Solder Joint Formation Simulation and Component Tombstoning Prediction During Reflow

1998 ◽  
Vol 120 (2) ◽  
pp. 141-144 ◽  
Author(s):  
X. Wu ◽  
X. Dou ◽  
C.-P. Yeh ◽  
K. Waytt
Keyword(s):  
Solder Joint ◽  
Model Simulation ◽  
Software Tool ◽  
Solder Paste ◽  
Reflow Process ◽  
Surface Evolver ◽  
Joint Formation ◽  
Geometry Design ◽  
Reliability Performance ◽  
Public Domain Software

The failure of electrical devices associated with solder joints has become one of the most critical reliability issues for surface-mounted devices. Solder joint reliability performance has been found to be highly dependent on the solder joint configuration, which, in turn, is governed by bond pad size, alloy material, and leadframe structure, as well as solder reflow characteristics. To investigate tombstone effects causing solder joint failure during leadless component reflow process, this work has focused on (1) developing a numerical model for the simulations of the solder joint formation during the reflow process, and (2) determining possibility that a tombstone effect for the leadless component may occur by analyzing the force and torque in the problem. Using this methodology, the tombstone effect associated with different pad geometry configurations and solder paste amount has been analyzed through the application of the public domain software tool Surface Evolver. Simulations show that the tombstoning is very sensitive to pad/component geometry design, solder surface tension, solder paste volume, wetting area, and wetting angle. This model simulation can be used to determine optimal solder paste volume, pad geometry configurations, and solder material for avoiding tombstone effects.

Prediction of Liquid Formation for Solder and Non-Solder Mask Defined Array Packages

1999 ◽  
Vol 124 (1) ◽  
pp. 37-44 ◽  
Author(s):  
Wen-Hwa Chen ◽  
Kuo-Ning Chiang ◽  
Shu-Ru Lin
Keyword(s):  
Solder Joint ◽  
Solder Joints ◽  
Reflow Process ◽  
Surface Evolver ◽  
Restoring Force ◽  
Solder Mask ◽  
The Difference ◽  
Design Factors ◽  
Joint Volume ◽  
Liquid Formation

This study presents an efficient method to accurately predict solder joint geometry after a reflow process. The proposed method can be utilized for Solder Mask Defined (SMD), Non-Solder Mask Defined (NSMD), or C4 type solder joints. The reflow process involves several design factors capable of influencing the final shape of the molten solder joint, such as solder joint volume, restoring force, surface tension, contact angle, pad thickness, and pad size. These factors are all considered in the calculations. The computed results are compared with those using the Surface Evolver program and also with available numerical/experimental results. Their excellent agreement shows that the method developed herein can be practically applied to predict the reflow shape of SMD/NSMD solder joints. The difference between SMD and NSMD is also examined in detail. Results in this study provide designers with a fundamental guideline for accurately predicting the liquid formation of solder joints during the reflow process.

A Novel Approach to Optimizing Solder Reflow Process in Assembling PQFN Packages

2009 ◽  
Author(s):  
Youmin Yu ◽  
Y. Q. Su ◽  
S. A. Yao ◽  
Y. W. Jiang ◽  
Sonder Wang
Keyword(s):  
Optimal Transport ◽  
Void Formation ◽  
Present Approach ◽  
Solder Paste ◽  
Trial And Error ◽  
Lead Frame ◽  
Reflow Process ◽  
Novel Approach ◽  
Underlying Principle ◽  
Reliability Performance

Solder void is a common defect during assembling Power Quad Flat No-lead (PQFN) packages. It is detrimental to the packages’ feature of good power management and reliability performance and needs to be controlled within certain specification. Reflow process is well considered as critical to the solder void formation for a given solder paste. The transport index of reflow oven, which determines how solder paste are reflowed through solder reflowing process within the reflow oven, has therefore been optimized by a novel approach in this study. The underlying principle of the optimization is to find such a transport index that solder paste have a best possibility to experience homogeneous heat transfer during reflow phase of the whole reflow process. Different from the traditionally experimental trial and error, the present approach first predicts the optimal transport index by calculating the relative locations of lead frame (solder paste are dispensed on it) to the heating blocks of the reflow oven and the amount of heat input at different locations on the lead frame during the reflow phase. Then only necessary experiments are conducted to validate the prediction. As the theoretic calculations already screen out part of experiments that have to be conducted in the traditional trial and error, the present approach saves time and cost in practice.

