What is so special about white solder mask?

[zapta]

I recently ordered from Elecrow boards with white soldermask and was surprised how easy it was to clean up. With previous boards (green blue and red solder mask) I always struggled to clean them using IPA a brush and Kimwipes, but the white boards were so smooth, like enamel, and were squeaky clean after a short time.

Is there anything different with white solder mask? Does the color really mater or is just subjective or the white background makes the flux traces invisible?

[nctnico]

It wouldn't surprise me if white is different. It is often used in lighting applications.

[rs20]

IIRC there was a thread not all that long ago where someone was complaining about the white solder mask being less well-defined (i.e., nominally rectangular cutouts were smeared/rounded, generally imprecise) as compared to other colours.

Interesting to consider that the colour white is generated by small particle that scatter light. The solder mask is set using UV light. Slightly conflicting requirements, perhaps? In any case, it sounds like the white mask spreads on as a thinner liquid perhaps; leading to poorer edge definition but a more self-levelled, smoother finish. </pure speculation>

[coppice]

Is there anything different with white solder mask? Does the color really mater or is just subjective or the white background makes the flux traces invisible?

I don't think white differs from other colours, but solder masks vary a lot for the same colour. When you order a board they don't usually ask the texture of mask you want. However, just sticking with traditional green you might get something smooth and shiny, and easy to wipe clean. You might also get something matt and deeply textured that you can really scrub at and still not get entirely clean.

We have received both matt and shiny white masks on boards we have made.

[Psi]

I suspect your white soldermaks isn't actually any easier to clean. You just have white streaks on white 

[zapta]

I found this article that compares PCB solder mask colors. This is what it says about white

Cleaning is just as tough as you’d expect. If you can get all the residue off then the board can look quite nice but it’s white so you really have to get every spot off for it to look good.

http://andybrown.me.uk/2015/01/05/pcb-colours/


I am puzzled, this is the exact opposite of my experience. Will keep ordering Elecrow white boards and see what if the texture varies.

[georges80]

I've used white soldermask and black silkscreen on my boards for at least 7 years and continue to use white.

The advantages I 'see' are it is that the contrast is much better between the board and the components. It really highlights the design and makes visual inspection of solder joint quality easier. That same contrast makes soldering wires to pads etc easier/clearer. A bonus for my customers that assemble the boards into their products.

I don't need to see/inspect traces - that's why boards are electrically tested prior to assembly - to ensure the traces are ok...

Mine have always been a nice smooth gloss finish. As long as the PCB house is doing quality work I haven't noticed a registration/definition issue between the soldermask and fine geometry solder pads (even BGA pads).

cheers,
george.