JP7157609B2 - METAL-CERAMIC BONDING SUBSTRATE AND MANUFACTURING METHOD THEREOF - Google Patents

Description

The present invention relates to a metal-ceramic bonded substrate and its manufacturing method, and more particularly to a metal-ceramic bonded substrate in which a metal member is bonded to a ceramic substrate and its manufacturing method.

In conventional power modules used to control large currents in electric vehicles, trains, and machine tools, a metal-ceramic insulating substrate is fixed by soldering to one side of a metal plate or composite material called a base plate. A semiconductor chip is soldered onto this metal-ceramic insulating substrate, and a heat-dissipating fin and cooling jacket made of metal are attached to the other side (rear surface) of the base plate via heat-conducting grease and screwed. It is

Since the base plate and the semiconductor chip are soldered to the metal-ceramic insulating substrate by heating, the base plate tends to warp due to the difference in thermal expansion coefficient between the joining members during soldering. In addition, the heat generated from the semiconductor chip is released to the air and cooling water by the heat radiation fins and cooling jacket through the metal-ceramic insulating substrate, solder, and base plate, so if the base plate warps during soldering, , the clearance becomes large when the heat radiation fins and the cooling jacket are attached to the base plate, and the heat radiation performance is extremely deteriorated.

In order to solve such problems and increase the reliability of metal-ceramic insulating substrates, metal-ceramic circuit substrates using aluminum with very low yield stress as a base plate, for example, a proof stress of 320 MPa or less and a thickness. A metal-ceramic circuit board has been proposed in which a base plate made of aluminum or an aluminum alloy with a thickness of 1 mm or more is directly bonded to a ceramic substrate by a molten metal method (see, for example, Patent Document 1).

However, although it is necessary to increase the purity of aluminum in order to reduce the yield stress of aluminum, it is difficult to control the crystal grain size of aluminum by the molten metal method, and only a large crystal grain size of 10 mm or more can be obtained. If the crystal grain size is large in this way, the crystal grain size distribution will vary, and the aluminum base plate will warp due to heating when a semiconductor chip or the like is soldered.

In order to solve such problems, a ceramic substrate is placed in a mold, and molten aluminum or an aluminum alloy is poured so as to come into contact with predetermined portions on both sides of the ceramic substrate, and then the molten metal is cooled and solidified. Thus, the base plate made of aluminum or an aluminum alloy is formed on the peripheral edge portion and the side surface of one surface of the ceramic substrate and substantially the entire surface of the other surface and is directly bonded to the ceramic substrate, and the circuit pattern made of aluminum or an aluminum alloy is formed. By forming the metal plate on one side of the ceramic substrate at a distance from the base plate and directly bonding it to the ceramic substrate, the ceramic substrate, the peripheral edge of one surface of the ceramic substrate, the side surface, and the other surface of the ceramic substrate. A metal comprising a base plate made of aluminum or an aluminum alloy directly bonded to substantially the entire surface thereof, and a circuit pattern metal plate made of aluminum or an aluminum alloy directly bonded to one surface of a ceramic substrate spaced apart from the base plate- A method for manufacturing a ceramic bonded substrate has been proposed (see, for example, Patent Document 2).

JP 2002-76551 A (paragraph number 0015-0017) JP 2017-228551 A (paragraph number 0009-0012)

However, in the metal-ceramic bonding substrate manufactured by the method of Patent Document 2, when it is incorporated into a power module, the ceramic substrate is placed outside (inside) the portion of the base plate on the side of the circuit pattern metal plate that corresponds to the ceramic substrate. It is difficult to miniaturize the base plate of the metal-ceramic bonding board because it is necessary to attach a case to the non-bonded part). Since it is necessary to attach the water cooling jacket to the outside of the part (the part where the ceramic substrate is not arranged inside), there is a problem that the strength of the base plate to which the water cooling jacket is attached is insufficient.

Therefore, in view of such conventional problems, the present invention provides a base plate made of aluminum or an aluminum alloy that is directly bonded to the peripheral edge portion and side surface of one surface of the ceramic substrate and substantially the entire surface of the other surface. Provided are a metal-ceramic bonded substrate and a method for manufacturing the metal-ceramic bonded substrate, in which a circuit pattern metal plate made of aluminum or an aluminum alloy is directly bonded to one surface of the ceramic substrate, and the base plate of the metal-ceramic bonded substrate can be miniaturized. for the purpose.

