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The effect of Ga addition on the microstructure, mechanical properties and weldability of Sn-0.3Ag-0.7Cu (SAC0307) lead-free solder was investigated in this research. It shows that Ga addition has positive impact on refining the microstructure and improving wettability of SAC0307. When Ga addition in SAC0307 accounts for 0.6 wt%, the solder has smaller grain size, more uniform distribution of intermetallic...
In this paper a micro-nano Cu@Ag core-shell particles were synthesized by liquid phase reduction method based on 50nm, 5µm, 20µm spherical copper powders for enhancement of Sn-10Sb high temperature solder. The as-prepared Cu@Ag core-shell particles were characterized by XRD, TEM and SEM methods, result indicated that a layer of Ag was uniformly coated on the surface of Cu. 3wt.% Cu@Ag core-shell particles...
Defect of SAC305 large-size BGA components attached with SnPb solder was analyzed by metallographic examination, and the faulty welded joint was found at the center position of the component. In order to explain the failure mode, reflow process simulation on assembled PCB board was carried out by ANSYS, and the temperature distribution was deeply studied. It is shown that there a obvious difference...
The heat generated by self-propagating exothermic reaction can be used to melt solder and then join the components. However, the microstructure of self-propagating interconnects is different from those obtained through traditional soldering process for its unique thermal conditions. In this paper, a finite element model was established to simulate the temperature field of self-propagating joints at...
In the current study, the effects of deep cryogenic treatment (DCT) on the microstructure and mechanical properties of Sn-3.0Ag-0.5Cu (SAC30) solder joints were investigated. the mechanism of microstructure, tensile strength and fracture path were discussed. The samples were placed in liquid nitrogen environment at 77 K for 24, 72, 168, and 600 hours. The experimental results show that the strength...
High pressure air blowing liquid solder and synchrotron radiation x-ray real-time imaging technology were used to study the interface reactions of Sn-XAg/Cu (X=0, 1, 3) joints during reflow with various soldering time under temperature of 250/275/300°C. This experiment allows us in-situ observe the interfacial IMCs growth and completely avoids Cu6Sn5 precipitation from the solder in cooling stage...
Sn-3.0Ag-0.5Cu lead-free solder, PCB copper clad laminate and copper thin film substrate were used as experimental materials and the Cu/SAC305/Cu interconnection plate-level structure micro-solder joint was prepared by pulsed hot-pressing welding test. The author aimed at investigating the pulse welding time, pulse welding temperature and welding pressure which influence on the microstructure of solder...
In this study, titanium (Ti) added Sn58Bi solder alloys were synthesized. Microstructure evolution and mechanical property change during 1008 h thermal aging were compared with those of eutectic Sn58Bi and Ti-added Sn58Bi alloys. According to the results, yield strength (YS) and ultimate tensile strength (UTS) decreased, while even after aging, the Ti-added Sn58Bi alloy maintained the highest YS and...
In this paper, the Bi-11Ag solders with additions of 1wt.%, 3wt.%, and 5wt.% Sn are prepared to investigate the microstructure, melting characteristic, and tensile strength of the solder joint. The result shows that the melting temperature decreases to 154 °C as the Sn continuously added; the microstructure was refined when the addition of Sn was below 5wt.%, as it reach 5wt.% or more, the dendritic...
The objective of this paper is to investigate the effect of rapid thermal cycling on microstructure and optical property (luminous flux and luminous efficiency) of high power light emitting diode (LED) by thermal fatigue testing from −40 to 125. Under an application of thermal fatigue device as a heating source, the specimens that were being non-operating and thermal fatigue testing in the experiment...
The in-situ TiC ceramic particle-reinforced TiCrFeCoNiCu multi-principal-element alloys matrix composites were first successfully prepared by “pre-self-propagating and casting” process and mechanical properties and microstructure of the material were analyzed. The results show that in the CrFeCoNiCuTi-10%vol.TiC composite, the spherical particles of TiC are distributed uniformly in matrix of multi-principal-element...
A structure of Cu/IMCs/Ni micro-joint has been prepared from Cu/Sn (1.5µm)/Ni sandwich layers through the transient liquid phase soldering at 240 °C and 290 °C. On the result of microstructural observation, two layers can be distinguished as the thick (Cu, Ni)6Sn5 layer beneath the upper layer of thin (Cu, Ni)3Sn layer, to constitute the IMCs interlayer in micro-joint formed at 240 °C with dwell time...
Ultrasound-assisted soldering of Cu/Cu was conducted with a self-developed Ni-Sn composite solder. The microstructure and mechanical properties of Cu/Ni-Sn/Cu joints were investigated in terms of ultrasonic vibration time. Results indicated that, in the joint ultrasonically soldered for 5 s, (Ni,Cu)3Sn4 was formed along the Ni metal foam and got contact with each other in local area while (Cu,Ni)6...
BGA micro-joint with double substrates used by SAC305 lead-free solder is fabricated by reflowing process based on substrate FR-4. The microstructures of the solder joints are studied through the method of rapid thermal cycling (RPC). The double-based plate Cu/SAC305/Cu solder joint was tested at extreme temperature 60–180 °C by rapid thermal cycling 48 hours and 72 hours respectively, it was found...
Thermal cycling is typical working environment of electronic chips due to electronic equipment power on-offs and thermal excursions. Accelerated thermal cycling is widely employed to strictly examine the electronic products for aerospace usage to simulate the actual thermal environment throughout the service life. In this study, the effect of thermal cycling to mechanical property of Sn-3.0Ag-0.5Cu...
The requirements for lead-free electronics lead to the development of new Pb-free solders. The Sn-3.0-Ag-0.5Cu (SAC305) is one of them and is widely used in the lead-free solder market. But the melting point of it, 217°C, exceeds that of traditional Sn-37Pb solder. The lower melting temperature of lead-free solder are needed to meet the requirements of the manufacturing process that depend on conventional...
Incorporating reinforcements into solder is an effective way to inhibit the growth of interfacial IMCs layer and also improve the mechanical properties of solder joints. In this study, some composite solders were prepared by adding of four types of reinforcements into SAC305 solder matrix respectively, including SiC nanowires, SiC, ZnO and Ni nanoparticles through the methods of mechanical ball milling...
In this paper, the growth behavior of Cu6Sn5 intermetallic compound in Cu/Sn/Cu interconnection system during the ultrasonic-assisted transient liquid phase soldering were investigated under various ultrasonic bonding time. Asymmetrical growth of the interfacial Cu6Sn5 was observed in the Cu/Sn/Cu solder joints, i.e., the Cu6Sn5 near the side of cavitation erosion grew randomly, while the Cu6Sn5 near...
A nano-Cu pressureless sinterable paste was developed for joint formation applications. The material was further engineered in both chemistry and process for enhanced oxidation resistance. This oxidation resistance capability allowed the paste exhibited a shelf life of 6 months when stored at −10°C. The paste was insensitive to either sintering atmosphere or surface finish type, and consistently exhibited...
Synchrotron radiation x-ray real-time imaging technology was used to study the interface reactions of Sn/Cu and Sn0.7Cu/Cu joints during reflow with soldering time of 1h under temperature of 300/350 °C. This experiment allows us in-situ observe the interfacial IMCs growth and completely avoids Cu6Sn5 precipitation from the solder in cooling stage to affect the morphology and thickness of interfacial...
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