WO2022209024A1

WO2022209024A1 - Metal-ceramic bonded substrate and manufacturing method therefor

Info

Publication number: WO2022209024A1
Application number: PCT/JP2021/045174
Authority: WO
Inventors: 正昭肥後; 悟井手口
Original assignee: Ｄｏｗａメタルテック株式会社
Priority date: 2021-03-31
Filing date: 2021-12-08
Publication date: 2022-10-06
Also published as: JP2022157171A

Abstract

This 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, is characterized in that a side surface of a plate-shaped reinforcing member comprising a metal having a higher strength than that of the metal base plate is bonded to a side surface of the metal base plate. Thus, it is possible to provide a metal-ceramic bonded substrate and a manufacturing method therefor with which cracking of the ceramic substrate can be suppressed and warpage can be adequately suppressed even when a thermal history is applied.

Description

METAL-CERAMIC BONDING SUBSTRATE AND MANUFACTURING METHOD THEREOF

TECHNICAL FIELD The present invention relates to a metal-ceramic bonding substrate and a manufacturing method thereof, and in particular, a ceramic substrate having a metal plate (metal circuit board) for mounting electronic components formed on one side and a metal base plate for heat dissipation on the other side. and a method of manufacturing the same.

In conventional metal-ceramic bonded substrates used as insulating substrates for power modules, a metal circuit board is bonded to one side of the ceramic substrate, and a metal base plate for heat dissipation is bonded to the other side. A semiconductor chip is mounted on the In order to dissipate the heat from heat generating elements such as semiconductor chips to the outside, heat dissipating fins, cooling jackets, etc. are placed on the back side of the heat dissipating metal base plate through through holes formed in the peripheral edge of the metal base plate. It is attached by fastening with screws or bolts.

As such a metal-ceramic bonding substrate, a metal circuit board is directly bonded to one surface of a ceramic substrate, and a heat radiation member made of aluminum or an aluminum alloy is directly bonded to the other surface of the ceramic substrate. A metal-ceramic bonding substrate has been proposed in which a radiator having a space formed therein is attached by screwing a cover to a heat dissipation member through a screw hole (through hole) formed therein (for example, patent Reference 1).

However, in the metal-ceramic bonding substrate of Patent Document 1, a heat dissipating member is directly bonded to the ceramic substrate by pouring molten aluminum or an aluminum alloy into a mold in which the ceramic substrate is placed and then solidifying the molten metal. Since the strength of the heat dissipating member is not high, the peripheral edge of the screw hole formed in the heat dissipating member may be depressed, or the screws may loosen when used as an insulating substrate for power modules in vehicles, industrial machines, etc. In addition, if the components of the additive metals in the aluminum alloy are adjusted to increase the strength of the heat dissipating member, the thermal conductivity of the heat dissipating member may decrease and the heat dissipation performance may deteriorate. is added, there is a risk that the reliability of the metal-ceramic bonded substrate will be reduced, such as cracking occurring in the ceramic substrate.

In addition, in order to prevent the occurrence of cracks in the periphery of the through-hole for screwing the substrate, a pipe member is fitted into the through-hole connecting both main surfaces of the substrate made of a composite of graphite and metal. has been proposed, and in order to improve the adhesion and heat dissipation between the pipe member and the substrate, it has been proposed to join the interface between the pipe member and the substrate with a brazing material or the like (see, for example, Patent Document 2). .

However, in the substrate of Patent Document 2, it is not sufficient to fix the pipe member only by fitting the pipe member into the through hole. When joining the interface with brazing material, it is not easy to form brazing material on the outer peripheral surface of the pipe member or the inner peripheral surface of the through hole. Enough improvement is difficult.

In order to solve such a problem, 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 is provided. Bonded to the ceramic substrate by directly bonding the outer peripheral surface of an annular member made of metal having higher strength than the metal base plate to the inner peripheral surface of the through hole (for screwing) formed so as to penetrate the surface. It has been proposed to improve the reliability of a metal-ceramic bonded substrate by suppressing deformation of the screwed portion of the metal base plate (see, for example, Patent Document 3).

In such a metal-ceramic bonding substrate, an annular member made of a metal having a melting point and strength higher than those of a metal base plate and a ceramic substrate are arranged separately in a mold, and both surfaces of the ceramic substrate in the mold are in contact with each other. By pouring molten metal so as to contact the outer peripheral surface of the annular member and then cooling and solidifying it, a metal plate is formed and directly bonded to one surface of the ceramic substrate, and a metal base plate is formed to form the ceramics. It can be manufactured by bonding directly to the other surface of the substrate, and directly bonding the outer peripheral surface of the annular member to the inner peripheral surface of the through hole penetrating from one surface to the other surface of the metal base plate.

JP 2007-294891 A JP-A-2005-136369 JP 2013-207133 A

However, in the metal-ceramic bonding substrate of Patent Document 3, although the deformation of the screwed portion is suppressed, when the metal-ceramic bonding substrate is subjected to heat history during the manufacture of the power module and the use of the power module, In particular, the metal base plate may warp significantly, causing defects in the power module manufacturing process. It has been found that in power modules that are fastened with bolts or the like through through-holes formed in parts, there is a possibility that the fastening force of the bolts will be reduced and the reliability will be lowered.

Therefore, in view of such conventional problems, the present invention provides a metal-ceramic bonded substrate that can suppress the occurrence of cracks in the ceramic substrate even when a thermal history is applied and can sufficiently suppress warping. It is an object of the present invention to provide a metal-ceramic bonded substrate and a manufacturing method thereof.

The metal-ceramic bonded substrate of the present invention is 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, and a metal base is attached to a side surface of the metal base plate. The side surface of a plate-like reinforcing member made of metal having a higher strength than the plate is joined.

The reinforcing member preferably has a through hole, and the through hole preferably extends in a direction perpendicular to the main surface of the reinforcing member.

The metal base plate is preferably directly bonded to the ceramic substrate, and the metal plate is preferably directly bonded to the ceramic substrate.

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 made of a material having a tensile strength of 150 MPa or more.

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

It is preferable that aluminum or an aluminum alloy is bonded to the main surface of the reinforcing member, and the reinforcing member joins the ceramic substrate and the base plate when viewed in plan from a direction perpendicular to the main surface of the ceramic substrate. It is preferable that the joint layer is formed in a region other than the region, and that a joint layer made of an alloy is formed at the joint interface between the reinforcing member and the metal base plate.

The reinforcing member is preferably rectangular, and may have a shape surrounding the metal base plate.

