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Optimization of particle reinforced lead-free solders

Stefan F. Awietjan 1Vinzenz Bissig 2Krzysztof J. Kurzydlowski 1Jolanta Janczak-Rusch 2

1. Warsaw University of Technology, Faculty of Materials Science and Engineering (InMat), Wołoska 141, Warszawa 02-507, Poland
2. Empa Materials Science and Technology (Empa), Überlandstrasse 129, Dübendorf 8600, Switzerland


The goal of this research was to optimize the structure and manufacturing process of a particle reinforced lead-free solder. The aim of the particles incorporation was to improve mechanical properties of the matrix solder, particularly the creep resistance. The main problem was a high porosity of the obtained composite solders samples and not homogenous particle distribution.

As a matrix solder Sn-4,0Ag-0,5Cu alloy in form of paste and powder was used. Three different particles types were used as a reinforcement; two types of nickel and copper particles. The particles were introduced by mechanical mixing, using a ball mixer under different mixing conditions. The amount of particles used was 5% wt.

The influence of particles type and mixing conditions upon the solders porosity was investigated. Two types of fluxes were added to the paste during mixing with particles and their influence examined. The Archimedes method was used for density measurements. Obtained composite solders microstructures were investigated with light and SEM microscopes.

The Lead-free composite solder joints and solder joints with different gaps were also prepared and tested. The optimal mixing and soldering parameters for composite solders were found. Obtained microstructure and particles arrangement is uniform. Composite samples with very low amount of pores were obtained.


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Related papers

Presentation: poster at E-MRS Fall Meeting 2005, Symposium H, by Stefan F. Awietjan
See On-line Journal of E-MRS Fall Meeting 2005

Submitted: 2005-07-08 11:58
Revised:   2009-06-07 00:44