Co-firing of magnetic and dielectric materials for fabricating composite assemblies for circulators and isolators

A method for making a composite magnetic-dielectric disc assembly, comprising:

• forming an unfired dielectric ceramic cylinder;
• forming a magnetic ceramic rod;
• pre-firing the magnetic ceramic rod;
• assembling the pre-fired magnetic ceramic rod coaxially inside the unfired dielectric ceramic cylinder to form a rod-and-cylinder assembly;
• shrinking the dielectric ceramic cylinder of the rod-and-cylinder assembly around the magnetic ceramic rod of the rod-and-cylinder assembly to form a joined rod-and-cylinder assembly, wherein the firing step is performed at a temperature lower than a temperature at which the magnetic ceramic rod is pre-fired to promote dimensional stability of the magnetic ceramic rod during firing of the rod-and-cylinder assembly;
• and
• slicing the joined rod-and-cylinder assembly to form at least one composite magnetic-dielectric disc assembly.

In a method for making a circulator or isolator, a method for making a composite magnetic-dielectric disc assembly, comprising:

• forming an unfired dielectric ceramic cylinder;
• forming a magnetic ceramic rod;
• pre-firing the magnetic ceramic rod;
• assembling the pre-fired magnetic ceramic rod coaxially inside the dielectric ceramic cylinder to form a rod-and-cylinder assembly;
• firing the rod-and-cylinder assembly to form a joined rod-and-cylinder assembly, wherein the firing step is performed at a temperature lower than a temperature at which the magnetic ceramic rod is pre-fired to promote dimensional stability of the magnetic ceramic rod during firing of the rod-and-cylinder assembly;
• and
• slicing the joined rod-and-cylinder assembly to form at least one composite magnetic-dielectric disc assembly.