As a result of intensive research to solve the above problems, the present inventors have found that a ceramic substrate is arranged in a mold so as to extend in a substantially horizontal direction, and a molten aluminum or aluminum alloy is placed in contact with the surface of the ceramic substrate. After pouring the molten metal, the molten metal is cooled and solidified to form a base plate made of aluminum or an aluminum alloy on substantially the entire peripheral edge of the upper surface, side surfaces and bottom surface of the ceramic substrate and directly bonded to the ceramic substrate, A circuit pattern metal plate made of aluminum or an aluminum alloy is formed on the upper surface of the ceramic substrate at a distance from the base plate and directly bonded to the ceramic substrate, so that the peripheral edge of one surface of the ceramic substrate, the side surface, and the other surface of the ceramic substrate. A compact base plate of a metal-ceramic bonded substrate in which a circuit pattern metal plate made of aluminum or an aluminum alloy is directly bonded to one surface of a ceramic substrate spaced apart from a base plate made of aluminum or an aluminum alloy directly bonded to substantially the entire surface The present inventors have found that it is possible to achieve the present invention.

That is, the method for producing a metal-ceramic bonding substrate according to the present invention comprises placing a ceramic substrate in a mold so as to extend in a substantially horizontal direction, and pouring molten aluminum or an aluminum alloy so as to come into contact with the surface of the ceramic substrate. Then, by cooling and solidifying the molten metal, a base plate made of aluminum or an aluminum alloy is formed on substantially the entire surface of the upper peripheral portion, side surfaces, and bottom surface of the ceramic substrate and is directly bonded to the ceramic substrate, and aluminum or aluminum. A circuit pattern metal plate made of an alloy is formed on the upper surface of the ceramic substrate while being spaced apart from the base plate, and is directly bonded to the ceramic substrate.

In this method of manufacturing a metal-ceramic bonded substrate, the mold is composed of an upper mold member and a lower mold member, and the upper mold member has a recess for forming the base plate having substantially the same shape and size as the outer shape of the upper portion of the base plate. and a recess for forming a circuit pattern having approximately the same shape and size as the metal plate for circuit pattern is formed, and a recess for forming a base plate having approximately the same shape and size as the outer shape of the lower side portion of the base plate is formed in the lower mold member. A recess is formed, and a plurality of ceramic substrate supporting portions are protruded from the peripheral edge of the bottom surface of the base plate forming recess, and the ceramic substrate supporting portions support the peripheral edge of the bottom surface of the ceramic substrate. It is preferable to Further, when the base plate is formed and directly bonded to the ceramic substrate, a large number of columnar protrusions projecting apart from each other may be formed integrally with the base plate on the bottom surface of the base plate. Further, it is preferable that a recess shallower than the base plate forming recess and the circuit pattern forming recess is formed as a molten metal flow path between the base plate forming recess and the circuit pattern forming recess of the upper mold member. Further, a plurality of circuit pattern forming recesses are formed, these circuit pattern forming recesses are arranged apart from each other, and the molten metal flow path is formed along the entire circumference of the circuit pattern forming recesses and the base plate forming recesses. You may form so that it may extend between the recessed parts for circuit pattern formation, and between the recessed parts for circuit pattern formation. In this case, it is preferable to project a holding pin for holding the ceramic substrate placed in the mold from a portion of the upper mold member corresponding to the molten metal flow path.

The metal-ceramic bonding substrate according to the present invention comprises: a ceramic substrate; a base plate made of aluminum or an aluminum alloy directly bonded to the peripheral portion and side surfaces of one surface of the ceramic substrate and substantially the entire surface of the other surface of the ceramic substrate; A circuit pattern metal plate made of aluminum or an aluminum alloy and directly bonded to one surface of the ceramic substrate separated from the base plate, and a part of the peripheral edge of the other surface of the ceramic substrate is exposed to the outside. It is characterized by

In this metal-ceramic bonding substrate, a part of the side surface of the ceramic substrate may be exposed to the outside. In addition, it is preferable to form a plurality of spaced-apart projecting columnar projections integrally with the base plate on the surface of the base plate that is directly bonded to the other surface of the ceramic substrate and is opposite to the ceramic substrate.

According to the present invention, a circuit pattern metal made of aluminum or an aluminum alloy is spaced apart from a base plate made of aluminum or an aluminum alloy directly bonded to the peripheral edge portion and side surface of one surface of a ceramic substrate and substantially the entire surface of the other surface. Provided are a metal-ceramic bonded substrate and a method for manufacturing the same, which can downsize the base plate of the metal-ceramic bonded substrate in which a plate is directly bonded to one surface of the ceramic substrate.

