2005 Articles

Inspired by WEEE, the newest trend is to design products to be taken apart.

The current crop of OEMs and CEMs use close monitoring and control to achieve efficient manufacturing and are also conscious that good design gives good results. Everyone demands that yields and first-time-pass rates and throughputs be maximized. We therefore have a plethora of common sense concepts ranging from Design for Manufacture/Test/Excellence, etc., to buzz-phrases such as Lean Manufacturing, Six-Sigma and so on.

How many are actually put into practice? Many companies have adopted most, if not all, of these concepts and are reaping the benefits, but many have not. It is likely that those that ignore design-related improvements will die out like dinosaurs. Likewise, engineers have written many wonderful guides and practices but these concepts need to be adopted completely for any real and lasting benefit.

We must add one more to the list. Design for Excellence is a combination of all that works well in achieving optimum yields and throughput. It embraces not only manufacturability and testability, but sets a level below which the facility must not fall. This means everything from product concept and market awareness through failure rates in the field must have predefined targets that are constantly scrutinized for improvement. Probably not enough manufacturers understand this or put it into practice.

So far, companies are trying make the best use of DfM/T/E to stay competitive. The number of “Design for …” rules is expanding and the latest will be forced upon us by legislation. Let us call this new rule Design for Dismantling, or DfD.

We have become efficient at making products in huge volumes and at high yields –because we use DfM, DfT, etc. – and this has allowed us to develop new markets, create new products faster, invent products that exist only because of new technologies and so on. Classic examples include PDAs, digital cameras, mobile phones and laptop computers. But what happens to last year’s models if they are not merely dumped in a landfill?

In some cases it is possible to find entirely new markets. For example, more than one African country has no cable-based telecom structure and makes use of cellular systems that are previous models or technologies. That is one set of equipment that will not find its way into the land fill sites of the world immediately.

Merely passing older equipment to Third World countries does not solve the problem, however, it just delays it. We need to consider carefully what happens at the end of a product’s life.

The End of Life Vehicles Directive gives some pointers. Modern vehicles have to be designed to be broken down into constituent parts quickly and easily, with these parts as recyclable as possible. Currently, if we cannot move an unwanted electronic product to another part of the world, we tend to dump it into landfill. Worries about lead or other nasty materials are actually a minor part of electronic product disposal. The sheer volume of equipment to be dumped is large, much of it is technically recyclable and we should take all practical steps to minimize the mountains of rubbish we find ourselves living on.

Establishments can recycle many of the materials found in electronics assemblies, and their job would be easier and more cost-effective if we consider DfD. We have concentrated on finding the most efficient way of putting something together: We now need an equivalent way of efficiently taking it apart.

DfD as a concept is in its infancy but designers should start thinking about how a product might end its life. The easy concepts are, for example, choosing plastic materials in connectors, PCB furniture, casings, etc., that can be recycled and designing modules and submodules that can be tiny and highly functional so that their impact on landfill is minimal if no other effective way of disposal exists. Rules and guidelines will emerge soon that will aid the designer in the same way as they did for DfM.

Technologies such as conductive adhesives may find a home for some products, but clearly not all products can use them. Consider adhesives rather than blindly following the metallic solder route; they may permit easier dismantling.

Not much can be done with plated PCBs but if the metals can be removed economically, the base laminate epoxy matrix can be ground up and used as filler for road aggregate, reducing the need to dig gravel from the earth.

We need to document the possibilities now and feed the information back into the design chain. It’s pity that we have to adopt lead-free solders as they require large amounts of extra processing energy but that’s another story. Let’s make sure the lead-free activities we have use as few resources as possible and embrace all the possibilities of DfD.

Previous articles have commented on the Kyoto protocol and efficiency in general; this concept is one more to add to the list. If we all work to minimize waste and damage to our environment, we stand a chance of bettering our world.

Peter Grundy is director of P G Engineering (Sussex) Ltd.; peter.grundy2@btinternet.com. His column appears semimonthly.

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