Abstract

The Sn-9Zn lead-free solder alloy was prepared by conventional casting technique then cold-rolled into long sheets of 1 mm thickness and 3 mm width. It was annealed at 80, 120 and 160°C for 60 min to investigate the effect of isochronal heat treatment on structure and mechanical properties of the cold rolled Sn-9Zn alloy. The results showed that, the crystallite size and lattice strain have opposite behavior with increasing annealing temperature due to recovery and recrystalization processes associated with the heat treatment process. Vickers micro-hardness number increases continuously from 155 to 180 MPa with increasing annealing temperature. Ultimate tensile strength (UTS) was also calculated. It was found that, it is equal to 61.4 MPa for the non annealed sample and slightly decreases to 60.5 and 58.2 MPa for samples annealed at 80 and 120°C, respectively. While, increases to 65.4 MPa for the sample annealed at 160°C. Also, ductility increases with increasing annealing temperature in opposite manor with the UTS. The new method for Micro-creep behavior as well as the creep rate calculated by this method has been characterized at room temperature.

Highlights

  • IntroductionThere are some characteristics which play a major role in the consideration of substitutes for tin-lead solders in electronic soldering, such as a lower melting temperature of solder, adequate strength, the environmental issues related to the toxicity, good electrical/thermal conductivity, low cost, good wetting properties, and availability in sufficient quantities as concerns the base metal

  • The results showed that, the crystallite size and lattice strain have opposite behavior with increasing annealing temperature due to recovery and recrystalization processes associated with the heat treatment process

  • There are some characteristics which play a major role in the consideration of substitutes for tin-lead solders in electronic soldering, such as a lower melting temperature of solder, adequate strength, the environmental issues related to the toxicity, good electrical/thermal conductivity, low cost, good wetting properties, and availability in sufficient quantities as concerns the base metal

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Summary

Introduction

There are some characteristics which play a major role in the consideration of substitutes for tin-lead solders in electronic soldering, such as a lower melting temperature of solder, adequate strength, the environmental issues related to the toxicity, good electrical/thermal conductivity, low cost, good wetting properties, and availability in sufficient quantities as concerns the base metal. These properties are mostly affected by the methods of preparation of the alloys such as rapid solidification, conventional casting or unidirectional solidification. Sn-Zn alloy is advantageous from the economic point of view because Zn is a low cost metal

Experimental
Structure of Sn-Zn Alloy Samples
Thermal Properties of Sn-Zn Alloy Samples
Tensile Measurements
Micro Hardness Measurement
Micro-Creep Behavior
Conclusions
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