文档介绍：APPLICATION NOTES
INSIDE
Designing Balanced Printed
Benefits of
balanced designs Circuit Boards
Designers can be tempted to design printed circuit boards (PCBs) with an odd number of layers.
Balancing layer counts If the additional layer is not needed for routing, why use it? Won’t eliminating the extra layer
to avoid warp
minimize board thickness? If the board has one less layer, the cost should be lower...shouldn’t it?
Modifying designs to But, on occasion, adding a layer can help reduce costs.
achieve even layer counts
The stackup of layers in the board can be handled in two different ways: core construction or
foil construction (See Figure 1).
Figure 1 -
Core vs Foil Construction foil
prepreg core prepreg
foil
Core Construction Foil Construction
Merix Corporation Core construction attaches the conductive layers of the board to a core material. Foil construction
Interconnect Solutions attaches all conductive layers except the external layers to a core material. The external conductive
1521 Poplar Lane
. Box 3000 layers of the board for foil construction are added using sheets of copper foil.
Forest Grove, Oregon 97116 All of the layers are bonded together using a prepreg at the multilayer lamination process.
phone
fax Core e to the PCB fabricator with copper laminated on both sides. Since each c