How to Solder Mask PCBs
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- เผยแพร่เมื่อ 30 ต.ค. 2017
- Check out the tutorial for list of parts and supplies: learn.adafruit.com/how-to-sol...
Wether you're etching or CNC milling your own PCBs, the copper layer on the substrate will eventually begin to oxidize and rust. The best way to prolong the life of your PCBs is to give them a protective coating. This is where PCB Solder Masks come into play.
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Just an idea: keep the transparent film but try spreading the mask with the something flater, like a piece o thick plexi (or even glass), and add "stopping guides" to the sides of the piece, like scrap PCB with some layers of duct tape, to give the thickness you want. Basically, make a jig.This should give better consistency and control than just using your bare hands.
REALLY helpful to see your failures. I have an older brother, so I'm used to having others' failures be a cautionary tale for me. :) Great work.
One thing I did with my DIY pcbs was use a UV nail light I got off Amazon. It had something like a 30 second or 1 minute timer which was more than enough time to cure the resin. Great job with this tutorial.
Talking about the cleaning up the unexposed solder mask, you can use a warm bath of Sodium Carbonate (Washing soda) to strip the mask really easily, you can also use a more concentrated bath in boiling water to strip off the under-exposed solder mask from your failed boards too.
Neat idea. A couple of thoughts:
The UV transfer is very similar to the process used to create a screen for screen printing shirts and such. In that domain, much more precisely controlled UV light, e.g. in a dark room with a UV table is the normal pro setup. For us amateurs, you could better approximate with a less powerful UV source (halogen lamp) for a longer cure time. You can do this in a darkened room lit by a yellow 'bug' bulb. If you keep the lamp a fixed distance away, there are test sheets that can help you figure out the right cure time. (You uncover part of the pattern every so often to test different times.)
Getting a really dark mask is also crucial. I've had good luck doubling up laser printed sheets, darkened with a light coat of spray clear.
I always apply the resin as thin as possible. It doesn't look as uniform a color, than when you apply it thicker. But it works a lot better. No more peeling of the resin from the pcb.
Cleaning the pcb is very important.
My last suggestion is to expose it a lot longer. I expose for 9 minutes, with two 1watt UV leds, at a distance of 15cm (6").
For my initial (cnc milled) prototypes I just go around tinning all the pads, then hit up both sides with spray paint. Once dry I take a soldering iron and touch each pad for a second to burn off the paint. Looks pretty good actually... but once I'm happy with the design I have 10 professionally made by a Chinese shop. Might have to try this out though, looks fun!
Hi, thanks for the video. I found the following:
1. I used laser print OHP film
2. I placed the printed film Toner side down on the board, carefully aligned and held with masking tape. Then flapped open to apply resin.
3. I used much less resin than you did. At a guess the amount you dispensed would have done me a board at least twice that size.
4. I squeegeed the resin using a thin steel “scraper” direct on the back of the film - part of a set I bought in a pound shop. Possibly a blunted Stanley blade would do. Plastic scraper too flexible across the width. Using that tool allowed me to push as well as pull the resin to even up the thickness a bit.
5. An exposure of about 15 secs at close range from a UV torch did the trick. You can check if the resin is cured without peeling by gently pressing on the film with a fingernail.
6. On peeling, much of the uncured resin came away with the film and a light wipe with isopropyl alcohol removed the rest.
Very interesting. I never even considered putting a mask on my milled PCBs. Will try it out now.
Save cutting the pcb's out for last. Mill the circuit paths, but don't cut the border out until you've applied the uv mask. This will reduce the issues you're seeing on the edges of the PCB after the uv mask has been applied.
A little tip I've discovered, is rather than going through the process of lining up a whole bunch of layers of to light blocking mask I found that (my printer at least) is accurate enough you can just run the same page through the printer a few times to gets the appropriate thickness of ink on the transparency. Just ensure care when you put the paper back into the tray to go through consecutive times.
