In the production of high-reliability electronics, quality control is performed not only of the function, but rather of how the function is performed. The burn-in test is a proactive reliability operation of placing the electronic devices, especially the PCBs, under stress conditions, to manifest hidden defects. This ensures against field failures and enables a longer PCB life.
According to manufacturers, a burnin test for PCB is the thermal and electrical stress applied to a completely assembled PCB under production test conditions to screen out latent defects. It is a gold standard for eliminating RMAs and minimizing field failures. In this article, we will understand the burn-in test used in PCB manufacturing industries.
What is a Burn-in Test in Manufacturing?
Burn-in test is a type of stress test wherein the electronic device is deliberately subjected to hot, high temperature, and high voltage levels to make it fail prematurely. It is especially good at catching “infant mortality” problems, defects that would make a device likely to fail soon after it was deployed.
In PCB burn-in testing, the aim is to capture these defects before products are out in the field with customers. The long test could take hours, or even days if the product is critical, depending on the use case.
Key Elements of a Burn-In Test
|
Element |
Typical Range/Requirement |
|---|---|
|
Temperature |
125°C – 150°C (or as per the component). |
|
Voltage |
125%. |
|
Duration |
24 to 168 hours, application dependent. |
|
Monitoring |
Monitoring Usage with Real-time logging for voltage/current spikes. |
|
Environment |
oven, chamber, or dedicated burn-in station. |
Types of Burn-in Tests
Static Burn-in Test
Static Burn-In is one method to discover concealed faults in semiconductor or electronic components without utilizing them. It subjects the components to extremely high voltage and temperatures, even while they are shut down, and no signal or function is being applied.
This technique is mostly applied in detecting faults in product manufacture, such as faulty solder joints or insulation faults. It is usually applied to simple components or comparatively straightforward integrated circuits (ICs).
Dynamic Burn-in Test
Dynamic Burn-In is one of the methods of testing, which tests electronic components for faults by simulating actual conditions. As opposed to static burn-in, it boots up the units and applies test patterns, signals, and workloads in addition to heat and voltage stressing to accelerate potential failure.
It is employed primarily for significant components such as CPUs, memory chips, and integrated circuits to ensure that they function effectively while under pressure, such as repetitive switching or extended usage. It identifies issues that only appear during the usage of the product, with the aim of enhancing quality and longevity.
Power Cycling (Thermal Cycling Burn-in)
Power Cycling (Thermal Cycling Burn-In) checks how dependable electronic components are by switching their power on and off repeatedly, as they would in actual use. It involves switching the power on and off rapidly, with or without temperature changes, to produce heat and movement stress.
This is utilized to determine faults such as cracks in solder joints due to various materials expanding under heat, die attach damage, as well as repeated contraction and expansion connection failures. This process conforms to industry standards such as JEDEC JESD22-A104 for temperature cycling and IPC-9701 for assessing the reliability of PCB assembly.
Accelerated Testing
Accelerated Testing is utilized to forecast how long something will endure through simulating many years of service in just hours or days. It applies techniques such as high temperature using the Arrhenius model to accelerate chemical failures, high voltage to accelerate issues such as electromigration and oxide breakdown, humidity tests such as THB to detect corrosion, and mixed stresses such as HAST, using temperature, humidity, and electric bias.
Key models such as the Arrhenius Equation to forecast thermal failures and Coffin-Manson to forecast thermal cycle failures predict how frequently failures occur. It is critical to ensure semiconductors are up to standard (such as JEDEC) and fit for automotive electronics (such as AEC-Q100).
Comparison Table
|
Test Type |
Stress Applied |
Target Failures |
Advantages |
Limitations |
|---|---|---|---|---|
|
Static Burn-In Test |
High temp (125°C–150°C), elevated voltage, 24–168 hrs. |
Material defects, contamination |
Simple setup, cost-effective for high volumes. |
Doesn’t mimic real operation, may miss dynamic failures. |
|
Dynamic Burn-In Test |
High temp, voltage, and functional signals (clocks/data patterns). |
Operational defects (logic, timing) |
More realistic than static burn-in, detects dynamic defects. |
More complex & expensive than static burn-in. |
|
Power Cycling |
Temp swings (ΔT), high cycle counts (1000s of cycles). |
Solder fatigue, interconnect cracks |
Simulates real-world power transitions, finds interconnect issues. |
Slow, may not cover other failure mechanisms. |
|
Accelerated Testing |
High temp (85°C–150°C), voltage extremes, or environmental stress. |
Long-term wear-out mechanisms |
Fast results, identifies weak design/material issues. |
Requires extrapolation (may not match real use conditions). |
Burn-in Test Process (Step-by-Step)
Test planning & objectives setting
Before even beginning the burn-in test, start with clear goals. This involves such things as deciding how long the test will be, what parts or systems will be tested against, and what types of failure conditions the test is attempting to uncover. The test, depending on the industry (aerospace, automotive, medical), can be customized to comply with or match a specific reliability level/standard. Part of this planning also involves selection of either static or dynamic burn-in, as well as determining the environmental conditions (temperature, voltage, current) to be employed.
