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Laminated Die Structure for Flip Chips to Reduce Die Warpage and Improve Solder Joint Reliability and Heat Dissipation

IP.com Disclosure Number: IPCOM000029157D
Publication Date: 2004-Jun-16
Document File: 2 page(s) / 68K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method that attaches a laminate of metal or composite material to the exposed die surface to counter warpage induced between the CTE mismatch of the die and substrate. Benefits include improving solder joint reliability at the die shadow.

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Laminated Die Structure for Flip Chips to Reduce Die Warpage and Improve Solder Joint Reliability and Heat Dissipation

Disclosed is a method that attaches a laminate of metal or composite material to the exposed die surface to counter warpage induced between the CTE mismatch of the die and substrate. Benefits include improving solder joint reliability at the die shadow.

Background

The following are common problems associated with the process:

§         Die warpage. CTE mismatch of the die and OLGA substrate causes localized warpage under the die shadow.

§         Solder Joint Reliability. Die shadow warpage causes the solder joint at the die shadow to have a higher risk of failure.

§         Thin die problem in Flip Chip. Thin dies for the FCBGA are not possible because the rigidity and low fracture toughness of silicon prevents the usage of this technology.

Currently, these problems are solved by using a thick die to provide increased rigidity, and by using smaller die sizes to decrease package warpage. (As package integrated functionality increases, bigger die sizes are required, but are limited by the warpage.)

General Description

The disclosed method uses a laminate that is similar to the CTE of an OLGA substrate, such as the substrate core or copper (see Figure 1a), to reduce package warpage and improve SJR. The laminate is attached using a film adhesive or other mean of joining, such as brazing between copper laminates with exposed die surfaces. The laminated die structure counters the warpage of the die. In the case of larger dies, warpage can be worse when using the current technolog...