 (step 46) to evacuate air from thehollow area 26 containing thecomponents 28 to be encapsulated while simultaneously drawingencapsulant material 24 through thehollow area 26. In one embodiment, prior to step 44 theworkpiece 27 may be lifted off of the conveyor to place the vacuum andinjection ports vacuum nozzle 16 and a nozzle at theinjector 18. - After the
vacuum source 14 begins applying the vacuum, theinjector valve 20 opens to begin dispensingmaterial 24 into the hollow area 24 (step 48). Because thematerial 24 is at a pressure higher than that in thehollow area 26, thematerial 24, after being injected from theinjector valve 20 is drawn through thehollow area 26, towards thevacuum hole 35. In addition, because thevacuum source 14 is applying a vacuum to thehollow area 26, thematerial 24 will flow through thehollow area 26 faster than if thehollow area 26 were evacuated then the vacuum was removed. Thecontroller 12 determines how long thevacuum source 14 applies the vacuum and how long theinjector 18 can inject material based on a number of factors, which can include the size of thehollow area 26, the number ofcomponents 28, the type ofmaterial 24, the level of the vacuum being applied, and the amount of material in thetrap 22. Those skilled in the art will recognize that other factors may affect the time for encapsulation. Based on information from thecontroller 12, theinjection valve 20 is closed at a predetermined time to stop the injection ofmaterial 24 into the hollow area 26 (step 50), and the vacuum is released at a predetermined time. Anyexcess material 24 that flows out of thevacuum hole 35 flows into thetrap 22 and is contained in thetrap 22, instead of contaminating the vacuum source 14 (step 52). Then, theinjector 18 andvacuum source 14 are be removed from the injection and vacuum holes 33, 35 (step 54), and the next encapsulation step (such as curing of the encapsulant) can proceed. - Note, however, that other events can cause the injection valve20 (and/or the vacuum valve 16) to stop the encapsulation process from continuing. For example, if a sensor in the
trap 22 indicates that the material 24 in thetrap 22 reaches a predetermined level, the sensor in thetrap 22 can either disable thevacuum source 14, or close theinjector valve 20, to stop the vacuum from drawingmaterial 24 through thehollow area 26. It should also be understood that the order ofsteps injection valve 20 is shut. - An embodiment of an automated
vacuum encapsulation system 100 in accordance with the present invention will now be described with reference to FIGS. 1 and 4-9. Theautomated system 100 includesencapsulation assemblies 102, aconveyor 104, and a display andcontrol panel 106. Thepanel 106 includes various indicators and switches permitting operators to monitor or control at least a portion of the encapsulation process being run at thesystem 100. For example, if theencapsulation system 100 included a trap 22 (FIG. 1), thepanel 106 can include indicators informing an operator the status of the trap 22 (e.g., empty, quarter-full, three quarters full, etc.) or that thetrap 22 must be emptied to avoid a shutdown of thesystem 100. - Also contained within the
system 100 are control electronics for the vacuum encapsulation process, such as acontroller 12, power circuitry (not shown), air sources (not shown), control pneumatics for theinjectors 18 and other devices, cooling fans, and the like. In one embodiment, the control electronics includes acontroller 12 having a microprocessor such as a PENTIUM processor, which can be programmed to control the dispensing system, to control the flow ofworkpieces 27 such as integrated circuits into and out of the dispensing system, and to operate some or all of the other control electronics. - The
conveyor 104 of theencapsulation system 100 flows from left to right and is manually adjustable to accommodate parts of varying widths. For example, in this embodiment, theconveyor 104 can be adjusted from 50 mm to 180 mm between itsrails 104′, 104″. A plurality of sensors (not shown) are operable with theconveyor 104 to sense when a workpiece 27 (FIG. 1) has been placed at the entrance end (left side) of theconveyor 104 and to sense when aworkpiece 27 has reached aninjector assembly 102. Theconveyor 104 is made from materials that are safe from electrostatic discharge (ESD). - Referring to FIG. 5, the
injector assemblies 102 are illustrated in greater detail. Eachinjector assembly 102 includes amaterial assembly 108 dispensingmaterial 24 used for encapsulation. For example, thematerial assembly 108 accepts 80 cc syringes and 150 cc cartridges as reservoirs formaterial 24. The locations of thematerial assemblies 108 ensure that they can be easily accessed and maintained by operators of the system. If thesystem 100 is running in a continuous high volume environment, however, thematerials assembly 108 can be coupled to a bulk material feeding device to avoid frequent replenishment ofmaterial 24 while running. - As
