Beyond slot 1

Beyond slot 1The cost and performance requirements of the telecoms, PC, mobile phone, networking and consumer markets are giving the connector makers food for thought. Richard Wilson reports in the interconnection feature. Some may say that Intel started the trend with the introduction of the revolutionary Slot 1 interconnection system for its Pentium II microprocessor, but the reality is probably not that simple. PC and telecommunications designers have been asking their connector suppliers to jump through a dazzling array of technology hoops for quite some time. The situation facing connector manufacturers is best summed up by Fred Krehbiel, the chief executive of Molex. “The products are getting more complex, but they must be cheaper, which is tough on us,” says Krehbiel. Molex is the world’s second largest connector firm, but even it must work hard at the product development and its manufacturing efficiencies to meet the cost/performance requirements of the competitive telecoms, PC, mobile phone, networking and consumer markets. And what about the notoriously competitive consumer electronics market with its drive by far eastern firms for miniaturisation and cost efficient manufacturing processes. There is little surprise that Krehbiel believes that one of the biggest technology trends is the continuing miniaturisation of connectors. “The camcorder connectors we were producing nine years ago had a 2.5mm spacing today they are 0.3/0.5mm spacing,” he points out, adding that the growing price pressure in the connector market can only be met with increased efficiencies in his own manufacturing process. Inevitably similar cost/performance issues are absorbing the product managers at AMP, the largest connector supplier. The main technology driver in the connector market is processor speeds which are continually pushing up bandwidth requirements on the signal paths passing through interconnection systems. But cost is still the influencing factor in the connector market. Arguably the connector is the one electronics market today where suppliers cannot get away with selling new technology for its own sake and at its own price. Simon Webb, product manager for terminals and connectors at AMP of Great Britain is clear that with the trend for miniaturisation there are limits to what manufacturers want, and usually those limits are set by project budgets. “It is a balance between what you can produce and what people are prepared to pay,” says Webb. Perhaps one such limit, says Webb, is in the IDC market where he sees that the emergence of low cost fibre optic interconnect technology could remove the need to push IDC miniaturisation below today’s 0.025in. pitch connectors. “It is all about the cost/capability lines and when they cross,” says Webb. “With the emergence of fibre optic technology I do not see the copper technology going down below that.” The computer developers may be setting the performance standards in terms of the bandwidth of data interfaces, but they are also showing there counterparts in the telecoms sector the importance of connector standardisation to cut costs. The telecoms backplane has traditionally been a major interconnect technology driver (see Teradyne p18). Consider for example the design effort deployed by Siemens in its latest high speed backplane connector. Siemens has developed from scratch, what is claimed to be the first generation of high speed, high density surface mount backplane connectors, capable of handling data rates of up to 2.5Gbit/s and with signal rise times down to 50ps. Called SpeedPac, the connector represents state-of-the-art copper backplane interconnect technology but to develop it Siemens needed the collaboration of US engineering design and test consultancy firm North East Systems Associates (NESA) to bolster its own in-house mechanical expertise. But the next generation of backplane may not be designed that way for there are signs that the situation may be changing with competitive cost pressures convincing the telecom systems manufacturers that they must move from custom interconnect technology to the standard systems already proven in the computer networking market. “There is real pressure from data communications players and this is raising cost issues,” says Webb. The move towards standard connector products in the once custom domains of telecoms backplanes is one thing, but Webb is not so convinced about moves towards a universal connector system for computer interconnect. “Just take a look at the back of your PC,” he points out. “there are five to ten connector types minimum and that creates issues for the connector supplier. You need to establish yourself as a do-all connector manufacturer.” For AMP, that “do-all” tag has moved beyond its traditional connector product lines to incorporate systems products such as wireless transceivers and networking cards. Similarly Molex recognises that the drive for high speed interconnection, particularly in the PC market with a number of interface standards such as Universal Serial Bus, IEEE1394 and Firewire all jockeying for position, has triggered the requirement for cabling/connector assemblies. Molex is lining up its first integrated connector and IC design. “It is a smart connector for the telecoms market with a signalling IC in the one package. That is an example of how we have stepped outside our bounds, but we will not move too far,” adds Krehbiel, indicating that Molex is unlikely to follow its larger rival into the networking card market.
For Krehbiel there is enough potential for growth in the company’s core connector market as long as the company continues to track the technology trends and the multifarious standards committees which he knows are so important in this market. High density backplane 40 signal pins/linear cm
Teradyne’s latest high density backplane connector provides 40 signal pins per linear centimetre. The company has developed stripline shielding techniques to support signals with 300ps rise times without the need for using signal pins as ground pins. This allows the supplier to claim 100 per cent usable signal pin density for the connector called VHDM (Very High Density Metric) which is based on a 2mm x 2.25mm grid and is available in 6- and 8-row configurations.
The connector, which has already been beta site tested in the US is designed for use with Teradyne’s multilayer custom backplanes. It is targeted at telecoms and computer applications, so there is a variant for differential signals.
A customised version for Silicon Graphics is carrying 1.2Gbyte/s signals with rise times of 60ps onto the backplane, but that requires alternate ground pins. Teradyne’s high density backplane connector that provides 40 signal pins per linear cm.


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