Читать книгу The ESD Control Program Handbook - Jeremy M. Smallwood - Страница 69

PCBs often enter a production process highly charged. They can remain charged for long periods or can become charged as they are transported or go through a handing or assembly process. Voltages on the board up to 1000 V are not unusual, although the measured voltage will typically change with the proximity of the PCB to other objects. A PCB can also have high induced voltage if there is a highly charged insulator or another source of electrostatic field nearby.

If a conductor (e.g. track or component pin) on the charged board touches a highly conductive machine part (e.g. stop pin), a charged board ESD event can occur (Figure 2.17). The PCB can have high effective capacitance, so this type of discharge can be quite energetic.