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What are PCB mouse bites?

PCB mouse bites are a row of small perforations in a breakaway connection between a circuit board and its panel or rail. The routed spaces around the connection establish most of the board outline; the remaining tab keeps the unit attached until an agreed separation operation. After separation, the perforations and broken laminate can leave a scalloped or rough region. That region must be considered part of the finished-edge design.

The holes are not electrical vias simply because they appear in a drill file. Their intended role is mechanical separation. State the plating requirement, hole dimensions, row position and retained-tab geometry explicitly. The tab drawing should also identify which side of the nominal board outline retains material after separation. A row placed without reference to that outline can produce an edge that conflicts with an enclosure or connector.

This page covers the geometry and release of perforated tabs. The broader panelization guide for assembly covers rails, repeat arrangement and assembly handling. The PCB depaneling review addresses separation method, support and component risk. Keeping those tasks separate makes the tab note easier to review.

Define the tab with dimensions that mean one thing

Center pitch is not the solid material between holes. If the pitch is 0.80 mm and diameter is 0.50 mm, the nominal ligament between neighboring holes is 0.30 mm. Confusing pitch with ligament changes the row width and the amount of retained material. Use one dimension convention across the footprint, drill output and mechanical drawing.

The outside span of a centered row is `(n 鈭� 1) 脳 p + d`. Symmetric end material is `(W 鈭� span) / 2`. These equations describe a straight row of identical circles. They do not cover staggered rows, elongated holes, tapered tabs or deliberately overlapping holes. Those constructions require their own geometry and manufacturing review.

Check a hole row before placing it on the panel

Enter your tab width, hole count, finished diameter and center pitch. The calculator rejects a row that extends beyond the tab and rejects overlapping or touching perforations in this separate-hole model. A zero end margin is displayed as geometry, not recommended as a release condition. No value is prefilled until you choose the illustrative example.

The output includes outside span, ligament, end material and the sum of solid width across the row. That last number is not a strength value: stress concentrations, laminate direction, thickness, tab depth and the actual force path are absent from the model. It must not be used to calculate break force, predict a clean snap or certify component protection.

A worked row that fits, but is not yet approved

For an illustrative 5.00 mm tab with five 0.50 mm holes at 0.80 mm center pitch, the outside span is 3.70 mm. The centered row leaves 0.65 mm at each end. There is 0.30 mm between neighboring holes, and the geometric sum of solid width across the row is 2.50 mm. These numbers are internally consistent, but they are not a 吃瓜tv capability table or a universal mouse-bite recommendation.

Now increase the hole count to seven without changing the tab. The span becomes 5.30 mm, so the entered row cannot fit within the 5.00 mm tab. A drawing that merely says 鈥渟even mouse-bite holes鈥� would conceal that conflict. The calculator makes it visible before a reviewer has to reconstruct the row from a screenshot.

Even the five-hole row still needs a position relative to the board edge. Shifting the row inward can remove material from the delivered outline; shifting it outward can leave more protruding material. The required final outline and any permitted residual edge features should control that decision. Do not move the perforations solely to make the footprint pass a generic CAD clearance check.

Place tabs around manufacturing and assembly constraints

Tabs must support the panel through its preceding operations, yet remain accessible at separation. That is a system tradeoff. Board size, outline, component population, rails and fixture design affect suitable placement. Avoid treating the smallest possible tab as the best tab: a weak panel can flex or become difficult to handle before the intended separation step.

Review component bodies, leads and overhangs on both faces. The tool that removes a tab needs a physical approach path, not just a line on the CAD drawing. Include the support fixture and any hold-down contact areas. A tall connector may block access even when its solder pads are well away from the tab. A small bottom-side capacitor can be at risk if a support lands beneath it.

The separation sequence also matters. Once one bridge disappears, the support conditions change. Number the intended removal order and show how the final unit is restrained after the last connection is removed. If an operation bends the board, review strain-sensitive components using their supplier guidance; the is one relevant starting reference for ceramic capacitors.

Decide whether the final edge is cosmetic or functional

A board edge sliding into an enclosure slot has a different requirement from an internal edge with generous space around it. Describe the maximum permitted protrusion, local recess, burr or roughness using the project's drawing conventions. If edge dressing is required, include it in the process and quote scope. Do not assume an operator will file the board until it fits.

Finishing can affect nearby copper, mask and components. The permitted removal envelope should be explicit, especially near a mounting reference or an electrical contact region. Debris and cleaning requirements also belong in the process plan. For an assembled board, a seemingly minor finishing step may introduce handling and contamination risks that were absent from the bare-board quote.

Represent the row consistently in manufacturing data

The fabrication package should contain one authoritative board outline, an unambiguous panel or tab drawing, and a drill representation that agrees with the intended holes. Separate the delivered board boundary from the routing paths and temporary connecting material. Otherwise, one viewer may show a complete outline while another implies that the bridge should already be removed.

Check units, origin, hole count and row orientation in an independent output view. A copied tab footprint can rotate or inherit unintended copper pads. Confirm that the drill data does not turn a mechanical perforation into a plated interconnect. The PTH versus NPTH file review explains why visible copper rings and hole-wall declarations are different decisions.

When a CAD rule reports a conflict near an intentionally interrupted outline, resolve the rule scope and the fabrication intent together. Do not silence every edge-related check to make the tab disappear from the error list. Document any deliberate exception, retain the exact output revision and have the manufacturer review the released geometry. provides version-specific output context; it is not a fabrication capability specification.

What changes the price of tabbed panels?

Tab routing uses panel area and creates routing, drilling, handling and separation work. More spacing can reduce the number of boards on a production panel; more tabs can increase removal and finishing effort. Fewer tabs may weaken support or complicate handling. A quotation should therefore compare the whole panel and assembly route rather than charge or optimize only by hole count.

Ask whether setup, edge finishing, cleaning and the intended populated-board separation are included. State the order quantity and the units delivered per panel. If a fixture is needed, identify ownership and whether its charge is one-time or recurring. Use a controlled trial to settle uncertain handling conditions before assuming that a nominally cheaper layout will be economical in repeat production.

For rectangular boards with continuous shared boundaries, mouse bites versus V-groove offers a focused comparison. It deliberately does not choose an option by a universal price ranking. The dimensions, route and support must fit the actual product.

A concise mouse-bite drawing handoff

Release the tab width and shape, hole diameter and count, center pitch, row offset, plating declaration, position tolerances and the required finished edge. Pair those dimensions with the separation method, fixture access and assembly state. If you provide an example footprint, label whether it is a required design or a starting proposal that may be changed after review.

Coordinate the drawing with PCB manufacturing before freezing the panel. If 吃瓜tv will also assemble the product, provide the component data at the same time so the tab and separation decisions can be reviewed together. A useful enquiry names the uncertainty鈥攅dge fit, component proximity, tool access or panel support鈥攊nstead of requesting 鈥渟tandard mouse bites鈥� without a final-edge requirement.

Mouse-bite design questions