JP4219448B2 - Semiconductor device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a semiconductor device that implements an intelligent power module and the like, and more particularly to the structure of the package.
[0002]
[Prior art]
First, taking the intelligent power module mentioned above as an example, the conventional assembly structure of a semiconductor device is shown in FIGS. In the figure, 1 is a resin case (resin molded product) of a terminal-integrated package, 2 is an upper lid of the resin case 1, and 3 is a main circuit terminal (input) formed on one side wall portion of the resin case 1 and drawn upward. Terminals +,-, output terminals U, V, W) and 4 are control signal terminals inserted into the other side wall portion of the resin case 1 and drawn upward. The main circuit block 5 and the control circuit block 6 having the structure are incorporated.
[0003]
Here, the main circuit block 5 has a configuration in which a power element (IGBT, freewheeling diode, etc.) 5a is mounted on an insulating substrate (aluminum insulating substrate, direct bonding copper (DBC) substrate, etc.) 5b, and resin. The first adhesive is between the peripheral edge of the insulating substrate 5b and the resin case side, and is fitted into a hole 1a for mounting the substrate opened on the bottom surface of the case 1 (a square hole corresponding to the outer dimension of the insulating substrate 5a). (Silicon adhesive) 7 is fixed. On the other hand, the control circuit block 6 has a configuration in which a circuit element 6a such as an IC is mounted on a printed circuit board 6b. The concave pedestal surface 1 formed on the bottom wall of the resin case 1 side by side on the main circuit block 5 ( A second adhesive (such as an epoxy-based adhesive) 8 is fixed on the printed circuit board.
[0004]
The main circuit block 5 and the main circuit terminal 3, the control circuit block 6 and the control signal terminal 4, and the main circuit block 5 and the control circuit block 6 are connected by bonding wires 9. An upper cover 2 is attached after sealing resin (silicone gel) 10 is filled inside the resin case 1.
Next, the procedure of the process of assembling the main circuit block 5 to the resin case 1 will be described in detail. That is, a stepped seat surface 1a-1 is formed on the lower surface side periphery of the hole 1a opened in the bottom surface of the resin case 1, and after applying the liquid adhesive 7 to the entire circumference of the seat surface, an insulating substrate is formed. The adhesive 7 is heat-cured while fitting 5b from the lower surface side and applying pressure. On the other hand, in order to fix the control circuit block 6 to the pedestal surface 1b of the resin case 1, after applying an appropriate amount of the liquid adhesive 8 to the concave pedestal surface 1b, the printed circuit board 6b is overlaid from above and bonded while applying pressure. Agent 8 is cured by heating.
[0005]
[Problems to be solved by the invention]
By the way, in the package structure of the conventional semiconductor device described above, the following problems are derived particularly when the main circuit block and the control circuit block are fixed to the resin case with an adhesive.
(1) In order to efficiently dissipate the heat generated from the power element 5a with the energization of the main circuit block 5 to the outside through the cooling fin, the back surface of the resin case 1 and the heat dissipating surface (back surface) of the insulating substrate 5b The relative height management is very important. That is, in the assembled state of the semiconductor device shown in FIG. 6, if the back surface of the insulating substrate 5 b is retracted by 0.1 mm or more from the back surface of the resin case 1, the back surface of the insulating substrate 5 b is not affected even if heat transfer grease is applied. It is difficult to adhere to the cooling fins, and the heat dissipation of the insulating substrate 5b decreases. On the other hand, when the back surface of the insulating substrate 5b protrudes 0.1 mm or more from the back surface of the resin case 1, the resin case 1 is fastened to the cooling fins through bolts through the bolt holes 1c opened at the left and right ends. In addition, excessive stress may be generated in the insulating substrate 5b, causing cracks and cracks in the substrate.
[0006]
For this reason, as shown in FIG. 6B, when assembling the semiconductor device, the step ΔS between the back surface of the insulating substrate 5b of the main circuit block 5 and the back surface of the resin case 1 has the tolerance (0.1 mm) described above. High assembling accuracy is required. In this case, if the supply amount of the adhesive applied to the stepped seating surface 1a-1 in the bonding process is large and the insulating substrate 5b is pressed against the resin case 1, the back surface of the insulating substrate 5b becomes the resin case 1. The adhesive 7 is cured while protruding downward from the back surface of the adhesive. Conversely, if the insulating substrate 5b is pressed too strongly against the resin case 1, the layer thickness of the adhesive 7 becomes extremely thin and a predetermined adhesive strength cannot be obtained, and the insulating substrate 5b is located on the inner side of the back surface of the resin case 1. The excess liquid adhesive 7 protrudes from the joint surface due to pressurization and goes around the back surface of the insulating substrate 5b and adheres to the heat transfer surface. For this reason, an extra work process for wiping off the adhesive protruding on the back surface side is necessary as a cleanup process.
