Homebrew PCBs

See page 26 and 27 here: http://www.jjorly.com/g10_fr4_sheets_fabricator.htm  Most copper is electrodeposited (i.e., plated) onto the FR4.

John
  ----- Original Message ----- 
  From: Dave M 
  To: Yahoo Homebrew_PCB 
  Sent: Wednesday, August 15, 2012 7:28 PM
  Subject: [Homebrew_PCBs] Bonding copper to FR4 core material


    
  I've followed a thread on the Tekscopes group for several days, hoping that 
  someone would ask the question that's eluded me for years. My question is 
  in regard to the raw PCB manufacturing process; hopefully, someone can 
  provide a clue.

  My question is: what process is used to prepare the surface of the copper 
  sheet prior to bonding to the bare fiberglass (e.g., FR4) board? If you've 
  ever lifted a trace from a PCB, you've probably noticed that the copper 
  surface that was bonded to the fiberglass board had some kind of brownish 
  coating on it. Logic would lead one to think that this coating would help 
  the copper to securely bond to the fiberglass.

  I've noticed that on some boards, the copper-fiberglass bond is quite 
  tenacious, requiring a good bit of effort to break it. Applying heat and 
  pressure is the easiest method, but physically pulling a copper trace form 
  the board can be difficult if you're trying to salvage the trace.

  I would like to know how the copper sheet is prepared prior to bonding to 
  the board. Anyone know?

  Cheers,
  Dave M 

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