Joined body, joined sheet, and method for manufacturing joined body

Abstract

To provide a joined body which can suppress cracking and deformation in a joined sheet, even when stress is applied to the joined sheet by an expansion coefficient difference between members due to temperature change, and a method for manufacturing the same.SOLUTION: In a joined body, each of an upper metal-containing member 2 and a lower metal-containing member 3 has a metal part 21 on a joined surface to a joined sheet 1, the joined sheet 1 is a cured product of a thermosetting resin composition containing a thermosetting resin and an inorganic filler 11, the whole upper surface of the joined sheet 1 is joined to the upper metal-containing member 2, the whole lower surface of the joined sheet 1 is joined to a lower metal-containing member 3, when the joined sheet 1 is viewed in a cross section, and a resin area ratio in an end region 1A at 300 μm inside from right and left one side ends of the joined sheet 1 is represented by P1A, and a resin area ratio in a central region 1B other than the end region 1A is represented by P1B, a value of P1A / P1B is larger than 1.10.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a bonded body having a structure in which an upper metal-containing member and a lower metal-containing member are bonded to the front and back of a bonding sheet, such as a power semiconductor device, a bonding sheet used therefor, and a method for manufacturing the bonded body.

Background Art

[0002] Among devices using semiconductors, devices that control and convert electric power such as power supplies are called "power semiconductor devices". A power semiconductor device on which electronic components are mounted has electronic components such as semiconductor elements arranged on the central upper surface of a metal base plate (heat sink) via an insulating substrate, and a heat dissipation member such as a metal member is further arranged on the electrical components, and these electronic components and heat dissipation members are sealed with a synthetic resin so as to surround them (see Patent Documents 1 to 4).

[0003] As such an insulating substrate, conventionally, a ceramic substrate having high thermal conductivity such as an alumina substrate or an aluminum nitride substrate has been used because it can achieve both thermal conductivity and insulation. However, the ceramic substrate has problems such as being easily cracked by impact, being difficult to thin, and being difficult to miniaturize. Therefore, a sheet having thermal conductivity using a thermosetting resin such as an epoxy resin and an inorganic filler has been proposed as an insulating substrate or the like.

[0004] Regarding a sheet using a thermosetting resin and an inorganic filler, for example, in Patent Document 5, a sealing resin sheet containing alumina particles and boron nitride together with a thermosetting resin and a thermoplastic resin, and having a thermal conductivity in the sheet thickness direction after thermosetting of 3 W / m·K or more is disclosed. Further, in Patent Document 6, a heat dissipation resin sheet containing an epoxy resin having a Tg of 60°C or lower and boron nitride, and having a boron nitride content of 30% by volume or more and 60% by volume or less has been proposed.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Patent Document 6

Summary of the Invention

Problems to be Solved by the Invention

[0006] As shown in FIG. 1, in a joined body having a structure in which an upper metal-containing member 2 and a lower metal-containing member 3 are joined to the front and back of a joining sheet 1 (corresponding to the insulating substrate), when stress is applied to the joining sheet 1 due to a difference in the expansion rate between members due to temperature change or the like, it has been found that pressure locally concentrates at the end of the joining sheet 1 and cracks and deformation occur in the joining sheet 1.

[0007] Therefore, an object of the present invention is to provide a new joined body, a joining sheet used therefor, and a method for manufacturing the joined body, which relate to a joined body having a structure in which an upper metal-containing member 2 and a lower metal-containing member 3 are joined to the front and back of a joining sheet 1, and can suppress cracks and deformation in the joining sheet 1 even when stress is applied to the joining sheet 1 due to a difference in the expansion rate between members due to temperature change or the like.

Means for Solving the Problems

[0008] The joined body proposed by the present invention, the joining sheet used therefor, and the method for manufacturing the joined body have the following configurations in order to solve the above problems.

[0009] [1] The first aspect of the present invention is a joined body having a structure in which an upper metal-containing member 2 and a lower metal-containing member 3 are joined to the front and back of a joining sheet 1, The upper metal-containing member 2 and the lower metal-containing member 3 each have a metal part on the joint surface with the joining sheet 1, The joining sheet 1 is a cured product of a thermosetting resin composition containing a thermosetting resin and an inorganic filler, The entire upper surface of the joining sheet 1 is joined to the upper metal-containing member 2, and the entire lower surface of the joining sheet 1 is joined to the lower metal-containing member 3. When the joining sheet 1 is viewed in cross section, the resin area ratio in the end region 1A from the left or right one-side end of the joining sheet 1 to the inside by 300 μm is P 1A , and the resin area ratio in the central region 1B other than the end region 1A is P 1B When it is set as, P 1A / P 1B The joined body is characterized in that the value of is greater than 1.10.

[0010] [2] The second aspect of the present invention is a joined body having a structure in which an upper metal-containing member 2 and a lower metal-containing member 3 are joined to the front and back of a joining sheet 1, The upper metal-containing member 2 and the lower metal-containing member 3 each have a metal part on the joint surface with the joining sheet 1, The joining sheet 1 is a cured product of a thermosetting resin composition containing a thermosetting resin and an inorganic filler, The entire upper surface of the joining sheet 1 is joined to the upper metal-containing member 2, and the entire lower surface of the joining sheet 1 is joined to the lower metal-containing member 3. When the joining sheet 1 is viewed in cross section, the void area ratio in the end region 1A from the left or right one-side end of the joining sheet 1 to the inside by 300 μm is S 1A , and the void area ratio in the central region 1B other than the end region 1A is S 1B When it is set as, S 1A / S 1B The joined body is characterized in that the value of is greater than 1.

[0011] [3] The third aspect of the present invention is a joined body having a structure in which an upper metal-containing member 2 and a lower metal-containing member 3 are joined to the front and back surfaces of a joining sheet 1, The upper metal-containing member 2 and the lower metal-containing member 3 each have a metal part on the joint surface with the joining sheet 1, The joining sheet 1 is a cured product of a thermosetting resin composition containing a thermosetting resin and an inorganic filler, The entire upper surface of the joining sheet 1 is joined to the upper metal-containing member 2, and the entire lower surface of the joining sheet 1 is joined to the lower metal-containing member 3. When the joining sheet 1 is viewed in cross-section, the average void size in the end region 1A from the left or right one-side end of the joining sheet 1 to the inner side by 300 μm is L 1A , and the average void size in the central region 1B other than the end region 1A is L 1B When it is set as, L 1A / L 1B The joined body is characterized in that the value of is greater than 2.

[0012] [4] The fourth aspect of the present invention is a joined body having a structure in which, in any one of the first to third aspects, the joining sheet 1 and the upper metal-containing member 2 are directly joined, and the joining sheet 1 and the lower metal-containing member 3 are directly joined. [5] The fifth aspect of the present invention is a joined body having a structure in which, in any one of the first to fourth aspects, the upper metal-containing member 2 has a structure in which the lower surface of the sheet or plate-like metal part 21 is exposed on the joint surface with the joining sheet 1, and the metal part 21 is covered and sealed with the resin 22. [6] The sixth aspect of the present invention is a joined body having a structure in which, in any one of the first to fifth aspects, the lower metal-containing member 3 has a flat plate-like or sheet-like metal body on the joint surface with the joining sheet 1.

[0013] [7] The seventh aspect of the present invention is a joined body characterized in that, in any one of the first to sixth aspects, the thermal conductivity in the thickness direction of the joining sheet 1 is 10 W / m·K or more. [8] The eighth aspect of the present invention is a bonded body characterized in that, in any one of the first to seventh aspects, the dielectric breakdown voltage of the bonding sheet 1 is 5 kV or more.

[0014] [9] The ninth aspect of the present invention is a bonded body characterized in that, in any one of the first to eighth aspects, the metal parts provided in the upper metal-containing member 2 and the lower metal-containing member 3 are made of a material containing copper or aluminum.

[10] The tenth aspect of the present invention is a bonded body characterized in that, in any one of the first to ninth aspects, the inorganic filler contained in the bonding sheet 1 includes boron nitride aggregated particles.

[11] The eleventh aspect of the present invention is a bonded body characterized in that, in the tenth aspect, the boron nitride aggregated particles have a card house structure.

[12] The twelfth aspect of the present invention is a bonded body characterized in that, in any one of the first to eleventh aspects, the thermosetting resin contained in the bonding sheet 1 includes an epoxy resin.

[13] The thirteenth aspect of the present invention is a bonded body characterized in that, in any one of the first to twelfth aspects, the thickness of the bonding sheet 1 is 80 μm or more and 300 μm or less.

