COST Action 531 Lead-free Solder Materials

Structural, physical and technological properties of lead-free solder materials on the base of tin Jaromír Drápala, Renata Kozelková et all. Institute of Mining and Metallurgy – Technical University of Ostrava, Ostrava, Czech Republic Jan Vřešťál Masaryk University, Brno, Czech Republic Aleš Kroupa Institute of Physics of Materials, Academy of Science of the Czech Republic, Brno, Czech Republic

Institute of Mining and Metallurgy – Technical University of Ostrava Faculty of Metallurgy and Materials Engineering Department of Non-ferrous Metals, Refining and Recycling Project COST OC Ministry of Education, Youth and Sports of the Czech Republic Title of our project: „Theoretical and experimental study of phase diagrams of low – melting binary and ternary alloys, their preparation and characterisation“ Jaromír Drápala Project leader

Team : Prof. Ing. Miroslav Kursa, CSc. Mgr. Petr Zlatohlávek, Safina Vestec, a.s., external graduant Ing. Rostislav Burkovič, CSc. Doc. Ing. Stanislav Lasek, PhD. Prof. Ing. Vlastimil Vodárek, CSc. Ing. Bedřich Smetana Ing. Rostislav Dudek, PhD. Co-workers : Ing. Jitka Malcharcziková Mgr. Zuzana Morávková, PhD. Quido Smitka Three diploma works: (Urbaníková, Zlatohlávek, Kozelková)

Cooperative and coordinating work places: Masaryk University in Brno (Prof. RNDR. J. Vřešťál, DrSc.) Institute of Physics of Materials AS of the Czech Republic, Brno (RNDr. A. Kroupa, CSc.) Vítkovice Research and development (Prof. Ing. V. Vodárek, CSc.) (Prof. Ass. J. Urbánek, CSc.) Czech Technical University in Prague, Faculty of Electrical Engineering, Prague (Prof. Ass. J. Urbánek, CSc.) Institute of Chemistry of Materials in Ostrava

in Partial results of the project solving in 2003:  Systematic study of binary systems on the base of tin, literary background research  Calculation of equilibrium solidus and liquidus curves for 15 admixture elements in tin.  Determination of equilibrium segregation (distribution) coefficients of admixtures in tin.  Statistical processing of tin – admixture binary diagrams from the standpoint of the credibility of input thermodynamic and experimental data.  Projection of the correlation periodical dependence of equilibrium segregation (distribution) coefficients of admixtures in tin on the atomic number of admixture element.

in Partial results of the project solving in 2004:  Systematic study of binary systems on the base of low-melting metals, literary background research  Calculation of equilibrium solidus and liquidus curves for Bi-, Cd-, Ga-, In-, Sb-, Zn- admixture elements binary systems.  Determination of equilibrium segregation (distribution) coefficients of admixtures in low-melting metals.  Correlation periodical dependence of equilibrium segregation (distribution) coefficients of admixtures in low-melting metals on the atomic number of admixture element.  Study of basic structural, physical and technological characteristics of the six alloys commercially produced in the Czech Republic (producer Kovohutě Příbram, a.s.): Sn99Cu1; Sn95Cu1.5Sb3.5; SnAg4; Sn95.5Ag3.8Cu0.7; Sn95Sb5 and classical Sn37Pb solder.

in Partial results of the project solving in 2005: Study of phase equilibria of isothermal sections in Copper – Indium – Tin ternary system.  Experimental preparation of nine types of alloys in the Cu-In-Sn ternary system with various contents of particular elements (melting, synthesis, homogenizing and casting into graphite moulds).  Long-term isothermal annealing of specimens in vacuum at 200, 400 and 600 °C at various times. Quenching of samples into water.  Identification of present phases and phase transformations.  Used analytical methods: differential thermal analysis (DTA, DSC, TG), chemical analysis (ICP-AES), chemical micro-analysis (EDX, WDX), metallography, measurement of micro-hardness of alloys annealed at 200 °C, tests of wettability, surface tension and density of alloys.

in Partial results of the project solving in 2006: 1)Creating of the computer program for modelling of solidus, solvus and liquidus surfaces in ternary systems (MATLAB) 2) Systematic study of binary systems on the base of Cu, Ag, Au, Pd. Assessment of regression parameters of solidus and liquidus curves, determination of equilibrium segregation coefficients of admixtures in copper, silver, gold and palladium. 3) Study of the copper – indium – tin ternary system. 4) Study of diffusion processes in Cu/In-Sn joints – reactive diffusion. Formation of intermetallic phases after long-time heat treatment. 5) Experimental preparation of lead-free solders with various contents of Ag, Cu, In, Sb, Bi and Sn. Assessment of selected physical, physico-chemical, mechanical and technological properties of 22 alloys.

