Making high quality home etching easy - 6/6mil PCBs exposed with an SLA printer - Page 1
Forum section: electronics / general

author: TmaxElectronics
author_rank: Regular Contributor
timestamp: January 21, 2022, 01:43:32 am
content: Just a note to start with: this is not a full tutorial, only a collection of info about my idea. There is a little guide further down, but I will make a proper tutorial if the interest is there.I know making PCBs yourself is mostly a thing of the past in the age of cheap express prototype board houses, but from time to time it can still come in handy to make your own.I've been making mine the good old fashioned way with transparencies and an inkjet printer, but actually getting them right was probably the most annoying part of making the PCBs.To make live easier I've started using the photomasking LCD from my Elegoo Mars SLA printer as a replacement for the transparency some time ago and I think I've nailed down the process now. I think I've seen a video of somebody trying something similar but he used the resin as a photomask, which didn't give as good a result as my technique, so I thought I'd share it here too.First off: the results.My latest PCB goes right down to 6/6mil spacings, and despite using the dry-film style photoresist for the first time and over-exposing it I still managed to etch it first try. Here are two 6mil traces between adjacent soic-8 pads:I can easily get traces between 0402 and larger SMD components and tested qfn footprints down to 0.5mm pitch.For double layer boards I also made an alignment jig, with which I consistently get the layer offset small enough for 1mm vias (0.7mm hole) not to short out against the ground plane from offset holes.How to get the gerbers into the printer:The Video I watched had the guy basically create a 3d model from them and then used the normal chitubox software. But that's tedious and doesn't easily allow for configuration of base-material parameters.So I decided to write a little software that allows you to import gerbers, apply scale corrections, adjust layer alignment and some more things and then just gives you back your .cbddlp file for the printer. It support almost the entire gerber standard with the exception of arcs (at least for the moment).But there's a catch... I'm not the desktop software kind of a guy; I can only program java and my skills aren't the best. That in combination with me getting easily bored by a project lead to me getting it to the point where I can use it, but not really anybody else (unfinished UI, no printer/exposure presets etc.). If there is enough interest in the project I will pick up development again though.That being said, here's the repo:https://github.com/TMaxElectronics/Gerber2ChituboxSo here's the process:First you'll need to modify the screen of your printer, this is a little dangerous so do it only if you are sure you can get a replacement screen (CHECK THAT! MARS SUPPORT WAS JUST DROPPED F.E.). By default the printers lcd has a glass pane in front of it for protection and likely flatness too. This however reduces exposure accuracy a lot (more like 0.4mm/15mil process) because of the lamp geometry. To fix this you will have to remove the piece of glass.First (carefully!) remove the display assembly from the printer. unfortunately it is glued in quite well (at least it was in my printer) which made it impossible to do without damage. (this is where the replacement screen might come inOnce you have the screen out you can start separating the glass pane. The two parts are glued together very well but putting a drop or two of isopropanol in between the actual lcd and the glass almost immediately loosens the glue. Slowly peel it apart. It shouldn't take much force at all, if it does add a bit more IPA.Then install only the LCD in the printer and put the thinnest non-transparent tape you can find around the outside of it so it looks like this:I also recommend making some alignment helper. The one I made registers in the space for the resin tank to make using it repeatable. This is less critical for doing single layer exposures, but absolutely essential for double. Something like this (ignore the numbers):Sidenote:you can't print 3d without the glass in front of the LCD, if you have used thin enough tape however, you can just lay it back onto the screen. It will stick down a bit again but not enough to make removing it a pain. Make sure to re-level your build platform after that though.sort-of-guide:Export the gerbers from your PCB-CAD.You will want to tell it not to use arcs (altium has an option right in the last dialog for that)Open them with the software I created.To do that, just run it with the java runtime environment, click the "+" button bottom left, and select all your gerber files. I recommend adding the drill files as well to generate centering holesExport the individual layers.Select each layer in the list on the left and click export. Select your printer (currently only the mars 1 is supported), and type in the parameters for your laminate.You also need to mirror the layer if it is on the bottom of the PCB. To make sure you are doing it right I recommend adding some text to each layer, and verifying that is it not mirrored in the layer preview in the export dialog. If desired you can add a centering holes too: select the layer with the holes in the bottom box, and adjust the hole size if you want.Then click export and name the file (right now you need to manually add the .cbddlp extension) and Copy the file to your usb stick like any other 3d printPrepare your base material, developer, etchant and what other things you might need once the exposure is completed. Remember that the software adds 2mm clearance from the LCD edge to the print, and the LCD has a bezel too. That is to say: cut your board quite a bit larger than the dimensions you want it to be in the end, and trim it down afterwardsAlign the base material on the LCD.Non mirrored layers will align on the right side while mirrored once are aligned on the left, this is so you can use only one reference edge for double layer exposures. You can briefly start the print if you aren't sure which side it will align on. If you're making a double layered board make sure to mark which corner was where so you don't forget it. Alsomake sure to sand any burs off the edges of the board or you might damage your LCD. To improve quality I also recommend putting some weights on the PCB, just make sure the base-plate arm won't hit them once its fully downExpose the board.Select the file on the printer and hit start like with any normal 3d printIf you have a second layer to expose, flip the board and align it to the horizontally opposite edge (you can verify you have it the right way around with the corner markings you made on the board)Develop & Etch.This step is the same as with other exposure methods.?Profit(couldn't resist the joke)I have recorded some video of me explaining it in detail but I'm not that happy with the way I did, but I'll re-record it if people are interested.So what do you think, is this something that is just useful for me or a project that could help others too? If there's enough interest I'll document everything properly and also get the software up to snuff. I'd love to get your feedback on this

