Date: Thu, 23 Mar 1995 23:54:21 -0800 (PST) From: michal mcelhany Subject: PCB board etching method First I thought I'd mention an ugly but fun PCB etching method. The Idea is slightly stolen from Radioslack. For all that don't know, you can draw on printed circuit board with Sharpie permanent markers. Then etch and it's much more simple than paint. I use a crude surface mount(no holes) layout. For IC based designs I draw three lines down the center of a rectangle. for -15/+15 supply, ground is the center line and the + and - on either side at about an inch. Then on either side of the ground line I draw tally like marks for the IC pins. an example for an op amp lets yor draw pin 4 going straight to the negative supply and pin 7 drawn straight out to the +. Then I look at the schematic and figure what other pins will have the most items going to it. Those tally like marks I extend with bulb-shaped ends fitting within the space between power supply lines. Then I draw dots on every available space. Then start connecting everything using the dots as landing points. Give yourself a lot of room and it is very easy to troubleshoot. Connect the ground and power lines at the end of the board. Also when drawing look at the schematic and connect grounded pins with the center line that now runs between all IC's. This can be adopted for quad or dual op amps so your circuit boards can be small. Maybe some will scoff at this method, but I have built at least ten modules this way with little trouble. Only when I'm in a complete hurry do I run into trouble. This method can pump out single boards quick and is comprehensive in layout. Also for the etching solution use at least two inches(depth) and hold board in the middle by the edges.Without dipping into the acid... lay the board onto the acid's like a falling domino(softly..don't splash that acid boy's and girls) this keeps airbubbles from forming under the board. Use single sided PCB board so you can watch the etch progress through the clear underside. Pull out when done and clean with paint thinner. than a little SOS pad action. Goodluck!! Ian Stokes.