JP2019181872A - Mold tool, resin molding device and resin molding method - Google Patents

Abstract

To provide a mold tool, a resin molding device and a resin molding method in which resin filling ability is enhanced by reliably exposing the surface of a chip.SOLUTION: A mold resin R is pressure-molded by relatively moving, together with the movement of a transfer mechanism 5, the position of a cavity insert 3f with respect to a chip pressing insert 3e pressed against the surface of a chip between a cavity volume expanded position and a cavity volume reduced position.SELECTED DRAWING: Figure 2

Description

  The present disclosure relates to a mold, a resin molding apparatus, and a resin molding method for resin-molding a workpiece having a plurality of chips mounted on a substrate with the chip surface exposed.

  In recent years, with the spread of AI technology, processor units such as GPU (Graphics Processing Unit) on the silicon substrate with TSV wiring and HBM (High Bandwidth Memory) in the vicinity are arranged close to each other, and the high density between the chips. Products related to SIP (System In Package) structure products connected by wiring and FPGAs (Field-Programmable Gate Array) having similar configurations have been developed. For example, many semiconductor chips such as GPU, FPGA and HBM are mounted on a wafer as an interposer having a diameter of 300 mm. These semiconductor chips having different heights (hereinafter simply referred to as “chips”) are used for circuit protection and external In order to facilitate connection with peripheral circuits, there is a need to provide a package mold.

  In this case, the GPU has a large mounting area, for example, 20 × 30 mm, and includes an extremely large number of elements, and the HBM is stacked in multiple layers, so that an extremely large number of memory elements are arranged, and these are high frequency. A large amount of heat is generated due to the operation with signals. For this reason, in resin molding, it is necessary to mold the resin in a state in which the surface of each chip is exposed to ensure heat dissipation. Moreover, since the height of each chip is different, there is also a problem that it is weak against mechanical stress and easily distorted.

  In addition, when mold underfilling a workpiece mounted in a matrix arrangement in which a plurality of chips are flip-chip connected on a substrate, the mold resin flows from a location with a large gap, so the resin between the flip-chip connected chip and the substrate or resin It is difficult to fill with mold resin in a portion such as a gap between chips in a direction orthogonal to the flow direction.

  As a technique to improve the resin filling property for mold dies, after clamping the workpiece with a clamper and filling the cavity with mold resin in the retracted position, the relative position of the cavity piece to the clamper is moved by mold closing operation. TCM (Transfer Compression Mold) that pushes back excess resin and mold mold (Patent Document 1: Japanese Patent Laid-Open No. 2013-28087) that uses a plate thickness adjustment mechanism. Mold mold that fills the mold resin melted from the pot into the cavity with the transfer mechanism at the same height as the surface, and pressurizes the resin in the cavity with the pressurization piece by repeating the mold opening and closing operation of the upper mold and lower mold Has been proposed (Patent Document 2: WO2015 / 159743).

JP 2013-28087 A WO2015 / 159743

However, as in Patent Document 1, when the gap between the cavity pieces at the position facing the chip is narrow, it is difficult for the resin to flow, and it is difficult for the resin to spread on the upper surface of the chip. However, there is a technique for improving the resin flow by filling the cavity space by increasing the cavity space to fill the narrow portion with the resin, but it is not suitable for chip exposure.
Also, as in Patent Document 2, when the mold opening / closing operation of the mold is repeated, it is necessary to control the position of the press device with high accuracy, and the device configuration becomes complicated and sophisticated.

  Disclosure applied to some embodiments described below has been made to solve the above-mentioned problems, and the object of the disclosure is to reliably expose the surface of the chip and improve resin filling properties. An object of the present invention is to provide a mold that can be molded, a resin molding apparatus, and a resin molding method.

  Disclosure relating to some embodiments described below includes at least the following configurations. That is, a first mold for supporting a work on which a chip is mounted, a second mold in which a cavity recess is formed facing the chip mounting portion, and a transfer mechanism for pressure-feeding mold resin into the cavity recess The second mold is disposed in the second mold so as to be surrounded by the clamper that clamps the workpiece that forms the cavity recess, and is placed on the chip surface in a mold-closed state. A chip pressing piece that is always pressed, and a cavity piece that is supported so as to be relatively movable around the chip pressing piece, and with respect to the chip pressing piece pressed against the chip surface in accordance with the operation of the transfer mechanism. The cavity piece position is relatively moved between a position where the cavity volume is enlarged and a position where the cavity volume is reduced. Wherein the pressure molding.

According to the above configuration, when the workpiece is clamped with the first mold and the second mold, the chip pressing piece is constantly pressed against the chip surface, so that the mold resin melted by operating the transfer mechanism is put into the cavity. Even when filled, the surface of the chip can be reliably exposed and molded.
Along with the operation of the transfer mechanism, the mold resin is moved by relatively moving the cavity piece position with respect to the chip holding piece pressed against the chip surface between the position where the cavity volume is reduced by the resin pressure and the position where the cavity volume is enlarged. Therefore, underfill molding can be prioritized first, and then the resin fluidity can be increased to increase the resin filling property so as to fill the gap between the chips.

