Process for the constrained sintering of a pseudo-symmetrically configured low temperature cofired ceramic structure

A method of making a low-temperature co-fired ceramic structure consisting essentially of an upper portion and a lower portion,

• wherein each portion comprises an assembly of one or more layers of primary tape and one or more layers of low k or high k glass-containing internal self-constraining tape, and wherein the self-constraining tape and primary tape maybe arrayed in unique combinations to provide symmetric and/or asymmetric z-axis placement and layer thickness arrangements to form practical co-fired ceramic circuit structures when the tapes are metallized with planar and interconnecting circuits, wherein the dielectric constant of the low k self-constraining tape is less than 8, the dielectric constant of the high k self-constraining tape is greater than 8, wherein each portion has z-axis symmetry with respect to the tape layers of the portion, wherein the structure, consisting of the upper and lower portions, has z-axis asymmetry with respect to the dielectric constant of the self-constraining tape layers, and wherein each self-constraining tape can independently provide a constraining pressure-less assisted sintering LTCC assembly with the primary tape, comprising the following steps:
• providing one or more layers of low k glass-containing internal self-constraining tape,
• providing one or more layers of high k glass-containing internal self-constraining tape,
• providing at least one layer of glass-containing primary tape,
• layering said internal self-constraining tapes and said primary tape(s) to form an upper portion and a lower portion,
• wherein each portion comprises one or more layers of low k self-constraining tape or high k glass-containing internal self-constraining tape, and wherein each portion does not contain both low k tape and high k tape,
• wherein each portion comprises at least one layer of glass-containing primary tape,
• wherein the dielectric constant of the low k self-constraining tape is less than 8, the dielectric constant of the high k self-constraining tape is greater than 8,
• wherein each portion has z-axis symmetry with respect to the tare layers of the portion, wherein the structure, consisting of the upper and lower portions, has z-axis asymmetry with respect to the dielectric constant of the self-constraining tape layers,
• and wherein each self-constraining tape can independently provide a self-constraining pressure-less assisted sintering LTCC assembly with the primary tape,
• and wherein, upon thermal processing, the glass of the self-constraining tapes initiates sintering to attain a rigid form before the onset of sintering of the primary tape, and wherein the internal self-constraining tapes and the primary tape are laminated to form a compositionally asymmetrical laminate
• and wherein the assembly is thermally processed producing a structure exhibiting an interactive suppression of x,y shrinkage.