Gold plated solder material and method of fluxless soldering using solder
AssigneeTRW Inc.
InventorHeinrich G. Muller
Life of this patent
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Abstract
A solder material 10 suitable for fluxless soldering attachment of a component 12 to a substrate 14 in a microelectronic assembly 16 such as a hybrid package comprises a core 18 and a gold layer 20 on the core. The core can comprise an alloy of tin and lead. The core preferably consists essentially of at least about 30 wt. % tin and the balance lead, so that it melts at temperatures of less than about 250° C. The gold layer is preferably applied to the core using an electroless plating process that forms a highly uniform gold layer. The solder material provides a joint between the component and the substrate comprising less than about 3 wt. % gold.
Claims5
A sheet of solder for application in fluxless soldering of a component to a substrate in a microelectronic assembly comprising:
- a) a core comprised of an alloy of tin and lead, said core having a thickness of no less than 50 μm;
- and
- b) a layer of electroless gold covering the entire core, said layer being no greater than 0.1 μm in thickness, and defining with said core a solder having a melting temperature under 280° C.
A sheet of solder material comprising:
- a) a core consisting of an alloy of tin and lead in the proportion of 63% tin and 37% lead, said core having a thickness of no less than 50 μm;
- and
- b) a layer consisting of electroless gold covering the entire core, and wherein said sheet of solder material possesses a melting temperature of less than about 280° C.
A sheet of solder material comprising:
- a) a core consisting essentially of about 63 wt. % tin and about 37 wt. % lead, said core having a thickness of no less than 50 μm;
- and
- b) a layer consisting of electroless gold substantially covering the core, wherein said electroless gold layer is applied on said core with an electroless plating process.
Dependencies are inferred from the claim text.