Experimental and numerical investigations of the vibration reliability of BGA and LGA solder configurations and SAC105 and 63Sn37Pb solder alloysGharaibeh, Mohammad; Stewart, Aaron J.; Su, Quang T.; Pitarresi, James M.
2019 Soldering & Surface Mount Technology
doi: 10.1108/ssmt-07-2018-0020
This paper aims to investigate and compare the reliability performance of land grid array (LGA) and ball grid array (BGA) solders, as well as the SAC105 and 63Sn37Pb solder alloys, in vibration loading conditions.Design/methodology/approachReliability tests were conducted using a sine dwell with resonance tracking vibration experiment. Finite element simulations were performed to help in understanding the observed failure trends.FindingsReliability results showed that the tin-lead solders out-perform lead-free solders in vibrations loading. Additionally, the LGA solder type could provide a better vibration reliability performance than BGA solders. Failure analysis results showed that in LGAs, the crack is initiated at the printed circuit board side and at the component side in BGAs. In both types, the crack is propagated throughout in the intermetallic compound layer.Originality/valueIn literature, there is a lack of published data in the comparison between LGA and BGA reliability performance in vibration loadings. This paper provides useful insights in the vibration reliability behavior of the two common solder joint types.
Influence of thermal shock cycles on Sn-37Pb solder bumpsGan, Guisheng; Xia, Da-quan; Liu, Xin; Liu, Cong; Cheng, Hanlin; Ming, Zhongzhen; Gao, Haoyang; Yang, Dong-hua; Wu, Yi-ping
2019 Soldering & Surface Mount Technology
doi: 10.1108/ssmt-08-2018-0026
With continuous concerning on the toxic of element Pb, Pb-free solder was gradually used to replace traditional Sn-Pb solder. However, during the transition period from Sn-Pb to Pb-free solder, mixing of Sn-Pb and Pb-free is inevitable occurred in certain products, and in China where Sn-Pb solder was still used extensively in certain areas especially. Correspondingly, understanding reliability of Sn-Pb solder joints was very important, and further studies were needed.Design/methodology/approachThermal shock test between −55°C and 125 °C was conducted on Sn-37Pb solder bumps in the BGA package to investigate the microstructure evolution and the growth mechanism of interfacial intermetallic compound (IMC) layer. The effects of thermal shock on the mechanical property and fracture behavior of Sn-37Pb solder bumps were discussed.FindingsPb-rich phase was coarsened and voids were increased at first; Pb-rich phase was refined and voids were decreased secondly with the increase of thermal shock cycles; the shear strength of solder bumps was slightly decreased after thermal shock, but was back up to 73.67MPa at 2,000 cycles; interfacial IMCs of solder bumps was from typical scallop-type into smooth, the composition of IMCs was from Cu6Sn5 into Cu6Sn5 and Cu3Sn after thermal shock with 1,500 and 2,000 cycles; 20.0 per cent of solder bumps at 1,500 cycles and 9.5 per cent of solder bumps at 2,000 cycles were failure respectively.Originality/valueCompared with the board level test method, the impact shear test for the single solder bump is more convenient and economical and is actively pursued by the industries. The shear strength of solder bumps was slightly decreased after thermal shock, but was back up to 73.67 MPa at 2,000 cycles; 20.0 per cent of solder bumps at 1,500 cycles and 9.5 per cent of solder bumps at 2,000 cycles were failure.
Research on soldering AlN ceramics with Cu substrate using Sn-Ag-Ti solderKoleňák, Roman; Kostolný, Igor; Drápala, Jaromír; Kusý, Martin; Pašák, Matej
2019 Soldering & Surface Mount Technology
doi: 10.1108/ssmt-10-2018-0039
This study aims to solder AlN ceramics with a Cu substrate using an active type Sn-Ag-Ti solder. Soldering was performed with power ultrasound. The Sn3.5Ag2Ti alloy was first studied.Design/methodology/approachIt was found to contain a Sn matrix, where both Ag phase – ɛ-Ag3Sn – and Ti phases ɛ-Ti6Sn5 and Ti2Sn3 – were identified. Ti contained in these phases is distributed to the interface with ceramic material. A reaction layer was thus formed. This layer varies in thickness from 0.5 to 3.5 µm and ensures the wettability of an active solder on the surfaces of ceramic materials.FindingsX-ray diffraction analysis proved the presence of new NTi and AlTi2 phases on the fractured surface. Sn plays the main role in bond formation when soldering the Cu substrate with Sn-Ag-Ti solder. The Cu3Sn and Cu6Sn5 phases, which grow in direction from the phase interface to solder matrix, were found in all cases within the solder/Cu substrate interface. The combination of AlN ceramics/Cu joint maintained a shear strength of 29.5 MPa, whereas the Cu/Cu joint showed a somewhat higher shear strength of 39.5 MPa.Originality/valueThe present study was oriented towards soldering of AlN ceramics with a Cu substrate by the aid of ultrasound, and the fluxless soldering method was applied. Soldering alloy type Sn-Ag-Ti was analysed, and the interactions between the solder and ceramic and/or Cu substrate were studied. The shear strength of fabricated soldered joints was measured.
