JP7775602B2 - Semiconductor module and method for manufacturing the same - Google Patents

Description

The present invention relates to a semiconductor module and a method for manufacturing a semiconductor module.

Semiconductor modules have substrates on which semiconductor elements such as IGBTs (Insulated Gate Bipolar Transistors), power MOSFETs (Metal Oxide Semiconductor Field Effect Transistors), and FWDs (Free Wheeling Diodes) are mounted, and are used in inverter devices and the like.

In this type of semiconductor module, for example, in Patent Document 1, multiple power modules are arranged in a row on a plate-shaped frame. The plate-shaped frame is made of a metal such as aluminum or copper, which has good thermal conductivity.

International Publication No. 2015/182301

Semiconductor modules, the majority of whose structure is composed of laminated bodies, typically have a flat plate shape. Therefore, the mounting surface onto which the semiconductor module is attached is often also flat. However, mounting surfaces are not always flat; for example, there may be cases where a semiconductor module needs to be mounted on a curved mounting surface.

The present invention was made in consideration of these points, and one of its objectives is to provide a semiconductor module and a method for manufacturing a semiconductor module that can be properly fixed even on a curved mounting surface.

A semiconductor module according to one aspect of the present invention comprises a laminated substrate formed by stacking an insulating plate having an upper surface and a lower surface, a heat sink disposed on the lower surface of the insulating plate, and multiple circuit boards disposed on the upper surface of the insulating plate; and a semiconductor element disposed on the upper surface of each of the circuit boards, wherein the multiple circuit boards are arranged side by side in a predetermined direction in a plan view, the lower surface of the heat sink has multiple heat dissipation regions separated along the boundary lines between adjacent circuit boards and arranged side by side in the predetermined direction in a plan view, and the insulating plate is curved along the predetermined direction so as to be convex toward one side in the thickness direction.

In addition, one aspect of the present invention relates to a method for manufacturing a semiconductor module, and includes a laminated substrate preparation process for preparing a laminated substrate by stacking an insulating plate having an upper surface and a lower surface, a plurality of circuit boards arranged side by side in a predetermined direction on the upper surface of the insulating plate in a planar view, and a heat dissipation plate arranged on the lower surface of the insulating plate, the lower surface of which is separated along the boundary line between adjacent circuit boards, and having a plurality of heat dissipation areas arranged side by side in the predetermined direction in a planar view; a chip placement process for placing semiconductor elements on the upper surface of each of the circuit boards; and a bending process for bending the insulating plate along the predetermined direction so that it is convex on one side in the thickness direction.

The present invention makes it possible to secure modules to curved mounting surfaces.

1 is a plan view of a semiconductor module according to an embodiment of the present invention; FIG. 2 is a plan view seen through the molding resin of FIG. 1. 2 is a cross-sectional view taken along a plane parallel to the ZX plane in FIG. 1 . 1 is a schematic diagram showing an example of a circuit configuration of a semiconductor module according to an embodiment of the present invention; 5A to 5C are schematic diagrams illustrating an example of a process (a laminated substrate preparation process) in the method for manufacturing the semiconductor module according to the present embodiment. 3A to 3C are schematic diagrams illustrating an example of a process (chip placement process) in the method for manufacturing the semiconductor module according to the present embodiment. 5A to 5C are schematic diagrams illustrating an example of a process (bonding process) in the method for manufacturing the semiconductor module according to the present embodiment. 10A to 10C are schematic diagrams illustrating an example of a process (bending process) in the method for manufacturing the semiconductor module according to the present embodiment. 5A to 5C are schematic diagrams illustrating an example of a process (bending process) in the method for manufacturing the semiconductor module according to the present embodiment. 5A to 5C are schematic diagrams illustrating an example of a process (molding process) in a manufacturing method for a semiconductor module according to the present embodiment. 5A to 5C are schematic diagrams illustrating an example of a process (molding process) in a manufacturing method for a semiconductor module according to the present embodiment. 5A to 5C are schematic diagrams illustrating an example of a process (molding process) in a manufacturing method for a semiconductor module according to the present embodiment. 5A to 5C are schematic diagrams illustrating an example of a process (terminal molding process) in the manufacturing method of the semiconductor module according to the present embodiment. 5A to 5C are schematic diagrams illustrating an example of a process (circuit board placement process) in the method for manufacturing the semiconductor module according to the present embodiment. 10A to 10C are schematic diagrams showing variations of a semiconductor module (heat sink) according to a modified example (circuit board mounting process).

A semiconductor module to which the present invention can be applied will now be described. Figure 1 is a plan view of a semiconductor module according to this embodiment. Figure 2 is a plan view seen through the molding resin in Figure 1. Figure 3 is a cross-sectional view taken along a plane parallel to the ZX plane in Figure 1. Figure 4 is a schematic diagram showing an example of the circuit configuration of a semiconductor module according to this embodiment. Note that the semiconductor module shown below is merely an example and can be modified as appropriate without being limited to this.

