JP2009064870A - Mold package - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent warp and crack in a ceramic substrate even when the ceramic substrate is pressed to a heat sink owing to molding pressure while resin is sealed, in a mold package that is formed by attaching the ceramic substrate to a metallic heat sink and by half-molding these elements with a molding resin. <P>SOLUTION: When a force is applied to the ceramic substrate 10 and the heat sink 20 which are mutually attached with each other with each one plate surface 11, 21 in the direction orthogonal to one plate surface 11 of the ceramic substrate 10, the heat sink 20 is bent easier than the ceramic substrate 10 regarding bending where displacement occurs in the relevant orthogonal direction. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a mold package in which a first plate made of a brittle material is bonded to a second plate and half-molded with a mold resin.

  Conventionally, as this type of mold package, a first plate material made of a ceramic substrate or the like and a second plate material made of an island, a heat sink or the like are provided, and one of the two plate materials is bonded together by bonding. At the same time, a material in which both plate materials are sealed with a mold resin so as to expose the other plate surface opposite to the one plate surface that is the bonding surface of the second plate materials has been proposed (for example, , See Patent Document 1).

  Such a mold package molds a ceramic substrate on which a bare IC or electronic component is mounted in a mold IC that maintains a circuit scale that cannot be wired with a lead frame or that includes a plurality of passive components such as ceramic capacitors. Suitable as a configuration.

  Here, the first plate is made of a brittle material such as ceramic. The second plate material is not particularly limited, but is made of a ductile material such as metal. When two plate materials of different materials are bonded together, in order to absorb the stress generated from the difference in thermal expansion coefficient of both plate materials, it is usually bonded using a flexible adhesive such as a silicone adhesive. It is common to do.

  In this type of mold package, as described above, the other plate surface opposite to the one plate surface of the second plate material is exposed from the mold resin, so that the heat dissipation is improved. ing.

The mold package is sealed with a mold resin by a normal transfer mold method, but since it has a large mold structure, a resin film called a resin flash tends to remain on the exposed surface of the second plate. Therefore, in Patent Document 1 described above, this is dealt with by providing a special clamp structure in the mold.
JP-A-8-139218

  However, as described above, providing a special clamp structure in the mold has a problem that, for example, the shape of the clamp portion remains in the completed package. Therefore, the present inventor considered that it is desirable to perform resin sealing with a general mold, and conducted intensive studies.

  As described above, this type of mold package has a large mold structure including a ceramic substrate and the like. Therefore, according to the study of the present inventors, in order to inject the resin so that there is no unfilled portion of the mold resin, it is necessary to inject the resin with a relatively large pressure (for example, 7 to 20 MPa). .

  At the time of this resin sealing, the second plate member out of both the bonded plate members is pressed against the mold, and pressure from the resin, that is, molding pressure is applied from above the first plate member. This molding pressure is an external force applied in a direction perpendicular to the plate surfaces of the two plate members to be bonded. In other words, for the first plate member, the load applied to each plate member along the direction orthogonal to the one plate surface of the first plate member is the molding pressure.

  Here, since the second plate material such as a heat sink is formed by a relatively inexpensive press process or the like, warping of, for example, about 50 μm occurs. On the other hand, the first plate material such as a ceramic substrate is also warped by about 50 μm, for example. When both plate materials having such warpage are bonded together, there is a high possibility that the bonded surfaces of both plate materials are not parallel to each other due to the warpage.

  Therefore, when these two plate materials are bonded together and resin sealing is performed, the first plate material having high brittleness is pressed against the second plate material by the molding pressure, and the first plate material follows the warped shape of the second plate material. The board is warped.

  That is, according to the study of the present inventor, it is found that the first plate member is bent in the direction orthogonal to the one plate surface where the first plate member is bonded, thereby causing the first plate member to crack. It was. In particular, when the directions of warpage of both plate materials are opposite, the bending displacement of the first plate material becomes larger.

  In addition, it is thought that the above-mentioned problem occurs in common with respect to a mold package in which a first plate made of a brittle material is bonded to a second plate and these are half-molded with a mold resin.

  The present invention has been made in view of the above problems, and even when the first plate material made of a brittle material is pressed against the second plate material by the molding pressure at the time of resin sealing, the first plate material is warped and cracked. The purpose is to prevent this.

  In order to achieve the above object, according to the present invention, in the conventional mold package, the second plate material is thicker than the first plate material. It was noted that the first plate material is more likely to warp following the warp shape present in the second plate material.

  That is, according to the present invention, the first plate member (10) is bonded to the first plate member (10) and the second plate member (20) which are bonded to each other on one plate surface (11, 21). When bending is applied in a direction orthogonal to one plate surface (11), the second plate (20) is more easily bent than the first plate (10). It is characterized by things.

  According to that, at the time of resin sealing, a molding pressure is applied from above the first plate material (10) of the two plate materials (10, 20) bonded together. Even if the second plate member (20) is warped due to this deformation, the second plate member (20) is pressed against the mold and approaches a flat shape. Therefore, even if the first plate member (10) made of a brittle material is pressed against the second plate member (20) by the molding pressure during resin sealing, the first plate member (10) is prevented from being warped and cracked. be able to.

  Here, the second plate member (20) is more easily bent than the first plate member (10). The thickness of the second plate member (20) is partially reduced. This can be achieved by providing thin-walled portions (23, 24, 25) (see FIGS. 9 to 12 described later).

  According to this, the second plate member (20) is bent more than the first plate member (10) by partially thinning the second plate member (20) by the thin wall portions (23 to 25). Easy configuration.

  And such a thin part can be made into the slit (23) dented in the thickness direction of the 2nd board | plate material (20) (refer below-mentioned FIGS. 6-8). The slit (23) may be filled with a resin (70, 71) having a higher thermal conductivity than the mold resin (60) (see FIGS. 7 and 8 to be described later). According to it, it is preferable when improving the heat dissipation through the 2nd board | plate material (20) of a 1st board | plate material (10).

  Moreover, the counterbore (25) dented in the thickness direction of the 2nd board | plate material (20) may be sufficient as the said thin part (refer below-mentioned FIGS. 10-12).

