JP2008098662A - Method of manufacturing metal-ceramic bonded circuit substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a metal-ceramic bonded circuit substrate capable of forming a fine pattern even when the metal plate for the circuit is thick and reducing the etching process time in bonding the metal plate for the circuit to a ceramic substrate by contacting melt of the metal to the ceramic substrate, cooling to solidify the metal thereafter, and forming the metal circuit-plate of a desired circuit pattern by etch-processing the metal plate for the circuit. <P>SOLUTION: The method comprises a step of bonding the metal plate 12 for the circuit to one surface of the ceramic substrate 10 and bonding a metal base plate 14 to the other surface of the substrate 10 by contacting melt of the metal to both surfaces of the ceramic substrate 10 and cooling the metal to solidify; a step of printing an etching resist 16 on the metal plate 12 for the circuit; and a step of allowing the shape of the metal plate 12 for the circuit bonded to the ceramic substrate 10 to resemble to a predetermined circuit pattern in forming the metal circuit-plate 12 of a desired pattern by performing an etching process. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a metal-ceramic bonding circuit board in which a metal circuit board is bonded to a ceramic substrate, and more particularly to a method for manufacturing a metal-ceramic bonding circuit board used for a power module or the like.

  Conventionally, as a method of manufacturing a metal / ceramic bonding circuit board used for a power module or the like, a metal plate is bonded to a ceramic substrate by pouring a molten metal onto the ceramic substrate and then cooling and solidifying, followed by screen printing. A metal-ceramic bonding circuit board having a metal circuit board having a desired circuit pattern is manufactured by printing an etching resist having a desired pattern shape by performing an etching process to form a circuit pattern and then removing the resist. There is a known method (see, for example, Patent Document 1).

JP 2002-76551 A (paragraph numbers 0030 and 0048)

  However, in the metal-ceramic bonding circuit board used for power modules and the like, the thickness of the metal circuit board is several hundred μm or more, and the metal circuit board of the printed circuit board that uses ordinary paper or glass epoxy as an insulating material. Since the thickness is several tens of times the thickness, the method disclosed in Patent Document 1 has a problem that the length of the skirt formed by the etching process and the amount of side etching increase. For example, when the thickness of the metal circuit board is 0.4 to 0.6 mm, the insulating distance between patterns (distance between bottoms) is the shortest when an etching resist having a distance between patterns of 0.5 mm is formed. However, it is as large as about 0.9 to 1.4 mm, and the distance between the tops of the metal circuits is further increased. When the metal circuit board becomes thicker, there is a problem that these distances become larger. Further, the thicker the metal circuit board is, the longer the etching process time is, the more man-hours are required, the cost is increased, and the resistance of the etching resist must be taken into consideration.

  Therefore, in view of such a conventional problem, the present invention joins a circuit metal plate to a ceramic substrate by bringing the molten metal into contact with the ceramic substrate and then cooling and solidifying the metal plate. When forming a metal circuit board having a desired circuit pattern by etching, a fine pattern can be formed even if the circuit metal plate is thick, and the etching time can be shortened. An object of the present invention is to provide a method for manufacturing a circuit board.

  As a result of diligent research to solve the above-mentioned problems, the present inventors have previously determined the shape of the circuit metal plate to be bonded to the ceramic substrate by bringing the molten metal into contact with the ceramic substrate and then solidifying it by cooling. By making the shape similar to the pattern, it is possible to shorten the etching processing time when forming a metal circuit board having a desired circuit pattern and to form a fine pattern even when the circuit metal plate is thick. As a result, the present invention has been completed.

  That is, in the method for manufacturing a metal / ceramic bonding circuit board according to the present invention, a metal plate is bonded to at least one surface of a ceramic substrate by bringing the molten metal into contact with at least one surface of the ceramic substrate and then solidifying by cooling. In the method of manufacturing a metal-ceramic bonded circuit board by etching the metal plate to form a metal circuit board having a desired circuit pattern, the shape of the metal plate bonded to the ceramic substrate is similar to the circuit pattern in advance. It is characterized by making it a shape.

