New method of PCB manufacturing - Page 1
Forum section: electronics / projects

author: jkristof94
author_rank: Newbie
timestamp: May 07, 2015, 08:13:57 am
content: Dear EEVBloggers!Some time ago I got interested in electronics projects. First I made my PCB-s on breadboards, then started doing toner transfer, UV exposure and so on. My problem is, they did not really come out well. There are always tips and tricks with each method. Now I am not saying those are bad methods, and I know I am the one to blame for the results, but it got me thinking.There are CD/DVD burners, with LightScribe capability. What if, we could use regular CD-RW, DVD-RW modules for creating films for exposure? Wouldn't that be interesting?My primary problem is that I don't know if there is a chemical that reacts the same way as the UV sensitive chemical, but for the DVD lasers spectrum. If there is, I could just cut out plastic disks, and use them as base material.Or can we etch away the film between the two parts of a CD? Who knows.Please understand that this is only a proof-of-concept question. And while maybe being highly impractical for manufacturing big boards, how cool would be if you could carry around your designs in a CD case?Anyway, any criticism is appreciated if not offensive/abusive. Hope we get a good discussion going.

author: tggzzz
author_rank: Super Contributor
timestamp: May 07, 2015, 08:26:08 am
content: Quote from: jkristof94 on May 07, 2015, 08:13:57 amYou can use google to research such ideas.Whatever you do, be very aware that high power lasers caninstantlydamage your retina - so makeverysure no reflections could ever get anywhere near anybody else's eyes. (I don't care what you do toyoureyes; that's your business!)

author: jkristof94
author_rank: Newbie
timestamp: May 07, 2015, 08:29:25 am
content: I tried researching with google, but not get far, that is why i asked you guys. Also, I sadly know the damage a laser can do from experience, so I will be cautious, and thanks for the reply .

author: kjs
author_rank: Regular Contributor
timestamp: May 07, 2015, 08:36:03 am
content: to be honest, I gave up making PCB's more than 15 years ago as it got that cheap to have them made and I have nice boards with vias and solder stop. Don't have to worry about fine pitch, impedance control and thin lines either. I can also use a stencil for solder paste. Sure, I have to wait a bit longer but with a bit of planing the boards are here when I need them. I started with an Edding to draw on the board, then tape on foil and ended with using a good laser printer and Ocalit (SP?) foil which gave decent films.Due to a big move in the next weeks I just trashed all my prehistoric PCB making equipment and I am sure I will never miss it. Ruined enough shirts and pants with the chemicals.....

author: jkristof94
author_rank: Newbie
timestamp: May 07, 2015, 08:59:14 am
content: Thank you for your reply. I agree that professional grade PCB manufacturing got very cheap in the recent years, however, as I said, this is only a proof-of-concept question. Also, for beginners with lots of error potential, DIY boards are better, because we could afford to make more of them as opposed to ordering PCB-s for every little change we make, while we experiment and learn

author: smjcuk
author_rank: Frequent Contributor
timestamp: May 07, 2015, 09:46:58 am
content: Sounds possible but I can see a problem: lightscribe doesn't seem to provide solid blacks which would mean that light could creep round and ruin the board exposure.Also, never just cut out a disk and stick it in a drive. Even a slightly bent one will shatter and destroy the drive:

author: donotdespisethesnake
author_rank: Super Contributor
timestamp: May 07, 2015, 11:13:06 am
content: Quote from: jkristof94 on May 07, 2015, 08:13:57 amIs the idea to take a disc shaped PCB, stick it in a LightScribe drive, mark a pattern, then etch it?I'm not sure the resolution would be very good. It's a great idea using existing mechanics, it leads to a bunch of other problems though. For example, it only works for small round PCBs with a hole in the middle. Unfortunately I know little about materials with the right properties for a particular laser. Would it work with regular photo-resist coatings?However, if you could put together a cheap XY plotter, then you can get good results just using paint, and the laser to do isolation routing.Seehttp://forums.reprap.org/read.php?133,235148.Bear in mind VDX is an experienced professional with access to a lot of expensive kit

author: sleemanj
author_rank: Super Contributor
timestamp: May 07, 2015, 01:26:47 pm
content: makig the mask is the easy part, don't know why you'd want to limit yourself to small round ones made in a dvd drive?If you realy want to go laser exposure, try a bluray laser diode, they are uv and i believe quite capabe of exposing pb resist...all be it probably slowly.

