Insulated circuit board, method for manufacturing the same, and cooling system

Abstract

The present invention provides an insulating circuit board with high heat dissipation performance, a method for manufacturing the same, and a cooling system. [Solution] The insulating circuit board 10 for the semiconductor device 50 comprises an insulating substrate 11 and a circuit layer 20 disposed on the insulating substrate 11. Recesses 26, 16 are formed on the circuit layer 20 and / or on the surface 11a of the insulating substrate 11 that faces the circuit layer 20.

Description

Technical Field

[0001] The present disclosure relates to an insulating circuit board, a method for manufacturing the same, and a cooling system.

Background Art

[0002] In recent years, for example, there are semiconductor devices used in electrical equipment for high currents that include an insulating circuit board (see Patent Documents 1 and 2).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] In such a semiconductor device, since a large current flows inside, the amount of heat generated is also large. In order to avoid various problems caused by heat, high heat dissipation is required for the members constituting the semiconductor device for high currents.

[0005] The present disclosure provides an insulating circuit board with high heat dissipation performance, a method for manufacturing the same, and a cooling system.

Means for Solving the Problems

[0006] Embodiments of the present disclosure relate to the following [1] to

[11] .

[0007] [1] An insulating circuit board for a semiconductor device, comprising an insulating base material and a circuit layer disposed on the insulating base material, wherein a recess is formed on the circuit layer and / or on the surface of the insulating base material on the circuit layer side. (Note: The Japanese text seems to be a bit unclear in terms of grammar or intended meaning in this part. The translation is done as accurately as possible based on the literal words. In a more polished text, it might be better expressed as "An insulating circuit board for a semiconductor device includes an insulating substrate and a circuit layer disposed on the insulating substrate, and a recess is formed on the circuit layer and / or on the surface of the insulating substrate on the side of the circuit layer." But this follows the instruction of not adding extra line breaks and keeping the original text structure as much as possible.)

[0008] [2] The insulating circuit board according to [1], wherein the insulating substrate has through holes communicating with the recesses.

[0009] [3] The insulating circuit board according to [1] or [2], wherein a metal layer is laminated on the side of the insulating substrate opposite to the circuit layer.

[0010] [4] The insulating circuit board according to [3], wherein the metal layer has through holes communicating with the recesses.

[0011] [5] The insulating circuit board according to [3] or [4], wherein the metal layer comprises a composite metal material.

[0012] [6] The recess is formed on the surface of the circuit layer facing the insulating substrate, as described in any one of [1] to [5].

[0013] [7] An insulating circuit board according to any one of [1] to [6], wherein two circuit layers are arranged on the insulating substrate, and each of the two circuit layers has the recess.

[0014] [8] The insulating circuit board according to any one of [1] to [7], wherein the circuit layer or the metal layer comprises a composite metal material.

[0015] [9] The insulated circuit board according to [1], wherein the recess is located between the two surfaces of the circuit layer.

[0016] A cooling system comprising a semiconductor device including an insulating circuit board as described in any one of

[10] [1] to [9], and a cooling mechanism for introducing a refrigerant into the recess of the insulating circuit board.

[0017]

[11] A method for manufacturing an insulating circuit board for a semiconductor device, comprising the steps of: preparing a circuit layer; preparing an insulating substrate; and bonding the circuit layer to the insulating substrate, wherein a recess is formed on the circuit layer and / or on the surface of the insulating substrate that is on the side of the circuit layer. [Effects of the Invention]

[0018] According to the present disclosure, the heat dissipation performance of the insulating circuit board is enhanced.

Brief Description of the Drawings

[0019] [Figure 1] FIG. 1 is a cross-sectional view showing an insulating circuit board according to the first embodiment. [Figure 2] FIG. 2 is an enlarged plan view showing the circuit layer of the insulating circuit board (viewed in the direction of arrow II in FIG. 1). [Figure 3] FIG. 3 is an enlarged plan view showing the circuit layer of the insulating circuit board according to a modified example. [[ID=佃]] [Figure 4] FIG. 4 is an enlarged plan view showing the circuit layer of the insulating circuit board according to a modified example. [Figure 5] FIG. 5 is a cross-sectional view showing a semiconductor device according to an embodiment. [Figure 6] FIGS. 6(A)-(K) are cross-sectional views showing a method for manufacturing an insulating circuit board according to the first embodiment. [Figure 7] FIGS. 7(A)-(D) are cross-sectional views showing a method for manufacturing an insulating circuit board according to a modified example. [Figure 8] FIG. 8 is a cross-sectional view showing an insulating circuit board according to the first modified example. [Figure 9] FIG. 9 is a cross-sectional view showing an insulating circuit board according to the second modified example. [Figure 10] FIG. 10 is a cross-sectional view showing an insulating circuit board according to the third modified example. [Figure 11] FIG. 11 is a cross-sectional view showing an insulating circuit board according to the second embodiment. [Figure 12] FIGS. 12(A)-(D) are cross-sectional views showing a method for manufacturing an insulating circuit board according to the second embodiment.

Modes for Carrying Out the Invention

[0020] (First Embodiment) Hereinafter, the first embodiment will be described with reference to FIGS. 1 to 10. In the following figures, the same parts are denoted by the same reference numerals, and some detailed descriptions may be omitted.

[0021] In this specification, half-etching refers to etching a material to be etched in its thickness direction up to a certain point. The thickness of the material to be etched after half-etching is, for example, 30% to 85%, preferably 40% to 60%, of the thickness of the material to be etched before half-etching.

