JPH114072A - Electronic circuit device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a solder connecting metal layer of high reliability without using plating or sputtering by a method wherein a metal piece wettable to solder is additionally provided to the solder connecting sintered metal part of a board and bonded by thermocompression to form a solder connecting metal layer. SOLUTION: A sintered board composed of copper and glass ceramic 1 is prepared. Many holes 3 are generated by sintering inside a copper wiring and the surface of a solder connecting metal layer. Prescribed copper pieces 5 are provided onto a heat-resistant sheet corresponding to a solder connecting pattern, the heat-resistant sheet is placed on the solder connecting pattern of the sintered board, and the sintered board and the heat-resistant sheet are heated and pressed from above. By this setup, the copper pieces 5 and copper contained in the sintered board are mutually diffused into each other to form the copper pieces 5 and the sintered board into one piece. Then, the heat-resistant sheet is separated off. Copper formed as above is kept free from holes, and an excellent soldering connection can be realized. A solder connecting metal layer can be formed on one or both sides of the sintered board.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an electronic circuit device using a ceramic wiring board for an electronic circuit device.

[0002]

2. Description of the Related Art A substrate formed of a metal part for electric wiring and a surrounding ceramic is used as a wiring substrate of an electronic circuit device. The latest technology of its composition and usage is described in, for example, IBM Journal of Research and Development, September, 1992, p.
Described on the page. Usually, a metal layer for solder connection is formed on the solder connection terminal portion of these substrates by plating or sputtering.

[0003]

However, formation of a metal layer for solder connection by plating or sputtering is costly. In addition, it is not preferable in terms of connection reliability to directly solder the metal part of the sintered substrate without forming the solder connection metal layer.

[0004] Because the metal portion of the sintered substrate has holes on the surface and inside due to the shrinkage of the metal during sintering, the solder penetrates into these holes, and the solder is partially quickly moved to the bottom of the metal layer for solder connection. To reach a state of direct contact with the ceramic, which significantly reduces the solder connection strength. For this reason, there is a disadvantage that the thickness of the metal layer required for connection cannot be designed.

[0005] Further, holes on the surface of the metal layer of the sintered substrate may cause voids in the solder, which may lower the connection reliability.

An object of the present invention is to provide an electronic circuit device using a substrate on which a highly reliable metal layer for solder connection is formed without plating or sputtering.

[0007]

The object of the present invention is achieved by newly arranging a metal piece wettable by solder on a sintered metal part for solder connection of a substrate, and by heating and pressing to form a metal layer for solder connection. it can.

Alternatively, the metal piece may be connected to the metal part for solder connection of the substrate with a small amount of solder, and then connected to the metal piece using a sufficient amount of solder.

Further, by supplying the solder to the metal piece in advance, the soldering process can be simplified.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION

(Embodiment 1) A sintered substrate made of copper and glass ceramic is prepared. FIG. 1 schematically shows a part of a cross section of the substrate. FIG. 2 shows a part of the soldering pattern on the surface of the substrate.

The inside of the copper wiring and the surface for solder connection have many holes by sintering. In correspondence with the solder connection pattern of FIG. 2, a copper piece consisting of 5/100 mm thick is
Prepare what is placed on the heat-resistant sheet. This is shown in FIG. This is placed on the solder connection pattern of the sintered substrate and heated to about 650 degrees Celsius while applying pressure from above. Thereby, the copper piece and the copper of the sintered substrate are mutually diffused and integrated.

Next, only the heat-resistant sheet is peeled off. The copper thus formed has no holes, and good solder connection is possible. FIG. 4 schematically shows a cross section of the substrate formed by this method.

The formation of the solder connection metal layer by this method can be performed not only on one side of the sintered substrate but also on both sides. Also, the copper pieces need not necessarily be applied to all of the soldering patterns on the substrate, and may be applied, for example, only to portions that are likely to pose a problem in reliability.