author: tggzzz
author_rank: Super Contributor
timestamp: May 07, 2015, 02:53:31 pm
content: Quote from: sleemanj on May 07, 2015, 01:26:47 pmAnd, as I'm sureyouknow, more than capable of blinding people passing by, not only the direct beam, but also reflections.As I say, I have no interest in what someone do to their own eyes, but I would get very ratty if they damaged someone else's eyes!

author: jkristof94
author_rank: Newbie
timestamp: May 07, 2015, 08:06:24 pm
content: Thank for all the postsAbout the potential risk of laser exposure : There would be none, since i do not plan on disassembling the drive, and here lies the beauty of it all. The true challenge is to re purpose the drive to do something it is not meant to do.I don't know if I can stick a PCB sheet in there, but if there is a possibility with light scribe to decrease the writing speed, like at a regular write, than maybe it would be safe even with a PCB board. It would be best to use CDs though.The problem with the DVD-RW is that the regular UV chemical (as to my knowledge) does not react to the ~650nm laser. The Blu Ray disk seems possible, and there are LightScribe enabled BD-R/RW drives. That would be a good place to start.For me the PCB size is not a problem since, as I said, it is for hobby boards with a few components, and also, I like making round PCB-s, for things like a LED wall clockNevertheless, I am happy that I got a few brains thinking O0

author: Canobi
author_rank: Regular Contributor
timestamp: May 07, 2015, 09:03:58 pm
content: Talking as someone who's recently started etching their own boards, I really like this precept.The modder/engineer in me can't help but think about lifting the emitter and making a mini CNC unit to stick in an aluminium briefcase. It would be protable, give proper emittance protection and increase the overall "exposure" area.Could even harvest motors and guide rails from a couple of flatbed scanners to use for the x y axis.I wonder what the minimum trace width would be....

author: mazurov
author_rank: Frequent Contributor
timestamp: May 07, 2015, 09:06:11 pm
content: Which color is the LightScribe laser? About a year ago I was looking for ways to laser etch copper foil and learned that green lasers are the only ones suitable as other wavelengths get reflected too well. 5W+ green lasers are also amazingly expensive.

author: jkristof94
author_rank: Newbie
timestamp: May 08, 2015, 12:25:35 pm
content: As to my knowledge, LightScribe laser uses the same laser for the graphics as for the writing of data to CD/DVD/BD. In a BD drive it , which would be ~400nm.Also with that wavelength, it would be possible to reach great precision.

author: jkristof94
author_rank: Newbie
timestamp: May 08, 2015, 12:27:31 pm
content: And yes, a portable PCB factory in a briefcase would be awesome, and could be used for education purposes, and promoting the maker community in schools

author: madires
author_rank: Super Contributor
timestamp: May 08, 2015, 01:04:56 pm
content: Quote from: jkristof94 on May 07, 2015, 08:13:57 amBe patient! It takes some tries to get the whole process working well. And after that it's really simple. I'm DIYing my PCBs for over 20 years using the UV method. Mostly single-sided, some double-sided, SMT and no extras like soldermask or silkscreen. And keep your layouts simple for DIYing. For more complex projects I'd pay some PCB manufacturer for a professional made PCB with all the fancy stuffQuote from: jkristof94 on May 07, 2015, 08:13:57 amI don't think that this would work. What works fine for me is a laser printer with tracing paper. Some toners are better, some worse. Don't use eco or toner saver mode. To get nice solid black areas I spray the layout with CRC Solvent 50 (actually for removing labels, but it's less expensive than special toner sprays and works really well). The UV exposure time needs to be a little bit longer to compensate for the tracing paper.