author: Zucca
author_rank: Unknown
timestamp: January 21, 2022, 04:33:40 am
content: Quote from: TmaxElectronics on January 21, 2022, 01:43:32 amCode:[img width=XXX]path_to_ingXXX is the width of the picture....example:Code:[img width=400]https://i.imgur.com/MkQ3AEc.jpg

author: TmaxElectronics
author_rank: Regular Contributor
timestamp: January 21, 2022, 12:59:59 pm
content: QuoteThank you so much, I've added that to the initial post

author: thm_w
author_rank: Super Contributor
timestamp: January 21, 2022, 10:11:30 pm
content: Nice work. Seems like a lot lower than 6mil is possible.One thing that isn't clear, is the device still usable as a 3D printer, or has it been modified beyond normal use?One of the older threads here:https://www.eevblog.com/forum/3d-printing/printing-pcb-with-3d-printer/

author: E-Design
author_rank: Regular Contributor
timestamp: January 21, 2022, 11:04:59 pm
content: @TmaxElectronics,"I know making PCBs yourself is mostly a thing of the past in the age of cheap express prototype board houses,"....Yes we hear that argument alot. However, the value of doing it yourself isNOTto save money in my opinion.. It is to saveTIMEprototyping.With DIY circuit boards, one can go from idea to working prototype in *one afternoon*. and by evening iterate or throw away the idea.One cannot (for any sane amount of money) purchase a PCB for delivery in a few hours. So I DIY boards torapidlyprototype and save time. The DIY method therefore is justified as a valid approach to this very day.For that reason, I am very much interested and hearing more about what you have done here. Keep up the great work!

author: TmaxElectronics
author_rank: Regular Contributor
timestamp: January 22, 2022, 02:44:01 am
content: QuoteIn theory it should be easily un-modified. If you keep the glass panel you removed from the screen and used some thin enough tape you should be able to just place it back when you want to 3d print something again. But full disclaimer: I haven't tried this yet. I rarely use my printer for its intended purpose and have a spare lcd on hand so I just swap out the entire assembly everytime I do print something.I'll just do a benchy run tomorrow with the glass back in place, then we know moreQuoteTotally agree! Even though 1 week is fast, there are some PCBs you simply need NOWI haven't timed a full run with the new dry film resist because I'm still getting used to it, but with the pre-sensitised boards I could get from a gerber file to finished double layer pcb in hand in <1h (if it didn't have too many holes of course)Oh and I forgot to mention in the initial post that I am also kind of working on hardware that will make things even easier. You can buy the LCD screens cheaply from aliexpress and it wouldn't be too hard to build some hardware that takes gerbers from an sd card or the network and throws them onto a display without any need for the chitu hardware at all. The display uses two seperate 4 lane mipi dsi interfaces, so an FPGA would be required.But nice to hear people are interested, I'll be sure to update you on any progress I make (mainly with the stillterriblesoftware lol)

author: PlainName
author_rank: Super Contributor
timestamp: January 22, 2022, 07:37:12 pm
content: QuoteI am interested in the sense of following what you're doing and thining of possibilities. But would I use this? Hmmm.I went through a phase of etching (still got a tank of etchant int the garage awaiting some activity) but switched to milling. Apart from not having to mess with chemicals, and have somewhere to mess with them and then dispose of them, it was the holes that got me. Holes with relatively thin annular rings would be prone to the copper lifting when drilled, and getting accurate positioning on very small holes could be a drag. With milling you start with no tracks or pads at all, so making the holes is no problem and then the milled annular ring can be thinner. Perfect registration too. But it can be a lot of dicking about to get a good setup and I wouldn't even dream of trying to get 6mil tracks.So, I am wondering right now if an answer may be to pre-drill and then use the holes to accurately position the screen. Previous etching setups used printed output which, even on film, could stretch. You seem to have the double-sided issue resolved so maybe that or a similar thing could be used for the drilling and exposing.

author: nctnico
author_rank: Super Contributor
timestamp: January 22, 2022, 07:58:34 pm
content: Quote from: TmaxElectronics on January 22, 2022, 02:44:01 amNo. An NVidia Jetson module suffices; this has Mipi DSI output (depending on the model). But I think a HDMI or display port to DSI adapter is much more convenient. Just hook it up to your PC/laptop as an external monitor. I still have a UV exposure box; maybe an LCD screen is an interesting upgrade. However I have a feeling that the PCB needs to be as close to the glass as possible to get a sharp image. Then again, developing the PCBs has always been a bit iffy but that is probably also due to me using laser printing on tracing paper which stays a bit translucent.

author: E-Design
author_rank: Regular Contributor
timestamp: January 22, 2022, 09:04:29 pm
content: I've had good success cutting boards with a low cost desktop CNC (3018), and I am able to turn out a decent smt board with say a few dozen components in a couple of hours from start to finish.Anything seriously complex or having too small pitch parts etc.. and I will send it to a board house.. but simple stuff is great to mill one out in a morning or afternoon.With my current setup, I cannot achieve 6 mil trace / space so I keep things to 8 minimum and 10 is comfortable.I am also interested to see what others are doing -- if it is somehow faster or can get finer geometries.@dunkemhigh, I have not had any problem with the copper rings lifting on holes.. could be the batch or brand of copper board you are using where the copper bond strength isnt that great.. Ive had a couple of those and when I found them, I purged them out of my stock. Additionally, could be a drill speed (too slow) or plunge rate issue.. or too much runout in the setup. I agree with a lot of dicking about get a good setup.. once its dialed in though, great results!