  Here, the first plate member (10) is provided with a heating element (30) that generates heat during driving, and the second plate member (20) serves as a heat radiating plate that radiates heat transmitted from the first plate member (10). When configured, the counterbore (25) may be provided in a portion of the second plate member (20) that is separated from the heating element (30) (see FIGS. 11 and 12 described later). .

  According to this, by not providing the counterbore (25) immediately below the heat generating element (30), the thickness of the second plate (20) as the heat radiating plate can be ensured, and in order to ensure heat dissipation. preferable.

  Further, in this counterbore (25), if the counterbore (25) is filled with a resin (70, 71) having a higher thermal conductivity than the mold resin (60) (see FIG. 12 described later), It is preferable when improving the heat dissipation through the 2nd board | plate material (20) of a board | plate material (10).

  Alternatively, the cavity (24) may be provided inside the second plate (20), and the portion including the cavity (24) in the thickness direction of the second plate (20) may be configured as the thin portion. Good (see FIG. 9 described later).

  In addition, the second plate member (20) is more easily bent than the first plate member (10). The second plate member (20) is made of a plurality of layers made of materials having different Young's moduli. This can be achieved by assuming that (2a, 2b) are laminated in the thickness direction (see FIG. 13 described later). By incorporating a material made of a material having a low Young's modulus, the second plate (20) can be bent more easily than the first plate (10).

  In addition, the second plate member (20) is more easily bent than the first plate member (10). The second plate member (20) has a plurality of layers (2c) in the thickness direction. In addition, the plurality of layers may be laminated at the central portion instead of being joined at the peripheral portion of the layers (see FIG. 14 described later). By doing so, the second plate member (20) can be bent more easily than the first plate member (10).

  Further, in this case, by making the plane sizes of the plurality of layers (2c) different from each other, the end surface of the second plate (20) is made uneven by the end portions of the plurality of layers (see FIG. 15 described later). ), The adhesion with the mold resin (60) on the end face of the second plate member (20) can be improved.

  In addition, the second plate member (20) is more easily bent than the first plate member (10) because the second plate member (20) is divided into a plurality of divided portions ( It can also be made by configuring the second plate member (20) as the aggregate 2d) (see FIG. 16 described later). By doing so, the second plate member (20) can be bent more easily than the first plate member (10).

In addition, the second plate (20) is more easily bent than the first plate (10) because the thickness of the first plate (10) is T ₁ and the Young's modulus is E _1. and then, T ₂ the thickness of the second plate (20), when the Young's modulus and E _2, by ^{_{T 1 3 × E 1> T}} 2 3 × E 2, the relationship is established, eggplant You can also.

  If this relationship is satisfied, the second plate (20) can be easily bent more easily than the first plate (10).

In this case, both the first plate member (10) and the second plate member (20) form a plane quadrangle, and the directions of one side of each other are arranged along the same direction. In this case, when the length of the other side adjacent to the one side in the first plate member (10) is W ₁ and the length of the other side adjacent to the one side in the second plate member (20) is W _2. T ₁ ³ × E ₁ × W ₁ > T ₂ ³ × E ₂ × W ₂ is preferably satisfied.

Furthermore, when the length of the one side in the first plate member (10) is L ₁ and the length of the one side in the second plate member (20) is L ₂ , (T ₁ ³ × E ₁ × W ₁ ) / L ₁ > (T ₂ ³ × E ₂ × W ₂ ) / L ₂ is preferably satisfied.

  In each of the above means, the first plate member (10) and the second plate member (20) are made of a flexible adhesive or solder having a Young's modulus lower than both plate members (10, 20), and The adhesive members (70) are preferably bonded to each other via an adhesive member (70) having a thickness smaller than that of the two plate members (10, 20). The adhesive member (70) is a thermosetting adhesive having a Young's modulus of 10 MPa or less. It is more preferable that According to this, the presence of the adhesive member (70) between the first plate (10) and the second plate (20) can be substantially ignored.

  The first plate (10) can be made of ceramic as a brittle material, and the second plate (20) can be made of metal as a ductile material.

  In addition, the code | symbol in the bracket | parenthesis of each means described in the claim and this column is an example which shows a corresponding relationship with the specific means as described in embodiment mentioned later.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiments, parts that are the same or equivalent to each other are given the same reference numerals in the drawings in order to simplify the description.

(First embodiment)
1A and 1B are views showing a mold package 100 according to a first embodiment of the present invention, in which FIG. 1A is a schematic plan view, and FIG. 1B is a schematic cross-sectional view. Note that (a) is a top view of (b), and shows the internal configuration of the mold resin 60 through the mold resin 60.

  The mold package 100 of the present embodiment is broadly divided into a ceramic substrate 10 as a first plate material, a heat sink 20 as a second plate material, and various electronic components 30, 31, 32 mounted on the ceramic substrate 10. A lead frame 50 connected to the ceramic substrate 10 via the wire 40 and a mold resin 60 for sealing these portions 10 to 50 are provided.

  The ceramic substrate 10 is a plate made of ceramic, which is a typical brittle material, and here is an alumina laminated substrate having a planar square shape. The ceramic substrate 10 is configured as a wiring substrate having wiring (not shown).

  The heat sink 20 is made of a ductile material such as metal. Here, the heat sink 20 is a plate made of a metal such as Cu or Fe, which is excellent in heat dissipation as a heat radiating plate, and has a planar square shape. The ceramic substrate 10 and the heat sink 20 are disposed so that one of the plate surfaces 11 and 21 faces each other, and are bonded to each other through the adhesive 70 as an adhesive member. Yes.

  The adhesive 70 is a flexible adhesive mainly composed of a silicone resin, whereby the ceramic substrate 10 and the heat sink 20 are fixed, and heat from the ceramic substrate 10 is dissipated to the heat sink 20. It has become.

  The electronic components 30, 31, and 32 are mounted on the other plate surface 12 of the ceramic substrate 10, and are bonded to the ceramic substrate via a bonding wire such as Al or Au, or a die mount material such as solder (not shown) or conductive adhesive. 10 is electrically connected.

  Here, the electronic component is a heating element 30 that generates heat when driving an analog IC or MOS transistor, an IC chip 31 that generates relatively little heat such as a microcomputer, and a passive component 32 such as a ceramic capacitor, a vibrator, a chip resistor, and a coil. It is shown.

