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Why Are Printed Circuit Boards Usually Green? (2017)

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Re: Why Are Printed Circuit Boards Usually Green? (2017)

#31

Post by bunnycorn »

ludwigvan wrote: post #22

> 1. Green can relieve visual fatigue and aid in inspections > In the early days, due to technological restrictions, quality inspections relied on workers manually checking the boards with their bare eyes. Squinting at tiny circuits all days is tiring work, but neurologists and psychologists agree that the wavelength of green light has relaxing effects on the body and can reduce fatigue. Additionally, they have found…

I have a gray background (so I can't see refelections in the black) and the current line is a dark green.

Re: Why Are Printed Circuit Boards Usually Green? (2017)

#32

Post by blueline »

ludwigvan wrote: post #22

> 1. Green can relieve visual fatigue and aid in inspections > In the early days, due to technological restrictions, quality inspections relied on workers manually checking the boards with their bare eyes. Squinting at tiny circuits all days is tiring work, but neurologists and psychologists agree that the wavelength of green light has relaxing effects on the body and can reduce fatigue. Additionally, they have found…

solarized is really popular and the dark theme is a sorta dark blue-green

Re: Why Are Printed Circuit Boards Usually Green? (2017)

#33

Post by starky »

borgel wrote: post #11
greglindahl wrote: post #6

One of my startups was purchased by QLogic, which made PCI cards in bulk. One of their corporate standards is that prototypes have red PCBs, to prevent them ever being mixed together with production parts. These days I have some friends who have a particular debit card that's the same color of red. Every time I see it, I twitch.

At work we often try to do a different color for each revision so you can tell at a glance what's in a given unit. It's definitely saved me a few times!

We use different solder mask colours to differentiate different product variants that share a board outline. It is way easier to tell a factory to install the red board when making a specific product variant than to have them read a part number off the board.

Re: Why Are Printed Circuit Boards Usually Green? (2017)

#34

Post by danellis »

peterburkimsher wrote: post #12

Pinouts usually use red and black to indicate power and ground [1]. It's possible to use several colours of solder mask on the same PCB. [2] What I'd like to see is a developer board targeted at the education market that uses colours to show the traces. I think that at least showing the power and ground could reduce the risk of shortouts. It would be a lot easier for teachers to say "plug the red wire into the red pi…

Almost certainly a lot cheaper to just use keyed connectors.

Re: Why Are Printed Circuit Boards Usually Green? (2017)

#35

Post by bsder »

> Green solder mask is physically superior

Possibly chemically. Practically? EVERY other solder mask color is better.

I find that because green is the default, cheap, PCB soldermask, manufacturers thin it to hell and back in order to save money. As such, I regularly get coverage gaps over vias underneath QFN components which then short to the pad underneath the chip. (Manufacturing tip: if you can, only put vias underneath the chip that are tied to the same signal as the QFN thermal pad and your reliability will be much better.)

If I want good soldermask coverage, I always order an alternate color (with the requisite expense) and almost always get great results.

Re: Why Are Printed Circuit Boards Usually Green? (2017)

#36

Post by mhd »

wenc wrote: post #26
SmellyGeekBoy wrote: post #7

Earlier quoted context omitted.

I have a GeForce 2 which is red, I think it's the earliest non-green card in my collection (2000-ish).

All Gravis Ultrasound cards were red (>1992ish). [1] It was partly a marketing choice, to make them stand out from conventional Sound Blaster cards. [1] https://en.wikipedia.org/wiki/Gravis_Ultrasound#Versions

Yes, that's the first non-green PCB I can remember, too.

And it took a while until I saw it become common -- I guess a big incentive was the appearance of side windows on PC cases. At first all DIY (Dremel), then commercially sold.

Re: Why Are Printed Circuit Boards Usually Green? (2017)

#37

Post by amelius »

robterrell wrote: post #30
ludwigvan wrote: post #22

> 1. Green can relieve visual fatigue and aid in inspections > In the early days, due to technological restrictions, quality inspections relied on workers manually checking the boards with their bare eyes. Squinting at tiny circuits all days is tiring work, but neurologists and psychologists agree that the wavelength of green light has relaxing effects on the body and can reduce fatigue. Additionally, they have found…

This research is why we were sold computers with green-colored phosphor monitors back in the 80s. I'm not going back, but if you're into it, maybe try: https://marketplace.visualstudio.com/items?itemName=gerane.T...

At some point people started switching to amber. If above research is correct, then why was amber deemed preferable?

Re: Why Are Printed Circuit Boards Usually Green? (2017)

#38

Post by Sniffnoy »

What this article doesn't answer is, when it talks about the green soldermask being physically superior, is that only because it's had more R&D put into it due to being popular, or would it actually be the best regardless? (Admittedly, I don't know how one would possibly answer that question without, like, actually trying to invent better soldermask of other colors. But it bugs me that the article doesn't even ask the question.)

Re: Why Are Printed Circuit Boards Usually Green? (2017)

#39

Post by Jerry2 »

chrisdhoover wrote: post #21
userbinator wrote: post #16

Note that in the early days of electronics, PCBs did not have soldermask, because it wasn't necessary: https://en.wikipedia.org/wiki/File:IBM_SMS_card_circuit_side...

And the PCBs were tan or natural.

> And the PCBs were tan or natural.

They were tan because they were made of phenolic paper (wood fiber) laminate. Modern PCBs are moade of glass fiber epoxy laminate material and they're usually clear/white without any solder mask dyes.

Re: Why Are Printed Circuit Boards Usually Green? (2017)

#40

Post by dotancohen »

greglindahl wrote: post #6

One of my startups was purchased by QLogic, which made PCI cards in bulk. One of their corporate standards is that prototypes have red PCBs, to prevent them ever being mixed together with production parts. These days I have some friends who have a particular debit card that's the same color of red. Every time I see it, I twitch.

I used to buy some quadcopters and parts from China, and there is a particular board revision that was horrible. It was easily identifiable because it was red. I wonder if this was a prototype or early production run that just kept going. I was buying this particular model for about two years, and the reds would show up during this entire time.
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