[0015]

[14] The fourteenth aspect of the present invention is a bonding sheet which is a cured product of a thermosetting resin composition containing a thermosetting resin and an inorganic filler. When looking at the bonding sheet 1 in cross section, the resin area ratio in the end region 1A from the left or right one-side end of the bonding sheet 1 to the inside 300 μm is P and the resin area ratio in the central region 1B other than the end region 1A is P 1A , when the value of P 1B / P 1A is greater than 1.10. When looking at the bonding sheet 1 in cross section, the void area ratio in the end region 1A from the left or right one-side end of the bonding sheet 1 to the inside 300 μm is S 1B and the void area ratio in the central region 1B other than the end region 1A is S 1A 1B When the value of S 1A / S 1B is greater than 1, and 1B ​ When the bonding sheet 1 is viewed in cross section, the average void size in the end region 1A from the left or right one - side end of the bonding sheet 1 to the inside by 300 μm is L 1A and the average void size in the central region 1B other than the end region 1A is L 1B When set as such, L 1A / L 1B The bonding sheet is characterized by satisfying at least one of the values being greater than 2

[0016]

[15] The 15th aspect of the present invention is a method for manufacturing a bonded body according to any one of the aspects 1 to 13, comprising laminating a thermosetting sheet formed by shaping the thermosetting resin composition into a sheet on the lower metal - containing member 3, applying a uniform pressure to bond the lower metal - containing member 3 and the thermosetting sheet, then laminating the upper metal - containing member 2 on the thermosetting sheet and applying a uniform pressure to bond the thermosetting sheet and the upper metal - containing member 2

[16] The 16th aspect of the present invention is a method for manufacturing a bonded body according to the 15th aspect, wherein the thermosetting sheet is subjected to low - temperature aging by being placed in an environment of - 50°C or higher and 0°C or lower before being laminated on the lower metal - containing member 3 [Effect of the Invention]

[0017] The bonded body proposed by the present invention relates to a bonded body having a structure in which the upper metal - containing member 2 and the lower metal - containing member 3 are bonded to the front and back of the bonding sheet 1. When the resin area ratio in the end region 1A from the left or right one - side end of the bonding sheet 1 to the inside by 300 μm is P 1A and the resin area ratio in the central region 1B other than the end region 1A is P 1B When set as such, P 1A / P 1B The value is made greater than 1.10, or when the void area ratio in the end region 1A is S 1A and the void area ratio in the central region 1B other than the end region 1A is S 1B When set as such, S 1A / S 1BIncrease the value of 1A to be greater than 1, or make the average void size in the end region 1A within 300 μm from one of the left and right end sides of the bonding sheet 1 be L 1B , and make the average void size in the central region 1B other than the end region 1A be L 1A . When 1B the value of is greater than 2, even if stress is applied to the bonding sheet 1 due to a difference in the expansion rate between members caused by a temperature change, cracks and deformation in the bonding sheet 1 can be suppressed.

Brief Description of the Drawings

[0018]

Figure 1

Figure 2

Modes for Carrying Out the Invention

[0019] Hereinafter, an example of an embodiment of the present invention will be described. However, the present invention is not limited to the embodiments described below.

[0020] <<Bonded Body of the Present Invention>> The bonded body according to an example of the embodiment of the present invention (also referred to as "the bonded body of the present invention") is a bonded body having a structure in which an upper metal-containing member 2 and a lower metal-containing member 3 are bonded to the front and back of a bonding sheet 1, as shown in FIG. 1. That is, it is a bonded body having a structure in which the upper metal-containing member 2 is bonded to the upper surface of the bonding sheet 1 and the lower metal-containing member 3 is bonded to the lower surface of the bonding sheet 1. At this time, it is preferable that the bonding sheet 1 and the upper metal-containing member 2 are directly bonded, and the bonding sheet 1 and the lower metal-containing member 3 are directly bonded. "Direct bonding" means bonding without the intervention of other members, and also means without the intervention of an adhesive (including solder). However, when the bonding surfaces of the bonding sheet 1, the upper metal-containing member 2, and the lower metal-containing member 3 are subjected to thin-layer surface treatments such as plating treatments such as nickel plating and tin plating, chemical conversion treatments, and physical treatments, which will be described later, they shall be included in "direct bonding".

[0021] As shown in FIG. 1, in the bonded body of the present invention, when viewed in the cross-section in the thickness direction, it is sufficient that the entire upper surface of one surface of the bonding sheet 1, that is, the entire upper surface, is bonded to the upper metal-containing member 2, and the entire lower surface of the other surface of the bonding sheet 1, that is, the entire lower surface, is bonded to the lower metal-containing member 3. Therefore, the area of the upper surface of the bonding sheet 1 needs to be the same as or smaller than the area of the lower surface of the upper metal-containing member 2, and the area of the lower surface of the bonding sheet 1 needs to be the same as or smaller than the area of the upper surface of the lower metal-containing member 3. At this time, the area of the upper surface of the bonding sheet 1 is preferably 80% or more and 100% or less, more preferably 90% or more and 100% or less, based on 100% of the area of the lower surface of the upper metal-containing member 2.

[0022] Also, the upper surface of the lower metal-containing member 3 is preferably larger than the lower surface of the upper metal-containing member 2. On the lower metal-containing member 3, one or a plurality of upper metal-containing members 2 can be arranged via a plurality of bonding sheets 1. Note that, as shown in FIG. 1, the bonding surfaces of the bonding sheet 1, the upper metal-containing member 2, and the lower metal-containing member 3 may each be a flat surface. However, they may each have a concave portion or a convex portion on the bonding surface.

[0023] (Resin area ratio) When the resin area ratio in the end region 1A from the left or right one-side end of the bonding sheet 1 to the inside by 300 μm when the bonding sheet 1 is viewed in cross-section is P 1A and the resin area ratio in the central region 1B other than the end region 1A is P 1B then, P1A / P 1B It is preferable that the value of is greater than 1.10.

[0024] In the present invention, the "cross-section" when the bonding sheet 1 is viewed in cross-section is a cross-section for showing the inner position and region from one end portion on the left or right side of the bonding sheet 1, and is a cross-section cut in the thickness direction along the length direction or width direction of the bonding sheet 1.

[0025] The resin area ratio P in the end region 1A 1A That is, by making the resin ratio larger than the resin area ratio P in the central region 1B 1B Preferably, by making the ratio (P 1A / P 1B ) greater than 1.10, even if stress is applied to the bonding sheet 1 due to a difference in the expansion rate between members due to a temperature change or the like, cracks and deformation in the bonding sheet 1 can be suppressed. From such a viewpoint, the resin area ratio in the end region 1A from the left or right one-side end portion of the bonding sheet 1 to the inside by 300 μm is P 1A , and the resin area ratio in the central region 1B other than the end region 1A is P 1B When, P 1A / P 1B It is preferable that the value of is greater than 1.10, more preferably 1.11 or more, still more preferably 1.12 or more, and most preferably 1.13 or more. On the other hand, from the viewpoint of suppressing the intrusion of moisture in the air between the upper metal-containing member 2 and the lower metal-containing member 3, P 1A / P 1B The value of is more preferably 2.0 or less, still more preferably 1.8 or less, may be 1.5 or less, and may be 1.2 or less.

[0026] In the present invention, the region from the left or right one-side end of the bonding sheet 1 to the inner side by 300 μm is defined as the end region 1A because it is considered to be the minimum range from the viewpoint of insulation retention and within the necessary range as a stress relaxation portion for expressing the effects of the present invention, such as improving the reliability of the cycle test. For example, when the thickness of the bonding sheet 1 is 80 μm to 300 μm, the range where stress is applied can be estimated to be approximately 100 μm to 500 μm from the left or right one-side end of the bonding sheet 1. Therefore, in the present invention, the region from the end to the inner side by 300 μm, which is the central portion of the range of 100 μm to 500 μm, is defined as the region where the influence of the applied stress can be determined.

[0027] To adjust the resin area ratio, that is, the resin ratio, in the end region 1A and the central region 1B of the bonding sheet 1 as described above, in the method of pressing the bonding sheet 1 by stacking the upper metal-containing member 2 and the lower metal-containing member 3 on the front and back of the present thermosetting sheet and heat-curing the present thermosetting sheet, the area ratio between the present thermosetting sheet and the upper metal-containing member 2, the pressing conditions, the type of thermosetting resin, the type of inorganic filler, the presence / absence and conditions of low-temperature aging, etc. may be adjusted. However, it is not limited to such a method. The above resin area ratio P 1A and P 1B can be calculated by obtaining the total area of the resin existing per unit cross-sectional area of the bonding sheet 1, that is, the total resin area, based on the cross-sectional photograph of each region of the bonding sheet 1 using image analysis software.

[0028] (Void area ratio) When the bonding sheet 1 has a void area ratio S 1A in the end region 1A from the left or right one-side end of the bonding sheet 1 to the inner side by 300 μm when viewed in cross-section, and a void area ratio S 1B in the central region 1B other than the end region 1A, it is preferable that the value of S 1A / S 1B is greater than 1. The void area ratio S 1A in the end region 1A and the void area ratio S 1BBy making it larger compared to , even if stress is applied to the bonding sheet 1 due to a difference in expansion rate between members caused by a temperature change, cracks and deformation in the bonding sheet 1 can be suppressed. From such a perspective, when the bonding sheet 1 is viewed in cross-section, the void area ratio S in the end region 1A from the left or right one-side end of the bonding sheet 1 to 300 μm inward 1A and the void area ratio S in the central region 1B other than the end region 1A 1B When set as such, it is preferable that the value of S 1A / S 1B is greater than 1, and more preferably 2 or more, among which 3 or more, among which 4 or more, among which 5 or more, among which 6 or more. On the other hand, from the perspective of suppressing the intrusion of moisture in the atmosphere between the upper metal-containing member 2 and the lower metal-containing member 3, the value of S 1A / S 1B is more preferably 10 or less, and more preferably 9 or less, and may be 8 or less, and may be 7 or less.

