Semiconductor device

Abstract

The present invention provides a semiconductor device. A semiconductor chip (10) is provided on a semiconductor circuit board (8) on one surface of an insulating substrate (4). On one surface of the insulating substrate (4), a circuit board (26) is provided at an interval from the semiconductor circuit board (8). Inside a resin-molded sealing body (2), the insulating substrate (4), the semiconductor circuit board (8), the semiconductor chip (10), and the circuit board (26) are sealed. The sealing body (2) has a resin non-adhesion portion (34).

Description

Technical Field

[0001] The present invention relates to a semiconductor device, and particularly to a device having a resin-molded sealing body. Background Art

[0002] In Japanese Patent Laid-Open Publication No. 2017-92389, an example of a conventional semiconductor device is disclosed. In this semiconductor device, a lead frame has a die pad, and the die pad has lead terminals. A semiconductor element is mounted on the die pad. The lead frame is sealed with a resin sealing body in such a manner that the die pad and the semiconductor element are located inside. The sealing body is formed by disposing the lead frame in a resin molding die with the lead terminals protruding from the resin molding die and injecting resin into the die. In this semiconductor device, as shown in FIG. 9 of Japanese Patent Laid-Open Publication No. 2017-92389, a part of the die pad portion in the lead frame is exposed from the sealing body.

[0003] The reason for the exposure of a part of the die pad is that the lead frame is pressed into the die by a protrusion or the like formed in the die. In this case, when resin is injected into the die, the resin does not adhere to the place in the die where the protrusion exists, so the portion pressed by the protrusion of the die pad, which is part of the lead frame, is exposed from the resin body. When an operator energizes this semiconductor device, current also flows into the exposed part of the die pad, and when the operator touches the exposed part, the operator may get an electric shock. In order to prevent electric shock, it is necessary to maintain the insulation of the semiconductor device. Therefore, sometimes after the semiconductor device is taken out of the die, resin is applied to the exposed part of the die pad to cover the exposed part. As a result, it is necessary to perform resin-related operations (injection and application) multiple times.

[0004] An object of the present invention is to provide a semiconductor device that can maintain insulation even when only one resin-related operation is performed. Summary of the Invention

[0005] In a semiconductor device according to one embodiment of the present invention, a semiconductor circuit base is provided on one surface of an insulating substrate. A semiconductor chip is provided on the semiconductor circuit base. The semiconductor circuit base can be configured such that current flows from the semiconductor chip to the semiconductor circuit base. On the one surface of the insulating substrate, a reinforcement and balance base is formed at a distance from the semiconductor circuit base. The reinforcement and balance base can be used to fix the semiconductor device to a heat sink by using fixing means such as screws. The insulating substrate, the semiconductor circuit base, and the reinforcement and balance base can be manufactured, for example, by processing a base material of an insulating substrate having a metal film formed over the entire area of the one surface. By removing a part of the metal film of the base material, for example, by etching, an insulating substrate having the semiconductor circuit base and the reinforcement and balance base on the one surface is produced. As the base material, a DCB substrate can be used. The resin-molded package seals the insulating substrate, the semiconductor circuit base, the semiconductor chip, and the reinforcement and balance base inside. The package has a resin non-adhesive portion. The resin-molded package can be, for example, a transfer-molded package. The resin non-adhesive portion can be formed, for example, by disposing a pressing tool in a transfer mold. In this case, when the insulating substrate having the semiconductor base with the semiconductor chip is disposed in the transfer mold, the pressing tool contacts the insulating substrate.

[0006] In this semiconductor device, generally, the integrally formed semiconductor circuit base and the reinforcement and balance base are disposed at a distance from each other inside the sealed body, so the semiconductor circuit base and the reinforcement and balance base are insulated from each other. Therefore, there is no need to bury the resin non-adhesive portion of the sealed body with resin.

