TestConX China 2022 Cleveland Chen: Application of Coaxial Structure on Micro Pitch Sockets

Application of Coaxial Structure on Micro Pitch Sockets
As technology advances, mobile devices have the most complex and high-speed system-on-chips (SoCs) ever produced. The request for increased functionality in the smallest possible footprint has led to a reduction of chip pitch below 500?m. High speed and fine-pitch chip testing usually uses short spring probe in test sockets or conductive elastomer sockets. But short spring probe can’t generate enough spring force for stable low Cres and conductive elastomer have limited compliance, all which impact the socket performance. Customers’ next generation device performance, require low loss signal integrity performance from test sockets for sub 500 µm pitches. Smiths Interconnect has successfully developed a coaxial structure based on patented DaVinci technology for high-speed test socket with minimum pitch to 350µm applications. It has filled up the gap of previously coaxial sockets for ?650 um pitch chip test, were only available. The coaxial structure fundamental formula means small pitch requires smaller diameter spring probe or contacts for impedance matching. The challenges to develop a production ready coaxial socket are immense. DaVinci Micro’s signal probe and IM socket housing structure have application specific configurations which have been developed and deployed to the field, which have shown excellent performance in high volume IC chip testing at our various customer sites. This paper will share the fundamental requirements of coaxial structure for micro pitch applications and our solutions for it. The basic performances including technical specifications and test results, both mechanical and electrical, will be presented to help audience understand the advantages of this technology. The challenges in the micro coaxial high speed test socket development and related solutions to meet higher speed requirement in micro pitch will also be presented.
Cleveland Chen, Bachelor of Mechanical Engineering, Nantong University; Master of Business Administration, Renmin University of China. Working in Semiconductor testing industry about 17 years; now is the Semi Eng. manager of R&D, smiths interconnect Suzhou.