Which soldermask colour has best component visibility - Page 1
Forum section: electronics / general

author: Wilson__
author_rank: Frequent Contributor
timestamp: September 25, 2024, 12:37:35 am
content: Which soldermask (was stated wronglysilkscreen) colour is easy tosee and positioncomponents during soldering?Have not seen Yellow, White, Purple and Matte green. Are they good? May be bright colours have better contrast with dark/black chips?On hand have Green, Red, Blue, Black. Red is best in four.Many thanksEDIT: for manual soldering

author: schmitt trigger
author_rank: Super Contributor
timestamp: September 25, 2024, 01:17:27 am
content: It goes without saying, that the soldermask color plays a very significant role.For instance, a black or blue soldermask would require either a white or yellow silkscreen. I prefer yellow, but that is only a personal preference.

author: Wilson__
author_rank: Frequent Contributor
timestamp: September 25, 2024, 01:49:50 am
content: Quote from: schmitt trigger on September 25, 2024, 01:17:27 amMany thanks. Sorry my typo. I meant solder mask instead of silkscreen

author: digger
author_rank: Regular Contributor
timestamp: September 25, 2024, 01:53:17 am
content: another thing worth considering is that soldermask color and thickness affect how well you can see traces underneath. probably not really useful for assembly but useful for anyone trying to work on it later.

author: ArdWar
author_rank: Frequent Contributor
timestamp: September 25, 2024, 02:14:07 am
content: You may need to actually sample each color if you want to make sure how each color actually look and behave. Not all manufacturers use the same formula for each color offerings. Some more durable than other, different transparency, different texture, different bonding strength, etc.You'd be surprised how many different offering even for the standard green solder resist are out there.

author: schmitt trigger
author_rank: Super Contributor
timestamp: September 25, 2024, 02:21:57 am
content: I also like red the best, but green many times has a lower cost and/or a shorter manufacturing time.

author: Wilson__
author_rank: Frequent Contributor
timestamp: September 25, 2024, 03:03:35 am
content: Quote from: ArdWar on September 25, 2024, 02:14:07 amDid not realize that. Looked again at those boards, the red is very transparent, can see trace clearly. Also, high contrast to chip which are black/dark

author: NorthGuy
author_rank: Super Contributor
timestamp: September 25, 2024, 03:10:26 am
content: White is the best. Black is the worst. Obviously.

author: SMTech
author_rank: Frequent Contributor
timestamp: September 25, 2024, 09:16:51 am
content: Quote from: NorthGuy on September 25, 2024, 03:10:26 amBlack looks cool but you really can't see traces through it, so mods, repairs or visual inspection for a PCB track fault are harder. I don't think it affect how easy it is to build a board by hand tho'You might think white, I personally disliked it for manually pasting a board as it seemed harder to align. If you were running a cheaper/older SMT machine they might also need adjustment on the optical/lighting side to pick up a fiducial on a white board the reflect much more light than a colored one.For manual soldering tho' the absolute worst it no soldermask at all, fingerprints, shorts and shiny surfaces a whole plethora of things throw out your eyes and skills.Personally its the surface finish I would focus on, I find ENIG gives a nice contrast both for stencil printing and assembly. Very easy to see gold where you expected to see a joint.If was to ask one of our assembly operatives, they'd probably shrug and say they didn't care tho' ....

author: loki42
author_rank: Frequent Contributor
timestamp: September 25, 2024, 10:14:06 am
content: Is this for manual soldering or machine? If it's for machine if it's you just use l test a few of each colour and see what your printer / aoi / spi has problems with. Green is usually the best. White and black would be bad on my machines.

author: Wilson__
author_rank: Frequent Contributor
timestamp: September 25, 2024, 02:17:37 pm
content: Quote from: loki42 on September 25, 2024, 10:14:06 amFor manual soldering

author: ebastler
author_rank: Super Contributor
timestamp: September 25, 2024, 03:53:35 pm
content: White or yellow will give you the best component-to-soldermask contrast. But you will have to use black silkscreen with them, and that can make the silkscreen print distracting when placing and soldering components. You may also find the contrast between soldermask and pads (HASL or gold) to be lacking.I would stick with green or red soldermask, combined with white silkscreen of course. These also happen to be the most common colors, available everywhere -- I wonder why?

author: huababua
author_rank: Contributor
timestamp: October 08, 2024, 07:24:17 pm
content: Fun fact;Green might be the best color for the human eye.Why?Recently I have seen a really nice documentary about the abraj al bait in Mecca.They had the challenge to select the best color for the watch face and did some research on it.It was green - I think this is the color the human eye is most sensitive therefore every other color automatically has the highest contrast to it.This documentary can be found on YouTube somewhere

author: Infraviolet
author_rank: Super Contributor
timestamp: October 09, 2024, 10:52:20 pm
content: huahabua: Indeed, green is sometimes described as the colour the human eye is best as distingushing differences in, and the colour which is (for a given level of watts per square metre) perceived as brightest. But where it's the components upon the board you want to see, rather than examining the board's own traces this perhaps makes green a bad choice. if the eye sees green really well it might "slide off" the components and not see them so well.Blue isn't too great, it's not that rare for some components, particularly SMD resistors to be manufactured in shades of blue, ans in poorer lighting (or well lit but from the from angle) the darker parts of a blue PCB (where the copper isn't) can look close to black.I've seen some green components too, some polyfuses and some lower value higher wattage SMD resistors, these all tend to be relatively big components though with large metallic areas on the ends for soldering to.Red is pretty good, neither when covering copper nor when covering bare FR4 does it look a similar colour to any components (except diffused red LEDs) I've seen.Ofcourse, if its a matter of machine assembly rather than by eye, then you'd probably want to buy some test boards in all the (reasonably priced) colours from whichever company you're using as your board house, and test all of them.

author: JacobPilsen
author_rank: Regular Contributor
timestamp: October 13, 2024, 03:37:37 pm
content: I'm voting green.Many years ago, Czechoslovak TESLA used many different colors of soldermask.One of them was a very light amber color, making the ordinary copper paths underneath look like they were gold plated.