Indium Corporation Blogs

I recently noticed something that appeared in a 3^rd party lab report that a customer shared with me. This lab report was an analysis of a NanoBond^® the customer had performed and sent out to verify. The thing that struck me was that the technician reported “This sample exhibited small fractures in the [NanoFoil^®] core material which we have seen before…” I started thinking about this, and there are very few products in the solder world other than NanoFoil that you would like to crack. In this case, cracking is a good thing!

You wouldn’t expect most soldering products to crack, but NanoFoil^® isn’t like other soldering products. As the aluminum and nickel layers react, the foil shrinks and tends to curl. Since the curling action of the foil is restricted, the foil cracks. Solder flows between the cracks and bonds to the reacted NanoFoil^® as well, creating a sort of micro-scale concrete.

Pretty interesting, huh? Here’s a link to learn more.

 

…And here’s a link to try it out!

It seems like a fairly simple thing to do.  What could be difficult about soldering a wire to a pad? 

Well, I hear three common complaints and expressions of frustration:

POSITIONING: Typically, in this process, a soldering iron is used. The first problem arises from trying to hold onto the soldering iron AND the wire to be joined to the prefluxed pad AND the solid-core solder wire you are using.  An extra hand would be nice! Some people use a system of fixtures or clips to hold the wire and the pad in the appropriate position. (see image and link, below)*.

COLD SOLDER JOINT: Another common complaint is that, after soldering, the wire easily pulls out of the solder joint.  This is due to the poor wetting of the solder to the wire and the pad - it never really "soldered".  A solution that I share is to pretin both the pad and the wire with the solder, using a flux.  To pretin the wire, I suggest melting some of the solder in a crucible or solder pot.  Dip the wire in the flux and then into the molten solder.  A teardrop should form on the end of the wire.  It can also be pretinned using the soldering iron. Next, pretin the pad. Both pretinned surfaces will have a coating of post-reflow flux residue.  If required, this residue can easily be removed using a suitable solvent.  Now that you have pretinned both surfaces, the pad should be heated with the soldering iron and, when the proper temperature is reached, the pretinned wire should be pressed to the pretinned pad.  The solder on both the pad and the wire will melt together and, when the heat is removed, the joint will be formed.  Usually this can be accomplished without adding additional flux.

INCONSISTENT VOLUME: A third issue is that the volume of solder in the joint is not uniform from piece to piece. If this is your concern, consider using a flux-coated solder preform. They can be produced with the exact solder volume, and the precise dimensions to fit onto the wire you are joining to the pad.  Similar to the process described above, when the pad and the wire are heated, the flux will be activated (removing the oxides) and the solder preform will melt, forming a consistent and perfect solder joint.

Please contact our technical support group with any questions you may have.  We are always ready to help you solve your soldering problem, whether it is large or small.

For more background, read these blog posts on hand soldering:

• soldering iron tip temperature
• hand soldering flux selection
• hand soldering tech support
• the importance of a clean soldering iron tip

 

Paul Socha

 

*Image: Harbor Freight sells a product called "Helping Hands" for (US) $6.99, as of this writing. Other companies offer similar products. Consider buying more clamps to hold the wire in place, freeing you to hold only the solder wire and the soldering iron.

It won't be long until we in the northern hemisphere are complaining about the snow and the cold, but right now, it is all about the heat! 

In particular about the heat that is needed to reflow high melting point (HMP) alloys.  These are generally high-Pb alloys that see very high operational temperatures. They are used for applications such as automotive under-hood or down-hole drilling equipment .

If you try and use a flux that is not formulated to withstand higher (greater than 220C) temperatures, your flux will burn off and char and never get a chance to really do its job.

So, the key is to use a flux that is specially formulated to activate at higher temperatures, like our 807HMP used in our flux cored wire.  It is ROL1 but has only 650 PPM of halogens.

You may also want to consider an alloy with a small amount of indium in it (such as Indalloy #164 which is 92.5Pb 5.0In 2.5Ag) since indium is well known for its thermal fatigue resistance.  This alloy works very well with the 807HMP.

Choosing the right alloy and the right flux are key to keeping your cool!

Carol

Folks,

Let's look in on Patty and her colleagues......

