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Method for C4 interconnect void reduction through modified particle size distribution of the solder metal particles

IP.com Disclosure Number: IPCOM000018906D
Publication Date: 2003-Aug-20
Document File: 3 page(s) / 92K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for controlled collapse chip collect (C4) interconnect void reduction through modified particle size distribution of the solder paste metal particles. Benefits include improved reliability.

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Method for C4 interconnect void reduction through modified particle size distribution of the solder metal particles

Disclosed is a method for controlled collapse chip collect (C4) interconnect void reduction through modified particle size distribution of the solder paste metal particles. Benefits include improved reliability.

Background

         The C4 process is used conventionally in the semiconductor industry for high-density interconnects. New products will require a tighter and smaller interconnect, which will function as a bridge for current between silicon active circuitry and the connecting substrate.

         Interconnect void formation typically presents a concern for the semiconductor industry because it reduces the cross sectional area of the connection. Reduced area makes a weaker connection and increases current density. Both phenomena have a negative impact on product performance, mechanically and electrically.

         C4 interconnect is sensitive to void formation when solder paste material is printed over the substrate. These voids may be formed by air trapped at solder resist holes where solder is being printed and by gases from flux, which is used as a dispersion vehicle for the solder metallic particles. This flux is organic in nature. It is made of several components that release gases when subjected to the reflow process. Gases can become trapped inside the solder, creating voids.

         Conventional solder pastes use single particle size distribution. Alternative solder sphere particle distribution enables the total amount of flux required in the solder paste to be significantly reduced. Less organic material has an immediate positive impact on void formation. However, a limit exists for reducing voids through the active flux components. Most of the flux mass provides plastic properties to solder paste for printability.

         Particle size distribution adjustment is widely use in the ceramic industry to adjust thixotropic characteristic of slurries for pumping purposes. But this concept is not conventionally applied to semiconductor interconnect void reduction.

General description

The disclosed method is alternative particle size distribution on the metal particles to reduce the percentage of flux in the solder paste. The method reduces void...