Papers by Keyword: Lead-Free Solder

Abstract: In electronics industries, most of them had to shifted their solder materials from leaded solders into lead-free solders due to the environmental concerns and follow the legislation of Restriction of use Hazardous Substances (RoHS). Thus, Sn-Ag-Cu solder is one of the choices that can replace the leaded solder and also offer better properties. This study investigates the comparison between Sn-4.0Ag-0.5Cu (SAC405) and EN(P)EPIG and EN(B)EPIG surface finishes. Reliability of solder joint has been assessed by performing solid state isothermal aging at 150oC for 250 up to 2000 hours. After reflow soldering process, (Cu,Ni)₆Sn₅ intermetallic compound (IMC) is dominated at near centre of solder meanwhile (Ni,Cu)₃Sn₄ IMC is dominated at near outside of solder ball_. Moreover, aging time resulted in an increase in thickness and changed the morphology into more spherical, dense and large grain size. Analysis by optical microscope revealed that the IMC thickness of EN(B)EPIG produced thicker IMC compared to EN(P)EPIG surface finish during reflow as well as isothermal aging.

Abstract: With world-wide strict legislation for reduction or removal of lead from industrial waste, development of a large number of lead-free alternative solder materials had been intensively examined. The drive for lead-free solders development was towards systems that can imitate conventional lead containing solder alloys in terms of melting temperatures and improvement of mechanical properties. Nanostructured solder alloy, with a grain size of typically < 100 nm, was a new class of materials with properties distinct from and frequently distinguished to those of the conventional alloy. In comparison, nanostructured solder alloys exhibit higher strength and hardness, enhanced diffusivity, and excellent soft and hard magnetic properties. Numerous different techniques were performed to synthesize these nanostructured solder alloys. Electrodeposition method has generated huge interest in nanostructured solder preparation, mainly due to its ability to deposit solders selectively and uniformly at nanoscale. These factors bring significant influences on the behaviors of products, such as magnetization, density, ductility, wear resistance, corrosion resistance, porosity, molecular structure, and crystal properties which plays a vital part in the field of electronic manufacturing. In this paper, a short review on the electrodeposition, a useful technique to deposit different metals and alloys, as a method for nanostructured lead-free solder alloys preparation is presented.

Abstract: This paper demonstrates the development of an experimental technique of in-situ observation for soldering of Sn-0.7wt%Cu lead-free solder on a Cu substrate which was achieved for the first time by synchrotron X-ray imaging. Reactions between liquid solder and Cu substrate during a soldering process were able to be recorded in real-time. Individual stages of the soldering process consisted of flux activation in removal of Cu oxide, solder melting and contact with the Cu substrate (wetting) and intermetallic compound (IMC) and void formation between the solder and Cu substrate. The technique development which includes experimental setup with calculated optimum beam energy in the range of 20 – 30 keV appears to result in a clear observation of real-time X-ray imaging of the soldering process. This technique provides a key method to understand the mechanism of formation of micro-electronic inter-connects for future electronic packaging applications.

Abstract: The effect of dipping time to the intermetallic compound and free solder thickness of Sn-Cu-Ni (SN100C) lead-free solder has been investigated. Dipping of copper strips in molten solder was carried out using GEN3 solderability test machine with 20 s, 60 s, 120 s, 180 s, and 240 s of dipping time. Scanning Electron Microscope (SEM) was used to observe the solder coating on the copper strips. Thickness of IMC, free solder and total solder coating was calculated. The influence of dipping time was established. The results indicated that longer dipping time produced high IMC thickness while the free solder thickness reduced with the growth of IMC. Solderability test was also conducted to know the wettability of SN100C coating for the lowest dipping time which had resulted in 1.571 s of wetting time and 4.066 mN of maximum force.

