In many industrial power systems, failures are often blamed on the semiconductor itself:

“The SCR failed.”
“The diode quality wasn't good enough.”

But in reality, most failures are not caused by the device — they are caused by how the device is used.

This is especially true in high-current, high-voltage applications such as welding power supplies, rectifiers, and industrial heating systems.

Let's look at why discrete power devices fail so often — and why assemblies tend to survive longer in the same environments.

The Hidden Weakness of Discrete Power Devices

Using discrete SCRs or diodes seems simple and flexible.
On paper, the ratings look sufficient.
In practice, several hidden risks appear after installation.

Inconsistent thermal paths

Even with identical devices, small differences in mounting pressure, surface flatness, or thermal grease application can lead to uneven heat dissipation.

一 device runs hotter → degrades faster → fails first.

Uneven current sharing

In parallel configurations, discrete devices rarely share current perfectly.
A slightly lower on-state voltage means one device carries more current — and ages faster.

Assembly variability

Manual assembly introduces variation:

• Torque differences

• Contact resistance

• Cooling effectiveness

Each unit may behave differently, even if the schematic is identical.

Why These Problems Rarely Show Up in Early Testing

Basic tests often show everything is “fine”:

• The system powers on

• Output looks stable

• No immediate overheating

But these tests don't simulate:

• Long-term thermal cycling

• Repeated surge currents

• Real ambient temperature variations

That's why many discrete-device failures happen weeks or months later , not on day one.

 What Power Semiconductor Assemblies Do Differently

A power semiconductor assembly is not just a group of devices placed together.
It is a controlled structure designed to behave as one reliable unit.

Assemblies typically offer:

• Defined and repeatable thermal paths

• Optimized mechanical pressure and contact surfaces

• Balanced current distribution

• Proven mounting and cooling methods

Instead of hoping every discrete device behaves the same, the assembly forces consistency by design .

The Result: Lower Failure Rates, Longer Service Life

In real industrial environments, assemblies usually:

• Run cooler

• Age more evenly

• Survive surges better

• Reduce unexpected downtime

This is why many OEMs see fewer “mysterious failures” after switching from discrete devices to assembled solutions.

The Real Question Isn't “Can I Use Discrete Devices?”

The real question is:

“How much risk am I willing to manage myself?”

Discrete devices can work —
but assemblies shift risk away from the OEM and into a more controlled, proven solution.

When Assemblies Make the Most Sense

Power semiconductor assemblies are especially valuable when:

• Downtime is expensive

• Loads are dynamic or pulsed

• Thermal conditions are harsh

• Consistency across units matters

In these cases, survivability matters more than theoretical flexibility .

Key takeaway

• Discrete devices fail not because they are weak —
  but because real-world conditions are unforgiving.
  Assemblies survive because they are designed for reality, not just ratings.