Effects of Mn nanoparticle addition on wettability, microstructure and microhardness of low-Ag Sn-0.3Ag-0.7Cu-xMn(np) composite solders

2018 ◽  
Vol 30 (3) ◽  
pp. 153-163 ◽  
Author(s):  
Yu Tang ◽  
Shaoming Luo ◽  
Guoyuan Li ◽  
Zhou Yang ◽  
Chaojun Hou
Keyword(s):  
Solder Matrix ◽  
Solder Paste ◽  
Dispersion Strengthening ◽  
Content Type ◽  
X Ray ◽  
Spread Ratio ◽  
Classic Theory ◽  
Free Solder ◽  
Wetting Process ◽  
Average Size

Purpose The purpose of this paper is to investigate of the effects of Mn nanoparticle addition on the wettability, microstructure and microhardness of SAC0307-xMn(np) (SAC: Sn–Ag–Cu; x = 0, 0.02, 0.05, 0.1 and 0.3 Wt.%) composite solders. Design/methodology/approach The SAC0307-xMn(np) composite solders were prepared by mechanically mixing different weight percentages of Mn nanopowders into the SAC0307 solder paste with rosin flux. In this study, the wettability of the solders was studied using contact angle and spread ratio methods. Afterward, the microstructure of the solders was investigated using scanning electron microscopy, energy-dispersive X-ray spectroscopy and X-ray diffractometry. Moreover, the microhardness of the solders was studied. Findings The wetting process of SAC0307-xMn(np) composite solders was found to experience four stages. Adding a small amount of Mn nanoparticles (x = 0.05 Wt.%) could improve the wettability compared to Mn-free solder. Beyond this level, the wettability deteriorated. The addition of Mn nanoparticles significantly refined the size and spacing of Ag3Sn grains in the solder matrix. When 0.1 Wt.% Mn nanoparticles was added, both the average size of the Ag3Sn grains and the spacing between the Ag3Sn grains decreased significantly and approached minimum values. Beyond this amount, the size and spacing between Ag3Sn grains increased slightly but remained smaller than those in the Mn-free solder matrix. The refined Ag3Sn grains increased the microhardness of the Mn-containing composite solders by 6-25 per cent, in good agreement with the prediction of the classic theory of dispersion strengthening. Originality/value The paper demonstrates that Mn nanoparticle addition could improve the SAC0307-xMn(np) solder wettability and reduce the grain size and spacing between Ag3Sn grains. The enhancement of the solder microhardness shows good correlation with the microstructure.

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.

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.

Characterization of SAC – x NiO nano-reinforced lead-free solder joint in an ultra-fine package assembly

2019 ◽  
Vol 31 (2) ◽  
pp. 109-124 ◽  
Author(s):  
Fakhrozi Che Ani ◽  
Azman Jalar ◽  
Abdullah Aziz Saad ◽  
Chu Yee Khor ◽  
Mohamad Aizat Abas ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Solder Joint ◽  
Lead Free ◽  
Inspection System ◽  
Lead Free Solder ◽  
Solder Paste ◽  
Nio Nanoparticles ◽  
Content Type ◽  
X Ray ◽  
Free Solder

Purpose This study aims to investigate the NiO nano-reinforced solder joint characteristics of ultra-fine electronic package. Design/methodology/approach Lead-free Sn-Ag-Cu (SAC) solder paste was mixed with various percentages of NiO nanoparticles to prepare the new form of nano-reinforced solder paste. The solder paste was applied to assemble the ultra-fine capacitor using the reflow soldering process. A focussed ion beam, high resolution transmission electron microscopy system equipped with energy dispersive X-ray spectroscopy (EDS) was used in this study. In addition, X-ray inspection system, field emission scanning electron microscopy coupled with EDS, X-ray photoelectron spectroscopy (XPS) and nanoindenter were used to analyse the solder void, microstructure, hardness and fillet height of the solder joint. Findings The experimental results revealed that the highest fillet height was obtained with the content of 0.01 Wt.% of nano-reinforced NiO, which fulfilled the reliability requirements of the international IPC standard. However, the presence of the NiO in the lead-free solder paste only slightly influenced the changes of the intermetallic layer with the increment of weighted percentage. Moreover, the simulation method was applied to observe the distribution of NiO nanoparticles in the solder joint. Originality/value The findings are expected to provide a profound understanding of nano-reinforced solder joint’s characteristics of the ultra-fine package.

