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What Determines The Color of a Logic Board?
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Clinically Insane
Join Date: Oct 2000
Location: Los Angeles
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Can someone tell me what process determines the color of a logic board? How do they make it one distinct color or another?
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"The natural progress of things is for liberty to yield and government to gain ground." TJ
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Mac Enthusiast
Join Date: Sep 2000
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The color is determined by the solder mask. The solder mask covers the entire board except for the pads that components are soldered to, to prevent solder from sticking to the traces and other exposed copper on the board. The solder mask is traditionally green, but recently it's become more popular to use other solder mask colors as well.
Before the solder mask is applied, standard FR4 boards are somewhat of a light brownish color.
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Clinically Insane
Join Date: Oct 2000
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Cool, thank you for the answer!
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"The natural progress of things is for liberty to yield and government to gain ground." TJ
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Admin Emeritus  Join Date: Oct 1999
Location: Zurich, Switzerland
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Apple typically uses green (classic) or blue/blue-green (more recently) for production boards. Prototypes have been seen in green, but also in red and yellow.
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Professional Poster
Join Date: Jun 2001
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Originally Posted by tooki 
Apple typically uses green (classic) or blue/blue-green (more recently) for production boards. Prototypes have been seen in green, but also in red and yellow.
I can attest to that.
I personally have seen several prototypes of Apple II machines and Apple peripheral cards in different colors other than green. One prototype Apple IIe motherboard was yellow. A few Super Serial Card prototypes were in yellow and red. One early Apple IIc prototype had the word "Pizza Box" etched into the motherboard (pre-dating the Centris 610/Power Macintosh 6100 form factor by almost a decade).
By far the most interesting Apple prototype-related thing I have seen (in person), is the complete set of engineers' blueprints (including case specifications, schematics, the logic designs of the custom chips, keyboard encoding matrices, etc.) for the Apple IIe. The person who has those won't say how they came to possess them. 
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Mac Elite
Join Date: Aug 2002
Location: Chicago, IL
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Originally Posted by tooki
Apple typically uses green (classic) or blue/blue-green (more recently) for production boards. Prototypes have been seen in green, but also in red and yellow.
For the prototypes, not only are the boards typically red/yellow, but in the older Apples, the computer cases were clear.
http://www.applefritter.com/node/2651
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Admin Emeritus Join Date: Oct 1999
Location: Zurich, Switzerland
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That's amazingly gorgeous, but are you sure it's not just a Japanese aftermarket housing? I know those were made at some point.
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Mac Enthusiast
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Yeah, it wouldn't surprise me if that's an aftermarket modification.
In the days before 3D CAD software made it easy to visualize how everything would fit together, Apple made a few prototypes of early Macs out of clear plastic to check the fit of components when everything was closed up, but I don't think they've done that for a few decades now...
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Addicted to MacNN
Join Date: Aug 2003
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Originally Posted by waxcrash
Wow. I'm not much for the transparent look. It seems regardless of where this design is used, it looks cheap IMO. Interesting find though, egadz!
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ebuddy
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Professional Poster
Join Date: Mar 2002
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Originally Posted by ibookuser2
The color is determined by the solder mask. The solder mask covers the entire board except for the pads that components are soldered to, to prevent solder from sticking to the traces and other exposed copper on the board. The solder mask is traditionally green, but recently it's become more popular to use other solder mask colors as well.
Before the solder mask is applied, standard FR4 boards are somewhat of a light brownish color.
Hold on. Are you talking about the thin sheet of metal that they use to apply the solder paste to the boards (solder mask)? Because that is metal and it has no color other than it's metal color. After they apply the solder paste and then pick and place all the components, it goes through an oven to melt the solder. At no time does any other mask go on top of the circuit board.
So what are you talking about?
The original color of green may be that way because of the color of the epoxy components that made up the boards. The boards also were made in a light brown color. Lately they've been making them in all sorts of colors to impress the customers I guess.
So back to your explanation. WTF?
(Last edited by Buckaroo; Dec 13, 2008 at 12:32 PM.
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Professional Poster
Join Date: Mar 2002
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Here:
http://www.letmegooglethatforyou.com...oards+green%3F
Which took me to this:
http://en.wikipedia.org/wiki/Printed_circuit_board
Conducting layers are typically made of thin copper foil. Insulating layers are typically laminated together with epoxy resin. The board is typically green in color and made of materials like polytetrafluoroethylene, FR-4, FR-1, CEM-1 or CEM-3. Well known prepreg materials used in the PCB industry are FR-2 (Phenolic cotton paper), FR-3 (Cotton paper and epoxy), FR-4 (Woven glass and epoxy), FR-5 (Woven glass and epoxy), FR-6 (Matte glass and polyester), G-10 (Woven glass and epoxy), CEM-1 (Cotton paper and epoxy), CEM-2 (Cotton paper and epoxy), CEM-3 (Woven glass and epoxy), CEM-4 (Woven glass and epoxy), CEM-5 (Woven glass and polyester).
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Mac Enthusiast
Join Date: Sep 2000
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Originally Posted by Buckaroo
Hold on. Are you talking about the thin sheet of metal that they use to apply the solder paste to the boards (solder mask)? Because that is metal and it has no color other than it's metal color. After they apply the solder paste and then pick and place all the components, it goes through an oven to melt the solder. At no time does any other mask go on top of the circuit board.
So what are you talking about?
No, the metal stencil that's used to apply solder paste to the board is called the stencil. It's completely different from the soldermask. And while different materials/epoxies used as substrates will change the board appearance somewhat, they're all rather dull and brownish/grayish/clear. The brightly-colored (green, red, blue, black, purple, etc.) boards that you see are all because of the color of the soldermask.
The soldermask is a layer that is silkscreened onto the outer layers of a board after it's been etched. The soldermask layer has holes in it where the pads for the components are (it looks very similar to the layer that's used to generate the stencils.) If you look at a PCB before components are placed, you'll see the shiny pads for the components, which the solder mask does not cover, and the traces, which are covered by the soldermask and appear greenish. (See this image from a Google image search for reference.) The pads and traces are all made out of the same copper (with a solder coating applied) but since the traces are covered by the solder mask, no solder would stick to them even if you tried.
It's perfectly possible to make a board without the soldermask; they appear light brown in color with copper-colored or shiny silver solder-coated traces, with no distinction between traces and pads; solder will stick to the copper anywhere.
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