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Nanometer Scale Engineering on Lead Frame

IP.com Disclosure Number: IPCOM000236897D
Publication Date: 2014-May-21
Document File: 3 page(s) / 894K

Publishing Venue

The IP.com Prior Art Database

Abstract

We report here on nanometer/atomic scale engineering (vertical axis) on selected areas of lead frame. This is to improve thin Au/Pd plating on smooth Ni layer over smooth Cu L/F. Also for the new metric for Pd/Au finish on Ni layer.

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Nanometer Scale Engineering on Lead Frame

ABSTRACT

We report here on nanometer/atomic scale engineering (vertical axis) on selected areas of lead frame.  This is to improve thin Au/Pd plating on smooth Ni layer over smooth Cu L/F.  Also for the new metric for Pd/Au finish on Ni layer.

QFN units with Au/Pd produced on Ni after surface mount soldering process may be subject failure.  Thinner Au/Pd films produced on Ni without considering roughness of Ni layer.  The Au/Pd film needs sufficient thickness and smoothness to protect the underlying rough Ni from oxidation during assembly so that solderability is not compromised.  Also, addresses cost saving strategy with this improved Pd/Au finish.

X-Sectional View

Proposal is to provide nanometer/atomic scale smooth surface on selected areas of Cu L/F. Also, provide L/F surface with Au/Pd layer thickness larger than Ni layer surface roughness.

The nanometer scale Cu surface on selected areas by any suitable (mechanical pressing) method.  Then perform Ni plating and Au/Pd plating. 

References

1.      Ultra-smooth metal surfaces generated by pressure-induced surface deformation of thin metal films by Logeeswaran et al. Appl. Phys. A (2007)


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