Handling Components

CHAPTER 15 Handling Components

Resistors must be bent into shape before insertion into the circuit board. The leads always emerge from the body of the resistor—one from each end— and are commonly bent at right angles so they can be inserted into the circuit board. The leads should be a short distance (a few millimeters) away from the end of the resistor body, otherwise there is the possibility of the resistor mate- rial fracturing.

There are two ways to bend resistors. The first is to use a pair of needle- nosed pliers to gently grip the leads and bend them by hand. The pliers not only act as a convenient gripping tool, giving you a nice straight edge, but also and more important, the pliers buffer the lead just enough from the resistor body. The second way to adapt resistors for insertion into the circuit board is to bend just one of the leads along the length of the resistor body and to leave the other lead intact, so that you end up with both leads facing the same direction. Again use the pliers to maintain the small spacing from the resistor body end.

Why the two different methods? The first type of bend is used where there is plenty of space and the resistor can be placed parallel with the board; however, where space is limited and you need to place a resistor between two adjacent pins on a circuit board, the second bend method is used.

Capacitors (disc ceramic types) rarely need bending because the leads already emerge from the same side of the capacitor body. Take care, however, that the leads are not stressed, or the area of the capacitor from which the leads emerge may be cracked. This could happen if the capacitor is pushed flush with the circuit board, so keep the capacitor a short distance away from the board. Where you need to open the lead spacing by bending, use the same needle- nosed pliers to grip the end of the lead nearest the body. By doing so, that part of the capacitor is protected against any strain.

Electrolytic capacitors can be purchased with leads coming from either end of the body (these are called axial lead devices) or with leads coming from the same end of the capacitor (these are called radial lead devices). I use only the radial lead devices to reduce the amount of components I carry.

38 BEGINNING ANALOG ELECTRONICS THROUGH PROJECTS Determining which type of capacitor should be used is logical. Where

surface height is tightly restricted, for example in a pager, the axial type of device would be used. Where plenty of headroom is available, but board space is limited, the radial device should be used because it conserves board area. For simple hobby projects, board space is more valuable and height restrictions are never an issue, so radial devices are used here.

Integrated circuits (ICs) are not handled in the same way as resistors and capacitors but often are inserted into sockets. All you need to do here is to squeeze the leads slightly inward to fit the socket. The socket itself is soldered directly to the circuit board and has no special needs.