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solder mask Answered

is a solder mask just pcb laquer? like you could make your own solder masks?

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hag

8 years ago

Adding a solder mask does a lot more that just "looknice."  It does what it's name implies, it masks the solder,keeping it from getting on anything but the exposed pads.  With asolder mask you can create a really densely paked board with many tracesrunning next to a pad or under a SMT component and not worry aboutshorting to the traces when soldering the board.  It is also almostmandatory when doing a fin pitch no lead part.  Whithout the soldermask, it is almost impossible to get the solder paste to reflowproperly and not cause shorts to nearby pins.  I have found thatsoldering to a board is far easier with a solder mask, especially whenusing SMT.

Have an idea to share... if we get a print out of just pads and vias layer using eagle schematic editor on a photopaper and tranfer it to the copper side of the already etched pcb and then spray some kind of green resist mask it will be an easier way to get solder resist masking done. the imp part is to find a spray type solder resist masks. i dont have such thing available in local market.

green mask.jpg

Bringing this topic up again, so... how can I tinplate the PCB's?

do you have to? as long as the copper is unbroken, people can tin the board themselves.

yeah, but it just makes boards look more profesional and makes them be able to solder right away, plus no (well, next to) corrosion. I found a thing called liquid tin by mg chemicals It would make boards like 3 cents more expensive per square inch, but (well to be quite honest) it would bring in more profit than without it.

unless they are working with smts, tinning really isnt essential.

you're right, but soldering with everything pre-tin is much more fun than normal soldering, the first time I soldered a PCB that wasn't made by me was the boarduino kit and it was a joy to solder.

. You ought to be able to build a wave solder bath that would do the job. Me: probably not. You: I bet you can.

im hoping to get a boarduino. do you need the cd pack, or just the boarduino and the cable?

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lollu

10 years ago

I make my "silk screens" at home too. idea's simple-when toner transfer works on one side, why not on the other? I print the silk screen layer mirrored on a laser printer and transfer it using iron box to the top side of the board. Not sure if its "professional" enough, but definitely solves my purpose-i never look back at the schematic when soldering. oh ya, the silk screen will be black and not white :-)

I'm going to make some solder masks with fans on it.
Instructable(s) coming soon!

  • How to kill octagons
  • Solder mask ( :P )
  • Instructables Toy Figure
  • Make your own rotary tool (Similar to Weissensteinburg's, might not post, don't have time.)
  • Make this one kind of chocolate biscotti that my mom bought.

And more!

Stay tuned!

:P

Instructables toy figure?

Make your own Robot??

Hurry, boy, I have birthdays to build for!

I'm trying as fast as I can! :P It's not actually going to be a robot, like electricishy, but it looks just like the Instructables Robot. Because it is an Instructables Robot toy figure. ;-)

well, once i finish my cnc machine is done (I had to put it off till my wooden grandfather clock is done) I'm going to sell really cheap custom pcb's. like let's say 1 company says 20 bucks for a 4x4 board. I'd make it for somewhere around 5 dollars. I'd be maxed to 2 layers though, until I have enough profit to get more stuff for it. I'd want a solder mask to make it seem more profesional and so that i could quick dip the board in a pool of solder to pretin all of the pads. Only downside i see of all of this is that it all has to be leadfree solder since im selling it.

If I had to choose between a plated (tin/gold) PCB or a solder masked PCB I'd choose the plated. Absolutely. The home PCB guys doesn't dip the PCB in a bucket of liquid solder to get it plated. You use a special tinning- or gold-plating solution that chemically deposits a layer on the copper. Apart from the plating and solder masking there are two other things that are present on a PCB from a professional PCB fab house. The first is the silk screen - the white letters and component outlines. Definitely an overkill for home made PCB's. The second is copper plating of the holes to connect the top and bottom layer. Without it you need to solder the components on both sides and put small wires in all vias and solder them on both sides also. That's a major pain in the butt.

Thanks for all of the info! I'll look into the solution thing because i didn't think realy manufactures dipped boards into a big bath of molten solder. I don't think I'll start offering silkscreen right away because I simply can't do that... yet. The viases are pretty much given when plating,yes? and solder masks also help prevent corrosion.

Unfortunately the holes are not fixed by just tin/gold-plating the PCB. They must be handled separately. The industrial process for it is not easy to replicate because it involves (if I remember correctly) putting some organic conductive stuff onto the walls of the holes and then electrolytically deposit copper there. DIY people either uses small copper tubes that are inserted into the holes and then flanged by a special tool on the top and bottom so they stay put. Or they just solder the components at both sides because that's easier than fiddling with the via tubes. Corrosion prevention by solder mask? Yes. But that is taken care of enough by the tin/gold plating. Gold doesn't corrode at all, and the corrosion of tin is more or less negible when it comes to soldering. Exposed copper becomes really nasty after a week or two especially if you've got fingerprints on it. Regarding the plating. PCB fab houses have several techniques for plating. One of the is actually to dunk the entire PCB in molten tin/lead and then blast if off with compressed air to get a nice and level film of tin on the copper.

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westfw

10 years ago

I think "heat resistant" is going to be the hard part of a general purpose laquer, other than applying it :-) And solder masks are pretty important for hand-soldering once you get to relatively fine pitch SMT parts. We has some freeduino board prototypes with no soldermask, and several people had significant problems soldering the SSOP FTDI chip (while they hadn't on slightly different boards WITH soldermask.)

Basically yes. It's a layer of heat resistant lacquer/epoxy paint that usually covers the entire PCB except for those areas that should be solderable. For hand soldering there's really no big advantage, except that is looks nice and green, of having a solder mask, it's mainly for automated wave soldering (where the whole PCB is subject to the liquid solder) to avoid shorts. If you want to make your own solder mask you need to find a paint that are heat resistant, cover of the areas you want solderable in the PCB, paint it and then remove the covers to expose the copper again...