I am slowing getting my feet wet in this technology. The ignition
computer is part through hole and part surface mount as my PCB
supplier had a limit on the number of holes,

I bought some solder paste from chip quick and it came in a 1/2 inch
plastic hypodermic needle. The plastic expanded and contracted when
you did not want it to :)

The gift that kept on giving :) Poor control over the size of the
solder paste dot.

So I made an aluminium version and went down on the cylinder size
for more control.

The $20 griddle can solder about 2 dozen of my surface mount boards
in 5 or ten minutes. It reaches 400 F which is about 220 C.

Paul Lamar


Paul,

My experience with surface mount is that it is best to have at least the
following:

1. Stencil
2. Solder Paste
3. Oven
4. Microscope

For very small production, may be I can ask my tech to help do for you
on his own time as I have the equipment in China.

If you decide to do it yourself. Then
1. Stay away from SMT ICs, especially fine pitched ones. It is very easy
to get solder bridge.
2. Use the largest possible size R, L, C. At least 0805. Don't even
think about 0402.
3. Solder paste needs to be in the refrigerator. Once open, it dries up
and thickens to almost a solid. In that case, you can slight heat it up
with a heat gun, and it will soften the paste and you can re-use it.

Hope that helps.

Henry

How are you doing Henry. It has been a while.
I am still not convinced it is the way to go for small scale production.

If you use the right machined pin sockets you can hide 1/10 watt resisters
and other through hole parts under the chips. 1204 surface mount parts
don't save much space if any.

Thanks for the tip on the solder paste in the fridge.

Here is my complete, programmable in BASIC compiler, ARM ignition computer.
Super fast. One usec pulses. Free IDE and compiler from Coridium.
Floating point hardware.

Paul lamar

Hi Paul, this might be useful:
http://pentondirect.net/view_online.asp?1253336&37e74bbcee4d84fb&18

Murry Rozansky

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