Teardrop (electronics)

A teardrop in printed circuit board (PCB) design is a small, filled shape, typically resembling a raindrop or teardrop, added at the junction where a trace (a conductive path) meets a pad (a larger area for component connection) or a via (a plated through-hole connecting different layers of the PCB). The primary function of a teardrop is to improve the mechanical and electrical reliability of the connection.

Teardrops achieve this improved reliability in several ways. Mechanically, they reinforce the connection by increasing the copper area at the junction. This reduces stress concentrations during manufacturing processes like soldering and subsequent thermal cycling. A larger, more gradual transition of copper mitigates the risk of the trace separating from the pad or via due to mechanical stress or vibrations.

Electrically, teardrops can improve signal integrity, particularly for high-speed signals. By smoothing the transition between the trace and pad, they reduce impedance discontinuities, which can cause signal reflections and degradation. They also help to evenly distribute current flow, reducing the risk of hot spots and improving overall circuit performance.

The size and shape of a teardrop are often determined by design rules specified by the PCB manufacturer or by internal company standards. Factors influencing the design include the trace width, pad size, layer count, and intended application of the PCB. Many PCB design software packages offer automated teardrop generation features, allowing designers to easily add and customize teardrops throughout their designs. In certain high-density designs, teardrops can sometimes be omitted to save space or avoid interference with other components.