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What Are Mouse Bites in PCB? — NextPCB

Posted:01:51 PM March 01, 2023 writer: ​NextPCB

The world is full of electronics and printed circuit boards (PCBs) play a critical role and is make sure the smooth operation of various devices. although, PCBs are not immune to problems, and it is one of the most common issues is mouse bites in PCB. They are also known as mouse nibbles, they refer to small, circular, or oval-shaped holes in the copper traces on a PCB. These holes in PCB are caused by the drilling process during PCB manufacturing.

Mouse Bites in PCB

Mouse bites in PCB may seem like minor issues, but they can have significant consequences. If left unaddressed, mouse bites can lead to poor electrical connections and signal interruptions, which can cause device malfunction or failure. In addition, mouse bites can also compromise the structural integrity of the PCB, making it more susceptible to damage and reducing its lifespan.

The purpose of this article is to provide a comprehensive guide on mouse bites in PCB. We will discuss the causes of mouse bites, how to detect them, and the various solutions available to fix them. This article aims to equip PCB designers, manufacturers, and technicians with the knowledge and tools needed to prevent and solve mouse bites in PCB.

In this article,

What Are Mouse Bites in PCB?

Mouse Bites in PCB

Mouse bites in PCB (Printed Circuit Board) refer to the process of creating small perforations or notches along the board's edge, forming breakaway tabs that can be easily removed from the panel. These notches can also be used to provide precise cuts to separate individual PCBs after the manufacturing process is complete.

These breakaway tabs or notches are designed to reduce the size of a PCB panel while maximizing the number of boards produced. The small perforations are made using a drill, creating small holes that are typically 0.25mm to 0.5mm in diameter, depending on the manufacturer's specifications.

Types of Mouse Bites in PCB

Mouse Bites in PCB

Mouse bites are tiny, round, or elliptical-shaped holes in the copper traces or pads on the surface of a PCB. These holes are caused due to the manufacturing process, environmental factors, or human errors. There are different types of mouse bites in PCB, including:

Vias Mouse Bites in PCB

Vias mouse bites occur due to insufficient plating of the vias. The via may not be entirely plated, leading to an exposed copper area. Over time, this may lead to corrosion or oxidation, resulting in a breakage of the connection.

Copper Trace Mouse Bites in PCB

Copper trace mouse bites occur when there is a thinning of the copper trace due to insufficient copper plating. As a result, the copper trace may not be strong enough to handle the current, leading to a breakdown of the circuit.

Pad Mouse Bites in PCB

When the pad is not plated correctly, it can lead to an exposed copper area, resulting in the occurrence of pad mouse bites. This exposed area may lead to corrosion or oxidation, resulting in a breakdown of the circuit.

Solder Mask Mouse Bites in PCB

When the application of the solder mask coating is incorrect, it leads to the occurrence of active solder mask mouse bites. This leads to an exposed copper area, which may cause a breakdown in the circuit.

Via-in-Pad Mouse Bites in PCB

Active via-in-pad mouse bites can be prevented by ensuring proper via filling, which avoids the occurrence of exposed copper areas. This can cause issues with the thermal and electrical connections between layers.

Barrel Mouse Bites in PCB

Barrel mice can cause bites when the copper barrel within the via is not fully plated, resulting in a copper area being exposed. This can cause corrosion and oxidation, which may lead to a breakdown in the connection.

Plating Void Mouse Bites

Plating void mouse bites occur when there is a void in the copper plating, leading to an exposed copper area. This can cause issues with the thermal and electrical connections between layers.

Causes of Mouse Bites in PCB

Causes of Mouse Bites in PCB

Mouse bites in PCB can be caused by a number of factors, including poor quality PCB material, improper handling, inadequate spacing between traces, electrical noise, corrosion, chemical contamination, and poor design. To prevent mouse bites, it is important to use high-quality materials, handle the PCBs properly, ensure adequate spacing between traces, and design the PCBs with care.

There are several causes of mouse bites in PCB. These are:

Poor quality PCB material

If the material used to make the PCB is of low quality, it can lead to mouse bites in PCB. This is because low-quality material can easily corrode, which can weaken the traces and make them more susceptible to damage.

Improper handling

If the PCB is not handled properly during the manufacturing process, it can lead to mouse bites. This can happen if the board is exposed to moisture, high temperatures, or physical stress, which can weaken the traces and make them more susceptible to damage.

Inadequate spacing between traces

If the spacing between the traces is too small, it can lead to mouse bites. This is because the traces can easily touch each other and cause a short circuit, which can damage the PCB.

