JP5174874B2 - Compression molding die and compression molding method - Google Patents

Description

  The present invention relates to a compression mold used for resin sealing of an electronic component mounted on a substrate, and a compression molding method using the same.

2. Description of the Related Art Conventionally, an electronic component such as a semiconductor chip mounted on a substrate is resin-sealed and compression-molded using a resin-sealing molding apparatus having a compression molding die composed of both upper and lower molds. . An example of a compression mold used for such resin sealing molding is shown in FIG. In the example of the compression mold 50 shown in this figure, the substrate 60 on which the electronic component 61 is mounted is held on the upper mold 51. The lower mold 52 includes a frame member 55 and a bottom member 54 that moves up and down within the frame member 55, and the resin 25 is supplied to a space (cavity 53) surrounded by the frame member 55 and the bottom member 54.
In the compression molding die 50, first, the substrate 60 is fixed to the lower surface of the upper die 51 so that the mounting surface of the electronic component 61 faces the lower die 52. Next, the lower mold 52 is raised to bring the lower surface of the upper mold 51 into close contact with the upper surface of the lower mold 52. Subsequently, the bottom member 54 is raised, and the electronic component 61 is immersed in the molten resin 25 in the cavity 53. The molten resin 25 in the cavity 53 is maintained for a predetermined time while being compressed by the bottom member 54, and the resin is cured. Thereby, resin sealing molding by compression molding is completed, and the electronic component 61 on the substrate 60 is resin-sealed.

  In the compression molding die 50 as described above, the bottom surface member 54 moves up and down with respect to the frame member 55, so that there is a gap between the frame member 55 and the bottom surface member 54. Although such a gap is designed to be as small as possible, when the molten resin 25 in the cavity 53 is pressurized, the molten resin 25 enters the gap. Therefore, in order to prevent the resin from entering the gap between the frame member 55 and the bottom member 54, the entire mold surface of the lower mold 52 is generally covered with a release film 56 such as a fluororesin ( (See FIG. 7). The release film 56 is pressed by a frame-shaped intermediate plate 57 having an opening larger than the opening of the cavity 53.

  However, since the release film needs to be replaced every time it is molded, a large amount of waste is generated and the load on the environment is great. Moreover, since the disposal cost is high, the manufacturing cost of the product (semiconductor package) becomes high. Further, when a release film is used, the compression mold is an upper mold 51, a lower mold 52, and an intermediate plate 57, and the release film 56 is supplied between the lower mold 52 and the intermediate plate 57. Therefore, the structure of the compression mold and the compression molding apparatus is complicated.

  In view of this, the present applicant has conventionally proposed a compression mold that enables compression molding without using a release film (see Patent Document 1). In this compression mold, as shown in FIG. 8, a frame member surrounding the bottom member 54 is divided for each side of the bottom member 54, and each frame member 58 is pressed against the bottom member 54 by an elastic member such as a spring. Accordingly, the gap can be made as small as possible while allowing the bottom surface member 54 to move up and down, and a release film becomes unnecessary.

  Furthermore, in Patent Document 1, as shown in FIG. 9, a groove is provided in the peripheral edge of the upper surface of the bottom member 54, and a fluororesin sealing member 59 is previously fitted therein, and each frame pressed by the elastic member. It is also disclosed that the member 58 is brought into contact with the sealing member 59. As a result, the frictional force generated on the contact surface is reduced, and the bottom member 54 easily slides up and down with respect to the frame member 58.

JP 2008-296382 A

  In the compression mold of Patent Document 1, an elastic pressing mechanism for elastically pressing the divided frame members 58 against the bottom surface member 54 is necessary. This elastic pressing mechanism is also necessary when the sealing member 59 is fitted to the bottom member 54 as shown in FIG. Therefore, the compression mold of Patent Document 1 has a complicated mold structure and a high manufacturing cost as compared with a general compression mold.

  The present invention has been made in view of these points, and the object of the present invention is to enable compression molding without using a release film and to simplify the structure of the compression mold. It is an object of the present invention to provide a compression mold and a compression molding method capable of achieving the above.

The compression mold according to the present invention made to solve the above problems is
An upper mold, and a lower mold comprising a frame member and a bottom member that can be moved up and down within the frame member, and the electronic component on the substrate held by the upper mold In a compression molding die of an electronic component used for sealing by compression molding of a resin material supplied in a cavity surrounded by the frame member and the bottom surface member of the mold,
The bottom surface member has a groove provided on the outer peripheral edge of the upper surface over the entire circumference, and the inner peripheral surface of the groove is recessed closer to the inner periphery than the opening of the groove on the upper surface of the bottom surface member. The undercut part currently formed is formed.

