DIY solder mask theory (And a big one, need helllllpppppp)

[Zben3129]

Yes, the wax idea does sound good.

A mask for the solder mask

I think you are on to something with the laser engraver, though.

For paint, I reccomend to just try a few options. Try to balance between effeciveness, ease, and cost. I'd reccomend clear, aswell, 'cuz it looks cool 

Have fun with it!

Zach

[frank]

About the "paint", I could search in plastic properties in my technical books.  But surely than an experienced guy will give you a better answer.  You will want a cross-linking plastic I think, so it won't melt with heat after.

[juse]

i actually want to spray the whole board with a paint and then use the same laser engraver that i made the board with to quickly take off the paint on the pads. all i'd gave to do is modify the original artwork so that it had only the pads and not the traces. the laser takes acrylics, enamels, and urethanes right off the coper and fiberglass. i mostly just wanted to know which paints people use to make the soldering masks.

Hi Darron,
On production boards, fab vendors typically use either green LPI in a silkscreen type method or they use Dryfilm (much nicer looking IMO but not really applicable in your situation), so maybe you could research the LPI for characteristics to emulate for your mask & help you choose a good paint.

What you are doing sounds really cool. So you have a laser, huh? I looked into a small one once & it was about $16,000 so I realized that it was out of my league. You could do so much with one, etch the boards & boxes too. I envy you...... 

I came up with my own tinning process. It's common in the industry - or used to be, before solder mask was common - to roller-tin PCBs.

R.G. - Very cool method for the tinning. It appeals to my minimalist side.

[darron]

juse, what's LPI? google didn't give me much useful. i've got some screenprinting ink left over so i'll give that a shot. thanks (:

you can get small lasers from china that start at around 4,000 or so. i got the idea after i got some routing work done. i'm getting an epilog laser though which cost me about $20,000AU. it's getting delivered next week. i've tested it on hammond enclosures and pcbs to make the mask for etching. VERY quick and easy. i also cut a small scratchplate from wood in about 20 secs. a few things that i was thinking of doing for DIY stuff was making some of those plexiglass bottoms that popped up in the pictures thread. if people had ones they could buy that perfectly fit then i think they might want them. i'd also consider etching the B and BB enclosures, i'm not sure if it's worth my efforts though. if it's one every now and then for people it would be alright. if i do the mask and they do the actual etching themselves then it would be heaps easier (:

[juse]

juse, what's LPI? google didn't give me much useful. i've got some screenprinting ink left over so i'll give that a shot. thanks (:

Sorry, LPI stands for Liquid Photoimageable. If you ask Google about that he'll tell you more than you ever wanted to know!

The laser I considered getting was the Epilog Mini 18. Nice machine. I can't justify it unless I was to go into business for myself with it. So, I'm stuck with the liquid etching. Be sure to post some of your stuff when you get it up & running. You'll probably etch everything in the house when you first get it.

[darron]

the mini 18 is what i'm getting. it actually won't really etch aluminium, and DEFINITELY won't dent copper in the slightest. it won't even cut through fiberglass because it sees the glass as a mirror and bounces most off it off. same with the copper. so i'm still going to be using the acid. the fact that it doesn't burn off the copper is what makes the soldering mask possible, i could paint on the copper and laser it and the copper will remain perfectly intact, undamaged. their fibermark machine does metals, but i'm not going to buy a laser just for a little diy hobbie of mine... if i was in production  i'd consider it, but even then it wouldn't be worthwhile. you bet i'm going to etch everything in my house!!! once i've got a bit of practice i'll even shove my mac book pro under there. if you youtube it, you'll see that there's so many more applications than you can think of. still, i'll need to find ways of doing boring stuff to help the machine pay for itself. i'll need to find the spare time to do it, but the plexiglass etc, will be some idea i'll want to do. i'll take a look into LPI. thanks! (:

[R.G.]

... i'm getting an epilog laser though which cost me about $20,000AU. it's getting delivered next week...

Holy Moley, Batman! 

How many PCBs can one buy for $20,000 AD?

[jpm83]

Here is my tonights experiment.

By jpm83, shot with Canon PowerShot A70 at 2008-02-25
I first fluxed the board and them melted a blob of solder to the tip of iron and then transferred the solder to the used desoldering wick and run that over the traces and pads.

Janne

[juse]

Here is my tonights experiment.
I first fluxed the board and them melted a blob of solder to the tip of iron and then transferred the solder to the used desoldering wick and run that over the traces and pads.

Janne, I do believe that would survive a nuclear blast!

One thing to keep in the back of your mind while tinning traces by hand with a soldering iron is to move as quickly as possible to keep from lifting traces or pads. Copper peels off of the FR4 pretty easily when coaxed by heat.

Another tinning method is called Skillet Reflow, if you can find some solder paste: http://www.opencircuits.com/Skillet_reflow.  You can even use a toaster oven for this one.

