PCB Teardrop You Should Know

In the design and manufacturing of PCBs (Printed Circuit Boards), the teardrop (Pad Tear Drop) plays a vital role. It is not only the connection point between electronic components and PCB, but it can also enhance the soldering strength and improve stability. This article will delve into what a PCB teardrop is, what it does, and how to set up a PCB teardrop to help you better understand and apply this key technology.

What is a PCB Teardrop?

PCB teardrops are small drops of solder material that form around electrical connection points on a PCB circuit board. It is usually oval or circular in shape and is located between the pad and the circuit line. It plays a role in strengthening the connection, enhancing the soldering strength, and reducing stress concentration. The formation of teardrops is due to the balance between the surface tension of the solder and the surface tension of the PCB substrate material during the soldering process. This balance causes the solder to form a drop-like structure between the pad and the circuit trace.

PCB Teardrop Type

While the typical shape of teardrops is a straight line that tapers off, they can also be concave. This type of teardrop is also called rounded or straight. To create the teardrop shape of a snowman, a smaller secondary pad needs to be added at the junction where it overlaps the main pad (hence the name).

PCB teardrops play an important role in the soldering process, primarily in the following aspects:

Enhancing soldering Strength: Teardrops can offer extra support and connection for soldering, improving the stability and reliability of the solder. This effectively prevents the soldering joints from breaking or loosening. It can not only protect the pads and prevent them from falling off during multiple soldering processes but also avoid problems such as uneven etching and cracks caused by offset vias during the production process.

Reduce stress concentration: Teardrops are formed as a buffer area under the influence of PCB surface tension and solder surface tension. This formation effectively reduces stress concentration around solder joints, minimizing the risk of solder joint fatigue and fracture.

Optimizing soldering Quality: Properly setting teardrops can enhance the distribution of solder between pads and circuit lines, leading to improved soldering quality and reduced soldering defects and defect rates.

Protecting Circuit Board Structure: Teardrops can prevent the contact points between wires and pads or wires and via holes from being disconnected when subjected to significant external force impacts. This helps safeguard the structural integrity of the circuit board. Additionally, teardrops can enhance the aesthetic appeal of the PCB circuit board.

Optimizing signal transmission: Teardrops can help smooth impedance, reduce abrupt changes in impedance, and prevent reflections caused by sudden reductions in line width during high-frequency signal transmission. This helps to provide a smoother transition between the trace and the component pad, optimizing signal transmission quality.

Where should I place the teardrops?

When designing your PCB, consider adding teardrops in the following situations:

● Add teardrops for through-holes where the trace-to-pad ratio is small.

● Add teardrops to high-density boards where the annular ring around vias needs to be preserved.

● Add teardrops on flex boards to reduce the stress where the trace joins the pad.

● Add teardrops under the BGA(Ball Grid Array) where there are many vias.

● Add teardrops when traces exit the pad, whether it is a solid pad or a pad with a via.

● Add teardrops when the trace becomes narrow.

● No need to add teardrops when the conductor is more than 20 mils.

How to Add Teardrops in Altium Designer?

Taking Altium Designer as an example, first select the "Tool" tool.

Execute the menu command "Tools-Teardrops" or the shortcut key "TE" to access the teardrop attribute setting dialog box as shown in the figure below, and then select the object to perform the operation.