[0029] Also, the area of the metal part exposed on the lower surface of the upper metal-containing member 2 is preferably smaller than the area of the bonding sheet 1, preferably 20% to 90% of the area of the bonding sheet 1, and more preferably 30% or more or 80% or less. Furthermore, the area of the metal part exposed on the lower surface of the upper metal-containing member 2 is preferably 20% to 90% of the central region 1B of the bonding sheet 1, and more preferably 30% or more or 80% or less. Furthermore, it is preferable that the entire surface of the metal part exposed on the lower surface of the upper metal-containing member 2 is in contact with the central region 1B of the bonding sheet 1. With such a configuration, discharge from the end face of the bonding sheet 1 can be suppressed.

[0030] In order to adjust the void area ratio, that is, the void ratio, in the end region 1A and the central region 1B of the bonding sheet 1 as described above, in a method of superposing an upper metal-containing member 2 and a lower metal-containing member 3 on the front and back of the present thermosetting sheet described later, pressurizing the bonding sheet 1, and heat-curing the present thermosetting sheet, the area ratio of the present thermosetting sheet to the upper metal-containing member 2, the pressurizing conditions, the type of thermosetting resin, the type of inorganic filler, the presence or absence and conditions of low-temperature aging, etc. may be adjusted. However, it is not limited to such a method. The above void area ratio S 1A and S 1B can be calculated by obtaining the total area of voids existing per unit cross-sectional area of the bonding sheet 1, that is, the total void area, based on the cross-sectional photographs of each region of the bonding sheet 1 and using image analysis software.

[0031] (Void average size) When the bonding sheet 1 has a void average size L in the end region 1A from the left or right one-side end of the bonding sheet 1 to the inside 300 μm when viewed in cross-section 1A and a void average size L in the central region 1B other than the end region 1A 1B when set as 1A / L 1B it is preferable that the value of is greater than 2. By making the void average size L in the end region 1A 1A larger than the void average size L in the central region 1B 1B and preferably by making the ratio (L 1A / L 1B ) of the two greater than 2, even if stress is applied to the bonding sheet 1 due to a difference in expansion rate between members due to temperature change or the like, cracks and deformation in the bonding sheet 1 can be suppressed. From such a viewpoint, when the bonding sheet 1 is viewed in cross-section, the void average size L in the end region 1A from the left or right one-side end of the bonding sheet 1 to the inside 300 μm 1A and the void average size L in the central region 1B other than the end region 1A 1B when set as 1A / L 1BIt is preferable that the value of 1A / L 1B is greater than 2, more preferably 3 or more, still more preferably 4 or more, still more preferably 5 or more, still more preferably 6 or more, still more preferably 7 or more, and still more preferably 8 or more. On the other hand, from the viewpoint of suppressing the intrusion of moisture in the air between the upper metal-containing member 2 and the lower metal-containing member 3, L

[0032] To adjust the void average size in the end region 1A and the central region 1B of the bonding sheet 1 as described above, in the method of pressing the bonding sheet 1 by laminating the upper metal-containing member 2 and the lower metal-containing member 3 on the front and back of the thermosetting sheet described later and heating and curing the thermosetting sheet, the area ratio of the thermosetting sheet to the upper metal-containing member 2, the pressing conditions, the type of thermosetting resin, the type of inorganic filler, the presence or absence and conditions of low-temperature aging, etc. may be adjusted. However, it is not limited to such a method. The above void average size L 1A and L 1B can be calculated by obtaining the average area of voids per number based on the cross-sectional photograph of each region of the bonding sheet 1 using image analysis software.

[0033] Furthermore, in the bonded body of the present invention, the value of P 1A / P 1B is greater than 1.10, and it is more preferable that the value of S 1A / S 1B is greater than 1. Also, the value of P 1A / P 1B is greater than 1.10, and it is more preferable that the value of L 1A / L 1B is greater than 2. Also, the value of S 1A / S 1B is greater than 1, and it is more preferable that the value of L 1A / L 1B is greater than 2.

[0034] Furthermore, P 1A / P 1BThe value is greater than 1.10 and S 1A / S 1B The value is greater than 1, and L 1A / L 1B It is more preferable that the value is greater than 2. However, as described later, considering each mechanism of action, it is considered that the problem of the present invention of suppressing cracks and deformation in the bonding sheet 1 can be solved if at least one of the above-described resin area ratio, void area ratio, and void average size is satisfied.

[0035] Also, the area of the metal portion on the lower surface of the upper metal-containing member 2 is preferably smaller than the area of the bonding sheet 1, preferably 20% to 90% of the area of the bonding sheet 1, and more preferably 30% or more or 80% or less. Furthermore, the area of the metal portion on the lower surface of the upper metal-containing member 2 is preferably 20% to 90% of the central region 1B of the bonding sheet 1, and more preferably 30% or more or 80% or less. Also, it is preferable that the entire surface of the metal portion on the lower surface of the upper metal-containing member 2 is in contact with the central region 1B. With such a shape, it is possible to suppress discharge from the end face of the bonding sheet 1.

[0036] (Thermal conductivity) When the bonded body of the present invention is used in applications such as power semiconductor devices, industrial equipment, in-vehicle, and power generation energy, the thermal conductivity in the thickness direction of the bonding sheet 1 in the bonded body of the present invention, that is, the bonding sheet 1 to which both the upper metal-containing member 2 and the lower metal-containing member 3 are bonded, is preferably 10 W / m·K or more, more preferably 11 W / m·K or more, and even more preferably 12 W / m·K or more. On the other hand, it is preferably 25 W / m·K or less, and more preferably 20 W / m·K or less.

[0037] In order to adjust the thermal conductivity of the bonding sheet 1 as described above, in the method of laminating the upper metal-containing member 2 and the lower metal-containing member 3 on the front and back of the present thermosetting sheet described later, pressing the bonding sheet 1, and heat-curing the present thermosetting sheet, the pressing conditions, the type of thermosetting resin, the type of inorganic filler, the presence or absence and conditions of low-temperature aging, etc. may be adjusted. However, it is not limited to such a method. Incidentally, the thermal conductivity in the thickness direction of the bonding sheet 1 can be measured by the following method. For example, using a thermal resistance measuring device to measure the thermal resistance value, the thermal conductivity can be obtained from the slope of the graph plotting the thermal resistance value against the thickness.

[0038] (Breakdown voltage (BDV)) When the bonded body of the present invention is used in applications such as power semiconductor devices, industrial equipment, in-vehicle, power generation energy, etc., the breakdown voltage of the bonding sheet 1 in the bonded body of the present invention, that is, the bonding sheet 1 in which both the upper metal-containing member 2 and the lower metal-containing member 3 are bonded, is preferably 5 kV or more, more preferably 5.5 kV or more, and still more preferably 6 kV or more. The higher the breakdown voltage, the better, and the upper limit value is not particularly limited.

[0039] In order to adjust the breakdown voltage of the bonding sheet 1 within the above range, in the method of laminating the upper metal-containing member 2 and the lower metal-containing member 3 on the front and back of the present thermosetting sheet described later, pressing the bonding sheet 1, and heat-curing the present thermosetting sheet, the pressing conditions, the type of thermosetting resin, the type of inorganic filler, the presence or absence and conditions of low-temperature aging, etc. may be adjusted. However, it is not limited to such a method. Incidentally, the breakdown voltage of the bonding sheet 1 can be measured by applying a voltage in the thickness direction of the bonded body.

[0040] <Upper metal-containing member, lower metal-containing member> The upper metal-containing member 2 and the lower metal-containing member 3 may each have a structure provided with a metal part on the joint surface with the joint sheet 1. For example, the upper metal-containing member 2 and the lower metal-containing member 3 themselves may be made of a metal plate or a metal sheet body as the metal part, or a metal body may be exposed as the metal part on each lower surface part or upper surface part, and the metal body may be covered with an arbitrary material, for example, a synthetic resin. Those having other structures may also be used. Also, the shapes and sizes of the upper metal-containing member 2 and the lower metal-containing member 3 are not particularly limited.

[0041] <Upper metal-containing member 2> As an example of the upper metal-containing member 2, as shown in FIG. 1, on the joint surface with the joint sheet 1, the lower surface of the sheet or plate-shaped metal part 21 is exposed, and a structure in which the metal part 21 is covered and sealed with a resin 22 can be given.

[0042] The metal part 21 may be in a plate shape, a sheet shape, or other shapes. The metal part 21 is preferably made of a material having good thermal conductivity. Among them, those made of a material containing, for example, copper or aluminum can be mentioned because of their good thermal conductivity and relatively low cost. Also, from the viewpoint of heat dissipation, the metal part 21 is more preferably copper. A plating treatment such as nickel plating or tin plating, a chemical conversion treatment, or a thin layer surface treatment such as a physical roughening treatment may be performed on the joint surface of the metal part 21 with the joint sheet 1 and other surfaces.

