Study tracks concerns about using Cu bonding wire


A recent study intended to gauge the semiconductor industry's use of copper bonding wire vs. gold for packaging applications seems to suggest there are "serious reservations" about Cu wire reliability and yield.

The Oct-Dec. 2009 survey, conducted by SEMI and commissioned by the London-based World Gold Council—an organization focused on creating demand for gold—polled 46 global "leading semiconductor companies" including IDMs and fabless companies (total 2008 sales $137B, 55% of the industry total, including 14 of the top 20 suppliers) to determine the extent of their Cu bonding wire programs, and unearth key issues and considerations in selecting bonding wire material. A separate report from SEMI and TechSearch International recently projected copper wire shipments to the industry will reach 5.8% of total shipments in 2009, up from 1.6% in 2007.

Among the new study's results: 59% of companies surveyed don't use Cu wire technology, but 72% are considering switching to it for some new products (13% for the majority of products, 15% not at all but will keep using flip-chip). Among their concerns in switching from gold to copper are in-service product reliability, process yield, and "unproven performance"—with specific concerns narrowed to use in automotive applications, increased equipment costs, Cu's unsuitability for complex shapes in advanced packages (e.g., wire loops) and high metal layer counts/complex pad structures, different electrical performance, and existing manufacturing capacity. Twelve companies selected "total cost" as their only response in identifying advantages of gold vs. copper wire.

Another finding: despite half of respondents claiming awareness that gold content represents 50% of the economic value of recyclability of electronic goods, only 21% of companies consider this when selecting their bonding wire material. — J.M.

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