Soldering Parameters Research Articles

Impact of hot air gun soldering process parameters on the electromechanical properties of electronic yarn

Researchers now confirm that the market for electronic textiles, or ‘E-textiles,’ will rise rapidly. One method of creating e-textiles is the integration of electronics with textiles. Several techniques were used to combine electronics with conductive textile. One of the best methods for connecting electronics to conductive textile fabrics is soldering. Because of this, it is important to look into how the soldering process parameter affects the developed e-textile’s characteristics. In the research paper presented, the effects of temperature, speed of hot air, and amount of paste size of hot air gun re-flow soldering parameters on the electromechanical properties of surface mount device (SMD) embedded electronic yarn were examined. Three main soldering parameters at four different levels were selected based on the preliminary test results involving the soldering of the tiny SMD into CLEVERTEX electrically conductive hybrid yarn. The result shows that soldering of SMD into CLEVERTEX electrically conductive hybrid yarn provided a higher conductivity with 10-ohm DC resistance. Statistical analyses were also carried out to prove the significant effect of the temperature on changing electrical resistance at, α = 0.5, with an F-value of 0.27 and a p value of .036. While the effects of different amounts of solder paste size on the electrical resistance were not statistically significant at α = 0.5, with an F-value of 0.27 and a p value of .84. Moreover, the tensile strength of the developed e-yarn was affected by the hot air soldering parameters. Furthermore, the developments of e-yarn using hot air gun soldering was pronounced in more extreme process conditions, which revealed that there was a strong interaction between the solder temperature, solder paste volume and solder speed. Furthermore, this approach made it easier to generate the optimum quality of e-yarn needed to continue creating prototype electronic textiles.

Low temperature soldering technology based on superhydrophobic copper microlayer

Cu–Cu soldering is realized under certain pressure and low temperature conditions by using a surface silver film to modify the copper microlayer structure, thus solving the problems of high thermal stress and signal delay aggravation caused by high temperature in the traditional reflow soldering process. The copper microlayer modified with silver film is obtained by electrodeposition. The surface substructure of the Cu microlayer is a nano cone-shaped protrusion. The diameter of the bottom of the cone is 500 nm∼1 μm, and the height of the cone is 1∼2 μm. The thickness of the silver film is about 320 nm, and the modification of the copper layer with silver film can effectively prevent the oxidation of the copper layer. Two silver-modified copper microlayers are placed in face-to-face contact as a soldering couple. A certain pressure and low temperature are applied to the contact area to realize the soldering and interconnection.The morphology of the soldered interface and the average shear strength of the soldered joints are analyzed by scanning electron microscopy, transmission electron microscopy and solder joint tester. It is found that under the optimal soldering parameters of soldering temperature 220 °C, soldering pressure 20 MPa and soldering time 20 min, the nano-conical projections of the Cu micrometer layer are inserted into each other to produce a physical blocking effect. The highly surface-meltable silver film effectively connects the surrounding copper layer as an intermediate buffer layer. The average shear strength of soldering joints is significantly increased. Heat treatment experiments have shown that the average shear strength can be effectively increased by heat treatment for an appropriate period of time. Prolonged exposure to heat has little effect on the average shear strength. With the special morphology of the copper microlayer structure and the nano-size effect of the silver layer, soldering can be done at low temperatures. The quality of the soldering interface is good and small soldering dimensions can be obtained.

Comparing the Solderability of Different SA C0307 Composite Solder Pastes

In the present study, the effect of four oxide ceramics (TiO2, ZnO, ZrO2, and CuO) as reinforcements were investigated on the soldering parameters of the SAC 0307 solder alloy. The oxide ceramics were used in nano-powder format. Composite solder pastes were composed by the standard ball milling process of the nano-particles into the SAC 0307 solder paste in 0.25wt% weight fraction. The wettability, shear strength, and microstructure of the composite solder joints were studied and compared. The ceramic nano-particles did not have a major effect on the wettability of the solder. Shear strength increases were observed at the composite joints, except in the case of ZnO. Generally, Sn grain refinement was found in the Sn-matrix which could be the reason for the shear strength increase.

