Archive of the former Yahoo!Groups mailing list: Homebrew PCBs
Subject: Does anyone know the process that IBM used to make this PCB
From: Rob <roomberg@...>
Date: 2017-10-07
Does anyone know the process that IBM used to make this PCB
http://www.learnmorsecode.com/3380/index.html
30 years ago I was a computer programmer on an IBM system 34.
IBM service technicians would sometimes open up the machine covers
and I saw some really strange circuit boards inside.
They did not look like anything found in any other electronic appliances.
It looked like there was no etched traces on the IBM circuit boards that
had square blocks..and every square block had solder in them..regardless if
there actually was a component in the holes.
All the components seemed to line up like houses on city streets.
Recently I stumbled onto an IBM 3380 disk drive analog servo board
and made these pictures with real up close details revealing what the strange boards
were really made of... sort of.
It turns out that the IBM PCBs had extremely thin traces on both sides of the PCB
and in some places there was 3 traces in the space between the solder squares
and
that space was no wider than a penny.
These traces would terminate at solder pads but would disappear from view.....
never being actually visible touching a solder pad.
Does anyone know what process made this circuit board?