Hi, a short update right from the lab: > Am 27.09.2016 um 17:07 schrieb H. Nikolaus Schaller <h...@goldelico.com>: > > >> Am 27.09.2016 um 16:08 schrieb tgrauss <tgra...@f-gp.eu>: >> >> The "Solder Paste Dipping" on page 3 is a very interesting chapter. It is >> more related to BGA soldering than PoP. > > Yes indeed. I have never heard about that and it does not really seem to be a > common method in 2016. > > And I am not sure if it would help for the DM3730 - which has no significant > difference to the tps65950 on the same board. > > I.e. one 0.4mm pitch BGA makes no problem. One makes big problems, but hadn't > made so much trouble in GTA04A4. > > Well there are some, but it is unclear what the difference is.
I managed to rework one of the boards which are known to have a short circuit by removing the DM3730 and PoP. Looking at the solder pads after removing the chip did reveal some shorts we already had seen by X-Ray. What I have done was to place a very tiny snippet of kapton tape under the DM3730 so that the BGA balls can not be squeezed as much as before. This appears to make a difference! Here is a first sign of activity: > tذb$U @D 6:b`U@ @QT,0 @tذb$U @QT,0 @tذb$U @D @tذb$U @D @tذb$U > @D tذb$U @D @ > > Texas Instruments X-Loader (MLO) 1.4.4ss modified for GTA04 (May 11 2016 - > 11:52:00) > No NAND detected > OMAP36XX/37XX-GP ES2.1 > Board detected: GTA04A2 > SYSBOOT[5:0]: 0x0f/15 > GMPC Memory: 1 > SDRC Memory: DDR 128MB/bank > NAND: mfr=0x00 id=0x00 > Reading FAT boot sector > > not there > Loading u-boot.bin from nand > Skipped bad block at 0x80000 > Skipped bad block at 0xa0000 > Skipped bad block at 0xc0000 > Skipped bad block at 0xe0000 > Skipped bad block at 0x100000 > Skipped bad block at 0x120000 > Skipped bad block at 0x140000 > u-boot.bin not found or blank nand contents - attempting serial boot . . . > ## Ready for binary (kermit) download to 0x80008000 at 115200 bps. Press 'M' > to break into low level monitor. which means that the DRAM/NAND wasn't found. This is likely a soldering issue of my prototyping. But the DM3730 BootROM did start and load something from the µSD card into SRAM. And did activate the UART3. The big question I have discuss with the production company is how to glue this very small patch of kapton tape during production... BR, Nikolaus _______________________________________________ Gta04-owner mailing list Gta04-owner@goldelico.com http://lists.goldelico.com/mailman/listinfo.cgi/gta04-owner