Effect of Microwave Hybrid Heating on Mechanical Properties and Microstructure of Sn3.0Ag0.5Cu/Cu Solder Joints

Microwave hybrid heating (MHH) has become soldering’s alternative method for lead-free solder alloys due to its benefits towards modern microtechnology, such as shorter processing time, lower energy consumption and lower defect rate. Nonetheless, it still requires susceptors to improve its heating performance, such as SiC, which is known for its high loss factor under low microwave frequencies. In this study, the effect of microwave hybrid heating on mechanical properties, as well as the microstructure of solder joint between Sn3.0Ag0.5Cu (SAC305) solder alloy and Cu substrate was investigated. Solder joint was created using MHH with different soldering parameters (amount of SiC in a range of 3-7g and exposure time in a range of 7-10min) between SAC305 solder alloy (in the form of wire and paste) and Cu substrate. Then, a lap shear test was carried out following a standard of ASTM D1002 to determine solder joint strength. Characterization was made using an optical microscope and scanning electron microscopy. Results showed that solder wire produced the highest solder joint strength with the value of 115.45 MPa when using 3.05g of SiC for 8.92min soldering time. Meanwhile, the solder paste produced 109.76MPa solder joint strength when using 3.03 g of SiC for 9.39 min soldering time. The intermetallic compound (IMC) form was scallop-like Cu6Sn5, both solder/substrate joints with a thickness of 2.87 μm for solder wire and 3.62 μm for solder paste. Nonetheless, an excessive amount of SiC would generate more heat in MHH and increase the IMC thickness as well as reduce shear strength, which eventually decreases the solder joint stability.

Effect of Different Solder Volumes on the Laser Soldering Process: Numerical and Experimental Investigation

Abstract Laser soldering is becoming more popular for soldering pin through-hole (PTH) components onto printed circuit boards (PCBs). Solder volume influences soldering joint reliability. However, it is difficult to accurately measure the effect of solder volume during the laser soldering process. The finite volume method (FVM) is used to simulate the molten solder flow in laser soldering to connect the through-hole capacitor onto the PCB in ansysfluent software. The simulation results reveal the effects of different SAC305 solder volumes on joining quality in terms of fillet shape formation, pressure, and velocity. The preferred solder volume is 1.517 mm3 with a filling time of 1.7 s, a temperature of 642 K, a hole diameter of 1.0 mm, a lead diameter of 0.5 mm and a PCB thickness of 1.20 mm, produces a fillet shape similar to a real sample of PTH laser soldering joint from the industry. This ideal volume was chosen with a suitable pressure and velocity to create a nice concave fillet shape and minimize voids during soldering. The pressure and velocity increase when the solder volume increases causing solidified solder to melt. The discrepancy between numerical and experimental values of fillet height is comparable, which inferred that the numerical model was well-validated. The good consistency between both results proves that the finite volume model will effectively predict the optimum solder volume. This opens up new opportunities for the optimization of the laser soldering parameters in the application of electronic manufacturing.

Experimental identification and prioritization of design and process parameters on hole fill in mini wave soldering

Mini wave soldering is a common method for soldering through-hole components on printed circuit boards (PCB). With PCB design becoming increasingly complex and copper layer thickness rising, the vertical hole fill of through-hole solder joints becomes a serious problem during manufacturing. At the same time, the process window is limited by limited material heat resistance of the PCB and the through-hole components. Especially critical is latent damage inside the PCB and the through-hole component which must not exceed its specific maximum core temperature because this would compromise reliability over lifetime. The choice of soldering parameters is critical to reaching sufficient vertical fill to achieve a reliable connection according to IPC-A-610. The dedicated description of the interaction between PCB design and vertical fill has the potential to considerably improve the understanding of the basics of design for manufacturing (DfM). In this paper, the essential process parameters of the selective wave soldering process are examined by design of experiment (DoE) with respect to hole fill, which determines mechanical and thermal reliability as well as current carrying capacity. The results show the individual effects of the copper layer design parameters including layer count, layer thickness, hole copper plating attachment and solder alloy on vertical hole fill, in combination with the solder process parameters. The copper layer design parameters, solder bath temperature and preheating temperatures show the strongest effects. The soldering time has the lowest impact within the tested process parameters. For a given solder joint with its defined heat capacity, the benefit of solder time diminishes the longer the contact time is. Component surfaces and connector pin material and machine parameters like pump power as well as environmental conditions show little to no impact within a reasonable operation window.

