Polyimide Flex Circuitry for >200°C

摘要

This Department of Energy-funded study represents the first significant investigation of polyimide flex as a substrate material for high-temperature (>200°C) electronics packaging for downhole oil and gas exploration. This program examined three key areas of package development: conductor adhesion to flex, through hole via reliability in flex, and high temperature interconnect methods for passive devices on flex. High-temperature storage testing of different adhesion layers to flex was performed at 200 and 250°C in air and nitrogen for as long as 1000 hrs. Multiple adhesion materials and thicknesses were evaluated by measuring the peel strength of copper traces to polyimide. A Cr adhesion layer was selected due to its ability to maintain high peel strength during the high-temperature storage testing. Thermal cycling of through hole vias between room temperature and 250°C for greater than 1200 cycles showed little degradation. Thermal cycling was also performed on passive components attached to flex using four high-temperature solders. Results up to 277 cycles are reported.