A restriction part for restricting relative movement of at least a part of the cavity piece on the runner gate side with respect to the chip holding piece is provided, and the at least some of the cavity pieces are cavity volumes with respect to the chip holding piece pressed against the chip surface. The mold resin is filled in the cavity recess in accordance with the operation of the transfer mechanism at the reduced position, and the cavity is moved to a position where the cavity volume is enlarged by the resin pressure, and the cavity of the at least some cavity pieces is moved by the restricting portion. When the movement in the direction of increasing the volume is restricted, the cavity piece may be relatively moved to the position where the cavity volume is reduced again by a further mold closing operation.
As a result, at least a part of the cavity piece on the side of the runner gate is moved from a position where the relative movement with respect to the chip holding piece is restricted to a position where the cavity piece is reduced again by a further mold closing operation. By relative movement, the resin pressure can be increased and pressure molding higher than transfer molding, and voids can be reduced as much as possible to fill areas that are difficult to fill with mold resin, such as gaps between chips and gaps between chips and substrates. Can do. In particular, by reducing the cavity volume other than the chip holding piece, it can be finally made the same height as the underfill mold, so the resin filling property of the underfill mold is improved and the amount of resin used in the molded product is reduced. You can also

In the second mold, the chip pressing piece is urged and supported by the first urging means with respect to the chase, and the cavity piece is urged and supported by the second urging means, and the cavity When the piece is pushed back against the urging force of the second urging means by the resin pressure, the movement is preferably restricted by the stopper and moved relative to the chip pressing piece.
Thereby, since the increase in the pressing force of the chip pressing piece against the chip by the mold clamp can be released by the first biasing means, excessive mechanical stress does not act on the workpiece.
Further, since the second urging means bends when the resin pressure acts on the cavity piece and the relative position with respect to the chip pressing piece changes, the cavity volume can be made variable. Therefore, when the cavity piece expands the cavity volume, mold resin is received in the cavity recess, and when the movable position is restricted by the stopper, the relative position moves downward with respect to the chip holding piece by further mold closing operation. Thus, the cavity volume can be reduced, and pressure molding can be performed by applying a higher resin pressure than in ordinary transfer molding.

It is preferable that the cavity piece relatively moves to the height of the lower surface of the chip pressed against the chip pressing piece by a mold closing operation, and moves relative to the height of the upper surface of the chip by resin pressure.
Thereby, when operating the transfer mechanism and filling the mold resin in the cavity concave portion, the mold underfill of the flip chip connected chip can be performed preferentially by moving the position of the cavity piece relatively, When the resin pressure is applied, the space in the cavity recess can be widened and the gap can be easily filled with the mold resin.
Moreover, if the final mold closing position of the cavity piece is kept below the upper surface height position of the chip, the resin pressure can be applied with a higher pressing force than in normal transfer molding, so the voids are reduced as much as possible and wasteful. The resin amount can be reduced and resin molding can be performed.

  The chip pressing pieces may be arranged so as to face a plurality of chips. Thus, the chip pressing piece can be surely exposed and molded by pressing the chip surface for each chip facing the chip pressing piece.

  It is preferable that a decompression space is formed in the mold by the mold closing operation by the first mold and the second mold. Thereby, the air bubbles mixed in the mold resin filled in the cavity recess can be removed by suction under reduced pressure to improve the molding quality.

  It is preferable that a film is sucked and held on the clamp surface including the cavity concave portion of the second mold and pressed against the chip surface by the chip pressing piece through the film. As a result, when the chip holding piece is pressed against the chip, the chip surface can be protected by using a film as a cushioning material, and the clamper, the chip holding piece and the cavity piece are relatively moved by the mold closing operation, and the volume of the cavity recess is increased. Even if changes, mold resin does not leak and mold maintenance can be facilitated.

The clamper may be provided with an overflow cavity that accommodates mold resin overflowing from the cavity recess.
As a result, the mold resin filled in the cavity recess is pressurized and overflows, so that an unfilled area of the mold resin can be eliminated as much as possible to improve the molding quality.

  In the resin mold apparatus, by providing any of the mold dies described above, it is possible to enhance the molding quality and improve the productivity by molding to enhance the resin filling property while reliably exposing the surface of the chip. Can do.

  A resin molding method in which a chip is exposed and transfer molded to a workpiece on which a chip is mounted. The mold is closed, the workpiece is clamped by a clamper that forms a cavity side, and a cavity bottom is formed. The cavity piece provided around the chip holding piece is moved relative to the first position where the cavity volume is reduced while the chip holding piece is pressed against the chip surface, and the mold resin melted by operating the transfer mechanism A step of feeding into the cavity, a step of retreating the cavity piece to a second position where the cavity volume is expanded by the resin pressure fully filled in the cavity, and filling the mold resin, and a second position of the cavity piece The mold is closed while the movement to the The I frame is relatively moved to the first position, characterized in that it comprises a step of extruding the cavity resin to pressurize cavity outside the.

If the resin molding method described above is used, even if the mold resin melted by operating the transfer mechanism is filled in the cavity, the chip surface can be surely exposed, and the cavity piece can increase the cavity volume. Prioritize the underfill mold at the reduced first position, then retreat to the second position where the cavity piece expands the cavity volume to increase the resin fluidity and increase the resin filling property to fill the gap between the chips. It can be pressure formed.
In addition, by moving the cavity piece to the first position again to pressurize the resin in the cavity and push it out of the cavity, the resin pressure can be applied with a higher pressure than in normal transfer molding, allowing voids. In addition, it is possible to reduce the amount of resin used in the final molded product and to mold the resin.
Therefore, transfer molding can be performed by exposing the chip with the underfill mold to the work on which the chip is mounted.

  By relatively moving the cavity piece to the first position which is the height position of the chip lower surface, the resin filling property of the underfill mold can be improved, and the amount of wasted resin in the final molded product can be reduced. Resin molding can be performed.

  If the mold, the resin molding apparatus, and the resin molding method are used, it is possible to mold with the resin filling property improved by reliably exposing the surface of the chip.

It is the top view and front view of the workpiece | work before shaping | molding used for 1st Example, and the front view of the workpiece | work after shaping | molding. It is a fragmentary sectional view of the mold metallic mold concerning a 1st example. FIG. 3 is a partial cross-sectional view of the mold following FIG. 2. FIG. 4 is a partial cross-sectional view of the mold after FIG. 3. FIG. 5 is a partial cross-sectional view of the mold following FIG. 4. FIG. 6 is a partial cross-sectional view of the mold after FIG. 5. FIG. 7 is a partial cross-sectional view of the mold following FIG. 6. FIG. 8 is a partial cross-sectional view of the mold after FIG. 7. It is a partial top view of an upper model. It is a partial top view of a lower mold | type. It is an enlarged plan view of the upper mold | type surface containing the cavity recessed part used for a 2nd Example. It is a fragmentary sectional view of the mold metallic mold concerning a 2nd example. FIG. 13 is a partial cross-sectional view of the mold after FIG. 12. FIG. 14 is a partial cross-sectional view of the mold after FIG. 13. FIG. 15 is a partial cross-sectional view of the mold after FIG. 14. FIG. 16 is a partial cross-sectional view of the mold following FIG. 15. FIG. 17 is a partial cross-sectional view of the mold following FIG. 16.