[0043] Examples of the resin 22 for sealing the metal part 21 include resins having insulating properties. Examples of the resin having insulating properties include epoxy resin, vinyl chloride resin, acrylic resin, polypropylene, polyethylene, nylon, polycarbonate, phenol resin, polyarylate, benzoxazine, isocyanate, and the like.

[0044] As an example of the upper metal-containing member 2, as shown in FIG. 2, a semiconductor chip 23 is mounted on a metal part 21 as a heat radiating member, a wiring member 24 is wired on the metal part 21, and the metal part 21 and the semiconductor chip 23 are covered and sealed with a resin 22 having insulating properties. A module configuration can be cited. As a more specific example of the upper metal-containing member 2, a module having a molded and sealed structure can be cited. As an example of the upper metal-containing member 2, a module having a size with each side larger than 10 mm and smaller than 150 mm can be cited. For example, one or more semiconductor chips 23 are mounted on the metal part 21, a wiring member 24 is wired on the metal part 21, and the metal part 21 and the semiconductor chip 23 are embedded with a resin 22 such as an epoxy resin by molding such as a transfer method or a compression method. A module configuration can be cited. For example, a TO package module manufactured by Infineon Technologies AG, HybridPACK TM Power modules such as DSC, and AIKQ120N75CP2XKSAI manufactured by Infineon Technologies AG can be cited. However, it is not limited to these.

[0045] <Lower metal-containing member 3> As an example of the lower metal-containing member 3, one having a flat plate-shaped or sheet-shaped metal body on the joint surface with the joint sheet 1 can be cited. As the flat plate-shaped or sheet-shaped metal body, for example, one made of a material containing copper or aluminum can be cited. More specifically, a metal plate containing copper or aluminum can be cited.

[0046] As an example of the lower metal-containing member 3, one having a metal plate with a thickness of 1 mm or more can be cited. The metal plate may have a concavo-convex structure on the joint surface of the joint sheet 1, the opposite surface thereof, or both surfaces. The concavo-convex structure may be a pin structure or a plate-like structure. Alternatively, the metal plate may have a warp. Further, the metal plate may have its bonding surface of the bonding sheet 1, or the opposite surface thereof, or both surfaces, subjected to surface treatments such as plating treatments such as nickel plating and tin plating, chemical treatments, and physical roughening treatments. The metal plate may be, for example, a generally known cooling base plate, a cooling fin typified by a pin fin, or a cooling unit. Conventional ones can be used. Among them, a pin fin is preferable.

[0047] <Bonding sheet 1> The bonding sheet 1 contains a thermosetting resin and an inorganic filler 11 and has voids 12 inside.

[0048] The bonding sheet 1 is a cured product of a thermosetting resin composition containing a thermosetting resin and an inorganic filler (referred to as "this thermosetting resin composition"). That is, it is a cured product of a thermosetting sheet (referred to as "this thermosetting sheet") formed by molding the this thermosetting resin composition into a sheet shape.

[0049] In the present invention, the "thermosetting resin composition" means a resin composition having the property of curing by heat. That is, any resin composition having curability with room for curing by heat may be used, and it may be already cured (also referred to as "pre-cured") in a state with room for curing, or it may be in a state where it has not been cured at all (referred to as "uncured"). Further, the "thermosetting sheet" means a sheet having the property of curing by heat. That is, any sheet having curability with room for curing by heat may be used, and it may be already cured (also referred to as "pre-cured") in a state with room for curing, or it may be in a state where it has not been cured at all (referred to as "uncured").

[0050] (Thickness) The thickness of the bonding sheet 1 is not particularly limited. When the bonded body of the present invention is used in, for example, a power semiconductor device, industrial equipment, in-vehicle applications, power generation energy, etc., the thickness of the bonding sheet 1 is preferably 80 μm or more, more preferably 100 μm or more, still more preferably 110 μm or more, and even more preferably 120 μm or more. On the other hand, the upper limit value of the thickness is preferably 300 μm or less, more preferably 250 μm or less, still more preferably 220 μm or less, even more preferably 200 μm or less, and even more preferably 180 μm or less. By setting the thickness of the bonding sheet 1 to 80 μm or more, not only can high heat dissipation performance be ensured, but also sufficient withstand voltage characteristics can be ensured. On the other hand, by setting it to 300 μm or less, miniaturization or thinning of the bonded body of the present invention can be achieved, and also, compared with the insulating and thermally conductive layer made of a ceramic material, the effect of reducing the thermal resistance in the thickness direction due to thinning can be obtained. Note that the thickness of the bonding sheet 1 decreases due to the thermal pressing when producing the bonded body of the present invention. The reduction rate of the thickness at that time is preferably 1% or more, more preferably 2% or more, from the viewpoint of insulation. On the other hand, from the viewpoint of maintaining the form, it is preferably 10% or less, more preferably 8% or less.

[0051] (This thermosetting resin composition) This thermosetting resin composition contains a thermosetting resin and an inorganic filler, and is not particularly limited as long as the bonding sheet 1 satisfies the above physical properties.

[0052] As the thermosetting resin, conventionally known ones can be used. For example, epoxy resins, phenolic resins, urea resins, melamine resins, polyester (unsaturated polyester) resins, polyimide resins, silicone resins, polyurethane resins, maleimide resins, cyanate resins, benzoxazines, etc. can be mentioned. Among them, it is preferable that the thermosetting resin contains an epoxy resin. Note that as the thermosetting resin, one or a mixture of two or more of these resins can be used.

[0053] As the inorganic filler, conventionally known ones can be used, and examples thereof include particles such as nitrides such as boron nitride and metal oxides such as alumina. In addition, one or more of these inorganic fillers can be mixed and used as the inorganic filler.

[0054] Among them, as the inorganic filler, boron nitride aggregated particles, that is, boron nitride aggregated particles formed by aggregation of primary particles of boron nitride, are preferably included from the viewpoints of having few problems of moisture absorption during heat molding, low toxicity, being able to efficiently increase the thermal conductivity, and being able to impart high insulation to the bonding sheet 1. From the viewpoint of improving the thermal conductivity, the aggregation structure of the boron nitride aggregated particles preferably has a card house structure. That is, the boron nitride aggregated particles preferably have a card house structure. The card house structure is a structure in which plate-like particles are stacked complexly without orientation, and is described in "Ceramics·43·No.2" (issued by The Ceramic Society of Japan in 2008). More specifically, it refers to a structure in which the flat surface portion of the primary particles forming the aggregated particles is in contact with the end surface portion of other primary particles present in the aggregated particles. The boron nitride aggregated particles having the card house structure have extremely high fracture strength due to their structure, and can suppress crushing even when pressurized in the manufacturing process of the bonding sheet 1. Therefore, usually, the primary particles that would otherwise be oriented in the longitudinal direction of the sheet can be made to exist in random directions. Therefore, when using boron nitride aggregated particles having a card house structure, the ratio of the ab plane of the primary particles oriented in the thickness direction of the bonding sheet 1 can be further increased, so that heat conduction can be effectively performed in the thickness direction of the bonding sheet 1, and the thermal conductivity in the thickness direction can be further increased.

[0055] The content of the thermosetting resin is preferably 5% by mass or more and 99% by mass or less with respect to 100% by mass of the solid content excluding the inorganic filler from the total solid content of the present thermosetting resin composition. If the content of the thermosetting resin is 5% by mass or more, the moldability is good, which is preferable. On the other hand, if it is 99% by mass or less, the content of other components can be ensured and the thermal conductivity can be increased, which is preferable. From such a viewpoint, the content of the thermosetting resin is preferably 5% by mass or more and 99% by mass or less with respect to 100% by mass of the solid content excluding the inorganic filler from the total solid content of the present thermosetting resin composition. Among them, it is more preferably 10% by mass or more, more preferably 20% by mass or more, more preferably 30% by mass or more, more preferably 40% by mass or more, and more preferably 50% by mass or more. On the other hand, it is more preferably contained at a ratio of 98% by mass or less.

[0056] The total content of the inorganic filler is preferably 40% by mass or more and 90% by mass or less with respect to 100% by mass of the total solid content of the present thermosetting resin composition. If the total content of the inorganic filler is 40% by mass or more, the thermal conductivity can be increased. On the other hand, if it is 90% by mass or less, the adhesion and insulation properties can be improved. From such a viewpoint, the total content of the inorganic filler is preferably 40% by mass or more with respect to 100% by mass of the total solid content of the present thermosetting resin composition. Among them, it is more preferably 50% by mass or more, more preferably 53% by mass or more, and even more preferably 55% by mass or more. On the other hand, it is preferably 90% by mass or less, more preferably 80% by mass or less, more preferably 75% by mass or less, and even more preferably 72% by mass or less.

