PCBs
Modern manufacturing strategies fuel in-circuit test advancements
By Choon-Hin Chang, product manager, Keysight Technologies P
rinted circuit board assembly (PCBA) manufacturers rely on in-circuit test (ICT) systems to detect manufacturing processes and component defects.
Manufacturers prefer ICT systems for testing electronic assemblies because they are easy to programme, have extensive fault coverage, rapid test throughput, low false fail rates, and outstanding diagnostic accuracy. In recent years, the landscape of ICT systems has undergone a significant transformation, driven by advancements in PCBA technologies, evolving test philosophies, and shifting manufacturing business models. These changes have created an array of new and diverse requirements for ICT manufacturers to accommodate. The challenges include diminishing test point access in specific product sectors, with a growing threat from the increase in low-voltage differential signalling integrated circuits used for high-speed signalling and ball grid array devices. These complexities motivate ICT manufacturers to innovate and adapt, preserving the effectiveness and relevance of their testing solutions. In this article, we explore the latest advancements in ICT that are revolutionising manufacturing tests by increasing coverage, reliability, and throughput in in-circuit production tests, ultimately driving down costs.
The introduction of ICT systems The introduction of ICT systems in the late 1970s marked a milestone in electronics manufacturing. The landscape at that time was vastly different from today’s. PCBAs used through-hole technology, and components sat on a single side of the board. The prevailing voltages powering these boards were typically no more than 15 volts. During this era, functional tests for manufacturing were complex and time-consuming. Precision and efficiency are essential in
40 March 2025
Figure 1. Bed-of-nails ICT fixture
electronics manufacturing. As technology advances and consumer demands evolve, rigorous testing methodologies are becoming increasingly crucial. Among these methodologies, ICT stands out as a way to ensure the quality and reliability of PCBAs. The advent of ICT systems transformed PCBA manufacturing. The process shifted from assessing the board’s functionality to evaluating the functionality of individual parts and ensuring the integrity of the assembly process.
ICT systems assess the board’s functionality by employing a bed-of-nails test fixture, as shown in Figure 1. In a bed-of-nails test fixture consisting of spring-loaded pins, the pin positions align with the PCBA’s test point. When the tester places the PCBA under test on the bed and presses down, the pins make electrical contact with test points or component leads on the PCBA. These contacts enable the tester to inject signals and power at specific points on the PCBA while measuring electrical properties and responses, such as resistance, capacitance, inductance, and voltage levels.
With robust electrical test access and innovative guarding and voltage-forcing techniques, each component can undergo
Components in Electronics
individual testing. These readings help verify component connections and check for manufacturing defects like open circuits, short circuits, or incorrect component values. The underlying principle is that manufacturers can trust the board’s functionality if ICT verifies the correct operation of all components and ensures proper assembly.
Navigating the complexity of testing diversity
As technology advances, printed circuit boards (PCBs) are getting smaller and more complex, making it harder to ensure full electrical test access. Low-voltage differential signalling integrated circuits used for high-speed differential signalling, increased use of ball grid array (BGA) devices, and faster input / output speeds are contributing to this challenge. To accommodate this trend, manufacturers are crafting intricate high-density interconnect boards featuring concealed and buried vias, narrower tracks with tighter spacing, and reduced copper availability on the board surface for electrical test access. Manufacturers of ICT systems have not only addressed the technological needs but also adapted to align with changing testing philosophies and business drivers. ICT vendors
have encountered challenges in meeting the diverse needs of various manufacturers, each of whom specifies unique requirements for its ICT system and holds distinct expectations regarding system functionality. For instance, low-margin manufacturers prioritise cost- effective ICT solutions. Manufacturers producing reliable, intricate products require comprehensive fault coverage and extensive pin count capacity. High-volume manufacturers demand increased test throughput and manufacturers employing outsourcing models seek equipment compatibility.
Over time, ICT vendors have addressed conflicting demands by providing varied tiers of ICT systems. Figure 2 illustrates the strategy that empowers manufacturers to precisely procure the required test capabilities, allowing for scalable adjustments without necessitating changes to the tester.
However, if the manufacturer operates only a manufacturing defect analyser (MDA+) class tester, it may struggle to test complex PCBAs because of limited capabilities. Conversely, choosing a high-performance ICT platform could be excessive for simple PCB assemblies, where advanced features are unnecessary and programme development demands highly skilled operators.
www.cieonline.co.uk
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56
