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Author Topic: Toner transfer and tqfp  (Read 2502 times)

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Offline z.s.tar.gzTopic starter

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Toner transfer and tqfp
« on: March 21, 2010, 06:11:50 PM »
Has anyone actually done this themselves and it work?
How much practice is required to get it right?
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Offline dunk

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Re: Toner transfer and tqfp
« Reply #1 on: March 21, 2010, 07:13:47 PM »
hi ZS,
yes and loads.

the biggest time sink for me was finding a suitable paper.
do your self a favor and ignore all the recommendations for ink jet-paper. some do work but some have a plastic film in them so take days to dissolve in water.
instead i use the backing paper from sticky labels. don't soak in water, just peel it off.

the next time sink will be how hot to iron it on. on my clothes iron i use a small bit cooler than the "cotton" setting.

one other thing: if you feed a sheet of paper through a laser printer more than once the image does not come out as well the 2nd time.
if you want to put more than one "transfer" on a sheet, it's better to cut the sheet and feed each piece through rather than send the whole sheet through multiple times.
(i have no idea why this is. i *think* it might be due to static charge on the paper but this is speculation.)


with a bit of practice you'll get a good image transfer 70% of the time and a good etch (no broken tracks etc) about 70% of the time for tqfp parts.

that's with practice though. be prepared for your first one to take at least 10 attempts.

i guess the question is: how patient are you?


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Offline Ro-Bot-X

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Re: Toner transfer and tqfp
« Reply #2 on: March 21, 2010, 07:18:47 PM »
Quote
with a bit of practice you'll get a good image transfer 70% of the time and a good etch (no broken tracks etc) about 70% of the time for tqfp parts.

that's with practice though. be prepared for your first one to take at least 10 attempts.

i guess the question is: how patient are you?

See, that's why I send my boards to a fabhouse...
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Offline z.s.tar.gzTopic starter

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Re: Toner transfer and tqfp
« Reply #3 on: March 21, 2010, 07:41:17 PM »
See, that's why I send my boards to a fabhouse...

I don't have a friggin month to wait for a pcb though, so no dice.

I'd say I'm a pretty patient person so I guess I'll order all the stuff tomorrow.
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Offline Soeren

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Re: Toner transfer and tqfp
« Reply #4 on: March 21, 2010, 09:58:51 PM »
Hi,

instead i use the backing paper from sticky labels. don't soak in water, just peel it off.

That is OK if you use a lot of labels, but a little pricey if you just bin them to get the backing.
Now I don't know how hot the fuser gets, but how about using Teflon (reuseable) baking paper?

I'd imagine that it cleans off well for reuse and it's around $3.50 to $4.- in DK, so probably cheaper anywhere else.
Teflon "Paper" 1 and Teflon "Paper" 2 is a bit more expensive (since it's brand names i guess).

The types available to me locally is yellowish (like raw Kevlar) and approximately the size of a baking plate (I use this for lots of stuff) and black in circular shape for using in a frying pan.
I think they have a max. temperature limit of 260°C - I haven't ever gotten numbers on a fuser, so don't know if it will work, but hey, if regular paper goes through, why wouldn't a baking paper?

Some of my "papers" have got a very slight weave pattern, which may or may not present a problem.
Regards,
Søren

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Offline dunk

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Re: Toner transfer and tqfp
« Reply #5 on: March 22, 2010, 03:44:00 AM »
That is OK if you use a lot of labels, but a little pricey if you just bin them to get the backing.
Now I don't know how hot the fuser gets, but how about using Teflon (reuseable) baking paper?
sounds promising.
i *think* my iron is set around 180C when the toner fuses . (although my memory might be wrong here.)
either way, it's not all that hot.

as for re-using the paper,
that would be theoretically possible with the label backing paper as well but see my comment about feeding paper through the printer more than once.
as i speculate it's a static electricity issue maybe leaving it for some time between prints would help.
as i don't know the root cause of this problem it's hard to speculate about solutions without experimentation.


