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US 5,729,440 AGranted
Solder hierarchy for chip attachment to substrates
AssigneeInternational Business Machines Corporation
InventorsMiguel Angel Jimarez, Amit Kumar Sarkhel, Lawrence Harold White
Life of this patent
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Abstract
The method for soldering a chip to a substrate to form a module and then soldering the module to a circuit board includes selecting a three level hierarchy of solders by the temperature required to melt. By this method, a module can be soldered to and de-soldered from a circuit board without affecting adversely the solder between the chip and the substrate. The package formed by this method is free of faults that are caused frequently during both manufacture and service.
Claims5
An organic chip package, comprising:
- a substrate formed of at least one layer of organic dielectric material, with an electrical circuit of a predetermined arrangement with points for connecting either to an external power source or to an external circuit;
- a chip with connection points of first solder material with a predetermined melting temperature of at least 300 degrees C. and formed of either 95% Pb and 5% Sn or 96.5% Pb and 3.5% Sn;
- and
- second solder material formed in the range of 2.0% to 3.5% Ag-98% to 96.5% Sn solder selected from a group of solders with a melting temperature in the range of 220 to 240 degrees C. attaching said first solder material to said substrate.
1 more element
Dependencies are inferred from the claim text.