Abstract
Ball grid array (BGA) packages have increasing applications in mobile phones, disk drives, LC displays and automotive engine controllers. However, the thermo-mechanical reliability of the BGA solder joints challenges the device functionality amidst component and system miniaturisation as well as wider adoption of lead-free solders. This investigation determines the effective BGA solders for improved thermo-mechanical reliability of the devices. It utilised a conducted study on creep response of a lead-based eutectic Sn63Pb37 and four lead-free Tin–Silver–Copper (SnAgCu) [SAC305, SAC387, SAC396 and SAC405] solders subjected to thermal cycling loadings and isothermal ageing. The solders form the joints between the BGAs and printed circuit boards (PCBs). ANSYS R19.0 package is used to simulate isothermal ageing of some of the assemblies at − 40°C, 25°C, 75°C and 150°C for 45 days and model the thermal cycling history of the other assemblies from 22°C ambient temperature for six cycles. The response of the solders is simulated using the Garofalo-Arrhenius creep model. Under thermal ageing, SAC396 solder joints demonstrate possession of least strain energy density, deformation and von Mises stress in comparison to the other solders. Under thermal cycle loading conditions, SAC405 acquired the lowest amount of the damage parameters in comparison. Lead-free SAC405 and SAC387 joints accumulated the lowest and highest energy dissipation per cycle, respectively. It is concluded that SAC405 and SAC396 are the most effective solders for BGA in devices experiencing isothermal ageing and temperature cycling during operation, respectively. They are proposed as the suitable replacement of eutectic Sn63Pb37 solder for the various conditions.
Highlights
Ensuring reliability of solder joints in electronic devices is vital for the operational performance of electronics systems used in safety-critical applications such as aerospace, defence, oil and gas (Received May 10, 2020; accepted September 25, 2020; published online November 5, 2020)drilling, automobiles, medical devices, and power grids
This paper investigated the effects of isothermal ageing and temperature cycling loading on the thermo-mechanical properties of lead-based eutectic Sn63Pb37 and lead-free SAC305, SAC387, SAC396 and SAC305 solder alloys used as ball grid array (BGA) solder joints
The lead-free SAC405 solder joint is the most effective solder under thermal cycling. This conclusion is drawn based on the finding that the solder possesses the lowest magnitudes of stress, strain rate, deformation rate and strain energy density than any other solder considered for temperature cycle loading in this investigation
Summary
Ensuring reliability of solder joints in electronic devices is vital for the operational performance of electronics systems used in safety-critical applications such as aerospace, defence, oil and gas (Received May 10, 2020; accepted September 25, 2020; published online November 5, 2020)drilling, automobiles, medical devices, and power grids. Ensuring reliability of solder joints in electronic devices is vital for the operational performance of electronics systems used in safety-critical applications such as aerospace, defence, oil and gas (Received May 10, 2020; accepted September 25, 2020; published online November 5, 2020). Solder joints have a significant function by providing mechanical, electrical and thermal connections between the electronics package and printed circuit board (PCB). Increasing miniaturisation of electronic components and recent application in hightemperature ambient have put higher demand on thermo-mechanical reliability of solder joints in these components. The properties and responses to the various loading conditions arising from diverse environments the new solders in electronic devices operate are yet to be fully qualified. Mission critical systems are yet to be fully compliant to the directives and necessitates continued effort in this regard
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