An Introduction to Mouse Bites: Usage, Features, & Standards


Mouse bites in printed circuit boards are small perforations that allow for small boards to be connected in a group. We will discuss the usage, features, and standards of mouse bites in PCBs.

These are a set of separating tabs that have special features to aid with manufacturing and assembly. You can file them, or drill them with a punch, without damaging the copper foil inside the board. You may have seen boards with small holes instead of breakaway tabs on some or all of the board edge connector pads, but you may not have known what those are for.

In this article, we’ll discuss how mouse bites work in a printed circuit board. I am sure you have seen these tiny holes when you look at the back of your circuit board.

Introduction to Mouse Bites

Introduction to Mouse Bites

What are Mouse Bites in a PCB?

When you look at a printed circuit board, you might wonder why it has holes all over the place.

The term “mouse bite” comes from the fact that this type of hole looks like it was made by a small rodent’s bite.

They are used to connect the small PCBs that make up an array together. The holes around postage stamps do the same thing, but with stamps instead of printed circuit boards. They’re used to make it easier to remove components from the board. The tab is perforated so that when you push down on it, it breaks off, allowing you to remove the component without damaging the circuit board itself.

What is Mouse Bites Purpose in a PCB?

There are lots of reasons why you might have a mouse bite on your circuit board.

One reason is to allow small boards to connect in a group. When you have a bunch of boards that need to be connected, but they’re too small for the connectors to be used on all of them, you can use these perforations to link them up. The perforations will let electricity flow through the board and connect it with other boards nearby.

Sometimes mouse bite holes are called perforated breakaway tabs. This allow power and data transfer between two different boards or devices. If you want one device or board to communicate with another device or board, this can happen through these holes. It’s easier than trying to figure out how to wire everything together!

Mouse Bites’ Features in a PCB

If you’re looking for a way to identify mouse bites on a printed circuit board, there are a few things to look out for. The mouse bites’ features in a printed circuit board are:

Number of Holes

Mouse bites, or mouse holes, are small holes that can be found on the surface of a printed circuit board. These holes are usually located in groups of five and are used to connect components together.

The number of mouse bites can vary depending on the design of your PCB, but they will typically be found in groups of 5.

Number of Holes

Number of Holes

Hole Size

Mouse Bites’ hole size is usually 0.020 inches or 0.5mm in diameter but it can vary depending on the printed circuit board design. The size of the hole is determined by the thickness of the material used to make the printed circuit board.

The holes are arranged in a specific pattern to ensure that the board components are properly aligned and connected during assembly.

Hole Size

Hole Size

Hole Spacing

The usual mouse bite hole spacing is 0.030 inches or 0.76mm apart, which prevents the components from being too close together and causing a short circuit.

Hole Spacing

Hole Spacing

Tips for Having Mouse Bites in your PCB

When you’re creating a PCB, it’s important to remember that there are a few things you need to do to ensure that your board is going to be as functional and robust as possible.

One of the most important things that you can do is make sure that your mouse bites are properly placed. When you have mouse bites in your PCB, you’re increasing the likelihood that your device will work correctly and last for years without needing repair or maintenance.

The following tips will help you get started:

Avoid Using Many Tabs

The use of tabs can affect the reliability of a mouse bite in a PCB. For example, if you have too many tabs and they are not properly soldered, there will be shorts between the leads. This can cause problems with the function of your circuit.

It’s tempting to use many tabs when designing your PCB, but do you really need all of those? Think about it: when you’re designing a PCB, the purpose is to create a circuit board that will allow electricity to flow through it. The more tabs you have, the more copper lines are being used, and the more copper lines are being used, the less effective your circuit is going to be.

When designing your circuit board with holes in it, keep this principle in mind: use as few tabs as possible. The fewer tabs you use, the better your circuit will work.

Sufficient Tabs to Sustain PCB

Since the mouse bite is an opening, it means that there are no connections to it. When this happens, there will be a short circuit between two parts of the PCB. To prevent this from happening, you need to make sure that your tab is strong enough to support the weight of the components located above it.

The best way to ensure the long-term stability of your PCB is to make sure it has enough tabs. This will ensure that the board will be able to sustain itself over time, and it’s also a great way to ensure that your board will be able to hold up under pressure.

Tabs Should be Far from Sensitive Components

When you’re designing a PCB, it’s important to keep in mind the distance between your tabs and sensitive components. In general, try to keep tabs away from any component that could be damaged by heat, soldering, or pressure—like a battery or a processor.

The main reason why you want to keep tabs away from sensitive components is that they can be easily damaged, which could potentially result in an electrical short. This could also cause your product to malfunction and stop working properly.

