JP2005217006A - Device and method for forming vacuum - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide vacuum forming device/method with which flatness is maintained, resin is sealed and forming quality can be improved without occurrence of a void in the narrow sealing space of a work and without sealing resin foaming. <P>SOLUTION: In a vacuum chamber 8, liquid resin 13 heated to a prescribed temperature under a gel temperature is applied to the work 4 from a dispenser 11. The vacuum chamber 8 is vacuum-broken, fluid pressure is applied and the work 4 is sealed. The sealed work 4 is taken out from the vacuum chamber 8 and is carried into a pressurization shaping part 3. The work is heated and pressurized at the temperature exceeding gelling, and the work is shaped while curing of liquid resin 13 is promoted. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a vacuum forming apparatus and a vacuum forming method for forming a liquid resin applied to a work housed in a vacuum chamber by pressurizing and heating at a pressure higher than atmospheric pressure by vacuum break.

  In recent years, semiconductor devices have been reduced in size and thickness, and package portions to be resin-sealed have also been reduced in thickness. As a workpiece to be sealed with resin, a flip chip type in which a semiconductor chip is flip-chip connected to a circuit board, a wire bonding type in which a semiconductor chip is wire-bonded to a circuit board, or the like is used. Many of these semiconductor chips are arranged in a matrix on a substrate and collectively sealed with resin. In addition, the sealing resin is a potting device or a printing device. When the workpiece is a flip chip type, the liquid resin is discharged onto the substrate and filled in a gap between the substrate and the chip, and the chip is molded. Overmolding is performed over the surface. When the workpiece is a wire bonding type, overmolding is performed to cover the chip surface. The package portion that is collectively sealed is cut into individual pieces by cutting each semiconductor device with a dicing device or the like.

As an effective method for underfill molding of flip chip type packages, liquid resin is discharged around a chip flip-chip connected to the substrate, surrounding the gap between the chip and the substrate, and then defoamed under reduced pressure. And a method of forcibly sucking and filling a liquid resin into the gap by using a pressure difference with the surrounding air by releasing the reduced pressure and returning to the atmospheric pressure by making the inside of the gap vacuum (for example, , See Patent Document 1).
Japanese Patent No. 3220739

  However, as disclosed in Patent Document 1, a liquid resin is applied around a flip chip-connected semiconductor chip in a reduced pressure space, and the pressure is returned to atmospheric pressure by the gap between the chip-substrate and the surrounding air pressure. When underfill molding is performed using only the difference, it is difficult to maintain the airtightness of the gap between the chip and the substrate due to the temporal flow of the applied liquid resin. Further, when the workpiece is heated in order to improve the fluidity of the liquid resin, the filler is likely to settle, and the filler is difficult to uniformly enter the narrow gap between the chip and the substrate. For this reason, the filler diameter is large around the semiconductor chip, and the filler diameter becomes smaller toward the center portion, so that the strength of the package portion varies and reliability decreases. In addition, since the work is heated to a temperature higher than the temperature at which the liquid resin gels, the curing starts before the liquid resin enters the gap between the chip and the substrate and reaches the center of the semiconductor chip. May occur. In addition, in a work in which a semiconductor chip is connected to a substrate by wire bonding, the resin enters the gap between the high-density wire wirings due to capillary action and wire wettability, but due to the surface tension of the resin, the resin enters the lower space of the wire. There is another issue that is hindering the entry.

On the other hand, for example, a liquid resin is dispensed into a work carried in a vacuum chamber of about 1 to 3 torr, and the workability is increased by increasing the fluidity of the resin by heating the work and sealing it by vacuum break. However, when the liquid resin is heated in the decompressed space, bubbles and volatile components (diluent, curing agent, coupling agent, etc.) inherent in the resin are foamed and voids are generated.
Further, in the case of a liquid resin, even if it is pressed by a hard surface such as a mold when applied to a semiconductor chip, the pressure is not easily transmitted due to the presence of a filler or the like mixed in the liquid resin, and the pressure is less easily transmitted as the resin layer becomes thinner. In particular, in a work in which a semiconductor chip is connected to a substrate by wire bonding, it cannot be expected that bubbles will penetrate through the large surface tension of the liquid resin formed between the high-density wire wirings and defoam.
In addition, since the substrate constituting the workpiece is easily heated and tends to be stretched or warped, there is a risk that a package with a reduced flatness may be formed.

  The object of the present invention is to solve the above-mentioned problems of the prior art, without generating voids in a narrow sealing space of a workpiece, and maintaining the flatness without foaming the sealing resin and molding the resin by sealing the resin. It is an object of the present invention to provide a vacuum forming apparatus and a vacuum forming method with improved performance.

