An end to surface mount?
22 September 2008
Of course not, but for the first time in three decades there seems a possibility of new processes infiltrating the electronics manufacturing mainstream.
Back in April I ran a couple of articles ( Occam results in simplicity without solder and KISS goodbye to the long tyranny of solder?) that suggested that a new electronics assembly technology had progressed enough to become commercially viable. This solderless technology involved plating and embedding circuits and components to build up the complete circuit. While this process still has much to offer, potentially, it seems that it has not made that breakthrough to commercial realisation.
Last week I spent some time with a company called Imbera, whose own technology might well overcome some of the problems encountered with embedded assembly.
It strikes me there are two main problems with embedding components within a circuit board. The first is that once the embedded component is in there it becomes part of a bigger assembly – permanently. If it does not work, either because of assembly errors or component failure, or you want to change your design, you can’t. Rework or change is not an option.
The second problem is more of a practical issue. Who actually makes these embedded circuits? Is it something board assemblers should do, or is it a PCB fabrication issue? Either way, there is no supply chain in place to cater for it and the average PCB fabricator is unlikely to want to invest in the equipment and expertise in SMT to be able to offer this complete solution.
This is where Imbera have made significant ground recently. The article ‘Embedded packaging comes of age’ outlines how the launch of its third generation technology is now, according to the company, a commercially viable solution. So how does it get round the two main obstacles to the acceptance of embedded packages?
Firstly, argues Imbera, like all technology, people get better at it the more they do it. The parallel here might be the use of ICT at the end of every SMT line – often a necessity in the past but now increasingly rare as yields improve. For all that this year marks the start of high volume manufacturing for Imbera, the concept has been around for a decade and prototype manufacturing has been going on for three years. The founder, Risto Tuominen, developed the concept as part of his thesis at the University of Helsinki, Finland in the late 90s. The point is that manufacturing problems in Imbera’s process have been ironed out and it claimed a yield of 99.97% in one recent project for a four-layer motherboard.
Also, what Imbera makes are modules – a bit like a modern equivalent of an old fashioned hybrid circuit – that can then be mounted on a PCB in the same way as any other component. I assume that the only limitations on the size of these modules is in the confidence in the technology. If a customer was happy with the process he would be happy to embed more expensive silicon and the module (called an Integrated Module Board – IMB) could become the whole board itself. It is anticipated that this gaining of confidence would be a gradual process. But as a component it can be discarded before assembly if faulty and therefore not result in having to add the whole assembly to the bone pile.
Which brings us on to the second main problem – how to accommodate a new technology into the existing manufacturing process. Imbera’s solution to this is a simple one, it does the manufacturing either itself or through a partner. In fact the company is launching a high volume facility in Asia at the same time as announcing a five year tie up with Ibiden, the world’s largest PCB manufacturer. This effectively means that the modules are supplied as a component, the same as any other, to be placed as part of the ordinary SMT process. Any company using the technology does not therefore need to invest in it – the supply chain issue care taken care of.
There are a host of technical reasons in terms of electrical and RF performance, power and thermal management, and of course in terms of miniaturisation why electronics engineers should start looking at this sort of technology, but it strikes me that Imbera has taken away the reasons why production engineers would stop looking at it – and this is an important step forward in its long term viability.
You can find out more about IMB technology at www.imbera.fi .
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