In the field of PCB board design, we can see significant benefits brought by automation, especially when using automatic routing technology. The once time-consuming and tedious manual wiring can now be completed within a few hours using automated wiring tools. However, there are two ways of automatic routing in PCB board design: standard automatic routing and interactive automatic routing. We will discuss these two methods here to see which one is more suitable for your design needs. The wiring on printed circuit boards can be very interesting. Like playing video games, wire between pins while avoiding obstacles and jumping between layers. If you want to solve complex problems, becoming a PCB layout engineer is a good choice. But when it comes to following specific design rules and routing thousands of lines according to specific patterns and lengths, this enjoyment is greatly reduced. Designers need some help in this area, and this help comes from the automatic routing of PCB boards. The obvious benefit of using automatic routing tools is that all lines can be quickly routed. Equally important is that the calculation and processing speed of automatic routing tools is fast enough to handle many situations, which can slow down the designer’s progress when manually routing. The automatic routing tool can also handle embedded design rules in the layout database, saving time, and can set its own rules as needed. In addition, they can also perform many other tasks such as skew processing, trimming lines, and other line cleaning tasks. PCB board designers can choose between two automatic wiring methods. The first type is standard automatic routing, which is completely controlled by routing tools, although still constrained by design rules. The second type is interactive automatic routing, which allows designers to control the layout of circuits on the board.
**Some Details About Auto-Routing Technology**
1. An automated router that can route an entire board for you is known as a batch router. These tools have been around for a long time, and their functionality has significantly improved over the years. Previously, the results of a batch autorouter seemed like black-box magic, but now routing outcomes are predictable and repeatable.
2. These routers are highly configurable with various options to achieve the desired results. Today, most batch autorouters are directly integrated into their corresponding PCB layout design tools. This integration allows them to utilize the design rules and constraints already established for the board.
3. While this integration saves designers a considerable amount of time, routers also allow designers to modify these rules. Additionally, the operation and type of routing can be customized. Some available options include:
4. **Pre-Route**: This option routes only escape traces and vias for surface-mount components.
5. **Routing**: This encompasses routing the entire board in bulk or routing selected nets by executing a few runs of the auto-routing program.
6. **Purge**: This function removes loops and stubs that may have resulted from the auto-routing process.
7. **After Routing**: This option adds additional routing functions, such as shielding or test points.
8. Autorouters are valuable tools that save significant time, but it is important to recognize that the patterns they produce are generally orthogonal. While this is advantageous for some types of networks, it may not be ideal for routing tight bus traces, such as those used in memory routers.
9. To address this, we introduce the automatic interactive router. Modern PCB auto-routers offer many rules and properties that can be configured for a design.
10. **How Is Automatic Interactive Routing Different?**
11. Automatic interactive routing leverages the capabilities of the automatic routing engine while combining it with the expertise of the PCB board layout designer to guide routing paths. Designers are provided with a virtual canvas where they can set parameters and directions for routing.
12. A good example of automatic interactive routing in PCB design is organizing meshes into bundles for group manipulation. Using tools like the Constraint Manager in Allegro, nets can be selected by groups and assigned to bundles from the schematic or layout.
13. Once a bundle is created, routing properties can be applied, pins can be swapped, and routing layers adjusted as needed. Designers can then manipulate the bundles to achieve the required routing flow, navigating conflict areas around bundles such as connectors or tightly placed components.
14. After bundling, designers can straighten out twisted connections to the pins by repositioning bundles, swapping pins, or changing layers. Beams can be converted to regular etch traces to become part of the finished design database.
15. Automatic interactive routing allows designers to create tight routing patterns, required for DDR or other specific router technologies, while benefiting from the speed of an automatic router. Additionally, it can be used for high-speed tracking adjustments and other route-clearing tasks.
16. Both types of auto-routers are essential, depending on the routing requirements. For instance, automatic interactive routing is more efficient for routing DDR memory buses. However, when DDR routing is complete and there are still many loose wires to connect, a standard batch router becomes invaluable, especially for cleaning up routing.
17. Using a standard router is also very convenient for quickly transitioning to point-to-point routing, saving time and avoiding tedious manual routing work on PCB boards.
**Some Details About Auto-Routing Technology**
1. An automated router that can route an entire board for you is known as a batch router. These tools have been around for a long time, and their functionality has significantly improved over the years. Previously, the results of a batch autorouter seemed like black-box magic, but now routing outcomes are predictable and repeatable.
2. These routers are highly configurable with various options to achieve the desired results. Today, most batch autorouters are directly integrated into their corresponding PCB layout design tools. This integration allows them to utilize the design rules and constraints already established for the board.
3. While this integration saves designers a considerable amount of time, routers also allow designers to modify these rules. Additionally, the operation and type of routing can be customized. Some available options include:
4. **Pre-Route**: This option routes only escape traces and vias for surface-mount components.
5. **Routing**: This encompasses routing the entire board in bulk or routing selected nets by executing a few runs of the auto-routing program.
6. **Purge**: This function removes loops and stubs that may have resulted from the auto-routing process.
7. **After Routing**: This option adds additional routing functions, such as shielding or test points.
8. Autorouters are valuable tools that save significant time, but it is important to recognize that the patterns they produce are generally orthogonal. While this is advantageous for some types of networks, it may not be ideal for routing tight bus traces, such as those used in memory routers.
9. To address this, we introduce the automatic interactive router. Modern PCB auto-routers offer many rules and properties that can be configured for a design.
10. **How Is Automatic Interactive Routing Different?**
11. Automatic interactive routing leverages the capabilities of the automatic routing engine while combining it with the expertise of the PCB board layout designer to guide routing paths. Designers are provided with a virtual canvas where they can set parameters and directions for routing.
12. A good example of automatic interactive routing in PCB design is organizing meshes into bundles for group manipulation. Using tools like the Constraint Manager in Allegro, nets can be selected by groups and assigned to bundles from the schematic or layout.
13. Once a bundle is created, routing properties can be applied, pins can be swapped, and routing layers adjusted as needed. Designers can then manipulate the bundles to achieve the required routing flow, navigating conflict areas around bundles such as connectors or tightly placed components.
14. After bundling, designers can straighten out twisted connections to the pins by repositioning bundles, swapping pins, or changing layers. Beams can be converted to regular etch traces to become part of the finished design database.
15. Automatic interactive routing allows designers to create tight routing patterns, required for DDR or other specific router technologies, while benefiting from the speed of an automatic router. Additionally, it can be used for high-speed tracking adjustments and other route-clearing tasks.
16. Both types of auto-routers are essential, depending on the routing requirements. For instance, automatic interactive routing is more efficient for routing DDR memory buses. However, when DDR routing is complete and there are still many loose wires to connect, a standard batch router becomes invaluable, especially for cleaning up routing.
17. Using a standard router is also very convenient for quickly transitioning to point-to-point routing, saving time and avoiding tedious manual routing work on PCB boards.
