Title :
Influence of Cooling Rate and Composition on the Solidification of SnAgCu Solders
Author :
Müller, Maik ; Wiese, Steffen ; Wolter, Klaus-Jürgen
Author_Institution :
Electron. Packaging Lab., Tech Univ. Dresden
Abstract :
This study points out the influence of cooling rate and solders composition on the microstructure of bulk SnAgCu. Therefore the alloys SnAg3.8Cu0.7, SnAg3.0Cu0.5 and SnAg3.5Cu0.4 were solidified with different cooling rates from 0.35 K/min to 37.4 K/min. During these experiments the temperature of the solder was measured. Changes in microstructure were investigated after thermal storage at 125degC, for 0.05 h, 0.5 h, 5 h, 50 h and 500 h. In an additional experiment a temperature gradient was generated inside different solder samples during solidification. The cross sections of these bulk samples indicate influence and dependence on phase growth, caused by this directed solidification. The chosen alloys, SnAg3.0Cu0.5, SnAg3.0Cu1.5 and SnAg3.0Cu0.5Au0.14 show effects on microstructure, caused by impurities like Au and Cu, which can solute from the PCB metallization during reflow. Another experiment shows the potential and the advantages of a new developed method for temperature measurements during the reflow process
Keywords :
cooling; copper alloys; crystal microstructure; directional solidification; gold alloys; metallisation; reflow soldering; silver alloys; solders; tin alloys; 0.05 h; 0.5 h; 125 C; 5 h; 50 h; 500 h; PCB metallization; SnAgCu; SnAgCuAu; microstructure changes; phase growth; reflow soldering; solders composition; solders cooling rate; solders solidification; temperature measurements; thermal storage; Electronics cooling; Environmentally friendly manufacturing techniques; Gold; Impurities; Intermetallic; Lead; Metallization; Microstructure; Temperature; Thermal stresses;
Conference_Titel :
Electronics Systemintegration Technology Conference, 2006. 1st
Conference_Location :
Dresden
Print_ISBN :
1-4244-0552-1
Electronic_ISBN :
1-4244-0553-x
DOI :
10.1109/ESTC.2006.280179