The method for producing a metal-ceramic bonded substrate of the present invention is a method for producing 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 of the ceramic substrate, wherein the metal base plate A plate-shaped reinforcing member made of a metal having a higher melting point and higher strength and a ceramic substrate are arranged in the mold with a gap therebetween, and the metal is placed in contact with both sides of the ceramic substrate in the mold and the side surfaces of the reinforcing member. After pouring the molten metal, the metal plate is formed and directly bonded to one surface of the ceramic substrate by cooling and solidifying, and the metal base plate is formed and directly bonded to the other surface of the ceramic substrate. 1) joining the side surface of the reinforcing member to the side surface of the metal base plate;

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

The molten metal for forming the metal plate is preferably made of aluminum or an aluminum alloy, and the molten metal for forming the metal plate is preferably made of aluminum containing 99.7% by mass or more of aluminum. Preferably, when pouring the molten metal, the molten metal is poured so as to come into contact with the main surface of the reinforcing member and then cooled and solidified so that the main surface of the reinforcing member is coated with aluminum or an aluminum alloy. is preferably joined.

Preferably, the reinforcing member is bonded to a region other than the bonding region between the ceramic substrate and the base plate when viewed from above in a direction perpendicular to the main surface of the ceramic substrate, and the bonding between the reinforcing member and the metal base plate. It is preferable to form a bonding layer made of an alloy on the bonding interface.

The present invention can provide a metal-ceramic bonded substrate that can suppress the occurrence of cracks in the ceramic substrate and sufficiently suppress warping even when a thermal history is applied, and a method for manufacturing the same.

1 is a plan view (top view) showing an embodiment of a metal-ceramic bonding substrate according to the present invention; FIG. FIG. 1B is a cross-sectional view of the metal-ceramic bonding substrate of FIG. 1A taken along the line AA. FIG. 1B is a cross-sectional view of the metal-ceramic bonding substrate of FIG. 1A taken along the line BB. FIG. 1B is a cross-sectional view of the metal-ceramic bonding substrate of FIG. 1A taken along line CC. 1B is a rear view of the metal-ceramic bonding substrate of FIG. 1A; FIG. FIG. 2 is a plan view (top view) of a lower mold (mold), which is a mold component used for manufacturing the metal-ceramic bonded substrate shown in FIG. 1; FIG. 2B is a cross-sectional view of the lower mold (mold) of FIG. 2A taken along the line AA. FIG. 2B is a cross-sectional view along the line BB of the lower mold (mold) of FIG. 2A; FIG. 2B is a cross-sectional view taken along the line CC of the lower mold (mold) of FIG. 2A; 2B is a rear view of the lower mold (mold) of FIG. 2A; FIG. FIG. 2B is a cross-sectional view taken along line DD of the lower mold (mold) of FIG. 2A; FIG. 2B is a cross-sectional view taken along line EE of the lower mold (mold) of FIG. 2A; FIG. 2B is a cross-sectional view taken along line FF of the lower mold (mold) of FIG. 2A; Fig. 3 is a plan view (top view) of a middle mold that constitutes the lower mold (mold) of Fig. 2; FIG. 3B is a cross-sectional view of the medium size of FIG. 3A taken along the line AA. FIG. 3B is a cross-sectional view along the line BB of the medium size of FIG. 3A; FIG. 3B is a cross-sectional view of the middle size of FIG. 3A taken along the line CC. Figure 3B is a rear view of the medium of Figure 3A; 3 is a plan view (top view) of an outer mold that constitutes the lower mold (mold) of FIG. 2. FIG. FIG. 2 is a plan view (bottom view) of an upper mold (mold) that is a mold component used to manufacture the metal-ceramic bonded substrate shown in FIG. 1; FIG. 2 is a plan view (top view) of an upper mold (mold) that is a mold component used for manufacturing the metal-ceramic bonded substrate shown in FIG. 1; FIG. 6 is a cross-sectional view corresponding to line AA when the upper mold of FIG. 5 is placed on the lower mold of FIG. 2; 6 is a sectional view corresponding to line BB when the upper mold of FIG. 5 is arranged on the lower mold of FIG. 2; FIG. 6 is a cross-sectional view corresponding to the CC line when the upper mold of FIG. 5 is placed on the lower mold of FIG. 2; FIG. 6 is a sectional view corresponding to line DD when the upper mold of FIG. 5 is placed on the lower mold of FIG. 2; FIG. FIG. 6 is a cross-sectional view corresponding to line EE when the upper mold of FIG. 5 is placed on the lower mold of FIG. 2; 6 is a sectional view corresponding to line FF when the upper mold of FIG. 5 is placed on the lower mold of FIG. 2; FIG. FIG. 2 is a plan view showing a second embodiment of the metal-ceramic bonding substrate of the present invention; FIG. 7B is a cross-sectional view of the metal-ceramic bonding substrate of FIG. 7A taken along the line AA. FIG. 7B is a cross-sectional view of the metal-ceramic bonding substrate of FIG. 7A taken along the line BB. FIG. 7B is a cross-sectional view of the metal-ceramic bonding substrate of FIG. 7A taken along line CC. 7B is a rear view of the metal-ceramic bonding substrate of FIG. 7A. FIG. FIG. 5 is a plan view showing a third embodiment of the metal-ceramic bonding substrate of the present invention; FIG. 8B is a cross-sectional view of the metal-ceramic bonding substrate of FIG. 8A taken along the line AA. FIG. 8B is a cross-sectional view of the metal-ceramic bonding substrate of FIG. 8A taken along the line BB. FIG. 8B is a cross-sectional view of the metal-ceramic bonding substrate of FIG. 8A taken along the line CC. 8B is a rear view of the metal-ceramic bonding substrate of FIG. 8A. FIG. FIG. 5 is a plan view showing a fourth embodiment of the metal-ceramic bonding substrate of the present invention; FIG. 9B is a cross-sectional view of the metal-ceramic bonding substrate of FIG. 9A taken along the line AA. FIG. 9B is a cross-sectional view of the metal-ceramic bonding substrate of FIG. 9A taken along the line BB. FIG. 9B is a cross-sectional view of the metal-ceramic bonding substrate of FIG. 9A taken along the line CC. 9B is a rear view of the metal-ceramic bonding substrate of FIG. 9A. FIG.

<Metal-ceramic bonded substrate>
The metal-ceramic bonded substrate of the present invention is 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, and a metal base is attached to a side surface of the metal base plate. The side surface of a plate-like reinforcing member made of metal having a higher strength than the plate is joined.

Hereinafter, examples of embodiments of the metal-ceramic bonding substrate according to the present invention will be described in detail with reference to the drawings.