First one came out great based on your video. Thanks! (10 seconds exposure from 3.5 inches above, then cleaned, then another 10 second exposure without the films.)
I've been waiting to do this for so long!!! Thank you so much.
Thanks, very helpful! I've experience with UV for etching boards (I use acid bath). I print the mask using laserjet printer on a transparency in reverse (i.e. mirrored), then I completely blacken it using a high-flow flipchart marker, then clean it off by wiping it thoroughly with a paper towel. This helps increase the mask contrast / blocking capability and has worked great for me. Maybe it could be used here as well. Because the print is mirrored, the print side goes directly onto the board, without the film between, this improves sharpness of the exposure.
method I used. print 3 layer pad template for even longer UV exposure. use a glass for better thickness consistency on spread, cutout the outline after masking done. And lastly tin plate it for exposed copper with stanum solution. help protect unsoldered area and soldering time. Gave a very good result.
complete solder work and then spray on silicone or acrylic conformal coating, job done
You can use a nail salon uv ligh. 36w of uv. It will be more evenly exposed and a fixed distance too. As another person mentioned, you can use a test pcb with strips on it for the timing. So you peel at 5 seconds, then 10, 30 etc.Also as another pesron mentioned, use a jig to get consistent even thickness of the paste.
oh lol, you summarised above (which are also the top) 2 comments
You should use a lab stand or a box to hold the light at a steady constant distance. Using a box would also help with light leakage.
10 seconds..impatience on another level 😂😂
How about milling the mask pattern into a sheet of transparent acrylic, filling the pockets with black paint? You could drill some holes for locating pins while you're at it.
You can also print on tracing paper with laser printer, and then add acetone to shoebox cover bottom and place paper on top for fumes to make thick layer of black
have to agree aplying the solder mask with a silk screen is so easy you cant get it wrong and its perfect everytime then put you transparancy with the ink markings on top then cure
Nice video but you forgot the Rosin Cleaner ! It makes the solder bridges easier to see and makes the board look much better!
Sharpie's are dye based. You'd be better off using a marker with a more solid type of pigment. Basically dye is like window tint film. You can make it really really thick but it still doesn't completely block out all of the light.
Dye just kinda sucks. I learned the hard way when I used to paint cars and a bozo decided to mark up a car with a sharpie showing what he wanted me to fix.
There is another video I watched recently on solder mask. He used a piece of glass to smooth out the surface. His results looked pretty good.
In my experience your issues with adhesion appear to be due to prep. Your product is sticking to the plastic instead of the PCB. You probably need more tooth (light sanding/scuffing) on the PCB surface, and a better cleaning solvent. When it comes to automotive paints these are some of the most important products and steps of the process. Most painters are religious about what they do and use for prep work. The wrong solvents will just spread out contamination making bigger problems. I used to wash my hands with Palmolive dishsoap only and used it for wet prep/sanding too. I won't shoot anything unless I have PPG's wax and grease remover... Even if I'm shooting with another manufacturer's paints... Prep is 99% of the job.
-Jake
This is the video where he used glass for the solder mask:
th-cam.com/video/Vj_cdBZO1Tk/w-d-xo.html
Would you recommend a marker better than sharpie?
Thanks for the video! Nice idea!
My solder mask can not be dry Does it need stronger uv lamp ??sometimes companies says their uv solder mask supported for example 3kw uv lamp can i dry it with a 36w uv lamp but more time??.
Since you're milling the PCBs already, why not just fully expose the mask then mill out the pads down to copper?
the copper are thin, probably you'll ended up ruining the traces
@@pierreuntel1970 Not if you use a spring loaded bit
@@pierreuntel1970 No he is not. There is a example of milling PCB mask
th-cam.com/video/7EctuSTL7-w/w-d-xo.html
I don't use a spring loaded bit since I didn't want to spend $200 getting a kit from WEGSTR. I am milling my pads though with help of an auto leveler.
I think you need mask the most between pattern so that solder get isolated for smd.