In the following figures, the longitudinal direction of the semiconductor module (cooler) is defined as the X direction, the transverse direction of the semiconductor module (cooler) as the Y direction, and the height direction (thickness direction of the board) as the Z direction. The longitudinal direction of the semiconductor module indicates the direction in which multiple circuit boards are arranged. The X, Y, and Z axes shown in the figures are perpendicular to each other and form a right-handed system. In some cases, the X direction may be referred to as the left-right direction, the Y direction as the front-back direction, and the Z direction as the up-down direction. These directions (front-back, left-right, up-down) are terms used for convenience of explanation, and their correspondence with the X, Y, and Z directions may change depending on the mounting orientation of the semiconductor module. For example, the heat dissipation surface (cooler side) of the semiconductor module is referred to as the bottom side, and the opposite side as the top side. In this specification, a planar view refers to the top or bottom of the semiconductor module as viewed from the Z direction. In this specification, the term "curved" is not limited to shapes composed solely of curves, but may also include straight lines. A "curved" shape may be, for example, a shape consisting of multiple straight lines and multiple curved lines.

The semiconductor module 1 according to this embodiment is a power semiconductor module that is applied to a power conversion device such as a power control unit for an on-board motor, and constitutes an inverter circuit (see Figure 4). As shown in Figures 1 to 5, the semiconductor module 1 comprises a laminated substrate 2, a plurality of semiconductor elements 3 and 4, and a molded resin 5 that seals these elements. The semiconductor module 1 is attached, for example, via a thermal compound (not shown), to the mounting surface 11 (see Figure 3) of a heat sink 10 provided in an on-board compressor. The configuration of the mounting destination for the semiconductor module 1 will be described later.

In this embodiment, the semiconductor module 1 as a whole forms the three-phase inverter circuit shown in Figure 4. As shown in Figure 1, in the semiconductor module 1, the U phase, V phase, and W phase are arranged in order from the positive side in the X direction.

The laminated substrate 2 is composed of, for example, a DCB (Direct Copper Bonding) substrate, an AMB (Active Metal Brazing) substrate, or a metal-based substrate. The laminated substrate 2 is composed of a laminated insulating plate 20, multiple heat sinks 21, and multiple circuit boards 22, and is formed into a rectangular shape as a whole in a plan view.

Specifically, the insulating plate 20 is formed as a plate-like body having an upper surface and a lower surface, and has a rectangular shape in a plan view extending in the X direction (see FIG. 2 ). The thickness of the insulating plate 20 may be 0.05 mm or more and 2.0 mm or less. Preferably, the thickness is 0.1 mm or more and 0.5 mm or less. If the insulating plate 20 is too thin, electrical insulation cannot be ensured, and if it is too thick, heat dissipation cannot be ensured. The insulating plate 20 may be formed of a ceramic material such as aluminum oxide ₍ Al ₂ O ₃ ), aluminum nitride (AlN), silicon nitride (Si _{3 N 4} ), aluminum oxide (Al 2 _{O 3} ) and zirconium oxide (ZrO 2 ). The insulating plate 20 may also be formed of a thermosetting resin such as epoxy resin or polyimide resin, or a composite material containing a thermosetting resin and glass or a ceramic material as a filler. The insulating plate 20 is preferably flexible and may be formed of a material containing, for example, a thermosetting resin. The insulating plate 20 may also be called an insulating layer or an insulating film. As will be described in detail later, the insulating plate 20 is bent between each of the circuit boards 22 (five locations) in the cross-sectional view shown in FIG. 3 , and has an overall arc-curved shape that is convex upward (in the +Z direction). More specifically, the insulating plate 20 has, in the cross-sectional view, alternately formed linear planar portions (six locations) on which the multiple circuit boards 22 are arranged and bent portions (five locations) that are curved in a direction that is convex upward (in the +Z direction) between each of the circuit boards 22, and has an overall arc-curved shape that is convex upward (in the +Z direction).

The heat sink 21 has a predetermined thickness and is rectangular in plan view, elongated in the Y direction (see Figure 2). The thickness of the heat sink 21 may be 0.1 mm or more and 4.0 mm or less. Preferably, it is 0.2 mm or more and 1.0 mm or less. The heat sink 21 is formed from a metal plate with good thermal conductivity, such as copper or aluminum. The heat sink 21 is disposed on the underside of the insulating plate 20. In this embodiment, multiple (six) heat sinks 21 are disposed at predetermined intervals. Specifically, as indicated by the dashed lines in Figure 2, they are disposed side by side in the X direction in plan view, and as shown in Figure 3, they are disposed in an arc-like shape that is convex upward (in the +Z direction) in cross section viewed from the Y direction.

As will be described in more detail below, the multiple heat sinks 21 are arranged to correspond to the multiple circuit boards 22. The lower surface of the heat sink 21 may be exposed on the underside of the semiconductor module 1. More preferably, it may protrude downward from the underside of the molded resin 5. The lower surface of the heat sink 21 is the mounting surface for the heat sink 10 (see Figure 3) to which the semiconductor module 1 is attached, and also functions as a heat dissipation surface (heat dissipation area) for dissipating heat from the semiconductor module 1.

Like the heat sink 21, the circuit board 22 has a predetermined thickness and a rectangular shape in plan view that is long in the Y direction (see Figure 2). The thickness of the circuit board 22 may be 0.1 mm or more and 4.0 mm or less. Preferably, it is 0.2 mm or more and 1.0 mm or less. The thickness of the circuit board 22 may be the same as that of the heat sink 21. The circuit board 22 is formed from a metal plate with good thermal conductivity, such as copper or aluminum. The circuit board 22 may also be called a circuit layer or circuit pattern. The circuit board 22 is disposed on the upper surface of the insulating plate 20. In this embodiment, multiple (six) circuit boards 22 are disposed at predetermined intervals. Specifically, as shown in Figure 2, the circuit boards 22 are disposed side by side in the X direction in plan view, and as shown in Figure 3, they are disposed in an arc-like shape that is convex upward (in the +Z direction) in cross-sectional view taken from the Y direction.

