Metal-ceramic bonded substrate and manufacturing method thereof

Abstract

To provide a metal-ceramic bonded substrate capable of sufficiently suppressing warpage even when a thermal history is applied, and a manufacturing method of the metal-ceramic bonded substrate.SOLUTION: In a metal-ceramic bonded substrate, a metal plate is bonded to one surface of a ceramic substrate and a metal base plate is bonded to the other surface, and the side surface of the metal base plate is bonded to the side surface of a plate-shaped reinforcing member made of metal higher in strength than the metal base plate.SELECTED DRAWING: Figure 1A

Description

[Technical field]

[0001] The present invention relates to a metal-ceramic bonding substrate and a manufacturing method thereof, and more particularly to a metal-ceramic bonding substrate in which a metal plate (metal circuit plate) for mounting electronic components is formed on one surface of a ceramic substrate and a metal base plate for heat dissipation is formed on the other surface, and a manufacturing method thereof. [Background technology]

[0002] Conventionally, in a metal-ceramic bonding substrate used as an insulating substrate for a power module, a metal circuit plate is bonded to one surface of a ceramic substrate, a heat dissipating metal base plate is bonded to the other surface, and a semiconductor chip or the like is mounted on the metal circuit plate. In order to dissipate heat from heat generating elements such as the semiconductor chip to the outside, a heat dissipating fin, a cooling jacket, or the like is attached to the back surface of the heat dissipating metal base plate by fastening with screws or bolts through through holes formed in the peripheral portion of the metal base plate.

[0003] As such a metal-ceramic bonding substrate, a metal circuit plate is directly bonded to one surface of a ceramic substrate and a heat dissipation member made of aluminum or an aluminum alloy is directly bonded to the other surface, and a heat sink having an internal space is attached by screwing a lid onto the heat dissipation member through a screw hole (through hole) formed on the periphery of the heat dissipation member (see, for example, Patent Document 1).

[0004] However, in the metal-ceramic bonding substrate of Patent Document 1, the heat dissipation member is directly bonded to the ceramic substrate by pouring molten aluminum or aluminum alloy into a mold with the ceramic substrate placed inside and then solidifying it, and since the strength of the heat dissipation member is not high, there is a risk that the periphery of the screw hole formed in the heat dissipation member may cave in, or that the screw may come loose when used as an insulating substrate for a power module in a vehicle or industrial machine. Furthermore, if the composition of the additive metal in the aluminum alloy is adjusted to increase the strength of the heat dissipation member, the thermal conductivity of the heat dissipation member may decrease, resulting in a decrease in heat dissipation performance, and when a heat cycle is applied to the metal-ceramic bonding substrate, cracks may occur in the ceramic substrate, and the reliability of the metal-ceramic bonding substrate may decrease.

[0005] Furthermore, in order to prevent the occurrence of cracks around the edges of the through holes used for screwing the substrate, it has been proposed to fit a pipe member into the through hole connecting the two main surfaces of the substrate made of a composite of graphite and metal, and to join the interface between the pipe member and the substrate with a solder material or the like in order to improve adhesion and heat dissipation between the pipe member and the substrate (see, for example, Patent Document 2).

[0006] However, in the substrate of Patent Document 2, simply fitting the pipe member into the through hole does not The material was not fixed sufficiently, so in order to improve the adhesion between the pipe and the substrate, When joining the interface between the pipe member and the substrate with a brazing material or the like, it is not easy to form the brazing material or the like on the outer surface of the pipe member or the inner surface of the through hole, and it is difficult to sufficiently improve adhesion by joining the pipe member and the substrate with the brazing material or the like.

[0007] In order to solve these problems, it has been proposed that in a metal-ceramic bonding substrate in which a metal plate is bonded to one side of a ceramic substrate and a metal base plate is bonded to the other side, the outer peripheral surface of a ring-shaped member made of a metal having a strength greater than that of the metal base plate is directly bonded to the inner peripheral surface of a through hole (for screwing) formed so as to penetrate from one side of the metal base plate to the other side, thereby suppressing deformation of the screwing portion of the metal base plate bonded to the ceramic substrate and improving the reliability of the metal-ceramic bonding substrate (see, for example, Patent Document 3).

[0008] Such a metal-ceramic bonded substrate can be produced by placing a ceramic substrate and an annular member made of a metal having a higher melting point and strength than a metal base plate in a mold at a distance from each other, pouring molten metal into the mold so that it contacts both sides of the ceramic substrate and the outer peripheral surface of the annular member, and then cooling and solidifying the metal plate to form a metal plate that is directly bonded to one side of the ceramic substrate and a metal base plate that is directly bonded to the other side of the ceramic substrate, and directly bonding the outer peripheral surface of the annular member to the inner peripheral surface of a through hole that penetrates from one side of the metal base plate to the other side. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] JP 2007-294891 A [Patent Document 2] JP 2005-136369 A [Patent Document 3] JP 2013-207133 A Summary of the Invention [Problem to be solved by the invention]

[0010] However, in the metal-ceramic bonding substrate of Patent Document 3, although deformation of the screw fastening portion is suppressed, when the metal-ceramic bonding substrate is subjected to a thermal history during the manufacture or use of a power module, it has been found that, in particular, a large warp occurs in the metal base plate, causing malfunctions in the manufacturing process of the power module, and in power modules in which heat dissipation fins, a cooling jacket, etc. are fastened by bolts or the like to the back surface of the heat-dissipating metal base plate of the metal-ceramic bonding substrate via through holes formed in the peripheral portion of the metal base plate, the fastening force of the bolts may decrease, resulting in reduced reliability.

[0011] In view of the above-mentioned problems in the conventional art, the present invention aims to provide a metal-ceramic bonding substrate that can suppress the occurrence of cracks in the ceramic substrate even when subjected to a thermal history, and can sufficiently suppress warping, and to provide a method for manufacturing the metal-ceramic bonding substrate. [Means for solving the problem]

[0012] The metal-ceramic bonding substrate of the present invention is a metal-ceramic bonding substrate in which a metal plate is bonded to one surface of a ceramic substrate and a metal base plate is bonded to the other surface of the ceramic substrate, and the side of a plate-shaped reinforcing member made of a metal having a strength higher than that of the metal base plate is bonded to the side of the metal base plate. The reinforcing member is formed in an area other than the ceramic substrate when viewed from above, and the reinforcing member has a through hole. It is characterized by:

[0013] It is preferable that the through hole extends in a direction perpendicular to a main surface of the reinforcing member.

[0014] It is preferable that the metal base plate is directly bonded to the ceramic substrate, and it is preferable that the metal plate is directly bonded to the ceramic substrate.

[0015] The metal base plate is preferably made of aluminum or an aluminum alloy, the reinforcing member is preferably made of carbon steel or stainless steel, and the reinforcing member is preferably a material having a tensile strength of 150 MPa or more.

[0016] The metal plate is preferably made of aluminum or an aluminum alloy, and the metal plate is preferably made of aluminum containing 99.7% by mass or more of aluminum.

[0017] It is preferable that aluminum or an aluminum alloy is bonded to a main surface of the reinforcing member, and it is preferable that a bonding layer made of an alloy is formed at the bonding interface between the reinforcing member and the metal base plate.

[0018] The reinforcing member is preferably rectangular, and may be shaped to surround the metal base plate.

[0019] The method for producing a metal-ceramic bonded substrate of the present invention includes a method for producing a metal-ceramic bonded substrate having a metal plate bonded to one surface of a ceramic substrate and a metal base plate bonded to the other surface thereof, the method comprising the steps of: arranging a plate-shaped reinforcing member made of a metal having a melting point and strength higher than that of the metal base plate and the ceramic substrate at a distance from each other in a mold; pouring molten metal into the mold so that the molten metal contacts both surfaces of the ceramic substrate and the side surface of the reinforcing member; and cooling and solidifying the molten metal to form a metal plate that is directly bonded to one surface of the ceramic substrate; forming a metal base plate that is directly bonded to the other surface of the ceramic substrate; and bonding the side surface of the reinforcing member to the side surface of the metal base plate. The reinforcing member is formed in an area other than the ceramic substrate when viewed from above, and the reinforcing member has a through hole. It is characterized by:

[0020] It is preferable that the through hole extends in a direction perpendicular to a main surface of the reinforcing member.

