The "Solder Paste Dipping" on page 3 is a very interesting chapter. It
is more related to BGA soldering than PoP.
Best regards
Thierry
On 27/09/2016 16:05, H. Nikolaus Schaller wrote:
Hi Thierry,
Am 27.09.2016 um 15:16 schrieb tgrauss <tgra...@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
<n...@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
<h...@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
<h...@goldelico.com>:
Am 14.09.2016 um 11:16 schrieb H. Nikolaus Schaller
<h...@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
<h...@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
<rol...@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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