Hi Monkeytree, as I said in the other topic, I'll now go through how I do my boards. It's going to be long, but I hope it helps you. It'd be handy to know which country you are in, because I can tell you then where I get my board from, etc., it's the best board I've used so far and has allowed me to get incredible results for the first time.
First thing I do is draw my schematic in Eagle, available in a free version which is what I'm using, with limited board size (fine for most hobby circuits) from
www.cadsoft.de.
I then change to the board layout part of the program and set out the components, which I move around as I'm routing it. If using the autorouter, I save it before autorouting so that if I need to change things to get it to route better, I can reload the unrouted layout. Here's my present project after I've manually routed the entire board (autorouter isn't always very good):
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It's then ready for printing. I use Staedtler Lumocolor Inkjet Film (Transparencies), grade 0.10mm, part number: 639 30 A4 H. They work very well. My printer is an old Epson Stylus Color 740 and is capable of maximum resolution of 1440x720 dpi. In the printer preferences, I choose print media as Photo Paper, and set it to the highest resolution (as if printing out a photograph on to glossy photo paper). In the Eagle print settings, I make sure I choose 'mirror' so that the layout prints out mirrored, since the view in Eagle is from the top of the board. I then print out the layout 3 times, using a splicer to cut off the print-out from the A4 transparency sheet each time, so the print-out doesn't go through the printer again and get smudged to death. Each time cutting off more of the sheet, so when overlayed the pieces of transparency get smaller and thereby give room for sellotape to stick each one to the one below. They must be precisely positioned over each other, especially if there are tracks close together. Here are the three of them overlayed and stuck together:
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Now for the board. I use pre-coated photo-resist board from
www.maplin.co.uk (in the UK, hence why I wondered where you live), which seems to be excellent. I cut it to the correct size, peel off the protective plastic over the copper and then quickly position the transparency over it. Then I place a piece of glass from a photo frame over the lot (heavier the better) and, using a couple of plastic can tops from my foam cleaner and freezer spray, place a UV face tanner over it all, so the UV source is about 3 inches above the board. I used a test strip and exposed patches for different times to find out what was needed - 1 minute exposure didn't quite do it, but 2 minutes and above was perfect, so I expose for 2 minutes using a countdown timer. Here is the face tanner I use (it's my wife's, she's very lenient and accepting of me
), cos I can't afford £100+ for a little PCB UV box when I make, what, one board a year?
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After exposure, unlike some photo-resist boards I've used, you can't see any hint of the layout on the board yet really. I quickly take the exposed board into my developing room (the kitchen... oops, I've already got some chemical or other on the stainless steel sink, which is now
stained steel, and my wife was not overly impressed. I can't help being a mad scientist at heart!) and dunk the board into a tray of Carbonate-based developer. Rocking it back and forth constantly, I stand there and forget timing it, I just watch until I can see the layout magically appear and carry on until there is no photo-resist left between close-together tracks, etc. My developer is a bit past its best now, and it takes around a couple of minutes till I'm happy it's done. Doesn't much matter, I could leave it in there for 5 minutes and it wouldn't over-develop, Carbonate is so much more gentle than the caustic soda (Sodium Hydroxide developer) I used to use back in the day.
When that's done, I rinse the board and place it in warm Ferric Choride solution, and stand there rocking it for as long as it takes, sometimes 20 minutes or so - boring, but it makes it etch faster. Sometimes I pour the acid back into my jug and warm it some more in the microwave (how long till the inside of the microwave has disappeared, I wonder, and how will my wife react... ho hum) and then pour it back into the tray. Speeds things up no end. Having dried the board, I get my little 12V PCB drill out and start drilling the holes, which is easy thanks to Eagle leaving a hole in the middle of each pad, so the copper gets removed there, giving a simple reference point for drilling, and making it easier because the drill can bite straight into the board material without swirling around on shiny copper, trying to get a grip and cut. In fact, the comparitively hard copper actually acts as an auto-centre to push the drill bit towards the centre of the pad. Here's the board after etching and drilling:
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Then it's simply a case of populating the board and soldering everything in place. I print out a non-mirrored image of the board with components showing but not the tracks - as they make it hard to see the parts and values properly - and then use that to see exactly where I need to place components, and their respective orientations. Here it is with parts soldered in place:
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And from the top, complete with ugly looking cables running to the speakers and audio output on the soundcard, along with a large heatsink bolted to the IC:
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So there you have it. If you're still with me and haven't flat-lined or fallen, snoozing, to the keyboard, this might help you or anyone else to obtain good results. I've been doing boards for around 7 years now, and these are the best I've ever managed, so it's been quite a course of trial and error, I'm just glad that I finally discovered this method and good board from Maplin.
Best of luck to you,
James