INCORPORATION BY REFERENCE
The disclosure of Japanese Patent Application No. 2011-242206 filed on Nov. 4, 2011 including the specification, drawings and abstract is incorporated herein by reference in its entirety.
The present disclosure relates to a semiconductor device including a flexible circuit substrate, and a manufacturing method of the semiconductor device.
A semiconductor device including: a ceramic substrate in contact with a heat dissipater; a metal member in contact with the ceramic substrate; an electronic component mounted on the metal member; and an electrode (control terminal) placed outside the ceramic substrate, electrically connected to the electronic component by a bonding wire, and leading to the outside is conventionally known (for example, see Japanese Patent Application Publication No. 2009-088215 (JP 2009-088215 A)).
The structure of electrically connecting the electronic component to the outside via the control terminal as in the technique described in above-mentioned JP 2009-088215 A has, however, a problem of an increase in size of the semiconductor device, because the control terminal is placed outside the substrate.
In this respect, a structure of directly attaching a flexible circuit substrate onto the substrate to achieve the electrical connection between the semiconductor element on the substrate and the outside is advantageous in that the size of the semiconductor device can be reduced. However, such a structure has a possibility that, when a resin is applied onto the substrate for sealing, the resin flows along the flexible circuit substrate and protrudes outside the substrate.
In view of this, the present disclosure has an object of providing a semiconductor device and a manufacturing method of the semiconductor device that can appropriately prevent the resin from flowing along the flexible circuit substrate and protruding outside the substrate.
According to an aspect of the present invention, a semiconductor device includes: a metal substrate; a semiconductor element placed on the metal substrate; a flexible circuit substrate that has one end placed on the metal substrate and is electrically connected to the semiconductor element, the flexible circuit substrate extending over an edge of the metal substrate to outside the metal substrate; a resin wall portion placed, in an outer periphery of the metal substrate, at least at the edge of the metal substrate over which the flexible circuit substrate extends, the resin wall portion being provided on the flexible circuit substrate at the edge; and a resin seal portion provided inside the resin wall portion so as to cover the metal substrate.
According to the aspect, it is possible to attain a semiconductor device and a manufacturing method of the semiconductor device that can appropriately prevent the resin from flowing along the flexible circuit substrate and protruding outside the substrate.
The following describes an embodiment with reference to drawings.
Though up and down directions of the semiconductor device 1 vary depending on a mounting state of the semiconductor device 1, the following description is based on an assumption that a semiconductor chip 10 side of a heat spreader 20 of the semiconductor device 1 is the upper side, for convenience's sake. Moreover, the following term definitions are used. The term “outside” and “inside” are defined with respect to a center of the heat spreader 20 in a plan view in a direction perpendicular to an upper surface of the heat spreader 20. That is, “outside” means away from the center of the heat spreader 20 in the plan view, whereas “inside” means toward the center of the heat spreader 20 in the plan view. Note that the center of the heat spreader 20 does not need to be precisely determined, and may be a substantial center.
For example, the semiconductor device 1 may be included in an inverter for driving a motor, which is used in a hybrid vehicle or an electric vehicle.
The semiconductor device 1 includes the semiconductor chip 10, the heat spreader 20, the insulation layer 30, the heat sink 40, a flexible printed circuit (FPC) 90, the resin wall portion 70, and the resin seal portion 72, as shown in
The semiconductor chip 10 includes a power semiconductor element. The semiconductor chip 10 is joined onto the heat spreader 20 by solder 50. In the example shown in the drawings, two semiconductor chips 10 that are respectively an insulated gate bipolar transistor (IGBT) and a free wheeling diode (FWD) are provided on one heat spreader 20. In this case, the IGBT has an emitter electrode on its upper surface and a collector electrode on its lower surface, and the FWD has an anode electrode on its upper surface and a cathode electrode on its lower surface. Note that the type and number of power semiconductor elements included in the semiconductor chip 10 are not specifically limited. The semiconductor chip 10 may include another switching element such as a metal oxide semiconductor field-effect transistor (MOSFET), instead of the IGBT.
A first connection terminal 12 is fixed (joined) to the upper surface of the semiconductor chip 10 by the solder 50. In the example shown in the drawings, lower ends of legs of the first connection terminal 12 are respectively joined to the emitter electrode of the IGBT and the anode electrode of the FWD by the solder 50. An upper part of the first connection terminal 12 may be joined to a bus bar (not shown) by, for example, laser welding.
