Method for closing holes in ceramic substrates

A method for closing holes in a ceramic substrate comprising the steps of:

• providing a ceramic substrate comprising at least one hole therethrough, said substrate melting at a first temperature;
• filling said hole in said substrate with a paste consisting essentially of a ceramic sealing material which melts at a second temperature that is less than said first temperature at which said ceramic substrate melts, a ceramic stabilizing material which melts at a third temperature that is greater than said second temperature at which said ceramic sealing material melts, and an organic carrier for suspending said ceramic sealing material and said ceramic stabilizing material together in order to form said paste;
• heating said ceramic substrate and said paste to a burn-off temperature sufficient to burn off the organic carrier within said paste, said burn-off temperature being less than said second temperature at which said ceramic sealing material melts;
• maintaining the ceramic substrate and said paste at said burn-off temperature for a burn-off time period sufficient to burn off substantially all of the organic carrier from said paste;
• additionally heating said ceramic substrate and said paste to said second temperature in the range of about 490.degree. C. to 530.degree. C. in order to melt the ceramic sealing material and thereby form molten ceramic sealing material;
• maintaining the ceramic substrate at said second temperature for a sealing time period sufficient to allow the molten ceramic sealing material to fill interstices in the hole;
• and
• cooling the ceramic substrate in order to cause said molten ceramic sealing material to solidify within said hole.