Is there a trend to smaller connectors carrying more power and data?

Bob Hult, director of product technology for connector market research specialist Bishop and Associates, said: "Product managers at leading connector manufacturers report demand for power connectors with increased current ratings in smaller envelopes, particularly in board to board interfaces used in the datacom industry. Although each chip may consume less power than its predecessor, systems often incorporate many more chips to provide greater functionality, upping the total current draw." Ken Stead, new product development manager with Molex, said: "Since I started this assignment eight years ago, customers have increasingly been looking for higher density power connectors. But what's interesting to note is how much copper can be packed into a given area, because current density – expressed as Amps per inch – is becoming the figure of merit." Darren Cox, connector product specialist with Avnet Abacus, noted: "When we talk with customers about connectors, miniaturisation is an important topic and has been for the last couple of years. There is certainly a trend towards smaller pcbs and connectors, but I have to say that I haven't seen too many people asking for devices that can carry more power. If anything, they're looking for smaller pitch connection." Wendy Bourne, product specialist with Harwin, reported a different view. "Harwin has a connector range which allows signal and power – even coax – to be mixed and we're seeing an increase in demand. It offers a range of options; you can just specify power contacts and that's being taken up." But she noted that designers are looking to handle more current within an existing form factor. According to Bourne, the Mix-Tek Datamate range offers contacts rated at up to 3A for signal purposes and at 20A for power applications. "This compares very well with other commercially priced, twin beam 2mm connectors whose contacts may only be able to handle 1A," she added. Stead said he believed all connector companies have hybrid devices available. "They might have 20 plus signal and power contacts integrated into one connector. When that's targeted at a power supply, for example, or at a board to board application, it usually features low data rates. But I'm hearing more people asking about handling 1Gbit/s; even 1.5Gbit/s. But there hasn't been massive demand. In the last five years, nobody asked how fast signal pins could run at. Now, they're talking about 1.5Gbit/s, so maybe it's the start of a trend." Stead pointed out that Molex has done some work in order to maximise current density. "But, at some point, the connector will have to get bigger in order to carry more current," he asserted. "We're working all the time to help customers understand that. We have to coach them to stop using contacts as heat sinks. If a designer is trying to pass 300A into a 100mm wide connector, the interface will overheat unless there is the proper pcb construction. Smaller connectors and higher current is an oxymoron," he said. Paul Jones, another product specialist from Avnet Abacus, said all leading manufacturers are offering connectors which can handle power and data. "There is increasing demand for computing power," he accepted, "and a demand for smaller interconnects. These are opposing forces and designers are having to explore the effects." Cox picked up the theme. "While there are growing numbers of enquiries about mixed power and data connectors, designers tend to stick with what they know; and that's standard products. Engineers see these as being available and reasonably priced." Cox also suggested that connectors may not be the first thing a system designer considers. "Connectors are one of the last things that get put on a board and it often comes down to available space. Having said that, if it's an industrial product, there is more space for wiring, but medical designers are certainly looking to miniaturise." Bourne is of the same opinion. "Many times, interconnect is viewed as a relatively simple problem, so is not addressed until the latter stages of the design. This means that often there simply is not enough room for separate signal, power and coax connectors." Stead pointed out work being done by Molex to improve performance. "Molex – and other manufacturers – are working with alloy manufacturers to increase connectivity by providing stress relaxation over time and temperature. On the male side, the metal is 100% copper; on the receptacle side, there are stress relaxation issues if you don't use alloys. Alloy 260 – cartridge brass – used to be the big thing, but we can't use that anymore and are now looking at more exotic alloys." All companies believe there is an increasing responsibility for engineers to specify the connectors they need more accurately. Avnet Abacus' Ian O'Mahoney said: "Engineers need to know how much power they need to handle; they need to know clearance distances. It's all about how much power, how much pitch?" The aim, he continued, is to get involved earlier in the design cycle. "We have to get designers thinking about connectors at an earlier stage," he believed, "rather than someone calling us and saying 'I've got an inch available and have to get 800 signals through'." Stead also sees a growing need for design support. "With changes in the market, some companies don't have the resources, so look to connector companies to help them." He believes aspects such as thermal modelling and determination of current density will become more important. "But it's a low volume, high mix market and suppliers have to be flexible and there are a lot of sales from derivatives of standard products." Bourne said it was important for the customer to know the performance criteria of their design. "The customer may specify a particular product and say it has to meet a particular set of requirements, which the product can't meet. Designers have to work out what their requirements are and find a connector which meets their needs." She said the Mix-Tek Datamate range offers a large number of configurations. "This effectively allows the customer to design a connector specific to their application by mixing and matching the required signal, power and/or coax contacts up to a maximum of 50 low frequency contacts or 12 special (coax and power) contacts." Stead believes the balance between higher current or voltage and smaller connectors has to change at some point. "It's all about Watts," he said. "More power comes either from higher voltage or higher current. It maybe that we see a move to 350V systems in order to deliver more power, then step down to 12 or 48V. But I'm hearing more conversations about higher voltage than higher current," he concluded.