  In this method of manufacturing a metal / ceramic bonding circuit board, it is preferable to make the thickness of the metal plate to be bonded to the ceramic substrate other than the part substantially corresponding to the circuit pattern thinner than the thickness of the part substantially corresponding to the circuit pattern, It is more preferable to make it 1/2 or less of the thickness of the portion substantially corresponding to the circuit pattern. In this case, it is preferable that the thickness of the portion substantially corresponding to the circuit pattern is 0.1 to 0.3 mm.

  Further, in the above-described method for manufacturing a metal-ceramic bonding circuit board, the ceramic substrate is placed in a mold having a recess having a shape similar to a circuit pattern, and the molten metal is brought into contact with at least one surface of the ceramic substrate. It is preferable to join the metal plate to at least one surface of the ceramic substrate by pouring into the concave portion of the ceramic substrate and then cooling and solidifying. In this case, it is preferable to make the depth of the concave portion of the mold other than the portion substantially corresponding to the circuit pattern smaller than the depth of the portion substantially corresponding to the circuit pattern. It is preferably 1 to 0.3 mm.

  The method for producing a metal / ceramic bonding circuit board according to the present invention includes the steps of placing a ceramic substrate in a mold, pouring molten metal into the mold so as to contact at least one surface of the ceramic substrate, and cooling. A metal plate is bonded to at least one surface of the ceramic substrate by solidification and the metal plate is etched to form a metal circuit plate having a desired circuit pattern. In the method, a mold having a recess having a shape similar to a circuit pattern is prepared, and a molten metal is poured into the recess of the mold. In this case, it is preferable to make the depth of the concave portion of the mold other than the portion substantially corresponding to the circuit pattern smaller than the depth of the portion substantially corresponding to the circuit pattern. It is preferably 1 to 0.3 mm.

  In the method for manufacturing a metal-ceramic bonding circuit board described above, when the molten metal is brought into contact with at least one surface of the ceramic substrate, the molten metal is brought into contact with the other surface of the ceramic substrate, and is cooled and solidified. A metal member may be bonded to the other surface of the substrate. Moreover, it is preferable that a metal molten metal is a molten metal which has aluminum as a main component.

  In the metal-ceramic bonding circuit board manufacturing method according to the present invention, the shape of the metal plate bonded to the ceramic substrate is not the same shape as the circuit pattern, but is similar to the metal plate bonded to the ceramic substrate. This is because it is difficult to form the same shape as the circuit pattern with a predetermined dimensional accuracy. In addition, in order to make the shape of the metal plate the same as the circuit pattern, it is necessary to form pouring holes for forming each circuit pattern by casting in the mold, which makes the mold complicated. This is because it is difficult to manufacture a simple mold. Therefore, in this specification, “a shape similar to a circuit pattern” means a shape that is as similar to a circuit pattern as possible by casting. In particular, if a metal plate is formed between adjacent patterns and the thickness of this portion is reduced, it is not necessary to form a pouring port for forming each circuit pattern in the mold, and the shape of the metal plate can be reduced. The shape can be similar to a circuit pattern.

  According to the present invention, the molten metal is brought into contact with the ceramic substrate and then cooled and solidified to join the circuit metal plate, and the circuit metal plate is etched to form a metal circuit plate having a desired circuit pattern. In the case of forming, by making the shape of the circuit metal plate bonded to the ceramic substrate in advance a shape similar to the circuit pattern, a fine pattern can be formed even when the circuit metal plate is thick, and a desired circuit can be formed. The etching processing time for forming the patterned metal circuit board can be greatly shortened.

  Embodiments of a method for producing a metal / ceramic bonding circuit board according to the present invention will be described below with reference to the accompanying drawings.

  First, a ceramic substrate is placed in a mold, and molten metal is poured into it and cooled and solidified, so that one surface metal base plate of the ceramic substrate is bonded and the other surface is bonded to the circuit metal plate. -Manufacture ceramic bonded substrates.

