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In this paper, the effects of package level structures and material properties on solder joint reliability subjected to impact loading are investigated by the integrated experimental testing, failure analysis, and finite element modeling. Three different package structures: ball on I/O wafer level package (WLP), copper post WLP, and chip-scale (CS) ball grid array (BGA) package, are studied. Experimental...
This paper will focus on the fast assessment methodology of FBGA fatigue life through simulation and physics of failure (PoF) analysis under thermal cycle. The structure of fine pitch ball grid array (FBGA) that has been investigated, and been modeled by ANSYS to compare with experimental data. There are two temperature cycling will be used, one is used to verify FEA model, and the other one is used...
Modern trends in design of electrical products require miniaturization and multi-function. In line with these trends, dimensions of lead-free solder joints reduce from over 100µm to 10µm, resulting in some new reliability issues. A high fraction of intermetallic compounds (IMC) with various shapes is a key feature in micro-solder joints. So far, few investigations focused on the influence of high...
Comprehensive finite element analysis (FEA) modeling is carried out to improve the performance of critical designs of wafer level chip scale package (WLCSP). First, a design with one layer redistribution layout (RDL) copper with etched pocket in the non-covered UBM area and one layer polyimide structure (1Cu1Pi design) is investigated. Different polyimide layouts, copper thicknesses, pocket parameters...
Three dimensional finite element analysis (FEA) is performed to assess the board level temperature cycling reliability for lead-free solder Sn96.5Ag3Cu0.5 (SAC305) used in eWLB packages. With Anand viscoplastic constitutive model used for the solder material, the chosen damage parameters, i.e. accumulated creep strain or accumulated creep strain energy density, can be derived from the finite element...
Peridynamic (PD) theory is used to investigate the dynamic responses of electronic packages subjected to impact loading arising from drop-shock. The capability of the PD theory to predict failure is demonstrated by simulating a drop test experiment of a laboratory-type package. The failure predictions and observations are exceptionally similar. For the drop test simulation of a production-type package,...
This study examines the dynamic fracture propagation experienced by critical solder joints in a BGA test package during board-level single drop test. An Input-G loading method is employed to simulate a drop test condition with a peak acceleration of 1500G within a time duration of 0.5 ms. Unified inelastic strain model (Anand) describes the strain rate-dependent response of the SAC405 solder material...
Analysis using ANSYS software, CSP component was reduced to two-dimensional model. In the thermal cyclic loading conditions using finite element simulating the stress and strain distribution of CSP components, obtained a dangerous solder joint of structural failure. The number of failure cycles about dangerous solder joint was predicted. Finally, introduced several analysis and evaluation method for...
Non-linear finite element simulation by an elastic-viscoplastic constitutive model and the experimental characterization were carried out to investigate the volume effect of BGA structure solder joints under shear stress. A solder mask defined flat type copper pad of a circular opening 480 μm diameter and Sn3.0Ag0.5Cu (SAC) lead-free solder balls of 300–760 μm in diameter, were used to fabricate BGA...
The influences of the standoff height (H), contact angle (θ), pad size and loading rate on shear fracture behavior of BGA structure Cu/Sn-3.0Ag-0.5Cu/Cu joints were investigated by finite element (FE) method. The simulation results show that the maximum Von Mises stress zones locate on the edge of the solder near the intermetallic compound (IMC) layer in the BGA joint under shear stress, the cracks...
Solder joints, which serve as mechanical, thermal and electrical interconnections between the electronic packages and the printed circuit board (PCB), are the most vulnerable part in a portable product when the product is subjected to mechanical loading. Therefore, a comprehensive study of mechanics behavior of solder joints is indispensable for understanding the reliability of portable electronic...
This article describes recent advance in research of reliability of lead-free (SAC 305) ball interconnections between electronic modules and base printed circuit boards. Alternative methods such as finite element method, which is being widely used in simulation software Ansys and by Coffin-Manson's fatigue model. Recent calculations concur to statistic-based evaluation of earlier experiments, which...
3D packaging is one of the main emerging markets especially for mobile application within the last view years. Mobile devices are exposed and hence need to be reliable under to vibration or mechanical shock conditions. Therefore, material properties covering strain rate dependency have to be at hand within reliability studies. Miniature bulk specimens were utilized to gain stress and strain data at...
In recent years, electronic product have been demanded more functionalities, miniaturization, higher performance, reliability and low cost. Therefore, IC chip is required to deliver more signal I/O and better electrical characteristics under the same package footprint. None-Lead Bump Array (NBA) Chip Scale Structure is then developed to meet those requirements offering better electrical performance,...
Thus far, there is a severe lack of understanding about interfacial fracture and impact behavior of the microscale lead-free solder interconnects. In this study, the finite element simulation and analytical method were used to characterize the interfacial fracture and impact behavior at the interfaces of the microscale Sn-Ag-Cu solder joints. The intersection of a linear microcrack tip upon Sn-Ag-Cu...
Warpage, high stress in dies and solder joints are introduced in assembly process of a package-on-package component. In this paper, a finite element approach is proposed to predict the warpages and stresses during the full assembly process. By the techniques of element die and birth as well as restart method, the approach is able to transfer the stress and warpage in one process to the next so that...
Wafer level Chip Scale Package (WLCSP) fulfills the demand for small, light, and portable handheld electronic devices, and it is one of the most advanced packaging concepts. When the WLCSP was assembled on board level, the connection, i.e. solder joints are generally the critical and challenging issue for the whole device's reliability. In addition to the shape and material of solder joints, the material...
Prevalence of portable devices such as netbook led to increased concerns on drop reliability of FBGA. In order to investigate drop reliability, board level drop test according to Jedec is done in assembly and SMT company, whereas system drop test such as netbook drop test is processed in final product company. In general, the lifetime of Jedec board level drop test and the lifetime of system drop...
The purpose of this paper is to compare the ability of solder joint with different shape (hourglass-shaped, barrel-shaped and cylinder-shaped) to resist destruction under drop impact loadings. Three 3D finite element models of VFBGA (very-thin-profile fine-pitch BGA) packages, including different shape of solder joints, are established respectively. According to the condition B in the drop test standard...
Interfacial fracturing is the most important failure mode of solder joints. In this paper, interfacial stresses of Cu pad/solder interfaces are evaluated based on the theory of interfacial mechanics and the finite element method. Effects of solder joint shapes and solder materials on the stress intensity are investigated. The results show that Sn37Pb/Cu interface has greater stress intensity than...
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