Effects of Solder Joint Voiding and Seating Plane Stability on Surface Mount Lead Standoff

1994 ◽  
Vol 116 (2) ◽  
pp. 89-91 ◽  
Author(s):  
M. K. Schwiebert
Keyword(s):  
Simple Model ◽  
Solder Joint ◽  
Solder Joints ◽  
Reaction Force ◽  
Molten Solder ◽  
Surface Mount Technology ◽  
Surface Mount

This study considers the influence of solder joint voiding and seating plane stability on the lead standoffs of surface mount technology (SMT) solder joints. A model is presented for approximating the reaction force generated by a gas-filled void in molten solder which is compressed under an SMT lead. Seating plane stability is defined with a simple model. The lead standoffs of a component with an unstable seating plane are sensitive to small forces. For some SMT components, the reaction force generated by compressed voids in molten solder can tilt or rock a component, resulting in lead standoffs much greater than the measured lead coplanarity.

Solder Joint Formation in Surface Mount Technology—Part II: Design

1990 ◽  
Vol 112 (3) ◽  
pp. 219-222 ◽  
Author(s):  
S. M. Heinrich ◽  
N. J. Nigro ◽  
A. F. Elkouh ◽  
P. S. Lee
Keyword(s):  
Surface Tension ◽  
Solder Joint ◽  
Solder Joints ◽  
Cross Sectional Area ◽  
Surface Mount Technology ◽  
Sectional Area ◽  
Cross Sectional ◽  
Joint Formation ◽  
Surface Mount ◽  
Surface Tension Model

In this paper dimensionless design curves relating fillet height and length to joint cross-sectional area are presented for surface-mount solder joints. Based on an analytical surface tension model, the advantage of these dimensionless curves is that they may be used for arbitrary values of solder density and surface tension. The range of applicability of previously developed approximate formulae for predicting joint dimensions is also investigated. A simple example problem is included to illustrate the use of both the design curves and the approximate formulae.

Effect of intermetallic compound layer thickness on the shear strength of 1206 chip resistor solder joint

2015 ◽  
Vol 27 (1) ◽  
pp. 52-58 ◽  
Author(s):  
Peter K. Bernasko ◽  
Sabuj Mallik ◽  
G. Takyi
Keyword(s):  
Shear Strength ◽  
Intermetallic Compound ◽  
Solder Joint ◽  
Layer Thickness ◽  
Solder Joints ◽  
Ageing Time ◽  
Circuit Board ◽  
Intermetallic Compound Layer ◽  
Content Type ◽  
Surface Mount

Purpose – The purpose of this paper is to study the effect of intermetallic compound (IMC) layer thickness on the shear strength of surface-mount component 1206 chip resistor solder joints. Design/methodology/approach – To evaluate the shear strength and IMC thickness of the 1206 chip resistor solder joints, the test vehicles were conventionally reflowed for 480 seconds at a peak temperature of 240°C at different isothermal ageing times of 100, 200 and 300 hours. A cross-sectional study was conducted on the reflowed and aged 1206 chip resistor solder joints. The shear strength of the solder joints aged at 100, 200 and 300 hours was measured using a shear tester (Dage-4000PXY bond tester). Findings – It was found that the growth of IMC layer thickness increases as the ageing time increases at a constant temperature of 175°C, which resulted in a reduction of solder joint strength due to its brittle nature. It was also found that the shear strength of the reflowed 1206 chip resistor solder joint was higher than the aged joints. Moreover, it was revealed that the shear strength of the 1206 resistor solder joints aged at 100, 200 and 300 hours was influenced by the ageing reaction times. The results also indicate that an increase in ageing time and temperature does not have much influence on the formation and growth of Kirkendall voids. Research limitations/implications – A proper correlation between shear strength and fracture mode is required. Practical implications – The IMC thickness can be used to predict the shear strength of the component/printed circuit board pad solder joint. Originality/value – The shear strength of the 1206 chip resistor solder joint is a function of ageing time and temperature (°C). Therefore, it is vital to consider the shear strength of the surface-mount chip component in high-temperature electronics.