author: PlainName
author_rank: Super Contributor
timestamp: January 22, 2022, 10:45:47 pm
content: The pad lifting didn't always happen, but I figured the problem was too much torque for the width of the ring. Starting off with a narrow ring and then not getting the drill absolutely centered probably wouldn't help! Could have been a board quality issue, although nothing else seemed to be wrong with them.The switch to dry working wasn't necessarily down to one thing, just a combination of several irritations.

author: nctnico
author_rank: Super Contributor
timestamp: January 22, 2022, 11:38:04 pm
content: Over my life I have etched a large number of boards. Drilling has never been a problem but then again I have been using tungsten drills and a small (precission) drill-press.

author: PlainName
author_rank: Super Contributor
timestamp: January 22, 2022, 11:55:12 pm
content: There is a possibility that I'm just bloody useless at this stuff

author: Zucca
author_rank: Unknown
timestamp: January 23, 2022, 02:13:15 am
content: Quote from: TmaxElectronics on January 21, 2022, 12:59:59 pmYRW. Please consider to make them smaller and upload the pic to the EEVBlog.They will stay there forever, I hope.

author: TmaxElectronics
author_rank: Regular Contributor
timestamp: January 23, 2022, 11:04:47 pm
content: QuoteInteresting, never had that issue myself. I usually add a centering hole of 0,4mm to each pad, that way alignment ist pretty easy even when hand-drilling.The software has direct support for that btwYou can just add you NCDrill file as a gerber layer and select it as a drill guide overlay in the export dialog. Even allows you to modify hole sizes to be the same everywhere.QuoteOr you could just route out two edges of the PCB and align them to the edge of a metal sheet like the one I have on my printer nowQuoteI did run a print just now, and at a glance I don't see anything wrong with using the printer after the mod. It might need a little longer exposure times from the worse optical contact between LCD and glass but for my test the old settings worked fine (though they are quite conservative though).One more problem though...I just tried to de-laminate the glass from one of the original chitu replacements for the elegoo mars and it seem like they changed the adhesive. I just wasn't able to seperate the two parts from one another, not to mention completely trashing the display while trying, despite using the same method I was using the three times or so i did it before. So be careful if you try this, if it takes quite a lot of force you're probably best off calling off the experiment.It might be possible to seperate them with a lot of heat though, gonna have to make a setup to test that soon.

author: PlainName
author_rank: Super Contributor
timestamp: January 24, 2022, 12:09:17 am
content: QuoteThanks for the info (and the testing!). I am at the thinking it might be a possible project at the moment, so could be a while before actually trying anything

author: dirtcooker
author_rank: Regular Contributor
timestamp: May 03, 2022, 04:21:05 pm
content: @TmaxElectronics,nice project. The latest generation of these MSLA printers like the MARS 3 4k should be able to make very good pcboards. jlcpcb.com and others often have gerber file size limits of 5 or 10MB. This is not a limitation for most boards, but I have one project with detailed artwork, the gerber is 83MB (5MB compressed) and the board houses choke on it. I think it could be made using a 4k screen direct to pcboard exposure. I wrote a python program to generate the artwork as an 8192x8192 bmp and as an svg vector file. inkscape reads both files no problem, but svg2mod, kicad 6, blender 3 all crash. So I am unable to extrude the file for use in the MARS3. kicad's bitmap2component successfully converted it to a kcad_mod file in about 10 min or so, and I was able to produce the gerber.Thus I would like to avoid all the software conversions. The screens are available cheap, for examplehttps://www.amazon.com/ELEGOO-Inches-Monochrome-Resolution-Printer/dp/B08NTBN8S5Does anyone know how to hook this up to an HDMI board, so it can be plugged into a PC as a display device? This might work, I dunno:https://www.displaymodule.com/products/display-adapter-for-hdmi-to-mipi-dsi?variant=31902301421666This appears to be a complete solution:https://www.aliexpress.com/item/1005003493405410.htmlThere are numerous applications for this: B&W prints, microwave metamaterials and antennas, glass lab-on-a-chip (LOC) devices.This is what the PC board artwork looks like, with 0.2mm dia holes in an otherwise solid copper layer, over 100k of them on a 100mm dia disk.2023-3-30 update: I bought the Pengji 8.9 Inch 4k Mono LCD Screen with HDMI Board With 3840*2400 Resolution For Resin 3D printer, PJ089Y2V5 off Aliexpress and plugged it into the hdmi port of a linux mint laptop, which reports it as 1280 x 2400. Displayed images are 3x wider than they should be, but can be made to expose pc boards by scaling the artwork to compensate (see pics). 3840 = 3 * 1280, so maybe it could be made to display its advertised higher resolution by exploiting the RGB channels somehow.

author: thm_w
author_rank: Super Contributor
timestamp: May 03, 2022, 09:28:26 pm
content: Quote from: dirtcooker on May 03, 2022, 04:21:05 pmPJ089Y2V5 is listed as 8 lane MIPI, this thing says 4 lane.TM089CFSP01 not sure, probably the same.Also its listed as 50 vs 60pin in some places, so may not work.Interesting that these companies are building HDMI boards, I wonder what their end application is. People making DIY resin printers I suppose?

