Sorgelig wrote:What you mean by "fail". Doesn't such module work at all, or doesn't pass some frequency?
v2.4 has smaller clearance between solder pads and ground plane. v2.5 has larger clearance making it easier to solder. Not sure if this can be a reason.
My process for testing as a seller goes like this:
1. memtest at 150mhz (pass if it has some errors)
2. memtest at 140mhz (fail if it has any errors)
3. test boot with archie core (fail if it hangs)
4. test boot and play a game with minimig (fail if has hanging issues with known good games)
5. test boot and watch for visual distortions with the neogeo core and bad apple rom (fail if it has any video compression errors)
Most of my fails come from the memtest, and on those (2.4) pcb's, they fail to pass any memtest above 120 (however they do work with archie,minimig,neogeo, and all other tested cores).
So far with the XSD 2.5, I have only had one problem out of around 30 modules and 90% seem to pass at 150mhz as well as 140mhz.
It could possibly be a soldering issue(but i have made a LOT of sdram modules at this point, most without issues), but i really suspect a fault with the pcb at time of manufacture. I'm curious if anyone has an explaination of what JLCPCB (or me) did wrong that is causing this..
Do you recommend any changes to my testing process?