[0007] In the semiconductor device according to the above embodiment, the resin non-adhesive portion can be formed at a position corresponding to the reinforcement and balance base. If the semiconductor circuit base and the reinforcement and balance base are formed without insulation and the resin non-adhesive portion is formed at a position corresponding to the reinforcement and balance base, in order to prevent an operator from getting an electric shock, it is necessary to newly bury the resin non-adhesive portion with resin. In contrast, in this structure, the reinforcement and balance film and the semiconductor circuit base are insulated, so even if there is a resin non-adhesive portion in the resin sealed body on the reinforcement and balance base side, there is no concern about electric shock and there is no need to bury the resin non-adhesive portion with resin.

[0008] In addition, the reinforcing and balancing base can be disposed on the insulating substrate on the side opposite to the protruding direction of the lead connected to the semiconductor chip. In this case, a resin non-adhesive portion is formed at the position where the pressing tool of the substrate contacts when the sealing body is formed by resin molding. Since the lead is disposed on the semiconductor circuit base, it protrudes from one end of the sealing body. In this case, from the viewpoint of preventing the movement and warping of the insulating substrate during resin injection, it is preferable that the pressing tool contacts the reinforcing and balancing base on the side opposite to the lead. Therefore, the resin non-adhesive portion is disposed at a position corresponding to the reinforcing and balancing base. If the reinforcing and balancing base and the semiconductor circuit base are integrally formed, in order to maintain the insulation of the reinforcing and balancing base, it is necessary to inject resin into the resin non-adhesive portion. In this structure, the semiconductor circuit base and the reinforcing and balancing base are insulated from each other, so even if the resin non-adhesive portion is provided, it is not necessary to inject resin into the resin non-adhesive portion. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 is a central longitudinal sectional side view of a semiconductor device according to an embodiment of the present invention.

[0010] Figure 2 is Figure 1 a side view of the semiconductor device.

[0011] Figure 3 is Figure 1 a front view of the semiconductor device.

[0012] Figure 4 is Figure 1 a front view of the internal structure of the semiconductor device.

[0013] Figure 5 is for forming Figure 1 a central longitudinal sectional side view of a state in which the insulating substrate, the semiconductor circuit base, and the reinforcing and balancing base of the semiconductor device are arranged in a mold for forming a sealing body of the semiconductor device.

[0014] Figure 6 is for forming Figure 1 a cross-sectional view of a state in which the insulating substrate, the semiconductor circuit base film, and the reinforcing and balancing base are arranged in a mold for forming a sealing body of the semiconductor device. DETAILED DESCRIPTION OF THE INVENTION

[0015] A semiconductor device according to an embodiment of the present invention is a discrete semiconductor device, such as a MOSFET. The MOSFET has a resin package, such as a sealing body 2, as shown in Figures 1 to 3 and the sealing body 2 is in a substantially flat rectangular parallelepiped shape.

[0016] Inside the sealing body 2, as shown inFigure 1 For example, an insulating substrate 4 having a rectangular shape is provided. On the entire surface of one side of the insulating substrate 4, a heat dissipation base, such as a heat dissipation film 6 made of a metal, such as copper, is formed, and the heat dissipation film 6 is exposed on the surface of one side of the sealing body 2. When the semiconductor device is mounted on a radiator (not shown), the heat dissipation film 6 contacts the radiator.

[0017] On the surface of the insulating substrate 4 opposite to the heat dissipation film 6, as Figure 1 and Figure 4 shown, a semiconductor circuit base, such as a semiconductor circuit film 8, is provided. The semiconductor circuit film 8 is formed in a substantially rectangular shape, is made of a metal, such as copper, and is located at a position from one end side of the insulating substrate 4 to a vicinity slightly beyond the center of the insulating substrate 4. A semiconductor chip 10 of a MOSFET is mounted on the semiconductor circuit film 8. The semiconductor chip 10 has two opposite faces. A drain region is formed on one face of the semiconductor chip 10, and the drain region is electrically connected to the semiconductor circuit film 8. A gate pad 12, source pads 14, 14, and a source sense pad 16 are formed on the other face of the semiconductor chip 10. A gate lead 18 is connected to the gate pad 12. Source leads 20 with a two-forked tip are connected to the source pads 14, 14. A source sense lead 22 is connected to the source sense pad 16. In addition, a drain lead 24 is connected to the semiconductor circuit film 8 to which the drain region is connected.

