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From part-time hobbyist to advanced hobbyist?
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by adafruit on Wed Mar 12, 2008 7:18 pm

yknow my friend gave me a lamintor he said was for this stuff, he doesnt make pcbs by hand anymore
it says GBC on the front and has a Pulsar patch on the bottom. is that the one you use?

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by jasonx on Wed Mar 12, 2008 7:50 pm

Mine is the same one Pulsar recommend
Well I think as I had to source mine in the uk
Model is GBC Heatseal H65
You have to pass the board's through 4 or 5 times i have found (I'm using press and peel blue)
And if you are etching small boards you may have to do 2 as the pcb needs to be long enough so as not to fall between the rollers. ... urces.html
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by magician13134 on Fri Mar 14, 2008 4:07 pm

I bought some Tinnit, which claimed indefinite shelf life until mixed with water, so I plan to mix only a little at a time, does anyone know how much I need per square in of board (mostly copper since I use copper pour almost always now)
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by Kevin on Sat Mar 15, 2008 11:21 pm

magician13134 wrote:Image

Hi magician13134,
Can you let me know where you get this?
Thanks! :D
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by magician13134 on Sun Mar 16, 2008 12:34 am

Ace hardware.
shadow wrote:I found for organizing stuff, this is great. i put resistors, capacitros, things like that in labeled bins, and projects in the bottom big ones. you might wanna use one that is all small boxes, and one that is all big boxes, as mine has both, just not a lot of one. hope this helps

They're $25, and if you drop them, the drawers aren't covered well, so things can spill, but they're nice.
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Re: From part-time hobbyist to advanced hobbyist?

by adafruit_support_mike on Thu Feb 11, 2010 6:00 pm

WRT etching, I've spent a huge amount of time bashing my head against the toner transfer wall, and have finally developed a process that works.

The paper I use is fairly low-cost glossy stuff from Staples ($10/300 sheets). I can get moderate success from plain copy paper for what I consider 'large' traces (.030" and up), but the glossy lets me go down to .010" at .010" spacing with ease.

I don't use the standard "melt it onto the copper" process for toner transfer though. Instead, I use four chemicals: acetone, alcohol, borax and shellac.

Step 1 is to dip the printed trace pattern in acetone and let it dry (15 seconds total). The acetone melts the toner just enough to turn a layer of powder into a thin sheet of plastic. I find that it greatly increases adhesion and reduces pinholing.

Step 2 is to give both the copper and the toner a thin coat of shellac.. and I do mean thin. Start with a regular can of 3-pound-cut shellac from the hardware store, measure out 1cc into a separate container, then dilute it with 10cc of alcohol. I usually tint the stuff by pulling the ink reservoir out of a cheap magic marker and dumping that into the alcohol for a couple hours before adding the shellac (it makes the washing step that comes later a bit easier), but that's optional. Wipe a layer of the thinned shellac across both the copper and the artwork, and give them a few seconds to dry.

The shellac will do two things: first, it will act like hot-melt glue to hold the toner to the copper. Second, it will serve as an extra layer of etch resist. The reason you want really thin coats is a matter of aspect ratio: you're going to wash the unwanted shellac off with a weak solvent, and the toner will act as a resist that protects the shellac you want to keep. Thin layers of shellac mean very little exposed area between the edges of the toner traces and the copper, and thus less chance of undercutting the toner and lifting it off the board.

Step 3: Soak the paper. Dump it in a bowl of hot water and let it soak all the way through before applying it to the copper. You want the stuff flexible and pliable so it will conform to the surface of the copper. I had a major Aha! moment when I stopped thinking of paper as flat surface and started thinking of it as a fiber web that can be molded to fit the copper's surface perfectly.

Step 4: Lay the artwork on the copper and give it a quick roll with a dowel. Lay down a couple of layers of paper towel, put the board on that, paper side up, add a couple more paper towels, and give it a brisk roll. All you're really doing at this point is getting rid of air bubbles and squeezing out the excess water. Don't press too hard or the paper will squirm out of position, adhere just well enough that you can't get it back off without ruining a couple of traces, and generally cause you to flex your vocabulary.

Step 5: Heat the board. I lay it on a medium-heat hot plate for 5-10 seconds (paper side up), until the paper starts to dry out. Shellac melts at about 80C (180F), so when the paper goes from 'wet sponge' to 'damp sponge' you've gone far enough. Don't let the paper dry all the way out, though, or it will buckle away from the copper.

Step 6: Pull the board off the hot plate, sandwich it between paper towels again, and give it another roll with the dowel. Go ahead and use moderate pressure this time, but don't skimp on the towels. Ingtalio printers (the people, not the devices) use thick wool mats between the press roller and the paper to make sure the paper goes all the way into the grooves that hold the ink. In this case, we want to make sure that every square millimeter of the printed surface makes full contact with the board.

