diy etching pcb's - Page 1
Forum section: electronics / projects

author: p.larner
author_rank: Frequent Contributor
timestamp: January 05, 2024, 06:57:17 pm
content: I just wanted to share what i use to etch boards,for the etchant i use a mix of hci concentrated mixed with hydrogen peroxide,i used to put it in a disposible takeaway food container and pop it in the microwave to warm it,now i use a slow cooker,i put water in the ceramic cooker dish then float the food contaner with the pcb to be etched in the water in the cooker with it on the low/warm setting,i also have an aquarium fsh tank pump running with the air pipe with its open end under the etchant mix,held there with a crock clip,it seems to work well.

author: Dan123456
author_rank: Regular Contributor
timestamp: January 06, 2024, 12:24:35 pm
content: Yep, that would work 100%Just be careful though as the fumes will oxidise pretty much anything metal they come into contact with really quickly as you will have a mix of HCl fumes, oxygen and some Chlorine gasI remember I was using the same mix for chemistry purposes in the past and pretty much everything metal around me has a layer of rust on it by the time I was doneAnyways, figured I’d just mention it incase you are using an expensive slow cooker as it could cause it to fail prematurely

author: p.larner
author_rank: Frequent Contributor
timestamp: January 06, 2024, 09:33:24 pm
content: its an old cooker thats ready for the bin so no worries can relate to it rusting thngs ie its vapour!,everything here has a red/brown tint to it!.

author: shapirus
author_rank: Super Contributor
timestamp: January 06, 2024, 09:43:47 pm
content: What's the point of using dangerous chemicals (HCl) that produce further dangerous substances (Cl) when the mix based on hydrogen peroxide + citric acid is not dangerous (until it has copper dissolved in it), easily obtainable, and works just fine and produces perfectly etched boards in minutes even at room temperature?...to be specific:100g of 3% H2O2 solution30g of citric acid5g of NaCl (this acts as a catalyst)

author: Dan123456
author_rank: Regular Contributor
timestamp: January 07, 2024, 03:12:02 am
content: Quote from: shapirus on January 06, 2024, 09:43:47 pmThat mix is basically the same thing with extra steps going on in the backgroundWhat you are doing is making the HCl “in situ”Without going into a full chemistry lesson, the salt is dissolving into Na+ and Cl-, then the Cl- is grabbing a H+ ion to form HClAll that said, you are probably right that it is probably a little bit safer as you don’t need to have concentrated HCl lying around (although HCl isn’t particularly scary so long as you respect it and use common sense such as wearing gloves and goggles when using it and don’t huff the fumes)

author: Teledog
author_rank: Regular Contributor
timestamp: January 07, 2024, 03:47:58 am
content: Be careful with the peroxide /acid mix in the kitchen stainless sink (or any stainless steel drain fixtures)Rinse it off immediately. Any leftover drops will corrode even stainless! (and GF will not be happy!)

author: MathWizard
author_rank: Super Contributor
timestamp: January 07, 2024, 06:31:37 am
content: I would like to try some of this stuff, but don't want another box of stuff. IDK where to but the chemicals either, I bet it's like everything else tho, expensive, and heavy to ship. And probably only sold in little bottles, so they can charge more.I would hope that some people living in the right city, could buy most any supplies they'd ever need for EE, locally.

author: shapirus
author_rank: Super Contributor
timestamp: January 07, 2024, 09:03:55 am
content: Quote from: MathWizard on January 07, 2024, 06:31:37 amIs hydrogene peroxide solution sold in Canadian drugstores?

author: Dan123456
author_rank: Regular Contributor
timestamp: January 08, 2024, 06:18:47 am
content: Quote from: MathWizard on January 07, 2024, 06:31:37 amIt’s actually not too expensive to doThe most expensive part by far is just the copper lined fiber glass board (I.e. the blank PCB)Other than that, I would just start with some ammonium persulphate as it is pretty safe, comes in a powder/ crystal form and is cheap and readily available online (and you can usually pick it up at your local electronics shop too)For drawing your layout, you can just use a sharpie! It probably doesn’t give the best results but worked shockingly well for me when I was doing some testing in the past

author: deepfryed
author_rank: Unknown
timestamp: January 08, 2024, 06:32:27 am
content: Quote from: Dan123456 on January 08, 2024, 06:18:47 amYou'd have better results with a fine tip permanent paint marker. If you make a lot of prototype PCBs, it might be good to invest in a decent desktop engraver that can be used to isolation mill tracks and drill holes. I pretty much use that now instead of etching PCBs. You can probably build one cheaply with aluminium extrusion, cheap ballscrews, steppers and a grbl stepper / breakout board. 10 mil / 10 mil is very doable with a good 0.1mm spiral engraving tool.

author: Dan123456
author_rank: Regular Contributor
timestamp: January 08, 2024, 09:36:55 am
content: Quote from: deepfryed on January 08, 2024, 06:32:27 amAbsolutely! I have found blue Dykem works amazingly!Just make a stencil on paper, cut out the tracks then tape it to the board and paint on some of that and you are ready to goThe sharpie still works reasonably well though, especially for someone that just wants to give it a go on the cheap as pretty much everyone already has a permanent marker lying around

author: soldar
author_rank: Super Contributor
timestamp: January 08, 2024, 11:06:52 am
content: Forty years ago I used ferric chloride but I haven´t made a PCB in decades. Now I wouldn't even know where to find ferric chloride.Reading this thread made me realize I have a 5 L jug of muriatic acid that's been under the kitchen sink for many years. I bought it for the pool but never used it. I wonder if it is still good. Maybe I can start tinkering with making PCBs again.