workpieces 27 move along theconveyor 104, when theworkpiece 27 reaches theinjector assembly 102, apneumatic assembly 109 helps to lifts theworkpiece 27 off of theconveyor 104 and towards the injector assembly 102 (this is shown in greater detail in FIG. 8). When lifted, theworkpiece 27 is disposed to contact itsinjection hole 33 andvacuum hole 35 with a nozzle of the injector valve 20 (not shown in FIG. 5) of theinjector 18, and thevacuum nozzle 16 coupled to the vacuum source 14 (not shown in FIG. 5), respectively. - FIG. 6 illustrates a side view of an
injector assembly 102 of FIG. 5 taken along the AA line. This view illustrates the relative physical locations of theinjector valve 20 and thepneumatic assembly 109 to theconveyor 104. - FIG. 7 illustrates another side view of the
injector assemblies 102 of FIG. 5 taken along the B-B line. In this view, alignment pins are 110, 112 are shown projecting from atop fixture element 114 in theinjector assembly 102. The alignment pins 110, 112 mate with corresponding alignment holes in theworkpiece 27, to ensure that thevacuum nozzle 16 and theinjector 18 can make proper contact with theinjection hole 35 and thevacuum hole 33. Although the alignment holes in theworkpiece 27 are not illustrated, those skilled in the art will recognize that conventional alignment pins and alignment holes can be used to align theworkpiece 27. - FIG. 8 illustrates still another side view of the
injector assemblies 102 of FIG. 5 taken along the B-B line. In this view, theinjector nozzle 20 and thevacuum nozzle 18 pass through thetop fixture element 114, from which alignment pins 110, 112 project. Theworkpiece 27 is disposed on a movablebottom fixture element 116, which has been raised a predetermined distance above theconveyor 104, to bring theworkpiece 27 towards theinjector nozzle 20 andvacuum nozzle 18 at thetop fixture element 114. The alignment pins 110, 112 are engageable with corresponding alignment holes in theworkpiece 27 and in thebottom fixture element 112, to hold theworkpiece 27 and the top andbottom fixture elements - As the alignment pins110, 112 are engaged with the workpiece alignment holes and the bottom fixture element alignment holes, the top face of the
bottom fixture element 116 is urged towards the bottom face of thetop fixture element 114, until theinjector nozzle 20 andvacuum nozzle 16 engage theinjection hole 33 andvacuum hole 35 of theworkpiece 27. Depending on the depth of the alignment holes, the length of the alignment pins 110, 112 and the thickness of thetop fixture element 114 where thevacuum nozzle 16 andinjector nozzle 20 pass through it, thetop fixture element 114 may be in contact with thebottom fixture element 116 when thevacuum nozzle 16 andinjector nozzle 20 are in proper engagement with thevacuum hole 35 andinjector hole 33. - Although FIGS.6-8 illustrate that the
bottom fixture element 116 has alignment holes and the top fixture element 113 has alignment pins 110, 112, those skilled in the art will recognize that thetop fixture element 114 could instead have the alignment holes and thebottom fixture element 116 could have the alignment pins. Similarly, although FIGS. 6-8 illustrate that thebottom fixture element 116 is lifted vertically above theconveyor 104 towards thetop fixture element 114, it is possible to instead move thetop fixture element 114 towards thebottom fixture element 116, or to move both thetop fixture element 114 and thebottom fixture element 116 towards each other. In addition, the fixture element that contacts that contacts theworkpiece 27 surface (or the die surface of a component on a carrier) can be adjustable to compensate for variations in the thickness of theworkpiece 27 or die thickness. This compensation allows proper clamping and fixturing of the components being processed due to lot variations. - FIGS.9A-9B illustrate an example of an
injector valve 20 usable in accordance with an embodiment of the invention. Theinjector valve 20 includes astroke cylinder 66,stopper rod assembly 60, andnozzle assembly 82, along with various fitting and hardware components, which operate together to provide a positive shut-off function that the controller 12 (FIG. 2) can control with precision. Each of these elements is described more fully below. - The
nozzle assembly 82 includes aflexible nozzle tip 83 that forms a tight seal to theinjection hole 33 of a workpiece 27 (FIGS. 1 and 2). Thenozzle tip 83 is “doughnut” shaped and has an opening in the center therein through whichmaterial 24 to be injected can flow and which can receive therod tip 61 of a stopper rod assembly 60 (described more fully below) to block the hole in thenozzle tip 83 and prevent material 24 from escaping. Thenozzle assembly 82 is coupled to a first end of anupper body assembly 78 to which anipple assembly 76 attaches. Thenipple assembly 76 couples to a source ofmaterial 24, such as the material assembly 108 (FIGS. 4-7), for receiving material to be injected. An O-ring 80 helps to form a tight seal between thenozzle assembly 82 and theupper body assembly 78. - A piston seal74 couples the second end of the