Electrical noise

Electrical noise can cause mouse bites in PCB. This happens when the noise interferes with the signals in the traces, causing them to become weak or damaged.

Corrosion

Corrosion can also cause mouse bites in PCBs. This is because the corrosion can weaken the traces and make them more susceptible to damage.

Chemical contamination

Chemical contamination can cause mouse bites in PCBs. This occurs when chemicals come into contact with the PCB and actively corrode the traces, resulting in weakness or damage.

Poor design

Poor design can also cause mouse bites in PCBs. This happens when the traces are laid out incorrectly or if excessive bending or sharp turns are present in the traces, which weakens them and makes them more susceptible to damage.

Poor design

How mouse bites occur in PCBs?

A range of factors can cause mouse biting in PCBs, including machine vibrations, PCB design, insufficient support, dull drill bits, human error, and environmental factors. It is essential to take steps to minimize the risk of mouse bites during the PCB fabrication process, such as ensuring proper board support and maintenance of tools and machines.

There are several ways to detect mouse bites in PCB, including visual inspection, electrical testing, and x-ray inspection.

Tool and machine vibrations

A lot of machinery and tools actively cut, drill, and mill the board during the PCB fabrication process. The vibrations caused by these machines can lead to a shift in the board's position, resulting in small cuts or holes.

PCB design

The placement of the holes or cutouts in the PCB design can also cause mouse bites. If the holes are too close together, or if the cutouts are too small, it can cause the drill or milling machine to veer off track, resulting in unintended cuts or holes.

Lack of support

If the drilling or milling process does not receive proper support for the PCB, it may cause the board to flex, resulting in cuts or holes. PCBs that are thinner or larger are more prone to flexing.

Dull or worn-out drill bits

Dull or worn-out drill bits can cause the drill to slip or move around, leading to unintended cuts or holes.

Human error

Mistakes made during the PCB fabrication process can also lead to mouse bites. For example, incorrect programming of the CNC machines, incorrect tool selection, or incorrect board positioning can all cause mouse bites.

Environmental factors

PCB fabrication facilities can be subject to a range of environmental factors, such as temperature changes, humidity, or dust. These factors can affect the accuracy of the CNC machines and cause unintended cuts or holes.

Damages Caused by Mouse Bites in PCB

Damages Caused by Mouse Bites in PCB

Mouse bites can cause a range of damages to PCBs, including short circuits, component failure, decreased performance, and fire hazards. It is essential to take steps to prevent mice from accessing electronic devices and to address any damage as soon as possible.

Short Circuits

Mice can chew through the thin copper traces on the PCB, leading to short circuits. This can cause permanent damage to the circuit board, rendering it useless.

Component Failure

Mouse bites can also cause damage to the electronic components on the PCB. If a mouse chews through the leads or pins of a component, it can cause the component to fail or malfunction.

Reduced Lifespan

Mouse bites may damage a PCB, reducing its lifespan. The damaged parts can cause the board to malfunction, leading to failure over time.

Fire Hazard

In extreme cases, mouse bites can create a fire hazard. If a short circuit occurs, it can generate heat and cause a fire.

Difficult Repairs

If mice actively bite a PCB, repairing it can become challenging or even impossible. It may be challenging to identify all the damaged areas and replace the damaged components.

Performance Issues Caused by Mouse Bites in PCB

Performance Issues Caused by Mouse Bites in PCB

Mouse bites in PCB can lead to a wide range of performance issues and other problems. Taking active measures to prevent mice from accessing electronic devices and promptly addressing any damage is essential.

Electrical Short Circuits

When a mouse bites through a PCB trace, it can create an electrical short circuit between two adjacent conductors. This can lead to a wide range of performance issues, such as incorrect signals, data loss, and even device failure.

Signal Integrity

The damage caused by mouse bites can result in signal integrity issues. Consequently, compromising the integrity of the signals can lead to data corruption, errors, and noise interference.

Reduced Reliability

Any damage to the PCB caused by mouse bites can reduce the overall reliability of the electronic device. This can lead to a shortened lifespan of the device, which can be costly and frustrating for users.

Increased Costs

The performance issues caused by mouse bites in a PCB can result in higher costs for both manufacturers and end-users. Manufacturers may need to conduct extensive testing to ensure that their devices are functioning properly. End-users may need to replace the device, which can be expensive.

Troubleshooting Difficulties

When performance issues arise in electronic devices, it can be difficult to troubleshoot the root cause. This is especially true in the case of mouse bites, as the damage may not be immediately visible to the naked eye.

