ESD main product
The main products used to prevent ESD are wristbands, with curled corduroy and dissipative surfaces or bedding - both must be properly grounded. Additional aids such as dissipative footwear or ankle straps and suitable garments are designed to prevent personnel from accumulating and maintaining a net charge as the electrostatic protection zone (EPA) moves.
The PCB should also prevent ESD from internal and external transport during and after assembly. There are many circuit board packaging products available for this purpose, including shielding bags, shipping cases, and mobile carts. While proper use of the above equipment will prevent 90% of ESD-related problems, in order to reach the last 10%, another protection is required: ionization.
The most efficient way to neutralize assembly equipment and surfaces that generate electrostatic charge is to use an ionizer - a device that blows out an ionized air stream over the working area to neutralize any charge accumulated on the insulating material.
A common paradox is that the charge in this area, such as a polystyrene cup or cardboard box, will be safely dissipated because the belt is carried on the workstation. By definition, the insulator does not conduct electricity, except that it cannot be discharged by ionization.
If a charged insulator remains in the EPA, it will radiate an electrostatic field, causing a net charge to any nearby object, thus increasing the risk of ESD damage to the product. Although many manufacturers attempt to ban insulation from their EPA, this method is difficult to implement. Insulation is a part of everyday life - from the comfort of the operator's foam pad to the plastic cover.
Due to the use of ionizers, manufacturers can accept the fact that some insulating materials appear in their EPA. Because the ion generation system continuously neutralizes any charge buildup that may occur above the insulator, they are a reasonable investment for any ESD plan.
There are two basic forms of ion generating devices in standard electronic assemblies:
*Desktop type (single fan)
* Over-the-top equipment (in a single over-the-top unit with a range of fans)
There are also indoor ion generators, but now they are mainly used in the clean room environment.
The choice depends on the size of the area that needs to be protected. The desktop ionizer will cover a single working surface, while the overtop ionizer will cover two or three. Another advantage is that the ionizer also prevents dust from electrostatically attaching to the product, potentially degrading the appearance.
However, without proper testing and monitoring of the effectiveness of ESD equipment, no protection plan is perfect. Leading ESD control and ionization experts report examples of manufacturers that use failed (and therefore useless) ESD devices without knowing their failure.
To prevent this, in addition to standard ESD equipment, ESD suppliers offer a variety of constant monitors that automatically alert if a performance is out of specification. The monitor can be used as a stand-alone unit or connected together in a network. There is also network software for automatic data collection that displays system performance for operators and workstations in real time.
The monitor simplifies the ESD program by eliminating many of the daily tasks, such as ensuring proper measurement of the belt every day, balancing and proper maintenance of the ionizer, and no damage to the workbench grounding point.
Related article: Anti-static products