I have some queries regarding PCB.

Discussion in 'General Electronics Chat' started by shankbond, Nov 27, 2007.

  1. shankbond

    Thread Starter Active Member

    Nov 4, 2007
    hello everybody, i have some queries regarding PCB

    i saw a pcb in my friends home yesterday ,it was like white when i look from upwards and green with metallic contacts embedded from downside

    so,my question is why is this PCB different ,like it is white whereas the most of pcb's i see are all green from each and every angle.

    it would be great if u help me out(i would be waiting for an answer from u)

  2. HarveyH42

    Active Member

    Jul 22, 2007
    You can get boards made in many different colors. There is also a spray-on coating to protect the copper traces, which is most commonly green, but can be other colors. Don't think it's too important these days, since the boards are usually eventually hidden in a case, and most stuff is made to be serviced anymore.
  3. eeboy

    Active Member

    Sep 27, 2007
    The "color" of the board is based on the dye used in the solder mask. There are many different colors available; blue, black, white, red, green... possibly more but these are the most common.

    I've never personally seen a board with two different color solder masks used. What I suspect you have seen is a board with a green solder mask applied to only one side. This would give a green appearance to one side and a white/yellowish appearance to the other (the color of the substrate material which is most likely FR4).
  4. CamCommando

    New Member

    Feb 12, 2008
    I did some research on this topic of why pcbs are green. There is no reason and they can be any color. Green is most common.

    The "white" is actually the substance used for the silkscreen. I have seen boards that people cover one entire side in the silkscreen, this would be one white side and the other green (or blue, red or black).

    You can use several different colors of soldermask to create a rainbow effect by applying them in layers, drizzled on. Its pretty cool. :p
  5. shankbond

    Thread Starter Active Member

    Nov 4, 2007
    thanks for the information mate:)
  6. JohnInTX


    Jun 26, 2012
    Appreciate the info and welcome to AAC.

    You DO realize that George W Bush was president when this thread was last visited??
  7. Roderick Young


    Feb 22, 2015
    There is nothing wrong with trying to help, your heart is in the right place.

    However, the original person asking the question may be long gone, as well as their need for an answer. That is why the moderators tend to lock old inactive threads.
    jean_howard likes this.
  8. DerStrom8

    Well-Known Member

    Feb 20, 2011
    Generally you want to avoid posting in old threads. It's often referred to as "necro-posting", in the sense that you're posting to a dead thread. It's generally discouraged.
  9. dl324

    AAC Fanatic!

    Mar 30, 2015
    It's not wrong, but generally not useful, frowned upon, and causes a lot of posts questioning why an old thread was resurrected. I've done it occasion when someone asked a question that wasn't answered or I felt the answer was faulty and warranted a correction (for posterity).

    I'm using the old interface and get a warning message when I attempt to respond to a thread older than a year or so...

    BTW, welcome to AAC!
  10. DerStrom8

    Well-Known Member

    Feb 20, 2011
    Good to have you. Welcome to AAC! :)
  11. alfacliff

    Well-Known Member

    Dec 13, 2013
    there are also somje types of pc board mateial containing teflon, usually a tan color, used in microwave circuits.
  12. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
    The answer to the OP/TS (not that they are here anymore) is that the specific PCB in question only had the solder mask applied to the non-component side (assuming through hole components) or on the component side (assuming surface mount components).
    Solder mask is really only needed on the soldered side and on boards with the components all on one side there is little/no point in applying it on the other side and a "slight" cost savings
    "Typical" FR4 base laminate is clear/white/yellowish in color.
  13. ian field

    AAC Fanatic!

    Oct 27, 2012
    At one time, "thick film" ceramic substrates were fairly common. The ceramic was almost always white, but the tracks on it often had green solder resist masking just like any normal PCB.

    Elektor PCB service boards were usually blue.