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PCB UV Box - Follow Up

Hello,

First off, thank you to every one of you for answering the other thread. It's given me plenty to research and perhaps over analyse.

I think I'm going to go for the ready kit put together by Rapid, this is written up below. But before I do that I'm left wondering something.. Where I have my nails done they use one of the little UV boxes. They're here on eBay;

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Now what I'm wondering is. Would one of those do the job? Or more to the point, would it be cost effective to strip one down and use the parts. Thereafter ALL you need is an enclosure and some perspex. Also today it's become clear regarding 4mm glass that suppliers either only stock UV-blocking glass, or don't even know at all. No one knows what they're selling anymore or even cares!! This is the UK, it's a dump full of under achievers and everyone has a degree in Travel & Tourism or Marketing, everyone else is on state benefits.

So.. The nail box up above? :-)

Warm thanks,

Alison

The following will need to be viewed in a fixed font such as Courier to all line up;

" Sourcing a UV Exposure Box for PCB Development.

-----------------------------------------------

  1. Introduction
  2. What's For Sale?
  3. Ultraviolet exposure unit with timer 202E
  4. Ultraviolet exposure unit with timer 202E - Starter Kit
  5. UV tubes available on eBay
  6. Flight case style enclosures
  7. Minimum parts required
  8. Conclusion

  1. Introduction

--------------- I wish to start developing PCBs using the Photoresist and UV Development method. In the past I have used a Dalo pen and drawn everything out, using ferric cloride to etch the copper off. I would like to design more complex circuits on a PC and print to transparancies.

The immiediate requirement is to source a UV Development box. There are two options; Build One; Buy One. When considering building one the light output has to be in the range of 400nM. There is absolutely no point in approaching DIY outlets as they have haven't a clue what you're talking about (I've been out hunting today). Blacklight dark UV tubes for making your white t-shirt glow are NOT suitable.

UV LEDs have been suggested as a possibility. These would need to be of a high candle output documented to be in the region of 5000-7000mcd, these can only be economically sourced from Hong Kong. There is a documented concern that UV LEDs placed in a grid fashion will result in exposure hot spots on the resulting PCBs. The projects are documented on the net, yet there are no examples of the PCBs which have been produced. This is a natural concern despite excitement in using such devices. It would be brilliant to have a compact UV light box.

  1. What's For Sale?

------------------- There are very few UV boxes out there. The most basic are about £120 all in, ranging to £1000's for double sided vaccum models.

There are very many UV tubes for sale on eBay. UV LEDs are also available.

  1. Ultraviolet exposure unit with timer 202E

-------------------------------------------- This is sold by Rapid for £115.68 (£98.39+VAT) item number 34-0700. It is also sold by Maplin for £105.14 (inc. VAT) item number YA36P. It uses a

6-minute mechanical timer. It uses two 8W 12" (304mm) tubes, 15" maybe??. The exposure area is 240 x 165mm (9.5 x 9.5"). The overall unit dimensions are 438 x 184 x 102mm (17 x 7 x 4").

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  1. Ultraviolet exposure unit with timer 202E - Starter Kit

---------------------------------------------------------- This is available from Rapid for £129.54 (£110.25+VAT) item number 34-0690. It includes a number of accessories making a saving of about £20 if bought seperately. It is Kit B.

These accessories are;

Rapid Quantity Description Unit Sub (inc.VAT) ----- -------- ----------- ---- --- ----

-----

34-0796 (1) Artwork Drafting Pack £4.95 £4.95 (6) Assorted Sheet Transfer ----- 34-0105 (3) 100 x 160mm SS Photo PCB £2.49 £7.47 34-0115 (1) 203 x 114mm SS Photo PCB £3.49 £3.49 34-0295 (1) Polifix Block £1.95 £1.95 34-0745 (1) Polypropylene Chemical Tray ----- 34-0395 (2) Developer Crystals £0.79 £1.58 34-0385 (1) Seno GS Etching Kit £8.95 £8.95 ======== £28.39 (£33.36) ======== 34-0700 (1) UV Exposure Unit - 202E £98.39 (£115.68) ======== £126.78 (£148.97) ========

A saving of some £20 is made as predicted. When offset against the standalone cost of a 202E, the above items are provided for an imaginary cost of some £10.