1 is a plan view of an embodiment of a metal-ceramic bonded substrate according to the present invention; FIG. 1B is a bottom view of the metal-ceramic bonding substrate of FIG. 1A; FIG. FIG. 1B is a cross-sectional view of the metal-ceramic bonding substrate taken along the IC-IC line in FIG. 1B; 1B is a cross-sectional view of a mold used to manufacture the metal-ceramic bonded substrate of FIG. 1A; FIG. 2B is a plan view of the lower mold member of the mold of FIG. 2A; FIG. 2B is a bottom view of the upper mold member of the mold of FIG. 2A; FIG. 2B is a cross-sectional view showing a variation of the mold of FIG. 2A; FIG. 3B is a plan view of the lower mold member of the mold of FIG. 3A; FIG. 3B is a bottom view of the upper mold member of the mold of FIG. 3A; FIG. Figure 3B is an enlarged cross-sectional view of a retaining pin of the upper mold member of the mold of Figure 3A;

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of a metal-ceramic bonding substrate and a method for manufacturing the same according to the present invention will be described in detail with reference to the accompanying drawings.

1A-1C show embodiments of metal-ceramic bonding substrates according to the present invention, and FIGS. 2A-2C show molds used to manufacture the metal-ceramic bonding substrates.

As shown in FIGS. 1A to 1C, the embodiment of the metal-ceramic bonding substrate according to the present invention includes a ceramic substrate 10 having a substantially rectangular planar shape and a peripheral edge of the upper surface (surface on the circuit pattern side) of the ceramic substrate 10. A base plate (aluminum base plate) 12 made of aluminum or an aluminum alloy and having a substantially rectangular planar shape and being directly bonded to substantially the entire surface of the part, side surfaces, and bottom surface (rear surface), and a base directly bonded to the peripheral edge of the upper surface of the ceramics substrate 10. One or more (two in the illustrated embodiment) metal plates for circuit patterns (aluminum plates for circuit patterns) 14 made of aluminum or an aluminum alloy and directly bonded to the upper surface of the ceramic substrate 10 separated from the plate 12 are provided. ing.

In addition, a large number of columnar protrusions 12a (as radiation fins) are integrally formed on the bottom surface of the base plate 12 so as to protrude. Each columnar protrusion 12a has a substantially cylindrical shape or a substantially truncated cone shape (a shape obtained by cutting the upper end of a substantially cone substantially parallel to the bottom surface), and extends substantially perpendicularly to the bottom surface of the base plate 12. . In addition, the columnar projections 12a are arranged such that a plurality of rows of the columnar projections 12a arranged in a row at predetermined intervals are parallel to each other and adjacent rows of the columnar projections 12a are separated from each other by a half pitch (adjacent columnar projections). The center lines of the portions 12a (half the distance between the axial lines along which the columnar projections 12a extend)) are arranged so as to be displaced, and more columnar projections 12a are arranged while ensuring the spacing between the adjacent columnar projections 12a. However, other arrangements may be used as long as a large number of columnar protrusions 12a can be arranged while ensuring the intervals between adjacent columnar protrusions 12a.

In this embodiment of the metal-ceramic bonding substrate, the ceramic substrate 10 is placed in a mold 20 as shown in FIGS. It can be manufactured by pouring a molten aluminum or aluminum alloy into contact with the part to be contacted and cooling it.

As shown in FIG. 2A, the mold 20 is made of a (porous) gas-permeable (impermeable to molten metal) material such as carbon (porous) or porous metal, and has a lower mold member 22 and an upper mold member each having a substantially rectangular planar shape. It is composed of a member 24.

