Ralph,
Your modification illustration assumes surface copper lands from which the addedcomponent must be isolated. For small chip components and a little bit of open real estate, what are your thoughts on bonding the component directly to the
"main" pwb and then soldering the jumper wires to the component terminations?
Jeff
> From [log in to unmask] Thu Jul 18 11:56 EDT 1996
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> Date: 18 Jul 1996 08:21:16 -0700
> From: "Ralph Hersey" <[log in to unmask]>
> Subject: FWD>RE>ASSY revision J-STD-
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> 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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> Subject: Re: ASSY revision J-STD-001
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