6.10 Glossary
Asymmetric stripline (Section 6.6): Traces between conducting planes that are not centered.
Centered stripline (Section 6.4): Traces that are on an inner layer of a circuit board that are evenly positioned between two conducting surfaces.
Clad laminate (Section 6.8): A glass epoxy layer with copper bonded to one or both surfaces.
Core (Section 6.1): The laminate structure used at the center of a circuit board. It is often glass epoxy with thin layers of copper bonded to the two surfaces.
Layer stack (Section 6.8): The set of laminates that make up a circuit board.
Layup (Section 6.8): The layers in their right order that make up a final circuit board.
Manhattan (Section 6.7): The xy pattern of traces similar to avenues and streets in the New York City.
Maxwell's equations (Section 6.2): A set of differential equations that describes all field phenomena in electricity.
Oz copper: A thickness of copper. When two pounds of copper are plated on 1 ft2 of material, the copper thickness is 2.7 mil. This is called 2-oz copper. The final thickness can change during manufacturing.
Prepreg (Section 6.8): Partially cured glass epoxy. When the layer stack is heated under pressure, the epoxy cures bonding laminate surfaces together.
Thieving (Section 6.8): In plating, areas with less copper are apt to receive an excess of plating. Adding pads of copper to a surface tends to even out the plating. The pads steal plating material from nearby points on the board.
Notes
1 IPC stands for Institute of Printed Circuits. It is a global organization headquartered in Lincolnwood, IL, USA. It maintains specifications and procedures, as they relate to circuit board manufacture. The organization also holds classes on various aspects of board manufacture.
2 ANSI stands for American National Standards Association. See www.ansi.org.
3 The tradition of connecting conductors to form circuits is not an easy one to change. We are used to the idea of connecting traces as transmission lines on the board but at the IC package the concept often stops. The logic connections and the ground connections are often widely separated. In fast logic, this causes reflections (delays) and radiation. Ideally, the characteristic impedance of every transmission line should be controlled up to the die itself.