印刷电路板设计大全 Complete PCB Design Using OrCad Capture and Layout_Part5

Figure 9-15 Final BOM listing with all footprints assigned.

ou can also use the Find tool to automatically select a part or parts of a certain type. To use

Figure 9-16 Using the Find tool to locate parts.

Grouping related components

Figure 9-17 Using the Property Editor to assign components to groups.

To view group information for the entire design go to the Project Manager and select Design icon. Right click and select Part Manager from the pop-up (or select Part Figure 9-18 Using the Part Manager to view all groups.

Figure 9-19 The Confi gure Part Property Display dialog box.

ou can also add the COMPGROUP property to the bill of materials listing by adding “\tCOMPGROUP” to the Header: list and “\t{COMPGROUP}” to the Combined Property

Figure 9-20 Performing a design annotation.

Warning!

■ Do not perform another annotation after you have generated a Layout netlist or performed a back annotation from Layout (especially if you had Layout renumber the parts), because the project can become unsynchronized and produce very

peculiar, irreversible results! To read more about the annotation function, search

Figure 9-21 The Capture Design Rules Check dialog box.

Figure 9-22 Creating a circuit netlist for Layout from Capture.

Defi ning the board requirements

One of the fi rst steps in setting up a new board in Layout is to select a technology fi le, which requires deciding on a couple of design requirements up front. Choosing a technology fi le requires knowing what types of parts will be used in the design (packaging and assem-bly requirements), the number and type of layers required, and the trace width and spacing requirements. These considerations for the analog design example are discussed in the follow-

Figure 9-23 Layer stack-up for Example 1.

Figure 9-24 Using the AutoECO to begin a new PCB design in layout.

rst view you have of your new board will probably be a black background and part of a red square. Click the Zoom All button, so that you can see the entire design. Y ou should see something similar to Fig. 9-27.

Setting up the board

Making a board outline

rst step in laying out the board is to make the board outline and add mounting holes so that the boundaries of the board are known. First turn off the DRC box by toggling the

Figure 9-25 Example of the AutoECO Link Footprint error. Figure 9-26 Adding a footprint library to the AutoECO tool’s library list.

Figure 9-27 Initial view of the analog design.

Online DRC button, located on the toolbar. Then, draw a board outline: select the Obstacle tool, . Right click in the work space and select New from the pop-up, right click again, and select Properties to invoke the Edit Obstacle dialog box. Make sure the obstacle Board outline on the Global layer. Click OK.

Left click at point 0,0 to place the fi rst vertex. Left click to place each vertex of the board outline. Make the board outline about 2.0 ϫ 2.5 in. (2000 ϫ 2500 mils). Right click and select Finish from the pop-up after you have placed the fourth vertex.