[0022] In this specification, a metal layer is any layer containing metal, and does not necessarily have to be composed entirely of metal. As will be described later, a composite material containing metal may be used as the metal layer. Also, "A and / or B" means "at least one of A and B".

[0023] (Configuration of an insulated circuit board) Figures 1 and 2 illustrate the schematic of the insulating circuit board for semiconductor devices according to this embodiment. Figures 1 and 2 are diagrams showing the insulating circuit board according to this embodiment.

[0024] The insulating circuit board 10 shown in Figures 1 and 2 is used in the manufacture of a semiconductor device 50 (Figure 5). The insulating circuit board 10 comprises an insulating substrate 11 and a circuit layer 20 disposed on the insulating substrate 11. A recess 26 is formed on the second surface 20b of the circuit layer 20, which will be described later, on the insulating substrate 11 side. A metal layer 12 is laminated on the surface of the insulating substrate 11 opposite to the circuit layer 20.

[0025] The insulating substrate 11 has a first surface 11a and a second surface 11b. The second surface 11b is located on the opposite side of the first surface 11a. The first surface 11a is the surface facing the semiconductor element 51, which will be described later. The first surface 11a may also be called the "front surface" or "upper surface". The second surface 11b is the surface facing the cooling mechanism 60, which will be described later. The second surface 11b may also be called the "back surface" or "lower surface".

[0026] The insulating substrate 11 is a plate-shaped member having a substantially uniform thickness. The insulating substrate 11 has insulating properties. The insulating substrate 11 may be composed of a ceramic material. Examples of ceramic materials include aluminum nitride, alumina, zirconia-reinforced alumina, and silicon nitride. Alternatively, the insulating substrate 11 may be composed of a resin material. Examples of resin materials include epoxy resins containing inorganic fillers filled to increase thermal conductivity.

[0027] When the insulating substrate 11 is made of a ceramic material, the thickness t1 of the insulating substrate 11 may be 100 μm or more and 2000 μm or less, or 250 μm or more and 1000 μm or less. When the insulating substrate 11 is made of a ceramic material, the thickness t1 of the insulating substrate 11 may be thicker than the thickness t2 of the metal layer 12.

[0028] When the insulating substrate 11 is made of a resin material, the thickness t1 of the insulating substrate 11 may be 20 μm or more and 300 μm or less, or 60 μm or more and 150 μm or less. When the insulating substrate 11 is made of a resin material, the thickness t1 of the insulating substrate 11 may be thinner than the thickness t2 of the metal layer 12.

[0029] The insulating substrate 11 has a first through hole 11c and a second through hole 11d. The first through hole 11c and the second through hole 11d each penetrate the insulating substrate 11 in the thickness direction. The first through hole 11c and the second through hole 11d are spaced apart from each other in the planar direction. The positions of the first through hole 11c and the second through hole 11d are arbitrary as long as they are spaced apart in the planar direction. The first through hole 11c and the second through hole 11d are appropriately positioned according to the shape of the recess 26 (flow channel) described later, but it is preferable that they be further apart as shown in the figure. The first through hole 11c communicates with the first communication portion 26c of the recess 26 described later. The second through hole 11d communicates with the second communication portion 26d of the recess 26 described later.

[0030] Refrigerant from the cooling mechanism 60 flows into the first through-hole 11c. The refrigerant that flows into the first through-hole 11c flows out toward the first communication section 26c. The first through-hole 11c may also be called an inlet hole. Refrigerant from the second communication section 26d flows into the second through-hole 11d and flows out toward the cooling mechanism 60. The second through-hole 11d may also be called an outlet hole. The first through-hole 11c and the second through-hole 11d may each be circular in plan view. The width W1 of the first through-hole 11c and the second through-hole 11d may be 0.01 mm or more and 100 mm or less, or 0.1 mm or more and 100 mm or less.

[0031] The circuit layer 20 is bonded to the first surface 11a of the insulating substrate 11. The circuit layer 20 has a first surface 20a and a second surface 20b. The second surface 20b is located on the opposite side of the first surface 20a. The first surface 20a is the surface on which the semiconductor element 51, described later, is mounted. The first surface 20a may also be called the "front surface" or "upper surface". The second surface 20b is the surface facing the insulating substrate 11. The second surface 20b may also be called the "back surface" or "lower surface".

[0032] Multiple circuit layers 20 are provided on the insulating substrate 11. In this embodiment, two circuit layers 20 are provided on the insulating substrate 11. The two circuit layers 20 are spaced apart from each other and are electrically insulated from each other. A semiconductor element 51, described later, is mounted on one of the circuit layers 20. A bonding wire 52, described later, is connected to the other circuit layer 20. Each circuit layer 20 has a shape smaller than the insulating substrate 11 when viewed from above.

[0033] The circuit layer 20 may be made of a metal such as copper, copper alloy, or 42 alloy (Fe alloy with 42% Ni). The thickness t3 of the circuit layer 20 may be 0.02 mm or more and 6 mm or less, or 0.06 mm or more and 2 mm or less.

[0034] The circuit layer 20 has a recess 26. Coolant from the cooling mechanism 60 flows through the recess 26, as will be described later. The recess 26 may also be called a flow path. The recess 26 is formed on the second surface 20b of the circuit layer 20. The recess 26 is a non-penetrating portion formed by thinning the circuit layer 20 partway along its thickness. The recess 26 is not exposed on the first surface 20a side of the circuit layer 20.