In order to achieve the above object, the present invention comprises the following arrangement.
In the vacuum forming apparatus, the first means is a resin discharge unit that discharges a liquid resin from the discharge unit while scanning the workpiece in a vacuum chamber in which a workpiece on which a semiconductor chip is mounted on a substrate is loaded and a vacuum state is formed; A pressure shaping unit that shapes the liquid resin discharged to the workpiece by heating and pressurizing, and a liquid resin that is heated to a predetermined temperature lower than the gelation temperature from the resin discharge unit in the vacuum chamber is applied to the workpiece, Vacuum the vacuum chamber and apply fluid pressure to seal the workpiece, take the sealed workpiece out of the vacuum chamber, load it into the pressure shaping unit, and heat and pressurize it at a temperature exceeding the gelation. It is characterized by shaping while promoting the curing of the resin.
Further, in the vacuum forming method, a work on which a semiconductor chip is mounted on a substrate is carried in, and the liquid is heated to a predetermined temperature lower than the gelation temperature from the resin discharge portion while scanning the work in a vacuum chamber in which a vacuum state is formed. Discharge resin, vacuum break the vacuum chamber and apply fluid pressure to seal the workpiece, take the sealed workpiece out of the vacuum chamber and carry it into the pressure shaping section, at a temperature exceeding gelation It is characterized by shaping while promoting the curing of the liquid resin by heating and pressing.
Further, as a second means, there are provided a resin discharge part for discharging a liquid resin onto a work on which a semiconductor chip is mounted on a substrate, and a pressure forming part for pressure forming into which the work on which the liquid resin has been discharged is carried. The workpiece is coated with a liquid resin at the resin discharge section, and is transferred into the pressure molding section. Immediately before the workpiece is clamped to the mold, the cavity is sealed and vacuumed, and the mold is clamped and the cavity is vacuum broken. The workpiece is sealed and shaped while promoting the curing of the liquid resin by heating and pressing at a curing temperature exceeding gelation.
Further, as a third means, a mounting substrate on which a land portion is formed is placed and fixed on a workpiece mounting portion provided in a vacuum chamber, and a sheet resin is carried over the mounting substrate in a vacuum state. A vacuum pressure forming section in which the semiconductor chip held by the pressure tool is pierced through the sheet resin by the electrode section and is electrically connected to the land section to be supplied with the workpiece. While the workpiece is clamped by the workpiece mounting part and the pressure tool, the resin softened by heating and pressing at a temperature lower than the foaming temperature is filled without any gap between the electrodes, and the vacuum level in the vacuum chamber is lowered to reduce the resin. It is characterized by shaping while promoting the melting and curing of the sheet resin by heating and pressurizing beyond the curing temperature.

If the vacuum forming apparatus and method according to the first means according to the present invention are used, the liquid resin is applied to the work from the resin discharge section in the vacuum chamber, and therefore, bubbles are entrained and sealed at the interface between the liquid resin and the work. There is nothing to do. In addition, a liquid resin that is heated to a predetermined temperature lower than the gelling temperature is applied to the work from the resin discharge part in the vacuum chamber, and the work is sealed by breaking the vacuum chamber and applying fluid pressure. Since the vacuum is broken and sealing is performed while applying fluid pressure to the liquid resin, the chip is created by applying atmospheric pressure + fluid pressure to the liquid resin in addition to capillary action while reducing the viscosity of the liquid resin and maintaining fluidity. The liquid resin can be filled without generating voids in the narrow sealing space surrounded by the wiring and the chip. In addition, since the sealed work is taken out from the vacuum chamber and carried into the pressure shaping unit, and shaped while promoting the curing of the liquid resin by heating and pressing at a temperature exceeding the resin gelation, the flatness of the package unit Can be sealed with resin. Therefore, it is possible to improve the molding quality of the package part, suppress the generation of defective products, and improve the yield.
If the vacuum forming apparatus according to the second means is used, the workpiece coated with the liquid resin is carried into the pressure molding section, and the liquid resin is spread around by the mold clamping operation, and the workpiece is clamped to the mold. Since the cavity is sealed immediately before vacuum suction, heating is performed in a reduced pressure environment, so that the movable clamping surface comes into contact before foaming of the liquid resin, so foaming does not occur from the contact surface. However, since it is limited to the vicinity of the flow front that does not become a product, the molding quality can be improved. In addition, while ensuring the fluidity of the liquid resin, an atmospheric pressure + clamping pressure is applied to the liquid without causing voids in the sealing space between the chip and the substrate or in the narrow sealing space surrounded by the wire wiring and the chip. Resin can be filled. In addition, while being clamped by the mold, it is shaped while promoting the curing of the liquid resin by heating and pressurizing at a curing temperature exceeding the gelation of the resin, so that the resin can be sealed while maintaining the flatness of the package part. .
If the vacuum forming apparatus according to the third means is used, the resin softened by heating and pressurizing at a temperature lower than the foaming temperature of the sheet resin while the work is clamped by the work placing portion and the pressurizing tool in the vacuum space. Since the electrodes are filled with no gap, the resin can be filled and sealed without any gap between the electrodes and without foaming. In addition, since the work is clamped by the pressurizing tool and is shaped by heating and pressurizing while promoting the melting and hardening of the sheet resin, the flatness of the package portion can be maintained and the resin can be sealed.

[First embodiment]
Hereinafter, a preferred embodiment of a vacuum forming apparatus according to the present invention will be described in detail with reference to the accompanying drawings.
First, a schematic configuration of the vacuum forming apparatus will be described with reference to FIGS. 1 and 2.
In FIG. 1, a vacuum discharge unit 2 and a pressure shaping unit 3 are provided on a base 1. Between the vacuum discharge unit 2 and the pressure shaping unit 3, a transfer hand 5 that holds the workpiece 4 on which the semiconductor chip is mounted on the substrate and can move between the vacuum discharge unit 2 and the pressure shaping unit 3. Is provided. A vision camera 72 may be provided on the workpiece mounting portion 71 on which the workpiece 4 is sucked and held by the transfer hand 5. The vision camera 72 images the workpiece 4, counts chip defects, and estimates the application amount of the liquid resin by calculation.

