A Unified Approach to In-Circuit Testing (ICT) and Functional Test (FCT) Integration

When it comes to manufacturing electronics, two types of tests are commonly used to ensure the quality and reliability of the products. These are known as In-Circuit Tests (ICT) and Functional Tests (FCT). Although distinct from each other, these testing methods are complementary and serve specific purposes in the production process.

ICT (In-Circuit Testing) is a process used to test the integrity of individual components and connections on a Printed Circuit Board (PCB). This process involves using specialized test probes or a bed of nails to check for electrical continuity, shorts, opens, and component values. By examining the electrical characteristics of each component and traces on the PCB, ICT detects potential manufacturing defects such as soldering errors, incorrect component placements, or faulty components. 

A functional Test (FCT) is a test that assesses the overall functionality of a finished electronic product through a range of test scenarios. This test is designed to mimic real-world usage conditions. FCT involves testing features such as power consumption, communication interfaces, and overall system performance. The purpose of FCT is to verify that the product performs its intended functions correctly and meets the design specifications. 

This white paper explores the possibility of creating a unified testing solution that bridges the gap between ICT and FCT.. 

ICT is used in the initial stages to detect any discrepancies that could potentially cause problems in the final product. On the other hand, FCT is used toward the end of manufacturing to ensure that the assembled products meet quality and performance standards before they are shipped to customers. Together, ICT and FCT provide comprehensive testing of electronic products. 

ICT identifies manufacturing defects early in production, reducing the cost of reworking or scrapping faulty boards. Additionally, ICT provides comprehensively tests individual components and PCB traces, ensuring thorough assembly inspection. On the other hand, FCT verifies the assembled product's overall functionality identifies defects not detectable through ICT, such as software issues or mechanical failures. FCT also simulates real-world usage scenarios, providing insights into the product's behavior under normal operating conditions.

The complexity of modern automotive systems, which often involve intricate electronic components and interconnected subsystems, underscores the need for thorough testing. For example, the electronic control unit (ECU) plays a significant role in today’s vehicles, managing a diverse array of functions ranging from critical engine and power steering control to luxurious amenities like power windows and seats, as well as security features such as door locks, the electronic control unit (ECU) also oversees vital safety components including airbags and basic active safety features like automatic emergency braking. Due to its safety-relevant characteristics, ECU must ensure reliability under all conditions.

ECUs receive inputs from various vehicle parts, depending on their function. They then communicate with actuators to perform actions based on the received input. Consequently, functional testing (FCT) is the common testing method for ECUs during manufacturing. Automotive manufacturers stimulate the ECUs via their hardware and software interfaces and evaluate their reactions upon receiving input in various testing environments. 

However, in pursuit of faster throughput and higher efficiency in the automotive industry, manufacturers have realized that relying solely on FCT for the testing process is insufficient. ICT is crucial to have in the testing process to prevent defects in individual components, such as short circuits and incorrect component values, before advancing to the FCT stage. It reduces the cost of rework and FCT's failure rate.

While having two separate testing systems on a production line improves efficiency, productivity, and quality control, it also increases the footprint and requires additional workforce to supervise each system. Moreover, the maintenance and calibration of two separate testing systems can increase operational costs. As automotive manufacturers strive to balance efficiency with quality assurance, finding a unified testing solution that integrates ICT and FCT while minimizing challenges becomes increasingly imperative.

Integrating ICT and FCT test functionalities requires meticulous planning to ensure compatibility, scalability, and performance. Architectural decisions must also address factors such as signal integrity, noise immunity, and environmental conditions to guarantee accurate and reliable test results.

Modular architectures offer flexibility and scalability by allowing individual subsystems (e.g., ICT module, FCT module) to be independently upgraded or replaced. On the other hand, Unified testing platforms consolidate ICT and FCT capabilities into a single hardware/software framework, simplifying system configuration and operation but potentially limiting flexibility and expandability. Hybrid approaches combine elements of both modular and unified architectures, striking a balance between flexibility and integration.

Keysight’s i7090 adopts a hybrid approach to allow various combinations of ICT and FCT systems in one system, such as only including FCT systems or ICT systems or having both systems. 

The i7090 Massively Parallel Board Test System boasts 20 parallel ICT cores, enabling engineers to simultaneously test multiple Units Under Test (UUTs) without needing multiple systems. It facilitates various tests, including resistance, capacitance, and inductance measurements, while also seamlessly integrating flash programming alongside ICT through innovative technology.

For FCT, the i7090 Massively Parallel Board Test System utilizes the TS-8989 PXI Functional Test System, which allows users to customize their own solutions on an automated inline system. It provides space for instrument placement and interface methods, including test fillets, ensuring easy integration into the test fixture.

Overall, the i7090 Massively Parallel Board Test System offers manufacturers a streamlined solution that enhances throughput and reduces footprint without separate systems.