[0007]
As described above, in the conventional structure, the assembly accuracy in the bonding process for fixing the main circuit block 5 to the resin case 1 is likely to vary, and this is a bottleneck in maintaining the quality of the product.
(2) Further, in the assembly process of fixing the control circuit block 6 to the pedestal surface 1b of the resin case 1 with the adhesive 8, if the amount of the adhesive 8 applied to the concave pedestal surface 1b is large, the printed circuit board 6b is mounted on the pedestal. When pressed against the surface 1b, excess adhesive 8 protrudes from the peripheral edge of the printed circuit board 6b, and in particular, the adhesive is on the peripheral wall side of the resin case 1 (here, the inner tip of the control signal terminal 4 protrudes). If it protrudes, it adheres to the surface of the circuit pattern of the control signal terminal 4 and the printed circuit board 5b, and this causes a problem that the bonding failure of the wire 9 is caused and the reliability is remarkably lowered.
[0008]
The present invention has been made in view of the above points, and its object is to improve the semiconductor in order to solve the above-mentioned problems and to obtain stable quality in the bonding process in which the main circuit block and the control circuit block are assembled to the resin case. An object is to provide an apparatus.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, according to the present invention, a main circuit block and a control circuit block are incorporated into a terminal-integrated resin case in which a main circuit terminal and a control signal terminal are insert-molded on a peripheral wall, and are bonded with bonding wires. The main circuit block is an internally connected semiconductor device, and the main circuit block is a stepped seating surface formed by fitting an insulating substrate from below into a substrate mounting hole opened on the bottom surface of the resin case and forming a peripheral edge on the back surface side peripheral edge of the substrate mounting hole. Adhering with an adhesive, the control circuit block is the one in which the printed circuit board is superimposed on the concave pedestal surface formed on the bottom of the resin case and fixed with an adhesive,
(1) A standoff functioning as a spacer for securing a constant thickness of the adhesive when the main circuit block is pressure-bonded to the stepped seating surface of the board mounting hole is dispersedly formed . A tapered chamfer that extends toward the back side of the resin case is formed over the entire circumference of the stepped seating surface, and excess adhesive is applied between the chamfered portion and the insulating substrate when the main circuit block is bonded. Absorption is performed in the remaining space between the peripheral surface (claim 1).
[0010]
(2) A standoff functioning as a spacer for ensuring a constant thickness of the adhesive when the main circuit block is pressure-bonded to the stepped seating surface of the board mounting hole is formed in a distributed manner. A projecting standoff projecting toward the side edge of the printed circuit board is formed on the side edge of the pedestal surface facing the peripheral wall side of the resin case with respect to the concave pedestal surface formed on the bottom surface, and the control circuit using the standoff as a spacer When the block is bonded to the concave pedestal surface, excess adhesive that protrudes is absorbed by the remaining gap space between the side edge of the printed circuit board and the side surface of the concave pedestal surface .
[0011]
With the above configuration, even if the amount of adhesive applied to the adhesive surface varies slightly in the bonding process for assembling the main circuit block and control circuit block to the resin case, the excess adhesive remains on the back surface of the insulating substrate. So that the step between the back of the insulating board of the main circuit block and the back of the resin case is within acceptable tolerances in terms of assembly accuracy. As a result, the reliability of the assembly is improved and the quality of the product is stabilized.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below based on the examples of FIGS. In addition, in the figure of an Example, the same code | symbol is attached | subjected to the same member corresponding to FIG. 6, FIG. 7, and the description is abbreviate | omitted.
First, in FIGS. 1A to 1C and FIGS. 2A to 2C, the assembly structure of the semiconductor device and the structure of the resin case are basically the same as those in FIGS. The resin case of the illustrated embodiment differs from the conventional structure in the following points. That is,
(1) With respect to the stepped seat surface 1a-1 which is opened at the bottom surface of the resin case 1 and formed at the periphery of the substrate mounting hole 1a, the cross section of the seat surface is projected so as to protrude toward the upper surface of the insulating substrate 5b. Protruding standoffs 1a-2 that are oval are distributed and formed at a plurality of locations.
