SOLAR

I have been asked to explain why someone would want to use rotary sputtering targets instead of planar sputtering targets.

Certainly there is some expense involved with larger targets and new equipment (assuming you are currently using a planar system), but in a high volume process (such as roll-to-roll thin film deposition) the advantages lead to a lower cost of ownership:

• Compared to planar targets, rotary targets generally have more surface area per given length.

• Rotary targets have much more surface area, so the magnetron power can be spread out over a larger area in a given amount of time. This helps keep the target running cooler, decreases nodule formation, and reduces the occurrence of arcing.

1. Since rotary sputtering decreases nodule formation, targets can have longer continuous runtimes.
2. There is generally more material available to sputter on a rotary target, which increases runtimes.
3. Rotary target utilization is usually ~80%, as opposed to ~30% for planar targets – which decreases scrap and increases runtimes.

• Rotary targets are well suited for continuous sputtering processes. Continuous processing increases throughput since there is less time wasted preparing the sputtering chamber.

• Rotary targets are more cost effective for high volume processes. They provide a good platform for long runtime processes, with less chance of defects and downtime.

• Planar targets are still best suited for prototype work or elemental experimentation, especially when large amounts of material are not needed at once.

If you are interested in discussing sputtering targets, contact our team at: Solar@Indium.com

~Jim

I was recently asked to gather some data comparing Indium Corporation’s tabbing fluxes and our largest competitor’s leading tabbing fluxes. Using a new method of solder spread testing found in an upcoming issue of Global Solar Technology, two Indium Corporation tabbing fluxes were directly compared to three of the leading competitor’s fluxes.

The test consists of these simple steps:

• Apply flux to cell
• Dry flux on cell
• Apply solder preforms on cell metallization
• Reflow on a hotplate
• Measure solder length

Finally, the measurements are plugged into the equation:

S = (L_f/L_i)100-100

                   Where:         S = Increase in preform length

                                      L_f= Final solder length

L_i= Initial length of preform

In the end, the Indium Corporation tabbing fluxes (GS-3434 and GS-5454) both caused the solder to spread ~44% further on a given cell – compared to only 13%, 15%, and 16% for the competitors' fluxes.

If you’d like to learn more about the test method or the results, or want help conducting your own evaluation, send me an email at solar@indium.com.

March 13th is the 78th anniversary of the founding of Indium Corporation.  Dr. William S. Murray, J. Robert Dyer JR, and Daniel Gray combined to create a company that was, in 1934, on the cutting edge of technology at the time - and that still is today.

Although some of the initial attempts to utilize indium were decidedly low-tech (plating of silverware and use in gold dental alloys), the first real breakthrough came when Mr. Dyer developed the process to indium-plate aircraft engine bearings to make them last longer.  Today our indium metal is in thermal interface materials, batteries, medical devices, aerospace devices, solar panels, flat panel displays. Of course, the full range of Indium Corporation products (including materials that contain no indium at all) can be found in a myriad of electronic devices.  We hold a wide variety of patents and have conducted endless tests and experiments including some aboard the space shuttle.

In between we have been featured in the Wall Street Journal, Business Week and many other technology journals and received awards for our technical expertise and our customer service.

Our original founders were very "hands on" in their approach to developing their company and we still follow that approach today.  Our sales and technical staff, locally located around the world, are as comfortable in a lab or on a production floor as they are presenting a technical paper.

Contact us at AskUs@indium.com to utilize our expertise and let us help you with your challenge.

Shown here is an original bottle of indium solder preforms with a hand written label.  Today we have a variety of packaging options with printed labels and bar codes to fit your product and application.

Carol Gowans cgowans@indium.com

I recently had a chance to catch up with a friend and colleague, Jasbir Bath. If you’ve spent time in the electronics assembly industry you have most likely met him, heard of him, or used an industry standard that he has helped create. Jasbir is a founding member of The Solar Engineering & Manufacturing Association,  SEMA. Who better to talk to about a new association than a founding member?

Jim: The Solar Engineering and Manufacturing Association (SEMA) is a relatively new association for engineers in the solar industry. Can you tell me a little about why it was created?