  In the compression molding die, it is desirable that one or a plurality of recesses be formed on the upper surface of the bottom member.

The compression molding method according to the present invention made to solve the above problems is as follows.
A method of resin-sealing an electronic component mounted on a substrate using the compression molding die by compression molding,
a) supplying a sealing resin material into the cavity and compressing the dummy molded product;
b) The compression molding is performed by separating the dummy molded product compression-molded with the sealing resin material from the groove filling member formed in the groove when the sealing resin material entering the groove is cured. Removing from the mold,
c) supplying a sealing resin material into the cavity in a state where the groove filling member is filled in the groove and sealing the electronic component on the substrate by compression molding;
d) separating the substrate sealed with the sealing resin material from the groove filling member and removing the substrate from the compression mold.

  In the compression molding method, the sealing resin material is preferably slidable.

  In the compression molding method, the sealing resin material is a resin filled with a filler, and the sealing resin material is made of only the resin, or the resin is more than the sealing resin material. It is desirable that the filler is mixed in a small proportion.

  In the compression molding die and the compression molding method according to the present invention, the sealing resin material is supplied into the cavity to compress the dummy molded product, and at the same time, the groove filling member is compression molded by the sealing resin material entering the groove. Since the groove part has an undercut part and the groove filling member cannot be punched as it is, when the dummy molded product is removed from the cavity, the dummy molded product and the groove filling member are separated. As a result, the groove filling member remains in the groove formed on the entire outer peripheral edge of the upper surface of the bottom member, thereby completely closing the gap between the bottom member and the frame member. Therefore, when the sealing resin material is next supplied into the cavity and the electronic component on the substrate is resin-sealed, the sealing resin material does not enter the gap. Therefore, it is not necessary to use a release film or a compression mold having a complicated structure in order to prevent the resin from entering the gap.

  After the sealing resin material is cured, when the dummy molded product and the groove filling member are separated, if they break in the groove, the sealing resin material enters the fracture surface at the time of subsequent molding, resulting in a sealed molded product. Resin burrs are generated. When this sealed molded product is placed on the placement surface with the resin side facing down, the resin burr breaks and resin waste tends to be generated. At this time, if a concave portion is provided in advance on the upper surface of the bottom surface member and a convex portion corresponding to the concave portion is formed in the sealed molded product, the sealing molding is performed when the sealed molded product is placed as described above. The product is supported by a convex portion, and the convex portion makes it difficult for the resin burr to contact the mounting surface. Therefore, it is possible to prevent the resin burrs from breaking and generating resin waste.

  As the sealing resin material, a material having slidability is preferably used. Thereby, the bottom member can be favorably slid with respect to the frame member while closing the gap between the frame member and the bottom member. In addition, when using a resin filled with a filler as a sealing resin material, a sealing resin material having a sliding property can be made of only that resin, or a small amount of filler can be mixed into the resin. It is preferable to use what was made. As a result, even if the groove filling member made of the sealing resin material is lost and the fragment is mixed in the sealing molded product, it is the same as the substance contained in the sealing resin material. Has little effect on properties.

Sectional drawing of the compression molding die which is one Embodiment of this invention. It is a figure explaining the compression molding method which is one Embodiment of this invention, (a) is before shaping | molding of the resin material for sealing, (b) is shaping | molding of the resin material for sealing, (c) is the resin material for sealing. After molding, (d) is before molding of the sealing resin material, (e) is during molding of the sealing resin material, (f) is a cross-sectional view of the compression mold after molding of the sealing resin material. is there. It is a figure explaining the torn surface of a groove part filling member, (a) is the position where the whole torn surface is in a position lower than the upper opening of a groove part, (b) is the position in which the center of a torn surface is lower than an upper opening In the case, (c) is an enlarged cross-sectional view of the vicinity of the fracture surface when the edge of the fracture surface is at a position lower than the upper opening, and (d) is an enlarged sectional view in the vicinity of the fracture surface when the entire fracture surface is at a position higher than the upper opening. Sectional drawing of a sealing molded product. Sectional drawing of the modification of a recessed part and a sealing molded product. It is a figure explaining the conventional compression molding die, (a) is sectional drawing before shaping | molding, (b) is sectional drawing during shaping | molding. It is a figure explaining the conventional compression molding die which uses a release film, (a) is sectional drawing before shaping | molding, (b) is sectional drawing during shaping | molding. It is a figure explaining the conventional compression molding die using the divided | segmented frame member, (a) is a top view of a frame member and a bottom face member, (b) is sectional drawing of a compression molding die. The expanded sectional view of the sealing member vicinity of the conventional compression molding type | mold using the divided | segmented frame member.

