Post by thread:PCB Methods: Iron On Transfers

Dear PICsters, One method for making printed circuit boards is to use commercial iron on transfer products, such as DynaArt Transfer Paper. I have been using the DynaArt Transfer Paper for a couple of years. When I first started I used an iron and got mixed results. Smaller boards generally came out OK, but anything much larger than the iron itself created a problem. I finally stopped playing around with the iron and ordered the SuperFuser, which is a laminator modified for a different temp range, and much slower feed rate. The advantages of the SuperFuser are: 1) consistency of results, and 2) once it is loaded you can do something else with your time. The SuperFuser once properly adjusted for temperature, gives me excellent boards. Note that different brands of toner require slight changes in the temperature setting! In the interest of helping others, here is a quick outline of how I do my own PC Boards. 1) Clean the PCB blank vigorously with a Scotchbrite pad. This mechanical cleaning is very important. The pcb blank should be shiny, and when water is applied the water should cover the surface uniformly. 2) When the mechanical cleaning is done I then clean it with a little TSP solution(Tri Sodium Phosphate). This helps remove fingerprints, grease, etc. Rinse thoroughly in running water to remove all chemicals. 3)I then wipe dry with a CLEAN cotton wipe, making sure no lint remains. Make sure *both* sides are completely dry. 4) I preheat the board with either a heat gun by waving it evenly over the surface, or by placing it in a little oven I have that was originally designed for drying glassware. This pre-heating helps, because when a cold board is placed in the SuperFuser there is a large temperature gradient, and the part of the board that goes in first would otherwise not get as evenly heated as the last part of the board. 5) When the board exits the SuperFuser I turn it around 90 degrees and run it through again immediately. If you do not do this, then you will sometimes find that long runs that are parallel to the board travel direction tend to lift off. 6) When the board comes out of the SuperFuser the second time, I let it sit on a dry cloth for about three minutes. This allows the board to cool slowly. Rapid cooling can cause the pattern to pull away from the board. 7) Once the board is cool to the touch, then I place it in a pan of room temperature water and let it sit for as long as it takes for the paper to float loose. Avoid the temptation to speed the process up by aggressively agitating the water, as this can cause sections to lift. You might also find it useful to preheat the transfer paper that has the image on it. This preheating helps to cause any tiny toner pinholes that may be present to disappear as the toner melts slightly. You have to be careful not to overdo this preheating. The idea is to allow pinholes to close up, but not to allow any dimension changes in the toner image. If you experience any problems with dimensional shrinkage of the image, then you might want to preheat the transfer paper *before* running it through the Laser Printer. That will cut shrinkage down by at least half. I usually make smallish PCBs, so I don't often have to resort to this. As regards toner. I use an el-cheapo re-manufactured cartridge to do my proofs, but the actual tranfer is done using an original cartridge. I prefer the cartridges that have the extra-fine toner. These are sometimes sold as 'extra black graphics cartridges', or 'specially formulated for high resolution graphics work' or something to that effect. I happen to use a 1200 DPI (true resolution) Lasermaster Unity 1000 printer. I have found that the 300 dpi printers are not high res enough. 600 DPI is useable. 1200 DPI is excellent. This goes not only for direct tranfer PCB work, but also if you are preparing your own 1:1 transparencies. When I do photographic versions of my PCB designs I usually produce artwork that is 1.5:1 or 2:1 and then have it photographically reduced to actual size. This allows for very fine lines, such as those that go between IC pins. And, it goes without saying, don't forget to make sure that the image you PRINT is a mirror image. I have had my fair share of times when I rushed a job only to discover that I had failed to flip the image first. I always try to have some lettering on the design that helps me know when I have made this mistake. Better to mess up just a sheet of transfer paper than to actually etch the board before you find the mistake! I try not to waste the special transfer paper so as to save money. I usually arrange my mirrored image so that it will fall at the bottom corner of a sheet of paper. I first print onto a regular sheet of paper, then I cut out the corner that has the toner design on it, leaving a margin of between 1/4 and 1/2 inch. I