Patent ID: 6309692
Filing Date: 2001-10-30
Classification: B01D,B05C,B05D

Abstract:
A method of coating, comprising:placing a substrate onto a support surface having a flatness of 2 .mu.m or less, and wherein said support surface has a plurality of holes;introducing a vacuum into said holes to attract said substrate into close contact with said support surface in order to eliminate deformations of said substrate;determining a capillary number as a function of a viscosity of a coating material, a surface tension of said coating material, and a coating speed of a coating die relative to said substrate by the equation:Ca=.mu.U/s,wherein Ca=said capillary number, .mu.=said viscosity (Pa.multidot.S), U=said coating speed (m/s), and s=said surface tension (N/m), andwherein said determining said capillary number includes selecting said capillary number to be 0.1 or less;determining a corresponding non-dimensional minimum coating thickness as a function of said capillary number;determining a reference gap between said coating die and said substrate as a function of said corresponding non-dimensional coating thickness and a target thickness of said coating material by the equation:H=h/t,wherein H=said reference gap, h=said target thickness of said coating material, and t=said corresponding non-dimensional coating thickness;moving horizontally said coating die relative to said substrate;maintaining said reference gap between said coating die and a reference surface of said substrate; andapplying said coating material onto said substrate by downwardly discharging said coating material from said coating die.