[Tinkerphones] [Gta04-owner] Status of GTA04A5 production +++ has started +++ video available

H. Nikolaus Schaller hns at goldelico.com
Mon Oct 3 13:05:51 CEST 2016


> Am 03.10.2016 um 12:50 schrieb H. Nikolaus Schaller <hns at goldelico.com>:
> 
> Hi,
> a short update right from the lab:
> 
>> Am 27.09.2016 um 17:07 schrieb H. Nikolaus Schaller <hns at goldelico.com>:
>> 
>> 
>>> Am 27.09.2016 um 16:08 schrieb tgrauss <tgrauss at 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

And some more photos:

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