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good/cheap heat press for DIY toner-transfer pcb's?

post #1 of 26
Thread Starter 
I just built my first toner-transfer pc board yesterday. it was fun

but the home clothes iron - that's a really ugly hack. I can't see how you can get reliable and consistent results this way.

I'm willing to spend a little bit on a heat press. but I don't know much about them or even what temperature and pressure I'll need to get this to work well.

anyone use one of those tee-shirt transfer presses for pc boards? or a laminating heat press?

I don't want a small heat element I have to move around. I'm ok with something like 12x12 inch boards as a max panel size so I should (?) be able to find a hobbiest heat press that will work in that size?

do you have one you can recommend?
post #2 of 26
Sorry to de-rail the topic a little, but I'm just wondering how the whole process went. I want to make a PCB for a Starving Student and I was thinking of making it this way.

Back on topic, I don't think its necessary to buy a $300+ piece of equipment when the iron does a decent job. Even if the iron occasionally screws up, it is only about $5-10 to start over.
post #3 of 26
Thread Starter 
time is money!

wasting time costs me more frustration than wasting money

I already had to redo a board 3 times with 'clothes iron sloppiness'. just hard to keep the heat pressed evenly and if you have an intricate pattern its even more important.

I don't mind spending $250 or so if I have to. I could go thru that in outsourcing pc boards (true, I'd get them cut, masked and drilled too) but the time turnaround is too slow for rapid prototyping.

the clothes iron was a good idea on-the-cheap but I'm ready to move up a notch
post #4 of 26
If you're willing to spend money, I'd recommend you shift to the photo-etching process. At minimum, you need a strong UV light source, and the boards themselves cost a little more. It's nice to have a proper etching tank with a heater and bubbler, but not essential. Much better use of funds than futzing with toner transfer.
post #5 of 26
Toner transfer works well for me with an ordinary iron, but I've learned a few things
1. use fine steel wool and clean/polish the board lots of fine scratches helps the toner grip the board.
2. Matt every day photo paper NOT glossy
3. Iron very hot, steam off
4. Drop the board into water when very hot I like to hear it hiss.
hope that helps
cheers
post #6 of 26
Thread Starter 
this is the first I've heard of avoiding glossy paper! I just bought some more generic glossy so I'll try but next time I'm out I'll get the matte style to compare.

@tangent: funny that you mention photo boards. I have some old (maybe not good anymore) photo developer and I tried it once (long time ago) but I probably didn't expose it long enough.

you still have to print to clear transparencies for this, though, right? isn't that going to crinkle the slide/foils enough to distort? maybe it works well if you use the right slide stock.

I am not sure that being stuck with pre-sensitized boards is going to be very cost effective. I have an ok collection right now of pc board blanks and I'm not even sure I like the idea of photo sensitizing them since you have to spray stuff on (in the dark) and it sounds more messy than I'd want.

my first toner transfer did work and it surprised me how WELL it worked. before giving up on the heat transfer toner style, I do want to at least try to find a heat press and give that a go.

alternately, I wonder if this trick might also work: heat up a cast iron skillet (large and heavy) and use THAT weighted hot thing to press down on the board. my problem with the iron is that it does not cover enough area and its irregular (meant to release steam thru holes in the base). really wrong thing to use for this! but maybe a super hot iron frying pan would work? problem is that once you remove it from the heat you have to hope there's enough heat to do the transfer.
post #7 of 26
I have to say that I have been toying with the idea of switching over to presensitized blanks and as soon as I figure out a way of reliably exposing double sided boards , I will tank the heat transfer for good.

I have had mixed success with the heat method - small boards are fine but the moment you near 4" X 5" it becomes a real PIA. The ground planes in particular are a real headache. I have actually been given a commercial heat press but I haven't bothered picking it up as I have no place to store it. Lining up double sided boards would also be a nightmare with a press.

Out of interest, I never found the photopaper to be any good and now look for the backing paper found on "stickers" ie large advertisement stickers used on cars/trucks or the backing paper for heavy duty drawer linings etc. This has a slightly waxy feel to it and after transfer, leaves a thin palsticized layer on the traces - less chance of unwanted corrosion.

This is one of the earliest boards I etched ( the CKKIII prototype)


I don't have images uploaded of some larger groundplanes to show you the mottled effect but that sort of frsutration would be a non-issue with the photoetch process.

If you find ways to do large surfaces which look clean, I would be very interested to hear of the technique.

