solder mask - UV solder mask procedure  - Page 1
Forum section: electronics / beginners

author: r00n
author_rank: Contributor
timestamp: November 28, 2023, 12:42:43 am
content: Hi. Lovely Day for PCBs.I am trying to do my first solder mask ---> I have had about 20 failed attempts and I am down to my last bit in the tube. It is green of course. All the information I have on masking obtained from you-tube videos so I thought if I documented my recipe you may be able to determine where I am failing.Here goes:1. photocopy the mask in duplicate onto 2 pieces of what we used to call Overhead transparencies, the plastic sheets that lecturers used. I tape the two sheets together being careful to line up the black masks to block out more UV.2. sand copper with a bit of really light grade wet and dry paper. wash the copper with isopropanol.3. put enough UV solder mask down on the copper to cover the board and place another transparent sheet over the top. Use a credit card to squidge out the UV solder mask with an even covering over the copper.4. place my duplicated photocopy mask over the top plastic lining up with the solder pads.5. place under UV light for about 4 minutes. (I completed a test exposing the UV solder mask to UV for varying times incrementing in 30 secs. For 7 minutes the porridge was too hot, and 2 minutes it was too cold)6. remove the plastic masks and sheet and wash the pads with a small amount of alcohol and a paint brush being gentle.should be ready to solder then...................................but no.The error occurs during removal of the mask and plastic sheet. The mask sticks to the OHP transparency and not the copper. Not all - but most. For the UV mask left on the copper, the pads are still moist enough to clean off.Any tips you have would be well received. Or perhaps there is a better method altogether?

author: thm_w
author_rank: Super Contributor
timestamp: November 28, 2023, 12:54:13 am
content: https://learn.adafruit.com/how-to-solder-mask-pcbs/applying-resinI don't think the transparency print needs to be duplicated?What UV light is used?Photos?

author: coppercone2
author_rank: Super Contributor
timestamp: November 28, 2023, 01:36:15 am
content: printing on transparancies is a little dodgy. I put it this way, I put a piece of kapton tape on a PCB during exposure to keep the transparency on. The area under the kapton tape was nearly perfect but the traces were a bit like swiss cheese for the same exposure time. Set with maximum darkness on the printer.But I did do a long etch, that is.. no polygon on top. So it was in the solution for a lot longer then necessary. If I put polygon I could have drastically reduced etch time and there would be no problem on the ground plane.my result was acceptable, but I can see it being improved.i use presensitized boards though.I heard people using some kind of translucent tracing paper with better results then transparencies. BTW transparencies are not so transparent to UV anyway. For instance a clear acrylic sheet, put under the UV light, you can see strong attenuation. SO paper is not that much worse, apparently. You do use glass to press it down on the pCB?

author: r00n
author_rank: Contributor
timestamp: November 28, 2023, 01:53:58 am
content: thm_w - thanks for the link. im not certain on the light that i am using but it is strong enough to cure the resin. After looking and reading the link I tried a shorter exposure time of 30 seconds and a thinner spread of resin. The resin cured and the mask didnt - which is exactly what is required, however it was stuck to the transparent film and not the copper.Quote from: coppercone2 on November 28, 2023, 01:36:15 amCoppercone2, I'm certain that the transparencies are the fault. If you have any more info on that tracing paper that would be useful info. not using glass but will give that a tryedit - maybe i could just paint it on with a brush and leave the solder pads

author: shapirus
author_rank: Super Contributor
timestamp: November 28, 2023, 02:10:51 am
content: Quote from: thm_w on November 28, 2023, 12:54:13 amI guess it depends on the printer, but in my case (for etching with photoresist, not for solder mask, but the reasoning is I think the same) I absolutely had to print it twice, normal + mirror, then, after drying the ink (I'm using an ink jet epson L805) put the two together, ink sides facing each other, align, fix them together using sticky tape, and it's good to go.With a single print it was a consistent failure because of very low contrast: black areas were half-opaque with multiple small transparent dots without any ink in them, so it was impossible to expose uncovered areas enough and not expose the covered ones at the same time. However, with two prints combined it became a consistent success (the biggest problem now becoming the reliable application of the photoresist film onto the board), and with a very decent resolution, too: 10/10 is not a problem at all, and, judging by how well the copper text with component reference markings serving as poor man's silk screen is etched, even thinner traces and clearances should be possible.Can also print twice on the same surface for the same effect (after thoroughly drying the ink which I do in a ventilated oven at 50 degrees C), but, even though the printer does a very good job at consistently aligning the image (or the sheet?) to print in exactly the same place, second printing spoils thin white (transparent) lines, which get even thinner, because the already printed areas can't soak enough of the new ink and it spreads a little outside of where it's supposed to stay. So I abandoned it and kept using two transparencies, at least where traces are thin and dense.Firm pressing (with some glass) of the transparency against the board is vital, too.I wonder what can go wrong using the same technique for solder mask. I've never tried it, and am now tempted to try it too.

author: shapirus
author_rank: Super Contributor
timestamp: November 28, 2023, 02:18:49 am
content: Quote from: r00n on November 28, 2023, 01:53:58 amIf it cures properly, then it either lacks adhesion to copper, or adhesion to the film is too strong (or both). For the former, you want to make sure that copper is absolutely free of any grease residue. IPA doesn't do a good job of removing it. Acetone or purified gasoline (light fractions of oil refining, usually sold as solvents), whatever is more available, will do it. Need to make sure that the stuff doesn't leave any residue after evaporating. Of course don't touch the copper after cleaning.For the unwanted adhesion to the film, maybe try a different material? For example, polyethylene film (used as food wrap etc). PE is well known for its inability to be glued with (most?) glues, which in this case is an advantage.

author: coppercone2
author_rank: Super Contributor
timestamp: November 28, 2023, 02:29:36 am
content: how to do it1) set printer to maximum density in advanced settings (mine goes to +6)2) set the quality to max (1200HQ on mine)3) set the whatever setting to super-something (it has options like 2x, 4x, and super). Its like alliasingI think you set it to transparency mode too.Then it does better. I got 0.5mm traces OK on mine (MSOP package) on yesterdays etch.I do 4 min with my 750mA 16V single die UV diode at a distance of like 12cmI have some film. Its old. I have not tried it. Maybe I can try for you because i got a blank copper (failed exposure). I have been meaning to try the film I Have on something. Wow. I got super derailed from my etching projects!vacuum the inside of your printer and wipe the rollers and whatever you can too.

author: abeyer
author_rank: Frequent Contributor
timestamp: November 28, 2023, 03:16:53 am
content: If your film on the first layer against the resin is the printable stuff, make sure you'renotputting the printable side down (and that it's not double-side printable), too. It's treated to make ink/toner adhere, so likely could do the same for resin.

author: coppercone2
author_rank: Super Contributor
timestamp: November 28, 2023, 03:33:03 am
content: I put my printed side on the board so there is less reflection. If its flat on it then its flat on it.

author: sleemanj
author_rank: Super Contributor
timestamp: November 28, 2023, 04:14:07 am
content: See this post I made some years back with various DIY soldermask info...https://www.eevblog.com/forum/beginners/diy-solder-mask/msg920711/#msg920711It has been a long while since I have used it, but as I recall you need the right type of plastic to ensure it doesn't bond to the plastic, and if you are not curing down to the PCB then you are not curing long enough (or you have it on too thick).In short, the ink stuff is a total pig to work with at a DIY level. Best if I recall to thin it (withIsoamyl Acetate I believe, good luck finding it), spray it, bake it (don't remember temperature), then expose it, and wash it.

author: coppercone2
author_rank: Super Contributor
timestamp: November 28, 2023, 04:20:56 am
content: oh haha i just realized this thread is about solder maskokmy experiance with it is shit. paper would be worse. i thought it was for the photoresist for some reason, because i have been working on doing this board for like 3 weeksmy experiance is that I tried it once and it pissed me off because you really need a clean board to do it on. if you have any solder on it or bumps it really gets bad. i did not want to super clean the board i was repairing. i got solder mask on it but it looks like someone hit it with a painters roller brush. but its enough to shield the mainboard of the rf generator i was repairing from leaked battery damage. i ended up using a paint brushI think mine was sticking to the acrylic too. I thought maybe a solution might be to put a thin layer of wax on it. I saw some guy use like a roller to push it around but for me it was like poking a turd with a stick. But I had some components and stuff on the PCB still, I made like a patchwerk cutout to put over most of the traces to try to squeeze it aroundmy theory on doing this right1) you need some kind of special roller for that goo shit, or just experiance rolling goo. I had some art store one. Applying even films of goo is hard.2) some kind of release agent for the filmi almost bought more goo but fuck i see you can buy a mask Ima try the mask I dont want to deal with that mother fucking goo anymore holy shit that pissed me off so hard its like trying to smear shit evenly into a picaso. lets call it tomato paste. serenity now serenity nowbought a film mask.ill let you know how that goes in some amount of time. I will polish that old PCB up with neverdull to get the tarnish off, apply the photoresist mask, etch it, and then if it works try the photoresist mask. if for some ungodly reason the silk dry film is worse then the goo, I might buy another tube of goo. but i would be happy to never see the goo again.