Jasbir: It was created about 2 years ago based on a need by the solar engineering/manufacturing base to address issues in the industry. There are many organizations in the solar industry but none are wholly dedicated to the engineering/manufacturing profession. SEMA was formed to address this need. We are working to address a number of gaps in the industry highlighted by the SEMA membership which include Education, Training, Standards, Reliability, Cost Reduction and Technology Gaps.

SEMA is a group of engineers, manufacturers and related professionals in the solar manufacturing and related disciplines who volunteer to conduct activities in the organization. The projects/programs we work on are driven by the active involvement of the membership.

Further details on SEMA and what we do can be found on the SEMA website at www.solar-ema.org

Our membership costs are low as we are not an organization looking to make a profit but to encourage participation and work to advance the solar industry as well as advancing education, training and collaboration within the solar manufacturing industries.

Jim: I heard there’s a new solar conference coming up? Can you tell me what makes this one different than all the other solar conferences we go to throughout the year?

Jasbir:  SEMA is collaborating with SMTA (Surface Mount Technology Association) to develop a conference meant for engineers and managers in the field to look at the areas of concern in the industry and develop ways to address them. We don’t see a similar conference to this which covers such a broad range of subjects which is specifically focused to address the needs of the industry. The program will consist of presentations and discussion covering the reliability testing of PV Modules covering gaps and where future work needs to be done. It will highlight various reliability programs being done in the industry with an assessment of current and evolving standards in manufacturing and reliability.

We are pleased to have a great line up of speakers and presentations. SEMA will present its reliability report assessing the reliability of PV modules at the conference. We will also have speakers from UL, IPC and NREL to discuss international solar standards together with a discussion of the work of the PV QA Task Force forum from leaders in that Task Force group. Areas covered will include temperature, humidity, voltage, mechanical and UV testing of PV modules and diode testing.

We will also have presentations on the reliability of microinverters/inverters and future trends from organizations including Sandia. PV Manufacturing Issues will be discussed by companies including Flextronics. The Global Solar Outlook will be reviewed by companies including Navigant, Custer Consulting and Prismark. Finally we will review general PV Module hazardous issues such as Electrical and Fire Concerns and well as Module Warranty/ Traceability Issues.

In addition we have industry leading training courses at the event on PV Module Manufacturing and Troubleshooting and PV Standards in addition to exhibitions.

The SEMA/SMTA Conference, Training Courses and Exhibition are from March 21^st to 23^rd at the Fairmont Hotel in San Jose. Further details on the program and sign up can be found at http://www.smta.org/solar/

Jim: One more question for you Jasbir. I know from working with you in different associations, that you are personally invested and involved in the future of module assembly. What attracted you to this field, and what keeps you interested in it?

Jasbir: I have been involved previously in the electronics manufacturing industry during the transition from tin-lead to lead-free soldering due to environmental legislation requirements. This was a challenge being involved in both from a technical and logistics perspective, but it was also fun as you saw the rewards of your efforts when the transition occurred successfully.

The solar/PV industry has challenges in addressing how to produce good quality and reliable products at lower cost, and it gives me the opportunity to try to make a positive contribution in an evolving expanding industry.

Jasbir and I look forward to seeing you in San Jose!

~Jim

As reported in Metals Bulletin, Malcolm Harrower of Indium Corporation recently addressed the topic of indium availability and supply as he told the delegates at the Minor Metals 2012 conference in Brussels that:

• there is no shortage in the supply of indium metal
• nearly 1,500 tonnes of indium was produced in 2010
• there are 50,000 tonnes of proven indium reserves in existing mines, a volume that will be sufficient to satisfy demand for the next 75 years,

Just 80 years ago, the potential for indium was just being discovered.  An article that I found in the archives of Science News from 1932 indicated that 10 lbs. of indium was due to be produced that year and it would give scientists a chance to do some great research on the possible uses of indium.  Twelve years later in 1944 another article was written on one of those uses which was to lubricate ball bearings to make them last longer (an application still in use today).  That article stated that the output had reached 500,000 troy ounces (34,250 lbs). 

Now 80 years after indium was first commercially produced, the yearly output has reached nearly 1,500 tonnes (3,300,000 lbs) per year, with about two-thirds of that being reclaimed and recycled material.  The versatility of indium has certainly driven that growth into all kinds of applications including:

1) Touch screens

2) Battery chemistry

3) Electronic thermal interface materials

4) Solders

5) Cryogenic and hermetic sealing

6) Solar panels

And as technology evolves, we expect to see more uses as time goes on.  Learn more by visiting our web site at www.indium.com. Or email/call me to discuss your needs.

