Effect of flux functional group for solder paste formulation towards soldering quality of SAC305/CNT/Cu

2020 ◽  
Vol 32 (3) ◽  
pp. 157-164
Author(s):  
Norliza Ismail ◽  
Azman Jalar ◽  
Maria Abu Bakar ◽  
Roslina Ismail ◽  
Najib Saedi Ibrahim
Keyword(s):  
Contact Angle ◽  
Solder Joint ◽  
Layer Thickness ◽  
Functional Groups ◽  
Functional Group ◽  
Solder Paste ◽  
Layer Formation ◽  
Content Type ◽  
Solder Pastes

Purpose The purpose of this paper is to investigate the wettability and intermetallic (IMC) layer formation of Sn-3.0Ag-0.5Cu (SAC305)/CNT/Cu solder joint according to the formulation of solder paste because of different types of fluxes. Design/methodology/approach Solder pastes were prepared by mixing SAC305 solder powder with different flux and different wt.% of carbon nanotube (CNT). Fourier transform infrared spectroscopy was used to identify functional groups from different fluxes of as-formulated solder paste. The solder pastes were then subjected to stencil printing and reflow process. Solderability was investigated via contact angle analysis and the thickness of cross-sectionally intermetallic layer. Findings It was found that different functional groups from different fluxes showed different physical behaviour, indicated by contact angle value and IMC layer thickness. “Aromatic contain” functional group lowering the contact angle while non-aromatic contain functional group lowering the thickness of IMC layer. The higher the CNT wt.%, the lower the contact angle and IMC layer thickness, regardless of different fluxes. Relationship between contact angle and IMC layer thickness is found to have distinguished region because of different fluxes. Thus it may be used as guidance in flux selection for solder paste formulation. Research limitations/implications However, detail composition of the fluxes was not further explored for the scope of this paper. Originality/value The quality of solder joint of SAC305/CNT/Cu system, as indicated by contact angle and the thickness of IMC layer formation, depends on existence of functional group of the fluxes.

X-ray inspection and Six-Sigma in analysis of LED thermal pad coverage

2017 ◽  
Vol 29 (1) ◽  
pp. 28-33 ◽  
Author(s):  
Barbara Dziurdzia ◽  
Janusz Mikolajek
Keyword(s):  
Six Sigma ◽  
Vapour Phase ◽  
Inspection System ◽  
Solder Paste ◽  
Process Variables ◽  
Reflow Soldering ◽  
Content Type ◽  
X Ray ◽  
Solder Pastes ◽  
Free Solder

Purpose The purpose of this paper is to evaluate selected methods of reduction voidings in lead-free solder joints underneath thermal pads of light-emitting diodes (LEDs), using X-ray inspection and Six Sigma methodology. Design/methodology/approach On the basis of cause and effect diagram for solder voiding, the potential causes of voids and influence of process variables on void formation were found. Three process variables were chosen: the type of reflow soldering, vacuum incorporation and the type of solder paste. Samples of LEDs were mounted with convection and vapour phase reflow soldering. Vacuum was incorporated into vapour phase soldering. Two types of solder pastes OM338PT and LFS-216LT were used. Algorithm incorporated into X-ray inspection system enabled to calculate the statistical distribution of LED thermal pad coverage and to find the process capability index (Cpk) of applied soldering techniques. Findings The evaluation of selected soldering processes of LEDs in respect of their thermal pad coverage and statistical Cpk indices is presented. Vapour-phase soldering with vacuum is capable (Cpk > 1) for OM338PT and LFS-216LT paste. Convection reflow without vacuum with LFS-216LT paste is also capable (Cpk = 1.1). Other technological soldering processes require improvements. Vacuum improves radically the capability of a reflow soldering for an LED assembly. When vacuum is not accessible, some improvement of capability to a lower extent is possible by an application of void-free solder pastes. Originality/value Six Sigma statistical methodology combined with X-ray diagnosis was used to check whether applied methods of void reduction underneath LED thermal pads are capable processes.

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.

