Author Topic: How do you do your PCBs?  (Read 5748 times)

Offline CrazyModder

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Re: How do you do your PCBs?
« Reply #25 on: January 21, 2016, 01:54:51 PM »
Yeah, looks like you used that tank commercially?

The methods outlined up there are certainly primarily for hobby purposes. If I find a timeslot somewhere between family and work, usually on late Saturday or Sunday, I want to make a smallish PCB right now and not wait for a delivery, no matter how fast or cheap it is. Also, often I notice something wrong with the layout only after the fact, and then it's no biggy to just go ahead and fix it right there and then, and do another run. ;)

Sure, if it's a bigger project with many ICs, vias etc., then a service will probably be the better choice.

Offline grg12

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Re: How do you do your PCBs?
« Reply #26 on: January 21, 2016, 02:55:23 PM »
LEDs emitting UV light with wavelength between 340nm 420nm work great with POSITIV-20 photoresist. I built a small (free version of Eagle sized :) ) lightbox using 168 of them and cheapest picture frame i could find (expensive ones have UV filter to preserve picture colors from fading). Laser-print on tracing paper (transparency foil tends to shrink during printing), then the print goes for a few minutes in jar filled with lacquer thinner vapours (cottonball with a drop of thinner) - this causes laser toner particles to expand a bit - the print has more "opacity" afterwards.

Offline awemawson

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Re: How do you do your PCBs?
« Reply #27 on: January 21, 2016, 03:13:42 PM »
This thread has encouraged me to plan to complete the 'air plumbing' to my CNC mill so not only can I then use my high speed air spindle to route PCBS, but also power the lock on my 4th Axis as well  :ddb:

Spindle is a simple jet of air impinging on a gear wheel and it spins at an enormous speed with the lubricated air emerging though the bearings to cool them, as they spin far faster than their upper design speed  :clap:

Involves a bit of swinging in the rafters so one for when I'm off light duties  :lol:
Andrew Mawson
East Sussex

Offline CrazyModder

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Re: How do you do your PCBs?
« Reply #28 on: January 21, 2016, 04:06:07 PM »
spin far faster than their upper design speed  :clap:

That's what we're here for, on MadModder!    :drool:

Offline PK

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Re: How do you do your PCBs?
« Reply #29 on: January 21, 2016, 06:16:27 PM »
Yeah, looks like you used that tank commercially?
I've mentioned it in other threads, its true we do commercial work. As such some of what I put up may not be relevant to the hobby user. We did however start out as, and continue to be, hobbyists. All those pictures were from my shed at home. At work we still apply the 'DIY or die' approach to building new machines and capability. We're very much of the same mind set.

In any case, feel free to ignore everything I say, just tell my wife you're doing it, she'll appreciate the company..

Specifically here, all of those tanks are appropriate for one off boards at home...

Quote
The methods outlined up there are certainly primarily for hobby purposes. If I find a timeslot somewhere between family and work, usually on late Saturday or Sunday, I want to make a smallish PCB right now and not wait for a delivery, no matter how fast or cheap it is. Also, often I notice something wrong with the layout only after the fact, and then it's no biggy to just go ahead and fix it right there and then, and do another run. ;)

Yes, I need it now! comes up every now and then. The problem with the etching is that the photo emulsions and chemicals have a limited shelf life (especially in the heat). If you are doing two boards a year then it can be difficult to get a good result.

When I get the 60KRPM spindle running at home I'm going to have a go at isolation routing.

Mostly though, because SMD is pretty much unavoidable now, the fact that commercial boards come with solder masks makes them pretty much the only choice..


Offline CrazyModder

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Re: How do you do your PCBs?
« Reply #30 on: January 22, 2016, 03:20:33 AM »
Nah, I don't want to ignore you, I just want your tanks!  :drool:

Wasn't intending to downtalk your solution - non-native speaker and all such.

Offline PekkaNF

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Re: How do you do your PCBs?
« Reply #31 on: January 22, 2016, 03:31:16 AM »
Thank you all very much. This has been most useful.

Hobby means very different things for most of us. And it all depends what we are doing :wave:

For me Traub and other machinery awemawson has looks pretty involved, but fits still into "hobby" category.

I also understand if a "hack" is enough for some.

I'm often somewhat in between, my background is electrical engineering, but never designed any of that for living. Still I have much respect to volts and amps. :zap:

I like much of the stuff that is professional/semiprofessional, even if I can't get the stuff. Often it is very nice to know alternative methods.

My motivation to PCB making is that I only make those assemblies I can't buy or does not exsist or needs combining some simple "stages" to get the end result. And I usually want it now. Therefore I like DIY PCBs even when they are crappy. I ahve manged to gobble something up, but SMD is a new challenge. There is a big danger that I will learn something.