  A vacuum chamber 8 is formed in the vacuum discharge unit 2 by, for example, a vacuum container (vacuum bell jar) 7 that opens and closes with respect to the base 1 by an opening / closing arm 6. The vacuum bell jar 7 is connected to a vacuum pump 9 and a compressor (not shown) through a hollow opening / closing arm 6. On-off valves 25 and 26 are respectively provided in the middle of the piping (see FIG. 3). When the vacuum pump 9 is operated, vacuum is sucked through the pipe, and a vacuum chamber 8 is formed in the vacuum bell jar 7. When the compressor is operated, compressed air can be fed into the vacuum bell jar 7 through the pipe. A movable table 10 on which the work 4 is placed is provided in the vacuum chamber 8. The movable table 10 is provided in the vacuum chamber 8 so as to be able to scan in the XY directions. As this table moving mechanism, for example, a known driving mechanism such as a driving mechanism or a linear motor provided with a connection between a stepping motor and a ball screw in the XY directions is used. In the vacuum chamber 8, a heater 24 (see FIG. 3) capable of heating the workpiece 4 on the movable table 10 is provided. The heater 24 is a temperature at which the liquid resin 13 and the workpiece 4 are difficult to foam at a predetermined temperature lower than the gelling temperature (which differs depending on the liquid resin but does not reach a semi-curing temperature or a curing temperature (approximately 120 ° C. to 130 ° C.), preferably Is provided for heating at 45 ° C. to 50 ° C. to enhance fluidity.

  The dispenser 11 serving as a resin discharge unit discharges the liquid resin 13 from the discharge nozzle (dispensing nozzle) 12 to the work 4 carried into the vacuum bell jar 7. The liquid resin 13 is not easily foamed at a predetermined temperature lower than the gelling temperature by the dispenser 11 (which differs depending on the liquid resin but does not reach the semi-curing temperature or the curing temperature (approximately 120 ° C. to 130 ° C.), preferably 45 ° C. to 50 ° C). In the dispenser 11, a discharge portion main body (syringe portion) 14 for storing the liquid resin 13 is disposed outside the vacuum bell jar 7, and only the nozzle tube 15 is introduced into the vacuum bell jar 7 through the seal portion 16. Yes. The nozzle tube 15 is connected to a dispensing nozzle 12 which is arranged above the movable table 10 in the vacuum bell jar 7 so as to be movable in the vertical direction. The discharge amount of the liquid resin 13 discharged from the dispense nozzle 12 is controlled by an electromagnetically operated valve 17 provided in the middle of the nozzle tube 15.

Thus, since only the dispensing nozzle 12 and the nozzle tube 15 are disposed in the vacuum bell jar 7 and the syringe part 14 is disposed outside the vacuum bell jar 7, the vacuum chamber 8 can be reduced in size. In addition, since the movable range of the movable table 10 in the vacuum chamber 8 can be reduced, the sealing performance in the vacuum chamber 8 can be maintained well. Further, when the movable table 10 on which the work 4 is placed scans in the XY direction, the liquid resin 13 can be applied to a wide range of the work 4 of various sizes. Can be made as small as possible. When the work 4 is a semiconductor chip arranged on a substrate in a matrix, as described above, in addition to applying the liquid resin 13 over a wide range of the chip area of the work 4, The liquid resin 13 may be applied in the form of dots in the center of each semiconductor chip. Alternatively, the liquid resin may be continuously applied to the board-side connection region of the wire wiring, and the inflow of the resin to the lower portion of the wire may be facilitated by the potential energy.
If time is required for resin sealing, for example, the liquid resin 13 is discharged from the dispensing nozzle 12 to the work 4 in the room temperature decompression space and then gradually filled into the narrow sealing space by capillary action. Workpiece at a predetermined temperature lower than the gelation temperature by the heater 24 (a temperature that varies depending on the liquid resin but does not reach a semi-curing temperature or a curing temperature (approximately 120 ° C. to 130 ° C.) and is difficult to foam, preferably 45 ° C. to 50 ° C.) 4 and the liquid resin 13 may be heated to increase the fluidity of the resin.

  FIG. 2 illustrates a press device 18 that is a pressure shaping unit. In FIG. 2, the press device 18 includes a lower die 19 and an upper die 20, and heaters 21 and 22 are built in the lower die 19 and the upper die 20. The pressing device 18 closes the upper die 20 while clamping the plate-like pressure plate 23 on the liquid resin 13 of the workpiece 4 placed on the lower die 19, clamps the workpiece 4, and pressurizes the workpiece 4. It is like that. Thus, the upper surface of the liquid resin 13 is cured by heating and pressing at a temperature (120 ° C. to 130 ° C.) exceeding the gelation of the semi-cured liquid resin 13 applied to the chip area of the workpiece 4 in the vacuum chamber 8. Shape it flat. The pressure plate 23 is not limited to a metal plate, and various plate materials such as a glass plate and a ceramic plate are used. Alternatively, the pressure plate 23 may be a heat radiating plate attached integrally with the liquid resin 13. Note that the upper mold 20 and the lower mold 19 may be directly clamped without using the pressure plate 23. Further, an inspection unit 73 may be provided in the vicinity of the press device 18. The application amount of the liquid resin is calculated by the calculation of the control unit based on the imaging of the work 4 of the vision camera 72. However, since there is a measurement error of the dispenser 11 and an accuracy of the estimation program, the thickness of the package after pressure shaping is measured by the inspection unit 73, and the inspection result is feedback-controlled to discharge the liquid resin to be applied next. The amount error may be corrected.

