Not every computer is a performance gaming rig. Some of us need cheap laptops and tablets for simple Internet browsing or word processing, and we don’t need to shell out thousands of dollars just for that. With a cheaper price tag comes cheaper hardware, though, such as the eMMC standard which allows flash memory to be used in a more cost-advantageous way than SSDs. For a look at some the finer points of eMMC chips, we’ll turn to [Jason]’s latest project.
[Jason] had a few damaged eMMC storage chips and wanted to try to repair them. The most common failure mode for his chips is “cratering” which is a type of damage to the solder that holds them to their PCBs. With so many pins in such a small area, and with small pins themselves, often traditional soldering methods won’t work. The method that [Jason] found which works the best is using 0.15 mm thick glass strips to aid in the reflow process and get the solder to stick back to the chip again.
Doing work like this can get frustrating due to the small sizes involved and the amount of heat needed to get the solder to behave properly. For example, upgrading the memory chip in an iPhone took an expert solderer numerous tries with practice hardware to finally get enough courage to attempt this soldering on his own phone. With enough practice, the right tools, and a steady hand, though, these types of projects are definitely within reach.
Well I’ll never be able to do it but I have to hand it to him, good work!
He did not want to repair them as far as putting them back on a board, he wanted to read the contents once, by placing solder paste over the cratered pads and inserting the device in a special socket. There is a big difference between that and repairing them. It was an interesting read in any event.
Well I just learned something…i always thought SMD meant “surface mount device” but according to the article it’s actually “solder mask defined”.
So which one is actually correct?
It’s both. In the context of BGA pads, SMD means solder mask defined, but otherwise it’s surface mount device.
This also may work on damaged BGA chips though in this case indium eutectic solder may be safer.
Not the best writeup.
Summarising what this guy has done, it’s a helpful technique for situations where a through-hole via is empty, called “cratering”. To get new solder paste to melt and stay in there during reflow (and not ball up out of the hole because of fluid surface tension), he covers it with a glass slide as a lid.