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| | EP678908 Ibm european software patent - Low temperature ternary c4 method. - Gauss |
 | | A high melting temperature composition, such as a binary Pb/Sn alloy, is deposited on contacts on, for example, the chip, and constituents of a low melting composition, such as Bi and Sn, are codeposited on contacts on, for example, the chip carrier. |
 | | The integrated circuit chip and the chip carrier are brought into contact, and the temperature of the chip and carrier are raised to the melting point of the lower melting solder composition.This causes the higher melting composition to solubilize and form a third, still lower melting temperature solder composition. |
 | | Next the chip and chip carrier are heated to cause the Bi and Sn to melt and form a low melting temperature Bi/Sn alloy, and dissolve the higher melting Pb/Sn therein. |
| gauss.ffii.org /PatentView/EP678908 (777 words) |
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