  The lead frame 50 is made of a general lead frame material, and a plurality of lead frames 50 are arranged outside the ceramic substrate 10. Here, the lead frame 50 is a plate material made of Cu, and its thickness is, for example, about 0.25 mm.

  The lead frame 50 and the ceramic substrate 10 are connected and electrically connected by a bonding wire 40 made of Au or Al. The ceramic substrate 10, the heat sink 20, the electronic components 30 to 32, the bonding wires 40, and the lead frame 50 are sealed with a mold resin 60.

  The mold resin 60 is a mold material made of an epoxy resin or the like generally used in the field of electronic devices, and is formed by a transfer mold method. Here, a part of the lead frame 50 protrudes from the mold resin 60 as an outer lead, and the outer lead leads to an electrical connection between the mold package 100 and the outside.

  Further, as shown in FIG. 1A, a suspension lead 51 of a lead frame 50 is fixed to the heat sink 20 by caulking or the like. This is because the heat sink 20 and the lead frame 50 are integrated in a state before molding.

  In addition, the other plate surface 22 opposite to the one plate surface 21 bonded to the ceramic substrate 10 in the heat sink 20 is exposed from the mold resin 60. As a result, heat generated from the heating elements 30 on the ceramic substrate 10 is released from the other plate surface 22 of the heat sink 20 to the outside via the heat sink 20.

  Here, in this embodiment, when the force is applied to both plate members 10 and 20 in a direction orthogonal to one plate surface 11 of the ceramic substrate 10 (vertical direction in FIG. 1B), the two orthogonally intersect. Regarding the bending that is displaced in the direction, the heat sink 20 is more easily bent than the ceramic substrate 10.

  That is, when a force in a direction perpendicular to the plate surface 11 on the bonding side of the ceramic substrate 10, that is, a molding pressure described later, is applied to both the plate materials 10 and 20, the heat sink 20 is more than the ceramic substrate 10. Is easily bent in the orthogonal direction.

  Furthermore, “the heat sink 20 is more easily bent than the ceramic substrate 10 with respect to the bending that is displaced in the orthogonal direction” means that the single ceramic substrate 10 and the single heat sink 20 When the degree to which a single plate is bent in the same direction when a certain load (that is, pressure) is applied in a direction perpendicular to one plate surface of the plate is defined as the degree of bending of the single plate, The degree of bending is that the heat sink 20 is larger than the ceramic substrate 10.

Specifically, in this embodiment, the thickness of the ceramic substrate 10 that is the first plate material is T ₁ , the Young's modulus is E ₁ , the thickness of the heat sink 20 that is the second plate material is T ₂ , and the Young's modulus is When E ₂ is satisfied, the relational expression T ₁ ³ × E ₁ > T ₂ ³ × E ₂ is established. Hereinafter, this relational expression is referred to as relational expression A.

  In the present embodiment, the thicknesses of the ceramic substrate 10 and the heat sink 20 are determined so that this relational expression A is established, or the materials of the ceramic substrate 10 and the heat sink 20 are selected, and the Young's modulus of both the plate materials 10 and 20 is determined. Has been decided. Since this relational expression A is established, the heat sink 20 has a larger degree of bending of the single plate material than the ceramic substrate 10.

  For example, the ceramic substrate 10 is a rectangular plate-shaped alumina laminated substrate obtained by stacking and firing five sheets, and has an overall thickness of 0.8 mm, a planar dimension of 10 mm × 20 mm, and a Young's modulus of 330 GPa. The heat sink 20 is a rectangular plate made of Cu and has a thickness of 0.6 mm, a size of 12 mm × 22 mm, and a Young's modulus of 120 GPa. Although each dimension value and Young's modulus are not limited to this, the above relational expression A is established by adopting each value.

  Next, a method for manufacturing the mold package 100 of this embodiment will be described. First, the electronic components 30 to 32 are mounted on the ceramic substrate 10, the ceramic substrate 10 and the heat sink 20 are bonded together with an adhesive 70, and the ceramic substrate 10 and the lead frame 50 are electrically connected by the bonding wires 40. Connect to.

  Next, this is sealed with a mold resin 60. FIG. 2 is a schematic cross-sectional view showing this molding process. This molding process is performed in a state in which a work is placed on a mold 200 as a mold shown in FIG. The mold 200 is the same as a general one.

  When a workpiece is placed in the cavity of the mold 200 and pressure is applied to the mold resin 60 by the plunger 201, the mold resin 60 is injected into the cavity from the gate 202, the workpiece is sealed with resin, and the mold resin 60 is fed to the air vent 203. Flows out. Thus, sealing with the mold resin 60 is performed, and the mold package 100 of this embodiment as shown in FIG. 1 is completed.

  Here, in the molding process, when the mold resin 60 reaches the air vent 203, the pressure in the cavity increases. That is, the pressure of the plunger 201 becomes the molding pressure F. At this time, the heat sink 20 is pressed by the lower mold of the mold 200, and the molding pressure F is applied in the direction of the heat sink 20 from the other plate surface 12 of the ceramic substrate 10, as shown in FIG.

  Here, FIG. 3 is a model perspective view of the plate members 10 and 20 for showing the dimensions of the respective portions of the both plate members 10 and 20. In FIG. 3, one plate material 10, 20 supported at both ends by two fulcrums K 1 is schematically represented as a single ceramic substrate 20 and a single heat sink 20, and at the center of the plate material 10, 20. A load F corresponding to the molding pressure is applied from above.

  In FIG. 3, the length L of the long side, the thickness T, and the length W of the short side are shown as the dimensions of the two plate members 10 and 20 having a planar rectangular shape. The Young's modulus is E. In this embodiment and each of the embodiments described later, these symbols L, T, W, and E are common, and when distinguishing between the ceramic substrate 10 and the heat sink 20, these symbols L, T, W, and Regarding E, the suffix “1” is attached to the ceramic substrate 10 and the suffix “2” is attached to the heat sink 20.

In this case, the warpage amount of the plate members 10 and 20 due to the load F, that is, the degree of bending of the single plate member is proportional to (F × L ³ ) / (T ³ × W × E). In the molding process, almost the same molding pressure F is applied to the heat sink 20 and the ceramic substrate 10, but in the conventional configuration, the ceramic substrate 10 is more likely to warp than the heat sink 20.