Numerical and experimental study on laser soldering process of SnAgCu lead-free solder

Laser soldering has been widely used in the connection of the electronic components and printed circuit boards. Normally, the temperature and thermal stress of solder joints significantly influence the soldering performance and the reliability of solder joints. However, it is difficult to be accurately measured by the experiment during laser soldering process. In order to reveal the effect of laser process parameters on the temperature and thermal stress of SnAgCu solder joints, a novel 3D transient thermo-mechanical coupling numerical model is proposed using finite element method. The numerical simulation results reveal that the temperature and the thermal stress as well as the deformation of the as-soldered samples are proportional to laser output power and output time. These results demonstrate that the fine and uniform microstructure is obtained for SnAgCu solder and the micro Vickers hardness reaches to the maximum value of 38.3 N at the condition of laser output power of 16 W and laser output time of 0.8 s. The good consistency between the experimental and simulation results proves that the finite element model may effectively predict the temperature distribution and stress distribution, which provides a new pathway for the optimization of the laser soldering parameters in the application of electronic components and PCB.

Effects of the Solder Phase Transformation on the Optimization of Reflow Soldering Parameters and Temperature Profiles

In this study, a heat convection model of the reflow oven and a heat conduction model of the soldering area are proposed based on heat transfer theory, and a dynamic Thomas algorithm is developed for solving linear equations with coefficient matrix evolving over time in the tridiagonal system, which is derived from a heat transfer problem with moving boundaries in the solder phase transition process. We have also carried out numerical simulations for investigating the accuracy of the mathematical model, in which the temperature profiles are calculated and compared for different cases with considering or ignoring phase transformations, respectively. Parameters of reflow soldering, such as the conveyor speed, the set temperature in each zone, and a part of the heating factor, are optimized by the use of the nondominated sorting genetic algorithm II. By comparing the temperature profile and optimal solutions in the two cases, numerical results show that phase transitions of the solder have great impacts on optimal parameters and the slope of temperature profiles. Moreover, the phenomenon that the heating factor varies with the maximum set temperature in a banded distribution is investigated and analyzed, which is an important part of this work.

Sn and Bi whisker growth from SAC0307-Mn07 and SAC0307-Bi1-Mn07 ultra-thin film layers

In the past years, the use of low silver content SAC0307 (99Sn0.3Ag0.7Cu wt%) solder alloy grew considerably due to its good soldering quality. In the latest version of this alloy, manganese, and bismuth are used to improve further its soldering parameters. In this study, a reliability issue, the whisker growth from SAC0307-Mn07 and SAC0307-Bi1-Mn07 solder alloys was investigated. Ultra-thin films (in 100–150 nm thickness) were vacuum evaporated from the investigated alloys onto Cu substrates. The samples were stored at laboratory conditions for 28 days. Whisker growth was followed by a scanning electron microscope, and the ultra-thin film layers structures were investigated in focused ion beam cuts. In the case of the SAC0307-Mn07, the mechanical stress due to the intermetallic layer growth resulted in whisker formation right after the layer deposition. However, Bi addition could increase the stress relaxation ability of the ultra-thin film layer; the whisker formation started only three days after the evaporation in the case of the SAC0307-Bi1-Mn07 layer. Besides, the SAC0307-Bi1-Mn07 alloy could entirely suppress the formation of filament-type whiskers that might cause reliability issues in microelectronics. Furthermore, a unique phenomenon was observed that the SAC0307-Bi1-Mn07 layer produced mostly Bi–Sn whisker couples.

Ultrasonic-assisted soldering of aluminium and copper with Sn–Zn–Bi–Ag solder

The effects of ultrasonic-assisted soldering parameters on the interfacial microstructural evolution and shear strength of designed Al/Sn–9.77Zn–11.36Bi–1.46Ag/Cu solder joints were investigated. The ultrasonic-assisted soldering process promoted the dissolution of Al substrate and roughed Al/solder interface, which improved the pinning effect of Sn–9.77Zn–11.36Bi–1.46Ag on Al substrate. With an increasing ultrasonic soldering temperature, time and power, more Al atoms dissolved from Al substrate and migrated across solder to the opposite Cu substrate to form Al-rich (Zn) solid solutions. Consequently, Al4.2Cu3.2Zn0.7 formed between ϵ-AgZn3 and Cu5Zn8 layers at Cu substrate, resulting in thinner Cu5Zn8 and higher shear strength of solder joints. The highest shear strength of solder joints (38.6 MPa) was achieved after ultrasonic-assisted soldering at 300°C for 10 s under 9 W.

Automatic Joining of Electrical Components to Smart Textiles by Ultrasonic Soldering.

