Electronics > Projects, Designs, and Technical Stuff

Toner Transfer

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jmelson:

--- Quote from: KL27x on January 14, 2019, 08:10:54 pm ---
--- Quote ---I have been trying several of the toner-transfer methods out there, but the transfer is very poor. I am etching with saltwater and current via a 6v/2a wallwart, but it eats away at the toner as well as the bare areas.

--- End quote ---
This sounds like undercutting. Different etchants have different levels of undercutting. Electroetching is perhaps "too fine" and gets into tight spaces, causing the toner to separate, early. This is also a problem with HCl and hydrogen peroxide etchant. The thicker/deeper you want to etch, the more you have to pay attention to this.

--- End quote ---
I use dry film resist, in a heated FeCl spray etcher.  When everything works right, the board is etched in about 1.5 minutes.  Exposing and developing the resist is the critical step, any dry film that is left in the areas that are supposed to be developed away will lead to slow etching and undercutting.

Jon

tautech:

--- Quote from: IdahoMan on January 14, 2019, 07:07:53 pm ---
I would like to try etching many items as well as PCBs (faceplates, blades, etc.), and other materials than just copper.

I have been trying several of the toner-transfer methods out there, but the transfer is very poor. I am etching with saltwater and current via a 6v/2a wallwart, but it eats away at the toner as well as the bare areas.

--- End quote ---
Toner porosity will be the issue and while a glossy transfer medium can help a higher DPI printer is needed to overcome porosity issues. Shorter etch times and/or heated etchant can help too.

KL27x:
The way I do toner transfer, there is no porosity issue. Power planes come out solid. If you get the toner hot enough to completely melt, it fuses the dots together. You just have to pre-etch the board so that the toner stays where it's supposed to. And if you want the cleanest most accurate etches, you cannot use hack etchant like HCl and peroxide.


--- Quote ---But, if you've ever tried dry film resist, you will probably never go back to toner transfer.
--- End quote ---
That might be true for the vast majority of people. But if you learn how, toner transfer is extremely reliable and probably a little bit easier.

tautech:

--- Quote from: KL27x on January 14, 2019, 11:54:46 pm ---The way I do toner transfer, there is no porosity issue. Power planes come out solid. If you get the toner hot enough to completely melt, it fuses the dots together.
--- End quote ---
Yes well that all depends on your printer, toner, dpi, transfer medium and transfer temp settings, but agreed that result is what we strive for.
Change any one thing like getting a new printer and all bets are off and back to the drawing board to rediscover a recipe that works well again.


--- Quote ---You just have to pre-etch the board so that the toner stays where it's supposed to.
--- End quote ---
Actually a pre-etch is not required if the gloss is first removed from the copper. 000 steel wool or 1000 grit wet and dry followed by a cleaning with water or IPA works fine too.
Of course contamination with skin oils from handling is to be avoided.

KL27x:

--- Quote ---Actually a pre-etch is not required if the gloss is first removed from the copper. 000 steel wool or 1000 grit wet and dry followed by a cleaning with water or IPA works fine too.
Of course contamination with skin oils from handling is to be avoided.
--- End quote ---
I'm afraid you and I are not on the same wavelength. This is why so many people are better off with UV. In the surface, toner transfer is simple. But there are some minor nuances to get consistent and accurate results. And the signal to noise ratio on the subject is very very low and expectations and techniques and results vary quite a bit. A lot of the information is old. And there are a lot of recent videos and webpages about it. Mostly with old information. Even 20 years ago, people were saying that a pre-etch is useful. And other people were saying that it is optional or not necessary.

IMO, pre-etch is essential if you want to completely liquify the toner. Cleaning the board is essential, period. And I use steel wool for that. The toner will have no trouble sticking to the copper if you just clean with steel wool or sandpaper.

The pre etch makes the surface porous, so that it sucks up the liquid toner instead of squishing it around. After cleaning the board, I dunk it in the etch tank for a few seconds and then rinse it off in a bucket of water. That's all a pre-etch is.

The predominant school of thought is to just barely/partially melt the toner. This is a very fine window with failure modes if too cold or too hot. If you pre etch, you can crank up the heat until the board bubbles and delaminates, and the transfer will still be fine.

This wasn't practical even 10 years ago.* The melted toner would suck into the paper and leave a mess of fibers on the board. Or the PnP would melt and distort. Today, this is the way to go, using Pulsar dextrin coated paper. Welcome to the 21st century.

I'm not saying I can make better boards than people who do not pre-etch or do not use Pulsar. I'm claiming that I can make a board once a year, any size, thickness, mass, down to 8 mil traces, and it will come out perfect on the first try, every time. No particular attention to detail or timing or muscle memory needed. It is foolproof. Just do the steps.

*unless you are one of those guys that stumbled upon the mythical legendary Photo Paper. The one that they changed the fomula of and/or discontinued by the time you posted about how great it is. :)

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