  For example, conventionally, when the heat sink 20 is a material mainly made of Fe, Young's modulus: about 220 GPa, dimensions are thickness: 1.6 mm, short side length: 12 mm, and long side length: 22 mm. When the ceramic substrate 10 is a material mainly composed of alumina, the Young's modulus is about 330 GPa, the dimensions are thickness: 0.8 mm, short side length: 10 mm, and long side length: 10 mm. Thus, conventionally, the relational expression A is not satisfied, and the ceramic substrate 10 is more likely to warp than the heat sink 20.

  At this time, the silicone adhesive 70 is very soft (for example, Young's modulus: 8 MPa) and is considered to be almost compressed when a molding pressure is applied, and the heat sink 20 and the ceramic substrate 10 are pressed. Conceivable.

  Conventionally, the total warpage of the ceramic substrate 10 is actually the sum of the initial warpage of the heat sink 20 and the warpage due to the molding pressure, and further the initial warpage of the ceramic substrate 10. In the case of a brittle material such as ceramic, it is easy to crack if warped even a little. This is specifically shown in FIG.

  FIG. 4 is a diagram showing a state of substrate cracking due to warping of the ceramic substrate 10 due to warpage of the heat sink 20 in the related art. 4A is an example in which the heat sink 20 is warped so as to be convex on the side opposite to the ceramic substrate 10, and FIG. 4B is an example in which the heat sink 20 is warped so as to be convex on the substrate 10 side.

  In any example, the ceramic substrate 10 bends and follows a warp shape of the heat sink 20. Further, when the ceramic substrate 10 is warped so as to protrude in the opposite direction to the heat sink 20, the amount of warpage of the ceramic substrate 10 is increased, and the substrate is likely to be cracked.

With respect to such a conventional problem, the present embodiment pays attention to the fact that the bending degree of the single plate material is proportional to (F × L ³ ) / (T ³ × W × E). On the other hand, the above relational expression A is established for the most dominant thickness T and Young's modulus E of the plate material. Accordingly, the degree of bending of the single plate material is set so that the heat sink 20 is larger than the ceramic substrate 10.

  And according to this embodiment, at the time of the said molding process, although the molding pressure F is applied from the upper part of the ceramic substrate 10 among the both board | plate materials 10 and 20 bonded together, at this time, it deform | transforms previously with the molding pressure F. Is the heat sink 20, and even if the heat sink 20 is warped due to this deformation, the heat sink 20 is pressed against the lower mold of the mold 200 to become a flat shape.

  Therefore, when the molding pressure F is applied to the ceramic substrate 10 made of a brittle material, the heat sink 20 is flat, and even if the ceramic substrate 10 is pressed against the heat sink 20, a force that warps the ceramic substrate 10 is generated. Hateful. Therefore, substrate cracking can be prevented.

  In practice, the influence of the adhesive 70 interposed between the ceramic substrate 10 and the heat sink 20 can be considered, but in order to substantially eliminate this influence, in the present embodiment, the two plate members 10 are used as the adhesive 70. A flexible adhesive having a Young's modulus lower than 20 and a thickness smaller than both plate members 10 and 20, for example, an adhesive made of a silicone resin is used.

  Such an adhesive is a thermosetting adhesive having a Young's modulus of 10 MPa or less, and has a thickness of, for example, about 100 μm. Accordingly, the presence of the adhesive 70 can be substantially ignored between the ceramic substrate 10 and the heat sink 20.

  Further, in the present embodiment, a preferable material of the heat sink 20 for realizing the relational expression A will be further described. About the dimension of the heat sink 20 which satisfies the relational expression A, it can be made into the thing of thickness: 0.6mm and a plane dimension: 12 mm * 22 mm like the example mentioned above.

  As such a heat sink 20, what consists of AlSiC which is a mixture of Al and SiC and whose Young's modulus is 120 GPa, for example is employable. Other examples of the heat sink 20 include Co, Fe, Ni, W, Mo, Al, and Ti. Desirably, Cu, Al, etc. with low Young's modulus are good. Moreover, in order to lower the Young's modulus, the Young's modulus may be apparently lowered by sintering metal or ceramic into a porous material.

(Second Embodiment)
According to the model of FIG. 3, the bending degree of the single plate material, that is, the warpage amount of the plate materials 10 and 20 due to the load F is actually M = (F × L ³ ) / where M is the warpage amount. (4 × T ³ × W × E). Hereinafter, this relational expression is referred to as relational expression B.

In fact, since there is the above relational expression B, the length W ₂ and the length L ₂ of the short side of the heat sink 20 having the rectangular plate shape are reduced. The ceramic substrate 10 may be less warped than the heat sink 20 by increasing the short side length W ₁ and the long side length L ₁ of the ceramic substrate 10.

  Here, as shown in FIG. 1A, both the plate members 10 and 20 form a planar rectangle, and their long sides are arranged along the same direction. That is, the long sides of both plate members 10 and 20 forming a planar rectangle are parallel to each other. As shown in FIG. 3, the bending of both plate members 10 and 20 is the bending in the long side direction.

In such an arrangement of two plate members 10 and 20, the thickness T ₁ of the ceramic substrate 10, E ₁ and Young's modulus, the length of the short side as W _1, T ₂ the thickness of the heat sink 20, the Young's modulus the E _2, when the length of the short side was set to ^{_{W 2, T 1 3 × E}} 1 × W 1> T 2 3 × E 2 × W 2, it is desirable that the relational expression is satisfied. Hereinafter, this relational expression is referred to as relational expression C.

Further, when the length of the long side of the ceramic substrate 10 is L ₁ and the length of the long side of the heat sink 20 is L ₂ , (T ₁ ³ × E ₁ × W ₁ ) / L ₁ > (T ₂ ³ × It is desirable that the relationship E ₂ × W ₂ ) / L ₂ is established. Hereinafter, this relational expression is referred to as relational expression D.

  Note that these relational expressions C and D are not limited to the case where the two plate members 10 and 20 are planar rectangles, but may be squares, parallelograms, or the like. That is, it is only necessary that both plate members 10 and 20 form a planar square, and one side of the ceramic substrate 10 and one side of the heat sink 20 are arranged in the same direction. In the case of the rectangle, the one side in the parallel relationship is the long side, and the short side is the other side adjacent to the one side in the parallel relationship.

