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Method for a preapplied substrate load redistributor with cavity pads for C4 interconnection

IP.com Disclosure Number: IPCOM000010061D
Publication Date: 2002-Oct-16
Document File: 4 page(s) / 96K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for a preapplied substrate load redistributor with cavity pads for controlled collapse chip collect (C4) interconnection. Benefits include improved productivity and improved performance.

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Method for a preapplied substrate load redistributor with cavity pads for C4 interconnection

Disclosed is a method for a preapplied substrate load redistributor with cavity pads for controlled collapse chip collect (C4) interconnection. Benefits include improved productivity and improved performance.

Background

        � � � � � The underfill process requires a period of hours to cure epoxy material, leading to low throughput time. However, the underfill process functions as a load redistributor and cannot be eliminated for C4 interconnection. Attempts to improve results by reducing the underfill process to a partial process were not successful. Fast curing the underfill reduced curing time but
contained corrosive materials that did not produce satisfactory results.

General description

� � � � � The disclosed method is a preapplied substrate load redistributor with cavity pads for C4 interconnection. On top of the load redistributor is a preapplied thermal interface layer, which contains silica and epoxy. An array of cavity pads with solder is electrolytically coated on the wall of the cavities. During the assembly’s processing, the cavities guide the die placement process and help to avoid misalignment. Air flows up during placement. During reflow, the heating process activates the thermal interface layer, improving contact between the die and the substrate. The epoxy cures at the interface layer. Solder melts and solidifies within the cavity pads. The whole bonding process is formed within one cycle. The disclosed method eliminates the underfill process and improves productivity while improving solder wetting.

� � � � � The key elements of the met...