The reliability of isotropically conductive adhesive as solder replacement - A case study using LCP substrate

In this study, the reliability of isotropically conductive adhesive (ICA) attachments on liquid crystal polymer (LCP) substrate was compared to the reliability of lead-free solder (SnAgCu) attachments on same substrate material. The assembled components were similar surface mount components and the reliability was assessed through real-time measurements of contact resistance of each connection. The devices were subjected to two environmental stress tests, a thermal cycle test and a sinusoidal vibration. Results show that when using LCP as a substrate material, the reliabililty of the device under thermal cyclic stress is somewhat inferior to the reliability of SnAgCu solder. No significant differences could however be percieved from the vibration test results since none of the assemblies failed in the test. The failure analysis revealed that most failures occured at the interface between component lead and the attachment material in both cases, but the test methods need to be developed to make further conclusions.