[Community] Status OpenPhoneux / GTA04

Dr. H. Nikolaus Schaller hns at goldelico.com
Tue Jul 3 15:42:43 CEST 2012

Am 03.07.2012 um 11:44 schrieb ed at kapitein.org:

> Thanks for your update!
> It takes the open phone concept a little further, if we have even x-rays of 
> the boards ;-)

Yes, we want to make the device transparent ... not the user :)

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> 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 ?crit , 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:
>> 	http://download.goldelico.com/gta04/images/20120622-GTA04A4-
> schlecht-01.jpg
>> If you want to compare to the GTA04A3 board X-Ray (with one short):
>> 	http://download.goldelico.com/gta04/images/20110707-GTA04A3-schlecht-
> xr002.
>> jpg
>> or the GTA04A2 board (where only 1 unit exists):
>> 	http://download.goldelico.com/gta04/images/20101109-GTA04A2-overview.jpg
>>> 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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