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Hello,i would like to ask about the photoresistive boards,if there is a colour that does not affect the photoresist to use it as a safety light in the dark room while i prepare the board.I can not turn on the lights in the room,i use the light from some leds away far for the board,but i cant see clear and the film up in the board most of the times is not aligned perfectly even in a single layer board,in double layer things sure will become even worst.

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The board material I use comes pre-coated with positive resist. It isn't affected by daylight during processing.

Leon Heller G1HSM

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As i read from the web,many people expose the boards to direct sunlight for development.This means that the coat of the board is affected from sunlight.I dont know if the light from some red leds in relatively small distance from the board is safe to used,something like in photography printing.

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Photoresitive film is sensitive to UV that is present in direct sunlight.
UV LEDs may be used for exposing.

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geoelec wrote:
As i read from the web, many people expose the boards to direct sunlight for development. This means that the coat of the board is affected from sunlight. I dont know if the light from some red leds in relatively small distance from the board is safe to used,something like in photography printing.

But it takes a lot longer to develop a photo sensitized PCB with the UV emitted from the sun, then it does with a PE2 high intensity UV incandecent bulb.

When I was using Kepro's (no longer in business) presentisized photo sensitive PCBs, I never had any problems working with them in regular room lighting.

These days, I use my laser printer and a laminator to put the artwork patterns on the PCB material - actually, I've been using direct etch for about the past fifteen years.

You can avoid reality, for a while.  But you can't avoid the consequences of reality! - C.W. Livingston

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If what you are designing is a one piece then the photoresist method Carl explains works well. I at one time tried this paper that you ironed on to standard copper clad and then into the etchant. Don't remember if it worked though.

If you are planning on making three or more boards then take a look at easypcb. The software is free and the cost to have the boards made is rather reasonable. Several of us here use them and not too many complaints.

Jim

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Atmel Studio6.2/AS7, DipTrace, Quartus, MPLAB, RSLogix user

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Last time I etched a board I used a technique where you use a laser printer and print on magazine paper. Then you use a clothing iron and "iron" the toner to the copper, which becomes your etch resist. Then dunk it in the etchant.

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Actually, that paper I use is decal paper, just like what you put decals on with for model cars and air planes.

The ironing doesn't work too well, I've found. I purchased a GBC laminator and modified it to accept .063 thick PCB material. The modification instructions were on the Internet for a long while, until they discontinued that particular model laminator.

The basic procedure is:

1. Make your PCB artwork, using your favorate PCB software.

2. Print out your PCB artwork, using your favorate laser printer.

3. Place the printed PCB artwork, with the toner against the Copper cladding.

At this point, I always run my artwork/PCB through the laminator twice to ensure proper fusing of the toner to the Copper cladding.

4. Place the toner paper/PCB blank in a tray of cold water.

5. Wait for a while and the paper will separate from the toner, the paper, eventually floating to the water surface.

6. Run the patternized PCB blank under hot water until the PCB is near water temperature. This helps dry the uncovered copper faster, reducing spots left by evaporating water.

7. Using a bath towell, place the PCB blank between two sections of the bath towell and - GENTLY - pat dry.

I also use that TPC bonder what coats the toner with a polomar that further protects the toner. This is done using the laminator, as well. The plastic carrier simply peels back, once the PCB blank cools to room temperature.

From here, use your favorate etching method to remove the unwanted copper.

Of course, I automate the drilling of the PCB so, I actually do the drilling between steps 2 and 3 on my table-top mill, using a jig that squares and gauges the PCB blank.

After the PCB is etched, I put the etched PCB blank back into my mill, in the same orentation as I took it out, performing any routing at this time.

Finally, I strip the polomar and toner and then tin the copper traces using Tin-It.

The PCB is now ready to have parts mounted.

Let me state here, cleanliness is EVERYTHING when it comes to making a good quality PCB using the method described above.

You can avoid reality, for a while.  But you can't avoid the consequences of reality! - C.W. Livingston

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I use milling to do both double and multilayer boards. No chemical etching. Milling down to 4 thou ( thousandth of an inch). Drill 0.3mm ( 12 thou ).

I use direct laser imaging on the solder mask. Screen print blank solder mask layer and then image it with a laser and develop under sodium carbonate solution.

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hehe

And if you're using the transfer system, DON'T FORGET to reverse the image when you print it.

Used to erase UV eproms by setting them out on the wall for a few days. Made a program that scanned for any 0 bits to tell if one was "done."

If you don't know my whole story, keep your mouth shut.

If you know my whole story, you're an accomplice. Keep your mouth shut. 

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Recently i made a pcb with toner transfer method but in the half side the toner placed and in the other not,some other had printed well,but if not then you have to do many more work to do to fix it with soldering wires and adding the time to draw pcb to computer,printing and toner waste,ironing,etching,drilling it is better or to use a photoresist board from the beggining or a breadboard.

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Tried toner transfer a couple times with "inkjet photo paper." That was hard and never got it to work. I never tried it with magazine paper. I use the blue transfer paper. This stuff has a water soluble surface you print the toner on. I scrub the board with a dry scotchbrite till it's bright and shiny. Be careful not to miss the edges. Then scrub the board with "91" (91% isopropanol). Dry it with air. THEN use a laminator, not an iron, to apply it. Run it through like 10 times. I change direction and position on the roller on each pass. Board should be to hot to hold for long. Then let it cool down and soak in water until the paper comes off on its own.

I still sometimes get a gap in traces near the edge. Maybe should get some uv LEDs.

If you don't know my whole story, keep your mouth shut.

If you know my whole story, you're an accomplice. Keep your mouth shut.