Empirical modeling of the time-dependent structural build-up of lead-free solder pastes used in the electronics assembly applications

被引：0

作者：

Mallik S. ^{[1
]}

Ekere N.N. ^{[1
]}

Bhatti R. ^{[1
]}

机构：

[1] Electronic Manufacturing Engineering Research Group, Medway School of Engineering, University of Greenwich at Medway, Chatham Maritime, Chatham

来源：

Journal of ASTM International | 2010年 / 7卷 / 09期

关键词：

Flux; Lead-free; Rheology; Solder pastes; Stretched exponential model; Time-dependent behaviors;

D O I：

10.1520/JAI103043

中图分类号：

学科分类号：

摘要：

Solder paste is the primary bonding material used in the assembly of surface mount devices in electronics industries. It generally has a flocculated structure, which may break-down on shearing and slowly rebuild at rest. The proper characterization of the time-dependent rheological behaviors of solder pastes is crucial for establishing the relationships between the pastes' structure and flow behavior and for correlating the physical parameters with paste printing performance. In this paper, we present a novel method that has been developed for characterizing the time-dependent and non-Newtonian rheological behavior of solder pastes and flux mediums as a function of shear rates. The objective of the study reported in this paper was to investigate the thixotropic build-up behavior of solder paste and flux mediums. The stretched exponential model has been used to model the structural changes during the build-up process and to correlate model parameters with the paste printing process. As expected, for solder paste samples, the rate of structural recovery was found dependent on the applied shear rate. The model parameters, such as equilibrium viscosity and characteristic time, have been correlated with the shear-thinning and slumping behaviors of solder paste during the stencil printing process. Copyright © 2010 by ASTM International.

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