In order to get the optimum use out of your printed circuit board (PCB), your PCB may require a process called backdrilling.
Backdrilling removes a part of the PCB’s structure called the via stub. The via stub is not connected to the circuit and performs no function within the PCB. Through backdrilling, manufacturers use a drill bit to remove the via stub’s plating and reduce the stub length.
How necessary is backdrilling and why do you need it? Let’s answer that question by exploring some of the benefits of backdrilling.
- Clearer Signal
Without backdrilling, the digital signals passing through your PCB can become distorted. The higher the data rate is, the greater the distortion can be.
One particular kind of signal distortion with PCBs is called deterministic jitter. Any kind of jitter can negatively impact the PCB’s performance and can even cause data loss. Deterministic jitter is a specific kind of jitter that you can more easily predict and adjust.
Removing the via stub plating through backdrilling can decrease signal interference and remove deterministic jitter.
- Lower Bit Error Rate
Bit error rate (BER) tells you how many of your PCB’s bits have errors. BER is the percentage of bits with errors divided by the total number of bits. It measures the performance of the entire transfer system, including the transmitter, medium, and receiver.
The lower the BER, the better the integrity of the entire system. In other words, a system with a lower BER will perform better and encounter fewer problems.
Bit error rate (BER) correlates with deterministic jitter. Once you lower the deterministic jitter through backdrilling, you can also decrease overall BER. This can lead to better integrity and performance for your PCB.
- Increased Channel Bandwidth
By removing the interference caused by via stubs, backdrilling can also increase channel bandwidth. Bandwidth refers to how much information a device can handle in the moment.
While low bandwidth is fine for simple tasks like searching the internet, higher bandwidth is crucial for streaming and transferring complex data and programs.
An increase in bandwidth improves your ability to transfer data. This increases the speed and quality of your applications—which can improve overall business performance.
- Reduced Via-to-Via Crosstalk
Crosstalk occurs when signals from two vias interfere with each other. Crosstalk decreases signal quality and often causes some kind of noise or feedback to occur. In a phone, crosstalk can cause someone to hear someone else’s conversation. High levels of crosstalk can even cause circuits to burn out.
By improving signal strength and quality, backdrilling can help eliminate crosstalk between vias.
- Decreased Signal Attenuation
A reduction of signal strength during transmission is known as attenuation. For example, when a signal travels through a barrier like a wall, its transmission weakens.
Improved impedance matching decreases attenuation. Impedance occurs when a system opposes energy flow. Impedance matching makes the load equal to the source. It reduces impedance and improves the transfer process.
Reducing stub length through backdrilling improves impendence matching. This in turn reduces signal attenuation, improving signal strength.
- Decreased EMI
When an outside source impacts a circuit’s performance, the disturbance is called electromagnetic interference, or EMI. EMI can cause an electrical circuit to stop performing entirely and could even cause you to lose your data. Outside sources that cause EMI include devices like phones and natural occurrences like thunderstorms.
Backdrilling can decrease the possibility for EMI from the stub end. Since the stub end is a common place for EMI to occur, backdrilling can decrease your risk of EMI and associated system failure.
- Reduced Resonance
Shortening stub length through backdrilling also decreases resonance. Resonance can create unwanted sound that is both long-lasting and reverberating. Reducing resonance can improve the overall quality of your PCB.
- Increased Data Rates
Along with increasing bandwidth, PCBs also increase your data rate. The data rate is defined as the speed data transfers from one device to another.
The benefits of an increased data rate is obvious. From aerospace to technology, every industry across the board needs to transfer data quickly and efficiently. Backdrilling is one way to enhance the speed and quantity of your data transactions.
In summary, backdrilling can get you a faster, higher-quality signal by reducing stub length.
There are alternatives to backdrilling that also reduce stub length. These include laser-drilled vias and alternative stacking arrangements. However, these other methods are often more expensive and don’t work in every situation.
Backdrilling has continuously shown to reduce signal distortions and improve signal performance, without any negative impact on the PCB.
Make sure you choose a PCB that is back-drill capable. If you need a new PCB or would like to backdrill your current PCB, call Streamline Circuits. We are a leading manufacturer of advanced PCBs for aerospace, medical equipment, communications, and many other industries.