‘Fueling’ a Revolution Print E-mail
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Written by Mike Buetow   
Friday, 29 February 2008 19:00
Caveat Lector

In 1843, when Sir William Grove invented the first fuel cell, he hardly could have foreseen its evolution. But today, with fuel cells found powering everything from city buses to roadside traffic monitors (and ubiquitously lighting so many home sidewalks and gardens), it’s hard to believe the market is still in its infancy.

Over the past year or so, fuel cells – and their near-cousins, solar cells and photovoltaics – have made a splash, with much press – and more important – customer demand.

Alternative energy – including solar and wind power, biofuels and fuel cells – was a $55 billion industry in 2006 and is headed to $226 billion by 2016, predicts Clean Edge (cleanedge.com), an environmental research firm. Solar power alone could jump fourfold to $69 billion in that time. Remarkably, photovoltaics – modules that use solar cells or arrays to convert sunlight into electricity – have the potential to be as large or larger than the electronics assembly industry.

It’s with good reason, then, more and more assemblers are lasciviously eyeing ways to penetrate the alternative energy market.

The harder one looks, the more alternative energy looks and feels like an extension of electronics assembly. What do Sharp, Kyocera, Sanyo and Mitsubishi have in common? All are major electronics OEMs, sure. But they also make up four of the five largest producers of fuel cells. Many of the leading equipment and materials suppliers are familiar too: BTU, Ekra, DEK, Asymtek, Indium, Cookson and more.

From a technical standpoint, the overlap between conventional SMT or thick-film production and alternative energy processing is equally striking.

As Rob DiMatteo of BTU International (btu.com) explains, for the metallization process, conductive inks are applied to both sides of the cell substrate, which is then doped, with conductive material dispensed or printed onto the cell. Material (ink, paste or slurry) is screen-printed in 10 to 100 µm thick layers, which are then dried or fired between prints. The material is dried and subsequent layers added; then the solar cells are fired in a furnace.

Another process involves diffusion. Silicon wafers are doped with phosphoric acid, a process that involves depositing phosphorous vapor or coating on a silicon substrate. According to DiMatteo, inline phosphorus doping is similar to SMT batch processing. The temperature range veers mightily, however, reaching up to 1,000°C. (It takes energy to make energy, it would appear.)

On the printing side, as with SMT, squeegee length, angle and hardness, print pressure, gap and speed, and substrate flatness all play heavily into product quality, explains Darren Brown, alternative energy business manager of DEK.

AOI is not required; instead, mass measurement weight monitoring is used.

Typical alternative energy substrates include steel, nickel foam or ceramic. (A reel-to-reel version uses polymer, flex, woven or membrane substrates.) Line setups can be batch or inline.

None of this technology comes cheaply. According to one EMS company that is currently producing an alternative energy product, a single fuel cell line can cost tens of millions of dollars.

Moreover, a Class 10,000 or better cleanroom is required. And the beat rate is often faster than SMT: under seven seconds per print cycle, for example. While the volumes are attractive, being much higher than any SMT assembly production outside of Southeastern Asia today, it requires wafer-handling skills, which is not an inherent strength of EMS companies.

So why would an electronics manufacturer invest in fuel cell production? A staggering market coupled with widespread OEM disinterest in in-house manufacturing. As DEK’s Brown says, “It still the early days, but most customers aren’t interested in building their own product.”

P.S. We want to thank the more than 2,200 engineers and designers who signed up for Virtual PCB (virtual-pcb.com), the industry’s first virtual trade show. It’s open for the next three months, so be sure to check it out. And we're pleased to announce a followup show will take place Nov. 18-19.

 

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