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

H. Nikolaus Schaller hns at goldelico.com
Tue Sep 27 17:07:18 CEST 2016


> 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.

BR,
Nikolaus

> 
> Best regards
> 
> Thierry
> 
> On 27/09/2016 16:05, H. Nikolaus Schaller wrote:
>> Hi Thierry,
>>> Am 27.09.2016 um 15:16 schrieb tgrauss <tgrauss at f-gp.eu>:
>>> Hello,
>>> Did you see this paper http://www.nordson.com/-/media/Files/Nordson/dage/Products/X-ray-Technical-Papers-and-Articles/Semiconductor-Inspection-and-Assembly/POP-paper-SMTA-2009-final.pdf ?
>> Not yet. It is really well written and gives a good overview of the
>> challenges and the process.
>>> They are giving other possible soldering failure causes for POP packages. I hope this will help...
>> I have worked through it to find a hint but unfortunately, I did not yet :(
>> The issue we have is not really PoP related. We have soldered two
>> DM3730 chips without PoP and they show the
>> same short circuit pattern in the middle as those with PoP. So it is
>> more a "soldering the DM3730" problem.
>> We already have checked the whole placement process by X-Ray and
>> placement is exact.
>> And we have tried placing the DM3730 into solder paste and just
>> dipping it into flux. Again no difference.
>> Interestingly the paper says that warpage usually leads to open solder
>> joints. This is not what we have seen. Not now and also not during the
>> GTA04A4 production.
>> So I would even conclude that warpage is not the problem. Unless the
>> DM3730 is very special with warpage so that it squeezes the BGA balls
>> in the innermost ring.
>> In addition, I have done a lot of experimentation today by unsoldering
>> chips and resoldering manually, trying different things.
>> But I never succeeded. I always have short circuits :(
>> One thing I can't easily compare and find out is if is an effect
>> created by the PCBs. For example the solder mask.
>> BR and thanks for this good paper,
>> Nikolaus
>>> Regards
>>> Thierry GRAUSS
>>> On 26/09/2016 18:51, H. Nikolaus Schaller wrote:
>>>> Hi all,
>>>> today we tried to solder the other side and get working GTA04A5 board,
>>>> but sadly we failed.
>>>> The boards look optically fine
>>>> but DM3730 has short circuits in the middle under the chip :(
>>>> The production company has recently bought their own X-Ray machine so that we can immediately see the problem.
>>>> But we don't know the reason.
>>>> Well, we know this problem exists with all OMAP3 and DM3730 chips and it
>>>> is warpage during the soldering process. Texas Instruments has published
>>>> some documents and application notes about this problem, but basically they
>>>> have no clear solution. Just a recommendation to experiment.
>>>> We already did fight a while with this during the assembly of GTA04A3 and
>>>> GTA04A4 boards,  but finally using a vapor phase soldering machine its was solved.
>>>> This time we also use a vapor phase machine right from the beginning. The
>>>> same that was used to produce some of the 600MHz OpenPandora and all 1GHz
>>>> OpenPandora devices. Which were successfully produced after some startup
>>>> issues.
>>>> We simply do not see any obvious reason why it fails so badly this time.
>>>> This needs some time to analyze and make more experiments (but ideally
>>>> not by wasting expensive and scarce chips and PCBs).
>>>> So I have to regret that we can't ship the first GTA04A5 boards this week
>>>> as planned.
>>>> I will keep you updated as soon as we find out something.
>>>> BR,
>>>> Nikolaus Schaller
>>>>> Am 25.09.2016 um 18:02 schrieb Neil Jerram <neil at ossau.homelinux.net>:
>>>>> Thanks for creating that video; previously I had no direct idea of what this kind of production is like.  It's very illuminating to see it.
>>>>>    Neil
>>>>> On 24/09/16 08:38, H. Nikolaus Schaller wrote:
>>>>>> Am 22.09.2016 um 17:31 schrieb H. Nikolaus Schaller <hns at goldelico.com>:
>>>>>> Hi,
>>>>>> we are coming closer...
>>>>>> I had a short meeting to discuss placement of some components today.