Numerical and Experimental Analysis of Solder Joint Self-Alignment in Fiber Attachment Soldering

2008 ◽  
Vol 130 (1) ◽  
Author(s):  
Wei Zhang ◽  
Chunqing Wang ◽  
Yanhong Tian
Keyword(s):  
Solder Joint ◽  
Low Cost ◽  
Three Dimensional ◽  
Major Axis ◽  
The Self ◽  
Alignment Error ◽  
Surface Evolver ◽  
Confocal Scanning Laser Microscope ◽  
Solder Volume ◽  
Public Domain Software

Fiber attachment soldering is low cost and high-precision technology in direct-coupling optoelectronic packaging. For accurate alignment, it is crucial to understand the self-alignment behavior of solder joint. In this research, the self-alignment method by using surface tension of molten solder and by adopting specific pad shape was proposed. First, the self-alignment model of solder joint in fiber attachment soldering was developed by using the public domain software called SURFACE EVOLVER and the three-dimensional geometry of solder joint with different solder volume was analyzed. Then, the self-alignment behavior of solder joint with an initial yaw misalignment was discussed and the theoretical equilibrium positions of ellipse and square pad were calculated. Next, based on the minimum potential energy theorem and data from geometry simulation, the influences of design and material parameters on the standoff height (SOH) were analyzed. Furthermore, experiments were done to examine the theoretical equilibrium positions of ellipse and square pad and the SOHs of solder joints were measured by using confocal scanning laser microscope. The numerical results show that the theoretical equilibrium positions of ellipse and square pad are the major axis of ellipse and the diagonal of square, respectively. SOH can be controlled by adopting proper solder volume, which is above the critical value for specific pad. The experimental results show that the solder joint with initial yaw angle can be self-aligned to the theoretical equilibrium position of pad and solder joint with ellipse pad substrate demonstrates smaller alignment error than those with square pad substrate. The measurement results of SOH are in agreement with the simulation results.

Solder Joint Formation in Surface Mount Technology—Part I: Analysis

1990 ◽  
Vol 112 (3) ◽  
pp. 210-218 ◽  
Author(s):  
S. M. Heinrich ◽  
A. F. Elkouh ◽  
N. J. Nigro ◽  
Ping S. Lee
Keyword(s):  
Solder Joint ◽  
Laboratory Data ◽  
Integral Form ◽  
Contact Angles ◽  
Reflow Process ◽  
Cross Sectional ◽  
Joint Formation ◽  
Surface Mount ◽  
Theoretical Predictions ◽  
Joint Shape

An analytical model of solder joint formation during a surface mount reflow process is developed in the present paper, and the solution is obtained in an explicit integral form. For two limiting cases—infinitesimal and infinite solder areas—the solution is expressed in closed form. Numerical results illustrate the influence of the process parameters (surface tension, density, and cross-sectional area of the molten solder, and the contact angles between the solder andpretinning) on joint shape and overall fillet dimensions. Comparisons between theoretical predictions and laboratory data show excellent agreement.

scholarly journals Study on the Reliability of Sn–Bi Composite Solder Pastes with Thermosetting Epoxy under Thermal Cycling and Humidity Treatment

Crystals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 733
Author(s):  
Lu Liu ◽  
Songbai Xue ◽  
Ruiyang Ni ◽  
Peng Zhang ◽  
Jie Wu
Keyword(s):  
Solder Joint ◽  
Thermal Cycling ◽  
Composite Solder ◽  
Solder Joints ◽  
Solder Paste ◽  
Epoxy System ◽  
Mechanical Reinforcement ◽  
Microstructure Observation ◽  
Temperature And Humidity ◽  
Thermosetting Epoxy

In this study, a Sn–Bi composite solder paste with thermosetting epoxy (TSEP Sn–Bi) was prepared by mixing Sn–Bi solder powder, flux, and epoxy system. The melting characteristics of the Sn–Bi solder alloy and the curing reaction of the epoxy system were measured by differential scanning calorimeter (DSC). A reflow profile was optimized based on the Sn–Bi reflow profile, and the Organic Solderability Preservative (OSP) Cu pad mounted 0603 chip resistor was chosen to reflow soldering and to prepare samples of the corresponding joint. The high temperature and humidity reliability of the solder joints at 85 °C/85% RH (Relative Humidity) for 1000 h and the thermal cycle reliability of the solder joints from −40 °C to 125 °C for 1000 cycles were investigated. Compared to the Sn–Bi solder joint, the TSEP Sn–Bi solder joints had increased reliability. The microstructure observation shows that the epoxy resin curing process did not affect the transformation of the microstructure. The shear force of the TSEP Sn–Bi solder joints after 1000 cycles of thermal cycling test was 1.23–1.35 times higher than the Sn–Bi solder joint and after 1000 h of temperature and humidity tests was 1.14–1.27 times higher than the Sn–Bi solder joint. The fracture analysis indicated that the cured cover layer could still have a mechanical reinforcement to the TSEP Sn–Bi solder joints after these reliability tests.

