In the electronics industry, "cost reduction" is a constant theme. Engineers' ingenuity can reach the heavens to save a few cents—for example, using PCB traces instead of antennas is already a common practice. These carefully designed traces on the circuit board take on the crucial task of signal reception, simplifying materials and saving on antenna purchase costs. Many actual projects use this; see these real-world examples:

But a recent practice circulating in the industry has completely shocked everyone: someone actually wants to replace fuses with PCB traces! That's right, the critical component responsible for "overload melting and safety protection" in a circuit is being replaced by copper foil traces? Is this a clever money-saving trick, or a gamble on safety? Let's break it down today.

First, the conclusion: Technically feasible, but not recommended in practice!

How is it technically possible? Relying entirely on copper foil for current control

Using PCB traces instead of fuses works on a simple logic: utilizing the current-carrying capacity of copper foil, by precisely controlling its width, length, and thickness, it operates stably under normal current. If the circuit is overloaded and the current exceeds the copper foil's capacity, it will overheat and melt, thus cutting off the circuit.

For example, common PCB copper foil thickness is 35μm. When the trace width is 1mm, each millimeter of copper foil can carry approximately 1A of current. If a circuit requires 5A protection, theoretically, a 5mm wide trace would suffice (in practice, adjustments must be made based on length and heat dissipation). Furthermore, the industry has specialized calculation tools that can precisely calculate the required parameters, such as the number of vias and temperature rise needed to carry 10A of current.

These fatal risks should never be avoided, no matter how much cost-saving measures are required!

While technically feasible, replacing fuses with PCB traces is akin to installing a "time bomb" in the circuit, with these five risks being unavoidable:

1. Complete Failure: Repair Equals Board Replacement. A standard fuse can be easily replaced, saving time and money. However, a PCB trace that blows cannot be replaced individually, potentially rendering the entire board unusable, increasing maintenance costs and wasting resources.
2. Significant Safety Hazards: Risk of Fire and Short Circuits. When the trace blows, copper foil may splatter metal balls, causing a secondary short circuit. If the copper foil design is inappropriate (too long or too short), it may either fail to melt in time, leading to overheating and fire on the input line, or carbonize the PCB, damaging surrounding components.
3. Uncontrollable Melting Effect. Standard fuses can precisely achieve "fast melting" or "slow melting," but PCB traces, made only of copper foil, have poor response speed and consistency. They may fail to melt when they should, or burn out when they shouldn't.
4. Failure to meet safety regulations prevents product launch. Exposed copper foil is susceptible to static electricity, moisture, and temperature changes, resulting in poor stability. Furthermore, many countries and regions have safety standards (such as those for home appliances and automotive electronics) that either prohibit or strictly limit this design, making it highly unlikely to pass approval.
5. High design complexity may lead to cost overruns. It's not simply a matter of drawing a line! To ensure effective fusing, precise parameter calculations are required, and single-point zigzag traces must be used instead of serpentine traces (to reduce heat dissipation impact). Manufacturing tolerances are extremely high; even slight errors can lead to protection failure, thus increasing production costs.

Standard fuses offer a wide range of options, with different specifications suitable for different scenarios. Common models like JSR30 and SR60 are safe and reliable.

Finally, a reminder: Cost reduction must not cross safety red lines.

While seemingly saving money on a single fuse may appear advantageous, it carries the risk of circuit board scrapping, safety accidents, and failure to meet safety regulations. These losses far outweigh the cost savings.

Therefore, whether it's home appliances, automotive electronics, or industrial equipment, prioritizing standard fuses is the safest approach—they meet safety standards, guarantee effective protection, and facilitate future maintenance. After all, the core of electronic design is "reliability and safety," and blindly cutting costs while ignoring risks will ultimately lead to more harm than good!