author: eugene
author_rank: Frequent Contributor
timestamp: May 03, 2022, 09:47:14 pm
content: DIY PCB fab might be relevant today. A benchtop CNC suitable for doing all the drilling could probably be DIY'ed for a few hundred dollars. Plated through holes would be nice, but we're talking about turning something around in a couple of hours. You can shove a piece of wire through the hole before soldering everything. Solder mask might be a luxury I could live without when prototyping. Might be a feature! Multilayer boards? I don't know.Good quality DIY PCB fabrication with fine pitch copper, well located vias, andnot too much artistic hand workmight not be an unrealistic goal.

author: ace1903
author_rank: Regular Contributor
timestamp: May 27, 2022, 08:35:18 am
content: Little bit help pleaseLocally I can find only Creality LD-006 SLA printer with 3840x2400 resolution.This resolution is probably with x3 interpolation since display is converted to monochromatic mode.Since I do not own SLA printer I do not know if I can use Gerber2Chitubox program for LD006, and if this program can make this conversion to monochromatic mode?Before investing in LD006 I would like to know if changes into software are needed and if this printer can make PCB with comparable results with Elegoo?My Java knowledge is not great but I think I can make small patches if needed.

author: TmaxElectronics
author_rank: Regular Contributor
timestamp: July 23, 2022, 04:20:57 pm
content: Right it seems my email notifications got disabled for this thread, so sorry for not responding for ages.QuoteInteresting approach. Did you consider maybe just using some normal monitor panel for this? Not sure about pixel pitch but you might just be able to find something that has the right density.UV should pass through it no problem even with the color mask, as the non monochrome versions of the chitubox printers still have it in place too (i think anyway).The biggest issue is likely to be scaling to the correct size.But incase you still want to make an adapter for the chitubox panels, you should find one that does 2x4lanes mipi. At least the panel on my early mars printer is split into two parts, each having its own independent interface. Thats likely the reason for the four/eight lane mipi confusion. I beleive the mipi standard doesn't even spec an eigth lane version of the interface.I was wanting to make a board that has an fpga on it generating the mipi data, which can read any file from an sd card. but I haven't yet had the time to do that yet. Might be worth attempting though, as the datasheet as well as interface specs are quite widely available now.Quoteyeah thats how I do vias at the moment too but its kinda annoying. I have seen somebody doing copper plating after treating the board with a graphite spray which is an interesting approach, but would require a second masking/plating step to prevent the plating in the holes being etched away again.QuoteIf I remember correctly, the data format is exactly the same as for the non monochrome printers.You should be able to test it my opening a normal printer file as exported my the chitubox slicer in this software:https://github.com/Photonsters/PhotonFileValidatorIf it can read and write the files then the gerber2chitubox software should be easily expandable to do the same as I use the fileIO core from the PhotonFileValidator to create the layers and output the cbddlp files.I'll look into adding custom printer presets once my exams are over

author: eugene
author_rank: Frequent Contributor
timestamp: July 26, 2022, 02:51:02 pm
content: Here's a 12.8" diagonal 6K monochrome LCD (supposedly) with HDMI input for $285 fro aliex:https://www.aliexpress.com/item/3256803602916144.html?spm=a2g0o.productlist.0.0.7b355607MJxHuA&algo_pvid=50919e2e-af03-4a06-990a-5237cf105407&algo_exp_id=50919e2e-af03-4a06-990a-5237cf105407-1&pdp_ext_f=%7B%22sku_id%22%3A%2212000027173881454%22%7D&pdp_npi=2%40dis%21USD%21%21285.0%21%21%21%21%21%40210318b816588466875221572eacce%2112000027173881454%21seaNot exactly dirt cheap, but if the HDMI works out of the box, then it could be a good start...Edit: I think I finally figured out that the second board - the one in the third photo - is the HDMI to whatever converter. The ribbon cable connects everything together. With essentially zero technical info in the ad, it's still a little expensive for me to take a chance on, but maybe some else will and report.EDIT 2: I see that the LCD alone is $285. The LCD + HDMI is $450. I expect that it's the same LCD that came in my recently delivered Elegoo Jupiter, so I'm thinking they should be available for less. More importantly, Elegoo is in the process of developing a resin printer with a10" 8k LCD. List price on the entire printer is $600, so replacement LCDs should be affordable when/if they become available.

author: eliocor
author_rank: Unknown
timestamp: July 28, 2022, 04:00:04 am
content: to my knowledge (never tested)UVtoolsis able to convert Gerber files to a format compatible to most resin printers.....

