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JANUARY 2022 I DESIGN007 MAGAZINE 31 tive electrification. e resulting solution addresses critical application needs for use in a harsh environment where very demanding, long-term thermal reliability performance, extreme thermal cycling, and very high voltage conductive anodic filament (CAF) formation and electro- migration resistance are required. Finally, the copper finish of the PCB lami- nate is also important. If there is a rough cop- per surface with particles, inconsistencies and contamination, arcing may occur. ese con- centrate the electric field and are more prone to arcing. Key Points • Spacing is crucial for high voltage isolation. • Appropriate trace spacing in a PCB design maintains signal integrity, prevents cross- talk, and prevents the propagation of electromagnetic energy coupling between components. • e IPC-2221A Generic Standard on Printed Board Design provides clearance and creepage tables that assist with setting design rules for high voltage design. • Any metallic print pattern that has sharp edges can cause a high electric field across insulators and a flashover. • High voltage design requires insulation that has high dielectric strength, high resis- tivity to prevent arcing, and a low power factor that reduces heating effects and the possibility of thermal breakdown. • e Comparative Tracking Index (CTI) is used to determine which PCB material type works best for the specific application when selecting dielectrics and insulators for a PCB. DESIGN007 Resources 1. Beyond Design: High-Speed PCB Design Con- straints, by Barry Olney, Design007 Magazine, May 2019 2. High Voltage Power Supply Design Guide for Space, NASA 3. High Voltage Circuit Design Guidelines and Materials, Cadence PCB Solutions 4. High Voltage PCB Design Tips: Materials for High Voltage PCBs, Altium 5. IPC-2221A Generic Standard on Printed Board Design Barry Olney is managing director of In-Circuit Design Pty Ltd (iCD), Australia, a PCB design service bureau that specializes in board- level simulation. The company developed the iCD Design Integrity software incorporating the iCD Stackup, PDN, and CPW Planner. The software can be downloaded at www.icd.com.au. To read past columns or contact Olney, click here.