▁in ks ▁used ▁in ▁thick ▁film ▁processes ▁a ▁high ▁temperature ▁( us ually ▁greater ▁than ▁ 3 0 0   ° C ) ▁firing ▁is ▁required ▁to ▁fix ▁the ▁layers ▁in ▁position ▁perman ently ▁on ▁the ▁substr ate . ▁ ▁A bras ive ▁Tr imming ▁of ▁resist ors ▁After ▁firing ▁the ▁resist ors ▁can ▁be ▁trim med ▁using ▁a ▁precision ▁ab ras ive ▁cutting ▁method ▁first ▁developed ▁by ▁S . S . ▁White . ▁The ▁method ▁involves ▁a ▁fine ▁ab ras ive ▁media , ▁usually ▁ 2 7 mic ron ▁al umin um ▁ox ide . ▁The ▁ab ras ive ▁cutting ▁is ▁fed ▁through ▁a ▁car b ide ▁no zz le ▁tip ▁that ▁can ▁be ▁of ▁different ▁sizes ▁that ▁can ▁range ▁from ▁. 0 0 5 " ▁through ▁. 0 0 6 " X . 0 6 0 " ▁rect angular . ▁The ▁no zz le ▁is ▁advanced ▁through ▁the ▁fired ▁res istor ▁while ▁the ▁res istor ▁element ▁is ▁monitor ed ▁with ▁pro be ▁contacts ▁and ▁when ▁final ▁value ▁is ▁reached ▁the ▁ab ras ive ▁bl ast ▁is ▁shut ▁off ▁and ▁the ▁no zz le ▁ret ract s ▁to ▁the ▁zero ▁start ▁position . ▁The ▁ab ras ive ▁technique ▁can ▁achieve ▁very ▁high ▁toler ances ▁with ▁no ▁heat ▁and ▁no ▁crack ing ▁of ▁the ▁glass ▁f rit ▁used ▁in ▁the ▁in k ▁form ulation . ▁ ▁Las er ▁trim ming ▁of ▁resist ors ▁After ▁firing , ▁the ▁substr ate ▁resist ors ▁are ▁trim med ▁to ▁the ▁correct ▁value . ▁This ▁process ▁is ▁named