A suitable connection method to automatically produce E-textiles does not exist. Ultrasonic soldering could be a good solution for that since it works with flux-free solder, which avoids embrittlement of the textile integrated wires. This article describes the detailed process of robot-assisted ultrasonic soldering of e-textiles to printed circuit boards (PCB). The aim is to understand the influencing factors affecting the connection and to determine the corresponding solder parameters. Various test methods are used to evaluate the samples, such as direct optical observation of the microstructure, a peeling tensile test, and a contact resistance measurement. The contact strength increases by reducing the operating temperature and the ultrasonic time. The lower operating temperature and the reduced ultrasonic time cause a more homogeneous metal structure with less defects improving the mechanical strength of the samples.

Modeling and Simulation of Multi-Material Soldering Performance for Spacecraft

In recent years, there have been several on-orbit failure cases of spacecraft thermistor circuit. Through the analysis of failure mode, it is confirmed that the failures are mostly caused by the failure of wire solder joint. In this paper, the finite element method (FEM) is used to simulate the effects of different soldering parameters on the stress-strain characteristics of spacecraft solder joints in cold-hot alternating environment.

On-Chip Diffusion Bonding creates Stable Interconnections Usable at Temperatures over 300°C

Abstract In this paper, we present a conceptual design of an on-chip solder stack to connect silicon devices faster and more reliable. Almost all electronic devices rely on solder layers to provide electrical, mechanical, and thermal connections between components. We improve the solder connection with industry-standard solder parameters of 300°C and some minutes of soldering time. An ideal solder connection is composed of intermetallic phases (IMPs) at the interfaces between device and solder, and substrate and solder. Typically, a thin region of Sn-based solder remains between the two IMP layers at the interfaces. IMPs of copper (Cu) and tin (Sn) are Cu6Sn5 and Cu3Sn. The formation of IMPs is decisive for a good mechanical connection because of their high melting point and mechanical stability. To achieve these requirements, we implement the solder stack as a transient liquid phase bonding (TLPB) system. To realize durable interconnections, we use the diffusion of a high-melting first component in a second component, which is liquid at solder process temperature. Ongoing diffusion leads to the formation of IMPs with a melting point above process temperature, resulting in a solidification of the connection at constant temperature. By this isothermal solidification, the solder connection becomes more durable against mechanical and thermal load and is usable at temperatures exceeding 300°C.

Enhanced Electrical and Mechanical Performances of Soldered Joint Between Copper Stabilized REBCO Superconducting Tapes

We have developed a thermo-compression soldering appliance for joining rare-earth barium copper oxide (REBCO) tapes with excellent control of process temperature and pressure. With this tool, we have systematically investigated the effects of soldering parameters and solder materials on the electrical and mechanical performances of soldered joints between REBCO superconducting tapes with laminated copper stabilizers. Low resistivity of about 30 nΩ·cm 2 at 77 K in self-field and high adhesion strength of about 5 N have been reproducibly achieved for lap joints with optimized process using InSn48 solder. The critical axial tensile stress of the joints was above 300 N, whereas the critical diameter for double bending of the joints was smaller than 20 mm. Lowering the temperature from 77 to 20 K reduced the joint resistance by 22%. However, applied magnetic fields up to 5 T showed little effect on the joint resistance. Increasing the overlapping joint length by N times dropped the joint resistance by a factor of about N -1 . A 3-m-long lap joint of 5-mm-wide REBCO tapes showed a resistance as low as 0.3 nΩ at 77 K and self-field, which is the lowest resistance for soldered joint so far as we know.

Reflow soldering method with gradient energy band generated by optical system.

Laser reflow soldering is an important technology in electronic components processing. In this paper, we presented a simple but efficient method to achieve reflow soldering process with gradient energy band created by just two parallel mirrors. The detailed influence of the variety of optical parameters on the soldering process has been analyzed by using the finite element method. And the modulation of the optical parameters on reflow soldering parameters also has been demonstrated. In our experiment, one HR mirror and one-mirror with transmissivity of 10% have been used to create a gradient energy band with an incident laser power of 50W. In summary, both the simulations and the experiments show that the typical reflow soldering profile has been acquired by the optical system. The high quality joints on both the front and rear surface of the capacitor can be acquired by just one surface radiation of the optical system.

Analysis of Ball Soldering Parameters on the Properties of a BGA Packaged Semiconductor

Integrated circuits have several applications, including medicine and the aerospace industry, where reliability is essential. Packaging is an important step in the manufacturing of integrated circuits, and ball soldering is one of the most critical process, especially in assembling and interconnecting integrated circuits. The solder joint formed during the ball soldering process is intrinsically associated with the performance and the reliability of the electronic system. This study analyzed the influence of parameters or factors affecting the ball soldering process from the perspective of intermetallic compound formation and shear stress of the solder joint. The results indicate there is an interaction coupling between these two factors that cannot be seen when they are investigated individually, meaning that the individual effect of each factor differs from that of the combinations of factors. The results showed that the factor that most influenced shear stress and thickness of the intermetallic compound was peak temperature during ball soldering.