  Hereinafter, a compression mold and a compression molding method according to an embodiment of the present invention will be described with reference to the drawings. The compression mold 10 of the present embodiment includes an upper mold 11 that holds a substrate on which an electronic component such as a semiconductor chip is mounted on a lower surface, and a lower mold 12 that is disposed to face the upper mold 11 (see FIG. 1). ). The lower mold 12 includes a frame member 15 and a bottom member 14 that can move up and down within the frame member 15, and a space surrounded by the frame member 15 and the bottom member 14 serves as a cavity 13.

  A substrate fixing mechanism 111 for holding the substrate is provided on the lower surface of the upper mold 11. In the present embodiment, the substrate fixing mechanism 111 is a mechanism that engages the substrate with the upper mold 11 by a hook, but may be a mechanism that sucks and fixes the substrate by suction from above.

  A groove 141 is provided on the outer peripheral edge of the upper surface of the bottom member 14 over the entire circumference. Therefore, the groove 141 exists on the sliding surface of the bottom member 14 and the frame member 15. Under the inner peripheral surface 145 of the groove portion 141, an undercut portion 142 is formed which is recessed on the inner peripheral side from the opening of the groove portion 141 (hereinafter referred to as “upper opening 146”) on the upper surface of the bottom surface member 14. Yes. Thereby, it can prevent that the resin material (groove part filling member 24 mentioned later) which penetrates into the groove part 141 from the cavity 13, and hardens | cures there escapes to the cavity 13 side. In addition, the undercut part 142 should just be provided in positions other than the upper end in the internal peripheral surface 145 of the groove part 141, for example, may be provided in the center part of the internal peripheral surface 145. Further, the undercut portion is not limited to the concave shape as shown in FIG. 1, and may be one in which the inner peripheral surface 145 of the groove portion 141 is inclined in a reverse taper shape.

  A recess 143 is provided on the upper surface of the bottom member 14. The depth of the recess 143 is set to be larger than the protruding height of the resin burr generated by the sealing resin material that has entered the vicinity of the upper opening 146 of the groove 141. Details of the resin burr and its protruding height will be described later, but the protruding height of the resin burr can be confirmed by actually performing a molding test.

  Next, a compression molding method using the compression mold 10 will be described (see FIG. 2). First, the compression mold 10 is opened, and the dummy substrate 63 on which no electronic component is mounted is fixed to the lower surface of the upper die 11 by the substrate fixing mechanism 111 (see FIG. 2A). At the same time, the sealing resin material 20 is supplied into the cavity 13. As the sealing resin material 20, it is desirable to use a material excellent in slidability and releasability. The sealing resin material 20 may be in the form of powder or liquid when supplied to the cavity 13, but in the case of powder, it is melted in the cavity 13 to form a liquid.

  Next, as shown in FIG. 2B, the frame member 15 and the bottom surface member 14 are raised so that the upper surface of the frame member 15 is in close contact with the lower surface of the dummy substrate 63, and the cavity 13 is filled with the sealing resin material 20. . In this state, while the sealing resin material 20 is compressed by the bottom member 14, the sealing resin material 20 is cured at a predetermined temperature for a predetermined time. As a result, the dummy molded product 21 composed of the dummy substrate 63 and the sealing resin material 20 is formed. At this time, the sealing resin material 20 has entered the groove portion 141 and is cured in a state where the gap between the bottom surface member 14 and the frame member 15 is completely closed. Thereby, the groove filling member 24 is formed in the groove 141.

  After the sealing resin material 20 is cured, the lower mold 12 is lowered while the dummy molded product 21 is fixed to the upper mold 11 by the substrate fixing mechanism 111, and the dummy molded product 21 is removed from the cavity 13 (FIG. 2 ( c)). At this time, the groove filling member 24 hardened in the groove 141 is torn off from the resin portion of the dummy molded product 21 and separated and remains in the groove 141. As a result, the cavity 13 is in a state where the groove 141 is closed by the groove filling member 24. Thereafter, the substrate fixing mechanism 111 of the upper mold 11 is operated to release the fixing of the dummy molded product 21, and the dummy molded product 21 is removed from the upper mold 11.