[0057] As described above, it is preferable to include an epoxy resin as the thermosetting resin, and as the inorganic filler, from the viewpoints of water resistance and low relative permittivity, it is preferable to include boron nitride aggregated particles formed by aggregation of primary particles composed of boron nitride. Among them, from the viewpoints of high thermal conductivity and high withstand voltage, it is preferable to include boron nitride aggregated particles having a card house structure as the boron nitride aggregated particles, and the shape is preferably spherical. In this case, with respect to 100% by mass of the total solid content of the present thermosetting resin composition, the content ratio of the boron nitride aggregated particles having a card house structure is preferably 40% by mass or more and 90% by mass or less, more preferably 50% by mass or more or 80% by mass or less, and still more preferably 55% by mass or more or 70% by mass or less.

[0058] The present thermosetting resin composition may be a composition containing, in addition to the thermosetting resin and the inorganic filler, other polymers, curing agents, curing accelerators, organic solvents, and other components as required, and these can be those known in the art, and examples thereof include the compositions described in International Publication No. 2023 / 189030 and the like.

[0059] <Method for manufacturing the bonded body of the present invention> Next, the method for manufacturing the bonded body of the present invention will be described. As the method for manufacturing the bonded body of the present invention, there are a method of disposing the present thermosetting sheet (bonding sheet 1) between the upper metal-containing member 2 and the lower metal-containing member 3 and controlling the pressing conditions such as the pressing pressure, pressing temperature, and pressing configuration, or a method of previously preparing a bonding sheet 1 having regions with different resin area ratios, void area ratios, or void average sizes and disposing it between the upper metal-containing member 2 and the lower metal-containing member 3. Preferably, the former method of controlling the pressing conditions is used. However, since the method described below is an example of the method for manufacturing the bonded body of the present invention, it is not limited to the following method.

[0060] As an example of the method for manufacturing the bonded body of the present invention, there can be mentioned a method for manufacturing a bonded body, which comprises laminating the present thermosetting sheet (bonding sheet 1) formed by shaping the present thermosetting resin composition into a sheet on the lower metal-containing member 3, applying a uniform pressure to bond the lower metal-containing member 3 and the present thermosetting sheet (bonding sheet 1), then laminating the upper metal-containing member 2 on the present thermosetting sheet (bonding sheet 1), and applying a uniform pressure to bond the present thermosetting sheet (bonding sheet 1) and the upper metal-containing member 2. At this time, it is preferable that this thermosetting sheet (bonding sheet 1) has been subjected to low-temperature aging by being placed in an environment of -50°C or higher and 0°C or lower in advance, that is, before being overlaid on the lower metal-containing member 3 as described above. Note that the reason for referring to "this thermosetting sheet (bonding sheet 1)" is that this thermosetting sheet is also the bonding sheet 1. This will be described in more detail below.

[0061] First, it is preferable to overlay this thermosetting sheet (bonding sheet 1) on the lower metal-containing member 3 and apply a uniform pressure (first pressurization) to bond the lower metal-containing member 3 and this thermosetting sheet (bonding sheet 1). At this time, as a material used to make the pressure uniform, for example, any other material such as copy paper, a fluorine-based film such as Teflon, a silicone rubber sheet, carbon paper, or a graphite sheet can be used as a cushion material.

[0062] Next, it is preferable to overlay the upper metal-containing member 2 on this thermosetting sheet (bonding sheet 1) and apply a uniform pressure (second pressurization) to bond this thermosetting sheet (bonding sheet 1) and the upper metal-containing member 2. That is, by pressurizing this thermosetting sheet (bonding sheet 1) that overlaps both the upper metal-containing member 2 and the lower metal-containing member 3 when viewed in cross-section, and further heating the entire this thermosetting sheet (bonding sheet 1) to cause thermosetting, the upper metal-containing member 2 and the lower metal-containing member 3 can be bonded to the front and back of the bonded body sheet 1, and the bonded body of the present invention can be produced. At this time, the area of the lower surface of the upper metal-containing member 2 is preferably 80% to 100% of the area of the upper surface of this thermosetting sheet (bonding sheet 1). At this time, a plurality of upper metal-containing members 2 to be bonded in a sheet form may be used. Also, as a material used to make the pressure uniform, for example, any other material such as copy paper, a fluorine-based film such as Teflon, a silicone rubber sheet, carbon paper, or a graphite sheet can be used as a cushion material.

[0063] Since it is sufficient for the first pressurization to be able to temporarily fix the present thermosetting sheet (bonding sheet 1) on the lower metal-containing member 3, it is preferable to pressurize so that a load of 0.5 MPa or more and 10 MPa or less is applied to the present thermosetting sheet (bonding sheet 1). Among them, it is more preferable to pressurize so that a load of 1 MPa or more or 9 MPa or less, and among them, a load of 2 MPa or more or 8 MPa or less is applied.

[0064] By pressurizing the present thermosetting sheet (bonding sheet 1) that overlaps both the upper metal-containing member 2 and the lower metal-containing member 3 when viewed in cross-section by the second pressurization, the sheet can flow laterally to increase the resin ratio in the end region 1A. Also, while the voids are crushed, they can flow laterally to increase the size of the voids in the end region 1A, and the void ratio can be increased. Also, by preventing the secondary particles of an inorganic filler such as boron nitride agglomerated particles from being broken, the contact between the inorganic fillers can be improved, making it easier to form a heat conduction path and enhancing the thermal conductivity. Furthermore, by lowering the viscosity of the resin component by high-temperature pressurization, and by causing the present thermosetting sheet (bonding sheet 1) to flow in a minute end face, stress can be relaxed in the end region 1A where pressure is likely to locally concentrate during high-pressure pressing. From such a viewpoint, in the second pressurization, it is desirable to carry out with a load of 2 MPa or more. The load is preferably 4 MPa or more, more preferably 5 MPa or more, and still more preferably 6 MPa or more. Also, the load is preferably 150 MPa or less, more preferably 100 MPa or less, and still more preferably 20 MPa or less.

[0065] In the second pressurization, heating may be carried out simultaneously. The heating temperature (product temperature) at this time is preferably 10 °C or more, more preferably 20 °C or more, and still more preferably 30 °C or more. The heating temperature is preferably 300 °C or less, more preferably 250 °C or less, and still more preferably 200 °C or less. By performing the second pressurization within this temperature range, the melt viscosity of the resin of this thermosetting sheet (bonding sheet 1) can be decreased, making it easier for the sheet to flow horizontally and enabling a higher resin ratio in the end region 1A. Also, while voids are crushed, it can be made easier to flow horizontally, enabling a larger void size in the end region 1A and a higher void ratio.

[0066] As a specific example, the upper and lower top plate parts of a press are preheated in advance. The upper metal-containing member 2 is stacked on this thermosetting sheet (bonding sheet 1) stacked on the lower metal-containing member 3 to form a laminate, and this laminate is set in a press and pressurized with the upper and lower top plate parts, so that pressurization and heating can be performed simultaneously. Alternatively, after stacking this thermosetting sheet (bonding sheet 1) on the lower metal-containing member 3 and stacking the upper metal-containing member 2 on this thermosetting sheet (bonding sheet 1) to form a laminate and setting the laminate in a press, the press or its press part is heated and pressurized, so that pressurization and heating can be performed simultaneously. At this time, both regions 1A and 1B of this thermosetting sheet (bonding sheet 1) are heated. Note that the temperature of the top plate part can be regarded as the product temperature of this thermosetting sheet (bonding sheet 1).

[0067] The pressurization time of the second pressurization is not particularly limited. Preferably it is 30 seconds or more, more preferably 1 minute or more, still more preferably 3 minutes or more, and particularly preferably 5 minutes or more. The time of the pressurization process is preferably 1 hour or less, more preferably 30 minutes or less, still more preferably 20 minutes or less. By the pressurization time being below the above upper limit value, the manufacturing time can be suppressed and the production cost can tend to be reduced. By the pressurization time being above the above lower limit value, the content rate of voids in this thermosetting sheet (bonding sheet 1) can be made low, and the heat transfer performance and withstand voltage characteristics can tend to be improved.

[0068] After the second pressurization, the thermosetting sheet (bonding sheet 1) may be cured by heating. At this time, the heating temperature (product temperature) is preferably 30°C to 400°C, more preferably 50°C or higher, and even more preferably 90°C or higher. On the other hand, it is preferably 300°C or lower, and even more preferably 250°C or lower.

[0069] In addition, as the above-mentioned pressing method, various known pressing devices for thermosetting resin molding can be used. From the viewpoint of preventing resin deterioration during heating press, it is particularly preferable to use a vacuum pressing device capable of reducing the amount of oxygen in the press machine during heating or a pressing device equipped with a nitrogen replacement device. In addition, as the above-mentioned heating method, methods such as temperature control of the upper and lower top plate parts of the above-mentioned pressing device can be mentioned.

