Advancing through obsolescence lines

01 September 2006

With technology constantly on the move, component obsolescence is a serious problem, for military, high-reliability and long-lifetime applications.

Thanks to the efforts of organisations such as the Component Obsolescence Group (COG), awareness of the issue is higher now than it has ever been.

Unfortunately, much of this awareness is negative, focusing on the potentially dire consequences and severe financial implications of failing to plan and implement an adequate obsolescence management
strategy.

In fact, although the results of such a failure can be very real and serious, solutions do exist for almost every obsolescence problem. While many of the problems can be solved in-house, an infrastructure of component engineering and sourcing firms has now grown up to support OEMs. Whatever approach is taken, the key is to be pro-active, and to focus on co-ordinating the purchasing and technical disciplines.

Preventative measure
The first necessity is to nip problems in the bud by preventing obsolescence issues in the first place. This means ensuring that products and systems are specified with back-ups and alternatives for critical components. The project must not be dependent upon a single supplier.

Many component manufacturers are beginning to offer contractual lifetime support (CLS) plans or non-obsolescence policies to eliminate the problem altogether. However, it is worth noting that, valuable
though these can be, they cannot be accepted at face value. Purchasing and engineering professionals need to work together to ensure that such guarantees are not only correctly framed to protect the customer, but also technically achievable.

For example, it may be necessary to assess how well a semiconductor supplier continues to support legacy process technologies when its mainstream manufacturing process roadmap indicates that the silicon components will continue to shrink.

Another way of securing supply is to use an obsolescence and parts procurement specialist to provide contract logistics support services. These give the customer an assurance of supply throughout the manufacturing and service life of a project.

Almost inevitably, a component sourcing approach that insures against obsolescence will appear more costly in terms of bill-ofmaterials. It is therefore also important that engineering and procurement departments both understand that, planned-for or not, obsolescence will contribute to the lifetime cost of the system.

Migration policy
In these terms, a perfectly credible obsolescence mitigation strategy is to plan to redesign the system throughout its lifetime, as components become obsolete. An up-front calculation of the expected cost of this approach (in terms of engineering time) can be compared to the bill-ofmaterial impact of using suppliers, which will offer guarantees of non-obsolescence. The important points are to acknowledge that costs exist in both approaches and that the guarantee is only as viable as the model solutions.

With 13,000 end-of-life notices being issued every month for electronic components, unexpected obsolescence is hard to avoid completely. This inevitability is behind much of the ‘doomsday’ coverage.

However, solutions exist even in these situations. Many manufacturers now buy sufficient components up-front to satisfy the predicted needs of the whole lifetime of the product, including after-sales service. This not only secures against obsolescence, but brings the cost benefits of bulk-buying, and allows the manufacturer to guarantee its own production schedules. With increasing awareness of the costs of missing a market window, such security can be valuable.

The proviso is that procurement for longterm storage requires a different approach to that for immediate usage. The overall aim is to ensure that parts which come out of long-term storage perform in exactly the
same way as ‘factory-fresh’ parts. This means not only storage in properly designed and dedicated facilities with ESD protection, and controlled humidity and temperature, but also the implementation of a sound incoming test system. Such initial testing should typically include a visual inspection, sample electrical testing, life-tests and solderability assessment. Watchdog samples must also be periodically taken from
storage for testing to assess any ongoing degradation.

Procurement means business
Just as important as the test and environmental control regime are the procurement and business information aspects. If faulty parts come out of longterm storage, it is vital to be able to establish whether the failure is due to components that arrived faulty, were damaged in packing, or have suffered due to the storage process. Quality control demands that there be an audit trail all the way back to manufacture, particularly for components purchased by indirect means. This can be, for example, via a distributor or the grey market.

In these matters, the devil is often in the detail. For instance, IGG recently dealt with a sourcing requirement for an OEM that arose after the OEM’s engineer visited the OEM’s stores to obtain components, now obsolete, intended to service a specific vital project. Unfortunately, no record had been kept of the reason the batch in question had been stored by the OEM. Consequently, the devices had long ago been used to
manufacture a completely different product. The lack of ‘ring-fencing’ of components in storage is a significant issue.

It is also important to ensure that any certificates of conformity or other approvals paperwork, without which components may be un-usable, are accessible.

Where pro-active measures are not in place, many manufacturers will have to take up ‘last-time buy’ opportunities from suppliers.

Replacement options
Failing this, it may be necessary to identify, or engineer, a replacement component. Experienced purchasers can use the grey market or sources of second-hand components, whilst avoiding the common
pitfalls. These include components failing incoming test; one manufacturer’s silicon turning up in another’s package; and even situations in which the ‘devices’ are in fact empty packages containing no silicon at all.

None of these problems are
insurmountable. As with components for storage, the purchaser needs to establish an audit trail and a range of qualification and incoming inspection tests. These range from simple visual inspection, through
highly-accelerated stress testing (HAST) and destructive physical analysis (DPA), to scanning electron microscopy (SEM), x-ray spectroscopy and scanning acoustic microscopy (SAM).

Sometimes, a safer bet than using secondhand or grey market components is to identify alternative devices that can be upscreened or upgraded. Upscreening is the process of taking a component and testing it to a higher standard, for instance a higher temperature or frequency, than that for which it was designed. Upgrading involves changing the component in some way to produce the same effect, for instance, adding a heatsink or physical protection against radiation damage.

In reverse gear
In the final resort, it may be necessary to reverse-engineer an obsolete part to establish how best it can be replaced, and to use a gate array, FPGA or similar configurable device to emulate the original functions. This can either be done by electrical testing, or by physical analysis and inspection. In general this will need to take place at a specialist laboratory which has the engineers and equipment to analyse the component’s exact function.

As obsolescence problems have become more frequent, the supply chain has developed rapidly to help buyers and engineers cope. Beyond the advice to ‘start early and plan ahead’, companies now have access to an established body of knowledge and expertise, built up as obsolescence management has become recognised as a distinct discipline.

Against this background, it is to be hoped that the industry can move beyond the tales of doom and destruction, and recognise that, with the right skills and best practices, even the most serious obsolescence problems can now be solved.

LLOYD FRANCIS is aerospace and defence manager, IGG Component Technology.


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