Low-voiding solder pastes in LED assembly

2020 ◽  
Vol 32 (4) ◽  
pp. 201-217
Author(s):  
Barbara Dziurdzia ◽  
Maciej Sobolewski ◽  
Janusz Mikołajek ◽  
Sebastian Wroński
Keyword(s):  
Solder Joints ◽  
Mean Value ◽  
Solder Paste ◽  
Production Environment ◽  
Content Type ◽  
X Ray ◽  
Electronic Manufacturing ◽  
Industry Practice ◽  
Solder Pastes ◽  
Free Solder

Purpose This paper aims to investigate voiding phenomena in solder joints under thermal pads of light-emitting diodes (LEDs) assembled in mass production environment by reflow soldering by using seven low-voiding lead-free solder pastes. Design/methodology/approach The solder pastes investigated are of SAC305 type, Innolot type or they are especially formulated by the manufacturers on the base of (SnAgCu) alloys with addition of some alloying elements such as Bi, In, Sb and Ti to provide low-void contents. The SnPb solder paste – OM5100 – was used as a benchmark. The solder paste coverage of LED solder pads was chosen as a measure of void contents in solder joints because of common usage of this parameter in industry practice. Findings It was found that the highest coverage and, related to it, the least void contents are in solder joints formed with the pastes LMPA-Q and REL61, which are characterized by the coverage of mean value 93.13% [standard deviation (SD) = 2.72%] and 92.93% (SD = 2.77%), respectively. The void diameters reach the mean value equal to 0.061 mm (SD = 0.044 mm) for LMPA-Q and 0.074 mm (SD = 0.052 mm) for REL61. The results are presented in the form of histograms, plot boxes and X-ray images. Some selected solder joints were observed with 3D computer tomography. Originality/value The statistical analyses are carried out on the basis of 2D X-ray images with using Origin software. They enable to compare features of various solder pastes recommended by manufacturers as low voiding. The results might be useful for solder paste manufacturers or electronic manufacturing services.

Quantitative Evaluation of Voids in Lead Free Solder Joints

2015 ◽  
Vol 772 ◽  
pp. 284-289 ◽  
Author(s):  
Sabuj Mallik ◽  
Jude Njoku ◽  
Gabriel Takyi
Keyword(s):  
Solder Bump ◽  
Solder Joints ◽  
Void Formation ◽  
Lead Free ◽  
Lead Free Solder ◽  
Solder Paste ◽  
X Ray ◽  
Size And Shape ◽  
Solder Bumps ◽  
Free Solder

Voiding in solder joints poses a serious reliability concern for electronic products. The aim of this research was to quantify the void formation in lead-free solder joints through X-ray inspections. Experiments were designed to investigate how void formation is affected by solder bump size and shape, differences in reflow time and temperature, and differences in solder paste formulation. Four different lead-free solder paste samples were used to produce solder bumps on a number of test boards, using surface mount reflow soldering process. Using an advanced X-ray inspection system void percentages were measured for three different size and shape solder bumps. Results indicate that the voiding in solder joint is strongly influenced by solder bump size and shape, with voids found to have increased when bump size decreased. A longer soaking period during reflow stage has negatively affectedsolder voids. Voiding was also accelerated with smaller solder particles in solder paste.

Influence of aging on microstructure and hardness of lead-free solder alloys

2020 ◽  
Vol 33 (1) ◽  
pp. 57-64
Author(s):  
Carina Morando ◽  
Osvaldo Fornaro
Keyword(s):  
Isothermal Aging ◽  
Treatment Time ◽  
Cast Alloy ◽  
Scanning Calorimetry ◽  
Content Type ◽  
X Ray ◽  
Different Temperatures ◽  
Free Solder ◽  
Cast Condition ◽  
Dsc Calorimetry

