A printed circuit is provided that is capable of operating at temperatures above 200.degree. C. A printed wiring board has a plating scheme of Tin plating over sulfamate nickel plated over copper. The materials are electroplated in the pattern of the desired circuit. The copper provides a conductive material for carrying electrical current. The sulfamate nickel is a ductile material that serves as a barrier between the copper and the Tin and is able to maintain its strength under temperatures of above 200.degree. C. The Tin is compatible with the new solder compound that is used to solder electrical components to the board. The solder compound is comprised of Tin and Silver. This solder has a higher initial melting point than traditional Tin/Lead solders but has a lower solder reflow temperature than conventional HMP solder compounds. This new solder is also stronger than conventional HMP solder and contains virtually no Lead component. A multilayer printed circuit is also provided that has a "Pads Only" design in which only the pads and short runs connecting to vias are allowed on the outer layers of the board. All power and signal runs are restricted to the inner layers of the board. This design has the advantage of protecting the runs in a high temperature environment and results in a more reliable assembly. The multilayer circuit uses the same plating scheme as in the above-described printed circuit.
This is a continuation of application Ser. No. 08/352,969, filed Dec. 9, 1994, which is a continuation of 08/000,948, filed on Jan. 5, 1993, now abandoned.
A thin film wiring scheme on a substrate. The thin film wiring scheme includes a plurality of chip connection pads at each of a first and second chip site on the substrate, a plurality of directional wiring lines interspersed between the chip connection pads at each of the first and second chip sites, at least one of the directional wiring lines being orthogonal to at least one of the other directional wiring lines at each of the first and second chip sites, and a plurality of chip site interconnection lines connecting directional wiring lines at the first chip site with the directional wiring lines at the second chip site.
Coupling components to an underlying substrate using a composition of a polymer and magnetic material particles. Upon applying the composition between the component and the printed circuit board, the composition may be subjected to a magnetic field to align the magnetic material particles into a conductive path between the component and the underlying substrate. At the same time the polymer-based material may be cured or otherwise solidified to affix the conductive path formed by the magnetic material particles.
Disclosed are methods of depositing electroless gold layers on a metal substrate using a catalytic palladium deposit. Such electroless gold layers have increased adhesion as compared to conventional electroless gold deposits.
Coupling components to an underlying substrate using a composition of a polymer and magnetic material particles. Upon applying the composition between the component and the printed circuit board, the composition may be subjected to a magnetic field to align the magnetic material particles into a conductive path between the component and the underlying substrate. At the same time the polymer-based material may be cured or otherwise solidified to affix the conductive path formed by the magnetic material particles.
Electronic components are bonded to an electronic circuit board with a lead-free solder. The bonded structure is cooled from a temperature close to the liquids temperature of the solder to a temperature close to the solids temperature of the solder at a first cooling rate of about 10 to 20.degree. C./second, followed by cooling the bonded structure to a temperature lower than the solids temperature of the solder at a second cooling rate of about 0.1 to less than 5.degree. C./second.