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Offline Soeren

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Re: Toner transfer and tqfp
« Reply #6 on: March 22, 2010, 01:02:43 PM »
Hi,

i *think* my iron is set around 180C when the toner fuses . (although my memory might be wrong here.)
either way, it's not all that hot.
Great!


as i speculate it's a static electricity issue maybe leaving it for some time between prints would help.
I don't think static is the issue, as the paper is made static first, then a LASER kills the static where there should be no toner before it "dusts" the paper and "bake" it.
I assume you wanna do it to increase the amount of toner or "repair" missing spots/pinholes, but there will allways be a slight amount of toner hitting the "white" and repeating may make that worse.
I would think that it wasn't precise enough to print exactly the same place either?

Now if I had a small cheap LASER printer with a linear paper feed, I'd rip it apart and make a PCB feeder for it - that would speed things up ;D

When I used toner transfer, I usually went over the PCB with a small knife and a Sharpie before etching.
Regards,
Søren

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Offline guru

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Re: Toner transfer and tqfp
« Reply #7 on: March 26, 2010, 08:00:42 AM »
I use this guy's stuff and I get awesome results:
http://www.pulsarprofx.com/

I've tried most methods, including the traditional photo transfer development which gives great results once tweaked but is a longer process and a chemical one. Read the site, everything I read there I have found to be 100% accurate. I can get less than 8mil trace/spaces without difficulty. I rarely have to patch/touchup anything afterwards and once you put the green foil on you need sandpaper to get the traces back off! (well, actually acetone works fast and easy, but you get my drift.) The replenishing supplies are not expensive (and they do a lot of boards). The paper used is specially designed to seperate in water and works the best. I wasted more money trying different inkjet paper than I spent on pulsars starter kit. The secret though is the green foil, it goes on over the toner once it is transfered to the pcb. When the toner traces are coated in green, those traces are practically indestructible and 100% etch resistant.

The laminator is optional, but I find it worth the small price. It's much easier than using an iron and hey, you get a handy paper laminator too.

The site has many tips about chemical etching too. I use the tip about putting the pcb and etchant into a zip-lock sandwich bag (double bag) and using a hobby rubber roller to squeeze the etchant over the board. This was good, but I also put the whole bag and all into a nice hot water bath and it's blazingly fast! The hot water heats the etchant and it works much faster. I can do a double sided board in about 5 mins flat!

Your will get good results the first time, but like anything it will take a few times to *really* get things tweaked. I wrecked a few boards because I left it in the water too long and the toner starts coming off then. I now time the soak for 1 minute only not 2 mins as suggested, this probably has to do with the hardness or softness of the water  so your results may differ too. Otherwise, follow the directions and you cant fail. Once tweaked, making pcbs will actually be fun for once.

I don't represent the company in any way btw, I'm just an evangelist because I hated doing pcbs before. I also still use pcb houses once I know my circuit works right. If only I could find a way to do through hole plating cheaply and easily I'd be all set.

C

Offline guru

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Re: Toner transfer and tqfp
« Reply #8 on: March 26, 2010, 10:46:17 AM »
FYI: I won't buy a home laser printer for pcbs, I find the home use laser printers output too little toner. the office depot 15'000 dollar copier produces much crispier and dense images! Home printers will work of course, but I see a difference in my pcbs with the office depot (or whatever) prints. This is especially true of copper fills, a home laster gets real thin there but the expensive printers produce dense copper fills.

I jus happened to by the worst printer for toner transfers...a Brother printer. Brothers use something unlike toner and it fuses too well to paper and is also cheaper. A good thing for 99.4% of users but not for us hobby pcb makers.

I instead just drive to office depot and get them to print it from my usb stick. It costs about 12 cents a print. I feel bad for them when I ask them to print on special paper, shiny side up and only give them 12cents! lol


C

 


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