Wettability of CNT-Doped Solder under Isothermal Aging

2016 ◽  
Vol 857 ◽  
pp. 76-78
Author(s):  
Norliza Ismail ◽  
Roslina Ismail ◽  
Nur Izni Abd Aziz ◽  
Azman Jalar
Keyword(s):  
Carbon Nanotubes ◽  
Contact Angle ◽  
Isothermal Aging ◽  
Optical Microscope ◽  
Image Analyzer ◽  
Solder Paste ◽  
Reflow Process ◽  
Weight Percentage ◽  
Test Board ◽  
Free Solder

Wettability for lead free solder 99.0Sn-0.3Ag-0.7Cu (SAC237) with addition of different weight percentage carbon nanotube after thermal treatment was investigated. SAC 237 solder powder with flux was mixed with 0.01%, 0.02%, 0.03% and 0.04% carbon nanotubes (CNTs) to form SAC-CNTs solder paste. Printed solder paste on test board with Cu surface finish was then reflow under 270°C temperature and isothermal aging at 150°C for 0,200 and 400 hours. Wettability of SAC-CNT solder was determined by measuring contact angle using optical microscope and image analyzer. As a result, from reflow process right through 400 hours of thermal aging, SAC237 with 0.04% CNT has the lowest contact angle as compared to other SAC-CNTs and SAC237 solder. As a conclusion, addition of carbon nanotubes into solder SAC237 improved their wettability on Cu substrate, especially at 0.04% of CNTs.

Effects of doping trace Ni element on interfacial behavior of Sn/Ni (polycrystal/single-crystal) joints

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Jianing Wang ◽  
Jieshi Chen ◽  
Zhiyuan Zhang ◽  
Peilei Zhang ◽  
Zhishui Yu ◽  
...  
Keyword(s):  
Solder Joint ◽  
Single Crystal ◽  
Microstructure Evolution ◽  
Thermal Aging ◽  
Interfacial Layer ◽  
Aging Treatment ◽  
Growth Behavior ◽  
Reflow Process ◽  
Content Type ◽  
Ni Substrate

Purpose The purpose of this article is the effect of doping minor Ni on the microstructure evolution of a Sn-xNi (x = 0, 0.05 and 0.1 wt.%)/Ni (Poly-crystal/Single-crystal abbreviated as PC Ni/SC Ni) solder joint during reflow and aging treatment. Results showed that the intermetallic compounds (IMCs) of the interfacial layer of Sn-xNi/PC Ni joints were Ni3Sn4 phase, while the IMCs of Sn-xNi/SC Ni joints were NiSn4 phase. After the reflow process and thermal aging of different joints, the growth behavior of interfacial layer was different due to the different mechanism of element diffusion of the two substrates. The PC Ni substrate mainly provided Ni atoms through grain boundary diffusion. The Ni3Sn4 phase of the Sn0.05Ni/PC Ni joint was finer, and the diffusion flux of Sn and Ni elements increased, so the Ni3Sn4 layer of this joint was the thickest. The SC Ni substrate mainly provided Ni atoms through the lattice diffusion. The Sn0.1Ni/SC Ni joint increases the number of Ni atoms at the interface due to the doping of 0.1Ni (wt.%) elements, so the joint had the thickest NiSn4 layer. Design/methodology/approach The effects of doping minor Ni on the microstructure evolution of an Sn-xNi (x = 0, 0.05 and 0.1 Wt.%)/Ni (Poly-crystal/Single-crystal abbreviated as PC Ni/SC Ni) solder joint during reflow and aging treatment was investigated in this study. Findings Results showed that the intermetallic compounds (IMCs) of the interfacial layer of Sn-xNi/PC Ni joints were Ni3Sn4 phase, while the IMCs of Sn-xNi/SC Ni joints were NiSn4 phase. After the reflow process and thermal aging of different joints, the growth behavior of the interfacial layer was different due to the different mechanisms of element diffusion of the two substrates. Originality/value In this study, the effect of doping Ni on the growth and formation mechanism of IMCs of the Sn-xNi/Ni (single-crystal) solder joints (x = 0, 0.05 and 0.1 Wt.%) was investigated.

Dynamic Aspects of Wetting Balance Tests

1996 ◽  
Vol 118 (3) ◽  
pp. 174-183 ◽  
Author(s):  
K. W. Moon ◽  
W. J. Boettinger ◽  
M. E. Williams ◽  
D. Josell ◽  
B. T. Murray ◽  
...  
Keyword(s):  
Software Package ◽  
Room Temperature ◽  
Silicone Oil ◽  
Surface Evolver ◽  
The Public ◽  
Meniscus Shape ◽  
Balance Tests ◽  
Glass Plates ◽  
Measured Force ◽  
Public Domain Software

The relationships between the force measured during wetting balance tests and the observed changes of contact angle and meniscus shape are studied. Experiments using silicone oil at 25, 50, and 100°C on glass plates as well as Pb-Sn eutectic solder on Au-coated glass plates are reported. Discrepancies between the measured force and height and those expected for a static meniscus are detailed. Equilibrium meniscus shapes are computed for wide plates using the elastica solution and for narrow plates using the public-domain software package, “Surface Evolver.” For room temperature experiments with oil, the measured force discrepancy disappears when the meniscus rise is complete. Thus, the force discrepancy may be due to shear stress exerted on the sample by fluid rising up the sample. For static menisci with heated liquids, force and meniscus height discrepancies do not disappear when the meniscus rise is complete. These discrepancies can be explained by Marangoni flow due to temperature gradients in the fluid for the oil experiments but not for the solder experiments.

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