Here, the vacuum forming operation will be described with reference to FIGS.
First, in FIG. 3A to FIG. 3D, an operation of underfill molding the work 4 in which the semiconductor chip 4a is flip-chip connected to the substrate 4b will be described. The workpiece 4 is carried onto the movable table 10 by the transfer hand 5 with the vacuum bell jar 7 opened. When the work 4 is loaded, the vacuum bell jar 7 is closed, the open / close valve 25 is opened, and the vacuum pump 9 is operated with the open / close valve 26 closed, whereby a vacuum space (for example, 0.1 to 50 torr) is formed in the vacuum chamber 8. Preferably 0.1 torr to 0.5 torr) is formed. Then, the liquid resin 13 is discharged from the dispenser 11 while scanning the movable table 10 on which the work 4 is placed in the XY directions. The liquid resin 13 is applied except for one side of the semiconductor chip 4a (see FIG. 3A). At this time, the vacuum chamber 8 is in a vacuum state, but may be applied in the atmosphere. If left in this state for a while, the liquid resin 13 can gradually enter the gap (underfill space) between the semiconductor chip 4a and the substrate 4b by capillary action.
Next, the liquid resin 13 is applied to the remaining one side in the vacuum chamber 8 in which the vacuum space is formed, and the underfill space is surrounded by the liquid resin 13. The liquid resin 13 dropped on the work 4 from the dispense nozzle 12 is defoamed in the vacuum chamber 8. When the discharge of the liquid resin 13 is completed, the scanning of the movable table 10 is stopped. At this time, the periphery of the semiconductor chip 4a is surrounded by the liquid resin 13, but a vacuum space 27 is formed in a gap with the substrate 4b immediately below the semiconductor chip 4a (see FIG. 3B). If the liquid resin 13 is applied to surround all the semiconductor chips 4a until the underfill space is insulated from the vacuum chamber space, the on-off valve 25 is closed and the on-off valve 26 is opened to evacuate the vacuum chamber 8 once. . Thereafter, the on-off valve 25 may be opened again, the on-off valve 26 may be closed, and vacuum suction may be performed so that the vacuum chamber 8 is in a vacuum state and the insufficient liquid resin 13 is applied and replenished.

Next, the operation of the vacuum pump 9 is stopped, the on-off valve 25 is closed, the on-off valve 26 is opened, and the vacuum chamber 8 is broken in vacuum. Further, the compressor is operated to send compressed air of, for example, about 1 to 10 atmospheres into the vacuum bell jar 7. At this time, by applying atmospheric pressure and fluid pressure to the liquid resin 13 surrounding the underfill space, filling of the gap of the liquid resin 13 by the capillary phenomenon (in this embodiment, underfill molding) is promoted. In particular, for a resin having high thixotropy (emulsion fluidity), fine vibration of the workpiece 4 may be used in combination with pressurization with compressed air.
Moreover, since the liquid resin 13 is heated by the heater 24 under a temperature condition in which the liquid resin 13 is not gelled and does not foam, the liquid resin 13 can be ensured in fluidity without being cured or foamed in the course of movement, so that the vacuum space 27 is gradually increased. (See FIG. 3C), and finally the liquid resin 13 is completely replaced (see FIG. 3D).

  Next, the vacuum bell jar 7 is opened, and the workpiece 4 is once taken out of the movable table 10 by the transfer hand 5 and carried into the press device 18 (see FIG. 1). Next, the pressure plate 23 is overlaid on the liquid resin 13 applied to the workpiece 4, and the press sealing device 18 is heated and pressurized by closing the press device 18 to accelerate the curing of the liquid resin 13 (the package portion). ) So that the upper surface is flat. The package part is diced and formed into individual semiconductor devices after molding. The workpiece 4 contains stress due to processing history due to heat, and the substrate is easily warped. For this reason, in order to maintain uniform molding quality of the package part, flattening is performed (see FIG. 2). Thereby, the dicing operation | work at the time of dicing the workpiece | work 4 at a post process can be performed with sufficient precision.

Next, in FIG. 4A to FIG. 4D, an operation of molding the workpiece 4 in which the semiconductor chip 4a is wire-bonded to the substrate 4b will be described. The workpiece 4 is carried onto the movable table 10 by the transfer hand 5 with the vacuum bell jar 7 opened. When the work 4 is loaded, the vacuum bell jar 7 is closed, the open / close valve 25 is opened, and the vacuum pump 9 is operated with the open / close valve 26 closed, whereby a vacuum space (for example, 0.1 to 50 torr) is formed in the vacuum chamber 8. More preferably, 0.1 torr to 0.5 torr) is formed. Then, the liquid resin 13 is discharged from the dispenser 11 while scanning the movable table 10 on which the work 4 is placed in the XY directions. In the work 4 in which the semiconductor chips 4a are arranged in a matrix on the substrate 4b, it is preferable to first form a flow stop (dam) by partitioning the chips in a grid. Next, the liquid resin 13 is applied to the substrate side connection portions of the bonding wires 4c formed on the four sides of the semiconductor chip 4a (see FIG. 4A). This work is an essential work process in the case of a stacked IC. The liquid resin 13 is applied in a vacuum space, but may be applied in the air. If left in this state for a while, the liquid resin 13 can gradually enter the gap between the bonding wire 4c and the substrate 4b by capillary action.
Next, the liquid resin 13 is dropped from directly above the workpiece 4 (semiconductor chip 4a) from the dispense nozzle 12 in the vacuum chamber 8 in which the vacuum space is formed. The liquid resin 13 dropped on the work 4 from the dispense nozzle 12 is defoamed in the vacuum chamber 8. When the discharge of the liquid resin 13 is completed, the scanning of the movable table 10 is stopped. At this time, the periphery of the semiconductor chip 4a is covered with the liquid resin 13, but a vacuum space 27 is formed in the gap with the substrate 4b immediately below the bonding wire 4c (see FIG. 4B). When the liquid resin 13 is discharged to the center of all the semiconductor chips 4a and flows out to the periphery until the resin filling space is insulated from the vacuum chamber space, the on-off valve 25 is closed and the on-off valve 26 is opened to open the vacuum chamber. 8 is vacuum broken once. After that, the opening / closing valve 25 is opened again, the opening / closing valve 26 is closed, vacuum suction is performed, the vacuum chamber 8 is evacuated, and the liquid resin 13 is applied to the central part of the work in a mountain range, and the air vent performance is maintained and insufficient. The resin to be used may be replenished.