(First embodiment)
As shown in FIGS. 1A to 1E, an embodiment of a metal-ceramic bonding substrate 1 according to the present invention includes an electrically insulating ceramic substrate 10 having a substantially rectangular planar shape and (a part of) a side surface of the ceramic substrate 10. ) and the other surface (rear surface (lower surface) in the illustrated embodiment), the metal base plate 12 having a substantially rectangular planar shape and one surface (the upper 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 the metal base plate 12, and on the side surface (end portion) of the metal base plate 12, the planar shape is substantially rectangular and substantially uniform. The side surface of a plate-like reinforcing member 16 made of a metal having a higher strength (tensile strength) than the thick plate-like metal base plate 12 is joined (to the outer side surface of the metal base plate 12). FIGS. 1A to 1E show a state in which the side surfaces of one reinforcement member 16 are joined to the right side surface and the left side surface (both end surfaces) of the metal base plate 12 . By bonding the reinforcing member 16 to the side surface of the metal base plate 12, it is possible to provide a metal-ceramic bonding substrate that can sufficiently suppress warping even when thermal history is applied.

The reinforcing member 16 preferably has a through hole 18 extending substantially perpendicularly to the main surface (plate surface) of the reinforcing member 16 . FIG. 1A shows that two through-holes 18 are formed at the end of one reinforcement member 16 .

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 dissipating member (not shown) such as a heat dissipating fin or a water cooling jacket, or a housing (not shown) surrounding the metal plate 14 for circuit patterns and the semiconductor mounted thereon may be screwed or bolted through the through holes 18. can be installed.
As described above, in the present invention, by bonding the reinforcing member 16 to the side surface of the metal base plate 12, warping is sufficiently suppressed even when thermal history is applied, and the portions to be fastened with screws or bolts are strengthened by the reinforcing member 16. Therefore, even after a heat cycle test, for example, the deformation of the screwed portion (reinforcing member 16) is sufficiently small, and the loosening (tightening torque) of the screw (or bolt) can be sufficiently suppressed. .
1B to 1D, the back surface of the reinforcing member 16 (the surface opposite to the circuit pattern metal plate 14) and the back surface of the metal base plate 12 (the circuit pattern metal plate 14 is The surface on the opposite side) is approximately the same plane, and the metal base plate 12 joined to the reinforcing member 16 and integrated can be assembled in a state of being in good contact with the heat dissipating member without gaps.

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

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

Chip parts such as semiconductor elements are mounted on the metal plate 14 for the circuit pattern, so a metal with excellent electrical conductivity and thermal conductivity is preferable. Aluminum or an aluminum alloy containing 99.9% by mass or more of aluminum is preferred.

It is desirable that the metal base plate 12 has a certain degree of hardness as a structural member as well as thermal conductivity.

The ceramic substrate 10 has a function of maintaining insulation between the metal plates 14 when there are a plurality of 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 ceramic substrate 10 (having a composition of 85% by mass or more) is preferably one or more selected from alumina, aluminum nitride, silicon nitride and silicon carbide.

1, the reinforcing member 16 is formed in a region other than the bonding region between the ceramic substrate 10 and the metal base plate 12 when viewed from above in a direction perpendicular to the main surface of the ceramic substrate 10. is preferred. It is preferable not to form the reinforcing member 16 in the bonding area between the ceramic substrate 10 and the metal base plate 12 in order to ensure heat dissipation.

Further, when the reinforcing member 16 made of carbon steel is used, the bonding interface between the reinforcing member 16 and the metal base plate 12 made of aluminum or an aluminum alloy has, for example, an alloy layer of Fe and Al with a thickness of several 100 μm or less ( A bonding layer (not shown) is preferably formed, and the reinforcing member 16 and the metal base plate 12 are firmly bonded. Further, the metal base plate 12 may have an alloy structure in which Fe diffuses from the alloy layer to the metal base plate 12 side and an intermetallic compound of Fe and Al is formed (dispersed) in the Al matrix. The strength of the metal base plate 12 is improved by the diffusion of Fe into Al and the formation of an intermetallic compound.

<Manufacturing method>
The method for producing a metal-ceramic bonded substrate of the present invention is a method for producing 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 of the ceramic substrate, wherein the metal base plate A plate-shaped reinforcing member made of a metal having a higher melting point and higher strength and a ceramic substrate are arranged in the mold with a gap therebetween, and the metal is placed in contact with both sides of the ceramic substrate in the mold and the side surfaces of the reinforcing member. After pouring the molten metal, the metal plate is formed and directly bonded to one surface of the ceramic substrate by cooling and solidifying, and the metal base plate is formed and directly bonded to the other surface of the ceramic substrate. 1) joining the side surface of the reinforcing member to the side surface of the metal base plate;

Hereinafter, as an embodiment of the method for manufacturing a metal-ceramic bonded substrate of the present invention, a metal-ceramic bonded substrate is obtained by bonding a ceramic substrate, a metal base plate, a metal plate for circuit patterns, and a reinforcing member by a molten metal bonding method. will be described with reference to the drawings.

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

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. 2A is a plan view (top view) of the middle mold 20 and the outer mold 40 that constitute the lower mold 100, FIG. 2D is a cross-sectional view along the CC line of FIG. 2A; FIG. 2E is a rear view of FIG. 2A; FIG. 2F is a cross-sectional view along the DD line of FIG. 2A; A cross-sectional view, FIG. 2H, is a cross-sectional view taken along line FF of FIG. 2A. In addition, in the cross-sectional view, the state in which the ceramic substrate 10 is arranged is indicated by a dotted line for the sake of convenience. A portion indicated by a dotted line where the ceramic substrate 10 is arranged is a ceramic substrate accommodating portion in the mold.

On the surface of the middle mold 20, there are formed a ceramic substrate supporting portion 21 which is a convex portion that abuts against the ceramic substrate 10 for insulation during casting, and a metal plate forming portion 22 for circuit which is a concave portion corresponding to the metal plate 14 for circuit pattern. , a metal base plate forming portion 23 that is a recess (located on the lower surface of the ceramic substrate accommodation portion) corresponding to the metal base plate 12 and a reinforcing member accommodation portion 24 that is a recess for accommodating the reinforcing member 16 are formed, A convex portion 25 corresponding 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 adjacent to the metal base plate forming portion 23 and formed integrally with the metal base plate forming portion 23 . A portion of the middle mold 20 where the reinforcing member 16 is arranged is referred to as a "reinforcing member accommodating portion 24" for convenience. For convenience, the portion where the molten metal is injected to form the metal base plate 12 is referred to as "metal base plate forming portion 23".

