An RF coupling device is formed on a hybrid printed circuit which avoids discrete capacitors or resistors. The substrate is formed of refractory dielectric sheet, such as alumina or another ceramic. A printed conductor is printed on the front surface of the substrate, and has one or more broadened portions formed on it as capacitor plates. One or more printed resistors are in contact with the printed conductor. A ground pad is printed in a predetermined pattern onto a portion of the reverse surface of the substrate at selected locations. The ground pad has one or more portions that are in registry with the capacitor plates and serve as grounded plates for the capacitors. One or more inductors can be printed onto the substrate in a meander pattern and in contact with the remainder of the printed conductor. The printed circuit receives one or more RF transformers whose leads can be soldered to the printed circuit. RF coupling devices such as a filter, a directional coupler, a two way signal splitter, and a four-way signal splitter can be constructed according to this technique. The capacitors formed as described are generally associated with high Q values which help reduce insertion loss and also increase frequency bandwidth.

The invention relates to circuit boards consisting of a flat core plate, 1 to 5 mm thick, of metallic material, graphite or electrically conductive carbon with a coating, 10 to 80 .mu.m thick, of electroplated aluminum eloxal and, optionally, an intermediate layer of copper or silver, 0.1 to 2 .mu.m thick. On the electroplated Al eloxal layer, a conductor run structure generated by an additive or subtractive technique may be present. The highly heat-conducting and mechanically strong circuit boards find application in electronics.

An improved multilayered circuit is disclosed comprising a molybdenum substrate with alternating layers of dielectric and conducting thick film materials deposited thereon. The molybdenum substrate has the advantages of being its own chassis, having a coefficient of thermal expansion that is well matched to the thick film materials and component ceramic chip carriers, and having a high thermal conductivity so as to act as its own heat sink.

High heat-conductive, thick film multilayered circuit board for high speed signal transmission in a high frequency region, the circuit board comprising: a substrate having high heat conductivity; an oxidized layer formed on a surface of said substrate; an electrically conductive layer formed of a printed paste containing therein crystallized glass; and an insulating layer formed of a printed insulating paste comprised of crystallized glass as a principal constitutent, wherein at least one of said conductive layer and at least one of said insulating layer are alternately disposed by printing on the oxidized layer of said substrate, and said conductive and insulating layers have been heated to form solid layers. The substrate is AlN, SiC/BeO, SiC, Cu/W and/or ZrB.sub.2 having a heat conductively of 40-140 W/m.multidot.k at room temperature. The layers have high adhesion strength to the substrate and the insulating layer has a low dielectric constant.