【仪测高下】高频高速PCB测试

Core Viewpoint - The article emphasizes the critical role of high-frequency and high-speed PCBs in various applications such as AI, high-speed communication, data centers, and consumer electronics, highlighting their performance stability and reliability as key factors for system signal integrity and operational efficiency [1]. Upstream, Midstream, and Downstream Summary - Upstream: Material suppliers provide high-performance substrate materials, where key parameters like dielectric constant (Dk/Df) and copper foil surface roughness (SR) directly impact PCB signal transmission performance [2]. - Midstream: PCB manufacturers utilize the supplied materials to produce multilayer high-frequency and high-speed circuit boards, catering to complex application demands through advanced manufacturing processes [2]. - Downstream: End customers integrate high-frequency and high-speed PCBs into various electronic devices, including AI servers, data centers, communication equipment, and smart terminals [2]. Key Testing Indicators for High-Speed PCBs - The main testing projects for PCBs include frequency domain S-parameters, time domain impedance, rise time, skew, eye diagrams, and material characteristics, which collectively assess transmission performance, impedance characteristics, timing characteristics, and signal integrity [3]. S-Parameter Testing - S-parameter testing is a routine evaluation method for high-speed PCBs, allowing designers to assess transmission and reflection performance, with a particular focus on insertion loss performance indicated by Sdd21, which reflects signal attenuation during transmission [5]. Time Domain Impedance Testing - Time domain impedance testing is crucial for evaluating the impedance characteristics of high-speed PCBs, providing insights into transmission line characteristics and impedance matching [8]. Rise Time and Skew Testing - Rise time testing measures the signal's rise time, reflecting transmission speed and response time, while skew testing measures the time delay differences between different signal lines, assessing signal synchronization and timing accuracy [10]. Eye Diagram Testing - Eye diagram testing is essential for evaluating signal integrity in high-speed PCBs, allowing for the observation of noise, jitter, and distortion issues [12]. Dk/Df Testing for PCB Copper Clad Materials - Dk (dielectric constant) and Df (loss factor) testing of PCB copper clad materials are vital for assessing dielectric performance and energy loss characteristics, with common measurement methods including resonant cavity methods [14]. De-embedding Applications and Methods - De-embedding is crucial for accurate PCB testing, as it eliminates the influence of fixtures on the test results. Various de-embedding methods are employed, including basic de-embedding, advanced time-domain de-embedding, and specialized methods like TRL and Delta-L [16][18]. New Challenges and Testing Requirements - The testing of high-frequency and high-speed PCBs faces new challenges due to the continuous development of high-speed technologies, necessitating comprehensive consideration of material properties, signal integrity, and compliance with standards [23][27]. Specific Challenges in High-Frequency Testing - The emergence of resonant issues in PCB lines at high frequencies and the need for improved de-embedding methods for frequencies exceeding 40GHz are highlighted, with ongoing research into Delta-L measurement solutions for 67GHz [24][26]. Conclusion - The industry must innovate and optimize testing solutions to meet the evolving demands of high-speed applications, ensuring that PCB designs comply with the requirements of 5G, AI, and supercomputing [27].