05-02-2013, 10:47 AM
PCB Board Design
[attachment=49635]
What is a PCB board
Printed Circuit Boards are primarily an insulating
material used as base, into which conductive
strips are printed
The base material is generally fiberglass, and the
conductive connections are generally copper and
are made through an etching process
The main PCB board is called the motherboard,
the smaller attachment PCB boards are called
daughter boards or daughter cards
What is PCB Board Design
PCB board design defines the electrical pathways
between components
It is derived from a schematic representation of
the circuit
When it is derived, or imported from a schematic
design, it translates the schematic symbols and
libraries into physical components and
connections
PCB Design Layers
A PCB design package allows the designer to
define and design on multiple layers
Many of these are physical layers such as:
• Signal Layer
• Power plane Layer
• Mechanical Layer
And some are special layers such as:
• Solder & Paste Mask Layers
• Silkscreen or Top Overlay Layers
• Drill guides
• Keep-out Layer
And some CAD specific display-only layers:
• Ratsnest layer
• DRC Errors
Internal Layers
Internal Layers are generally used for Power
Planes
They are drawn in the negative, in other words
tracks placed on this layer represent the void
A signal name such as VCC or GND can be
assigned to an Internal Plane and the CAD tool
will automatically connect pads to the plane,
greatly simplifying PCB routing
Internal planes can also be split into sub planes or
split planes
Mechanical & Keepout Layers
Mechanical Layers are special in that they can be
added or viewed in any layer
Used to provide drill and cut-out guides during
the manufacturing process
Keepout layers generally follow the mechanical
layer to indicate to the CAD tool an area should
not be routed over. This is useful as an autorouting
constraint.
[attachment=49635]
What is a PCB board
Printed Circuit Boards are primarily an insulating
material used as base, into which conductive
strips are printed
The base material is generally fiberglass, and the
conductive connections are generally copper and
are made through an etching process
The main PCB board is called the motherboard,
the smaller attachment PCB boards are called
daughter boards or daughter cards
What is PCB Board Design
PCB board design defines the electrical pathways
between components
It is derived from a schematic representation of
the circuit
When it is derived, or imported from a schematic
design, it translates the schematic symbols and
libraries into physical components and
connections
PCB Design Layers
A PCB design package allows the designer to
define and design on multiple layers
Many of these are physical layers such as:
• Signal Layer
• Power plane Layer
• Mechanical Layer
And some are special layers such as:
• Solder & Paste Mask Layers
• Silkscreen or Top Overlay Layers
• Drill guides
• Keep-out Layer
And some CAD specific display-only layers:
• Ratsnest layer
• DRC Errors
Internal Layers
Internal Layers are generally used for Power
Planes
They are drawn in the negative, in other words
tracks placed on this layer represent the void
A signal name such as VCC or GND can be
assigned to an Internal Plane and the CAD tool
will automatically connect pads to the plane,
greatly simplifying PCB routing
Internal planes can also be split into sub planes or
split planes
Mechanical & Keepout Layers
Mechanical Layers are special in that they can be
added or viewed in any layer
Used to provide drill and cut-out guides during
the manufacturing process
Keepout layers generally follow the mechanical
layer to indicate to the CAD tool an area should
not be routed over. This is useful as an autorouting
constraint.