>>>>>> For example the position of the two LEDs is not easy to determine because
>>>>>> they are tilted a little.
>>>>>> But the whole GTA04 design is more complex than they thought, so that
>>>>>> they had much more work than planned to program the Siplace system.
>>>>>> This was intersting to see.
>>>>>> Basically they have a CAD system where they read in the Gerber files
>>>>>> and overlay Pick&Place positions and component packages. Components
>>>>>> can be shifted and rotated manually if needed. This is automatically
>>>>>> replicated for a multiple panel.
>>>>>> I have already seen the boxes with all components. Those are tempered
>>>>>> tonight and tomorrow they do the setup. Depending on how long it needs,
>>>>>> they can start tomorrow. Or Monday latest.
>>>>>> All this means they are again behind schedule. But not much and we can
>>>>>> be happy to have someone who produces so small quantities for us with
>>>>>> such elaborated machinery. And they have already produced many OpenPandora
>>>>>> devices so they know how to solder the PoP chips.
>>>>>> Anyways I will take a camera with me tomorrow so that I can show some
>>>>>> scenes from setting up GTA04 production then.
>>>>> Yeah! Here it is:
>>>>> https://youtu.be/8PZOa-789eY
>>>>> Everything looks good and the first boards have been populated by chips
>>>>> and connectors on the bottom side. This is the side where the display
>>>>> will be installed.
>>>>> The complex top side with OMAP3, package-on-package RAM+NAND and the
>>>>> 3G module will be done on Monday.
>>>>> Then we will also x-ray the boards to check if they are soldered properly
>>>>> without short circuits - and I will do the first function tests.
>>>>> Let's hope that there is no hidden design bug.
>>>>> BR,
>>>>> Nikolaus
>>>>>> It remains thrilling :)
>>>>>> BR,
>>>>>> Nikolaus
>>>>>>> Am 20.09.2016 um 09:04 schrieb H. Nikolaus Schaller <hns at goldelico.com>:
>>>>>>>> Am 14.09.2016 um 11:16 schrieb H. Nikolaus Schaller <hns at goldelico.com>:
>>>>>>>> Hi,
>>>>>>>> "next week" has arrived and it looked good for Friday
>>>>>>>> and I just waited for the final confirmation to take
>>>>>>>> my handy-cam and make a video of the production run.
>>>>>>>> Now I got an info that everything is prepared.
>>>>>>>> But it has turned out that the dipping machine for the
>>>>>>>> package on package memory chip is defective. It will
>>>>>>>> be repaired and is planned to arrive on Monday.
>>>>>>>> So production run will be Tuesday or Wednesday.
>>>>>>> It is now scheduled for Thursday... We have to wait 2 more days.
>>>>>>>> Please cross fingers :)
>>>>>>>> BR,
>>>>>>>> Nikolaus Schaller
>>>>>>>>> Am 07.09.2016 um 19:21 schrieb H. Nikolaus Schaller <hns at goldelico.com>:
>>>>>>>>> Next progress: it looks as if the first 20 units are built before end of next week.
>>>>>>>>> They will notify me and I can go there to make some videos.
>>>>>>>>> BR,
>>>>>>>>> Nikolaus
>>>>>>>>>> Am 05.09.2016 um 14:26 schrieb Roland Häder <roland at mxchange.org>:
>>>>>>>>>> Hi,
>>>>>>>>>> good to hear about the progress. :-)
>>>>>>>>>> Roland
>>>>>>>>>> H. Nikolaus Schaller – Mon., 5. September 2016 13:49
>>>>>>>>>>> Hi,
>>>>>>>>>>> production time is coming very close. Last Friday we discussed the final fine-tuning for the
>>>>>>>>>>> stencil for printing the solder paste.
>>>>>>>>>>> And now I got the confirmation that all components (incl. PCBs and BNO055) now have
>>>>>>>>>>> arrived. So I am eagerly awaiting when they have time on their production machines to
>>>>>>>>>>> build the first 20 units. I will go there and try to make some videos.
>>>>>>>>>>> So you can probably feel my excitement :) And nervousness (because I don't know if
>>>>>>>>>>> there is still one catastrophic mistake or bug in the design).
>>>>>>>>>>> BR,
>>>>>>>>>>> Nikolaus
>>>>>>>>>>> Preorders:
>>>>>>>>>>> http://shop.goldelico.com/wiki.php?page=GTA04
>>>>>>>>>>> http://shop.goldelico.com/wiki.php?page=GTA04%20Complete
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