Mechanical and physical design
Since the PDF is a reference document, use this workflow when you hit a design roadblock: Ipc-2221 Pcb Design Pdf
(Do not treat the above illustrative numbers as authoritative — always consult IPC‑2221 tables for exact values for your class and environment.) Mechanical and physical design Since the PDF is
At 5,000 meters, air is thinner; arc-over happens at 50% of the sea-level voltage. If your product is for a high-altitude city (e.g., Denver or Mexico City), the PDF requires you to multiply internal clearances by 1.5x. Many cheap fabs accept "IPC Class 2" by default
Before sending your Gerbers to a manufacturer (like JLCPCB or PCBWay), compare your layout against the IPC-2221 annular ring requirements. Many cheap fabs accept "IPC Class 2" by default. If your product needs Class 3, you must explicitly tell the fab and present your IPC-2221 compliance report.