Design Optimization: How to Avoid Incomplete Milling of Internal Corners in PCB Panels
2 min
When panelizing PCBs with no gap between boards, the outlines of adjacent boards can sometimes form sharp internal corners that cannot be accurately routed without artefacts such as spurs or indents. Panels like this need to be redesigned to ensure complete, spur-free board outlines.
| Example V-Cut Panel With Three Boards |
Two Possible Routing Strategies And Results
Because the router bit is round, it's unable to reach into tight corners. The unreached parts become sharp spurs after separating the boards. | In order to recreate the rounded corners of each board, the router bit must cut into their adjacent boards, altering their outline. |
Optimization Strategies
Four Improvement Strategies for the Example Panel
| 1. Add drilled holes at internal corners | 2. Add separation and mouse bites between boards |
Pro: Removes the majority of unreachable material Con: Small spurs remain | Pro: Clean outlines with no spurs Con: Jagged edges at the mouse bites after separation |
3. Add separation between boards and connect on sides with tooling strips | 4. Add sacrificial strips between boards |
Pro: Clean outlines with no spurs Con: Need tooling strips to hold boards together | Pro: Clean outlines with no spurs by allowing overcut Con: Slightly larger board area – higher cost |
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