Setting up the DUT
The Device Under Test (DUT), typically a complete PCB, is mounted on a dedicated burn-in board or a fixture. These boards are used to accommodate several DUTs and interface them with power, signal inputs, and measurement equipment. Ensure proper seating and stable connections to avoid false failures due to contact issues.
Environmental Conditioning
The burn-in board containing the DUTs is placed in a burn-in chamber or an oven. These chambers are kept at a high constant temperature (usually 85 to 125 degrees Celsius). Humidity can be optionally controlled as well to mimic outdoor environmental conditions. This conditioning operation is highly important because several early-life component failures occur only under those extreme service conditions.
Application of Stress (Electrical & Thermal)
Upon entering the chamber, an electrical stress is applied. For the static burn-in, regardless of input signals, the voltage is always applied as above. In dynamic burn-in, data signals, clock signals, or data patterns are driven into the devices as in use. Power cycling can also be performed where the device is repeatedly cycled from off to on under load, which can be used to identify thermal expansion-related problems and power bumps.
Monitoring During the Test
The performance of the DUTs is constantly checked during the entire burn-in testing. Current draw, voltage levels, thermal data, and other key parameters are recorded in real-time. If any machine exhibits erratic or outside-norm behavior, the flags a potential failure. Surveillance processes can be automated and integrated with algorithms to alert operators of any deviations in real-time.
Duration of the Test
The length of the test varies per application, although typical PCB burn-in tests range from 24 and 168 hours. For mission-critical applications such as satellite electronics or life support systems, burn-in may be even longer. The objective is to subject the device to a period of stress that is long enough to remove a portion of the vector and latent defects, and yet short enough such that good components are not over-aged.
Analysis and Failure Report
Upon completion of the test, all the data is processed and checked to see if any DUTs failed or exhibited any instability. When units fail, they are removed for additional analysis to determine the cause of the failure. This knowledge would be valuable for optimizing manufacturing and design processes.
Final Approval or Rejection
Successfully tested PCB are generally more reliable devices and are either installed or forwarded to system testing. Units that fail may be scrapped, reworked, or sent for failure analysis. The burn-in yield is usually recorded in QA reports for compliance with regulatory standards or internal specifications.
Board-level vs. Component-level Reliability Tests
|
Feature |
Burn-In Test |
Stress Test |
|---|---|---|
|
Purpose |
Separate out early failures. |
Test limits of operation. |
|
Environment |
Simulated elevated stress. |
Extreme conditions. |
|
Test Duration |
Hours to days. |
Minutes to hours. |
|
Failure Analysis |
Yes. |
Sometimes. |
|
Mass Production |
Yes. |
Rarely. |
Conclusion
Burn-in testing is a well-documented method to ensure the reliability of PCBs and electronic products. Whether you’re testing one of them or a whole batch, a burn-in test for PCB guarantees that early defects are detected and removed before they get to end customers. This has the benefit of enhanced customer satisfaction and a dramatic reduction in the costs of returns or warranty claims.
Frequently Asked Questions
What is a burn-in test for PCB?
A PCB burn-in test is a process of testing circuit boards for a certain period under high temperature & voltage conditions to discover early failure.
What conditions are used in burn-in testing?
PCBs are exposed to high temperatures (often 125°C or higher), maximum voltage, and continuous operation to simulate extended use in a short time.
Do all electronic devices need burn-in testing?
Although burn-in testing is not required for every device, it is essential for parts that are used in application-specific devices where reliability is paramount, such as an aerospace or medical device.
Why does PCB fail during burn-in, but it passes function tests?
Functional tests are limited to checking basic operation at standard conditions, while burn-in tests are used to stress the PCB with elevated voltage, temperature, and worst-case loading. Burn-in failures often indicate marginal components, soldering defects, or thermal issues that standard functional tests might miss.
How to avoid common PCB component placement errors?
Employ static burn-in when you are testing simple analog or passive components. Choose dynamic burn-in if you have an MCU loaded PCB, memory chips, or high-speed logic - real signals simulate field conditions more accurately.