[0021] The molten metal for forming the metal base plate is preferably made of aluminum or an aluminum alloy, the reinforcing member is preferably made of carbon steel or stainless steel, and the reinforcing member preferably has a tensile strength of 150 MPa or more.

[0022] It is preferable that the molten metal for forming the metal plate is made of aluminum or an aluminum alloy, and it is preferable that the molten metal for forming the metal plate is made of aluminum containing 99.7% or more by mass of aluminum. When pouring the molten metal, it is preferable that the molten metal is poured so as to come into contact with the main surface of the reinforcing member, and then cooled and solidified, thereby directly joining the aluminum or aluminum alloy to the main surface of the reinforcing member.

[0023] It is preferable to form a bonding layer made of an alloy at the bonding interface between the reinforcing member and the metal base plate.

[0024] The reinforcing member is preferably rectangular, and may be shaped to surround the metal base plate. Effect of the Invention

[0025] The present invention can provide a metal / ceramic bonding substrate that can suppress the occurrence of cracks in the ceramic substrate even when subjected to a thermal history, and can sufficiently suppress warping, and a method for manufacturing the same. [Brief description of the drawings]

[0026] [Figure 1A] 1 is a plan view (top view) showing an embodiment of a metal / ceramic bonding substrate according to the present invention. [Figure 1B] 1B is a cross-sectional view of the metal-ceramic bonding substrate of FIG. 1A taken along line AA. [Figure 1C] 1B is a cross-sectional view of the metal-ceramic bonding substrate of FIG. 1A taken along line BB. [Figure 1D] 1B is a cross-sectional view of the metal-ceramic bonding substrate of FIG. 1A taken along line CC. [Figure 1E] 1B is a rear view of the metal-ceramic bonding substrate of FIG. 1A. [Figure 2A] 2 is a plan view (top view) of a lower mold (mold), which is a mold component used to produce the metal / ceramic bonding substrate shown in FIG. 1. FIG. [Figure 2B]2B is a cross-sectional view of the lower mold (casting mold) taken along line AA in FIG. 2A. [Figure 2C] 2B is a cross-sectional view of the lower mold (casting mold) of FIG. 2A along line BB. [Figure 2D] 2B is a cross-sectional view of the lower mold (casting mold) of FIG. 2A taken along line CC. [Figure 2E] FIG. 2B is a rear view of the lower mold (casting mold) of FIG. 2A. [Figure 2F] 2B is a cross-sectional view of the lower mold (casting mold) of FIG. 2A taken along line DD. [Figure 2G] 2B is a cross-sectional view of the lower mold (casting mold) of FIG. 2A taken along line EE. [Figure 2H] 2B is a cross-sectional view of the lower mold (casting mold) of FIG. 2A taken along the line FF. [Figure 3A] FIG. 3 is a plan view (top view) of a middle mold constituting the lower mold (casting mold) of FIG. 2. [Figure 3B] FIG. 3B is a cross-sectional view of the middle portion of FIG. 3A taken along line AA. [Figure 3C] FIG. 3B is a cross-sectional view of the medium-sized line BB in FIG. 3A. [Figure 3D] FIG. 3B is a cross-sectional view of the middle size taken along the line CC in FIG. 3A. [Figure 3E] FIG. 3B is a rear view of the medium size of FIG. 3A. [Figure 4] FIG. 3 is a plan view (top view) of an outer mold constituting the lower mold (casting mold) of FIG. 2. [Figure 5A] 2 is a plan view (bottom view) of an upper mold (mold), which is a mold component used for producing the metal / ceramic bonding substrate shown in FIG. 1. FIG. [Figure 5B] 2 is a plan view (top view) of an upper mold (mold), which is a mold component used to produce the metal / ceramic bonding substrate shown in FIG. 1. FIG. [Figure 6A] 6 is a cross-sectional view corresponding to line AA when the upper mold in FIG. 5 is disposed on the lower mold in FIG. 2. [Figure 6B] 6 is a cross-sectional view corresponding to line BB when the upper mold in FIG. 5 is disposed on the lower mold in FIG. 2. [Figure 6C] 6 is a cross-sectional view corresponding to line CC when the upper mold in FIG. 5 is placed on the lower mold in FIG. 2. [Figure 6D] 6 is a cross-sectional view corresponding to the line DD when the upper mold in FIG. 5 is disposed on the lower mold in FIG. 2. [Figure 6E] 6 is a cross-sectional view corresponding to line EE when the upper mold in FIG. 5 is placed on the lower mold in FIG. 2. [Figure 6F] 6 is a cross-sectional view corresponding to the line FF when the upper mold in FIG. 5 is placed on the lower mold in FIG. 2. [Figure 7A] FIG. 4 is a plan view showing a second embodiment of a metal / ceramic bonding substrate of the present invention. [Figure 7B] 7B is a cross-sectional view of the metal-ceramic bonding substrate taken along line AA in FIG. 7A. [Figure 7C] 7B is a cross-sectional view of the metal-ceramic bonding substrate of FIG. 7A taken along line BB. [Figure 7D] 7B is a cross-sectional view of the metal-ceramic bonding substrate taken along line CC in FIG. 7A. [Figure 7E] FIG. 7B is a rear view of the metal-ceramic bonding substrate of FIG. 7A. [Figure 8A] FIG. 4 is a plan view showing a metal / ceramic bonding substrate according to a third embodiment of the present invention. [Figure 8B] 8B is a cross-sectional view of the metal-ceramic bonding substrate taken along line AA in FIG. 8A. [Figure 8C] 8B is a cross-sectional view of the metal-ceramic bonding substrate of FIG. 8A taken along line BB. [Figure 8D] 8B is a cross-sectional view of the metal-ceramic bonding substrate of FIG. 8A taken along line CC. [Figure 8E] 8B is a rear view of the metal-ceramic bonding substrate of FIG. 8A. FIG. [Figure 9A] FIG. 11 is a plan view showing a metal / ceramic bonding substrate according to a fourth embodiment of the present invention. [Figure 9B] 9B is a cross-sectional view of the metal-ceramic bonding substrate taken along line AA in FIG. 9A. [Figure 9C] 9B is a cross-sectional view of the metal-ceramic bonding substrate of FIG. 9A taken along line BB. [Figure 9D] 9B is a cross-sectional view of the metal-ceramic bonding substrate taken along line CC in FIG. 9A. [Figure 9E] FIG. 9B is a rear view of the metal-ceramic bonding substrate of FIG. 9A. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] <Metal-ceramic bonded substrate> The metal-ceramic bonding substrate of the present invention is a metal-ceramic bonding substrate having a metal plate bonded to one surface of a ceramic substrate and a metal base plate bonded to the other surface, characterized in that the side surface of the metal base plate is bonded to the side surface of a plate-shaped reinforcing member made of a metal having strength greater than that of the metal base plate.

[0028] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the metal / ceramic bonding substrate according to the present invention will be described in detail with reference to the drawings.

[0029] (First embodiment) As shown in Figures 1A to 1E, the embodiment of the metal-ceramic bonding substrate 1 according to the present invention includes an electrically insulating ceramic substrate 10 having a substantially rectangular planar shape, a metal base plate 12 having a substantially rectangular planar shape bonded to the entire surface of the side (part of) and the other side (the back surface (lower surface) in the illustrated embodiment) of the ceramic substrate 10, and one or more (three in the illustrated embodiment) metal plates 14 for circuit patterns directly bonded to one side (the upper surface in the illustrated embodiment) of the ceramic substrate 10, and the side (end) of the metal base plate 12 is bonded to (the outer side of the metal base plate 12) a side of a plate-shaped reinforcing member 16 made of a metal having a higher strength (tensile strength) than the flat metal base plate 12 having a substantially rectangular planar shape and a substantially uniform thickness. Figures 1A to 1E show a state in which the side of one reinforcing member 16 is bonded to each of the right side and left side (both end faces) of the metal base plate 12. By bonding the reinforcing members 16 to the side surfaces of the metal base plate 12, it is possible to provide a metal / ceramic bonding substrate that can adequately suppress warping even when subjected to a thermal history.