author: coppercone2
author_rank: Super Contributor
timestamp: November 28, 2023, 04:42:42 am
content: is anyone here a professional silk screen goo roller? i wanna know how that is done in the factory. its one of those processes probobly where there is fine details and extremely neutrotic attention to tool choice. or im just fuckin incapable. or there is a old master doing that stuff with a wooden spoon like in a pizzeria. some how those guys get gauge block level of sauce flatness on a pizza using a 1/3 cup spoon. the lighting in those places always sucks so you know hes seeing in monochromatic from the malfunctioning flourescentsthe other idea I got is to get another sheet of transparancy, cut a square out of it, put it on the PCB, and then run a oiled blade over it to smooth it out, like a long razor, or a starrett level

author: sleemanj
author_rank: Super Contributor
timestamp: November 28, 2023, 05:57:39 am
content: For soldermask they use a silkscreen process to apply the ink.Or it will be spray appliedFor the silkscreen text layer they can use a silkscreen and imaging as with soldermask, but also they can use direct printing these days like a massive inkjet.

author: sleemanj
author_rank: Super Contributor
timestamp: November 28, 2023, 06:05:22 am
content: This is a good overview from PCBWay on the Soldermask process...Clean board, apply the ink with a silkscreen/spray, oven dry, expose with mask, wash in alkaline, oven bake. As above the drying temperature is somewhat critical, and low, and ink dependant.

author: coppercone2
author_rank: Super Contributor
timestamp: November 28, 2023, 06:15:11 am
content: how do you spray that goo like a billion psi??

author: sleemanj
author_rank: Super Contributor
timestamp: November 28, 2023, 06:19:41 am
content: I don't know if it is done in factory but supposedly the goo can be thinned with "Banana Oil", which is Isoamyl Acetate. Maybe other solvents.

author: sleemanj
author_rank: Super Contributor
timestamp: November 28, 2023, 06:23:49 am
content: Thought I had written about this before, a mere decade ago...https://www.eevblog.com/forum/eda/diy-problems-with-an-enormous-508mm-board/msg396222/#msg396222Quote from: Kerry Koppert

author: coppercone2
author_rank: Super Contributor
timestamp: November 28, 2023, 06:32:13 am
content: oh I have some too, that replaced MEK as paint stripper in home depotwhy do I suspect total shenanigans with dilution of soldermask using solvents? I diluted epoxy before, it dont' work too good.

author: Jwillis
author_rank: Super Contributor
timestamp: November 29, 2023, 07:19:47 am
content: First off. Don't try this in broad daylight. That will make the job harder. Set up a room that you can make dark and purchase a red or yellow LED bulb. I prefer yellow because it makes it easier for me to see. Incandescent bulbs will work as well. All work is done in the "Dark Room". I use UV activated mask form Aliexpress Vendor.I don't use roller because the crap goes on to thick. A silk screen and squeegee work the best for me. You may have better luck with the roller.Put a thin layer of mask on the PCB and Dry using a heat gun or other source. Dry at around 160oC. That's an arbitrary temperature, just don't burn it. It must be completely dry before the transparency is attached.I use double transparencies to achieve maximum shielding from the UV. One transparency allows to much leakage. Expose with UV light. Time depends on the light source and intensity. I use UV LED strips set up side by side on an 8 x 12 inch Aluminum plate under a sheet of glass. Usually it takes about 6 to 10 minutes at high intensity. Let the exposed PCB rest in the dark for 30 minutes. Wash with the appropriate solvent. This is tricky because the solvent I use is from a silk screen vendor on Aliexpress and I can't get an English translation of the label. But it smells like Methyl Ethyl Ketone. I won't guarantee that this is without some possible health risk. I haven't grown any new appendages as of yet but do use caution and good ventilation.Silk screening takes practice with lots of failures until you get it right. It makes a really nice job once the procedure is perfected. But it's time consuming and messy. So being set up with all the necessary supplies and equipment before you begin makes the task much smoother. Use silks of 300 count or more for lettering. To low and it doesn't look nice.Regards

author: coppercone2
author_rank: Super Contributor
timestamp: November 29, 2023, 11:10:00 am
content: lol just general ranting about PCB... my board.. I drilled all the holes, mounted all the PITA smt parts, etc. Then I decided ima just test the regulators before i power the whole thing up with a jumperOk regs dont work. hmm. not minimum load problem..turns out I unmirroed the mirrored part I randomly chose to check as a sanity test and I mirrored the bottom instead of the top so my PCB was backwards! so the part orientation was wrong but it made my design seem right.at least rev #2 I will wait till I get the silkscreen film, and put polygon on top, for more even etching, reduce UV exposure time too.maybe I will get a beautiful board this time, or at least the correct orientation.i made a orange light bar powered by 2x d-cell for the dark room work BTW. glued a bunch of orange power LED modules to a aluminum square piece i cut into and made a diffuser for it. I set it up standing in the corner, its enough towork fromalso for alignment, this time I will buy a 1/16 sheet of acrylic and use it to line up the top and bottom layers. I lined them up perfectly on top of each other but when I etched the board i got more then a mm of offset! i think its because the thickness of the board ? like it was dead on...... :'(

author: shapirus
author_rank: Super Contributor
timestamp: November 29, 2023, 11:19:41 am
content: Quote from: coppercone2 on November 29, 2023, 11:10:00 amPlease elaborate on these.I've been working with negative photoresist with a regular 9W 3000K bulb (in a meter or so from it) and it seems, only seems, not to create any negative impact, but I guess I might want to try something that's considered better.Quote from: coppercone2 on November 29, 2023, 11:10:00 amThe board must have slipped when you flipped it to expose the other side. I've done 2mm thick boards with no offset between the sides, but it does require attention to how you grab the board and the transparencies that cover it from both sides to flip it.Of course the transparencies must be aligned and reliably fixed against each other with e.g. some scotch tape before inserting the board between them.

author: Solder_Junkie
author_rank: Frequent Contributor
timestamp: November 29, 2023, 12:26:31 pm
content: For the past 47 years, I have been making my own PCBs. Initially hand drawn with a Dalo pen and then using cheap Chinese laser toner heat transfer paper. I spray the board after assembly with printed circuit lacquer (conformal coating), it doesn’t look as nice as solder mask, but it protects the copper from tarnishing.While I like the idea of having a board ready to solder in an hour or so, recently I bit the bullet and used JLCPCB. OK, I have to wait a couple of weeks for the board to arrive, but zero mess and the cost is minimal.Perhaps not the answer for those who like to make their own boards, but I’m a convert.SJ

author: coppercone2
author_rank: Super Contributor
timestamp: November 29, 2023, 01:01:12 pm
content: Quote from: shapirus on November 29, 2023, 11:19:41 amI don' know. I aligned it on a light table. I used 3 pieces of aluminum tape to secure it. I cut a hole on one side and used kapton tape to stick it to the PCB so it does not move when I flip it. I put a 1/4 inch thick piece of glass on top for the exposure too. no idea how it moved. it was aligned enoguh so that the 0.3mm holes all over the PCB are all shining light through (drill marks)

author: Jwillis
author_rank: Super Contributor
timestamp: November 29, 2023, 11:10:45 pm
content: Quote from: shapirus on November 29, 2023, 11:19:41 amThe orange , red or yellow light is for work purpose and not to activate the mask or photo resist. Light on the low side of the spectrum won't activate the the UV materials while your working. Broad spectrum lighting will. Also the photo resist film will begin activation as soon it is exposed to broad spectrum light. I lost entire rolls because of this. Now I only unseal rolls in the darkroom under yellow or red light. If your photoresist roll has turned from a pale blue to darker blue or purple, Don't expect good adhesion or etching.If you are using emulsions for making silk screen prints, the emulsion must be used within a month after the activator powder is added.To align the transparencies ,I drill a couple holes to insert pins through the board . That holds the transparencies from misalignment. You can use existing drill points in the circuit art if you like.

