Insulated circuit board with heat sink

Abstract

The present invention provides an insulating circuit substrate with a heat sink, comprising: an insulating circuit substrate having a circuit layer bonded to one surface of a ceramic substrate and a metal layer composed of aluminum or an aluminum alloy bonded to the other surface of the ceramic substrate; and a heat sink bonded to the metal layer, wherein the heat sink has: a first metal layer bonded to the metal layer and composed of copper or a copper alloy, a ceramic plate material bonded to the surface of the first metal layer on the opposite side to the metal layer, and a second metal layer bonded to the surface of the ceramic plate material on the opposite side to the first metal layer and composed of copper or a copper alloy, wherein a thickness T1 of the first metal layer is greater than or equal to 0.3 mm and less than or equal to a thickness T2 of the second metal layer.

Description

Technical Field

[0001] The present invention relates to an insulating circuit substrate with a heat sink joined to a power module substrate or the like used in a semiconductor device for controlling a large current and a high voltage. This application claims priority based on Japanese Patent Application No. 2018-59658 filed on March 27, 2018, and the contents thereof are incorporated herein by reference. Background Art

[0002] There is known an insulating circuit substrate with a heat sink in which a circuit layer is bonded to one surface of an insulating layer composed of a ceramic substrate represented by aluminum nitride, and an aluminum-based heat sink is bonded to the other surface via an aluminum plate.

[0003] For example, the insulating circuit substrate with a heat sink disclosed in Patent Document 1 has a circuit layer composed of any one of a pure aluminum plate, an aluminum alloy plate, a pure copper plate, and a copper alloy plate bonded to one surface of an insulating layer composed of a ceramic substrate, a metal layer composed of a metal plate of pure aluminum or an aluminum alloy bonded to the other surface of the insulating layer, and a heat sink composed of aluminum or an aluminum alloy bonded to the metal layer via a copper layer. In this case, the insulating layer and the metal layer are bonded using a solder, and the metal layer and the heat sink are solid-phase diffusion bonded to the copper layer existing therebetween.

[0004] In such an insulating circuit substrate with a heat sink, warping may occur due to the bonding of components having different thermal expansion coefficients, such as a ceramic substrate and an aluminum plate. In order to prevent such warping, a composite body with a low thermal expansion coefficient, which is formed by impregnating a porous silicon carbide molded body disclosed in Patent Document 2 with a metal having aluminum as a main component, may be used as the material of the heat sink.

[0005] Patent document 3 discloses a metal-ceramic bonded substrate (insulated circuit substrate with heat sink) formed by bonding a first metal plate to one surface of a first ceramic substrate, bonding a second metal plate to the other surface of the first ceramic substrate and one surface of a second ceramic substrate, and bonding a plate-shaped heat dissipation component having a plurality of heat sinks to the other surface of the second ceramic substrate. The metal-ceramic bonded substrate is formed by arranging the first ceramic substrate and the second ceramic substrate at intervals in a carbon casting mold, allowing aluminum alloy molten metal to flow into the casting mold, cool, and solidify.

[0006] Patent Document 1: Japanese Patent Application Publication No. 2014-60215

[0007] Patent Document 2: Japanese Patent Application Publication No. 2000-281465

[0008] Patent Document 3: Japanese Patent Application Publication No. 2017-212316

[0009] The metal-ceramic bonded substrate disclosed in Patent Document 3 is manufactured by arranging two ceramic substrates at a distance in a mold and pouring molten aluminum alloy into the mold, so that all metal plates, heat dissipating components, and heat sinks are made of the same aluminum alloy. Summary of the invention

[0010] The present invention has been made in view of such circumstances, and an object of the present invention is to suppress warping of an insulating circuit board with a heat sink formed by bonding a heat sink made of a metal having a composition different from that of a metal layer of an insulating circuit board.

[0011] The insulating circuit substrate with a heat sink of the present invention comprises: an insulating circuit substrate having a ceramic substrate, a circuit layer bonded to one surface of the ceramic substrate, and a metal layer bonded to the other surface of the ceramic substrate and composed of aluminum or an aluminum alloy; and a heat sink bonded to the metal layer, wherein the heat sink comprises: a first metal layer bonded to the metal layer and composed of copper or a copper alloy and having a thickness of T1, a ceramic plate material bonded to the surface of the first metal layer on the side opposite to the metal layer, and a second metal layer bonded to the surface of the ceramic plate material on the side opposite to the first metal layer and composed of copper or a copper alloy and having a thickness of T2, wherein the thickness T1 of the first metal layer is greater than or equal to 0.3 mm and less than or equal to 3.0 mm, and a thickness ratio T1 / T2 is greater than or equal to 1.0.