[0030] The reinforcing member 16 preferably has through holes 18 extending in a direction substantially perpendicular to the main surface (plate surface) of the reinforcing member 16. In Fig. 1A, two through holes 18 are shown formed at the end of one reinforcing member 16.

[0031] When manufacturing a semiconductor device such as a power module, the through holes 18 of the reinforcing member 16 can be used as fastening holes for fastening to other members with screws or bolts. For example, a heat dissipation member (not shown) such as a heat dissipation fin or a water-cooling jacket, or a case (not shown) that surrounds the metal plate 14 for the circuit pattern and the semiconductor mounted thereon can be attached via the through holes 18 with screws, bolts, etc. As described above, in the present invention, by joining the reinforcing member 16 to the side of the metal base plate 12, warping is sufficiently suppressed even when thermal history is applied, and since the part that is fastened with screws or bolts is the reinforcing member 16, deformation of the screw-fastened part (reinforcing member 16) is sufficiently small even after performing a heat cycle test, for example, and loosening of the screws (or bolts) (reduction in tightening torque) can be sufficiently suppressed. Furthermore, as shown in Figures 1B to 1D, the back surface of the reinforcing member 16 (the surface opposite to the metal plate 14 for the circuit pattern) and the back surface of the metal base plate 12 (the surface opposite to the metal plate 14 for the circuit pattern) are substantially flush with each other, and the metal base plate 12 joined to the reinforcing member 16 as an integrated unit can be assembled in a state of good contact with the heat dissipation member, etc., without any gaps.

[0032] The reinforcing member 16 is preferably made of a material having a strength greater than that of the metal base plate 12, for example, a tensile strength of 150 MPa or more, or even 200 MPa or more, and is preferably made of carbon steel or stainless steel.

[0033] The metal base plate 12 is preferably directly bonded to the ceramic substrate 10, and the metal plate 14 for the circuit pattern is preferably bonded to the ceramic substrate 10. The metal base plate 12 is preferably made of aluminum or an aluminum alloy, and the metal plate 14 for the circuit pattern is preferably made of aluminum or an aluminum alloy. The metal base plate 12 is preferably made of a material having a tensile strength of, for example, about 70 to 130 MPa (or preferably 75 to 120 MPa), and is preferably made of aluminum or an aluminum alloy.

[0034] Since the metal plate 14 for the circuit pattern will be mounted with chip components such as semiconductor elements, a metal with excellent electrical conductivity and thermal conductivity is preferable. If the metal is aluminum, it is preferable that the metal be aluminum or an aluminum alloy containing 99.7% by mass or more of aluminum, and more preferably 99.9% by mass or more of aluminum.

[0035] Since it is desirable for the metal base plate 12 to have a certain degree of hardness as a structural member as well as thermal conductivity, it is preferable for the metal base plate 12 to have a greater hardness than the metal plate 14 for the circuits.

[0036] The ceramic substrate 10 has a function of maintaining insulation between the metal plates 14 when there are multiple metal plates 14 for circuit patterns, and between the metal plates 14 for circuit patterns and the metal base plate 12. The main component of the ceramic substrate 10 (85 mass % or more in terms of composition) is preferably one or more selected from alumina, aluminum nitride, silicon nitride, and silicon carbide.

[0037] In addition, the reinforcing members 16 are preferably formed in regions other than the bonding region between the ceramic substrate 10 and the metal base plate 12 when viewed in a plan view from a direction perpendicular to (above) the main surface of the ceramic substrate 10 as shown in Fig. 1. It is preferable not to form the reinforcing members 16 in the bonding region between the ceramic substrate 10 and the metal base plate 12 in order to ensure heat dissipation.

[0038] Furthermore, when a reinforcing member 16 made of carbon steel is used, it is preferable that an alloy layer (bonding layer, not shown) of Fe and Al having a thickness of, for example, several hundred μm or less is formed at the bonding interface between the reinforcing member 16 and the metal base plate 12 made of aluminum or an aluminum alloy, so that the reinforcing member 16 and the metal base plate 12 are firmly bonded together. Furthermore, the metal base plate 12 may have an alloy structure in which Fe diffuses from the alloy layer toward the metal base plate 12 side, and an intermetallic compound of Fe and Al is formed (dispersed) in the parent phase of Al. The diffusion of Fe into Al and the formation of the intermetallic compound improve the strength of the metal base plate 12.

[0039] <Manufacturing method> The method for manufacturing a metal-ceramic bonded substrate of the present invention includes a method for manufacturing a metal-ceramic bonded substrate in which a metal plate is bonded to one surface of a ceramic substrate and a metal base plate is bonded to the other surface thereof, and the method comprises arranging a plate-shaped reinforcing member made of a metal having a melting point and strength higher than that of the metal base plate and the ceramic substrate at a distance from each other in a mold, pouring molten metal into the mold so that it contacts both surfaces of the ceramic substrate and the side surface of the reinforcing member, and then cooling and solidifying the molten metal, thereby forming a metal plate and bonding it directly to one surface of the ceramic substrate, and forming a metal base plate and bonding it directly to the other surface of the ceramic substrate, and bonding the side surface of the reinforcing member to the side surface of the metal base plate.

[0040] Hereinafter, as an example of an embodiment of the method for producing a metal-ceramic bonding substrate of the present invention, a method for producing a metal-ceramic bonding substrate by bonding a ceramic substrate, a metal base plate, a metal plate for a circuit pattern, and a reinforcing member by a molten metal bonding method will be described with reference to the drawings.

[0041] A mold used when manufacturing the metal / ceramic bonding substrate 1 of the first embodiment shown in FIGS. 1A to 1E by a molten metal bonding method will be described.

[0042] First, the lower mold (mold), which is a mold component, will be described with reference to Figs. 2A to 2H. The lower mold (mold) illustrated here has a structure in which a middle mold (mold) and an outer mold (mold) are fitted together. Fig. 2A is a plan view (top view) of the middle mold 20 and the outer mold 40 constituting the lower mold 100 seen from above, Fig. 2B is a cross-sectional view taken along line AA in Fig. 2A, Fig. 2C is a cross-sectional view taken along line BB in Fig. 2A, Fig. 2D is a cross-sectional view taken along line CC in Fig. 2A, Fig. 2E is a rear view of Fig. 2A, Fig. 2F is a cross-sectional view taken along line DD in Fig. 2A, Fig. 2G is a cross-sectional view taken along line EE in Fig. 2A, and Fig. 2H is a cross-sectional view taken along line FF in Fig. 2A. For convenience, the cross-sectional views show the state in which the ceramic substrate 10 is arranged by dotted lines. The portion shown by dotted lines where the ceramic substrate 10 is arranged is a ceramic substrate accommodation portion in the mold.

[0043] On the surface of the middle mold 20, a ceramic substrate support portion 21, which is a convex portion that comes into contact with the insulating ceramic substrate 10 during casting, a circuit metal plate forming portion 22, which is a concave portion that corresponds to the metal plate 14 for the circuit pattern, a metal base plate forming portion 23, which is a concave portion (located on the lower surface of the ceramic substrate accommodating portion) that corresponds to the metal base plate 12, and a reinforcing member accommodating portion 24, which is a concave portion that accommodates the reinforcing member 16, are formed, and a convex portion 25 that corresponds to the through hole 18 of the reinforcing member 16 is formed in the reinforcing member accommodating portion 24. The reinforcing member accommodating portion 24 is formed integrally with the metal base plate forming portion 23 adjacent to the metal base plate forming portion 23. In the middle mold 20, the portion where the reinforcing member 16 is disposed is referred to as the "reinforcing member accommodating portion 24" for convenience. Also, the portion where the molten metal is poured to form the metal base plate 12 is referred to as the "metal base plate forming portion 23" for convenience.