author: shapirus
author_rank: Super Contributor
timestamp: November 30, 2023, 12:05:18 am
content: Quote from: Jwillis on November 29, 2023, 11:10:45 pmYeah, I kind of know that, was just wondering whether there were some specific LEDs that could be recommended, or, rather, what configuration would be more convenient, from experience, than others. I've just searched aliexpress for "orange led light", and it did show a few results, but of those potentially suitable were only some 600nm (which is yellow/orange) LED strips. I guess I'll search for some higher power LEDs of this part of the spectrum, maybe even our local stores have something. Strips could work just as well though.

author: coppercone2
author_rank: Super Contributor
timestamp: November 30, 2023, 02:52:18 am
content: yeah i don't renember, I probobly got it on digikey

author: Jwillis
author_rank: Super Contributor
timestamp: November 30, 2023, 06:45:50 am
content: Quote from: shapirus on November 30, 2023, 12:05:18 amI just got these for work lights.There are orange ones from other manufacturers.

author: shapirus
author_rank: Super Contributor
timestamp: November 30, 2023, 10:45:47 am
content: Quote from: Jwillis on November 30, 2023, 06:45:50 amThis is an interesting topic, which isn't as simple as it seemsSo I have just used some kapton tape to cover a regular (warm) white 3000K LED bulb. Nice yellow light as seen by the eye. Then I looked at it through a spectroscope. Red, orange, yellow, all right. Then, the green part of the spectrum is all preserved. Blue is all blocked, but after blue there is quite visible purple, which isn't blocked, and too bad I can't see UV, maybe it's all there as well.Maybe the paint used in these party/anti-insect bulbs works differently. Or maybe not.I've also ordered some supposedly monochrome "600-605 nm" LEDs from aliexpress, it will be interesting to see how really monochrome they are.

author: coppercone2
author_rank: Super Contributor
timestamp: November 30, 2023, 10:11:07 pm
content: kapton tape is a massive uv blocker. i put kapton tape on my PCB to hold the film on during exposure in a spot, its the best looking etch on the whole board (0 holes). blocks it way better then the toner. If you use clear tape, basically there is very little attenuation, but kapton is a strait up mask.i was actually thinking to get a CNC cutter to just cut out kapton so you can peel off for a UV mask instead of printing it for super high quality exposure with no leakage.if you need some power distribution board that is simple, using a exacto blade over kapton tape should give you a superb mask. Like print the design on normal paper, stick kapton sheet over the board with tape, then put the paper on top, cut with a blade, peel what you don't want and you are good to go with no ink. Like a small board for a filter, or rectifier, power distribution for lugs (welding backbone board), etc.

author: coppercone2
author_rank: Super Contributor
timestamp: December 01, 2023, 09:19:14 am
content: made another one, slightly modified with the extra filler on top. Still got some porosity, I can see light through the PCB in a patch. It has to do with the bubble impingement in the etcher, and probobly overexposure, it still came out good where the kapton was.I will try another etch, this time with a 1 min 30 sec exposure per side, this attempt was at 3:30. A few patches came out really nice though. Its getting close.

author: coppercone2
author_rank: Super Contributor
timestamp: December 01, 2023, 09:52:38 am
content: damn 30 seconds was actually really nice, 1 minute is over exposed.. I think 15 sec might be good.i thought no way it could be that fast. with the florescent light it was like 15 min.its like i just entered the semi conductor age or something. i was nuking those boards, for real. its like choosing a 1 meg resistor instead of a 10k. double digit improvement magnitude.

author: shapirus
author_rank: Super Contributor
timestamp: December 01, 2023, 04:15:19 pm
content: Quote from: coppercone2 on December 01, 2023, 09:52:38 amSo is that for etching or for solder mask? Have you had success with the latter, which this thread started with in the first place?p.s. yes a proper UV light makes wonders. I use one of these, it's pretty powerful stuff:https://www.aliexpress.com/item/1005004276628499.htmlp.p.s. sorry, I have just realized that you aren't the OP. d'oh. anyway, this thread seems to be hijacked by copper etchers now!

author: coppercone2
author_rank: Super Contributor
timestamp: December 01, 2023, 05:38:32 pm
content: It should be a very similar process. It’s almost the same material.

author: coppercone2
author_rank: Super Contributor
timestamp: December 02, 2023, 07:54:54 am
content: how do you apply silk screen photo resist film? can it be done with sticky tape and a roller or fingers? I dont ever wanna buy a laminator.also, instead of a iron, can you sandwich between two plates and bake it? the clothing iron is ridiculous. well maybe. I have some old school mini travel iron that is begging for P_IDand for on topic, this is a dying art. you need people to etch and then they get interested in silk screen. also, tis just gonna fall off the front page and die

author: shapirus
author_rank: Super Contributor
timestamp: December 02, 2023, 11:11:51 am
content: Quote from: coppercone2 on December 02, 2023, 07:54:54 amI haven't done any silk screens or solder resist (yet).But here's what I do to apply the dry film photo resist for the etching step. I guess the steps should be similar to dry solder mask film as well (not the liquid one), however, I don't really understand how the latter works when the board is already etched and there is height difference between tracks and clearances. It has to be thick and supple enough to fill all the gaps. Not sure. I know that people use it, but liquid solder mask sounds more natural to me.Anyway, for the etching film:1) Thouroughly degrease the copper surface(s). Sanding might be required when it's oxidated or very rough; I found that it works without sanding just as well, if not better, for me.2) Spray a fine mist of water (they say deionized works best as it doesn't react with the photo resist material; I used boiled and cooled down water, it worked) onto the board's surface.3) Peel off a small portion of the photo resist's lower protection layer, align it with the board and begin applying it. The water on the surface helps to avoid bubbles. The idea is to remove the protection film not all at once, but gradually: use a squeege to lay it nice and flat and squeeze all the water out, and, as you go, peel off the protection layer just where the squeege is going to move to next.4) Once done and you're satisfied (meaning no air or water filled bubbles), use a hard, e.g., polyurethane, roller to press the film firmly.5) Well, the clothing iron. It's important to use a temperature-controlled one (use your DMM's thermocouple to know which setting gives the required temperature). Generally about 70 deg.C is recommended, and going above ~100 is not. I do somewhere in between. The idea here, I guess, is that you want the temperature at which the photo resist material is just about to begin to melt: that's when it can adhere well to the copper surface without losing its shape, for the lack of a better word. This is to be determined experimentally. I have also found that overheated film still works. After all, you need only a miniscule amount of it on the surface to prevent contact with the etching agent later, so it's not super critical. Fully removing the unexposed areas during the development stage is much, much more important.I put a piece of what is known as "baking pergament" here (thin semi-translucent paper with a somewhat slick surface that withstands cooking oven temperatures) between the iron and the resist film to prevent any chance of it sticking to the iron.6) While the board is still hot, use the hard roller again.7) Since the iron's primary purpose is to heat up the film, less so pressing it onto the surface (you can't press it firmly enough with the iron anyway -- it's where laminators are helpful), I guess it should be possible to heat it up using hot air, e.g. with a rework soldering fan (as long as the board isn't too large), and then use a roller to press it to the board. I haven't tried this, but I think I will, because it'll be easier to control the temperature this way.p.s. for etching, I use the hydrogen peroxide + citric acid method with great success: the components aren't toxic and don't leave stains (unlike ferric chloride), are readily available at any time and work very well. Proportions: dissolve 30+ g of dry citric acid in 100 ml of 3% H2O2 solution found in pharmacies (maybe not in all countries though -- for example, in Canada pharmacies are a miserable joke, so it can be a "prescription only" substance), add 5+ g of NaCl. Takes a while to fully dissolve, but it works fine, including at room temperature, however heating it speeds up the etching process.

author: coppercone2
author_rank: Super Contributor
timestamp: December 02, 2023, 04:58:24 pm
content: I gave the 30 second exposure a etch, there is still some porosity in a few spots, but some areas look good (like the tape). I think there need to be a even shorter exposure time (it looks like near the middle is more damaged) then 30 seconds, and I also think the bubbles need regulation.The little air compressor I think is producing too many bubbles and its damaging the coating. I need to reduce that, but out of PCB for now. This one will do because its really good compared to the other one. silk screen might be in here in 2 weeks

author: tooki
author_rank: Super Contributor
timestamp: December 02, 2023, 05:49:11 pm
content: Quote from: r00n on November 28, 2023, 12:42:43 amThey’re still called overhead transparencies, because overhead projectors are still in use in education. You can buy brand new overhead projectors today, and obviously the supplies too, both transparencies and OHP pens. Definitely not as common as they used to be, but hardly rare.Quote from: coppercone2 on November 28, 2023, 01:36:15 amTransparencies were a very common thing to use back in the day, when magazines came with PCB layouts for you to photocopy onto a transparency and then expose sensitized PCB stock. Transparencies may attenuate UV, but certainly not by enough to thwart the process.Not sure why you brought up acrylic; transparencies aren’t made of acrylic. The ones for handwriting are cellulose acetate (especially in the olden days) or polypropylene, the ones for laser are polyester with a toner-adhering coating. The ones for inkjet are also polyester, but with a different coating to absorb the ink so it can actually dry without pooling up.

