Metal fusion bonding – Including means to apply flux or filler to work or applicator
Patent
1998-06-29
2000-08-01
Ryan, Patrick
Metal fusion bonding
Including means to apply flux or filler to work or applicator
228 41, 228118, 228254, B23K 100, H01L 2160, H05K 334
Patent
active
060953977
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a solder deposit carrier for the selective soldering of terminal areas of a substrate, comprising on an electrically conductive, non-wettable or wetting-inhibiting coating a transfer mask of an electrically isolating, non-solderable material which exposes the coating in the area of mask openings, in which the mask openings serve to accommodate solder deposits electroplated to the coating.
BACKGROUND OF THE PRIOR ART
There is known from U.S. Pat. No. 5,217,597 a method for the selective soldering of terminal areas of a substrate, in which use is made for the transfer of solder deposits onto the terminal areas of the substrate of a solder deposit carrier which comprises for accommodating and transferring the solder deposits a transfer mask with mask openings. For the electroplating of the solder deposits in the mask openings, the latter are disposed on an electrically conductive coating. After deposition of the solder deposits in the mask openings the solder deposits are transferred onto terminal areas of a substrate that are to be soldered, namely by the solder deposit carrier being disposed above the substrate in such a way that the solder deposits are located in an overlap ply with the terminal areas to be soldered. The actual transfer of the solder deposits onto the terminal areas located directly below them takes place by means of a so-called "solder reflow", in which the solder deposits in the mask openings in the transfer mask are heated up beyond the melting temperature of the solder and in so doing wet the terminal area to be soldered. A stripping of the melted solder deposits from the coating at the bottom of the mask openings is made possible in the case of the known solder deposit carrier by the fact that the coating consists of a material which is on the one hand electrically conductive, but on the other, however, also non-solderable, and hence not wettable.
For the coating of the solder deposit carrier there is given in U.S. Pat. No. 5,217,597 a non-wettable material which is known under the title ITO coating and comprises an indium/tin oxide alloy.
During tests with the known solder deposit carrier it was found that the known coating, in which both the function of a galvanic carrier layer and the function of a non-wettable contact layer for the solder deposits in the mask openings is performed by one and the same layer material, leads to disadvantages in the carrying out of the known method. In particular it was found that because of the relatively high electric layer resistance of the known ITO coating an electroplating of solder deposits on the solder deposit carrier is not processable in the case of larger solder deposit carriers, such as are required for example in the processing of structures distributed over a large area, for instance semiconductor wafers, by virtue of the high voltage drops occurring.
Moreover, in the case of the solder deposit carrier known from U.S. Pat. No. 5,217,597 the mask openings in the transfer mask are so proportioned that during the electroplating only one part of the solder deposits can be accommodated within the mask openings, while another part of the solder deposits extends outside the mask openings and their edges in an overlap, with the result that the current-carrying cross-section of the solder deposits changes during the electroplating operation in the outer part of the solder deposits. If said change in the current-carrying cross-section is not compensated by a suitable, sophisticated process control, the result is an irregular solder electroplating and a correspondingly uncontrolled structure composition in the solder deposits, which impedes in particular the formation of eutectic solder bumps or the exact solder composition in general.
OBJECT OF THE INVENTION
The present invention is based on the object of proposing a solder deposit carrier which can also be used for the selective soldering of substrates covering a wider area.
This object is achieved by a solder deposit carrier with th
REFERENCES:
patent: 4463059 (1984-07-01), Bhattacharya et al.
patent: 4832255 (1989-05-01), Bickford et al.
patent: 4908689 (1990-03-01), McBride et al.
patent: 5063658 (1991-11-01), Wild
patent: 5072873 (1991-12-01), Liu et al.
patent: 5171712 (1992-12-01), Wang et al.
patent: 5217597 (1993-06-01), Moore et al.
patent: 5376584 (1994-12-01), Agarwala
patent: 5391517 (1995-02-01), Gelatos et al.
patent: 5550427 (1996-08-01), Hayashi
patent: 5709957 (1998-01-01), Chiang et al.
patent: 5736456 (1998-04-01), Akram
patent: 5775569 (1998-07-01), Berger et al.
patent: 5851911 (1998-12-01), Farnworth
patent: 5903058 (1999-05-01), Akram
IBM Technical Disclosure Bulletin, vol. 36, No. 3, Mar. 1993, New York US, p. 103-104, XP000354716 "Hydrogen Overvoltage Suppression in Solder Decal Plating".
IBM Technical Disclosure Bulletin, vol. 36, No. 4, Apr. 1993, New York US, pp. 223-224, XP000364495 "Enhanced solder bump retention on solder decals".
Patent Abstracts of Japan vo.18, No. 573 (E-1624), Nov. 2, 1994 and JP, A,06 216135 (Toshiba Corp), Aug. 5, 1994.
Chmiel Gerhard
Wolf Jurgen
Fraunhofer-Gesellschaft zur Forderung der ange-wandten Forschung
Ryan Patrick
Stoner Kiley
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