then use Scotch Tape to hold on a section of transfer paper that slightly overlaps the section cut out. The shiny side of the transfer paper should be facing where the toner will be applied. I then load this modified carrier sheet and print the image again, with the exact same settings as before. I adjust my printer so that the sheet comes straight out the back of the printer, instead of turning around and coming out the top. This helps to insure that the taped transfer paper does not get stuck in the printer. BTW, use 3M Scotch tape, and not some cheap imitation, as some of the imitations cannot take the heat of the printer, and they will melt inside and make a real mess. I do my etching with Ammonium Persulphate that I purchase from Mouser Electronics. My etcher is a slightly modified version of the etcher sold by DynaArt. I made a few changes to enhance the flow of etchant. Originally the pumps would give me trouble. They were designed for pumping water, and the extra densisty of the Ammonium Persulphate solution was just enough to sometimes cause one or more of the pumps to stall. I modified the pumps by cutting the rotor blades down a bit, and now they pump reliably. I can generally etch a board in 3 to 5 minutes with fresh etchant that has been heated. Room temperature etchant takes twice as long. Hope this helps. Fr. Tom McGahee

Where can the "SuperFuser" be found ?? Thanks for the information, it will be helpful !! Regards --- Thomas McGahee <spam_OUTtom_mcgaheeTakeThisOuTSIGMAIS.COM> wrote: {Quote hidden}> Dear PICsters, > > One method for making printed circuit boards is to use commercial > iron on transfer products, such as DynaArt Transfer Paper. > > I have been using the DynaArt Transfer Paper for a couple of years. > When I first started I used an iron and got mixed results. Smaller > boards generally came out OK, but anything much larger than the > iron itself created a problem. > > I finally stopped playing around with the iron and ordered the > SuperFuser, which is a laminator modified for a different temp range, > and much slower feed rate. > > The advantages of the SuperFuser are: > 1) consistency of results, and > 2) once it is loaded you can do something else with your time. > > The SuperFuser once properly adjusted for temperature, gives > me excellent boards. Note that different brands of toner require > slight changes in the temperature setting! > > In the interest of helping others, here is a quick outline of > how I do my own PC Boards. > > 1) Clean the PCB blank vigorously with a Scotchbrite pad. > This mechanical cleaning is very important. The pcb blank should > be shiny, and when water is applied the water should cover the surface > uniformly. > > 2) When the mechanical cleaning is done I > then clean it with a little TSP solution(Tri Sodium Phosphate). This > helps remove fingerprints, grease, etc. Rinse thoroughly in running > water to remove all chemicals. > > 3)I then wipe dry with a CLEAN cotton wipe, making sure no lint > remains. Make sure *both* sides are completely dry. > > 4) I preheat the board with either a heat gun by waving it evenly > over the surface, or by placing it in a little oven I have that > was originally designed for drying glassware. This pre-heating > helps, because when a cold board is placed in the SuperFuser there > is a large temperature gradient, and the part of the board that goes > in first would otherwise not get as evenly heated as the last > part of the board. > > 5) When the board exits the SuperFuser I turn it around 90 > degrees and run it through again immediately. If you do not do this, > then you will sometimes find that long runs that are parallel > to the board travel direction tend to lift off. > > 6) When the board comes out of the SuperFuser the second time, > I let it sit on a dry cloth for about three minutes. This allows > the board to cool slowly. Rapid cooling can cause the pattern to > pull away from the board. > > 7) Once the board is cool to the touch, then I place it in a pan > of room temperature water and let it sit for as long as it takes > for the paper to float loose. Avoid the temptation to speed the > process up by aggressively agitating the water, as this can cause > sections to lift. > > You might also find it useful to preheat the transfer paper > that has the image on it. This preheating helps to cause any > tiny toner pinholes that may be present to disappear as the > toner melts slightly. You have to be careful not to overdo > this preheating. The idea is to allow pinholes to close up, > but not to allow any dimension changes in the toner image. > > If you experience any problems with dimensional shrinkage of > the image, then you might want to preheat the transfer paper > *before* running it through the Laser Printer. That will cut > shrinkage down by at least half. I usually make smallish PCBs, > so I don't often have to resort to this. > > As regards toner. I use an el-cheapo re-manufactured cartridge > to do my proofs, but the actual tranfer is done using an > original cartridge. I prefer the cartridges that have the > extra-fine toner. These are sometimes sold as 'extra black > graphics cartridges', or 'specially formulated for high > resolution graphics work' or something to that effect. I happen > to use a 1200 DPI (true resolution) Lasermaster Unity 1000 > printer. I have found that the 300 dpi printers are not high res > enough. 