Stress Analysis of Surface-Mount Interconnections Due to Vibrational Loading

1997 ◽  
Vol 119 (3) ◽  
pp. 183-188 ◽  
Author(s):  
K. Darbha ◽  
S. Ling ◽  
A. Dasgupta
Keyword(s):  
Finite Element ◽  
Solder Joint ◽  
Stress Analysis ◽  
Solder Joints ◽  
Test Time ◽  
Clear Understanding ◽  
Local Curvature ◽  
Surface Mount ◽  
Quantitative Models ◽  
Vibrational Loading

Recently, accelerated testing of surface mount interconnects under combined temperature and vibration environments has been recognized to be a necessary activity to ensure enhanced test-time compression. Successful use of vibration stresses requires a clear understanding of the correlation between vibrational damage and thermomechanical damage in surface mount solder joints. Hence, fatigue due to vibrational loading is important and accurate quantitative models are required to model effects due to vibrational fatigue. The proposed analysis in this paper contributes towards development of such quantitative models. This paper presents an approximate method to analyze stresses in surface mount solder joints subjected to vibration loading, using a generalized multidomain Rayleigh-Ritz approach (Ling and Dasgupta, 1995). The advantage of this approach is in its computational efficiency, compared to general-purpose finite element methods. Ling developed this approach in the context of thermomechanical stress analysis of solder joints. In this paper, the technique is modified and adapted for analyzing stresses caused by out-of-plane flexural dynamic modes of the printed wiring boards (PWBs). The analysis uses a two-step procedure where the local PWB curvatures are first estimated and the resulting deformations in the solder interconnect are then determined. The input boundary conditions for the first step are the bending moments in the PWB due to random vibrations. The stiffness of the interconnect assembly is then predicted using an energy method and curved-beam analysis. The bending moment and the computed stiffness of the interconnect assembly are then used to predict the local curvature of the PWB under any given surface-mount component by using an eigenfunction technique developed by Suhir (Suhir, 1988). In the second step of the analysis, the local curvature of the PWB is used as a boundary condition to predict the state of deformations, stresses, and strains in the solder joint using a modified version of the multidomain Rayleigh-Ritz approach. The overall method is applied to a specific example (J-lead solder joint) for illustrative purposes, and compared to finite element predictions for validation.

Fracture Life Evaluation of Cu-Cored Solder Joint in BGA Package

2009 ◽  
Author(s):  
Hisashi Tanie ◽  
Nobuhiko Chiwata ◽  
Motoki Wakano ◽  
Masaru Fujiyoshi ◽  
Takeyuki Itabashi
Keyword(s):  
Solder Joint ◽  
Crack Propagation ◽  
Shape Analysis ◽  
Fracture Mechanism ◽  
Solder Joints ◽  
Joint Stiffness ◽  
Molten Solder ◽  
Initiation Point ◽  
Mps Method ◽  
Propagation Analysis

A Cu-cored solder joint has an accurate height, a low thermal resistance, and a low electric resistance. However, the fracture mechanism of Cu-cored solder joints has yet to be clarified, and thus the fracture life cannot be predicted. We evaluated the fracture life of Cu-cored solder joints by using our molten-solder-shape analysis and crack-propagation analysis methods. Our molten-solder-shape analysis is based on the moving-particle semi-implicit (MPS) method. In the MPS method, a continuum is expressed as an assembly of particles. In contrast to finite element analysis (FEA), the MPS method can easily express a large deformation and any geometric topology changes, because the continuum does not need to be divided into elements. Using our molten-solder-shape analysis, we could calculate the shapes of Cu-cored solder after the reflow process. Our crack-propagation analysis has a feature where a crack initiation point and the crack propagation paths are automatically calculated and where the fracture life is quantitatively evaluated using FEA. Using our crack-propagation analysis, we could analyze the fracture mechanism of Cu-cored solder joints. By combining our molten-solder-shape and crack-propagation analyses, we could evaluate the fracture life of Cu-cored solder joints in a ball grid array package. As a result, we found that the fracture life of Cu-cored solder joints is longer than that of conventional joints. The height of a joint is one of the reasons for the improved fracture life. Since the height of a Cu-cored solder joint is controlled by the size of the core ball, the height is larger and more highly accurate than that in conventional joints. Accordingly, the solder strain and strain variation are decreased. Joint stiffness is the second reason for the improved fracture life. Cu is harder than solder, so the joint stiffness of a Cu-cored joint is greater than that of conventional joints. Accordingly, the displacement of a joint is decreased. The crack-propagation behavior is the third reason for the improved fracture life. In a conventional solder joint, a solder crack only propagates near the interface of the solder and the land. In a Cu-cored solder joint, a solder crack not only propagates near the interface of the solder and the land, but also at the interface of the solder and core ball. The crack-propagation life is longer than that in a conventional joint due to crack-path scattering. We found that the fracture life of Cu-cored solder joints is improved by using these mechanisms.

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