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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)

#51

Post by milankragujevic »

dotancohen wrote: post #40
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.

Eachine? Or Syma? Both have a version in red that's bad.

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

#52

Post by sannee »

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…

> It would be a lot easier for teachers to say "plug the red wire into the red pin" instead of "the top right ... no, other top, turn it around".

Well blowing stuff up is part of the electronic learning experience isn't it? :)

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

#53

Post by Sharlin »

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…

Most ”black”boards these days are green, apparently for similar legibility and eye fatigue reasons. Color schemes with a similar background color are definitely available for text editors.

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

#55

Post by ludwigvan »

CoolGuySteve wrote: post #48
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…

Human eyes are more sensitive to slight variations in green than other colours. This is why YUV video often encodes green sharper and why 16bit colour give 6 bits to green and 5 bits to red/blue. So on a circuit board with subtle green-on-green variations, it makes sense that they picked green. But since people have many more rods than cones, black/white contrast is easier to discern and white uses all the subpixels…

Thank you, very well explained.

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

#56

Post by jsjohnst »

brianwawok wrote: post #15
Eduardo3rd wrote: post #2

Interesting example of a place where a small but meaningful advantage in a manual application (reduced eye strain during visual inspection) leads to a larger, nearly insurmountable advantage in a world where the task has been largely automated thanks to preexisting R&D/economies of scale. I expect we will see more and more of this in the coming decades across multiple industries. Anything else fit this pattern today?

QWERTY keyboards? Built so mechanical typewriter keys would not hit. Used for computers.

> Built so mechanical typewriter keys would not hit.

Most likely a myth. There’s tons of articles on it, but here’s one to get you started:

https://www.smithsonianmag.com/arts-culture/fact-of-fiction-...

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

#57

Post by ultrasounder »

s1mon wrote: post #43
msoad wrote: post #8

Apple PCBs are all black nowadays. They probably went all they to make the black pigmened oil as good as green.

Some flex circuits are black because they use a conductive coating to create ground planes without increasing the stiffness as much as another set of copper/adhesive/coverlay layers.

The black stuff on flex circuits is actually dual purpose. Stiffener and also EMI shield.Flex circuits in Consumer Electronics is typically used in Two places. Camera module interface and Display interface both of which push serial data to upwards of 1GB/s LVDS(MIPI) CSI and DSI. And due to tlack of dedicated ground planes( cheaper) they add a adhesive that serves to contain emissions from the 8b/10b(Manchester) encoded data stream.

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

#59

Post by duskwuff »

userbinator wrote: post #25
setquk wrote: post #20

Earlier quoted context omitted.

Also lots of boards had transparent solder mask after that (Tektronix did this) which was great for debugging! Examples here: http://golddredgervideo.com/kc0wox/tek/7504/detailedpictures... Whole scope is a work of art!

Wow, gold everywhere. Even the ICs have gold-plated pins... that's not something I've seen before.

It's pretty common in older test equipment. The production cost was phenomenal, of course, but the equipment was expensive too.

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

#60

Post by mhh__ »

dkersten wrote: post #10
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 wonder if this is also why a lot of boards from eg sparkfun are red.

I would guess not, given that these days (At least in small quantities, which I assume scales) the choice of colour is aesthetic (To first order) rather than dictated economically.
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