MAGNETIC AND MECHANICAL-PROPERTIES OF MICROMACHINED STRONTIUM FERRITEPOLYIMIDE COMPOSITES

In this work, strontium ferrite/polyimide composite thin films are fab ricated and characterized for micromachining applications, The applica tion of these materials in microelectronics and micromachining dictate s the use of different polymers than those previously used for convent ional plastic magnets due to fabrication compatibility constraints, Th e material investigated here consists of magnetically anisotropic stro ntium ferrite particles suspended in a benzophenone tetracarboxylic di anhydride-oxydianiline/metaphenylene diamine polyimide matrix, Magneti c, mechanical, and processability properties of these composites are i nvestigated for a strontium ferrite loading range of 55%-80% by volume , Intrinsic coercivity H-ci, residual magnetic flux density B-r, and m aximum energy product (BH)(max) have been determined. For an 80% by-vo lume concentration loading of ferrite, H-ci of 318 kA/m, B-r approachi ng 0.3 T, and (BH)(max) of 11900 T . A/m have been achieved, Biaxial Y oung's modulus and residual stress are determined using a slightly mod ified in-situ load/deflection technique, The biaxial Young's modulus i ncreases with increasing the magnetic powder loading. The materials ha ve been deposited and patterned using two techniques: 1) screen-printi ng and 2) spin-casting, followed by photolithography, Finally, a simpl e magnetic microactuator made with those materials has been fabricated and tested, which demonstrates the usefulness of those materials to m icromachining.