Photo resist application slider fabrication
Low stress adhesive and wax dispensing to bond rows of heads to lapping tools (row bond)
UV and silver dot applications at head gimbal assembly
Silver dot grounding for head stacks to case
Flux dispensing for flex circuit soldering
Underfill on flex circuit
Underfill on drive control board
Form in place gaskets for final drive assembly
The following provides more information about dispensing applications for hard disk drive assembly.
Speed, Precision & Control
Head to Gimbal
Jetting UV and silver adhesive dots, for head to gimbal assembly. Dot volume and position can impact flying height and ultimately yield. Using jetting to apply these critical glue dots, as small as 225 microns.
Row Tool Adhesive
Applying wax to lapping and dicing tools to hold wafer strips / rows. A jet with heated fluid path keeps wax in a molten state. Wax is jetted on demand, onto a lapping tool, minimizing the amount of wax used. Lower material costs and minimized tool cleaning.
Printed Circuit Board / Flex - Underfill
Nordson ASYMTEK is a world leader in supplying equipment for encapsulation and underfill on PCB or flex. Precise control allows underfill to be dispensed without bridging critical gaps. as in the photograph to the right, here two 5mm die are being underfilled and no bridging is occurring across a 1mm gap between the two die. Design engineers can typically save 40% on the area of a foot print for an underfilled die. Jetting on flex removes all of the process problems of determining needle to flex position. Jets are insensitive to dispense gap and hence can move faster into position and therefore have higher throughputs than needle dispensing.
Head Stack Assembly
For gimbal or head stack assembly, small dots of silver epoxy are used to electrically ground flex circuits to gimbal arms. Silver lines can also be dispensed to make electrical connection to MEMS actuators on heads. Nordson ASYMTEK has equipment from simple bench top automation to high speed, automated systems, capable of jetting dots of silver epoxy at rates of 50,000 dph.
Photoresist Spray - Air Bearing Surface Patterning
Nordson ASYMTEK's micro spray applicator can be used to apply photoresist to wafer strips for air bearing surface patterning. Liquid photoresist (PR) can produce finer features than dry film photo resists. Spraying PR instead of spinning, is much more efficient method of applying PR, reducing the amount of waste, and cleaning. Spraying can apply PR on single rows, eliminating the need to group rows for coating.
Flux Jetting and Solder Paste Dispensing
Nordson ASYMTEK has a range of flux jetting systems for precise application of flux to flex circuits used in head stack assembly. Flux can be applied by jets or needles, as dots or lines with thickness' as small as 5 microns.
In addition, we have a range of solder paste dispensing systems for every application.
Form In Place Gasket
Protecting hard disk drives from the outside environment requires a precision dispensed seal. Nordson has for many years supplied dispensing equipment for this application. Nordson's range of pail pumps and meter mix equipment has greatly simplified manufacturing of form in place gaskets (FIPG). At the same time Nordson ASYMTEK is developing new dispensing methods such as jetting to enable FIPG in smaller geometries and in tight spaces next to drive cover walls.