Not every part of a circuit board ends up
in the final product. Some are temporary by design, like the small tabs on the
edges of the board. These tabs don't carry current or hold components.
We are talking about PCB breakaway
tabs—tiny connectors that hold boards together during production. If you have
ever snapped a small circuit board out of a larger panel, you have seen them in
action. Maybe you didn’t notice. That’s the point.
In this blog, we will discuss everything
you need to know about PCB breakaway tabs. Let’s break them down.
What Are PCB Breakaway Tabs?
Breakaway tabs are small bridges of
material left between PCBs during panelization. They keep multiple circuit
boards together as one unit through manufacturing. Once the boards are
assembled, tested, and reflowed, the tabs get snapped off. Clean separation.
Minimal stress.
There are different types. Some use mouse
bites—a row of small drilled holes that make snapping easier. Others use
V-scores—grooved lines scored into the board surface for clean, straight
breaks. They are not part of the circuit. But they are part of the process.
Essential for keeping boards aligned and manageable on the production floor. In
short? They’re sacrificial. And they make the rest of your PCB’s life easier.
Common Types of Breakaway Tabs
There are several ways to design
breakaway tabs, each suited to different needs. Here are the most common:
1. Mouse Bites
This is the most widely used type. A
solid tab connects PCBs in the panel, and a row of small drilled holes—called
mouse bites—makes it easier to break the tab off after assembly. Think of it
like the perforation on a ticket stub. After assembly, the tab can be snapped
off cleanly. It's fast and low-cost.
2. Scored Tabs (V-Scoring)
In this method, a shallow "V"
groove is cut into both sides of the PCB surface. It leaves just a thin strip
of material in the middle. After assembly, the board can be snapped along the
score line. V-scoring is often used when a clean edge is required, as it leaves
minimal residue.
3. Combination Tabs
Some panels use both mouse bites and
V-scoring. This allows for even cleaner separation, especially in automated
depaneling processes.
Each method has trade-offs. Mouse bites
are easy to implement but may leave rough edges. Scored tabs provide cleaner
edges but may need extra handling.
Benefits of Using Breakaway Tabs
Why use PCB breakaway tabs at all? Can’t
you just manufacture boards individually? Technically, you can. But it’s not
efficient.
Here are the key advantages:
● Efficient handling: Panels are easier to load onto assembly machines than individual small
boards.
● Reduced cost: Shared panelization saves on material, labor, and machine time.
● Lower damage risk: During transport and reflow, small boards can shift, bend, or break.
Tabs hold everything in place until the very last step.
● Improved throughput: Breakaway tabs allow multiple boards to be processed in a single pass.
● Scalable: Whether you are running 10 boards or 10,000, breakaway tabs keep
things streamlined. They work for quick prototyping and full-scale production
alike
For contract manufacturers and OEMs,
these benefits translate into better margins and faster turnaround times.
Assembling and Using Breakaway Tabs PCBs
So, how are breakaway tabs PCB designs
handled during manufacturing? Here’s the typical workflow:
1. Component Assembly
Panels with breakaway tabs are loaded
onto pick-and-place machines. The full panel is treated as a single unit. This
allows components to be placed quickly and consistently across all the boards
in the panel.
During reflow, the tabs help maintain
structural stability. No need to worry about tiny boards shifting or warping
inside the oven.
2. Breaking Off Tabs
After inspection and testing, the boards
need to be separated. This is known as depaneling.
There are two common ways:
● Manual depaneling: A technician snaps the boards apart by hand or uses cutting tools like
depaneling pliers or cutters. It’s common in low-volume or prototyping setups.
● Automated depaneling: High-volume factories use routers or dedicated machines to remove tabs
cleanly. This ensures consistent edge quality.
If mouse bites are used, the board might
have a slightly rough edge. This can be filed or sanded smooth if needed.
3. Customization and Configuration
Designers can control where the breakaway
tabs are placed. This depends on factors like:
● Component layout
● Board stress tolerance
● Final product casing
Tabs should be positioned to avoid
damaging traces or sensitive areas during depaneling. Most PCB design tools
allow users to insert mouse bites or V-scores easily into panelized layouts.
Design Considerations
Adding breakaway tabs isn't something you
do at the last minute. Good panelization planning starts early in the design
process.
Here are a few key things to consider:
● Tab size and placement: Tabs should be strong enough to hold the board but not too tough to
break. Avoid placing them near delicate components.