[0044] The ceramic substrate supporting portion 21 is formed so as to surround the periphery (side surface) of the ceramic substrate 10, and a step having an approximately L-shaped cross section is provided at the outer periphery of the ceramic substrate supporting portion 21 so as to abut against the peripheral portion of one surface (the surface on the circuit pattern side) of the ceramic substrate 10 to support the ceramic substrate 10 at a predetermined position, thereby forming a ceramic substrate accommodating portion, which is a space for accommodating the ceramic substrate. The ceramic substrate support portion 21 is preferable because it has an L-shaped cross section, which can prevent the ceramic substrate 10 from shifting from its predetermined position when the molten aluminum or aluminum alloy is poured into the mold after the ceramic substrate 10 is placed in the ceramic substrate accommodation portion. Therefore, it is desirable that the tip (upper end) of the ceramic substrate support part 21, which has an L-shaped cross section, is at the same height as or lower than the upper surface (surface on the metal base plate side) of the ceramic substrate 10 when the ceramic substrate 10 is placed. However, if it is too low, that is, if it is at the same height as or lower than one surface (surface on the circuit pattern side) of the ceramic substrate, there is a high possibility that the position of the ceramic substrate 10 will be misaligned. Therefore, it is desirable that the tip of the ceramic substrate support part 21 is at a height from approximately half the thickness of the ceramic substrate 10 to a height equivalent to the thickness of the ceramic substrate 10 from one surface (surface on the circuit pattern side, lower surface) of the ceramic substrate 10 when the ceramic substrate 10 is placed on the ceramic substrate support part 21. In addition, when the tip of the ceramic substrate supporting portion 21 is at the same level as or higher than the top surface of the ceramic substrate 10, the metal base plate 12 will not be joined to the side of the ceramic substrate 10 (however, in practice, the metal base plate may be joined to the side of the ceramic substrate 10 so that there is some play (gap) between the side of the ceramic substrate 10 and the ceramic substrate supporting portion 21 to make it easier to position it). One or more (three in the illustrated embodiment) recesses (metal plate forming portions) 22 for forming a metal plate 14 for a circuit pattern are formed in the approximate center of the upper surface (the surface that abuts against one surface of the ceramic substrate) of this ceramic substrate supporting portion 21. This metal plate forming portion 22 is separated from the metal base plate forming portion 23 via the ceramic substrate supporting portion 21, so as to ensure insulation between the metal base plate 12 and the metal plate 14 when the ceramic substrate 10 is arranged.

[0045] A recessed runner 26 for molten metal is formed on the surface adjacent to the metal base plate forming section 23 of the middle mold 20, and a through-hole 27 for pouring molten metal (four through-holes are shown in Figure 2A) is formed on the surface (bottom surface) of the metal plate forming section 22 for the circuit pattern of the middle mold 20.

[0046] FIG. 3A is a schematic plan view (top view) of the middle mold 20 constituting the lower mold in FIG. FIG. 4 is a schematic plan view (top view) of the outer mold 40 constituting the lower mold 100 in FIG. 2.

[0047] The outer mold 40 has a protrusion 41 that fits into the space of the molten metal reservoir of an upper mold 200 (FIG. 5) which is a mold component that is combined with the outer mold 40 during casting, and the molten metal is poured onto the upper surface of the protrusion 41 during casting. A molten metal inlet 43 and a groove-shaped runner 44 are formed on the surface (convex portion 41) of the outer mold 40 to supply molten metal to the metal plate forming section 22 for circuits. The molten metal pouring hole 27 of the metal plate forming section 22 for circuits of the inner mold 20 passes linearly through the plate thickness of the inner mold 20, and its through hole is connected to the vicinity of the tip of the groove of the runner 44 of the branched outer mold.

[0048] During casting, molten metal is poured onto the upper surface of the convex portion 41, and the molten metal is pressurized and fed from the molten metal inlet 43 to the runner 44. Therefore, in Figures 2A, 3A, and 4A, the upper side is the high temperature side of the temperature gradient, and the lower side is the low temperature side of the temperature gradient. In addition, the runner 26 for supplying molten metal to the metal base plate forming section 23 is a separate route from the runner 44 for supplying molten metal to the metal plate forming section 22 for the circuit, and the molten metal is supplied to the runner 26 from the molten metal inlet 42.

[0049] 5A and 5B are schematic diagrams showing the structure (plan view) of an upper mold 200, which is a mold component for producing a cast product of the metal-ceramic bonding substrate 1 shown in Fig. 1, and is used in combination with a lower mold. Fig. 5A is a bottom view (the side that covers the lower mold), and Fig. 5B is a top view (the side that becomes the upper side when it is covered with the lower mold). The upper mold 200 has a molten metal reservoir 201 that receives the molten metal supplied to the mold.

[0050] The molten metal reservoir 201 is a space penetrating the body of the upper mold 200, and during casting, the molten metal is introduced from a supply port 204, which is an upper opening (of the molten metal reservoir 201) of the upper mold 200. On the surface of the lower surface of the upper mold 200 shown in FIG. 5A, a metal base plate forming portion 202, which is a recess corresponding to the metal base plate 12, and a reinforcing member accommodating portion 203, which is a recess for accommodating the reinforcing member 16, are formed. The reinforcing member accommodating portion 203 is formed integrally with the metal base plate forming portion 202, adjacent to the metal base plate forming portion 202. Within the upper mold 200, the portion where the reinforcing member 16 is disposed is referred to as the "reinforcing member accommodating portion 203" for convenience. Also, the portion where the molten metal is poured to form the metal base plate 12 is referred to as the "metal base plate forming portion 202" for convenience.

[0051] The material of each of the mold components (lower mold 100, upper mold 200) is preferably a gas-permeable carbon material, for example.

[0052] Figures 6A to 6F show schematic examples of cross-sectional structures of a mold constructed by combining the lower mold 100 shown in Figure 2 and the upper mold 200 shown in Figure 5. Figure 6A corresponds to a cross section at the position indicated by line AA in Figure 2A, Figure 6B corresponds to a cross section at the position indicated by line BB in Figure 2A, Figure 6C corresponds to a cross section at the position indicated by line CC in Figure 2A, Figure 6D corresponds to a cross section at the position indicated by line DD in Figure 2A, Figure 6E corresponds to a cross section at the position indicated by line EE in Figure 2A, and Figure 6F corresponds to a cross section at the position indicated by line FF in Figure 2A.

[0053] Next, a manufacturing method for producing a metal / ceramic bonding substrate 1 by a molten metal bonding method using the above mold will be described. First, the middle mold 20 is accommodated in the middle mold accommodating portion 45 of the outer mold 40 of the lower mold 100, which is a mold component (resulting in the state shown in Figs. 2A to 2H). Next, the ceramic substrate 10 is placed on the ceramic substrate support portion 21 of the middle mold 20. By placing the ceramic substrate 10, a metal plate forming portion 22 is defined, which is a space between one side of the ceramic substrate 10 and the surface of the middle mold 20. The ceramic substrate support portion 21 also plays a role in positioning and preventing displacement so that the ceramic substrate 10 will not be displaced from a predetermined position by the molten metal when the molten metal is poured later.

[0054] The reinforcing member 16 is placed in the reinforcing member accommodating portion 24 of the middle mold 20. The reinforcing member 16 is plate-shaped and has a through hole 18 for screwing formed therein in advance, and the protrusion 25 of the middle mold 20 is positioned to correspond to the through hole 18 of the reinforcing member 16 and has an appropriate size to be fitted therein. By fitting the through hole 18 of the reinforcing member 16 into the protrusion 25, the reinforcing member 16 can be placed in a predetermined position in the reinforcing member accommodating portion 24. By arranging both in the middle mold 20 in this manner, the ceramic substrate 10 and the reinforcing member 16 are positioned apart from each other. For the sake of convenience, the cross-sectional views of the lower mold 100 shown in FIGS. 2B to 2D and 2F to 2H show a state in which the ceramic substrate 10 is arranged.

