PCB Etching Nightmare

I have tried my first positive photo resist etch. The light exposure / developing step went great. All the exposed parts of the PCB looked like copper and all the unexposed parts looked like photo resist. So far, so good. After rinsing and drying, I put my board in a tank of Radio Shack's best etching solution. Unfortunately, I don't have a good etching tank, just a pan. After stirring for 30 minutes, barely any of the copper was etched. After leaving it overnight, still only

1/2 of the copper is etched and some of my traces are starting to erode - aargh! I used to etch standard PCBs all the time with Radio Shack etchant with no problem (about 30 minutes etch time). Is there something special about photo resist PCBs that standard etchant won't work? Am I doing something wrong? Please help.

BRW

Reply to
Bennet Williams
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what kind of pan did you use ... glass or pyrex I hope?

Tom Woodrow

Bennet Williams wrote:

Reply to
Tom Woodrow

No. It was Tupperware. I figured that was OK since most etching tanks use plastic. Even the $150 model uses polyethylene (plastic).

BRW

Reply to
Bennet Williams

It's been years since I did this but....After exposing don't you have to remove any unexposed resist using a special solution? You mentioned rinsing but what with? Perhaps it's water but I can't remember.

Reply to
CWatters

Did you heat the Ferric Chloride?

It Helps a lot if its at a temperature of 100 F to 120 F or even a little more.

Take care.....Gary

Reply to
Gary Lecomte

Try some agitation during the etch. Orienting it either vertically or face-down in the etchant speeds things up. Laying it flat with copper-up will take forever.

You say you stirred for 30 minutes. Hmmm. Maybe you need new etchant. The bottle you bought from Radio Shack may have been from 1972.

Blake

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Reply to
Blake

Reply to
Frank Pickens

It was unused, but it may have been old. The bottle was very dusty.

BRW

Reply to
Bennet Williams

No. You don't remove the unexposed resist. The resist is what creates your circuit in the etching tank. You just rinse the board in water.

BRW

Reply to
Bennet Williams

No. But I've decided to break down and buy a $40 etch tank with a heater and bubbler. I am also going to try a higher quality board (if price is any indication) - M.G. Chemicals 600 series. It costs $6.50 for a 4" x 6" board vs. the $2.50 for the board I was using. I figure if I throw enough money at this problem, it will go away. I'll probably end up spending so much that I could get 10 boards done at professional PCB house. The problem is, I don't have the PCB layout software that they need.

BRW

Reply to
Bennet Williams

There is an abundance of low cost software that can output files used by most pcb houses. What house are you talking to? What software do they need?

Regards, Brad PC Logic

Schematic entry and PCB design software

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Reply to
AtPCLogic

After exposure, did you rinse off the un-exposed resist with the proper solvent?

Harry C.

Reply to
Harry Conover

Thanks Richard. I'll look into them. It looks like a top-notch organization. Have you used them?

BRW

Reply to
Bennet Williams

Not yet. But their customer list reads like "Who's Who" of blue-chip technology companies. I will certainly use them for my next project.

Reply to
Richard Crowley

One word of caution. Most of the free software from a pcb house will not produce industry standard files. You will have to go to them for additional copies and so on. Think razor blades here. The entry price is very low, but they get you on every board they make for you. Brad PC Logic

Schematic entry and PCB design software

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Reply to
AtPCLogic
3 Steps to make PCB;

1.Expose Riston board for approx 90 sec in light box (depends on tubes)

2.Develop pcb to remove unexposed Riston coating 3.Etch in Ammonium Persulphate or Ferric Chloride

Etching in a heated bubble tank will usually take only minutes depending on freshness of etchant and amount of copper to be removed.

Ross Herbert

Bennet Williams wrote:

Reply to
Ross Herbert

This how to do it.

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3 Steps to make PCB;

Reply to
Ross Herbert

but did you carry out the DP50 stage?

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Geo

Reply to
Geo

Geo,

If you are referring to me, yes, I did do the DP50 stage as per instructions

Ross Herbert.

Geo wrote:

Reply to
Ross Herbert

It is a nice site. I'd like it better if it also included information on environmentally responsible ways to dispose of the used chemicals and maybe also sold stuff to facilitate doing so.

Allan Adler snipped-for-privacy@zurich.ai.mit.edu

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Reply to
Allan Adler

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