Sam Watkins, ACME New Hampshire site GM, had just finished meeting with his boss, ACME CEO Mike Madigan. He was embarrassed that these meetings always stressed him; Mike was an intimidating character. Still, why should he be nervous? Things were going really well. Profits were up at all sites since NMAC/I/O was implemented as their new profitability metric. Patty Coleman, who suggested this metric, visited all of the ACME sites with weaker NMAC/I/O and profits, and, after performing process audits, helped these sites get their acts together. Oh, and we can’t forget Pete Ortiz, who works for Patty. They seemed to have a terrific synergistic relationship. He was an integral part of this success story.

Sam started writing an email to Patty. He and Mike concluded that, building on the recent NMAC/I/O success, they need to make ACME a “copy exactly” company. They agreed that if they were implementing a copy exactly strategy they should do it with the most cost effective assembly equipment and materials. It seemed to both of them that that the lowest “cost of ownership” should be the most important metric in this strategy. Sam finished his note to Patty asking (ordering) her to implement this strategy. She was to present a plan to achieve this goal to Sam and Mike in 6 weeks. Her presentation was to include the recommended equipment and materials, a phase-in plan, the budget needed to achieve the goal, and the projected ROI of the endeavor.

Patty was in her office having lunch while reading Golf Digest and USA Today. She looked up at her laptop screen and saw Sam's email. Reading it energized her. She was happiest when working on a significant project. After digesting the contents she thought she would call The Professor and ask his advice. Sam and Mike had insisted that she put The Professor on a retainer as he had added so much value to ACME. Patty had to chuckle, it was hard to get him to send in his bill; he seemed little motivated by money.

The Professor would never tell her how many languages he spoke, so she was going to try a little French on him.  She and Rob had been studying it at home.

“Bonjour Professeur, comment ca va?” Patty cheerfully said as The Professor answered the phone.

“Très bien Patty. Comment sont Rob et vos fils? Ma femme et moi avons été inquiets au sujet de Rob. Est-ce le dos guérit bien?” The Professor replied with a Parisian accent. (Very well Patty. How are Rob and your sons? My wife and I have been worried about Rob. Is his back healing well?)

Patty sighed and thought, “Well that makes about 10 languages I have verified so far.”

“Rob is doing quite well. Word got around and my Lean Six Sigma Green Belt instructor, Jim Hall called and shared his thoughts with me about over doing it in exercise programs. Jim is a fitness instructor and a big believer in moderate exercise. Rob has promised me to tone it down a lot,” Patty answered.

“I’m relieved,” said The Professor, “Rob needs to be healthy to keep up with your sons.”

“But, I imagine you have some business to discuss,” the Professor went right to the point.

“Yes, Sam and Mike want me to head up implementing a copy exactly program with equipment and materials, and they are strongly suggesting that the equipment and materials have the lowest cost of ownership,” Patty summarized.

“Copy exactly can be very beneficial, if the materials and equipment are good choices,” The Professor answered thoughtfully.

“But I have real problems with ‘Lowest Cost of Ownership.’ It is a good metric to compare something like automobiles, but to compare equipment or materials that are used to generate a profit it can be misused.” he replied.

Patty felt she understood where he was going, but wanted to hear it from him.

“Can you give an example?” she asked.

The Professor answered, “Let’s say a man mow lawns for a living. He considers two lawn mowers for his business, one is a push mower that cuts a 20 inch path and costs $300. Assume he takes 3 years to pay off the loan to buy it. Maintenance is $150 per year and fuel is $1200 for a 30 week season. The other is a sit down lawn mower that costs $3000, with $500 maintenance per year and it uses $3,000 in fuel per year. It cuts a 50 inch path. Which has the lower ‘Cost of Ownership?’”

“That’s easy,” Patty said, “the 20 inch push mower.” “But clearly the lowest cost of ownership is meaningless,” she went on.

“Explain,” replied the professor.

Patty answered, “Well, the man is in business to optimize profit. Clearly he can mow more laws with the sit down mower. Let’s say with the push mower he can do 4 lawns a day and with the sit down mower he can do 10 lawns a day. We can also assume he gets $35 per lawn. So, for a New Hampshire 30-week lawn mowing year, he earns 4x7x30x$35 = $29,400 with the push mower and 10x7x30x$35 = $73,500 with the sit down mower. Let me make a spreadsheet to determine the profit in each case.”

Patty was one of those young people who could type so fast that it made The Professor’s head spin. In seconds she had a spreadsheet developed.

“Wow, with the push mower he only makes $27,950 and with the riding mower he makes $69,000!” Patty exclaimed.