[0018] In a region from the other end side of the insulating substrate 4 to a position slightly in front of its center, a reinforcing and balancing base, such as a reinforcing and balancing film 26 made of a metal, such as copper, is provided. The reinforcing and balancing film 26 and the semiconductor circuit film 8 are provided at intervals and are insulated from each other. The reinforcing and balancing film 26 is in a rectangular shape with a part removed. An insertion hole 28 is formed in the insulating substrate 4 in the removed part. A screw for mounting the semiconductor device on a radiator is inserted through the insertion hole 28. As Figure 1 shown, corresponding to the insertion hole 28, an insertion hole 30 is also formed in the resin sealing body 2, and an insertion hole 32 is also formed in the heat dissipation film 6 corresponding to the insertion hole 28.

[0019] On both sides of the insertion hole 30, resin non-adhesive portions 44, 44 are provided as described later.

[0020] In addition, the insulating substrate 4, the heat dissipation film 6, the semiconductor circuit film 8, and the reinforcing and balancing film 26 are manufactured by removing, for example, etching a DCB (Direct Copper Bonding) substrate obtained by directly sintering or brazing copper on both sides of a base material, such as an insulating substrate.

[0021] The resin sealing body 2 is manufactured as described below. On the insulating substrate 4 having a heat dissipation film 6 formed on one surface and a semiconductor circuit film 8 and a reinforcement and balance film 26 formed on the other surface, the drain region of the semiconductor chip 10 is connected to the semiconductor circuit film 8 as Figure 1 shown. As Figure 4 shown, leads 18, 20, 22 are connected to the pads 12, 14, 14, 16 of the semiconductor chip 10, and a lead 24 is connected to the semiconductor circuit film 8. As Figure 5 shown, they are disposed in a cavity 38 formed by an upper mold 34 and a lower mold 36 for transfer molding. As a result, the leads 18, 20, 22, and 24 are held by the mating surfaces of the upper mold 34 and the lower mold 36. The cavity 38 has an internal shape complementary to the outer shape of the resin sealing body 2. For example, the upper mold 34 has a protrusion 40 in the cavity 38 for preventing resin from entering the portions corresponding to the insertion holes 28, 30, and 32. As Figure 6 shown, pressing protrusions 42 and 42 (shown by dashed lines in Figure 5 ) are formed in the upper mold 34, for example, on both sides of the protrusion 40 located in the cavity 38. The tips of the pressing protrusions 42 and 42 contact at least the insulating substrate 4.

[0022] As Figure 6 shown, each of the leads 18, 20, 22, 24 is clamped and constrained by the mating surfaces of the upper mold 34 and the lower mold 36. If the insulating substrate 4 is not constrained by the pressing protrusions 42 and 42, the insulating substrate 4 moves or warps when resin is injected into the cavity 38. To prevent this problem, the pressing protrusions 42 and 42 are provided on the side of the insulating substrate 4 located on the opposite side of these leads 18, 20, 22, 24. These protrusions 42 and 42 also contact a part of the reinforcement and balance film 26 of the insulating substrate 4 in order to ensure a sufficient contact area. As Figure 6 shown, when resin is injected into the cavity 38, the resin does not adhere to the portions where the pressing protrusions 42 and 42 are present. Therefore, when the sealing body 2 is removed from the mold after the resin injection into the cavity 38 is completed, as Figure 2 and Figure 3 shown, resin non-adhesive portions 44, 44 are formed on both sides of the insertion hole 30.

