PSP Wifi Reflow
I recently bought an Aoyue hot air reflow station so I could do SMT soldering faster and more easily. £90 on ebay - bargain! As I repeatedly say, there's nothing magic about surface mount stuff - it can be soldered easily by hand with an ordinary iron and a little practise. However, hot air reflow does allow one to solder BGAs.
A friend came to me with a PSP wifi module with an insane problem - all the joints on the BGA had failed, and the module just sheared off, leaving perfectly tinned pads on the module, and perfect flat-topped balls on the PCB! Presumably it wasn't quite soldered correctly at the factory.
I added flux with a flux pen, and reflowed the balls so they were all nice and shiny and rounded again.
Then I preheated the pcb from the back and front, to prepare for soldering the BGA. I removed the sticker from the top of the module so it didn't burn. Flux was applied to the back of the module. I aligned the module roughly (the balls of solder do the rest) using a vacuum pick-up tool - a little freebie that came with the reflow station. I tried to be fairly quick so the board didn't cool down too much.
Then I heated the module mostly from the top. I heated it fairly gently over about a minute, heating a little more strongly towards the end. I poked the module with a screwdriver to feel whether the balls had melted. They had - the module wobbled on the surface tension like jelly. I didn't take any photos, as I was too busy worrying about whether I was overheating it!
I let it cool, then washed it in the ultrasonic bath with methylated spirits to remove the flux.
Nick reported that the module worked fine. I had slightly overheated a connector on the back, so it was a tight fit, but the board worked ok.
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