  Hereinafter, an embodiment for carrying out the invention will be described in detail with reference to the accompanying drawings. The term “mold mold” refers to an upper mold and a lower mold respectively supported by a mold base, and refers to a mold excluding a mold opening / closing mechanism (press device). In addition, when referring to a resin molding apparatus, it is an apparatus provided with at least a mold die and a mold opening / closing mechanism (pressing device such as an electric motor, a screw shaft, and a toggle link mechanism; not shown) for opening and closing the mold. For this purpose, the apparatus includes a resin transfer device or a workpiece transfer device, and a workpiece carry-out device after molding. In the case of transfer molding, it is assumed that a transfer mechanism for operating a plunger inserted in the pot, and a pressure reducing mechanism for forming a pressure reducing space in the mold when the mold is closed are provided. Hereinafter, the configuration of the mold will be mainly described. In addition, the work W is made of an interposer substrate (semiconductor wafer, resin substrate, etc.) on which a large number of semiconductor chips such as processors and HBM are mounted, as well as an interposer substrate (semiconductor wafer, resin substrate, etc.) on which MEMS chips are mounted. The case where it molds is assumed. As an example, the mold will be described assuming that the lower mold is a movable mold and the upper mold is a fixed mold, but the upper mold may be a movable mold and the lower mold may be a fixed mold, or both may be movable molds.

The workpiece W includes a substrate K and a chip T, and the chip T is electrically connected to the substrate K (flip chip connection or the like). The chip T includes a semiconductor chip and a functional component such as a MEMS chip. The above-described semiconductor chip, MEMS chip, or the like has been exemplified as the chip T that needs to be exposed. However, the present invention is not limited to these. The chip T indicates the entire mounted component of the substrate K that needs to be exposed. For this reason, the chip T is not necessarily flip-chip connected.
In the following, the case where the chip T is sandwiched and formed using the film F will be described, but the film F is not necessarily a necessary member and may be omitted.

[First embodiment]
FIG. 1 illustrates a case where mold underfill is performed using a strip-shaped strip substrate (rectangular substrate) of 100 mm × 300 mm as the workpiece W.
As shown in FIG. 1A, chips T are mounted on a substrate K in a matrix arrangement. As shown in FIG. 1B, the chip T is flip-chip connected to terminal connection portions formed on the substrate K via solder bumps.
FIG. 1C shows the workpiece W after forming. The chips T arranged in a matrix are mold-underfilled and molded with a mold resin R up to the gap between the chips. FIG. 1 shows an example of 5 lines, but FIG. In addition, a row and a column are examples and are not limited to this.

  Next, a configuration example of the mold 1 will be described with reference to FIGS. 2, 9, and 10. In FIG. 2, the cavity 3 is formed in the upper mold 3 (second mold) so as to face the chip mounting portion. The lower mold 2 (first mold) is provided with a transfer mechanism 5 that supports a workpiece W on which a chip T is mounted and pressure-feeds the mold resin R to the cavity recess 4.

  First, the configuration of the lower mold 2 will be described. A lower mold chase 2a is provided on a lower mold base (not shown). A lower mold insert 2b and a lower mold center insert 2c are supported on the lower mold chase 2a. The lower mold center insert 2c is assembled with a cylindrical pot 2d in which pot holes (through holes) are formed (in FIG. 2, a single pot 2d is drawn, but a plurality of pots in a direction perpendicular to the paper surface are drawn. Exists.) A plunger 5 a is inserted into the pot 2 d, and the plunger 5 a is moved up and down by the trans-affer mechanism 5. The plunger 5a is floatingly supported by a coil spring provided in the transfer mechanism 5, for example. The plunger 5a may be supported by a hydraulic equal pressure circuit instead of being supported by a coil spring.

  In addition, a workpiece placing portion 2e on which the workpiece W is placed is engraved in the lower mold insert 2b. The workpiece W may be sucked and held when placed on the workpiece placing portion 2e. The workpiece W may be positioned by a clamp claw or the like while being placed on the workpiece placing portion 2e or the lower mold insert 2b. An annular sealing material 2f is provided on the outer peripheral edge of the lower chase 2a. The sealing material 2f is sandwiched and sealed between an upper die chase 3a described later, thereby forming a closed space in the mold 1. The lower chase 2a is provided with a suction path 2g connected to the closed space, and is connected to a suction mechanism (not shown). A reduced pressure space is formed in the mold 1 by operating a suction mechanism (not shown) in a state where the seal 2f between the upper mold 3 and the lower mold 2 is in contact. An example of the planar layout of the lower mold 2 is shown in FIG. The workpiece W is mounted on the workpiece mounting portion 2e, and is mounted using the side surface of the lower mold center insert 2c as a positioning guide. A positioning pin (not shown) may be inserted into the hole on the outer periphery of the workpiece for positioning.

  Next, the configuration of the upper mold 3 will be described. In FIG. 2, an upper mold chase 3a is provided on an upper mold base (not shown). On the upper chase 3a, an upper clamper 3b is suspended and supported by a third coil spring 3c (third urging means). The upper mold clamper 3b clamps the work W (the outer periphery of the substrate K) placed on the work placement section 2e of the lower mold 2. A through hole 3d is provided in a portion corresponding to the cavity bottom of the upper mold clamper 3b. In the through hole 3d, a chip pressing piece 3e that is always pressed against the chip surface in a mold-closed state, and an upper mold cavity piece 3f are inserted around the chip pressing piece 3e so as to be relatively movable. The chip pressing pieces 3e are arranged to face the chip T, respectively. A cavity recess 4 is formed by the upper mold clamper 3b, the chip pressing piece 3e, and the upper mold cavity piece 3f.