  Next, as shown in FIG. 2 (d), the substrate 60 with the electronic component 61 mounted on the lower surface of the upper mold 11 is fixed by the substrate fixing mechanism 111 so that the electronic component mounting surface faces the lower mold 12. . Similarly, as shown in FIG. 2D, the sealing resin material 22 is supplied to the cavity 13 in a state where the groove 141 is filled with the groove filling member 24. The sealing resin material 22 is a resin for resin-sealing the electronic component 61, and is, for example, an epoxy resin. Similarly to the sealing resin material, the sealing resin material may be in the form of powder or liquid when supplied to the cavity 13, but in the case of powder, it is melted in the cavity 13 to be liquid.

Next, as shown in FIG. 2 (e), the frame member 15 and the bottom surface member 14 are raised to bring the upper surface of the frame member 15 into close contact with the lower surface of the substrate 60, and the electronic component 61 is sealed with the sealing resin in the cavity 13. Soak in material 22. In this state, the sealing resin material 22 is compressed by the bottom member 14. At this time, since the groove part 141 is closed with the groove part filling member 24, the sealing resin material 22 does not enter the back part of the groove part 141. However, the sealing resin material 22 may enter the vicinity of the upper opening 146 of the groove 141 depending on the position of the fracture surface that is the upper surface of the groove filling member 24. For example, as shown in FIG. 3A, when the entire fracture surface of the groove filling member 24 is at a position lower than the upper opening 146 of the groove 141 (the upper surface 144 of the bottom member 14), the sealing resin material 22 is used. Enters from its upper opening 146 to its fracture surface. In addition, as shown in FIGS. 3B and 3C, sealing is performed even when a part of the fracture surface of the groove filling member 24 (a central part or a peripheral part) is located at a position lower than the upper opening 146 of the groove 141. The stopping resin material 22 enters the vicinity of the upper opening 146 of the groove 141. 3D, when the entire fractured surface of the groove filling member 24 is located higher than the upper opening 146, the sealing resin material 22 does not enter the groove 141.
Then, the state shown in FIG. 2E is maintained at a predetermined temperature for a predetermined time to cure the sealing resin material 22. Thereby, the sealing molded product 23 in which the electronic component 61 is sealed with the sealing resin material 22 is formed.

  After the sealing resin material 22 is cured, the lower mold 12 is lowered while the sealing molded product 23 is fixed to the upper mold 11 by the substrate fixing mechanism 111, and the sealing molded product 23 is removed from the cavity 13. At this time, the groove filling member 24 in the groove 141 is separated from the sealing molded product 23 and remains in the groove 141. Thereafter, the substrate fixing mechanism 111 is operated to release the fixing of the sealing molded product 23, and the sealing molded product 23 is removed from the upper mold 11 (see FIG. 2 (f)).

  As shown in FIG. 4, a raised portion (convex portion 231) is formed at the center of the resin-side surface of the taken-out sealing molded product 23 as shown in FIG. 4. The convex portion 231 is formed by transferring the shape of the concave portion 143 of the bottom surface member 14 to the sealing resin material 22. In addition, the broken line in a figure shows the surface corresponding to the upper surface 144 of the bottom face member 14 in the sealing molded product 23. FIG. 3A, 3B, and 3C, when the sealing resin material 22 has entered the upper opening 146 of the groove 141, the same direction as the protruding direction of the convex portion 231. A resin burr 232 is formed on the substrate. Here, the height of the convex portion 231 corresponds to the depth of the concave portion 143, and the depth of the concave portion 143 is set to be deeper than the protruding height of the resin burr 232 as described above. The height of the convex portion 231 is higher than the protruding height of the resin burr 232. That is, the tip of the resin burr 232 does not protrude below the convex portion 231. Thereby, when the sealing molded product 23 is placed on the placement surface with the resin side facing down, the resin burr 232 does not contact the placement surface. Therefore, it is possible to prevent the resin burr 232 from being broken and generating resin waste.