600 DPI is useable. 1200 DPI is excellent. This goes > not only for direct tranfer PCB work, but also if you are > preparing your own 1:1 transparencies. When I do photographic > versions of my PCB designs I usually produce artwork that is > 1.5:1 or 2:1 and then have it photographically reduced to > actual size. This allows for very fine lines, such as those that > go between IC pins. > > And, it goes without saying, don't forget to make sure that the > image you PRINT is a mirror image. I have had my fair share of > times when I rushed a job only to discover that I had failed to > flip the image first. I always try to have some lettering on the > design that helps me know when I have made this mistake. > Better to mess up just a sheet of transfer paper than to actually > etch the board before you find the mistake! > > I try not to waste the special transfer paper so as to save > money. I usually arrange my mirrored image so that it will > fall at the bottom corner of a sheet of paper. I first print > onto a regular sheet of paper, then I cut out the corner > that has the toner design on it, leaving a margin of between > 1/4 and 1/2 inch. I then use Scotch Tape to hold on a section > of transfer paper that slightly overlaps the section cut out. > The shiny side of the transfer paper should be facing where > the toner will be applied. I then load this modified carrier > sheet and print the image again, with the exact same settings > as before. I adjust my printer so that the sheet comes straight > out the back of the printer, instead of turning around and coming > out the top. This helps to insure that the taped transfer > paper does not get stuck in the printer. > > BTW, use 3M Scotch tape, and not some cheap imitation, as > some of the imitations cannot take the heat of the printer, > and they will melt inside and make a real mess. > > I do my etching with Ammonium Persulphate that I purchase from > Mouser Electronics. My etcher is a slightly modified version > of the etcher sold by DynaArt. I made a few changes to enhance > the flow of etchant. Originally the pumps would give me > trouble. They were designed for pumping water, and the extra > densisty of the Ammonium Persulphate solution was just enough > to sometimes cause one or more of the pumps to stall. I > modified the pumps by cutting the rotor blades down a bit, and > now they pump reliably. > > I can generally etch a board in 3 to 5 minutes with fresh > etchant that has been heated. Room temperature etchant takes > twice as long. > > Hope this helps. > Fr. Tom McGahee > _________________________________________________________ Do You Yahoo!? Get your free @yahoo.com address at http://mail.yahoo.com

[snip] > 5) When the board exits the SuperFuser I turn it around 90 > degrees and run it through again immediately. If you do not do this, > then you will sometimes find that long runs that are parallel > to the board travel direction tend to lift off. > > 6) When the board comes out of the SuperFuser the second time, > I let it sit on a dry cloth for about three minutes. This allows > the board to cool slowly. Rapid cooling can cause the pattern to > pull away from the board. > [snip] Thanks for these tips, i think i may want to try this before i retire my SuperFuser. Having tried this method with the SuperFuser, I personally prefer the Photoresist method in terms of accuracy. However, the Toner-Transfer method has great appeal, as it requires no dark-room, or specially prepared PCB blanks. Another tip that was given by a PIClister a while back, and what prompted me to try this method in the first place, is to use 'Epson Photo Paper' for Inkjet printers. I think it works even better than the TTS stuff, because it leaves a thicker coating on the copper (some of the paper actually comes off with the toner). And it is much cheaper to boot. For those struggling with UV-resistant inks from their printers, i have a possible solution: you might want to try "Kodalith" film. It's black-white contrast film used in the printing industry. You expose your image onto the Kodalith, then from the Kodalith to the PCB. The drawback is that it is somewhat costly. It only comes in a box of 100, at close to $200 for 8x11 size. I have not tried this yet, only because I am still looking for someone to sell me a few sheets to test the results.