[0023] In these resin non-adhesive portions 44, 44, as Figure 3A part of the reinforcing and balancing film 26 shown is exposed. When the semiconductor circuit film 8 and the reinforcing and balancing film 26 are integrally formed, not only the semiconductor circuit film 8 but also the reinforcing and balancing film 26 has a drain current flowing through it. A part of the reinforcing and balancing film 26 through which the drain current flows is exposed at the resin non-adhesive portions 44, 44. In order to prevent an operator from getting an electric shock, it is necessary to apply resin to the resin non-adhesive portions 44 and bury the resin non-adhesive portions 34 with the resin. However, in this semiconductor device, the reinforcing and balancing film 26 and the semiconductor circuit film 8 are insulated, so no current flows through the reinforcing and balancing film 26. Therefore, even if an operator touches this semiconductor device by hand, there is no worry of electric shock, so it is not necessary to bury the resin non-adhesive portions 44 with resin, and the manufacturing process can be simplified.

[0024] Although it is also considered not to form the reinforcing and balancing film 26 and the heat dissipation film 6 corresponding to the reinforcing and balancing film 26 in this semiconductor device, without them, the strength of the sealing body 2 corresponding to these parts of the completed semiconductor device is reduced. In addition, it is also considered to remove the reinforcing and balancing film 26 by etching. However, from the viewpoints of the weight, heat dissipation amount, and warpage amount of the insulating substrate 4, etc., there is an imbalance in the weight between the surface of the insulating substrate 4 on the side where the heat dissipation film 6 is provided and the surface where the semiconductor circuit film 8 is provided, and furthermore, there is an imbalance in the weight between the part where the lead terminals 18, 20, 22, 24 are provided on the surface of the insulating substrate 4 where the semiconductor circuit film 8 is provided and the part on the opposite side thereof. Therefore, there is a possibility that the warpage of the semiconductor device as a whole becomes large.

[0025] In contrast, in this semiconductor device, the DCB substrate serving as the basis for the insulating substrate 4, the reinforcing and balancing film 26, and the semiconductor circuit film 8 is etched in such a way that the reinforcing and balancing film 26 and the semiconductor circuit film 8 can be insulated. Therefore, the areas of the metal parts on both sides of the insulating substrate 4 are balanced, and in the surface of the insulating substrate 4 where the semiconductor circuit film 8 and the reinforcing and balancing film 26 are provided, the areas of the metal parts are balanced. As a result, it is possible to prevent the warpage of this semiconductor device from becoming large.

[0026] In the above-described embodiment, the present invention is applied to a MOSFET, but it is not limited thereto, and as long as it is a semiconductor element in which a current flows through the semiconductor circuit film, it can be used for any element. In the above-described embodiment, the insulating substrate 4, the heat dissipation film 6, the semiconductor circuit film 8, and the reinforcing and balancing film 26 are formed from the DCB substrate, but it is also possible to form the insulating substrate 4, the heat dissipation film 6, the semiconductor circuit film 8, and the circuit film 26 not from the DCB substrate but from a normal printed circuit board.

Claims

1. A semiconductor device having: An insulating substrate; A circuit base for semiconductors provided on one surface of the insulating substrate; A semiconductor chip provided on the circuit base for semiconductors; A circuit base provided at an interval from the circuit base for semiconductors on the one surface of the insulating substrate; and A sealing body that internally seals the insulating substrate, the circuit base for semiconductors, the semiconductor chip, and the circuit base, and has a resin non-adhesive portion, The resin non-adhesive portion is provided at a position corresponding to the circuit base.

2. The semiconductor device according to claim 1, Wherein, The circuit base is provided on the insulating substrate on a side opposite to the protruding direction of the lead connected to the semiconductor chip, and the resin non-adhesive portion is formed at a position where a pressing tool of the substrate contacts when the sealing body is formed by resin molding.

3. The semiconductor device according to claim 1, Wherein, The circuit base for semiconductors and the circuit base are provided by removing a part of the metal film formed over the entire area of the one surface of the insulating substrate.

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