Lead-free Alloys Effect Back-end Manufacturing Technologies

(September 21, 2005) London, England &#8212 Lead-free wafer bumping and electronic packaging are emerging as an effective means of creating better performance semiconductor devices and gaining a competitive edge in a crowded market, furthered by growing environmental concerns from authorities such as the RoHS Directive. End-user demand for low-cost products, fuelled by the influx of Southeast Asian companies, is also prompting European participants to up the ante in innovation.

Participants use lead-free alternatives such as the tin-silver-copper (SnAgCu or SAC) system combined with materials such as gold. However, the slow adoption of these processes is propelled by issues like high yield loss and low reliability. “For instance, flip chip assembly qualifies for eutectic PbSn (lead-tin), but proves to be difficult for lead-free material,” explains Sivakumar Muthuramalingam, Frost & Sullivan research analyst. “High yield losses occur after the board assembly due to substrate warpage.”

The high fatigue characteristic of lead-free alloys results in temperature challenges causing flux problems, which can adversely impact manufacturing processes. “The integration of lead-free materials into flip chip/chip scale package (CSP) applications is difficult due to the material characteristics, such as stiffness and material compliance, that increasingly makes reliability an issue,” points out Muthuramalingam. “To overcome this, researchers in Germany are continuously working to develop novel wafer-bumping technologies for a wide range of applications.”

Constant innovation and enhanced products such as electroless nickel bump, stencil printing, and electroplating will also aid in solving issues surrounding the lack of standardization in the packaging industry, especially since several designs are used for the same package. While the European electronic packaging market leads in terms of research and development, it is facing a problem of underfinancing and stiff competition from the Far East. Southeast participants are intensifying competition, as the packaging service providers in Europe are unable to continue to support the drive for increasingly lower price margins. Going forward, greater standardization of electronic packaging
technologies, the race towards miniaturization of electronic devices, and the rise in demand for consumer electronics will sustain end-user interest in next-generation back-end semiconductor manufacturing technologies.


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