Carol

cgowans@indium.com

+1-315-853-4900

No one likes being controlled by the cost of silver. We deal with fluctuating Ag costs here at Indium Corporation on a very large scale – so I understand the issues with using Ag-filled low temperature metallization paste for thin-film solar cell interconnection.

People always ask for alternative fillers like copper – although the chemistry of metallization paste doesn’t allow the substitution of most filler materials. Our solution is a new material: silver-plated copper particles.

Silver-plated copper particles allow us to utilize a very low amount of silver precisely where it needs to be, on the surface of the particles. By tricking our metallization paste chemistry into thinking it is still working with silver flakes, we are able to maintain the same high levels of flexibility, fine line printing, and adhesion that we have become accustom to with materials such as LT-918 metallization paste.

Due to the inherent bulk conductivity difference between copper and silver, very lowest resistances will still be achieved with solid silver flake metallization pastes. The silver-plated copper material has performed unexpectedly well in electrical performance though, winning over some customers due to a substantial difference in price.

Our new silver-plated copper particle material is currently in beta testing, and has completed over 2,000 hours of dry and damp heat testing. Our data so far has confirmed superior print performance, and customers like the fact that the material can be shipped at room temperature. If you are interested in beta testing the material, please let me know.

~Jim

After the report by Isofoton regarding reliability testing of Bi-based alloys for tabbing ribbon, the world learned that Bi-based alloys could survive the lamination process and function in use. If you haven’t seen it yet, I consider this mandatory reading! Here is the info: B. Lalaguna, P.Sanchez-Friera, I.J. Bennett, L.J. Caballero, J. Alonso, “Evaluation of Bismuth-Based Solder Alloys for Low-Stress Interconnection of Industrial Crystalline Silicon PV Cells", 22^nd EU PVSEC, Milan, 2007Milan, 2007.

We all know the Bi based alloys like 57Bi/42Sn/1Ag and 58Bi/42Sn can be used in a standard module assembly process, but is there an advantage to using Bi/Sn or Bi/Sn/Ag when Sn/Pb and Sn/Pb/Ag alloys are so well known and trusted in the industry?

I’ll give you 3 benefits:

1)    1) Bi/Sn/Ag and Bi/Sn are Pb-Free

2)    2) Bi/Sn/Ag and Bi/Sn are low-temperature alloys, they allow you to lower your tabbing process temperatures

3)    3) When paired with the correct flux and metallization, these Bi alloys form a powerful bond without microcracks (due to the lower process temperature)

Below are results with SunTab^TM ribbon assembled on a Komax X series stringer and tested on a XYZTEC Condor 150-3 bond tester (provided by the respective companies).

You’ll probably notice the lack of y-axis scale – I’m not going to give away all the cool information that easily! Contact me at jhisert@indium.com to learn more.

Yes, here in the central New York (CNY) region, a lot of state-funded activity is beginning to bud, even in the middle of a New York winter. Local academics have been busy. Professor Wolf Yeigh, President of State University of New York Institute of Technology at Utica/Rome (SUNY-IT) recently commented on his team's plans for academic excellence in nanotechnology and semiconductors:

"The projected Computer Chip Commercialization Center (Quad-C) and Center for Advanced Technology (CAT) complex will be on the main campus of SUNYIT. Construction will begin this year, and we envision that the complex will be 120,000 ft² of lab and office spaces complemented by up to 30,000 ft2 of clean room for Quad-C. The academic CAT building will be around 65,000 ft2 of academic and research space. The two buildings will be connected by a rotunda collaboratorium, and the entire complex layout will be similar to what you'd see at the Center for Nanoscale Science and Engineering (CNSE) in Albany, allowing a free flow of academic and industry R&D interaction along with the standard teaching and learning spaces.

Rather than duplicating fundamental research done at CNSE, our facility will emphasize further application and integration of nanotechnology research and development, including testing and evaluation. The academic departments at SUNYIT, working in conjunction with CNSE faculty, will offer courses and programs in nanotechnology applied to semiconductors, materials, informatics, biology and engineering (electrical, computer, civil, mechanical, bio, and materials).

