Solder hierarchy for chip attachment to substrates
Patent 5655703 Issued on August 12, 1997. Estimated Expiration Date: 
May 25, 2015. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.
May 25, 2015. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.InventorsApplicationNo. 449747 filed on 05/25/1995US Classes:228/180.22, Lead-less (or "bumped") device228/187, Separate successive bonds at different temperatures228/191, With disassembling of bonded joint (e.g., desoldering)257/E21.503, Encapsulation of active face of flip chip device, e.g., under filling or under encapsulation of flip-chip, encapsulation perform on chip or mounting substrate (EPO)257/E21.511Mounting on insulating member provided with metallic leads, e.g., flip-chip mounting, conductive die mounting (EPO)ExaminersPrimary: Bradley, P. AustinAssistant: Knapp, Jeffrey T. Attorney, Agent or FirmInternational ClassesB23K 001/00B23K 001/018 B23K 031/02 AbstractThe 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.Other References
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