Are you grounded?

'Shocking' details about charges that affect our company's profitability.


	Armed with knowledge
	Establishing an ESD program at our facility in Carlsbad, Calif., has helped improve product quality and customer acceptance rates.

Intentionally dragging your feet across the carpet and "shocking" unsuspecting friends is an action most adults admit to doing at one time or another during their childhood.

But this seemingly innocent game that often sparked laughter among friends – and likely an occasional argument or two – can cause serious issues for Rockwell Collins and the customers our company serves.

Known as electrostatic discharge (ESD), this sudden and momentary unwanted electric current that flows between two objects can result in thousands of dollars of damage to the products our employees design, develop and manufacture.

According to Lenny Howell, manager of Technical Support for Government Systems Test Solutions and Engineering in Richardson, Texas, the ease with which these electric currents can be created – coupled with the fact that it takes very little energy to damage sensitive, digital equipment – are the primary reasons our company is working harder than ever before to minimize such incidents.

"Few people realize that small, electronic devices actually require very little power to operate," said Howell. "However, these tiny circuits are much easier to 'fry' through static discharge. That's why it's so important for our employees to be cautious when they're assembling and testing our products."

David Mager agrees. A senior engineering manager for Commercial Systems Technical Support in Melbourne, Fla., Mager also stresses the importance of realizing that an electrostatic discharge might not necessarily be felt. Still, that doesn't mean it hasn't occurred.

"ESD can easily be created when you stand up from a chair and then touch a door knob or another metal fixture," he said. "As little as 50 volts can damage some new, integrated circuit devices, and normally you can't feel static discharge until it reaches 3,000 volts."

Man on a mission — Tom Smith believes educating our employees and making them aware of the damage that can be caused by electrostatic discharge is one way to help our company continue providing quality avionics systems. Smith is a component application engineer in Cedar Rapids.
Photo by Paul Marlow, Cedar Rapids, Iowa

According to Tom Smith, a component application engineer who is also a certified ESD engineer, ESD-sensitive devices may be damaged by discharges going to or coming from the device. The ESD Association recognizes three primary ESD models, each having their own classification schemes.

Charges going to the device are described by the Human Body Model (HBM) and the Machine Model (MM), while discharges from the device are described by the Charged Device Model (CDM). Each one has its own test methodology and classification scheme, and each one requires special strategies for protection.

"HBM is the oldest and most commonly used model for classifying device sensitivity to ESD," explained Smith, who received ESD certification from the National Association of Radio and Telecommunications Engineers (NARTE) in 2005. "It represents the discharge that's delivered to our product from the fingertip of a standing individual, and is why we ground our operators with wrist straps and have them use special ESD flooring and footwear to drain charges."

The Machine Model is similar to HBM, but replaces the human body resistance to current flow with a direct short. The damage from the MM can be 10 times as destructive as HBM damage and takes place when a charged component comes in direct contact with metal, such as a tool or automated placement machine. According to Smith, the goal in this case is to eliminate the charge or control the discharge.

"It's best to think of current like water in a hose," said Smith. "If you don't use a valve to restrict the flow, you can destroy your garden. At Rockwell Collins, we use special high resistance work surfaces to control ESD current and we use air ionizers to remove static charges."

Finally, CDM occurs when a device is discharged to the ground in the presence of a charged insulator. It also can be more destructive than HBM for certain devices. While the duration of the discharge is very short – often less than one nanosecond – the peak current and resulting energy can be very high. CDM damage is controlled by keeping insulative material like styrofoam cups and plastic objects away from sensitive devices.

As an in-house professional consultant, Smith's level of expertise regarding ESD and his ability to perform damage assessments when ESD procedures are violated helps ensure that our company is providing customers with undamaged product. In addition, it also helps save thousands of dollars in needless scrapping or reworking of suspect product.

Staying grounded — Rockwell Collins Production Specialist Diane Kilburg wears a wrist strap to ensure she is grounded and does not deliver an electrostatic discharge to the product she is building. Kilburg works on ARC-210 products in our Cedar Rapids facility.
Photo by Paul Marlow, Cedar Rapids, Iowa

"The misunderstanding and knowledge gap when it comes to ESD is extraordinary," said Smith. "I try to gather the facts and apply my knowledge of the science of ESD in order to reach the best decision for the company and the customer."

Senior Systems Engineer Rod Schmidt appreciates Smith's expertise. During a recent ESD evaluation and assessment in Government Systems, Smith was able to help address customer concerns and answer various questions. In the end, the customer was completely satisfied.

"Tom evaluated the situation, suggested appropriate corrective actions, and provided a detailed report within a very short period of time," Schmidt said. "Without his assistance, there likely would have been significant production delays. Instead, we were able to save our customer money, and also maintain a high level of confidence with them."

While Smith admits there is absolutely no way to prevent electrostatic discharge from taking place, he is confident that our employees can be successful in preventing ESD from reaching damaging levels.

"Education and awareness are the keys to success," said Smith. "We want to remain a world-class provider of quality avionics systems, so we must strive for world-class ESD procedures."

Smith also encourages those who want to increase their knowledge about ESD to join the new ESD discussion forum ("Ask Al"), which is available to our employees via Rockwell Collins Online (our company's intranet).

"I'm also available to mentor anyone who is serious about improving their facility's ESD program," he concluded. "I'm very passionate about this and I'm happy to share my knowledge."