Conductive Silver Tape (CST) Reduces EMI in Notebook PC Display Cable

When a leading personal computer manufacturer developed a new line of state-of-the-art notebook computers with high-resolution, and Thin Film Transistor (TFT) screen displays, the company also created a significant electromagnetic interference (EMI) shielding challenge.

The issue: Although recognized for their quality and high resolution, TFT displays emit high levels of EMI. Of particular concern was the interconnect cable that attaches the motherboard to the display. The cable required exceptional shielding and it needed to remain flexible enough to allow the display to open and close regularly.

The solution: Schlegel Electronics Materials (SEM) Electronic Materials’ tough Conductive Silver Tape (CST) meets high-level electromagnetic compatibility (EMC) demands and can withstand the repeated movement of the display and flexing of its associated cabling.
Before turning to SEM Electronic Materials, the manufacturer considered using copper foil tape, but found it inadequate for several reasons: The frequent opening and closing of the computer caused the foil tape to crack and reduced its shielding effectiveness. The resulting reduction in shielding effectiveness could cause non-compliance with EMC regulations. Copper tape presents risks for assemblers who can cut their hands on its sharp edges. With SEM’s flexible, easy-to-use Conductive Silver Tape, the manufacturer resolved these concerns.

Composed of silver-plated fabric and conductive adhesive, SEM CST delivers average attenuation of 60 dB*, which is more than enough to shield the cable in this application. SEM CST also addressed all the manufacturer’s durability and assembly issues. With its pliable, but tough nylon ripstop fabric, SEM CST endured a punishing 100,000-cycle flex test simulating the motion of opening and closing the computer’s display cover. After this formidable test, SEM’s CST showed no signs of cracking or compromise in shielding effectiveness.

For assemblers, the SEM CST’s soft fabric is safe and easy to work with, staying firmly in place with SEM’s strong, high-tack conductive adhesive. The conductive fabric base also allows the tape to be custom-cut in virtually any unique shape with simple, inexpensive tooling – which helps keep costs low for the manufacturer. An off-the-shelf, low-cost solution, SEM CST makes an open-and-shut case in the use of flexible shielding products. For more information, please visit the SEM CST Tape page.