DIY PCB Manufacture: Photoresist or Toner Transfer?

Question

So here's what happening: I have my board layout ready to go on eagle, and am looking for a good way to produce this board at home, of a quantity of about 2 or 3, so not large scale at all. All the components are through-hole and the layout is single sided. For those curious the layout looks like this (the lines are from the a bad render as I just took a screenshot of it from paint):

Looking at DIY PCB manufacture all round the world wide web I have arrived at two most effective methods (from what I know): 1. Using a pre-made photoresist board to etch traces and 2. directly transferring ink from photo paper on to the copper (both using Ferric Chloride to route traces).

Since I have zero experience with this could someone please share some knowledge as to: for my application (low scale DIY PCB manufacture), which method would be the better choice and proved to be the most effective?

And for those with some experience in making your own PCB's at home, any advice or tips to share about this with a completely inexperienced guy like me? Any layout re-design required?

Really appreciate it.

Answer 1

Photoresist

Photoresist will give you the best results, and once you have the knowhow, it's easy and fast to make further PCBs. But it's a complex way for DIY:

As UV light source, the sun or an ordinary light bulb might work somehow, but a source specialized for UV and exposure is definitely better. (For DIY: get an old, thick (!) scanner and a face tanner and build your own exposure unit - This is identical to small and cheap semi-professional units, but can cost up to 90% less)

You need to produce a mask where black areas are as light-tight as possible, while other areas are as transparent as possible. The higher the contrast, the better.
To my experience, laser printer can produce a quite dark black on standard paper, but when the paper is more transparent, the black becomes lighter, too. There are sprays to be applied to a printout promising to increase the density (darkness), but this doesn't work for all toners. And there are other sprays making the paper more transparent, like oil does.

Next, you need to develop and etch your exposed PCBs.

In general, you need some test series to find out if your mask and UV light source are suitable, and what's the best exposure and developing time. This costs some PCBs or at least cans of photoresist and lots of time.

Long story short: This method is very expensive and time consuming when doing it just once.

Toner transfer

Also for this method, you need several trials, but as you get a good "preview" on the PCB before etching, you can just remove the toner with some solvents and try again. However, be prepared to produce more PCBs than you need, because pieces of the toner may separate from the PCB during etching.

Beneath the right technique of ironing (time, pressure), the paper is the most critical part. More glossy papers like those from magazines will not suck up the toner and leave more on the surface (better for the transfer), but the toner may also form a thinner film on them (not so good). And glossy papers don't soak as easily in water, so it's harder to peel them off without damaging the mask on the PCB. Some papers may contain some wax, oil or similar substances, which may also be transferred to the PCB. Clean the PCB gently with some dish liquid after transfer. (And also: clean it before the transfer with some good solvents like benzine or acetone.)

As edges are usually not that sharp and precise when using toner transfer, this method is not very suitable for PCBs with SMD components. You need a large clearance (space between tracks) and high track widths. The bigger, the better. But if you're making PCBs very rarely and don't need too much precision, toner transfer is a good alternative.

For your board, I would increase the width by a factor of 2 or more. You can still use thinner tracks where needed, just inspect them more carefully after the transfer. Also, you are using thermals (slits around holes in the copper plane, making soldering easy). For toner transfer, I would not use them, as they are too small to come out nicely on the PCB.

A paint pen (which applies thick pain, not just ink) is fine to correct errors or to fill large areas. (It seems many printers use less toner for filled areas than for lines). A needle and / or a scalpel can be used to scratch away an excess of paint.

Answer 2

There is also a third possibility: freehand drawing. If I look at your design it should be easy to draw freehand.

• print your design on paper
• fix it on the bare PCB with some tape
• drill all holes
• draw the traces freehand
• etch
• clean
• tin all traces (if you want to)

This might sound a bit archaic, but worked for me for a mildly complex dual layer hifi PCB based on the LM4780 (see https://github.com/mru00/amp/blob/master/doc/P1090084.JPG for a photo)

I used a common fine permanent marker, but can't recall the exact type (probably an Edding, http://www.edding.com/professional-marking/)

Of course, the result doesn't look as technical, and needs a little PCB redesign (no common ground plane), but allows you to express artistic freedom! It certainly will make your heart design something unique.

I wasted lots of hours trying to get the toner transfer working properly. For a one-shot (or 2, 3) PCBs this might be a good alternative.

Answer 3

Toner Transfer method is more preferred over photoresist as you need to expose the layout with UV light, which increases the cost astronomically; For 3-4 Prototype boards.

I have successfully etched prototype boards with very fine traces using Toner transfer, however you need a high quality laser printer with superior transfer media. Set it to darkest and maximum DPI print.

There's a hack if your printer has cartridge issues, then you can take a fine point permanent marker and draw the traces which weren't printed correctly.

I would also recommend that you have more clearance between the tracks and track width to be more, because you are doing it for the first time. Etching a board at home will test your patience and will take a lot of tries to get it correct. But Don't give up, keep trying.

Answer 4

Thermal transfer is something that will get the job done in your case, and you can do it at home using an iron and some additional ingredients. Photoresist requires a lot more work, but it's much better for PCB layouts using very small SMD. When you apply heat and pressure processing your board (iron or hot rollers), the ink tends to get heated up and spill around very easily (which is impossible to notice in spacier designs, proves extremely challenging with small route-to-route distances). To sum it up: - if you keep it simple, go with toner transfer - if you want your board a bit more complicated, go with UV

Answer 5

I would go with toner transfer, because you need expensive chemicals (does not last for long time), practice and UV lamp to do photo method.
Not all printers are good for toner transfer, I had issues with Brother toner, therefore I suggest you to make first a test. Then you need to learn to use iron as well, right temperature (cotton), apply pressure and move the iron up/down, lastly use the tip of the iron to apply even more pressure. when you peel the foil, all toner has to remain on board, if not do it again, I did ruin 3 foils for the first time.

Answer 6

If you have it in eagle format ... there are literally thousands of places that will have your boards to you, with plated through and holes drilled, solder mask, printing graphics and tested ... in 24 hour turn around time. making your own boards is simply not worth it. Have done it every way possible. trust me this is simpler. email or upload the eagle files, visa or MC, wait a day.