JP5694486B2 - Resin sealing device - Google Patents

Description

  The present invention provides a resin seal that clamps a mounting substrate on which a plurality of semiconductor elements are mounted on one side with a lower mold in which a cavity recess is filled with a sealing resin while being held by suction on the upper mold, and collectively encapsulates the resin. It relates to a stopping device.

  In order to increase the production efficiency of semiconductor devices, a work in which a plurality of semiconductor elements are mounted on a large substrate is loaded into a mold, sealed with resin, and the molded product is diced and separated into individual pieces. It is being commercialized.

  Generally, a sealing resin (epoxy resin, etc.) has a higher thermal shrinkage rate than a substrate material (eg, glass epoxy resin substrate, etc.). ) And tends to warp so as to have a convex shape on the opposite side. As a result, the processing accuracy such as subsequent dicing may be reduced, handling may be difficult, or a defect such as a connection failure may be caused when the product is mounted on a board.

  For this reason, the substrate on which the semiconductor element is mounted is placed on the lower mold in which the cavity recess is formed with the semiconductor element facing the cavity recess, and the upper mold surface that clamps the substrate with the upper mold is convex. Is formed. When the substrate is clamped with a mold, the substrate is resin-sealed while the semiconductor element mounting surface side is curved along the convex shape of the upper die. As a result, the warped portion of the substrate is corrected by cooling the package portion after molding and heat shrinking. (Patent Document 1).

JP 10-326800 A

  Since the production efficiency of the substrate in which the semiconductor elements are arranged in one row is low, it is efficient to mount the semiconductor elements in a matrix using a larger substrate and encapsulate them in a resin. In Patent Document 1, the upper mold surface is a convex surface corresponding to each semiconductor element mounted on the substrate. However, in addition to bending the substrate, the resin pressure is applied to the wire connection of the semiconductor element. Since a load is applied to the part, connection reliability may be reduced. In addition, in the case of transfer molding, since the sealing resin is made to flow, voids are likely to be generated by embracing air, and in the case of a thin product having a relatively small heat capacity, the sealing resin is easily cured by heat, so that a large substrate It is not suitable for molding.

  Also, consider a device configuration in which a sealing resin is supplied in advance to a cavity recess formed in the lower mold, and a large substrate is sealed with a mold using a mold mold that holds and clamps the substrate to the upper mold. It is done. However, since a large molding area of the substrate requires a large pressing force, it is necessary to prevent air bubbles from being trapped in the mold. In the case of a thin package, it may be considered that the cavity is closed and reduced pressure molding is performed in order to eliminate the generation of voids. However, there is a possibility that the substrate may be detached from the suction surface and fall due to displacement or deformation due to bending of the large substrate or formation of a decompression space. In addition, in the case of a substrate having a large molding area, there is also a problem that it is difficult to release from a mold after molding.

  The object of the present invention is to solve the above-mentioned problems of the prior art and prevent the substrate from separating from the adsorption surface and dropping when resin-sealing a semiconductor mounting substrate in which a plurality of semiconductor elements are mounted on a large substrate, and It is providing the resin sealing apparatus which can accelerate | stimulate the mold release after shaping | molding.

In order to achieve the above object, the present invention comprises the following arrangement.
That is, a resin that is collectively sealed by clamping with a lower mold in which a cavity recess is filled with a sealing resin while a semiconductor element mounting substrate on which a plurality of semiconductor elements are mounted on one side is adsorbed and held by the upper mold In the sealing device, the lower die has a lower chase fixed to a lower die base, and a center block and a movable block urged upward by an elastic body around the center block. A plurality of support pins are provided on the substrate clamp surface of the movable block so as to protrude and immerse from the substrate clamp surface so as to abut against and support the substrate sucked and held by the upper die. The upper mold chase is fixed to the upper mold base, and a seal ring is provided between the upper mold chase and the lower mold chase. When the mold clamping operation is started, the upper mold chase absorbs the upper mold chase. The support pins abut against the held substrate to support the cavity, and when the seal ring is clamped by the upper die chase and the lower die chase, the cavity is sucked by a suction device through a suction passage communicating with the cavity. wherein the vacuum space is formed clamping within.
As a result, when the clamping operation is started while the substrate is sucked and held by the upper die, the substrate is first supported by the plurality of support pins protruding from the substrate clamping surface of the movable block. The fall of the used substrate can be prevented. Moreover, since the substrate remains adsorbed to the upper mold insert when the mold is opened, the molded product is released from the cavity, and the support pin pushes the substrate up again from the movable block, so that the release of the molded product can be promoted. .
In addition, since the pressure difference between the pressure of the resin in contact with the substrate and the pressure in the cavity is increased and the air present at the interface between the substrate and the sealing resin is pushed out of the cavity, the package is thin and large. Even in this case, molding can be performed without mixing bubbles, and molding quality can be improved.
In the present specification, “clamp” includes not only an operation of sandwiching a solid substance but also an operation of sandwiching a liquid or semi-liquid fluid (for example, a molten resin) filled in a concave portion to pressurize it.

