I’m running into issues with mousebites on thinner PCBs, specifically 0.039" and0.049" boards, where flexing becomes a problem—especially when there are SMT components placed close to the board edge. On 0.062" PCBs this hasn’t been a concern, but the thinner substrates are much more prone to bending and damage after depanelization.
Right now, I’m using mousebites made up of five unplated 0.5mm holes spaced 1 mm apart. I’m depanelizing with pliers, which works to a degree, but there’s still some shearing and the occasional minor damage to the board. I’ve considered adjusting the mousebite design to make them snap off more easily or sawing them off for a cleaner edge—but that would require a jig and adds process complexity.
In some designs, I can’t avoid having SMT parts near the mousebite areas, which makes things trickier. When there’s not enough material between the board and the tooling strips, there’s too much flexure during assembly, and I’m relying too heavily on push-up pins during SMT placement.
Has anyone else run into similar problems? Any tips for cleaner mousebite removal or strategies to reduce stress on thin boards during depanelization and assembly?
I’ve worked with a CM who used a milling machine to remove the tabs cleanly, which eliminates the need for mousebite holes altogether. It’s a much cleaner process, especially for thin boards, and it significantly reduces the risk of flexing or shearing during depanelization. If your CM offers this option, it might be worth exploring.
Yes, we’ve dealt with this on occasion, one trick that’s helped us is to make sure the solder mask is cleared on both sides of the board around the snap-off region—this reduces stress and potential delamination during depanelization.
We make sure the mousebite holes go into the PCB outline rather than extending beyond it. That way, once snapped off, the board edge stays flush with the routed profile, which improves both aesthetics and mechanical stability.
One option to consider for thin PCBs or flex circuits is laser singulation. Since it’s a non-contact method, it minimizes mechanical stress during depanelization—helping reduce bending, edge damage, and risks to nearby SMT components. It can be a cleaner alternative to mousebites, especially when tight layouts don’t leave much room for tooling strips.
In most cases, V-scoring (scoring along the top and bottom surfaces) tends to work well for easy snap-off during depanelization—especially for standard board shapes. It’s generally cleaner and causes less flexing compared to mousebites.
For non-standard shapes like circular boards, we’ll still use mousebites, but we try to optimize the design by using hole sizes similar to via diameters to balance strength and ease of separation. That seems to help reduce stress during breakaway.
My CM generally prefers V-scoring over mousebites whenever the board layout allows for it. That said, there’s a minimum board thickness below which scoring isn’t practical—if I recall correctly, it’s somewhere around 20 mils for standard rigid boards. Below that, alternative methods like mousebites or laser depaneling might be more suitable
Several contributors in this thread have offered great insights.
The best solution is to use a depanelization router, which cuts out the individual boards rather than breaking them out. This dramatically reduces stress on the laminate and leaves clean edges without glass fiber splinters or nubs. It essentially uses mousebite tabs, but instead of snapping them off, the router cuts them precisely.
These routers rely on a camera system and alignment fiducials placed in the panel array, which are defined in the original CAM data. This is why it’s helpful to have the same vendor handle both fabrication and assembly, to ensure there’s no disconnect in file handling.
For extremely thin or specialty materials like PTFE, laser depanelization is another great option that completely avoids mechanical stress.