W ₁ in the relational expression C is the length of the other side adjacent to the one side in the parallel relation in the ceramic substrate 10, and W ₂ is one side in the parallel relation in the heat sink 20. It is the length of the adjacent other side. Further, L ₁ and L ₂ in the relational expression D are the length of one side in the parallel relation in the ceramic substrate 10 and the length of one side in the parallel relation in the heat sink 20.

  FIG. 5 is a schematic plan view showing an example of a mold package in which the long side and the short side of the ceramic substrate 10 are larger than that of the heat sink 20 in order to satisfy the relational expressions C and D in the second embodiment. FIG. Except for this, the package shown in FIG. 5 is the same as that shown in FIG.

  Even in this embodiment, even when the ceramic substrate 10 made of a brittle material is pressed against the heat sink 20 by the molding pressure during resin sealing, the ceramic substrate 10 can be prevented from warping and cracking.

(Third embodiment)
Further, the ceramic substrate 10 may be a single-layer substrate in which a circuit is formed only on the surface layer by a thick film conductor or the like, or a multilayer substrate obtained by laminating and firing a plurality of sheets in which wiring is formed in the inner layer. The substrate is weaker.

  For example, an alumina laminated substrate may generally be broken by a strain (warp) of 1 μm / mm. Further, generally, when a metal material such as an iron material having a length of about 30 mm is punched out by a press, a warp of about 60 μm is generated, so that a warp larger than 1 μm / mm is initially generated in the heat sink 20. The potential is great.

  For example, with respect to the rectangular plate-shaped ceramic substrate 10 having a size of 10 mm × 20 mm, a thickness of 0.8 mm, and a Young's modulus of 330 GPa, as shown in FIG. Consider the case where a fulcrum to 10 is possible.

  The molding pressure during the molding process is usually 5 MPa to 20 MPa. In this case, when the amount of warpage of the substrate is calculated, warpage of 1 mm or more occurs. Actually, since the heat sink 20 is initially warped only a few tens of μm, the ceramic substrate 10 is also warped only a few tens of μm, but a sufficient amount of deformation occurs to break the substrate.

  In other words, even if the molding pressure is such that the ceramic substrate 10 warps only about several tens of micrometers, for example, the molding pressure is about 0.05 MPa, the substrate is cracked. That is, each of the above embodiments can be applied even to a mold package that seals the mold resin 60 with a molding pressure of 0.05 MPa, which is significantly lower than the conventional pressure, and can be prevented from cracking the substrate. That is.

As described above, since the alumina laminated substrate may generally be cracked by a warp of 1 μm / mm, the relational expression A (T ₁ ³ × E ₁ > T ₂ ³ × E ₂ ) is further exceeded. , T ₁ ³ × E ₁ > 2 × T ₂ ³ × E ₂ is desirable. With this relational expression E, the deformation amount of the ceramic substrate 10 can be reduced to 1 μm / mm or less.

(Fourth embodiment)
FIG. 6 is a schematic sectional view showing a mold package according to the fourth embodiment of the present invention. Also in this mold package, when a force is applied to the two plate members 10 and 20 in a direction perpendicular to the one plate surface 11 of the ceramic substrate 10 (vertical direction in FIG. 6), the bending is displaced in the perpendicular direction. As for, the heat sink 20 is more easily bent than the ceramic substrate 10.

  Here, in the present embodiment, the heat sink 20 is more easily bent than the ceramic substrate 10, that is, the bending degree of a single plate material is larger than that of the ceramic substrate 10. The heat sink 20 is formed by providing a thin portion 23 having a partially reduced thickness.

  Specifically, the thin portion 23 is a slit 23 that is recessed in the thickness direction of the heat sink 20, that is, in a direction substantially orthogonal to one plate surface 11 of the ceramic substrate 10. Here, the slit 23 is a groove recessed in the other plate surface 22 exposed from the mold resin 60 in the heat sink 20.

  Such a slit 23 can be formed by cutting or pressing. Since the heat sink 20 can be partially thinned by the slit 23 as the thin portion, the heat sink 20 can be configured to bend more easily than the ceramic substrate 10.

  Even in this embodiment, even when the ceramic substrate 10 made of a brittle material is pressed against the heat sink 20 by the molding pressure during resin sealing, the ceramic substrate 10 can be prevented from warping and cracking.

  If the slit 23 is made too deep, the heat dissipation performance of the heat sink 20 is lowered. Therefore, it is necessary to select the depth of the slit 23 in consideration of ease of bending. In the present embodiment and the later-described embodiments, when making such a thin portion, the heat sink 20 is preferably made of Fe or the like.

  FIG. 7 is a schematic cross-sectional view showing a mold package as another example of the fourth embodiment. 6, in the mold package shown in FIG. 6, the slit 23 is filled with a resin 71 having a higher thermal conductivity than the mold resin 60, that is, a high thermal conductive resin 71. In this case, after sealing with the mold resin 60, the high thermal conductive resin 71 may be filled.

  Examples of such a high thermal conductive resin 71 include silicone rubber and thermal conductive grease. Further, as the high thermal conductive resin 71, the adhesive 70 may be used as long as the thermal conductivity is higher than that of the mold resin 60.

  In the example shown in FIG. 7, the heat sink 20 is brought into contact with the cooling member 300 through the high thermal conductive resin 71 to improve the heat dissipation of the heat sink 20. Examples of the cooling member 300 include a block body made of Al or the like. In this way, if the slit 23 is filled with the high thermal conductive resin 71, it is preferable to improve heat dissipation from the ceramic substrate 10 through the heat sink 20.

(Fifth embodiment)
FIG. 8 is a schematic sectional view showing a mold package according to the fifth embodiment of the present invention. Similarly to the fourth embodiment, the present embodiment also includes a slit 23 as a thin portion.

  Here, in the fourth embodiment, the slit 23 is provided on the other plate surface 22 of the heat sink 20, but in this embodiment, the slit 23 is formed on the one plate surface 21 that is the mounting surface of the ceramic substrate 10 in the heat sink 20. Is provided.

