Metallurgy System for Pin Attachment to MLC
Original Publication Date: 1984-Jan-01
Included in the Prior Art Database: 2005-Feb-02
A given number of semiconductor chip packaging approaches have utilized MLC (multilayer ceramic) technology. Conventionally, input/output (I/O) pins are brazed on the bottom surface for I/O's to a printed circuit (PC) board. The pins can be brazed with 80% Au/20% Sn alloy which is very expensive or with Cu/Ag eutectic alloy which must be brazed at temperatures of 900ŒC or higher. This alloy (Cu/Ag eutectic) is also known to be susceptible to Ag migration. A new cost-effective metallurgy system for pin attachment for low cost MLC is described here. Fig. 1 shows a Cu solder pin system for MLC. The Cu (copper) is screened or plated over a Mo (molybdenum) pad. A Au (gold) flash of approximately 10-15 u" is plated over the copper for corrosion protection.