Hi Nikolaus, On Mon, Feb 27, 2017 at 7:30 PM, H. Nikolaus Schaller <[email protected]> wrote: > Hi Marek, > >> Am 27.02.2017 um 11:46 schrieb Belisko Marek <[email protected]>: >> >> >>> -1.: Only 12 out of 36 (*) GTA04A5 boards we >>> have produced, are booting to Linux. The others either have a >>> short circuit under the OMAP (which is the general PoP soldering >>> problem we already know since the first generations of the >>> GTA04) or the OMAP shows no response or does not recognise the >>> µSD card for unknown reasons. > >> Hmm this is bad. Doesn't something like that happen in first verification >> run? But maybe I'm wrong. >> Did you try to get some info from chip producer what could be a problem or >> which technology should be used to have it solder properly. > > Yes, we asked TI in details some years ago when we built the GTA04A3 and A4. > From that we probably know everything what can be known about this DM3730 > soldering issue... > > And we though that this knowledge is enough to avoid to fall back into the > same > old problems we had back then when using a new (and modern) production line. > > Back then we had to experiment several months to raise yield from ca. 30% to > 90%. > Then, the production batch was completed. But we had to do a lot of repairs > back > then as well. > > So all this means the production process of the DM3730 + PoP is very very > critical > to parameters we can't repeat several years later. And therefore we had to > start > optimization almost from scratch. But do not have the means to continue to > reach > 90% again. > >> 12 from 36 is exactly third which is too high. I'm sorry to hear such bad >> news. > > I am currently making a plan in which sequence we try to repair what > (desolder chips > and replace). So I am confident that we can come a little closer to 36 of 36. This is great news. But AFAIK desoldering/soldering BGA is not really easy process and sometimes happens that chip is damaged. Do you have some special idea how to do that? Thanks for sharing. > > BR, > Nikolaus > _______________________________________________ > Community mailing list > [email protected] > http://lists.goldelico.com/mailman/listinfo.cgi/community > http://www.tinkerphones.org
BR, marek -- as simple and primitive as possible ------------------------------------------------- Marek Belisko - OPEN-NANDRA Freelance Developer Ruska Nova Ves 219 | Presov, 08005 Slovak Republic Tel: +421 915 052 184 skype: marekwhite twitter: #opennandra web: http://open-nandra.com _______________________________________________ Community mailing list [email protected] http://lists.goldelico.com/mailman/listinfo.cgi/community http://www.tinkerphones.org