Optimization on laser soldering parameters onto lead-free solder joint

This paper presents the results of optimization on laser soldering parameters onto lead free solder joint. The objective of this study is to determine the laser power needed and scanning time required to produce a high quality of solder joint. Laser soldering was selected due to its rapid and controllable selective process as well as suitable for temperature sensitive assemblies, which is very desirable nowadays as compared to time consuming process such as casting. A fibre laser with 200W was used in this study to form a joining between lead free solder wire and copper board. However, a continuous laser power was ranged between 48 to 60W to create joining. Before that, flux was also applied prior to laser soldering for uniform heat distribution throughout the solder volume. Lead free solder wire with the size of 1.0mm diameter was formed into several shapes including straight line-shape with 20mm in length, and spiral-shape with 6mm diameter, in order to capture and disperse the heat evenly. Results showed that laser power ranged from 48W to 60W with 3.5 to 4.5s duration was found to be suitable for lead free solder wire with spiral-shape condition. Besides, the wetting angle was also in optimal when the laser power was increased The optimized fibre laser parameters obtained in this study will be used for future reference in performing a laser soldering between solder alloy copper board.

Multi-objective optimization on laser solder jet bonding process in head gimbal assembly using the response surface methodology

This paper aims to investigate the effect of laser solder jet bonding parameters to the solder joints in Head Gimbal Assembly. Laser solder jet bonding utilizes the fiber laser to melt solder ball in capillary. The molten solder is transferred to two bonding pads by nitrogen gas. The response surface methodology have been used to investigate the effects of laser energy, wait time, nitrogen gas pressure, and focal position on the shear strength of solder joints and the change of pitch static attitude (PSA). The response surface methodology is employed to establish the reliable mathematical relationships between the laser soldering parameters and desired responses. Then, multi-objective optimization is conducted to determine the optimal process parameters that can enhance the joint shear strength and minimize the change of PSA. The validation test confirms that the predicted value has good agreement with the actual value.

A numerical model for soldering process in silicon solar cells

Solar or Photovoltaic (PV) cells are utilized to convert solar energy into electricity through the photovoltaic effect. Although, Silicon solar cell is one of the most prevalent type of solar cells; manufacturing of this type of solar cells especially soldering copper electrodes to the silicon wafer is very challenging. If the soldering parameters are not selected properly, small cracks will be created in silicon layer, and finally, fracture of the solar cell will happen. The goal of the present study is to develop, for the first time, a finite element model to simulate the soldering process in the fabrication of silicon solar cell in which the soldering system is passing over the solar cell to connect the copper electrode to the silicon wafer. The temperature and thermomechanical stress distributions induced in different layers of the cell are extracted. The effects of several parameters such as soldering power, soldering speed, and the thickness of silicon wafer on the temperature and stress distributions are probed. The results show that the silicon layer is the most critical layer in a silicon solar cell during the soldering process which is susceptible to high thermomechanical stresses. It is shown that increasing the soldering system power and decreasing the soldering system speed lead to increase of thermomechanical stresses induced in the silicon wafer. In addition, using thicker silicon wafer can decrease the thermomechanical stresses generated in this layer.

Experimental and Numerical Analysis of Melting and Solidification of SnAgCu Joints

One of the most vulnerable components of electronic circuits is the solder joints. The most common technique of soldering used in electronics is the reflow soldering. During the soldering process, different issues may occur leading to the inception of some defects (tombstone effect, flux spattering, etc.). To avoid these defects, it is mandatory to follow the parameter values of the reflow process, especially temperature values. In this paper, the temperature distribution for three types of samples (two interconnected soldering pads–without solder, with solder on one pad, and with solder on both pads) during the reflow soldering process, calculated with Comsol Multiphysics software (heat transfer 3-D module) is presented. The calculated values are then compared to the ones obtained by experiments in order to verify the accuracy of the numerical model. To carry out the computations, the latent heat of melting/solidification and the variation with the temperature of the solder parameters were considered. The results show that there is a good correlation between the measured and calculated values, the differences (for all types of samples) being lower than ±3 °C.