[0012] In the present invention, the heat sink is composed of a first metal layer bonded to the metal layer of the insulating circuit substrate, a ceramic plate bonded to the first metal layer, and a second metal layer bonded to the ceramic plate. That is, the ceramic plate is built inside the first metal layer and the second metal layer composed of copper or copper alloy, so that the linear expansion coefficient of the heat sink can be reduced, and the linear expansion difference with the insulating circuit substrate can also be reduced. As a result, the warpage change of the insulating circuit substrate with the heat sink at high temperature and low temperature can be suppressed.

[0013] Furthermore, the thickness T1 of the first metal layer is set to be greater than 0.3 mm and less than 3.0 mm because if the thickness T1 of the first metal layer is less than 0.3 mm, the heat dissipation effect of the heat sink may be reduced, and if the thickness T1 exceeds 3.0 mm, the influence of the expansion of the first metal layer composed of copper or copper alloy becomes greater, and the linear expansion of the joint body (heat sink) of the first metal layer and the ceramic plate increases, so the warping of the joint body of the insulating circuit substrate and the heat sink, that is, the insulating circuit substrate with the heat sink increases. Furthermore, if the thickness T1 of the first metal layer is less than the thickness T2 of the second metal layer, when the insulating circuit substrate with the heat sink is heated, it is possible to warp in a convex shape toward the insulating circuit side, so T1 / T2 is set to be greater than 1.0.

[0014] As a preferred embodiment of the insulating circuit board with a heat sink of the present invention, the thickness ratio T1 / T2 is preferably 10.0 or less.

[0015] As a preferred embodiment of the insulating circuit board with a heat sink of the present invention, the thickness T2 of the second metal layer is preferably 0.3 mm or more.

[0016] As a preferred embodiment of the insulating circuit substrate with a heat sink of the present invention, it is preferred that the circuit layer is made of aluminum or an aluminum alloy, the ceramic substrate is made of aluminum nitride, and the ceramic plate is made of silicon nitride.

[0017] As a preferred embodiment of the insulating circuit board with a heat sink of the present invention, it is preferred that the metal layer and the first metal layer are solid phase diffusion bonded.

[0018] According to the present invention, warping of an insulating circuit board with a heat sink formed by bonding an insulating circuit board having a metal layer and a heat sink having a metal layer having a composition different from that of the metal layer of the insulating circuit board can be suppressed. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 1 is a cross-sectional view showing a power module using an insulating circuit substrate with a heat sink according to an embodiment of the present invention.

[0020] Figure 2 1 is a plan view showing the insulating circuit substrate with a heat sink in the above-mentioned embodiment when viewed from the circuit layer side.

[0021] Figure 3A For explanation Figure 1 A cross-sectional view of a method for manufacturing an insulating circuit substrate with a heat sink is shown.

[0022] Figure 3B For illustration Figure 1 A cross-sectional view of a method for manufacturing an insulating circuit substrate with a heat sink is shown.

[0023] Figure 3C For illustration Figure 1 A cross-sectional view of a method for manufacturing an insulating circuit substrate with a heat sink is shown. DETAILED DESCRIPTION

[0024] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0025] [Schematic Structure of Insulating Circuit Board]

[0026] like Figure 1 As shown in FIG. 1 , the insulating circuit substrate 100 with a heat sink according to the present invention is formed by bonding a heat sink 2 to an insulating circuit substrate 1 and is used, for example, as a substrate for a power module. Figure 1As shown by the two-dot chain line, the element 30 is mounted on the surface (upper surface) of the insulating circuit substrate 100 with a heat sink to form a power module.

[0027] The element 30 is an electronic component having a semiconductor, and various semiconductor elements such as IGBT (Insulated Gate Bipolar Transistor), MOSFET (Metal Oxide Semiconductor Field Effect Transistor), and FWD (Free Wheeling Diode) can be selected. At this time, although not shown in the figure, an upper electrode portion is provided on the upper part of the element 30, and a lower electrode portion is provided on the lower part. The lower electrode portion is joined to the upper surface of the circuit layer 12 by solder 31, etc., so that the element 30 is mounted on the upper surface of the circuit layer 12. In addition, the upper electrode portion of the element 30 is connected to the circuit electrode portion of the circuit layer 12 via a lead frame etc. joined by solder etc. to manufacture a power module.

