ABSTRACT The Electrochemical Migration (ECM) behaviour of lead-free, micro-alloyed, low Ag solder alloys was investigated using Scanning Transmission Electron Microscopy (STEM), Energy Disperse X-ray Spectroscopy (EDS) and Electron... more
ABSTRACT The Electrochemical Migration (ECM) behaviour of lead-free, micro-alloyed, low Ag solder alloys was investigated using Scanning Transmission Electron Microscopy (STEM), Energy Disperse X-ray Spectroscopy (EDS) and Electron Diffraction methods. Different solder alloys were investigated by Water Drop (WD) tests to stimulate ECM failure mechanism. After WD tests, differently structured dendrites were formed depending on the solder alloy types. The results showed that micro-alloying components (e.g. Sb) also played role during the ECM processes. The novelty of this study is the demonstration that Sb can take part in the ECM process; the ECM model of Sb is also discussed.
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This paper describes the interface reactions and diffusion between silver/polypyrrole (Ag/PPy) composite and silicon substrate. This composite material can be used as a novel technique for 3D-LSI (large-scale integration) by the fast... more
This paper describes the interface reactions and diffusion between silver/polypyrrole (Ag/PPy) composite and silicon substrate. This composite material can be used as a novel technique for 3D-LSI (large-scale integration) by the fast infilling of through-silicon vias (TSV). By immersion of the silicon wafer with via holes into the dispersed solution of Ag/PPy composite, the holes are filled with the composite. It is important to develop a layer between the composite and the Si substrate with good diffusion barrier and adhesion characteristics. In this paper, SiOx and two types of SiOxNy barrier layers with various thicknesses were investigated. The interface structure between the Si substrate, the barrier, and the Ag/PPy composite was characterized by transmission electron microscopy. The adhesion and diffusion properties of the layers were established for Ag/PPy composite. Increasing thickness of SiOx proved to permit less Ag to transport into the Si substrate. SiOxNy barrier layer...
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ABSTRACT In this paper the tin whisker growth properties of lead-free SAC (SnAgCu) solder alloys were investigated. There different alloys were studied: two micro-alloyed SAC (SnAgCu + Bi + Sb) and the widely applied SAC305 as reference.... more
ABSTRACT In this paper the tin whisker growth properties of lead-free SAC (SnAgCu) solder alloys were investigated. There different alloys were studied: two micro-alloyed SAC (SnAgCu + Bi + Sb) and the widely applied SAC305 as reference. FR4 test board was developed for 0805 chip resistor components. Solder joints were fabricated on imm-Sn surface finish. The samples were aged in elevated temperature and different humidity levels to induce the tin whisker formation: at 85 °C/85RH% and 85 °C/20RH%. The test duration was 3000 h. Whisker growth was checked after every 500 h by scanning electron microscope. The developed whiskers were etched by focused ion beam and the cross-sections were observed by scanning ion microscope and transmission electron microscope. It was shown that the lead-free SAC solder alloys can also develop tin whiskers and the whiskering ability depends on the corrosion behavior of the SAC solders. Copper and bismuth precipitations were found at the whisker roots and within the whiskers which could effect on the number, length and type of the developed whiskers.
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ABSTRACT The aim of this research is to examine the whiskering ability of immersion tin layers in natural and elevated temperatures and elevated or decreased humidity environments. Immersion tin layer with 2 μm layer thickness on copper... more
ABSTRACT The aim of this research is to examine the whiskering ability of immersion tin layers in natural and elevated temperatures and elevated or decreased humidity environments. Immersion tin layer with 2 μm layer thickness on copper substrate has been tested. Five different groups of samples has been investigated: a reference in room environment (25 °C/ 50% RH), two hot and dry circumstances in 50 °C and 105 °C temperature with 15% Relative Humidity (RH) and two hot and wet circumstances in 40 °C and 105 °C temperature with 92% RH and 100% RH respectively. The whisker growth was observed by using Scanning Electron Microscopy (SEM). The structure of the whiskers and the tin layer were also examined with FIB (Focused Ion Beam). It is shown that the immersion tin layer is also capable of growing tin whiskers. Most of the detected whiskers were the so called “nodule” types, approximately 3-9 μm long with 1-2 μm thickness.
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ABSTRACT In this paper the intermetallic (IMC) layer growth mechanisms and rates are investigated in Sn-Cu, Sn-Ag-Cu and Sn-Ni-Cu layer systems. The aim of the study is to characterize the IMC layer growth in these layer structures and... more
ABSTRACT In this paper the intermetallic (IMC) layer growth mechanisms and rates are investigated in Sn-Cu, Sn-Ag-Cu and Sn-Ni-Cu layer systems. The aim of the study is to characterize the IMC layer growth in these layer structures and find relationship between their whiksering behaviors. On Cu base substrate, Ni or Ag for barrier layer and Sn for surface finish was electroplated. The samples were aged in elevated temperatures to induce intermetallic layer growth. Two kinds of aging conditions have been used: 50°C and 125°C. The IMC layer growth was checked by etching the samples with Focused Ion Beam (FIB) and observing the cross-sections with Scanning Ion Microscope (SIM) and Energy-Dispersive X-Ray Spectroscope (EDX). It will be shown that the barrier layers can effectively blocks the development of Cu6Sn5 IMC. It was observed that the IMC growth mechanisms are totally different in the Sn-Ag-Cu system than in the Sn-Cu and Sn-Ni-Cu systems. The growth characteristics of the Sn-Cu and Sn-Ni-Cu systems are similar, expect during the deposition of Sn layer which could be one main reason of the different tin whiskering abilities.
