Friday, August 12, 2011

My First Etched PCB for SMD

Ok, so I really wanted to try some SMD or surface mounted devices. I have ordered some parts for an amp-hour meter that are only available as SOIC. That's a little hard here cause I am renting an apartment in Carmen, Cebu Island, Philippines while my live aboard sailboat is being repaired in Republic Dry Dock, Danao, Cebu Is, PI.

Cebu is 45KM away and the second largest city in the Philippines apparently has no SMD component outlet. I see young people on the sidewalk in front of grocery stores with hot air reflow stations repairing cell phone circuit boards, but no parts. Could be I just haven't asked the right question. I did find a guy selling the hot air stations and standard DIP parts, but no small ones or unusual parts. He says everyone orders their own. I got blank board from him and the parts below.

The circuit I chose to copy for my first board was: LED Tester from the Robot Room

Since I couldn't find SMD parts, I opted for surface mounting some standard parts. No drill handy. My dremel is stored with most of the stuff from the boat.

The top of the board. I laid out the parts on a small piece of perf board then copied the paths with a Sharpie. Then I tried to touch up the lines with a really fine point one.The more I messed the worse it got. The dried ink seemed to make the Sharpie point act dryer than it was and rub off what I had prior.

The bottom, just to save the etch. All I had was a double sided blank.

Ready to roll! I've got the peroxide, the HCL and a baggie just bigger than the board.
I pour in a couple cap-fulls of peroxide, cause it says Always Add Acid. That means put other stuff before the acid. Then add a cap-full of Muriatic. Notice it says "PURE" on the label.

Then slip in the board.

That's not working very fast. What could be wrong. Maybe the acid isn't very strong. So I see the "Duck" in the bathroom has only one ingredient on the label, HCL. Maybe it is a little stronger.

On a second trip to the local Gaisano (grocery store here in the Philippines) I discover that Muriatic Acid comes in 29% or 19% or mild. I now have a bottle of the 29% for the next board.
So I add an equivalent cap-full of DUCK. Much better action and turns green like the others say it should.

Looks like 5 minutes or so and I have a reasonable facsimile of a DIY PCB.

Cleaned up and I see that my lettering is not so good, but the 1/16 traces(if you can call them that ) are ok. There is a "V" and an "A" at least I thought I drew them.

The finished board. I(t doesn't look so bad with components and at a distance.

My "Workstation"! Ha! I have to share the small plastic table with my wife and her hobbies, currently sewing a quilt(but that's another story).

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