TADCO Separator Plates TADCO Separator Plates are offered in four different stainless steel alloys with varying degrees of hardness and surface finish: 304, 420, 630 and S-4 Offering a choice of alloys allows TADCO to design each job to the customers specific needs. This flexibility makes a world of difference in a competitive PCB market. TADCO's superior quality assures the customer of unsurpassed flatness, hardness, parallelism and outstanding surface finish. SPECS: 304 Stainless: Custom polish: #4 finish 420 Stainless: Hardness: 44/50 Rockwell C Parallelism: Within .001" TIR Thickness: ±.003" Custom polish: #4 finish Expansion Factor (TCE): 11.6 630 Stainless: Hardness: 44/50 Rockwell C Parallelism: Within .001" TIR Thickness: ±.003" Custom polish: #6 finish Expansion Factor (TCE): 11.6 S-4 Stainless: Hardness: 44/50 Rockwell C Parallelism: Within .001" TIR Thickness: ±.003" Custom polish: #6 finish Expansion Factor (TCE): 16.2