Expanded packaging and performance options make power connectors surge.
Power connectors once occupied just a tiny niche of the total separable interface market, but they are now on a rapid growth curve as many new power connectors that offer expanded packaging and performance options come into the market.
In the world of pluggable electronic interconnects, the market is divided into two basic types: Signal and power. Although there is no universally accepted dividing line between them, it is generally agreed that signal connectors are designed to connect circuits that convey information via analog or digital signaling. By contrast, power connectors are designed specifically to connect circuits that deliver the energy necessary to power signaling circuits. In many industries, the voltage in signal connectors is often five VDC or less, with current measured in milliamps. Power connectors may be rated to several hundred amps at a wide range of DC or AC voltages. Signal connectors may feature several hundred contacts on small centerlines while power connectors may have as few as one or two large and widely spaced contacts.
Historically, power connectors have been a high-mix/relatively low-volume commodity with a limited number of dedicated suppliers and connector types. Standard connectors were physically large and prices high. System designers had little design flexibility. Most connector manufacturers included a line of power connectors as part of their total product offerings, with a few suppliers making power interfaces their primary focus. Fast-forward 10 years and the power connector landscape has changed dramatically.
The growth of supercomputers, huge server farms, and network switches that may consume megawatts of power have spurred demand for power interconnection devices that efficiently conduct large currents, consume as little space as possible, provide extensive design flexibility, and support the thermal management strategy of the application. Connector manufacturers have stepped up to the challenge.
We have seen major commitments by leading connector suppliers to greatly expand their power product lines in order to offer a complete interconnect solution in terms of current rating, reduced voltage drop, increased current density, and design flexibility. To a large degree, many of these new power connectors represent refinements of established power connector technology, but they enable system designers to achieve their immediate packaging objectives.
These advances were accomplished through:
- Lower contact resistance achieved by increasing the thickness of the contact materials as well as utilizing new copper alloys that offer higher electrical conductivity
- Improved contact designs that may include bifurcated beams and louvered bands that ensure multiple points of contact in parallel
- More economical precision gold strip-plating that puts gold only at the electrical interface
- Vented connector housings that keep the temperature at the contact cooler, which allows a higher current rating
- Improved connector performance documentation that provides greater insight on the actual performance of the power connector in a variety of environments
- Availability of more accurate and user-friendly thermal modeling and simulation software that more closely predicts connector performance in a specific environment during the early design stage
The new mantra for power connectors is efficiency. Connectors that feature reduced contact resistance and voltage drop have become essential in new product design. Power connectors must exhibit low voltage drop, both initially as well as at the expected end of life, to ensure long-term performance. Power loss due to resistance generates heat that is a costly byproduct, especially in large data centers and supercomputers. As current consumption at a single rack can be measured in kilowatts, engineers are desperate to find ways to deliver vast amounts of power with minimal loss.
An ongoing procession of new products that feature increased power ratings in smaller envelopes is satisfying demand for connectors that deliver more current in less space. Hybrid connectors that feature combinations of high/low power along with signal contacts are gaining in popularity.
A new metric of amps per linear or cubic inch has become an important measure of power connector efficiency. Traditionally, the maximum published current rating was determined by increasing the current through a mated pair of contacts until the temperature at the interface reached and stabilized at 30°C above the ambient temperature. Factors including ambient temperature, airflow, adjacent power contacts, terminating wire gauge, and duty cycle, as well as shock and vibration, will have significant influence on the actual current limits of a power contact in application. Due to the difficulty in extrapolating the results from laboratory test conditions against a real-world application and concern about connector failure, engineers would commonly de-rate the connector by as much as 50%. That paradigm is changing as more designers use the published current rating as a starting point for modeling and simulations, which enables them to more closely approximate performance in their specific application.
Keeping the contact interface cool can permit a higher current rating. The most recent power connector introduction from FCI is the PwrBlade ULTRA connector, which is highly vented to provide power density of up to 260A per linear inch.
TE Connectivity introduced the Multi-Beam CE edge-card power connector. This low-profile connector is only 8.06mm high and consists of 21 power and 24 signal contacts in 74.6mm of PCB edge. The vented housing enables a contact rating to 38A.
Another significant change has been the introduction of power connectors fabricated with laminated or modular molds. Fixed combinations of power and signal contacts once published in a print catalog have evolved to nearly custom combinations of hybrid connectors that feature customer-defined configurations of high/low power and signal contacts with little or no extra engineering or manufacturing charges.
Demand for greater efficiency extends to the entire power distribution system. Interest is growing in the use of rigid and laminated bus bars that can replace large round cables in rack-mounted servers, switches and routers. These engineered assemblies are more efficient, occupy less space, reduce obstruction to airflow, reduce assembly labor costs, and dissipate heat better. In response, several connector manufacturers have beefed up their bus-bar interconnect product lines.
Robert Hult, Market Director, Bishop & Associates, Inc.
Bishop & Associates recently published a new market research report: Power Connectors in Computing and Datacom Applications. Long- and short-term industry trends are reviewed, and market values that exceeded $1 billion in 2013 are evaluated by region of the world with forecast data to 2018. An outline of this report and ordering information is available at www.bishopinc.com.
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