Structural Assessment of Lead Free Solder Joint of Miniaturized Electronics Assembly

This paper presents a study on structural assessment of ultra-fine package assembly with nano-composites lead free solder joint after reflow soldering process. In this work, various nanoparticles (i.e. TiO2, Fe2O3 and NiO) with different weightage percentage (i.e., 0.01, 0.05 and 0.15 wt.%) were successfully incorporated into SAC305 solder paste using the mechanical solder paste mixer to synthesize novel lead-free composite solders. Effects of the nanoparticles addition on the quality of joining and fillet height between various weightage (wt.%) for the ultra-fine package assembly in the reflow soldering process have been investigated after the reflow soldering process by using the scanning electron microscope (SEM) system equipped with an energy dispersive X-ray spectroscopy (EDS) and XTV 160 x-ray inspection system. The experimental results show the increment of TiO2, Fe2O3 and NiO nanoparticles addition to 0.15wt.%, 0.05wt.% and 0.01wt.%, respectively, produce highest fillet height of each composition of nanoparticles solder paste. Among all these new composition of nanoparticles solder paste, NiO nanoparticles reinforced solder paste with 0.01wt.% yielded highest fillet height The miniaturized solder joints do not cause any problem in terms of solder voids. The findings show the capability of the reflow soldering process in assembling miniaturized electronics assembly and expected to provide a reference in electronic package industry

Reliability Assessment Of Self-Alignment Assemblies Of Chip Component After Reflow Soldering Process

Reliability of surface mount components and interconnect are significant issues in electronic manufacturing. Although the reliability of devices has been broadly studied,here we are focusing on the reliability of the solder joint after the self-alignment phenomena during reflow soldering.In this study,the quality of the self-alignment assemblies was analyzed relate to the joint shear strength according to the JIS Z3 198-7 standard and the inspection according to IPC-A-610E standard.The results from reliability study indicate that the shear strength of the misalignment component of solder joints indeed depends on the degree of chip component misalignment.For shift mode configuration in the range of 0-300µm,the resulted chip assembly inspection after the reflow process was in line with the IPC-A-610E standard

Soldering Characteristics And Thermomechanical Properties Of Pb-Free Solder Paste For Reflow Soldering

A deep understanding in thermal characteristics of lead-free solder paste grades is one of the most crucial factors when dealing with reflow soldering process. These temperatures are critical parameters for proper settings of the real reflow process. This report is devoted to discussing the findings obtained during utilization of differential scanning calorimetry (DSC) and calculation using MATLAB to identify the latent heat, solidus and liquidus temperature, and surface tension applicable to numerically simulate the real process of reflow soldering. It can be stated that the equilibrium solidus and liquidus temperatures during solidification process are not a reversal of the melting process, with the solid phase equilibrium occurred at a lower temperature due to the difficulty of ß-Sn nucleation. Amount of heat energy released during solidification differs less than 10% for SAC405 and less than 1% for SAC105 with the latent heat of fusion during the melting process

Thermo-Mechanical And Adhesion Performance Of Silver-Filled Conductive Polymer Composite (SFCP) Using Thermoplastic Polyurethane (TPU) Substrate

Emerging of conductive metal filler in nanoscale like Silver-Filled Conductive Polymer Composite (SFCP) ink is one of the important technology for electronic interconnects future. Among the key challenges in the successful development of such materials are to offer high electrical conductivity and good adhesion in polymer-based substrates without compromising on the mechanical reliability of such devices. This paper discussed the characteristics of Thermoplastic Polyurethane (TPU) based-materials in terms of their sustainability, wettability and SFCP conductivity of thermal effect (room temperature –25°C), 40°C, 60°C and 80°C). The experimental work involved electrical conductivity measurement using a Four-Point Probe, contact angle measurement and surface roughness analysis. Surface morphology analysis was carried out by using Axioscope 2MAT Optical Microscope and Scanning Electron Microscopic (SEM). The results show that sheet resistance of SFCP increased with an increasing strain and decrease with the increasing of temperature. The above results were observed due to the crack formation against strain but the presents of temperature cause the silver (Ag) particle to expand, filled the gap and form network path for electrical conduction even at maximum temperature and strain (80°C at 80%). Moreover, the TPU shows low wettability that exhibits poor adhesion between SFCP and TPU substrate due to reducing in the contact area between adhesive and substrate that cause the surface has low surface energy when exposed to variation of temperature

