Thermal stress-strain simulation analysis of BGA solder joint reflow soldering process

2018 ◽  
Author(s):  
Xiang-qiong Tang ◽  
Sheng-jun Zhao ◽  
Chun-yue Huang ◽  
Liang-kun Lu
Keyword(s):  
Thermal Stress ◽  
Solder Joint ◽  
Simulation Analysis ◽  
Stress Strain ◽  
Reflow Soldering ◽  
Soldering Process

A Comparison of Thermal Stress/Strain Behavior of Elliptical/Round Solder Pads

1999 ◽  
Vol 123 (2) ◽  
pp. 127-131 ◽  
Author(s):  
Kuo-Ning Chiang ◽  
Chang-Ming Liu
Keyword(s):  
Thermal Stress ◽  
Solder Joint ◽  
Solder Joints ◽  
Numerical Models ◽  
Ball Grid Array ◽  
Stress Strain ◽  
Restoring Force ◽  
Array Type ◽  
Finite Element Software ◽  
Area Array

As electronic packaging technology moving to the CSP, wafer level packaging, fine pitch BGA (ball grid array) and high density interconnections, the wireability of the PCB/substrate and soldering technology are as important as reliability issues. In this work, a comparison of elliptical/round pads of area array type packages has been studied for soldering, reliability, and wireability requirements. The objective of this research is to develop numerical models for predicting reflow shapes of solder joint under elliptical/round pad boundary conditions and to study the reliability issue of the solder joint. In addition, a three-dimensional solder liquid formation model is developed for predicting the geometry, the restoring force, the wireability, and the reliability of solder joints in an area array type interconnections (e.g., ball grid array, flip chip) under elliptical and round pad configurations. In general, the reliability of the solder joints is highly dependent on the thermal-mechanical behaviors of the solder and the geometry configuration of the solder ball. These reliability factors include standoff height/contact angle of the solder joint, and the geometry layout/material properties of the package. An optimized solder pad design cannot only lead to a good reliability life of the solder joint but also can achieve a better wireability of the substrate. Furthermore, the solder reflow simulation used in this study is based on an energy minimization engine called Surface Evolver and the finite element software ABAQUS is used for thermal stress/strain nonlinear analysis.

Mechanical reliability of self-aligned chip assembly after reflow soldering process

2020 ◽  
Vol 33 (1) ◽  
pp. 9-17
Author(s):  
Mohd Najib Ali Mokhtar ◽  
M.Z. Abdullah ◽  
Abdullah Aziz Saad ◽  
Fakhrozi Cheani
Keyword(s):  
Shear Strength ◽  
Statistical Analysis ◽  
Solder Joint ◽  
Silver Content ◽  
The Self ◽  
Mechanical Reliability ◽  
Reflow Soldering ◽  
Content Type ◽  
Strength Assessment ◽  
Soldering Process

Purpose This paper focuses on the reliability of the solder joint after the self-alignment phenomenon during reflow soldering. The aim of this study is to analyse the joint quality of the self-alignment assemblies of SnAg alloy solder joints with varying silver content. Design/methodology/approach The shear strength assessment was conducted in accordance with the JIS Z3 198-7 standard. The standard visual inspection of IPC-A-610G was also performed to inspect the self-alignment features of the solder joint samples. Statistical analysis was conducted to determine the probabilistic relationship of shear strength of the misalignment components. Findings The results from the mechanical reliability study indicate that there were decreasing trends in the shear strength value as misalignment offset increased. For shift mode configuration in the range of 0-300 µm, the resulting chip assembly inspection after the reflow process was in line with the IPC-A-610G standard. The statistical analysis shows that the solder type variation was insignificant to the shear strength of the chip resistor. The study concluded that the fracture occurred partially in the termination metallization at the lower part of the chip resistor. The copper content of the joint on that area shows that the crack occurred in the solder joint, and high silver content on the selected zone indicated that the fracture happened partially in the termination structure, as the termination structure of the lead-free chip resistor consists of an inner layer of silver and an outer layer of tin. Practical implications This study’s findings provide valuable guidelines and references to engineers and integrated circuit designers during the reflow soldering process in the microelectronics industry. Originality/value Studies on the effect of component misalignment on joint mechanical reliability are still limited, and studies on solder joint reliability involving the effect of differing contents of silver on varying chip component offset are rarely reported. Thus, this study is important to effectively bridge the research gap and yield appropriate guidelines in the potential industry.