[0013]
The stand-off 1a-2 is formed along the inner peripheral edge of the board mounting hole 1a with the width of the seating surface 1a-1 being d and about ½ of the width. The protruding height H of the standoff 1a-2 is such that the adhesive 7 is applied to the stepped seating surface 1a-1 and the insulating substrate 5b is pressed against the tip of the standoff 1a-2 as shown in the figure. , The step ΔS between the back surface of the insulating substrate 5b and the back surface of the resin case 1 is within an allowable range (within ± 0.1 mm), and the insulating substrate 5b in the entire peripheral area of the seating surface 1a-1. The layer thickness of the adhesive 7 sandwiched between the two is set so as to ensure the thickness specified by the type of adhesive from the viewpoint of adhesive strength.
[0014]
(2) Further, a tapered chamfer 1a-3 (taper angle α) is formed in the side wall portion of the stepped seating surface 1a so as to extend toward the back surface side of the resin case 1 over the entire circumference.
The chamfer 1a-3 serves as an adhesive reservoir that absorbs the excess of the adhesive 8 as described below. The insulating substrate 5b of the main circuit block 5 is fixed to the resin case 1 with the adhesive 7. When the insulating substrate 5b is pressed, an excessive adhesive that protrudes from the stepped seating surface 1a-1 and goes around to the back surface of the substrate is formed between the peripheral surface of the insulating substrate 5b and the chamfer 1a-3. Is absorbed by the cross-sectional triangular space between them, thereby preventing the adhesive 7 from wrapping around the back surface side, and the work of wiping off the protruding adhesive is not necessary.
[0015]
(3) Further, for the concave pedestal surface 1b on which the control circuit block 6 is mounted, on the side edge of the printed circuit board 6b on the side edge of the pedestal surface facing the peripheral wall side of the resin case 1 in which the signal terminals 4 are inserted. A protrusion-like standoff 1b-1 protruding toward the surface is formed. The stand-off 1b-1 is formed on both the left and right sides of the pedestal surface 1b, and the height h from the bottom surface is kept lower than the thickness of the substrate so as not to protrude upward from the top surface of the printed circuit board 6b. is there.
[0016]
In the assembly process of assembling the control circuit block 6 to the resin case 1, the printed circuit board 6b is fitted into the concave pedestal surface 1b using the standoff 1b-1 as a positioning member, and the printed circuit board 6b is attached to the adhesive. When the base plate 1b coated with 8 is pressed and cured by heating, the excess adhesive protruding from the side of the printed circuit board 6b with the stand-off 1b-1 as a spacer is contacted with the side surface of the concave base surface 1b. The adhesive is prevented from adhering to the circuit pattern of the printed circuit board 6b or the surface of the signal terminal by absorbing the gap space remaining between them.
[0017]
Next, FIGS. 3 and 4 show an application example of the stand-off 1a-2 formed on the stepped seat surface 1a described in (1). That is, in the embodiment of FIG. 2, the protruding standoff 1a-2 having an oval cross section is formed along the inner peripheral edge of the board mounting hole 1a, whereas the embodiment shown in FIGS. In the example, a stand-off 1a-2 having the same shape as that of FIGS. 2B and 2C is formed along the outer peripheral edge of the stepped seating surface 1a. 4A and 4B, the standoff 1a-2 is formed as a pin-shaped protrusion having a circular cross section.
[0018]
【The invention's effect】
As described above, according to the present invention, the following effects can be obtained.
(1) For the stepped seating surface formed at the periphery of the hole for mounting the main circuit block opened on the bottom of the resin case, the layer thickness of the adhesive to apply to the groove and fix the insulating substrate of the main circuit block is constant. By dispersing and forming the protruding standoffs that function as spacers to ensure the thickness, the variation in the adhesive layer thickness, which has been a problem with conventional structures, is suppressed and stably managed to a predetermined thickness. In addition, in terms of assembly accuracy, a cooling fin that is a heat sink with a step between the back surface of the insulating substrate of the main circuit block and the back surface of the resin case serving as a heat dissipation surface for heat generation of the power element within an allowable range Can be secured.
[0019]
(2) Further, by forming a tapered chamfer extending toward the back side of the resin case over the entire circumference of the stepped seating surface, excess adhesive is removed when the main circuit block is bonded. Wiping off the excess resin that has been performed in the past can be prevented by absorbing the remaining space between the part and the peripheral surface of the insulating substrate and preventing excess adhesive from wrapping around the back side of the resin case and insulating substrate. Work becomes unnecessary.