..dB
post #8 of 26
I use the "celcast" or Kodak Matte every day paper and it's much better than the glossy, it seems to soak off easier. When heating I use the iron but I move it around like I'm ironing a shirt, I don't just press down I move it around a lot and keep a solid pressure on it, I also cover the board with a piece of kitchen paper so I don't accidently move the photo
post #9 of 26
Quote:
Originally Posted by Fred_fred2004 View Post
Toner transfer works well for me with an ordinary iron, but I've learned a few things
1. use fine steel wool and clean/polish the board lots of fine scratches helps the toner grip the board.
2. Matt every day photo paper NOT glossy
3. Iron very hot, steam off
4. Drop the board into water when very hot I like to hear it hiss.
hope that helps
cheers
+1, especially for point #1

I use the Press-N-Peel blue sheets. Works great with a regular iron.
post #10 of 26
Oh that stuff looks incredible, this must be the best kept secret !!

Thanks for the info kklee ..dB
post #11 of 26
Quote:
Originally Posted by linuxworks View Post
I probably didn't expose it long enough.
That, or you didn't use a strong enough UV source. Exposing longer increases the risk of light leakage around the printed traces.

Quote:
you still have to print to clear transparencies for this, though, right? isn't that going to crinkle the slide/foils enough to distort? maybe it works well if you use the right slide stock.
They sell acetate sheets made for computer printers. There are different sorts for laser vs. ink jet printers.

The only trick is to print it in reverse so you can put the printed side towards the board. Less light leaks around the printed traces that way than when there's a thickness of plastic between the printing and the light.

Quote:
Originally Posted by dBel84
as soon as I figure out a way of reliably exposing double sided boards...
I don't bother hand-etching double-sided boards. If I can't get it into a single side, maybe with a few jumpers, it's time to get professionally made boards. It's well worth the cost of the boards to avoid the hassle, and then you get the advantage of being able to do a denser design than you'd even dream of trying to hand-etch.
post #12 of 26
Quote:
Originally Posted by tangent View Post
I don't bother hand-etching double-sided boards. If I can't get it into a single side, maybe with a few jumpers, it's time to get professionally made boards. It's well worth the cost of the boards to avoid the hassle, and then you get the advantage of being able to do a denser design than you'd even dream of trying to hand-etch.
The problem with larger boards is cost - small boards can still manufactured for around $50 , but scale it up and you are looking at $200 for a single board - that is setup and production, obviously the more you make the lower the final individual cost. In this hobby of ours I feel there is still a place for prototyping with home etching and I am am now torn between the idea of photo etchig or this mylar film kklee linked to. I reckon that is the solution to my headaches at least.



this type of board is easily done double sided, if the transfer is good. That said, if having professional boards done was much cheaper, it would be a no brainer..dB
post #13 of 26
Thread Starter 
hmm, I think I might now give up on toner-transfer and try the photo and pre-sensitized board method.

one thing I'm finding is a lot of 'rough edges' when you iron on the toner. the amount of time and pressure seems to matter and one attempt that I did had the paper peel off perfectly AND not leave anything I had to scrub off! that was perfect and it was my first trial. the 2nd trial had paper stuck to the board (longer time holding the iron) and I had to scrub with a toothbrush and my fingers for a while to get the paper off. the board needed a LOT of touch-up. too much work that way ;( my third/last trial gave me a really neat blue look to the toner (not even black but blue shiny stuff). I still had to do a lot of touch-up with rub-on lines and pads.

I'm giving up on anything serious with the hack of toner transfer. for 'easier' boards it might work but I have traces going thru DIP pad alleys (how do you refer to this?) and with toner transfer, I can manage 1 trace between pads but it looks really ugly and usually needed touchup before etching.

I think the photo method will be more perfect and precise. you are only transferring 'light' and that's a LOT easier to precisely control than heat and pressure from a thing that was not at all 'lab grade'

the real problem I have with photo is that you can't easily use your own board stock. has anyone had luck spraying on (etc) the sensitizer themselves? is it worth it? I don't want to spend whole days doing this..
post #14 of 26
Use the boards you have now for making RF boxes and ground planes for ratsnest style prototypes.
post #15 of 26
Thread Starter 
I might just do a split; finish the ones I have for iron-on stuff (or whatever) but any 'complex board' should be done via photo.

I finally, after a few more tries, got a really clean all-blue iron transfer to work. I'm using office max (store brand) generic glossy photo paper. if you hold it under the iron for a good 5 minutes, you not only get the black toner lifted off the paper but some blue film backing also comes off - but the shiny gloss stays behind on the paper and there was NO cleaning or scrubbing - at all - needed! its really hit and miss with this method.

I think I'll try to get some commercial sensitized blank boards and try a pass at the photo method. how critical is the timing? I once just tried it and exposed it to sunlight for 'a while' (I forget how long I left it in the sun) - and the pattern did show up but I think the edges were fuzzy and not as sharp as I had wanted. could have been a case of not pressing hard enough on the film, on the board. but do I really need to get a fancy UV light?
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