Since "IPC-2221" is a copyrighted industry standard, a legitimate, official "free PDF" of the full document does not exist legally. It must be purchased from the IPC (Association Connecting Electronics Industries).
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. Ipc-2221 Pcb Design Pdf