Laser soldered high density cable assemblies for portable electronics

The purpose of this study was to evaluate feasibility and viability of the laser soldering process of small diameter stranded wire to a contact on Insulation Displacement Connector (IDC), and comparing it to non-permanent IDC joints. IDCs are cost effective, however for more demanding applications in portable electronics, with exposure to contamination, corrosion and vibration, their performance could be significantly improved, at a low cost, by addition of permanent solder joints. 30 AWG stranded copper/silver plated wire has been laser soldered to contacts on high density, double row, 0.8 mm CHAMP miniature IDC AMP connector. To simulate manufacturing environment, industrial type IR, Nd:YAG, pulsed laser was used to make joints. To reduce manufacturing cost and environmental impact, solder preforms with no-clean flux have been used. Both IDC and laser soldered joints assemblies have been evaluated, the same way, first visually and later electrically using industry compatible AMP test specifications. Contact resistance has been measured initially, after temperature/humidity test, and after thermal shock test. The results have been presented in a comparative statistical format. They fully confirmed that integrity of the laser soldered joints is superior over IDCs. When the Standard Deviation for the laser soldered joints changed very little, from 1.67 to 1.75 (mohm), for IDC joints it dramatically increased from 1.75 to 7.14 (mohm). The biggest impact had a thermal shock test. Our evaluation confirmed, that laser soldering of stranded wires into contacts, on miniature high density IDCs, can be considered as a cost effective, valuable alternative process for high performance cable assemblies in portable electronics.