High melting point process for Au:Sn:80:20 brazing alloy for chip carriers
AssigneeInternational Business Machines Corporation
InventorsNorman G. Ainslie, James E. Krzanowski, Paul H. Palmateer
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Abstract
Brazing of elements to electronic chip carrying substrates requires brazing materials strong at high temperatures used to remove and replace chips. Flanges and pins are brazed with Au:Sn brazing alloys modified during brazing by addition of Group IB metal to the brazing material to promote formation of the higher melting point .beta. phase of the alloy and a Group VIII metal to draw Sn out of the melt by gettering, also to promote formation of the .beta. phase of the alloy and to thicken the braze material. An Au preform is plated with Ni and juxtaposed with surfaces to be brazed and the brazing materials to add Ni and Au to the melt almost simultaneously.
Claims18
In a process of brazing metallic elements to a substrate in a thin film electronic circuit package wherein said substrate carries said metallic elements and solder connections supporting a plurality of chips on said substrate, with the metallic elements brazed to said substrate by means of a gold tin brazing solder, the improvement comprising providing a source of a Group IB metal and a thin film source of a Group VIII metal within a thickness of up to about 1.25 .mu.m thick coating said Group IB metal, said Group VIII metal being adjacent to said gold tin solder, said Group IB metal, said Group VIII metal in combination with said brazing solder coming into contact with said metallic elements during brazing, whereby the melting temperature of said brazing solder is raised substantially during brazing to a value above the melting temperature of said solder connections.
In a process of brazing metallic elements to a substrate in a thin film electronic circuit package wherein said substrate carries said metallic elements and solder connections supporting a plurality of chips on said substrate, with the metallic elements brazed to said substrate by means of a gold tin brazing solder, the improvement comprising providing a source of a Group IB metal and a source of a Group VIII metal in combination with said brazing solder, to come into contact with said metallic elements during brazing, whereby the melting temperature of said brazing solder is raised substantially during brazing to a value above the melting temperature of said solder connections said substrate is mounted to a flange with the flange and the substrate being brazed together by said brazing solder with the substrate brazing area being coated with an Mo border coated with a nickel layer, said source of a Group IB metal and a Group VIII metal being a flat preform located within a braze fillet between said substrate and a said metallic element prior to brazing.
In a process of brazing metallic pins to a substrate in a thin film electronic circuit package wherein said substrate carries said metallic pins and solder connections supporting a plurality of chips on said substrate, with said metallic pins brazed to said substrate by means of a gold tin brazing solder, the improvement comprising providing a source of Group IB metal and a source of a Group VIII metal in combination with said brazing solder, to come into contact with said metallic pins during brazing, whereby the melting temperature of said brazing solder is raised substantially during brazing to a value above the melting temperature of said solder connections, wherein a source of a Group IB metal and Group VIII metal is derived from the composition of said metallic pins during brazing wherein a said metallic pin is composed of a core of a Group IB metal coated with a Group VIII metal prior to brazing.
In a process of brazing metallic pins to a substrate in thin film electronic circuit package wherein said substrate carries said metallic pins and solder connections supporting a plurality of chips on said substrate, with the metallic elements brazed to said substrate by means of gold tin brazing solder, the improvement comprising providing a source of a Group IB metal and a source of a Group VIII metal in combination with said brazing solder, to come into contact with said metallic pins during brazing, whereby the melting temperature of said brazing solder is raised substantially during brazing to a value above the melting temperature of said solder connections wherein said source of a Group IB metal and a Group VIII metal is a flat preform located within a braze fillet between said substrate and a said metallic element prior to brazing.
Dependencies are inferred from the claim text.