MECHANICAL PROPERTIES OF Sn-In-Ag WITH DIFFERENT WEIGHT PERCENTAGE OF INDIUM LING CHUO ANN

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3 MECHANICAL PROPERTIES OF Sn-In-Ag WITH DIFFERENT WEIGHT PERCENTAGE OF INDIUM LING CHUO ANN A report submitted in partial fulfillment of the requirements for the award of the degree of Bachelor of Science and Education (Physics) Faculty of Education Universiti Teknologi Malaysia March 2006

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5 Dedicated to my beloved dad (Ling Yew Lung) and mum (Chan Swee Kheng) iii

6 iv ACKNOWLEDGEMENT Firstly, I would like to thank my supervisor, Prof. Madya Dr. Mohammad Radzi Sudin who helps me a lot in completing this project. He guides and teaches me from time to time. Advices and examples given by him were mostly appreciated. I had learned and gained much knowledge especially in physics. Secondly, I would like to express my gratitude to all the lab assistants in Department of Physics, Faculty of Science. They might include Mr. Md. Sam, Mr. Jaafar and Mr. Rahman. They guided me in using equipments in laboratory. Moreover, they also provided the materials which I need in this project. Besides, I would like to thank Mr. Jefri for helping me to operate EDAX. Nevertheless, thank you to my dear family who always support and encourage me. My family had encouraged me to do my best in this project. Besides, I would like to express my gratitude to my course mates and friends who had always shared their idea with me. Finally, thank you to those who had ever helped me directly and indirectly which I cannot state out every one of them. Their helps, advices and encouragements were mostly appreciated. Thank you.

7 v ABSTRACT Conventional alloy (Sn-Pb) contains lead which is harmful to human health. Lead free solders are developed to replace the conventional alloy. The objective of this project is to identify the mechanical properties of tin-indium-argentum (Sn-In- Ag) alloy. Five samples of Sn-xIn-2.8Ag alloy with different weight percentage of indium, x = 16, 18, 20, 22 and 24 were prepared by heating process in furnace. The compositions of alloys were determined by using Energy Dispersive X-ray (EDAX). Densities of the alloys were determined by Archimedes principle. Meanwhile, Differential Thermal Analyzer (DTA) was used to find out the melting temperature of each alloy. Besides that, ultrasonic testing was carried out to determine the Young modulus of the samples. The results obtained showed that the compositions of the samples prepared were different from the initial compositions. The densities of alloys were slightly differ with the increasing of indium. The melting points of alloys decrease when the amounts of indium increase. Moreover, Young modulus is decreased with the increasing of weight percentage of indium. Sn-24In-2.8Ag has potential to become solder material because it has melting point and Young s modulus close to conventional alloy.

8 vi ABSTRAK Aloi konvensional (Sn-Pb) mengandungi plumbum yang boleh membahayakan kesihatan manusia. Pateri tanpa plumbum dihasilkan untuk menggantikan aloi konvensional. Objektif kajian ini ialah untuk mengkaji sifat mekanik aloi timah-indium-argentum (Sn-In-Ag). Lima sampel aloi Sn-xIn-2.8Ag dengan peratus berat indium, x = 16, 18, 20, 22 dan 24 disediakan dengan proses pemanasan menggunakan relau. Peratus komposisi aloi ditentukan dengan menggunakan kaedah Sinar-X Sebaran Tenaga (EDAX). Ketumpatan aloi ditentukan dengan menggunakan prinsip Archimedes. Kaedah Analisis Terma Pembezaan (DTA) pula digunakan untuk mengkaji suhu lebur setiap sampel. Selain itu, ujian ultrasonik dijalankan untuk menentukan modulus Young sampel. Keputusan yang diperolehi menunjukkan komposisi sampel yang dihasilkan berbeza dengan komposisi asal. Ketumpatan aloi berubah sedikit apabila indium bertambah. Suhu lebur pula berkurang apabila kandungan indium bertambah. Sementara itu, modulus Young berkurang dengan pertambahan peratus berat indium. Sn-24In-2.8Ag berpotensi untuk dijadikan bahan pateri kerana ia mempunyai suhu lebur dan modulus Young yang hampir kepada aloi konvensional.