Effects of nano-copper particles on the properties of Sn58Bi composite solder pastes

2017 ◽  
Vol 34 (1) ◽  
pp. 40-44 ◽  
Author(s):  
Hao Zhang ◽  
Yang Liu ◽  
Fenglian Sun ◽  
Gaofang Ban ◽  
Jiajie Fan
Keyword(s):  
Formation Mechanism ◽  
Composite Solder ◽  
Defect Formation ◽  
Void Formation ◽  
Experimental Results ◽  
Solder Paste ◽  
Content Type ◽  
Weight Percentage ◽  
Copper Particles ◽  
Solder Pastes

Purpose This paper aimed to investigate the effects of nano-copper particles on the melting behaviors, wettability and defect formation mechanism of the Sn58Bi composite solder pastes. Design/methodology/approach In this paper, the mechanical stirring method was used to get the nano-composite solder pastes. Findings Experimental results indicated that the addition of 3 wt.% (weight percentage) 50 nm copper particles showed limited effects on the melting behaviors of the Sn58Bi composite solder paste. The spreading rate of the Sn58Bi composite solder paste showed a decreasing trend with the increase of the weight percentage of 50 nm copper particles from 0 to 3 wt.%. With the addition of copper particles of diameters 50 nm, 500 nm or 6.5 μm into the Sn58Bi solder paste, the porosities of the three types of solder pastes showed a similar trend. The porosity increased with the increase of the weight percentage of copper particles. Based on the experimental results, a model of the void formation mechanism was proposed. During reflow, the copper particles reacted with Sn in the matrix and formed intermetallic compounds, which gathered around the voids produced by the volatilization of flux. The exclusion of the voids was suppressed and eventually led to the formation of defects. Originality/value This study provides an optimized material for the second and third level packaging. A model of the void formation mechanism was proposed.

SAC–xTiO2 nano-reinforced lead-free solder joint characterizations in ultra-fine package assembly

2018 ◽  
Vol 30 (1) ◽  
pp. 1-13 ◽  
Author(s):  
Fakhrozi Che Ani ◽  
Azman Jalar ◽  
Abdullah Aziz Saad ◽  
Chu Yee Khor ◽  
Roslina Ismail ◽  
...  
Keyword(s):  
Electron Microscope ◽  
Solder Joint ◽  
Solder Joints ◽  
Ion Beam ◽  
Lead Free ◽  
Lead Free Solder ◽  
Solder Paste ◽  
Content Type ◽  
X Ray ◽  
Free Solder

Purpose This paper aims to investigate the characteristics of ultra-fine lead-free solder joints reinforced with TiO2 nanoparticles in an electronic assembly. Design/methodology/approach This study focused on the microstructure and quality of solder joints. Various percentages of TiO2 nanoparticles were mixed with a lead-free Sn-3.5Ag-0.7Cu solder paste. This new form of nano-reinforced lead-free solder paste was used to assemble a miniature package consisting of an ultra-fine capacitor on a printed circuit board by means of a reflow soldering process. The microstructure and the fillet height were investigated using a focused ion beam, a high-resolution transmission electron microscope system equipped with an energy dispersive X-ray spectrometer (EDS), and a field emission scanning electron microscope coupled with an EDS and X-ray diffraction machine. Findings The experimental results revealed that the intermetallic compound with the lowest thickness was produced by the nano-reinforced solder with a TiO2 content of 0.05 Wt.%. Increasing the TiO2 content to 0.15 Wt.% led to an improvement in the fillet height. The characteristics of the solder joint fulfilled the reliability requirements of the IPC standards. Practical implications This study provides engineers with a profound understanding of the characteristics of ultra-fine nano-reinforced solder joint packages in the microelectronics industry. Originality/value The findings are expected to provide proper guidelines and references with regard to the manufacture of miniaturized electronic packages. This study also explored the effects of TiO2 on the microstructure and the fillet height of ultra-fine capacitors.

The behaviour of solder pastes in stencil printing with electropolishing process

2013 ◽  
Vol 25 (3) ◽  
pp. 164-174 ◽  
Author(s):  
Yong‐Won Lee ◽  
Keun‐Soo Kim ◽  
Katsuaki Suganuma
Keyword(s):  
Circuit Board ◽  
Surface Finishing ◽  
Design Parameters ◽  
Solder Paste ◽  
Stencil Printing ◽  
Printing Process ◽  
Content Type ◽  
Solder Paste Printing ◽  
Solder Mask

