Abstract:
A thin-film metal resistor (44) suitable for a multilayer printed circuit board (12), and a method for its fabrication. The resistor (44) generally has a multilayer construction, with the individual layers (34, 38) of the resistor (44) being self-aligned with each other so that a negative mutual inductance is produced that very nearly cancels out the self-inductance of each resistor layer (34, 38). As a result, the resistor (44) has a very low net parasitic inductance. In addition, the multilayer construction of the resistor (44) reduces the area of the circuit board (12) required to accommodate the resistor (44), and as a result reduces the problem of parasitic interactions with other circuit elements on other layers of the circuit board (12).
Abstract:
A method for manufacturing a microelectronic assembly to have aligned conductive regions and dielectric regions, for example, for producing integral capacitors (32), generally entails providing a substrate (10) with a first conductive layer (12), forming a dielectric layer (14) on the first conductive layer, and then forming a second conductive layer on the dielectric layer (16). A first region of the second conductive layer is then removed to expose a first region of the dielectric layer, which in turn is removed to expose a first region of the first conductive layer that is also removed. From this process, the first regions of the conductive and dielectric layers are each removed by using the overlying layer or layers as a mask, so that the remaining second regions of these layers are coextensive.
Abstract:
A method for manufacturing a microelectronic assembly to have a resistor (12) on a circuit board (10). The method entails applying a photosensitive dielectric to a substrate (18) to form a dielectric layer. The dielectric layer is photoimaged to polymerize a first portion (22). An electrically resistive film (14) is then applied to the dielectric layer and the dielectric layer is developed so that a portion of the resistive film remains over the second portion to form the resistor. A second dielectric layer (32) is then applied, photoimaged and developed to form openings (34). Terminations (16) can then be formed in the openings by known plating techniques. The resistive film is preferably a multilayer film that includes an electrically resistive layer, such as NiP, NiCr or other nickel alloy and a sacrificial backing such as a layer of copper.
Abstract:
Printed circuit boards (6) with integral high and low value resistors (2 and 4) are efficiently produced. The method of their manufacture entails applying a first layer of a low resistance material (8) onto a dielectric substrate (6) in a predetermined thickness and pattern. The pattern defines the electrical lengths and widths of low value resistors (2), as well as pairs of terminal electrode pads (28 and 30) for the high value resistors (4). A second layer of a high resistance material (18) is applied between and in contact with the top surfaces of the facing ends of each member of the terminal pad pairs (28 and 30). The fixed lengths, widths and thicknesses of the patterned high resistance material determine the values of the high value resistors. Conductive metal terminals are provided at the ends of the low value resistors and at the distal ends of the high value resistor pad to complete the resistors.
Abstract:
A method for fabricating circuit board conductors (24A & 24B) generally entails forming a metal layer (24) on a positive-acting photodielectric layer (22), and etching the metal layer to form at least two conductor traces (24A & 24B) that cover separate regions of the photodielectric layer while exposing a third region therebetween. The third region of the photodielectric layer is developed using the two traces as a photomask and removed. Thus, the traces are not only separated by a void (30) formed when the metal layer was etched, but are also separated by the opening (32) formed in the photodielectric layer by the removal of the third region of the photodielectric layer. A ferrite-filled polymer may also be deposited in the void and opening to form a ferrite core (34). Traces formed in accordance with the above may be formed as adjacent and parallel conductors or adjacent inductor windings of an integral inductor.
Abstract:
One of a plurality of capacitors embedded in a printed circuit structure includes a first electrode (415) overlaying a first substrate layer (505) of the printed circuit structure, a crystallized dielectric oxide core (405) overlaying the first electrode, a second electrode (615) overlying the crystallized dielectric oxide core, and a high temperature anti-oxidant layer (220) disposed between and contacting the crystallized dielectric oxide core and at least one of the first and second electrodes. The crystallized dielectric oxide core has a thickness that is less than 1 micron and has a capacitance density greater than 1000 pF/mm2. The material and thickness are the same for each of the plurality of capacitors. The crystallized dielectric oxide core may be isolated from crystallized dielectric oxide cores of all other capacitors of the plurality of capacitors.