Inside Apple's blue logic boards

Inside Apple's blue logic boards

Summary: If you've opened a Mac to upgrade a hard drive or RAM recently you may have noticed that Apple is now using blue circuit board material as opposed to the more traditional green G10-FR4 epoxy circuit boards.


MacPro Blue Logic BoardIf you've opened a Mac to upgrade a hard drive or RAM recently you may have noticed that Apple is now using blue circuit board material as opposed to the more traditional green G10-FR4 epoxy circuit boards.

G10-FR4 (FR4) is a fire rated electrical-grade, dielectric fiberglass laminate epoxy resin system combined with a glass fabric substrate. The abbreviation "FR4" means:  F (for flame) and R (for retardancies) and the 4 is a # 4 epoxy. FR4 grades offer excellent chemical resistance, flame ratings (UL94-VO) and electrical properties under dry and humid conditions.  
FR4 also features high flexural, impact, superior mechanical strength and bond strength at temperatures up to 130°C. G10-FR4 is suitable for structural, electronic, pc boards and electrical applications.

According to a colleague who has worked in the semiconductor industry for years blue boards used to be less reliable and more prone to wiskering (copper migrating between plated through holes and shorting connections) and were not as temperature stable as their green G10-FR4 counterparts.

Some have speculated that Apple may have moved to the new blue boards to be more "green" but this is unconfirmed. Others have mentioned that the switch to blue boards is cosmetic only and that the blue material has the same characteristics as green.

Most of Apple's products now ship with blue logic boards:

It looks as if Apple is the next Big Blue if our logic boards are any indication. Apple declined to comment on this story.

I have posted a gallery of images of the MacBook Pro Core Duo and Core 2 Duo logic boards.

(Thanks to Kenn Marks for his research on the subject.)

Topic: Apple

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  • Its called solder mask

    The color of the PCB is determined by a thin layer of polymer that is put on the outer layers of the PCB keep solder bridges from forming between the exposed traces. The color has absolutely nothing to do with performance, they could have just as easily chosen white, red or a number of other colors. Green is just the most common and can be cheaper for low volume circuit boards.
  • Apple desktops have had blue logic boards for years

    Apple changes the color of the logic boards a lot. The iMac g3 had a green board, but the sunflower version had a blue board. The Powermac g4 cube had a green board, but the quicksilver had a green board. The laptops seem to have always had green boards. Apple prototype units have red boards. Maybe it depends on which company is manufacturing which models?

    Powermac G4:

    Powermac G5:

    iMac (sunflower):

    Prototype with red logic board:
  • Apple's blue logic boards

    I worked for a motherboard manufacturer in Fremont, CA. For high level customers we would use colored for by request of the customer for different stages of development and for the final product. The main customer who came to mind was HP. They used both red and blue. There was no difference in material used, just the dye.
  • Soldermask color is not the fr4 material

    Working in the circuit board industry for over 20 years. The raw FR4 board has a brown-green hue. The green soldermask is the darker green you see on most circuit boards.
    For years we have been masking boards with blue and red and yellow and pink and...

    The issue with copper wiskering is the quality of the Soldermask and the application process. In the past the colored soldermasks (other than green) did have coverage problems. No longer. You can mask with any sm and it should work...unless your application process has flaws (like trying to spread the SM too thin to cut material costs).
  • Thanks everyone for the update

    Thanks for all the great responses and update to my circuit board
    education. Hopefully everyone else was equally educated. I just
    remembered back in the seventies when builing burn-in board for
    Military Semiconductor life tests they were putting dye in the epoxy
    to show grades of glass epoxy boards. And I was wondering if
    those guidelines still existed. Thanx ever so much.
    Kenn Marks
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