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ABSTRACT In this paper the tin whisker growth properties of lead-free SAC (SnAgCu) solder alloys were investigated. There different alloys were studied: two micro-alloyed SAC (SnAgCu+Bi+Sb) and the widely applied SAC305 as reference. FR4... more
ABSTRACT In this paper the tin whisker growth properties of lead-free SAC (SnAgCu) solder alloys were investigated. There different alloys were studied: two micro-alloyed SAC (SnAgCu+Bi+Sb) and the widely applied SAC305 as reference. FR4 test board was developed for 18 pieces of 0805 chip resistor components. Solder joints were fabricated on imm-Sn surface finish. The samples were aged in elevated temperatures and different humidity levels to induce the tin whisker formation. Three kinds of aging conditions have been used: 85°C/85RH%, 105°C/100RH% and 105°C/20RH%. The test duration was 3000 hours. Whisker growth was checked after every 500 hours by scanning electron microscope. It was shown that the lead-free SAC solder alloys can also develop tin whiskers and the whiskering ability depends on the composition of the SAC solders.
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ABSTRACT The aim of this research is to examine the effects of annealing and recrystallization of electroplated tin layers on mitigating the growth of tin whiskers. Tin plating electroplated on copper substrate has been tested. Three... more
ABSTRACT The aim of this research is to examine the effects of annealing and recrystallization of electroplated tin layers on mitigating the growth of tin whiskers. Tin plating electroplated on copper substrate has been tested. Three different groups of samples have been investigated: reference, annealed and recrystallized. Three types of ageing were being used to accelerate the whisker appearance: two life-like circumstances with a constant elevated temperature in low humidity and a temperature cycling test. The whisker growth was observed by using scanning electron microscopy and was evaluated by the average and maximum whisker length and the average whisker density. It is shown that at different ageing temperatures whisker appearance and growth are decreasing in aspect of the applied pre-treatments. The effects of the pre-treatments were explained by changes of the grain structure in the tin layer which were observed with focused ion beam.
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Page 1. Investigating Whisker Growth on Annealed and Recrystallized Tin Platings Balázs Illés, Barbara Horváth, and Balázs Lipák Department of Electronics Technology, Budapest University of Technology and Economics, Budapest, Hungary... more
Page 1. Investigating Whisker Growth on Annealed and Recrystallized Tin Platings Balázs Illés, Barbara Horváth, and Balázs Lipák Department of Electronics Technology, Budapest University of Technology and Economics, Budapest, Hungary billes@ett.bme.hu ...
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ABSTRACT The aim of this research is to examine the whisker growth behaviour of tin-copper alloy surface finishes in highly oxidizing environment. Samples from copper base substrates were plated with 10 μm thick tin-copper alloys between... more
ABSTRACT The aim of this research is to examine the whisker growth behaviour of tin-copper alloy surface finishes in highly oxidizing environment. Samples from copper base substrates were plated with 10 μm thick tin-copper alloys between 0 and 5 wt% copper content (with 1% steps) by solder dipping technology. Two types of aging were being used to accelerate the whisker appearance; these were an elevated humidity and temperature condition (85°C/85%RH) and a Highly Accelerated Stress Test (HAST 105°C/100%RH) up to 2400 hours in order to keep the samples in highly corrosion environment. The whisker growth was observed by using Scanning Electron Microscopy (SEM) and was evaluated by the morphology of the whiskers, by the average and maximum whisker length and the average whisker density. Results indicate differences in whisker growth depending on the test circumstances and on the copper content. The series of tests has shown that the different test circumstances induce different whiskering mechanisms and the significance in whisker formation of humidity and melting temperature of the plating alloy were also proven.
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Abstract A major problem with tin electroplating is the formation of tin whiskers. These are spontaneous protrusions of few microns in diameter and up to hundreds of microns or even millimeters in length. There are several mitigation... more
Abstract A major problem with tin electroplating is the formation of tin whiskers. These are spontaneous protrusions of few microns in diameter and up to hundreds of microns or even millimeters in length. There are several mitigation strategies and using a nickel or silver ...
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ABSTRACT In this paper we have written about our work of XRF (X-ray fluorescence) analysis. With this non-destructive testing it is possible to analyze the composition of a certain material. While examining different materials we have... more
ABSTRACT In this paper we have written about our work of XRF (X-ray fluorescence) analysis. With this non-destructive testing it is possible to analyze the composition of a certain material. While examining different materials we have concluded that some manufacturers have not complied their products with the RoHS directives even after more than a year. After observing printed wiring boards (PWB), components and solders, sometimes we found amounts of restricted materials even 10 to 50 times above the limit. In our experiments we realized that not just the components, even the working tools have to comply with RoHS in order not to contaminate the experiments.