Stamp-hole (mouse-bite) depaneling produces burrs when the breakaway web between the milled holes is torn rather than sheared or milled clean, and the only reliable fix is to control hole geometry, run a sharp carbide bit at a matched spindle speed, and accept a short deburr pass—not a harder hand snap.
Stamp holes—buyers also call them mouse bites or perforated breakaway tabs—are the row of small drilled holes along the line where a board attaches to its panel. A router mills the outline, and the holes leave a perforated web that you break off. Do it wrong and the web tears, dragging FR4 fibers and leaving a fuzzy, burred edge that fails an IPC-A-610 visual. I have pulled boards off a line where the router cut was fine but the hand snap at the end turned a clean edge into lint.
What Are Stamp Holes and Why Do They Leave Burrs?
Stamp holes are a depaneling aid, not a decorative feature. A board designer places a string of 0.6–1.0 mm holes down the break line so the router only has to cut the thin web between them, not solid FR4 across the whole span. After routing, that web is snapped or punched off, and the half-holes stay on the board edge as a castellated profile.
The burr shows up in two places, and they are different problems.
- The torn web. If the break is a manual pull or a mis-set punch, the FR4 between holes rips instead of shearing. That rip leaves a ragged fiber edge and a burr taller than the hole line.
- The routed shoulders. Even a clean router pass leaves a small burr where the bit exits the material. This one is smaller and predictable; the torn web is the one that wrecks a lot.
IPC-A-610 treats frayed, exposed glass fibers at a board edge as a defect regardless of class. A small, smooth burr may pass, but the moment you see glass strands standing off the edge, that board is a reject. Hold the edge to your own acceptance note—treat the IPC class as a floor, not a target.
How Should You Size Stamp Holes to Keep the Break Clean?
Geometry does most of the work before the machine even starts. The goal is a web thin enough to break under controlled force but strong enough to survive SMT handling.
| Parameter | Typical range | Effect on the edge |
|---|---|---|
| Hole diameter | 0.6–1.0 mm | Smaller leaves less material to break |
| Hole pitch (center to center) | 1.2–2.0 mm | Tighter pitch leaves shorter bridges |
| Holes per tab | 3–8 | More holes give a weaker, cleaner break |
| Web to board edge | 0.3–0.5 mm | Thinner web frays less when snapped |
| Board thickness | 0.8–2.0 mm FR4 | Thicker needs slower feed and a sharper bit |
I tell buyers to push hole diameter down and pitch down together. You want the bridges between holes short so the break is a series of small snaps, not one long rip. But do not starve the tab: a web under ~0.3 mm can crack during reflow or handling and drop a board into the bin before it is even depaneled. The 0.6–1.0 mm hole with 1.2–2.0 mm pitch is the band most houses run; lock your value with the PCB fab and your own process sheet, not off a forum post. Exact values depend on board thickness, material, and stack-up—set them to your program spec, not a generic table.
One more thing people miss: hole-wall quality. If the drill leaves a rough, resin-smeared hole, the break starts there and the burr follows. Spec clean drilled holes in the fab note, or the downstream break inherits the roughness.
Which Depaneling Method Produces the Least Burr on Stamp-Hole Boards?
Three ways to take the web off, and they are not equal.
Router cutting wins for control. A CNC router follows the hole line and shaves the remaining web with a carbide bit. The edge it leaves is the most consistent of the three, and because the cut is a mill rather than a rip, you almost never get the long fiber tear. The cost is cycle time and bit wear—fine for low-to-mid volume, painful at scale.
Punching (die cutting) is fast and gives a sheared edge, but only if the die clearance is right. Too much clearance and the material rolls instead of shears, leaving a burr lip. Too little and you need a press that strains the board and risks component damage. Punch is the volume play; it demands a tooling spec you actually verify, not one you assume.
Manual snap is the one I warn against. Hand-breaking stamp-hole tabs is cheap until a tech yanks at an angle and shreds the edge. If you must do it, use a controlled fixture and break perpendicular. For anything automotive or medical, I would not let manual snap near the line.
Chuangqitech router depaneling machines handle stamp-hole boards as a standard routing job: a vision system finds the break line, the spindle mills the web, and the edge comes off clean. The decision is less about the machine and more about bit sharpness and feed—covered next.
How Do You Set the Router to Avoid Edge Tearing?
This is where most burrs are actually made. The bit, the speed, and the direction decide whether the edge is milled or shredded.
- Use a sharp carbide bit and change it on a count, not on sight. A dull bit pulls FR4 instead of cutting it, and the burr grows with every board. Track bit life by hours or holes, not by “looks okay.”
- Match spindle speed to bit diameter. Small 0.8–2.0 mm router bits run in the 30,000–60,000 rpm band in normal practice; drop the feed as the bit gets smaller so the chip load stays sane. Exact numbers are machine- and material-specific—set them from your process sheet, not a blog.
- Cut climb (down-mill) on the top surface. Climb milling lays the burr down on the exit side instead of lifting the fibers, which is the difference between a clean shoulder and a fuzzy one.
- Add a light finishing pass after the break-roughing pass. A shallow second pass cleans the shoulders the first pass left behind.
I have watched a line flip from “every board needs hand-deburr” to “none do” on nothing but a sharper bit and a climb-direction change. The machine was fine. The program was not.
Do You Still Need a Deburr Step After Depaneling?
Plan for one, even when the cut looks clean. A deburr pass is cheap insurance against a lot reject at final inspection.
- Abrasive nylon brush: spins along the edge and knocks the small router burr off without touching components, provided the edge is kept clear of tall parts.
- Manual Scotch-Brite or fine sanding: fine for low volume and for the stubborn burr at a corner, but it is only as good as the person holding it.
- Micro-tumbling or barrel finish: for high-volume, burr-sensitive parts, but keep components out of the media or you will sand the wrong things.
The honest call: if your router setup is tuned, the deburr step becomes a light brush touch, not a rescue mission. If you are leaning on deburring to fix a bad break, fix the break first. Deburring a torn edge just polishes the defect.
Bottom line: Stamp-hole burrs come from a torn web and a dull router, not bad luck. Size the holes tight, mill the web with a sharp climb-cut bit, and keep a light deburr pass as a floor. The edge either passes IPC-A-610 on the first look or it does not—there is no middle where a hard snap saves you.
Q: What causes burrs when depaneling stamp-hole boards?
Q: What stamp-hole size keeps burrs to a minimum?
Q: Is router or punch better for burr-free stamp-hole depaneling?
Q: Do you still need a deburr step after stamp-hole depaneling?
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