Browse Prior Art Database

Non-Permanent Mounting Technique for Test And Burn-In of C4 Devices

IP.com Disclosure Number: IPCOM000102549D
Original Publication Date: 1990-Nov-01
Included in the Prior Art Database: 2005-Mar-17
Document File: 2 page(s) / 66K

Publishing Venue

IBM

Related People

Mace, EW: AUTHOR [+2]

Abstract

Historically, direct chip attachment of C4 chip devices for multi-chip applications for small systems has been avoided due to the inability to test, burn-in and rework the devices unless they are hard attached to a substrate. Burn-in and test at the chip level is a requirement since overall yield of the assembly is the product of the yields and is low for any design utilizing more than a few chips/devices.

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Non-Permanent Mounting Technique for Test And Burn-In of C4 Devices

       Historically, direct chip attachment of C4 chip devices
for multi-chip applications for small systems has been avoided due to
the inability to test, burn-in and rework the devices unless they are
hard attached to a substrate.  Burn-in and test at the chip level is
a requirement since overall yield of the assembly is the product of
the yields and is low for any design utilizing more than a few
chips/devices.

      This article describes a method where the C4 solder ball is
forced into contact with substrate metallization without reflowing
the solder, allowing burn-in and test of the chip.  For the example
described, a flexible substrate will be used.  Typically, the
flexible substrate is a polyimide film material with copper
metallization (see Fig. 1).  The chip, with C4 solder balls attached,
is placed over vias in the metallized/circuitized polyimide film.
The holes in the polyimide (d2) are somewhat smaller than the
diameter of the C4 balls (d1) such that contact can be made between
the C4 solder and the copper metallization.  A weight is applied to
the chip top to insure proper contact. This assembly is resting on an
elastomeric material which is used to assure intimate contact even if
the planarity of the C4 balls is poor.  Electrical signals can be
applied as appropriate to fully exercise the chip and accomplish test
and burn-in requirements.  At the completion of the test and b...