CONTROLLING AND OPTIMIZATION OF THERMAL PROFILE IN REFLOW SOLDERING

2009 ◽  
Vol 23 (06n07) ◽  
pp. 1949-1955
Author(s):  
JIANWEI SHI ◽  
PENG HE ◽  
XIAOCHUN LV
Keyword(s):  
Solder Joint ◽  
Circuit Board ◽  
Solder Paste ◽  
Thermal Profile ◽  
Reflow Soldering ◽  
Soldering Process ◽  
Joint Reliability ◽  
Controlling Parameter ◽  
Technical Evaluation ◽  
Reliability Of Solder Joints

Heating factor, Q is a quantitative parameter describing a process of reflow soldering. It can be used to evaluate a reflow soldering process and the reliability of solder joints. The value of Q is directly related to the energy absorbed by solder joint during heating and the morphology of Intermetallic Compound formed at the interface between solder and pad. Electronic product manufacturers use heating factor as a technical evaluation parameter to guide the adjustment of reflow soldering process and the optimization of reflow soldering curve, to ensure the best reliability of the circuit board. Solder paste manufacturers use heating factor to represent characteristics of their reflow soldering products, and to customize products according to consumer's requests. Equipment manufacturers for reflow soldering use heating factor as an important controlling parameter to establish automatic system for managing solder joint reliability. A reliable soldering result can be achieved using the automatic reflow management system, to control and optimize thermal profile, which leads to the adjustment of the heating factor.

Case Analysis on PTH Fracture Caused by Twin Copper

2014 ◽  
Vol 1061-1062 ◽  
pp. 431-435
Author(s):  
Xiao He
Keyword(s):  
Thermal Analysis ◽  
Thermal Stress ◽  
Theoretical Analysis ◽  
Cross Section ◽  
Current Density ◽  
Case Analysis ◽  
Actual Case ◽  
Soldering Process ◽  
Root Cause ◽  
Section Analysis

An actual case of PTH fracture after soldering process was studied. By means of cross section analysis using metallography microscope and SEM, together with thermal analysis results, root cause of PTH fracture was concluded that a high density of twin copper weakened the mechanical strength so seriously that PTHs could not undergo thermal stress from soldering process, and higher CTE was attributed to an accelerative factor. Moreover, it is recommended to enhance current density properly and make sure the effectiveness of electroplating additives to prevent twin copper by theoretical analysis.

scholarly journals Head-on-Pillow Defect Detection: X-Ray Inspection Limitations

2019 ◽  
Vol 16 (2) ◽  
pp. 91-102
Author(s):  
Lars Bruno ◽  
Benny Gustafson
Keyword(s):  
Solder Joints ◽  
Solder Paste ◽  
Wafer Level ◽  
Reflow Soldering ◽  
X Ray ◽  
Soldering Process ◽  
Irregular Shapes ◽  
Fine Pitch ◽  
Solder Balls ◽  
Ball Grid Array Packages

Abstract Both the number and the variants of ball grid array packages (BGAs) are tending to increase on network printed board assemblies with sizes ranging from a few millimeter die size wafer level packages with low ball count to large multidie system-in-package (SiP) BGAs with 60–70 mm side lengths and thousands of I/Os. One big challenge, especially for large BGAs, SiPs, and for thin fine-pitch BGA assemblies, is the dynamic warpage during the reflow soldering process. This warpage could lead to solder balls losing contact with the solder paste and its flux during parts of the soldering process, and this may result in solder joints with irregular shapes, indicating poor or no coalescence between the added solder and the BGA balls. This defect is called head-on-pillow (HoP) and is a failure type that is difficult to determine. In this study, x-ray inspection was used as a first step to find deliberately induced HoP defects, followed by prying off of the BGAs to verify real HoP defects and the fault detection correlation between the two methods. The result clearly shows that many of the solder joints classified as potential HoP defects in the x-ray analysis have no evidence at all of HoP after pry-off. This illustrates the difficulty of determining where to draw the line between pass and fail for HoP defects when using x-ray inspection.

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