  If the resin sealing device according to the present invention is used, when the semiconductor mounting substrate in which a plurality of semiconductor elements are mounted on a large substrate is resin-sealed, the substrate is prevented from separating from the adsorption surface of the upper mold insert and dropping. And the resin sealing apparatus which can accelerate | stimulate the mold release after shaping | molding can be provided.

It is sectional explanatory drawing which shows the state before the mold clamping of the resin sealing apparatus which concerns on Example 1. FIG. It is sectional explanatory drawing which shows the state after the mold clamping of the resin sealing apparatus of FIG. It is sectional explanatory drawing which shows the state before the mold clamping of the resin sealing apparatus which concerns on Example 2. FIG. FIG. 4 is a cross-sectional explanatory view showing a state after mold clamping of the resin sealing device of FIG. 3.

  Hereinafter, preferred embodiments of a resin sealing device according to the present invention will be described in detail with reference to the accompanying drawings.

First, referring to FIG. 1, the upper mold 1 will be described as a fixed mold and the lower mold 2 as a movable mold.
The configuration of the upper mold 1 will be described. An upper chase 4 is fixed to the upper mold base 3. An upper mold insert 5 is supported on the upper mold chase 4 by a guide block 6. The upper mold insert 5 is assembled in the upper mold chase 4 by being elastically bent in advance so as to protrude downward toward the center position of a cavity recess described later.

  A coil spring 7 is loaded in the screw hole 3 a that penetrates the upper die base 3 and the through hole 4 a that penetrates the upper die chase 4. A press screw 8 is screwed into the screw hole 3a. When the press screw 8 is tightened, the coil spring 7 is pressed and contracted so that the upper mold insert 5 is always urged downward. ing. The amount of deflection of the upper mold insert 5 can be adjusted by adjusting the fitting amount of the pressing screw 8 with respect to the screw hole 3a (height of the pressing screw 8). For example, in the case of a large substrate 23, the position of the pressing screw 8 is lowered and adjustment is made such that the upper mold insert 5 is strongly biased by the coil spring 7, so that the substrate 23 is bubbled regardless of the size of the substrate 23. It is possible to bend to a predetermined angle suitable for discharging the gas.

  The upper mold insert 5, the upper mold chase 4, and the upper mold base 3 are provided with air suction paths 9 a, 9 b, 9 c, respectively, and are connected to the suction device 10. When the suction device 10 is operated, the substrate 23 is sucked and held on the lower surface of the upper mold insert 5. Further, the substrate suction surface 5a of the upper mold insert 5 is formed on a satin surface communicating with the suction device 10 through the air suction passages 9a, 9b, 9c. The pear ground is formed in a range narrower than the outer shape of the substrate 23 to be adsorbed. A sealing material 26 is inserted between the upper mold insert 5 and the upper mold chase 4 so as to ensure airtightness between the air suction path 9a and the air suction path 9b.

  Further, the upper mold insert 5 is supported by a guide block 6 provided in the upper mold chase 4 so as to be urged by a coil spring 7 and to be bent downward. In this case, the upper mold insert 5 is held by the upper mold chase 4 by engaging the step formed on the outer periphery of the upper mold 5 with the step formed on the opposing surface of the guide block 6. The upper die insert 5 may be supported by the upper die chase 4 without being provided with the coil spring 7, so that the upper die insert 5 is preliminarily ground and pressed and bent so as to protrude downward. .

For example, when the central portion of the upper insert 5 having a thickness of 12 mm and a vertical and horizontal dimension of 100 mm × 200 mm is pressed by the coil spring 7 having a length of 372 kgf, the amount of deflection of the upper insert 5 is approximately 0.2 mm. When the upper mold insert 5 is clamped and sealed with resin, it is pushed back against the bias of the coil spring 7 by the resin pressure, and the outer shape in plan view slightly expands (less than 1 μm). It is positioned on the side wall of the mold chase 4 and is supported flat. In addition, when the cavity area is 80 mm × 160 mm, it is confirmed that the resin pressure is pushed back flat at a pressure of about 4.7 kgf / cm ² .