Our major connectivity within the NY school system will be with CNSE. We will also work with community colleges and private institutions in the regions just as CNSE works with community colleges and institutions in the Capital Region and beyond."

The not-for-profit Mohawk Valley (MV) Edge group has been actively promoting the area as suitable for development, with control over 400 acres of land leased from NY State adjacent to the SUNY-IT facility in Marcy. Despite the fact that several years ago, the MV Edge failed in its bid to have AMD (now Global Foundries) locate their fab in Marcy, the region still stands ready to host a manufacturing facility. Already appropriately zoned and wetland permit-approved, with all new infrastructure ideal for a semiconductor fab or similar high-technology facility, the area may be ideally suited - if not for a fab - certainly for BEOL / 2.5D and 3D assembly processes, as the site is an easy drive (less than 2 hours) from the Global Foundries Saratoga Springs, and the adjacent SUNY-run CNSE facility in Albany, the New York state capital.

Local semiconductor, solar and LED-focused companies like Indium Corporation, and the first tenants in the proposed Quad-C building, Valutek and nfrastructure, will derive benefits from the close proximity of the SUNYIT facilities.

Nestled in the foothills of the Adirondack mountains (which remains the largest park in the United States), it looks like a brand new chapter may be about to be written, as the small Mohawk Valley region transforms from its old electronics moniker "RF Valley" to "Nano Valley".

Cheers!  Andy

Recently I was testing the resistance of a new low temperature metallization paste* (for solar photovoltaic assembly) in the lab. The samples were initially tested with a 4-point probe, just before entering a chamber set at 85°C and 85% relative humidity. To my surprise, the resistance dropped noticeably (as seen in the chart).

I brought the results to the material’s creator in our R&D department, ready to wow him with my discovery. I exclaimed, “I just finished testing the samples we put into the 85/85 chamber and can’t believe the values I’m getting!” Without a flinch he replied: “The resistance went down, didn’t it? That’s a unique feature of this material.”

While I didn’t gain any cool points in R&D for discovering an awesome new feature of an upcoming product, I hope the trait of this material can be useful for our customers (some of whom have since noted the improved characteristics after reliability testing).

The thing I learned from this experience is how important end of life testing is for metallization paste – all too often samples are only compared based on time-zero testing. This will change the way I compare metallization pastes from now on.

~Jim

*For my followers who aren't familiar with low-temperature metallization paste,it is also referred to as "grid ink", "silver ink", and "conductive ink". Low-temperature metallization paste is a silver-filled contact material used in the assembly of photovoltaic solar cells. It gets its low-temperature label because it is processed at lower-than-traditional glass frit temperatures of ~1,000°C. In addition to its role as a contact for thin-film connections, low-temperature metallization paste is also useful as a low-temperature alternative metallization on Si-based cells.

Learn more here.

Here is a list of tricks to help you overcome the issues that can arise while hand soldering silicon-based solar cells (and other applications as well). Some of these ideas are obvious for most, but all the suggestions can help you form a better solder joint - and build a better final product:

1)    Use the correct soldering tip. I’ve made the mistake of using an inappropriate solder tip before, and so have many of my customers. It’s a frustrating problem you will only let happen to you once: everything is set up perfectly but nothing will melt, until you notice the solder tip is not the correct size or shape. This has happened to many of my customers who were initially using cone point soldering tips when they were working with 2mm wide solder coated tabbing ribbon. Simply changing the tip to a 2mm wide chisel point made all the difference, and promoted soldering readily. Why such a big difference in performance? The chisel tip allows heat to flow across the ribbon, instead of only heating a single point. More heat flow = more heat in your solder joint.

2)    Pre-tin the soldering iron. Just as an appropriately sized soldering tip will distribute heat across the soldering surface, a bit of molten alloy can help create a thermal interface to maximize heat transfer. Remember to melt a small amount of solder onto the tip of your iron before soldering, and be sure it’s the same alloy you are soldering with. (Leave the custom alloying to us ;)

3)    Consider the alloy you are soldering. All the heat your typical soldering iron can produce will not be enough to melt some of the highest temperature alloys. Be sure to have a good understanding of the alloy you have selected. In some cases with low-temperature alloys (like bismuth or indium alloys), excessive soldering temperature can de-wet the alloy and char low temperature fluxes.

