Electronic assembly processing manufacturer of BGA welding process

by:A-TECH      2020-05-27
In electronic welding, the gold excellent stability and reliability, become one of the commonly used metal surface coating. But as impurities in the solder, gold is very harmful to the ductility of solder and Sn - because will form the brittleness of solder Au( Tin - Gold) Intermetallic compounds ( Mainly AuSn4) 。 Although many Korea containing low concentration of AuSn4 can improve the mechanical properties of the tin solder, but more than 4% when the content of gold in the solder, tensile strength and failure by rapid decline of elongation. Welding tray 1. 5 um thickness of pure gold and alloy layer, can be completely dissolved in wave soldering to melt the solder, formation of AuSn4 enough to damage to the mechanical performance of the plate. But there are for assembly process on the surface, can accept the gold plating thickness is very low, need to precise calculation. Glazer, et al. Reported for plastic quad flat package ( PQFP) And FR - The copper - 4 PCBs Nickel - Gold ( Cu- Ni- Au) Solder joints between metal coating, when its concentration is not more than three gold. 0 W/O, will not damage the reliability of solder joints. Electronic assembly machine manufacturers choose expansion will vendors to supply the entire LED chip film uniform expansion, make closely attached to the membrane surface is put LED grain, is advantageous for the crystal. Back glue. Will enlarge good crystal crystal ring on expanding has good silver pulp layer back glue scraper, silver paste on his back. Silver paste. Suitable for bulk LED chip. Selection will be just the right amount of silver pulp point glue on the PCB printed circuit board. Electronic assembly processing first USES the craft para, line around the perimeter of BGA and the PCB pad printing line alignment. Here's a tip: in the process of the BGA and silk screen line alignment, even if not completely aligned, even if the solder ball and solder, against 30%, still can be welded. Tin ball in the melting process, circuit board welding will automatically due to the tension between it and solder and solder alignment. In the complete alignment operation in the future, put the PCB on the bracket of BGA rework station, should be fixed, and the level of BGA rework station. Choose appropriate nozzle, and then select the corresponding temperature curve, welding, end of the temperature curve, cooling, and completed the BGA welding
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