[SIZE=-1]Key issues with or without commercial transfer paper include keeping your fingers off the clean board and the transfer paper. What follows are tips and info that has allowed me to make very good SS, DS, and silkscreens using the toner transfer method.
Some people make a big deal out of cleaning the board. Just scrub till evenly clean and brite with a green scotch brite pad and Dawn dish soap. Lay it on the counter and put some elbow grease into it. Rinse with water.
Do not touch it again except with a paper towel to dry it.
Treat the transfer paper with care too. If you touch it prior to printing you run the risk of the toner falling off prior to or during transfer. If you touch the toner after printing the toner will fail to stick to the copper.
The next problem is to transfer the toner from the transfer paper to the board. The hands down easy way to do this is with a laminator. They provide even heat and pressure. If you do not have a laminator there are instructions on the PulsarProFx site on how to use a large wood dowel with a clothes iron to fake one. A clothes iron by itself can be difficult to use.
The Pulsar site also has instructions on how to determine what heat setting to use on a clothes iron.
The pulsar has a lot of good info even if you do not use their product.
Removing the paper after transfer. If you use a commercial paper a minute of two in a warm water bath and it falls off. With gloss high clay content paper a few minutes of soaking in hot water should do it. Boiling ?
It costs a few dollars to get into the commercial transfer papers but the cost per square inch is low. They make the process easier to get right and seem to provide finer detail then can be hand without them. I can run 2 lines between .1" pitch IC pads without making the pads smaller. Have done 3 in tests but have never found the need to do so on an actual board. I am using .01" traces without problems.
[/SIZE][SIZE=-1]The commerical transfer papers from
https://www.PulsarProFx.com can be found at Mouser [/SIZE]
5165-TTS10. Ten [SIZE=-1]8.5x11in sheets are $15. They also offer a foil that can be laminated on top of the foner to further seal pin holes that are in the toner for about $10.
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The press and peel from
https://www.techniks.com/ run $33 for 20 8.5x11in sheets. I am not as familiar with their products.
Some things to keep in mind.
With the commercial transfer products the laser printer you use is often the limiting factor. You transfer is as only as good as the toner pattern the printer makes.
Most printers are better at alignment across the page then they are down the page. Position the artwork across rather then down the page.
The toner is liquified twice. Once when fused to the paper by the printer and again when transferred to the copper. To get dense toner the printer is set to its darkest setting. This much toner can creep/flow a bit when liquid. This is not a problem with most boards but it is a source of error in the process. If you iron the crap out of it or run it through the laminator too many times you can make it worse.
[/SIZE][SIZE=-1]Not 100% sure on this one. [/SIZE][SIZE=-1]Some printers can only deliver so much toner to a given area of the paper. If you do a fill you are more apt to have problems with traces. But if you are having problems when using a pour try turing the pour off.
Again keep it clean. Wash your hands often to remove the oil from you fingrer tips. I go a step further. When I start on a new sheet of transfer paper I attach a sheet of normal printer paper to the active/printing side with a few tabs of blue painters tape (3M). It is low tack and comes off easier then most tapes. Then I can layout and cut the needed bits without danger of touching. When a tab is cut away add a new one.
Eagle
I have found that if you extend the dimension lines so as to create a tic-tac-toe looking design with the board in the middle it makes aligning the transfer paper to the carrier sheet (normal paper with the board location printed on it) easier. Simple but helpful
When printing a pattern for the top side of the board (DS or SS surfaced mount) check the Mirror box in addition to the Black and Solid which should be used all the time.
ERC and DRC are your friends. Note that DRC
design rule check does more then check the board, it has values that effect the layout itself.
The DRC restring value determines the size of pads on vias as a percentage of the drill size. The default value is 25%. I bump them up to 35% and even 45% if possible to make soldering easier and the pads better able to stand up to rework. Some parts have the pins close together and will limit how large a value you can use for restring.
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