Peter, back when Earl Moon and I were in diapers there were no plated
through holes. As we came out of the caves BC said "lets get more parts on
these PWB's by making the holes conductive". We crammed eyelets and/or
tubelets into the holes thus creating an electrical path through the hole.
Later someone got the Idea to plate the inside of the holes chemically and
make them interfacial connections as well. Wow what a revelation! Holes with
conductive innards where you can solder parts into boards "with the greatest
of ease". Next came multilayer PWB's and PTH's through the board and
attached to circuits inside too! Wow what a revelation. And look where we
are now. Unbelievable that we have come so far in just a couple of diaper
changes, and BC says "it is good".
And that is how I remember it, even though I suffer from "old timers"
disease.
Ron Dieselberg
Trainer/Auditor
CMC ELECTRONICS
CINCINNATI
[log in to unmask]
-----Original Message-----
From: [log in to unmask]
[mailto:[log in to unmask]]
Sent: Tuesday, June 25, 2002 22:18 PM
To: [log in to unmask]
Subject: Re: [TN] Definition of Supported/
unsupported hole
Looking at the correspondance on this, there seem to have
been two
different definitions of what is a supported hole and what
is an
unsupported hole. One definition talks of plated barrels and
unplated
barrels, while the other definition talks of pads - one or
none for
unsupported and two for supported. Majority rule goes with
the plating
definition (my own understanding of the difference between
supported and
unsupported holes), but I am interested to know the origins
of and resons
for two such different definitions. Anyone have a light they
can shed on
this?
Peter
"Mcmaster, Michael" <[log in to unmask]> 26/06/2002 08:14
AM
Sent by: TechNet <[log in to unmask]>
Please respond to "TechNet E-Mail Forum."; Please respond to
"Mcmaster,
Michael"
To: [log in to unmask]
cc: (bcc: DUNCAN Peter/Asst Prin Engr/ST
Aero/ST Group)
Subject: Re: [TN] Definition of Supported/
unsupported hole
So if it's unplated, why does an unsupported hole have a
breakout (or more
appropriately a "no breakout") requirement (IPC-6012 Table
3-5)?
----------
From: Neda Thrash[SMTP:[log in to unmask]]
Reply To: TechNet E-Mail Forum.;Neda Thrash
Sent: Tuesday, June 25, 2002 1:36 PM
To: [log in to unmask]
Subject: Re: [TN] Definition of Suported/
unsupported hole
Peter, a supported hole in a PWB is plated through the
board
according to IPC-T-50 (Terms and Definitions for
Interconnecting and
Packaging Electronic Circuits) " or otherwise
reinforced". The
unsupported holes do not contain plating.
>>> [log in to unmask] 06/25/02 02:22PM >>>
Technet,
Can anyone explain the difference between a supported
and unsupported hole on PCB?
I am reading a section on IPC-A-600 RevF and section
2.10.3/4 specify difference acceptance criteria
according to the hole type.
Rgds,
Peter
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