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US 3,932,932 AGranted
Method of making multilayer printed circuit board
AssigneeInternational Telephone and Telegraph Corporation
InventorDavid S. Goodman
Life of this patent
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Abstract
A method of making a multilayer board in which relatively thick ground and voltage planes are punched to form clearance holes. The planes are stacked with insulative layers, laminated and then drilled to produce through holes aligned with the clearance holes. The through holes are then plated-through. The method eliminates under-etch problems in thick ground and voltage planes which are capable of carrying high magnitudes of current.
Claims7
A method of making a multilayer printed circuit board comprising the steps of:
- providing at least two individual metal sheets of a thickness which, if etched, would have an under-etch condition;
- simultaneously punching a plurality of clearance holes in one of said sheets in a first predetermined pattern;
- simultaneously punching a plurality of clearance holes in the other of said sheets in a second predetermined pattern;
- filling said clearance holes with an insulative material;
- stacking said sheets with an insulative inner layer therebetween and insulative outer layers on the top and bottom thereof with at least some of the clearance holes in the respective sheets misaligned;
- laminating said stack of sheets and layers together to provide a unitary assembly;
- drilling holes vertically through said stack coaxial with the clearance holes in each of said sheets, said through holes having a diameter less than that of said clearance holes;
- and
- plating through said through holes with a conductive material.
6 more elements
Dependencies are inferred from the claim text.