upper body 78 to a first side of abushing assembly 70 via afirst retainer nut 72. Asecond retainer nut 68 couples the second side of thebushing assembly 70 to astroke cylinder 66 and astopper rod assembly 60. Thestroke cylinder 66 is coupled via a length oftubing 62 and first, second, andthird fittings stroke cylinder 66 can be an SMC Cylinder manufactured by Kinequip Inc., Buffalo, N.Y., such as Model. No. NCJ2B16-050T. This model can operate with a maximum pressure of 100 pounds per square inch (PSI), and those skilled in the art will recognize that other stroke cylinders having comparable specifications can be used in accordance with the invention. - The
stopper rod assembly 60 is movably coupled to thestroke cylinder 66, such as by spring loading. During operation of theinjector valve 20, pressure from a pressure source 23 (FIG. 1) can be applied and removed from thestroke cylinder 66. When pressure is applied, the pressure compresses the spring biasing within thestroke cylinder 66, thereby holding thestopper rod assembly 60 back from thenozzle tip 83. Thus, when pressure is applied, thestopper rod assembly 60 is disposed within theupper body 78 andnozzle assembly 82 to permitmaterial 24 to flow through thenozzle tip 83 of thenozzle assembly 82, through an injection hole 33 (FIG. 1) and into thehollow area 26 of a workpiece 27 (FIG. 1). - When pressure is released, the spring biasing within the stroke cylinder releases and the
stroke cylinder 66 can move thestopper rod assembly 60 through thebushing 70 andupper body 78 so that therod tip 61 of thestopper rod assembly 60 is disposed at the opening in thenozzle tip 83 of thenozzle assembly 82, to preventmaterial 24 entering through thenipple 76 from escaping through thenozzle tip 83. Because the controller 12 (FIG. 2) can precisely control when and how pressure from pressure source 23 (FIG. 2) is applied, the flow ofmaterial 24 out of theinjector valve 20 can be precisely controlled. - FIG. 10 illustrates an example of a
vacuum nozzle 16 usable in accordance with an embodiment of the invention. Anozzle body 88 has aseal 86 at one end and a fitting 90 at the other end. The fitting 90 andseal 86 are structured and arranged to be operable with the vacuum source 14 (FIG. 1) and to be coupled closely to thevacuum hole 35. Those skilled in the art will recognize the types of vacuum nozzles that may be usable in accordance with the invention. - As described herein, the present invention provides improved systems, methods, and apparatuses for encapsulation of articles such as electronic components. The controller and injector valve precisely control the flow of encapsulant into the workpiece, which ensures that a proper quantity of encapsulant is applied to the articles, improves the yield of the encapsulation process, and decreases waste of encapsulant. Having the controller control operation of the vacuum source provides precise control of the vacuum being applied to the workpiece. This permits the time and magnitude of the applied vacuum to vary based on the encapsulant used and the number and size of articles to be encapsulated.
- In addition, use of a vacuum source applying a vacuum directly to the area containing articles to be encapsulated, as described herein, provides advantages over the prior art. First, applying a vacuum only to that area helps to reduce the size of the vacuum source required, thereby reducing the size of the dispensing system overall. Second, applying a vacuum to the area in which encapsulant is being injected at the same time that the encapsulant is being injected speeds the flow of encapsulant through the workpiece and helps ensure that the encapsulant thoroughly contacts all the articles to be encapsulated. In addition, use of a trap in connection with the vacuum source helps prevent encapsulant being drawn through the workpiece from contaminating the vacuum source or other areas outside of the workpiece.
- Having thus described at least one illustrative embodiment of the invention, various alterations, modifications and improvements will readily occur to those skilled in the art. Such alterations, modifications and improvements are intended to be within the scope and spirit of the invention. Accordingly, the foregoing description is by way of example only and is not intended as limiting. The invention's limit is defined only in the following claims and the equivalents thereto.
Claims (33)
Priority Applications (1)
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US10/233,746 US20030010286A1 (en) | 2000-01-28 | 2002-09-03 | Conveyorized vacuum injection system |
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US09/493,873 US6444035B1 (en) | 2000-01-28 | 2000-01-28 | Conveyorized vacuum injection system |
US10/233,746 US20030010286A1 (en) | 2000-01-28 | 2002-09-03 | Conveyorized vacuum injection system |
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Cited By (3)
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US20070116794A1 (en) * | 2002-12-26 | 2007-05-24 | Kenya Wada | Resin application method on panel, manufacturing method of panel for display and resin applying apparatus thereof |
US7452197B2 (en) * | 2002-12-26 | 2008-11-18 | Hitachi High-Technologies Corporation | Resin application method on panel, manufacturing method of panel for display and resin applying apparatus thereof |
CN111867346A (en) * | 2020-07-06 | 2020-10-30 | 黄美婷 | Split type press fitting system of power electronic module |
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