Home brewing uV PCB's - Page 1
Forum section: electronics / general

author: Davy
author_rank: Regular Contributor
timestamp: May 08, 2020, 05:59:25 pm
content: I wonder if anyone has any 'tips n' tricks' when printing the uV mask? I have a Canon ip8750 inkjet and a Samsung ML3050 mono laser capable of 1200dpi, this does a good job using Press n' Peel toner transfer, I get decent results on various sized boards.... but they are never repeatable without touch up here and there.To get a decent image using uV I seem to need to double stack the image to get a decent black, be it tracing paper or OHP film on either printer, the inkjet on inkjet OHP does seem to be slightly better.I'd be grateful of any help, idea's or advice.Thanks, Dave.

author: Fred27
author_rank: Unknown
timestamp: May 08, 2020, 07:55:27 pm
content: My Canon MG5250 inkjet has a T-shirt printing mode that lays down loads of lovely thick black ink (also mirrored) on transparencies. Way better than a laser printer. No need to double up at all.

author: sleemanj
author_rank: Super Contributor
timestamp: May 08, 2020, 10:07:15 pm
content: Instead of double stack, try reducing the exposure time a lot.If you are using dry film you probably do not need nearly as much exposure as you think, just enough that you can develop it without damaging the image, then put the developed pcb under uv for a couple minutes to fully cure. In my led uv boxes, exposure time is 20-30 seconds with tracing paper.Of course play with your print settings, especially laser printer to make it get the most toner down you can (usually like toner density settings).

author: ogden
author_rank: Super Contributor
timestamp: May 08, 2020, 10:24:38 pm
content: Canon ip8750 inkjet is right tool for the job. Make sure you print BW using black pigment ink, set max possible ink density - select highest quality & resolution photo print mode. NEVER use "office grade" transparencies, look for those made for screen printing. If you have to double-stack your transparencies, you are doing something wrong.

author: xavier60
author_rank: Super Contributor
timestamp: May 08, 2020, 11:32:29 pm
content: I tried it years ago with a HP inkjet printer. One problem I noticed was that the residual solvent in the ink degrades the photo resist.

author: ogden
author_rank: Super Contributor
timestamp: May 08, 2020, 11:59:11 pm
content: Quote from: xavier60 on May 08, 2020, 11:32:29 pmTried drying your print for a while? Like hour or so? Years ago HP had dye inks. Those sux for transparencies - much more transparent compared to pigment ink

author: xavier60
author_rank: Super Contributor
timestamp: May 09, 2020, 12:38:03 am
content: Quote from: ogden on May 08, 2020, 11:59:11 pmYes, that helped. Part of the problem was that I was printing to paper so I needed a longer exposure time causing the ink to warm up driving out any remaining solvent residue. It would cause the resist to behave like it had been exposed.

author: Davy
author_rank: Regular Contributor
timestamp: May 09, 2020, 12:44:21 am
content: Ah, now then as ogden mentioned.... maybe I am using 'office graded stuff, I did order some micro porous OHP film from Amazon but won't be here until the 19th I'll see how that goes.I always thought Pigment ink would be better than dye, yet I always thought toner would be better than inkjet, pretty sure I proved myself wrong here. With the inkjet I had it set to high quality print, grey scale and turned the ink level sliders to the highest on manual print setting, yes in this mode the drying time is needed, it really does look right when it's still wet.As for the laser there is only a couple of settings, darkest text and 600 or 1200dpi print, obviously toner save mode is off. Thanks for all the input.Just hit me, I'm not using Canon inks and should that matter there's only one way to find out.... I really do wonder who makes their ink tanks.Dave

author: ogden
author_rank: Super Contributor
timestamp: May 09, 2020, 08:54:57 am
content: As you have both inkjet and laser - compare prints. Look at both against bright light (but not sun). Some years ago pigment inkjet would mostly win. Today it depends - you may get good, black transparency print out of laser as well.

