Arch Warnecke wrote a definitive article on Air Gap Shielding in 1992 for the EOS/ESD Technology Magazine. (click here for article). Ted Dangelmayer in his book , ESD Program Management, states that rigid packages that provide an adequate air gap are more effective for ESD and physical protection than "stressed" flexible packages.

The use of 3-D packages for appropriate ESD protection is now accepted by many. VPI LLC Sheet Products along with other companies manufacture thermoformable sheet products which can be formed into 3 -dimensional packages that when designed properly with the appropriate air gaps can provide as effective ESD protection as shielding bags. The air gap shielding method so well described by Mr. Warnecke and Dangelmayer before me gives users of ability to optimize their ESD packages for physical proterties without compromising the ESD protection.

In the previous articles listed above, the testing of this method of ESD protection is conclusive. Many companies today make use of the shielding protection of 3-D packages without metal layers.

The telecommunication industry is but one which uses the packages in the most rigorous of environments: THE FIELD. When a telephone technician takes the circuit cards out to the remote locations, the only protection is a thermoformed clamshell. This means the technician in the winter may put the package on the truck seat for convenience. When he arrives at the location he may slide across the seat of the truck, grab the package and head out to the problem cabinet. Talk about a non-ESD safe environment! If these packages work here, they should work anywhere.

While in storage, the packages are treated not so gently (ESD wise). They are taken out of their outer corrugated boxes and stored on shelves only in the clamshells.

 

When determining the type of packaging for an electronic component, the designer may use either shielding bags or thermoformed packages. The decision is one of physicals , not just ESD shielding. These type 3-D packages may be used for almost any electronic component. Some exceptions may be found but they are very few.