Wireless Systems Design

Reliable Board-To-Board Connections Are Forged

Board-to-board interconnections are commonly made by traditional mechanical stacking connectors. Unfortunately, this approach invites modification costs and concerns. To eliminate these issues, Tyco Electronics Elastomeric Technologies spawned the Gold STAX connectors. These connectors flaunt gold-coated particles that are embedded within a low-durometer silicone. As a result, they eliminate concerns over the corrosion of materials that are exposed to the environment. They also claim to provide lower contact resistance between irregular surfaces when compared to traditional compression-style or wire-based elastomeric connectors. In addition, the connectors extend the working range of deflection to 5%-65%.

Within every conductive layer, the gold-coated particles create thousands of conductive paths. Each conductive layer provides multiple points of contact to the substrate interface. Because the pitch of the Gold STAX conductive layers is only 0.127 mm (0.005 in.), multiple conductive layers are permitted for making contact to each substrate.

In addition, Gold STAX promises freedom from the constraints of pin-count availability, specific mating heights, and overall size. The connectors are a good fit for the next-generation color LCDs that are often utilized in cell phones. Those displays are moving from chip-on-flex (COF) to chip-on-glass (COG) manufacturing techniques. They have 8 to 15 I/O positions on the LCD glass and lead-free solutions.

As a zero-insertion-force (ZIF) connector, Gold STAX is composed of alternating layers of conductive and non-conductive silicone rubber. Because those layers don't require any soldering, interconnection can be made by deflecting the elastomeric connector between the mirror-image pad patterns on mating substrates. Among the connectors' other potential applications are the direct connection of chip-on-glass liquid-crystal-display substrates and board-to-board connections in a wide range of portable/handheld devices.

Pricing for the Gold STAX connectors is as low as $0.01/contact in 250,000-piece annual volumes. Prototypes are available in 48 hrs. Full production takes approximately four weeks.

Tyco Electronics, Elastomeric Technologies
2405 Maryland Rd., Willow Grove, PA 19090, (800) 989-STAX, FAX: (215) 784-4522; www.elastomerictech.com.

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