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Integrated Micro Heater-Based Flip-Chip Attach Process for Reduced Thermal Stress

IP.com Disclosure Number: IPCOM000101737D
Publication Date: 2005-Mar-16
Document File: 2 page(s) / 19K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method that attaches a micro heater on a flip-chip die to heat the flip-chip bump during the attach process. Benefits include reducing the thermal stress due to a CTE mismatch between the die and the organic substrate.

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Integrated Micro Heater-Based Flip-Chip Attach Process for Reduced Thermal Stress

Disclosed is a method that attaches a micro heater on a flip-chip die to heat the flip-chip bump during the attach process. Benefits include reducing the thermal stress due to a CTE mismatch between the die and the organic substrate.

Background

Conventional eutectic tin-lead and lead-free solders (e.g. tin-gold-copper) have melting temperatures of 183oC to 217oC, and above. This high melting temperature (and therefore high reflow temperature) imposes a large thermal stress because of the thermal expansion mismatch among components during the chip-attach process. This results in device failure, especially in dies with fragile low-k interlayer dielectrics and/or multi-layer BLM structures.

Currently, some low Tm solders are being tried, but their homologous temperature during operation (i.e. temperature normalized with respect to their melting temperature in K) can be as high as 90 to 95%. This poses an extremely high reliability risk, especially under temperature-driven reliability conditions (e.g. temp cycling or baking). Conductive adhesives are also used; however, they have poor electrical performance (due to water absorption and oxygen permeation), low impact strength, poor adhesion to the copper and tin finished pads, and poor long-term reliability performance.

General Description

In the disclosed method, the micro heater is integrated to the backside of the die. For the chip attach process...