Purpose The purpose of this paper is to carry out a study of the evolution of the microstructure and the microhardness of Sn-Cu-Ag alloys from as-cast condition and under artificial isothermal aging at different temperatures (100ºC and 180ºC) for a treatment time up to 500 h. A comparison with Sn-37% Pb eutectic solder samples was also made. Design/methodology/approach Sn-3.5%Ag, Sn-0.7%Cu and Sn-3.5%Ag-0.9%Cu were poured in two different cooling rate conditions and then aged at 100ºC (373ºK) and 180 °C (453ºK) during 500 h. Microstructural changes were observed by optical microscopy, scanning electron micrograph and energy dispersive X-ray microanalysis. Differential scanning calorimetry technique (DSC) was also used to confirm the obtained results. Findings A decrease up to 20% in microhardness respect to the value of the as-cast alloy was observed for both aging temperatures. These changes can be explained considering the coarsening and recrystallization of Sn dendrites present in the microstructures of all the systems studied. Originality/value There is no evidence of dissolution or precipitation of new phases in the range of studied temperatures that could be detected by DSC calorimetry technique. The acting mechanisms must be the result of coarsening of Sn dendrites and the residual stresses relaxation during the first stages of the isothermal aging.

Wetting properties of Nd:YAG laser treated copper by SAC solders

2017 ◽  
Vol 29 (2) ◽  
pp. 69-74 ◽  
Author(s):  
József Hlinka ◽  
Miklós Berczeli ◽  
Gábor Buza ◽  
Zoltán Weltsch
Keyword(s):  
Surface Treatment ◽  
Laser Treatment ◽  
Contact Angles ◽  
Laser Surface ◽  
Lead Free Solder ◽  
Solder Paste ◽  
Laser Surface Treatment ◽  
Content Type ◽  
Wetting Properties ◽  
Free Solder

Purpose This paper aims to discuss the effect of surface treatment on the wettability between copper and a lead-free solder paste. The industrial applications of laser technologies are increasing constantly. A specific laser treatment can modify the surface energy of copper and affect the wetting properties. Design/methodology/approach The surfaces of copper plates were treated using an Nd:YAG laser with varying laser powers. After laser surface treatment, wetting experiments were performed between the copper plates and SAC305 lead-free solder paste. The effect of laser treatment on copper surface was analysed using optical microscopy and scanning electron microscopy (SEM). Findings The experimental results showed that the wetting contact angles changed with the variation in laser power. Furthermore, it means that the surface energy of copper plates was changed by the laser treatment. The results demonstrated that the contact angles also changed when a different soldering paste was used. Originality/value Previous laser surface treatment can be a possible way to optimize the wettability between solders and substrates and to increase the quality of the soldered joints.

Isothermal Aging Effects on the Microstructure, IMC and Strength of SnAgCu/Cu Solder Joint

2007 ◽  
Vol 353-358 ◽  
pp. 2928-2931 ◽  
Author(s):  
Xiao Yan Li ◽  
Xiao Hua Yang ◽  
Wei Zhen Dui ◽  
Ben Sheng Wu
Keyword(s):  
Tensile Strength ◽  
Solder Joint ◽  
Aging Time ◽  
Isothermal Aging ◽  
Solder Matrix ◽  
Aging Effects ◽  
Imcs Layer ◽  
X Ray ◽  
Formation And Evolution ◽  
Free Solder

The formation and evolution of the intermetallic compound (IMCs) between SnAgCu lead-free solder and Cu substrate, after isothermal aging at 150°C for 24, 48, 120, 240 and 480 hours, were studied. Scanning electron microscope (SEM) was used to observe the microstructure evolution of solder joint during aging. The IMC phases were identified by energy dispersive X-ray (EDX). The results showed that IMCs layer of Cu6Sn5 was formed at the interface of solder and Cu during reflowing. With the increase of aging time, the grain size of the interfacial Cu6Sn5 increased and the morphology of the interfacial Cu6Sn5 column was changed from scallop-like to needle-like and then to rod-like and finally to particles. At the same time, the rod-like Ag3Sn phase formed at the interface of solder and the IMCs layer of Cu6Sn5 with the aging time increased. In addition, large Cu6Sn5 formed in the solder with the aging time increased. The tensile strength was measured for the solder joints. The results showed that the tensile strength increases slightly at beginning and then decreases with the aging time. SEM was used to observe the fracture surface and it showed that the fracture position moved from solder matrix to the interfacial Cu6Sn5 IMCs layer with the aging time increased. The weakening of the solder matrix is caused by the coarsening of the eutectic solder structures. The weakening of the interfacial IMCs layer is caused by the evolution of morphology and size of the interface Cu6Sn5 layer.