  1. UV tubes available on eBay

----------------------------- A wide range of UV tubes are available. Most are marketed for use with Fly Killer devices and for curing Acrylic Nails in beauty salons.

4W 6" (152mm) straight tubes;
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9W 6" (152mm) nail curing double tubes;

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25W 9" (229mm) U tubes;
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22W 8" (203mm) Circular tubes;

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  1. Flight case style enclosures

------------------------------- It would be intended to fit a self build unit into a small flight case. These are relatively expensive to buy. I have a small case here which is

283 x 235 x 90 (11" x 9" x 3.5") external dimensions, it was purchased for £9.99 and contains a hobby drill. It seems that to obtain the smaller flight cases it is economically easier to buy something else and to use it's presentation case, thus discarding it's contents. Makeup boxes, hairdryers, all sorts of low priced items come in perfectly adequate aluminium flight cases.

My full size budget flight case which can be bought for £11 in a local DIY store has external dimensions of; 464 x 328 x 150mm (18 x 13 x 6"). It is made as cheaply as possible yet you could not achieve that level of build yourself without significant outlay.

  1. Minimum parts required

------------------------- This is assuming use of a full size budget flight case, with basic ON/OFF operation;

Quantity Description Unit Sub (inc.VAT) -------- ----------- ---- --- ----

-----

(1) Flight case £11.00 £11.00 (4) 12" UV tubes £5.00 £20.00 (4) Starters £1.00 £4.00 (2) Ballasts £7.50 £15.00 (1) Rocker ON/OFF Switch £1.00 £1.00 (1) IEC 3-pin socket £2.00 £2.00 (1) 4mm Cut glass (local) £5.00 £5.00 (1) Other unknowns (fixings etc.) £20.00 £20.00 (1) Travelling costs £15.00 £15.00 ======== £93.00 (NA) ========

The above does not take into consideration PCBs, developer etc. It appears cost effective to buy the UV 202E kit from Rapid for an approximate £35 extra. The above also does not take into account stress and rushing about. I could have the kit on this coming Tuesday after the Easter bank holiday weekend.

  1. Conclusion

------------- It will be more practical and straightforward to buy the complete kit for £129.54 (£110.25+VAT) item number 34-0690, from Rapid. At this early stage in my experiences with UV development it makes sense to buy a prepared kit with instructions where it is all there for you from the moment go.

Having spoken to my Mother who knows everything her comment is, "You're just like your bloody Grandfather, you'd lick a farthing out of a turd." In other words, buy the kit. "

Reply to
Aly
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In message , Aly

Reply to
Clint Sharp

it's

There's nothing special about these light box things. Don't allow distraction by talk of weird and wonderful exotic materials. The nail hardener thing (also insect killers, currency detectors et al) wouldn't be worth the effort to break down and the UV tubes will be be quite weak. It's quite painful to look at the bare blue light of a real UV box. Built a box 7 tears ago for small 'one off PCBs'. Works well. Vital key is those UV tubes which Maplin offers at £16 for 2. Mine uses 4 Maplin UV tubes just clipped into 2 of those cheap 12V dc, camping florry lights thingies. Stuck in a MDF box lined with cooking foil, with a normal glass window and a 12V power supply. High density black lines, printed on matt film and 7 minutes exposure gives lines as fine as I can deal with. (ie those thin buggers that end up going in between the 0.1" IC pads).

--
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Reply to
john jardine

In message , Aly

Reply to
Clint Sharp

quite

foil,

gives

Hey John :-)

Perked up again this end. Must be something to do with Clint and his taxes. :-)

Back on track.. Reading.. Those Maplin tubes I believe to be 8W 12" T5 UV tubes. Two for £15 odd, Maplin YA39N. About the same at Rapid, 34-0707.

These are what I'm looking at on eBay which I believe to be the same at £4.50ea.;

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Out local shop for local people is charging... £5.84ea. although I'm not sure if they'll allow local pickup. I much prefer picking up locally.

