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Thinking ahead is the key to managing the burgeoning problem of component obsolescence

Component Obsolescence Group (COG) : 01 January, 2005  (Company News)
How long do you think the components in your design will be available? If it's been around for a couple of years, then the chances are that you'll have to start thinking about what happens to those parts in the next three to five years. Of course, if you are designing fast moving consumer goods or mobile phones, you have nothing to worry about. But, for an increasing number of applications in the industrial, transportation, automotive and medical sectors, the issue of component obsolescence is becoming increasingly important.
Components become obsolete through a number of factors. Sometimes advances in manufacturing technology make their continued manufacture hope-lessly uneconomic. This is a common problem with semiconductor devices, where the latest 130nm and 90nm processes are leading to an explosion in the level of functionality that can be supported by a single chip. Then there is simple lack of demand. You many want the part desperately, but unless a significant number of fellow manufacturers share your requirements, production volumes are going to be too small to attract the attention of suppliers. This is particularly acute for higher specification, e.g. military grade parts, where even initial production volumes tend to be relatively small.

The Component Obsolescence Group brings together component makers, specialist distributors and users to highlight problems and encourage designers to establish strategies to handle obsolescence. 'Why do you need an obsolescence strategy? By proactively managing the process, it means you are not surprised,' said Mike Trenchard, coordinator of COG.

'Components go through a lifecycle,' says Trenchard. 'There's the initial stage, with prototyping, followed by full production; then, as demand starts to fall, you move from multi-source to single-source, and then to the lifetime buy scenario, where customers are buying stocks to serve the remaining lifetime of a product. The lifecycle typically extends from three to five years, so if you are dealing with projects with a 10- or even 30-year lifetime, you've got a real problem.'

The demand for knowledge and support on obsolescence issues is growing across Europe, and COG is expanding into France and Germany, with 23 companies joining the German chapter in just five months. 2005 will see a pan-European management body set up to oversee the different groups.

'I would say that, in the military and aerospace area, those affected by obsolescence recognise the potential problems. But this isn't necessarily the case for the likes of railways, oil and gas and medical equipment,' says Trenchard.

Component lifecycle monitoring tools can help. These are basically databases of components, detailing the part number, performance parameters and the stage reached in the component's lifecycle. 'Then, if you know a component is coming to the end of its life you can takes steps to ensure continuity of supply,' says Trenchard.

One approach is to make a last-time buy (when a component comes to the end of its production run), which is then stored in a die bank, either as 'naked' die or as packaged components. But this can be expensive. Storage times can be as long as 20 years, and to prevent corrosion the bank's temperature and humidity must be maintained within closely controlled limits. Even then, your problems may not be over. Devices stored 10 years ago, although perfectly sound from a functional point of view, could be unsuited to current board manufacturing technology because of the switch to lead-free solders.

Another solution is to look for an alternative component, more readily available but offering equivalent, or near equivalent functionality. Here again, added costs are likely to be incurred, e.g. in adapting a board design to the different form factor of the new component.

Up to now the long-term costs associated with obsolescence have essentially been unknown, making it hard for engineers to justify higher up-front costs with the potential to reduce obsolescence costs in the longer term. This situation has now been transformed thanks to a survey into the true cost of managing obsolescence undertaken by ARINC (a US supplier of standards and equipment for aviation and transportation) and the UK defence contractor QinetiQ, for the Ministry of Defence. The report based on this survey, 'The Ministry Of Defence Component Obsolescence Resolution Cost Metrics Study', is available through the National Obsolescence Centre (

The survey found that the additional cost of managing obsolescence ranged from an average non-recurring engineering cost of 100 for using stock that had been stockpiled in a lifetime buy, to a one-off cost of 2400 for designing in a substitute part, or 1300 for using a hard-to-find part reclaimed from another board. But the biggest costs came from having to do a minor redesign to emulate the function of the obsolete part, at 75,000, through to a major redesign of the systems, which cost on average 300,000.

Given these figures, major redesigns are, understandably, rare and the majority of obsolescence problems are solved by finding alternative parts. Emulation is also common, using other discrete parts, or by implementing the function in a field-programmable gate array. However, both approaches to emulation necessitate a redesign of the original sub-system.

FPGAs from Actel and QuickLogic with metal-to-metal links are popular for emulation, as there is no penalty for using small volumes. But even these parts sometimes have to be bought up in last-time buy programmes, implying high long-term storage costs. Another option is for the manufacturer to sell wafers, which are easier to store, often to specialist distributors. The wafers are then diced up, tested and packaged when required. This approach provides full traceability, a vital element for military and aerospace designs, and something that can be difficult with a reclaimed or alternative part.

A more extreme approach, pioneered by companies such as Richardson Electronics, is to buy up the mask sets of a device as part of a last-time buy, so that new parts can be made to the original design. However, this accounts for just 6% to 7% of the business.

Companies such as Quarndon Electronics in Derby have also taken on older designs of VME cards that are no longer made by the big vendors, and produced on its own manufacturing line, emulating the function-ality of older cards with new components.

An example of component obsolescence extending beyond the defence sector is provided by the Scottish specialist chip maker Semelab. The company boasts long product lifetimes, and ships 90% of its RF MOSFETs to industrial customers. It came across obsolescence in a radio handset using a particular RF transistor.

The problem centred on an RF transistor used in a radio handset design produced by one of Semelab's industrial customers. Eighteen months into the design the first part was made obsolete. Six months later the handset went into production, then just nine months later the replacement part was made obsolete, with over five years of the planned product life remaining. This is when Semelab stepped in with an alternative part with the same specification. 'It is more expensive, but in 14 years we have never made an RF transistor obsolete,' says Cliff Robins, sales and marketing director at Semelab.
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