Announcements Distribution Solution Leaders Pilot NOW LIVE for all Infineon Distributors â join now, more information here ! 'E' is for enhanced: IR HiRel's redesigned SMD-0.5e package 'E' is for enhanced: IR HiRel's redesigned SMD-0.5e package â10 Oct 2023 04:47 AM The past couple of years have seen magnificent strides in the space frontier. Between Indiaâs lunar mission breaking new ground and exponential growth within the commercial space industry, rapidly changing space missions require evolving solutions. Enter the SMD-0.5e, IR HiRelâs enhanced version of our legacy SMD-0.5 package. This blog post will break down the key differences between the new and old package, specifically addressing our redesigned approach to thermal mismatch. You can follow along by downloading the application note . Why the redesign? Our legacy SMD-0.5 package has long been an industry standard package for power discretes. Its size and performance make it especially popular for power electronic applications in satellites and spacecrafts. But material differences between circuit boards and large power devices pose a challenge in maintaining reliable solder joints and preserving the sealed integrity of highly reliable, hermetically packaged devices. The SMD-0.5e remedies these issues, eliminates leads and promotes product longevity â no layout change necessary. Put simply, the SMD-0.5e is a simpler, more thermally efficient alternative to its legacy counterpart, with all the high-reliability features the SMD-0.5 package offers. The problem of thermal expansion No matter how you go about it, it is an inherent property of materials to expand and contract with temperature changes. This process causes stress and strain, posing assembly problems (to view specs and images, check out the application note ). Solutions throughout the supply chain to minimize stress fractures and cracks have found limited success. Developing stronger ceramics and modifying local properties of PCBs are just two attempts to alleviate the problem; but neither solution has been adopted by the industry at large. Fig. 1. The SMD-0.5 (pictured) uses leads to regulate thermal expansion while SMD-0.5e does not require leads. IR HiRel has offered package lead and carrier options to our customers to overcome this issue of CTE mismatch. But this process can be time consuming. For example, leads pave the way for parasitic resistance and inductance, complicating assembly. Thatâs why we redesigned the SMD-0.5 to better handle thermal expansion and heat transfer. SMD 0.5e offers an optimal solution Engineers will be happy to know that our SMD-0.5e package has drop-in compatibility with the SMD-0.5. But our favorite part of the redesign is how it addresses the root of the problem, which isnât necessarily thermal mismatch. The inherent problem lies within the terminal interface between the SMD and the circuit board solder pads â something ribbon leads canât fix. Our mission was to (1) solve the stress cracking problem caused by any CTE mismatch and (2) minimize thermal and electrical resistance. The SMD-0.5e does just that with a base better able to match CTE throughout the rad hard power discrete device. Conclusion Qualification testing of the SMD-0.5e demonstrated that the redesign can withstand thermal expansion differences between package and PCB while maintaining hermetic integrity. Compared to thermal expansion solutions in the SMD-0.5, the redesign takes up less space and weighs less than the original, all while providing a more direct thermal path for heat transfer. The result is a cost-effective, drop-in compatible alternative to the SMD-0.5. For more details on the SMD-0.5e, including figures, data sheets, and outline drawings, visit the application note . Copy Link You must be a registered user to add a comment. If you've already registered, sign in. Otherwise, register and sign in.