The socket will also uses up a lot of area on the PCB compared to a BGA which adds to the end cost, and requires more traces on the board than a BGA would require. That probably adds 5 to 10 bucks to the BOM and it is a through hole part that needs to be hand soldered in place which will probably add another 1 to 2 bucks to the final price. The alternative would be to add a 204 pin gold contact SO-DIMM edge connector coated with a thick enough layer of gold plating to last at least the specified minimum 25 mating cycles. The data rates are getting so high that soldered on to the board provides the most reliable and is the cheapest option. > restrict upgradability by soldering the RAM chips directly to the board Posted in Repair Hacks Tagged BGA soldering, memory upgrade, ram Post navigation We’ve seen quite a lot of ’s work here at Hackaday, one of his most recent was this amazing LED D20.

We’ll leave you with his final words though: “ But next time I think I’ll just buy the 16GB variant upfront.“. The final step is the non-trivial task of reballing and reworking the new BGAs onto the board, before testing the laptop and finding the process to be a success. An aside is how he checked the chips he received for fakes, including the useful tip of hiring a dentist to take an x-ray. Surprisingly it’s not as easy as one might expect to buy small quantities of some RAM chips, but he was eventually able to find some via AliExpress. Some research revealed their configuration, at which point the correct chips were sourced. A soldered-on laptop has none of these, so instead it employs a series of resistors whose combination tells the BIOS what memory to expect. The write-up is a fascinating primer on how DRAM identification works, which for removable DIMMs is handled by an onboard FLASH chip containing the details of the chips on board. Upgrading memory should then be impossible, but this reckons without the skills of, who worked through the process on his Dell XPS13. But sometimes a laptop manufacturer can be particularly annoying, and restrict upgradability by soldering the RAM chips directly to the board. Upgrading the memory in a computer is usually a straightforward case of swapping out a few DIMMs or SODIMMs, with the most complex task being to identify the correct type of memory from the many available.

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