Adhering to RoHS is more than designers ticking the ‘compliance required’ box on their drawings and letting the suppliers sort it out, which could be product suicide. Andy Hughes says deal with RoHS early in the supply chain

Like it or not, RoHS compliance is now a significant issue in the lives of many electronic and electrical engineers’ working lives. However, while information on the topic seems to be omnipresent in trade titles, industry seminars and product catalogues, there is still a worrying lack of practical experience of actually achieving RoHS compliance and its impact on the manufacturing supply chain.

In short, most people who need to understand about the legislation have read the leaflets and ticked the boxes. But true compliance is much more complicated than that.

Our experience in the PCB market shows there are still too many designers out there who have simply seen RoHS as ‘a product that contains no lead’, and that by ticking the ‘materials must be RoHS-compliant’ box, they assume their product becomes compliant. This is dangerous thinking, as mere adherence to the letter of RoHS legislation, may well be creating huge problems further down the line for OEM suppliers.

For Exception PCB, the implementation of the Directive has brought our relationships with both suppliers and customers into sharp focus. While our finished PCBs have been lead-free for some time now, the critical point is what happens after they leave the plant.

RoHS has encouraged us to find out more about how our PCBs are being used and enhanced further down the manufacturing chain. Similarly, the legislation is prompting OEM customers to think more carefully about the functionality of the boards and their suitability to achieve RoHS compliance. This last point has proved vitally important in many of our conversations with OEM manufacturers.

Let us first look at the components of a PCB and how players in the manufacturing supply chain interface to deliver a finished product.

Previously, a designer from an OEM manufacturer would send over their drawings for a certain quantity of PCBs to be manufactured to a specific quality by an agreed time. We would then produce the required product. Simple.

With the advent of RoHS, that relatively simple relationship between designer and supplier has been turned on its head. Designers, cognisant of the fact they need to meet RoHS compliance standards now add the note into their designs that ‘all materials must be compliant’, without realising that the necessary adoption of lead-free alternatives has huge knock-on effects for other materials used in the manufacturing process.

While a designer may be right to tick the ‘compliance required’ box on his submitted drawings, we are aware of instances where adopting the letter of the law and blindly adopting lead-free solders in isolation would be product suicide.

In reality, adhering to the designer’s RoHS-friendly specifications would create a fully compliant, but totally flawed product. The reason being that laminates – even those that pass the stringent FR4 test for quality – are generally unable to withstand the much higher temperatures required to work with lead-free solders. Hence, FR4 standard laminates, as specified by designers looking for the best quality boards, would find their RoHS-compliant PCBs suffering from the effects of Z axis expansion during assembly as well as potential board decomposition. Even if the boards survive the assembly process, the potential for failure in the field is vastly increased.

We have worked closely with a number of laminate suppliers – including Isola and Polyclad – to understand the demands lead-free manufacturing places on laminates. Having identified the issues, we have worked closely with designers and helped to create a ‘virtuous community’ so that vital knowledge on laminates is understood by all in the manufacturing supply chain.

Designers need to understand that RoHS compliance is vitally important, but cannot be adhered to with a simple tick box mentality. OEMs that have sorted their compliance issues out are characterised by the fact that they have established ongoing dialogue with their suppliers to understand the RoHS issue from every angle.

Electronics designers that get the most from their suppliers are those that step back and take the time to consider the end application of a component. What type of board do we really want? What function does it have and under what sort of tolerances must it operate? These are the type of questions that should be asked when re-evaluating designs. Exporting the problem of RoHS can only create issues further down the supply chain.

Andy Hughes is a technical engineer for Exception PCB

www.exceptionpcb.com