[0028] [Structure of insulating circuit substrate]

[0029] The insulating circuit substrate 1 includes a ceramic substrate 11 , a circuit layer 12 bonded to one surface of the ceramic substrate 11 , and a metal layer 13 bonded to the other surface of the ceramic substrate 11 .

[0030] The ceramic substrate 11 is a rectangular plate-shaped insulating substrate that prevents electrical connection between the circuit layer 12 and the metal layer 13, and is formed, for example, by aluminum nitride (AlN), silicon nitride (Si3N4), aluminum oxide (Al2O3), zirconium oxide toughened aluminum oxide substrate, etc., and has a thickness of 0.2 mm to 1.2 mm. In addition, when the circuit layer 12 and the metal layer 13 bonded to both sides of the ceramic substrate 11 are both composed of aluminum or aluminum alloy, the ceramic substrate 11 is preferably composed of aluminum nitride.

[0031] In addition, the plane size of the ceramic substrate 11 is not particularly limited, but is set to 40 mm to 140 mm×40 mm to 100 mm in the present embodiment.

[0032] The circuit layer 12 is bonded to the upper surface (surface) of the ceramic substrate 11 and is made of pure aluminum or aluminum alloy having a purity of 99 mass % or more and has a thickness of, for example, 0.2 mm to 0.9 mm.

[0033] Furthermore, the planar size of the circuit layer 12 is smaller than the planar size of the ceramic substrate 11 , and although not particularly limited, is set to 36 mm to 136 mm×36 mm to 96 mm in the present embodiment.

[0034] The metal layer 13 is bonded to the bottom (back) of the ceramic substrate 11 and is made of pure aluminum or aluminum alloy with a purity of 99 mass % or more. According to the JIS standard, 1000 series aluminum can be used, and 1N99 (purity of 99.99 mass % or more: so-called 4N aluminum) can be used in particular. Its thickness is, for example, 0.2 mm to 0.9 mm.

[0035] Furthermore, the plane size of the metal layer 13 is smaller than the plane size of the ceramic substrate 11, and although not particularly limited, in this embodiment, it is set to 36 mm to 136 mm × 36 mm to 96 mm, similarly to the circuit layer 12. In addition, the circuit layer 12 and the metal layer 13 preferably have the same composition, thickness, and size.

[0036] [Structure of radiator]

[0037] The heat sink 2 is bonded to the insulating circuit substrate 1 to dissipate heat transferred from the insulating circuit substrate 1. The heat sink 2 includes a first metal layer 21 bonded to the metal layer 13 of the insulating circuit substrate 1, a ceramic plate 23 bonded to the lower surface (back surface) of the first metal layer 21, and a second metal layer 22 bonded to the lower surface (back surface) of the ceramic plate 23.

[0038] The first metal layer 21 is made of copper or a copper alloy, and its thickness T1 is set to be 0.3 mm or more and 3.0 mm or less. The second metal layer 22 is made of copper or a copper alloy, and its thickness T2 is set to be 0.3 mm or more and 3.0 mm or less.

[0039] In addition, if the thickness of the first metal layer 21 is less than 0.3 mm, the heat dissipation effect of the heat sink 2 may be reduced, and if it exceeds 3.0 mm, the linear expansion of the bonded body (heat sink 2) of the first metal layer 21 and the ceramic plate 23 increases, so that the bonded body of the insulating circuit substrate 1 and the heat sink 2, that is, the insulating circuit substrate 100 with a heat sink, increases in warpage. In addition, if the thickness of the first metal layer 21 is smaller than that of the second metal layer 22, the heat sink 2 may be warped in a convex shape toward the first metal layer 21 side when heated. Therefore, the thickness T1 of the first metal layer 21 is set to be greater than 0.3 mm and less than 3.0 mm, and is set to be greater than the thickness T2 of the second metal layer 22 (equal to or thicker than the thickness T2 of the second metal layer 22).

[0040] Furthermore, a thickness ratio T1 / T2 of the thickness T1 of the first metal layer 21 to the thickness T2 of the second metal layer 22 is preferably greater than or equal to 1.0 and less than or equal to 10.0.

