Browse Prior Art Database

Postage Stamp Lamination of Reworkable Interposers for Direct Chip Attach

IP.com Disclosure Number: IPCOM000106795D
Original Publication Date: 1993-Dec-01
Included in the Prior Art Database: 2005-Mar-21
Document File: 2 page(s) / 92K

Publishing Venue

IBM

Related People

Foster, RA: AUTHOR [+3]

Abstract

Interconnection of integrated circuit chips using laminated organic carriers is a standard in the industry as it provides a relatively low cost package with good electrical performance. Attachment and connection between high signal count chips and an organic carrier is typically accomplished using either ceramic substrates, plastic packages with lead frames or direct attachment of the chips using C-4 technology. This disclosure suggests an alternate method utilizing organic interposers.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Postage Stamp Lamination of Reworkable Interposers for Direct Chip Attach

      Interconnection of integrated circuit chips using laminated
organic carriers is a standard in the industry as it provides a
relatively low cost package with good electrical performance.
Attachment and connection between high signal count chips and an
organic carrier is typically accomplished using either ceramic
substrates, plastic packages with lead frames or direct attachment of
the chips using C-4 technology.  This disclosure suggests an
alternate method utilizing organic interposers.

      Direct Chip Attachment (DCA) is desirable from an electrical
standpoint as signals propagate directly into a high performance
medium without the discontinuity of an intervening package.  However,
fabrication of the organic carrier is made more complex by the
necessity of providing extremely fine, high density circuitry for the
C-4 array.  This tends to reduce the yield achievable in carrier
manufacturing.  Hence, it is desirable to fabricate the high density
C-4 to carrier grid transformation circuitry on small organic
interposers.  These interposers have the advantage of small piece
yield, plus, using the techniques described, they are removable
(reworkable).   Benefits provided over conventional ceramic and
organic interposers (first level packages) are greater reworkablity,
and providing an electrically "seamless" interface to the second
level carrier.

      By using low temperature and pressure lamination methods
discrete "postage stamps" of material, each with custom chip wiring
may be laminated onto a card/module/substrate.  Additionally, chip
burn-in and test may be carried out on the actual product with chip
removal.

      An organic polymer thin film of polyimide, photoimageable
polyimide, poly-tetrafluoroethyolene, benzocycolbutene, cyanate
esters, high density poly-propylene, thermoplastic liquid crystal
polymer, polyphenylene, or IBM's liquid photoimageable ASM solder
mask may be deposited onto a layer of reworkable polysiloxane or
other adhesive material supported to maintain uniformity and
planarity.  Adhesive materials would include Thermoplastic polymers
with suitable softening points, coefficient of thermal expansion
(CTE), mechanical properties, and dielectric constants which could be
laminated to a second card/module/ substrate.  These polymers could
be filled with varying percentages of silica or other suitable
materials that would improve rigidity perhaps dielectric constant...