9 vii TABLE OF CONTENTS CHAPTER ITEMS PAGE THESIS STATUS DECLARATION AUTHENTICATION TITLE CLARIFICATION DEDICATION ACKNOWLEDGEMENT ABSTRACT ABSTRAK TABLE OF CONTENTS LIST OF TABLES LIST OF FIGURES LIST OF SYMBOLS LIST OF APPENDICES i ii iii iv v vi vii x xi xiii xv CHAPTER 1 INTRODUCTION 1.1 Research background Literature review Objective Scope of study 5 CHAPTER 2 THEORY

10 viii 2.1 Tin (Stannum) Indium Argentum Alloy Phase iagram Energy-Dispersive X-ray Spectroscopy (EDAX) Differential Thermal Analysis (DTA) Archimedes principle Young s modulus Ultrasonic testing 22 CHAPTER 3 METHODOLOGY 3.1 Introduction Preparation of material Alloying with furnace Slicing process Grinding and polishing process Composition percentage determination Measurement of density Determination of melting temperature Young s modulus measurement 40 CHAPTER 4 RESULT AND DICUSSION 4.1 Introduction Composition determination Density measurement Determination of melting temperature Determination of Young s modulus 51

11 ix CHAPTER 5 CONCLUSION AND RECOMMENDATION 5.1 Introduction Conclusion Recommendation and Suggestions 56 REFERENCES 57 APPENDICES APPENDIX A-B 59-83

12 x LIST OF TABLES TABLE NO. TITLE PAGE 2.1 Properties of Stannum, Indium and Argentum Percentage of composition Weight percentage of each sample Percentage of deviation of indium composition Density measurement for each composition of alloy Melting temperature of Sn-In-Ag alloy Young s modulus of Sn-In-Ag alloy Conclusion of the results 56

13 xi LIST OF FIGURES FIGURE NO. TITLE PAGE 1.1 Research flow chart Interstitial and substitutional structures 10 (a) Interstitial solid solution (b) Substitutional solid solution 2.2 Phase diagram 12 (a) Phase diagram of complete miscibility in solid and liquid states (b) Phase diagram of complete miscibility in liquid state and no miscibility in solid state (c) Phase diagram of complete miscibility in liquid state and partial miscibility in solid state 2.3 Sn-In-Ag alloy phase diagram Schematic diagram of spectrometer arrangements for wavelength-dispersive and energy-dispersive X-ray spectroscopy (WDXS/EDAX) in electron microscopy EDAX instrumentation for TEM and SEM with conventional EDAX detector attached to a TEM/STEM Schematic illustration of a DTA cell The buoyant force on a cube Block diagram of pulse echo method The principle of time of flight measurement Sound pulse 25 (a) Initial pulse = Start (b) Pulse after 10 ms 2.11 Electron beam 27

14 xii (a) Beam spot at the 4th scale graduation (b) Beam spot at the 8th scale graduation (c) Backwall echo at the 8th scale graduation 2.12 Longitudinal wave Transverse waves or shear waves Digital weighing machine Furnace Spark Erosion Unit Strip Grinder Model Buehler Tool Grinder Diamond compound Energy Dispersive X-ray (EDAX) Archimedes method Differential Thermal Analyzer Ultrasonic testing (pulse-echo overlap) Comparison between the experiment result and actual value of weight percentage of indium Relation between densities and different weight percentage of indium Graph melting temperature versus weight percentage of indium Graph Young modulus versus weight percentage of indium 53

15 xiii LIST OF SYMBOLS A - Area E - Young s modulus f - Frequency F - Force F B - Buoyant force g - Acceleration of gravity G - Shear modulus h b - Distance between bottom of object to fluid surface h t - Distance between top of object to fluid surface K - Bulk modulus L - Length L 0 - Original length m f - Mass of fluid m w - Mass of fluid displaced m r - Reduced mass P b - Bottom pressure P t - Pressure on the top t - Time v L - Longitudinal velocity V - Volume W - Weight of object in air W r - Weight of object in fluid W t - Weight of object in toluene L - Length difference P - Pressure difference ρ - Density of object ρ f - Fluid density