Abstract: SN100C lead-free solder coating wettability on SN100C solder has been investigated on as soldered samples and exposed intermetallic compound (IMC). In addition, the effect of oxidation on its wettability has also been investigated. Oxidation layer on the coated copper surface was developed after 120 hours of exposure on as soldered samples and exposed IMC samples. GEN3 solderability test machine in globule mode was used to determine the wettability of each sample. The influence of oxidation and the effect of exposed IMC were established. Results show that oxidation affected wettability by increasing the wetting time. On the other hand, exposed IMC had increased the wetting time and decreased the maximum force.

Abstract: The electrochemical corrosion behavior of the Sn-8Zn-3Bi-xCu lead-free solder in 3.5%NaCl solution was studied to reveal effect of Cu addition on the corrosion resistance of Sn-8Zn-3Bi solder alloy. The results showed that adding Cu element increased the corrosion potential of Sn-8Zn-3Bi-xCu solder alloysThe corrosion resistance of Sn-8Zn-3Bi-xCu solder alloys was improved correspondingly. The corrousion product of Sn-8Zn-3Bi-xCu alloy was mainly zinc oxide. More corrosion products were observed with the increse of Cu content.

Abstract: Industry should gradually replace the tin-lead solder alloys used traditionally in the soft soldering technology by lead-free soldering alloys, which raises a lot of new technological and scientific problems to be solved. The introduction and application of lead-free alloys caused a number of soldering defects not observed earlier; mechanisms of their formation are still unclear. One of such defects is whisker formation, another one is intensified formation of intermetallic phases. The appearance of undesired intermetallic phases in the soldering material spoils its mechanical properties; therefore it is particularly important that these phases do not form in electronic components. Besides, the formation of intermetallic compounds may occur in the soldering bath, thus making the soldering process difficult or even impossible.Tin-copper-nickel and tin-silver-copper alloys are suitable for the replacement of tin-lead alloys. The components of these alloys were studied. After metallographic examination of the specimens the occurrence of intermetallic phases was determined by the XRD method. The identification of intermetallic phases was carried out by using literature data and phase diagrams.

Abstract: With the increasing focus on developing environmentally benign electronic packages, Pb-free alloys have received a great deal of attention. Among the lead-free solder materials, Sn–Ag–Cu alloy has advantages of good wetting property, superior interfacial properties, high creep resistance and low coarsening rate. In this article, the organization and mechanical performance of Sn-Ag-Cu Material are investigated. Series of inspections and analytical research methods are introduced. Experimental results show that Sn-Cu solder organization contains a large number of Cu₆Sn₅ graphic, while Sn-Ag-Cu graphic is IMC Ag₃Sn graphic. The mechanical propersity of Sn-Ag-Cu alloy is better than the Sn-Cu alloy. Fracture surfaces of the Sn-Ag3.0-Cu0.5 alloys specimen have many small size and homogeneously distributed dimples.

Abstract: Physical and mechanical properties of a solder joint will be improved by adding the high performance of reinforcement particulates in the monolithic lead-free solder. In this study, 0.1wt% of activated carbon (AC) was added into Sn-0.7Cu lead-free solder which fabricated via powder metallurgy (PM) techniques. Various parameters used in PM technique such as mixing time, compacting load and sintering temperature has been carried out in fabricating the composite solder. In this study, the best mixing time has been optimized. The distribution of carbon in SnCu matrix for each mixing time was observed by using optical microscope. Microstructural observation showed that the increasing in mixing time has increased the number of AC particles to become agglomerated. It is found out that 1hour of mixing time is the best parameter to fabricate SnCu/AC composite solder via powder metallurgy route since the distribution of reinforcement particles has distributed uniformly at the grain boundaries without any agglomeration.

Abstract: Studying Al particles reinforced composite lead-free solder by experiments of constant temperature thermal stress aging treatment. Scanning electron microscope was used to observe the micro-structure of composite solder. The results show that composite lead-free solder after constant 125°C aging treatment for 24 hours, Al particles has two types of morphologies: one is small amount of solid solution,another type is a large number of aluminum particles structure.The existence of Al particles slowed down the coarsening rate of the Bi Phase grain, and obtained uniform refined the Bi Phase grain.