[0055] Next, by placing the upper mold 200 on the lower mold 100, a space is formed between the upper mold 200 and the lower mold 100 as shown in Figures 6A to 6F, and a metal base plate forming portion 202 and a metal base plate forming portion 23 (which define the shape of the metal base plate 12), and a reinforcing member accommodating portion 203 and a reinforcing member accommodating portion 24 are defined. Note that the reinforcing member accommodating portion 203 and the reinforcing member accommodating portion 24 become an integrated space. Similarly, the metal base plate forming portion 202 and the metal base plate forming portion 23 become an integrated space.

[0056] Next, the mold is inserted into a heating furnace (not shown) and heated in an atmosphere of a non-oxidizing gas such as nitrogen gas, and molten metal material melted in a melting furnace (not shown) is introduced into the molten metal reservoir 201 from the molten metal supply port 204. At this time, it is desirable that the molten metal to be poured has had the oxide film removed from the surface of the molten metal.

[0057] For example, it is preferable to pour the molten metal supplied from the melting furnace while performing an oxide film removal treatment. In the case of aluminum-based molten metal, for example, a method of pouring the molten metal while removing the oxide film on the surface of the molten metal by passing the molten metal through a very small nozzle is effective as the oxide film removal treatment.

[0058] The molten metal accumulated in the molten metal reservoir 201 in the mold is supplied from the molten metal inlet 42 formed by combining the upper mold 200 and the lower mold 100 to the runner 26, and from the molten metal inlet 43 to the runner 44, filling the metal base plate forming section 202, the metal base plate forming section 23, and the metal plate forming section 22 in the space within the mold. A portion of the molten metal of the metallic material introduced from the supply port 204 into the molten metal storage section 201 is fed from the molten metal inlet 42 to the runner 26, and fills the metal base plate forming section 202 and the metal base plate forming section 23. A portion of the remaining molten metal of the metallic material introduced from the supply port 204 into the molten metal storage section 201 is fed from the molten metal inlet 43 to the runner 44, and passes through the molten metal pouring holes 27 to fill each of the metal plate forming sections 22.

[0059] After the molten metal is filled (supplied) into the mold, it is desirable to directionally solidify the molten metal by forcibly extracting heat from the low-temperature side of the mold by contacting the outer wall of the mold at the low-temperature end (for example, the lower end of Figs. 6D to 6F) with, for example, a water-cooled copper block as a cooling device. In order to prevent casting defects such as shrinkage cavities, it is desirable to supply the molten metal from the runner 26 to the metal base plate forming section 202 and the metal base plate forming section 23, and from the runner 44 to the metal plate forming section 22 through the pouring hole 27 while applying pressure, for example, 5 to 200 kPa, using an inert gas such as nitrogen gas from the runner inlet 204, and to proceed with solidification while applying pressure.

[0060] In this way, molten metal is poured so that it contacts both sides of the ceramic substrate 10 in the mold and also the side of the reinforcing member 16, and then cooled and solidified, thereby directly bonding the metal base plate 12, which has an approximately rectangular planar shape and is bonded to the entire side and other side (rear side) of the ceramic substrate 10, directly bonding one or more (three in the illustrated embodiment) metal plates 14 for circuit patterns directly bonded to one side of the ceramic substrate 10, and bonding the side (inner surface) of the reinforcing member 16 to the side of the metal base plate 12.

[0061] The metal base plate 12 is preferably made of aluminum or an aluminum alloy, i.e., a molten metal of aluminum or an aluminum alloy is preferably poured into the mold. Also, the metal plate 14 is preferably made of aluminum or an aluminum alloy, i.e., a molten metal of aluminum or an aluminum alloy is preferably poured into the mold.

[0062] Since the metal plate 14 for the circuit will be mounted with chip components such as semiconductor elements, a metal with excellent electrical conductivity and thermal conductivity is preferable. In the case of aluminum, it is preferable to pour molten metal of aluminum or an aluminum alloy containing 99.7% by mass or more of aluminum, and more preferably 99.9% by mass or more of aluminum.

[0063] In addition, since it is desirable for the metal base plate 12 to have a certain degree of hardness (strength) as a constituent member as well as thermal conductivity, it is preferable for the metal base plate 12 to be harder than the circuit metal plate 14. In other words, the molten metal used for the metal base plate 12 and the molten metal used for the metal plate 14 may be of different compositions, and poured from separate runners provided in the mold so that the hardness of the metal base plate 12 is greater than that of the metal plate 14. When the aluminum or aluminum alloy compositions of the metal base plate 12 and the metal plate 14 are different, the molten metal supply port 204 and the molten metal reservoir 201 may be provided separately (not shown) for pouring molten metal.

[0064] In order to strengthen the bond between the reinforcing member 16 made of carbon steel or stainless steel and the metal base plate 12, it is preferable to form a bonding layer made of, for example, an alloy of Fe and Al at the bonding interface between the reinforcing member 16 and the metal base plate 12. Since Fe diffuses into Al and reduces electrical conductivity, it is preferable to provide separate runners 26 for supplying the molten metal to the metal base plate 12 and 44 for supplying the molten metal to the metal plate 14 for the circuit pattern. On the other hand, Fe diffused into Al is called FeAl 3 The hardness of the metal base plate 12 can be increased by forming a compound such as the above, thereby making it possible to obtain a hardness (strength) appropriate for the metal base plate.

[0065] The metal-ceramic bonded body obtained as described above is taken out by removing upper die 200 and dismantling the mold. The solidified portion of runner 26 connected to metal base plate 12 is cut and removed, and any protrusions on the surface of metal plate 14 remaining in molten metal pouring hole 27 are polished to produce a metal-ceramic bonded substrate 1 of a predetermined shape.

[0066] (Second embodiment) 7A to 7E are schematic diagrams of a metal-ceramic bonding substrate 2 according to another embodiment. In FIG. 2, a protrusion is provided on the surface of the reinforcing member accommodating portion 24 of the mold, and when the reinforcing member 16 is accommodated in the reinforcing member accommodating portion 24 and the reinforcing member accommodating portion 203, a gap is provided between the middle die 20 and the reinforcing member 16 and between the upper die 200 and the reinforcing member 16, and when the molten metal is poured, the molten metal is brought into contact with the main surface (plate surface) and the side surface (outer surface) of the reinforcing member 16 other than the joining surface, so that aluminum or aluminum alloy 30 may be bonded to the main surface and side surface of the reinforcing member 16. Note that the diameter of the protrusion 25 may be reduced to provide a gap between the reinforcing member 16 and the through hole 18, and aluminum or aluminum alloy may also be formed on the surface (inner surface) of the through hole 18 by pouring the molten metal.

[0067] If the reinforcing member 16 is carbon steel and the metal base plate 12 is aluminum or an aluminum alloy, there is a possibility that the reinforcing member 16 will corrode (galvanic corrosion) when the metal-ceramic substrate is incorporated into a semiconductor device such as a power module and used. Therefore, it is preferable to cover the entire surface of the reinforcing member 16 (the main surface and the side surface to which the metal base plate 12 is not joined, as well as the inner surface of the through hole 18) with aluminum or an aluminum alloy 30, that is, to join (form) aluminum or an aluminum alloy 30 to the surface of the reinforcing member 16.

[0068] (Third embodiment) 8A to 8E, a metal-ceramic bonding substrate 3 may be formed in which the metal base plate 12 is not bonded to the side surface of the ceramic substrate 10 but is directly bonded to the entire surface of the other surface. This can be produced by, for example, changing the shape of the mold so that the shape of the metal base plate 12 of the metal-ceramic bonding substrate in FIG.

