PCB, short for printed circuit board, is a support used to connect electronic components (such as resistors, capacitors, diodes, etc.) to circuits. In the PCB design , all designers know that right angles are a very difficult problem, because right angles will introduce many problems during the manufacturing process and use. Therefore, why PCB layout cannot have right angles becomes an interesting question.
Why PCBs cannot have right angles?
First of all, it needs to be clear that during the PCB manufacturing process, right angles will cause many problems due to manufacturing and inspection requirements. The main problem is that when there are right angles in the circuit board, it will cause the finished circuit board to have great mechanical stress, especially under high temperature and humidity conditions.
During the manufacturing process, PCB needs to be manufactured through a series of process steps, including PCB drilling, copper plating, PCB etching, gold plating, printing, etc. If there are right angles in the PCB design, the right angles will be easily corroded during the etching process, resulting in uneven or incomplete patterns. In addition, right angles can cause etching imbalances that may damage cold-welded joints and affect the service life and reliability of the finished product.
In addition, during the manufacturing process, PCBs also need to undergo AOI (Automated Optical Inspection) inspection to ensure that the quality of the circuit board meets the design requirements. If there is a right-angle design during the AOI inspection process, it will be difficult to guarantee the accuracy of the inspection results. Because of the height of the right angle and the shape of the edge, the inspection instrument may not be able to obtain correct data. Moreover, right angles tend to harbor dirt and grime, making detection more challenging.
Secondly, even if there are no problems during the PCB manufacturing process, right angles will have an adverse effect on the circuit board during use. Circuit boards occupy very small spaces in electronic devices and need to withstand various mechanical stresses and temperature changes. If the circuit board has right angles, the vertical force will not be distributed evenly, the risk of corrosion will increase, and the circuit board will be more likely to be damaged during use.
In addition to these hard manufacturing and usage issues, right angles can also affect the aesthetics of PCB design. Although this issue may not be that important, designers still try to avoid using obvious right angles in designs whenever possible, especially in high-end products, and do not like to create an unsightly impression.
Why do we need to route lines at 45 degrees?
In PCB design, why should we use 45-degree inclined lines for routing? There are several reasons to explore here.
The first is electromagnetic compatibility (EMC). In PCB design, EMI (electromagnetic interference) will occur between many signal lines and power lines. During PCB layout, if you want to minimize EMI, you need to pay attention to avoid right-angle connections.
Right-angle connections create very strong charge edges from the electric fields of signal and power lines. This causes electrons to collect at the edges and form high-energy states, creating a flow of electrons. This flow of electrons can cause high-frequency leakage, causing EMI. The 45-degree angle connection will make the charge at the edge more uniform and the electron flow smoother, thus effectively reducing the level of EMI interference.
Second is continuity and reliability. At right-angle connections, tiny gaps between circuit traces can cause signal reflections and impedance changes, which can lead to signal loss and instability. The 45-degree angle connection can reduce this reflection and change to a certain extent, thereby improving circuit conductivity and reliability.
Finally, there are the visual effects. Using a 45-degree angle connection can make the PCB traces look neater and more beautiful. This is particularly important for products with commercial applications.
How to use 45 degree angle in PCB layout?
Using 45-degree connections in PCB layout is usually very simple. Here are some basic practices:
The first is to use 45 degree angle connections as the default for the PCB layout. When designing PCB diagrams, right-angle connections should be avoided as much as possible, and 45-degree angle connections are encouraged to reduce EMI and improve conductivity and reliability.
The second is to use the 45-degree angle connection tool provided in the PCB software. When wiring, PCB software usually provides hotkeys or shortcuts for 45-degree angle connections. This results in faster routing and fewer errors.
Finally, during the wiring process, the overall arrangement of the wiring must be considered rationally. In extensive circuit routing, the routing needs to be refined based on considerations such as the importance of connections and crossovers between different layers. This can effectively reduce EMI and improve conductivity and reliability.
Conclusion
In summary, right angles have many problems for PCB manufacturing and use. In the design and manufacturing of PCBs, designers should avoid using right-angle designs to ensure the reliability and stability of the circuit board. If a right angle must be used in a design, careful consideration and care must be taken to ensure that the right angle has the least impact on the equipment.
In the future, the continuous advancement and innovation of PCB manufacturing technology may reduce the problems caused by right angles, but the principle of prohibiting the use of right angles will still persist. This is also a basic principle that a PCB designer needs to follow.