[0020]
(3) Furthermore, a protruding standoff protruding toward the side edge of the printed circuit board is formed on the side surface of the pedestal surface facing the peripheral wall side of the resin case with respect to the concave pedestal surface of the resin case mounting the control circuit block. The excess adhesive that protrudes from the side edge of the substrate into the gap space remaining between the printed circuit board and the side surface of the concave pedestal surface via the standoff is recovered, so that the excess adhesive is There is no risk of improperly adhering to the circuit pattern of the printed circuit board or the surface of the signal terminal to hinder subsequent wire bonding.
[0021]
As a result, the reliability in the assembly process of the semiconductor device is improved, and the product quality can be stabilized.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a semiconductor device according to an embodiment of the present invention, in which (a) is a longitudinal side view of the entire semiconductor device, and (b) and (c) are details of portions A and B in FIG. FIG. 2 is a structural view of the resin case in FIG. 1. (a) is a plan view of the entire resin case, and (b) and (c) are stand parts for part A in FIG. FIG. 3 is a structural diagram of a different embodiment of the stand-off corresponding to FIGS. 2 (b) and 2 (c). (A) and (b) FIG. 4 is a structural diagram of a further different embodiment of the stand-off corresponding to FIGS. 2 (b) and 2 (c). b) is an enlarged back view showing the shape and arrangement of the stand-off, and a cross-sectional view. FIG. FIG. 6 is a block diagram showing a conventional assembly structure of a semiconductor device, where (a) is a vertical side view of the entire semiconductor device, and (b) and (c) are portions A and B in FIG. FIG. 7 is a structural diagram of the resin case in FIG. 6, (a) is a plan view of the entire resin case, and (b) and (c) are portions A in FIG. Partial enlarged back view and cross-sectional view showing the shape of the stepped seating surface [Description of symbols]
1 Resin case 1a Board mounting hole 1a-1 Stepped seating surface 1a-2 Standoff 1a-3 Tapered chamfer 1b Concave seating surface 1b-1 Standoff 2 Upper lid 3 Main circuit terminal 4 Control signal terminal 5 Main circuit block 5a Power circuit element 5b Insulating substrate 6 Control circuit block 6a Circuit element 6b Printed circuit board 7, 8 Adhesive 9 Bonding wire 18 Sealing resin

Claims (2)

A semiconductor device in which a main circuit block and a control circuit block are incorporated in a resin case of a terminal integrated type in which a main circuit terminal and a control signal terminal are insert-molded on a peripheral wall, and are internally connected by bonding wires. The main circuit block is insulated. The board is fitted into the board mounting hole opened on the bottom surface of the resin case from below, and the periphery thereof is fixed to the stepped seating surface formed on the peripheral edge of the back surface of the board mounting hole with an adhesive. In the one where the printed circuit board is overlaid on the concave pedestal surface formed on and fixed with an adhesive,
A stand-off functioning as a spacer for ensuring a constant thickness of the adhesive when the main circuit block is pressure bonded is provided on the stepped seating surface of the board mounting hole on the upper surface of the main circuit block. A tapered chamfer extending toward the back side of the resin case is formed over the entire circumference of the stepped seating surface, and bonded to the main circuit block. In such a case, a surplus adhesive is absorbed in the remaining space between the chamfered portion and the peripheral surface of the insulating substrate . A semiconductor device in which a main circuit block and a control circuit block are incorporated in a resin case of a terminal integrated type in which a main circuit terminal and a control signal terminal are insert-molded on a peripheral wall, and are internally connected by bonding wires. The main circuit block is insulated. The board is fitted into the board mounting hole opened on the bottom surface of the resin case from below, and the periphery thereof is fixed to the stepped seating surface formed on the peripheral edge of the back surface of the board mounting hole with an adhesive. In the one where the printed circuit board is overlaid on the concave pedestal surface formed on and fixed with an adhesive,
A stand-off functioning as a spacer for ensuring a constant thickness of the adhesive when the main circuit block is pressure bonded is provided on the stepped seating surface of the board mounting hole on the upper surface of the main circuit block. The printed circuit board is provided on the side edge of the pedestal surface facing the peripheral wall side of the resin case with respect to the concave pedestal surface of the resin case on which the control circuit block is mounted. Protruding standoffs protruding toward the edges are formed, and excess adhesive that protrudes when the control circuit block is bonded to the concave pedestal surface using the standoffs as spacers is printed on the side edges of the printed circuit board and the side surfaces of the concave pedestal surfaces. A semiconductor device characterized in that absorption is performed in a gap space remaining between the two .

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