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

IP.com Disclosure Number: IPCOM000036477D
Original Publication Date: 1989-Oct-01
Included in the Prior Art Database: 2005-Jan-29
Document File: 2 page(s) / 59K

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 report 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 burn-in cycle, the chip is...