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Subject: Re: Problems with using Aerosol Photoresist
Date: Thu, 5 Dec 2002 17:11:46 +1100
X-Newsreader: Microsoft Outlook Express 5.00.2314.1300
Thanks Barry for the response.
I actually wrote an e-mail to Electrolube explaining my problems and I hope
you don't mind, but I also included your response to my newsgroup posting (I
deleted your last name). Please find their response attached....
Sorry for the difficulties that you have been having with the product. Due
to circumstances out of our control we had to change to the green
photoresist. When I do work with the photoresist I follow a revised set of
instructions that I devised, I know that you will never use the product
again but if you still have some left in the tin then you might like to
follow the instructions attached. Your comments have been noted and will be
forwarded to the relevant people.
Sorry once again
Guidelines for Use of PRP and FCC
Copper test panels (available from RS) - 6" x 4" Cu covered laminates.
Light Exposure Box
1. Clean copper panel using wire wool.
2. Rinse panel with SWA/deionised water and then dry with acetone
3. Coat with PRP (do not shake can) - spray evenly so the Cu is not visible
- do not drown the coating.
4. After application dry panel immediately in dark for 30 minutes
- do not bake the product (applied to old PRP product).
Water vapour needs to be present in the atmosphere for curing
5. Place panel (uncoated side up) in light exposure box and close lid
6. Time exposure (time device on box) for 6 minutes
7. Remove copper panel from box - a change in colour (dark green) and a
tracking pattern should be observed.
8. Next develop the panel using NaOH solution (7g/litre water). Although
Electrolube's PDN is recommended, the solution is not strong enough.
9. Submerge the panel in the NaOH solution and swirl the top of the
solution - do not be aggressive and do not touch the copper panel.
10. After 30s immersion, the panel is developed - remove from the solution
and rinse with deionised water. Finally, dry.
Etching Copper with FCC
1. Make a concentrated solution of FCC and submerge copper panel
2. Leave submerged for 10 minutes
3. Wash copper panel with water and rinse with acetone
(FCC is iron chloride solution, which releases HCl and dissolves copper)
Potential Issues -PRP
· Exposed in Daylight for too long before left in the dark
· Product out of date
· Do not shake can
· Copper panel is baked (no water present for curing)
· Lamp in UV Box is not working or wrong wavelength is used for
Note - PRP is not suitable for industrial large scale applications, and
where intricate details are required in the pattern
Sent: 03 December 2002 08:18
Subject: PRP Positive Photoresist
Below is the result of your feedback form. It was submitted by
Ross on Tuesday, December 3, 2002 at
phone: 613 95417809
textarea: I have recently purchased from Farnell Australia a bottle of
PRP200 Positive Photoresist and a bottle of PDN250ML Photoresist Developer.
Unfortunately, after following your instructions, I have not been able to
develop an image onto the blank copper PCB. The steps I take are as
1) The blank PCB is thoroughly cleaned and dried.
2) In darkness, the PCB is sprayed with the photoresist.
3) In darkness, I allow the PCB to dry for 20 minutes at 50 degrees C.
4) Expose the PCB using a UV light source, using a laser printed
transparency as a master. I've tried different UV light sources, and
varying the time lengths.
5) Develop in darkness as per the PDN250ML instructions (1 part developer, 4
After a few minutes, the developer always removes all the resist without
leaving any image what so ever.
It seems that I am not the only one having trouble using your product. I
have seen it noted on several websites that people are generally happy with
the old blue/purple formulation, but are unable to get the new green
formulation to work.
I recently posted on the newsgroup sci.electronics.design the following
On Sat, 30 Nov 2002 12:28:05 +1100, "Ross"
>Has anyone out there had any success in using the Electrolube PRP positive
>photoresist for making PCB's. I understand this product has changed
>recently from an easy to use blue chemical, to the current green
And here's the reply:
In a word NO!
In my experience, the new formulation is a disaster, and I took it
back to the supplier. Never had a problem with the older one, once I
got the process sorted out, but the new one was hopeless. The main
problem seemed to be inconsistent results with the same exposure time,
temp, developer strength. Maybe I didn't spend enough time getting the
process under control (Only 2 days of very frustrating messing about
!!) but anyway, it behoves the manufacturer to tell the users if they
have made some formulation change, and therefore what process changes
may or may not be required.
I'll never touch it again.
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