Multi-substrates are made by stacking two or more circuits on top of each other, and they have reliable pre-set interconnections.
Since drilling and plating have been completed before all the layers are rolled together, this technique violates the traditional manufacturing process from the beginning.
The two innermost layers are composed of traditional double panels, while the outer layers are different, they are composed of independent single panels.
Before rolling, the inner substrate will be drilled, through-hole plating, pattern transfer, development and etching.
The outer layer to be drilled is the signal layer, which is plated through in such a way that a balanced copper ring is formed on the inner edge of the through hole.
The layers are then rolled together to form a multi-substrate, which can be interconnected (between components) using wave soldering.