  Comparing the compression molding method of the present embodiment with the conventional compression molding method using a release film, in the conventional resin sealing method using a release film, if the stroke of the bottom member is increased, the release film is wrinkled or torn. Is likely to occur. Therefore, it is not suitable for compression molding of a relatively thick semiconductor package (for example, a semiconductor package having a thickness of about 5 mm with a built-in power transistor for controlling a large current). On the other hand, in the compression molding method of this embodiment, since the release film is not used, the above trouble does not occur. Therefore, it is suitable not only for compression molding of a general semiconductor package having a thickness of about 1 mm but also for compression molding of a relatively thick semiconductor package having a thickness of 5 mm or more.

  Note that the above embodiment is merely an example, and it is apparent that appropriate modifications and corrections can be made in accordance with the spirit of the present invention. For example, a plurality of recesses 143 provided on the upper surface of the bottom member 14 may be provided as shown in FIG. Also in this case, an effect of preventing the resin burr 232 from being broken by the convex portion 231 formed on the sealed molded product 23 is produced. In this case, the amount of the sealing resin material used can be reduced as compared with the sealing molded product of the above embodiment.

Generally, as a resin material for sealing an electronic component, a resin filled with a filler at a high rate (for example, about 70 to 90%) is used. However, as a resin material for sealing, only a resin of a sealing resin material is used. The material may be used. Further, as the sealing resin material, a material in which a filler is mixed in a small proportion (for example, a proportion of 5% or less) may be used.
Specifically, for example, when an epoxy resin material filled with a filler is used as a sealing resin material, a resin material (filler is removed from the epoxy resin material as a sealing resin material). An encapsulating resin material not included) can be used.
When an epoxy resin material is used as the sealing resin material, an epoxy resin (base resin) can be used as the sealing resin material.
Further, as the sealing resin material, a resin (for example, a fluorine-based sealing agent) different from the resin contained in the sealing resin material may be used.

  The depth of the recess 143 may be set to be equal to or greater than the depth of the groove 141 in consideration of the fact that the protruding height of the resin burr 232 does not exceed the depth of the groove 141. In this case, the depth of the recess 143 can be set without performing a molding test. The compression mold 10 may be a metal mold (mold) or a mold other than metal (for example, a resin mold or a ceramic mold).

DESCRIPTION OF SYMBOLS 10, 50 ... Compression molding die 11, 51 ... Upper die 111 ... Substrate fixing mechanism 12, 52 ... Lower die 13, 53 ... Cavity 14, 54 ... Bottom member 141 ... Groove 142 ... Undercut part 143 ... Concave 144 ... Bottom member The upper peripheral surface 145 of the inner peripheral surface 146 ... the upper openings 15, 55, 58 ... the frame member 20 ... the sealing resin material 21 ... the dummy molded product 22 ... the sealing resin material 23 ... the sealed molded product 24 ... the groove filling member 231 ... Projection 232 ... Resin burr 25 ... Molten resin 56 ... Release film 57 ... Intermediate plate 59 ... Sealing member 60 ... Substrate 61 ... Electronic component 63 ... Dummy substrate

Claims (5)

An upper mold, and a lower mold comprising a frame member and a bottom member that can be moved up and down within the frame member, and the electronic component on the substrate held by the upper mold In a compression molding die of an electronic component used for sealing by compression molding of a resin material supplied in a cavity surrounded by the frame member and the bottom surface member of the mold,
The bottom surface member has a groove provided on the outer peripheral edge of the upper surface over the entire circumference, and the inner peripheral surface of the groove is recessed closer to the inner periphery than the opening of the groove on the upper surface of the bottom surface member. A compression molding die characterized in that an undercut portion is formed.   The compression molding die according to claim 1, wherein one or a plurality of recesses are formed on an upper surface of the bottom member. A method of resin-sealing an electronic component mounted on a substrate using the compression molding die according to claim 1 or 2 by compression molding,
a) supplying a sealing resin material into the cavity and compressing the dummy molded product;
b) The compression molding is performed by separating the dummy molded product compression-molded with the sealing resin material from the groove filling member formed in the groove when the sealing resin material entering the groove is cured. Removing from the mold,
c) supplying a sealing resin material into the cavity in a state where the groove filling member is filled in the groove and sealing the electronic component on the substrate by compression molding;
d) a step of separating the substrate sealed with the sealing resin material from the groove filling member and removing it from the compression mold.   The compression molding method according to claim 3, wherein the sealing resin material has slidability.   The sealing resin material is a resin filled with a filler, and the sealing resin material is made of only the resin, or the filler is mixed into the resin in a smaller proportion than the sealing resin material. The compression molding method according to claim 3 or 4, wherein the compression molding method is used.

Images