-------- Original message --------
From: Brad Thompson <brad.thompsonaa1ip@gmail.com>
Date: 01/05/2021 9:25 PM (GMT-06:00)
To: TekScopes@groups.io
Subject: Re: [TekScopes] A note on PC boards, double and single sided.

Harvey White wrote on 1/5/2021 8:55 PM:

Printed circuit boards are generally made with one of two materials
(there are others), either a paper epoxy (FR-3) or a fiberglass epoxy
(FR-4).  There are others, but these are most common.

Paper epoxy (FR-3) has a lower temperature tolerance, is not as
mechanically stable, can be burnt easily, and is constructed of paper
and epoxy holding it together.  You see it in a lot of commercial
(expensive or not...) equipment.  It is mostly brown...

Hello--
Older imported electronics used a phenolic-based laminate-- typically
medium to dark brown
and liable to losing its traces when the repairer applied too much heat.
Oh, and when overheated
it smelled like warm horse s*it.

73--

Brad  AA1IP