author: elektryk
author_rank: Regular Contributor
timestamp: January 08, 2024, 12:26:21 pm
content: I use ferric chloride (FeCl3), it works but its stains are terrible.I can also recommend chinese photosensitive dry film, it gives slightly better results than painting traces manually.

author: pcprogrammer
author_rank: Super Contributor
timestamp: January 08, 2024, 12:41:30 pm
content: Why bother with all this when it is dirt cheap to get a 2 layer PCB made in China. It looks fare more professional with solder masks and silkscreen. No tinkering with having to connect the sides together when using a via, etc.Sure one can have it as a hobby, but for me the choice is made easily.

author: elektryk
author_rank: Regular Contributor
timestamp: January 08, 2024, 12:51:55 pm
content: This way I can design and make PCB prototype in a single day but only 1 side makes some sense to me, for 2 sided it's a waste of effort.

author: pcprogrammer
author_rank: Super Contributor
timestamp: January 08, 2024, 01:43:01 pm
content: Quote from: elektryk on January 08, 2024, 12:51:55 pmFor that I use the breadboard type of pcb and solder wires to make up the circuit. Probably just as fast as messing around with drawing on a copper surface, etching it, drill the needed holes and then solder.But each his own

author: jpanhalt
author_rank: Super Contributor
timestamp: January 08, 2024, 02:18:10 pm
content: I agree. I used to make frequently PCB's, both single- and double-sided using positive photoresist. It can be done quickly, but as time passed, I did it more and more infrequently, so now it is a lot of fuss to do. I switched to solderable prototype boards. See attachments. For layout, I made a device that was just a trivial symbol and a package (capture 1, the 0.1" grid is toggled off). With my version of Eagle, I only have 2 signal layers. I can use one (bottom) for existing connections and the other for wired ones. I use a short dash in dimension layer to indicate existing connections that must be cut. For something really simple, I don't even bother doing that. All in all, it is a little slower including assembly, but not by much.EDIT: For assembly, i print a version with the grid and number it. Then cutting jumpers to the correct length is quite simple.

author: elektryk
author_rank: Regular Contributor
timestamp: January 08, 2024, 02:34:01 pm
content: Quote from: pcprogrammer on January 08, 2024, 01:43:01 pmWhy not both?Here's Bluepill and a custom PCB with AVR64DD32, I know that there are SMD adapters (sometimes not matching the breadboard), but by doin' custom one, I can check footprint and I'm sure that VCC capacitors are close enough to the IC, which isn't that obvious on a breadboard.

author: shapirus
author_rank: Super Contributor
timestamp: January 08, 2024, 04:27:33 pm
content: Quote from: pcprogrammer on January 08, 2024, 12:41:30 pmSometimes the whole point is in doing the board yourself.Otherwise, quick prototyping. And often the prototype and the final board are the same thing.Quote from: pcprogrammer on January 08, 2024, 12:41:30 pmHomemade solder mask and pseudo-silkscreen are quite possible.Here's an example of a 2-layer board:Too much effort for anything beyond 1 pcs of a given design, though, or anything larger than, say, 5x10 cm.

author: E-Design
author_rank: Regular Contributor
timestamp: January 08, 2024, 04:40:18 pm
content: @shapirius what was your workflow like to produce this Protoboard?Also, if not stated already, my main reason to DIY a prototype like this is it isFAST. One can make a couple of iterations on these in the same day. You cant get that kind of service with the low cost houses and domestically, the cost is outlandishly unreasonable.

author: shapirus
author_rank: Super Contributor
timestamp: January 08, 2024, 05:13:20 pm
content: Quote from: E-Design on January 08, 2024, 04:40:18 pm- kicad- print normal and mirror images of each side on transparencies, put the two for each side together, ink facing ink, then make an "envelope" from front and back copper prints- apply dry film negative photoresist onto the bare board- put the board into the envelope mentioned above, cover with a piece of glass to press the transparency to the board, expose- flip (make sure the board doesn't move inside), expose again- develop- etch- repeat the procedure with liquid solder mask for both sides for the solder mask layers (more details in the recent solder mask topic in the beginners section)- use a different color liquid solder mask for the silk screen layer(s)- drill holes- use tinned copper wire to simulate vias

author: Spar59
author_rank: Contributor
timestamp: January 08, 2024, 06:07:53 pm
content: I concurr - be wary about where you store it.I used some of my Hydrochloric to shift limescale from the loo bowl and left the container (lid screwed on) adjacent to the loo in case I needed to re-apply, the screw cap was obviously not airtight and some fumes escaped and did a damn good job of trying to strip the chrome plating from the towel radiator!!!

author: MathWizard
author_rank: Super Contributor
timestamp: January 10, 2024, 05:51:33 pm
content: Quote from: shapirus on January 07, 2024, 09:03:55 amYup, but I don't think it's very concentrated, not the medical stuff at a drugstore.I have a bunch of copper clad boards, and I have a few tools to try cutting pads for deadbug/island projects. But yeah, I'll have to look up some guide on it, and see what I'd really need. Things like glass jars, it's nice to reuse them, so besides a few chem's, I guess I can;t complain.

author: shapirus
author_rank: Super Contributor
timestamp: January 10, 2024, 05:54:49 pm
content: Quote from: MathWizard on January 10, 2024, 05:51:33 pmVery concentrated isn't needed. 3% is fine. I posted the proportions a few posts above. It really does work, and the beauty of it is that it doesn't require anything beyond basic commodities.