4)    Use the correct flux. Fluxes are quite different, I’ve spent my entire soldering career trying to get that point across. There are fluxes for high temperatures or low temperatures, cleaning with water or not cleaning at all. There are specialty fluxes for specialty alloys and there are fluxes for different soldering surfaces. Use the correct flux. If you don’t know what the best flux for the application is - just ask; that’s what I am here for.

5)    Use a bottom side heater. Silicon is known to pull heat away – that c-Si solar cell that needs to be soldered is a heatsink! Some solder equipment vendors also provide underside heating pads to help prevent excessive heat loss.

6)    Keep your soldering iron clean. That black crud that builds up on your soldering iron tip, it’s not helping you form a good solder joint. Those oxides and charred flux residues can easily be removed by wiping the hot iron across the wet sponge (that should be at your soldering station). A clean tip will lead to better heat transfer, and it will make the fluxes you use more effective.

This is the soldering station I use, it’s a PS-900 supplied by OK International. Just about any soldering iron will work, but they won’t all work as well – or come with as good support.

I’m still learning all the tricks to hand soldering, so feel free to share any you have learned over the years!

~Jim

As unlikely as it sounds, your reaction to this picture is probably similar to my reaction to Solar Power International 2011. Allow me to explain…

Aside from the fact that both the picture and the conference took place in Dallas Texas, there was another similarity: The show seemed to lack a clear audience. Just as you might ask, “Why am I looking at this picture?”, or “Why did you take that picture?”, I could not answer my own question of “Who is the audience for SPI 2011?”.

At SPI there were vendors who were selling retail solar water heaters, there were big name module assemblers, and there were materials manufacturers like us. There was no clear group of people on which the tradeshow seemed to focus. The result was a slow stream of traffic throughout the show compared to events like InterSolar, PVSEC, and SNEC.

In the end, it was still a good chance to meet with some industry partners, and with customers I haven’t seen in a few months. It was also a great chance to work with the IPC team on the upcoming module assembly documents. That, in itself, was a good enough reason to visit Texas!

~Jim

A friend recently mentioned to me that I don’t look like I’m really happy in my pictures online, this one is for you…



I found this picture that someone took from across the way at the PVSEC (European Photovoltaic Solar Energy Conference and Exhibit) in Germany a few weeks ago. (It has been zoomed in and cropped.) I don’t always love to travel, but I must admit that this was a very good trip. Our team had a great time in Germany – and met with many of the key people we talk with throughout the year. I felt that the show this year was a little slow, although our conference room was almost always full and our leads have been rather successful so far.

So here’s what I thought about the 2011 PVSEC:

• The conference hall (as usual) was a long walk from the exhibition. Tech guys are sometimes spread thin between working at an exhibit and catching a presentation. It would be great if it was easier to juggle these activities.
• Germany IS the location for the premier solar show of the year, good job!
• There is so much to see. Four-day tradeshows are long, but this one stayed interesting with so many things going on.
• It’s good to see so many equipment vendors still showing off their products. Other shows this year have been (in my opinion) light on equipment, but the PVSEC is the place to be to get demos – especially for tabbing/stringing lines.

If you made it out to the show, feel free to leave a message - I’d be interested in knowing what you thought of the PVSEC this year!

Your PV Application Engineer,
~Jim

Last week I spent some time in the simulation lab with Eric Bastow, verifying the printing characteristics of our newest low temp metallization paste LT-918. Due to its current success with a variety of customers, we needed to take production capacity to the next level. New equipment was purchased to keep up with the demand, but there is always the chance that material may not perform the same when it is made in substantially larger batches. Our testing confirmed the printing characteristics of the material made on the new equipment surpassed that of previous batches. That’s good news for everybody.

As you can see from the picture, we used a standard printer designed for stencil printing solder paste onto electronic circuit boards. The printer was not the only similarity to solder paste printing though. An interesting characteristic of LT-918 is that it has a higher viscosity than most metallization pastes, which helps with print definition. The high viscosity of LT-918 helps it print like a solder paste, this is great for solder paste printers (like Eric and I, and many of you for that matter) from the SMT and semiconductor assembly industries.