[0070] It should be noted that it is preferable to perform low-temperature aging on this thermosetting sheet in advance, that is, at least before stacking this thermosetting sheet on the lower metal-containing member 3. For low-temperature aging, for example, it is preferably placed in an environment of -50°C or higher and 0°C or lower, more preferably -30°C or higher or -5°C or lower, and preferably for 5 minutes or more and 365 days or less, more preferably for 1 hour or more or 7 days or less. It is not necessary to apply pressure during low-temperature aging. However, a minute pressure of 0.1 kPa or less may be applied. Examples of the timing for low-temperature aging include after coating, after heat drying, and after pressing. Among them, after pressing is preferable. However, this pressing refers to the pressing during the production of this thermosetting sheet before the heat press for producing the bonded body of the present invention.

[0071] By performing such low-temperature aging on this thermosetting sheet, the moisture inside the sheet can be frozen and dispersed as minute ice, and by creating small chambers of moisture confined in fine spaces even after returning to room temperature, deterioration of insulation can be prevented without generating large voids, and generation of cracks when the sheet is bent due to moisture retention can be suppressed. Further, by highly dispersing minute voids in the sheet, the fluidity of the resin component when pressurized is increased, the resin amount ratio at the ends is increased, and at the same time, the voids inside the sheet are easily extruded to the ends, and the voids accumulated at the ends are connected, and an effect of increasing their size can be expected. Furthermore, an effect of stress relaxation at the interface end of the bonded body of the present invention can also be expected.

[0072] <Explanation of terms, etc.> In the present invention, when referring to a "film", it includes a "sheet", and when referring to a "sheet", it includes a "film". In the present invention, when described as "α to β" (α and β are arbitrary numbers), unless otherwise specified, it includes the meaning of "α or more and β or less", and also the meaning of "preferably greater than α" or "preferably less than β". Also, when described as "α or more" or "α ≦" (α is an arbitrary number), unless otherwise specified, it includes the meaning of "preferably greater than α", and when described as "β or less" or "≦ β" (β is an arbitrary number), unless otherwise specified, it includes the meaning of "preferably less than β".

Examples

[0073] Hereinafter, an example of an embodiment of the present invention will be described. However, the present invention is not limited to the embodiments described below.

[0074] (Upper metal-containing member 2) As the upper metal-containing member 2, a member having a size of 21 mm in length × 16 mm in width × 5 mm in thickness was prepared, which had a structure in which the periphery of the bottom surface of a copper plate having a length of 16 mm, a width of 13 mm, and a thickness of 2 mm as the metal part 21 was coated with an epoxy resin as the resin 22.

[0075] (Lower metal-containing member 3) As the lower metal-containing member 3, a copper plate with a length of 40 mm, a width of 80 mm, and a thickness of 2 mm was prepared.

[0076] (Preparation of thermosetting sheet 1a) 9 parts by mass of a high molecular weight epoxy resin (weight average molecular weight in terms of polystyrene: 30,000, epoxy equivalent: 9,000 g / equivalent, density of about 1.2 g / cm 3 ) 7 parts by mass of a polyfunctional epoxy resin containing a structure having 4 or more glycidyl groups in one molecule (molecular weight of 500 or less, density of about 1.2 g / cm 3 ) 15 parts by mass of a biphenyl-type solid epoxy resin (molecular weight of about 400, density of about 1.2 g / cm 3 ) 63 parts by mass of spherical boron nitride aggregated particles having a card house structure (average particle diameter (D50) of 45 μm, maximum particle diameter (Dmax) of 90 μm), 5 parts by mass of a phenolic resin-based curing agent, a curing catalyst (2,4-diamino-6-[2'-ethyl-4'-methylimidazolyl-(17')]-ethyl-s-triazine, molecular weight: 247, property: solid, melting point: 215 - 225 °C) 0.4 parts by mass, and a curing catalyst (2-phenyl-4,5-dihydroxymethylimidazole, molecular weight: 204, property: solid, melting point: dec. 230, so the melting point is 230 °C or higher) 0.4 parts by mass were added with methyl ethyl ketone and cyclohexanone so that the solid content concentration became 74% by mass, and mixed using a planetary stirrer to prepare a slurry-like thermosetting resin composition.

[0077] The maximum particle diameter (Dmax) and average particle diameter (D50) of the boron nitride aggregated particles were obtained by dispersing the boron nitride aggregated particles in a pure water medium containing sodium hexametaphosphate as a dispersion stabilizer, measuring the volume-based particle size distribution with a laser diffraction / scattering type particle size distribution measuring device LA-300 (manufactured by Horiba, Ltd.), and determining the maximum particle diameter Dmax and the cumulative volume 50% particle diameter (average particle diameter D50) from the obtained particle size distribution.

[0078] The slurry-like thermosetting resin composition obtained as described above was applied to a PET substrate by the doctor blade method, heated and dried at 60 °C (ambient temperature) for 120 minutes, and then, using a press, at 42 °C (product temperature), 1500 kgf / cm 2 and pressed for 10 minutes to obtain a sheet-like resin composition having a length of 20 mm, a width of 15 mm, and a thickness of 150 μm (referred to as "thermosetting sheet 1a"). The total content of methyl ethyl ketone and cyclohexanone in the thermosetting sheet 1a was 1% by mass or less. The above thermosetting sheet 1a was placed in a freezer at -20 °C for 2 days without applying any particular load to perform low-temperature aging to obtain the thermosetting sheet 1a.

[0079] <Example 1> Using the above-described upper metal-containing member 2, lower metal-containing member 3, and thermosetting sheet 1a, a joined body was produced as follows.

[0080] The thermosetting sheet 1a was stacked on the lower metal-containing member 3 so that the entire lower surface of the thermosetting sheet 1a overlapped with the lower metal-containing member 3 to form a laminate. Copy paper was placed on top and bottom of this laminate, and this was set in a press machine whose upper and lower platen parts had been preheated to 80 °C, and hot-pressed at 80 °C (product temperature) such that a load of 2 MPa was applied for 5 minutes. Next, the upper metal-containing member 2 was stacked on the thermosetting sheet 1a stacked on the lower metal-containing member 3 so that the entire upper surface of the thermosetting sheet 1a overlapped with the upper metal-containing member 2, and also so that the entire bottom metal part of the upper metal-containing member 2 overlapped with the sheet 1a to form a laminate. Further, copy paper was placed on top and bottom of this laminate, and this was set in a press machine whose upper and lower platen parts had been preheated to 180 °C, and hot-pressed at 180 °C (product temperature) such that a load of 6 MPa was applied for 30 minutes. As shown in FIG. 1, the upper metal-containing member 2 and the lower metal-containing member 3 were joined to the front and back of the joined sheet 1 having a thickness of 150 μm to obtain a joined body.

[0081] When the bonding sheet 1 is viewed in cross-section, the resin area ratio P in the end region 1A from the left or right one-side end of the bonding sheet 1 to the inside by 300 μm 1A is 51%, and the resin area ratio P in the central region 1B 1B is 45%, and the ratio of the two (P 1A / P 1B ) was 1.13. The void area ratio S in the end region 1A 1A is 5.5%, and the void area ratio S in the central region 1B 1B is 0.8%, and the ratio of the two (S 1A / S 1B ) was 6.8. The average void size L in the end region 1A 1A is 14 μm 2 / piece, and the average void size L in the central region 1B 1B is 1.6 μm 2 / piece, and the ratio of the two (L 1A / L 1B ) was 8.75. The area of the metal part exposed on the lower surface of the upper metal-containing member 2 was 68% of the area of the bonding sheet 1, 68% of the central region 1B of the bonding sheet 1, and the entire metal part was in contact with the central region 1B of the bonding sheet 1. It was confirmed that the breakdown voltage (BDV) of the bonding sheet 1 was 5 kV or more. The thermal conductivity in the thickness direction of the bonding sheet 1 was 14 W / m·K. Using an ultrasonic imaging device, the presence or absence of cracks and deformations in the bonding sheet 1 during manufacturing and the interface between the metal (upper metal-containing member 2 and lower metal-containing member 3) and the bonding sheet 1 were observed. As a result, no cracks or deformations were found, and no peeling was found at the interface. It was confirmed that the breakdown voltage (BDV) of the bonding sheet 1 after the thermal cycle test was 5 kV or more. After the thermal cycle test, using an ultrasonic imaging device, the presence or absence of cracks and deformations in the bonding sheet 1 during temperature change after manufacturing and the interface between the metal (upper metal-containing member 2 and lower metal-containing member 3) and the bonding sheet 1 were observed. As a result, no cracks or deformations were found, and no peeling was found at the interface.

[0082] <Comparative Example 1> In the production of the thermosetting sheet 1a, instead of low-temperature aging by placing it in a freezer at -20°C for 2 days, aging was performed by placing it in an environment at 100°C for 1 hour to obtain a thermosetting sheet. Then, a joined body was produced in the same manner as in Example 1 except that the obtained thermosetting sheet was used.