PurposeThe purpose of this paper is to study the effect of the electropolishing time of stencil manufacturing parameters and solder‐mask definition methods of PCB pad design parameters on the performance of solder paste stencil printing process for the assembly of 01005 chip components.Design/methodology/approachDuring the study, two types of stencils were manufactured for the evaluations: electroformed stencils and electropolished laser‐cut stencils. The electroformed stencils were manufactured using the standard electroforming process and their use in the paste printing process was compared against the use of an electropolished laser‐cut stencil. The electropolishing performance of the laser‐cut stencil was evaluated twice at the following intervals: 100 s and 200 s. The performance of the laser‐cut stencil was also evaluated without electropolishing. An optimized process was established after the polished stencil apertures of the laser‐cut stencil were inspected. The performance evaluations were made by visually inspecting the quality of the post‐surface finishing for the aperture wall and the quality of that post‐surface finishing was further checked using a scanning electron microscope. A test board was used in a series of designed experiments to evaluate the solder paste printing process.FindingsThe results demonstrated that the length of the electropolishing time had a significant effect on the small stencil's aperture quality and the solder paste's stencil printing performance. In this study, the most effective electropolishing time was 100 s for a stencil thickness of 0.08 mm. The deposited solder paste thickness was significantly better for the enhanced laser‐cut stencil with electropolishing compared to the conventional electroformed stencils. In this printing‐focused work, print paste thickness measurements were also found to vary across different solder‐mask definition methods of printed circuit board pad designs with no change in the size of the stencil aperture. The highest paste value transfer consistently occurred with solder‐mask‐defined pads, when an electropolished laser‐cut stencil was used.Originality/valueDue to important improvements in the quality of the electropolished laser‐cut stencil, and based on the results of this experiment, the electropolished laser‐cut stencil is strongly recommended for the solder paste printing of fine‐pitch and miniature components, especially in comparison to the typical laser‐cut stencil. The advantages of implementing a 01005 chip component mass production assembly process include excellent solder paste release, increased solder volume, good manufacture‐ability, fast turnaround time, and greater cost saving opportunities.

The Cause Analysis of Pseudo Solder in Surface Mounted Technology

2010 ◽  
Vol 146-147 ◽  
pp. 895-898
Author(s):  
Fu Pei Wu ◽  
Sheng Ping Li
Keyword(s):  
Solder Joint ◽  
Technological Process ◽  
Solder Joints ◽  
Solder Paste ◽  
Cause Analysis ◽  
Solder Material ◽  
Five Factors ◽  
Degree Of Satisfaction ◽  
Solder Paste Printing

Pseudo solder is one kind of familiar solder joint defect, and it is very difficult to be detected in surface mounted technology. Reduce the pseudo solder is viewed as one of effectively way to keep the quality of solder joints. In this manuscript, the quality of component, solder paste printing process, mounting processing, reflowing process, solder material are analyzed to illustrate the cause of pseudo solder in surface mounted technology. Based on the five factors, a pseudo solder model is built for IC component. In the pseudo solder model, its parameters are used corresponding to the cause of pseudo solder, and their values are used to evaluate the degree of satisfaction based on the SMT technological process. Experiments results show that parameters of the pseudo solder model can illustrate the cause of pseudo solder effectively.

Methodology for Evaluating and Optimizing Infrared Interpretations

1986 ◽  
Vol 40 (3) ◽  
pp. 344-348 ◽  
Author(s):  
David D. Saperstein
Keyword(s):  
Functional Groups ◽  
Ir Spectrum ◽  
Functional Group ◽  
Spectral Information ◽  
Synthetic Spectrum ◽  
Spectral Difference ◽  
Expectation Value

With the use of spectral information, a means is reported for evaluating and optimizing infrared (IR) interpretations. A procedure is described for numerically estimating the spectral difference between the interpreted IR spectrum and a synthetic spectrum composed of the characteristic subspectra of the functional groups in the interpretation. The expectation value assigned to each functional group by an interpreter can then be modified to minimize the estimated numerical differences and improve the quality of the interpretation.

An investigation on energy consumption and part quality of stereolithography apparatus manufactured parts

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Jizhuang Hui ◽  
Zhiqiang Yan ◽  
Jingxiang Lv ◽  
Yongsheng Liu ◽  
Kai Ding ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Energy Consumption ◽  
Layer Thickness ◽  
Laser Power ◽  
Dimensional Accuracy ◽  
Electrical Energy ◽  
Design Stage ◽  
Content Type ◽  
Part Quality

Purpose This paper aims to investigate the influences of process parameters on part quality, electrical energy consumption. Moreover, the relationship between part quality and energy consumption of UTR9000 photosensitive resin fabricated by stereolithography apparatus (SLA) was also assessed. Design/methodology/approach Main effect plots and contour maps were used to analyze the interactions and effects of various parameters on energy consumption and part quality, respectively. Then, a growth rate was used defined as the percentage of the value of energy consumption (or the part quality) of the sample compared to the minimum value of the energy consumption (or the same part quality), to jointly analyze relationships between part quality and energy consumption on a specific process parameter. Findings The part qualities can be improved with increased energy consumption via adjusting layer thickness, without further increasing energy consumption through adjusting laser power, over-cure and scanning distance. Energy consumption can be highly saved while slightly decreasing the tensile strength by increasing layer thickness from 0.09 mm to 0.12 mm. Energy consumption and surface roughness can be decreased when setting laser power near 290 mW. Setting an appropriate over-cure of about 0.23 mm will improve tensile strength and dimensional accuracy with a little bit more energy consumption. The tensile strength increases nearby 5% at a scanning distance of 0.07 mm compared to that at a scanning distance of 0.1 mm while the energy consumption only increases by 1%. Originality/value In this research, energy consumption and multiple part quality for SLA are jointly analyzed first to accelerate the development of sustainable additive manufacturing. This can be used to assist designers to achieve energy-effective fabrication in the process design stage.

