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Method using composite pillars for creating a compliant connection in a coreless package

IP.com Disclosure Number: IPCOM000009505D
Publication Date: 2002-Aug-28
Document File: 3 page(s) / 50K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for using composite pillars for creating a compliant connection in a coreless package. Benefits include improved performance and improved design flexibility.

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Method using composite pillars for creating a compliant connection in a coreless package

Disclosed is a method for using composite pillars for creating a compliant connection in a coreless package. Benefits include improved performance and improved design flexibility.

Background

        � � � � � Mechanical failure can occur for interconnects on a die or between a die and a package. Conventionally, one of the most challenging problems is the reliable connection of the die to the package, typically due to coefficient for thermal expansion (CTE) mismatch between the two. This situation can cause failure of the solder bumps. With the introduction of low κ inter-layer dielectric (ILD) materials on the die, interconnect structures are equally or more prone to failure. Because ILD κ is required to decrease in future generations, this problem is expected worsen.

        � � � � � While no confirmed solutions exist, an option being explored is to reduce the CTE of the package to which the die is attached. However, because this system must be attached to a motherboard that has a high CTE, this experimental solution moves the CTE mismatch from die/package to the package/motherboard.

        � � � � � The conventional placement process is comprised of the following steps:

1.        � � Single material bumps are placed on the package (see Figure 1).
2.        � � A cavity is milled and etched out for die placement (see Figure 2).
3.        � � The die is placed in the cavity (see Figure 3).

General description

        � � � � � The disclosed method is compliant pillars formed using more than one metal for connecting a silicon die to a coreless package. Rather than forming a bump or stud made of a single material (typically solder), a compliant pillar material...