[0041] The ceramic plate 23 is provided to reduce the linear expansion difference between the heat sink 2 and the insulating circuit substrate 1, and is formed of silicon nitride (Si3N4), aluminum nitride (AlN), aluminum oxide (Al2O3), zirconium oxide toughened aluminum substrate, etc., and its thickness T3 is set to 0.2mm~1.2mm.

[0042] Furthermore, the planar size of the first metal layer 21, the second metal layer 22, and the ceramic plate 23 is larger than the planar size of the ceramic substrate 11. Although not particularly limited, they are all set to the same size, for example, 50 mm to 180 mm × 60 mm to 140 mm. In addition, the ceramic plate 23 is preferably made of silicon nitride because the first metal layer 21 and the second metal layer 22 made of copper or a copper alloy are bonded to both surfaces thereof.

[0043] When the insulating circuit substrate 100 with a heat sink is observed from the circuit layer 12 side, Figure 2 As shown, the ceramic substrate 11 is larger than the circuit layer 12 , and the heat sink 2 (the first metal layer 21 , the second metal layer 22 and the ceramic plate 23 ) is larger than the ceramic substrate 11 .

[0044] As described above, the heat sink 2 has a structure in which the ceramic plate 23 is built inside the first metal layer 21 and the second metal layer 22 made of copper or a copper alloy.

[0045] [Method for manufacturing an insulating circuit substrate with a heat sink]

[0046] Next, a method for manufacturing the insulating circuit substrate 100 with a heat sink according to the present embodiment will be described.

[0047] Regarding the manufacturing method of the insulating circuit substrate 100 with a heat sink, Figures 3A to 3C As shown, the insulating circuit substrate manufacturing process comprises: bonding a circuit layer metal plate 120 and a metal layer metal plate 130 made of pure aluminum or aluminum alloy to a ceramic substrate 11 ( Figure 3A ), a heat sink manufacturing process of joining a first metal layer metal plate 210 and a second metal layer metal plate 220 made of copper or a copper alloy to a ceramic plate 23 ( Figure 3B ) and a step of bonding the insulating circuit substrate 1 and the heat sink 2 ( Figure 3C ). The following is an explanation in order of the steps.

[0048] (Insulating Circuit Board Manufacturing Process)

[0049] First, if Figure 3AAs shown, the metal plate 120 for the circuit layer and the metal plate 130 for the metal layer are bonded to the ceramic substrate 11 using Al-Si brazing filler metal. Specifically, the metal plate 120 for the circuit layer and the metal plate 130 for the metal layer are stacked on the surface (upper surface) and the back surface (lower surface) of the ceramic substrate 11 via the Al-Si brazing filler metal foil 14, and these stacked bodies are clamped by carbon plates, and heated in a vacuum while applying a load in the stacking direction, thereby bonding the ceramic substrate 11, the metal plate 120 for the circuit layer, and the metal plate 130 for the metal layer. Thus, an insulating circuit substrate 1 is formed in which the circuit layer 12 is bonded to the surface (upper surface) of the ceramic substrate 11 via a bonding portion (brazing portion), and the metal layer 13 is bonded to the back surface (lower surface) via a bonding portion (brazing portion).

[0050] In addition, it is preferred that the pressure applied in the stacking direction is set to 0.3 MPa to 1.5 MPa, and the heating temperature is set to 630°C to 655°C. Furthermore, the thickness of the Al-Si brazing filler metal foil is preferably 5 μm to 15 μm. In addition to the Al-Si brazing filler metal, Al-Ge, Al-Cu, Al-Mg, Al-Mn or Al-Si-Mg brazing filler metals can also be used.

[0051] (Heat Radiator Manufacturing Process)

