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General => General Technical Chat => Topic started by: RayJones on August 15, 2010, 12:43:20 am

Title: Photosensitive PCB supplies (AUSTRALIA)
Post by: RayJones on August 15, 2010, 12:43:20 am
I'm finding a desire of late to restart doing what I used to do a hell a lot of back in the 80's (Am I really that old?)

That is making one off PCBs.

In the past it was relatively easy to obtain Riston coated boards, and 3M made a nice UV sensitive negative film. Some alkaline solutions and a UV box was all you needed, along with the good ol ferric chloride.

Is this stuff still around?
What are people using these days if not?
Is there a good supplier in *Australia*?

The main reason I lost interest in the past was the hole drilling drove me insane, but these days SMD technology is the go, and guess what minimal holes compared to back then ;D
Title: Re: Photosensitive PCB supplies (AUSTRALIA)
Post by: DJPhil on August 15, 2010, 05:34:44 am
Not much has changed really. The primary alternatives are toner transfer and milling, each with their own ups and downs. There is an alternative to FeCl (http://members.optusnet.com.au/eseychell/PCB/etching_CuCl/index.html) that I use to keep things a bit cheaper, but it takes more work and is probably not worth the trouble unless you're broke.

It looks like farnell has a few photoresist boards (http://au.farnell.com/jsp/search/browse.jsp?N=1003223+511&No=0&getResults=true&appliedparametrics=true&locale=en_AU&catalogId=&prevNValues=1003223&filtersHidden=false&appliedHidden=false&originalQueryURL=%2Fjsp%2Fsearch%2Fbrowse.jsp%3FN%3D1003223%26No%3D0%26getResults%3Dtrue%26appliedparametrics%3Dtrue%26locale%3Den_AU%26catalogId%3D%26prevNValues%3D1003223), but the prices seem high to me. I've never shopped photoresist stuff for price. I'm sure the local folks will know where to send you.

I checked my favorite PCB supplier (abcfab on ebay, based in the US) and it isn't immediately apparent whether they do photoresist or international shipping, though I remember they once did ship internationally. If you decide to ask, the fellow to contact would be Bill and you can reach him through ebay or via email at abcfab yahoo. They've got all sorts of different materials, colors, thickness, copper weights, etc. for a reasonable price, which is something I never thought I'd see! He's been a help to the hobbyists here, so I thought I'd plug him a bit.  ;)

Hope that helps some :)
Title: Re: Photosensitive PCB supplies (AUSTRALIA)
Post by: Simon on August 15, 2010, 07:24:58 am
one twist now is you can make your own LED UV boxes in old scanners but it can be like 10 hours work to build a small one
Title: Re: Photosensitive PCB supplies (AUSTRALIA)
Post by: tycz on August 15, 2010, 07:36:57 am
World Wide Electronics (http://members.iinet.net.au/~worcom/) in Perth sell Kinsten brand Presensitised PCB. I've been using the stuff for years without trouble.

Tips:

For etching I use Ferric Chloride and two plastic trays. Fill one tray 1/3rd full of hot water, and the other tray with enough Ferric Chloride to cover the PCB. Put Blutack on the corners of the PCB if it's double sided. Put the etchant tray inside the hot water tray then rock it back and forth for 10 minutes or so.

Paper phenolic is my favourite material for single sided boards, it's much easier to cut and drill than fiberglass.
Title: Re: Photosensitive PCB supplies (AUSTRALIA)
Post by: RayJones on August 15, 2010, 07:53:47 am
tycz,

Now that's what I'm talking about, a reasonable price for the coated boards.  :)

Looks like a damn good supplier of bits, shame they are over in Perth, would be worth a visit.

Roger on all the tips.
I was making double sided s100 boards in the past, and registration of top to bottom is crucial on that sort of size.
As for clamping, the best bet is two sheets of glass either side of the DS sandwich, clamped with bulldog clips.
You can then easily flip over for the opposite side exposure.

Best paper for direct exposure back in the 80's was teleprinter paper - real thin, used along with a carbon sheet and a dot matrix printer very good results could be had.
This was still via a negative acting 3M scotchcal product.

Hmmm the old plotter / drafting mylar. Is that any good in an inkjet.....

I prefer the FR4 fibreglass, it is simply just more robust and I really prefer the appearance, all personal taste of course  ;D
Title: Re: Photosensitive PCB supplies (AUSTRALIA)
Post by: Simon on August 15, 2010, 08:05:07 am
these days you can get inkjet film and it is great for PCB's, I tried tracing paper and was not impressed with the results but the film is great, it does not come cheap though
Title: Re: Photosensitive PCB supplies (AUSTRALIA)
Post by: mikeselectricstuff on August 15, 2010, 08:46:04 am
For lots of tips on making good homebrew PCBs check out this article on my site (http://www.electricstuff.co.uk/pcbs.html).
For exposure, insect killer tubes are the right type - probably cheaper than UV LEDs.
Best artwork I've found is laser print on thick tracing paper. Drafting film crinkles under the fusing temperature, and acetates don't hold the toner well.
The number 1 tip is don't use sodium hydroxide developer. Silicate based ones are WAY better as the margin between "develop" and "strip" "is huge - concentration and temperature are much less critical than with sodium hydroxide, and you can make it really strong to develop in a few seconds.   
Title: Re: Photosensitive PCB supplies (AUSTRALIA)
Post by: McPete on August 15, 2010, 11:19:18 am
World Wide Electronics (http://members.iinet.net.au/~worcom/) in Perth sell Kinsten brand Presensitised PCB. I've been using the stuff for years without trouble.

We use the single-sided Kinsten boards at work for our designs- Top-knotch stuff. I don't think we buy through WWE, but they look good (aside from that website...). I'll circulate that one amongst my colleagues.