author: mag_therm
author_rank: Frequent Contributor
timestamp: July 28, 2022, 03:26:53 pm
content: I use an el cheapo HP2720 inkjet.The problem with ink jet is pin holes.By trial and error a color ( mix of the 4 jets) was found that has least pin holes on the transparent film.I use a vacuum jig to UV expose MG Chem single sided pre-coated boards.Can do only one size board, being a quarter of the 6 by 4 inch board.This example is mostly surface mount with about 9 IC.https://app.box.com/s/dx5jbzu1qgq1l47r05f2k7u26u7l6ldohttps://app.box.com/s/us5pjv7tmcmzwp5ldb81uv6bnzgszgcb

author: E-Design
author_rank: Regular Contributor
timestamp: July 28, 2022, 11:09:19 pm
content: Quote from: mag_therm on July 28, 2022, 03:26:53 pmWhat is the finest geometry you can reliably produce with your method? As in trace width and trace (space) gaps ?TIA

author: mag_therm
author_rank: Frequent Contributor
timestamp: July 28, 2022, 11:55:06 pm
content: Hi E_Design,I doubt that I will be able to challenge Tmax with 6 mil!Refer to the png image of the artwork in post # (The red artwork)At lower right is the smallest package I have tried so far being a TSSOP-14 Dual FF with 10 mil inch padsThe tracks and gaps around it are 10 mil.They came out in copper quite well.But that package caused difficulties in hand solder.I can more easily solder the SN74AUP... with ..DCK layout. This TI series has 5 and 6 pin packages with single device. They have 0.35mm pads (About 14mil inch) I used 10 mil tracks and spacing, and can get the soldering tip on 0.35mm pads easier.There are two of those at lower right of the artwork image.Regards

author: jz79
author_rank: Contributor
timestamp: October 10, 2024, 07:44:03 pm
content: Sorry for necroing an old thread, but this was the inspiration to try and ditch the methods involving laser printers, so I thought I'd report on a success, sort of...The msla printer I used was a new out of the box Elegoo Saturn 4 Ultra (because it had the high resolution 10" mono lcd, and it has a tilting feature that supposedly makes 3d printing a lot faster, though there are bugs with the whole design), and this is most definitely not an ad, I do NOT recommend it for this PCB exposure thing, because there is no easy way to just pop your image on the screen for certain amount of time, so get around this I you'd need UVTools freeware software, it is used for creating and editing 3d print files, it will open .goo (Elegoo format) files that you can feed from USB into the printer, so I took the example file that came on the USB together with the printer, deleted all layers, imported new layer using custom .png image (had to be resized, because pixel dimensions are 24x19 micron, they aren't square), then edit the layer settings, set exposure time and hit print, aaaand wait for it to go through all the pointless (for this purpose) actions, calibrating some mystical parameters etc, and then override couple errors to get your image to pop up on lcd finally.I initially tried couple dry films from Ali, the really cheap ones, and they are no good, it seems they are too thick and overall they have defects, like wrinkles in the dry gel that won't adhere properly, and the thickness seems to cause problems exposing narrow features, after exposing and trying to dissolve (develop) the resist, I can actually see crisp top layer of the features seen below (that is just a test image of TSSOP 24 with 0.1mm track weaving in between the pads), but the thin parts in between seem to catch some UV and partially cure also, making the developer a bit more concentrated kind of helped to dissolve some of it, but it also started to lift some other features, basically - a fail.I tried all sorts of things with the UV intensity settings, exposure time, but nothing really solved the above, the film I bought needed very short exposure, only 10 seconds, going lower started to look like underexposure, developer was kind of starting to attack the exposed resist.this is what it looked like overetched trying to get the pads to separateAnd this is the result with spray on positive resist called Positiv 20, manufactured by Kontakt Chemie, this was first time trying to use wet resist, made a spin fixture out from a pc fan with some double sided sticky tape to hold the pcb, sprayed the resist on, just a thin coat, it doesn't really spray that evenly, spun it for maybe 10-15 seconds, that leveled it reasonably well, baked for 30min at 60C.Exposure settings - 45sec, etching with plain ferric chloride, slightly warm, maybe 40-45C, etch time was probably 6-8 minutes, face down, constantly moving it

author: PlainName
author_rank: Super Contributor
timestamp: October 10, 2024, 09:53:39 pm
content: Nice!Well done

author: rajhlinux
author_rank: Contributor
timestamp: November 01, 2024, 07:01:41 am
content: Last year, I've found some tablet-like OEM displays in the range of 8K resolution.Edit:Oh wow, haven't realized the market has catched up selling consumers SLAs with 12K displays. Wow...Edit:Wait there are even 14K displays too?...

author: rajhlinux
author_rank: Contributor
timestamp: November 01, 2024, 07:23:19 am
content: Holy Shamoley, thats the most accurate PCB etch I've ever seen in a DIY style.What are the actual pixel size of the LCD? From my calculations for a 10 inch diagonal screen with a 12K resolution should be around 20 microns.Your PCB etching is thus accurate down to at least ~25 microns +/-.You might wanna give a try to Dupont Dry Film which are used for Laser series sensitizing lithography.

