Rev 4.0

33

PD-97528

IR3856MPbF

Solder Resist

IR recommends that the larger Power or Land Area pads are Solder Mask Defined (SMD.) This allows

the underlying Copper traces to be as large as possible, which helps in terms of current carrying

capability and device cooling capability.

When using SMD pads, the underlying copper traces should be at least 0.05mm larger (on each edge)

than the Solder Mask window, in order to accommodate any layer to layer misalignment. (i.e. 0.1mm in X

& Y.)

However, for the smaller Signal type leads around the edge of the device, IR recommends that these are

Non Solder Mask Defined or Copper Defined.

When using NSMD pads, the Solder Resist Window should be larger than the Copper Pad by at least

0.025mm on each edge, (i.e. 0.05mm in X&Y,) in order to accommodate any layer to layer misalignment.

Ensure that the solder resist in-between the smaller signal lead areas are at least 0.15mm wide, due to

the high x/y aspect ratio of the solder mask strip.