The Significance of Protecting Medical Devices from Electrostatic Discharge
We’re all familiar with the kid’s prank, and for that matter, some adults too, of shuffling your feet on a carpeted floor, generating a charge of static electricity, lightly touching someone’s ear lobe and laughing at their reaction to the ZAP. In technical terms, this ZAP is called tribocharging or electrostatic discharge! It’s a fun prank. No long lasting damage, right? However, if you are a static sensitive printed circuit board, it’s no laughing matter and there can be long lasting or latent damage.
Electrostatic charge is defined as “electric charge at rest”. Static electricity is an imbalance of electrical charges within or on the surface of a material. This imbalance of electrons produces an electric field that can be measured and that can influence other objects. Electrostatic discharge (ESD) is defined as “the rapid, spontaneous transfer of electrostatic charge induced by a high electrostatic field. Electrostatic charge is defined as “electric charge at rest”. Static electricity is an imbalance of electrical charges within or on the surface of a material. This imbalance of electrons produces an electric field that can be measured and that can influence other objects. (http://www.esda.org/about-esd/esd-fundamentals/part-1-an-introduction-to-esd) Static discharge is not a friend of printed circuit boards or static sensitive electronics.
Printed circuit board components, devices and circuitry in general, have been engineered to be less electrostatic sensitive. The need for static protection cannot and should not be overlooked. Electronic medical devices are relying more and more on electronic componentry and integrated circuitry to gather, disseminate and record data wirelessly. Consider the growth of “wearable” electronic devices and their contribution to overall improved medical data collection and distribution to medical staff. The protection of these devices cannot be taken for granted.
Printed circuit safety starts at the device manufacturing level. Have a well established ESD safety program inclusive of EPA (electrostatic protective areas) and systems for the reduction of static generation such as using grounding to dissipate or neutralize static, ionization and the use of static dissipative or conductive control materials. Thermoformed static dissipative or conductive packaging solutions are material and labor saving alternatives to anti-static foams, conductive lined corrugated boxes, and metallized shielding bags. (http://uppi.com/industries-served/electronics-packaging).
Per the packaging standard ANSI/ESD S541, a low-charging, conductive or dissipative package is required for packaging or material handling within an EPA. Outside the EPA, the packaging must also have the discharge shielding property. Effectiveness, cost and device vulnerability to the various mechanisms need to be balanced in making packaging decisions (see ANSI/ESD S541, the ESD Handbook ESD TR20.20, and/or CLC/TR 61340-5-2 User guide for more detailed information) http://www.esda.org/about-esd/esd-fundamentals/part-3-basic-esd-control-procedures-and-materials/
A strong ESD control coordinator at the manufacturing level is also instrumental in launching and operating an effective static control program. A continuous education and training program, as well as, the implemention of static control materials at the manufacturing level will reduce the likelihood that products will experience an ESD event resulting in a latent damage situation.
While it might be fun to ZAP someone on the ear and laugh at their surprise, it’s no fun for a printed circuit board! Just ask the wearable device on your wrist the next time you look at how many steps you’ve walked in a day, or the phone in your hand or the dashboard in your car or the computer in front of you… I’m sure they will tell you that they’re just fine thanks to the static control coordinator’s implementation of an effective static control program and the use of static protective packaging solutions at the manufacturing level.