Usually the multilayer circuit board pcb circuit board except that , in addition to a multilayer circuit board pcb top and bottom , there are several intermediate layers , these intermediate layers may be a signal layer (mid layer), can also be internal power / ground plane (internal plane).
1 , the middle layer of the multilayer pcb circuit boards to create and set
The role of the middle layer of the bottom and the top is similar to the sample , but can not place the component . Internal power / ground plane layer is a layer of copper, may be divided into isolated regions, each region has a copper film with a specific power / ground pad or via a network by Unicom, its role is to simplify the power supply and the bottom grid connection, reduce line impedance, enhanced anti-jamming capability of the power supply network.
Create a method in the middle layer, and the layer is provided by a dedicated management tools ---- layer stack manager ( Layer Stack Manager ) , the specific operation to select the menu command [ design] / [ Layer Stack Manager] in the pop-up dialogue layer frame can easily set needed. In four-layer board , for example, two intermediate layers are provided for the power level (power means ) and a ground layer (gnd shown) connected to the network number is not set. Notably , for the four-layer board, the general approach is to select layer signal layer, power supply layer, ground, signal layers. A better way is to select layer signal layer, power supply layer, a signal layer, the formation.
2 , segmentation within the multilayer circuit board layers
Planning and set up an intermediate layer , the component layout is complete, you can split the electrical layer , protel dxp 2004 split within the dielectric layer is simpler than previous versions and more convenient . Specific methods of operation , select the menu command [ design] / [ color] pcb level or press the shortcut key letter l, to bring up the [ board ] panel layers and colors , so you can turn off the unwanted layers ( such as top, bottom , other intermediate layers ) to display the desired separation layer to a power supply layer , for example, the power supply layer [ tick ] is displayed on the pcb to the interface "power" level . Back pcb interface, select the menu command [ place ] / [ straight ] or shortcuts p / l, recall drawing a line tool , select to split the power pads ( eg vcc), to form a closed surface , double closed box pop-up dialog box , select the network split out of this closed area is connected (vcc). A good split within the layer has been completed, similar to other power networks (vdd) operation.
