Coating a heat curable liquid dielectric on a substrate

A method for coating a polymeric dielectric on a substrate, comprising the following steps in the sequences set forth:

• removing contaminants from the substrate that might otherwise substantially interfere with adhesion or curing of said polymeric dielectric on the substrate;
• heating the substrate to remove moisture that might otherwise substantially interfere with the adhesion or curing of said polymeric dielectric on the substrate;
• depositing a single coating of a liquid polymeric dielectric on the substrate before the substrate receives sufficient contaminants or absorbs sufficient moisture to substantially interfere with the adhesion or curing of the polymeric dielectric;
• and
• heating the liquid polymeric dielectric at most 15.degree. C. per minute to a cure temperature about 225.degree. C. but not exceeding 450.degree. C., thereby providing from the single coating a cured polymeric dielectric film at least 15 microns thick with a uniformity of less than 5 microns which adheres to the substrate.

A method for coating a polymeric dielectric on a substrate, comprising the following steps:

• removing contaminants from the substrate that might otherwise substantially interfere with adhesion or curing of the polymeric dielectric on the substrate;
• heating the substrate to remove moisture that might otherwise substantially interfere with the adhesion or curing of the polymeric dielectric on the substrate;
• curtain coating the substrate with a single coating of a heat curable liquid polymeric dielectric before the substrate receives sufficient contaminants or absorbs sufficient moisture to substantially interfere with the adhesion or curing of the polymer dielectric, said curtain coating including
• i) forcing the liquid polymeric dielectric through a slit in a dispenser spaced above the substrate onto the substrate, and
• ii) moving the substrate linearly with respect to the dispenser so that the liquid polymeric dielectric is deposited on the entire substrate;
• and
• heating the liquid polymer dielectric at most 15.degree. C. per minute to a cure temperature above 225.degree. C. but not exceeding 450.degree. C., thereby providing from the single coating a cured polymeric dielectric film at least 15 microns thick with a uniformity of less than 5 microns which adheres to the substrate.

A method for coating a polymeric dielectric on a substrate, comprising the following steps in the sequence set forth:

• removing contaminants from the substrate that might otherwise substantially interfere with adhesion or curing of the polymeric dielectric on the substrate;
• heating the substrate to remove moisture that might otherwise substantially interfere with the adhesion or curing of the polymeric dielectric on the substrate;
• depositing a single coating of a liquid polymeric dielectric on the substrate before the substrate receives sufficient contaminants or absorbs sufficient moisture to substantially interfere with the adhesion or curing of the polymeric dielectric;
• and
• heating the liquid polymeric dielectric at most 15.degree. C. per minute to a cure temperature about 170.degree. C. but not exceeding 450.degree. C., wherein the liquid polymeric dielectric is heated at least three different rates of temperature increase, a first rate being greater than a second rate, a third rate being greater than the first rate, thereby providing from the single coating a cured polymeric dielectric film at least 15 microns thick with a uniformity of less than 5 microns which adheres to the substrate.

A method for coating a polymeric dielectric on a substrate, comprising the following steps:

• removing contaminants from the substrate that might otherwise substantially interfere with adhesion or curing of the polymeric dielectric on the substrate;
• heating the substrate to remove moisture that might otherwise substantially interfere with the adhesion or curing of the polymeric dielectric on the substrate;
• curtain coating the substrate with a single coating of a heat curable liquid polymeric dielectric before the substrate receives sufficient contaminants or absorbs sufficient moisture to substantially interfere with the adhesion or curing of the polymeric dielectric, said curtain coating including
• i) forcing the liquid polymeric dielectric through a slit in a dispenser spaced above the substrate onto the substrate, and
• ii) moving the substrate linearly with respect to the dispenser so that the liquid polymeric dielectric is deposited on the entire substrate;
• and
• heating the liquid polymeric dielectric at most 15.degree. C. per minute to a cure temperature above 170.degree. C. but not exceeding 450.degree. C., wherein the liquid polymeric dielectric is heated at least three different rates of temperature increase, a first rate being greater than a second rate, a third rate being greater than the first rate, thereby providing from the single coating a cured polymeric dielectric film at least 15 microns thick with a uniformity of less than 5 microns which adheres to the substrate.