[0035] The recess 26 has a first communication portion 26c located on one side and a second communication portion 26d located on the other side. The first communication portion 26c communicates with the first through hole 11c of the insulating substrate 11 and overlaps with the first through hole 11c in a plan view. The first communication portion 26c may have the same shape as the first through hole 11c in a plan view, or it may have a different shape. The second communication portion 26d communicates with the second through hole 11d of the insulating substrate 11 and overlaps with the second through hole 11d in a plan view. The second communication portion 26d may have the same shape as the second through hole 11d in a plan view, or it may have a different shape.

[0036] Refrigerant from the cooling mechanism 60 flows into the first connecting section 26c. The first connecting section 26c may also be called an inlet or inlet hole. Refrigerant flows out from the second connecting section 26d and returns to the cooling mechanism 60 side. The second connecting section 26d may also be called an outlet or outlet hole.

[0037] A space 26b is formed between the first connecting section 26c and the second connecting section 26d. The refrigerant flowing in from the first connecting section 26c passes through space 26b, cooling the circuit layer 20. The refrigerant that has cooled the circuit layer 20 flows out from space 26b through the second connecting section 26d. Space 26b may also be called a main flow path or groove.

[0038] The depth d1 of the recess 26 may be 5% to 95% of the thickness t3 of the circuit layer 20, or 30% to 60%. The depth d1 of the recess 26 refers to the distance between the second surface 20b and the deepest part of the recess 26.

[0039] As shown in Figure 2, the recess 26 may have a meandering shape in plan view. The space 26b of the recess 26 extends in a single meandering curve between the first communication portion 26c and the second communication portion 26d. Alternatively, the space 26b of the recess 26 may have an angular (connected line segment) meandering shape. A peripheral wall portion 20c is formed around the recess 26. The peripheral wall portion 20c is not thinned from either the first surface 20a or the second surface 20b. The recess 26 is surrounded by the peripheral wall portion 20c in plan view. Therefore, the refrigerant in the recess 26 does not flow out or into any location other than the first communication portion 26c and the second communication portion 26d. The width W2 of the recess 26 may be 0.01 mm or more and 100 mm or less, or 0.1 mm or more and 100 mm or less. The recess 26 has a meandering shape in plan view, which allows the refrigerant to be transported substantially uniformly into the circuit layer 20.

[0040] As shown in Figure 3, the recess 26 may have a planar area when viewed from above. The space 26b of the recess 26 forms a wide area between the first connecting portion 26c and the second connecting portion 26d. The recess 26 may be a polygon such as a roughly circular, roughly elliptical, or roughly quadrilateral when viewed from above. The maximum width W3 of the recess 26 may be 1 mm or more and 100 mm or less, or 2 mm or more and 10 mm or less. By having a planar area when viewed from above, the recess 26 can transport the refrigerant over a wide area within the circuit layer 20.

[0041] As shown in Figure 4, the recess 26 may have a grid shape in plan view. The space 26b of the recess 26 has a rectangular or parallelogram grid shape between the first communication section 26c and the second communication section 26d. The recess 26 may also have a triangular grid shape in plan view. The width W4 of the recess 26 may be 0.01 mm or more and 200 mm or less, or 10 mm or more and 20 mm or less. By having a grid shape in plan view, the recess 26 can transport the refrigerant over a wide area within the circuit layer 20.

[0042] The planar shape of the recess 26 can be any shape other than those shown in Figures 2 to 4, as long as it is a form that allows for cooling of the circuit layer 20.

[0043] Referring again to Figure 1, the metal layer 12 is bonded to the second surface 11b of the insulating substrate 11. The metal layer 12 has a first surface 12a and a second surface 12b. The second surface 12b is located on the opposite side of the first surface 12a. The first surface 12a is bonded to the second surface 11b of the insulating substrate 11. The first surface 12a may also be called the "front surface" or "upper surface". The second surface 12b is the surface facing the cooling mechanism 60, which will be described later. The second surface 12b may also be called the "back surface" or "lower surface".

[0044] The metal layer 12 is a layer that relieves stress during manufacturing and increases the strength of the insulating circuit board 10. The metal layer 12 may also be called a metal base. The metal layer 12 may be a flat metal plate. The metal layer 12 may have the same shape as the insulating substrate 11 in plan view. Alternatively, the metal layer 12 may have a smaller shape than the insulating substrate 11 in plan view, or a larger shape than the insulating substrate 11. The metal layer 12 may be composed of metals such as copper, copper alloy, 42 alloy (Fe alloy with 42% Ni), aluminum, or iron. The thickness t2 of the metal layer 12 may be 0.01 mm or more and 10 mm or less, or 0.03 mm or more and 5 mm or less.

[0045] The metal layer 12 has a third through-hole 12c and a fourth through-hole 12d. The third through-hole 12c and the fourth through-hole 12d each penetrate the metal layer 12 in the thickness direction. The third through-hole 12c and the fourth through-hole 12d are spaced apart from each other in the planar direction. The third through-hole 12c communicates with the recess 26 via the first through-hole 11c of the insulating substrate 11. The fourth through-hole 12d communicates with the recess 26 via the second through-hole 11d of the insulating substrate 11.

[0046] The third through-hole 12c overlaps the first through-hole 11c of the insulating substrate 11 in a plan view. The third through-hole 12c may have the same shape as the first through-hole 11c or a different shape in a plan view. The fourth through-hole 12d overlaps the second through-hole 11d of the insulating substrate 11 in a plan view. The second connecting portion 26d may have the same shape as the second through-hole 11d or a different shape in a plan view.

