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Solder Mask in Color

Tie dye PCBWith Halloween coming up here in the United States, I feel compelled to go to the mail bag and answer some pressing questions about candy corn and solder mask. Why candy corn? I mean, solder mask makes sense - it’s a PC board thing, but candy corn? What is the tie in?

Unfortunately, I don’t have that answer, but I did find an expert in both solder mask and candy corn; Jackie Jack O’LED-lantern. JJL has an advanced certification in printed circuit board process control and extensive study in the chemistry of sugar-based imitation candy type substances.

According to JJL: “Solder mask is really important and comes in many colors these days, while candy corn is not really important and only comes in yellow, orange and white [Ed: and sometimes brown].”

The most important reason for having solder mask is to keep the solder where it should be. It keeps solder on the land pads and helps to guide the solder on small or critical pads. My advice to you: don't fab a board without solder mask unless you are hand soldering it yourself.

It seems that the more time passes, the more mask colors are available, and it’s getting less expensive to switch from the venerable “PCB green” to a different shade. As volume goes up, the switch becomes even less expensive.

Why colors other than green?

PCBs are hidden within a case in most commercial products, so the color doesn't matter that much. However, prototypes and a lot of the hobby or development boards come with the PC board exposed for all to see. Many companies with these open board products have chosen to use a specific color as a part of their identity.

Arduino products are blue, as are most boards from Adafruit. SparkFun makes theirs red. Ti Launchpads are red as well. The Beaglebone uses color, essentially, as a model number; Beaglebone black, Beaglebone green. This is possible because major PC board fab houses have made different colors more economical than they used to be. Our partners at Sunstone Circuits have eight standard colors and more available as non-standards. [Ed: Please don't ask for a tie dye PC board. It's bad for solder adhesion]

You can often get different color silk screen legend too. Just make sure there's contrast between the two. White silkscreen on white solder mask would not be the best choice. PCB design is a form of art, so there’s nothing wrong with choosing a color to make a statement. I say, go for it. Just be aware that since green is by far the most common color, it is the least expensive. Adding your artistic tint may cost more, especially in small quantities.

Now that you know everything you need about solder mask, hop on over to Screaming Circuits to get a quote and order some PC boards + parts + assembly.

Duane Benson
Really - don't ask for tie dye solder mask. I hacked up the PCB photo
Although, it would be pretty cool...

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