As shown in FIGS. 2A and 2B, on the upper surface of the lower mold member 22, the base plate 12 (the lower portion of the side surface side portion of the ceramic substrate 10 and the bottom surface (rear) side portion) is formed. (for base plate formation) concave portion (base plate forming portion) 22a is formed. The bottom surface of the base plate forming portion 22a is formed with recesses (columnar projection forming portions) 22b (for forming columnar projections) for forming a large number of columnar projections 12a. Further, on the bottom surface of the base plate forming portion 22a, a plurality of (two pairs in the illustrated embodiment) substrate support portions (longitudinal substrate support portions) having a substantially rectangular planar shape for supporting both ends in the longitudinal direction of the ceramic substrate 10 are provided. ) 22c, and a plurality of (two pairs in the illustrated embodiment) substrate support portions (width direction substrate support portions) 22d having a substantially rectangular planar shape for supporting both ends in the width direction of the ceramic substrate 10 are provided approximately from the bottom surface thereof. It is formed to protrude in the vertical direction. These substrate support portions 22c and 22d are stepped so as to have a substantially L-shaped cross section so as to abut on the peripheral portion of the bottom surface and side surfaces of the ceramic substrate 10 and support the ceramic substrate 10 at a predetermined position. is provided. Even if the ceramic substrate 10 is placed on these substrate supporting portions 22c and 22d, the peripheral edge portion of the upper surface (surface on the circuit pattern side) of the ceramic substrate 10, the side surface, and the bottom surface (rear surface) are substantially entirely surrounded by The base plate forming portion 22a is secured.

As shown in FIGS. 2A and 2C, on the bottom surface of the upper mold member 24, the upper portion of the side surface side portion of the base plate 12 (of the ceramic substrate 10) and the peripheral portion side portion of the upper surface (circuit pattern side surface) are provided. ) for forming a (base plate forming portion) 24a and a (circuit pattern forming) concave portion (circuit pattern forming portion) 24b for forming the circuit pattern metal plate 14. is formed. The circuit pattern metal plate forming portion 24b is separated from the base plate forming portion 24a so as to ensure insulation between (the circuit pattern side portion of) the base plate 12 and the circuit pattern metal plate 14. It's becoming

In the upper mold member 24, a base plate forming portion 24a and a circuit pattern metal plate forming portion 24b of the upper mold member 24 are fed from a molten metal pouring nozzle (not shown), and a base plate forming portion 22a of the lower mold member 22 (and A pouring port (not shown) for pouring molten metal is formed in the columnar projection forming portion 22b). In addition, in the upper mold member 24, the molten metal flow path 24c extending between the base plate forming portion 24a and the circuit pattern metal plate forming portion 24b and between the circuit pattern metal plate forming portions 24b (base plate forming portion 24a and the circuit pattern metal plate forming portion 24b). 1A and 1C show the metal-ceramic bonding substrate after removing the portion corresponding to the molten metal flow path 24c.

In order to use such a mold 20 to manufacture the metal-ceramic bonded substrate of the embodiment shown in FIGS. After placing 10 , upper mold member 24 is placed over lower mold member 22 . In this state, when molten aluminum or aluminum alloy is poured into the mold 20 and cooled, the base plate 12 is directly formed on substantially the entire surface of the upper surface (circuit pattern side) of the ceramic substrate 10, the side surfaces, and the bottom surface (rear surface). It is possible to manufacture a metal-ceramic bonded substrate in which the circuit pattern metal plate 14 is directly bonded to the ceramic substrate 10 while being bonded together (the portion on the circuit pattern side) of the base plate 12 . A plurality of recesses 12b corresponding to the substrate support portions 22c and 22d are formed in the base plate 12, and a part of the peripheral edge of the ceramic substrate 10 is exposed. - Has little effect on the reliability and thermal conductivity of the ceramic bonded substrate.

A metal-ceramic bonded substrate may also be manufactured using the mold 30 shown in FIGS. 3A-3D. In the upper mold member 34 of the mold 30, instead of the molten metal flow path 24c of the mold 20, a base plate forming portion 34a and a circuit pattern metal plate forming portion 34b are provided over the entire circumference of the circuit pattern metal plate forming portion 34b. and between the circuit pattern metal plate forming portions 34b. If the molten metal flow path 34c is formed in this way, the ceramic substrate 10 may float when the molten metal is poured into the mold 30. At least one (five in the illustrated embodiment) (substantially cylindrical) retaining pins 34d extend from the upper mold member 34 (located within the mold 30) in the portion of the member 34 corresponding to the melt channel 34c. ) protrudes toward the ceramic substrate 10 and comes into contact with the ceramic substrate 10 (or close to the ceramic substrate 10 at a distance of 0.3 mm or less (preferably 0.1 mm or less)). . Other configurations are substantially the same as those of the mold 20 shown in FIGS. 2A to 2C described above, so in FIGS. 3A to 3D, reference numerals 10 are added and descriptions thereof are omitted.

In addition, in the embodiment of the metal-ceramic bonding substrate and the manufacturing method thereof, a ceramic substrate containing aluminum nitride, alumina, silicon nitride or the like as a main component can be used as the ceramic substrate.

