Lead skew can cause process problems by causing a portion of the lead to land off of the solder pads. A small amount of skew can cause up to 50% of the lead to be off of the pad due to tolerance build up between the connector centerlines and board pad centerlines.

The gull-wing foot on surface mount leads can be out of square due to improper forming, improper assembly into the insulator or damage during handling or shipping. The maximum heel to toe angle is usually specified as 0 to 7 degrees.