Printed Circuit Board (PCB) designs vary, depending on the specifications. Today, it is possible to make perforations or what have come to be known as “bites” on a circuit board.
In this article, we talk about the underlying concept of “Mouse PCB.”
What is Mouse PCB?
It is also called mouse bites PCB. The other name is perforated breakaway tabs. The idea is to make small holes or perforations on the body of a Printed Circuit Board (PCB), with the aim of making room for panelization and depanelization of smaller PCB group.
It is also noteworthy that mouse bites PCB has to do with the creation of spaces for the smaller or little circuit boards to be made into a group and added to the larger PCB.
Design Scheme of the Mouse PCB
The design of this circuit board involves punching out or making a hole in the circuit board’s copper layer. Once this is done, solder paste would be used to fill the hole, after which it would be melted when the circuit board is being assembled.
Due to the design iteration, mouse bites are ideal for use with either the larger motherboards or the smaller daughterboards on the PCB.
Have in mind also that the holes to be made or perforated are to be positioned near the circuit board’s edges.
The Importance of Mouse Bites in PCBs
Why do we use smaller holes or “mouse bites” in a Printed Circuit Board (PCB)? Here are some reasons why this is important:
By using mouse bites in the PCB, designers would be able to add more components almost for the price of one.
The design iteration comes in handy to enable the processing of several panels at once – and almost for the cost of one.
Due to the design, PCBs with mouse bites can be easily disassembled. All that has to be done is to take out the affected part, fix it and fix back.
Looking to get a better grip on your Printed Circuit Board (PCB)? One popular way to achieve that is by perforating the “mouse bites/holes” around the edges.
This helps to improve the grip on the board during mounting, especially when you consider that the board wouldn’t easily slip out of place.
Creating Mouse Bites on a PCB
The processes involved in creating or making holes on the PCB are two (2). You can go in the way of laser cutting or use CNC routers.
Here are how these two compares:
Follow this method if you are looking to make the holes faster – and easily. CNC routers involve designing the PCB mouse bites with a CAD program, before making an individual perforation for the holes.
Once these holes are made, proceed to group them before drawing one hole out for connecting the others.
After the interconnections (drawing of the holes) are made, you can then export the same to an STL file. It is from this that you would get the three-dimension (3D) model of the mouse bites.
In this process, you have to set up the machine before printing. Laser cutting often entails removing both the solder mask and the traces before cleaning the PCB’s surface and applying the flux to the circuit board.
Important Considerations for Making Mouse Bites on a PCB
If you want to make these holes, certain criteria must be followed to get the best results. Here are some of the important factors that could make or mar the project:
This has to do with the diameter of the holes. The standard is 0.508mm. It has become common with manufacturers and designers alike to use this dimension because of the adjustability that allows for the shifting or modification of the holes to the components. This diameter is also preferred because of the ease of inserting the wires into the holes.
2. Sizes, Location and Spacing
The sizes of the holes also contribute to the overall specifications. It also has to do with the number of holes, which in most cases, are five (5).
In this case, the presence of 5 perforated holes in the breakaway tabs often requires the 0.030 inches or 0.76mm spacing and between 0.020 inches wide and 0.5mm for the holes’ diameters.
Exceptions: there are exceptions to the standard spacing and sizing above. In such instances, the circuit boards might not follow the above specifications. That often entails making random sizes and spacings for the holes.
If that is to be the case, it would be practically impossible to smoothen out larger holes, but the tinier holes can be smoothened out faster. The only difference between the two is that larger mouse bites would take more time for the holes to be smoothened out, while more holes need to be drilled for the tiny holes.
The density of the holes has to do with the spacing. The closer the holes are to one another, the denser they become, thereby, leaving little real estate for traces to be made on the PCB.
The diameter of the holes is also important to consider. The idea is to make larger holes that allow for the insertion of parts.
Another consideration to make for the density is the sizes. The tinier the sizes, the more difficult it becomes to insert the components. More parts can be inserted if the holes were larger.
Mouse Bites on PCB vs. V-Grooves
There are two (2) major types of breakaway tabs used in circuit boards. They are Mouse Bites and V-Grooves.
Here are some of the differences between the two:
|Involves punching holes in the PCB’s copper layer and locating these holes near the board’s edges.
|Designed as a shallow groove that runs along the length of the circuit board.
|More affordable than making mouse bites in a PCB.
|Requires less precision
|The precision level is high, such that larger gaps/sizes could lead to the PCB cracking.
|Mainly used to attach more boards, especially the larger motherboards and the smaller daughterboards.
|The primary use is for separating the circuit boards of varying widths.
|The circuit board’s edges are not so smooth.
|Offers better smoothness in the end of the Mouse PCB.
The making of mouse bites in a Printed Circuit Board (PCB) is a welcome development. Using this technique, more components can be added, multiple circuit boards (both daughterboards and motherboards) can be attached and still, there will be some spaces left for routing the traces.