Next, both the sintered board with copper pieces and the conventional sintered board were soldered, and the state of internal connection was examined from cross-sectional observation. The corresponding parts of the electronic component and the substrate are tin 6
The connection was made at 230 degrees Celsius using a solder consisting of 3 weight percent and 37 weight percent lead.

FIG. 5 is a schematic view of a solder cross section of a sintered substrate with copper pieces, and FIG. 6 is a schematic view of a solder cross section of a conventional sintered substrate for comparison. In FIG. 5, there is no void inside the solder,
In addition, the amount of copper consumed is substantially constant irrespective of the position, and the connection is good. On the other hand, in FIG. 6, a large number of voids exist inside the solder, which deteriorates the connection quality.
There is a portion where the copper has been partially consumed and the solder has penetrated into the holes in the copper. In this portion, the adhesive strength with the underlying glass ceramic is significantly reduced. Thereby, the effect of the present invention was confirmed.

Although a form using copper as a metal piece to be bonded is shown here, nickel or another metal or alloy may be used instead of copper. Also, the solder metal portion of the sintered substrate need not be copper. Further, the solder is not limited to Sn37Pb, and solders having various melting points can be applied as needed.

(Embodiment 2) As in Embodiment 1, a sintered substrate made of copper and glass ceramic is prepared. FIG. 1 schematically shows a part of a cross section of the substrate. FIG. 2 shows a part of the soldering pattern on the surface of the substrate.

This time, the present method is applied only to the peripheral solder sealing portion of the pattern of FIG. First, Sn3A having a thickness of 3/100 mm is formed on the lower surface of a copper piece having the same shape as the peripheral pattern of FIG.
g solder and 2 mm thick S
The n3Ag solder is supplied in advance by a plating method or the like. This is placed at a predetermined position on the sintered substrate, and a sealing frame is further placed thereon to melt the solder at about 250 ° C. and connect.

Next, the cross section of the solder connection was examined in the same manner as in the first embodiment. The resulting sketch is shown schematically in FIG. There is no portion where the solder reaches the ceramic, and a connection excellent in reliability is obtained. Thereby, the effect of the present invention was confirmed.

Here, the form in which copper is used as the metal piece to be bonded is shown, but nickel, other metals and alloys may be used instead of copper. Also, the solder metal portion of the sintered substrate need not be copper. Further, the solder is not limited to Sn37Pb, and solders having various melting points can be applied as needed.

[0021]

According to the present invention, a metal layer for solder connection can be formed at low cost without plating or spattering, whereby the reliability of solder connection can be improved.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of a part of a cross section of a sintered substrate.

FIG. 2 is a solder connection surface pattern diagram of a sintered substrate.

FIG. 3 is a pattern diagram of a copper piece arranged on a heat-resistant sheet.

FIG. 4 is a conceptual diagram of a part of a cross section of a substrate after copper pieces are bonded.

FIG. 5 is a conceptual diagram of a cross section in which a copper piece adhesive layer-attached substrate is connected by soldering.

FIG. 6 is a conceptual diagram of a cross section directly connected to a conventional board by soldering.

FIG. 7 is a conceptual diagram of a cross section in which a copper piece adhesive layer-attached substrate is connected by soldering.

[Explanation of symbols]

1 ... ceramic, 2 ... sintered metal part for solder connection, 3 ...
Hole, 4 ... heat-resistant sheet, 5: copper piece, 6: electronic component,
7: Solder, 8: Intermetallic compound, 9: Metal layer disappeared portion, 10: Void, 11: Frame.

Claims (3)

[Claims] 1. A sintered substrate having ceramic and metal as main constituents, wherein a sintered metal portion for solder connection has a portion to which a metal piece which is wetted by solder is bonded after sintering. An electronic circuit device characterized by the above-mentioned. 2. A sintered substrate having ceramic and copper or a copper alloy as main components, wherein a sintered metal portion for solder connection has a portion to which a metal piece wet with solder after sintering is bonded. An electronic circuit device comprising: 3. The electronic circuit device according to claim 1, wherein a metal piece supplied with solder on both sides or one side is used.