[0069] (Fourth embodiment) 9A to 9E, a metal-ceramic bonding substrate 4 may be formed by bonding a reinforcing member 16 to surround the periphery of a metal base plate 12. This can be manufactured by changing the shape of the reinforcing member 16 and changing the shapes of the reinforcing member accommodating portions 203 and 24 of the mold so that the reinforcing member 16 of the metal-ceramic bonding substrate in FIG.

[0070] Although the embodiment of the present invention has been described above, the present invention is not limited to this, and any other embodiment that is in line with the gist of the present invention is included in the present invention. For example, pins or fins for heat dissipation may be formed integrally with the aluminum base plate on the rear surface of the aluminum base plate (the surface to which the ceramic substrate is not bonded). The pins or fins for heat dissipation formed integrally with the aluminum base plate can be produced by preparing a mold with a space inside that is approximately the same shape as the pins or fins, and then pouring aluminum alloy into the mold.

[0071] EXAMPLES Hereinafter, examples of a metal / ceramic bonding substrate and a method for producing the same according to the present invention will be described in detail. EXAMPLES

[0072] Example 1 An approximately rectangular aluminum nitride substrate (AlN substrate) measuring 70 mm long x 65 mm wide x 0.6 mm thick was prepared as the ceramic substrate 10, and an approximately rectangular SPCC (common steel) plate measuring 10 mm long x 80 mm wide x 2 mm thick (material with tensile strength of 270 MPa or more) was prepared as the reinforcing member 16. The reinforcing member 16 had through holes 18 with a diameter of 6 mm that penetrated the plate surface vertically at positions 8 mm from both ends in the width direction and 5 mm in the length direction. For convenience, the horizontal direction in FIG. 2A is represented as the length direction, and the vertical direction is represented as the width direction. Next, the ceramic substrate 10 was placed on the ceramic substrate supporting portion 21 of the middle mold 20 of the lower mold (mold) 100 similar to the mold component member shown in Figure 2, and the through hole 18 of the reinforcing member 16 was fitted into the convex portion 25 of the reinforcing member accommodating portion 24 of the lower mold 100, thereby accommodating the reinforcing member 16 in the reinforcing member accommodating portion 24. Next, upper die 200 was placed over lower die 100 as shown in Fig. 6. The mold was heated in a nitrogen atmosphere, and molten pure aluminum (containing 99.9% by mass or more of Al) was poured into the mold while removing the oxide film on the surface. The mold was then cooled to solidify the molten aluminum, thereby producing a metal-ceramic bonded body in which a metal base plate 12 (having an outer dimension of 80 mm in length and 80 mm in width) was integrally formed over the entire other surface of ceramic substrate 10, and three metal plates 14 made of aluminum for circuit patterns were formed on one surface of ceramic substrate 10, and reinforcing members 16 were directly bonded to both side surfaces of metal base plate 12. At this time, the thickness of the metal base plate bonded to the other surface of the ceramic substrate 10 was 0.47 mm, the thickness of the metal base plate in a region with a width of 0.2 mm on the outer periphery of the ceramic substrate 10 (the recess in the drawing, the portion that was the tip of the ceramic substrate support portion of the mold during casting) was 0.77 mm, and the thickness of the metal base plate in other regions (such as the portion bonded to the reinforcing member) was 2 mm. Also, the thickness of the metal plate for the circuit pattern bonded to one surface of the ceramic substrate was 0.93 mm. The tensile strength of the metal base plate is about 80 MPa, the thermal conductivity is 237 W / mK, and the electrical conductivity of the metal plate is 62% IACS. The tensile strength of the metal base plate is measured by cutting the metal base plate and using a test piece for measurement. Next, the metal-ceramic bonding body was removed from the mold, the aluminum portion formed to correspond to the runner 26 was cut, and the surface of the metal plate 14 for the circuit pattern was polished to produce the metal-ceramic bonding substrate 1.

[0073] Example 2 The thickness of the reinforcing member 16 was 3 mm, the thickness of the metal base plate 12 bonded to the other surface of the ceramic substrate 10 was 0.8 mm, the thickness of the metal base plate in a 0.2 mm wide region (recess in the drawing) on ​​the outer periphery of the ceramic substrate 10 was 1.1 mm, and the thickness of the metal base plate in other regions (such as the portion bonded to the reinforcing member) was 3 mm. A metal-ceramic bonded substrate was produced in the same manner as in Example 1, except that the thickness of the metal plate 14 for the circuit pattern bonded to one surface of the ceramic substrate was 1.6 mm.

[0074] Example 3 The thickness of the reinforcing member 16 was 4 mm, the thickness of the metal base plate 12 bonded to the other surface of the ceramic substrate 10 was 1.1 mm, the thickness of the metal base plate in a 0.2 mm wide region (recess in the drawing) on ​​the outer periphery of the ceramic substrate 10 was 1.45 mm, and the thickness of the metal base plate in other regions (such as the portion bonded to the reinforcing member) was 4 mm. A metal-ceramic bonded substrate was produced in the same manner as in Example 1, except that the thickness of the metal plate 14 for the circuit pattern bonded to one surface of the ceramic substrate was 2.3 mm.

[0075] Example 4 A metal / ceramic bonding substrate was produced in the same manner as in Example 2, except that the material of reinforcing member 16 was S45C (carbon steel for machine construction) (having a tensile strength of 570 MPa or more).

[0076] Example 5 A metal / ceramic bonding substrate was produced in the same manner as in Example 2, except that the material of reinforcing member 16 was SS400 (general structural rolled steel material) (having a tensile strength of 400 MPa or more).

[0077] Example 6 A metal / ceramic bonding substrate was produced in the same manner as in Example 2, except that the material of reinforcing member 16 was SUS303 (stainless steel) (having a tensile strength of 520 MPa or more).

[0078] Example 7 A metal / ceramic bonding substrate was produced in the same manner as in Example 2, except that the material of reinforcing member 16 was SUS304 (stainless steel) (having a tensile strength of 520 MPa or more).

[0079] Example 8 A metal / ceramic bonding substrate was produced in the same manner as in Example 2, except that the material of reinforcing member 16 was SUS316 (stainless steel) (having a tensile strength of 520 MPa or more).

[0080] Example 9 A metal / ceramic bonding substrate having the shape shown in FIG. 9 was produced in the same manner as in Example 2, except that reinforcing member 16 was formed in a (mouth-shaped) shape surrounding the outer periphery of metal base plate 12 with a width of 10 mm.

[0081] Example 10 A roughly rectangular reinforcing member 16 measuring 10 mm in length, 80 mm in width, and 2.4 mm in thickness was prepared, and three protrusions measuring 1 mm in diameter and 0.3 mm in height were provided in the reinforcing member accommodating section 24 to support one main surface (plate surface) of the reinforcing member 16 at a distance of 0.3 mm from the surface (bottom surface) and side of the intermediate mold 20, and a gap of 0.3 mm was provided between the other main surface (plate surface) of the reinforcing member 16 and the outer mold 40. A metal-ceramic bonding substrate in which 0.3 mm-thick aluminum was formed (bonded) (covered) on one main surface, the other main surface, and side of the reinforcing member 16 corresponding to Figure 7 was produced in the same manner as in Example 2, except that

[0082] Example 11 A roughly rectangular reinforcing member 16 measuring 10 mm in length, 80 mm in width, and 2.6 mm in thickness was prepared, and three protrusions measuring 1 mm in diameter and 0.2 mm in height were provided in the reinforcing member accommodating section 24 to support one main surface (plate surface) of the reinforcing member 16 at a distance of 0.2 mm from the surface (bottom surface) and side of the intermediate mold 20, and a gap of 0.2 mm was provided between the other main surface (plate surface) of the reinforcing member 16 and the outer mold 40. A metal-ceramic bonding substrate was produced in which 0.2 mm-thick aluminum was formed (bonded) (covered) on one main surface, the other main surface, and side of the reinforcing member 16 corresponding to Figure 7 in the same manner as in Example 2, except that

