By Andy C. Mackie, Ph.D., Indium Corporation, Utica, NY
Despite the relative stagnancy of the semiconductor market in 2009, there will be significant growth in the standard and power semiconductor assembly market spaces, as many device makers move to reduce costs by outsourcing the assembly side of their operations. As such, materials considerations are expected to play an increasingly important role. This article discusses technology drivers for materials used in these two distinct markets.
Technology Drivers in Standard Semiconductor Assembly Products
Halogen/Halide-free: There is a universal need for halogen-free fluxes, but the exact meaning of this phrase is still debated. Requirements will vary from the absolutist “not-intentionally- added” (NIA) to the frequently-quoted “9-9-15” halogen specifications. Meanwhile the IPC is also working on its own materials standards. 2009 will almost certainly see the usage of more stringent standards. NIA halogen will remain easy to promise but difficult for users to confirm and verify, however, because the limit of detection (LOD) of the combined sample preparation and test methods (which together determine the analytical sensitivity) will vary from test-laboratory to laboratory.
No-clean: There are still some moves towards no-clean ball-attach fluxes, but these materials have still not achieved market dominance. One of the prime reasons for this is that the customers of our ball-attach flux customers are typically very sensitive to cosmetic issues, even though residues may be shown to be functionally benign.
Drivers for Power Semiconductor Die-attach
Lead-free: The recent volte face in European end-of-life vehicle legislation announced in August of this year has alarm bells ringing throughout the power semiconductor industry. Many power semiconductor die-attach customers are now asking for high-melting point alternatives to the high-lead solders currently in use. Inevitably, trade-offs will be made in 2009 in terms of melting point, cost, malleability, allowable lead content, and thermal/electrical conductivity as lead-free alternatives are sought.
No-clean:As clip-bonding increasingly replaces some standard wire-bonding applications, customers are using ultra-low residue (ULR) no-clean materials in high-volume manufacturing for power semiconductor die-attach applications, and seeing major reductions in cost and throughput. Although there is a necessary caveat that the usage conditions and failure modes for “no-clean” materials used by the power semiconductor industry are drastically different from those of standard surface mount technology no-clean materials. In lieu of clear test methods confirming no-clean materials’ fitness for use in power electronics applications, customers are evaluating solder materials on a case-by-case basis in each customer’s unique process, and then putting them through advanced life testing (ALT).
Andy C Mackie, Ph.D. product manager, semiconductor assembly materials, may be contacted at Indium Corporation, 34 Robinson Road, Clinton, NY 13323 USA; 315/381/7524, www.indium.com; E-mail: [email protected].