  An example of a lower mold member of a mold used for manufacturing the metal-ceramic bonding substrate is shown in FIG. As shown in FIG. 1A and FIG. 1B, the lower mold member 100 includes a bottom surface portion 100a having a substantially rectangular planar shape, and side walls extending upward in the vertical direction from the peripheral edge portion of the bottom surface portion 100a. Part 100b. On the upper surface of the bottom surface portion 100a of the lower mold member 100, one or a plurality of recesses 100c (two are shown in FIGS. 1 (a) and 1 (b)) having stepped side walls are formed. . Each of the recesses 100c has a planar shape similar to the circuit pattern of the metal circuit board and one or a plurality of depths substantially equal to the thickness of the metal circuit board (4 in FIGS. 1A and 1B). And one or a plurality of circuit metal plate forming portions 100d (shown in FIG. 1), which are formed adjacent to the upper portion of the circuit metal plate forming portion 100d and have substantially the same shape and size as the ceramic substrate. ) And the ceramic substrate housing portion 100e shown in FIG. 1 (b). In the circuit metal plate forming portion 100d, as shown in FIG. 1C, the depth of the portion between the adjacent patterns is shallower by d than the depth of the portion substantially corresponding to the circuit pattern of the metal circuit plate. Of the space defined inside by covering the upper mold of the lower mold member 100 with an upper mold (not shown) having a substantially rectangular plane shape, the portion excluding the recess 100c of the lower mold member 100 is a metal base. It is the plate forming part 100f. The upper mold is formed with a pouring port (not shown) for pouring the molten metal into the mold. Further, the lower mold member 100 is formed with a molten metal passage (not shown) extending between the metal base plate forming portion 100f and the circuit metal plate forming portion 100d, and the ceramic substrate is placed in the ceramic substrate housing portion 100e. The metal base plate forming portion 100f and the circuit metal plate forming portion 100d communicate with each other even when they are housed.

  After the ceramic substrate is accommodated in the ceramic substrate accommodating portion 100e of the lower mold member 100 of this mold, the molten metal is poured into the metal base plate forming portion 100f, and is used for the circuit via the molten metal flow path (not shown). The metal base plate 14 is directly bonded to one surface of the ceramic substrate 10 as shown in FIG. 2A by filling the metal plate up to the metal plate forming portion 100d and then cooling to solidify the metal melt. In addition, an integrated metal / ceramic bonding substrate in which the circuit metal plate 12 having a shape similar to the circuit pattern is directly bonded to the other surface is obtained.

  Next, as shown in FIG. 2B, an etching resist 16 having a predetermined shape is printed on the surface of the circuit metal plate 12, and an etching process is performed with an etching solution such as a ferric chloride solution to obtain a desired circuit. After forming the metal circuit board 12 having a pattern, the resist 16 is peeled off to obtain a metal-ceramic bonding circuit board having a metal circuit board having a desired circuit pattern, as shown in FIG.

  Hereinafter, embodiments of the method for producing a metal / ceramic bonding circuit board according to the present invention will be described in detail.

[Example 1]
On the bottom surface of the lower mold member, the thickness of the portion substantially corresponding to the circuit pattern is 0.6 mm, the thickness of the portion between the adjacent patterns is 0.3 mm, and the distance between them is 0.8 mm. A circuit metal plate forming portion, which is a recess having a shape and size substantially equal to that of the circuit metal plate (see FIG. 3A), is formed adjacent to the upper portion of the circuit metal plate forming portion. A ceramic substrate housing portion which is a concave portion having a shape and size substantially equal to a ceramic substrate having a size of 5 mm × 40 mm × 0.635 mm is formed, and a metal base plate forming portion is adjacent to the upper portion of the ceramic substrate housing portion. A carbon mold was formed in which a molten metal flow path formed between the metal base plate forming portion and the circuit metal plate forming portion was formed.