[0083] Example 12 A roughly rectangular reinforcing member 16 measuring 10 mm in length, 80 mm in width, and 2.0 mm in thickness was prepared, and three protrusions measuring 1 mm in diameter and 0.5 mm in height were provided in the reinforcing member accommodating section 24 to support one main surface (plate surface) of the reinforcing member 16 0.5 mm away from the surface (bottom surface) and side of the intermediate mold 20, and a gap of 0.5 mm was provided between the other main surface (plate surface) of the reinforcing member 16 and the outer mold 40. A metal-ceramic bonding substrate in which 0.5 mm-thick aluminum was formed (bonded) (covered) on one main surface, the other main surface, and side of the reinforcing member 16 corresponding to Figure 7 was produced in the same manner as in Example 2, except that

[0084] Example 13 A metal-ceramic bonding substrate was produced in the same manner as in Example 2, except that the reinforcing member 16 was 2.4 mm thick and had a (mouth-shaped) shape surrounding the outer periphery of the metal base plate 12 with a width of 10 mm, three protrusions with a diameter of 1 mm and a height of 0.3 mm were provided in the reinforcing member accommodating portion 24 to support one main surface (plate surface) of the reinforcing member 16 0.3 mm away from the surface (bottom surface) and side of the middle mold 20, and a gap of 0.3 mm was provided between the other main surface (plate surface) of the reinforcing member 16 and the outer mold 40. In this manner, a metal-ceramic bonding substrate was produced in which 0.3 mm thick aluminum was formed (bonded) (covered) on one main surface, the other main surface and side of the reinforcing member 16 corresponding to Figure 9.

[0085] Comparative Example 1 A metal / ceramic bonding substrate was produced in the same manner as in Example 2, except that the reinforcing member 16 was not placed in the mold, and molten pure aluminum was poured into the reinforcing member receiving portion 24 as well and allowed to solidify.

[0086] Comparative Example 2 A metal-ceramic bonding substrate was produced in the same manner as in Comparative Example 2, except that molten aluminum-magnesium alloy A5052 was poured and solidified. The tensile strength of the formed metal-base plate was about 200 MPa, the thermal conductivity was 137 W / (m / K), and the electrical conductivity was 35% IACS.

[0087] Comparative Example 3 Plate-shaped reinforcing member 16 was not placed in the mold, but instead, a pipe-shaped member made of SUS304 was placed surrounding protrusion 25. The pipe had a wall thickness of 1 mm and a height of 3 mm. A metal-ceramic bonding substrate was then produced in the same manner as in Example 2, except that molten aluminum was poured and solidified.

[0088] <Evaluation and Results> The examples and comparative examples were evaluated and compared with respect to joinability, screw fastening ability, warping of the metal base plate, heat dissipation, electrical conductivity, and corrosion resistance.

[0089] (zygosity) For the bonding interface between the reinforcing member and the metal base plate of the metal-ceramic bonding substrate (in Comparative Example 3, it was a pipe-shaped member and a metal base plate), the cross section of the bonding substrate was observed under a microscope to confirm the presence or absence of bonding defects at the bonding interface, as well as the presence and thickness of a bonding layer (Fe-Al alloy layer). As a result, no bonding defects were observed at the bonding interface in Examples 1 to 5, 9 to 13 and Comparative Examples 1 and 2, and the bonding was excellent. Although minute voids were observed at the bonding interface between the reinforcing member and the aluminum metal base plate in Examples 6 to 8, the bonding strength was sufficient and there was no problem in using the product. In Comparative Example 3, many voids were observed at the bonding interface between the pipe-shaped member and the metal base plate, and the bonding was judged to be poor. Observation of the bonding interfaces of Examples 2, 4, 5, and 9 to 13 confirmed that the bonding layer (alloy layer) was made of Fe and Al. The thickness of the bonding layer in Examples 2 and 9 to 13 was about 150 μm, that of Example 4 was about 50 μm, and that of Example 5 was about 100 μm. In addition, in Examples 10 to 13, aluminum is formed (joined) on the main surface (plate surface) and side surfaces of the reinforcing member, and it was confirmed that a bonding layer is formed between the aluminum on the main surface and side surfaces and the reinforcing member, improving the strength (hardness) of the aluminum on the surface of the fastening parts, etc.

[0090] (warp) When viewed in a plan view from a direction perpendicular to the main surface of the ceramic substrate, the height of the metal plate for the circuit pattern at the center of the metal-ceramic bonding substrate and the height of the metal base plate (designed to be the same height as the metal plate for the circuit pattern) at two corners (corner portions) diagonally located at the outer peripheral edge of the metal-ceramic bonding substrate were measured, and the difference between the height of the reference line passing through the two points and the metal plate for the circuit pattern at the center was taken as the warpage of the product. Warpage is considered positive when the height at the center is low, and (initial) warpage is preferably in the range of -0.3 to 0.3 mm. As a result, the warpage was in the range of −0.1 to 0.1 mm, which was good, in Examples 1 to 13 and Comparative Examples 1 and 3. In Comparative Example 2, it was about +0.5 mm. In addition, the warpage after heating the metal-ceramic bonding substrate to 300° C. was calculated by simulation using the finite element method. Products with a change in warpage after heating of 0.15 mm or less from the initial warpage were rated as excellent products (◎), those with a change in warpage between 0.15 mm and 0.20 mm or less were rated as good products (◯), those with a change in warpage between 0.20 mm and 0.25 mm or less were rated as defective products (△), and those with a change in warpage over 0.25 mm were rated as defective products (×). As a result, Examples 1 to 8, 10 to 12 and Comparative Example 2 were non-defective, Examples 9 and 13 were excellent, and Comparative Examples 1 and 3 were defective.

[0091] (fastening performance) A frame-shaped member made of stainless steel (SUS304) with external dimensions of 100 mm in length, 80 mm in width, and 10 mm in height, and a frame thickness of 10 mm, and further equipped with bolt fastening parts with through holes formed in the parts corresponding to the through holes in the metal base plate at the four corners, was prepared as a frame-shaped member equivalent to a water-cooled jacket (heat dissipation member).A frame-shaped member made of polyethylene with external dimensions of 100 mm in length, 80 mm in width, and 10 mm in height, and a frame thickness of 10 mm, and further equipped with bolt fastening parts with through holes formed in the parts corresponding to the through holes in the metal base plate at the four corners, was prepared as a frame-shaped member equivalent to a case member (housing) that surrounds a semiconductor or the like. For each of the metal-ceramic bonding substrates obtained in Examples 2, 10, 11, and 12 and Comparative Examples 1 and 2, a frame-shaped member corresponding to the water-cooling jacket was placed on the rear surface of the metal base plate, and a frame-shaped member corresponding to the case member was placed on the front surface of the metal base plate, and then these were fastened with bolts via the through holes of the frame-shaped members and the through holes of the metal base plate. A heat cycle test was conducted on the metal-ceramic bonded substrate in which these frame-shaped members were fastened with bolts, in which 500 cycles of heat cycles (one cycle was -40°C x 30 minutes → 25°C x 10 minutes → 150°C x 30 minutes → 25°C x 10 minutes) were applied. For evaluation, the tightening torque of the bolts was measured (actually) before (initial) and after the heat cycle test. Those in which the tightening torque after the heat cycle had decreased by 20% or less compared to before the heat cycle were rated as good. In addition, the ceramic substrate of the metal-ceramic bonded substrate after 500 cycles was checked for the presence or absence of cracks. As a result, in all of Examples 2, 10, 11, and 12, the tightening torque was maintained at 80% or more of the initial value even after 500 heat cycles were applied (torque drop of 20% or less). On the other hand, in Comparative Example 1, the tightening torque was 16% of the initial value after 500 heat cycles were applied (torque drop of 84%). Also, deformation of 50 to 100 μm was confirmed in the fastening portion. In addition, in Examples 1 to 13 and Comparative Examples 1 and 3, no cracks were observed in the ceramic substrate after 500 heat cycles, but in Comparative Example 2, cracks were observed in the ceramic substrate, and the reliability as a metal-ceramic bonding substrate was poor.

