How are PC boards made?

Hi guys:

How are ordinary copper-clad printed circuit boards made? Is the
copper deposited onto the substrate by some process, or is it attached
as a foil with an adhesive?

Thanks for any replies.

Don

 

Usually the board house buys copper foil clad laminate and etches the
unwanted stuff away, then electroplates the bores of the
through-holes.


John

 

OK, but how is the original copper foil attached to the board? Is
there an adhesive involved, or is it deposited in a molten or powder
state somhow?

Don

 

http://en.wikipedia.org/wiki/Printed_circuit_board

nb

 

In a nutshell...

Copper foil is glued to a "substrate" board (anything from plastic to
teflon, usually fiberglass). The fab shop drills all the holes in it,
then plates (usually electrochemically) additional copper over it all
(making the foil thicker as well as electically connecting through the
holes). Then, a mask is applied over the copper and whatever isn't
masked is chemically removed.

 

Or they pretend to. I almost never get 1 oz or 2 oz when I specify it.
On one of my fab drawings, it says

START WITH 2 OZ COPPER

which helps.

John

 

As far as I know, roll copper foil is epoxied to the laminate, which
is usually epoxy-glass. The foil is usually "black oxide" treated on
one side to stick better.

For some exotics, generally microwave stuff, the copper is
electroplated onto the substrate and not glued. These are usually
teflon or polyimide boards, low-loss stuff, and they want both good
adhesion and a micro-inch smooth, pure copper surface on both sides of
the copper.

John

 

PC board material has a solid copper foil glued (or otherwise
attached) to the fiberglass. When you make your board, any copper
that doesn't look like your circuit is etched away.


--
Peter Bennett, VE7CEI
peterbb4 (at) interchange.ubc.ca
new newsgroup users info : http://vancouver-webpages.com/nnq
GPS and NMEA info: http://vancouver-webpages.com/peter
Vancouver Power Squadron: http://vancouver.powersquadron.ca

 

And for multilayer boards do they simply epoxy each layer on top of each
other layer?

-phaeton

 

Multilayer ( 4 or greater) actually have prepreg (a form of glue) as
the outer layer

A typical stack might look like:

Top ------------ 1 oz Cu
Prepreg ----------
Inner 1 ----------- 0.5 oz Cu
Core ----------- [FR4, typically. Depends on application]
Inner 2 ----------- 0.5 oz Cu
Prepreg -----------
Bottom ------------ 1 oz Cu

[thicknesses and types of core / prepreg are carefully selected for
impedance controlled boards]

Cheers

PeteS