Capacitive/resistive devices, organic dielectric laminates and printed wiring boards incorporating such devices, and methods of making thereof
A capacitive/resistive device provides both resistive and capacitive functions. The capacitive/resistive device may be embedded within a layer of a printed wiring board. Embedding the capacitive/resistive device conserves board surface real estate, and reduces the number of solder connections, thereby increasing reliability. Conserves board surface real estate, and reduces the number of solder connections, thereby increasing reliability.
1. A laminate structure comprising a capacitive/resistive device, comprising:
a first metal foil;
a dielectric disposed over the first metal foil;
a second metal foil;
a resistive layer having two opposing surfaces and disposed over the second metal foil;
wherein one surface of the resistive layer contacts the dielectric layer;
a first electrode formed by etching the first metal foil;
a second electrode and a conductive trace separately formed by etching the second metal foil;
the first electrode, the dielectric layer, and the second electrode forming a capacitor;
wherein at least a portion of the opposite surface of the resistive layer contacts both the second electrode and the conductive trace, thereby forming a resistor element;
wherein the resistor element contacts the dielectric layer,
wherein the dielectric comprises a polymer filled with a high dielectric constant powder phase;
wherein the dielectric layer is 8-25 micrometers in thickness with a dielectric constant of between 5 and 40, and
wherein the dialectic layer is formed by casting a dielectric slurry comprising the polymer, a solvent, and the high dielectric constant powder phase over the first metal foil, the second metal foil, or over the first metal foil and the second metal foil; and
wherein the capacitor and resistor are laminated to, and embedded within, at least two printed wiring board dielectric laminate layers.
2. The capacitive/resistive device of claim 1 , wherein the resistive layer is disposed between the dielectric and the second electrode.
3. The capacitive/resistive device of claim 1 wherein said dielectric comprises polyimide polymer.
4. The capacitive/resistive device of claim 1 wherein said high dielectric constant powder phase is selected from barium titanate, barium strontium titanate, lead zirconate titanate, lead lanthanium zirconate titanate, lead magnesium titanate, calcium copper titanate, and mixtures thereof.
5. A printed wiring board, comprising:
at least one laminate structure according to claim 1 ; and
at least one IC device disposed on a top surface of the printed wiring board,
wherein the IC device is electrically coupled to the capacitive/resistive device.