Method of forming recessed patterns in insulating substrates

A method of making a recessed pattern in an insulating substrate, which includes forming a recessed pattern in a ceramic green sheet for use in a multilayer ceramic module, comprising the steps of:

• providing a sculptured plastic tape mold which comprises a floor and a plurality of protrusions on and extending above the floor;
• casting a ceramic slurry into the mold such that the slurry contacts the floor and the protrusions;
• and
• drying the slurry so as to produce a ceramic green sheet with a recessed pattern that replicates the shapes of the protrusions.

A method of forming a recessed pattern of openings in a top major surface of a ceramic green sheet suitable for firing into a multilayer ceramic package with a fully inlaid, firmly bonded metallurgy filled into the recessed pattern, comprising, in sequence, the steps of:

• providing a sculptured plastic tape mold which comprises a planar floor, a pair of planar sidewalls adjacent to and extending perpendicularly above opposite sides of the floor, a plurality of vertically disposed cylindrical protrusions on and extending above the floor, and a plurality of horizontally disposed rectangular protrusions on and extending above the floor with flat top surfaces positioned in parallel with the floor and located beneath the top surfaces of the cylindrical protrusions and the sidewalls;
• casting a ceramic slurry into the mold such that the slurry is contained by the sidewalls and forms a uniform voidless layer with a top major surface against the floor, covers the floor and the rectangular protrusions, and surrounds and partially covers the cylindrical protrusions;
• heating the slurry so as to dry the slurry into a flexible ceramic green sheet with a recessed pattern in the top major surface having a plurality of horizontal trenches partially through the thickness of the sheet which replicate the shapes of the rectangular protrusions and a plurality of vertical vias completely though the thickness of the sheet which replicate the shapes of the cylindrical protrusions;
• and
• removing the mold from the recessed pattern without disturbing the shapes of the trenches and the vias.

A method of forming a recessed pattern in an insulating substrate for use in a multilayer ceramic module, comprising the steps of:

• providing a mold with a protrusion;
• casting a ceramic slurry into the mold;
• solidifying the slurry into a ceramic green sheet;
• firing the ceramic green sheet before removing the ceramic green sheet from the mold, thereby transforming the ceramic green sheet into a rigid ceramic substrate;
• and
• removing the rigid ceramic substrate from the mold, said substrate containing a recessed pattern shaped by the protrusion and adapted to be filled with a conductor.

A method of forming a conductive pattern in a rigid ceramic substrate for use in a multilayer ceramic module, comprising the steps of:

• providing a mold which comprises a floor and a plurality of protrusions on and extending above the floor;
• casting a ceramic slurry into the mold such that the slurry contacts the floor and the protrusions;
• drying the slurry so as to produce a ceramic green sheet with a recessed pattern that replicates the shapes of the protrusions;
• firing the ceramic green sheet before removing the ceramic green sheet from the mold so as to form a rigid ceramic substrate with the recessed pattern;
• removing the rigid ceramic substrate from the mold;
• and then
• filling the recessed pattern of the rigid ceramic substrate with a conductor.

A method of making a conductive pattern in the top major surface of a rigid ceramic substrate, comprising the following steps in the sequence set forth:

• providing a mold which comprises a planar floor, a pair of planar sidewalls adjacent to and extending perpendicularly above opposite sides of the floor, a plurality of vertically disposed cylindrical protrusions on and extending above the floor, and a plurality of horizontally disposed rectangular protrusions on and extending above the floor with flat top surfaces positioned in parallel with the floor and located beneath the top surfaces of the cylindrical protrusions and the sidewalls;
• pouring a ceramic slurry into the mold such that the slurry is contained by the sidewalls and forms a uniform voidless layer with a top major surface against the floor, covers the floor and the rectangular protrusions, and surrounds and partially covers the cylindrical protrusions;
• heating the slurry so as to dry the slurry into a flexible ceramic green sheet with a recessed pattern in the top major surface having a plurality of horizontal trenches partially through the thickness of the sheet which replicate the shapes of the rectangular protrusions and a plurality of vertical vias completely though the thickness of the sheet which replicate the shapes of the cylindrical protrusions;
• firing the ceramic green sheet before removing the ceramic green sheet from the mold so as to form a rigid ceramic substrate and removing the rigid ceramic substrate from the mold without disturbing the shapes of the trenches and the vias;
• and
• filling the trenches and vias with an electrical conductor to form a fully inlaid, firmly bonded metallurgical pattern of trenches and vias in the rigid ceramic substrate which replicate the shapes of the protrusions in the mold.