  Specifically, the upper mold cavity piece 3f is suspended and supported by the support plate 3g. The support plate 3g is supported by being suspended from the upper chase 3a by a second coil spring 3h (second urging means). A support block 3i is integrally supported on the lower surface of the support plate 3g, and the upper end portion of the suspension pin 3j is suspended and suspended from the support block 3i. A tip pressing piece 3e is connected to a lower end portion of the hanging pin 3j. The suspension pin 3j is suspended and supported in a state in which the pin head (upper end portion) is pushed down by a first coil spring 3k (first urging means) that is elastically provided in the support block 3i. Therefore, the support plate 3g is suspended and supported apart from the bottom surface (first stopper 3m) of the upper chase 3a in a state where the second coil spring 3h is extended. Further, the chip pressing piece 3e is suspended and supported by being separated from the lower end surface (second stopper 3n) of the support block 3i by the impact of the first coil spring 3k. The movable range of the upper mold cavity piece 3f is narrower than the movable range of the chip pressing piece 3e. That is, the movable range in which the support plate 3g is restricted to the bottom of the upper die chase 3a is narrower than the movable range in which the chip pressing piece 3e is restricted to the stopper 3m.

In this way, since the increase in the pressing force of the chip pressing piece 3e on the chip T in mold closing is absorbed by the bending of the first coil spring 3k, excessive mechanical stress does not act on the workpiece W. Furthermore, because of the clamping via the film F described later, there is less mechanical stress.
Further, when the resin pressure acts on the upper mold cavity piece 3f, the second coil spring 3h bends and absorbs the resin pressure to change the relative position with respect to the chip pressing piece 3e, so that the cavity volume can be made variable.
Therefore, when the mold resin R is received in the cavity recess 4 with the upper mold cavity piece 3f expanding the cavity volume, and the movable position of the upper mold cavity piece 3f is restricted by the first stopper 3m, further mold closing operation is performed. As a result, the cavity can be reduced relative to the chip pressing piece 3e and the cavity volume can be reduced, so that a higher resin pressure can be applied and pressure molding can be performed.

  In FIG. 2, a seal material 3p is provided between the outer wall surface of the upper mold clamper 3b and the inner wall surface of the upper mold chase 3a. The upper chase 3a is provided with a suction path 3t and is connected to a suction mechanism (not shown). A vacuum space is formed in the mold 1 by operating the suction mechanism in the mold closed state. Further, an upper mold cull 3q and an upper mold runner gate 3r (resin path) are engraved on the clamp surface of the upper mold clamper 3b at a position relative to the lower mold center insert 2c (see FIG. 9). As shown in FIG. 9, the tip of the upper runner gate 3r is connected to the cavity recess 4 (the outer peripheral edge of the upper die cavity piece 3f).

  The film F is adsorbed and held on the upper mold clamping surface including the cavity recess 4 and the resin path connected thereto. The film F may be either a continuous film or a film (sheet-fed film) cut into a strip shape. As the film F, for example, a release film having a thickness of about 50 μm and heat resistance is used. The release film is easily peeled off from the mold surface, and has flexibility and extensibility, such as PTFE, ETFE, PET, FEP film, fluorine-impregnated glass cloth, polypropylene film, polyvinyl chloride, etc. A single layer or a multi-layer film mainly composed of is preferably used. As a result, it is possible to cover the surface of the chip T and absorb variations in height, and to prevent the mold resin R from entering the chip surface and perform exposure molding.

  Further, the film F may be a filtration film-like porous film that does not allow moisture or the like to escape and escapes moisture and air, such as Poeflon (trade name), microporous film, and the like. Further, in the case of a porous film, air can be released without allowing the mold resin R to enter, so that the molding quality is improved by releasing the air mixed in the mold resin R and the generated gas under a reduced pressure environment. be able to.

  Next, a resin molding operation using the workpiece W will be described with reference to FIGS. FIG. 2 shows a state where the mold 1 is opened. The film F is adsorbed and held on the upper clamp surface of the upper mold 3. A solid resin (resin tablet) is supplied into the pot 2d of the lower mold 2, and the workpiece W is positioned and supported by the workpiece mounting portion 2e. The workpiece W and the mold resin R may be loaded simultaneously by a loader (not shown) or may be loaded individually. The support plate 3g and the chip pressing piece 3e are suspended and supported at the lower end position of the movable range.

  FIG. 3 shows a state in which the mold closing operation of the mold 1 proceeds, the lower mold 2 moves upward relative to the upper mold 3, and the sealing material 2f is clamped by the upper mold chase 3a and the lower mold chase 2a. By a suction operation by a suction mechanism (not shown), air is sucked from the suction paths 2g and 3t into the mold 1 in which the closed space is formed, thereby forming a decompression space. Further, the chip pressing piece 3e is pressed against the surface of the chip T through the film F as the mold closing proceeds.

  FIG. 4 shows a state in which the lower mold 2 is further moved upward and the mold closing is advanced. The upper mold clamper 3b contacts and clamps the workpiece W (outer periphery of the substrate K) and the lower mold insert 2b through the film F. Further, the chip pressing piece 3e has a stronger pressing force against the chip T, but the first coil spring 3k is bent, so that no excessive stress is applied to the chip T. Accordingly, the height of the lower end portion of the upper mold cavity piece 3f is relatively lowered to the height position of the terminal (solder bump) of the chip T. Thereby, the resin injection height in the cavity can be made substantially the same regardless of the presence or absence of the chip T.

