Catwalker

Time for yet another new project, today I'm just posting part one. Part two will come later. Today I'll give some brief details about the printing of the PCB. Or "Printed Circuit Board". The project I am making isn't my own this time, but can be found here: Open Programmer It is a programmer for microcontrollers. Mainly, the Microchip PIC series.


Here are the raw materials for making the PCB, invisible is a piece of plywood (more on that a bit later) and no, the inclusion of a clothes iron is no accident. The newest tool in my staple of electronics bits and bobs. Why an iron?






Because for the first time,
I am using the
TONER.... TRANSFER.... METHOD....
as Bre Pettis from Makezine puts it.
The last time I made a PCB, it was about 17 years ago, I had no access to:

a) UV exposure boxes
b) Sensitised boards
c) developer
d) money for all of the above :)

I used to cover the copper clad board in wide strips of masking tape, draw on the pattern, cut it out with a sharp Xacto knife, paint the exposed copper with acrylic paint, let it dry, peel the tape away, patch up any damaged areas, etch the board. This worked, but it was overly time consuming, messy and couldn't really do fine traces. And the etch resist pens from Radio Shack were crap.

Check out this like: Make your own PCB's for the full explanation, the Youtube video references this site: Toner transfer method as explained by Thomas Gootee. Be very careful when using the etchant mix, I'm told it can become exothermic under the right (or should I say wrong?) circumstances, and it it needs to be used O*U*T*S*I*D*E or in a well ventilated space - it's toxic and it stinks. And if you get it on your mom's (or your wife's) stainless steel sink, you could be sleeping in the dog house. (You may be better off using ferric chloride - I was impatient so made my own etchant).

(BTW - If I were you, I wouldn't take Zander up his suggestion about amusing Law enforcement - There seems to be somewhat of a lack of a sense of humour on the part of a number of law enforcement officials --- some will be amused, others ... not so much -> just sayin :) )


I had a smallish piece of plywood, which I placed under the copper clad board, so I would n't damage anything underneateh. Here is my piece of plywood after ironing the paper pattern onto the copper clad board. It got pretty hot.







The board was hot enough to sizzle when I slid it into the bowl of hot water. As you can see, the paper is actually slightly scorched.





After about ten minutes of soaking in the hot water, I was able to carefully peel away part of the first layer of paper on the back, you can see the pattern from the paper plainly stuck to the copper clad board.





Here is the board with the paper gone ( a little bit of residue to clean up) I was surprised at the results, especially considering some of the traces are very small.




Board etched - I have deliberitely darkened the image a bit so you can see that the excess copper is gone, and the board is trimmed to size (about 2 3/4 x 4 inches) - just a couple of more things to do...



Board mostly complete, with the toner scrubbed off with acetone (use a mask, and ventilation - acetone is nasty stuff) - those couple of things to do? Clean it a bit (there are a couple of traces shorted together) and drill the holes - for that I need to get a couple of Carbide drill bits, FR4 glass epoxy and copper make quick lunches of HSS drill bits and band saw blades.


Coming up, once drilled, I will show off the completed project, and the reason I am going to all this effort.

じゃまた