Next, the configuration of the lower mold 2 will be described.
In the lower mold 2, a lower mold chase 12 is fixed on the lower mold base 11. A heater 13 is built in the lower chase 12. A center block 14 is fixed to the lower chase 12. Around the center block 14, a movable block 15 functioning as a clamper is always urged upward by a first spring 16 which is elastically inserted between the lower block chase 12. A cavity recess 17 is formed by the center block 14 and the movable block 15.

  Further, on the substrate clamp surface (upper surface) 15 a of the movable block 15, support pins 18 are provided so as to protrude and sink from the substrate clamp surface 15 a so as to abut against and support the substrate 23 sucked and held by the upper mold 1. The support pin 18 is always biased in a direction of protruding upward by a second spring 19 that is elastically inserted into the movable block 15. When the lower die 2 is clamped, the support pin 18 resists the bias of the second spring 19 so that the support pin 18 comes into contact with the substrate 23 adsorbed by the upper die insert 5 and is supported while being supported. And pushed.

Further, a seal ring 20 is provided on the upper outer peripheral side of the lower die chase 12, and a closed space is formed when sandwiched between the upper die chase 4 and the opposite. An air suction path 21 connected to the closed space is formed in the lower chase 12 and is connected to the suction device 22.
When the seal ring 20 is sandwiched between the upper die chase 4 and the lower die chase 12 and air is sucked by the suction device 22, a reduced pressure space is formed in the mold including the inside of the cavity.

Here, an example of the resin sealing operation using the resin sealing device will be described.
As the substrate 23, a semiconductor mounting substrate in which a plurality of semiconductor elements 24 are mounted on one side in a matrix is used.
In FIG. 1, when the mold is in the mold open state, the substrate 23 is loaded into the upper mold insert 5 of the upper mold 1 and the suction device 10 is operated so that the substrate 23 faces the semiconductor element mounting surface downward. The substrate is attracted and held in alignment with the substrate attracting surface (pear surface) 5a. At this time, the substrate 23 is sucked and held so as to protrude downward, following the bending of the upper mold insert 5.

  A sealing resin 25 such as a granule resin or a semi-cured resin is supplied to the cavity recess 17 of the lower mold 2. It is desirable that the sealing resin 25 supplied to the cavity recess 17 has a uniform and flat shape over the entire cavity surface so as not to flow as much as possible in order to avoid air bubbles and wire flow. The substrate 23 and the sealing resin 25 are supplied by a loader (not shown).

  When the substrate 23 and the sealing resin 25 are supplied, the lower mold 2 is raised using a known mold clamping mechanism (such as an electric motor and a toggle link). At this time, first, as shown in FIG. 1, the support pins 18 abut against and support the substrate 23 adsorbed by the upper mold insert 5. Next, when the seal ring 20 is sandwiched between the upper die chase 4 and the lower die chase 12 to form a closed space, a decompression space is formed in the cavity by the suction operation of the suction device 22. The suction device 22 may be operating before the seal ring 20 is clamped. The substrate 23 is gradually immersed in the molten sealing resin 25 while extruding bubbles outward from the central portion of the substrate where bending occurs, so that there is almost no resin flow, so the sealing resin 25 is cured while holding the bubbles. Can be prevented. Specifically, the sealing resin 25 is rapidly cured at the outer peripheral portion (particularly, the four corners) of the cavity concave portion 17 due to heat conduction from the heated movable block 15. For this reason, for example, when the substrate 23 is immersed in the sealing resin 25 while being held at a uniform height, since the outer peripheral portion has already progressed, the bubbles are present when bubbles are present in the central portion. May be hindered by the sealing resin 25 at the outer peripheral portion where curing has progressed, making it difficult to discharge. However, by immersing the substrate 23 in the sealing resin 25 while bending so that the central portion of the substrate is convex downward, the substrate 23 can be immersed while creating a gap from the always immersed interface toward the outer peripheral side. Accordingly, since the bubbles can be clamped while being discharged toward the outer peripheral portion of the substrate, it is possible to reliably prevent the bubbles from being mixed into the sealing resin 25 after molding.