I have made in past two sided PCBs, but only to solder trough components and no real vias. Plenty of jumpers. I have reached my limit and trying to take the next step.

I think I have seen writeups about the laminated solder masks same way than etch resists. Never tried one.

Is chemical tinning any alternative or addition to solder mask? Some fluxes seem to work differently even on kit boards.

Pekka

Offline awemawson

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Re: How do you do your PCBs?
« Reply #32 on: January 22, 2016, 04:16:17 AM »
Pekka, I use 'electroless tinning' - it really is very easy - the cleaned etched copper clad board is immersed in a warm solution:

https://www.megauk.com/tin-plating.php


As an aside my personal take on the professional /amateur discussion is this: If some one joins and pushes their commercial products and services solely for their own benefit then they are spammers and should be removed - that's not what the forum is about. However if someone active in any of the spheres we discuss and enjoy here chips in and offers advice, or points to one of their products that would solve a problem someone has, or a process that they use then surely we can only benefit  :scratch:

I'm sure that John Stevenson won't mind me quoting him as an example: he runs a commercial jobbing shop, is very knowledgeable regarding machining and CNC, and is involved with ArcEurotrade - one of our suppliers. His contributions to this and many other 'hobby' forums has been legion. I don't think that anyone here would want him to 'cease and desist'

Personally I've never made my living using any branch of mechanical engineering or CNC - it was always a hobby totally different from the industrial process control computers I earned my living looking after. Even before I retired I always would refuse to take payment for all those little jobs people bring you - no problem trading favours, but not actual payment, firstly as I didn't (and don't) want any local authority being able to claim I am 'commercial', and secondly I don't want the commercial and moral pressures of deadlines and specifications - after all, I do it 'cos I want to do it.


....... just my personal take, not necessarily Forum Policy - that's for Eric to set out.
Andrew Mawson
East Sussex

Offline CrazyModder

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Re: How do you do your PCBs?
« Reply #33 on: January 22, 2016, 04:39:13 AM »
I did not at all mean it in a derogative or "cease and desist" way. My comment with the unlucky word "commercial" in it should have read like this:

"You seem to have used these tanks in a professional way, they look much better than my randomly hacked diy tools."

Just to clear that up!

Offline PK

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Re: How do you do your PCBs?
« Reply #34 on: January 22, 2016, 04:59:33 AM »
:-) Looks like the missus is drinking alone tonight then.

The last board I etched was done in glass tray over a gas hob using ammonium persulphate.  I basically boil the solution with the board in it. I've used microwave ovens and her tupperware too.

Offline PekkaNF

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Re: How do you do your PCBs?
« Reply #35 on: January 24, 2016, 12:33:48 PM »
One more distraction: How does the vacuum system works on two sided UV PCB exposure unit?

I only have used method were PCB is slipped in a artwork and put between two glass plates.

I'm wondering how much stress vacuum creates on glass plates and is cheap 2 mm or 3 mm glass plaet enough for euro card size?

I have small quiet compressor that has vacuum inlet. Might consider vacuum. There must be some stuff I'm not aware of.

Would it be possibe to use exact same thickness (probably easiest to use even same PCB material) as a "frame" that has eurocard (100*160 mm) or such cutout for the PCB under construction. Maybe neoprene seal on perimeter to seal the artwork - or glass plate?

Pekka


Offline PK

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Re: How do you do your PCBs?
« Reply #36 on: January 24, 2016, 05:33:58 PM »
 :doh:
One more distraction: How does the vacuum system works on two sided UV PCB exposure unit?

I only have used method were PCB is slipped in a artwork and put between two glass plates.

I'm wondering how much stress vacuum creates on glass plates and is cheap 2 mm or 3 mm glass plaet enough for euro card size?

I have small quiet compressor that has vacuum inlet. Might consider vacuum. There must be some stuff I'm not aware of.
Vacuum is easily substituted with mass for the DIY case. You just need to hold the transparency onto the PCB. Holding it stupid hard doesn't (in my experience) make any difference.
The lid on my exposure box weighed maybe 6-7Kg. I used 5mm toughened glass, about 450mmx250mm. I recall supporting it at the ends with two bits of round bar and standing in the middle. Unbelievably strong stuff!
PK

Offline PekkaNF

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Re: How do you do your PCBs?
« Reply #37 on: January 25, 2016, 04:21:19 AM »
:doh:
One more distraction: How does the vacuum system works on two sided UV PCB exposure unit?

I only have used method were PCB is slipped in a artwork and put between two glass plates.

I'm wondering how much stress vacuum creates on glass plates and is cheap 2 mm or 3 mm glass plaet enough for euro card size?

