Etching PCB:s

Loial

Member
2004-11-21 10:06 pm
Gävle
How do you make/etch your PCB:s?
I would like to know the best method to make a quite fine pitched PCB for SMD IC:s, qould ordinary plastic film/developing/etching do the job?

OR, does anyone know where you can buy cheap prototype PCB:s? ( by cheap i mean maybe up to 20-30$ a piece )
 
I print the file onto mylar film, then expose the boards under a darkroom negative viewer for 7 minutes, develop in dilute sodium hydroxide solution, wash in running water, etch with a combination of hydrogen peroxide and hydrochloric acid -- for the H2O2 I use the inexpensive pharmaceutical brand which is $0.39/qt -- straight, no dilution and for the HCl I use muriatic acid from the hardware store. just a few ml's of HCl "promote" the reaction.

I can get a 10 mil trace thickness pretty consistently. I also find that "pouring" a ground or power plane causes the etching process to go much faster as there isn't a lot of copper to remove.
 
Loial said:
How do you make/etch your PCB:s?
I would like to know the best method to make a quite fine pitched PCB for SMD IC:s, qould ordinary plastic film/developing/etching do the job?

OR, does anyone know where you can buy cheap prototype PCB:s? ( by cheap i mean maybe up to 20-30$ a piece )

I used to use this process, with boards and chemicals supplied by these guys:

http://www.megauk.com/cgi-bin/mega/lp.pl?page=http://www.megauk.com/producing_a_pcb.php

For denser boards, www.olimex.com do 160mm x 100mm double-sided with 0.2mm track and gap, solder resist and silkscreen for $33.
 

rnrss

Member
2005-07-20 7:41 pm
na
Loial said:
How do you make/etch your PCB:s?
I would like to know the best method to make a quite fine pitched PCB for SMD IC:s, qould ordinary plastic film/developing/etching do the job?

OR, does anyone know where you can buy cheap prototype PCB:s? ( by cheap i mean maybe up to 20-30$ a piece )

you will have a difficult time if you want to get traces less than .010 if you do not have a clean room etc

I just use amonium persufate water and hydrogen peroxide
 

Loial

Member
2004-11-21 10:06 pm
Gävle
Now I've tried to use the "toner transfer" method - and it works perfect! It looks like I found the correct paper at once =)
now this is a method I'm gonna stick to - print, press, clean, etch. It cant be easier than this...

My only problem at the moment, is that I cant really find a good layout program, I tried expressPCB, but the traces dont really end up that good with screendumping and printing :-/
Eagle PCB drove me crazy...
Any program that works kind of like ExpressPCB - but without the print fuzz?

EDIT

I dont really need 0.01 traces, i can do with 0.02 or so. Anyway this method produced sharper traces than the ordinary plastic film/developing method. And i DONT have a cleanroom, neither a clean room ;-)
 
Loial said:

My only problem at the moment, is that I cant really find a good layout program, I tried expressPCB, but the traces dont really end up that good with screendumping and printing :-/
Eagle PCB drove me crazy...
Any program that works kind of like ExpressPCB - but without the print fuzz?

Umm, I'm guessing you're looking for a free PCB software?

I don't know any free ones that won't drive you nuts. I have tested lots.
:smash:

I've been using Proteus for a while and it's fine, although not perfect in my opinion. But it's not free. The demo versions don't allow you to save your work, so... it's up to you if you're interested.

If you want something Open Source, you might like to give Kicad a try. http://www.lis.inpg.fr/realise_au_lis/kicad/
Guaranteed to drive you crazy on a regular basis, but not that bad, has interesting features and is totally open.
 

cbm5

Member
2005-03-14 12:47 am
Arkansas
Absolute cheapest prototyping house I've ever used is Olimex, based out of Bulgaria.

$33 for a double-sided, through-plated, solder-masked, silkscreened 6"x4" board.

The kicker? They'll cut up the board for free, and even combine multiple different board files into one board! You try to get that with any other PCB house, and you'll be paying full price for each board and no panelization, and $5 for each cut, etc. If your boards are small so you can get 3 or more in one panel, there isn't any cheaper option, not even home etching.

Doing business with Bulgaria is a little painful to set up at first, but I find them to be trustworthy.
 
Loial: To get a clear print out from ExpressPCB I use Nedip. It's a virtual printer that dumps a 600DPI image when you print through it.

So this way you can use the print function of ExpressPCB and get really good print out. The only other piece of software required is something like Paint Shop Pro to adjust the print out to the printer and sometimes retouch the images a bit.

Hope this helps!
Sébastien