  In FIG. 8A, the slit 70 is filled with an adhesive 70, and the ceramic substrate 10 and the heat sink 20 are bonded via the adhesive 70. In this case, it is preferable that the adhesive 70 has a higher thermal conductivity than the mold resin 60. In FIG. 8B, the slit 23 is filled with the high thermal conductive resin 71 different from the adhesive 70 in advance, and then the ceramic substrate 10 and the heat sink 20 are bonded via the adhesive 70. ing.

  Further, in FIG. 8C, a slit 23 is also provided on the other plate surface 22 of the heat sink 20 in the case shown in FIG. 8B. That is, the slits 23 are provided on both plate surfaces 21 and 22 of the heat sink 20. In FIG. 8C, the high thermal conductive resin 71 may be filled in the slit 23 on the other plate surface 22 of the heat sink 20.

  Also with the mold package of this embodiment shown in FIG. 8, the heat sink 20 can be configured to bend more easily than the ceramic substrate 10 due to the slits 23 as thin portions. Therefore, even if the ceramic substrate 10 made of a brittle material is pressed against the heat sink 20 by the molding pressure at the time of resin sealing, the ceramic substrate 10 can be prevented from warping and cracking.

(Sixth embodiment)
FIG. 9 is a schematic sectional view showing a mold package according to the sixth embodiment of the present invention. Also in this embodiment, the heat sink 20 is more easily bent than the ceramic substrate 10 by providing the heat sink 20 with a thin portion that is partially thin.

  Here, in this embodiment, as shown in FIG. 9, by providing the cavity portion 24 inside the heat sink 20, the portion including the cavity portion 24 in the thickness direction of the heat sink 20 is configured as a thin portion. I have to. That is, the thickness of the heat sink 20 is reduced by an amount corresponding to the hollow portion 24, and a thin portion is configured.

  For example, the cavity 24 is a hole extending in the direction perpendicular to the paper surface in FIG. 9 and opens to one or both of the both end surfaces of the heat sink 20 located in the direction perpendicular to the paper surface, and can be produced by cutting or the like. It is a thing.

  The hollow portion 24 may not be filled with anything, but here, the high thermal conductive resin 71 similar to the above is filled in the hollow portion 24. Thereby, like the above, the heat dissipation of the heat sink 20 is improved. In addition, if this cavity part 24 is made into the through-hole opened to both the both end surfaces of the heat sink 20 located in the paper surface perpendicular | vertical direction in FIG. 9, if coolant, such as water, is circulated through the cavity part 24, it will cool This leads to improved performance.

  The mold package of this embodiment also has a configuration in which the heat sink 20 is more easily bent than the ceramic substrate 10 due to the hollow portion 24 as a thin-walled portion, and similarly to the above, it is possible to prevent the ceramic substrate 10 from cracking. it can.

(Seventh embodiment)
FIG. 10 is a schematic sectional view showing a mold package according to the seventh embodiment of the present invention. In the present embodiment, the heat sink 20 is bent more easily than the ceramic substrate 10 by providing a counterbore 25 that is recessed in the thickness direction of the heat sink 20 as a thin portion provided in the heat sink 20.

  The counterbore 25 is a recess formed by cutting or pressing. In FIG. 10, (a) shows an example in which the counterbore 25 is formed on the other plate surface 22 of the heat sink 20, and (b) shows the counterbore 25. Further, an example in which the thermal conductivity higher than that of the mold resin 60 described above is filled with the heat conductive resin 71 is shown.

  And also with the mold package of this embodiment, the heat sink 20 is configured to bend more easily than the ceramic substrate 10 due to the counterbore 25 as a thin portion, and the crack of the ceramic substrate 10 can be prevented in the same manner as described above. . Further, in the example in which the counterbore 25 is filled with the high thermal conductive resin 71, the heat dissipation of the heat sink 20 can be expected to be improved.

(Eighth embodiment)
FIG. 11 is a schematic sectional view showing a mold package according to the eighth embodiment of the present invention. In the present embodiment, similarly to the seventh embodiment, a counterbore 25 as a thin portion is provided on the other plate surface 22 of the heat sink 20, and the same effect can be expected.

  Here, in the mold package of the present embodiment, similarly to the one shown in FIG. 1, the ceramic substrate 10 that is the first plate member is provided with a heating element 30 that generates heat during driving. The heat sink 20, which is a plate material, is configured as a heat radiating plate that radiates heat transmitted from the ceramic substrate 10.

  In this embodiment, the counterbore 25 is provided in a portion of the heat sink 20 that is separated from the heat generating element 30. That is, as shown in FIG. 11, the counterbore 25 is not provided immediately below the heat generating element 30, and the counterbore 25 is not provided immediately below the other electronic components 31, 32 with small heat generation, so that the heat sink 20 as a heat radiating plate is provided. The thickness is secured.

  According to the present embodiment, the above-described counterbore 25 can exhibit the effect of preventing cracking of the ceramic substrate 10, and the heat generating element 30 can be prevented from losing heat dissipation, which is preferable for ensuring heat dissipation of the heat sink 20. Can be. Also in this embodiment, although not shown, the counterbore 25 may be filled with a resin having a higher thermal conductivity than the mold resin 60, and in this case, the above-described effect of the resin can be expected.

(Ninth embodiment)
FIG. 12 is a schematic sectional view showing a mold package according to the ninth embodiment of the present invention. This embodiment also includes a counterbore 25 as a thin-walled portion as in the seventh and eighth embodiments.

  Here, in the seventh and eighth embodiments, the counterbore 25 is provided on the other plate surface 22 of the heat sink 20, but in this embodiment, one plate surface 21 that is the mounting surface of the ceramic substrate 10 in the heat sink 20. Counterbore 25 is provided on the surface.

  FIG. 12A is an example in which counterbore 25 is provided on substantially the entire surface of one plate surface 21 of the heat sink 20, and FIGS. 12B and 12C are heating elements on one plate surface 21 of the heat sink 20. By providing the counterbore 25 at a part off 30, the same effect as in the eighth embodiment is aimed.

(10th Embodiment)
FIG. 13 is a schematic sectional view showing a mold package according to the tenth embodiment of the present invention. Also in this mold package, when a force is applied to both plate members 10 and 20 in a direction orthogonal to one plate surface 11 of the ceramic substrate 10 (vertical direction in FIG. 13), the bending is displaced in the orthogonal direction. As for, the heat sink 20 is more easily bent than the ceramic substrate 10.