If you mill after mask you lose mask where you need most
A tube painted black on the inside with the PCB at the base out in the sun for a bit works well too.
Now i know how to use solder mask thanks :)
FYI... to help you out what you can do it take 2 older or bad pcb boards place it on both sides.. take some card stock or cardboard from like a cereal box to add more space for the gel.... use a good roller like a pcv tube or a metal putty knife.. plastic ones will not have a good enough edge.. and scrap it with that ... you will get an even coat across it every time
Omg thank you so much for this video which i am looking for
I've seen videos where they use a silk screen mesh to apply the UV resin. This seems to leave a more homogeneous layer of resin. I'm going to try this method myself, since I had the same issue.
Nice vid! Thank you!
May it be possible to double print the same sheet? PS The entyre project would be awesome
Really Good job. i like it and subscribed
spin coat it, bake it for 1.5h at 70C to make it solid then expose then remove unexposed with acetone
Very much thanks for informative video
nice bro, this looks like easily than other ways
Very good work.
Does scratching the layer remove the film in case you accidentally cover the holes or soldring pads?
Using 90T screen printing mesh gives good results for spreading mask on PCB and is way more error-prone than spreading it using flat surface.
Is it possible to apply solder mask on sides of the board as well?
will using screen printing makes more even coat ?
Try using spin transfer?
you could make a jig of sorts that will measure an exact mil thickness for the solder paste or in this case, resin. i believe an alum can is what some people use.
Are you printing simply "100% black" onto the transparency film, or a rich black (for example 50 cyan, 50 magenta, 50 yellow, 100 black)?
can you put mask on pcb then mill it. don't know how it will take milling.
What CAD software do you use ? Please provide a list of supplies and links.
Wonder if you could do this with an SLA 3d printer
Thanks for sharing. However I would suggest first doing the mask and only later drilling through the pcb.
donde compraste esos botones con membrana?
I love utube, learning channel
I might try spinning them.
Can we use mobile phones screen protector?
Since red is on the opposite end of the [visible] light spectrum from UV and a material's color is what light frequencies it doesn't absorb, it may be absorbing more of the UV than the others do. The result would be better curing around the fine details of the artwork.
Note: This is only speculation, since it could be reflecting as much UV as the others and we wouldn't know it since we can't see it.
hy in your mask you use
catalyst ? or just the mask ?
Hi! What happens when the solder mask is over-exposed? Is it as bad as under-exposed?
It is possible to just CNC the raisin out?
@Adafruit Indestries,
Hey plz can u explain me how to make the pads on PCB design black in colour in the EAGLE SOFTWARE.
✌👌
if your using a cnc, then milling the paint off the pads after and just exposing the whole thing might be easier
Looked how to apply silk screen as a pcb I cleaned up had the silk screen peeled off the edge - I know pcb is easy and cheap to get made nowadays and now I wonder if people still do this...
Hi nice work. May i ask where you got your pcb holder from. Best regards james
I'm using a panavise Jr. you can find them here: www.adafruit.com/product/151
Adafruit Industries thankyou
where do you buy your mechanics UV solder mask?
we can use regular printer ? not a laser printer ?
what a printer serial u use??
What if I over exposure the mask?
where i can buy tube like in the video ?
Can you pls share pcb mask material supplier details (green, blue and red color material paste)
Hi all,
Does anyone know what the energy board at 5.30 is?
Interesting video. Tried to click through to the tutorial/parts/supplies list but the link in the description leads to a 404 page. Thanks!
You can always try eBay for instance...
Nice video
Hi There, Could someone tell me that how could i dilute the solder mask paste , to make it more liquid? Thanks
Is solder mask the same as photoresist film?
I want to buy these solder mask plz share online link if possible
I wonder if you can just screen print on a pcb to make the mask? If so, what sort of dyes would you use?
you would still use these types of solder mask "dye". UV curing would still need to be done. this is because you need the solder resist feature.
use a heavy piece of glass instead of acrylic to even spread the resin
how to make your stand solder?