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I'm swaying towards thick perspex maybe, although have found that picture framers are the ones to talk to about non-UV glass and offcuts. 4mm is a minimum.

One of my electronic friends has mentioned banding caused by the intense UV light in the area closest to the tubes, and is suggesting the £200 UV box from Rapid, 34-0705 ;

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I just want to build one really. Spending £200 goes against why I even do any of this. I do it for fun :-)

The bits I can source at no cost; IDC, switch, ballast, starters. The outlay will be the flight case, say £20. The tubes, say £20. Glass, say £5 odd. So give or take £50 for a decent little box.

:-)

Aly

Reply to
Aly

[...]

taxes.

UV

UV

£5

Tell your electronics friend to go bollocks. Banding or shadowing occurs when a tube fails. I.e when the dark end of a big PCB is seeing maybe 1/5 of the UV at the bright end. And isn't it amazing how people always know they will be safe from risk and critism by recommending expensive commercial product as an 'answer' to any technical question?

My ISP for some reason will not let me use Google, so will check the links tomorrow. They look useful as I'm after half a dozen UV tubes for a metal photo-etching light box I'm thinking about. A fiver or so each seems reasonable, after all they're just standard tubes with a modified coating. Perspex, 4mm glass, both OK. Maybe even better is the double glazing acrylic sheet sold by Wickes B+Q etc. The stuff is designed not to discolour from the UV in sunlight. The plastics have to be cut though and it's maybe easier just to call into the local glass shop and have them cut a piece to size for a couple of quid.

But yes. I love to see a good heartfelt rant!. Nowadays, seemingly becoming a British cultural pastime.

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Reply to
john jardine

In message , Aly

Reply to
Clint Sharp

Normal glass is fine for a UV box.

Reply to
Mike Harrison

ISTR reading somewhere that perspex is less UV-transparent than glass. Probably more important is that it scratches much more easily than glass. I think I used 3mm glass on my A3 sized box - easily strong enough if supported all round.

Not a major issue - put some tracing paper or white paper on the glass and adjust the glass-to-tube distance so the illumination looks reasonably even to the eye. It's not too critical.

Reply to
Mike Harrison

What's your opinion on this? (and anyone's opinon for that matter). I'm humming and harring over it. Trouble is the weight. I can barely carry

25Kg. Have a logic analyser which I don't use as it's too heavy to move about, bought another one Thurlby LA4800 which is about 2Kg. Anyway...

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£250. Double sided. I'm tempted, but need pushing. I fancied a little UV flight case I'd done myself for £50.

What do you experts think on that eBay one? They're just down the road too so can pickup, have already spoken to the guy.

Alison :-)

Reply to
Aly

......

Some plastics (e.g. Polycabonate) will block parts of UV bandwidth, don't know any that block the whole UV bandwidth, if that was the case sunglasses would be made of them.

Scratching and easier to mark (etch fluids etc..) also more susceptible to various bending and warping over time. The tubes do get warm. Also some plastics have higher refractive index and lower transfer rate which can mess things up. The lower transfer rate usually means the plastic heats up a small amount as it absorbs some of the UV. Also means longer exposure times to get same amount of cumulative UV to the object.

Getting even illumination is a major key, over the whole area. get your interlocks (microswitches and relays) as well as heat dissipation if used frequently.

Remember looking at a project for UV curing a glue on a plastic sheet

6ft x 3ft, with 5 tubes a couple of feet away for optimum evenness and using reflective UV tubes. These are specialist tubes with internal reflector layer on 60% of the inside surface, tubes are used for tanning couches and industrial applications. We got mock up done but full blown mechanical jig never got built. 
--
Paul Carpenter          | paul@pcserviceselectronics.co.uk
    PC Services
              GNU H8 & mailing list info
             For those web sites you hate
Reply to
Paul Carpenter

Well if you could bid a low price on it or afford the 250 for a working unit that has fetures you want and features (like double sided) you could use and can do it to have more time doing electronics you want to do then go for it.

No harm in bidding while pricing up a home made alternative and working out max size of PCB you are likely to need.

