By making V-groove just before soldering,
it prevents deterioration of flux and solder
ball scattering.
In addition, the oozing flux from the V-groove
improves the solderability.
Using BONKOTE V-cut machines and
LA type soldering irons together,
the prevention of solder ball scattering enable to
obtain its effect more.
Solder wires DIA. 0.6 ~ 1.6 mm are usable by
exchanging the guide pulley.