6 Practical PCB Design Tips to Avoid 90% of Manufacturing Pitfalls! Even Beginners Can Quickly Get Started

When designing circuits, many people focus all their energy on schematics and component selection, hastily wrapping up the PCB layout and routing stage. The result? Either frequent errors occur during factory production, or the circuit board malfunctions after a short period of use—overheating, signal interference, poor soldering—these problems can actually be avoided in advance through scientific design. Today, we'll break down the core techniques of PCB design to help you quickly create manufacturable, functionally stable circuit boards!

I. Component Placement: More Than Just Neatness, Ease of Soldering and Usability

Component placement is the foundation of PCB design, requiring both adherence to circuit logic and compatibility with production processes. Many beginners only pursue a "neat appearance," neglecting the actual soldering and assembly requirements.

Unified Orientation Saves Time

Placing similar components like resistors and capacitors in the same direction reduces the need for frequent angle adjustments by the machine during soldering, improving efficiency and reducing the probability of cold solder joints and incorrect soldering. Components of different sizes should not obstruct each other.

Avoid placing small components directly below or behind large components. Otherwise, when soldering the large component, the small component will be obstructed, creating a "shadow area" that hinders soldering.

Simplify assembly by categorizing components.
Try to place surface mount (SMT) components on the same side of the circuit board, and concentrate through-hole (TH) components at the top. This avoids repeated flipping during factory assembly, reducing production costs. If two types of components must be used together, consider the additional assembly process costs in advance.

II. Trace Design: Power, Ground, and Signal Routes Must Be Meticulous.

After placing the components, plan the routing of power, ground, and signal traces, as this directly affects circuit stability. Many signal interference and power instability issues stem from routing problems.

Power and Ground Layers on Inner Layers.
Place power and ground layers inside the circuit board, maintaining symmetry and centering. This prevents the circuit board from bending and allows for more precise component positioning. When powering chips, use thicker traces and avoid daisy-chain connections (connecting components in series) to prevent voltage instability.

Signal traces should be "short and straight." Signal traces between components should follow the shortest possible path; direct connections are preferable to bends. If a component needs to be horizontally fixed, run the trace horizontally for a short distance before turning vertically. This prevents solder flow during soldering from causing component misalignment; conversely, running the trace vertically first can cause the component to tilt.

Trace width should follow current. For ordinary low-current signals (such as digital and analog signals), a 0.010-inch (10mil) wide trace is sufficient. If the current exceeds 0.3 amps, the trace width must be increased; the higher the current, the wider the trace should be to prevent overheating and burnout.

III. Isolation Design: Digital, Analog, and Power Supplies Should Be Separate.

High-voltage, high-current power supply circuits can easily interfere with sensitive control or analog circuits, leading to the "signal jitter" problem many encounter. Proper isolation significantly reduces interference.

Power Ground and Control Ground Should Be Separate. Each power supply's power ground and control ground should be routed separately, not mixed together. If a connection is necessary, it should only be made at the end of the power path to avoid interference conduction. Strict Isolation of Digital and Analog Circuits

If the circuit board contains digital circuits (such as microcontrollers) and analog circuits (such as sensors), they should be laid out separately, and proper impedance paths should be provided for the ground plane of the intermediate layer. Analog signals should only travel on analog ground and should not cross with digital ground to reduce capacitive coupling interference.

IV. Heat Dissipation: Don't Let Heat Destroy Your Circuit Board

Many circuit boards experience performance degradation or even burn out after a period of use, most likely due to inadequate heat dissipation. This is especially true for power components, where heat buildup can severely impact their lifespan.

Identify the "Heat Giants"

Check the component's datasheet for its thermal resistance (TRT) parameter. Lower TRT results in better heat dissipation. Keep high-power components (such as transistors and power chips) away from sensitive components, and add heat sinks or small fans if necessary.

Hot Air Pads are Key

Through-hole components must use hot air pads. These slow down the heat dissipation of the pins, ensuring sufficient temperature during soldering and preventing cold solder joints. Additionally, adding "teardrop" pads at the connection points between pads and traces strengthens copper foil support and reduces thermal and mechanical stress.

Typical Hot Air Pad Connection Method

V. Hot Air Pads: A "Magic Tool" for Solding Defects

Many beginners are unaware of the function of hot air pads, resulting in open circuits, cold solder joints, and poor solder joints, which cannot be resolved by repeatedly adjusting the oven temperature. The root cause of the problem lies in the wiring design.

Large areas of power or ground copper foil heat up slowly and dissipate heat quickly. If the solder leads of small components (such as 0402 packaged resistors and capacitors) are directly connected to large copper foil, the temperature will not reach the solder's melting point during soldering, resulting in a cold solder joint. During manual soldering, the heat is quickly conducted away, also preventing successful soldering.

The principle of hot air pads is simple: connecting the pads to a large area of ​​copper foil via several thin copper strips ensures electrical conductivity while reducing the heat dissipation area. This allows the pads to maintain a sufficient temperature during soldering, ensuring the solder adheres firmly to the pads.

VI. Design Check: Don't Skimp on the Final Step

After completing the design, always perform a double check; otherwise, even small errors can render the entire circuit board unusable.

First, run "rule checks": Use the Electrical Rule Check (ERC) and Design Rule Check (DRC) functions in the design software to check trace width, spacing, short circuits, unrouted networks, etc., to ensure compliance with manufacturing requirements.

Second, verify signal-by-signal: From schematic to PCB, check the connection of each signal line to avoid omissions or errors. Use the software's shielding function to confirm that the layout matches the schematic.

Conclusion

PCB design may seem complex, but its core revolves around "manufacturability" and "stability." Properly placing components, ensuring short and wide traces, implementing good isolation and heat dissipation, utilizing hot air pads effectively, and finally, conducting a thorough check—these six steps will help you avoid most pitfalls.

Beginners don't need to strive for perfection at the start. Master these fundamental skills first, then optimize them in conjunction with real-world projects. You'll quickly be able to design high-quality circuit boards. Remember, good PCB design not only reduces production costs but also makes circuit performance more stable and extends its lifespan.