Status OpenPhoneux / GTA04

ed at ed at
Tue Jul 3 11:44:36 CEST 2012

Thanks for your update!

It takes the open phone concept a little further, if we have even x-rays of 
the boards ;-)

Kind regards,

On Tuesday 03 July 2012 11:15:16 Dr. H. Nikolaus Schaller wrote:
> Hi all,
> I did a long telephone call this morning to discuss the production situation
> of the GTA04A4 boards.
> Am 25.06.2012 um 20:56 schrieb Dr. H. Nikolaus Schaller:
> > Hi,
> > 
> > Am 25.06.2012 um 16:16 schrieb Gilles Filippini:
> >> Hi Nikolaus,
> >> 
> >> Dr. H. Nikolaus Schaller a écrit , Le 31/05/2012 17:36:
> >>> So please expect that it will become End of June for delivery...
> >> 
> >> Since we are near to End of June, time for asking how is it going? ;)
> > 
> > Neither good nor bad...
> > 
> > This means:
> > * we have already shipped some of the GTA04 Group Tour boards
> > * some friends have upgraded to a complete OpenPhoenux (we have a handful
> > reworked GTA02) * but we still have a list of open orders for roughly 90
> > GTA04 Group Tour boards
> > 
> > The production company had stopped again to do some more
> > analyses and the last status I received today is that they had
> > again made some X-Ray. Now they think they can again optimize
> > the soldering process a little so that we don't get so much broken
> > boards that need manual rework.
> So here is a copy of the latest X-Ray image of the DM3730CBP with short
> circuits:
> If you want to compare to the GTA04A3 board X-Ray (with one short):
> jpg
> or the GTA04A2 board (where only 1 unit exists):
> > Every rework ruins some components (unfortunately 1 DM3730
> > + 1 Memory chip > 50 EUR) and costs intensive working time.
> > And we simply can't afford that if it happens too often...
> > 
> > So the highest priority is to get rid of the root cause for these
> > soldering failures.
> After analyzing and discussing the X-Ray images we now think we
> understand what happens (but you never know if you are right...).
> The reason appears that the DM3730CBP gets some warp during
> the soldering process squeezing the balls in the middle of the BGA
> grid so that they may touch a neighbor and make a short circuit.
> And on the corners the balls lift off and this may result in interruptions.
> This theory correlates exactly with the error patterns we see:
> * some 50% of the boards come out of the soldering process with
> shorts on VDD1, VDD2 and/or VIO which are mostly available
> on the center balls
> * if the chip has no short on the power supply or is reworked some
> 50% of the boards have interruptions which makes a single function
> fail. Sometimes the SD interface has just 3 data lines, sometimes the
> WLAN chip. Sometimes some sensor is not working. Sometimes
> the USB is not working, or one display data link distorting the
> colors etc.
> Now comes the crucial question: how can this be improved?
> The specialists of the production company have spent whole weekends
> to do more experiments but did not yet find the right trick. It is not that
> they do not want to solve the problem (they see it as a challenge) they
> simply have not yet found the key.
> One factor is that our GTA04 board has exceptionally squeezed
> components (since we must be small) so the soldering of a OpenPandora
> or the BeagleBoard may be a little easier from heat distribution.
> I.e. we are pushing an experienced EMS to their limits...
> An EMS who has produced more than 2000 different products in small
> quantities (which is their strength) including some 0.4mm BGAs.
> A new experiment is scheduled for week 29 to use a different
> reflow soldering machine and process which uses a little lower
> temperature.
> Unfortunately, we can't contribute to this production improvement
> to speed things up.
> Unless one of the readers on these list knows some real specialist
> for such PoP soldering of BGAs who is willing and capable to
> consult (even if it costs money). So if you know someone, please
> let me know.
> > The good answer is that as soon as we decide to continue,
> So we had to decide to wait for the different reflow soldering process
> first.
> > it takes less than 4 weeks to produce, test and ship all missing
> > boards. They have planned that it works even if holiday season
> > is coming. And our shipment plan is by sequence of order. So
> > if you did order early, it is even a little closer.
> So it is a stony path towards a community driven independently
> developed and produced open smartphone platform. But Rome
> wasn't built in one day...
> And we have to solve this issue before we can start to think
> about a future quad core LTE device with multitouch... Please
> keep the faith.
> BR,
> Nikolaus
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