[0047] Refrigerant from the cooling mechanism 60 flows into the third through-hole 12c. The refrigerant that flows into the third through-hole 12c flows out toward the first through-hole 11c of the insulating substrate 11. The third through-hole 12c may also be called an inlet hole. Refrigerant from the second through-hole 11d of the insulating substrate 11 flows into the fourth through-hole 12d and flows out toward the cooling mechanism 60. The fourth through-hole 12d may also be called an outlet hole. The third through-hole 12c and the fourth through-hole 12d may each be circular in plan view. The width W5 of the third through-hole 12c and the fourth through-hole 12d may be 0.01 mm or more and 100 mm or less, or 0.1 mm or more and 100 mm or less.

[0048] (Configuration of a semiconductor device) Next, a semiconductor device 50 manufactured using the insulating circuit board 10 according to this embodiment will be described with reference to Figure 5. Figure 5 is a cross-sectional view showing the semiconductor device 50 according to this embodiment.

[0049] The semiconductor device (semiconductor package) 50 shown in Figure 5 is a power semiconductor device used, for example, in electrical equipment for high currents. As shown in Figure 5, the semiconductor device 50 comprises an insulating circuit board 10, a semiconductor element 51, bonding wires (connecting members) 52, a sealing resin 53, a case 56, and external terminals 57.

[0050] The semiconductor element 51 is mounted on one circuit layer 20 of the insulating circuit board 10 via a solder layer 54. The semiconductor element 51 has multiple electrodes. One electrode of the semiconductor element 51 is electrically connected to one circuit layer 20 via the solder layer 54. The semiconductor element 51 is not particularly limited and can be any type of semiconductor element that is commonly used. The semiconductor element 51 may be a power semiconductor element. The semiconductor element 51 may be an integrated circuit such as a MOSFET, for example.

[0051] The bonding wire 52 electrically connects the semiconductor element 51 to the other circuit layer 20. The bonding wire 52 is made of a highly conductive material such as gold or copper. One end of the bonding wire 52 is electrically connected to the electrode of the semiconductor element 51. The other end of the bonding wire 52 is electrically connected to the other circuit layer 20.

[0052] The sealing resin 53 encapsulates the insulating circuit board 10, semiconductor element 51, bonding wire 52, and external terminal 57. The sealing resin 53 can be a thermosetting resin such as silicone resin or epoxy resin, or a thermoplastic resin such as PPS resin. The sealing resin 53 is embedded within the case 56. The sealing resin 53 adheres closely to each circuit layer 20.

[0053] The case 56 constitutes the outer shell of the semiconductor device 50. The case 56 houses the insulating circuit board 10, semiconductor elements 51, bonding wires 52, external terminals 57, and sealing resin 53. The case 56 can be made of resins such as epoxy or polyphenylene sulfide. A bottom opening 56a is formed at the bottom of the case 56. The metal layer 12 of the insulating circuit board 10 is placed in the bottom opening 56a.

[0054] The two external terminals 57 electrically connect to the circuit layer 20 of the insulating substrate 11 and to an external wiring board (not shown), respectively. One external terminal 57 is electrically connected to one circuit layer 20, and the other external terminal 57 is electrically connected to the other circuit layer 20. Part of each external terminal 57 is housed within the sealing resin 53, while the other part extends outward from the sealing resin 53. The parts of the external terminals 57 that extend outward from the sealing resin 53 are located above the case 56. Metal materials such as copper, copper alloy, 42 alloy (Fe alloy with 42% Ni), aluminum, and iron can be used as the external terminals 57.

[0055] The configuration of the insulating circuit board 10 is the same as that shown in Figures 1 and 2 above, so a detailed explanation is omitted here.

[0056] The semiconductor device 50 is placed on a cooling mechanism 60. The cooling mechanism 60 introduces a refrigerant into the recess 26 of the insulating circuit board 10. The cooling mechanism 60 uses the refrigerant to release heat from the semiconductor element 51 to the outside. The cooling mechanism 60 may have a pump to deliver the refrigerant and a heat exchanger to cool the recirculated refrigerant. As the refrigerant, a liquid such as water, or a gas such as air or nitrogen can be used. The cooling mechanism 60 has a refrigerant outlet 61 and a refrigerant inlet 62. The refrigerant outlet 61 is connected to the third through-hole 12c of the metal layer 12. The refrigerant inlet 62 is connected to the fourth through-hole 12d of the metal layer 12. The refrigerant flowing out from the refrigerant outlet 61 flows into the third through-hole 12c and then passes through the recess 26 of the circuit layer 20. The refrigerant that has passed through the recess 26 and flowed out from the fourth through-hole 12d flows into the refrigerant inlet 62.

[0057] The cooling system 70 is comprised of a semiconductor device 50 including the insulating circuit board 10 described above, and a cooling mechanism 60 that introduces a refrigerant into the recess 26 of the insulating circuit board 10. In this embodiment, such a cooling system 70 is also provided.

[0058] (Manufacturing method for insulating circuit boards) Next, the manufacturing method of the insulating circuit board 10 shown in Figures 1 and 2 will be explained using Figures 6(A)-(K). Figures 6(A)-(K) are cross-sectional views showing the manufacturing method of the insulating circuit board 10 according to this embodiment.

[0059] The circuit layer 20 is fabricated by the process shown in Figures 6(A)-(D).

[0060] In this case, first, a flat metal substrate 20A is prepared as shown in Figure 6(A). As the metal substrate 20A, a substrate made of metal such as copper, copper alloy, or 42 alloy (Fe alloy with 42% Ni) can be used. It is preferable to use a metal substrate 20A that has been degreased and cleaned on both sides.

