Distribution of Coated Metal Layer on Free Air Ball (FAB) Surface

Abstract

Developments in bonding wire focus on coated silver wire for stacked devices in memory sectors revealing near equivalent performances to 4N Au wire. In addition to stacked device applications, the wire is also examined for other conventional applications. The innovative wire exhibits excellent performance on biased Highly Accelerated Stress Test (bHAST) passing 192h and 504h at 130°C, 85%RH for +3.3V and +20V, respectively. Thus, the wire satisfied one of the important criteria required to pass automotive reliability test (2X stress test, AEC Q100 Rev-H, with limited test samples). The test is conducted using 0.8mil coated silver wire and molded with green epoxy molding compound. Another benefit of the wire is stitch bond bondability with high MTBA of greater than 2h.

Gold Coated Silver Bonding Wire and Its Consistent Reliability Performances

“…EMCs developed for copper and silver-based bonding wires limit chlorine and sulfur below 20ppm formulated with ioncatchers, demonstrates longer reliability life of copper/silver bonded balls. The present study reports the findings on the reliability behavior of gold-coated silver bonding wire for longer (extended) test durations, and the performances are consistent and similar to previous test evaluations [1][2][3][4][5][6].…”

“…This leads to enriched gold-silver alloy along the outer layer of the bonded ball on both the right and left corners. Where, to a certain extent, diffusion of chlorine and sulfur ions from environment into the bond interface is protected [3][4][5][6]. Gold coating thickness is optimized in design of the wire bonding performances.…”