As will be described in more detail below, as shown in Figures 1 and 2, of the six circuit boards 22, the two circuit boards 22 aligned on the positive side in the X direction form the U-phase circuit. The two circuit boards 22 aligned in the middle form the V-phase circuit. The two circuit boards 22 aligned on the negative side in the X direction form the W-phase circuit. In each phase, the circuit board 22 on the positive side in the X direction forms the upper arm (which may also be called the high side), and the circuit board 22 on the negative side in the X direction forms the lower arm (which may also be called the low side).

Each of the heat sinks 21 described above is disposed in a location corresponding to the area directly below each circuit board 22 (on the opposite side of the insulating plate 20). The corresponding location refers to a location that includes the area directly below each circuit board 22 (on the opposite side of the insulating plate 20). Furthermore, it is preferable that the heat sink 21 has a larger area than the circuit board 22 in a plan view. Even more preferably, each heat sink 21 is disposed so as to include the entire area directly below each circuit board 22 (on the opposite side of the insulating plate 20).

The gap between adjacent heat sinks 21 is located at a position that corresponds to the gap directly below the gap between adjacent circuit boards 22 (on the opposite side of the insulating plate 20). The corresponding position refers to a position that includes the area directly below the gap between adjacent circuit boards 22 (on the opposite side of the insulating plate 20). Furthermore, it is preferable that the gap between adjacent heat sinks 21 has a smaller area than the gap between adjacent circuit boards 22 in a plan view. Even more preferably, the gap between adjacent heat sinks 21 is located so that it is entirely included in the area directly below the gap between adjacent circuit boards 22 (on the opposite side of the insulating plate 20).

A terminal member 23 (first terminal member) that constitutes the wiring for the main current is connected to the end of each circuit board 22 on the negative side in the Y direction. The terminal member 23 has an elongated shape that extends from the end of the circuit board 22 toward the negative side in the Y direction. Each terminal member 23 is formed inside the width (X direction) of the corresponding circuit board 22.

The terminal member 23 on the upper arm side of each phase constitutes the high-potential input terminal (P terminal). Meanwhile, the terminal member 23 on the lower arm side of each phase constitutes the output terminal (U terminal, V terminal, or W terminal) of that phase.

A long terminal member 24 (second terminal member) is arranged on the negative Y-side of the circuit board 22 on the lower arm side of each phase. The terminal member 24 has a long shape extending from the end of the circuit board 22 toward the negative Y-side. The terminal member 24 is arranged next to the negative X-side of the terminal member 23. The terminal members 23 and 24 extend adjacent to each other and parallel along the Y-direction. Each terminal member 24 is formed inside the width (X-direction) of the respective circuit board 22. The terminal member 24 constitutes a low-potential input terminal (N terminal).

In addition, a long terminal member 25 (third terminal member) is arranged on the positive Y-axis side of the circuit board 22 on the lower arm side of each phase. The terminal member 25 extends toward the positive Y-axis side. Each terminal member 25 is formed inside the width (X-axis) of the corresponding circuit board 22. The terminal member 25 constitutes a gate terminal (G terminal). As shown in FIG. 2, the terminal member 25 is arranged on the opposite side of the terminal member 23 across the semiconductor elements 3 and 4 in a plan view.

As will be described in more detail below, the multiple circuit boards 22 and multiple terminal members 23, 24, and 25 are formed from a single metal plate and are connected by a rectangular frame-shaped runner portion 26 during the manufacturing process (see Figure 5B). In a later process, the runner portion 26 is removed, separating (cutting off) each circuit board 22 and each terminal member 23, 24, and 25. The integrated metal plate may also be called a lead frame or metal wiring board.

Semiconductor elements 3, 4 are arranged on the upper surface of each circuit board 22 via a bonding material S such as solder. The semiconductor elements 3, 4 are arranged side by side in the Y direction. The semiconductor elements 3, 4 are formed into a rectangular shape in a plan view using a semiconductor substrate made of, for example, silicon (Si) or silicon carbide (SiC). The semiconductor elements may be switching elements such as IGBTs (Insulated Gate Bipolar Transistors) or power MOSFETs (Metal Oxide Semiconductor Field Effect Transistors), or diodes such as FWDs (Free Wheeling Diodes).

In this embodiment, semiconductor element 3 located on the positive side in the Y direction is an IGBT element, and semiconductor element 4 located on the negative side in the Y direction is an FWD element. Semiconductor elements 3 and 4 may be connected in reverse parallel to each other. Note that this embodiment describes a case where the IGBT element and FWD element are configured separately, but this is not limited to this. As semiconductor elements, RC (Reverse Conducting)-IGBTs in which the IGBT element and FWD element are integrated, RB (Reverse Blocking)-IGBTs with sufficient reverse bias voltage resistance, etc. may also be used.

Furthermore, the shape, number, and location of the semiconductor elements 3 and 4 can be changed as appropriate. In this embodiment, the semiconductor elements 3 and 4 are so-called vertical switching elements in which functional elements such as transistors are formed on a semiconductor substrate, but they are not limited to this and may also be horizontal switching elements.

The above-mentioned semiconductor elements 3 and 4, circuit board 22, and terminal members 23 and 24 constitute an inverter circuit as shown in Figure 4. In Figure 4, IN (P) represents the positive terminal (high potential input terminal), IN (N) represents the negative terminal (low potential input terminal), and OUT (U), OUT (V), and OUT (W) represent the output terminals of each phase. Also shown is an example in which two semiconductor elements 3 and 4 are connected in anti-parallel.