[0061] Next, a photosensitive resist is applied to both sides of the metal substrate 20A and dried. Subsequently, the photosensitive resist on the metal substrate 20A is exposed to light through a photomask and developed. This forms etching resist layers 32 and 33 (Figure 6(B)). The etching resist layer 32 on one side has an opening 32b. The etching resist layer 33 on the other side has an opening 33b. For example, a dry film resist may be used as the etching resist layers 32 and 33.

[0062] Next, the metal substrate 20A is etched (Figure 6(C)). Specifically, etching is performed on the metal substrate 20A using an etching solution, with etching resist layers 32 and 33 acting as corrosion-resistant films. The etching solution can be appropriately selected depending on the material of the metal substrate 20A used. For example, when copper is used as the metal substrate 20A, a ferric chloride aqueous solution is usually used as the etching solution, and spray etching may be performed from both sides of the metal substrate 20A. As a result, one circuit layer 20 on which the semiconductor element 51 is mounted and the other circuit layer 20 to which the bonding wire 52 is connected are formed on the metal substrate 20A. On one circuit layer 20, a portion is thinned from one side by half-etching, forming a recess 26.

[0063] Next, the etching resist layers 32 and 33 on both sides of the metal substrate 20A are peeled off (Figure 6(D)). This yields the circuit layer 20.

[0064] The circuit layer 20 may also be manufactured by cutting and machining a flat metal substrate 20A.

[0065] Furthermore, the metal layer 12 is fabricated by the process shown in Figures 6(E)-(H).

[0066] In this case, first, a flat metal substrate 12A is prepared as shown in Figure 6(E). As the metal substrate 12A, a substrate made of metal such as copper, copper alloy, or 42 alloy (Fe alloy with 42% Ni) can be used. It is preferable to use a metal substrate 12A that has been degreased and cleaned on both sides.

[0067] Next, a photosensitive resist is applied to both sides of the metal substrate 12A and dried. Subsequently, the photosensitive resist on the metal substrate 12A is exposed to light through a photomask and developed. This forms etching resist layers 34 and 35 (Figure 6(F)). The etching resist layer 34 on one side has an opening 34b. The etching resist layer 35 on the other side has an opening 35b. For example, a dry film resist may be used as the etching resist layers 34 and 35.

[0068] Next, the metal substrate 12A is etched (Figure 6(G)). Specifically, etching is performed on the metal substrate 12A using an etching solution, with etching resist layers 34 and 35 acting as corrosion-resistant films. The etching solution can be appropriately selected depending on the material of the metal substrate 12A used. For example, when copper is used as the metal substrate 12A, a ferric chloride aqueous solution is usually used as the etching solution, and spray etching can be performed from both sides of the metal substrate 12A. This forms a third through-hole 12c and a fourth through-hole 12d in the metal substrate 12A.

[0069] Next, the etching resist layers 34 and 35 on both sides of the metal substrate 12A are peeled off (Figure 6(H)). This yields the metal layer 12.

[0070] The metal layer 12 may also be manufactured by forming a third through-hole 12c and a fourth through-hole 12d in a flat metal substrate 12A by cutting and machining.

[0071] Furthermore, the insulating substrate 11 is manufactured by the process shown in Figures 6(I)-(J).

[0072] In this case, first, a flat insulating material substrate 11A is prepared as shown in Figure 6(I). The insulating material substrate 11A may be composed of ceramic materials such as aluminum nitride, alumina, zirconia-reinforced alumina, or silicon nitride. Alternatively, the insulating material substrate 11A may be composed of a resin material such as an epoxy resin containing an inorganic filler filled to increase thermal conductivity.

[0073] Next, as shown in Figure 6(J), a first through-hole 11c and a second through-hole 11d are formed in the insulating material substrate 11A by cutting and machining. This gives rise to the insulating substrate 11.

[0074] The insulating substrate 11 may also be manufactured by forming a first through-hole 11c and a second through-hole 11d in a flat insulating material substrate 11A by etching.

[0075] The order of the above-mentioned steps—the process of fabricating the circuit layer 20 (Figure 6(A)-(D)), the process of fabricating the metal layer 12 (Figure 6(E)-(H)), and the process of fabricating the insulating substrate 11 (Figure 6(I)-(J))—does not matter.

[0076] Subsequently, the circuit layer 20 and the metal layer 12 are bonded to the insulating substrate 11. Specifically, the circuit layer 20 is bonded to the first surface 11a of the insulating substrate 11, and the metal layer 12 is bonded to the second surface 11b of the insulating substrate 11 (Figure 6(K)). At this time, the recess 26 of the circuit layer 20, the first through hole 11c of the insulating substrate 11, and the third through hole 12c of the metal layer 12 are in communication with each other. Also, the recess 26 of the circuit layer 20, the second through hole 11d of the insulating substrate 11, and the fourth through hole 12d of the metal layer 12 are in communication with each other.

[0077] The method of joining the circuit layer 20 and the metal layer 12 to the insulating substrate 11 is not limited. For example, an indirect joining method using an adhesive such as an activated metal brazing material may be used. Alternatively, a direct joining method such as diffusion bonding may be used.

[0078] In this way, the insulating circuit board 10 shown in Figures 1 and 2 is obtained.

[0079] The insulating circuit board 10 shown in Figures 1 and 2 is used inside the semiconductor device 50, as shown in Figure 5. In the semiconductor device 50 shown in Figure 5, a power semiconductor element is used as the semiconductor element 51, in particular, and a lot of heat is generated from the semiconductor element 51.