“And the same is true in electronics assembly. The best equipment, solder paste, solder preforms, underfill, cored solder wire, and solder fluxes are the ones that help your company make the most profit. Not the ones that have the ‘lowest cost of ownership,’” The Professor summed up.

To be continued.....

Cheers,

Dr. Ron

image

Folks,

I thought I would post a few short thoughts as the new year begins. Here it goes:

1.    A billion hours ago the stone-age was the future, a billion minutes ago Caesar ruled Rome, a billion seconds ago Jimmy Carter was President, a billion passives ago you took your last break (about 4 hours ago). As exciting as the latest quad core microprocessor is, the largest number of components that we assemble is passives, approaching two trillion per year. That is about 6 billion a day. If you lined up all of the 7 billion people in the world, each year you could give every man, woman and child several hundred passives from all of the passives that are produced. If two trillion passives (assume 0402s) were lined up end to end they would circle the earth 50 times!

2.    Schools in Indiana are no longer required to teach cursive writing. Key board skills are considered more important.  Yikes! I’m all for keyboard skills, but I want my grandkids to be able to write in cursive. If not, how do they write their names? Are we less than a generation away from people writing their names as an “X?”

3.    Thoughts on lead-free solder reliability in long term mission critical environments from a NASA study:

        “Test vehicles assembled with lead-free materials (notably tin-silver-copper) exhibited lower reliability under some test conditions.”

Some people would respond to this statement by saying, “I told you that lead-free solder was no good.” However, another way of stating the results would be, “Lead-free solder performed better in more tests than tin-lead solder did.” The ratio, by my count, was about 5 to 3 in favor of lead-free. However, I agree that lead-free is not ready for mission critical (>20-year) service life. The main reason being that, in some cases, when lead-free solder joints failed in these types of studies, the results were much, much worse than tin-lead solder joints. These failure modes need to be understood and addressed. In addition, tin whiskers and pad cratering are looming problems in these, mission critical, long service life quadrant D applications as discussed in the Navy's Manhattan Project (http://www.navyb2pcoe.org/pdf/LFEMP_book.pdf).

 

4.    SACM has arrived. SACM is a SAC105 alloy that is doped with manganese. Work performed on SACM by Liu, Lee, et al was reported in a May 2009 ECTC paper, Achieving High Reliability Low Cost Lead-Free SAC Solder Joints Via Mn Or Ce Doping. The thorough testing reported in this paper suggests that SACM has promise as a material candidate for quadrant D applications mentioned in #3. In explaining the superior performance of this material the authors state:

“The mechanism for high drop performance and high thermal cycling reliability can be attributed to a stabilized microstructure, with uniform distribution of fine IMC particles, presumably through the inclusion of Mn or Ce in the IMC.”

 

We have had to wait awhile for this material to become commercially available as it is a challenge to manufacture doped solders like this in large quantities.  I think this paper should be on you "must read" list.

 

5.   I had not planned on reading Steve Job’s biography , as I thought I knew quite a bit about him from reading recent articles in Forbes, Fortune and Business Week. But I went ahead and downloaded it to my Kindle anyway. This work by Walter Isaacson is a masterpiece. To share one tidbit from it that relates to those of us in electronic assembly: 

"In almost all cases electrical engineers first design the circuits that perform the functions of some device like a mobile phone or tablet. Mechanical Engineers are then left to fit the circuits into the “box.” (Hence MEs are often called “box stuffers” by EEs). Jobs completely changed this approach. He told the engineering team how he wanted the product to look and function first, then they had to determine how to make it work that way. I’m convinced that only through this approach are the revolutionary design concepts that Jobs and Apple came up with possible."

The book also points out his many flaws (e.g. Jobs would regularly park in handicap spots, the author reports several times that Jobs just didn’t think the rules applied to him, etc.). Another interesting thought (read it and see if you agree with me) that if Steve was not Paul Jobs' adopted son, Apple would have never happened.

 

Cheers,

Dr. Ron

Solder wire is generally used for manual soldering operations, including rework.  But, it can also be used in automated applications such as die-attach soldering.  Solder wire can be flux-cored, or solid with a separate flux used.

Each application can have different requirements for the wire.  For example, wire used in die-attach applications needs tight dimensional tolerances to insure an exact, repeatable amount of solder is deposited each time.  Reduced oxides are also critical to eliminate any "splattering" of the molten solder during the deposition process.