author: DanielS
author_rank: Frequent Contributor
timestamp: May 08, 2015, 01:27:36 pm
content: Quote from: tggzzz on May 07, 2015, 02:53:31 pmThe last time I looked at optical disk lens systems, the laser's output first passes through a de-focusing lens to widen the beam and then through a focusing lens to bring it back into focus at the disk's recording media surface. On audio-CD, this was used to make the system more tolerant of surface scratches and it is also how DVD/BD can manage multi-layer. As long as the laser head assembly is in one piece, the laser light is not likely to ever be in focus beyond a few millimeters in front of the outer lens.

author: tggzzz
author_rank: Super Contributor
timestamp: May 08, 2015, 02:31:28 pm
content: Quote from: DanielS on May 08, 2015, 01:27:36 pmThat's almost certainly the case. Unfortunately not everybody use "high power" lasers in that way. It therefore behooves us to point out potential problems before they injure someone else.

author: Canobi
author_rank: Regular Contributor
timestamp: May 08, 2015, 02:52:13 pm
content: Amen to that madires, it does indeed take time to iron out the process. I too have tried all the verious etch resist techniques.Toner transfer:Wilkinson's high gloss photo paper @£0.79 per pack of 25 are the bomb. After much experimenting, the best turned out to be the least expensive, it also peels off like a dream while still hot, the only gloss left on the board is what's stuck to the traces. I found that soaking the boards to remove the paper is detrimental as the cooling makes the gloss become adhesive to copper and more rubbing is needed the get rid of it.Minium trace width I've managed using this paper .25 with no ground planes. Actually, toner transfer is pants when ground planes are present as there so much ink the paper has a tendency to slip around smearing everything.Positive/negative etch resist films:Both are good and I too use tracing paper (200gsm as it's heat stable at that thickness), though dust/particle control is always an issue at home when using the laminator.Interestingly, after some deeper research into artwork mediums I found out that tracing paper is actually the ideal. It diffuses pretty much all wavelengths appart from a small bandwidth ranging from 320-400nm,I'm surprised you need to give your exposures extra time, I barely ever tip 2:30:00, usually it's just 2 in my case.I will say one thing about final quality PCB though, it's not just about a crisp resist image, a lot has to be said about the etch solution used. Ideally you need to aim for an etch time of no more than 8-10 mins tops. Regardless of what resist your using, that's all its can do...resist. Eventually it'll be eaten away like everything else and long times in the bath equal fine traces vanishing and pock holes in ground planes and thicker traces.I'm interested in knowing more about the label remover wash and how that works but maybe by PM as I don't want to derail this rather interesting topic.@tggzzz Any idea how fine the beam is when it writing?I have a first donor scanner for a possible x axis motor and guide rail, I just used the glass bed for a briefcase exposure box build

author: tggzzz
author_rank: Super Contributor
timestamp: May 08, 2015, 06:41:20 pm
content: Quote from: Canobi on May 08, 2015, 02:52:13 pmWhen what beam is writing what? Start by looking at the dot sizes on a DVD etc.Consider very carefully that 5mW lasers are not eyesafe. Some easily available lasers are 250mW-1000mW -- so even if 99.5% of the power misses the eye, you might still be blinded.There used to be posters around various labs along the lines of "do not look into laser withremainingeye". Such labs took the possibilities of specular reflectionsveryseriously. And if you'd ever seen what a laser can do to an anaesthetised primate's face, then - after you had stopped vomiting - you would take laser safety very seriously.I don't care what you do to your eyes. I would care what you accidentally did to the eyes of someone walking past. (If I'm blinded then I will commit suicide, since I'm very deaf)

author: jkristof94
author_rank: Newbie
timestamp: May 10, 2015, 09:59:08 am
content: Guess I will just stick to laser printing then UV exposure since the BD thing got complicated. Although it might be doable. Maybe in the future when I will have time, I might do it, then post the results hereThank you for all of your contribution.

author: best man
author_rank: Newbie
timestamp: May 16, 2015, 09:12:14 am
content: mayby you can have a try of 3D Printers, there is a 3D Printers, can make the PCB boards for you.