  Thus, when the mold clamping operation is started while the substrate 23 is attracted and held on the upper mold 1, the substrate 23 is first supported by the support pins 18 protruding from the substrate clamp surface 15 a of the movable block 15. The substrate 23 adsorbed on the upper mold insert 5 can be prevented from falling. In particular, when the decompression space is formed, the suction operation of the suction device 22 and the substrate suction operation by the suction device 10 are in an equilibrium state, which is effective in preventing the substrate 23 from falling.

  Next, as shown in FIG. 2, when the support pin 18 of the movable block 15 of the lower mold 2 is immersed in the movable block 15 and the substrate clamping surface 15a clamps the substrate 23, the resin pressure in the cavity acts on the entire surface of the substrate 23. Therefore, the bending of the substrate 23 and the upper mold insert 5 is pushed back against the bias of the coil spring 7 and is supported in a flat shape. The upper die insert 5 is pushed back to a flat shape by the resin pressure, and the outer shape slightly expands (less than 1 μm). However, the upper die insert 5 is deformed as a whole and positioned on the side wall of the upper die chase 4. There is no deviation. Even if the sealing resin 25 is cured and reduced, the clamp pressure continues to act due to the bending of the upper mold insert 5.

  In the mold clamping state, the sealing resin 25 is heated and cured, the suction operation by the suction device 22 is stopped, and the lower mold 2 is moved down to open the mold. When the mold is opened, the substrate 23 remains adsorbed to the upper mold insert 5, so that the molded product is released from the cavity, and the support pins 18 push the substrate 23 up again from the movable block 15, thereby promoting the release of the molded product. .

  As described above, since the resin pressure gradually increases as the sealing resin 25 is brought into contact with the outer peripheral edge from the center of the substrate, the resin pressure is lower than the center of the substrate where the resin pressure first becomes high even if bubbles are present. It moves toward the outer peripheral edge of the substrate and is pushed out, thereby preventing the entrapment of bubbles. Further, when the seal ring 20 provided between the upper die chase 4 and the lower die chase 12 is clamped, a decompression space is formed in the cavity and the substrate clamping operation is performed, so that the resin pressure in contact with the substrate 23 is increased. The pressure difference in the cavity that has been reduced in pressure increases, and the air present at the interface between the substrate 23 and the sealing resin 25 is pushed out of the cavity and exhausted. Therefore, even if the package portion is a thin and large product, it can be molded without mixing bubbles, and the molding quality can be improved. Further, even if the sealing resin 25 is cured and contracted, the upper mold insert 5 follows and bends by the bias of the coil spring 7, so that the package portion (resin sealing portion) is continuously pressed, thereby uniform resin density. Can be sealed with resin. That is, for example, when the flat upper mold insert 5 is used, most of the molding pressure applied by clamping with the upper mold insert 5 is handled (supported) by the sealing resin 25 on the outer periphery of the substrate that has been further cured. Therefore, the molding pressure is relatively small in the sealing resin 25 in the central portion where the progress of curing is slow. However, since the central portion of the upper mold insert 5 protrudes downward in this embodiment, a desired molding pressure (clamping pressure) is applied to the sealing resin 25 at the central portion of the substrate regardless of the progress of curing of the outer peripheral portion of the substrate. Can be added. Accordingly, the distribution of the molding pressure acting on the sealing resin 25 can be made uniform, and the package portion (resin sealing portion) can be resin-sealed with a more uniform resin density.

Next, another example of the resin sealing device will be described.
Since the schematic configuration is the same as that of the mold of FIGS. 1 and 2, the same reference numerals are assigned to the same members, and the description will be referred to, and different configurations will be mainly described.
Next, in FIG. 3, the schematic configuration of the mold is the same as in FIGS. 1 and 2, but the seal ring 20, the suction device 22, and the air suction path 21 that form a decompression space in the lower mold 2 are omitted. The support pins 18 that support the substrate 23 are also omitted. In this embodiment, a release film 28 is provided so as to cover the cavity recess 17 of the lower mold 2.

The release film 28 has heat resistance that can withstand the heating temperature of the mold, and is easily peeled off from the mold surface, and has flexibility and extensibility to deform along the inner surface of the cavity recess 17. For example, PTFE, ETFE, PET, FEP film, fluorine-impregnated glass cloth, polypropylene film, polyvinylidin chloride and the like are preferably used. The release film 28 may be a long film that is continuously supplied to a mold by a release film supply mechanism (not shown), or a film that has been cut into a strip shape in advance. Either is fine.
The release film 28 is sucked and held through the substrate clamp surface 15 a of the movable clamp 15 and the gap 29 between the movable block 15 and the center block 14.

