Photo-etching..

[Adrian Brentnall]

HI Folks

Bit of a long shot - but I know there's folks here who have experience of photo-etching in the context of PCB manufacture...

I'm looking to use a photo-etching process to produce stencils which are then used for glass etching, like a tiny screen-print process...

An exhaustive search of the net suggested that only one company sells this kit - it's called 'Dura-Film'. Process is: - create positive image on transparency film, use pos image to uv-expose the Dura-Film stencil, then develop the stencil, which then 'loses' the unexposed areas and can be used to screen-print the etching cream onto the glass.

Only slight fly in the ointment is that the company is in the USA, and they're rather over-enthusiastic with the markup on their shipping costs - so I'm wondering whether the two fluids (a Developer and a Stencil Activator) could be procured over here in Ireland - so saving on shipping costs.

Question is - how to find out what these liquids are ? I've seen CSI - where they put a few drops of 'something' into a mass spectrometer and it tells them exactly what it is - but how does it work in real life ? (Presumably an analytical lab report is going to cost a few quid ?)

The Developer is a clear liquid with no odour - so no clues there. The 'Activator' is used to adhere the stencil to the piece to be etched, and stinks of acetone.... but what else...? I guess it's possible that the same chemicals are used in the PCB or metal label business..? - and might be available over this side of the water..?

I have asked the supplier 'what's in the bottles' - but fully expect them to tell me where to go!

Anybody got any experience in this area please ?

Thanks Adrian

[Dave Osborne]

Have you considered getting stencils lasered directly out of stainless?

You can get dura film from Mastergrave.

[The Natural Philosopher]

Or use a sheet of acrylic.?

I can laser cut either.

[Adrian Brentnall]

That's an idea - but it's likely to be a small number off each design - and the ability to produce a design & stencil 'locally' on my pc is a big advantage. I might also end up etching non-flat items like glasses etc - not sure if the stainless would conform to those surfaces?

So you can - I'm sure I emailed them asking for details but didn't get a reply - however the kit in your second link looks to be the same as I've just purchased.... so it mught be possible to purchase the consumables from mastergrave (will have to see what their postage/shipping rates are to Ireland!)

I was planning on making a UV-led exposure box - having seen what people are charging for a UV-bulb and a bit of bent ali!

Adrian

[Adrian Brentnall]

I need (I think!) a stencil that can be either flat or conforming to the shape of a rounded surface (drinking glass etc) - and may be a one-off or smallish run (say up to 20).

I know it's not quite the same as laser-cut, but I can do vinyl-cutting and then acid cream etch - but the detail's relatively coarse on small designs, and they are very much 'one-use-only'...

Knowing that the consumables are available in the UK makes the whole thing look more practical - assuming that Mastergrave have realistic shipping costs to Ireland - not every supplier does!

Thanks Adrian

[Owain]

I think it was the late Andy Hall who used to arrange his own couriers to collect stuff from US sellers, so avoiding the widespread incompetence or unwillingness of US suppliers to supply outside the land of the free and the home of the brave.

More than a few quid.

The Materials Safety Data Sheet or their equivalent of COSHH (OSHA?) data might prove revealing.

Owain

[Adrian Brentnall]

I've had some success in the past by asking (particularly) Stained-glass suppliers who do know where 'Urup' is to source things and then post them for me - but you don;t like to make a pain of yourself by doing this too often

Thought so ...

They weren't supplied with the liquids - is that something that should have been supplied. Just a laser-printed label saying 'Developer' and 'Activator'.

Actually - the problem may have gone away as Dave gave me a link to a company in Bedford (lil' ol England ) who seem to have the same kit in stock - and might even ship to Ireland for less than a King's ransom...

Need to get on with the exposure unit - 100 UV leds on veroboard - what fun !

Thanks Adrian

[Tim Watts]

Any reason for LEDs rather than tubes?

[Adrian Brentnall]

Lower power, cheaper..... and I've always liked leds

Online folks were asking UKP100 - 300 for a simple lightbox - seemed possible to diy it cheaper...

Seems that the trick is to get the spacing right between the leds and the distance from leds to exposure area so that the 'beams' merge...

I guess a light etching of the underside of the glass might also help..?

Lots of examples on the web - like this one

[Adrian C]

based in Dublin came up for me while googling. While possibly not etch-o-matic dealers, there is similar stuff on their website.

That 'developer' _could_ be a solution of sodium hydroxide in water, which was the usual for removing UV exposed resist on PCBs and metal labels I've used - but then I'd not like to guess compatibility being that your stencil also has an active chemical on it.

[Dave Plowman (News)]

buying one.

[Dave Plowman (News)]

The press and peel stuff designed for PCBs might work on glass - it does on at least some metals. You simply print it on a laser printer then iron on. I assume glass would stand 200C? Of course only maybe suitable for flat glass?

[Owain]

18 superlux leds on a PCB designed to replace a 150W floodlight (PCB =A32.95 ea)

Owain

[Adam Aglionby]

Thin as possible glass, its a UV block.

one

> Adrian

LED UV ain`t cheaper, ususal `UV` LED is around 400nm , to go below

400nm price rockets, lifespan can also be measured on some in 100`s of hours due to degradation.

Most UV curing things like to go lower, blacklight blue fluro is centred on 379nm which means faster print times, LED is also hard to get to focus evenly, UV reactive dyes are much more snsitive to power density than MK1 eyeball.

Blacklight CFLs are cheap as chips nowadays.

Cheers Adam

[<me9]

bulb (small flouorescent tube). Will LEDs be a suitable wavelength? We (a group at work) bought a tube that would work in a small battery powered lamp, but the UV degraded teh plastic in next to no time. It also needed keeping well away from eyes.

[Dave]

Dave, am I right in thinking that a sun bed tube is the right sort for this project?

Dave

[Andy Dingley]

Dental UV cure sets are about 80 quid these days (Chinese eBay ones), which is getting to be affordable.

[Dave Plowman (News)]

I dunno. I used standard 'black light' ones. Don't think sun bed ones are the same.

[Steve Firth]

Is this as accurate as your claims about laminated glass?

I take it your complete silence on that subject is your abject apology?

[Dave]

I only asked because the UV box I borrowed many years ago had light blue lamps and not the black light ones, nor the ones for erasing EPROMS. When I get a round tuit I'll get back on this.

Dave