[0080] In contrast, according to this embodiment, a recess 26 is formed on the second surface 20b of the circuit layer 20. Coolant from the cooling mechanism 60 flows into this recess 26. Specifically, the coolant flowing out from the coolant outlet 61 of the cooling mechanism 60 reaches the space 26b of the recess 26 by sequentially passing through the third through-hole 12c, the first through-hole 11c, and the first communication part 26c. As the coolant passes through the space 26b of the recess 26, it removes heat from the semiconductor element 51. Subsequently, the coolant flowing out from the second communication part 26d of the recess 26 reaches the coolant inlet 62 by sequentially passing through the second through-hole 11d and the fourth through-hole 12d. After that, the coolant is cooled again within the cooling mechanism 60. Thereafter, the above process is repeated, and the coolant circulates between the circuit layer 20 and the cooling mechanism 60 to cool the semiconductor element 51. This effectively releases heat from the semiconductor element 51.

[0081] Furthermore, according to this embodiment, a metal layer 12 is laminated on the side of the insulating substrate 11 opposite to the circuit layer 20. This reduces stress during the manufacturing of the insulating circuit board 10 and increases the strength of the insulating circuit board 10.

[0082] (Variable example of a manufacturing method for an insulating circuit board) Next, a modified example of the manufacturing method of the insulating circuit board 10 shown in Figures 1 and 2 will be described using Figures 7(A)-(D). Figures 7(A)-(D) are cross-sectional views showing the manufacturing method of the insulating circuit board 10 according to this embodiment.

[0083] First, the circuit layer 20 is fabricated in much the same manner as shown in Figures 6(A)-(D) (Figure 7(A)).

[0084] Next, as shown in Figure 7(B), a flat insulating material substrate 11A is prepared, and a circuit layer 20 is laminated on one side of the insulating material substrate 11A. A conductive layer 36 is formed on the other side of the insulating material substrate 11A. As for the method of forming the circuit layer 20 and the conductive layer 36, for example, an indirect bonding method using an adhesive such as an activated metal brazing material may be used, or a direct bonding method such as diffusion bonding may be used. The material of the conductive layer 36 is preferably, for example, copper, nickel, tin, silver, gold, nickel alloy, nickel-chromium alloy, etc. The thickness of the conductive layer 36 may be formed in the range of 10 nm to 1000 nm.

[0085] Next, as shown in Figure 7(C), the conductive layer 36 may be used as a seed layer, and metals such as copper, nickel, tin, silver, gold, and nickel alloys may be deposited on the conductive layer 36 using an electroplating method, or solder material may be applied. After that, metal foils such as copper, copper alloys, and 42 alloys (Fe alloy with 42% Ni) are bonded to it to form a metal substrate 12A. The conductive layer 36 may be substantially integrated with the metal substrate 12A.

[0086] Next, as shown in Figure 7(D), the insulating material substrate 11A and the metal substrate 12A are subjected to cutting and machining. This creates a first through hole 11c and a second through hole 11d in the insulating material substrate 11A. Additionally, a third through hole 12c and a fourth through hole 12d are formed in the metal substrate 12A.

[0087] In this way, the insulating circuit board 10 shown in Figures 1 and 2 is obtained.

[0088] (A modified example of an insulated circuit board) Next, various modifications of the insulating circuit board 10 according to this embodiment will be described with reference to Figures 8 to 10. In Figures 8 to 10, the same reference numerals are used for parts that are the same as those shown in Figures 1 to 5, and detailed descriptions are omitted.

[0089] (First variation) Figure 8 is a cross-sectional view showing an insulating circuit board 10 according to the first modified example.

[0090] As shown in Figure 8, recesses 26 may be formed not only in one circuit layer 20 on which the semiconductor element 51 is mounted, but also in the other circuit layer 20 to which the bonding wire 52 is connected. Coolant from the cooling mechanism 60 flows through the recesses 26 of the two circuit layers 20. The configurations of the recesses 26 of the two circuit layers 20 may be identical or different.

[0091] Furthermore, refrigerant flows into the recesses 26 of the two circuit layers 20 from the first through-hole 11c of the insulating substrate 11 and the third through-hole 12c of the metal layer 12, respectively. The refrigerant that has passed through the recesses 26 of each circuit layer 20 flows out toward the cooling mechanism 60 sequentially through the second through-hole 11d of the insulating substrate 11 and the fourth through-hole 12d of the metal layer 12, respectively.

[0092] In the modified example shown in Figure 8, the heat generated in the semiconductor element 51 is carried to the outside by a coolant flowing through the recesses 26 of the two circuit layers 20. This allows for more efficient heat dissipation from the semiconductor element 51.

[0093] (Second variation) Figure 9 is a cross-sectional view showing an insulating circuit board 10 according to a second modified example.

[0094] As shown in Figure 9, a recess 16 is formed on the first surface 11a of the insulating substrate 11, and a recess 26 does not necessarily have to be formed in the circuit layer 20. Coolant from the cooling mechanism 60 flows through the recess 16 of the insulating substrate 11. The recess 16 is a non-penetrating portion formed by thinning the insulating substrate 11 partway along its thickness.

[0095] The recess 16 communicates with the first through-hole 11c and the second through-hole 11d, respectively. Coolant from the cooling mechanism 60 flows into the recess 16 sequentially through the third through-hole 12c and the first through-hole 11c of the metal layer 12. The coolant that has passed through the recess 16 returns to the cooling mechanism 60 side sequentially through the second through-hole 11d and the fourth through-hole 12d of the metal layer 12.

