Tuesday, March 3, 2009

My first SMT build

I saw a PIC Logic Tester kit being offered by JayCar which uses SMDs. I built a TTL/CMOS probe in my previous life as a hardware designer in the 70s but hadn't updated to the new lower power technologies. I need a logic probe so this was a good start.

Kit arrived this afternoon and I nearly died when I saw how small the components really are. But under the magnifying lamp I could read their values or markings and the PCB looked a lot clearer. So I fired up my new soldering iron and commenced work.

Six hours later it's finished. Lots of problems encountered and overcome. The worst was when I squeezed too hard on the tweezers and a capacitor shot out and I have no idea where in the room it landed. I spent 15 minutes looking but couldn't find it, so decided to proceed without it, hoping it wasn't too critical. But then I found it under the board itself. 0603 components are the worst for hand assembly.

I also discovered I probably had the iron too cold initially. I started with 350C but moved it to 375C and joins seemed a lot quicker and 'wetter'.

Now I've realised I don't have a circuit to test it on so my next project will be to use the FreeScale sample chip I got a while ago to build a simple counter or whatever and I can check my new logic probe on that.

I was delighted to run the 'blinktest' demo program on my S40C18 and display a 291Hz square wave from one of the pins on my new oscilloscope.

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