Wire can also be used for non-soldering applications. For example, indium (and indium alloys) wire are often used as a sealing material (particularly in cryogenic sealing applications) - more here) and as a thermal interface / management material.

Decades ago, 0.030" (0.76mm) diameter was the standard size, but today we are able to produce diameters as small as 0.001" (0.025mm) in tin silver (Sn Ag), tin silver copper (SAC) and gold tin (Au Sn) alloys.  Considering that a human hair is about 4X that size, that is a very small diameter!  Pure indium wire is limited to 0.010" (0.254mm), but alloys containing indium can be produced smaller than that.

The wide variety of diameters available in Au Sn make this alloy ideal for the complex applications in medical, aerospace, and other high reliability applications.  However, the Sn Ag and the Sn Ag Cu are used across a variety of standard applications that require lead-free materials.  Sn Ag is particularly good in soldering to Nitinol.

At first look, wire seems like a pretty simple product.  But specifying the right alloy, diameter, tolerances, and packaging can make all the difference.  It can help you achieve a repeatable process that gives you high yields, strong solder joints, and enhanced profitability.  For further information - contact me.

Carol Gowans

Folks,

Technology: Always Advancing?

I believe most of us think of technology as always advancing. A quick look at the evolution of mobile phones or laptops would quickly strengthen this argument. Looking at a photo of these devices circa 1985 will always cause a chuckle. In addition to their performance and appearance improvements, those of us in electronics assembly are also aware of the significant improvements in component packaging, PWB design, and soldering materials and processes.

But I argue, with a little “tongue in cheek”, that there has been some technology retrograding going on too. The photos below show one case in point. The black Casio calculator watch can be purchased today at Wal-Mart. It has been unchanged for more than 15 years. It is a simple add, subtract, multiple, and divide watch. It also has an alarm function. The silver Casio watch is much more sophisticated. If you look carefully, many extra buttons can be observed. It is essentially a “full scientific.” It can do trigonometric functions, exponents, etc. So one might think it is from the year 2011. Wrong! It was purchased in the early 1980s. They now sell used for >$300 on Ebay. Sadly, mine needs repair. So if you like scientific calculator watches, you live in the wrong era.

Another example is the smart phone. Originally, it appeared to be a combination of a Palm Pilot and a mobile phone. It was great for me. It kept my calendar, and contacts, and it could be used for taking notes and maybe even had a spreadsheet type of function. 

I purchased a Droid X  last October. I love it. With all of the widgets it can do many things. The core functions of calendar and keeping contacts are there. But for note taking and spreadsheet functions one has to search for widgets that clearly are not main stream. Essentially the smartphone has morphed from a productivity tool to an entertainment device. Not that this is necessarily bad, but a major change.

The other interesting fact of modern smartphone ownership is that the norm for storing data is in the “cloud” . When I asked the salesperson how to store all of my mobile phone data on my PC, he looked at me with an expression that seemed to say, “Why would someone want to do that?” I had to find out how to store my data on my computer myself. It involves adding an extra software widget on my phone…….for $40!

Oh well, time to go for a power walk. I think I’ll use Ride Tracker on my Droid, while I listen to music too.

Cheers,

Dr. Ron

Jon major recently joined the Indium Corporation as a Product Manager for Solar back-end assembly products. I greeted him with this impromptu interview.

Jim: First of all Jon, welcome. It’s great to have you as a new addition to the team!

 

Jon: Thank you Jim – it’s an exciting time to be at Indium Corporation and a fantastic time to be a part of the growing solar industry. I am extremely enthusiastic about my new position and am looking forward to making a positive contribution to the solar industry.

 

Jim: I noticed it didn’t take you long to get up to speed. Your time in Silicon Valley must have helped.

 

Jon: Coming from the electronics industry with a focus on product development, new product introduction, manufacturing, and external partner management, I am excited that my past experiences can contribute both to the industry and to Indium Corporation. After joining Indium only a few weeks ago, not only am I getting used to Upstate NY weather, but I have been immersing myself in solar with the goal of gaining a comprehensive understanding of:

 

•       Both rigid and thin-film technologies

•       Technology trends

•       Global and regional markets (EU, China, US, North America)

•       Solar supply chain (Silicon, wafers, cells, module, equipment, inverters, integrators)

•       Equipment manufacturers, contract manufacturers, and how we can collaborate with them to move the industry forward

•       Our products and pricing

•       Our current and future customers

•       Our short and long term opportunities

•       Our competition

•       Our roadmap

•       Our strengths, weaknesses, and threats

•       Our manufacturing capabilities and our QA process

•       Our sales channels, value proposition, key differentiators

•       All Indium processes

 

Jim: I know you've got solar products on your mind. Let our readers know a little bit more about your role here at Indium?

