PCB Etching Nightmare

B

Bennet Williams

Guest
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
 
what kind of pan did you use ... glass or pyrex I hope?

Tom Woodrow

Bennet Williams wrote:
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
Click to expand...
 
No. It was Tupperware. I figured that was OK since most etching tanks
use plastic. Even the $150 model uses polyethylene (plastic).

BRW


On Wed, 13 Aug 2003 02:01:21 GMT, Tom Woodrow <tomwoodrow@comcast.net>
wrote:

what kind of pan did you use ... glass or pyrex I hope?

Tom Woodrow
Click to expand...
 
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.


"Bennet Williams" <brwilliams@adelphia.net> wrote in message
news:9p2jjv087johiam71j48vqto78l0ve0lq8@4ax.com...
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
Click to expand...
 
Bennet Williams <brwilliams@adelphia.net> wrote in message news:<9p2jjv087johiam71j48vqto78l0ve0lq8@4ax.com>...
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
Click to expand...

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
 
Bennet Williams wrote:

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
Click to expand...
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
--
Drop 'pants' to reply by email
 
I question whether the exposure was long enough.
Frank P

Bennet Williams wrote:

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

BRW

On Wed, 13 Aug 2003 13:13:18 -0400, Boris Mohar <borism@sympatico.ca>
wrote:

On Wed, 13 Aug 2003 07:30:39 -0400, Bennet Williams
brwilliams@adelphia.net> wrote:

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

BRW

Was the etchant fresh or previously used?
Click to expand...
 
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

On Wed, 13 Aug 2003 16:22:52 GMT, "CWatters"
<colin.watters@pandora.be> wrote:

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.


"Bennet Williams" <brwilliams@adelphia.net> wrote in message
news:9p2jjv087johiam71j48vqto78l0ve0lq8@4ax.com...
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
Click to expand...
 
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

On 13 Aug 2003 10:09:17 -0700, chemelec@hotmail.com (Gary Lecomte)
wrote:

Bennet Williams <brwilliams@adelphia.net> wrote in message news:<9p2jjv087johiam71j48vqto78l0ve0lq8@4ax.com>...
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


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
Click to expand...
 
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
Click to expand...
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
http://www.pclogic.biz
http://members.aol.com/atpclogic/index.html
 
Bennet Williams <brwilliams@adelphia.net> wrote in message news:<9p2jjv087johiam71j48vqto78l0ve0lq8@4ax.com>...
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
Click to expand...
After exposure, did you rinse off the un-exposed resist with the proper solvent?

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

BRW

On Wed, 13 Aug 2003 17:56:15 -0700, "Richard Crowley"
<rcrowley7@xprt.net> wrote:

"Bennet Williams" wrote ...
...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.

Several have FREE layout software availble for download.
For example: http://www.pcb123.com/
Click to expand...
 
"Bennet Williams" wrote ...
Thanks Richard. I'll look into them. It looks like a top-notch
organization. Have you used them?
Click to expand...
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.
 
Thanks Richard. I'll look into them. It looks like a top-notch
organization. Have you used them?

BRW
Click to expand...
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
http://www.pclogic.biz
http://members.aol.com/atpclogic/index.html
 
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:

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

On Wed, 13 Aug 2003 16:22:52 GMT, "CWatters"
colin.watters@pandora.be> wrote:

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.


"Bennet Williams" <brwilliams@adelphia.net> wrote in message
news:9p2jjv087johiam71j48vqto78l0ve0lq8@4ax.com...
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
Click to expand...
 
This how to do it.

http://www.computronics.com.au/kinsten/

Ross Herbert wrote:

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:

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

On Wed, 13 Aug 2003 16:22:52 GMT, "CWatters"
colin.watters@pandora.be> wrote:

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.


"Bennet Williams" <brwilliams@adelphia.net> wrote in message
news:9p2jjv087johiam71j48vqto78l0ve0lq8@4ax.com...
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
Click to expand...
 
On Thu, 14 Aug 2003 13:41:45 GMT, Ross Herbert <rherber1@bigpond.net.au> wrote:

This how to do it.

http://www.computronics.com.au/kinsten/

but did you carry out the DP50 stage?
Click to expand...
http://www.computronics.com.au/kinsten/dp/

Geo
 
Geo,

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

Ross Herbert.

Geo wrote:
On Thu, 14 Aug 2003 13:41:45 GMT, Ross Herbert <rherber1@bigpond.net.au> wrote:

This how to do it.

http://www.computronics.com.au/kinsten/

but did you carry out the DP50 stage?
http://www.computronics.com.au/kinsten/dp/

Geo
Click to expand...
 
What exposure lamps did you use? It seems like they didn't expose
long enough to get thru the resist. Try repositioning your layout and
re-exposing again. What type of artwork did you use?

I looked at the replies and your answers, and I think you said the
board was 5" away from your light source.
Did you use a piece of glass to hold the layout against the board?
If you did, and you used just any old piece, it may have had lead in
it. This will impede the uv which exposes the resist. Get a piece of
6mm no lead content plate glass from your local glass house and try
again.

I use F15T8BL uv lamps or the latest eqv in cheap fluroscent holders
I buy from Home Depot. I remove the plastic cover, replace their lamp.
I built a box big enough to hold 4 holders, with 6" high sides and
rabbitted a groove on the top inside edge, for the glass to sit in.
With the holders 3" apart, I can expose a 12" x 12" board without
problems. Since my lamps are 15 years old, I expose 5 minutes and can
easily do .01" traces. I have used MG boards and resist for years,
but now they don't supply resist. I coat my own boards with positive
resist and use MG418 developer mixed .1part dev, to 6 parts water.
This is my "stock" solution. When I need developer, I mix 1 part stock
to 1 part water. It can be cold and put it in a glass dish. I watch
the resist change color, and remove the board when it is quite dark. I
wash it off and put it back into the tray to finish developing, then
wash and etch.
The developer can be reused until it get too dark to see the board.
Keep the used developer in a different bottle.

If you need any assistance please contact me and I will try to help.

Bill Jenkins
On Tue, 12 Aug 2003 20:57:27 -0400, Bennet Williams
<brwilliams@adelphia.net> wrote:

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
Click to expand...
 
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