Browse Prior Art Database

Method for concave bump coining in FCBGA processing

IP.com Disclosure Number: IPCOM000018654D
Publication Date: 2003-Jul-30
Document File: 2 page(s) / 64K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for concave bump coining in flip-chip ball grid array (FCBGA) processing. Benefits include improved reliability and improved yield.

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Method for concave bump coining in FCBGA processing

Disclosed is a method for concave bump coining in flip-chip ball grid array (FCBGA) processing. Benefits include improved reliability and improved yield.

Background

      In the conventional FCBGA manufacturing process, solder bumps in controlled collapse chip collect (C4) pads must be flattened to ensure good connectivity. The process includes mechanical pressing on the solder bump after singulation (see Figure 1).

      Not wetting is one of chronic defects in FCBGA assembly.

General description

      The disclosed method forms a dent on FCBGA solder bumps to reduce the likelihood of not wetting during chip attachment. The key element of the method includes a protruded coining head that matches the C4 bump array.

Advantages

              The disclosed method provides advantages, including:

•             Improved reliability due to improved joint formation

•             Improved yield due to defect prevention

Detailed description

      In the disclosed method, solder bumps are flattened by a convex coining head so that C4 bumps are well located on the solder bumps and ensure good joint formation (see Figure 2).

              The disclosed method utilizes existing equipment/tools, but the coining head is modified. To make a dent on a solder bump, the heads must be embossed the same as the C4 array. The depth and diameter of dent should be based on the product specification. The dent is formed on the bump by localized pr...