In my opinion, LT-918 is the best metallization paste currently available for interconnecting thin-film cells. It has not only excelled in printing, it also has industry-leading resistivity scores, and has passed customer reliability testing including thermal cycling, damp heat stability, and accelerated UV tests. Much of the data that we can share will be available soon as a product brochure that we hope to have ready for you at EU-PVSEC in September.

Typical Tabbing Ribbon Solders

Only a few solder alloys have become common, industry-wide, among solar module assemblers, and those can be pared down into three categories:

• BiSn alloys (58Bi42Sn, 57Bi42Sn1Ag)
• SnPb alloys (63Sn37Pb, 62Sn36Pb2Ag)
• SnAg alloys (96Sn4Ag)

Tin-Silver Solder (SnAg)
SnAg has become the most widely used Pb-free solder alloy, particularly in tabbing ribbon designed for cell interconnection. Historically, its melting temperature (221°C) made it an obvious replacement for processes previously running SnPb solders.

In designs where step soldering is necessary (however uncommon in back end solar module assembly), SnAg can be used as the step previous to soldering with Sn63 or similar Pb-Free solder (albeit carefully since the second soldering temperature is quite near 221C). 

While SnAg eutectic solder is a desirable composition for electronic component soldering, for instance, power semiconductors, recent studies using this alloy for stringing solar modules have indicated that the other common alloys listed for this application are easier to work with and better designed to meet the needs of this solar assembly application.  SnAg does have a high melting temperature, and the preferred fluxes for module assembly are not yet optimized for this solder composition.     

Regardless, SnAg has its benefits.  When a solder that melts somewhat above the melting point of a “standard” solder alloy is needed, and it must be Pb-free, this is it!!  Check it out!

Happy Testing!!

Amanda

I recently had a discussion with Frank Zimone (VP of Business Development at Angstrom Sciences) about sputtering target utilization. He stressed the point: although "material by weight sputtered off the target" is how most folks define the ‘target utilization’, when judging the efficiency of a process, it is only the material that makes it to the product that counts. Frank said:

“What is happening now, is that we are seeing that many companies, after the rush to set up a process to create a good product and “get to market”, are now working on dialing in the process to save money by lowering production costs. This can be achieved by putting more of the target material onto thin-film cells, and wasting less by depositing less of the material elsewhere in the production tool.

“We have recently completed a study with a major photovoltaics company which evaluated enhanced magnetics from multiple competitors.  In a back-to-back comparison with identical process conditions (power density, line speed, etc.) both targets were utilized ~85%  as measured by weight loss.” (Remember folks – this is application specific.) “The main difference between the seemingly similar depositions was that one set of magnetics yielded 20% more material on the substrate.”

I asked the obvious question at this point: “How was that possible?”

Frank replied:

“One set on magnetics was able to get the 2 erosion racetracks more closely aligned, and more perpendicular to the target surface. This translated into higher dynamic deposition rate and less wasted material on the chamber shields.”

It’s a simple concept if you understand the physics of sputtering, and Frank agreed that most customers know this from an academic point but do not have the time/resources to properly test. He said, “More established customers are now looking into these particular issues.”

To learn more about moving magnetics, contact Frank Zimone at FZimone@angstromsciences.com or stop by and see him at InterSolar this week!

I'll be there, as well. Look for me in the Indium Corporation exhibit #5325.

~Jim

Today I received an interesting email that could be useful for my readers. Here goes:

“Dear Jim,

I saw your recent blog. I am in the process of prototyping a photovoltaic application. I am aware that Indium Corporation has a lead-free alternative for tabbing and bus wire. Can you comment on why the photovoltaic industry, specifically in the US, has not adopted this standard as a better non-toxic solution and what Indium Corporation has done to promote this alternative? I look forward to hearing your point of view!

Best Regards,”

That’s definitely an important question, what an ice breaker! This was my response:

“First of all, thank you for reading the blog and thank you for the thoughtful question.