Hydrophobicity Performance Of Polyethylene Terephthalate (PET) And Thermoplastic Polyurethane (TPU) With Thermal Effect

Combining the flexibility and stretchability of printed flexible circuits (PFC) such as PET and TPU with water repellent characteristics may improve the functionality of printed circuit for electronic packaging. Water repellent characteristics using ceramic-based coating may protect the surface from degradation and moisture absorption due to the hydrophobicity behavior of the surface after coating. This paper seeks to provide insight into characterization and understanding on the effect of thermal on the hydrophobic performance of polymer substrate (PET and TPU) with and without coated with a ceramic coating which is Titanium Dioxide (TiO2) for more robust and vigorous hydrophobic coating. The annealing temperature was determined by using DSC analysis and four different temperatures have been used in this study. Contact angle and surface roughness characterization were evaluated by self-fabricate contact angle measurement tools and Mitutoyo Profilometer Surftest SJ410. The results reveal that hydrophobicity of uncoated TPU increase and PET decrease after thermally aged. However, after coated with TiO2, both substrate shows further increment in hydrophobicity with contact angle more than 90°. The 2D profile reveals that surface roughness protrusion becomes one of the factors affecting the hydrophobicity of the surface due to liquid-air interfaces under the droplet (air trap) as stated in Wenzel and Cassie-Baxter theory

Numerical Simulation Of Self-Alignment Of Chip Resistor Components For Different Silver Content During Reflow Soldering

Three-dimensional simulation and experimental investigation of self-alignment phenomena during the reflow soldering process were presented. The multiphase flow model was developed using ANSYS Fluent to investigate the self-alignment effect of laminar melted lead-free solder during the reflow phase on board. User-defined function with c-code was integrated into the model, Volume of Fluid (VOF) method was applied to the melt front tracking, and solidification model was used for the phase change solder material. The material used in the study was SAC 105, SAC 305 and SAC 405. The specific heat, latent heat, solidus temperature, liquidus temperature of the lead-free solder and geometrical data for model input was determined experimentally. The model was validated experimentally. The self-alignment capability of different lead-free solder was presented. It has been observed that higher silver content solder (SAC 405) have higher self-alignment capability during reflow soldering compare to SAC 305 and SAC 105. Moreover, all cases show self-alignment in perpendicular to the longer sides of chip resistor travelled more towards the central position. The experimental and simulation results are in good conformity and can be extended for different cases

Effect of Sn plating thickness on wettability, solderability, and electrical connections of electronic lead connectors for surface mount technology applications

The wettability of solder is important to achieve good solderability between the electronic component and printed circuit board (PCB). Tin (Sn) plating is widely used to promote the wettability of the solder on the substrates. However, an adequate amount of Sn plating thickness must be taken into consideration to acquire good wettability and solderability. Thus, this study investigates the Sn plating thickness of the electronic lead connector and their effect on the wettability and electrical connection. Two types of Sn plating thicknesses, ~3 μm, and 5 μm were applied on the electronic lead connector surface. It was found that the thin Sn plating thickness of ~3 μm has shown failure in electrical connections and lack of solder joint wettability and solderability properties. A thicker Sn plating thickness of 5 μm, has shown better wettability and solderability properties. In addition, the electrical connections also passed which implies that the thicker Sn plating thickness provides good solder joint establishment leading to good electrical connections. It is also observed that the better wettability of solder has been achieved for thicker Sn plating thickness. The finding from the field emission scanning electron microscope (FESEM) shows that the intermetallic compound (IMC) layer growth in the lead connector surface is regarded as abnormal for thin Sn plating thickness (~3 μm), in which the IMC layer was consumed and penetrating up to the surface of Sn-coating. This has led to poor solderability of the thin Sn plating with the solder to establish solder joint. The findings from this study have shed some light upon a better understanding of the importance of considering the adequate amount of Sn coating thickness to avoid IMC consumption at the Sn plating, better wettability properties, solderability, and solder joint quality for surface mount technology (SMT) especially for electronic lead connector applications