Volpiano (Italy)

May 05, 2025

Trade-offs of In-Circuit Testing for LED Defects Detection

ICT test practices and new advanced testing methods

In-circuit testing is crucial for identifying LEDs defects on Printed Circuit Board Assemblies (PCBAs) during manufacturing.

Despite advancements in LED technology, manufacturing inconsistencies can result in defects affecting the stringent standards performance of LED lighting products. Testing PCB assemblies is a vital procedure to ensure compliance with design requirements, thereby decreasing the chances of recalls and upholding the manufacturer’s reputation.

Why is In-Circuit Testing Crucial for the Quality of LED PCB Assembly

Electronic manufacturers perform a range of tests to ensure a zero-defect product supply, and ICT testing, performed at the end of production cycles, plays a crucial role in preventing defects of individual components on the PCB assemblies that may compromise the electronic device performance. This approach also targets printed circuit board assemblies that incorporate LEDs, concentrating on defects detection across multiple measurements, including:

• Electrical characteristics like voltage and current
• LEDs optical properties such as light intensity and color

The in-circuit test method identifies LEDs issues early in the manufacturing process providing consistent testing.

Where do Most LED PCBA Defects Occur

Key issues impacting LED performance include color shifts, irregular light distribution, insufficient brightness or flickering, and incorrect communication with control systems.

Color shifts may lead to noticeable differences in light emitted by LEDs, while improper light distribution can hinder uniform illumination. Problems with brightness and flickering can arise from electrical connection issues, affecting overall visibility. Additionally, the communication protocols used to manage these lights can malfunction, leading to further operational issues.

These problems have direct implications especially in applications where safety is of paramount importance, making in-circuit testing of LED-equipped PCBAs essential for manufacturers to maintain reliability and performance.

Where Are the Challenges in ICT Testing for LED Printed Circuit Board Assemblies

The in-circuit test method typically features LED analyzers that use fiber optic spectrometers and sensors integrated into ICT testers to assess the integrity and performance of each LED on the PCBA. Although this solution is a commonly embraced testing technique and proves to be very effective for PCB assemblies with few LEDs, traditional ICT test that incorporates fiber optics LED analyzers can present certain challenges:

Fiber optics drawbacks. Manufacturers face challenges in accurately measuring LED light parameters due to the complexities of printed circuit board assemblies and the limitations of fiber optic sensors, which struggle to distinguish between single-die and multi-die LEDs and cannot effectively eliminate interference from adjacent lights, leading to measurement inaccuracies.

Intensive data correlation. The use of LED analysers during in-circuit testing generates more data, requiring strong data management to effectively correlate defects, especially since traditional methods separate electrical and optical tests, leading to longer testing times as PCBAs with LEDs grow larger.

Requirements for in-depth measurements. The increasing complexity of LED lighting necessitates deeper measurements and testing, such as full light beam analysis and advanced color parameters, to ensure consistency and compliance.

SPEA has taken the aforementioned factors into account while designing the automatic test equipment aimed at addressing the challenges of in-circuit testing for LED lights, particularly in defect detection.

Where to Find the Best Automatic Testers for LED PCB Assemblies and Modules

SPEA, as a world leader in automatic test equipment and a pioneer in innovations, has engineered the T100L automatic tester, which aims to address these challenges effectively.

This automatic tester simplifies the testing process for PCBAs and modules with numerous LEDs while offering flexibility and cost efficiency. Unlike traditional ICT testers that necessitate fiber optics and spectrometers in the test fixture for different PCB assemblies, the T100L is a fiberless fixture tester that accommodates a variety of LED configurations with minimal setup, thereby reducing downtime and costs. Additionally, it utilizes a flying scanner technology that facilitates measurements of LED micro-spots and accurate spectral composition, effectively overcoming the challenges associated with in-depth measurements.

The T100L represents a comprehensive solution to challenges in testing PCB Assemblies and modules with hundreds of LEDs.

FAQs