[0083] When the joined sheet 1 in this joined body was viewed in cross section, the resin area ratio P in the end region 1A from the left or right one-side end of the joined sheet 1 to the inside by 300 μm 1A was 42%, and the resin area ratio P in the central region 1B 1B was 44%. The ratio of the two (P 1A / P 1B ) was 0.95. The void area ratio S in the end region 1A 1A was 7.0%, and the void area ratio S in the central region 1B 1B was 7.9%. The ratio of the two (S 1A / S 1B ) was 0.89. The average void size L in the end region 1A 1A was 109 μm 2 / number, and the average void size L in the central region 1B 1B was 55 μm 2 / number. The ratio of the two (L 1A / L 1B ) was 1.98. The area of the metal part exposed on the lower surface of the upper metal-containing member 2 was 68% of the area of the joined sheet, 68% of the central region 1B of the joined sheet 1, and the entire metal part was in contact with the central region 1B of the joined sheet. It was confirmed that the breakdown voltage (BDV) of the joined sheet 1 after the thermal cycle test was less than 5 kV. After the thermal cycle test, when the joined sheet 1 was observed for cracks and deformations during temperature changes after production and the interface between the metal (upper metal-containing member 2 and lower metal-containing member 3) and the joined sheet 1 using an ultrasonic imaging device, cracks and deformations were observed, and peeling was also observed at the interface.

[0084] <Comparative Example 2> In the production of the thermosetting sheet 1a, instead of the low-temperature aging in which it was placed in a freezer at -20°C for 2 days, aging was performed by placing it in an environment at 60°C for 3 days to obtain a thermosetting sheet. Then, a bonded body was produced in the same manner as in Example 1 except that the thermosetting sheet was used.

[0085] When the bonding sheet 1 in this bonded body was viewed in cross section, the resin area ratio P in the end region 1A from the left or right one-side end of the bonding sheet 1 to the inside by 300 μm 1A was 40%, and the resin area ratio P in the central region 1B 1B was 37%, and the ratio of the two (P 1A / P 1B ) was 1.08. The void area ratio S in the end region 1A 1A was 6.6%, and the void area ratio S in the central region 1B 1B was 12%, and the ratio of the two (S 1A / S 1B ) was 0.55. The average void size L in the end region 1A 1A was 108 μm 2 / number, and the average void size L in the central region 1B 1B was 85 μm 2 / number, and the ratio of the two (L 1A / L 1B ) was 1.27. The area of the metal part exposed on the lower surface of the upper metal-containing member 2 was 68% of the area of the bonding sheet 1 and 68% of the central region 1B of the bonding sheet 1, and the entire metal part was in contact with the central region 1B of the bonding sheet 1. It was confirmed that the breakdown voltage (BDV) of the bonding sheet 1 after the thermal cycle test was less than 5 kV. After the thermal cycle test, when the bonding sheet 1 was observed for cracks and deformations during temperature changes after production and the interface between the metal (upper metal-containing member 2 and lower metal-containing member 3) and the bonding sheet 1 using an ultrasonic imaging device, cracks and deformations were observed, and peeling was also observed at the interface.

[0086] <Measurement method and evaluation method of physical properties> The physical properties and evaluation of the bonded bodies produced in the examples and comparative examples were carried out as follows.

[0087] (Taking cross-sectional SEM images) Bonding sheets were produced under the same conditions as the bonding sheet 1 in the bonded bodies produced in the examples and comparative examples. That is, a part of the thermosetting sheet 1a was hot-pressed at 80 °C (product temperature) with a load of 2 MPa for 5 minutes, and then hot-pressed at 180 °C (product temperature) with a load of 6 MPa for 30 minutes, to produce a bonding sheet (measurement sample) having a region pressurized twice and a region not pressurized twice. Appropriate locations of this bonding sheet (measurement sample) were cut in the thickness direction along the width direction (lateral direction) using a churring process (DSW3500P (manufactured by Maiwa Focus Co., Ltd.)), and the cross-section was used. Cross-section processing was performed by subjecting an arbitrary location on each sheet cut surface to ion milling treatment (Cross Section Polisher SM-09010 (manufactured by JEOL Ltd.)). Thereafter, SEM images were obtained by observing with a SEM scanning electron microscope (SU5000 (manufactured by Hitachi, Ltd.)) at an acceleration voltage of 10 kV and a magnification of 300 times.

[0088] (Calculation method of resin area ratio) The calculation of the resin area ratio was performed by cutting out a range of 300 μm × 165 μm at an arbitrary location in the SEM image obtained above, and performing image analysis on the image of that range using image analysis software. That is, the cut-out image was binarized, and from the difference in contrast, the areas of the copper plate, inorganic filler, resin (that is, the portion composed of high molecular weight epoxy resin, polyfunctional epoxy resin, biphenyl type solid epoxy resin, phenolic resin-based curing agent, and curing catalyst), and void were separated, and the area of the region corresponding to the resin was divided by the total area of the inorganic filler, resin, and void, and multiplied by 100 to obtain the filler area ratio (%). The resin area ratio (%) of the end region 1A and the center 1B was shown as the average value of two fields of view.

[0089] (Calculation method of void area ratio) The calculation of the void area ratio was performed by cutting out a range of 300 μm × 165 μm at an arbitrary location in the SEM image obtained above, and performing image analysis on the image of that range using image analysis software. That is, the cut-out image was binarized, and from the difference in its contrast, the areas of the copper plate, inorganic filler, resin (i.e., the portion composed of high molecular weight epoxy resin, polyfunctional epoxy resin, biphenyl type solid epoxy resin, phenolic resin-based curing agent, and curing catalyst), and void were separated. The area of the region corresponding to the void was divided by the total area of the inorganic filler, resin, and void, and multiplied by 100 to obtain the filler area ratio (%). The void area ratio (%) of the end region 1A and the center 1B was shown as the average value of two fields of view.

[0090] (Method for calculating the average void size) In the SEM image obtained in the same manner as above, a range of 300 μm × 165 μm was cut out at an arbitrary location, and the area (μm 2 ) of the region corresponding to the void obtained as above was divided by the number of voids in the same region to obtain the average void size. The average void size (μm 2 / number) of the end region 1A and the center 1B was shown as the average value (μm 2 / number) of two fields of view.

[0091] (Breakdown voltage (BDV) measurement) The bonded bodies obtained in the examples and comparative examples were immersed in Fluorinert FC-40 (manufactured by 3M), a voltage application jig was installed so that a voltage was applied between the metal part 21 of the upper metal-containing member 2 and the lower metal-containing member 3, and using a high-voltage withstand tester 7470 (manufactured by Measurement Technology Research Institute), a voltage of 0.5 kV was applied to the region 1A of the bonding sheet 1, and the voltage was increased by 0.5 kV every 60 seconds to measure the breakdown voltage (BDV), and it was confirmed whether the breakdown voltage (BDV) was 5 kV or more.

[0092] (Measurement of thermal conductivity) A bonding sheet was produced under the same conditions as the bonding sheet 1 produced in the examples. That is, the thermosetting sheet 1a was hot-pressed at 80 °C (product temperature) with a load of 2 MPa applied for 5 minutes, and then hot-pressed at 180 °C (product temperature) with a load of 6 MPa applied for 30 minutes to produce a bonded sheet (measurement sample) that was pressure-applied twice. The thermal conductivity of the bonding sheet (measurement sample) was measured using the "T3ster DynTIM Tester" manufactured by Mentor Graphics. Two, three, or four bonding sheets (measurement samples) were stacked, and the thickness, area, and thermal resistance values of four types of sheets with different thicknesses were measured. From the slope represented by the thermal resistance value with respect to the sheet thickness, the thermal conductivity (25 °C) in the sheet thickness direction by the steady-state method was determined (conforming to ASTM D5470). Note that the probe size during measurement was φ12.8 mm, the fixed pressure was 3400 kPa, and the measurement time was 300 sec. "OIL COMPOUND (product name: G-747)" manufactured by Shin-Etsu Chemical Co., Ltd. was used to improve the adhesion between the sample and the probe.

[0093] (Observation of cracks, deformation, and interface) The bonded bodies produced in the examples and comparative examples were observed for cracks and deformation in the bonding sheet 1 and the interface between the metal (upper metal-containing member 2 and lower metal-containing member 3) and the bonding sheet 1 using an ultrasonic imaging device FinSAT (FS300III) manufactured by Hitachi Power Solutions. For the measurement, a probe with a frequency of 50 MHz was used, the gain was 30 dB, the pitch was 0.2 mm, and the bonded body (sample) was placed in water for the measurement. Such results were taken as the presence or absence of cracks and deformation during manufacturing and the observation results of the interface.

[0094] (Thermal cycle test) The bonded bodies produced in the examples and comparative examples were subjected to a thermal cycle test using a thermal shock device TSA-41L-A (manufactured by Espec). The test conditions were: starting from room temperature, cooling to -40 °C and holding for 30 minutes, then returning to room temperature, and then heating to 150 °C (product temperature) and holding for 30 minutes, and then returning to room temperature. One cycle was defined as one cycle, and this was repeated 100 times. After the thermal cycle test, in the same manner as described above, the breakdown voltage (BDV) was measured, and it was confirmed whether the breakdown voltage (BDV) was 5 kV or more. Also, after the thermal cycle test, in the same manner as described above, using an ultrasonic imaging device, the presence or absence of cracks and deformation in the bonding sheet 1 and the interface between the metal (the upper metal-containing member 2 and the lower metal-containing member 3) and the bonding sheet 1 were observed. Such results were taken as the presence or absence of cracks and deformation and the observation results of the interface during temperature changes after manufacturing.

