Specifications

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- Another aspect about a snap grid is that it will make editing, movement of
tracks, and components easier to do because the board will eventually
expand in size.
- There are two types of grids in a PCB package that a developer in
electronics can choose from: a visible grid or a snap grid.
Design Equations for Printed Circuit Boards
The first design factor for printed circuit boards to discuss about is the conductor
capacitance. The conductor capacitance is necessary because it will tell the
designer how much electrical energy is stored for a given potential. Finding the
capacitance is easy to figure out once you are given the thickness of the
conductor, the conductor width, and the distance between conductors. To attain
the value of the dielectric constant for the substrate that can be looked up in a
table with other materials.
Conductor Capacitance
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k = substrate dielectric constant
a = thickness of the conductor
b = conductor width (given in inches)
d = distance between conductors (given in inches)
Another concept that is prevalent in printed circuit board design for
manufacturers is conductor resistance. Conductor resistance is affected by the
thickness of a wire, length, temperature, and the conductivity of the base material
being used. The thickness of the wire is basically the cross sectional area of the
substance being fabricated. Area in this case is length of the material times the
width of the material. In order to determine the conductor resistance the only
specification that a designer needs to take into consideration is the conductor
width.
Conductor Resistance
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W = conductor width (given in inches)
The characteristic impedance of an electric structure is the ratio of amplitudes of
voltage and current waves moving along an infinitely long line. Characteristic
impedance comes into view as resistance due to them having the same SI units.
The power of the infinitely long line is accounted for since it is being generated
on one end of the line and transmitted through the line as well. For a printed
circuit board this is the formula used to determine the characteristic impedance of
an infinitely long line.