Should teardrops be added when designing PCBs?

This question can spark a lengthy debate among both new and experienced engineers in the electronics industry: some insist that teardrops must be added to the entire board, calling it a "life-saving operation" to improve reliability; others strongly oppose it, complaining that adding them to high-frequency boards directly causes signal failure. Even more confusing is that experienced engineers have completely opposite approaches.

In reality, there's no "must-add" or "absolutely not-add" standard answer for teardrops. The key is to understand their true function and find the right application scenarios. Today, we'll explain the core logic of PCB teardrops in simple terms, so you'll never have to worry about this again!

First, understand this: teardrops are not "decorative," but a collection of 5 practical functions.

Teardrops are the teardrop-shaped or arc-shaped transitional copper areas between PCB traces and pads or vias. They may seem insignificant, but they hide five key functions:

1. Strengthening the connection:
Like reinforcement strips at clothing seams, teardrops increase the contact area between the trace and the pad, dispersing external forces. Whether it's vibration during product transportation, plugging and unplugging during use, or later maintenance and connector removal, it prevents the pad and trace from being torn apart, directly doubling the mechanical strength.

2. Protecting the pads from "failure":
During multiple soldering cycles, the pads repeatedly endure thermal expansion and contraction stress, easily leading to warping and peeling; uneven etching during production and via misalignment can also cause pad cracking. Teardrops act like a buffer, absorbing thermal stress and reducing these failure risks.

3. Ensuring smooth signal transmission:
When the trace and pad widths change abruptly, signals are prone to reflection and attenuation. The smooth transition of the teardrop reduces impedance changes, allowing for smoother signal transmission and preventing "traffic jams."

4. Improving production "yield":
Drill bits inevitably have slight deviations during drilling. The extra copper allowance of the teardrop "cushions" against this, preventing the trace from breaking due to drilling deviations; it also reduces over-etching problems during the etching process, giving factories a higher tolerance for errors during production.

5. An aesthetic "bonus":
Compared to rigid right-angle connections, teardrops make the transition between traces and pads more natural, improving the overall appearance of the PCB. The board looks more organized and professional, and the visual effect is directly upgraded.

In these scenarios, teardrops are a "must-have," and omitting them will inevitably lead to problems.

Based on actual application scenarios, it is recommended to prioritize adding teardrops in the following 4 situations to significantly reduce the risk of product failure:

1. Environments with high mechanical stress: Mandatory addition
Products such as automotive electronics, industrial controllers, and frequently plugged/unplugged connector interfaces are subject to vibration, collision, or frequent plugging/unplugging. The connection between the traces and the pads is a "weak point" where stress is concentrated. It is recommended to choose rounded or "snowman" shaped teardrops, which can effectively disperse stress and prevent fracture failures during use.

2. High-frequency/high-speed signal scenarios: Add with caution
High-frequency and high-speed circuits such as 5G communication modules and high-speed memory interfaces have extremely high requirements for signal integrity. Teardrops should not be added blindly; smooth, curved teardrops should be prioritized, and impedance matching must be verified through simulation to avoid signal distortion caused by the teardrops.

3. High-density PCBs: Selective addition
High-density boards such as mobile phone motherboards and wearable devices have extremely limited routing space. Adding teardrops to the entire board will occupy extra space and affect routing density. It is recommended to add them only to critical pads and vias, and omit them in non-critical areas to balance reliability and routing efficiency.

4. Mass production optimization scenarios: Adjust as needed
For low-cost consumer electronic products, if the PCB manufacturer's process capabilities are average (e.g., low drilling accuracy), the teardrop coverage area can be appropriately increased to compensate for process deficiencies and improve mass production yield; if the manufacturer's process is mature, the conventional size can be used to avoid wasting space.

Adding teardrops in these 3 places is equivalent to... Adding teardrops: Proceed with caution!

Not all scenarios are suitable for adding teardrops. Blindly adding them in the following situations will only be counterproductive:

1. Impedance-sensitive areas:
For areas with extremely high impedance requirements, such as antennas and differential pairs, impedance verification must be performed before adding teardrops. If the teardrops cause impedance mismatch, it will directly affect product performance, making it worse than not adding them at all.

2. Ultra-high-density boards:
For products such as miniature sensors and extremely compact mobile phone motherboards, where the wiring density is already maximized, teardrops will further compress the routing space, potentially leading to routing difficulties or even short-circuit risks. Careful evaluation is required before deciding whether to add them.

3. Low-complexity circuits:
For simple control boards and ordinary consumer electronics, which have lower requirements for mechanical strength and signal integrity, the benefits of adding teardrops are limited, and it will only increase design time. To simplify the process and improve efficiency, teardrop design can be omitted.

Summary: The core principle of teardrops is "adapt as needed."

PCB teardrops are essentially an "icing on the cake" optimization design, not a core element that determines the circuit function. They are neither a "cure-all" nor a "superfluous item":

• When pursuing reliability and dealing with complex environments, they are a "protective shield" to reduce risks;
• When facing high-density routing and high-frequency/high-speed signals, they are a "detail" that needs careful control;
• In simple circuits and mass-produced products with mature processes, they are an "optimization option" that can be flexibly chosen.

Excellent PCB design is never about blindly piling on features, but rather precisely adapting to product needs. Mastering the applicable scenarios and design techniques of teardrops is essential to finding the best balance between reliability, performance, and efficiency.