Characterization of SAC – x NiO nano-reinforced lead-free solder joint in an ultra-fine package assemblyChe Ani, Fakhrozi; Jalar, Azman; Saad, Abdullah Aziz; Khor, Chu Yee; Abas, Mohamad Aizat; Bachok, Zuraihana; Othman, Norinsan Kamil
2019 Soldering & Surface Mount Technology
doi: 10.1108/ssmt-08-2018-0024
This study aims to investigate the NiO nano-reinforced solder joint characteristics of ultra-fine electronic package.Design/methodology/approachLead-free Sn-Ag-Cu (SAC) solder paste was mixed with various percentages of NiO nanoparticles to prepare the new form of nano-reinforced solder paste. The solder paste was applied to assemble the ultra-fine capacitor using the reflow soldering process. A focussed ion beam, high resolution transmission electron microscopy system equipped with energy dispersive X-ray spectroscopy (EDS) was used in this study. In addition, X-ray inspection system, field emission scanning electron microscopy coupled with EDS, X-ray photoelectron spectroscopy (XPS) and nanoindenter were used to analyse the solder void, microstructure, hardness and fillet height of the solder joint.FindingsThe experimental results revealed that the highest fillet height was obtained with the content of 0.01 Wt.% of nano-reinforced NiO, which fulfilled the reliability requirements of the international IPC standard. However, the presence of the NiO in the lead-free solder paste only slightly influenced the changes of the intermetallic layer with the increment of weighted percentage. Moreover, the simulation method was applied to observe the distribution of NiO nanoparticles in the solder joint.Originality/valueThe findings are expected to provide a profound understanding of nano-reinforced solder joint’s characteristics of the ultra-fine package.
Rheology of F620 solder paste and fluxBarbosa, Flavia V.; Teixeira, José C.F.; Teixeira, Senhorinha F.C.F.; Lima, Rui A.M.M.; Soares, Delfim F.; Pinho, Diana M.D.
2019 Soldering & Surface Mount Technology
doi: 10.1108/ssmt-08-2018-0027
The aim of this paper is to characterize the rheological properties of the flux media exposed to different levels of solicitation and to determine its influence on the rheology of the solder paste. The data obtained experimentally are fundamental for the development of numerical models that allow the simulation of the printing process of printed circuit boards (PCB).Design/methodology/approachRheological tests were performed using the Malvern rheometer Bohlin CVO. These experiments consist of the analysis of the viscosity, yield stress, thixotropy, elastic and viscous properties through oscillatory tests and the capacity to recover using a creep-recovery experiment. The results obtained from this rheological analysis are compared with the rheological properties of the solder paste F620.FindingsThe results have shown that the flux is viscoelastic in nature and shear thinning. The viscosity does not decrease with increasing solicitations, except in the case where the flow is withdrawn directly from the bottle. Even if the solder paste shows a thixotropic behavior, this is not the case of the flux, meaning that this property is given by the metal particles. Furthermore, the oscillatory tests proved that the flux presents a dominant solid-like behavior, higher than the solder paste, meaning that the cohesive/tacky behavior of the solder paste is given by the flux.Research limitations/implicationsTo complement this work, printing tests are required.Originality/valueThis work demonstrates the importance of the rheological characterization of the flux in order to understand its influence in the solder paste performance during the stencil printing process.
Design of a bi-manual haptic interface for skill acquisition in surface mount device solderingJames, Jose; Rao R., Bhavani; Neamtu, Gabriel
2019 Soldering & Surface Mount Technology
doi: 10.1108/ssmt-01-2018-0001
Offering unskilled people training in engineering and vocational skills helps to decrease unemployment rate. The purpose of this paper is to augment actual hands-on conventional vocational training methods with virtual haptic simulations as part of computer-based vocational education and training.Design/methodology/approachThis paper discusses the design of a bi-manual virtual multi-modal training interface for learning basic skills in surface mount device hand soldering. This research aims to analyze human hand dexterity of novices and experts at micro level skill knowledge capture by simulating and tracking the users’ actions in the manual soldering process through a multi-modal user interface.FindingsHaptic feedback can enhance the experience of a virtual training environment for the end user and can provide a supplementary modality for imparting tangible principles to increase effectiveness. This will improve the teaching and learning of engineering and vocational skills with touch-based haptics technology, targeted toward teachers and students of various disciplines in engineering. Compared with the traditional training methods for learning soldering skills, the proposed method shows more efficiency in faster skill acquisition and skill learning.Originality/valueIn this study, the authors proposed a novel bi-manual virtual training simulator model for teaching soldering skills for surface mount technology and inspection. This research aims to investigate the acquisition of soldering skills through virtual environment, with and without haptic feedback. This acts as a basic-level training simulator that provides introductory training in soldering skills and can help initially unskilled people find educational opportunities and job offers in the electronics industry.