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Materials And Processes for the Fabrication of Low Dielectric Constant Insulators for Advanced Printed Wiring Boards

IP.com Disclosure Number: IPCOM000103268D
Original Publication Date: 1990-Sep-01
Included in the Prior Art Database: 2005-Mar-17
Document File: 1 page(s) / 67K

Publishing Venue

IBM

Related People

Park, JM: AUTHOR [+3]

Abstract

Conventional microwave low dielectric constant (Er) laminates are typically constructed of glass reinforced fluorocarbon (FC) laminates. However, high lamination temperature and inherently high thermal coefficients of expansion (TCE) of the FCs are two major drawbacks. Unreinforced low Er films, such as polychlorotrifluoroethylene (CTFE), are being used as bonding sheets in multilayer boards. However, by using unreinforced film, it is difficult to achieve uniform dielectric thickness during composite lamination. When an inorganic reinforcement is used in conjunction with the films for thickness control, the effective Er becomes higher.

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Materials And Processes for the Fabrication of Low Dielectric Constant Insulators for Advanced Printed Wiring Boards

      Conventional microwave low dielectric constant (Er) laminates
are typically constructed of glass reinforced fluorocarbon (FC)
laminates.  However, high lamination temperature and inherently high
thermal coefficients of expansion (TCE) of the FCs are two major
drawbacks. Unreinforced low Er films, such as
polychlorotrifluoroethylene (CTFE), are being used as bonding sheets
in multilayer boards.  However, by using unreinforced film, it is
difficult to achieve uniform dielectric thickness during composite
lamination.  When an inorganic reinforcement is used in conjunction
with the films for thickness control, the effective Er becomes
higher.

      The present invention relates to composite materials consisting
of (A) a low Er thermoplastic resin and (B) a woven or nonwoven
FC-based reinforcement material.  Material B is usually in a form
based on drawn fibers, which are mechanically strong.  By combining A
and B, a low Er and dimensionally stable composite film is prepared.
By using a hierarchy of (A) resins, these materials can be used as
insulators in core construction as well as bonding sheets for
multilayer fabrication.

      Examples of material A are:  FC films such as Arlon CUCLAD*
6700, 6250 and DICLAD* HBF-430 and LFT-250, or most commercially
available thin FC films.  Examples for material B are:  fabrics based
on FC fibers...