Thing is, the laminator takes a major beating every time I do this. It will not last, and they are pretty expensive overall.

So I will try the experiment, and I'll let you know how it goes.

The iron (as in ironing board) method used to work well for me, but they cheapened up the irons to the point where it can't work due to temperature variations on the surface caused by thin metal. The goal is to distribute the temperature evenly over a wide area.

I apologize for hijacking the OP's thread. If we continue this I will move the relevant posts to a new thread.

 

I don't mind the hijacking, after all the title was "toner transfer" and this is very interesting stuff.

In response to The_RB I have to say I had never considered thermal expansion, although I have never seen any smudged tracks either. Google tells me that the thermal expansion of copper is 16.6um/m/K and GRP about 20 to 30um/m/K so taking a "worst" case of say heating by 100K the max expansion wold be 0.003m/m so for a 0.1m board the expansion would be 0.3mm so possibly a whole track width.

There are a couple of other things to consider, the paper will expand, although I can't find any figures for that; and presumably the toner doesn't start to transfer until it is soft so I guess a lot of the expansion has occurred before the toner starts to transfer.

<edit>
one final thought, from experience the paper seems to expand due to the pressure of ironing

 

Thing is, the laminator takes a major beating every time I do this. It will not last, and they are pretty expensive overall.
...

I bought a $25 laminator, with electronic temperature control. Opening it up showed a factory-set trimpot to set the temperature. I just turned that up.

Regarding mechanical issues it has reasonably soft silicone rollers, so it tolerates standard FR4 1.6mm thick PCB stock with no problems.

However I'm still interested in your experiments with a single time heat press.

I would suggest you try pre-heating the PCB stock first (close to final temp), then apply the toner paper then a final hotter press. In that way you could get most of the PCB thermal expansion done before any toner has a chance to touch it. The cool down might still be an issue but should be more rapid.

 

One of the things that a lot of websites seem to recommend is lots of pressure, burnishing with the tip of the iron etc. I have been thinking about this and started wondering if this is necessary or could even be detrimental.

What we want is to get the toner in close contact with the copper so that it sticks, we then remove the paper, layer by layer leaving the toner on the copper. I wonder if too much pressure could force the toner into the paper causing it come off the copper.

Knowing the melting temp. for toner may be helpful but there does not seem to be much info on this.

 

Hello,

The MSDS sheets of a black toner of the HP 4500 series tells us a softening point of 100 - 150 °C.
http://www.hp.com/hpinfo/globalciti...uctdata/Countries/us/lj_c4191a_us_eng_v13.pdf

More MSDS sheets from HP can be found here:
http://www.hp.com/hpinfo/globalcitizenship/environment/productdata/ljmsdsuseng.html

For Brother laser printers you can have a look here:
http://www.brothertoner.com/toner_list.asp

Bertus

 

Thanks Bertus, knowing the correct phrase to Google makes all the difference. I am using a Kyocera, toner melting point 140°C.

Looks like setting the iron to Wool/Silk, as I did and which gave better results, just happens to be correct for my toner - apparently the recommended ironing temperature for Wool is 148°C

 

...
What we want is to get the toner in close contact with the copper so that it sticks, we then remove the paper, layer by layer leaving the toner on the copper. I wonder if too much pressure could force the toner into the paper causing it come off the copper.
...

Gloss paper has a high clay content, and is very dense and not absorbent.

That's why people like to use the very thin gloss paper they use on junkmails, ie colour catalogues etc.

Personally I switched to "press'n'peel blue". It's a special product designed for the task, and not too expensive, if you buy a pack. It also adds an extra layer on top of the toner, so you get less (or no) track breaks.

 

As has been mentioned, wax paper has worked out pretty well for me overall. You just have to attach it to a sheet of paper before printing on it.

 

I use Argos paper its pretty good, I have two laminator's that are exactly the same except, one is broken. They are GBC one's and were expensive, But RB has given me an idea. If I can fix the broken one then I might try and alter the speed. The heat control on the one I have seems complex, no obvious pots. But speed control should just be a question of pwm of the roller motors.
I tried a cheap laminator but it didnt work well for me

 

Thanks, yes I've done that in the past but I find it hard to keep the tracks very narrow, perhaps I need a finer marker, if such a thing exists (currently using a Staedtler fine marker).

Sharpie sell an "Ultra Fine Point" marker which may be of use, I find Sharpies Fine markers to be far from fine when compared with the Staedtler ones.

Also Staedtler sell what they call "Super Fine" markers, these have an orange S on the lid instead of the M or F.

A quick search on amazon brings up these results if you have no luck finding them in your local stores:

http://www.amazon.co.uk/Staedtler-L...95409416&sr=8-3&keywords=super+fine+staedtler
http://www.amazon.co.uk/Sharpie-Ult...1395409392&sr=1-3&keywords=ultra+fine+sharpie

Hope this helps

 

If you are etching your own boards, try to leave as much copper on the board by using copper pour or floods. Not only will your etching solution last longer but also your board will take shorter time to etch.

I don't bother leaving a copper fill on my boards because I don't like the looks of it. Also the ferric chloride is cheap as chips with the amount of boards I make. The tin plating solution that I use (crystals dissolved in water - non electrolysis method) is also very expensive, so I don't like big copper fills.

 

One of the things that a lot of websites seem to recommend is lots of pressure, burnishing with the tip of the iron etc. I have been thinking about this and started wondering if this is necessary or could even be detrimental.

I have noticed this, applying too much pressure actually smudges the tracks, especially when using the tip of the iron. I haven't tried it yet, but I think a lower temperature may be better. Most people recommend the max setting and I think this is where I am going wrong.

I use glossy magazines for mine and I try to place the board into nearly boiling water to get the paper to come off. Sometimes when it works if literally floats off almost instantly leaving the transfer on the board perfect. A quick rub with an old toothbrush removed any stubborn paper and also reveals any areas where the toner hasn't adhered correctly. These can then be touched up with a Sharpie.