● Clearance zones: Allow space for router bits or depaneling tools to work without
hitting parts or traces.
● Stress distribution: Spread tabs evenly around the board to avoid flexing or cracking
during snap-off.
● Edge quality: Know if you need post-processing (filing or sanding) after depaneling.
If you are designing for automated
depaneling, talk to your manufacturer early. They might have specific
requirements for spacing, hole size, or tooling paths.
PCBasic’s Approach to Panelization and
Breakaway Tabs
At PCBasic, panelization isn’t an
afterthought. It’s a core part of our PCB manufacturing process. We design with
the full production cycle in mind—from layout to final break-off.
Our engineers work closely with customers
to determine the right type of breakaway tabs. Whether it’s mouse bites or
V-scoring, we focus on speed and quality. No compromises.
Mouse bites are still the top pick,
especially for prototypes and short runs. They are quick, cost-effective, and
require no special routing. For higher-end products or where edge quality
matters more, we lean toward scoring or combined methods.
Each board type is evaluated for:
● Size and thickness
● Component density
● Fragility of layout
● Required edge smoothness
● Method of depaneling
This ensures the tabs match the board's
actual use case, not just the standard template. We also prioritize panel
strength. Some boards need extra rails or support tabs to avoid bowing or
warping during reflow. In those cases, extra material is added to the
edges—still removable, but stronger.
Smooth Edge Finishing After
Depaneling
One common issue with breakaway tabs PCB
designs? Rough edges. Especially when using mouse bites.
After snapping, the leftover stubs from
the perforation can stick out. It's not a problem for all applications—but if
your board goes into a tight-fitting case, you’ll notice.
PCBasic offers optional edge finishing.
We use sanding wheels or mechanical routers to smooth down mouse bite remnants.
This creates a more polished and professional edge. It also prevents sharp
burrs from causing fitment issues or damaging plastic enclosures.
For boards with V-scoring, the separation
is usually cleaner. But even then, a light sanding pass can make the difference
between “functional” and “production-grade.” Some customers opt to handle edge
cleanup in-house. Others prefer it done before shipping. Either way, it’s good
to plan for this step if your design has strict size tolerances.
Support for Both Manual and
Automated Separation Processes
Different projects need different
workflows. Some engineers design their boards to be snapped off by hand. It's
fast, easy, and cost-saving, especially for small runs or DIY electronics.
Others work in high-volume environments
where manual depaneling is too slow—and too risky. That’s where automated
depaneling comes in.
PCBasic supports both. For manual
processes, we recommend mouse bites and accessible tab placement. The goal is
to make snapping safe and easy without damaging components.
For automation, we take a different
route:
● Add precise V-scores at calculated points
● Design clearance zones for routing tools
● Mark fiducials for optical alignment. While used mainly during
assembly, they also help some depaneling systems align cuts accurately.
● Use stronger rails or frames to support the panel during machine
separation
We also help customers decide if
router-based depaneling or laser depaneling is better suited for their needs.
Both methods have trade-offs in cost, time, and cleanliness.
Laser depaneling, for instance, is
non-contact and extremely precise—but expensive. However, it requires precise
thermal control to avoid damaging nearby components. Mechanical routing is more
common and more affordable.
Either way, the breakaway tab design
needs to match the depaneling method from the start. Changing it later adds
risk and rework.
Conclusion
PCB breakaway tabs are small, but they
play a big role in the production process.
They hold boards together during
handling, simplify panelization, and reduce manufacturing costs. Whether it’s a
basic mouse bite tab or a precision V-scored groove, the right choice depends
on your product’s needs.
Breakaway tabs PCB designs allow for
easier assembly, lower waste, and scalable production. But it’s not just about
choosing a tab type. Good results come from thoughtful planning—placement,
strength, tooling clearance, and finishing all matter.
At PCBasic, we don’t treat breakaway tabs
as an afterthought. We build them into your design from day one. Our engineers
help configure the right layout for your board and your budget. Whether you
need simple snap-off panels or high-volume automated depaneling, we’ve got the
experience to do it right.
And if you’re unsure which tab method to
use—mouse bites or scoring—just ask. We’ll help you design for
manufacturability without compromising performance.
In PCB manufacturing, it’s often the
little things that count. Breakaway tabs are one of those things. Small.
Invisible in the final product. But absolutely essential to getting there.
