Loading patent…
AssigneeDigital Equipment Corporation
InventorsJames C. K. Lee, Arshad Ahmad, Myrna E. Castro, Francisca Tung
Estimating the term…
A very fine line three-dimensional package is constructed without lamination during construction of the signal core. Construction of the signal core employs a method of line and hole formation and planarization without drilling, and avoids imposing excessive stress on the package during its assembly. In forming the three-dimensional structure, a power core which may comprise a single or multiple layers is manufactured in the conventional method using a very high dielectric constant material. A signal core is on both sides of the power core, using a sequential approach with a low dielectric constant material. The method comprises utilizing photoresist techniques to define the regions of horizontal lines running parallel to the surface of the power core substrate and vertical posts running perpendicular to the surface of the power core, as each layer of lines and posts is established. After metallization of the lines and posts, the dielectric is flowed over the pattern of lines and posts to form a finished layer of the signal core. The sequence is repeated as many times as necessary to build up the required wiring pattern in the signal core. Layers of signal core are built up sequentially on both sides of the power core by alternating between depositing conducting metal and flowing and solidifying a dielectric in place.
A method of making a multilayer circuit board including a power core and signal cores carried on both major surfaces of said power core, said method of making said circuit board including the steps of:
A double-sided high density multilayer fine line circuit board comprising a power core layer including at least a highly conductive ground plane and a signal core formed on each side of said power core layer, each said signal core including patterned layers of conductive lines extending horizontally over and parallel to said ground plane and electrically communicating with said ground plane through conductive posts extending vertically above and perpendicular to said ground plane, said conductive posts overlying portions of said conductive lines and extending vertically between said patterned layers of conductive lines or to a surface of said signal core, said conductive lines and posts being electrically isolated by a flowable nonconducting material of a relatively low dielectric constant flowed into place over said conductive lines and posts, then solidified, whereby said conductive lines and posts are electrically isolated, said conductive posts being 0.003 inch or less in diameter.
Dependencies are inferred from the claim text.