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Nondestructive Solder for Thin Metallic Films

IP.com Disclosure Number: IPCOM000092657D
Original Publication Date: 1967-Feb-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Berry, BS: AUTHOR

Abstract

Electronic packages are produced by joining component elements to a perforated interconnection system on a base module or substrate. During this procedure, a metallization pattern of conductive stripes representing the interconnection system is established on the substrate. This pattern is then tinned by dipping the whole module in a solder. The components are then positioned on the module and are joined to the stripes by melting the solder. If is essential that the solder not dissolve and remove the initial metallization.

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Nondestructive Solder for Thin Metallic Films

Electronic packages are produced by joining component elements to a perforated interconnection system on a base module or substrate. During this procedure, a metallization pattern of conductive stripes representing the interconnection system is established on the substrate. This pattern is then tinned by dipping the whole module in a solder. The components are then positioned on the module and are joined to the stripes by melting the solder. If is essential that the solder not dissolve and remove the initial metallization.

Normally, a lead-tin solder, e. g., Pb-5%Sn alloy, is not compatible with a thin film of copper. This is because it has a small but finite solubility in the solder. Thin films of copper on glass substrates, when immersed in the bath of Pb-5% Sn alloy at 350 degrees C, are removed from the substrate in only a few seconds. Such an alloy is made compatible with the thin film of copper by saturating the solder with copper to inhibit the solution action.

It is convenient to inhibit the solubility and to maintain the saturation of the solder by copper by partially lining the solder pot with copper foil. The life of copper film immersed in Pb-5% Sn alloy at 350 degrees C is extended from less than 10 seconds to approximately 20 minutes.

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