author: jz79
author_rank: Contributor
timestamp: November 01, 2024, 09:42:45 am
content: lcd pixel size is 19x24um (11520x5120px and 220x122mm screen size), I would have preferred a square pixel LCD, but it seems there is nothing like that in the 10" lcd size range currently, and I think the results show that the squareness of the pixel isn't that important, it is just a small inconvenience having to resize the "square pixel" image out of the CAD package to the 1.25:1 ratio so the final exposure is the correctI don't think dry films are worth the trouble to be honest, always tricky without a clean room and right equipment to get good repeatable results, I find the spray-spin-bake easy and quick enough process, and I think I'd rather buy a stack of presensitized boards from quality manufacturer like Bungard (I'm in Europe) to have something on hand rather than dealing with the dry filmbiggest "issue" for me currently is the closed nature of the firmware on the printer and the lack of support, there's a feature on the printer to show a test image to check if the screen is working correctly, it would have been perfect if this feature had a dialogue to browse and select which image you want to display on the lcd (time duration setting there is already present), mentioned it as an idea to the manufacturer, so they can potentially get additional customers to buy their product if their printer could be used for PCB exposures, but zero responseand it seems it is running most likely LinuxCNC under the hood, since the printer will accept G code, there is even specific G code to display an image, but it doesn't seem to work, the screen lights up blank, like it can't load the image I specified in the G code command, that would greatly simplify using this particular printer for this task, but even this simple request the support staff completely ignored - to explain how to display images on the lcd using G code...even worse is that the lcd driver is some custom board soldered right on the "motherboard" of the controller, I expected it would have hdmi interface like the mono LCDs controllers on ali do, and I thought in worst case scenario I could stick a raspberry inside there to run the thing, but sadly no such luck due to lcd driver interface, I did however find a script and set of tools to unpack the original firmware, but hadn't have the time yet to dig into it more to figure how to add the functionality I wantso, if anyone is thinking about buying a printer for this - avoid the ones that don't accept standard G code, and talk to support first just to get a feel if they are willing to help if any problems arise, because Elegoo, while rich on features on paper, are absolute garbage when it comes to solving issues with their products, I understand that 400eur resin printer may not have built in margin to fund extensive support, but not helping a user to tell them how to display an image on the screen using G code is no support at all, doesn't cost them anything, and it isn't like they can add to the price if they start to include pcb exposure as a feature when competition can do the same with just a Gcode command

author: rajhlinux
author_rank: Contributor
timestamp: November 02, 2024, 03:19:56 am
content: 19x24 microns = 456 square microns/pixel, that is not enough for my standards of accuracy, need something more in the range of <= 200 microns.Actually I think the area of the pixel is not useful in determining the accuracy of precision imaging, but rather the diagonal size of the pixel, for 19x24 microns and using Pythagorean theorem, the overall size light emitted from a pixel of the size of 19x24 microns should be ~29 microns (Diagonal Size). Which is great and can be used for many high precision PCB sensitizing.I agree, I've read about dry film usage in the PCB lithography process and it is really cumbersome to work with, everything needs to be clean and perfect and less forgiving. But I do know many of the state-of-the-art PCB fabs uses dry film.However when precision comes into mind, I think the spray/liquid photoresist on a spinner is the winner, hands down. Its the process used for making Integrated circuits on silicon, various methods are used. I agree it's easier to work with than film based and adds higher accuracy.Have you considered simply buying the OEM 12K or 14K LCD displays from Ali and simply design your own lithography box? I was planning to do this years ago when 8K LCDs were the highest resolution. However I simply decided to stick with something that is much more simpler to work with, using professional grade printers, particularly Epson Pro grade printers (they cost a pretty penny, buy them used after testing their accuracy of nozzle print checks). I've done many testing and completely shocked at the level of detail it can produce. I believe they are accurate down to 15 microns -/+. The interesting part about these printers is that their printhead nozzles are produced in a semiconductor fabrication process of lithography to produce ultra precise and small nozzles. Canon professional grade printers are good too and somewhat cheaper, produces excellent results, but their printheads are thermal based and doesn't give much freedom of using various types of inks compared to Epsons.My main ideal PCB lithography system would be a custom made ultra-precision, ultra-high-resolution scanning laser system, concept is similar to laser jet printers. As accurate down to sub microns. However building such device requires a PCB, and many high-precision machinists machinery and skills therefore need to start somewhere to produce fundamental PCBs.

author: coppercone2
author_rank: Super Contributor
timestamp: November 02, 2024, 03:48:51 am
content: lol that dry film shit, try this method1) clean sink good2) fill sink with water3) open dry film under water4) align with PCB5) pull it out slowly at an angle6) put into hot roller machine a bunch of times7) do again for other sideit sounds bootleg as hell but it works. i was losing my mind trying to do it in the airthe key is to use a big sink. trying to get tupperwares and shit is beyond ridiculous

author: rajhlinux
author_rank: Contributor
timestamp: November 02, 2024, 04:31:14 am
content: Yes I've seen people doing this and swears by it.

author: jz79
author_rank: Contributor
timestamp: November 02, 2024, 08:16:06 am
content: don't get me wrong - I'm not saying dry films are bad in general, just that the ones I tried were badBungard sells their dry film also, but smallest roll is 80EUR (0.3x25m roll, so that is a lot of film), and the issue with clean conditions to apply it still remains, I'm not going to bother using sink full of water, that is just too much hassle IMO when spray-spin-bake works just finequick google search showed that Dupont to be available from around 20EURand I didn't go for 12k 10"mono lcds from Ali because they end up costing around 200EUR and there basically is no warranty whatsoever, and a printer is 300~400EUR

author: coppercone2
author_rank: Super Contributor
timestamp: November 02, 2024, 09:48:48 am
content: how do you spin a board of substantial size? I only ever saw people make spin tools for little PCByou can do a 12 inch x 12 inch PCB in a fairly normal kitchen sink

author: jz79
author_rank: Contributor
timestamp: November 02, 2024, 02:59:00 pm
content: double sided sticky tape on a 2$ atx power supply fan inside a cardboard box... powered from lab power supply, since need to limit the rpm, no problem with 200x120mm boards, that is max what I can fit on the LCD anyway, anything larger I would most likely outsource, but I very rarely if ever need a board longer than 200mmthat was the big surprise for me that even a ghetto spin fixture like that ends up having better than expected results compared to dry films I tried, I didn't even clean the copper particularly well, the board was one of those cheap paper ones, and more than 40 years old, some scotchbrite to get rid of most oxidation, acetone to degrease, then spray, it had some unevenness even after spinning, but dried flat enough, if you ever spray painted anything and had seen water droplets from condensation in the paint, that is what the sprayed and spun coat looked like, but it turned out in the end just fine

author: nctnico
author_rank: Super Contributor
timestamp: November 02, 2024, 09:35:58 pm
content: Quote from: rajhlinux on November 01, 2024, 07:23:19 amIt looks good indeed but are there no shorts between the pads? There can be barely visible shorts between the pads if the etching wasn't completed. I have done etching with ferric chloride for decades but never went under 0.2mm trace width / seperation. Not because of the lithographic process, but due to the etching process. BTW, I always used pre-clad boards from reputable brands.