author: Davy
author_rank: Regular Contributor
timestamp: May 09, 2020, 10:00:22 am
content: I really do think the inkjet is better, between colour and grey scale, I'm not sure, I've tried that many times I've confused myself, I need to try exposing rather than just looking.I have a sneaky feeling that Brother lasers may prove better with uV because they use plastic particles and require a higher fusing temperature.I started to make a LED uV diode A4 size panel, as per usual I just finished the panel with some 315 uV LEDS and the following day went to a local QRP rally, lo and behold a SK (silent key) sale of a Mega uV light box.... for a tenner I just couldn't refuse, now I have a choice tubes or LED's.The reason for switching to uV is that once a mask is made it can be reused rather than wasting a sheet or two of Press n' Peel on larger boards..... not yet even half way up the learning curve yet.Dave

author: ogden
author_rank: Super Contributor
timestamp: May 09, 2020, 10:29:11 am
content: Quote from: Davy on May 09, 2020, 10:00:22 amWhy don't you use your time building something that is not out there? UV nail lamps work well, cost little. Dunno about cheap LED "nail lamps", but I know that one with UV lamps work well. Take out two lamps on sides and consider it done. Thou it is not A4.

author: jpanhalt
author_rank: Super Contributor
timestamp: May 09, 2020, 10:33:03 am
content: Quote from: Davy on May 08, 2020, 05:59:25 pmI few years ago, the only PCB's I made were home brew with a photomask. Nothing compared for being reproducible and giving high resolution.My #1 choice was an inkjet. But as the frequency of making such PCB decreased, the cartidiges would dry out or plug. So I switched to a HP Laser jet 4. That does not use LED's for fixing the toner -- just high temp. I could use a dry-erase (aka white board) marker to make the pattern denser. That method will not work with LED-based fixing, as the toner deposits are too soft.On the rare occasion that I make one today, I just use an inexpensive Canon PIXMA printer with flow and dots/inch adjusted. A big variable with inkjet masks is not so much the printer but the medium on which you print.My favorite by far is a high-resolution, artist quality transparency. The specific brand is Pictorico Premium OHP Transparency Film. It has a microcrystalline* deposit on the print surface and will hold a very fine line without gaps. I have never used more than one layer of mask. I print mirror and put the ink surface against the sensitized plate.** There is no need to waste a whole sheet. Just cut the size you need and tape it to a standard size piece of paper so it feeds properly.*The deposit is so fine that the sheet looks transparent. You can only tell which side to print on by the fact it looks a little less shiny with reflected light. The full sheets are keyed so you don't need to do that. If you use a partial sheet be sure to mark the orientation. It is hard to tell.**I use a single-pane piece of glass as an overlay. Some people prefer a drop of water. If you use the water method, put the ink side up. Ordinary inkjet inks are not water proof. There is a difference, but it is small.EDIT: In my experience printing in color or black makes no difference. Most colors are just as effective at blocking near UV as is black. Even just yellow works. You do not need UVC or UVB. Near UVA will work just fine. In fact, ordinary fluorescent tubes that emit in the 390 nm to 405 nm range will work.

author: Davy
author_rank: Regular Contributor
timestamp: May 09, 2020, 02:36:43 pm
content: @jpanhaltThanks for that, I've found a UK source for Pictorico Premium OHP Transparency Film. I'll wait and get some stuff I ordered and try that first, if no good I'll give this a try.I've been looking at using 'Dry erase' to darken the toner, this all new to me.... I use 'paper save' when using Press n' Peel so non is wasted.Dave

author: jpanhalt
author_rank: Super Contributor
timestamp: May 09, 2020, 03:54:47 pm
content: Quote from: Davy on May 09, 2020, 02:36:43 pmThe dry erase method was simple. I used "Expo" brand. All I did was carefully paint over the entire LaserJet transparency. No scrubbing or back and forth. Let it dry, then wipe clean with soft tissue. Facial tissue (Kleenex) was best. It worked with all the LJ printers I had through my MPF4101 (which is a tank -- I can barely lift it). When I got my new laser printer (Brother), it no longer worked. The image is too soft. I tried a variety of things, including reheating the image. Result was a little better, but not up to what it was.Above are examples done with the LJ4. First is a painted image on bottom. Second is before (bottom) and after (top). It was great while it lasted, but not any more.John