Further, after removing the metal-ceramic bonding substrate manufactured by the above-described method for manufacturing a metal-ceramic bonding substrate from the mold, the portion corresponding to the molten metal flow path of the mold is removed by machining or etching with a chemical solution. Remove. When removing the portion corresponding to the molten metal flow path by etching, etching may be performed after forming an etching resist on the surfaces of the circuit pattern metal plate and the base plate.

REFERENCE SIGNS LIST 10 ceramic substrate 12 base plate 12a columnar protrusion 12b recess 14 circuit pattern metal plate 20, 30 molds 22, 32 lower mold member 22a, 32a base plate forming recess (base plate forming portion)
22b, 32b columnar projection forming recess (columnar projection forming portion)
22c, 32c Longitudinal substrate support portions 22d, 32d Width direction substrate support portions 24, 34 Upper mold members 24a, 34a Base plate forming recesses (base plate forming portions)
24b, 34b circuit pattern forming recesses (circuit pattern metal plate forming portions)
24c, 34c Molten metal flow path 34d Holding pin

Claims (9)

A ceramic substrate is arranged in a mold so as to extend in a substantially horizontal direction, molten aluminum or an aluminum alloy is poured so as to come into contact with the surface of the ceramic substrate, and then the molten metal is cooled and solidified to obtain aluminum or aluminum. A base plate made of an alloy is formed over substantially the entire peripheral edge of the upper surface, the side surfaces, and the bottom surface of the ceramic substrate and is directly bonded to the ceramic substrate, and a metal plate for circuit patterns made of aluminum or an aluminum alloy is spaced apart from the base plate. A method for producing a metal-ceramic bonded substrate, characterized by forming the substrate on the upper surface of the ceramic substrate and directly bonding it to the ceramic substrate. The mold is composed of an upper mold member and a lower mold member, and the upper mold member includes a recess for forming a base plate having substantially the same shape and size as the outer shape of the upper portion of the base plate and the metal plate for circuit pattern. A circuit pattern forming recess having the same shape and size is formed, and a base plate forming recess having substantially the same shape and size as the outer shape of the lower side portion of the base plate is formed in the lower mold member, and the base A plurality of ceramic substrate support portions are protruded from the peripheral edge portion of the bottom surface of the plate forming recess, and the ceramic substrate support portions support the peripheral edge portion of the bottom surface of the ceramic substrate, The method for producing a metal-ceramic bonding substrate according to claim 1. A recess shallower than the base plate forming recess and the circuit pattern forming recess is formed as a molten metal flow path between the base plate forming recess and the circuit pattern forming recess of the upper mold member. Item 3. A method for producing a metal-ceramic bonding substrate according to item 2. A plurality of the circuit pattern forming recesses are formed, the circuit pattern forming recesses are arranged apart from each other, and the molten metal flow path extends over the entire circumference of the circuit pattern forming recesses and the base plate forming recesses. 4. The method for manufacturing a metal-ceramic bonding substrate according to claim 3 , wherein the substrate is formed so as to extend between the circuit pattern forming recesses and between the circuit pattern forming recesses . 5. The metal-ceramics according to claim 4 , wherein holding pins for holding the ceramic substrate placed in the mold are protruding from the portion of the upper mold member corresponding to the molten metal flow path. A method for manufacturing a bonded substrate. When the base plate is formed and directly bonded to the ceramic substrate, a large number of columnar projections projecting apart from each other are formed integrally with the base plate on the bottom surface of the base plate, 6. The method for producing a metal-ceramic bonded substrate according to claim 1 . A ceramic substrate, a base plate made of aluminum or an aluminum alloy directly bonded to a peripheral edge portion and a side surface of one surface of the ceramic substrate and substantially the entire surface of the other surface of the ceramic substrate, and one surface of the ceramic substrate spaced apart from the base plate. A circuit pattern metal plate made of aluminum or an aluminum alloy directly bonded to a metal-ceramic bonded substrate, characterized in that a part of the peripheral edge of the other surface of the ceramic substrate is exposed to the outside. 8. The metal-ceramic bonding substrate according to claim 7, wherein a part of the side surface of said ceramic substrate is exposed to the outside. A plurality of columnar projections projecting apart from each other are formed integrally with the base plate on the surface opposite to the ceramic substrate of the portion of the base plate that is directly bonded to the other surface of the ceramic substrate. The metal-ceramic bonding substrate according to claim 7 or 8, characterized by:

Images