The upper surface electrodes of semiconductor elements 3 and 4 are electrically connected by wiring member W. The upper surface electrode of semiconductor element 4 and one end of terminal member 24 are also electrically connected by wiring member W. Furthermore, the gate electrode 30 of semiconductor element 3 and one end of terminal member 25 are also electrically connected by wiring member W.

These wiring members W are made of conductive wire (bonding wire). The wire material can be any one of gold, copper, aluminum, gold alloy, copper alloy, and aluminum alloy, or a combination thereof. It is also possible to use materials other than wire as the wiring members. For example, ribbon can be used as the wiring member.

The laminated substrate 2, multiple semiconductor elements 3, terminal members, and wiring members W are packaged (sealed) in molded resin 5. As will be described in detail below, molded resin 5 can be formed by transfer molding. The molded resin 5 may be a thermosetting resin material such as epoxy resin or silicone rubber, and may further contain glass or ceramic materials as fillers. The molded resin 5 is preferably flexible and is a material that contains a thermosetting elastomer such as silicone rubber. This makes it easier to position the semiconductor module 1 along the heat sink 10, which has a cylindrical outer shape, as will be described below.

In general, in semiconductor modules, the substrate (laminated substrate) on which the semiconductor elements are mounted is usually flat, taking into consideration ease of assembly, heat dissipation, etc. Therefore, it is preferable that the location on which the semiconductor module is installed is also on a flat surface.

However, depending on the shape of the structure to which it is to be attached (for example, an automobile compressor or motor), it may be necessary to mount the semiconductor module on a curved mounting surface, such as a cylindrical surface. In this case, it is possible to form a flat portion on the structure to which it is to be attached, but considering the mounting space for the entire device, it is desirable to mount the semiconductor module in a shape that corresponds to the structure to which it is to be attached without increasing its size. Thus, there is a demand for semiconductor modules with mounting structures that correspond to the shape of the structure to which they are to be attached.

In the past, it was considered to arrange multiple semiconductor modules side by side on the top surface of a flat heat sink, then curve the heat sink and attach it to the curved surface. However, this type of structure is specialized for configurations with multiple semiconductor modules, and it also requires the metal heat sink itself to be curved. As a result, this conventional structure does not necessarily ensure flexibility in installation, and there is room for improvement.

The inventors therefore conceived the present invention to realize a structure in a single semiconductor module that can be curved and installed on a mounting surface. Specifically, in this embodiment, the circuit boards that make up the three-phase inverter circuit are divided into six circuit boards 22, one for each upper and lower arm of each phase, and are arranged side by side in the longitudinal direction (X direction) of a single continuous insulating plate 20. In addition, the heat sink that is normally placed on the underside of the insulating plate 20 is also divided into six heat sinks 21 and arranged so that they correspond directly below the six divided circuit boards 22.

That is, the lower surface of the heat sink 21 is separated along the boundary line L between adjacent circuit boards 22. More specifically, the heat sink 21 is divided into multiple pieces along the boundary line L. In this way, the lower surfaces of the multiple divided heat sinks 21 form multiple heat dissipation regions arranged side by side in the X direction in a plan view.

As a result, in the laminate substrate 2 alone, as shown in FIG. 2, the insulating plate 20 is exposed at locations along the boundary line L between adjacent circuit boards 22 or heat sinks 21. That is, no circuit board 22 is present above the boundary line L, and no heat sink 21 is present below the boundary line L. The boundary line L extends in a direction (the width direction, or Y direction, of the laminate substrate 2) perpendicular to the direction in which the multiple circuit boards 22 are arranged (the longitudinal direction, or X direction, of the laminate substrate 2). Therefore, near the boundary line L, the bending rigidity (resistance to bending) of the laminate substrate 2 in the longitudinal direction is adjusted (reduced) to the bending rigidity of one layer of the insulating plate 20, rather than that of three layers (insulating plate 20, heat sink 21, and circuit board 22). Therefore, the laminate substrate 2 (insulating plate 20) is prone to bending starting from the multiple boundary lines L. Therefore, as shown in FIG. 3, the laminate substrate 2 can be molded in a curved state when sealed with molded resin 5.

Specifically, the laminated substrate 2 is formed with a circuit board 22, an insulating plate 20, and a heat sink 21, in this order. The insulating plate 20 is formed from a single, continuous, rectangular plate with its length in the X direction. The upper surface of the insulating plate 20 has multiple (six) divided circuit boards 22 aligned in the X direction, with multiple (five) gaps aligned in the X direction. The lower surface of the insulating plate has multiple (six) divided heat sinks 21 aligned in the X direction corresponding to the circuit boards 22, with multiple (five) gaps aligned in the X direction corresponding to the gaps between the circuit boards 22. The laminated substrate 2 is curved in an arc shape that is convex upward (in the +Z direction) as a whole, with the multiple (five) opposing gaps between the heat sink 21 and the circuit board 22 curved.

More specifically, the laminated substrate 2 has a flat portion on which at least one of the circuit board 22 and the heat sink 21 is disposed, and a bent portion on which neither the circuit board 22 nor the heat sink 21 is disposed. Each bent portion is bent in a direction that convexes upward (toward +Z). As a result, the underside of the semiconductor module 1 is curved in an arc shape that convexes upward (toward +Z) as a whole. As a result, the semiconductor module 1 can be placed along a heat sink 10 that has a cylindrical outer shape and a curved mounting surface 11.

