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    发明专利
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    公开(公告)号:DE1271235B

    公开(公告)日:1968-06-27

    申请号:DE1271235

    申请日:1964-12-09

    Applicant: IBM

    Abstract: 1,015,827. Printed circuits. INTERNATIONAL BUSINESS MACHINES CORPORATION. Nov. 30, 1964 [Dec. 23, 1963], No. 48526/64. Heading H1R. In a method of forming a conductive connection between conductive sheets 12, 14 clad on opposite faces of a dielectric sheet 10, an aperture is produced in sheet 12 by a photo-etching process, then a registering aperture is etched in sheet 10, after which a layer 22 of copper is electrolytically deposited on layer 12 and inside the apertures, wherein it contacts the inner surface 20 of layer 14. The area to be electroplated is first seeded with an electroless deposit of palladium chloride, and the copper may be coated with silver, nickel, lead-tin solder &c. Subsequently, desired circuit patterns are formed in layers 12-22 and 14. When dielectric layer 10 is of polyethylene-terephthalate, or phenolic or epoxy material, hot concentrated sulphuric acid is used to etch the aperture therein; the glass fibres in epoxy glass require hot concentrated sodium hydroxide o hydrofluoric acid as etchant. When multilayer circuit boards are used, undercutting of dielectric layers is minimized by etching each layer independently with intermediate rinsings. Instead of plating the apertures, solder balls may be inserted and applied by heating. To etch a hole in a dielectric sheet having one surface only conductor-clad, the unclad surface is masked, except at the site of the hole, with a metallic resist.

    A METHOD OF BRAZING ADJOINING SURFACES OF ELEMENTS

    公开(公告)号:DE3170758D1

    公开(公告)日:1985-07-04

    申请号:DE3170758

    申请日:1981-10-29

    Applicant: IBM

    Abstract: Brazing of metallic elements to an electronic circuit board carrying a plurality of chips requires brazing materials which remain strong at high temperatures used to remove and replace the chips attached by solder balls to the board. According to the present invention flanges and pins (19) are brazed to the board (10) with a gold tin brazing solder (15) which is modified during brazing by addition of a Group IB metal (13) to promote formation of the higher melting point β phase of the solder and a Group VIII metal (14) to drawtin out of the melt by gettering. The melting temperature of the brazing solder is raised substantially during brazing to a value above the melting temperature of the solder balls attached to the chips.

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