[0092] (heat dissipation, conductivity) The heat dissipation of the metal base plate was evaluated by thermal conductivity, and the electrical conductivity of the metal plate for the circuit pattern was evaluated by electrical conductivity. A thermal conductivity of 180 W / mK or more and an electrical conductivity of 50% IACS or more were considered good. In Examples 1 to 13 and Comparative Examples 1 and 3, both the thermal conductivity and the electrical conductivity were good. Comparative Example 2 had a thermal conductivity of 137 W / mK, which was low enough for a metal base plate (for heat dissipation) and had poor heat dissipation properties, and had an electrical conductivity of 35% IACS, which was too low for a metal plate for circuit patterns and was not suitable for use.

[0093] (Vickers hardness) The surface of the metal plate for circuit patterns and the surface of the metal base plate in the vicinity of the reinforcing member were measured for Vickers hardness in accordance with JIS-Z2244. Except for Comparative Example 2, the Vickers hardness HV of the surface of the metal plate for circuit pattern was in the range of 20 to 23. Also, except for Comparative Examples 1 and 2, the Vickers hardness HV of the surface of the metal base plate was in the range of 28 to 35. The Vickers hardness HV of the metal base plate of Comparative Example 1 was in the range of 20-23, and the Vickers hardness HV of the surface of the metal plate for the circuit pattern and the surface of the metal base plate of Comparative Example 2 was in the range of 45-48.

[0094] (corrosion resistant) After conducting a corrosion test in salt water, if corrosion of the reinforcing member or metal base plate (aluminum or aluminum alloy) was confirmed, it was deemed to have poor corrosion resistance. Note that even if the corrosion resistance is poor, it may not be a problem if the design is such that the corrosion can be dealt with by covering it with resin or the like when it is incorporated into a semiconductor device, but it is preferable for the corrosion resistance to be excellent. The above tests showed excellent corrosion resistance with no corrosion observed in Examples 10 to 13 and Comparative Examples 1 and 2. Rust and galvanic corrosion were observed in Examples 1 to 5 and 9, and galvanic corrosion was observed in Examples 6 to 8 and Comparative Example 3.

[0095] A summary of the evaluation results is shown in Table 1. [Table 1] [Industrial Applicability]

[0096] The present invention is applicable to metal / ceramic bonding substrates. [Explanation of symbols]

[0097] 1, 2, 3, 4 Metal-ceramic bonded substrate 10 Ceramic Substrate 12 Metal base plate 14 Metal plate 16 Reinforcement members 18 Through hole 20 medium size 21 Ceramic substrate support 22 Metal plate forming section 23 Metal base plate forming section 24 Reinforcement member storage section 25 Convex 26 Yudo 27 Pouring hole 30 Aluminum or aluminum alloy 40 External mold 41 Convex 42, 43 Molten metal inlet 44 Yudo 45 Medium storage area 100 Lower mold 200 upper mold 201 Molten metal storage section 202 Metal base plate forming section 203 Reinforcement member storage section 204 Hot water outlet

Claims

1. A metal plate is bonded to one side of the ceramic substrate, In a metal-ceramic bonding substrate having a metal base plate bonded to the other surface, A side of a plate-shaped reinforcing member made of a metal having a strength higher than that of the metal base plate is joined to a side of the metal base plate, The reinforcing member is formed in an area other than the ceramic substrate when viewed in a plan view, A metal / ceramic bonding substrate, characterized in that the reinforcing member has a through hole.

2. 2. The metal / ceramic bonding substrate according to claim 1, wherein said through holes extend in a direction perpendicular to a main surface of said reinforcing member.

3. 3. The metal / ceramic bonding substrate according to claim 1, wherein said metal base plate is directly bonded to said ceramic substrate.

4. 4. The metal / ceramic bonding substrate according to claim 1, wherein said metal plate is directly bonded to said ceramic substrate.

5. 5. The metal / ceramic bonding substrate according to claim 1, wherein said metal base plate is made of aluminum or an aluminum alloy.

6. 6. The metal / ceramic bonding substrate according to claim 1, wherein said reinforcing member is made of carbon steel or stainless steel.

7. 7. A metal / ceramic bonding substrate according to claim 1, wherein said reinforcing member is made of a material having a tensile strength of 150 MPa or more.

8. 8. The metal / ceramic bonding substrate according to claim 1, wherein said metal plate is made of aluminum or an aluminum alloy.

9. 9. The metal / ceramic bonding substrate according to claim 8, wherein the metal plate is made of aluminum containing 99.7 mass % or more of aluminum.

10. 10. The metal / ceramic bonding substrate according to claim 1, wherein aluminum or an aluminum alloy is bonded to a main surface of said reinforcing member.

11. 11. The metal / ceramic bonding substrate according to claim 1, wherein a bonding layer made of an alloy is formed at a bonding interface between said reinforcing member and said metal base plate.

12. 12. The metal / ceramic bonding substrate according to claim 1, wherein said reinforcing member is rectangular.

13. 12. The metal / ceramic bonding substrate according to claim 1, wherein the reinforcing member is shaped to surround the metal base plate.

14. A metal plate is bonded to one surface of the ceramic substrate, A method for manufacturing a metal-ceramic bonding substrate having a metal base plate bonded to the other surface of the substrate, comprising the steps of: A plate-shaped reinforcing member made of a metal having a higher melting point and strength than the metal base plate and a ceramic substrate are disposed in a mold at a distance from each other; Molten metal is poured into the mold so that it contacts both sides of the ceramic substrate and the side of the reinforcing member, and then cooled and solidified. A metal plate is formed and directly bonded to one surface of the ceramic substrate; forming a metal base plate and directly bonding it to the other surface of the ceramic substrate; A side surface of the reinforcing member is joined to a side surface of the metal base plate; A method for producing a metal / ceramic bonding substrate, wherein the reinforcing member is formed in an area other than the ceramic substrate when viewed from above, and the reinforcing member has a through hole.

15. 15. The method for producing a metal / ceramic bonding substrate according to claim 14, wherein the through holes extend in a direction perpendicular to a main surface of the reinforcing member.

16. 16. The method for producing a metal / ceramic bonding substrate according to claim 14, wherein the molten metal for forming the metal base plate is made of aluminum or an aluminum alloy.

17. 17. The method for producing a metal / ceramic bonding substrate according to claim 14, wherein the reinforcing member is made of carbon steel or stainless steel.

18. 18. The method for producing a metal / ceramic bonding substrate according to claim 14, wherein the reinforcing member has a tensile strength of 150 MPa or more.

19. 19. The method for producing a metal / ceramic bonding substrate according to claim 14, wherein the molten metal for forming the metal plate is made of aluminum or an aluminum alloy.

20. 20. The method for producing a metal / ceramic bonding substrate according to claim 19, wherein the molten metal for forming the metal plate is made of aluminum containing 99.7 mass % or more of aluminum.

21. The method for producing a metal-ceramic bonding substrate according to any one of claims 14 to 20, characterized in that, when pouring the molten metal, the molten metal is poured so as to contact the main surface of the reinforcing member, and then cooled and solidified, thereby bonding aluminum or an aluminum alloy to the main surface of the reinforcing member.

22. The method for producing a metal-ceramic bonding substrate according to any one of claims 14 to 21, characterized in that the reinforcing member is bonded to an area other than a bonding area between the ceramic substrate and the metal base plate when viewed in a plan view from a direction perpendicular to a main surface of the ceramic substrate.

23. 23. The method for producing a metal / ceramic bonding substrate according to claim 14, wherein a bonding layer made of an alloy is formed at a bonding interface between said reinforcing member and said metal base plate.

24. The method for producing a metal / ceramic bonding substrate according to any one of claims 14 to 23, wherein the reinforcing member is rectangular.

25. The method for producing a metal / ceramic bonding substrate according to any one of claims 14 to 23, wherein the reinforcing member is shaped to surround the metal base plate.

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