Mail*Link(r) SMTP FWD>RE>ASSY revision J-STD-001
Phil,
Currently there is no procedure for mounting additional components as a
modification, in particular surface mounted components, to printed board
assemblies.
In a prior life, as chairperson of the IPC's repair committee, there was a
proposal to add a modification/repair method that would meet you requirements.
Currently, I'm not sure what the status of the modification, perhaps if Jeff
Ferry is listening/watching/reading he could give us an update.
In any case, your "gut reaction" is close to the proposal. What the proposed
method was, was to add (adhesively bond) a small printed board (with
additional lands) to the surface of the printed board for the additional
component mounting and electrical terminations. As you mentioned, then
adhesively spot-bond the wires in place.
The following is an attempt to illustrate most of the modification:
_______________
| added comp. |w
w|_______________|wwwwwwwwwwwww
____cccccc__________cccccc_____
|____________added PB___________|
_______cccccc_______ccccccc_______________
/ the main PB \
/__________________________________________\
The "c"s are the lands or other conductors on the printed boards.
The "w"s represent on the left-side a jumper wire that is lap-soldered along
the surface of the component's electrical terminal and the land; on the
right-side, the wire is formed into an "L" shaped wire lead end and soldered
to the land and the component's electrical terminal.
Not shown are the adhesive for bonding the "added PB" to the "main PB", the
jumper wire's lead dressing, wire staking, or the solder.
A "thin" printed board slightly larger than the land pattern is manufactured
and attached to the surface of the printed board using a suitable adhesive.
The "slightly larger" is to provide the necessary electrical spacing. The
component is soldered to the lands using good hand-soldering surface mounted
component methods. The jumper wires and wire terminations would be much like
the current R-700, Rev C, Method 5.2.4 on page 185.
This repair (intuitively) looks like it will meet about any of the IPC's
performance/functional Class requirements.
Hope it helps,
Ralph Hersey, [log in to unmask]
--------------------------------------
Date: 7/17/96 6:05 PM
From: Phil Bavaro
Mike,
Is there any standard which covers the repair of a completed CCA such as
the addition of a 0805 chip capacitor which doesn't have metallized lands
beneath it?
We need to do some repair due to an electrical engineering change which
will require components and jumper wires to connect them. I know I've seen
this covered in an official procedure but cannot recall if it was an IPC
document or a Military spec or what. I looked through the 700 document but
it only covers the jumper wire installation.
My gut reaction is to attach the component body to the pwb using the
wavesolder adhesive dot process and then to install the jumpers (with lots
of stress relief in them), making sure to stake the wires down every inch
of length.
Any help would be appreciated.
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Date: Wed, 17 Jul 1996 17:40:30 -0800
To: Mike Buetow <[log in to unmask]>
From: Phil Bavaro <[log in to unmask]> (Phil Bavaro)
Subject: Re: ASSY revision J-STD-001
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