Embedded capacitance PCBs are finding their way into applications in high speed multilayer PCBs, servers, routers, back panels, military, and aerospace, as well as graphics processing. Embedded capacitance technology is also economical in PCBs with >4 SMT by-pass capacitors per square inch.

The advantages are plentiful. Improved PCB performance; reduced "noise"; reduced board area; reduced or eliminated discrete SMT capacitors; reduced solder joints; reduced via holes are among the advantages. An embedded capacitance PCB essentially has an extremely thin dielectric between copper layers. Typically this thin layer is used between a power and ground plane in a multilayer PCB.

Cambridge America has partnered with a board manufacturer who uses 3M Embedded Capacitance Material that is 14 microns thick made of a ceramic filled epoxy and has a capacitance value of 6.4nF/In2.

Since design tools are not readily available for using embedded capacitance, Cambridge America suggests a prudent strategy for those interested in trying the concept:

• Select Existing PCB Design
• High Capacitor count
• Unresolved Hi Frequency Noise Problem
• 4Layer (2,3 Power/Ground)
• Submit Design to Cambridge America, who will determine viability of candidate PCB with 3M and our board fabricator.
• Build Board with no changes except 3M Embedded Capacitance material specified for layers 2 and 3.
• Assemble Board without SMT capacitors originally designed into board.
• Test
• Determine effectiveness, savings