  In this state, as shown in FIG. 5, the transfer mechanism 5 is actuated to raise the plunger 5a, and the mold resin R heated and melted in the pot 2d is passed through the upper mold cull 3q and the upper mold runner gate 3r into the cavity recess 4 Pressure feed. The mold 1 is heated by a heater (not shown). At this time, since the lower end portion of the upper mold cavity piece 3f is located at the height position (first position) of the terminal (solder bump) of the chip T, the mold resin R is from the gate side regardless of the presence or absence of the chip. Sequentially injected. FIG. 5 shows a state where the mold cavity R is not yet fully filled in the cavity recess 4. In addition, although the upward movement of the lower mold | type 2 has stopped once, you may raise continuously. The height of the first position is the height of the terminal (solder bump) of the chip T. However, if the force through which the resin passes between the bumps is larger than the force through which the resin flows other than the bumps, the first position is difficult to flow. The height of the position may be set narrower so that the bump flows preferentially.

Next, as shown in FIG. 6, since the cavity recess 4 is filled with the mold resin R by the transfer mechanism 5, the resin pressure in the transfer operation is increased, and the upper mold cavity piece 3f and the support plate 3g that supports the resin pressure are increased. Thus, the second coil spring 3h is pushed back upward against the urging force. Then, the support plate 3g is pushed back to the position (second position) where it abuts against the first stopper 3m (the bottom surface of the upper die chase 3a).
Next, as shown in FIG. 7, the upper mold clamper 3b is pushed up against the bias of the third coil spring 3c by further upward movement of the lower mold 2. The workpiece W mounted on the lower mold insert 2b is raised and pushes up the chip pressing piece 3e, but the cavity piece 3f cannot be raised while being fixed. As a result, the upper die cavity piece 3f moves downward relative to the chip pressing piece 3e and presses the mold resin R. At this time, the mold resin R overflowing due to the reduction of the cavity volume is returned to the pot 2d by pushing down the plunger 5a via the resin path (upper runner gate 3r, upper mold cull 3q). Alternatively, the mold resin R may overflow into an overflow cavity (not shown) provided in the upper mold clamper 3b by reducing the cavity volume.

Thereby, even in a narrow gap between the chips T, the resin pressure can be increased and the filling property can be improved. At this time, although the pressing force against the chip T by the chip pressing piece 3e is increased, the first coil spring 3k is bent, so that no excessive stress is applied to the chip T. The height of the lower end surface of the upper mold cavity piece 3f may be the height position (first position) of the terminal (solder bump) of the chip T or the surface of the chip T. In this state, the upward movement of the lower mold 2 is stopped, and the mold resin R is heated and cured while maintaining the resin pressure to hold the pressure.
Since the tip pressing piece 3e does not hit the second stopper 3n, the strength of the pressing force acting on the tip T is absorbed by the bending of the first coil spring 3k. Further, the third coil spring 3c that suspends and supports the upper mold clamper 3b is continuously compressed and compressed while the lower mold 2 continues to move upward.

  Next, as shown in FIG. 8, when the molding operation is completed, the mold 1 is opened and the film F sucked and held on the clamp surface of the upper mold 3 is peeled and replaced. Moreover, since the workpiece | work W and unnecessary resin remain | survive on the clamp surface of the lower mold | type 2, they are carried out by the unloader etc. which are not shown in figure.

As described above, when the workpiece W is clamped by the upper mold 3 and the lower mold 2, the chip pressing piece 3e is always pressed against the chip surface, so that the mold resin R melted by operating the transfer mechanism 5 is moved into the cavity. Even when filled, the surface of the chip T can be reliably exposed and molded.
Further, the mold resin 1 is operated by the transfer mechanism 5 at the first position where the cavity volume of the upper mold cavity piece 3f is reduced with respect to the chip presser piece 3e pressed against the chip surface by performing the mold closing operation. Since R is injected into the cavity and the height of the upper mold cavity piece 3f is substantially the same as the height of the underfill of the chip T, the mold resin R is sequentially filled from the gate toward the surrounding gap, and the cavity recess 4 can be fully filled.
Further, the relative movement of the upper mold cavity piece 3f is restricted, and the mold resin R is pressure-molded by moving the upper mold cavity piece 3f relative to the first position where the cavity volume is reduced again by further mold closing operation. Therefore, pressure molding can be performed by increasing the resin pressure more than transfer molding, and voids can be reduced as much as possible to fill areas where resin is difficult to fill, such as gaps between chips T and gaps between chips T and substrates K. it can. In particular, since the cavity volume other than the chip pressing piece 3e can be reduced to the same height as the underfill mold, the amount of resin used can be reduced while improving the filling property of the mold resin R. .

[Second Example]
Next, an example of a mold for performing mold underfill using a circular carrier substrate (semiconductor wafer) having a diameter of 300 mm as the workpiece W will be described. As an example of the chip T so as to correspond to the plan view of the upper mold 3 (FIG. 11A), for example, a large number of semiconductor chips in which a GPU of 20 × 30 mm size and an HBM are arranged in the vicinity thereof are arranged on the circular carrier substrate K. It is a board for FPGA mounted. The chip T is flip-chip connected to terminal connection portions formed on the substrate K via solder bumps (see FIG. 12).
In the first embodiment, the cavity pieces can be arranged between the chips T with the chips T arranged in the matrix. However, in the second embodiment, since the chips are arranged narrowly adjacent to each other, the cavities are arranged between the chips T. Pieces cannot be placed.

Next, a configuration example of the mold 1 will be described with reference to FIGS. 11 and 12. The same members as those of the mold 1 according to the first embodiment are denoted by the same reference numerals, and the description is incorporated. FIGS. 12 to 17 are schematic views and are accurate unless the upper die cavity piece 3f existing around the chip holding piece 3e of the upper die 3 (especially on the side opposite to the upper die runner gate) is required for explanation. Not shown in the figure.
In FIG. 12, the cavity 3 is formed in the upper mold 3 (second mold) so as to face the chip mounting portion. The lower mold 2 (first mold) supports a work W on which a chip T is mounted, and a transfer mechanism 5 that presses the mold resin R into the cavity recess 4 is provided.

