Teardrops are copper shapes at the junction where a trace meets a pad, via, or wider trace. They strengthen the connection and help offset manufacturing tolerances and drill misalignment. Teardrops are especially useful on high-density boards and designs that see mechanical stress.
In Fusion, teardrops are design rules. When a rule is enabled, Fusion can add teardrops automatically or when you turn them on for individual wires. The rules also check teardrop results and report issues in the DRC panel.
Fusion provides four built-in teardrop rules in General Rules:
| Rule | Connection |
|---|---|
| Via Teardrop | Trace to via |
| PTH Pad Teardrop | Trace to plated through-hole pad |
| SMD Pad Teardrop | Trace to surface-mount pad |
| Trace-to-Trace Teardrop (Taper) | Narrow trace to wider trace on the same net |
Enable each rule separately. Parameters apply only to connections that match that rule. To enable teardrops and set rule parameters, see Apply teardrops to a 2D PCB.
Built-in rules set default teardrop behavior for the design. To override those defaults for specific nets, net classes, or other scopes, add a Teardrops rule under Custom Rules.
Fusion uses the first matching enabled teardrop rule in list order. Custom rules take priority over built-in teardrop rules when a custom rule is ordered above the built-in rules and matches the same connection. Custom teardrop rules use the same parameters as built-in rules. See Custom rules for scopes and rule priority.