16 xiv ρ t - Density of toluene σ - Stress ε - Strain

17 xv LIST OF APPENDICES APPENDIX TITLE PAGE A Results of EDAX for each sample 59 B Results of Differential Thermal Analysis (DTA) 74

18 CHAPTER 1 INTRODUCTION 1.1 Research background Soldering technology has became important for the interconnection of electronic devices and circuits. The microelectronic industry has used Sn-Pb solders for a variety of interconnection needs. Electronic devices such as computers, printers, PDAs, fax machines, televisions, VCRs, refrigerators and dishwashers all contain Sn-Pb solders that are used primarily for interconnecting and packaging electronic components and assemblies. However, it is now widely recognized that lead is a highly toxic substance. Lead and compound of lead have been cited by Environmental Protection Agency (EPA) as one of the top 17 chemicals containing greatest threat to human beings and the environment (Yu et al., 2004). Therefore, many efforts have been taken to solve the consequences of the lead usage. The use of lead alloy can give a great damage to human health. If someone is exposed to lead seriously, it may cause accumulation of lead in his/her body. Consequently, he may get blood and central nervous systems damage (Juberg, 2000). Besides, exposure to lead is known to cause neurological, reproductive, renal and hematological disorders. Children are especially at risk, as early high blood lead levels can adversely affect their development. Lead poisoning can be detected by blood analysis and the limits are defined by national government. The standard upper value of untainted human beings should not exceed 130 µg/l (Miric and Grusd, 1998).

19 2 With the increased use of consumer electronics and large appliances, there has been a substantial growth in lead containing waste electrical and electronic equipment (e-waste). In 1998, e-waste represented over 6 million tons of waste or approximately 4% of the municipal waste stream. This amount is expected to increase by 3% to 5% annually (CEC 2000). This implies that the amount of lead contained in municipal waste will increase. The world is moving towards implementation of environmentally friendly manufacturing techniques. Due to the hazard of lead to human health and the environment, the commercial microelectronic industry is rapidly implementing Pb free strategies. In 1998, the European Union (EU) introduced an legislative action called the WEEE (Waste from Electrical and Electronic Equipment) Directive. The WEEE Directive calls for a ban on lead-in all electronic (except automotive) by 1/1/2004. The law intends to ban the selling and import of electrical or electronic equipment containing lead interconnect (Charles, 2002). Besides, Japan is also working toward reduction or elimination of lead and has showcased some consumer products that are touted as lead free. On January 1998, JEIDA (Japanese Electronic Industry Development Association) and JIEP (Japanese Institute of Electronics Packaging) presented a lead-free roadmap. Some major Japanese OEMs begin to jointly develop recycling processes for electronic products. The aggressive move of Japanese manufacturers will justify European legislation requiring Pb reduction and highly recyclable electronic products. In United State (U.S), NEMI (National Electronics Manufacturing Initiative) has been coordinating the effort of U.S industry to find viable solutions for lead-free soldering. IPC also organized a conference IPC Works 99 which was held in October 1999 at Minneapolis with major emphasis on lead free issue.

