AN055
ESD Static Protection Manual
13
or damage to other internal components.
Moisture sensitive components (classified in accordance with IPC/JEDEC J-STD-020,
ECA/IPC/JEDEC J-STD-075 or their equivalents) shall operate in accordance with
IPC/JEDEC J-STD-033 or their equivalents Provisions for documented procedures. IPC-1601
provides guidelines for moisture control, operating, and packaging of PCBs.
3.2.
Physical Damage
Irregular operations can easily damage the chip and the PCB test board, such as component
pins/pads, cracked/shattered/broken connectors, bent or broken terminals, and severe
scratches on the board surface and conductor pads. In addition, chip-level ESD caused by
inattentive ESD protection causes chip circuit P-N junction damage, oxide layer
breakdown/penetration, and sensitive parameter drift.
3.3.
Pollution
Mostly products are contaminated through carelessness or improper handling during the
manufacturing process, leading to soldering and coating problems. Human salts and oils, as
well as unapproved hand creams, are typical sources of contamination. Body oils and acids
can reduce solderability and increase corrosion and dendrite growth. It can also lead to poor
adhesion of subsequent coatings or encapsulations. Ordinary cleaning methods cannot
remove all contamination. It is therefore important to minimise the chance of contamination.
The best solution is prevention, frequent washing, and only taking the edge of the board
without touching the connectors or pads will help reduce contamination. When required, using
pallets and brackets will also help reduce contamination during assembly.
The use of gloves or finger cots can often give the illusion of protection and can be more
contaminated than bare hands for a brief period of time. When using gloves or finger cots,
they should be discarded and replaced frequently. Gloves and finger cots must be carefully
selected and used appropriately.
3.4.
Electronic Components
Even if the components do not have the ESD sensitive marking on them, they still need to be
treated as ESD sensitive components. In any case, ESD sensitive components and electronic
assemblies need to have appropriate EOS/ESD markings for easy identification, refer to
Figure 1-1. ESD Sensitive Symbols and ESD Protective Symbols
. Many sensitive
components will also have their own logo, usually on the edge connector. In order to prevent
ESD and EOS from damaging sensitive components, all operations, unpacking, assembly
and testing should be carried out on an electrostatic protection workbench, refer to
2-1. Series connection and parallel connection of anti-static wristbands
