ESD protection strategies include packaging and shipping
Many times a special packaging solution needs to be created for ESD sensitive products. Electrostatic Discharge (ESD) is a phenomenon that most of us experience just about every day. One example is walking on a carpet in stocking feet. Sometimes this causes a charge to be built up on our body that will discharge when we touch a metal door knob. Stockings that cling to clothing after coming out of dryer is another example. Perhaps the most spectacular example of ESD is lighting. In most cases when an electrostatic discharge event happens, it is barely perceptible.
ESD happens when two materials that have different propensities for ion attraction come in intimate contact. One material will gain electrons and the other material will lose electrons. The material that attracts becomes positively charged and the material that loses becomes negatively charged. Opposites attract so that is why dissimilar materials will cling to each other. If everything that is in the dryer is 100% cotton, then there will be no clinging problems, but throw a polyester stocking in the bunch and you will see clinging.
When the buildup of charge is great enough, a discharge can take place without intimate contact; this is when you will see or feel a spark. The discharge is electrons from the higher energy object flowing to the lower energy object. The higher the energy level that is built up on the surface, the longer the spark. The energy level essentially needs to exceed the natural dielectric strength of air to spark to another surface. The amount of energy needed to generate a 2 millimeter spark from your finger to a door handle is roughly 6000 volts source. It is said that a human can generate a charge of over 25,000 volts when walking across the carpet source.
ESD can be a problem in a number of areas. In electronics, there are many components that are ESD sensitive. A spark can puncture through the dielectric layer of a micro-component and essentially melt the conductive materials making the device non-functional. Since thicknesses of the various elements of a micro-electronic devise can be much thinner than a strand of human hair, it does not take much spark to do damage.
When dealing with electronic packages that are ESD sensitive, one must have a comprehensive ESD protection program that includes every phase of the product life cycle. Once fully assembled, most electronic products have enough built in protection so that ESD is not an issue. But a product can be handled and transported several times before that point.
The most common and effective strategy for ESD protection is to prevent static electricity from building up on nearby surfaces. Electronics usually flow freely on conductive surfaces so a charge won’t build up. Coating surfaces with a slightly conductive coating will help prevent energy build up on the surface. The biggest source of ESD is the human operator. Operators wearing grounding straps will help keep static electricity from building up on the human body.
Many packaging materials are available for ESD sensitive components that won’t allow static buildup on the material surface. This includes plastic bags, foam and plastic containers. In each case the material is made to be conductive enough to not allow a static build up.
Packnet routinely fabricates custom packaging solutions for handling ESD sensitive products. Materials that we use include:
- Conductive corrugated plastic
- Conductive shipping cases
- Special ESD foam for cushioning
- Conductive coated plastic wraps and bags
- Conductive spray coatings applied as needed
- Conductive strapping for grounding
For more information on how Packnet can create a custom packaging solution for your ESD sensitive product, call 952-944-9124 to speak to one of our application specialists.