What many people do not realize, is that there are actually a few different types of lead-free alternatives for cell tabbing. The 3 most common alloys for tabbing ribbon are :

• 96.5Sn/3.5Ag
• 57Bi/42Sn/1Ag
• 58Bi/42Sn

Here are the main reasons that people stick with Sn/Pb based tabbing ribbon coatings:

• Sn/Pb and Sn/Pb/Ag have been extensively proven with many different module designs  
  
• Indium (the metal) based alloys are quite expensive compared to Sn/Pb based alloys
• Sn/Ag melts at a higher temperature range, causing greater expansion of the base copper (and therefore greater coefficient of thermal expansion mismatches).
• Some people fear the melting point of Bi/Sn and Bi/Sn/Ag may be too low for their subsequent processes (such as lamination)

The key point I’d like to note is that there are companies currently using each one of these alternative, and finding them feasible in regards to cost and reliability. We promote the use of these alloys - I would personally like to see the 57Bi/42Sn/1Ag alloy take over the market. I like to see my customers making good modules and feeling good about the materials they use too!

All the best,

          ~Jim”

Later on in the day we discussed the technical aspects of using lead-free alloys and settled on Bi/Sn/Ag and GS-5454 as the go-to materials. It was great to have this conversation with someone focused on conscious material selection and eager to learn more about lead-free options.

What are your thoughts?

On behalf of our solar PV team here at Indium Corporation, I’d like to mention how excited we are to see you at Intersolar in July. I look forward to going to this event every year; what’s not to love? A beautiful city, 2 simultaneous premier tradeshows, and many of the customers, partners, and vendors I’ve been planning on meeting or just catching up with.

I hope that you do stop by and say ‘hello’. If you’ve already mapped out your stops at the show I’d like to note that we will be located in a different aisle than originally planned. According to the event organizers:

“Currently Indium is located in booth 5228, we will be relocating you to booth 5328.  Please reference the attached floorplan for your new location as well as access the online floorplans for an overview of North Hall. The new location has been updated in the print directory now in development as well as with our vendor partners for all orders submitted to date.”

Here’s the important message: come visit us at booth #5328!

Send me an email if you want to set up an appointment to chat.

~Jim

As a tech guy, I couldn’t be more excited about testing these 8 different c-Si solar cell / metallization designs!

Q1) What the heck are we looking at in this picture?

A1) It’s a CuGa (copper gallium) target being sputtered at Angstrom Sciences, Inc. test lab. Since CuGa rotary sputtering targets are becoming more popular in the CIGS deposition industry, we wanted to see how they work with AS cathodes. The result: a winning combination!

Angstrom Sciences Lab








Q2) Why haven’t Cu-Ga rotary targets been more popular for production of CIGS solar cells (a thin film technology)?

A2) The big problem has historically been segregation of the copper and gallium in traditionally cast targets. This was a hot topic for those who stopped by the booth at the Society of Vacuum Coaters TechCon and checked out our full size CuGa display target. It is only natural to question if a display piece actually works well in a production sputtering process. In order to make this product work, we had to manufacture it using our proprietary hybrid consolidation technique.

Without giving away all the juicy details, I can tell you that it was a learning experience and that there were some setup issues that led to improved applied power settings. Our customers have been pleased with the results of our CuGa targets, although the fine tuning is proprietary to them and we cannot share their learnings. Now we have a much better understanding of the maximum power we can use for this type of target. That's why it was so important to work with an equipment supplier.

One thing that is obvious from looking at the spent target is the lack of an erosion groove from magnet dwell - a nice feature of the magnetron that was used. The spent target is on display in my boss’ office. It serves as a reminder of the time we spent with the Angstrom Science guys sputtering the target, gathering data, and learning from the team.

This year’s Society of Vacuum Coaters Technical Conference was certainly as focused on vacuum deposition as it has been over the years, but we were delighted by the new emphasis placed on solar cell fabrication. As I mentioned before , one of our key topics was thermal evaporation material - although we also presented on the topics of nano-bonding sputtering targets and the availability of indium and gallium. Along with these topics, the audience was treated to themes of cell fabrication, increasing solar cell efficiency, and roll-to-roll processing.

At the show, we had a chance to discuss new ideas with many of our existing and potential customers. Improved throughput and eliminating alloy segregation were hot topics at the Indium booth. Many customers wanted to learn more about CIGS materials like indium forms for evaporation, or full-size Cu-Ga, CIG, & In rotary targets for magnetron sputtering.

2011 raised the bar for the Society of Vacuum Coaters Tech Convention, I can’t wait for the 2012 event to top it!