[bside2234]

When I have a tight layout, I just take an awl (pointed tool) and just scratch away the PNP from the solder pads and leave the PNP on the traces. Works really well for preventing solder bridges plus it smells good when it burns! After you are done you can just leave it and it will eventually all come of or you can spray it with something to keep it on there. I usually just leave it.

[frank]

I've also heard that some put a "lacquer" over the whole pcb (even the pads).  Then when they solder the components, the lacquer melts and act like flux.  Sure it will not help quick soldering over the pad only but the copper traces will be protected.  I would really like to know what kind of "lacquer" should be used there cose I've tried it on ROG "fet 18" with acrylic lacquer and it was hell of a job to heat an off as to go trough it.  I finally had to clean all that mess and start all over.  Well if you know what kind of lacquer tell me.  

[frank]

Darron,

I have searched in my mess and found what I had talked of before to you.  My aunt use the same device but it is a no mess "included in the funnel" electric device (instead of heating with a candle).



Now, note how precise "ARTWORK" you can do with those babies.  All are step-dyed with that wax process.  This is my collection:



Low tech savoir-faire.
Mhh Think I'm gonna try that on a new project.

[QSQCaito]

If I do this it would be to protect the circuit, rather than avoiding bridges. Could you (yes, its a pita) use the stuff to paint nails to protect the circuit?

[darron]

R.G., I guess you could probably buy like a billion! haha. but it's not a pcb makin' machine. that's just some of the abuse it's going to cop.

the skillet reflow method sounds pretty similar to what was in that youtube clip. did anyone watch that? i'll report my finding on which paints stink soon.

thinking about it, i pulled out an old board i made about 2 years ago which i clear-coated over. i think i used a polyurethane (years ago). all of the traces are actually a dark-ish tarnished brown. maybe it's just the surface, i suppose its not going to get worse and the copper won't deteriorate.

those are some mighty fancy eggs! apply that practice to an enclosure and you've got a respected spot in the pictures thread

[frank]

By the way, the green corrosion on the copper IS PROTECTIVE.  That is why so many roofs are made of copper and lasts so long. Just make sure there is not much flux left. after your board is finished.  The green/brown copper oxide will protect the copper trace because it create a seal against oxygen penetration. That is also why bronze statues lasts for 100 of years,  On iron it is not the same thing, ferrous oxide is not a tight protective layer against oxygen.

[juse]

By the way, the green corrosion on the copper IS PROTECTIVE....

The green patina may look good on a roof, but not so much in an electronic circuit. My issue with it is that it interferes with future rework by possible contamination of the new solder. I suppose you could buff it off before you resolder, but then you risk ripping up a trace or pad & it is just an extra step I'd prefer to avoid. I would rather protect my circuits with something I can control, like tinning. But, I guess the patina could give a certain vintage vibe.....

[frank]

By the way, the green corrosion on the copper IS PROTECTIVE....

But, I guess the patina could give a certain vintage vibe.....

AAAHHHH AH ...JUSE...  Now, you really got to start a myth with this one.  Sure some will believe it.

[Plecky]

I've also heard that some put a "lacquer" over the whole pcb (even the pads).  Then when they solder the components, the lacquer melts and act like flux.  Sure it will not help quick soldering over the pad only but the copper traces will be protected.  I would really like to know what kind of "lacquer" should be used there cose I've tried it on ROG "fet 18" with acrylic lacquer and it was hell of a job to heat an off as to go trough it.  I finally had to clean all that mess and start all over.  Well if you know what kind of lacquer tell me.  

Here in Europe, the company Kontakt Chemie is widely known for a lot of different aerosol-based cleaning/protecting/etc stuff. They make something like what you described, which you can see here.
Probably not available outside Europe, but you could look at the ingredients to see if you can find something similar.
They also have some sort of acrylic lacquer which they say can be soldered through, but it sounds a little nasty to me.

[darron]

By the way, the green corrosion on the copper IS PROTECTIVE....

But, I guess the patina could give a certain vintage vibe.....

AAAHHHH AH ...JUSE...  Now, you really got to start a myth with this one.  Sure some will believe it.

MXR is already going down that road with their fuzz face advertising:
http://www.jimdunlop.com/index.php?page=products/pip&id=359&pmh=products/p_and_e_detail

t is authentic in every detail - a handwired brown circuit board with no solder mask and circuitry carefully matched to the original specs.

[frank]

Oh! The the industry is very competitive, I see....
Seymour is selling beaten up PAFs, Marshall is selling cabs with teared down grillcloth and perforated speakers, and Fender is selling tribute Keith Richard teles with completely burned headstock by cigarettes.
Soon they will be selling us worned to the bottom picks.   
So Darron, you understood the lesson, (stare at Dragonfly's whrils).....no more solder masks....no more solder masks....