On improving the surface finish of 3D printing polylactic acid parts by corundum blasting

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Ana Pilar Valerga Puerta ◽  
J.D. Lopez-Castro ◽  
Adrián Ojeda López ◽  
Severo Raúl Fernández Vidal
Keyword(s):  
Layer Thickness ◽  
Polylactic Acid ◽  
Surface Quality ◽  
Fused Deposition Modeling ◽  
Fused Filament Fabrication ◽  
High Exposure ◽  
Content Type ◽  
Fused Deposition ◽  
Deposition Modeling

Purpose Fused filament fabrication or fused deposition modeling (FFF/FDM) has as one of its main restrictions the surface quality intrinsic to the process, especially linked to the layer thickness used during manufacture. The purpose of this paper is to study the possibility of improving the surface quality of polylactic acid (PLA) parts manufactured by FFF using the shot blasting technique. Design/methodology/approach The influence of corundum blasting on 0.2 mm layer thickness FDM PLA parts treated with two sizes of abrasive, different exposure times and different incidence pressures. Findings As a result, improvements of almost 80% were obtained in the surface roughness of the pieces with high exposure times, and more than 50% in just 20 s. Originality/value This technique is cheap, versatile and adaptable to different part sizes and geometries. Furthermore, it is a fast and environmentally friendly technique compared to conventional machining or vapor smoothing. Despite this, no previous studies have been carried out to improve the quality of this technology.

Residual free solder process for fluxless solder pastes

2018 ◽  
Vol 30 (2) ◽  
pp. 118-128 ◽  
Author(s):  
Alexander Hanss ◽  
Gordon Elger
Keyword(s):  
Formic Acid ◽  
Market Potential ◽  
Solder Paste ◽  
Solder Alloys ◽  
Content Type ◽  
Soldering Process ◽  
Fluxless Soldering ◽  
Solder Pastes ◽  
Free Solder ◽  
Metal Formates

Purpose For soldering, flux is essential because it enables the wetting of the molten solder. Fluxless soldering, i.e. residue-free soldering with the aid of gaseous activators, has been known for many years, but is only well established in the field of opto- and microwave electronics where the solder is applied as preform. In high-volume SMD applications where solder paste is printed, this technology is rarely used until now. The reducing effect of a gaseous activator like formic acid vapor on certain solder alloys is known in practice. However, the corresponding reactions which occur under soldering conditions in nitrogen atmosphere have so far not been systematically investigated for different solder alloys. This study aims to analyze the different chemical reaction channels which occur on the surface of different solders, i.e. catalytical dissociation of formic acid on the pure or oxidized metal surface and the formation and evaporation of metal formates. Based on this analysis, a residue-free solder process under formic acid is developed for solder paste applications. Design/methodology/approach In this paper, different solder alloys (SnAgCu, SnPb, BiSn, In) were analyzed with thermal gravimetric analysis (TGA) under formic acid flow. Details on mass change depending on the soldering temperature are presented. Activation temperatures are estimated and correlated to the soldering processes. Based on the analysis, fluxless solder pastes and suitable soldering processes are developed and presented. Major paste properties such as printability are compared to a commercial flux solder paste. High-power flip chip LEDs which can be assembled directly on a printed circuit board are used to demonstrate the fluxless soldering. Likewise, the soldering results of standard paste and fluxless paste systems after a reflow process are evaluated and compared. Findings The experimental results show that TGA is an efficient way to gain deeper understanding of the redox processes which occur under formic acid activation, i.e. the formation of metal formates and their evaporation and dissociation. It is possible to solder residue-free not only with preforms but also with a fluxless solder paste. The resulting solder joints have the same quality as those for standard solder paste in terms of voids detected by X-ray and mechanical shear strength. Originality/value In the fluxless soldering process, the reduction of oxide layers, and therefore the wetting of the solder spheres, is enabled by gaseous formic acid. After the soldering process, no cleaning process is necessary because no corrosive residues are left on the circuit boards and components. Therefore, soldering using solder paste without aggressive chemical ingredients has a high market potential. Expensive preforms could be replaced by paste dispensing or paste printing.

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