Saturday, January 22, 2011
【 Weak current College 】 printed circuit board set using constraint management to simplify 】
Reduce PCB design cycle has become a general problem. Designers are also faced with circuit board technology is rapidly changing, such as processing at an increasing rate increasingly complex, IC packaging, thus this is the simplest design processes of PCB design added complexity. Therefore, in order to improve the efficiency of the design process, constraint management tools has increasingly become indispensable.
Although the market existing CAD Kit visible to constraint management tool, but many designers have not been able to take full advantage of all the potential of these tools. Use constraints management tools, the key is understanding the software capabilities and features, and how it can be integrated with the entire design flow. In the design, the effective use of constraints and rules, you can shorten the design cycle, improving existing or under development technology to upgrade capacity and delivery in the future design reuse design trouble.
Constraint management concepts easy to understand: you only need to set up constraints and rules, and then design the layout process. Moreover, the fact that at some point, it is the case for direct implementation. But once the engineers in the design environment access restrictions and regulations to enter into stage, you'll find that not everything is as envisaged.
From exploring the available capacity and functional aspects are very important. Right text lists some important principles, designers should keep in mind.
1. understand what your design related, as well as information on how to design a stage of the process is passed to the next stage. Assign the differential signal is a good habit. Ideally, you want the difference signal is assigned as part of the top-down approach; therefore, you must ensure that in principle diagram or constraint management tools can achieve the above requirements, and then send it to the layout.
2. information for proper archiving management to ensure that in future design can take advantage of this information. Establishing a storage proven implementation and can be used by the design team members share the implementation of the system, you can save time and help to shorten the design cycle of the overall project. Many CAD system is structured, so the design data will be saved in a folder, the folder that contains the include in the design of the constraints and templates, all of the information. In the project folder smart management of your data so that you can later design to use some specific data again, you can easily access the data.
3. the use of constraint management tool flexibility. This software can be used in the design cycle at any point in the constraint before or after the move, generate reports and records the change. All this reduces rework and helps to maintain design integrity.
4. ensure you have the choice of tools for analyzing rendering topology, incentive and a single set, or create a unique composite segment plates laminated.
Using derived from spreadsheet data manual calibration value and then attempt to use these data in the schematics and layout tools passed back and forth between the constraints when compared to the practice management system to become more efficient in the center of the application.
The PCB design process at various stages for constraint management
Should not be
1. the excessive constraint networks. It will give the signal to wiring. In extreme cases, especially when you need to add an extra layer, to overcome similar timing or spacing requirements of appropriate wiring problems, design time may be extended several times.
2. in the design process in the Middle set constraints. It is important to do at the start of a task. If you select in a later stage set constraints for the signal, you may have to restart on PCB wiring, it will waste a lot of time. In the layout and wiring, should plan and handle the relevant policies to ensure this happens.
3. forget critical network. If the use of constraint management system setting constraints, in complete critical network cabling for the entire PCB wiring without losing the wise — especially when you set the signal length or delay constraints. Otherwise, when the signal length policy implementation, you no longer have the room for its extension.
4. unable to interact with the wiring tools and cannot introduce data reporting systems of management tools. Setting of constraints and rules, of course, very good, but if you must assign each a query by hand, will make the use of constraint management tools effectively nullified.
5. application and design rules are not consistent. Designers to meet manufacturing guidelines-based on the PCB wiring. If no constraint manages and where to etch effect set appropriate signal spacing or in order to minimize cross interference with good layer stack, together with design guidelines, it will cause problems. Some tools allow your design freely any constraint applied to critical network; others are in the design cycle of the application at any stage of your design rules, so they are strengthened. Either way, when you use constraints, be sure not to violate the rules of good design.