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Understanding Burn-In Boards: Functionality, Uses, and Desgin

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To test the reliability of electronic components, manufacturers use a PCB called a burn in board. It helps check the components for early failure, ensuring their quality and reliability. We wrote this post to explain how the PCB works, its design characteristics, and why semiconductor companies need it when conducting product quality checks.

What is a Burn In Board?

The burn in board (BIB) is a type of PCB used in the burn in test. This test checks the service life of electronic components. It involves using electrical and thermal loads to stress components and trigger failure modes.

The typical BIB contains testing sockets and connections. Because it undergoes long periods of exposure to heat, it uses a material that can withstand higher temperatures.

It also has traces and support components like resistors, capacitors, and other devices. These parts must also resist damage when electrically or thermally stressed.

As you can see, the BIB differs from a conventional PCB in design and construction. The following section examines how manufacturers use it to run product reliability checks.

Operating a burn in board tester
Operating a burn in board tester
Resource: https://www.youtube.com/watch?NfNlr9cuzs

What Does a Burn In Board Do?

The burn in board PCB holds the components under test. In other words, it serves the function of a testing jig or fixture, allowing the testing expert to simulate (and exceed) end-use conditions. Here is a brief description of how it helps check component reliability and lifespan.

  • The BIB is mounted with components in the test sockets and placed in the heating chamber. Here, it gets subjected to gradually increasing temperatures or heat cycles from low to high.
  • It’s also powered to electrically stress the components. The voltage hastens damage by higher currents, while the heat induces mechanical stress.
  • At the end of the process, a testing head inserted into each testing socket identifies working and non-working components.
  • Failed devices provide information about the cause of damage, allowing the manufacturer to correct flaws.
  • The test can last hours or days, depending on the components’ reliability and requirements.
Burn in test curve
Burn in test curve
Resource: https://www.mdpi.com

Understanding Burning In Testing

Burn in tests accelerate or shorten early failure rates from weeks or months to only a few days or hours. As we have seen, it works by introducing electronic components to thermal stress and voltage cycles. Two main testing procedures are employed: static and dynamic.

Static Test

In static testing, the components receive no signal inputs, only voltage, and higher temperatures during the testing process. This method is simple to carry out. However, it provides limited information about component failure.

Dynamic Test


The dynamic test involves more than thermal and electrical loads. Each component receives a signal input. As a result, the failure data obtained is more comprehensive. The test checks components for more demanding applications.

The burn-in oven where the accelerated component aging takes place
The burn-in oven where the accelerated component aging takes place
Resource: https://youtu.be/C2vUkqQIMug?

Importance of Burn in Board Test

This test is crucial in the electronics industry. It lets component manufacturers determine if a batch’s products can operate reliably without failing prematurely.

The results of the burn in board test help plot what’s called the “bathtub curve.” This curve shows the failure characteristics of the products under check.

A faulty part will usually fail in the early stages of its application environment. Those that survive this period are quality enough to last through their estimated lifespans.

After the test, engineers can identify a product’s design and fabrication flaws for correction. The good thing is that correction happens before the product can reach its application device or system.


It helps companies prevent expensive product recalls or warranty claims. That’s in addition to avoiding unnecessary PCB or device repairs caused by failed components.

Burn in test diagram showing the process's setup
Burn in test diagram showing the process’s setup
Resource: https://www.semanticscholar.org/paper

Burn In Test Board Design

PCB fabricators must follow specific burn in board design rules, or the device may not serve the intended purpose. That includes the choice of materials, circuit layout, and configuration requirements.

Board Material

The burn in board assembly must operate at extreme heat levels. That calls for a material with a higher Tg temperature value. Special FR4s with Tg values above 180°C are required.

For tests involving higher temperatures than 125°C, a substrate that can bear more heat is necessary. Various materials are available. One of them is polyimide, especially when checking devices for demanding applications.

Circuit Layout and Configuration

The design engineer must carefully select the BIB components based on the required function. The parts must be sturdy enough to withstand extreme heat and voltage loads.


In the layout stage, the designer must adequately space components to avoid thermal and other issues. Other crucial design requirements include separating power and signal layers with ground planes.

BIB PCB assembled with semiconductor components
BIB PCB assembled with semiconductor components
Resource: https://www.researchgate.net

Burn In Board Design Guidelines

The BIB PCB must not fail during the testing process’s extreme temperatures. As such, its design varies slightly compared to a standard PCB. The following rules apply across the different types of the BIB:

1. Use components rated higher than the testing conditions. This requirement prevents the BIB from failing in the extreme temperature of the testing chamber.

2. Ensure the correct stack-up for the specific testing needs. BIB layers can range from two to up to 10 or more depending on the signal, power, and ground plane requirements.

3. Use thicker or broader traces. The device must be able to carry the higher currents that characterize the electrical loads of the testing process.

4. Testing the BIB for circuit shorts and opens is crucial, as these can cause it to malfunction and not produce the required results.

5. Simulate the BIB operation before validating it for fabrication. It confirms its workability, ensuring everything is set correctly for the needs of the test.

Conclusion

The burn in board is a crucial device in the electronics industry. Manufacturers use it for the “burn in test,” a process that checks the early failure rate of electronic components. This test validates the quality and reliability of electronic and semiconductor components before their use in various devices and systems.

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