International Business Machines Corporation

Eric Duschesne

Kang-Wook Lee

Valerie A Oberson

The invention relates to a composition of matter comprising a soldering flux, wherein the flux consists essentially of a combination of a fluxing agent and a solvent, and wherein the fluxing agent comprises a keto acid such as levulinic acid or acetylbutyric acid. The flux may also comprises an ester acid, or comprises a mixture of the keto acid with the ester acid. The solvent comprises a mixture of a tacky solvent with a non-tacky solvent. The invention also relates to a process comprising soldering at least two surfaces together, each of which comprises a metal area to which solder can adhere by employing the following steps in any order: applying solder to at least one of the metal areas, aligning the metal areas so that they are superimposed over one another, heating at least one of the areas to a temperature that comprises at least the melting temperature of the solder. The last step comprises joining the superimposed areas to one another. The process employs the flux composition operatively associated with the solder, and in one embodiment the invention comprises a mixture of the flux composition with powdered solder. In another embodiment, the process comprises IMS, C4 and C4NP processes and the solder comprises a lead free solder. The invention also comprises a product produced by the foregoing process or processes.

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Armonk, NY, United States of America

Eric Duschesne