Self-constrained low temperature glass-ceramic unfired tape for microelectronics and methods for making and using the same

DETAILED DESCRIPTION OF THE INVENTION As previously explained, the electronic module industry has not yet found a way to address the shrinkage issue in an economical and trouble-free way.
An ideal solution would be a single non-shrink ceramic tape material that would process like regular LTCC tape in processing steps such as stacking, laminating, printing and via filling.
The advantage would be greater yet if the tape were to co-fire or sinter simultaneously with metallization at standard LTCC temperatures.
Further, a single tape versatile enough to address issues such as low dielectric loss at high frequencies and the integration of passive and active components, while eliminating dimensional uncertainty as the panel size increases, would also be desirable.
The present invention accomplishes these objectives.
Specifically, a monolithic green body tape is provided which may be used for the construction of multilayered ceramic structures that contain embedded conductor patterns for microelectronic applications.
As will be described in more detail below, this green body tape processes like traditional single layer LTCC tape, yet maintains its geometrical x-y dimensions after firing due to the fact that the tape itself is self-constrained, thereby alleviating several problems facing currently practiced externally constrained sintering manufacturing techniques.
For example, the self-constrained green body tape according to the invention allows for improved planarity of the resulting structures formed therefrom, and may be used in the construction of ceramic multilayer circuits and individual modules composed of conventional thick film metallizations, including surface conductors, surface resistors, surface dielectric masks, imbedded passive/active components and cavities within.
The improved tape according to the present invention also enhances the properties of the metal conductive patterns printed therein or thereon, including solderability, adhesion, conductivity, and resistivity.
Green Body Tape The monolithic green body tape for use in low temperature co-firing may be referred to as "self-constrained" because, as will be explained in further detail below, essentially no shrinkage of the tape occurs in the x-y direction upon sintering, yet no constraint is needed to achieve this objective