[0052] Then, if Figure 3B As shown, a first metal layer metal plate 210 having a thickness T1 of 0.3 mm to 3.0 mm and a second metal layer metal plate 220 having a thickness T2 of 0.3 mm to 3.0 mm and less than T1 are bonded to a ceramic plate material 23 having a thickness T3 of 0.2 mm to 1.2 mm, respectively, using Ag-Cu-Ti based brazing filler metal. Specifically, the first metal layer metal plate 210 and the second metal layer metal plate 220 are stacked on the surface (upper surface) and the back surface (lower surface) of the ceramic substrate 23, respectively, with Ag-Cu-Ti based brazing filler metal foil 14 interposed therebetween, and these stacked bodies are sandwiched by carbon plates, and heated in a vacuum while a load is applied in the stacking direction, thereby bonding the ceramic substrate 23 to the first metal layer metal plate 210 and the second metal layer metal plate 220. Thus, a heat sink 2 is formed, in which a first metal layer 21 having a thickness T1 of 0.3 mm to 3.0 mm is joined to the surface (upper side) of a ceramic plate 23 via a joining portion (welding portion), and a second metal layer 22 having a thickness T2 of 0.3 mm to 3.0 mm and less than the thickness T1 of the first metal layer 21 is joined to the back side (lower side) via a joining portion (welding portion).

[0053] Furthermore, the pressure applied in the stacking direction is preferably set to 0.1 MPa to 1.0 MPa, and the heating temperature is preferably set to 800° C. to 930° C. Furthermore, the thickness of the Ag-Cu-Ti brazing material foil is preferably 5 μm to 15 μm. In addition to the Ag-Cu-Ti brazing material, a Cu-P brazing material can also be used.

[0054] (Joining process)

[0055] Next, the insulating circuit substrate 1 and the heat sink 2 are solid phase diffusion bonded. Figure 3C As shown, the metal layer 13 of the insulating circuit substrate 1 is stacked on the heat sink 2, and the stacked bodies are heated to the bonding temperature in a vacuum atmosphere while being pressurized in the stacking direction, thereby solid-phase diffusion bonding of the metal layer 13 and the heat sink 2. The pressure at this time is set to 0.5MPa to 2.0MPa, and the heating temperature is set to 500°C to 540°C, and the pressurization and heating state is maintained for 30 minutes to 120 minutes. In this way, the metal layer 13 and the heat sink 2 are bonded, as shown in FIG. Figure 1 As shown, an insulating circuit substrate 100 with a heat sink is obtained.

[0056] In the present embodiment, the bonding surface of the metal layer 13 and the bonding surface of the heat sink 2 are smoothed by removing scratches in advance and then solid phase diffusion bonding is performed.

[0057] Among them, when the heat sink is composed of a copper or copper alloy plate, the linear expansion difference between the metal layer 13 composed of aluminum or aluminum alloy of the insulating circuit substrate 1 is large. Therefore, the expansion rate at high temperature and the contraction rate at low temperature are different, and the warping of the insulating circuit substrate 100 with the heat sink is large.

[0058] In contrast, in the present embodiment, the heat sink 2 is composed of the first metal layer 21 bonded to the metal layer 13 of the insulating circuit substrate 1, the ceramic plate 23 bonded to the first metal layer 21, and the second metal layer 22 bonded to the ceramic plate 23. That is, the ceramic plate 23 is built inside the first metal layer 21 and the second metal layer 22 made of copper or a copper alloy, so that the linear expansion coefficient of the heat sink 2 can be reduced, and the linear expansion difference with the insulating circuit substrate 1 can be reduced.

[0059] Furthermore, the thickness T1 of the first metal layer 21 is greater than or equal to 0.3 mm and less than or equal to 3.0 mm, and is greater than or equal to the thickness T2 of the second metal layer 22 (T1 ≥ T2). Therefore, while maintaining the heat dissipation effect of the heat sink 2, the warping of the heat sink 2 can be suppressed, and the warping change of the insulating circuit substrate 100 with the heat sink at high temperature and low temperature can be further suppressed.

[0060] In addition, the detailed structure is not limited to the structure of the embodiment, and various changes can be added without departing from the scope of the present invention.

[0061] For example, in the above embodiment, the circuit layer 12 is made of aluminum or an aluminum alloy, but the present invention is not limited thereto, and the circuit layer 12 may be made of oxygen-free copper, for example. That is, the composition of the circuit layer 12 is not limited.

[0062] Furthermore, in the above-described embodiment, an example is described in which the insulating circuit substrate 100 with a heat sink is used as a substrate for a power module with a heat sink. However, the insulating circuit substrate 100 with a heat sink can also be used as various insulating substrates such as a substrate for an LED element.

[0063] Example

[0064] Next, the effects of the present invention will be described in detail using examples, but the present invention is not limited to the following examples.