The ceramic substrate supporting portion 21 is formed so as to surround the periphery (side surface) of the ceramic substrate 10, and the outer peripheral portion of the ceramic substrate supporting portion 21 abuts on the peripheral portion of one surface (the surface on the circuit pattern side) of the ceramic substrate 10. A step having a substantially L-shaped cross section is provided to support the ceramic substrate 10 at a predetermined position in contact therewith, forming a ceramic substrate accommodating portion which is a space for accommodating the ceramic substrate.
The ceramic substrate supporting portion 21 has an L-shaped cross section, so that when the molten aluminum or aluminum alloy is poured into the mold after the ceramic substrate 10 is placed in the ceramic substrate accommodating portion, the ceramic substrate 10 is This is preferable because it can prevent deviation from the predetermined position.
Therefore, when the ceramic substrate 10 is placed, the tip (upper end) of the ceramic substrate support portion 21, which has an L-shaped cross section, must be at the same height or lower than the upper surface (the surface on the side of the metal base plate) of the ceramic substrate 10. is desirable. However, if it is too low, that is, if it is the same height as or lower than one surface of the ceramics substrate (the surface on the circuit pattern side), there is a high possibility that the ceramics substrate 10 will be misaligned. Therefore, when the ceramics substrate 10 is placed on the ceramics substrate supporter 21, the tip of the ceramics substrate supporter 21 has a thickness corresponding to the thickness of the ceramics substrate 10 from one surface of the ceramics substrate 10 (the surface on the circuit pattern side, the lower surface). It is preferable that the height is approximately half or more to the same height as the thickness of the ceramic substrate 10 .
If the tip of the ceramic substrate supporting portion 21 is at the same level as or higher than the upper surface of the ceramic substrate 10, the metal base plate 12 is not joined to the side surface of the ceramic substrate 10 (however, in practice, the ceramic substrate 10 A metal base plate may be joined to the side surface of the ceramic substrate 10 in order to provide a slight clearance (gap) between the side surface of the ceramic substrate 10 and the ceramic substrate supporting portion 21 for easy placement.).
At least one (three in the illustrated embodiment) for forming a metal plate 14 for a circuit pattern is provided approximately in the center of the upper surface of the ceramic substrate supporting portion 21 (the surface with which one surface of the ceramic substrate abuts). ) (metal plate forming portion) 22 are formed. The metal plate forming portion 22 is separated from the metal base plate forming portion 23 via the ceramic substrate supporting portion 21, and provides insulation between the metal base plate 12 and the metal plate 14 when the ceramic substrate 10 is arranged. It is designed to be secured.

On the surface adjacent to the metal base plate forming portion 23 of the middle mold 20, a runner 26 for molten metal, which is a concave portion, is formed. Holes 27 (four through-holes are shown in FIG. 2A) for pouring molten metal are formed.

FIG. 3A schematically illustrates a plan view (top view) of the middle die 20 that constitutes the lower die of FIG.
4 schematically illustrates a plan view (top view) of the outer mold 40 constituting the lower mold 100 of FIG. 2 as viewed from above.

The outer mold 40 has a convex portion 41 that fits into the space of the molten metal storage portion of an upper mold 200 (FIG. 5), which is a mold component to be combined during casting. Molten metal is poured.
A molten metal inlet 43 and a grooved runner 44 for supplying molten metal to the circuit metal plate forming portion 22 are formed on the surface (convex portion 41 ) of the outer mold 40 . The pouring hole 27 of the metal plate forming part 22 for the circuit of the middle mold 20 straightly penetrates the plate thickness of the middle mold 20, and the through hole is the tip of the groove of the branched runner 44 of the outer mold. connected nearby.

During casting, molten metal is poured onto the upper surface of the projection 41 , and the molten metal is pressurized and fed from the molten metal inlet 43 to the runner 44 . Therefore, in FIGS. 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.
The runner 26 for supplying the molten metal to the metal base plate forming portion 23 is a separate path from the runner 44 for supplying the molten metal to the metal plate forming portion 22 for the circuit. Molten metal is supplied to the runner 26 from the .

5A and 5B show the structure (plan view) of an upper mold 200 used in combination with the lower mold, which is a mold component for producing a cast product of the metal-ceramic bonding substrate 1 shown in FIG. Schematically exemplified. FIG. 5A is a bottom view (the side covered with the lower mold), and FIG. 5B is a top view (the side that faces up when the lower mold is covered). The upper mold 200 has a molten metal reservoir 201 that receives the molten metal supplied to the mold.

The molten metal reservoir 201 is formed by a space penetrating the body of the upper mold 200, and during casting, the molten metal is introduced from the upper opening of the upper mold 200 (of the molten metal reservoir 201) through a supply port 204. On 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. there is The reinforcing member accommodating portion 203 is adjacent to the metal base plate forming portion 202 and formed integrally with the metal base plate forming portion 202 . A portion of the upper die 200 where the reinforcing member 16 is arranged is referred to as a "reinforcing member accommodating portion 203" for convenience. For convenience, the portion where the molten metal is injected to form the metal base plate 12 is referred to as "metal base plate forming portion 202".

It should be noted that the material of each of the mold components (lower mold 100, upper mold 200) is preferably a carbon material having gas permeability, for example.

6A to 6F schematically illustrate cross-sectional structures of molds constructed by combining the lower mold 100 shown in FIG. 2 and the upper mold 200 shown in FIG. 6A corresponds to the cross section indicated by the AA line in FIG. 2A, FIG. 6B corresponds to the cross section indicated by the BB line in FIG. 2A, and FIG. 6C is the CC line in FIG. 2A. corresponds to the cross section at the position indicated by , FIG. 6D corresponds to the cross section at the position indicated by the DD line in FIG. 2A, and FIG. 6E corresponds to the cross section at the position indicated by the EE line in FIG. FIG. 6F corresponds to a cross section at the position indicated by the FF line in FIG. 2A.

Next, a manufacturing method for manufacturing the metal-ceramic bonded substrate 1 by a molten metal bonding method using the mold will be described.
First, the middle mold 20 is housed in the middle mold housing portion 45 of the outer mold 40 of the lower mold 100, which is a mold component (the states shown in FIGS. 2A to 2H).
Next, the ceramic substrate 10 is placed on the ceramic substrate supporting portion 21 of the medium mold 20 . By arranging the ceramic substrate 10, a metal plate forming portion 22, which is a space between one surface of the ceramic substrate 10 and the surface of the medium mold 20, is defined. The ceramic substrate supporting portion 21 also plays a role of positioning and preventing displacement so that the ceramic substrate 10 is not displaced from a predetermined position by the molten metal when the molten metal is poured later.