[0096] The depth d2 of the recess 16 may be 5% to 95% of the thickness t1 of the insulating substrate 11, or 30% to 60%. The depth d2 of the recess 16 refers to the distance between the first surface 11a and the deepest part of the recess 16.

[0097] The planar shape of the recess 16 may be the same as, for example, the planar shape of the recess 26 shown in Figures 2 to 4 above.

[0098] According to the modified example shown in Figure 9, since no recess 26 is formed in the circuit layer 20, the manufacturing process for the circuit layer 20 can be simplified.

[0099] (Third variation) Figure 10 is a cross-sectional view showing an insulating circuit board 10 according to a third modified example.

[0100] As shown in Figure 10, a recess 26 may be formed on the second surface 20b of the circuit layer 20, and a recess 16 may be formed on the first surface 11a of the insulating substrate 11. Coolant from the cooling mechanism 60 flows through the recess 26 of the circuit layer 20 and the recess 16 of the insulating substrate 11. The recess 26 of the circuit layer 20 and the recess 16 of the insulating substrate 11 together constitute a coolant flow path.

[0101] The recesses 16 and 26 communicate with the first through-hole 11c and the second through-hole 11d, respectively. Coolant from the cooling mechanism 60 flows into the recesses 16 and 26 sequentially through the third through-hole 12c and the first through-hole 11c of the metal layer 12. The coolant that has passed through the recess 16 returns to the cooling mechanism 60 side sequentially through the second through-hole 11d and the fourth through-hole 12d of the metal layer 12.

[0102] The total depth d3 of the recesses 16 and 26 may be 5% to 500% of the thickness t1 of the insulating substrate 11, or 30% to 200%. The total depth d3 of the recesses 16 and 26 refers to the distance between the deepest part of the recess 26 of the circuit layer 20 and the deepest part of the recess 16 of the insulating substrate 11.

[0103] The planar shape of the recess 26 of the circuit layer 20 may be the same as the planar shape of the recess 16 of the insulating substrate 11, or it may be different from the planar shape of the recess 16 of the insulating substrate 11. The planar shapes of the recesses 16 and 26 may be the same as, for example, the planar shapes of the recess 26 shown in Figures 2 to 4 above.

[0104] In the modified example shown in Figure 10, the recess 26 of the circuit layer 20 and the recess 16 of the insulating substrate 11 form a single channel, thus widening the refrigerant channel. This allows for more efficient heat dissipation from the semiconductor element 51.

[0105] (Fourth variation) In the embodiments described above, the case in which the circuit layer 20 and the metal layer 12 each contain a metal material such as copper was explained as an example. However, the invention is not limited to this, and the circuit layer 20 and the metal layer 12 may each contain a composite material (hereinafter also referred to as a composite metal material) that contains a metal.

[0106] As the composite metal material, for example, a composite material of copper and carbon may be used. The copper-carbon composite material is a sintered body obtained from flake graphite particles and copper particles as raw materials. The flake graphite particles are laminated with copper layers in between. Here, "with copper layers in between" means that the flake graphite particles are connected by adjacent copper layers. In other words, the flake graphite particles in the composite material are electrically continuous. The thickness of the copper layer in the composite material is not particularly limited, but it may be between 3 μm and 25 μm.

[0107] The circuit layer 20 and the metal layer 12 may both contain a composite metal material, or one of the circuit layer 20 and the metal layer 12 may contain a composite metal material.

[0108] Such composite metal materials have a higher thermal conductivity compared to copper. For example, the thermal conductivity of a composite metal material may be between 700 W / mK and 900 W / mK. Furthermore, composite metal materials have a thermal expansion coefficient similar to that of silicon, a power semiconductor material. The thermal expansion coefficient (CTE) of a composite metal material is, for example, 4.5 (×10⁻⁶). -6 / K) or more 5.5(×10 -6It may be less than or equal to / K. In this way, when the first circuit metal layer 21, the second circuit metal layer 22, and some layers of the metal layer 12 contain a composite metal material, the heat dissipation performance of the insulating circuit board 10 can be improved, and the reliability of the insulating circuit board 10 when it becomes hot can be increased.

[0109] (Second Embodiment) A second embodiment will be described with reference to Figures 11 and 12. The second embodiment shown in Figures 11 and 12 mainly differs in the configuration of the recesses of the circuit layer 20, while other configurations are substantially the same as those of the first embodiment described above. In Figures 11 and 12, the same reference numerals are used for parts that are the same as those in the first embodiment shown in Figures 1 to 10, and detailed descriptions are omitted.

[0110] (Configuration of an insulated circuit board) The schematic of the insulating circuit board according to this embodiment will be described with reference to Figure 11. Figure 11 is a cross-sectional view showing the insulating circuit board according to this embodiment.

[0111] As shown in Figure 11, the insulating circuit board 10 comprises an insulating substrate 11 and a circuit layer 20 disposed on the insulating substrate 11. A recess 22a is formed in the circuit layer 20. The recess 22a is located between the first surface 20a and the second surface 20b of the circuit layer 20. The circuit layer 20 has a first circuit metal layer 21 and a second circuit metal layer 22.

[0112] The first circuit metal layer 21 is laminated on the insulating substrate 11. The first circuit metal layer 21 may be composed of a metal such as copper, a copper alloy, or a 42 alloy (a Fe alloy with 42% Ni). The first circuit metal layer 21 has openings 21a and 21b. One opening 21a communicates with the first through hole 11c of the insulating substrate 11 and overlaps with the first through hole 11c in a plan view. The other opening 21b communicates with the second through hole 11d of the insulating substrate 11 and overlaps with the second through hole 11d in a plan view.

