There are several causes that lead to the high heat of PCB:
1. Component Malfunction Causing Dissipation
One common cause of high heat in a PCB is that one component within the PCB malfunctions and dissipates, failing to generate the amount of power it typically produces. When this happens, the surrounding components have to generate more power to compensate. Generating more power leads to the risk of overheating.
2. Through-Hole Interference
Through-hole components and heat-sink components are the components of the PCB that supply power. They generate heat and dissipate it into the air. If a heat sink is soldered incorrectly, or if a different component of the PCB is interfering with the through-hole, the other components will generate more heat than usual to compensate. This scenario also leads to a risk of overheating.
3. Surface-Mount Device Distance
Surface-mount devices (SMDs) connect to the PCB in the same way through-hole components do. They allow for a smoother flow of current through the through-hole and heat-sink components. But the through-hole components and the SMDs must be positioned at the correct distance from one another. If they are too far away, the current will have farther to travel. The extra time it takes the current to travel can cause the receiving components stay cool for too long. When that happens, other components may overheat to compensate.
4. High-Frequency Circuits
High temperatures are particularly likely in applications that make use of high-frequency circuits. The reason is that the generation of more power naturally produces more heat.
Radio-frequency circuits, for example, represent a fast-growing sector in PCB engineering. These circuits are highly complex but have many useful applications, from wireless security in medical and industrial products to smart phones. These high-frequency circuits tend to generate tremendous amounts of heat, so special design techniques are necessary for these types of PCBs.
5. Lead-Free Solder
As a whole, the PCB industry is moving toward the restriction of hazardous substances (RoHS). RoHS PCBs use lead-free solder, and lead-free solder requires high temperatures so it can flow freely.
How to prevent high temperature of PCB?
1. Heat Sinks
A PCB is basically a heat-generating factory because of all the heat-producing components it contains. The PCB needs some way to dissipate all that thermal energy. Generally, the answer involves heat sinks. Heat sinks dissipate the heat safely so it will not build up and damage the board.
Most electronic devices contain fans for cooling, and part of the purpose of those fans is to help cool PCBs. Cooling fans disperse heat out of electronic devices while letting cool air in, helping to prevent overheating and extend the PCB’s lifespan and performance.
3. Considering Materials and Components
Choosing heat-resistant materials is one of the most effective strategies for reducing heat in a PCB. For example, heavy copper PCBs constructed with thick copper plates make excellent choices for their durability and ability to withstand high temperatures. They handle higher levels of currents, resist higher temperatures for longer amounts of time and provide for stronger connection points than standard PCBs. For these reasons, they are particularly useful in automotive, aviation, heavy machinery and power converter applications and other heavy-duty environments.