Browse Prior Art Database

Method for the direct attachment of flip-chip dice to PCBs

IP.com Disclosure Number: IPCOM000103393D
Publication Date: 2005-Mar-17
Document File: 2 page(s) / 141K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for the direct attach of flip-chip dice to printed circuit boards (PCBs). Benefits include improved functionality, improved performance, improved mechanical reliability, and improved cost effectiveness.

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Method for the direct attachment of flip-chip dice to PCBs

Disclosed is a method for the direct attach of flip-chip dice to printed circuit boards (PCBs). Benefits include improved functionality, improved performance, improved mechanical reliability, and improved cost effectiveness.

Background

      Electronic packages add size and cost to an integrated system. Direct die attach eliminates the package, enabling a smaller system form factor and potentially lower system cost.

      The conventional package attachment methodology occurs at high temperature, ~220ºC. The heat interacts with the different rates of thermal expansion of the silicon and the board to create joints that are highly stressed at room temperature and are subject to failure.

              Conventionally, die are soldered on to a substrate or package interface. This integrated package is soldered on to the PCB or motherboard. The solder reflow process subjects the substrate, die, and package to temperatures in excess of 220ºC.

General description

      The disclosed method attaches a die directly to a board through the use of a conductive adhesive.

              The key elements of the disclosed method include:

•             PCB design – Contact pad footprint mirrors the die footprint

•             Die – Contacts aligned with the PCB for direct placement; silicon, gallium arsenide, or other material; targeted for flip-chip applications

•             Assembly process – Utilizes uniform volume of conductive adhesive deposited on the PCB to support electrical and mechanical contacts

Advantages

              The disclosed method provides advantages, including:
•             Improved functionality due to providing die attachment without using a package

•             Improved functionality due to enabling smaller systems, particularly in height, with the elimination of the package
•             Improved performance due to reducing the CTE mismatch b...