[0065] As insulating circuit substrates constituting samples of Examples 1 to 18, Comparative Examples 1 to 3 and prior art examples, a circuit layer with a thickness of 0.4 mm and a metal layer with a thickness of 0.4 mm were manufactured on a ceramic substrate with a thickness of 0.635 mm and a plane size of 120 mm × 90 mm by the method described in the above embodiment, and circuit layers and metal layers with the compositions shown in Table 1 were prepared.

[0066] Furthermore, as the heat sinks constituting the samples of Examples 1 to 18 and Comparative Examples 1 to 3, the first metal layer and the second metal layer composed of oxygen-free copper were manufactured by the manufacturing method described in the above embodiment on a ceramic plate having a thickness of 0.32 mm and a plane size of 140 mm×100 mm. The first metal layer and the second metal layer were prepared with the thickness shown in Table 1. In addition, as for the conventional example, a heat sink composed of a single oxygen-free copper plate having a thickness of 5.0 mm and a plane size of 140 mm×100 mm was manufactured.

[0067] Then, the insulating circuit substrates and the heat sink were bonded together using the bonding method described in the above embodiment, and the following experiments were conducted on the obtained samples (Examples 1 to 18, Comparative Examples 1 to 3, and Conventional Example).

[0068] (Warp change)

[0069] For each sample obtained, in a series of heating tests in which the sample was heated from 30°C to 285°C and then cooled to 30°C, the warping amount when heated to 285°C and the warping amount when heated to 285°C and then cooled to 30°C (the warping amount when cooled to 30°C) were measured respectively. The deformation of each sample caused by the temperature change was confirmed as the warping change amount.

[0070] The warpage was measured using a moire-type three-dimensional shape measuring machine (Akrometrix thermal warpage and deformation measuring machine Thermoire PS200) with the center of the second metal layer of the heat sink (100 mm × 80 mm range) as the measuring surface. More specifically, the minimum plane was obtained from the distribution of the measuring surface, and the difference (absolute value) between the highest point and the lowest point was obtained based on the plane to obtain the warpage.

[0071] The warpage amount thus obtained is set to positive or negative according to the warpage state. That is, a positive value is set when the center of the measurement range is closer to the circuit layer side than the plane formed by the four corners of the measurement range (the second metal layer protrudes toward the circuit layer side) and when the center of the measurement range is on the plane formed by the four corners of the measurement range, and a negative value is set when the center of the measurement range is further away from the circuit layer side than the plane formed by the four corners of the measurement range (the second metal layer protrudes toward the heat sink side).

[0072] The absolute value of the difference between the warping amount when the positive and negative heating is set to 285°C and the warping amount when the positive and negative cooling is set to 30°C (the warping amount when the positive and negative heating is set to 285°C - the warping amount when the positive and negative cooling is set to 30°C) is defined as the warping change amount.

[0073] (Evaluation of component position deviation)

[0074] Regarding the evaluation of component position deviation, the soldering position of the electronic component was measured after soldering it to the circuit layer, and 30 samples were made to confirm whether position deviation occurred. Then, the situation where the position deviation of more than 0.2mm occurred was regarded as unqualified, and the situation where the position deviation of less than 0.2mm occurred was regarded as qualified.

[0075] Then, in each evaluation performed on 30 samples, the condition in which the pass rate was 90% or more was evaluated as good "A", and the condition in which the pass rate was less than 90% was evaluated as bad "B".

[0076] (Evaluation of thermal cycle reliability)

[0077] Furthermore, the insulating circuit substrate with a heat sink of Examples 1 to 18, Comparative Examples 1 to 3, and the prior art example was subjected to a temperature cycle test in which the temperature was changed between -50°C and 175°C for 1,000 times, and then it was visually determined whether the ceramic substrate of the insulating circuit substrate had cracks. At this time, the ceramic substrate with cracks was determined as a poor "B", and the ceramic substrate without cracks was determined as a good "A". The results of the evaluation of the warpage change, the component position deviation, and the evaluation of the thermal cycle reliability are shown in Table 2.