Furthermore, the area of the heat sink 21 in plan view is larger than the area of the corresponding circuit board 22. With this configuration, when the semiconductor elements 3 and 4 arranged on the circuit board 22 generate heat, the heat sink 21 diffuses that heat toward the heat sink 10 in accordance with the range of heat diffusion. As a result, the heat from the semiconductor elements 3 and 4 can be effectively dissipated.

In this way, in the semiconductor module 1 according to this embodiment, by dividing the circuit board 22 and heat sink 21 for each phase arm, it is possible to easily curve the laminated substrate 2 starting from the boundary line L between adjacent arms. As a result, it is possible to obtain a semiconductor module 1 that matches the shape of the curved mounting surface 11, enabling the semiconductor module 1 to be mounted in a space-saving manner.

In addition, in the semiconductor module 1 according to this embodiment, the insulating plate 20 is a single continuous piece, which ensures a sufficient creepage distance between the circuit board 22 and the heat sink 21. This allows the distance between adjacent circuit boards 22 and adjacent heat sinks 21 to be reduced. As a result, a compact semiconductor module 1 can be obtained that conforms to the shape of the curved mounting surface 11, making it possible to create a semiconductor module 1 that is space-saving.

Next, a method for manufacturing a semiconductor module according to this embodiment will be described with reference to Figures 5 to 13. Figures 5 to 14 are schematic diagrams showing an example of one step in the method for manufacturing a semiconductor module according to this embodiment. Figures 5A, 6A, and 7A are schematic cross-sectional views, and Figures 5B, 6B, and 7B are schematic plan views. Note that the method for manufacturing a semiconductor module shown below is merely an example, and is not limited to this configuration and can be modified as appropriate.

The manufacturing method for semiconductor module 1 according to this embodiment includes a laminated substrate preparation process (see FIG. 5), a chip placement process (see FIG. 6), a bonding process (see FIG. 7), a bending process (see FIGS. 8-9), a molding process (see FIGS. 10-12), a terminal molding process (see FIG. 13), and a circuit board placement process (see FIG. 14). The order in which these processes are performed may be changed or combined, provided that no contradictions exist.

First, as shown in Figures 5A and 5B, in the laminated substrate preparation process, a laminated substrate 2 is prepared by stacking an insulating plate 20 having an upper surface and a lower surface, a plurality of circuit boards 22 arranged in a predetermined direction (X direction) on the upper surface of the insulating plate 20, and a plurality of heat sinks 21 arranged in positions corresponding to the plurality of circuit boards 22 on the lower surface of the insulating plate 20.

As shown in Figure 5B in particular, the multiple circuit boards 22 and the multiple terminal members 23, 24, and 25 are formed from a single metal plate. More specifically, the multiple circuit boards 22 and the multiple terminal members 23, 24, and 25 are integrally connected by a rectangular frame-shaped runner portion 26.

Next, the chip placement process is carried out. As shown in Figures 6A and 6B, in this chip placement process, semiconductor elements 3 and 4 are placed on the upper surface of each circuit board 22. Specifically, one semiconductor element 3 and one semiconductor element 4 are placed on the upper surface of each circuit board 22 via bonding material S.

Next, the bonding process is carried out. As shown in Figures 7A and 7B, in the bonding process, the top electrodes of the semiconductor elements 3 and 4 are electrically connected by the wiring member W. The top electrode of the semiconductor element 4 is also electrically connected to one end of the terminal member 24 by the wiring member W. The gate electrode 30 of the semiconductor element 3 is also electrically connected to one end of the terminal member 25 by the wiring member W. In this case, in the bonding process, it is preferable to bond the wiring member W with a long slack, in anticipation of the laminated substrate 2 being bent in the subsequent bending process. This makes it possible to prevent the wiring member W from becoming stiff even after bending, preventing breakage.

Next, the bending process is carried out. As shown in Figures 8 and 9, the laminated substrate 2 after the chip placement process is placed in a mold (lower mold 12 and upper mold 13). A curved recess (concave) that is convex upward is formed in the lower mold 12 and the upper mold 13. The laminated substrate 2 is pressed against the recess in the lower mold 12 and bent to conform to the curved shape of the recess. That is, in the bending process, the laminated substrate 2 (insulating plate 20) is bent along a predetermined direction (X-axis direction) so as to be convex on one side in the thickness direction (Z-axis direction). Note that this embodiment describes a case in which the laminated substrate 2 is bent so as to be convex toward the positive side of the Z direction, but this is not limited to this and can be modified as appropriate. For example, the laminated substrate 2 may be curved so as to be convex toward the negative side of the Z direction. Furthermore, the laminated substrate 2 may include both a portion that is curved so as to be convex toward the positive side of the Z direction and a portion that is curved so as to be convex toward the negative side of the Z direction. Alternatively, the laminated substrate 2 may include a convexly curved portion and a flat portion. Furthermore, in this embodiment, the case where the laminated substrate 2 is curved in an arc shape is described, but this is not limited to this and can be modified as appropriate. For example, the laminated substrate 2 may be curved in an arc corresponding to a portion of an ellipse.