author: coppercone2
author_rank: Super Contributor
timestamp: December 02, 2023, 06:42:42 pm
content: WHATEVER they are, the point is that I read some where a while back that someone was saying some kinda tracing paper was doing WAY better then transparancies for making PCB. Possibly on hackaday.ie..Lindsay Wilson says:February 25, 2013 at 12:53 pmAlthough this is a clever hack, I have to admit I don’t really see the point. With all the boards I do, I print two copies (on to TRACING paper – in my experience, transparency film doesn’t hold as much toner) and then align and tape them together. Gives a nice dense fill, even on ground planes (and even though my printer says the toner is below 1% and should be replaced!).I’ve found that genuine HP toner is denser than the no-name compatible stuff, so it’s probably best splashing out for the real toner.

author: Jwillis
author_rank: Super Contributor
timestamp: December 03, 2023, 12:17:59 am
content: Quote from: coppercone2 on December 02, 2023, 06:42:42 pmThis is what I have experience when dealing with specific papers to use for toner transfer. Straight printer paper won't release the toner easily. Some photo papers work some don't . A lot of trial and error. HP glossy photo paper works well. By far the best results I got was using the backing paper for vinyl adhesive signs. And I get it free from a local sign maker which is a plus.I modified a cheap laminator to except the thicker PCB board. It will heat both the top and bottom with good pressure. When laminating the photo resist place the PCB in between two sheets of paper to prevent direct contact to the laminator rollers. Direct contact will cause the photo resist to stick to the rollers.Best results are made if the copper clad is sanded lightly with 150 grit sand paper. A 150 grit sanding sponge works the best. Clean sanded surface well with alcohol. Apply the photo resist and roll out the bubbles as best as you can. Remaining bubbles can be popped with a sharp pin and rolled out.A fair bit of pressure on the surface of the PCB is essential for proper adhesion. The PCB and photo resist must reach at least 90oC but no more than 110oC to adhere to the copper.I use 93oC (200F) . Let cool in a dark area or enclosure.I have since chosen to use liquid UV activated paint applied with a silk screen. I can now skip all extra processes involved with toner or adhesive photo resist. Complete, well made, silk screen kits and supplies can be bought at Aliexpress at a fairly reasonable prices.Once you figure it out it's really easy.regards

author: tooki
author_rank: Super Contributor
timestamp: December 03, 2023, 04:35:34 pm
content: Quote from: coppercone2 on December 02, 2023, 06:42:42 pmThat articleis referring to TONER TRANSFER, not UV exposure!!Completely different process with no bearing on this.

author: coppercone2
author_rank: Super Contributor
timestamp: December 03, 2023, 06:31:34 pm
content: they talk about transparencies and toner which is what I use in laser printing for photo etching. Also, its not the only one, I just cant' find it. but its better not to post information that can be misinterpreted then to post snippets because I am just gonna end up in an argument because of 'context' and assumptions that some old ass forum post on a different forum MUST be about toner transfer because it HAS to be on topic. but I am sure your contextual analysis of what the hell the meaning of that is vs my memory has to be accurate because

author: tooki
author_rank: Super Contributor
timestamp: December 04, 2023, 08:02:35 am
content: Quote from: coppercone2 on December 03, 2023, 06:31:34 pmI wasn’t assuming anything. The post you linked is TAGGED “toner transfer”.Toner transfer doesn’t involve exposing anything to UV, so it’s completely irrelevant. And as I said, there is ample evidence disproving your claim, since toner-based transparency copying for the purposes of UV-exposing sensitized PCBs was a significant method used for small-scale PCB production in the past.

author: coppercone2
author_rank: Super Contributor
timestamp: December 04, 2023, 05:25:16 pm
content: There is nothing because I did not find whatever I read that said a form of tracing paper is superior for uv exposure then transparency sheet for photoresist exposure. That post may or may not be related to the post I am looking for. You can also use toner for uv. Not everyone owns a ink jet.

author: tooki
author_rank: Super Contributor
timestamp: December 04, 2023, 08:16:19 pm
content: Quote from: coppercone2 on December 04, 2023, 05:25:16 pmWhat the hell, man? Stop wasting my and others’ time with comments that are unsubstantiated. If you can’t find a source, then say so, rather than providing an irrelevant one!

author: sleemanj
author_rank: Super Contributor
timestamp: December 05, 2023, 06:01:55 am
content: Tracing paper works fine for UV exposure, it's sufficiently transparent to UV in my experience.You want fairly thick stuff though as thin tracing paper in a laser printer will wrinkle, 100-110 gsm is goodIs it as god as OHP transparencies, no idea.

author: coppercone2
author_rank: Super Contributor
timestamp: December 05, 2023, 09:26:18 am
content: see its worth while to post this without the sauce police interfering because someone actually delivered a snipet of relevant informationlike the post above, this one said that it did better then transparencies on UV because of greater contrast. now someone might actually do a side by side comparison sooner then me. or stumble upon the best tracing paperand you still have no idea what the post I found is talking about, its ambiguous if its toner transfer or toner light block

author: shapirus
author_rank: Super Contributor
timestamp: December 05, 2023, 09:57:12 am
content: Quote from: coppercone2 on December 05, 2023, 09:26:18 amI was going to give it a try, but a quick search showed that it's about $50 / 250 sheets. Nah thanks. I don't need that many. I'll stick with transparencies for now which are more expensive per sheet, but can be had in small quantities at ~$5 / 10 sheets.

author: coppercone2
author_rank: Super Contributor
timestamp: December 05, 2023, 10:04:37 am
content: what brand is good? i see alot of them on amazon for <20$i think the price is if its velum or paper. im not sure what is betteri am jsut gonna go with the cheap paper kind, lamb skin seems more impervious to ink then wood paper. just gonna go the ethical route here instead of ed gein. i seen couches wipe clean but paper is fucked once its inked. unless it bleeds I guess.https://www.amazon.com/Translucent-Printable-Sketching-Drafting-Quotidian/dp/B0951VQDPN

author: shapirus
author_rank: Super Contributor
timestamp: December 05, 2023, 11:14:55 am
content: Quote from: coppercone2 on December 05, 2023, 10:04:37 amnot sure. there's not much in our market at all, in fact it's only a single type of A4 sheets from Xerox and some rolls (for plotters) again from Xerox. so I'm out of the experiment on this one.choice of transparencies is wider. not all are good.

author: coppercone2
author_rank: Super Contributor
timestamp: December 05, 2023, 11:29:49 am
content: I am just thinking there is probobly no way a cast plastic can absorb or adhere to anything as good as paper. paper is the gold standard for composites.I bought a pack.I have 2x ruined segments of copper clad board that were used for tuning the exposure time. I can put my photoresist film on it with the method in this thread and try transparant paper exposureoh shit, i totally forgot you can use a 3d printer to make boards

author: coppercone2
author_rank: Super Contributor
timestamp: December 05, 2023, 02:37:14 pm
content: just FYI if you get kicad and freecad and get the freecad addon for kicad you can put the kicad into freecad and with the trace only botton you can get the thing to show up and then you can click the ground plane to delete it it looks like you can get the tracks into a 3d printer in 2 d form

author: coppercone2
author_rank: Super Contributor
timestamp: December 06, 2023, 01:09:12 am
content: tried my first dry film application. seems to work. I just did a bootleg test to see if it works at all. not as bad as I thought for how dodgy my work was. this stuff is damn thick compared to the mg chemicals one. need to try to develop it with sodium carbonate or whatever instead of the other mix I have. Exposure time is similar, I over exposed because I figured its thicker. I actually think the dry film silk screen might workI thought it might be unservicable balonyI just hope I can get by without a laminator, I hate the idea of buying that machine.

