Electronics - Disk Drive Flexure Welding
Disk Drive Flexures hold the ferrite reader that floats over the spinning magnetic media in a hard-drive. The high speeds of positioning and the ultra-close proximity of the ferrite reader mean that this assembly must be accurately assembled from 3 or 4 pieces of stainless steel with thicknesses ranging from 20um to more than 200um. Their design must accommodate resonances, stiffness, and overall component accuracy in three planes. Assembly of these flexures must be highly automated for low-cost, repeatable manufacture.
Lasers have been the only joining solution available for this application since the early 1980s. Their ability to produce discreet energy levels and pulse shapes for each weld location and relative thickness means that each weld is tailored to its target and the welding rate can be over 150 welds/second!
Most systems today use galvo-mirrors that direct the laser beam through a flat-field lens onto the part. Ultra-precise fixtures hold the parts together for laser welding and also feed inert gas to the weld area for clean, smooth, oxide-free, welds. Any brittle oxide or melt spatter on the surface can flake-off and contaminate the drive rendering it useless.
Pulsed YAG lasers produce the necessary discreet laser energy pulses for each weld. High beam quality fiber delivered units are best to achieve the very small weld diameters, some smaller than 100um diameter. Using more pulse energy and letting that energy flow into the surrounding area create larger welds. Creating consistent welds means that the assembly will remain very flat and not be warped due to uneven solidification forces. Special controls are used to achieve fast pulse energy changes with minimum system controller inputs.
Typical lasers that have been used for this application
JK125P, JK300P & JK300HP
For Fiber-Delivered Cutting, Welding, Heat Treating
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