  First, the configuration of the lower mold 2 will be described. In FIG. 12, a lower die chase 2a is provided on a lower die base (not shown). A first lower mold insert 2b1, a second lower mold insert 2b2, and a lower mold center insert 2c are supported on the lower mold chase 2a. The lower mold center insert 2c is assembled with a cylindrical pot 2d in which pot holes (through holes) are formed (in FIG. 12, a single pot 2d is depicted, but a plurality of pots in a direction perpendicular to the paper surface are drawn. May exist). A plunger 5 a is inserted into the pot 2 d, and the plunger 5 a is moved up and down by the trans-affer mechanism 5. The plunger 5a is floatingly supported by a coil spring provided in the transfer mechanism 5, for example. The plunger 5a may be supported by a hydraulic equal pressure circuit instead of being supported by a coil spring.

  A work W is placed on the first lower mold insert 2b1. Upper end surfaces of the second lower mold insert 2b2 and the lower mold center insert 2c are formed higher than the first lower mold insert 2b1, and the workpiece W is mounted on the upper surface of the first lower mold insert 2b1. The workpiece W may be sucked and held when placed on the first lower mold insert 2b1. In addition, a flange-shaped workpiece pressing portion 2d1 is formed at the upper end portion of the pot 2d, and the circular workpiece W is pressed and positioned on the upper surface of the first lower mold insert 2b1. The work pressing portion 2d1 may also serve as a resin path (lower runner gate). The workpiece W may be positioned by a clamp claw or the like while being placed on the lower mold insert 2b. The lower mold chase 2a is provided with a sealing material 2f. The sealing material 2f is sandwiched between an upper mold chase, which will be described later, and a closed space is formed in the mold. The lower chase 2a is provided with a suction path 2g and is connected to a suction mechanism (not shown). A vacuum space is formed in the mold by operating the suction mechanism in the mold closed state.

  Next, the configuration of the upper mold 3 will be described. In FIG. 12, an upper mold chase 3a is provided on an upper mold base (not shown). On the upper chase 3a, an upper clamper 3b is suspended and supported by a third coil spring 3c (third urging means). The upper mold clamper 3b clamps the work W (the outer periphery of the substrate K) placed on the first lower mold insert 2b1 of the lower mold 2 and the upper surface of the second lower mold insert 2b2. The lower surface portion of the fixed cavity piece 3s forming the cavity concave portion 4 of the upper mold clamper 3b is a pressurizing cavity portion 3b2 that pressurizes the mold resin R, and the outer side of the pressurizing cavity portion 3b2 is an intra-clamper cavity concave portion 3b1. An overflow cavity (not shown) may be formed in the clamper cavity recess 3b1.

  As shown in FIG. 11A, a through hole 3d is provided in a portion corresponding to the cavity bottom of the upper mold clamper 3b. In the through hole 3d, a chip pressing piece 3e that is always pressed against the chip surface in a mold-closed state, and an upper mold cavity piece 3f are inserted around the chip pressing piece 3e so as to be relatively movable. The chip pressing pieces 3e are arranged to face the chip T, respectively. A cavity recess 4 is formed by the upper mold clamper 3b, the chip pressing piece 3e, and the upper mold cavity piece 3f. In FIG. 11A, the entire area surrounding the chip pressing piece 3e is the upper cavity piece 3f. However, as shown in FIG. 11B, the upper mold piece 3f that can move relative to the chip holding piece 3e is a runner. It may be provided on at least a part necessary for resin flow on the gate side, and the others may be a pressurizing cavity portion 3b2 of the fixed cavity piece 3s. A cavity recess 4 is formed by the upper mold clamper 3b, the chip pressing piece 3e, the upper mold cavity piece 3f, and the pressurizing cavity 3b2.

In FIG. 12, a fixed cavity piece 3s is supported and fixed on the bottom surface of the upper chase 3a. A first suspension pin 3j1 is inserted into the through hole in the fixed cavity piece 3s, and a chip pressing piece 3e is suspended and supported on the lower surface side of the fixed cavity piece 3s at the lower end of the pin. A first coil spring 3k (first urging means) is elastically provided between the upper end portion of the first suspension pin 3j1 and the bottom surface of the upper chase 3a.
Similarly, a second suspension pin 3j2 is inserted into the through hole in the fixed cavity piece 3s, and an upper mold piece 3f is suspended and supported on the lower surface side of the fixed cavity piece 3s at the lower end of the pin. In FIG. 12, the upper mold cavity piece 3f shows only a part on the gate side where the mold resin R first flows into the cavity recess 4, and only a part of the upper mold cavity piece 3f up to the chip pressing piece 3e is shown. It is shown. Further, a second coil spring 3h (second biasing means) is elastically provided between the upper end portion of the second suspension pin 3j2 and the bottom surface of the upper chase 3a.

  Therefore, the upper die cavity piece 3f is supported by being separated from the bottom surface (first stopper 3m) of the fixed cavity piece 3s. Further, the chip pressing piece 3e is suspended and supported apart from the lower end surface (second stopper 3n) of the fixed cavity piece 3s. The movable range of the upper die cavity piece 3f is wider than the movable range of the chip pressing piece 3e. That is, the movable range in which the upper mold cavity piece 3f is restricted by the first stopper 3m is wider than the movable range in which the chip pressing piece 3e is restricted by the second stopper 3n.

In this way, since the increased pressing force of the chip pressing piece 3e during mold closing is absorbed by the bending of the first coil spring 3k, excessive mechanical stress does not act on the workpiece W. Further, since the chip T is clamped via the film F, there is little mechanical stress.
Further, when the resin pressure acts on the upper mold cavity piece 3f, the second coil spring 3h bends and absorbs the resin pressure to change the relative position with respect to the chip pressing piece 3e, so that the cavity volume can be made variable.
Therefore, when the mold resin R is received in the cavity recess 4 with the upper mold cavity piece 3f expanding the cavity volume, and the movable position of the upper mold cavity piece 3f is restricted by the first stopper 3m, further mold closing operation is performed. As a result, the cavity can be reduced relative to the chip pressing piece 3e and the cavity volume can be reduced, so that a higher resin pressure can be applied and pressure molding can be performed.