A reinforcing member 16 is arranged in the reinforcing member accommodating portion 24 of the middle mold 20 . The reinforcing member 16 is plate-shaped, and through holes 18 for screwing are formed in advance, and the projections 25 of the middle die 20 are positioned corresponding to the through holes 18 of the reinforcing member 16 and have an appropriate size for fitting. By fitting the through hole 18 of the reinforcing member 16 into the convex portion 25 , the reinforcing member 16 can be arranged at a predetermined position in the reinforcing member accommodating portion 24 .
By arranging both on the medium mold 20 in this way, the ceramic substrate 10 and the reinforcing member 16 are positioned apart from each other.
2B to 2D and 2F to 2H, which are cross-sectional views of the lower mold 100, show the state in which the ceramic substrate 10 is arranged for the sake of convenience.

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

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

For example, it is preferable to pour the molten metal supplied from the melting furnace while removing the oxide film. As the oxide film removal treatment, in the case of an aluminum-based molten metal, it is effective to pour the molten metal while removing the oxide film on the surface of the molten metal by passing the molten metal through, for example, a very small nozzle.

The molten metal accumulated in the molten metal reservoir 201 in the mold is sent 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. The metal base plate forming portion 202, the metal base plate forming portion 23, and the metal plate forming portion 22 in the space within the mold are each filled with the molten metal.
A portion of the molten metal material introduced into the molten metal storage portion 201 from the molten metal inlet 204 is fed from the molten metal inlet 42 to the runner 26 and filled in the metal base plate forming portion 202 and the metal base plate forming portion 23 . be. Further, the remaining part of the molten metal material introduced into the molten metal reservoir 201 from the molten metal supply port 204 is fed from the molten metal inlet 43 to the runner 44 and passes through the pouring hole 27 to form each metal plate. Part 22 is filled.

After filling (supplying) the molten metal in the mold, the low temperature of the mold is reduced by a method such as contacting a water-cooled copper block as a cooling device to the mold outer wall at the low temperature side end (for example, the lower end in FIGS. 6D to 6F). It is desirable to directionally solidify the molten metal by forcibly extracting heat from the side. In order to prevent casting defects such as shrinkage cavities, the metal base plate forming portion 202 and the metal base plate are passed through the runner 26 while being pressurized with an inert gas such as nitrogen gas from the hot water supply port 204 at a pressure of, for example, 5 to 200 kPa. It is desirable to feed the molten metal from the pouring hole 27 to the metal plate forming portion 22 via the forming portion 23 and the runner 44, and solidify while applying pressure.

In this way, the molten metal is poured into the mold so as to be in contact with both sides of the ceramic substrate 10 and the side surface of the reinforcing member 16, and then cooled and solidified, whereby the side surface and the other side of the ceramic substrate 10 are solidified. A metal base plate 12 having a substantially rectangular planar shape that is bonded to the entire surface (back surface) is directly bonded, and at least one (three in the illustrated embodiment) that is directly bonded to one surface of the ceramic substrate 10. The circuit pattern metal plate 14 is directly joined, and the side surface (inner side surface) of the reinforcing member 16 is joined to the side surface of the metal base plate 12 .

It is preferable that the metal base plate 12 is made of aluminum or an aluminum alloy, that is, it is preferable to pour a molten metal made of aluminum or an aluminum alloy into the mold. Moreover, it is preferable that the metal plate 14 is made of aluminum or an aluminum alloy, that is, it is preferable to pour a molten metal made of aluminum or an aluminum alloy into the mold.

Since chip parts such as semiconductor elements are mounted on the metal plate 14 for the circuit, a metal having excellent electrical conductivity and thermal conductivity is preferable. It is preferable to pour molten metal of aluminum or aluminum alloy containing more than mass % of aluminum.

Moreover, since it is desirable that the metal base plate 12 has thermal conductivity and a certain degree of hardness (strength) as a constituent member, it is preferable that the metal plate 14 has a higher hardness than the circuit metal plate 14 . That is, by changing the compositions of the molten metal used for the metal base plate 12 and the molten metal used for the metal plate 14, the hardness of the metal base plate 12 is greater than the hardness of the metal plate 14. You may pour hot water from the runner provided separately.
When metal base plate 12 and metal plate 14 have different aluminum or aluminum alloy compositions, metal supply port 204 and molten metal reservoir 201 may be separately provided (not shown) for pouring.

In addition, a bonding layer made of, for example, an alloy of Fe and Al is formed at the bonding interface between the reinforcing member 16 made of carbon steel or stainless steel and the metal base plate 12 so that the bonding between the reinforcing member 16 and the metal base plate 12 becomes strong. preferably.
Since Fe diffuses into Al to reduce electrical conductivity, runners 26 for feeding the molten metal to the metal base plate 12 and runners for feeding the molten metal to the metal plate 14 for the circuit pattern are provided. 44 is preferably provided separately.
On the other hand, Fe diffused into Al forms a compound such as FeAl ₃ to increase the hardness of the metal base plate 12, thereby obtaining appropriate hardness (strength) for the metal base plate.

The metal-ceramic bonded body obtained as described above is taken out by removing the upper mold 200 and dismantling the mold. For the cast product, which is a metal-ceramic bonded body, the solidified portion of the runner 26 connected to the metal base plate 12 is cut and removed, and the protrusions on the surface of the metal plate 14 remaining in the pouring hole 27 are polished. The metal-ceramic bonding substrate 1 having a predetermined shape can be obtained by, for example, forming the substrates.

(Second embodiment)
7A to 7E show schematic diagrams of a metal-ceramic bonding substrate 2 of another embodiment. In FIG. 2, projections are provided on the surface of the reinforcing member accommodating portion 24 of the mold. A gap is left between the mold 200 and the reinforcing member 16, and when the molten metal is poured, the molten metal also contacts the main surface (plate surface) and the side surface (outer surface) of the reinforcing member 16 other than the joint surface. In this manner, aluminum or aluminum alloy 30 may be bonded to the main and side surfaces of reinforcing member 16 . By reducing the diameter of the convex portion 25 and providing a gap between it and the through-hole 18 of the reinforcing member 16 and pouring the molten metal, the surface (inner surface) of the through-hole 18 can also be made of aluminum or an aluminum alloy. may be formed.

If the reinforcing member 16 is made of carbon steel and the metal base plate 12 is made of aluminum or an aluminum alloy, the reinforcing member 16 will corrode (galvanic corrosion) when the metal-ceramic substrate is incorporated in a semiconductor device such as a power module. Since there is a possibility, the entire surface of the reinforcing member 16 (the main surface, the side surface to which the metal base plate 12 is not bonded, and the inner surface of the through hole 18) is covered with aluminum or aluminum alloy 30, that is, the surface of the reinforcing member 16 is covered with aluminum or aluminum alloy 30. Preferably, aluminum or aluminum alloy 30 is bonded (formed).

