Laser processing to adjust the suspension preload of magnetic recording head stack assemblies

The suspension preload of head stack assemblies (HSA) of hard disk drives is adjusted after assembly, using a laser processing technique. Side firing optical fibers are used to direct the laser radiation to the suspension hinge area in the HSA. The preload can be either increased or decreased depending on the pulse length, peak power and average power of the laser used. This allows one to adjust the mean and tighten the preload distribution. The processing technique is shown to only alter the preload and not affect the other functional properties of the suspension.