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Browse Prior Art Database

Micro Machined Chip C-4 Socket Interposer

IP.com Disclosure Number: IPCOM000104831D
Original Publication Date: 1993-Jun-01
Included in the Prior Art Database: 2005-Mar-19
Document File: 2 page(s) / 51K

Publishing Venue

IBM

Related People

Kim, J: AUTHOR [+3]

Abstract

Disclosed is a cost-saving device to ensure the durability of the expensive MLC substrate of chip burn-in testing.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 90% of the total text.

Micro Machined Chip C-4 Socket Interposer

      Disclosed is a cost-saving device to ensure the durability of
the expensive MLC substrate of chip burn-in testing.

      Fig. 1 illustrates the device schematically.  A disposable,
cheap, and rigid interposer is joined to the testing MLC substrate.
The interposer has a tapered feature so that it can act as a nesting
site for C-4 solder ball during the mechanical contact and it
prevents any physical flow during burn-in at high temperature.

      Fabrication of the interposer can be done as follows:  Single
crystal materials have unique anisotropic etching characteristic
because of a different etching rate of atomic plane.  For example,
using an (100) single crystal Si substrate, etching will be done
anisotropically so that etching plane (111) will be 54.74º
off from the substrate normal axis, if anisotropic etchants such as
KOH compounds are used.  Other single crystal substrates that exhibit
higher fracture toughness such as sapphire can be similarly etched.
Once the slanted via hole is made by etching, the via hole can be
filled with highly conductive metal, such as Cu, by any conventional
metal deposition techniques.  Deposition of an adhesion layer, such
as Cr or Ti, before Cu deposition is preferred.  Then the same
anisotropic etching is performed on the flip side of the interposer.
Slight over-etching will create not only a nest site for the C-4 ball
but also an extremely sharp metal probe, which is a...