[0078] [Table 1]

[0079]

[0080] [Table 2]

[0081] Warpage difference(mm) Component position deviation Hot and cold cycle reliability Example 1 0.29 A A Example 2 0.32 A A Example 3 0.54 A A Example 4 0.77 A A Example 5 1.10 A A Example 6 0.19 A A Example 7 0.89 A A Example 8 1.20 A A Example 9 0.35 A A Example 10 0.39 A A Embodiment 11 0.41 A A Example 12 0.35 A A Example 13 0.37 A A Embodiment 14 0.36 A A Embodiment 15 0.36 A A Example 16 0.33 A A Embodiment 17 0.42 A A Embodiment 18 0.46 A A Comparative Example 1 1.23 A B Comparative Example 2 1.28 A B Comparative Example 3 1.35 B A Existing examples 1.30 B B

[0082] As can be seen from Table 2, in Examples 1 to 18, the warpage change is less than 1.20 mm, and the evaluations of component position deviation and thermal cycle reliability are all good "A". Therefore, it can be seen that the following effective range is: the thickness T1 of the first metal layer of the heat sink is greater than 0.3 mm and less than 3.0 mm, and the thickness of the second metal layer is greater than T2 (T1 ≥ T2).

[0083] On the other hand, in Comparative Examples 1 and 2, although the warpage change amount was relatively large, the evaluation of component position deviation was good "A", but the result of the hot and cold cycle test was evaluated as bad "B" due to the cracking of the ceramic substrate. Therefore, it can be seen that when the thickness of the first metal layer is 4.0 mm, effective results cannot be obtained. And in Comparative Example 3, although the hot and cold cycle reliability was evaluated as good "A", the warpage change amount was more than 1.3 mm, which was large, and component position deviation occurred, so it was evaluated as bad "B". Therefore, it can be seen that when the thickness T2 of the second metal layer is greater than the thickness T1 of the first metal layer, effective results cannot be obtained.

[0084] Industrial Applicability

[0085] The warping of the insulating circuit board with a heat sink formed by bonding an insulating circuit board having a metal layer and a heat sink having a metal layer having a composition different from that of the metal layer of the insulating circuit board can be suppressed.

[0086] Explanation of symbols

[0087] 1 Insulated circuit board

[0088] 2 Radiator

[0089] 11 Ceramic Substrate

[0090] 12 Circuit layer

[0091] 13 Metal Layer

[0092] 14 solder foil

[0093] 21 1st metal layer

[0094] 22 2nd Metal Layer

[0095] 23 Ceramic Plate

[0096] 30 Elements

[0097] 31 Solder

[0098] 100 Insulated circuit board with heat sink

[0099] 120 Metal plate for circuit layer

[0100] 130 Metal plate for metal layer

[0101] 210 Metal plate for the first metal layer

[0102] 220 Metal plate for the second metal layer

Claims

1. An insulating circuit substrate with a heat sink, comprising: an insulating circuit substrate having a ceramic substrate, a circuit layer bonded to one surface of the ceramic substrate, and a metal layer bonded to the other surface of the ceramic substrate and composed of aluminum or an aluminum alloy; and a heat sink bonded to the metal layer, wherein the insulating circuit substrate with a heat sink is characterized in that: The heat sink comprises: a first metal layer which is bonded to the metal layer and is made of copper or a copper alloy and has a thickness of T1, a ceramic plate which is bonded to a surface of the first metal layer opposite to the metal layer, and a second metal layer which is bonded to a surface of the ceramic plate opposite to the first metal layer and is made of copper or a copper alloy and has a thickness of T2, The thickness T1 of the first metal layer is greater than or equal to 0.3 mm and less than or equal to 3.0 mm, and the thickness ratio T1 / T2 is greater than or equal to 1.

0. The plane size of the ceramic plate in the heat sink is larger than the plane size of the ceramic substrate in the insulating circuit substrate. When the absolute value of the difference between the warpage amount when heating with positive and negative values ​​set at 285° C. and the warpage amount when cooling with positive and negative values ​​set at 30° C. is defined as the warpage change amount, the warpage change amount is 1.20 mm or less.

2. The insulating circuit substrate with a heat sink according to claim 1, characterized in that: The thickness ratio T1 / T2 is 10.0 or less.

3. The insulating circuit substrate with a heat sink according to claim 1 or 2, characterized in that: The thickness T2 of the second metal layer is greater than or equal to 0.3 mm.

4. The insulating circuit substrate with a heat sink according to claim 1 or 2, characterized in that: The circuit layer is made of aluminum or aluminum alloy. The ceramic substrate is made of aluminum nitride. The ceramic plate is made of silicon nitride.

5. The insulating circuit substrate with a heat sink according to any one of claims 1 to 3, characterized in that: The metal layer is solid phase diffusion bonded to the first metal layer.

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