Delays in Production

If mouse bites occur during the manufacturing process, it can result in delays in production. This can be costly for manufacturers and may result in missed delivery deadlines for customers.

Safety Risks

In some cases, mouse bites in PCBs can create safety risks for users. For example, if a device malfunctions due to a mouse bite, it could result in injury or damage to property.

Impact on The Functioning of The PCB

Impact on The Functioning of The PCB

PCB or Printed Circuit Board is a crucial component of modern electronic devices. People use it to connect and arrange electronic components actively to perform various functions. The functioning of the PCB is critical for the performance of the electronic device. Here are the points that explain the impact on the functioning of the PCB:

Electrical connectivity

PCB provides electrical connectivity between the components of the electronic device. If there is an issue with the connectivity, the device will not function correctly. To ensure proper connectivity, it is important to properly design and fabricate the PCB.

Signal integrity

The signals transmitted between the electronic components need to maintain their integrity. If there is any loss or noise in the signal, the device will not function correctly. Proper PCB design, including the selection of the right materials, tracks, and via, is crucial to maintaining signal integrity.

Thermal management

Many electronic components generate heat during their operation. The PCB must have proper thermal management, including heat sinks, to dissipate the heat. Improper thermal management can cause components to fail, leading to device failure.

Power delivery

The power delivered to the electronic components should be stable and noise-free. The PCB should have proper power delivery mechanisms, including the selection of the right capacitors, resistors, and inductors, to ensure stable power delivery.

EMI/RFI

Electromagnetic interference (EMI) and radio-frequency interference (RFI) can affect electronic devices. Therefore, the PCB should have proper shielding and grounding to prevent EMI/RFI interference.

Manufacturing defects: Mouse Bites in PCB

PCBs can have manufacturing defects that can affect their functioning. These defects can include missing or incomplete connections, incorrect component placement, and incorrect soldering. Proper quality control measures should be in place to ensure defect-free PCBs.

In short, PCBs are vital for electronic devices to work properly. Good PCB design is key, including electrical connections, signal quality, heat control, power supply, shielding, and quality checks, to make sure electronic devices work their best.

Prevention and Solution for Mouse Bites in PCB

Prevention and Solution for Mouse Bites in PCB

preventing mouse bites in PCB involves proper handling techniques, using traps, maintaining cleanliness, sealing entry points, using chemical deterrents, and hiring professional pest control. These measures will help keep mice away from the PCBs and ensure their safe operation.

There are several ways to prevent mouse bites in PCB. Some tips to consider include:

Proper Handling Techniques

Handling a mouse with care and caution is crucial to preventing mouse bites in PCB. Always use gloves when handling mice to protect your hands from potential bites. Avoid excessive force or pressure when handling mice, as this can cause them to bite in self-defense. Also, avoid sudden movements, as this can startle the mouse and cause it to bite.

Use Traps

Using traps is another effective way to prevent mice from entering the PCBs. There are different types of traps available in the market such as snap traps, glue traps, and humane traps. These traps capture the mouse without harming it, making it easier to release it outside.

Maintain Cleanliness

Keeping the work area clean and free of clutter can help prevent mice from entering the PCBs. Clean up any food or drink spills promptly, and store food and garbage in sealed containers. Cleaning and decluttering, the presence of mice can be reduced since they are attracted to sources of food and areas that are disorganized.

Seal Entry Points

Mice can enter PCBs through small cracks and holes. Therefore, sealing these entry points can prevent mice from entering the PCBs. To do this, use caulk or foam to seal all cracks and holes. Additionally, make sure to firmly shut all doors and windows to prevent any air leaks.

Professional Pest Control

If the mouse infestation is severe, then it may be necessary to hire a professional pest control service. Additionally, they can provide a comprehensive treatment plan to eliminate mice and prevent future infestations.

Conclusion: Mouse Bites in PCB

In conclusion, mouse bites in PCB can have a range of negative effects on the performance and functioning of electronic devices. It is essential for electronics manufacturers and designers to take steps to prevent these bites from occurring, such as using mouse repellents, storing devices in sealed containers, and using protective coatings on the PCBs.

Moreover, in case there are indications of mouse bites on a printed circuit board (PCB), it is imperative to promptly address the issue by repairing the damage and verifying that the device is operating correctly. This can prevent further damage and ensure that the device continues to operate as intended.

For further reading on PCBs, you can check out NextPCB's blog for more informative articles on PCB manufacturing, design, and testing. 

Tag: Mouse Bites
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