Disclaimer: This review is for informational purposes. I cannot provide a direct download link to the copyrighted PDF. Please visit the official IPC website (ipc.org) to purchase the standard.
Electrical requirements
The PDF states that for reliable plated-through holes, the board thickness divided by the hole diameter should not exceed 10:1. For high-reliability (Level A), stay below 8:1. Ipc-2221 Pcb Design Pdf