The heat spreader 20 is a member for absorbing and diffusing heat generated from the semiconductor chip 10. The heat spreader 20 is made of a metal having excellent thermal diffusivity, such as copper, aluminum, or the like. In this embodiment, the heat spreader 20 is made of copper, as an example. As the copper, oxygen-free copper (C1020) having highest conductivity of copper materials is preferably used.
A second connection terminal 14 is joined to the upper surface of the heat spreader 20 by solder or the like. Since the collector electrode of the IGBT as the semiconductor chip 10 (and the cathode electrode of the FWD as the semiconductor chip 10) is connected to the heat spreader 20, the second connection terminal 14 constitutes an extraction portion of the collector electrode of the IGBT. Like the first connection terminal 12, the second connection terminal 14 may be joined to a bus bar (not shown) by, for example, laser welding.
The insulation layer 30 may be made of a resin adhesive or a resin sheet. The insulation layer 30 may be made of, for example, a resin with alumina as a filler. The insulation layer 30 is provided between the heat spreader 20 and the heat sink 40, and joined to the heat spreader 20 and the heat sink 40. The insulation layer 30 ensures high thermal conductivity from the heat spreader 20 to the heat sink 40, while maintaining electrical insulation between the heat spreader 20 and the heat sink 40.
The heat sink 40 is made of a material having high thermal conductivity, for example, a metal such as aluminum. The heat sink 40 has fins 42 on its lower surface, as shown in
The FPC 90 has an upper surface (surface on the opposite side from a surface joined to the heat spreader 20) on which wiring (not shown) connected to a bonding wire 80 is formed (printed). The FPC 90 has one end attached onto the heat spreader 20, as shown in
The FPC 90 is connected to the semiconductor chip 10 by the bonding wire 80 on the heat spreader 20, as shown in
The resin wall portion 70 and the resin seal portion 72 are described below, with reference to
The resin wall portion 70 is provided along the entire periphery of the heat spreader 20, as shown in
The resin seal portion 72 is provided in an area surrounded by the resin wall portion 70 on the upper surface of the heat spreader 20. The resin seal portion 72 may be formed by molding a resin material into the area surrounded by the resin wall portion 70 on the upper surface of the heat spreader 20. The resin material may be any material suitable for sealing, such as a silicon gel or a thermosetting resin (e.g. epoxy resin) using an acid anhydride or phenolic curing agent.
As shown in
In this embodiment, on the other hand, the resin wall portion 70 functions as a dam frame (bank) when forming the resin seal portion 72, so that the flow of the resin material to extend over the edge of the heat spreader 20 to outside on the FPC 90 is blocked. This prevents the resin seal portion 72 from protruding outside, as a result of which the element to be sealed by the resin seal portion 72 can be reliably sealed.
The resin wall portion 70 is preferably set to a height based on a highest element to be sealed by the resin seal portion 72 from among various elements placed on the heat spreader 20. In the example shown in the drawings, the highest element to be sealed by the resin seal portion 72 is the bonding wire 80. In this case, the resin wall portion 70 is set to have a height larger than that of the bonding wire 80 with respect to the upper surface of the heat spreader 20. Thus, the bonding wire 80 can be reliably sealed by the resin seal portion 72, as shown in
In the example shown in
The following describes a manufacturing method of the semiconductor device 1 in this embodiment.
First, as shown in
Next, as shown in
Next, as shown in
In the embodiment described above, the heat spreader 20 corresponds to the “metal substrate” in the claims, and the FPC 90 corresponds to the “flexible circuit substrate” in the claims.
Though the preferred embodiment of the present invention has been described in detail above, the present invention is not limited to the embodiment described above. Various modifications and substitutions can be added to the embodiment described above, without departing from the scope of the present invention.
For example, though the resin wall portion 70 is formed along the entire periphery of the heat spreader 20 in the preferred embodiment described above, the resin wall portion 70 may be formed only at the part of the periphery of the heat spreader 20 where the FPC 90 is placed, or at a part of the periphery of the heat spreader 20 including the part where the FPC 90 is placed. In such a case, too, the flow of the resin material to extend over the edge of the heat spreader 20 to outside on the FPC 90 is blocked, so that the resin seal portion 72 can be prevented from protruding outside.
In the embodiment described above, the part of the FPC 90 located on the edge of the heat spreader 20 (the end 90a of the FPC 90 placed on the edge of the heat spreader 20 in the example shown in the drawings) may be provided with a reinforcer. The reinforcer may be made of, for example, the same material (e.g. polyimide) as the FPC 90. This reduces stress concentration in the FPC 90 caused by a force received from the edge of the heat spreader 20, which makes it possible to appropriately protect the wiring on the FPC 90.
Number | Date | Country | Kind |
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2011-242206 | Nov 2011 | JP | national |