(Third Embodiment)
As another embodiment, as shown in FIGS. 8A to 8E, a metal-ceramic bonding substrate 3 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 other surface of the ceramic substrate 10 can be used. good. It can be manufactured by changing the shape of the mold so that the shape of the metal base plate 12 of the metal-ceramic bonding substrate of FIG. 8 is formed.

(Fourth embodiment)
As another embodiment, as shown in FIGS. 9A to 9E, a metal-ceramic bonding substrate 4 may be used in which a reinforcing member 16 is bonded so as to surround a metal base plate 12. FIG. By changing the shape of the reinforcing member 16 and changing the shape of the reinforcing member accommodating portion 203 and the reinforcing member accommodating portion 24 so that the reinforcing member 16 of the metal-ceramic bonding substrate shown in FIG. 9 can be accommodated in the mold, can be manufactured.

Although the examples of the embodiments of the present invention have been described above, the present invention is not limited to this, and includes those in line with the gist of the present invention. For example, heat radiation pins or fins 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 and fins for heat radiation integrally formed with the aluminum base plate are prepared by preparing a mold having a space substantially the same as the shape of the pins and fins inside, and then pouring an aluminum alloy into the mold. can be made.

Hereinafter, examples of the metal-ceramic bonding substrate and the manufacturing method thereof according to the present invention will be described in detail.

(Example 1)
A substantially rectangular aluminum nitride substrate (AlN substrate) having a length of 70 mm, a width of 65 mm, and a thickness of 0.6 mm was prepared as the ceramic substrate 10, and a substantially rectangular substrate having a length of 10 mm, a width of 80 mm, and a thickness of 2 mm was prepared as the reinforcing member 16. A rectangular SPCC (ordinary steel) plate material (having a tensile strength of 270 MPa or more as a material) was prepared. The reinforcing member 16 has a through hole 18 having a diameter of 6 mm and vertically penetrating the plate surface at a position 8 mm from both ends in the width direction and 5 mm in the length direction. For convenience, in FIG. 2A, the horizontal direction is represented as the length direction, and the vertical direction as the width direction.
Next, the ceramic substrate 10 is placed on the ceramic substrate supporting portion 21 of the middle mold 20 of the lower mold (mold) 100 similar to the mold component shown in FIG. The through hole 18 of the reinforcing member 16 was fitted, and the reinforcing member 16 was accommodated in the reinforcing member accommodating portion 24 .
Then, the upper mold 200 was placed over the lower mold 100 as shown in FIG. The inside of the mold is heated in a nitrogen atmosphere, and molten pure aluminum (containing 99.9% by mass or more of Al) is poured into the mold while removing the oxide film on the surface, and then the mold is cooled. By solidifying the molten metal, a metal base plate 12 (having an outer shape of 80 mm in length and 80 mm in width) is integrally formed on the other surface of the

ceramics substrate

10, and 3 is formed on one surface of the ceramics substrate 10. A metal plate 14 made of aluminum for a circuit pattern was formed, and a metal-ceramic bonded body was produced in which reinforcing members 16 were directly bonded to both side surfaces of a 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 set to 0.47 mm, and the area of the outer peripheral portion of the ceramic substrate 10 with a width of 0.2 mm (the recess on the drawing, the ceramic substrate of the mold at the time of casting) The thickness of the metal base plate in the portion that was the tip of the support portion) was set to 0.77 mm, and the thickness of the metal base plate in other regions (the portion joined to the reinforcing member, etc.) was set to 2 mm. Also, the thickness of the metal plate for the circuit pattern bonded to one surface of the ceramic substrate was set to 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. For the tensile strength of the metal base plate, a cut metal base plate is used as a test piece for measurement.
Next, after taking out the metal-ceramic bonded body from the mold, the aluminum portion formed corresponding to the runner 26 is cut, and the surface of the circuit pattern metal plate 14 is polished to obtain the metal-ceramic bonded substrate 1. was made.

(Example 2)
The thickness of the reinforcing member 16 is set to 3 mm, the thickness of the metal base plate 12 bonded to the other surface of the ceramic substrate 10 is set to 0.8 mm, and the outer peripheral portion of the ceramic substrate 10 has a width of 0.2 mm ( The thickness of the metal base plate in the concave portion) was set to 1.1 mm, and the thickness of the metal base plate in other regions (the portion joined to the reinforcing member, etc.) was set to 3 mm. A metal-ceramic bonded substrate was produced in the same manner as in Example 1, except that the thickness of the circuit pattern metal plate 14 bonded to one surface of the ceramic substrate was 1.6 mm.

(Example 3)
The thickness of the reinforcing member 16 is set to 4 mm, the thickness of the metal base plate 12 bonded to the other surface of the ceramic substrate 10 is set to 1.1 mm, and the outer peripheral portion of the ceramic substrate 10 has a width of 0.2 mm ( The thickness of the metal base plate in the concave portion) was set to 1.45 mm, and the thickness of the metal base plate in other regions (the portion joined to the reinforcing member, etc.) was set to 4 mm. A metal-ceramic bonded substrate was produced in the same manner as in Example 1, except that the thickness of the circuit pattern metal plate 14 bonded to one surface of the ceramic substrate was 2.3 mm.

(Example 4)
A metal-ceramic bonding substrate was produced in the same manner as in Example 2, except that the reinforcing member 16 was made of S45C (carbon steel for machine structural use, which has a tensile strength of 570 MPa or more).

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

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

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

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

(Example 9)
A metal-ceramic bonding substrate having a shape as shown in FIG. .

(Example 10)
A substantially rectangular reinforcing member 16 having a length of 10 mm, a width of 80 mm, and a thickness of 2.4 mm was prepared, and three protrusions each having a diameter of 1 mm and a height of 0.3 mm were provided in the reinforcing member accommodating portion 24, and one side of the reinforcing member 16 was The main surface (plate surface) of the middle mold 20 is separated from the surface (bottom surface) and the side surface by 0.3 mm, and the gap between the other main surface (plate surface) of the reinforcing member 16 and the outer mold 40 is 0.3 mm Aluminum having a thickness of 0.3 mm was formed (joined) on one main surface, the other main surface and the side surface of the reinforcing member 16 corresponding to FIG. A metal-ceramic bonded substrate was fabricated.

(Example 11)
A substantially rectangular reinforcing member 16 having a length of 10 mm, a width of 80 mm, and a thickness of 2.6 mm was prepared, and three protrusions each having a diameter of 1 mm and a height of 0.2 mm were provided in the reinforcing member accommodating portion 24, and one side of the reinforcing member 16 was The main surface (plate surface) of the middle mold 20 is separated from the surface (bottom surface) and the side surface by 0.2 mm, and the gap between the other main surface (plate surface) of the reinforcing member 16 and the outer mold 40 is 0.2 mm Aluminum having a thickness of 0.2 mm was formed (joined) on one main surface, the other main surface and the side surface of the reinforcing member 16 corresponding to FIG. A metal-ceramic bonded substrate was fabricated.