Next, the molding process is carried out. As shown in Figure 10, in the molding process, the lower mold 12 and upper mold 13 are brought close together to form a predetermined closed space within the mold. Then, as shown in Figure 11, mold resin 5 is filled into the closed space within the mold, packaging the laminated substrate 2 and semiconductor elements 3 and 4. This mold resin 5 is formed, for example, by transfer molding. By using transfer molding, there is no need to prepare a dedicated case, and it is possible to mount all the components and then seal and integrate these components all at once. Then, once the mold resin 5 has completely hardened, the lower mold 12 and upper mold 13 are retracted and opened, and a single semiconductor module 1 with the components integrated can be obtained.

Next, the terminal molding process is carried out. As shown in Figure 13, the runner portion 26 (see Figures 5-7) is removed, separating (cutting off) each circuit board 22 and each terminal member 23-25. Furthermore, each terminal member 23-25 is bent at a right angle along bend line B shown in Figure 13. This forms each terminal member 23-25 so that it extends toward the positive side of the Z direction.

Next, the circuit board placement process is carried out. As shown in Figure 14, in this process, a circuit board 6 (which may also be called a printed circuit board or a control board) is placed on multiple terminal members 23-25. Specifically, the circuit board 6 is composed of a printed circuit board that is rectangular in plan view, and through holes (not shown) are formed at locations corresponding to the tips of the multiple terminal members 23-25. The tips of each terminal member are inserted into the through holes and soldered, electrically connecting the circuit pattern on the circuit board 6 to each terminal member.

As shown in FIG. 14, a semiconductor device 100 (power conversion device) may be configured including a semiconductor module 1, a heat sink 10 that forms part of a cooler to which the semiconductor module 1 is attached, and a circuit board 6.

As described above, according to this embodiment, by dividing the circuit board 22 and heat sink 21 into separate arms, the laminated substrate 2 can be easily bent, and a semiconductor module 1 can be obtained that matches the shape of the curved mounting surface 11.

In the above embodiment, the components of the semiconductor module 1 are sealed by transfer molding, but this configuration is not limited to this. For example, a resin case and metal terminals may be formed separately, and various components may be placed inside the case, which is then filled with a sealing resin.

Furthermore, in the above embodiment, six heat sinks 21 are arranged directly below the six circuit boards 22, but this configuration is not limited to this. For example, the configuration shown in Figure 15 may also be used. Figure 15 shows variations of heat sinks according to modified examples.

In the above embodiment, the heat sink 21 is divided into multiple (six) pieces by the boundary line L. Here, "divided" refers to a state in which adjacent heat sinks 21 are completely separated with a predetermined gap between them. In a modified example, as shown in FIG. 15A, the underside of the insulating plate 20 may have a thin groove (heat sink 21a) extending in the Y direction between two adjacent heat sinks 21. That is, the underside of the heat sink 21 may be separated into multiple heat sink areas by grooves formed along the boundary line L so as to leave a predetermined thickness. Here, "separation" does not necessarily mean a state in which the heat sink 21 is completely divided, but also includes a state in which the underside heat sink area is divided into multiple pieces while leaving a small portion of the thickness of the heat sink 21. The grooves may form heat sinks 21a that are thinner than the surrounding heat sinks 21. In this case, it is preferable that the boundary line L between adjacent heat sinks 21 coincide with the boundary line L of the circuit board 22 located directly above. Furthermore, it is preferable that the boundary line L is located at a position that overlaps with the groove portion (heat sink 21a) of the heat sink 21. As a result, bending rigidity is reduced near the boundary line L. As a result, the laminated substrate 2 (insulating plate 20) is more likely to bend from multiple boundary lines L. Furthermore, on the underside of the insulating plate 20, another heat sink 21a may be placed between two adjacent heat sinks 21. In this case, it is preferable that the rigidity (hardness, etc.) of the other heat sink 21a is less than that of the heat sink 21. In this case, it is also preferable that the thickness of the heat sink 21a is less than that of the heat sink 21. In this way, by changing the configuration of the heat sink, it is possible to adjust (reduce) the flexibility (bending rigidity) of the laminated substrate 2 as a whole.

15B, identically shaped heat sinks 27 may be offset in the X direction and partially overlap in the Z direction, forming an expandable shutter-like heat sink 27 as a whole. In this case, the boundary line L between adjacent heat sinks 21 may be the shutter portion of the area facing the gap between adjacent circuit boards 22. Also, as shown in FIG. 15C, identically shaped heat sinks 28 may be offset not only in the X direction but also in the Y direction, forming a bendable heat sink by connecting multiple heat sinks alternately in the Y direction. Furthermore, as shown in FIG. 15D, a bendable heat sink like a bamboo blind may be formed by arranging and connecting multiple cylindrical heat sink members 29 elongated in the Y direction along the X direction. In this case, the boundary line L between adjacent heat sinks 21 may be in the area facing the gap between adjacent circuit boards 22. That is, in Figures 15A-15D, there is no circuit board 22 on the upper surface of the insulating plate 20, and one or more grooves exist in the heat sinks 21 (21a), 27-29 on the lower surface of the insulating plate 20, corresponding to the boundary lines L. As a result, bending rigidity is reduced near the boundary lines L. As a result, the laminated substrate 2 (insulating plate 20) is prone to bending starting from the multiple boundary lines L.

Furthermore, in the above embodiment, the number and placement locations of the semiconductor elements 3 and 4 are not limited to the above configuration and can be changed as appropriate.

Furthermore, in the above embodiment, the number and layout of circuit boards are not limited to the above configuration and can be changed as appropriate.

