The influence of thermal ageing on the flow-stress of copper traces on PCB's

This study focuses on the onset of plastic flow in different copper raw materials. The tested copper sheets varied in the way in which they were manufactured and in terms of their post-manufacturing treatments, namely annealing. Tensile tests were conducted at various temperatures (24 degrees C, 60 degrees C, 100 degrees C, 150 degrees C) in a temperature controlled chamber on thin copper specimens. Each material was analysed in its raw form as received from the manufacturer and additionally in an annealed form for comparison. These additional specimens were annealed for 1 hour at 250 degrees C in a reflow oven. The results showed that the onset of plastic flow depends strongly on the manufacturing condition of the copper materials.