Institute of materials and machine mechanics Slovak Academy of sciences

Lead-free solder materials


Project start:11.03.2002
Project end:10.03.2007
Programme:COST
Project number:COST 531
Institute position in the project:Partner
Project leader at the institute:Pavol Šebo
The project joining of composite materials with copper substrate and with composite materials themselves by lead-free solder Sn-3.5Ag-1Cu was studied . Wetting of Cu substrate by the solder was measured by a sessile drop method in temperature interval 250-320 °C for 1800 s. Two types of composite materials - copper - carbon fiber (Cu-CF) and copper-tungsten filament (Cu-WF) - were studied. Both composites were prepared by diffusion bonding of matrix and fibers. Bonds Cu (or Cu-CF)-solder-CF-Cu, Cu (or Cu-WF)-solder-Cu-WF. In case of Cu-CF composite the bond failure occurred at the interface of the copper and fiber due to poor adhesion of copper to carbon fibers. Shear strength in this case was 22.0 MPa. In the case of copper - tungsten filament composite, failure occurred in the solder. The shear strength of bonds copper-composite and composite-composite was practically the same (26 and 27 MPa). The results showed that materials having different thermal expansion practically do not affect the shear strength of bond created by solder in question.
 
Cu-CF Joining of copper-carbon fibres composite with copper substrate