ECAs that Improve the Bottom Line Print E-mail
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Written by Jie Bai   
Thursday, 08 March 2012 23:45

 



Novel materials are more process-friendly and hold up against traditional solders.

When solder or mechanical interconnect solutions simply don’t suffice for certain electronics applications, technology specialists turn to electrically conductive adhesives (ECAs). These well-known materials are capable of delivering a reliable interconnect and, as the industry moves toward more regulatory compliant Pb-free processes, satisfy criteria for sustainability. ECAs are used in countless applications. These include the mounting of bare die and components on a variety of substrates (particularly in automotive applications), photovoltaic module assembly processes, sensor attachment to leadframes and the assembly of tantalum capacitors, among others.

The benefits of ECAs are many. Among the advantages are lower temperature processability, enabling both bare die and passive component mounting in a single step; lower stress assemblies, as ECAs compensate for thermal mismatch between components and their corresponding substrates; and Pb-free formulations that comply with current industry regulatory standards. Until now, one of the few disadvantages to ECAs has been their inability to cope with non-noble metals on component terminations, which meant they could be used primarily with higher cost components finished with palladium silver, silver or gold. But, that’s no longer the case.

New formulation breakthroughs have yielded ECAs that deliver all the benefits traditionally associated with conductive adhesives, but do so in a material system that permits manufacturers to incorporate lower cost, Sn-terminated components. These new adhesives provide low and stable contact resistance when used with 100% Sn-finished components and their ability to provide reliable component assembly to a variety of substrates including low temperature co-fired ceramics (LTCCs), high temperature ceramics and OSP-finished PCBs, make them extremely adaptive and cost-effective. Many of these newer adhesives have exhibited no bridging or wicking under very small components such as 0402s, making them well-suited for today’s miniaturized assemblies.

One of the more compelling advantages of these ECAs is their ability to enable electronics specialists to implement significant cost-reduction measures. Because the ECAs can be used with Sn-terminated components and lower-cost organic-coated bare boards, some manufacturers have reported a significantly lower cost per board.

In addition to cost-effectiveness, Sn-compatible ECAs streamline the assembly process and introduce flexibility into the manufacturing operation. Manufacturers can use a single assembly process to attach both bare die and packaged components, as opposed to the two-step process required when soldering techniques are used. The materials could be screen-printed or dispensed, delivering ease-of-use and process adaptability. Because of the materials’ adaptability to different substrate types, a single material can be sourced for different applications, which permits reduced complexity in the supply chain and lower overall costs.

While some ECAs have proven to be well-suited for many automotive applications, they have relevance for any market where high-reliability and cost reduction targets are integral to the technology roadmap. These may include the aerospace sector, wireless datacom infrastructure (WDI) products, security devices, lighting technologies and others.

The bottom line is, well, the bottom line! With these new ECAs, costs can be reduced and performance can be raised – truly a best of both worlds scenario.

Acknowledgments

The author would like to thank Henkel engineer Wilson Ma for his valuable input.

Jie Bai is a chemist at Henkel Electronics Group (henkel.com); This e-mail address is being protected from spambots. You need JavaScript enabled to view it .

Last Updated on Friday, 09 March 2012 00:58
 

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