Failure analysis of solder layer in power transistor

Abstract

Purpose The purpose of this paper is to present a failure analysis of the solder layer in a Darlington power transistor in a TO-3 package. Design/methodology/approach A failed Darlington power transistor in a TO-3 package was examined by different kinds of failure analysis techniques. At first, internal gas analysis was conducted to measure the atmosphere. Then, scanning acoustic microscopy (SAM) was performed to check the quality of the solder layers in the failed device, and the failure location was determined in the solder layer between chip and substrate. Next, the failed device was decapped to observe the defects. After removing the chip from the substrate, energy dispersive spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) were applied and the main elemental composition of the solder layer was identified. Findings Internal gas analysis indicated that the moisture and oxygen contents exceeded the allowed maximum value. Large areas of voids were found in the solder layer by SAM. The main elemental compositions of the solder layer were identified by scanning electron microscopy and EDS. Furthermore, the valences of the chemical components in the solder layer were identified by XPS. Except for the few simple substances of the initial solder material, the chemical formulae of oxidation products in the solder layer were deduced. In addition, the root causes are also discussed. Originality/value This paper focuses on the solder layer failure of a power transistor. Factors such as the presence of oxygen, voids and other factors, which can cause transistor damage, were comprehensively analyzed. The analysis process is worth learning from and the results can be used to improve the reliability of power devices in this kind of package.

The Influence of Soldering Profile on the Thermal Parameters of Insulated Gate Bipolar Transistors (IGBTs)

“…The quality of the solder joints is very important for proper heat transfer in the soldered structure [2]. It was proven that degradation of the solder joints leads to an increase in thermal impedance and thus accelerates the failure possibility of the device [11]. Moreover, aging leads to changes in temperature distribution, thermal impedance, fatigue resistance, and the shearing of the solder joints as well [11].…”

“…It was proven that degradation of the solder joints leads to an increase in thermal impedance and thus accelerates the failure possibility of the device [11]. Moreover, aging leads to changes in temperature distribution, thermal impedance, fatigue resistance, and the shearing of the solder joints as well [11]. One of the most important quality factors that can influence thermal management in these components is gas void formation (empty spaces in the solder joints) [11].…”

“…Moreover, aging leads to changes in temperature distribution, thermal impedance, fatigue resistance, and the shearing of the solder joints as well [11]. One of the most important quality factors that can influence thermal management in these components is gas void formation (empty spaces in the solder joints) [11]. Due to their high surface tension, lead-free solder alloys are more prone to void formation, since the outgassing of volatile organic compounds (e.g., fluxes) from the melted solder is limited [12].…”

Reliability analysis of SnAgCu lead-free solder thermal interface materials in microelectronics

“…Further investigation of the situation has led to studies of the effectiveness of the materials used as thermal interface materials (TIMs) in such devices. From the literature (Jiang et al, 2018;Vijay, 2012;Deppisch et al, 2006;Montano et al, 2005;Otiaba et al, 2013), it was discovered that tin-silver-copper (SnAgCu) lead-free solders or solder thermal interface material were beginning to gain more attention as TIMs. However, there is little published research work on the reliability or fatigue life of SnAgCu solder alloys used as TIMs.…”

Machine learning framework for predicting reliability of solder joints

“…Many previous works (Tapani Nurmi and Olavi Ristolainen (2002), Syed (2004); Kang et al (2004), Hegde et al (2009); Andersson et al (2009), Collins et al (2012); Liu et al (2017), Jiang et al (2018)) have been carried out to understand the reliability of solder joints. Various factors including thermal deformation, fundamental mechanical properties such as elastic modulus, yield strength, shear strength, fatigue, creep, microstructure, intermatallic compound formation, electromigration, void formation, and metallurgy and phase transformation affect solder joint reliability.…”