author: cunningfellow
author_rank: Regular Contributor
timestamp: November 04, 2024, 01:13:11 am
content: Quote from: nctnico on November 02, 2024, 09:35:58 pmSpray etching can help with that.

author: chickenHeadKnob
author_rank: Super Contributor
timestamp: November 04, 2024, 05:44:03 am
content: Quote from: jz79 on November 02, 2024, 02:59:00 pmWas your PCB 1 ounce (34 micron) or 0.5 ounce (17 micron) copper weight? The half ounce is better to get the really thin tracks without undercut.nice work by the way.

author: nctnico
author_rank: Super Contributor
timestamp: November 07, 2024, 02:00:13 pm
content: Quote from: cunningfellow on November 04, 2024, 01:13:11 amBeen there, done that. Spray etching is actually is worse because getting the spray pattern even is hard to do and this method etches extremely fast. If I would get an etching machine again, I would go for one which uses FeCl and foam.

author: Teal
author_rank: Newbie
timestamp: December 04, 2024, 10:42:10 am
content: I've been trying to get into this too but couldn't find any software that would work for me. So I wrote my own. The script converts gerber /svg / png files and patches Anycubic printer files with new image data.Maybe someone will find it useful:https://github.com/BleakyTex/Anycubic-PW0-ConverterI haven't tried to make PCBs with it yet but the display of my Anycubic Photon Mono 4 resolves 0.05mm traces and gaps.

author: chrome72
author_rank: Newbie
timestamp: May 29, 2025, 05:57:59 pm
content: This is awesome. Would this program work for other resin printers?i have the mars elegoo msla. I had some great success with the idea but couldnt get perfect alignment. Im not making PCBs but resist masks on metal prior to electroplating. I realized i can build a jig directly onto the build plate which will then hold my metal. Center the art, the build plate jig would be centered and I shouldnt have to worry about alignment anymore.I just need a better way of converting a svg to a stl to a sliceable file.

author: eliocor
author_rank: Unknown
timestamp: May 30, 2025, 03:01:53 am
content: @chrome72:see my previous (#21) message:https://www.eevblog.com/forum/eda/making-high-quality-home-etching-easy-66mil-pcbs-exposed-with-an-sla-printer/msg4325344/#msg4325344https://github.com/jaseg/gerbolyzehttps://www.eevblog.com/forum/eda/i-made-an-svg-vector-graphics-to-gerber-converter/https://forum.kicad.info/t/svg-to-gerber-kicad8-04/53000

author: Psi
author_rank: Super Contributor
timestamp: May 30, 2025, 03:09:41 am
content: Back when I was doing home etch, the only way I could get it to work reliably for doing 0.5mm pitch parts was to intentionally skew the sizes of the tracks to counteract the issue of track width shrinking due to copper side-etching. Which isn't as straight forward as you think it will be.Once I got that nailed down it was fine. I'd usually had a couple of track breaks that I needed to fix up but that was fine.I was using press-n-peal blue + warm HCL/peroxide etch.I never got to 6/6mil, but never needed to for the projects i was doing.Even when you get the etch process down the thing that kills you is drilling holes and via's. It was enough of a pain to make me switch to china PCBs. This was around the time when cheap china PCBs were starting to appear

author: jz79
author_rank: Contributor
timestamp: May 30, 2025, 11:20:03 am
content: Quote from: chickenHeadKnob on November 04, 2024, 05:44:03 amsorry for not replying for a long time, I hadn't noticed there were repliesI actually don't know the thickness of the copper, first tests I did was with some really old pcbs from soviet era, and the new ones I bought from one of the local stores don't specify the thickness, I'll try using micrometer on etched region next to copper, even 0.01mm mic should be good enough to tell if it was 34 or 17um, will edit the post laterregarding etching, I have not tried double sided, but for single sided I tried different things, all with FeCl warmed up to 45-50 degreesstuff that didn't work, or that I could not get to work:pumping FeCl using peristaltic pump to imitate spray, I did get it to flow evenly over the board, but the parts that get fresh solution etch faster than parts where it flows down, perhaps even spray like from a air paint gun might help, but requires high pressure, special nozzle, hermetic container etc, too much trouble in shortrigged up holder that holds the it horizontally and moves the pcb in solution up and down, resulted consistently in perimeter getting etched significantly quicker, middle always lagged behind, unable to get even track width across the board as consequencealso movement, but pcb is vertical, movement vertical - also inconsistent resultsI ended up just suspending horizontally with copper down in the tray, tray is heated from below, one of those silicone heater pads, no movement, no agitation, slower etching overall, but quite even across the whole boardalso note regarding the spray resist I used - thickness of the layer matters, it dries very quickly so spinning doesn't get all the excess off, spray only enough to have full coverage - thinner = better, more consistent developing results and no undeveloped whiskers or dots left on the board, it is probably linked to the UV exposure time, but I kept exposure to same time as before and go for thinner UV resist coat, at it workedand as someone mentioned - draw the traces slightly oversize to allow for slight overetching to reduce chance for dots, shorts, etc, for instance to get a 0.15mm track - draw it 0.17-0.18, but I wouldn't bother so much, this is prototyping after all, don't waste time trying to perfect this, use pcb supplier to get production boardsedit: measured thickness difference between etched and copper areas on some of the test samples with micrometer, and it is just over 30um, and all the tests I did took similar time to etch, not half of others, so safe to assume all the stock I have is 34um copper

