A practice-driven verification has revealed that storing flex-rigid PCBs (FR4 polyamide compound) as well as BGAs in a 3% ultra-low relative humidity cabinet from Seika for a time span of 4 days has made additional tempering superfluous. Compared to the PCB and BGA samples baked at 140°C/6 hrs for minimizing humidity in the parts, the soldering results displayed better performance. Especially the solder balls of the BGAs didn’t show this degree of oxidation that is normal for intensive high-temperature tempering, and there is no pre-aging of semiconductors, shortening their lifetime. Dry storage (10% RH) for handling, packing, shipping und application of moisture-sensitive reflow SMDs can efficiently be provided according to the IPC-JEDEC standard J-STD-033. This can lead to a remarkable improvement of product quality while reducing costs for the drying process. And not to be forgotten: drying of humidity-sensitive parts, particularly molded semiconductor devices, is an indispensable action in order to prevent the packages from forming micro cracks.
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