  In FIG. 12, a seal material 3p is provided between the outer wall surface of the upper mold clamper 3b and the inner wall surface of the upper mold chase 3a. The upper chase 3a is provided with a suction path 3t and is connected to a suction mechanism (not shown). A vacuum space is formed in the mold 1 by operating the suction mechanism in the mold closed state. Further, an upper mold cull 3q and an upper mold runner gate 3r (resin path) are engraved on the clamp surface of the upper mold clamper 3b at a position relative to the lower mold center insert 2c. The tip of the upper die runner gate 3r is connected to the outer periphery of the upper die cavity piece 3f. The film F is adsorbed and held on the upper mold clamping surface including the cavity recess 4 and the resin path connected thereto. The film F may be either a continuous film or a film cut into a strip shape, as in the first embodiment.

Next, a resin molding operation using the workpiece W will be described with reference to FIGS.
FIG. 12 shows a state where the mold 1 is opened. The film F is adsorbed and held on the upper clamp surface of the upper mold 3. The workpiece W is positioned and supported on the upper surface of the first lower mold insert 2b1. As shown in FIG. 13, the work W is placed on the upper surface of the first lower mold insert 2b1 in a state where the outer peripheral edge is surrounded by the lower mold center insert 2c and the second lower mold insert 2b2, and the work holder of the pot 2d is pressed. Positioning is performed by superimposing the part 2d1 on the upper surface of the workpiece W (substrate K). A solid resin (mold resin R: resin tablet) is supplied into the pot 2d. The workpiece W and the mold resin R may be loaded simultaneously by a loader (not shown) or may be loaded individually. The upper die cavity piece 3f and the chip pressing piece 3e are suspended and supported at the lower end position of the movable range. At this time, the suction operation may be started from the suction path 3t of the upper chase 3a and the suction path 2g of the lower chase 2a.

  FIG. 14 shows a state in which the mold closing operation of the mold 1 proceeds, the lower mold 2 moves upward relative to the upper mold 3, and the sealing material 2f is clamped by the upper mold chase 3a and the lower mold chase 2a. A reduced pressure space is formed by performing air suction through the suction paths 2g and 3t in the mold 1 in which a closed space is formed by a suction operation by a suction mechanism (not shown). Further, as the mold closing operation proceeds, the chip pressing piece 3e is pressed against the surface of the chip T via the film F.

  Further, when the lower mold 2 further moves upward and the mold closing proceeds, the upper mold clamper 3b moves the work W (the outer periphery of the substrate K) and the lower mold clamping surface (the first lower mold insert 2b1 and the second lower mold) through the film F. Clamp in contact with the insert 2b2). Further, the chip pressing piece 3e has a stronger pressing force against the chip T, but the first coil spring 3k is bent, so that no excessive stress is applied to the chip T. Accordingly, as shown in FIG. 14, the height of the lower end portion of the upper mold cavity piece 3 f is relatively lowered to the height position of the terminal (solder bump) of the chip T.

  In this state, the transfer mechanism 5 is actuated to raise the plunger 5a, and the mold resin R melted in the pot 2d is cavityd through the resin path between the upper mold cull 3q, the upper mold runner gate 3r, and the work pressing section 2d1. Pressure is fed into the recess 4. At this time, the mold resin R has a lower end portion of the upper mold cavity piece 3f at the height position (first position) of the terminal (solder bump) of the chip T. Sequentially injected. FIG. 14 shows a state where the cavity recess 4 is not yet filled. In addition, although the upward movement of the lower mold | type 2 has stopped once, you may raise continuously.

  Next, as shown in FIG. 15, since the transfer operation by the transfer mechanism 5 is completed and the cavity recess 4 is filled with the mold resin R, the resin pressure is increased by the transfer operation, and the upper mold cavity piece 3f is It is pushed back upward against the bias of the two-coil spring 3h. Then, the upper die cavity piece 3f is pushed back to the position (second position) where it abuts against the first stopper 3m (the bottom surface of the fixed cavity piece 3s), and may be located above the upper surface of the chip T in this figure. Is shown. As shown in FIG. 16, when the lower mold 2 is further moved upward, the pressurizing cavity 3b2 of the upper mold cavity piece 3f and the fixed cavity piece 3s is moved downward relative to the chip pressing piece 3e, and the mold resin R Press. At this time, the mold resin R overflowing due to the reduction of the cavity volume is returned to the pot 2d by pushing down the plunger 5a via the resin path (upper runner gate 3r, work holding part 2d1, upper mold cull 3q). Alternatively, the mold resin R may overflow into an overflow cavity provided in the upper mold clamper 3b by reducing the cavity volume. In the first embodiment, the resin thickness is finally formed at the height of the bump, but in the second embodiment, the resin thickness is formed up to the surface of the chip T. FIG. 17 shows another embodiment, which is an embodiment of the upper die cavity piece 3f except for the chip pressing piece 3e in the cavity recess 4 as in the first embodiment.

Thereby, even in a narrow gap between the chips T, the resin pressure can be increased and the filling property can be improved. At this time, although the pressing force against the chip T by the chip pressing piece 3e is increased, the first coil spring 3k is bent, so that no excessive stress is applied to the chip T. The height of the lower end surface of the upper mold cavity piece 3f may be the height position (first position) of the terminal (solder bump) of the chip T or the chip surface. In this state, the upward movement of the lower mold 2 is stopped, and the mold resin R is heat-cured and held while maintaining the resin pressure.
Since the tip pressing piece 3e does not hit the second stopper 3n, the strength of the pressing force acting on the tip T is absorbed by the bending of the first coil spring 3k. Further, the third coil spring 3c that suspends and supports the upper mold clamper 3b is continuously compressed and bent while the lower mold 2 continues to move upward from when the lower mold 2 is clamped.

  When the molding operation is completed, the mold 1 is opened, and the film F adsorbed and held on the clamp surface of the upper mold 3 is peeled off and replaced. Moreover, since the workpiece | work W and unnecessary resin remain | survive on the clamp surface of the lower mold | type 2, they are carried out by the unloader etc. which are not shown in figure.

