If you’re a PCB manufacturer hoping to jump into the high-growth photovoltaics manufacturing industry, there’s good news and bad news. The good news, according to Don Cullen, managing director of photovoltaics at MacDermid, is that photovoltaic cells, especially once assembled into a module, are heavy and fragile. This means that they benefit from geographic pairing, where the assembler and customer are in the same region and shipping is minimized. Solar cell assembly is also a highly automated in-line process, so labor costs are minimal. The bad news? Despite similar processes such as chemical etch and electroplating, circuit board fabricators will likely need to re-tool from the ground up to convert to solar cell manufacturing.
Cullen spoke to a joint meeting of IMAPS, SMTA, and ACerS in Boston. He outlined several areas for improvement in solar cell manufacturing and highlighted three in particular — the screen printing, conductor metallization, and imaging processes — where PCB fabrication expertise is welcome. Silicon solar cells are made from thin wafers with screen printed silver paste conductors, and the force of screen printing can lead to breakage. Printed paste covers 7% of the average cell, shadowing areas that could be absorbing light. Compare that to electroplated nickel and copper where shadowing is less than half than 7%. Also, the silver conductor paste is both expensive and difficult to work with; opens are a problem. Right now, about 90% of solar cells are screen printed, said Cullen, who calls solar cell manufacturing an “inelegant process, compared to circuit board and semiconductor manufacturing.” Some methods to improve screen printing include electroplating silver on top of a narrow conductor path, augmenting it. Other technologies call for an electroless bath to embed silver into the nooks and voids of the sintered silver paste. Plated metal conductors of all sorts are also in early stages of implementation. Metallization expertise is needed, as various combinations of silver/nickel and copper layers are still under development. Plating can create a 40-µm-pitch conductor, whereas screen printed conductors are 120 µm wide.
The decision to manufacture with screen printing or with a different metallization system impacts costs. The capital equipment investment for metallization technologies is steep; however, it eliminates the waste (breakage), consumables cost (silver paste), and efficiency problems (shadowing, wide conductors) of screen printing. Factor in the huge scale of solar cell throughput, and the equipment costs aren’t terribly overwhelming.
Electronics manufacturing is a mature market, as Cullen noted, but it is built on solid expertise, automation, and cost-sensitivity. It experiences about 5% annual growth. The solar energy sector sees roughly 40% growth annually, with solar technologies persevering through the recession. Right now, capacity outpacing demand, as new entrants are getting poised to produce 2012 demand. The 3 gigawatts of excess production drives retail costs down, increasing demand, leading to extra capacity. This is all typical of a fast-growing industry.
Is there profit to be made in solar cell manufacturing? Make-where-you-use means PV manufacturing could become a major industry in the U.S. and other developed nations. Module prices are falling, Cullen reports, but this is mainly due to a drop in the price of silicon and other raw materials, so PV maker’s profits remain intact. There is room for cost reduction in PV manufacturing, Cullen adds. Profitability looks more sustainable in solar than ever before. Challenges for entry into the photovoltaics manufacturing field will come from the investment side, as capital is harder to obtain during this recession. Cullen compares the growth rate of PV to that of semiconductor manufacturing from 1981 to 1994. The PV growth predictions from analysts mirror this historic growth path of semi.
Different solar applications require different manufacturing processes and emphasis, so consider niches such as space applications or military applications in solar. While experience in military PCB manufacturing may not translate directly process-to-process for military solar panels, an understanding of the use environment, reliability expectations, and mobility requirements will prove valuable. Similarly, if you are accustomed to manufacturing high-volume, thin, consumer-product PCBs, this knowledge can be ported to solar cell manufacturing with low cost/cell and minimal waste. To covert from circuit board manufacturing to solar cell production (or extend your electronics business into the solar sector), you need capital, guidance from experts in the solar field, a strategic plan for implementing solar production, and possible partnerships in the sector.
:: Click Here to View Cullen's Presentation on the IMAPS Website ::
Meredith Courtemanche, executive editor
About Don Cullen
Don Cullen is the managing director of photovoltaics at MacDermid (Waterbury, CT). His group is responsible for interacting with the worldwide photovoltaic manufacturing supply chain to ensure the correct development, deployment, and use of chemical processes. The Photovoltaics Solutions division was formed from MacDermid’s New Business Opportunities review team in 2008. Cullen previously served as director of OEM & assembly applications within the Electronics Solutions business. He acted as a liaison between the OEM sector, PCB manufacturers, EMS providers, and MacDermid’s Electronics Solutions worldwide business. Cullen helped found the Final Finishes group in MacDermid Electronics Solutions, which includes nickel/gold, silver, tin, OSP, and palladium processes for PCB technology. He holds three patents, and authored the latest edition of Coombs’ PCB Handbook chapter on Surface Finishes, among over 100 other publications and industry papers. Cullen holds a degree in chemistry from Rensselaer Polytechnic Institute (RPI).