SMART look back
23 August 2010
We asked the SMART Group to provide some of its members’ views on how technology has been implemented over the past 30 years, and the pressures and changes forced on it by progress in design.
SMART Group congratulates EPD/EM&T on reaching the grand old age of 30 years, especially as it coincides with SMART celebrating its own 25 years of supporting industry. As someone who has seen the many exciting challenges and changes in design, components, printed circuit boards, manufacturing and test, I can confirm its been an exciting period! We are delighted to share some of the landmarks/reflections of the past and a look towards the future. Here are just some thoughts from my committee colleagues.
Mike Judd PR Director SMART Group.
Then and now
It’s always easy to look back to a golden age: the main issues are remembered with clarity - simple and uncluttered by trivia now conveniently forgotten. Any problems were first easily solved and then resolved into opportunities. So how was it really?
Well back then old timers were probably congratulating themselves on inventing and implementing the three key items of modern electronics: the PCB, solid state devices and mass soldering. They had successfully transitioned from hand soldering point-to-point assemblies to the commercialisation of these essential elements and benefiting from the huge markets mass production had created. There was continuing innovation but the basics of production were established. Then along came surface mount.
It’s not easy now to realise how strange a leadless component looked – and it was on the same side as the solder! Never-the-less the transition was made. These were technical and engineering issues and could be solved. The emphasis though was changing in more subtle ways. Alongside the purely technical issues of “could it be made”, manufacturing and social issues were rising: could it be made reliable? Was the process safe to workers; was the process and product safe for the planet? At the same time the rate of change was increasing. Still is.
So now we can boast: not only have we introduced fine pitch components, area array devices and the means to solder them. We have lowered costs to a fraction of their previous levels, coped with globalisation, invented products of huge social significance. And all that in the face of increasingly onerous environmental pressures/restrictions, some of which would not be rationally predicted.
Then we were looking at type 2 solder paste and worrying about type 3. Could it be made? Now we are using type 3, know we have type 4 in the bag and are looking at type 6. Then we were worrying about white residues from solvent cleaning. Now we don’t clean at all (by and large). Then we worried about which new process options and devices would “fly”. Now we have industry road maps and tick box standards for everything.
On the other hand how much is really new? We hear much these days about new processes such as transient liquid phase soldering, new high efficiency devices based on silicon carbide, area array packages and so on. Much of these actually died back decades, some to the 1960’s. So maybe there isn’t really anything new, we just need a few decades of hind sight to puzzle out what was important at the time.
Mike Fenner, Indium
Evolution of test in manufacturing
As products have become more and more complex they offer the end-user a massive increase in functionality, speed and a reduction in size. It was once possible to separate test functions from manufacturing functions but for a long time now, Test Strategies have had to be considered at the outset before any manufacturing could take place so that an appropriate level of test could be built into the production strategy.
Test used to be broadly broken down into Manufacturing Defect Analysis (MDA) and Function testing. Today’s controls over manufacturing efficiency mean that manufacturing defects are often designed out of the product before production commences and so MDA has become less obvious. However, it is still essential to know that a particular product fulfils the functions for which it is intended even though it may be a highly dense, double-sided product such as a mobile phone. Therefore, function testing is still a vital part of production although it now has less circuit area to address and so strategies such as Boundary Scan or Flying Probe testing are common and allow high levels of test coverage whilst still allowing highly dense circuits to proliferate.
For some time it has been sensible to use the test system to programme certain parts of the circuit during testing. Circuits will not reduce in complexity, nor will densities decrease. Therefore, more use will be made of Boundary Scan and more components will become available with Boundary Scan functions built in. Flying probe systems will become faster. Test will become more of an essential part of the overall product strategy and production and test functions and engineers will become more closely associated.
Failure analysis and HALT-HASS will become much more main-stream and part of the product strategy. Manufacturers of production and test equipment will work much more closely together but without buying each other out!
Thoughts from a test engineer
When I started out on my career as an electronics test engineer, PCBs were all either single-sided without plated-holes or double-sided with plated through-holes. (To be strictly accurate, I began with “Vero-board” single-sided strip-board, but you get the idea!)
It was ten years later before the day job regularly presented the challenges of multilayer PCBs and surface-mount components. This combination produced a new set of complexities which lead immediately to both a greater number of opportunities for defects to occur and a wider variety of defect types.
As an electronics engineer diagnosing circuit performance problems of current and newly introduced products, I then had to rapidly educate myself in the detail of our own PCB assembly processes and of the manufacturing process of the bare PCB itself in order to understand root cause and effect. With no formal training or experience in PCB manufacturing, some of the complexities of the chemistry and metallurgy involved require a little background reading to say the least – but all good engineers are supposed to seek out opportunities for CPD (Continuing Professional Development) and there were plenty of experts out there to talk to.
Having just got to grips with all that, along came the EU’s RoHS Directive and lead-free soldering. Now the required knowledge and expertise was something almost everyone in the industry was striving to obtain simultaneously. The easy availability of information on the internet and the benefits of online networks to share experience, such as the SMART Group’s online forum smart-e-link certainly made this much easier than it would have been even five years previously.
In the main, however, I find that there are few new “lead-free” problems to learn about just the re-emergence of defect mechanisms discovered and remedied many years ago, now back again due to the narrower process windows involved, combined of course with ever smaller footprint devices (for example, 01005, uBGA, CSP, QFN), which are packed more closely together on the PCB with ever reducing PCB track and gap topologies, thanks to the designers!
Nigel Burtt, Invensys Rail
The Printed Circuit Board
The Past : Invented by Doctor Paul Eisler, an Austrian Engineer, in the 1940s, became popular in the 1960s, and today we could not live without the printed circuit board. We carry them in our pockets, they control our cars, are at the heart of all computers, and homes are full of them. Try to imagine a world without PCBs……….
With the ever increasing demand for more functionality and decreasing size, boards have become very complex, with various techniques like via in pad technology on microBGAs, that are plated shut. This requires a lot of investment in manufacturing equipment like Laser Direct Imaging, couple this with the aggressive pricing of products and the fast turnarounds available from the Far East , give’s the poor UK printed circuit manufacturers a difficult time sustaining, what is definitely a shrunken market , it is now only approx 10% of its peak, with an ever increasing demands on costs, due to materials, cost of manufacturing, legislation like RoHS etc…
The Present : This has changed the UK Printed Circuit Industry, to the point it is now practically all small to medium production with high volume being manufactured with offshore partners, it is very unlikely that volume will return to the UK PCB Market.
We now see a massive increase in the use of BGAs on PCBs over the last two years, which increases functionality, with the added increase in board complexity.
The Future of the PCB Market: It is unlikely we will see a large increase in the volume of PCBs being manufactured in the UK. The likelihood is that we will all endeavour to do more and more of the higher end more complex boards, which require more investment and ship the lower end low cost products to our offshore partners.
Ian Hood, Zot Engineering
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