Step 7: Scrape the back of the paper lightly with 120-220 grit sandpaper. You're not trying to sand all the way through the paper here, just scuffing the clayed surface of the paper so water will soak through faster.

Step 8: Re-soak the board-and-paper in hot water, re-heat, and re-roll a few times. I do six passes on the theory that six standard deviations puts the chance of bad adhesion at around 1/1,000,000. Besides, it's fast and easy.

Step 9: Soak the board again and start peeling away the paper. You want to be fairly gentle at this point, brushing off rolls of fiber rather than ripping up huge strips of paper. Use lots of water and very little force, and above all, resist the temptation to scrub at the surface.. that will cut through the toner faster than anything. The goal is to brush away all the fiber, leaving the layer of shellac and embedded toner undisturbed. When you do it right you'll still have a very thin layer of clay from the surface of the paper on top of the shellac, and the surface will feel like fine-grit sandpaper.

Step 10: Remove the excess shellac. Shellac has an interesting range of thermal and chemical properties.. it's thermoplastic in the 70-100C range, it thermosets at about 160C (though I don't recommend baking PCBs at that temperature), and it has two different kinds of solvents: alcohol and mildly alkaline solutions. That's where the borax comes in. Mix about 1 teaspoon of borax in 1 cup of warm water and you have a solvent that's strong enough to take the exposed shellac, but completely incapable of penetrating the toner. Warm the board on the hot plate and then brush the borax-water across it. When you have the temperature right the exposed shellac should lift off easily.

Like I said earlier, adding some color to the shellac makes it easier to see when you've gotten it all off. I tend to do another half-dozen rinses after I'm reasonably sure I've gotten everything, just to be sure, since again each pass is fast and easy.

Step 11: Dry the board and inspect it for broken traces, pinholes, etc. You can fix large problems with a Sharpie.

Step 12: Wipe-etch. I use cupric chloride and a small makeup sponge.. dip the sponge in the cupric and wipe it gently across the board. The exposed areas should go salmon-pink, areas still coated with shellac will stay bright. If the whole board looks good, you're ready to dump it in the etchant bath. If there are problems, you'll see them before you ruin a board. If you lose the resist entirely at this point, you can still sand the board with 1200-grit paper and start over.

The whole process takes me 5-10 minutes per board, and I lose maybe one resist in ten if I'm moving fast (usually during steps 9 or 10). I've done a few graticules to test the resolution of the process, and have found that I'm basically limited by my printer. 010/010 (10 mil trace, 10 mil spacing) is easy, 007/007 is doable, and 005/005 is too tight for an HP91 to resolve cleanly. 005/007 is tricky but feasible, and I can't solder at that kind of pitch anyway.

BTW - the board material I use is 1/32" Garolite FR4 single-sided from McMaster-Carr. It's fairly inexpensive ($25 for a 2' x 3' sheet) but not the lovely smooth stuff you'll see in precoated boards. The texture of the fiberglass mat is clearly visible on the copper surface, and there are the occasional pits and dimples. This process gives easy 010/010 resolution on that kind of surface, so it should work just fine on the good stuff.
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Re: From part-time hobbyist to advanced hobbyist?

by sirket on Thu Feb 11, 2010 7:24 pm

For storage recommendations see this thread:

Get a decent iron. I prefer Weller because of the huge variety of tips and parts available. Others will have their own recommendations. Do not spend more than $125.

Do _not_ buy a microscope unless you have really poor eyesight and absolutely need it. I have a Mantis Elite Stereo scope- it's awesome- and it's mostly useless except in oddball cases. It can be a lifesaver- but it's definitely not worth the money unless you have everything else.

A good iron, good tips, good solder, good flux, good braid, some basic hand tools, and a decent multimeter are all you really need on the tools side. As for etching- that's a whole other can of worms. My setup has gotten out of hand. I prefer UV exposure for the increased accuracy it provides. By the time you go through all the trouble, however, it's a lot of effort for minimal reward in most cases. It's also only really useful for single sided SMT boards- or double sided if you have a decent through hole system.
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Re: From part-time hobbyist to advanced hobbyist?

by adafruit on Thu Feb 11, 2010 11:41 pm

oh you know this should be moved to Tools

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Re: From part-time hobbyist to advanced hobbyist?

by AdHoc on Fri Jul 23, 2010 12:10 am

I'm curious, I only gave tone transfer a couple of goes before switching to pre-coated photoresist boards. The results were much better (I expect my toner technique was poor) and I didn't think there was much difference in costs overall.
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Please be positive and constructive with your questions and comments.