author: coppercone2
author_rank: Super Contributor
timestamp: December 06, 2023, 10:32:01 am
content: Quote from: shapirus on December 02, 2023, 11:11:51 amI scrubbed the copper with a brillo pad with bar keepers friend to 'activate' it, rinsed and spray dryed with anhydrous alcohol. I think I messed up because I did not have a mister for the water, I just put a few drops on. I had trouble trying to get water vaccuoles out from under the film after this. I tried to roll it as flat as I could and put it upside down on a hot plate with a plasticblock on top to press it down (set to 110C based on recommendations). I gave it a roll with a soft roller and then over exposed it.What do you recommend for a mister? Like a cleaning spray bottle or finer? I had a really nice super fine glass mister but I broke it a long time ago.Also, it did not look as good as a commerical one after. While it was adhered, it looked 'splotchy' on the bond interface, kind of like if you put glue down, lifted something transparant, and set it back down. like patches of frosting. Not sure what caused that. I think I can try lower temp, mist water and shorter exposure and a hard roller. I have a soft roller and a leather coated one I made... I guess I should buy another one. Only other problem is that I have positive film, my circuits were made for negative film. However, that is a easy change.I imagine the silkscreen process is similar to photoresist, so I have a few weeks to practice before that roll comes in.

author: shapirus
author_rank: Super Contributor
timestamp: December 06, 2023, 10:58:50 am
content: Quote from: coppercone2 on December 06, 2023, 01:09:12 amAre you talking about solder mask dry film (I mean as opposed to the etching resist film)? Which one did you use?

author: coppercone2
author_rank: Super Contributor
timestamp: December 06, 2023, 10:59:56 am
content: the photoresist. I don't have the dry film yet, but I Have alot of photo resist. it seems like good practice. it looks like the same shit different color

author: shapirus
author_rank: Super Contributor
timestamp: December 06, 2023, 12:38:02 pm
content: Quote from: coppercone2 on December 06, 2023, 10:32:01 amYou could have simply dipped the board in water, I think. That would have likely worked just as well. You just need it wet, but maybe finer drops allow to spread water more evenly, and it's easier that way.If you get a water (or air) pocket under the film, that will be a certain fail. Once you have them, it's a no-go. But you shouldn't be getting them, as long as you peel the protective layer just as you move the squeegee to lay the fim flat, gradually.I suspect it's the application technique that you didn't do quite right.I shot a quick vid to show what I do:Conveniently, it also demonstrates (at 0:43) a mistake to be avoided: do not peel the remaining protective layer and let go the film before the squeegee reaches the very edge of it. I did it because it's kinda inconvenient to apply the film while it's obscured by the phone that's recording the video.Quote from: coppercone2 on December 06, 2023, 10:32:01 amAnything, really. I use one of those travel covid hand spray bottles (seen in the vid). Of course, filled with water instead of the original IPA-based solution, because IPA, as well as ethanol, will thin or dissolve your photo resist. They can actually be used to develop it (I mean negative -- no experience with positive here).Quote from: coppercone2 on December 06, 2023, 10:32:01 amMight have been the temperature. 110C sounds a bit too high, try to begin with 70-80 and then, step by step, find your upper limit where it still works well.Quote from: coppercone2 on December 06, 2023, 10:32:01 amThey say that positive film is more difficult to work with (more sensitive to unwanted exposure etc.)I don't know, I only worked with the negative type.

author: coppercone2
author_rank: Super Contributor
timestamp: December 06, 2023, 01:16:24 pm
content: it also says positive film is less sensitive to solvent impingment and it has higher stability/resolution.I got it a long time ago because my goal was MSOP and smaller packages DIY. Like alot of them.The guides I read said 100-115C, but I can try way lower

author: coppercone2
author_rank: Super Contributor
timestamp: December 08, 2023, 05:01:29 am
content: The photoresist I have is three layers. One layer peels off, then you can heat it on the PCBbut then there is a top layer. I see in the youtube video this guy removes it after the exposure. But I am wondering why its there?could you get better quality by perhaps giving the board a little flash of UV light to delaminate the top film then expose the rest?I notice the prelaminated PCB do not have a post-exposure removal layer.edit: tried it. I was able to get the layer off after a few seconds of exposure but pretty much the photoresist totally failed during exposure. IDK if its viable to get rid of the middle film. perhaps I over did it.actually I found some ebay listing. it says to remove other layer after exposure. OK I guess. Just wanted to see what happens...i feel like god damn blade dealing with this shit. its like menacing vampire council. too much and it kills them too little and you don't get shitand I found another process definciency, the roller I have is a huge piece of shit. totally uneven. i wonder why I was getting blisters then I looked at it like a strait edge and its a wrinkly dinkly piece of red shit. switched to a ceramic rod and its like 5000 times better. fucking art storealso for wetting, I just scrubbed it with the barkeeper friend and then if you smear water on it with a wet plastic glove it seems to coat it fairly evenly. but you need more on the edges.and the temperature is like 105C. I tried 90C and it peeled off the copper. but I remember I got the wrong thermocouple in the hot plate and there is a error. I need to fix that (N instead of K). So I don't know what the true temp is. I think it was a bit lower. But at the lower end it was pretty close

author: westfw
author_rank: Super Contributor
timestamp: December 09, 2023, 11:53:18 pm
content: QuoteDoes it need a drying step in between? Some of those UV-cured things are all resin, but some of them are resin dispersed in a solvent...

author: Jwillis
author_rank: Super Contributor
timestamp: December 10, 2023, 02:47:18 am
content: Dry film photo resist is the blue clear film. Unexposed Dryfilm is soluble in sodium or potassium carbonate dissolved in water at 27-35°C (80-95°F). This is the development stage.Laminating is done between 100-115°C (212-239°F). I have gone as low as 93oC and it works fine.If you have questions about the process, it's best to consult the datasheet.https://www.dupont.com/content/dam/dupont/amer/us/en/ei-transformation/public/documents/en/DEC-Riston-LDI300-DataSheet.pdfStripping is done with sodium or potassium hydroxide. Sodium Hydroxide is commonly known as Lye.Dry film solder mask (clear green)is resistant to most chemicals when exposed . Unexposed mask is developed with sodium or potassium carbonate the same as Dry film photoresist. Application is usually done with a vacuum with a combination of UV curing at 121°C Max and Thermal curing at 145 – 155°C .http://www.cipeldistribution.com/uploads/default/Dynamask-5000-161130.pdfThe processes are similar but Neither can replace one for the other for obvious reasons.For Wet laminating, this is the process recommended to me.http://www.cncnet.info/galery/dupont/Wet_Lamination_of_Photoresist_for_Hobbyists.pdfIn any case the you don't want your temperatures to get to low.All liquid photoresists need to be dry before exposure. Drying is not the same as curing as long as the drying temperature is not to high. This is especially important with heat cured Masks.Consult the datasheet for the type and make of liquid mask you are using.

author: coppercone2
author_rank: Super Contributor
timestamp: December 10, 2023, 02:50:31 am
content: a vacuum?just let me get my fucking moon base readyi already hate those god damn rollers. the only two rollers I like is the pasta machine. and even that one pulls pasta into the god damn gearbox. now you need a vacuum pasta machinedealign with that god damn paste shit is better then a vacuum lamination machinei wonder how much of a difference it makes or if its just some quality wankoff to confuse people that it needs to be assembled in intergalactic deep space and exposed by Bellatrix to be any good (meanwhile some chinese guy with a soup ladle and a street light does a better job)

author: sleemanj
author_rank: Super Contributor
timestamp: December 10, 2023, 04:04:23 am
content: Quote from: coppercone2 on December 08, 2023, 05:01:29 amTo protect it from damage, also it's a bit sticky.Using dry film is explained in my documenthttps://sparks.gogo.co.nz/dry-film-tips.pdf

author: shapirus
author_rank: Super Contributor
timestamp: December 10, 2023, 01:58:32 pm
content: Quote from: coppercone2 on December 10, 2023, 02:50:31 amI guess that has to do with the fact that it has to fill every tiny gap where copper areas transition into hollows (etched areas). I can't see how it can be done without vacuum.The etching resist film, OTOH, is applied to a more or less even copper surface, which makes it much easier, as there are no hollows.That's what, theoretically (I haven't tried it yet), should make liquid solder mask much more appropriate for DIY boards as it's easy to apply it so that it fills every microscopic gap on the board regardless of its depth.Has anyone tried dry film solder mask for DIY PCBs? Does it work at all? What are the tips and tricks, if it does?Quote from: coppercone2 on December 10, 2023, 02:50:31 amNow that's an idea! I do have a pasta roller machine. Next time I'll try to use it instead of the simple polyurethane roller (if it's possible to use just its rollers without the parts that will try to shred the board).

