Circuit Building 101

Step 3 Prebend Leads for Easy Insertion

To avoid stressing the holes and junction between the resistor body and its lead, pre-bend the leads before inserting the part. To do this, line up the resistor on it's board location, grip the lead a little inside with needle nose pliers and then fold the lead over the pliers. The pliers prevent stress from reaching the the connection point between body and lead. You can also use something called a christmas tree to quickly form both leads to the correct size.

Just fyi, for sensitive circuits (ie, military, space), serrated pliers aren't allowed because they might create a divot in the lead that could weaken and fail from vibration.

The "right" way aside, just bending the leads with fingers can work well, too

Comments

[ac-dc]

For practical purposes, bending the leads as shown will work ok, but the best way to do this is to grasp the body of the part with your fingers but not the lead (leaves oil from fingers on it), instead bending the lead with wider, non-serrated duck bill pliers. This not only preserves the lead better but creates a nicer very straight and uniform lead. Again, for practical purposes it may not matter but if you have the duck bill pliers or are looking for tools to buy, it's a better result.

[CuriousInventor.com]

Just to add to the "proper" fire, the most important thing (according to the IPC standards) is making sure the resistor-lead junction isn't stressed. They recommend holding the lead with pliers in between the bend and the body.