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Method for rapid soldering of die-to-package bumps with reactive multilayers

IP.com Disclosure Number: IPCOM000100662D
Publication Date: 2005-Mar-16
Document File: 3 page(s) / 65K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for rapid soldering of die-to-package bumps with reactive multilayers. Benefits include improved functionality, improved performance, improved reliability, and improved design flexibility.

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Method for rapid soldering of die-to-package bumps with reactive multilayers

Disclosed is a method for rapid soldering of die-to-package bumps with reactive multilayers. Benefits include improved functionality, improved performance, improved reliability, and improved design flexibility.

Background

      Thermal expansion mismatch between the die and the package during attachment induces severe thermal stresses. They can be transferred to the underlying dielectric layers, causing their failure.

              Conventionally, potential alternatives include low-temperature bonding and thick metal layers at the interface. A die-package interface schematic illustrates a die attached to a package by controlled collapse chip collect (C4) bumps. Features are designated as follows (see Figure 1):

•             100 – Die

•             101 – C4 bumps

•             102 – Package bumps

•             103 – Package

      No solutions for the thermal expansion mismatch have been implemented conventionally.

General description

      The disclosed method is the local heating and soldering of die bumps to packages for stress mitigation at the die-package interface.

              The key elements of the disclosed method include:

•             Deposition of multilayers of Al and Ni on top of the die C4 bumps and package bumps

•             Activation of exothermic reaction by application of moderate pressure and/or electrical voltage and heat

•             Rapid soldering of bumps at activation due to locally generated heat at the interface between the bumps

•             Localized rapid soldering of bumps, using the exothermic reaction in interlayers between C4 and package bumps, leading to near room temperature die-package attachment

Advantages

              The disclosed method provides advantages, including:
•             Improved functionality due to enabling near room temperature die-package attachment
•             Improved performance due to providing localized rapid bump soldering

•             Improved reliability due to preventing thermal expansion mismatch between the die and the package during attachment

•             Improved design flexibility due to increasing the materials applicable to the design

Detailed description

      The disclosed method includes rapid local heating, which does not affect the underlying materials. As a result, thermal mismatch effects are minimized to a local region rather than the entire die package...