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Outgaseed Copper Foil

IP.com Disclosure Number: IPCOM000118194D
Original Publication Date: 1996-Oct-01
Included in the Prior Art Database: 2005-Apr-01
Document File: 2 page(s) / 41K

Publishing Venue

IBM

Related People

Ohkuma, H: AUTHOR [+2]

Abstract

Disclosed is an invention to outgas from plated copper foil to be used for Tape Carrier Package (TCP) and Printed Circuit Board (PCB), which works to minimize an Sn-Cu intermetallic compound growth at the soldering process. For this purpose, plated copper foil is to be heated in a vacuum for outgassing O2,H2 H2O, etc. before the lamination process of an insulation film, such as polyimide.

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Outgaseed Copper Foil

      Disclosed is an invention to outgas from plated copper foil to
be used for Tape Carrier Package (TCP) and Printed Circuit Board
(PCB), which works to minimize an Sn-Cu intermetallic compound growth
at the soldering process.  For this purpose, plated copper foil is to
be heated in a vacuum for outgassing O2,H2 H2O, etc. before the
lamination process of an insulation film, such as polyimide.

      In general, plated copper foil is porous, trapping a large
number of gasses such as O2, H2, H2O inside, which easily accelerate
Cu-Sn diffusion at the soldering process, resulting in poor solder
joint strength.

      Fig. 1 shows an example which applies an outgassing process for
copper plated foil to be used for TCP.

      As an example, Fig. 2 shows the difference between original
copper foil and outgassed copper foil in Cu-Sn intermetallic compound
growth at 170C.  According to Fig. 2, outgassed copper foil is slower
in Cu-Sn diffusion than original copper foil.

Note:
  1.  Each copper foil was electroless tin-plated.
  2.  Outgass parameter: 10xE(-7)torr, 215C, 10min.