Bonding wires are made from casting into millimeter diameter sized wire followed by progressive multi-die drawing and
annealing to achieve final diameter of 50 micron or below. As copper will work harden, annealing at high temperature
might be needed during the course of drawing, depends on the material characteristics. However, an annealing process at
the final diameter must be carried out to induce recrystallization and softening of the wire before it is being put to use.
Industry users are most interested in knowing the hardness of the copper wire for ultrasonic wedge bonding and also of remelted
wire that forms a ball for thermosonic ball bonding that will allow best bondability and least or no damage to the
device. Hence, to determine the hardness of the wire, they have to be measured at the exact size and configuration in order
to reflect the correct property