Evaluation of Doubled-sided Substrate Attachment Technique for Round Shaped Large Metallic Housing under Airborne System Development

This article presents about innovation carried out in double sided direct substrate attachment onto the housing for round shaped large size aluminum housing. Conventional reflow soldering methods or vapor phase soldering has lots of issues for PCB direct attachment on to the housing floor. This problem even become severe when attachment size is considerably large. One of the main issue of it is unwanted voids beneath the substrate and it create several issues in RF performances especially in phase nonlinearity. This article compares all the conventional soldering methodologies and proposes a simple, mass production-worthy faster attachment process using electrically and thermally conductive epoxy based silver filled adhesive film (50 μm thick), called coolspan adhesive. X-Ray reports have been analyzed for each processes to take crucial decisions about attachment process and to ensure percentage of voids for comparison purpose. Phase nonlinearity responses of various channels have been analyzed and final frequency got resolved. Modules have been made and tested over extensive thermal cycling from -40°C to +71°C and random vibrations in three axes to establish the analysis.