Question 1

How many vias are needed for a high-current connection?

Accepted Answer

A single standard via (0.3 mm drill, 25 μm plating) can typically handle 0.5–1.5A depending on acceptable temperature rise. For higher currents, use multiple vias in parallel—each via adds its cross-section to the total. For example, a 5A connection might require 4–6 standard vias. Place them close together to minimize trace length between vias.

Question 2

What is the difference between via current capacity per IPC-2221 and IPC-2152?

Accepted Answer

IPC-2221 treats vias similarly to internal traces using empirical constants. IPC-2152 provides more detailed thermal analysis considering board stackup, copper plane proximity, and via aspect ratio. IPC-2152 generally yields higher allowable currents for vias near large copper planes due to better heat spreading, giving more realistic results for modern multilayer PCBs.