Sensitive Components

Sensitive Components

The spacing of two mouse bites should be between 60mm to 90mm

The spacing between two mouse bites is a very important factor in the design of PCBs. If there is too much space between two mouse bites, then it will be difficult to install components. If there is too little space, then it will be easy for the solder to flow into unwanted places and cause shorts or other problems.

You can use a ruler or even a pair of calipers to measure the distance between two mouse bites on your PCB.

Have at least 0.125 inches of clearance to the nearest components.

You should have at least 0.125 inches of clearance to the nearest components. This is a good rule of thumb to follow for any design, but it’s especially important for high-density PCBs. The closer you get to your components, the harder it will be to solder them and keep them in place. If you get too close, you’ll end up with solder bridges between pads or traces, which can cause all sorts of problems later on—and lead to an unusable board.

Mouse Bites and V-Grooves Difference

When it comes to PCB manufacturing, you might be wondering what the difference is between a mouse bite and a v-groove. Mouse bites and V-grooves are two common methods used to connect the ends of a pipe. Both are effective, but they have some key differences. But which one is right for your project?

Mouse Bites Advantages

There are several advantages to using mouse bites instead of V-grooves.

Better Grip

Mouse Bite holes offer a better grip when mounted than V-grooves. The larger the hole, the more surface area you get for the adhesive to grip, which makes installation easy and keeps your circuit board from shifting around.

The larger the hole, the more surface area you get for the adhesive to grip. This makes installation easy and keeps your circuit board from shifting around.

Better Grip

Better Grip

Better use in Hand Separation Techniques

For applications where hand separation is desirable, mouse bites will work better than V-grooves.

V-grooves are used when you want to use machine separation as your primary technique for separating the two parts. Mouse bites are meant to be used with hand separation as a secondary technique for separating the two pieces.

Hand Separation

Hand Separation

V-Grooves Advantages

V-grooves are the most common type of through-hole component placement. They consist of a rectangular hole that is wider at the top. V-grooves are used for placing components vertically, with their leads facing outwards.

Cost Efficient

V-grooves are less expensive to make than a mouse bite hole. Mouse bites holes are made by using a drill or punch press that cuts through the copper layer of the board and leaves tiny holes. These holes can be seen on top of the copper layer. V-grooves do not show through as they are located under the surface of the copper layer. The cost difference between these two types of holes is significant.

Easier to Manufacture

Another main advantage of V-Grooves in a printed circuit board is that they are easier to manufacture than the mouse bites hole. The process for making V-Grooves is relatively simple and straightforward. This makes them easier to produce than the traditional mouse bites hole.

Greater Strength

They offer greater strength than mouse bites and can be filled with epoxy to prevent corrosion. They also have improved thermal stability, meaning they are less likely to warp or distort over time.



IPC-7351 For Mouse Bite Standards

The IPC-7351 standard is a set of guidelines for designing, manufacturing, and assembling electronic equipment. The document details the requirements for a product to be classified as “IPC” compliant. One section of this standard deals with the design and manufacture of electronic devices that can be easily removed from their housing without the use of tools. This type of device is referred to as a “breakaway”.

In particular, it covers the ways in which breakaway connections can be made between electrical components such as connectors and PCBs. It also specifies how these connections should be made so that they do not impede access to other components within the device after removal has occurred.

IPC-7351 Preferred Mouse Bites

In order to ensure that we meet the required standards, the trace routing must be at least 1 mm away from the finished board edge and mouse bites.

IPC-7351 Preferred Mouse Bites

Preferred Mouse Bites

IPC-7351 Acceptable Mouse Bites

The trace routing on top of the finished board edge and the mouse bites are still acceptable. The traces are routed in the correct direction, there is no under-routing, and the mouse bites are still within tolerance according to IPC-7351 standards.

IPC-7351 Acceptable Mouse Bites

Acceptable Mouse Bites

IPC-7351 Not Recommended Mouse Bites

The trace routing aligned with the finished board edge and the mouse bites is still not recommended by the IPC-7351 standards.

The IPC-7351 standard has a section on testing for mouse bites. It does not specify that you need to route traces over the finished board edge. In fact, it suggests you don’t route them over the finished board edge. The reason for that is routing over the finished board edge can cause issues with solderability and reliability.

IPC-7351 Not Recommended Mouse Bites

Not Recommended Mouse Bites


If you are new to designing and learning about mouse bite holes in your printed circuit boards. The templates in this article will be a great resource to get you started on your first project. If you have experience, then this may be a good example of what not to do. Regardless the choice is up to you but if it helps I hope these articles have provided some insight into mouse bite holes design as well as printed circuit board design overall.

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