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: May 10, 2020, 04:31:00 am
content: Quote from: jpanhalt on May 09, 2020, 10:33:03 amI've never heard the term "fixing" used for printers, that's a photographic process involving baths of wet chemicals and that definitely doesn't happen in any printer that fits on a desk.The laser or LEDs don't fix or fuse the toner, they simply develop the image on a drum coated in toner, both LED or laser printers use a fuser to melt the toner on to the paper; no difference there.Just pop the hood on a color LED printer if in doubt.https://youtu.be/_saDCwsB9Ww

author: jpanhalt
author_rank: Super Contributor
timestamp: May 10, 2020, 05:52:48 am
content: Quote from: Alex Eisenhut on May 10, 2020, 04:31:00 am"Fixing" is used in a lot of fields with different meanings than you propose. Fixing a car is one such meaning. In clinical laboratories, it is used to mean making something stick, as in making a smear of a bacteria from a colony stick to a slide, or preserving something, as in fixing a tissue formalin before processing. In the 1960's, large format "Xerox" prints were made in separate steps. After the toner was transferred to the paper, it was fixed with heat.Now you know the term has other meanings outside a dark room.

author: ogden
author_rank: Super Contributor
timestamp: May 10, 2020, 08:31:56 am
content: Quote from: jpanhalt on May 10, 2020, 05:52:48 amRight. Same happens today, in LED printers as well. Instead of laser, linear LED array "develops" image on the drum so toner sticks only where needed, then it is transferred to paper and finally fixed/melted using heat.QuoteThou you have to use termscorrectly. Your claim that LEDs instead of heat are used for fixing in LED printer, is wrong.

author: jpanhalt
author_rank: Super Contributor
timestamp: May 10, 2020, 11:31:25 am
content: Yes, I agree both printers use heat to fix toner to the print medium. I phrased what I was thinking very wrong. As described below, the distinction I should have made was the temperatures apparently used for fixing.The original toner was made from soot, as from burning rubber, and an inorganic fine powder (iron oxide?). I heard early on that HP used to burned pollen, but I have not been able to confirm that easily. Modern toners as used in Brother (and perhaps all others) is made from a plastic.What one can notice between the LJ4 & 4101 era machines and the LED machines is that media in the older machines comes out noticeably warmer than in the newer machines. I assume that means a lower temperature may be used for plastic-based toner than in the earlier machines. (I am not sure what toner is used in the MFP4101 printer series, but media does come out warmer.) I will just refer to the two types as "high-temp" and "low-temp" as labels that are not necessarily accurate.When testing the dry erase modification, toner deposits in the high-temp printers are quite stable. If one looks at them microscopically, an untreated pad looks like this:A treated pad looks like this:An inkjet pad has larger dots than the untreated pad, but they flow together (image available, but not shown for brevity). Low-temp dots had more of a fried egg appearance. Most important, after treating with Expo dry erase, they seemed to soften and be removed from the backing. Expo is formulated (MSDS) with diacetone alcohol. It is not a particularly strong solvent, but it has very little odor to most people and is safe.I played a little with other formulas, including water color pigments with weaker solvents/surfactants, but since I also needed an inexpensive color printer, I got the Canon PIXMA and did not pursue what was to me a dead horse. If someone were to pursue it, I would recommend they use a pigment, not a dye, in water or water with a small amount of surfactant/binder.

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: May 11, 2020, 01:52:13 pm
content: It's not called fixing in a laser/LED printer. It's fusing. Why confuse the issue? Why make up terms that other people will either never find and be lost, or worse, pick up and propagate?Now you know what's it's supposed to be called.PS: It's not the 1960s anymore.Find me a "fixer unit" in a laser printer and I'll agree with you.https://en.wikipedia.org/wiki/Laser_printingctrl-f "fix""phrase not found"https://support.brother.ca/app/answers/detail/a_id/115512/~/how-can-i-check-the-remaining-life-of-the-fuser-unit%3Fhttps://www.brother.ca/en/search?query=fixeretc