Next, the operation of the vacuum pump 9 is stopped, the on-off valve 25 is closed, the on-off valve 26 is opened, and the vacuum chamber 8 is broken in vacuum. Further, the compressor is operated to send compressed air of, for example, about 1 to 10 atmospheres into the vacuum bell jar 7. At this time, by applying atmospheric pressure and fluid pressure to the liquid resin 13, the gap filling of the liquid resin 13 by capillary action (in this embodiment, the gap filling between the high-density wire wiring and the substrate) is promoted. In particular, for a resin having high thixotropy (emulsion fluidity), fine vibration of the workpiece 4 may be used in combination with pressurization with compressed air.
Further, since the liquid resin 13 is heated by the heater 24 at a temperature at which the liquid resin 13 is not gelled and is not foamed, the liquid resin 13 can be ensured in fluidity without being cured or foamed during the movement. It gradually becomes smaller (see FIG. 4C) and is finally completely replaced with the liquid resin 13 (see FIG. 4D).

  Here, with reference to FIG. 5, a state in which the liquid resin 13 is filled with time into the bonding wire 4 c will be schematically described. The left half of FIG. 5 shows the flow front of the liquid resin 13. The bonding wire (for example, gold wire) 4c electrically connects the electrode portion of the semiconductor chip 4a and the substrate terminal portion, but the distance between the bonding wires 4c becomes dense on the chip side and rough on the substrate terminal side. Therefore, when the liquid resin 13 is dropped onto the chip central portion, it flows to the periphery, passes through the surface of the bonding wire 4c, and begins to enter from the gap between the wires on the substrate terminal side (area E1). At this time, the behavior of the liquid resin 13 is affected by the potential energy of the liquid resin 13, the contraction energy of the vacuum space, the wettability with the bonding wire 4c, and the like. Next, the fluid pressure by compressed air is applied in addition to the atmospheric pressure due to the vacuum break, and the pressure further enters the inside (area E2), and the liquid resin 13 is further heated at a temperature lower than the gelation to reduce the viscosity. By increasing the fluidity, it has been found that the vacuum space 27 is reduced to foam and replaced with liquid resin (area E3). In addition, the right half of FIG. 5 schematically shows changes in the size of bubbles mixed with the liquid resin 13 over time. Assuming that the size of the bubble initially broken by vacuum is R1, the size of the bubble when pressurized with compressed air is reduced to R2, and the bubble of the bubble when the liquid resin 13 is heated at a temperature lower than the gelation is further reduced. The size is reduced to R3, and finally it can be reduced to a size that cannot be detected by the soft X-ray inspection apparatus.

[Second Embodiment]
Next, another example of the vacuum forming apparatus will be described with reference to FIGS.
In FIG. 6, the vacuum forming apparatus includes a resin discharge unit (a dispenser (not shown)) that discharges the liquid resin 13 to the workpiece 4 on which the semiconductor chip 4a is mounted on the substrate. Further, a compression molding die 28 which is a pressure molding part for pressure molding into which the work 4 discharged with the liquid resin 13 is carried is provided.

  The compression mold 28 includes a lower mold 29 on which the workpiece 4 is placed, and an upper mold 31 in which the cavity recess 30 is formed. The lower mold 29 is fitted with a workpiece placement portion 32 and a sealing material 33 surrounding the workpiece placement portion 32. The upper mold 31 includes a cavity block 34 that forms the bottom of the cavity recess 30 and a movable block 35 that forms the side wall of the cavity recess 30. The movable block 35 is suspended and supported by the upper mold base 36 by a coil spring 37. The cavity block 34 is supported and fixed to the upper mold base 36. A sealing material 38 is fitted on the inner peripheral surface of the movable block 35 to seal a gap 39 with the cavity block 34. The movable block 35 is provided with vacuum suction paths 40 and 41 connected to a vacuum pump (not shown). The vacuum suction path 40 is formed so as to communicate with the gap 39 between the cavity block 34 and the movable block 35, and the vacuum suction path 41 is provided so as to communicate with the clamp surface of the movable block 35.

  A release film 42 is laid in the cavity recess 30. The release film 42 covers a portion that contacts the sealing resin. In this embodiment, the release film 42 is laid so as to cover the cavity recess 30 of the upper mold 29. The release film 42 is sucked and held in the cavity recess 30 through the vacuum suction path 40 from the gap 39. The release film 42 has heat resistance capable of withstanding the heating temperature of the compression mold 28 and is easily peeled off from the upper mold surface. The release film 42 is a film material having flexibility and extensibility, such as PTFE and ETFE. PET, FEP, fluorine-impregnated glass cloth, polypropylene, polyvinyl chloride, etc. are preferably used. By using the release film 42, it is not necessary to provide the upper die 29 with an ejector pin and a cleaner part for cleaning the die surface after molding.