In addition, in the above embodiment, the laminated substrate 2 and semiconductor elements 3 and 4 are configured to be rectangular or square in plan view, but this configuration is not limited to this. These elements may also be configured to be polygonal shapes other than those described above.

Furthermore, while this embodiment and its variations have been described, other embodiments may be combinations of the above embodiments and variations in whole or in part.

Furthermore, this embodiment is not limited to the above-described embodiment and variations, and may be modified, substituted, or altered in various ways without departing from the spirit of the technical idea. Furthermore, if technological advances or derived technologies allow the technical idea to be realized in a different way, it may be implemented using that method. Therefore, the claims cover all embodiments that may fall within the scope of the technical idea.

The features of the above embodiment are summarized below.
The semiconductor module according to the above embodiment comprises a laminated substrate formed by stacking an insulating plate having an upper surface and a lower surface, a heat sink arranged on the lower surface of the insulating plate, and a plurality of circuit boards arranged on the upper surface of the insulating plate, and a semiconductor element arranged on the upper surface of each of the circuit boards, wherein the plurality of circuit boards are arranged side by side in a predetermined direction in a planar view, the lower surface of the heat sink is separated along the boundary line between adjacent circuit boards, and has a plurality of heat dissipation areas arranged side by side in the predetermined direction in a planar view, and the insulating plate is curved so as to be convex toward one side in the thickness direction along the predetermined direction.

Furthermore, in the semiconductor module according to the above embodiment, the heat dissipation areas are arranged in locations directly below the circuit boards, and the insulating plate is curved starting from the boundary line between the adjacent circuit boards or the heat dissipation areas.

Furthermore, in the semiconductor module according to the above embodiment, the boundary line extends in a direction intersecting the predetermined direction.

Furthermore, in the semiconductor module according to the above embodiment, the heat sink is divided into multiple pieces along the boundary line.

Furthermore, in the semiconductor module according to the above embodiment, the underside of the heat sink is separated into multiple heat dissipation areas by grooves formed along the boundary lines so as to leave a predetermined thickness.

Furthermore, in the semiconductor module according to the above embodiment, a three-phase inverter circuit is formed by a plurality of the circuit boards and semiconductor elements arranged on the upper surfaces of the circuit boards, and the circuit boards constituting each phase of the three-phase inverter circuit are arranged side by side in the predetermined direction.

Furthermore, in the semiconductor module according to the above embodiment, in each phase of the three-phase inverter circuit, the circuit board constituting the upper arm and the circuit board constituting the lower arm are arranged side by side in the predetermined direction.

Furthermore, the semiconductor module according to the above embodiment further includes first terminal members connected to the circuit boards and constituting wiring for the main current, the first terminal members being formed as elongated bodies extending in a direction intersecting the predetermined direction, and the first terminal members provided on each of the circuit boards being arranged side by side in the predetermined direction.

The semiconductor module according to the above embodiment further includes a second terminal member arranged on the side of the circuit board constituting the lower arm, the second terminal member being formed of an elongated body extending in a direction intersecting the predetermined direction and arranged adjacent to and parallel to the first terminal member.

The semiconductor module according to the above embodiment further includes a third terminal member arranged on the opposite side of the circuit board from the first terminal member, and the third terminal member is formed as an elongated body extending in a direction intersecting the predetermined direction.

Furthermore, in the semiconductor module according to the above embodiment, the first terminal member on the upper arm side constitutes a high-potential side input terminal, the first terminal member on the lower arm side constitutes an output terminal for each phase, the second terminal member constitutes a low-potential side input terminal, and the third terminal member constitutes a gate terminal, and the third terminal member is electrically connected to the gate electrode of the semiconductor element.

Furthermore, in the semiconductor module according to the above embodiment, the area of the heat sink in a plan view is larger than the area of the corresponding circuit board.

Furthermore, in the semiconductor module according to the above embodiment, the heat sink in plan view includes the entire area directly below the corresponding circuit board.

The method for manufacturing a semiconductor module according to the above embodiment also includes a laminated substrate preparation process for preparing a laminated substrate by stacking an insulating plate having an upper surface and a lower surface, a plurality of circuit boards arranged side by side in a predetermined direction on the upper surface of the insulating plate in a plan view, and a heat dissipation plate arranged on the lower surface of the insulating plate, the lower surface of which is separated along the boundary line between adjacent circuit boards, and which has a plurality of heat dissipation areas arranged side by side in the predetermined direction in a plan view; a chip placement process for placing semiconductor elements on the upper surface of each of the circuit boards; and a bending process for bending the insulating plate along the predetermined direction so that it is convex on one side in the thickness direction.

Furthermore, the manufacturing method for a semiconductor module according to the above embodiment further includes a molding step of encapsulating the laminated substrate and the semiconductor element with a molding resin after the bending step.

In addition, the semiconductor module manufacturing method according to the above embodiment further includes a terminal molding process in which the laminated substrate preparation process includes a metal wiring board in which multiple circuit boards and multiple terminal members are integrally connected via runner portions, and the runner portions are removed to mold the multiple terminal members.

Furthermore, the method for manufacturing a semiconductor module according to the above embodiment further includes a circuit board placement process for placing a circuit board on the plurality of terminal members after the terminal molding process.

As described above, the present invention has the effect of being able to properly secure semiconductor modules even on curved mounting surfaces, and is particularly useful for semiconductor modules that are mounted on curved mounting surfaces.

