QFN pads have a small "nick" in them...do you know why?

[opampsmoker]

Hi
There is a nick in the corners of the big pads of the ACS71240 QFN current sensor
(page 23 of datasheet).
What are they for?. Is it ok if I just make the pads rectangular?

ACS71240 datasheet:

Cost-Effective Shunt Alternative Hall-based Current Sensor - ACS71240

The Allegro ACS71240 is an automotive-grade, current sensor IC with common-mode field rejection and overcurrent detection in a small footprint. It is a cost-effective shunt alternative hall-based current sensor.

www.allegromicro.com

 

[wwfeldman]

i take it you mean the small cut off corner in the PCB Layout Reference View.

no idea what they are for - it isn't a pin 1 indicator, as the device is not symmetric

it is probably to line up with the pads on the bottom view, as they have an edge that
looks like it lines up with the cut off corner.

there is no indication of the dimensions of the cut off corner
the entire pad is 1.27 by 1 mm. the cutoff isn't much at all.

i think you can make the PCB pad rectangular

 

[dick_freebird]

Looks to me like maybe a creepage / field concentration
relief meant to keep the isolation of the current-path
from the "cold side" supply & signal pins, up. Sharp
corners tend to reduce breakdown and lower corona
discharge voltage. The current path has a chamfer
on the package and the PCB footprint seems to
follow, at some oversize.