Methods for manufacture of multilayer circuit boards
AssigneeFoster-Miller, Inc.
InventorsJames M. Burnett, Richard J. Mathisen
Life of this patent
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Abstract
The invention is for the formation of multilayer circuit boards where layers are formed sequentially using selective plating techniques and imaging of dielectric materials to achieve fine line resolution and interconnections between circuits. The invention permits the sequential formation of multilayers of higher density using imaging techniques. The method may also be used in single-sided and double-sided circuit board fabrication and for inner layers used in multilayer circuit boards.
Claims31
A process for the formation of a circuit board having two or more layers of circuitry, said process comprising the steps of applying a permanent dielectric coating over a substrate, said permanent dielectric coating having imaged openings defining interconnections, selectively plating metal into said imaged openings to form interconnections, applying a sacrificial coating over the layer comprising the permanent dielectric coating and metallized interconnections, said sacrificial coating having imaged openings defining a circuit pattern, catalyzing surfaces of underlying material where bared and the surfaces of said sacrificial coating with an electroless plating catalyst, replacing said sacrificial coating with a second coating having imaged openings corresponding to those formed in the sacrificial coating, and electrolessly plating metal into said openings for interconnections in said dielectric coating and onto catalyzed surfaces, whereby, when plated, there is formed a second circuit in electrical contact with said first substrate, and whereby areas between circuit lines are free of catalyst.
The process of claim 14 where said sacrificial coating is developable in weak base solution.
Dependencies are inferred from the claim text.