Investigation of solder beading phenomenon under surface-mounted electrolytic capacitors

2022 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Daniel Straubinger ◽  
Attila Toth ◽  
Viktor Kerek ◽  
Zsolt Czeczei ◽  
Andras Szabo ◽  
...  
Keyword(s):  
Optical Microscopy ◽  
High Reliability ◽  
Primary Source ◽  
Circuit Board ◽  
Solder Paste ◽  
Reflow Soldering ◽  
Content Type ◽  
X Ray ◽  
Electrolytic Capacitors ◽  
Component Design

Purpose The purpose of this paper is to study the solder beading phenomenon (referring to larger-sized solder balls) of surface-mounted electrolytic capacitors. Solder beading could induce failures by violating the minimal electrical clearance on the printed circuit board (PCB). In modern lead-free reflow soldering, especially in high-reliability industries, such as automotive, aeroplane and aerospace, detecting and preventing such defects is essential in reliable and cost-effective manufacturing. Design/methodology/approach The large size of the involved components may block the view of automatic optical inspection; therefore, X-ray inspection is necessary. To detect the failure mode, X-ray imaging, cross-section grinding, optical microscopy and Fourier transformed infrared spectroscopy were used. High-resolution noncontact profilometry and optical microscopy were used to analyse component designs. The surface mounting process steps were also analysed to reveal their dependence on the issue. Test methods were designed and performed to reveal the behaviour of the solder paste (SP) during the reflow soldering process and to emphasise the component design relevance. Findings It was found that the reduction of SP volume only reduces the failure rate but does not solve the problem. Results show that excessive component placement pressure could induce solder beading. Statistical analysis revealed that differences between distinct components had the highest effect on the solder beading rate. Design aspects of solder beading-prone components were identified and discussed as the primary source of the problem. Practical implications The findings can be applied in surface-mount technology production, where the total failure count and resulting failure costs could be reduced according to the findings. Originality/value This paper shows that component design aspects such as the low distance between the underside of the component and the PCB and blocked proper outgassing of volatile compounds of the SP can be root causes of solder beading under surface-mounted electrolytic capacitors.

Influence of assembly parameters on lead-free solder joints reliability in Package-on-Package (PoP) technology

2015 ◽  
Vol 27 (3) ◽  
pp. 98-102 ◽  
Author(s):  
Janusz Sitek ◽  
Wojciech Stęplewski ◽  
Kamil Janeczek ◽  
Marek Kościelski ◽  
Krzysztof Lipiec ◽  
...  
Keyword(s):  
Solder Joints ◽  
Accelerated Aging ◽  
Lead Free ◽  
Process Window ◽  
Lead Free Solder ◽  
Solder Paste ◽  
Materials Selection ◽  
Content Type ◽  
Free Solder ◽  
Component Assembly

Purpose – The purpose of this paper is to evaluate the influence of assembly parameters on lead-free solder joints reliability in Package-on-Package (PoP) Technology and demonstrate factors important for this issue. Design/methodology/approach – Two types of soldering materials and three different assembly procedures were used for assembly of PoP system. The reliability properties of assembled PoP systems were investigated using accelerated aging and periodic resistance measurements of daisy-chain solder joints systems. The purpose of such approach was to determine which soldering material (flux or solder paste) as well as which assembly process parameter (dipping depth of upper component in soldering material), would provide better reliability properties of the solder joints in the PoP system. Findings – It was stated that both selected flux and solder paste dedicated to assembly of PoP systems can be utilized in soldering of PoP applications. More reliable PoP systems applications require larger attention regarding materials selection and assembly parameters. It is recommended 50 per cent dipping depth of ball’s height into soldering material during upper PoP component assembly for more reliable applications. For less demanding PoP systems, the process window from 30 up to 70 per cent is acceptable. All observed failures after thermal shocks occurred in upper PoP components. Originality/value – This paper explains how materials and assembly parameters have influence on lead-free solder joints reliability in PoP systems. Especially, influence of process window for dipping procedure of upper components balls into soldering material was presented.

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