Session 19: Conductors

Novel Low Temperature Materials as Key Enablers of Flexible Hybrid Electronics
Thursday, February 15, 2018
1:40 PM - 2:05 PM

Emerging Trends: In current and emerging electronics, ‘Flexible Hybrid Assemblies’ are being increasingly employed because of their substantial advantages compared to conventional rigid FR-4 based assemblies. Specifically, Flexible Hybrid Assembles enable weight reduction, facilitate thinner devices/smaller stand-offs and offer remarkable design flexibility. Incumbent Technologies: Current generation flexible hybrid assemblies typically use polyimide-based substrates and SAC-based solder pastes with a melting points around 217°C. Challenges and Limitations: Polyimide-based substrates tend to be typically expensive and lack water clear transparency. Furthermore, SAC-based solder pastes, with a peak reflow temperature of around 240°C, often induce warpage, misalignment and can cause other assembly defects. To address these shortcomings, we demonstrate the use of novel low temperature, very high reliability, solder pastes for wide array of flexible substrates. Low Temperature Solutions: This paper will present results of a comprehensive multi-year initiative covering: - Low Temperature Alloy Development: Focus on thermo-mechanical reliability enhancement of new SnBi Alloys. - Paste Development: Low temperature solder paste development and performance comparison to traditional SAC-based solder pastes on Polyimide substrates. - Process Development: Printing and Reflow performance of low temperature processed assemblies on various flexible substrates. - Reliability Assessment: Thermal Cycling and Mechanical Vibration Performance. In summary, we show that novel low temperature materials and processes will be key enablers of next generation Flexible Hybrid Electronics.