Radio frequency system (250) which includes a first and second sub-assembly (100, 200), each formed of a plurality of layers of conductive material (504, 508, 516) disposed on a substrate (102) and arranged in a stack. The stacked layers form signal processing components (108, 110) and at least one peripheral wall (104, 204) surrounding a walled area (118, 218) of each substrate. The second sub-assembly is positioned on the first sub-assembly with a first walled area of a first substrate aligned with a second walled area of a second substrate.