[0095] (Discussion) From the above-described examples and comparative examples, and the test results obtained by the present inventors to date, in a joined body having a structure in which the upper metal-containing member 2 and the lower metal-containing member 3 are joined to the front and back of the bonding sheet 1, the resin area ratio P in the end region 1A from the left or right one-side end portion of the bonding sheet 1 to the inside by 300 μm 1A , and the resin area ratio P in the central region 1B other than the end region 1A 1B When 1A / P 1B is made greater than 1.10, or when viewing the bonding sheet 1 in cross-section, the void area ratio S in the end region 1A from the left or right one-side end portion of the bonding sheet 1 to the inside by 300 μm 1A , and the void area ratio S in the central region 1B other than the end region 1A 1B When 1A / S 1B is made greater than 1, or when viewing the bonding sheet 1 in cross-section, the average void size L in the end region 1A from the left or right one-side end portion of the bonding sheet 1 to the inside by 300 μm 1A , and the average void size L in the central region 1B other than the end region 1A 1B When 1A / L 1B is made greater than 2, it was found that even if stress is applied to the bonding sheet 1 due to a difference in expansion rate between members due to temperature changes, cracks and deformation in the bonding sheet 1 can be suppressed.

[0096] P 1A / P 1BBy making the value of greater than 1.10, that is, by increasing the resin ratio in the end region 1A of the bonding sheet 1, the stress relaxation effect can be enhanced. Even if stress is applied to the bonding sheet 1 due to a difference in expansion rate between members caused by temperature change in a test or mounting process where stress particularly occurs at the end of the bonding sheet 1, it is presumed that cracking and deformation in the bonding sheet 1 can be suppressed. Also, S 1A / S 1B By making the value of greater than 1, in a test or mounting process where stress particularly occurs at the end of the bonding sheet 1, voids act like a buffer material, and by enhancing the stress relaxation effect, even if stress is applied to the bonding sheet 1 due to a difference in expansion rate between members caused by temperature change, it is presumed that cracking and deformation in the bonding sheet 1 can be suppressed. Also, L 1A / L 1B By making the value of greater than 2, in a test or mounting process where stress particularly occurs at the end of the bonding sheet 1, even if stress is applied to the bonding sheet 1 due to a difference in expansion rate between members caused by temperature change, it is presumed that cracking and deformation in the bonding sheet 1 can be suppressed. From the above mechanism of action, if at least one of the three requirements is satisfied, it is considered that the problem of the present invention of suppressing cracking and deformation in the bonding sheet 1 can be solved even if stress is applied to the bonding sheet 1 due to a difference in expansion rate between members caused by temperature change.

Explanation of Reference Numerals

[0097] 1 Bonding sheet 1A End region 1B Central region 2 Upper metal-containing member 3 Lower metal-containing member 11 Inorganic filler 12 Void 21 Metal part 22 Resin 23 Semiconductor chip 24 Wiring member

Claims

1. A bonded body having a configuration in which an upper metal-containing member 2 and a lower metal-containing member 3 are bonded to the front and back of a bonding sheet 1, Each of the upper metal-containing member 2 and the lower metal-containing member 3 has a metal portion on a joining surface with the joining sheet 1, The bonding sheet 1 is a cured product of a thermosetting resin composition containing a thermosetting resin and an inorganic filler, The entire upper surface of the joining sheet 1 is joined to the upper metal-containing member 2, and the entire lower surface of the joining sheet 1 is joined to the lower metal-containing member 3. When the joining sheet 1 is viewed in cross section, the resin area ratio in an end region 1A extending from one of the left and right ends of the joining sheet 1 to 300 μm inward is P １Ａ , the resin area ratio in the central region 1B other than the end region 1A is P １Ｂ Then, P １Ａ / P １Ｂ A joint body characterized in that the value of is greater than 1.

10.

2. A bonded body having a configuration in which an upper metal-containing member 2 and a lower metal-containing member 3 are bonded to the front and back of a bonding sheet 1, Each of the upper metal-containing member 2 and the lower metal-containing member 3 has a metal portion on a joining surface with the joining sheet 1, The bonding sheet 1 is a cured product of a thermosetting resin composition containing a thermosetting resin and an inorganic filler, The entire upper surface of the joining sheet 1 is joined to the upper metal-containing member 2, and the entire lower surface of the joining sheet 1 is joined to the lower metal-containing member 3. When the joining sheet 1 is viewed in cross section, the void area ratio in an end region 1A extending from one of the left and right ends of the joining sheet 1 to 300 μm inward is S １Ａ , the void area ratio in the central region 1B other than the end region 1A is S １Ｂ Then, S １Ａ / S １Ｂ A conjugate characterized in that the value of is greater than 1.

3. A bonded body having a configuration in which an upper metal-containing member 2 and a lower metal-containing member 3 are bonded to the front and back of a bonding sheet 1, Each of the upper metal-containing member 2 and the lower metal-containing member 3 has a metal portion on a joining surface with the joining sheet 1, The bonding sheet 1 is a cured product of a thermosetting resin composition containing a thermosetting resin and an inorganic filler, The entire upper surface of the bonding sheet 1 is bonded to the upper metal-containing member 2, and the entire lower surface of the bonding sheet 1 is bonded to the lower metal-containing member 3. When the bonding sheet 1 is viewed in cross section, the average void size in an end region 1A extending from one of the left and right ends of the bonding sheet 1 to 300 μm inward is L １Ａ , the average void size in the central region 1B other than the end region 1A is L １Ｂ When this is done, L １Ａ / L １Ｂ A conjugate characterized in that the value of is greater than 2.

4. The joined body according to any one of claims 1 to 3, comprising a configuration in which a joining sheet 1 and an upper metal-containing member 2 are directly joined, and a joining sheet 1 and a lower metal-containing member 3 are directly joined.

5. The upper metal-containing member 2 has a sheet- or plate-shaped metal portion 21 having an exposed underside at the joining surface with the joining sheet 1, and the metal portion 21 is covered and sealed with resin 22, forming a joint body as described in any one of claims 1 to 3.

6. The joint body according to any one of claims 1 to 3, wherein the lower metal-containing member (3) has a flat or sheet-shaped metal body on a joint surface with the joint sheet (1).

7. 4. The joined body according to claim 1, wherein the joining sheet (1) has a thermal conductivity in a thickness direction of 10 W / m·K or more.

8. 4. The joined body according to claim 1, wherein the joining sheet (1) has a dielectric breakdown voltage of 5 kV or more.

9. 4. The joined body according to claim 1, wherein the metal portions of the upper metal-containing member and the lower metal-containing member are made of a material containing copper or aluminum.

10. The bonded body according to any one of claims 1 to 3, wherein the inorganic filler contained in the bonding sheet 1 includes boron nitride agglomerated particles.

11. 11. The joint of claim 10, wherein the boron nitride agglomerated particles have a house of cards structure.

12. The bonded body according to any one of claims 1 to 3, wherein the thermosetting resin contained in the bonding sheet 1 includes an epoxy resin.

13. The bonded body according to any one of claims 1 to 3, wherein the bonding sheet 1 has a thickness of 80 µm or more and 300 µm or less.

14. The bonding sheet is a cured product of a thermosetting resin composition containing a thermosetting resin and an inorganic filler, When the joining sheet 1 is viewed in cross section, the resin area ratio in the end region 1A from the left or right end to the inner 300 μm is P １Ａ , the resin area ratio in the central region 1B other than the end region 1A is P １Ｂ Then, P １Ａ / P １Ｂ The value of is greater than 1.10; When the joining sheet 1 is viewed in cross section, the void area ratio in the end region 1A extending from the left or right end to the inside by 300 μm is S １Ａ , the void area ratio in the central region 1B other than the end region 1A is S １Ｂ Then, S １Ａ / S １Ｂ The value of is greater than 1, and When the joining sheet 1 is viewed in cross section, the average void size in the end region 1A extending from the left or right end of the joining sheet 1 to the inside by 300 μm is L １Ａ , the average void size in the central region 1B other than the end region 1A is L １Ｂ When this is done, L １Ａ / L １Ｂ A bonding sheet characterized in that the value of is greater than 2.

15. A method for producing a bonded body according to any one of claims 1 to 3, comprising the steps of: A method for producing a joined body, comprising: placing a thermosetting sheet obtained by molding the thermosetting resin composition into a sheet shape on a lower metal-containing member (3); applying uniform pressure to bond the lower metal-containing member (3) and the thermosetting sheet together; and then placing an upper metal-containing member (2) on the thermosetting sheet; and applying uniform pressure to bond the thermosetting sheet and the upper metal-containing member (2).

16. The method for producing a joint body according to claim 15, wherein the thermosetting sheet is subjected to low-temperature aging in an environment of −50° C. or higher and 0° C. or lower before being placed on the lower metal-containing member 3.

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