As described above, when the workpiece W is clamped by the upper mold 3 and the lower mold 2, the chip pressing piece 3e is always pressed against the chip surface, so that the mold resin R melted by operating the transfer mechanism 5 is moved into the cavity. Even when filled, the surface of the chip T can be reliably exposed and molded.
Further, with the operation of the transfer mechanism 5 from the first position where the cavity volume of the upper mold piece 3f is reduced with respect to the chip presser piece 3e pressed against the chip surface by performing the mold closing operation of the mold 1 The cavity can be filled into the cavity recess 4 while being relatively moved to the second position where the cavity volume is enlarged and urging filling of the mold resin R from the runner gate toward the surrounding gap.
Further, the relative movement of the upper mold cavity piece 3f is restricted, and the mold resin R is pressure-molded by the relative movement of the upper mold cavity piece 3f again to the first position where the cavity volume is reduced by further mold closing operation. Therefore, the pressure can be increased by increasing the resin pressure more than transfer molding, and the voids can be reduced as much as possible to fill the gap between the chips T and the area where the resin is difficult to fill, such as the gap between the chips T and the substrate K. . In particular, since the cavity volume other than the chip pressing piece 3e can be reduced to the same height as the underfill mold, the amount of resin used can be reduced while improving the filling property of the mold resin R. .

  In the embodiment described above, the transfer mechanism 5 is provided in the lower mold 2, but may be provided in the upper mold 3. The cavity recess 4 is provided in the upper mold 3, but may be provided in the lower mold 2.

  W Work T Chip K Substrate R Mold resin F Film 1 Mold 2 Lower mold 2a Lower mold chase 2b Lower mold insert 2b1 First lower mold insert 2b2 Second lower mold insert 2c Lower mold center insert 2d Pot 2d1 Work holding part 2e Workpiece mounting part 2f, 3p Sealing material 2g, 3t Suction path 3 Upper mold 3a Upper mold chase 3b Upper mold clamper 3b1 Cavity cavity recess 3b2 Pressurization cavity 3c Third coil spring 3d Through hole 3e Chip retainer 3f Upper mold Cavity piece 3f1 Fixed cavity piece 3f2 Movable cavity piece 3g Support plate 3h Second coil spring 3i Support block 3j Hanging pin 3j1 First hanging pin 3j2 Second hanging pin 3k First coil It 3m first stopper 3n second stopper 3q upper mold cull 3r upper mold runner gate 3s fixed cavity piece 4 cavities 5 transfer mechanism 5a plunger

Claims (11)

A first mold for supporting a workpiece on which a chip is mounted; a second mold having a cavity recess formed facing the chip mounting portion; and a transfer mechanism for pressure-feeding mold resin into the cavity recess. A mold mold provided,
The second mold includes a clamper that clamps the workpiece forming the cavity recess, a chip pressing piece that is surrounded by the clamper and is constantly pressed against the chip surface in a mold-closed state, and the chip A cavity piece supported so as to be relatively movable around the holding piece,
In accordance with the operation of the transfer mechanism, the cavity piece position with respect to the chip holding piece pressed against the chip surface is relatively moved between a position where the cavity volume is enlarged and a position where the cavity volume is reduced. A molding die characterized by pressure-molding a resin.   A restriction part for restricting relative movement of at least a part of the cavity piece on the runner gate side with respect to the chip holding piece is provided, and the at least some of the cavity pieces are cavity volumes with respect to the chip holding piece pressed against the chip surface. The mold resin is filled in the cavity recess in accordance with the operation of the transfer mechanism at the reduced position, and the cavity is moved to a position where the cavity volume is enlarged by the resin pressure, and the cavity of the at least some cavity pieces is moved by the restricting portion. 2. The mold according to claim 1, wherein when the movement in the direction of expanding the volume is restricted, the cavity piece is relatively moved to a position where the cavity volume is reduced again by a further mold closing operation.   In the second mold, the chip pressing piece is urged and supported by the first urging means with respect to the chase, and the cavity piece is urged and supported by the second urging means, and the cavity The mold metal according to claim 1 or 2, wherein when the piece is pushed back against the urging force of the second urging means by the resin pressure, the movement is restricted by the stopper and moves relative to the chip pressing piece. Type.   4. The cavity piece is relatively moved to a lower surface height of the chip pressed against the chip holding piece by a mold closing operation, and is relatively moved to a height position of the upper surface of the chip by a resin pressure. The mold according to any one of the above.   The mold die according to any one of claims 1 to 4, wherein each of the chip pressing pieces is disposed so as to face a plurality of chips.   The mold according to any one of claims 1 to 5, wherein a reduced pressure space is formed in the mold by a mold closing operation by the first mold and the second mold.   7. The film according to claim 1, wherein a film is sucked and held on the clamp surface including the cavity concave portion of the second mold, and is pressed against the chip surface by the chip pressing piece through the film. The mold according to the description.   The mold according to any one of claims 1 to 7, wherein the clamper is provided with an overflow cavity that accommodates a mold resin overflowing from the cavity recess.   A resin mold apparatus comprising the mold according to claim 1. A resin molding method in which a chip is exposed and transfer molded to a workpiece on which a chip is mounted,
Closing the mold and clamping the workpiece with a clamper that forms the cavity side; and
A step of relatively moving the cavity piece provided around the chip holding piece while pressing the chip holding piece forming the cavity bottom against the chip surface to the first position where the cavity volume is reduced;
A step of pressure-feeding the molten mold resin into the cavity by operating the transfer mechanism;
Retreating to a second position where the cavity piece expands the cavity volume by the resin pressure fully filled in the cavity, and filling the mold resin;
Performing the mold closing operation of the mold while restricting the movement of the cavity piece to the second position, relatively moving the cavity piece to the first position to pressurize resin in the cavity and push it out of the cavity;
A resin molding method comprising:   The resin molding method according to claim 10, wherein the cavity piece is molded by relatively moving to a first position which is a height position of a chip lower surface.

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