  The workpiece 4 is carried into the workpiece placing portion 32 of the lower die 29 with the compression molding die 28 opened. It is assumed that the release film 42 is vacuum-sucked from the vacuum suction path 40 and is stretched on the upper mold 29. Next, when the liquid resin 13 is dropped in a central manner on the center of the work 4 by a dispenser (not shown), the upper mold 29 is moved down to start mold clamping. Further, vacuum suction from the vacuum suction path 41 formed in the movable block 35 is started. When the upper die 29 starts the clamping operation, first, the release film 42 covering the cavity block 34 comes into contact with the liquid resin 13 to spread the resin around. Then, when further lowered, the clamp surface of the movable block 35 comes into contact with the sealing material 33. At this time, the inside of the cavity 43 becomes a closed space, and vacuum suction from the vacuum suction path 41 acts to reduce the pressure. Further, the lower mold 31 includes a heater (not shown) and is heated below the gelling temperature of the liquid resin 13, so that the fluidity of the resin is improved and the liquid resin 13 is quickly spread throughout the work 4. Can. The liquid resin 13 is foamed when heated in a vacuum atmosphere. However, since the upper surface side of the liquid resin 13 is pressed by the cavity block 34 via the release film 42, foaming from the contact surface does not occur, and only. It occurs at the flow front of the liquid resin 13. The foamed air from the flow front is sucked into the vacuum suction path 41.

  When suction is started from the vacuum suction path 41, a force in the direction in which the release film 42 is peeled off from the upper mold surface acts, but if the vacuum suction from the vacuum suction path 40 is stronger or in an equilibrium state, the release film 42 does not peel off. Further, if the suction of the vacuum suction path 41 is stronger, the release film 42 is peeled off and dropped, but the upper mold 31 is moved down to start the clamping operation, so that it quickly reaches the top surface of the liquid resin 13. Since it contacts and is supported, foaming of the liquid resin 13 can be suppressed on the contact surface.

The movable block 35 clamps the substrate 4b via the release film 42, and the movable block 35 is pressed against the upper mold base 36, whereby the mold clamping is completed. After the mold clamping is completed, the vacuum suction of the vacuum suction path 41 is stopped and the cavity 43 is sealed by vacuum breakage.
At this time, in addition to the atmospheric pressure, the pressure by the die press acts on the narrow sealed space of the work 4, so that the liquid resin 13 is accelerated by capillary action.

  While the workpiece 4 is clamped by the upper mold 31 and the lower mold 29, the upper surface is shaped to be flat while promoting the curing of the liquid resin 13 by heating and pressing at a curing temperature exceeding the gelation of the liquid resin 13. .

Thus, when resin sealing is performed using the compression mold 28, it is necessary to reduce foaming of the liquid resin 13 because heating is performed while forming a vacuum space in the cavity 43, but the cavity block 34 is released. Since the liquid resin 13 applied to the workpiece 4 is quickly contacted through the film 42, the influence of foaming can be reduced.
Further, since the compression molding die 28 serves as both a vacuum chamber and a pressure molding unit, the apparatus configuration can be simplified. The liquid resin 13 may be dispensed by the compression mold 28 at normal temperature and pressure, but the liquid resin 13 may be dispensed by forming a reduced pressure space.

FIGS. 7A to 7D show a vacuum forming operation using the workpiece 4 in which the semiconductor chip 4a is connected to the substrate 4b by wire bonding. Unlike FIG. 6, the vacuum suction path 41 is formed not in the movable block 35 but in the lower mold 29.
In FIG. 7A, after the liquid resin 13 is applied in a pile shape on the center of the work 4, the mold closing operation of the upper mold 31 on which the release film 42 is adsorbed and held is started. When the movable block 35 comes into contact with the sealing material 33, the cavity 43 is sealed from the outside air, and vacuum suction is started from the vacuum suction path 41. At this time, even if the release film 42 is peeled from the upper mold surface by vacuum suction from the vacuum suction path 41, the upper mold 31 is supported by the liquid resin 13 because the upper mold 31 contacts and spreads on the top surface of the liquid resin 13. Further, since the space of the cavity 43 communicates in the circumferential direction, the depressurized state proceeds.

  In FIG. 7B, when the vacuum level in the cavity 43 increases, the flow front (vacuum interface portion) of the liquid resin 13 that is not in contact with the release film 42 due to heating below the foaming temperature by the heater in the mold. Foaming begins. Further, as the cavity block 34 moves downwardly, the liquid resin 13 is spread to the peripheral edge.

  In FIG. 7C, when the fluidized liquid resin 13 reaches the cavity peripheral edge, the liquid resin 13 starts to be compressed by the downward movement of the cavity block 34. At this time, the liquid resin 13 is filled in the gap between the bonding wire 4c and the substrate 4b, and the vacuum level is lowered by the inflow of the resin into the gap and pressurization.

  In FIG. 7D, when the upper die 31 moves downward until the movable block 35 abuts against the upper die base 36, the clamping operation is stopped. At this time, the void space existing in the liquid resin 13 disappears due to the press pressure. Next, the vacuum suction of the vacuum suction path 41 is stopped and released to the atmosphere, and the workpiece 4 is heated and pressurized at a curing temperature exceeding the gelation of the liquid resin 13 while the workpiece 4 is clamped by the upper mold 31 and the lower mold 29. The top surface is shaped to be flat while promoting the curing of the resin 13.