author: chrome72
author_rank: Newbie
timestamp: May 30, 2025, 03:58:53 pm
content: Please bear with me because I am a total newbie to this part. I just have the will to want to create.If I have a highly detailed SVG design of a watch dial face (.45mm text) am i better off doing a SVG to gerber converter like you posted or importing the design into a different program and creating a very thing 3d STL model of it and then importing that into a slicing suite for my resin printer? I know they are essentially the same idea, but you had some text in your write up about handling complicated designs. I have lots of little bits and fine features.

author: eliocor
author_rank: Unknown
timestamp: May 30, 2025, 05:30:11 pm
content: I think you have to try by yourself: I do not know the exact printer model you have, but on mine, the pixel size is 35x35\$\mu\$m so it will be difficult to get a discernible text.... Maybe using a Mars 5 Ultra (18x18\$\mu\$m) the resolution is enough.The same is for the photoresist you are using: can it resolve enough details?In few words: make some tests! Only you know what you really want.

author: jz79
author_rank: Contributor
timestamp: May 31, 2025, 03:22:24 pm
content: Quote from: chrome72 on May 30, 2025, 03:58:53 pm0.45mm text is very small, and I don't think even 12k screens with around 20 micron pixel will produce a great result, meaning your 450 micron text height is only ~20 pixels high, that is not a lotfor this I think something similar to ic photolithography setup is necessary, meaning you'd be using oversized image source and then using lenses to shrink it to the size you need, maybe MSLA LCD could still be used to generate the oversized pattern, but you still need lense setup to reduce it to the size you need

author: chrome72
author_rank: Newbie
timestamp: June 02, 2025, 03:26:38 pm
content: Yes .45mm is indeed small! I have done this with photosensitive film and a transparency of the design printed at 1,200 dpi which is like 20 microns in detail. It works very well. My resin printer is the Mars 4 MSLA and I should be able to get 18 microns per the specs.I had looked into photo reduction but I read you lose a lot of the UV light during the reduction and that basically makes it a moot method. Do you know something more than me? If so I am interested in learning.

author: coppercone2
author_rank: Super Contributor
timestamp: June 03, 2025, 03:03:43 am
content: I was wondering about another technology, that is a display which can be put over the photo film and programmed to show the mask. It would need to be quartz glass and have very high contrastNot a projector, but a digital mask

author: jz79
author_rank: Contributor
timestamp: June 03, 2025, 08:03:40 am
content: Quote from: chrome72 on June 02, 2025, 03:26:38 pmcan't help you with anything practical regarding lenses, but using optics to get fine enough resolution at that scale is pretty much the only option as far as I know, in pictures I previously posted, when I was examining photoresist exposure and development quality, I was starting to see jagged lines from pixel edges, I did couple tries using anti-aliasing on the b&w image that I import into the layer using slicing software, but it didn't do much, since even trace amount of photoresist is preventing etchant from removing copper, it does work for smoothing resin prints, but here - not quiteI remembered there was this channel on YT, I looked up the channel name, but don't recall details of the videos, but afair he was using microscope optics to focus UV light, scale is wrong for you, but perhaps something from photography lenses can be used, you'll lose some UV of course, but longer exposure time should fix thatI think Mars series printers use DLP mirros to form the image, my Saturn is monochrome lcd pass through, so perhaps that mirror and the surface it projects the image on to is already taking care of antialiasing, and that is why you don't observe pixel edgeshere is that YT channel, maybe there is something useful for you therehttps://www.youtube.com/@SamZeloof/videos

author: chrome72
author_rank: Newbie
timestamp: June 04, 2025, 07:34:36 pm
content: Thanks. Projection is the original route I had started looking into before I found the resin printer idea (plus my kids would get a kick out of having a resin printer). I have refamiliarized myself with this method and I think all i need is a UV light, a collimator, and a lens that reduces the image.Since I am not looking for .005mm bits, I think i could get away with a slide projector and modify the lens. Here is what I am thinkinghttps://clickpix.org/image/2RywYQ

author: quadtech
author_rank: Regular Contributor
timestamp: June 05, 2025, 07:45:49 am
content: Quote from: coppercone2 on June 03, 2025, 03:03:43 amLike so?By far the best results I have seen of any diy UV PCBs are from the "Alphacrow HLDI" projecton the Russian Radiokot forum - there is a huge thread on it there. It uses a linear encode tape froman inkjet printer on the X axis to fire the laser at the correct X position.DC motor on X axis, stepper on Y.Really fast and they also use the same machine to expose the UV soldermask with great results.X - Axis - you could pretty much use the guts of a Canon printer as is. The Y Axis is relatively easy as thepcb moves in one direction only, so no backlash to worry about. A simple stepper + belt would do.