Why Is My PCB Getting Hot? Common Causes and Solutions

ElecSuppliers Electronics GuideAug 20, 2026

A PCB can become warm during normal operation, but unexpected or excessive heating usually means something in the design, component selection, power path, or thermal management needs attention.

The difficult part is that the hot spot is not always the actual source of the problem. A PCB trace may become hot because too much current is flowing through it, while a nearby component may be heating the board through its package and solder connections.

Finding the source before changing the design can save a lot of time.

Start by Finding the Hot Spot

Before changing the PCB, identify exactly where the heat is coming from.

Check the major power components, MOSFETs, regulators, diodes, resistors, connectors, copper traces, and areas around vias. A thermal camera is useful because it can show whether the heat is concentrated around one component or spread across a current path.

If only one component is significantly hotter than the surrounding area, investigate that component first.

If an entire trace or copper area is heating up, the problem may be related to current density or copper resistance.

PCB Traces Can Get Hot From Excessive Current

One of the most common causes of PCB heating is excessive current through a narrow copper trace.

Every copper trace has electrical resistance. When current flows through that resistance, power is dissipated as heat.

A trace that works perfectly well with a low-current signal may become unsuitable when used to carry several amps.

Trace width, copper thickness, trace length and the acceptable temperature rise all affect the amount of heat generated.

Increasing the copper width or thickness can reduce resistance and help distribute the current over a larger area.

For high-current designs, simply making a trace “look wide enough” is not a reliable design method. The expected current and allowable temperature rise should be considered during PCB design.

Power Components May Be the Real Heat Source

Sometimes the PCB itself is not the primary problem.

Voltage regulators, MOSFETs, power diodes, inductors and other power components can generate substantial heat.

For example, a regulator converting a higher input voltage to a much lower output voltage may dissipate significant power even when the output current appears reasonable.

The important value is not only the current rating of the component but also the power it actually dissipates under the operating conditions.

If a component is converting electrical energy into heat, improving the PCB alone may not solve the problem.

Insufficient Copper Can Limit Heat Dissipation

Copper is useful for more than carrying electrical current.

Large copper areas can also spread heat away from components and into the PCB.

A power device connected to a small copper area may operate at a higher temperature than the same device connected to a larger copper region.

Thermal copper areas should therefore be considered when placing components that generate heat.

However, simply adding copper everywhere is not always practical. The copper must also work with the electrical layout, signal requirements and manufacturing rules.

Thermal Vias Can Help Move Heat

For some surface-mounted power components, thermal vias provide a path from the component's PCB pad to an internal or bottom copper layer.

These vias can transfer heat away from the component and spread it over a larger copper area.

The number, diameter and arrangement of thermal vias depend on the component package and PCB construction.

Thermal vias should be designed according to the component manufacturer's recommendations rather than added randomly.

Poor Component Placement Can Create Hot Spots

Component placement can have a major effect on PCB temperature.

Placing several heat-producing components close together can create a local hot zone. The combined heat may raise the temperature much more than any individual component would produce on its own.

Heat-generating components should be considered as part of the overall thermal layout.

Sensitive components such as temperature sensors, precision references and some analog circuits may also need to be kept away from strong heat sources.

Connectors and PCB Contacts Can Also Heat Up

A connector can become hot when too much current passes through its contacts.

A loose connection, damaged contact or unsuitable connector rating can increase contact resistance. The resulting heat may be concentrated around the connector rather than distributed across the PCB.

This is particularly important in power supplies, battery systems, motor control boards and other high-current applications.

If the connector is significantly hotter than the surrounding PCB, inspect the connector rating and physical connection before redesigning the entire board.

PCB Material Matters at Higher Temperatures

The PCB material itself also has temperature limits.

For applications exposed to continuous high temperatures, the thermal properties of the laminate should be considered during material selection.

The glass transition temperature (Tg), decomposition temperature and thermal expansion characteristics can become important when a board operates under demanding thermal conditions.

Choosing a higher-temperature material does not remove the original heat source, but it can provide a more suitable material system for the operating environment.

When the Problem Appears After Reflow

A PCB that becomes warped, damaged or unreliable after assembly may have a different thermal problem from a PCB that simply runs hot during operation.

Reflow soldering exposes the board to a controlled high-temperature profile.

If the board design, material selection, copper distribution or manufacturing process is unsuitable, thermal stress during assembly can contribute to defects.

This is why operating temperature and assembly temperature should be treated as separate design considerations.

A Practical Way to Troubleshoot PCB Heating

When a PCB runs hotter than expected, check the problem in this order:

First, identify the hottest location.

Then determine whether the heat comes from a component, trace, connector or another part of the board.

Next, measure the actual voltage and current under the conditions where the heating occurs.

After that, estimate the power being dissipated by the suspected component or current path.

Finally, review the PCB layout, copper area, trace dimensions, thermal vias and component placement.

This approach is usually more useful than immediately increasing the trace width or adding a heatsink.

When a PCB Redesign Is Necessary

A redesign may be necessary when the temperature remains above the component or system's acceptable operating range.

Possible changes include using wider or thicker copper, increasing thermal copper areas, adding thermal vias, changing component placement, selecting a component with lower power dissipation, improving airflow or choosing a more suitable PCB material.

The correct solution depends on where the heat originates.

A hot PCB is therefore not automatically a PCB manufacturing problem. It may be caused by electrical loading, component losses, thermal layout, mechanical connections or the surrounding system.

Finding the actual heat source first is the most reliable way to decide what needs to change.