Performance of Sn-3.0Ag-0.5Cu Composite Solder with Kaolin Geopolymer Ceramic Reinforcement on Microstructure and Mechanical Properties under Isothermal Ageing.

Nur Syahirah Mohamad Zaimi,Shayfull Zamree Abd Rahim,Mohd Arif Anuar Mohd Salleh,Petrica Vizureanu,Andrei Victor Sandu,Mohd Mustafa Al Bakri Abdullah,Norainiza Saud,Mohd Izrul Izwan Ramli,Rita Mohd Said

doi:10.3390/ma14040776

Abstract

This paper elucidates the effect of isothermal ageing at temperature of 85 °C, 125 °C and 150 °C for 100, 500 and 1000 h on Sn-3.0Ag-0.5Cu (SAC305) lead-free solder with the addition of 1 wt% kaolin geopolymer ceramic (KGC) reinforcement particles. SAC305-KGC composite solders were fabricated through powder metallurgy using a hybrid microwave sintering method and reflowed on copper substrate printed circuit board with an organic solderability preservative surface finish. The results revealed that, the addition of KGC was beneficial in improving the total thickness of interfacial intermetallic compound (IMC) layer. At higher isothermal ageing of 150 °C and 1000 h, the IMC layer in SAC305-KGC composite solder was towards a planar-type morphology. Moreover, the growth of total interfacial IMC layer and Cu3Sn layer during isothermal ageing was found to be controlled by bulk diffusion and grain-boundary process, respectively. The activation energy possessed by SAC305-KGC composite solder for total interfacial IMC layer and Cu3Sn IMC was 74 kJ/mol and 104 kJ/mol, respectively. Based on a lap shear test, the shear strength of SAC305-KGC composite solder exhibited higher shear strength than non-reinforced SAC305 solder. Meanwhile, the solder joints failure mode after shear testing was a combination of brittle and ductile modes at higher ageing temperature and time for SAC305-KGC composite solder.

Highlights

The results proved that, 1 wt% kaolin geopolymer ceramic was able to yield an optimum result in terms of thickness of the intermetallic compound (IMC) layer, refining the microstructure and shear strength
The effects of kaolin geopolymer ceramic (KGC) particles as the reinforcement in SAC305 solder had been investigated at temperature of 85 °C, 125 °C and 150 °C for 100 h, 500 h and 1000 h
The effects of KGC particles as the reinforcement in SAC305 solder had been investigated at temperature of 85 ◦ C, 125 ◦ C and 150 ◦ C for 100 h, 500 h and 1000 h

Summary

Introduction

Development of lead-free solder alloy was ineluctable due to the prohibition of lead usage in the electronic industry implemented by environmental laws. The toxicity of lead has devoted the industry to search for a new generation of solder alloy which is free from lead content. Numerous studies have been carried out in finding a suitable lead-free solder alloy [2,3,4]. Other than being widely available in the market industry, SAC solder alloy has good mechanical properties, and better solderability with a suitable melting temperature [8,10]. The growth of interfacial intermetallic compound (IMC) phases, such as Cu6 Sn5 and Cu3 Sn, at the solder/substrate in SAC solder joints is faster as compared to eutectic tin-lead (SnPb) solder joints, resulting in a thicker interfacial

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