DIY PCB Idea

[SAborn]

Anyone tried quartz/tungsten/halogen lights as a UV source?
If thet are removed from an glass layer, they chuck out UV too.

At 50-500 watts it would not look to be a good option.

As this is a electronic forum i think the advice of a bunch of UV leds would be a far better option, as they work very well with pcb and are quick, cheap, and low power.

They give a very consistant results and there is no mains wiring required.

 

[Dippy]

How do you ensure a good even spread of UV with LEDs?
As we all know , the 'lens quality' of LEDs is very iffy (uneven).

Proper UV boxes are very good, ensuring edge to edge consistency for larger boards (esp where you have <0.2mm tracks).

I've yet to see LED based UV exposure boxes from proper manufacturers.
(No, I don't mean Johnny's home-made UV box )
I'm sure they'll happen, I just haven't seen one to see the method for even distribution.
I wonder if I could convert a plotter into a UV exposure unit with a single UV emitter?

In the meantime I'm going to get some suntan lotion and sit under my CFL.

 

[SAborn]

How do you ensure a good even spread of UV with LEDs?
I wonder if I could convert a plotter into a UV exposure unit with a single UV emitter?

In the meantime I'm going to get some suntan lotion and sit under my CFL.

Oil up mate and dont forget the sunnys for the eyes.

I use leds at aprox. 100mm (4") off the board to get even exposure.

Also have the leds mounted on an old bubblejet printer carriage so they scan across the board.

You could get reasonable results with just hand scanning but i like to just hit the on button and walk away while it do the passes and switches itself off when done.

Most DIY people only do small boards so its not to hard to set up a mini exposure box.

I agree with not seeing a comercial led exposure system as yet, but we are talking DIY here and its well with in the DIY scope to use UV leds.

Not sure what you mean by a single UV emitter but find at least a double row of leds work best with a scan function.

 

[Dippy]

I meant like a UV 'laser beam' in a plotter type mechanism zapping the photo-resist in a similar way that a milling cutter cuts the copper in CNC PCB mills.

Out of interest, how long would it take to expose a 6" x 4" PCB using your scanning method?
Is your consistency good enough for (say) 0.2mm tracks edge-to-edge with 100% develop and etch results?

 

[SAborn]

I like your CNC idea.

A 4 x 6 board would take about 5 miniutes to expose as it scans slow at about a foot per miniute and do several passes so it really comes down to the distance it needs to travel before it reverses the pass.

I dont mind it slowish as there is always something to do while its exposing, and find if im doing repeat boards then its exposed by the time i develop one and check it anyway.

Consistant results is important compared to speed.

0.2mm is doable but as i work off plain paper printed, the grain in the paper causes problems on fine tracks and i tend to go no smaller than 0.5mm when needed.
Also plain paper extends the exposure time too compaired to clear film, but its cheap and who cares about a miniute or two.

Remember its DIY we are talking and there is little point in going ultra fine tracks for the average picaxe project.
I see no point in etching heaps of copper off a board for the sake of fine tracks if it is not needed.
Been there done that, and now days would rather have wider tracks and larger pads where able for the average circuit board.

For the home tinker to be able to produce a good board with 1mm tracks is good enough for 99% of the time, and a hell of a lot beter than vero board 100% of the time.

Often notice every time a DIY PCB thread comes up it always ends in whos got the best light box and can do the finest tracks the fastest.

It simply dont matter to the home builder, good exceptable results is the important factor, within a persons budget they can afford.

I float a plastic container in a bucket of hot water for etching and it works just as well as a $100.00 etching tank.

You dont need all the expencive stuff to be able to produce a good useable board. (it can make it easier though)

 

[Dippy]

As you say, 100% better than veroboard - if you have the time and mum's kitchen facilities

However, what I was trying to get at was bottom-line reliability.

We both know the cost of coated copper board - which is a whole subject on it's own.

Therefore I don't care if the exposure takes 1.5 minutes as with a proper UV box or 5 minutes with your device.
But if the 'method' leads to a 20% failure rate then it's an expensive 'method' in terms of time and materials for anyone.
And, of course, failure rate increases inversely proportionally with track size.

I appreciate that hobby-time is essentially free but there is still the frustration of repeated failures when making things. I am not a patient person. It's "acceptable" by the way.

So, no it wasn't really a competition, although it goes without saying that mine is bigger than yours

 

[SAborn]

So, no it wasn't really a competition, although it goes without saying that mine is bigger than yours

They say size don't matter and if it do than you need to hang out with a better class of people

I don't have any trouble etching the fine footprints for the tiny little bloody smd devices.

I find what limits the results is the paper the artwork is printed onto and the quality of the printing in the first place.

I have gone through several printers over the last few years with less than happy results with their ability to print fine lines with good density of ink.

The old epson bubblejet i had 8 years ago was far better than any i have had since including laser printers.

Now days the PCB side is a brease but the printing is the biggest problem.

All said it is still the fastest most reliable way to make pcb's in my opinion.

 

[John West]

It's not the size of the board, it's the motion of the etchant.

OT:
I now have a keyboard with a working comma key! The only problem now is that my fingers keep trying to hit CTRL V whenever I need to insert a comma.

 

[tjetson]

It's not the size of the board, it's the motion of the etchant.

OT:
I now have a keyboard with a working comma key! The only problem now is that my fingers keep trying to hit CTRL V whenever I need to insert a comma.

I've noticed before that you've said you've had to Ctrl+V in commas whenever they were necessary. Does this mean that every day when you switch on your computer, you open a little text document with a comma and Ctrl+C? Or do you have some sort of macro or something to do it for you?

 

[John West]

I did the "little text doc" bit most of the time, but when I was in here I'd steal the comma from the "Private Messages: Unread 0, " up in the upper right corner of the forum page. It caused a problem whenever I wanted to C&P anything else though. I'd have to go back and re-grab it. But no more!

 

[tjetson]

I would have just inserted a pencil or something into the button on the keyboard (to quote Marks) lol

 

[John West]

I couldn't. It wasn't a mechanical switch. It appeared to be a Hall Effect contact, and the tiny mechanical mechanism that lowered the tiny magnet was to small and fragile for me to reattach.

I also stole one of the ALT buttons for use on the missing letter L key, as the letter L is quite indispensable, while there's really only so much ALT a body has any use for.

Now I have a good little, used, $20 desktop computer and a new second-hand keyboard. It works quite well. Also, I'm in the middle of putting together a really nice tower system with a 3GHz processor and a Gig of RAM. No more stuttering video clips for me! It's gonna be good. I'll finally be fully empowered to ride along on the information super-highway.

 

[SAborn]

No more stuttering video clips for me! It's gonna be good. I'll finally be fully empowered to ride along on the information super-highway.

Sounds like you spend to much time on route 69

The sound on those stuttering videos aint worth listening to anyway. Ahaa, Ahaa, Ahaa.........??

 

[fritz42_male]

IAlso, I'm in the middle of putting together a really nice tower system with a 3GHz processor and a Gig of RAM. No more stuttering video clips for me! It's gonna be good. I'll finally be fully empowered to ride along on the information super-highway.

3Ghz processor and a Gig of Ram? Luxury! Eeeee when I were a lad.....



Actually, 1GB of Ram sounds a bit paltry - what OS?

 

[John West]

WinXP. A Gig will do until I snag some more memory. The dead PC had only 512M and limped along running XP.

But this is all OT. 'Nuf said on my computer woes.