(Example 12)
A substantially rectangular reinforcing member 16 having a length of 10 mm, a width of 80 mm, and a thickness of 2.0 mm was prepared, and three protrusions each having a diameter of 1 mm and a height of 0.5 mm were provided in the reinforcing member accommodating portion 24, and one side of the reinforcing member 16 was The main surface (plate surface) of the middle mold 20 is supported with a distance of 0.5 mm from the surface (bottom surface) and the side surface of the middle mold 20, and the gap between the other main surface (plate surface) of the reinforcing member 16 and the outer mold 40 is 0.5 mm Aluminum having a thickness of 0.5 mm was formed (joined) on one main surface, the other main surface and the side surface of the reinforcing member 16 corresponding to FIG. A metal-ceramic bonded substrate was fabricated.

(Example 13)
The reinforcing member 16 has a thickness of 2.4 mm and has a (mouth-like) shape surrounding the outer circumference of the metal base plate 12 with a width of 10 mm. and supports one main surface (plate surface) of the reinforcing member 16 with a distance of 0.3 mm from the surface (bottom surface) and the side surface of the middle mold 20, and the other main surface (plate surface) of the reinforcing member 16 and the outer mold 40 Aluminum with a thickness of 0.3 mm is formed on one main surface, the other main surface and the side surface of the reinforcing member 16 corresponding to FIG. A (bonded) (covered) metal-ceramic bonded substrate was produced.

(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 pure aluminum molten metal was poured into the reinforcing member accommodating portion 24 and allowed to solidify.

(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 formed metal-base plate has a tensile strength of about 200 MPa, a thermal conductivity of 137 W/(m/K), and an electrical conductivity of 35% IACS.

(Comparative Example 3)
The plate-shaped reinforcing member 16 was not arranged in the mold, and instead, a pipe-shaped member of SUS304 surrounding the convex portion 25 was arranged. The pipe has a wall thickness of 1 mm and a height of 3 mm. Thereafter, a metal-ceramic bonding substrate was produced in the same manner as in Example 2, except that molten aluminum was poured and solidified.

<Evaluation and results>
The examples and comparative examples were evaluated and compared with respect to bondability, screw fastening property, warpage of the metal base plate, heat dissipation, electrical conductivity, and corrosion resistance.

(bondability)
Regarding the bonding interface between the reinforcing member of the metal-ceramic bonding substrate and the metal base plate (the pipe-shaped member and the metal base plate in Comparative Example 3), the cross section of the bonding substrate was observed with a microscope to determine the presence or absence of bonding defects at the bonding interface. The presence or absence of a bonding layer (Fe—Al alloy layer) and its thickness were confirmed.
As a result, in Examples 1 to 5, 9 to 13 and Comparative Examples 1 and 2, no bonding defect was observed at the bonding interface and the bonding was excellent. In Examples 6 to 8, although minute voids were observed at the bonding interface between the reinforcing member and the aluminum metal base plate, the bonding strength was sufficient and there was no problem in use. In Comparative Example 3, many voids were observed at the joint interface between the pipe-shaped member and the metal base plate, and it was determined that the joint was defective.
When the bonding interfaces of Examples 2, 4, 5, 9 to 13 were observed, a bonding layer (alloy layer) composed of Fe and Al was confirmed. The thickness of the bonding layer in Examples 2 and 9 to 13 was about 150 μm, the thickness of the bonding layer in Example 4 was about 50 μm, and the thickness of the bonding layer in Example 5 was about 100 μm.
In Examples 10 to 13, aluminum is formed (bonded) on the main surface (plate surface) and side surfaces of the reinforcing member, but a bonding layer is formed between the aluminum on the main surface and side surfaces and the reinforcing member, and the fastening is performed. It was confirmed that the strength (hardness) of aluminum on the surface of the part was improved.

(warp)
Located diagonally between the height of the metal plate for the circuit pattern in the center of the metal-ceramic bonding substrate and the outer peripheral edge of the metal-ceramic bonding substrate when viewed from the direction perpendicular to the main surface of the ceramic substrate. Measure the height of the metal base plate (designed to be the same height as the metal plate for the circuit pattern) at two corners (two points), and measure the reference line passing through the two points and the center The warpage of the product was defined as the difference in the height of the metal plate for the circuit pattern. The warp is positive when the height of the central portion is low, and the (initial) warp is preferably in the range of -0.3 to 0.3 mm.
As a result, the warpage of Examples 1 to 13 and Comparative Examples 1 and 3 was in the range of −0.1 to 0.1 mm, which was good. Comparative Example 2 was about +0.5 mm.
Further, the warpage after heating the metal-ceramic bonded substrate to 300° C. was calculated by simulation using the finite element method. Those with a warp change of 0.15 mm or less after heating with respect to the initial warp are regarded as excellent products (◎), those exceeding 0.15 mm and 0.20 mm or less are regarded as good products (◯), and 0.20 mm is regarded as a good product. Those exceeding 0.25 mm or less were regarded as defective products (Δ), and those exceeding 0.25 mm were regarded as defective products (x).
As a result, Examples 1 to 8, 10 to 12 and Comparative Example 2 were good products, Examples 9 and 13 were good products, and Comparative Examples 1 and 3 were bad products.

(Fixability)
A frame-shaped member made of stainless steel (SUS304) having an outer size of 100 mm long x 80 mm wide x 10 mm high and a frame thickness of 10 mm, and corresponding to the through holes of the metal base plate at the four corners. A frame-shaped member corresponding to a water-cooling jacket (radiating member) was prepared, which had a bolt fastening portion formed with a through-hole. A polyethylene frame member having an outer size of 100 mm long, 80 mm wide, 10 mm high, and a frame thickness of 10 mm, and further having four corners corresponding to the through holes of the metal base plate. First, the frame-shaped member corresponding to a case member (housing) for enclosing a semiconductor or the like, which has a bolt fastening portion with a through hole formed therein, was prepared.
For each of the metal-ceramic bonded substrates obtained in Examples 2, 10, 11, 12 and Comparative Examples 1 and 2, a frame-shaped member corresponding to the water cooling jacket was provided on the back surface of the metal base plate. A frame-shaped member corresponding to the case member was arranged on the surface of the metal base plate, and bolts were fastened through the through-holes of these frame-shaped members and the through-holes of the metal base plate.
For the metal-ceramic bonding substrate to which these frame members are fastened with bolts, a heat cycle (one cycle is -40°C x 30 minutes → 25°C x 10 minutes → 150°C x 30 minutes → 25°C x 10 minutes) A heat cycle test was conducted by adding 500 cycles of For evaluation, the bolt tightening torque was measured (actual measurement) before (initial) and after the heat cycle test. A reduction in tightening torque after the heat cycle of 20% or less compared to before the heat cycle was evaluated as good. In addition, the presence or absence of cracks in the ceramic substrate of the metal-ceramic bonding substrate after 500 cycles was confirmed.
As a result, in Examples 2, 10, 11, and 12, even after 500 heat cycles were applied to the initial value, the tightening torque was maintained at 80% or more (the decrease in torque was 20% or less). ). On the other hand, in Comparative Example 1, after 500 heat cycles were applied, the tightening torque was 16% of the initial value (the torque decreased by 84%). Moreover, deformation of 50 to 100 μm was confirmed in the fastening portion.
Further, in Examples 1 to 13 and Comparative Examples 1 and 3, no cracks were observed in the ceramic substrate after 500 heat cycles. It was unreliable as