author: shapirus
author_rank: Super Contributor
timestamp: December 10, 2023, 02:06:58 pm
content: Quote from: sleemanj on December 10, 2023, 04:04:23 amThat's a very good howto. Could very well be a "read this first" link in a DIY PCB forum section. It'll give a good starting point for a beginner and help avoid a lot of trial&error.The font, though... That's one hell of a font choice for a text document. It makes reading difficult, especially from screen. There's a good reason why proportional sans-serif fonts are a de-facto standard for screen text (and they're readable just as well on paper).

author: Jwillis
author_rank: Super Contributor
timestamp: December 11, 2023, 07:16:01 am
content: Quote from: shapirus on December 10, 2023, 01:58:32 pmOne has to keep in mind that those procedures describe in the data sheets are for industrial laminating machines. Not all the procedures are possible for the average hobbyist. So sometimes we have to make things up as we go and try different things. I've not used it myself but a person could make a vacuum box similar to ones used for vacuum forming. I made one for making vacuum formed pieces for model rockets and model airplanes when I was young. But that's a lot of extra work.Theirs no rule that says we can't use different methods for each stage of PCB building. Some people will find some procedures easier than others based on what they have on hand for tools, equipment, work area and availability of supplies.As long as the basic instructions for application are followed for the material your using. Dry film requires pressure and heat to be applied at the same time. Heat softens the film and the pressure "squishes" it into the micro fissures of the copper.I gave up on dry films because by the time I get it, it's been X-rayed and opened to light by customs officers. So a roll won't last a month, if that. Sometimes it was just about completely exposed because it wasn't wrapped back up properly.The liquid etching paint and mask works better for me because I can gt it in small batches and it lasts longer on the shelf, that's all. Maybe a bit better resolution. Aside from how it's applied the chemistry is the same.I'm wondering if any one has used thishttp://www.kontaktchemie.com/koc/KOCproductdetail.csp?division=&product=POSITIV%2020&ilang=en&plang=enand if it's any good. I've tried to find it here but haven't had any luck.

author: coppercone2
author_rank: Super Contributor
timestamp: December 13, 2023, 03:06:54 am
content: lol the dry film totally failed.idk how to translate their insane process to something I can understand. need some kind of UV joule meter I guess.don't think its worth my time, I will stick to tintook me 20 min to get the film off the top even. tape does nothing. mega frustrating shit. Think I feel more confident in trying to deal with the goop then tryin to use this fucking film.probability of success: zeroidk what tape would be sticky enough. crazy ! the blue UV exposure shit looks like a MAYBE because I can at least get the protective layer off. this one is just pure troll. dynatroll 5000now after I fuck up the exposure, the other film side comes off easily, but the initial film? forget about it! adhesion at 60C ? LOL more like 100. Maybe if you have some million dollar vacuum laminatorleave this one for ET. this one makes me want to flog myself with a three phase line! :vomit:

author: shapirus
author_rank: Super Contributor
timestamp: December 13, 2023, 09:54:26 am
content: Now, once again, are you talking etch resist or solder resist film?With solder resist, I have no experience (but I actually ordered some liquid one yesterday to experiment with it).If you mean etch resist film, well, the trick to remove the first (inner, in terms of how it sits on the roll) protective layer is to stick a piece of scotch tape onto it, in a corner, and peel it off using that tape. May take a few attempts, but it's much easier than without it. May need to make it a bit loose in that corner using a needle or something before applying the scotch tape.p.s. yeah, of course, in either case it requires certain level of fine motor skills. It takes time and patience to grasp it :)

author: coppercone2
author_rank: Super Contributor
timestamp: December 13, 2023, 09:38:36 pm
content: no, the solder resist film green is the one that is impossible to use. the pre-etching film is OK. The pre-etching film I have is purchased in 2020 and it works OK, just some problems with air bubbles etc.dynatroll 5000basically the blue film is OK. The green film does not work as in the complex manual with vacuum laminating joules per second whatever. i probobly recommend you keep messing with the paste then attempt the green filmwith the green shit, if you read the manual, your supposed to bake the PCB bone dry before applying it. you can't even use the trick where you put water on the PCB before applying the film! it says wash then bake at 80C for like 1 hour, apply film (in a vacuum I might add), then go through a sequence of chemicals, heat and exposure to UV light.

author: coppercone2
author_rank: Super Contributor
timestamp: December 13, 2023, 09:55:19 pm
content: I could give you more insight if I could figure out how to measure light joules per second for the procedure for the green filmand figure out what tape i need to remove the top layer of the green film

author: shapirus
author_rank: Super Contributor
timestamp: December 13, 2023, 10:45:19 pm
content: Nah I guess the liquid one is the way to go. It's shipped, I guess I'll play with it on the weekend.One problem to solve will be to figure out what kind of solvent can be used to remove the uncured (unexposed) resin after exposure, especially if the substance is dried before exposure, like people generally recommend.Acetone is not an option (illegal to buy and sell without a drug license here). Ethanol, IPA, petroleum solvents and sodium hydroxide, for example, can be easily obtained. I hope that the 75/115 oil fraction solvent that I have will work, otherwise I don't know.p.s. 1 J/s = 1 W. But I guess it's of no use, because they probably mean actual power transmitted by the light waves, or who knows what.

author: Smokey
author_rank: Super Contributor
timestamp: December 13, 2023, 10:52:33 pm
content: I'm not sure what all the problems are here. My PCB solder mask comes out absolutely perfect every time.My procedure is:1) Click the "Green" Option for "PCB Color" at JLCPCB2) Boards show up with perfect solder mask.Seriously though, if you absolutely can't wait 7 days for boards and you have to have hand made PCBs right now, do they need soldermask? What is the use case for these boards?

author: coppercone2
author_rank: Super Contributor
timestamp: December 13, 2023, 10:56:00 pm
content: omg acetone requires a license?!its found in your body in small amount AFAIK. The smell concerns people I guess?

author: coppercone2
author_rank: Super Contributor
timestamp: December 13, 2023, 10:59:15 pm
content: Quote from: Smokey on December 13, 2023, 10:52:33 pmwhat is a use of studying electrical engineering? I go on a industrial job board and hire a consultant to bring me a finished product that i described over a telephone within 2 months. I even have my accountant do all the boring part with the numbers. I even have IT run it it for me because of the crazy thing with the power company.whenever I get this post it feels like dealing with Q spawning. I am sure in the last problem you faced you hired some people to change the gravitational constant of the universe.

author: shapirus
author_rank: Super Contributor
timestamp: December 13, 2023, 11:41:14 pm
content: Quote from: Smokey on December 13, 2023, 10:52:33 pmFinally! I wonder why it took so long this time for someone to come and tell us that outsourcing PCB fabrication is the way to go.Thank you very much. We are well aware of its advantages.The fun for many of us, however, is exactly in the DIY part. At least in the beginning.

author: shapirus
author_rank: Super Contributor
timestamp: December 13, 2023, 11:45:26 pm
content: Quote from: coppercone2 on December 13, 2023, 10:56:00 pmWell it's used to make drugs, that's why. We can't also buy e.g. potassium permanganate for that same reason too.Anyway, there ought to be some substitute. I'll search around.

author: coppercone2
author_rank: Super Contributor
timestamp: December 13, 2023, 11:47:41 pm
content: lol what can't be used to make drugsthat water... someone might try to dissolve something in it!!!

author: shapirus
author_rank: Super Contributor
timestamp: December 13, 2023, 11:59:09 pm
content: Quote from: coppercone2 on December 13, 2023, 11:47:41 pmWell yes you get it right. It's ridiculous but it is what it is.

author: coppercone2
author_rank: Super Contributor
timestamp: December 14, 2023, 12:00:41 am
content: how about gasoline? That is a extremely powerful solvent, its just not used much because of its uber explosive natureif its too powerful you can freeze it first, the solvent power decreases with lower temperature (work in a cold box)

author: shapirus
author_rank: Super Contributor
timestamp: December 14, 2023, 12:02:56 am
content: Quote from: coppercone2 on December 14, 2023, 12:00:41 amThat's my hope. The 75/115 that I mentioned is basically gasoline, a light oil fraction used as a solvent. I use it to degrease stuff, works fine for that. Also dissolves flux residue very well btw, much better than IPA/ethanol.

author: coppercone2
author_rank: Super Contributor
timestamp: December 14, 2023, 12:03:55 am
content: playing with temperature of whatever solvent you are working with might be useful. hot or very cold (even with dry ice in it). Just the board has to be frozen or heated so there is no thermal shock

author: shapirus
author_rank: Super Contributor
timestamp: December 14, 2023, 12:07:40 am
content: Well, I'll post an update when I get to it. I'm gonna try both dried and non-dried solder mask resin, different exposure times and see how it all works.

