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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