[0113] One opening 21a receives refrigerant from the cooling mechanism 60. This opening 21a may also be called an inlet or inlet hole. The other opening 21b receives refrigerant, which flows back to the cooling mechanism 60. This other opening 21b may also be called an outlet or outlet hole.

[0114] The second circuit metal layer 22 is bonded to the first circuit metal layer 21. The second circuit metal layer 22 is located on the opposite side of the insulating substrate 11 from the first circuit metal layer 21. The second circuit metal layer 22 may be composed of a metal such as copper, a copper alloy, or a 42 alloy (Fe alloy with 42% Ni). The second circuit metal layer 22 has a recess 22a. The recess 22a may also be called the circuit metal layer recess. Coolant from the cooling mechanism 60 flows through the recess 22a. The recess 22a is a non-penetrating portion formed by thinning the second circuit metal layer 22 partway along its thickness. The recess 22a is not exposed on either the first surface 20a or the second surface 20b of the circuit layer 20. The planar shape of the recess 22a may be the same as, for example, the planar shape of the recess 26 shown in Figures 2 to 4 above.

[0115] Furthermore, the configuration of the insulating circuit board 10 is the same as that shown in Figures 1 to 10 above, so a detailed explanation is omitted here.

[0116] (Method for manufacturing an insulating substrate) Next, the manufacturing method of the insulating circuit board 10 shown in Figure 11 will be explained using Figures 12(A)-(D). Figures 12(A)-(D) are cross-sectional views (corresponding to Figure 11) showing the manufacturing method of the insulating circuit board 10 according to this embodiment.

[0117] First, a second circuit metal layer 22 having a recess 22a is fabricated (Figure 12(A)). The second circuit metal layer 22 can be fabricated in substantially the same manner as the method for fabricating the circuit layer 20 shown in Figures 6(A)-(D).

[0118] Next, a laminate 10A is prepared in which a metal substrate 12A, an insulating material substrate 11A, and a substrate 21A for the first circuit metal layer are stacked in this order (Figure 12(B)). The metal substrate 12A corresponds to the metal layer 12, the insulating material substrate 11A corresponds to the insulating substrate 11, and the substrate 21A for the first circuit metal layer corresponds to the first circuit metal layer 21.

[0119] Next, the laminate 10A is subjected to cutting or etching. This forms a third through-hole 12c and a fourth through-hole 12d in the metal substrate 12A. In addition, a first through-hole 11c and a second through-hole 11d are formed in the insulating material substrate 11A. Furthermore, openings 21a and 21b are formed that penetrate the first circuit metal layer substrate 21A. Finally, the outer shape of the first circuit metal layer substrate 21A is formed (Figure 12(C)).

[0120] Subsequently, the insulating circuit board 10 shown in Figure 11 is obtained by bonding the second circuit metal layer 22 described above to the laminate 10A of the metal layer 12 obtained in this manner, the insulating substrate 11, and the first circuit metal layer 21 (Figure 12(D)). Specifically, the second circuit metal layer 22 is bonded to the first circuit metal layer 21 of the laminate 10A. The method of bonding the second circuit metal layer 22 to the laminate 10A is not limited. For example, an indirect bonding method using an adhesive such as activated metal brazing material may be used. Alternatively, a direct bonding method such as diffusion bonding may be used.

[0121] According to this embodiment, the recess 22a through which the refrigerant flows can be brought closer to the semiconductor element 51 in the thickness direction, thereby enabling more efficient heat dissipation from the semiconductor element 51.

[0122] It is also possible to combine the multiple components disclosed in each of the above embodiments and variations as needed. Alternatively, some components may be removed from all the components shown in each of the above embodiments and variations. [Explanation of symbols]

[0123] 10 Insulated circuit board 11 Insulating substrate 12 metal layer 20 circuit layers 26 recesses 50 Semiconductor Equipment 60 Cooling mechanism 70 Cooling System

Claims

1. In an insulating circuit board for semiconductor devices, Insulating substrate and The circuit layer is disposed on the insulating substrate, An insulating circuit board in which a recess is formed on the circuit layer and / or on the surface of the insulating substrate facing the circuit layer.

2. The insulating circuit board according to claim 1, wherein the insulating substrate has a through hole communicating with the recess.

3. The insulating circuit board according to claim 1, wherein a metal layer is laminated on the surface of the insulating substrate opposite to the circuit layer.

4. The insulating circuit board according to claim 3, wherein the metal layer has through holes communicating with the recesses.

5. The insulating circuit board according to claim 3, wherein the metal layer includes a composite metal material.

6. The insulating circuit board according to claim 1, wherein the recess is formed on the surface of the circuit layer facing the insulating substrate.

7. The insulating circuit board according to claim 1, wherein two circuit layers are arranged on the insulating substrate, and each of the two circuit layers has the recess.

8. The insulating circuit board according to claim 1, wherein the circuit layer includes a composite metal material.

9. The insulating circuit board according to claim 1, wherein the recess is located between the two surfaces of the circuit layer.

10. A semiconductor device including an insulating circuit board as described in claim 1, A cooling system comprising a cooling mechanism for introducing a refrigerant into the recess of the insulating circuit board.

11. In a method for manufacturing an insulating circuit board for semiconductor devices, The process of preparing the circuit layer, The process of preparing an insulating substrate, The process includes a step of bonding the circuit layer to the insulating substrate, A method for manufacturing an insulating circuit board, wherein a recess is formed on the circuit layer and / or on the circuit layer-side surface of the insulating substrate.

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