Apr 07, 2008 As long as spring pins have been used to make electrical contact in IC contactors, two forces have continuously driven their size smaller � decreasing pitch and increasing electrical requirements. Because the main performance limitation in the contactor�s conductive path (the spring pin) has been inductance, spring pins are always designed to be as short and wide as possible to limit the inductance. As pitches become smaller, the spring pins have had to become narrower and shorter, making them more difficult to design. Six years ago, ECT introduced the Bantam spring pin, which revolutionized the technology by eliminating the spring-in-barrel architecture and exposing the spring. The enlarged spring and reduction of internal contact points (from two to one) created a product with exceptional mechanical and electrical properties. Over the past six years, however, the number of devices being manufactured at very fine pitches has increased, but more importantly, the electrical performance of those devices has increased dramatically.
The Gemini spring pin was created to meet this significant industry challenge, with an innovative design that is a radical departure from tradition. The unique, next-generation architecture is a technological advancement with two complete, parallel signal paths, each with its own contact point and spring. The design features redundant sliding wiping biased contacts, which affords excellent contact force at this small scale.
Gemini uses a proprietary manufacturing process, which breaks the barrier to smaller contact sizes and results in faster electrical contact in ICs, which ultimately results in higher speed/throughput rates in the end product.
The signal path length at test height is 1.5 mm (0.060") with a compliance of 0.38 mm (0.015"). A Gemini contactor has a bandwidth of 40 GHz because the inductance balances the capacitance to create a near 50-Ohm environment. ECT probes have a target force of 35 grams to provide enough force to penetrate oxides and debris on the device without creating damaging witness marks. The Gemini has 38 grams of force at test height. One of the goals of this design was reduced inductance, achieved through the short, wide circuit path, making it easy to maintain and repair (if necessary). The self-inductance of the Gemini probe is 0.5 nHenrys. Low inductance is only part of the RF picture. The ultimate parameters are bandwidth and characteristic impedance. With its low inductance, short signal path, and near 50-Ohm impedance (at several pitches), the Gemini has a spectacular 40+ GHz bandwidth at 1dB.
The contact resistance is less than 100 Ohms. Several features (hard base material; dual, unstressed springs; redundant wiping surfaces) contribute to an outstanding life of over 500K insertions.
The Gemini offers an extremely unique, patent-pending design. Because both forks are biased to contact one another, no matter how the contact is twisted, there will always be at least one contact point on each side, ensuring that there will always be two parallel paths. Features that make this design unique include two wiping surfaces and two signal paths; highly scalable with reasonable NRE costs; extended spring life and higher forces than similarly-sized probes; and the capability of being arranged in-line down to 0.4 mm pitch and in arrays down to 0.5 mm.
Premiering in 2008, the NPI Awards program is an annual celebration of product excellence in electronics surface mount assembly. Premier products based on the finest examples of creative advancement in technology are chosen by a distinguished panel of industry experts.
Everett Charles Technologies, a Dover Corporation company, is a leading manufacturer of electrical test products and services, including semiconductor test products, bare-board automatic test systems, Pogo� test contacts, backplane and loaded PCB test fixtures. Corporate manufacturing, service, and support facilities are ISO registered with locations in the United States, Europe and Asia. The company has been awarded numerous patents and participates actively in developing industry standards. Additional information is available at http://www.ectinfo.com.