  An aluminum nitride substrate having a size of 32.5 mm × 40 mm × 0.635 mm is accommodated in the ceramic substrate accommodating portion of the lower mold member of the mold, and the upper mold is covered and sealed. As shown in FIG. 3 (a), the molten metal is poured into the metal plate, filled with the molten metal to the circuit metal plate forming portion through the molten metal flow path, and then cooled to solidify the molten metal. The metal base plate 14 was directly bonded to one surface of the ceramic substrate 10, and an integrated metal-ceramic bonding substrate was obtained in which the circuit metal plate 12 having a shape similar to the circuit pattern was directly bonded to the other surface.

  As shown in FIG. 3A, an etching resist 16 is printed on the surface of the metal plate for circuit of the metal-ceramic bonding substrate with a spacing of 1.2 mm between adjacent patterns, and etched with a ferric chloride solution. After processing to form a metal circuit board having a desired circuit pattern, the etching resist 16 is peeled off, and the distance between the pattern bottoms of adjacent patterns (insulation distance) is as shown in FIG. A metal-ceramic bonding circuit board having a metal circuit board having a desired circuit pattern of 1.6 mm was obtained.

[Examples 2 to 4]
The size of the ceramic substrate was 32.5 mm × 74 mm × 0.635 mm (Example 2), 32.5 mm × 40 mm × 0.25 mm (Example 3), 32.5 mm × 74 mm × 0.25 mm (Example 4) A metal-ceramic bonding circuit board was obtained by the same method as in Example 1 except that the size of the ceramic substrate housing portion of the lower mold member was made substantially equal to the size of each ceramic substrate.

[Examples 5 to 8]
A metal-ceramic bonding circuit board was obtained by the same method as in Examples 1 to 4, except that the ceramic substrate was an alumina substrate.

[Example 9]
As shown in FIG. 4 (a), the embodiment is different except that the interval between adjacent patterns of the circuit metal plate 12 is 0.3 mm and the interval of the etching resist 16 printed on the adjacent pattern is 0.5 mm. 4, a metal-ceramic bonding having a metal circuit board 12 having a desired circuit pattern with a distance (insulation distance) between adjacent pattern bottoms of 1.0 mm, as shown in FIG. A circuit board was obtained.

[Examples 10 to 12]
The size of the ceramic substrate was 32.5 mm × 74 mm × 0.635 mm (Example 10), 32.5 mm × 40 mm × 0.25 mm (Example 11), 32.5 mm × 74 mm × 0.25 mm (Example 12) A metal-ceramic bonding circuit board was obtained by the same method as in Example 1 except that the size of the ceramic substrate housing portion of the lower mold member was made substantially equal to the size of each ceramic substrate.

[Examples 13 to 16]
A metal-ceramic bonding circuit board was obtained by the same method as in Examples 9 to 12 except that the ceramic substrate was an alumina substrate.

[Comparative Examples 1 to 16]
A metal-ceramic bonding circuit board was obtained by the same method as in Examples 1 to 8, except that the depth of the circuit metal plate forming part was set to a constant depth of 0.6 mm.

  In Comparative Examples 1 to 16, the etching time was about 30 minutes, but in Examples 1 to 16, the etching time was about 15 minutes, and in Examples 1 to 16, it was found that the etching time can be significantly shortened. Further, in Examples 1 to 8 in which the distance between the etching resists 16 printed on the adjacent patterns is 1.2 mm, a desired circuit pattern having an insulation distance (distance between the pattern bottoms) of 1.6 mm can be formed. However, similarly, in Comparative Examples 1 to 8 in which the distance between the etching resists was 1.2 mm, the insulation distance was 2.1 mm, and a desired circuit pattern could not be formed. Furthermore, in Examples 9 to 16 in which the interval between the etching resists 16 printed on the adjacent patterns was 0.5 mm, a desired fine pattern with an insulation distance of 1.0 mm could be formed. In Comparative Examples 9 to 16 in which the distance between them was 0.5 mm, the insulation distance was 1.4 mm, and a desired fine pattern could not be formed.

