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pra3718 19th December 2009 09:05 AM

etching gainclone pcb
Till today, I was using protoboard/veroboard and point-to-point wiring. Now I am confident that I can make my circuit layout. Yesterday, I went to my electronic part supplier for tda7294 (which I build successfully with my layout) He offer me for blank PCB and eatching powder and said do art-work by permanent marker pen on pcb. Put the pcb in PVC pot add eatching powder and warm water.

I google with "etching pcb" and got lot-off stuff. Laser printing toner transfer method is popular.

First, I have to make art-work. I use windows paint-brush. Major problem is alignment of IC's pin & coponents. I found LM3886tf & TDA7294's pin alignment is different.

1) How to calculate distance between pins ?
2) How to draw on paint-brush. The distance looks on Computer monitor does not print the same distance.
3) I experienced 4700uf 25v caps are different sizes with different brands.

How the experienced members manage these problems ?

Magura 19th December 2009 09:09 AM

Download Eagle light, and take it from there.

Magura :)

XL5 19th December 2009 02:19 PM

CAD software
I agree with Magura. Try a free electronic CAD software.
Look here;
Printed Circuit Board Computer Aided Design and Manufacturing

pra3718 19th December 2009 02:53 PM

Thank you, Learning Eagle light

gootee 19th December 2009 03:00 PM

You could try this way:

Easy PCB (Printed Circuit Board) Fabrication, Using Laser Printer Toner Transfer, with a Household Clothes Iron and Glossy Inkjet Photo Paper

Basically, if you can print the pattern with a laser printer, onto glossy inkjet photo paper, you can use a hot clothes iron and transfer the pattern to the copper. The laser printer's toner is mostly plastic, and copper etchants cannot eat plastic. And voila!

I've done it hundreds of times. You can go from a computer-based design to a finshed board in less than an hour. But you have to get the details done correctly. So read the link.

There's also a good recipe for etchant, there, that's better than any of the powder types I've used, and is very cheap and made from two very-widely-available chemicals.



chingyg 21st December 2009 03:40 PM

yes for the enchant use a mix of HCl and H2O2, I don't care much about the ratio through, go with your feeling, 1Hcl to 0.3 30% H2o2 seems quite good.

Mooly 21st December 2009 04:31 PM

You can make excellent PCB's using an inkjet printer and special transparency to print on.

Mega-UK - Artwork Aids look near bottom of page... Jetstar film
Mega-UK - Producing a PCB

And for PCB design I find Diptrace excellent.
DipTrace - Professional Schematic & PCB Design Software

For a simple design you may just want to draw by hand and use transfers for pads etc.

jaycee 21st December 2009 04:46 PM

Gootee's toner transfer method works very very well, but you have to find a good quality paper to use for this. Most cheap "Photo" paper just has a plastic like cover that will come away with the heat of the iron.

The stuff I use is Kodak Ultima 270 g/m2 paper. This has an ultra glossy finish like "real" photographic paper (the stuff you used to get 35mm prints on) and allows the toner to peel clean away under heat. The only thing you need to do is use a sheet of plain paper between it and the iron, or the iron sticks.

I just use regular old ferric chloride etchant as it is easy to get. I store it in an old 2L juice container (I have no young children who might drink it!) and use it in a Tupperware tray that is inside a washing up bowl filled with hot water.

tomchr 21st December 2009 07:09 PM

I used to go the photoresist - film route for etching PCBs. But this toner transfer method sounds pretty attractive.

Does anyone have a good suggestion for a paper that will print and transfer without pinholes? The list of papers on Gootee's site hasn't been updated in a while and these office supply stores and paper manufacturers have a way of selling old wine on new bottles (eh... "rebrand") their papers every 20 minutes.



head_spaz 22nd December 2009 06:05 AM

For more information on the toner transfer pcb etching method, check out PulsarProFX.
They discovered the toner pcb process, and offer free tips, and sell some very useful supplies that really help to improve the process.
To eliminate pinholes, try using their Green Toner Foil. It is a foil-like sheet (mylar?) with a heavy pigmentation layered onto one side. After you transfer the toner to your pcb, just iron the pigmented foil over your toner to "seal up any open pores." Pretty slick process... very fast and simple to do... and it works like a charm. Turns a tedious task into a no-brainer that works perfect every time.
And if you'd like to make your boards more "professional" looking, get some white toner foil as well so you can use toner to make your silkscreen, and then iron over it using the white pigmented foil to impregnate color into your toner. I use this same method to label my front panels and stompbox enclosures. They lots of custom foil colors to choose from, even flourescents and metallics.
These guys also offer DryTransfer Decal Kits too. Very nice product... tho a bit pricey.
The toner foils cost about 9 bux each... but they last forever! Worth every penny too!

Check out their shockwave flash tutorials in the Decal Pro section of their site while you're there... because it's a very similar process, but more complex.

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