  Here, in the present embodiment, the heat sink 20 is more easily bent than the ceramic substrate 10, that is, the bending degree of a single plate material is larger than that of the ceramic substrate 10. As shown in FIG. 13, the heat sink 20 is formed by laminating a plurality of layers 2a and 2b made of materials having different Young's moduli in the thickness direction.

  For example, in FIG. 13A, in the heat sink 20 consisting of two layers, the first layer 2a made of Cu is arranged on one plate surface 21 side, and the second layer 2b made of Fe is arranged on the other plate surface 22 side. ing. In this case, if all of the heat sink 20 is made of Fe, there is a sufficient heat capacity, but since the Young's modulus is stiff as 220 MPa, the ceramic substrate 10 is likely to break due to a difference in thermal expansion coefficient.

  Therefore, as shown in FIG. 13A, although the heat capacity is slightly reduced by constituting half of the heat sink 20 with Cu, the heat conductivity is improved, thereby ensuring heat dissipation and the heat sink 20 as a whole. Therefore, the ceramic substrate 10 can be prevented from cracking.

  At this time, the 1st layer 2a and the 2nd layer 2b should just have a different Young's modulus, and are not limited to Fe and Cu. According to the present embodiment, by incorporating a material made of a material having a low Young's modulus, the heat sink 20 can be configured to bend more easily than the ceramic substrate 10. Therefore, according to the present embodiment as well, cracking of the ceramic substrate 10 can be prevented in the same manner as described above.

  Here, the first layer 2a and the second layer 2b in the heat sink 20 may be connected in advance by welding, soldering, adhesive, or the like, or fixed by caulking with each lead frame. There may be. Further, the first layer 2a and the second layer 2b do not have to be laminated, and for example, as shown in FIG. 13B, one may wrap the other. .

(Eleventh embodiment)
FIG. 14 is a schematic sectional view showing a mold package according to the eleventh embodiment of the present invention. Also in this mold package, the heat sink 20 is more easily bent than the ceramic substrate 10 as described above.

  Here, in this embodiment, as shown in FIG. 14, the heat sink 20 is formed by laminating a plurality of layers 2 c in the thickness direction, and the plurality of layers 2 c are bonded to each other at the periphery of the layers. It is assumed that they are joined at the center without.

  Thereby, when the heat sink 20 is bent, the layers 2c are shifted in the peripheral portion of the plurality of layers 2c, so that the heat sink 20 is easily bent. Therefore, the heat sink 20 is more easily bent than the ceramic substrate 10, that is, the degree of bending of a single plate material is larger in the heat sink 20 than in the ceramic substrate 10.

  At this time, each layer 2c consists of Fe etc., for example, is connected in the center part by welding, such as resistance welding and laser welding. In FIG. 14, the welded part is shown as a welded part M. By doing so, the heat sink 20 can be bent more easily than the ceramic substrate 20 as compared with the case where the heat sink 20 is composed of one layer of Fe.

  In FIG. 14, the number of layers is three, but it may be two or four or more. Further, since the plurality of layers 2c are fixed by the mold resin 60, they may not be joined by welding or the like, and in that case, the same effect can be expected.

(Twelfth embodiment)
FIG. 15 is a schematic sectional view showing a mold package according to the twelfth embodiment of the present invention. The present embodiment is a partial modification of the eleventh embodiment in which the heat sink 20 is composed of a plurality of layers 2c welded at the center.

  That is, in this mold package, as shown in FIG. 15, the end surface of the heat sink 20 is made uneven by the end portions of the plurality of layers 2c by making the plane sizes of the plurality of layers 2c different from each other. By carrying out like this, there exists an advantage that the adhesiveness with the mold resin 60 in the end surface of the heat sink 20 improves by the anchor effect, and peeling of the mold resin 60 is prevented.

(13th Embodiment)
16A and 16B are views showing a mold package according to a thirteenth embodiment of the present invention, in which FIG. 16A is a schematic plan view, and FIG. 16B is a schematic cross-sectional view. Note that (a) is a top view of (b), and shows the internal configuration of the mold resin 60 through the mold resin 60. Also in this mold package, the heat sink 20 is more easily bent than the ceramic substrate 10 as described above.

  Here, in the present embodiment, the heat sink 20 is more easily bent than the ceramic substrate 10, that is, the bending degree of a single plate material is larger than that of the ceramic substrate 10. As shown in FIG. 16, the heat sink 20 is configured as an aggregate of a plurality of divided portions 2 d (three in FIG. 16) divided in a plane.

  Here, each divided portion 2d is fixed by, for example, a lead frame and caulking. By dividing in this way, the heat sink 20 that is an aggregate of the divided portions 2d becomes easy to bend at the separated portion, and apparently has a configuration that is easier to bend than the ceramic substrate 10, so that the above-described ceramic The crack of the substrate 10 can be prevented.

(Other embodiments)
Note that the first plate member may be made of a brittle material, and typically includes the above-described ceramic, but other brittle materials may be used if possible. Further, the second plate material may be other than the ductile material represented by the metal described above. That is, the material of the second plate material is not particularly limited as long as the above-described bendability is larger than that of the first plate material.

  Further, although the heat sink 20 as the second plate material is separate from the lead frame 50, an island integrated with the lead frame 50 may be used as the second plate material instead of the heat sink. Also in this case, it is sufficient if the island is more easily bent than the first plate.

  In addition, as an adhesive member that is interposed between the first plate material and the second plate material and adheres them, if the Young's modulus is lower than both plate materials and the thickness is smaller than both plate materials, silicone Solder etc. may be sufficient besides flexible adhesives, such as resin.