20 3 It is important to develop possible alternative lead-free solder for electronic assemblies replacing the lead solder. There is no drop-in replacement for Sn-Pb solder. Each potential substitute alloy has its disadvantage. Various chemical, physical and mechanical properties of the candidate alloy systems as well as economic considerations should be taken into account in order to design the prospective materials. 1.2 Literature Review Research and development of lead free solder alloys have focused on identifying alloys that meet specific criteria for manufacturing, reliability, toxicity, cost and availability. These criteria can be understood by examing the metallurgy and constraints of a typical solder joint with respect to manufacturing and reliability. The metallurgy of solder alloy includes phase transformations, wetting behaviour and mechanical properties. Among the 90 naturally occurring elements, only 11 elements can be combined with each other to form a soft solder usable for circuit board assemble. Those are antimony, bismuth, copper, gallium, gold, indium, lead, palladium, silver, tin and zinc. The most prevalent alloy composition is at or close to the eutectic composition 63Sn-37Pb (melting point C). A lot of lead-free solder alloys have been proposed such as 93.6 Sn-4.7Ag-1.7Cu, 95.5Sn-3.9Ag-0.6Cu, 99.3Sn-0.7Cu, 78Sn-6Zn-16Bi and so on. The alloys are expected to be multicomponent because the most common binary candidate-solders do not satisfy some technologic parameters. The 77.2Sn-20In-2.8 Ag solder alloy is a potential lead-free solder for replacing the traditional Sn-Pb solders. According to the Journal of Electronic Materials (Yeh, 2002), addition of Indium in Sn-Ag solders could depress their melting temperature. Moreover, the Au dissolves much more slowly into the solder

21 4 which contain Indium. Kariya and Otsuka (1998) have also reported that the mechanical properties of Sn-3.5Ag-5In solder were better than those of the eutectic Sn-Pb alloy. Therefore, it is worthwhile to establish a database of ternary Sn-In-Ag solders for electronic packaging. National Center for manufacturing Sciences (NCMS) had included Sn-20In- 2.8Ag alloy in manufacturing and reliability trials because they wanted to have one alloy with a liquidus temperature close to 183 o C. Besides, 77.2Sn-20In-2.89Ag showed the shortest fatigue life of any lead-free solder tested for both thermal cycling conditions and both components that showed solder joint failures. Indium Corporation has developed alloy Sn-In-Ag with composition range ( )Sn-( )In-( )Ag. According to the Indium Corporation study, DSC data for Indalloy 227 indicates that the presence or disappearance of the C low temperature eutectic Sn/In phase is dictated by the content of In only. According to Ning Cheng Lee (2002), the physical properties of Sn-20In-2.8Ag are fairly comparable to those of 63Sn-37Pb. This alloy has both a higher tensile strength and shear strength than 63Sn-37Pb. From the Environment Report 2004, Anritsu Corporation has conducted pilot tests to substantiate the validity of a new type of lead free solder consisting of Sn-In- Ag. They have corroborated the possibility of lead free soldering even for parts with a low heat-resistance temperature. The mechanical properties of Sn-In-Ag alloy should be furthered investigated to determine the alloy is compatible for electronic assemblies.

22 5 1.3 Objectives The purpose of this project is to grow a lead-free alloy which has melting point and mechanical properties close to 63Sn-37Pb alloy. Lead-free alloy will replace the traditional Sn-Pb solder in order to overcome the hazardous problem of Pb to health. The lead-free alloy which is going to be investigated in this project is Stannum-Indium-Argentum alloy. Different composition of Sn-In-Ag will be used in finding the mechanical properties of the alloy. The percentage of composition in Sn- In-Ag alloy is determined in the beginning of the research. Then, this research will look into the melting temperature, density and Young s modulus of Sn-In-Ag alloy. 1.4 Scope of Study This project looks into the characteristic of ternary alloy Sn-In-Ag. Different composition of Sn and In is grown by using furnace. Then, X-ray Energy Dispersion (EDAX) is used to determine the composition of element in the alloy. After that, the melting temperature of the alloy is determined by using Differential Thermal Analyzer (DTA). At the same time, Archimedes Principle is used to find out the density of the alloy. Finally, the alloy is tested for its Young s modulus. The flow of the research is shown in flow chart below (Figure 1.1). The flow chart show the activities and works which have been done to investigate the mechanical properties of Sn-In-Ag.

23 6 Sn-In-Ag alloy preparation (different weight percentage) Alloying with furnace Slicing the sample (Spark Erosion Unit) Grinding and polishing Investigation of mechanical properties of Sn-In-Ag Percentage of composition (EDAX) Melting temperature (DTA) Density (Archimedes principle) Young s modulus (Ultrasonic testing) Figure 1.1 : Research flow chart