(heat dissipation, conductivity)
The heat dissipation of the metal base plate was evaluated by thermal conductivity, and the conductivity of the metal plate for the circuit pattern was evaluated by conductivity. A thermal conductivity of 180 W/mK or higher and an electrical conductivity of 50% IACS or higher were considered good.
Examples 1 to 13 and Comparative Examples 1 and 3 were good in both thermal conductivity and electrical conductivity.
Comparative Example 2 has a thermal conductivity of 137 W/mK, which is low for a metal base plate (for heat dissipation) and poor in heat dissipation, and has a conductivity of 35%IACS, which is too low to be used as a metal plate for circuit patterns. was not suitable for

(Vickers hardness)
Vickers hardness was measured based on JIS-Z2244 for the surface of the circuit pattern metal plate and the surface of the metal base plate in the vicinity of the reinforcing member.
Except for Comparative Example 2, the Vickers hardness HV of the surface of the metal plate for circuit pattern was in the range of 20-23. 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 28-35.
The Vickers hardness HV of the metal base plate of Comparative Example 1 is in the range of 20 to 23, and the Vickers hardness HV of the surface of the circuit pattern metal plate and the surface of the metal base plate in Comparative Example 2 is in the range of 45 to 48. Met.

(Corrosion resistance)
Corrosion resistance was judged to be poor when corrosion of the reinforcing member or metal base plate (aluminum or aluminum alloy) was confirmed after the corrosion test in salt water. In some cases, even if the corrosion resistance is poor, if the design is such that it is covered with resin or the like when incorporated into a semiconductor device, the corrosion can be dealt with and no problem arises, but it is desirable that the corrosion resistance is excellent.
According to the above test, Examples 10 to 13 and Comparative Examples 1 and 2 were excellent in corrosion resistance with no corrosion observed. 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.

Table 1 shows an overview of the evaluation results.

The present invention can be applied to metal-ceramic bonding substrates.

1, 2, 3, 4 metal-ceramic bonding substrate 10 ceramic substrate 12 metal base plate 14 metal plate 16 reinforcing member 18 through-hole 20 middle die 21 ceramic substrate support portion 22 metal plate forming portion 23 metal base plate forming portion 24 reinforcing member accommodation Portion 25 Convex portion 26 Runner 27 Pouring hole 30 Aluminum or aluminum alloy 40 Outer mold 41

Convex portions

42, 43 Molten metal inlet 44 Runner 45 Middle mold container 100 Lower mold 200 Upper mold 201 Molten metal reservoir 202 Metal base plate formation Part 203 Reinforcing member accommodation part 204 Hot water supply port

Claims

A metal plate is bonded to one side of the ceramic substrate,
In a metal-ceramic bonded substrate having a metal base plate bonded to the other surface,
A metal-ceramic bonding substrate, characterized in that the side surface of a metal base plate is joined to the side surface of a plate-shaped reinforcing member made of a metal having a higher strength than the metal base plate.
The metal-ceramic bonding substrate according to claim 1, characterized in that said reinforcing member has through holes.
The metal-ceramic bonding substrate according to claim 1 or 2, characterized in that the metal base plate is directly bonded to the ceramic substrate.
The metal-ceramic bonding substrate according to any one of claims 1 to 3, wherein the metal plate is directly bonded to the ceramic substrate.
The metal-ceramic bonding substrate according to any one of claims 1 to 4, characterized in that said metal base plate is made of aluminum or an aluminum alloy.
The metal-ceramic bonding substrate according to any one of claims 1 to 5, wherein the reinforcing member is made of carbon steel or stainless steel.
The metal-ceramic bonding substrate according to any one of claims 1 to 6, wherein the metal plate is made of aluminum or an aluminum alloy.
The metal-ceramic bonding substrate according to any one of claims 1 to 7, characterized in that aluminum or an aluminum alloy is bonded to the main surface of the reinforcing member.
The metal-ceramic bonding substrate according to any one of claims 1 to 8, characterized in that a bonding layer made of an alloy is formed on the bonding interface between the reinforcing member and the metal base plate.
A metal plate is joined to one side of the ceramic substrate,
In a method for manufacturing a metal-ceramic bonded substrate in which a metal base plate is bonded to the other surface,
A plate-shaped reinforcing member made of a metal having a melting point and strength higher than those of the metal base plate and a ceramic substrate are spaced apart from each other in the mold,
By pouring a molten metal so that it contacts both sides of the ceramic substrate in the mold and contacts the side surface of the reinforcing member, and then cooling and solidifying,
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 method for manufacturing a metal-ceramic bonded substrate, which comprises bonding a side surface of a reinforcing member to a side surface of a metal base plate.
The method for producing a metal-ceramic bonding substrate according to claim 10, characterized in that said reinforcing member has through holes.
The method for producing a metal-ceramic bonding substrate according to claim 10 or 11, wherein the molten metal for forming the metal base plate is made of aluminum or an aluminum alloy.
The method for producing a metal-ceramic bonding substrate according to any one of claims 10 to 12, characterized in that said reinforcing member is made of carbon steel or stainless steel.
The method for producing a metal-ceramic bonding substrate according to any one of claims 10 to 13, wherein the molten metal for forming the metal plate is made of aluminum or an aluminum alloy.
When pouring the molten metal, 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 joining aluminum or an aluminum alloy to the main surface of the reinforcing member. The method for producing a metal-ceramic bonding substrate according to any one of claims 10 to 14, characterized in that:
16. The method for producing a metal-ceramic bonding substrate according to claim 10, wherein a bonding layer made of an alloy is formed on the bonding interface between said reinforcing member and said metal base plate.