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Method for Replacing Broken Tracks and Circuit Pads

IP.com Disclosure Number: IPCOM000115571D
Original Publication Date: 1995-May-01
Included in the Prior Art Database: 2005-Mar-30
Document File: 2 page(s) / 44K

Publishing Venue

IBM

Related People

Garrity, JJ: AUTHOR [+2]

Abstract

Printed circuit cards can become damaged during manufacture. This can result in soldered components being knocked off the cards. This invariably results in copper pads being ripped off the cards. The cards generally have to be scrapped after being damaged in this manner.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 70% of the total text.

Method for Replacing Broken Tracks and Circuit Pads

      Printed circuit cards can become damaged during manufacture.
This can result in soldered components being knocked off the cards.
This invariably results in copper pads being ripped off the cards.
The cards generally have to be scrapped after being damaged in this
manner.

      Conventionally, for 50MIL pitch surface mount type printed
circuit cards, repair is achieved by gluing pad down in position and
track welding pad to track.  This is an extremely tedious labor
intensive and time consuming process.

      Described is an improved technique for salvaging the cards.

      The damaged cards are recovered by replacing the copper lands
and solder on the cards with a high conductivity thermoplastic
conductive adhesive.  The conductive adhesive can be deposited by any
of the following methods.
  1.  If real estate allows, the conductive adhesive can be screen
       printed.
  2.  Alternatively the conductive adhesive can be applied either
       manually or automatically with a syringe or positive dispense
       pump.

      The conductive adhesive replaces the copper pads and solder
which are obviously no longer there after the damage has occurred.
The adhesive also serves as the medium of electrical contact to the
copper tracks which have been severed.
  PROCESS
  1.  Prepare copper tracks by scraping off solder resist (note that
       light abrasion of the cop...