  8A to 8D show a vacuum forming operation when the liquid resin 13 is applied to the workpiece 4 in a line shape. When vacuum suction in the cavity 43 is started, the release film 42 is supported by the crest portion of the liquid resin 13 formed in a line shape (see FIG. 8A), and foaming of the liquid resin 13 is applied in a line shape. The vacuum forming operation is the same as that shown in FIGS. 7A to 7D except that it occurs in the formed resin recess (vacuum space 27) (see FIG. 8B). FIG. 9A to FIG. 9D show the vacuum forming operation when the liquid resin 13 is applied to the work 4 in the form of dots for each semiconductor chip 4a. Since the outline of the vacuum forming operation is the same as that in FIGS. 8A to 8D, the description thereof is omitted.

  FIG. 10 shows a case where the liquid resin 13 is dispensed to the work 4 a plurality of times. For example, the liquid resin 13a applied for the first time using the same liquid resin 13 may be applied by overlapping the liquid resin 13b for the second and subsequent times a plurality of times. Further, by using different types of liquid resins 13, for example, a resin having a small filler diameter may be applied for the first time, and a resin having a coarse filler diameter may be applied for the second and subsequent times. Furthermore, a liquid resin 13b in which durability against electromagnetic waves and heat radiation characteristics are improved by applying a liquid resin mixed with carbon nanotubes may be applied to the surface layer resin applied after the second time.

  FIG. 11 shows a compression mold 28 for sealing a laminated IC 44 (including those bonded by wire bonding and those flip-chip connected) in which semiconductor chips are stacked as a workpiece. The schematic configuration of the compression mold 28 is the same as that of FIG. 6, but a positioning pin 45 is erected on the lower mold 29, and a recess 46 is formed in the opposed movable block 35. The recess 46 accommodates the liquid resin 13 leaking from the cavity, and the tip of the positioning pin 45 enters with the release film 42 when clamping the workpiece. Further, an air passage for applying air pressure is formed to prevent the release film 42 that has entered the recess 46 from being loosened.

Spacer blocks 47 and 48 are provided on the upper mold base 36 and the lower mold base 49 on the outer peripheral side of the movable block 35 in order to mold the package portion uniformly. The spacer blocks 47 and 48 are lower limit positions at which the cavity block 34 moves after the movable block 35 is clamped by the spring force stored in the coil spring 37 when the movable block 35 is pushed back against the workpiece when the mold is closed. Is regulated.
With the above configuration, a narrow seal surrounded by a sealing space between the chip and the substrate stacked by applying atmospheric pressure + clamping pressure while securing the fluidity of the liquid resin 13 and the chip stacked with the wire wiring. The liquid resin can be filled without generating voids in the stop space.

[Third embodiment]
Next, a vacuum forming apparatus according to another example will be described.
In FIG. 12, the configuration of the vacuum pressure forming unit will be described. An openable / closable vacuum bell jar 51 is placed on the base 50, and a vacuum chamber is formed in the vacuum bell jar 51. A vacuum suction path 52 connected to a vacuum pump (not shown) is formed on the base 50. Further, the base 50 is provided with an XY-θ table 53 as a work placement unit. On the upper surface of the XY-θ table 53, a porous plate 54 that sucks and holds the workpiece 4 is supported by a support base 55. The support base 55 is provided with a vacuum suction path 56 and a heater 57 for heating.

  Further, the pressurizing tool 58 is provided so as to move up and down while entering the vacuum bell jar 51 and maintaining the degree of vacuum. On the lower surface of the pressurizing tool 58, a porous plate 59 for adsorbing and holding the workpiece 4 is supported by a support base 60. The support base 60 is provided with a vacuum suction path 61 and a heater 62 for heating.

  The vacuum bell jar 51 is opened, and the mounting substrate 64 on which the land portion 63 is formed is placed on the XY-θ table 53, and is sucked and held by the porous plate 54. Further, the sheet resin 65 is carried on the mounting substrate 64 in an overlapping manner. The semiconductor chip 4 a is sucked and held on the porous plate 59 of the pressing tool 58 and is carried into the vacuum bell jar 51.

  The mounting substrate 64 and the sheet resin 65 are loaded onto the XY-θ table 53, and the vacuum bell jar 51 is closed to the base 50 while the semiconductor chip 4 a is sucked and held on the pressing tool 58. A vacuum space is formed in the vacuum bell jar 51 by vacuum suction from the vacuum suction path 52.

  The pressure tool 58 is pressed against the XY-θ table 53 in the vacuum space, and the semiconductor chip 4a breaks through the sheet resin 65 by the electrode portion 4d and is electrically connected to the land portion 63 (see the left half of FIG. 12). ). Then, while the workpiece 4 is clamped, the heaters 57 and 62 are heated and pressed at a temperature equal to or lower than the foaming temperature of the sheet resin 65 to fill the molten resin without gaps between the electrode portions 4d. Then, the vacuum level in the vacuum chamber is gradually lowered. Thereby, even if the sheet resin 65 is heated under vacuum, it can be sealed without foaming. Finally, the inside of the vacuum bell jar 51 is evacuated and compressed air is sent to eliminate the void space existing in the narrow gap between the electrode portions 4d, and the heater 57 is raised to the curing temperature to cure the sheet resin 65. Shape while promoting (see right half of FIG. 12). Note that the workpiece 4 is not limited to the semiconductor chip 4a for flip chip connection, and may be a semiconductor wafer on which a connection post is formed.