author: rdl
author_rank: Super Contributor
timestamp: December 14, 2023, 02:00:26 am
content: Instead of acetone, you might look for something called "lacquer thinner". You can usually find it at hardware stores and hobby shops.

author: shapirus
author_rank: Super Contributor
timestamp: December 14, 2023, 10:04:54 am
content: Quote from: rdl on December 14, 2023, 02:00:26 amNail polish remover might be yet another option. It used to contain acetone, but now they make it from something else, which still does the job, so it might work as well. It's however costly, as it's sold in tiny bottles, and smelly because of the nasty perfumes they add to it.update: I just checked one (almost empty) bottle lying around, and the sticker says that it actually contains 50% acetone. Made in 2015, though. Interesting, I'll need to check the stickers of those they sell now.

author: coppercone2
author_rank: Super Contributor
timestamp: December 14, 2023, 02:16:45 pm
content: its ethyl acetate. smells nice an available as MEK replacement in gallon quantitiesnow I will say, MEK does smell fuckin terrible. acetone is a bit sharp but MEK is just awful.

author: shapirus
author_rank: Super Contributor
timestamp: December 14, 2023, 03:03:06 pm
content: Quote from: coppercone2 on December 14, 2023, 02:16:45 pmRight, it's the second component that it contains after acetone: acetone < 50%, ethyl acetate, water, glycerine, chamomile extract, perfume/fragrance (no idea how to translate correctly -- the stuff that's supposed to mask the smell of the chemicals).Will probably buy a fresh bottle of it, if the composition hasn't changed.

author: Jwillis
author_rank: Super Contributor
timestamp: December 14, 2023, 08:27:18 pm
content: Isopropyl alcohol dissolves the unexposed mask that I use. Not sure if it's the same as the mask you use, but I can't see it being any different. This is a dried liquid mask and not the dry film just to be clear.

author: shapirus
author_rank: Super Contributor
timestamp: December 16, 2023, 05:25:07 pm
content: All right, first results aren't so bad.The substance I've got is "Mechanic UVH900".Proper application may be a bit tricky. Basically, for the result to look good, you need to apply an even layer of it. So far I have tried using a piece of a transparent film that I print the PCB stencils on as a squeegee to flatten the liquid that I put and spread more less evenly on the board: it works, but it's too thin, need something thicker/more rigid for a better result.I'm not sure if drying it prior to exposure is actually necessary. I did one run without drying, but didn't expose enough, as it turned out later. Will need to try again.It takes time to dry. 20 minutes at ~100 deg.C is far from enough. I didn't have the patience to wait longer.Then, I put a layer of thin PE wrapping film onto the board to isolate the stencil transparency from the resin. This does not work very well: it leaves wrinkles that are then imprinted in the resulting image. Need something a little thicker and that doesn't stretch -- I think the film used in baking sleeves should work.Then, exposure. This one is the most surprising: it requires, and tolerates, a LONG exposure. For comparison, where I do ~50 sec for the negative photo resist film, I did 5 minutes for the solder mask, and I believe it could have been even longer, as the unexposed areas still washed away very easily. A longer exposure should allow to cure the exposed areas better.Developing was easy. No acetone or solvents were necessary: as advised in the post above, IPA (actually 50/50 IPA+ethanol -- I believe either would work) worked like a charm.I tried to touch and lightly scrub it with an iron tip at ~330 deg.C -- no damage, stays in place.It doesn't have the glossy look of a factory-made PCB, the surface is matte, but it'll do the job.Attaching some close-up pictures: one is an SO-8 footprint, another shows some 1206 footprints. The traces inside the SO-8 and the vertical traces connecting to the 1206 are 15 mil wide. Resolution can be quite decent, once the right application process is figured out, and it can also be used to create a DIY silkscreen layer.The surface is the copperless side of a single-sided board.

author: coppercone2
author_rank: Super Contributor
timestamp: December 16, 2023, 05:50:39 pm
content: it looks likeand if its durable enough then it does not matter what it looks like

author: coppercone2
author_rank: Super Contributor
timestamp: December 16, 2023, 05:54:25 pm
content: how does it do with solder wicking under it? Some silk screen seems to let solder creep under it and lift it, while some seems to act as a barrier. like it will prevent splashing and prevent like a flow from one trace to another, but it will let the solder penetrate under the silk screen on the trace you are solderingsome 80's silkscreen will actually stay (loosely) on top of the molten solder that penetrated under it. Then if you start poking it with tweezers it might flake off. Not sure if that means its compromised or if its a certain type.

author: shapirus
author_rank: Super Contributor
timestamp: December 16, 2023, 05:56:21 pm
content: I can see how it can be more attractive for etching than the usual resist film. Much more tolerant to varying exposure time, much easier (however a bit more messy) application, no need for a laminator or iron or the tedious removal of the protective layer films.The only questions are whether it is impervious to the etching solution and what can be used to remove the remaining mask after etching is done. I'll try to drop it into NaOH now and see if that works.

author: coppercone2
author_rank: Super Contributor
timestamp: December 16, 2023, 05:57:15 pm
content: well that might be a interesting way to make a high power board of thick copper weight. And my other interest, which is making complex sheet metal parts from etching out of thicker materials. Like screens shields etc.if you can get correctly shaped sheet metal bits you can make advanced stuff like telescoping optics with custom limit switches and slide contacts etc.. combined with a 3d printer that brings it into the realm of advanced optics and possibly even feedback positioners for things like controlling ion beams or something.But my hopes are not too high because for contacts its only 1/3 of the puzzle, you still need the final forming dies (precision ground) and platings. But for a prototype......... that stuff only needs to be considered for long term wear. I have a feeling simple rub on silver plating with manually formed curls will function for a plastic telescoping tube mechanism (i.e. camera), and you can also go heavy on grease to reduce need for platings

author: shapirus
author_rank: Super Contributor
timestamp: December 16, 2023, 05:58:20 pm
content: Quote from: coppercone2 on December 16, 2023, 05:54:25 pmYes that's interesting. I'll check this later. Need to find out how to remove it first (apart from mechanical scrubbing) to reuse the same board for multiple experiments.

author: coppercone2
author_rank: Super Contributor
timestamp: December 16, 2023, 06:04:46 pm
content: probobly hot concentrated hydroxide solution will eat itI recommend modest exposure followed by rinse and scrubbing to get rid of flakes then redip. a combined mechanical chemical process will save you time and energy (you need a deep basin too). Take extra care to verify water pressure is stabilized for rinses, kitchen faucet is ehhhh..possibly alcohol mixed with hydroxide too (50% ethanol 50% strong potassium hydroxide solution).get goggles that conform to face and make sure your handling tools are excellent (no trying to pry a circuit board from bottom of a exposure vat with a butter knife). When you deal with these mixes it needs to be so that every motion you make is low energy. No tweezers either IMO. Any spring that can open up on you for whatever reason can splash caustics. You want like hooks to lower and raise thingsand making up a bottle of spray weak acid for neturalization of drops is a good idea. if you see small splatter as you go, neutralize first...also recommend metal pots and pans for this, not glass, and also handles that areverifiedfor ideal safety let the vessel totally cool before moving/pouring. Get lids for the pots so you can close it when you are done and let it totally cool down.new pair of thick rubber gloves too for pouring (preferably reinforced with fibers)if you are unfamiliar with strong hot caustic burns, they really suck, avoid them at all costs.

author: shapirus
author_rank: Super Contributor
timestamp: December 16, 2023, 06:14:46 pm
content: Yeah I'm well aware of how nasty strong bases are.FWIW, it's been sitting for a few minutes in a solution of an unknown concentration (a few grams of dry close to 100% NaOH drain cleaner in ~30ml of water), zero result so far. I'll let it soak for longer, but I think something else may be needed. If it requires some fancy chemicals for stripping, then it's a downside for etching use, and it makes it somewhat more difficult for DIY, as there is basically no undo if you mess things up, or undo is tedious (mechanical removal).