So what’s the process to make your own pcb ?
Ninja Gaiden NES game - nice. ;)
By the way: why do you use multiple layers of transparent mask? I may be wrong, but perhaps re-printing on same, single transparent film multiple times would give you enough darkness without the hassel of working with multiple layers. A printer does not care is your paper or film is blank or not - it will spray another layer of ink on top of previous one anyway.
Been there, done that. Problem is, your printer is not accurate at all with the orientation of the sheet, this will result in misaligned layers, inevitably.
so, in short; if you need professional looking boards and don't mind waiting... go to a board house :p nice to know if you can't wait though. Is there a lifetime on the resin like there is on solder paste?
Since the mask reacts to sunlight, to I have to store it in darkness? What about working in with daylight? Is it a problem?
You could have just used the tStop Layer for that purpose...
I wanted to see what happens with UV over exposure. Surprised that it is compromised with more than 20 seconds.
Eu não sabia o que usar para pintar a placa porque drpois que ela é confeccionada não tinha como pintá-la.
what about the black one? have any of you guys used it? lemme now how it was
Wish I had a cnc!
Factorio thumbnail :)
Ok, as you say this seems to be a bit of a fiddly and error prone approach. Some ideas for alternatives that pop to mind.
1. If oxidation is all you are worried about it is probably faster to either tin the copper by hand or use a chemical tinning solution (although this last involves using chemicals which you might not like)
2. If for some reason you really want the masks specifically then perhaps using a vinyl cutter is a better approach than using inkjet or laserprinted UV blocking prints. Just cut what you do not want covered in solder mask (same as with the inkjet) into a vinyl sheet. Use the same transfer tape that is almost always used with vinyl cutters to transfer the trimmed vinyl cut-out to the PCB directly so that the vinyl covers your pads, via's etc. You can add art too if you want. Vinyl cutters are fairly accurate and cheap these days). Then all that is left is to spread the solder mask on the PCB (the vinyl will prevent it from getting on the pads). You can cure as long as needed since there is no risk of the UV shining through the inkjet printed blocking print. When cured just peel the vinyl from the board to reveal the pads again.
As long as you don't have too thick a layer of solder mask on there the vinyl should peel of easy no?
I found that the type of plastic sheet you use on top of the resin is an important parameter. Transparent sheets for laser printer will tend to stick too much to the resin. I use transparent vinyl sheets and longer UV exposure for reliable results (using a proper UV exposure unit helps a lot).
Also, the artworks (traces and solder mask) can be exposed to acetone vapor for about 1h at ambient temperature, the toner will dissolve and wet the surface evenly. This will make the black areas even more opaque and should not change the widths if it's timed correctly (you can overdo it). You still need to double up the artworks but it's worth the effort. I can handle designs with SSOP packages and such at home using this method.
Couldn't you just use some kind of mold release agent on the plastic you're laying on top of the solder mask
Yay!!
Good
This guy's voice sounds exactly like NileRed
100%!!!!!!!!!!!!!
Yeah, it does.
A lil more nasal tho
What's wrong with over-exposed UV? I mean, it can go in the sun afterwards anyway. So will sunlight damage it? If not, why not "over-expose" to avoid wasted PCBs?
Oh, I see. The light might get past/through the dark spots in the overlay. I guess one could hold the flashlight farther away, to avoid high angles of UV penetrating from the sides of the ink. And use 3 or 4 layers of overlay. Just a thought.
Convert your paste form into spray form
you could probably spincoat an even layer of solder mask
Interesting video but I think it was done better in the past. When I would make PCBs I would start with the same materials but would etch in a solution that was made for such purpose. There was no guessing or torn traces like this. The solution removed completely anything that wasn't covered by the mask.
where did you get that clamp?
That's a Panavise Jr www.adafruit.com/product/151
Why do you export pads layer and manualy touch it, when you can just export soldermask layer which is made just for this???
You need quartzglas for UV
The oxidization looks super cool and steampunk.