The workpiece 4 may be a single semiconductor chip provided in a row or a plurality of semiconductor chips arranged in a matrix, and the semiconductor chip may be flip-chip mounted on a substrate or wire-bonded mounted. Further, it may be a stacked type semiconductor chip.
The gelation temperature of the liquid resin 13 varies depending on the type of resin, and the temperature at which the sheet resin 65 does not foam varies depending on the type of resin.

It is a top view which shows schematic structure of the vacuum forming apparatus which concerns on 1st Example. It is explanatory drawing of a press molding part. It is explanatory drawing of vacuum forming operation | movement. It is explanatory drawing of vacuum forming operation | movement. It is explanatory drawing of the liquid resin with which the clearance gap between semiconductor chips is filled. It is explanatory drawing of the vacuum forming apparatus which concerns on 2nd Example. It is explanatory drawing of vacuum forming operation | movement. It is explanatory drawing of vacuum forming operation | movement. It is explanatory drawing of vacuum forming operation | movement. It is explanatory drawing of the vacuum forming operation | movement which concerns on another example. It is explanatory drawing of the vacuum forming operation | movement which concerns on another example. It is explanatory drawing of the vacuum forming apparatus which concerns on 3rd Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 50 Base 2 Vacuum discharge part 3 Pressure shaping part 4 Work 4a Semiconductor chip 4b Substrate 4c Bonding wire 5 Transfer hand 6 Opening / closing arm 7, 51 Vacuum bell jar 8 Vacuum chamber 9 Vacuum pump 10 Movable table 11 Dispenser 12 Dispense nozzle DESCRIPTION OF SYMBOLS 13 Liquid resin 14 Syringe part 15 Nozzle tube 16 Seal part 17 Electromagnetically operated valve 18 Press apparatus 19, 29 Lower mold 20, 31 Upper mold 21, 22, 24, 57, 62 Heater 23 Pressure plate 25, 26 On-off valve 27 Vacuum Space 28 Compression molding die 30 Cavity recess 32 Workpiece placement portion 33, 38 Seal material 34 Cavity block 35 Movable block 36 Upper die base 37 Coil spring 39 Gap 40, 41, 56, 61 Vacuum suction path 42 Release film 43 Cavity 4 stacked IC
45 Positioning Pin 46 Recess 47, 48 Spacer Block 49 Lower Mold Base 53 XY-θ Table 54, 59 Porous Plate 55, 60 Support Stand 58 Pressurizing Tool 63 Land Part 64 Mounting Board 65 Sheet Resin 71 Work Placement Part 72 Vision Camera 73 Inspection Unit

Claims (6)

A resin discharge unit that discharges a liquid resin from the discharge unit while scanning the workpiece in a vacuum chamber in which a workpiece on which a semiconductor chip is mounted on the substrate is loaded and a vacuum state is formed;
A pressure shaping unit that shapes the liquid resin discharged to the workpiece by heating and pressing;
A liquid resin heated to a predetermined temperature lower than the gelation temperature is applied to the workpiece in the vacuum chamber from the resin discharge portion, and the workpiece is sealed by applying a fluid pressure by breaking the vacuum chamber under vacuum. A vacuum forming apparatus characterized in that a workpiece is taken out from a vacuum chamber, is carried into a pressure shaping unit, and is shaped while promoting curing of a liquid resin by heating and pressurizing at a temperature exceeding gelation.   2. The vacuum forming apparatus according to claim 1, wherein fluid pressure is applied to the liquid resin by sending compressed air into the vacuum chamber that has been ruptured by vacuum. A resin discharge part for discharging a liquid resin to a workpiece on which a semiconductor chip is mounted on a substrate;
A pressure molding unit for pressure molding into which a workpiece discharged with a liquid resin is carried,
The work to which liquid resin is applied at the resin discharge section is carried into the pressure forming section, and the cavity is sealed and vacuum sucked immediately before the work is clamped to the mold to vacuum break the cavity after the mold clamping is completed. The vacuum forming apparatus is characterized in that the workpiece is sealed by, and is shaped while promoting the curing of the liquid resin by heating and pressing at a curing temperature exceeding gelation.   The pressure molding part is a compression molding die with a release film laid in the cavity recess, and the vacuum chamber is created by sealing the cavity from the outside air and vacuuming it immediately before closing the die loaded with the workpiece. The vacuum forming apparatus according to claim 3, wherein the cavity is vacuum broken after completion of the mold clamping. A mounting board on which a land part is formed is placed and fixed on a work mounting part provided in a vacuum chamber, and a sheet resin is superimposed on the mounting board and carried into a vacuum state, which is held by a pressure tool. A vacuum press-molding part in which the work piece is supplied by the semiconductor chip being broken through the sheet resin by the electrode part and electrically connected to the land part,
While the workpiece is clamped by the workpiece placement unit and the pressure tool in the vacuum chamber, the resin softened by heating and pressing at a temperature lower than the foaming temperature is filled without any gap between the electrodes, and the vacuum in the vacuum chamber A vacuum forming apparatus characterized in that shaping is performed while reducing the level and heating and pressurizing beyond the curing temperature of the resin to promote melting and curing of the sheet resin.   A workpiece on which a semiconductor chip is mounted on a substrate is carried in, and a liquid resin heated to a predetermined temperature lower than the gelling temperature is discharged from a resin discharge portion while scanning the workpiece in a vacuum chamber in which a vacuum state is formed, and the vacuum The chamber is broken by vacuum and fluid pressure is applied to seal the workpiece. The sealed workpiece is taken out from the vacuum chamber and loaded into a pressure shaping unit, and heated and pressurized at a temperature exceeding the gelation to form a liquid resin. A vacuum forming method characterized by shaping while promoting curing.

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