I have small quiet compressor that has vacuum inlet. Might consider vacuum. There must be some stuff I'm not aware of.
Vacuum is easily substituted with mass for the DIY case. You just need to hold the transparency onto the PCB. Holding it stupid hard doesn't (in my experience) make any difference.
The lid on my exposure box weighed maybe 6-7Kg. I used 5mm toughened glass, about 450mmx250mm. I recall supporting it at the ends with two bits of round bar and standing in the middle. Unbelievably strong stuff!
PK

Jep. I just wonder:
* Previously I had trouble finding material that will not absorb UV (surpricingly many glass and PMMA sheets does..) and like to keep it thin. Found 2 mm picture frame glass, this does not take much load.
* Taking care to put "ink" side next to photoresis, hmmm. not extremely flat if loaded only on edges...
* Would like to expose it two sided - one go - putting books or weight lifters on top of it is not viable
* Plastic C-profile seems to clamp it good enough, might go for that.

Usually KISS is best, sometimes it just takes few tries to get there and boil it down to minimum. :lol:

Pekka

Offline PK

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Re: How do you do your PCBs?
« Reply #38 on: January 25, 2016, 05:15:51 AM »
Honestly?
You're overthinking it.
I ran 5mm glass and my exposure times were bang on for the wavelength (ie around 90 seconds) .
The plastic film and the copper layer crushes more than good glass bends.
That box that I showed a picture of (which had slotted mounts for the hinges BTW so the top plate of glass could always be parallel with the bottom) made hundreds and hundreds of boards with 10 mil tracks.
By all means, go buy special glass, vacuum pumps and dilthium crystals, it's fun to make these things as flash as you can (I'm serious, I really get it..).... but getting your dev/rinse/etch chemistry under control, or a temperature controlled storage box for chemicals and emulsion coated boards will have orders of magnitude more effect on the finished board than a few microns of gap between a film and a board.

Offline PekkaNF

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Re: How do you do your PCBs?
« Reply #39 on: January 25, 2016, 06:03:02 AM »
Ok. Thank you. My suspicion has a reason: Few years ago I bough 1 metre long 5 mm thick PMMA (acrylic) that was supposed to transparent to UV. It Blocked most of it. When I asked them to double check it with BIG LETTERS, I got the type an sure enough it had a filter added....they refused to deliver small amount "stadard" PMMA that would not filter UV, noobody-wants-it!. Then I bough some "good glass" and you may guess it. IT HAD UV FILTER TOO. Fool me once - well - fool me six times?

I put presensitized PCB and different "transparent" material on both sides and nothing in 10 mm space between the glass and PMMA. That way I figured that while 30 s exposure showed up almost good eneough without any "filter" 120 s was marginal on that first UV-transparent acrylic sheet I got and the "glass" need nearly same. I had cut the acrylic to size and I was in process of finishing the light box.

I'll build slap together 2 sided unit that assumes sandwich of max. 2-classes (2-3 mm), two transparencies and PCB of 0,6 - 1,5 mm + plastic C-profile to keep them clamped. If that doesn't work I'll take up on knitting.

Pekka

Offline PK

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Re: How do you do your PCBs?
« Reply #40 on: January 25, 2016, 08:42:42 AM »
If that doesn't work I'll take up on knitting.
Don't sell yourself short... there's always gardening!


I would never have thought that UV filters on glass would be a thing in your part of the world.... Actually, I've never heard of them applied to glass or perspex anywhere. Wow... Must remember that.

Back on topic. I'm sure you can get to a place that sells the right tubes.  Just in case the UV tubes also have UV filters on them, the tubes in 'bug zappers' work pretty well for smaller boxes..
PK

Offline PekkaNF

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Re: How do you do your PCBs?
« Reply #41 on: January 25, 2016, 09:55:16 AM »
If that doesn't work I'll take up on knitting.
Don't sell yourself short... there's always gardening!

Incidently, I like gardening, but it is under 20-35 cm of snow now. Garage is too cold for my complexion, therefore I'm confined indoors :lol:

I would never have thought that UV filters on glass would be a thing in your part of the world.... Actually, I've never heard of them applied to glass or perspex anywhere. Wow... Must remember that.

Back on topic. I'm sure you can get to a place that sells the right tubes.  Just in case the UV tubes also have UV filters on them, the tubes in 'bug zappers' work pretty well for smaller boxes..
PK
I know. Most of the winter I only see sun from outside...maybe the seller tried to be nice and sell me "the good stuff"?

I have some tubes: UVA lamppu 8W T5, philips Actinic BL
http://www.reichelt.de/Etching-Machines-Exposure-Equipment/UV-LAMPE-1/3/index.html?&ACTION=3&LA=2&ARTICLE=936&GROUPID=3376&artnr=UV-LAMPE+1

The acrylic turned out to be: PLEXIGLAS® XT 0A000 (20070)Standard solid sheet grade; largely UV-absorbing....Hmm. maybe I should make a light table out of that to filter rest of the residual UV that is left on yellow lamp :lol:

Pekka