100: Semiconductor device 1: Semiconductor module 2: Laminated substrate 3: Semiconductor element 4: Semiconductor element 5: Molded resin 6: Circuit board 10: Heat sink 11: Mounting surface 12: Lower mold 13: Upper mold 20: Insulating plate 21: Heat sink 21a: Heat sink 22: Circuit board 23: Terminal member 24: Terminal member 25: Terminal member 26: Runner portion 27: Heat sink 28: Heat sink 29: Heat sink member 30: Gate electrode B: Bending line L: Boundary line S: Bonding material W: Wiring member

Claims (18)

a laminated substrate formed by laminating an insulating plate having an upper surface and a lower surface, a heat sink disposed on the lower surface of the insulating plate, and a plurality of circuit boards disposed on the upper surface of the insulating plate;
a semiconductor device disposed on an upper surface of each of the circuit boards;
The plurality of circuit boards are arranged side by side in a predetermined direction in a plan view,
the lower surface of the heat sink has a plurality of heat dissipation regions separated along the boundary lines of the adjacent circuit boards and arranged side by side in the predetermined direction in a plan view;
the insulating plate is curved along the predetermined direction so as to be convex on one side in a thickness direction ,
The heat sink is divided into a plurality of pieces along the boundary line,
A semiconductor module , wherein the area of the heat sink in a plan view is larger than the area of the corresponding circuit board . the plurality of heat dissipation regions are disposed at locations corresponding to the positions directly below the plurality of circuit boards;
The semiconductor module according to claim 1 , wherein the insulating plate is curved from a boundary line of the adjacent circuit board or the heat dissipation area. The semiconductor module described in claim 2, wherein the boundary line extends in a direction intersecting the predetermined direction. 4. The semiconductor module according to claim 1, wherein a three-phase inverter circuit is formed by a plurality of the circuit boards and semiconductor elements arranged on upper surfaces of the circuit boards, and the circuit boards forming each phase of the three -phase inverter circuit are arranged side by side in the predetermined direction. 5. The semiconductor module according to claim 4 , wherein in each phase of the three-phase inverter circuit, the circuit board constituting the upper arm and the circuit board constituting the lower arm are arranged side by side in the predetermined direction. a first terminal member connected to the circuit board and constituting a wiring for a main current;
the first terminal member is formed of an elongated body extending in a direction intersecting the predetermined direction,
6. The semiconductor module according to claim 5 , wherein the first terminal members provided on each of the circuit boards are arranged side by side in the predetermined direction. a second terminal member disposed on a side of the circuit board constituting the lower arm;
7. The semiconductor module according to claim 6 , wherein the second terminal members are formed as elongated bodies extending in a direction intersecting the predetermined direction, and are disposed adjacent to and extending parallel to the first terminal members. a third terminal member disposed on the opposite side of the circuit board from the first terminal member;
The semiconductor module according to claim 7 , wherein the third terminal member is formed as an elongated body extending in a direction intersecting the predetermined direction. the first terminal member on the upper arm side constitutes a high-potential input terminal,
the first terminal member on the lower arm side constitutes an output terminal for each phase,
the second terminal member constitutes a low-potential side input terminal,
the third terminal member constitutes a gate terminal,
The semiconductor module according to claim 8 , wherein the third terminal member is electrically connected to a gate electrode of the semiconductor element. 10. The semiconductor module according to claim 1 , wherein the heat sink in plan view includes the entire area directly below the corresponding circuit board. 11. The semiconductor module according to claim 1, wherein the insulating plate is a single continuous piece, and the upper surface and the lower surface are exposed along the boundary line. 12. The semiconductor module according to claim 1, wherein the gap between adjacent heat sinks has an area smaller than that of the gap between adjacent circuit boards in a plan view. 13. The semiconductor module according to claim 1, wherein another heat sink having a lower rigidity than the heat sink is disposed between two adjacent heat sinks on the lower surface of the insulating plate. 13. The semiconductor module according to claim 1, wherein the heat sinks of the same shape are arranged so as to be shifted in the predetermined direction and partially overlap in the thickness direction, and the semiconductor module as a whole is formed in the shape of an expandable shutter. a laminated substrate preparation process for preparing a laminated substrate by laminating an insulating plate having an upper surface and a lower surface, a plurality of circuit boards arranged side by side in a predetermined direction in a plan view on the upper surface of the insulating plate, and a heat dissipation plate arranged on the lower surface of the insulating plate, the lower surface being separated along the boundary line between adjacent circuit boards, the heat dissipation plate having a plurality of heat dissipation regions arranged side by side in the predetermined direction in a plan view, the heat dissipation plate being divided into a plurality of pieces along the boundary line, and the area in a plan view being larger than the area of the corresponding circuit board ;
a chip placement step of placing a semiconductor element on the upper surface of each of the circuit boards;
a bending step of bending the insulating plate along the predetermined direction so that it is convex on one side in a thickness direction. The method for manufacturing a semiconductor module according to claim 15 , further comprising a molding step of sealing the laminated substrate and the semiconductor element with a molding resin after the bending step. In the laminated substrate preparation step, the laminated substrate is formed of a metal wiring board in which the plurality of circuit boards and the plurality of terminal members are integrally connected via runner portions,
17. The method for manufacturing a semiconductor module according to claim 15 , further comprising a terminal molding step of removing the runner portion to mold the plurality of terminal members. The method for manufacturing a semiconductor module according to claim 17 , further comprising, after the terminal molding step, a circuit board placement step of placing a circuit board on the plurality of terminal members.