author: coppercone2
author_rank: Super Contributor
timestamp: December 16, 2023, 06:16:00 pm
content: heat is probobly a requirement. and alkaholic KOH is powerful. used for cleaning severely dirty chemistry glasshttps://www.inrf.uci.edu/wordpress/wp-content/uploads/sop-wet-alcohol-hydroxide-cleaner.pdf

author: shapirus
author_rank: Super Contributor
timestamp: December 16, 2023, 07:08:57 pm
content: Okay, so:- NaOH (not too concentrated): fail- Toilet cleaner with "<5% Sodium hypochlorite": fail- Petroleum based solvent: fail- Nail polish remover (<50% acetone, ethyl acetate): hmm... It seems to work, somewhat. It doesn't dissolve the solder mask, but it seems to degrade it such that it becomes rather easy to scrub off mechanically. The problem however is that I don't have much left of it, and the ones sold today are all acetone-free, they only contain ethyl acetate. No idea if that'll work the same. However, there is a solvent actually available that contains <50% acetone+toluol, and that might work as well. But that's nasty stuff too, requires ventilation and all.At this point it becomes totally not worth it for etching, and for the actual solder mask and silk screen... well, avoid making mistakes so that you won't have to remove it later

author: shapirus
author_rank: Super Contributor
timestamp: December 16, 2023, 09:44:12 pm
content: Another run:- no drying at all- baking sleeve film for the separation layer- 7 or 8 minutes of exposure (I screwed up the timer, so not sure exactly)Results:- glossy surface!- very decent mechanical strength, can't scrape it off with a fingernail, including the shape edges- the liquid must have as little bubbles as possible before levelling it flat and covering with the separation layer- the baking sleeve film is a pleasure to apply: works just like the etching resist film applied onto a moist copper surface- good resolution(metric scale: 0.05mm/div)

author: shapirus
author_rank: Super Contributor
timestamp: December 16, 2023, 09:47:51 pm
content: btw, as far as the drying step goes, it may depend on the actual material used. There may be liquid masks thinned with some solvent, then probably it may be required. In my case it doesn't seem to need it. It's also odorless (unless you sniff it real close), which suggests that there's no solvent to be gotten rid of prior to exposure.

author: sleemanj
author_rank: Super Contributor
timestamp: December 17, 2023, 01:13:08 am
content: The drying is only needed for easier handling (no separation reqd) is my understanding.I have never heard the term "baking sleeve", is it just a name for an oven roasting bag?

author: coppercone2
author_rank: Super Contributor
timestamp: December 17, 2023, 02:27:59 am
content: yeah actually that does not make sense to me either a transparancy I would imagine is way more stiff then any turkey bag or whatever (i don't use them though)re-read it. he means something stiffer then saran wrap. a turkey bag might qualifythe problem of a thicker more durable spreader has not yet been solved with kitchen goods

author: abeyer
author_rank: Frequent Contributor
timestamp: December 17, 2023, 03:33:18 am
content: Quote from: coppercone2 on December 17, 2023, 02:27:59 amI'd consider trying the FEP films (and corresponding frame/stretcher assemblies) used in 3D SLA printers. They're specifically designed to pass UV and not bond to the UV cured resins... so seem like they'd be a perfect material, and the film plus prebuilt frames to hold them flat and tensioned are readily available.

author: shapirus
author_rank: Super Contributor
timestamp: December 17, 2023, 10:02:49 am
content: Quote from: sleemanj on December 17, 2023, 01:13:08 amYes probably. I have no idea how it may be called where you are, so I just translated literally how it's called here. It's a sleeve (sold in rolls) made of thin temperature-resistant polymer film that you can cut a length of, put something (e.g. a chicken) in, tie at both ends, and put in an oven.The advantage of it is that it doesn't stretch and doesn't form wrinkles when put over the liquid solder mask. Easy to apply as well: start at one side, and from there it goes almost on its own, being pulled by the liquid's surface tension.It also doesn't adhere to the cured resin (neither does PE film, but it's next to impossible to apply it evenly without creating surface defects).Quote from: sleemanj on December 17, 2023, 01:13:08 amWith the solder mask I bought, it is still required, even after drying it for 20 minutes at ~100 deg.C (which I guess should be enough). It doesn't get sticky, it isn't drying inside, only the surface becomes matte. So probably it's a different type (e.g., solvent vs no solvent, I don't know).But I think I like it. Easy to work with. Only requires some practice at the spreading stage, where you want to make it spread as evenly as possible, avoiding bubbles and other irregularities, and make sure that it's not too thin (being not too thick I think applies as well).p.s. I think I would want to use a separation layer in any case: I use ink jet transparencies with the printed side facing down during exposure, and anything but dry clean surface may damage the printed image.

author: shapirus
author_rank: Super Contributor
timestamp: December 17, 2023, 12:46:13 pm
content: Not only it is more tolerant to the varying exposure time, but also to the stencil's contrast. Poor stencil seems to contribute to the number of defects, though.I have now made an actual solder mask on the copper side to test if the solder will try to wick under the mask coating. I did not want to waste a transparency sheet on this, so I just printed the mask layer on a sheet of regular paper and then soaked it in oil to make it translucent. Proper transparency is still a must, I guess, for a real PCB.10 minutes of exposure, result:Again, the better you spread it before exposure, the better result you're going to get. Bubbles are your enemy, and it doesn't matter where they are: inside the liquid, between the liquid and the separation layer, or, in this particular case, between the separation layer and the oiled paper stencil.For example, the big uncovered spot in the upper right corner between the two 1206 pads is the result of an air pocket between the solder mask liquid and the separation layer. So it needs to be applied carefully and without any air pockets, just like the etching photo resist film.Some defects will still be unavoidable, I guess. If there's a few bigger ones, they can be fixed by manually putting some liquid mask on them and exposing it to UV. It may also make sense to perform the operation twice to create two layers, each of which will cover the defects of the other.

author: shapirus
author_rank: Super Contributor
timestamp: December 17, 2023, 01:37:29 pm
content: Solder test: passed.

author: tooki
author_rank: Super Contributor
timestamp: December 17, 2023, 01:48:02 pm
content: Quote from: coppercone2 on December 16, 2023, 05:54:25 pmI'm pretty sure what you're thinking of is the 80s-style solder mask which was appliedover solderto begin with. (It's the kind that looks crinkly.) It's not that solder is wicking under it, but rather that it was applied to PCBs which had all the traces tinned (e.g. HASL)beforesolder mask was applied. So when heated, that solder that's already underneath can melt, robbing it of a solid foundation, making it vulnerable to flaking off.AFAIK we no longer use that process, and solder mask is always applied directly to the copper (or in some cases, other plating), but never over solder.

author: shapirus
author_rank: Super Contributor
timestamp: December 19, 2023, 08:37:06 am
content: Not all solder mask liquids are equal.The red one shown above was perfect. Very good mechanical durability and adhesion to to surface.Then I tried yellow: same brand, same series, Mechanic UVH900. This one was a complete fail. Very poor adhesion, it just doesn't want to stick to the surface, even though it seems to polymerize well. It just tends to flake off.Unlike the red one, the yellow can be dried: 5 minutes in an oven at ~110 deg.C, and it becomes tacky. So obviously a different, and worse, material than the red. Maybe not exactly worse, but requiring a different technique, which is not known to me.I have also ordered green and black liquid of the same name. Will test them some time later.

author: coppercone2
author_rank: Super Contributor
timestamp: June 10, 2024, 10:43:40 pm
content: I finally broke down and bought a laminator machine with adjustable temperature that is somewhat industrialthat is one weird thing to buy. but eventually something bad is going to happen playing press on the hot plate

author: coppercone2
author_rank: Super Contributor
timestamp: June 12, 2024, 07:36:56 pm
content: great ceasars ghost what a piece of crapit needed a oiling and a severe brogain adjustment before the motor quieted down. I put silicone grease on the gears and silicone oil on the motor and the roller bushings (one of which is broken).I wonder if this thing did tours of duty at the DMV or something lolALSO wtf is the motor60KTYZBut the one in the machine has a 3 phase terminal block and its 110V. The ones for sale are for +-

author: coppercone2
author_rank: Super Contributor
timestamp: June 13, 2024, 02:22:27 am
content: well I tried to coat some PCB. It comes out better but there was some wrinkles etc. as i suspected its still difficult to get it nice

author: coppercone2
author_rank: Super Contributor
timestamp: June 14, 2024, 04:42:20 am
content: ok if your doing this be sure to try different films. I got two blue films. One is older.The older one maybe its thinner I did 10 attempts to laminate a board i could not get it to spread out without bubbles for anything. the other one is like 99 times better. it has a orange peel effect on it though. its tiny. not as nice as presensitized pCB but I have a feeling it will work.this stuff can make you seriously mad if you get the wrong filmthi is gonna take off when you have lunar apartments so you can do this vacuum bullshit by opening a window to your house. i loathe vacuum systemsalso they should be slightly sticky. i noticed it sticks really good to glass. the old film is not sticky.also another problem is that it rolled up. i wish the fucking sellers stop rolling this shit up. I would pay you for a big fucking roll so it does not curl up. IMO basically all the film that you buy is broken by sellers that wanna roll it up tight like a fucking blunt. roll it around a dryer duct and sell it in a bigger box. its ruining the film.