My largest single PCB so far is 30cm x 30cm (6 layers) but done at a PCB shop, the 0.2mm vias, I did not fancy doing by hand.. :-^

Could be a useful purchase if you have somewhere to store it and use it size is another issue.

--
Paul Carpenter          | paul@pcserviceselectronics.co.uk
    PC Services
              GNU H8 & mailing list info
             For those web sites you hate
Reply to
Paul Carpenter

Hey Paul,

Long time..

Erm. I've just bought it!! :-) It's BIG!

Alison

Reply to
Aly

Yes indeed, expect email; about Hedgehog status....

^ ^ I bet you say that to all the men :-^

--
Paul Carpenter          | paul@pcserviceselectronics.co.uk
    PC Services
              GNU H8 & mailing list info
             For those web sites you hate
Reply to
Paul Carpenter

Why yes, yes I do Paul.

Reply to
Aly

I dont wish to throw a spanner in the works but your tax pounds have very little to do with UK universities these days. The vast majority of undergraduate student funding is done by a)charging foreign students extra (at least £11K per year, more depending on the course) to cover the loss left over from only b)charging the home students 3K a year. Most university equipment is funded through industrially linked research (and industrial donations), which has to be fully economically costed, meaning all projects have to be run as a business would including all costs inc office space, technician time etc counted and charged to the project account - so they cannot be considered to have an unfair advantage over industry. Research council grants form a percentage of the money given to universities, but only generally cover postgraduate projects which have to be fully justified and peer reviewed before acceptance. And even they are sponsored by industry. If a group does not pull in funding for a year or two it is effectively canned.

Uni's arent the public tax black hole they used to be, which is WHY they have been forced (against their will, trust me) to create "micky mouse" degrees which pull in people who will pay to do a course which takes little supervision and still generates the same cash per head. To have purely "useful" degrees for the small minority who can acheive them through skill and interest, as opposed to just taking it as a way to muck about for 3 years, is not financially viable - that target market is too small and could not collectively afford the actual cost of their tuition. If you want them to drop their "micky mouse" degrees then you WILL pay for it in taxes!

Reply to
Coyoteboy

In message , Coyoteboy writes

Hmm, sense of humour bypass detected, donning flameproof attire. I would say though, that if a penny of my taxes went to funding 'surf science' or Travel and tourism courses, then I'd consider it wasted (WTF is a travel and tourism course anyway?), I would much rather see the little that universities do get of my tax pound going to fund 'proper' courses instead of the bull*h*t 'we've got more graduates than you' games the government has been playing for years now.

I have great fun taking the p*ss out of 'students' on Travel and Tourism courses, hell, my niece is one (nice girl, recently got a full page spread exposing her as a binge drinker in her Uni town evening rag) and dumb as a post, but, bless, she'll have a degree at the end of it all if she can manage to keep her head out of the toilet long enough to show up for a lecture or two so she should be ideally qualified to ask if I want fries with that when I next visit McD's in her home town. You imply I would deprive myself of that amusement.

> 
--
Clint Sharp
Reply to
Clint Sharp

university

projects

justified

little

could

We, the people, gave the uni's £7 Billion this year, seems more than a 'very little'. They also garnered an additional £6 Billion by the means you mention. As a taxpayer, I -expect and want- to pay taxes for higher education. I want this country to be a centre of excellence and am happy to contribute to this end. I am very unhappy to have to pay for the education of media studies graduates, golf course designers and the other dalliances. The mickey mouse degrees are actually a true reflection of our present social culture and are here to stay. Few youngsters want the work entailed studying subjects that would benefit the country in an industrial sense and as the media studies people et al invariably come from well off, middle class backgrounds and can pay their own way, then it's time the uni's were forgotten and my taxes spent in more worthy areas. (Honest!).

1% of the population now own 50% of the country's wealth. 50% of the population own 1%, hence the country is becoming little more than a large offshore banking operation. Vastly wealthy bankers supported by a huge army of servant workers. Industry? Technology?, forget it. The Swiss are remembered for their Cuckoo clocks, we'll be remembered for our bad plumbing. 
--
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Reply to
john jardine

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