  In FIG. 3, when the mold is in the mold open state, the substrate 23 is carried into the upper mold insert 5 of the upper mold 1 and the suction device 10 is operated so that the semiconductor element mounting surface faces downward. The substrate is attracted and held in alignment with the substrate attracting surface (pear surface) 5a. At this time, the substrate 23 is sucked and held so as to protrude downward, following the bending of the upper mold insert 5.

  In addition, the release film 28 is sucked and held on the lower mold 2 so as to cover the cavity recess 17. A sealing resin 25 such as a granular resin, a pulverized resin, or a semi-cured resin is supplied to the cavity concave portion 17 covered with the release film 28. It is desirable that the sealing resin 25 supplied to the cavity recess 17 has a uniform and flat shape over the entire cavity surface so as not to flow as much as possible in order to avoid mixing of bubbles. The substrate 23 and the sealing resin 25 are supplied by a loader (not shown).

  When the substrate 23 and the sealing resin 25 are supplied, the lower mold 2 is raised using a known mold clamping mechanism (such as an electric motor and a toggle link). At this time, first, as shown in FIG. 4, the movable block 15 abuts and supports the substrate 23 adsorbed by the upper mold insert 5 via the release film 28. Further, since the substrate 23 is gradually immersed in the melted sealing resin 25 from the central portion of the substrate where the bending has occurred and there is almost no resin flow, it is possible to prevent entrapment of bubbles in the sealing resin 25. . Further, since the resin pressure is gradually increased by bringing the sealing resin 25 into contact with the outer peripheral edge from the center of the substrate, the outer peripheral edge of the substrate having a lower pressure than the central portion of the substrate where the resin pressure first becomes high even if bubbles are present. It moves toward the part and is pushed out through the interface between the substrate 23 and the release film 28, thereby preventing bubbles from being held.

  When the release film 28 is used, various resins such as a pulverized resin, a granule resin, and a sheet resin can be used as the sealing resin 25, and the mold maintenance is simplified because mold contamination is less likely to occur. Since the moldability is good, mass productivity can be improved.

Further, resin sealing may be performed using a sheet resin with a mount as the sealing resin. As the mount, a metal mount or a metal mount in which the resin contact surface is processed into a satin finish surface is preferably used. Moreover, the resin sheet laminated | stacked on a base_sheet | mounting_paper is used suitably for semi-cured resin (B stage).
If the above-mentioned sheet resin with a mount is used, it is easy to handle the sealing resin and good releasability, so that the manufacturing process can be simplified.
In addition, resin sealing may be performed using a liquid resin as the sealing resin.

1 Upper mold 2 Lower mold 3 Upper mold base 3a Screw hole 4 Upper mold chase 4a Through hole 5 Upper mold insert 5a Substrate adsorption surface 6 Guide block 7 Coil spring 8 Press screw 9a, 9b, 9c, 21 Air suction path 10 Adsorption device 11 Lower mold base 12 Lower mold chase 13 Heater 14 Center block 15 Movable block 15a Substrate clamping surface 16 First spring 17 Cavity recess 18 Support pin 19 Second spring 20 Seal ring 22 Suction device 23 Substrate 24 Semiconductor element 25 Sealing Resin 26 Sealing material 28 Release film
29 Clearance

Claims (1)

Resin sealing that is clamped with a lower mold in which a cavity resin is filled with a sealing resin while a semiconductor element mounting substrate on which a plurality of semiconductor elements are mounted on one side is held by suction on the upper mold A device,
The lower die has a lower die chase fixed to a lower die base, a center block and a movable block urged upward by an elastic body around the center block to form the cavity recess, and the movable block A plurality of support pins that abut against and support the substrate held by suction on the upper die are provided on the substrate clamp surface of the upper die so as to protrude or immerse from the substrate clamp surface. Is fixed, and a seal ring is provided between the upper die chase and the lower die chase. When the mold clamping operation is started, the support pins abut against the substrate held by suction on the upper die. Support and suction operation by a suction device through a suction path communicating with the cavity when the seal ring is clamped by the upper die chase and the lower die chase Resin sealing apparatus according to claim more to the vacuum space within the cavity is formed clamping.

Images