Electrical insulation testing of thin base material, for multilayer printed circuit board, applies voltage avoiding breakdown, then breakdown current measurement

摘要

Edges of the copper layers (1, 2) are made smooth and uniform. Testing establishes adequate electrical resistance between layers, using a test voltage lower than the insulating layer breakdown voltage. Preferred Features: A subsequent test establishes the current flow resulting from breakdown of the insulating layer (3). Smooth edges are first produced by a milling or sawing process. Testing employs DC voltages. For the insulating base and intermediate layers (4/5, 5/6) of the multilayer circuit board (M), identical material of the same thickness is used.