Trace widths for toner transfer etching


#1

I am working on a PCB for etching using toner transfer. My first attempts show the default trace dimensions (clearance 0.2 mm, track width 0.25 mm) do not transfer well - there are visible breaks in the traces, some of which barely transfer at all.

What dimensions (without excessive width) are likely to be more successful?


#2

How about creating a set of lines with different widths (e.g. increased in 0.1 mm steps) and different cleareances for testing?

From own experience, I can tell you that you should create patterns with horizontal and vertical lines for testing because of the inaccurate line width reproduction of some laser printers.


#3

Toner transfer is always a lottery.
These days, web-pcb suppliers are cheaper all the time, so I’m surprised anyone bothers with the toner transfer trials anymore,
Places like https://jlcpcb.com/ quote $2.00 starting for 2L, and shipping costs are not too onerous.
you get 2 ( or /4/6) layers, plated through, solder mask, overlay,


#4

It can be hard when one has the desire to create their own work with their own skills to consider emailing a file and a payment method.

However, at this point in time in regards to technology, I have to agree with you. I don’t think I can produce even a minimalist board for the price that the purple board vendor can provide one for.


#5

Thanks, folks. I’ll follow ikletti’s idea. Experimentation seems the way to go.

FTR: I will persevere with my toner transfer attempts simply because it interests me :yum:. I will get around to trying a commercial source some time but my experience here in Australia is that packages are still delivered by sailing ship (and not clippers either) and delivery costs come in any multiple you like of the value of the object. If anyone knows an Australian supplier I would be delighted to hear :hugs:.


#6

But even the Chinese fabs deliver quickly and inexpensively. Your Australian experience is obviously quite limited.


#7

When it comes to PCBs my Australian experience is non-existent. I have a bit of experience in purchasing from overseas suppliers and they can take a couple of weeks to get stuff to me. Mind you, I shouldn’t grizzle too much. It can take two weeks to get stuff across the Nullabor.:tired_face:


#8

I haven’t done toner transfer for many years but this:


might be worth trying.


#9

Yes, I often get free deliveries from China faster than paid deliveries from the east coast.


#10

The problem with the Kangaroo Express is they have a tenancy to get distracted en route.

:rofl:


#11

The Yahoo Group " Homebrew Printed Circuit Boards " may be a better source of advice.

Dale


#12

I didn’t had the need to order express from China so far, but via plane stuff should be over in WA in the same time stuff arrives in the sticks up north-east where I am. I know that some express things via plane make it from China to bush around Cairns in 4-5 days :wink:
Longest usually is Customs down in Sydney/Melbourne/Brisbane.

PS: seems also we now get to pay 10% GST for things from China, with the free-ride for things below $1000 being a thing of the past… was nice as long as it lasted. But with more and more going online, it’s no wonder the government coffers needed to follow the sourcing there…


#13

Pesonally I prefer etching by myself. Your are limited to 2 layers, and that’s ok for small circuits. It’s not as nice as professional way, but in 1 hour the job is done. It cost more however. But you can have trace of .2mm with .4mm between easily. Just use the chimical way and press it with a little warm pieces of wood. Nothing complicated! Just try worth it.


#14

I found the template I created for UV exposure tests a few years ago in my heap of files. Have fun!

Testmuster Platine V1_0.pdf (178.5 KB)


#15

Toner transfer can be tricky to get working well. Here are the things you need get right for best results:

use toner transfer paper. I particularly like Press’n’Peel Blue. People will say magazine paper works, and it does, but proper transfer paper is better, especially Press’n’Peel
Copper must be absolutely free of oxide, grease and dust. I use an abrasive rubber polisher I got from RS. Dust is an issue as it can stop the artwork making contact with the pcb.
Even heating
Sufficient temperature ( this is dependent on your printer toner - too cold and it wont stick, too hot and it will smear
even pressure
sufficient pressure

My final setup used a temperature controlled hotplate, and a vacuum pump with a silicone sheet to provide pressure. I got to the point where I could have a PCB in my hand in 30 mins. Great when you’re in the middle of a rapid prototyping cycle where you might want to try three or four variants in a day (which I have done). No chinese fab house can do that for you.
I got this process to the point where I could make double sided Kapton flex circuits using 5mil/5mil design rules (thats 0.13mm in metric).

To your specific issues I’d say the missing toner is likely due to not enough heat and uneven heat or pressure. Next most likely is bad copper prep - dust/oxide/grease.


#16

Thank you very much for this !!!