in Partial results of the project solving in 2007:  Experimental preparation of ternary alloys for lead-free solders and investigation of their thermodynamic characteristics by means of DTA, TG, DSC, TMA, micro-structural analysis, chemical analysis, X-ray diffraction phase micro-analysis (EDX, WDX), measurement of surface tension and wettability of solders, measurement of mechanical properties (hardness, toughness), measurement of rezistivity.  Optimisation of chemical composition of new types of solders.  Tests of solderability in electrical engineering industry, investigation of interaction between a substrate and solder (collaboration with industrial producer – ON Semiconductors Czech Republic, a.s.)  Experimental preparation of solders and characterisation of properties of selected types of low-melting alloys  Study of reactive diffusivity in the Cu – In – Sn system  Comparison, systematization and evaluation of the obtained results  Final report

Systematic study of segregation coefficients in binary systems on the base of Cu, Ag, Au, Pd Cu – 47 binary systems Ag – 52 binary systems Au – 49 binary systems Pd – 59 binary systems Summary: 207

Periodical correlation dependence of segregation coefficients of elements in silver on atomic number of admixtures Atomic number of admixtures

Study of the copper – indium – tin ternary system Chemical composition of specimens: CuInSnCuInSn No: Nominal [at. %]Analysis ICP-AES (at. %)

EXPERIMENT Heat treatment of specimens in vacuum: Heat treatment of specimens in vacuum: * 200 °C 56 days * 200 °C 56 days * 400 °C 22 days * 400 °C 22 days * 600 °C 7 days * 600 °C 7 days + quenching into water Diffusion annealing of Cu/In, Cu/Sn, Cu/In-Sn joints at 400 and 600 °C, various times Diffusion annealing of Cu/In, Cu/Sn, Cu/In-Sn joints at 400 and 600 °C, various times

Results of the differential thermal analysis Sample No: Heating 7 °C/min Cooloing 7 °C/min Liquid temperature [°C] Peak 1 [°C] Peak 2 [°C] Peak 3 [°C] Peak 4 [°C] Peak 1 [°C] Peak 2 [°C] Peak 3 [°C] Peak 4 [°C] Author[Lee]

Results: Thermo-Calc v. Experiment

Diffusion in Cu/25In+75Sn joint annealed at 600 °C / 48 h Cu  Cu  hole  solder

Results – diffusion 873 K 673 K  Cu      L

Experimental preparation of lead-free solder materials with various contents of Ag, Cu, In, Sb, Bi in Sn

DTA analysis (re-heating and cooling rate 4 °C/min) and micro-hardness of tin alloys

DTA analysis (re-heating and cooling rate 4 °C/min)

Tests of surface tension 242 °C260 °C274 °C 286 °C F45 - Sn-0.5Ag-3Cu-5In Temperature [ °C] Surface tension [mN/m]

Test of wettability Meniscograph solderability tester GEC

Test of wettability Characteristics of specimens Tested surfaces: brass (66 wt. % Cu), nickel and copper wires, diameter 1 mm. Lead–free solders: Sn95Sb5; Sn95Sb3,5Cu1,5; Sn96Ag4; Sn95,5Ag3,8Cu0,7; Sn97Bi2Cu1; Sn97Cu3; Sn99Cu1; Sn99,75 Lead- tin solderSn63Pb37 Fluxes: Epsilon 5; Epsilon 5M; Epsilon 2 Wire: brass 66 % Cu Solder: SnAg4 Flux: Epsilon 2 Wire: Cu, Solder: Sn95Sb3.5Cu1.5 Flux: Epsilon 2

Test of wettability Classification of solders and soldering flux Epsilon 2 at the test of wettability:

Corrosion tests Methods: Potentio-dynamic polarisation tests using 0.1 mol/l NaCl water solution Salt spray test, Galvanic corrosion test, Polarisation resistance test BEST

Test of solderability Fluxes: FB12-11 MT-SW 24/3 MT-SW24/2 F1 Epsilon 5 Epsilon 5M

Comparison of lead-free solders

Publications Year Impact journals Other journals Proceeding - conference Diploma work *2+2* 1*1** in print

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