It is a figure which shows the lower mold member of the casting_mold | template used for embodiment of the manufacturing method of the metal-ceramics junction circuit board by this invention, Fig.1 (a) is a top view, FIG.1 (b) is FIG. BB sectional drawing of FIG.1, FIG.1 (c) is the partially expanded view of FIG.1 (b). Sectional drawing which shows the manufacturing process of embodiment of the manufacturing method of the metal-ceramics junction circuit board by this invention. The figure explaining the process of manufacturing a metal-ceramics junction circuit board in Examples 1-8. The figure explaining the process of manufacturing a metal-ceramics bonded circuit board in Examples 9-16.

Explanation of symbols

10 Ceramic substrate 12 Metal plate for circuit (metal circuit plate)
14 Metal base plate 16 Etching resist 100 Lower mold member 100a Bottom surface portion 100b Side wall portion 100c Recessed portion 100d Circuit metal plate forming portion 100e Ceramic substrate housing portion 100f Metal base plate forming portion

Claims (10)

A metal plate is bonded to at least one surface of the ceramic substrate by bringing the molten metal into contact with at least one surface of the ceramic substrate and then cooled and solidified, and the metal plate is etched to form a metal having a desired circuit pattern. In a method of manufacturing a metal-ceramic bonded circuit board by forming a circuit board, the metal plate bonded to the ceramic substrate is shaped in advance to be similar to a circuit pattern. Manufacturing method. 2. The thickness of the metal plate to be bonded to the ceramic substrate other than a portion substantially corresponding to the circuit pattern is made thinner than a thickness of a portion substantially corresponding to the circuit pattern. Manufacturing method of metal-ceramic bonding circuit board. The thickness of a portion of the metal plate to be bonded to the ceramic substrate other than a portion substantially corresponding to the circuit pattern is set to ½ or less of a thickness of a portion substantially corresponding to the circuit pattern. 2. A method for producing a metal / ceramic bonding circuit board according to 1. 4. The method for manufacturing a metal / ceramic bonding circuit board according to claim 2, wherein a thickness of a portion substantially corresponding to the circuit pattern is 0.1 to 0.3 mm. The ceramic substrate is placed in a mold having a recess having a shape similar to the circuit pattern, and the molten metal is poured into the recess of the mold so as to contact at least one surface of the ceramic substrate, and then cooled. The method for manufacturing a metal / ceramic bonding circuit board according to claim 1, wherein the metal plate is bonded to at least one surface of the ceramic substrate by solidifying the substrate. After the ceramic substrate is placed in the mold, the molten metal is poured into the mold so as to be in contact with at least one surface of the ceramic substrate, and then cooled and solidified to form a metal plate on at least one surface of the ceramic substrate. In a method of manufacturing a metal-ceramic bonding circuit board by bonding and etching the metal plate to form a metal circuit board having a desired circuit pattern, a mold having a recess having a shape similar to the circuit pattern is prepared. A method for producing a metal / ceramic bonding circuit board, comprising pouring a molten metal into the recess of the mold. The metal-ceramic according to claim 5 or 6, wherein a depth of the concave portion of the mold other than a portion substantially corresponding to the circuit pattern is made shallower than a depth of a portion substantially corresponding to the circuit pattern. A method for manufacturing a bonded circuit board. 8. The method of manufacturing a metal / ceramic bonding circuit board according to claim 7, wherein a depth of a portion substantially corresponding to the circuit pattern is 0.1 to 0.3 mm. When the molten metal is brought into contact with at least one surface of the ceramic substrate, the molten metal is brought into contact with the other surface of the ceramic substrate, and is cooled and solidified to form a metal member on the other surface of the ceramic substrate. The method for producing a metal / ceramic bonding circuit board according to claim 1, wherein: The method for producing a metal / ceramic bonding circuit board according to claim 1, wherein the molten metal is a molten metal containing aluminum as a main component.

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