It is a figure which shows the mold package which concerns on 1st Embodiment of this invention, (a) is a schematic plan view, (b) is a schematic sectional drawing. It is a schematic sectional drawing which shows the mold process which concerns on the said 1st Embodiment. It is a model-like perspective view of the board | plate material for showing each part dimension in both board | plate materials. It is a figure which shows the mode of the board | substrate crack by the ceramic board | substrate warping conventionally by the curvature of a heat sink. It is a schematic plan view of the mold package which concerns on 2nd Embodiment of this invention. It is a schematic sectional drawing which shows the mold package which concerns on 4th Embodiment of this invention. It is a schematic sectional drawing which shows another example of the said 4th Embodiment. It is a schematic sectional drawing which shows the mold package which concerns on 5th Embodiment of this invention. It is a schematic sectional drawing which shows the mold package which concerns on 6th Embodiment of this invention. It is a schematic sectional drawing which shows the mold package which concerns on 7th Embodiment of this invention. It is a schematic sectional drawing which shows the mold package which concerns on 8th Embodiment of this invention. It is a schematic sectional drawing which shows the mold package which concerns on 9th Embodiment of this invention. It is a schematic sectional drawing which shows the mold package which concerns on 10th Embodiment of this invention. It is a schematic sectional drawing which shows the mold package which concerns on 11th Embodiment of this invention. It is a schematic sectional drawing which shows the mold package which concerns on 12th Embodiment of this invention. It is a figure which shows the mold package which concerns on 13th Embodiment of this invention, (a) is a schematic plan view, (b) is a schematic sectional drawing.

Explanation of symbols

2a ... first layer of heat sink, 2b ... second layer of heat sink, 2c ... multiple layers,
2d-division part, 10-ceramic substrate as the first plate material,
11: One plate surface of the ceramic substrate, 12 ... The other plate surface of the ceramic substrate,
20 ... a heat sink as a second plate material, 21 ... one plate surface of the heat sink,
22 ... the other plate surface of the heat sink, 23 ... a slit as a thin part,
24 ... hollow portion as thin portion, 25 ... counterbore as thin portion, 30 ... heating element,
60 ... mold resin, 70 ... adhesive, 71 ... high thermal conductive resin.

Claims (18)

Comprising a first plate (10) and a second plate (20);
The first plate (10) is made of a brittle material,
One plate surface (11) of the first plate member (10) and one plate surface (21) of the second plate member (20) are bonded together,
The two plate members (10, 20) are sealed with a mold resin (60), and one plate surface (21) bonded to the first plate member (10) in the second plate member (20). In the mold package in which the other plate surface (22) opposite to () is exposed from the mold resin (60),
For the bending that is displaced in the orthogonal direction when a force is applied in the direction orthogonal to the one plate surface (11) of the first plate material (10) with respect to the both plate materials (10, 20), The mold package, wherein the second plate (20) is more easily bent than the first plate (10). The second plate member (20) is more easily bent than the first plate member (10).
The mold package according to claim 1, wherein the second plate member (20) is provided with a thin portion (23, 24, 25) having a partially reduced thickness. The mold package according to claim 2, wherein the thin portion is a slit (23) recessed in the thickness direction of the second plate (20). The mold package according to claim 3, wherein the slit (23) is filled with a resin (70, 71) having a higher thermal conductivity than the mold resin (60). The mold package according to claim 2, wherein the thin portion is a counterbore (25) recessed in a thickness direction of the second plate member (20). The first plate (10) is provided with a heating element (30) that generates heat during driving,
The second plate (20) is configured as a heat radiating plate that radiates heat transmitted from the first plate (10),
6. The mold package according to claim 5, wherein the counterbore (25) is provided in a portion of the second plate member (20) that is detached from the heating element (30). The mold package according to claim 5 or 6, wherein the counterbore (25) is filled with a resin (70, 71) having a higher thermal conductivity than the mold resin (60). A cavity (24) is provided inside the second plate (20), and a portion including the cavity (24) in the thickness direction of the second plate (20) serves as the thin portion. It is comprised, The mold package of Claim 2 characterized by the above-mentioned. The second plate member (20) is more easily bent than the first plate member (10).
The said 2nd board | plate material (20) is made | formed by making the several layer (2a, 2b) which consists of a material from which Young's modulus differs in the thickness direction, It is made | formed. The mold package described. The second plate member (20) is more easily bent than the first plate member (10).
The second plate member (20) is formed by laminating a plurality of layers (2c) in the thickness direction, and the plurality of layers are joined at the central portion without being joined at the periphery of the layers. The mold package according to claim 1, wherein the mold package is formed by: The planar surfaces of the plurality of layers (2c) are different from each other, whereby the end surface of the second plate member (20) has an uneven shape due to the end portions of the plurality of layers. The mold package according to 10. The second plate member (20) is more easily bent than the first plate member (10).
The said 2nd board | plate material (20) is made | formed by comprising the said 2nd board | plate material (20) as an aggregate | assembly of the some division | segmentation part (2d) which divided | segmented planarly. The mold package according to 1. The second plate member (20) is more easily bent than the first plate member (10).
Said first plate (10) having a thickness of the T _1, the Young's modulus and E _1, the thickness T ₂ of the second plate (20), when the Young's modulus and E _2, T ₁ ³ × _2. The mold package according to claim 1, wherein the mold package is formed by satisfying a relationship of E ₁ > T ₂ ³ × E ₂ . The first plate member (10) and the second plate member (20) both form a plane quadrangle, and the directions of one side of each other are arranged along the same direction,
W ₁ the length of the other side adjacent to the one side in the first plate (10), when the length of the other side adjacent to the one side in the second plate member (20) has a W ₂ The mold package according to claim 13, wherein a relationship of T ₁ ³ × E ₁ × W ₁ > T ₂ ³ × E ₂ × W ₂ is established. When the length of the one side in the first plate member (10) is L ₁ and the length of the one side in the second plate member (20) is L ₂ , (T ₁ ³ × E ₁ × W The mold package according to claim 14, wherein a relationship of ₁ ) / L ₁ > (T ₂ ³ × E ₂ × W ₂ ) / L ₂ is established. The first plate member (10) and the second plate member (20) are made of a flexible adhesive or solder having a Young's modulus lower than that of the two plate members (10, 20) and the both plate members (10, The mold package according to any one of claims 1 to 15, wherein the mold package is bonded through an adhesive member (70) having a thickness smaller than that of 20). The mold package according to claim 16, wherein the adhesive member (70) is a thermosetting adhesive having a Young's modulus of 10 MPa or less. The mold according to any one of claims 1 to 17, wherein the first plate (10) is made of ceramic as a brittle material, and the second plate (20) is made of metal as a ductile material. package.

Images