[Gta04-owner] GTA04 Production Status

[Dr. H. Nikolaus Schaller]

Hi all,
since last Friday things have developed very positively.

The production company did borrow a small vapour phase
soldering (condensation soldering) machine and tried on Friday
afternoon to solder some boards with this.

Results are excitingly good. Much better than with the big
reflow machine.

Therefore I asked them to do some tests to simply solder
a second time some boards that had some minor issues
(e.g. no sound, no GPS, no WLAN etc.) and therefore did
pile up instead of being shipped. In some cases this simple
resoldering was sufficient to make the hardware bugs go away.

So they continue with this hand-operated machine to produce
the still missing boards. And tomorrow they will start to
resolder/rework the others.

This means:
* some more boards are now ready for immediate shipment
* I have already notified the next buyers on the waiting list
   to confirm their shipment address
* there will be as many boards to ship by end of this week
   as in the past 2 months, i.e. more than we can test, flash and
   pack immediately
* I expect that we can now work through the backlog quite
  quickly
* So if you ordered the installation service, please prepare
  to send your GTA02 to us.

What makes the vapour phase soldering machine so much
better?

The reason is how heat is brought into the board, the
components and the solder balls. In standard reflow this
is done by hot air @ approx. 260 degrees. This air tries to heat
up the PCB and the chips and there may not be enough air
to go under the BGA chips since they are very small and
we have tightly packed components to fit into the small case.

I.e. there isn't enough heat (air is a weak heat transport medium)
and therefore some BGA balls don't melt and after cooling down,
there is simply a missing connection. And one missing connection
is sufficient to make the board fail to pass all tests.

Now with vapour phase the medium is a special liquid
that boils at 230 degrees. This creates some fog above
the liquid and the PCBs are simply put into that fog.

Like humidity makes your glasses wet when entering a
building in winter because they have been cooled down,
the fog makes the colder PCB, Chips and Solder balls
wet. And since the liquid can flow much easier between the
BGA balls and has a much higher energy transport capacity,
all these parts are warmed up to the 230 degrees of the
fog and the solder must melt. This process is much more
reliable in soldering the BGA balls.

And, it uses a lower temperature! This finally reduces the
warpage of the DM3730 chip we had already been fighting
with for a while.

So in summary it uses a different physical principle that
is much more robust.

When choosing a production facility for future GTA boards
we will keep this in mind and check if they have such
a soldering machine :)

Nikolaus

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