Originally Posted by Jitsuryoku
And in case you didn't know it's overheating that causes YLoD.
Mate, as a degree qualified Electronics Engineer, working towards chartership you don't need to tell me what causes YLoD, and it's not overheating, it's the BGA connections that eventually crack due to constant heating and cooling cycles causing thermal stress in the lead free alloy which is used at the factory. Sometimes it can be caused by tin wiskers which are small crystals that form and can cause shorts between connections, tin wiskers can grow at a rate of 0.5mm per year and when you see how close the pads are on the GPU it becomes apparent that tin wiskers could be liable for the issue.
Leaded solder does not suffer from this because first of all lead supresses tin wiskers and has done for the last 50 or so years leaded solder has been used and nothing else has been found that can supress it as well as lead can. Not to mention lead is more maliable than lead-free solder and as such is less prone to cracking from thermal stress. Also, during a reball you are replacing the old already thermally stressed balls with fresh ones. A reflow does not do that so the balls are still prone to cracking, hence reflows can fail very often.
If the CPU or GPU overheat then the console shuts down with a flashing red light (RLoD) and no yellow light appears. Heat is the cause of YLoD due to constant heating and cooling cycles, but the main issue is the lead free solder that was introduced in 2006 due to RoHS & WEEE directives.
Hence BGA failures have become more common as of recent since lead free solder came into force.