author: free_electron
author_rank: Super Contributor
timestamp: May 11, 2020, 03:51:37 pm
content: i made many boards using film , overhead transparencies, and photoimageable board.here is what i found- inkjet works better than laser. The problem with laser is the warping of the image due to heat. The foil becomes irregular. Other issues are non linearity in the drum. this may be solved these days , but back in the 90's the lasers did not really have perfectly round drums. if you had a long connector like 80 pins on a 2.54mm pitch : By the time you were at the last pin you were half pitch offset ... Inkjets did not have that issue- get a black only inkjet. I had an original HP Deskjet +. Black was BLACK in those days ! none of that emulated fudy duddy ladida they spit out these days.- Get a non absorbent type of paper. You do not want the fibers in the paper to 'fuzz up' the image produced by the printer. The best paper i found was that smelly paper used for wet copiers. The ink would pearl up and not get absorbed by the paper. The paper would also not 'wrinkle' when it got wet.(it was designed for wet processing). These days i would suggest using photo paper ..you can image through such paper , but you need long exposure time.I used an intermediate step : Agfa Litex film. This is a professional film used for press. This is a NEGATIVE film.(it inverts the image)Using the same Uv exposure unit i would 'flash' my printed artwork onto the film. Just making the UV tubes blink a couple of times is enough exposure. The film is very forgiving..After developing using black white photo developer and fixing you have a true 'artwork film' with the same optical qualities used in real PCB production. Transparent is clear like glass and not that semi fuzzy transparency that overhead films have.For positive resist i would simpy 'revert' the film back onto a second foil.Best positive image ready to use pcb board : bungard. hands down. and Seno developer . This is pure sodium metasilicate . Sodium hydroxide also works but that is caustic. Sodium hydroxide absorbs co2 from atmosphere and goes 'bad' very fast. Metasilicate has a longer shelf life when mixed.Using the Agfa film and those Bungard pre-sensitized boards i could easily home etch 6 mil track. I would buy the thin boards ( 0.8mm) because they have 1/2 of copper.As for etchant : i always used Sodium Persulfate. I hate that brown yuck stuff that stains everything.Later i switched to negative film as that yields far better results than positive resist. The positive resist DISSOLVES by exposure to light. So , even after developing : the remaining material , exposed to light becomes weak when exposed to light. So if your film has light 'leakage' you are damaging the resist.Negative resist HARDENS when exposed to light. so you wash a way the soft stuff.. what remains on the board is hard. further light exposure does nothing ( if anything it hardens it more...)good video showing the process :

author: Davy
author_rank: Regular Contributor
timestamp: May 11, 2020, 05:53:33 pm
content: @free_electron"..... get a black only inkjet. I had an original HP Deskjet +. Black was BLACK in those days ! none of that emulated fudy duddy ladida they spit out these days....."I've been reading about Agfa Litex film, some useful videos about, thanks for the link.I know what you mean, my friend had windows 95 and an old Canon inkjet, at the time I had the ip4000 I think it was, his text would put mine to shame. I don't know what ink it was but he filled his own tanks, his inks appeared nice n' thick made mine look watery.I just got some Micro porus film, just tried a print with greyscale and brightness and contrast fully 'up', the setting was fine quality photo paper... the print being far better than anything I managed to date being black and even all over. I've a feeling that this may will do the trick.I need to try the other paper settings, I can't see a transparency setting, there's a matt photo paper and fine art setting, it does seem limited if you ask me, 'other photo paper setting' offers no explanation what paper that is. I'm stumped here so I'm going to have to try them..... any suggestions?So any old media for this game is a big no, no that's for sure.Dave

author: ogden
author_rank: Super Contributor
timestamp: May 11, 2020, 06:31:32 pm
content: Quote from: Davy on May 11, 2020, 05:53:33 pmGeneric transparencies can't take ink much, so it does not sound like good mode. Better look for highest resolution, hi-quality glossy photo print. On Epson it would be color:grayscale, paper: Premium Glossy, quality: more settings->highest_quality_you_can_set.