 

Jon: As a Solar Backend Product Manager I will focus (officially) on the business development and growth of Indium’s Solar Back End product offerings.  Now that sounds great but what does it actually mean? I could cut and paste my official job description but I prefer to explain it in my own words. As I think about the first part of that statement, “business development and growth…”, I see my role as:

 

–      Know the market, the customers, the product, and the competition

–      Develop relationships with the Indium team, reps, partners, equipment manufacturers, and, of course, customers

–      Write valuable data sheets, publications, and sales literature

–      Listen to our customers' needs and provide solutions

–      Manage schedules and orders with minimal surprises

–      Build cross-functional collaboration (sales, distribution, marketing, engineering, R&D, QA, production, management)

–      Never let down partners or customers

–      Support all functions of the organization, both internal and external

–      Deliver above & beyond commitments

–      Make great bets – on technology, customers, and opportunities

–      Understand the product life-cycle

–      Ship high quality, consistent product

 

The second part of that statement “..of Indium’s Solar Back End product offerings” is fairly straightforward. Of course this means I will focus on Indium’s current back end products (tabbing ribbon, bus ribbon, metallization paste (or as I prefer to call it – “grid ink”), flux and flux cored wire). With a product development background, this also means I have an opportunity to work with customers, partners, and R&D to develop and bring new products to market that will advance the module assembly industry – very exciting for me personally.

 

Ultimately, I think of my role as both building awareness of Indium’s products and superior technical support available to our customers as well as helping to shape our growing industry.

 

Jim: Okay Jon, you’ve had a while to settle in and get familiar with our Solar Team’s past and present – what are you planning for the future of module assembly?

 

Jon: Regarding the future of module assembly it’s a bit early to know for sure but I am excited about our low-temperature bismuth-containing alloys. These low temperature, lead-free, bismuth-containing alloys reduce the soldering process temperatures, thus reducing thermal stresses. I’m also working with the Indium production team to further reduce our tabbing and bus ribbon yield strength. A lower yield strength will reduce mechanical stress on cells during the assembly process. This is crucial to minimizing the possibility of microcracks and cell breakage during the solar module assembly process.

 

In closing, having lived in California for the last 10 years, I am not 100% familiar with our Upstate New York climate, and especially not all the snow shoveling. I see in my future a solar powered driveway heater!

 

Jon can be reached at jmajor@indium.com

I was reading a blog post (click here to read it) authored by the owner of Taylor Guitars, and I started relating it to how I feel about solder. For those of you that don’t know, Taylor guitars are beautifully crafted instruments, not the kind of “dime-a-dozen” toys that you find at garage sales or music sections of department stores – they are the real-deal. Last year I happened upon a tour

of the Taylor Guitar facility in El Cajon, CA after a trade show and I was blown away by how much care goes into each of the guitars that are produced there. Taylor’s core customers realize how special the product is, and they will settle for nothing less.

 

So, how the heck does this relate to solder? As a tech guy I get calls from people who want Indium Corporation material - they don’t know which product they need yet, but they want to use our products if at all possible. It might be because they feel good about the quality, packaging, technical support, supporting documentation, or just because they feel like they have a connection with us. To me, that’s awesome! I admit - I am the same way with some things I purchase. Feel free to give us a call, even if it’s just to chat!

All the best,
~Jim

The following is an example of how a simple procedure like cleaning a soldering iron tip can make a world of difference in the quality of a solder joint. Eric Bastow responded to a customer after doing some testing in the lab – and confirming that a clean iron tip contributes to a clean solder joint:

 

“As I mentioned in our conversation, I did not think that a flux coated preform would fare any worse than a cored wire in a hand soldering application where charring is concerned. Rosin is rosin is rosin, regardless of whether it is within a cored wire or coating a solder preform. I did a quick experiment to see what would happen.

 

Using a Weller WS80 soldering station, set to an abusively high temperature of 850F/455C, I soldered some .250” square x .005” thick Sn63 preforms (folded-up as small as I could do by hand), flux coated with 1% NC9, to a nickel metallized FR4 test coupon. The contact time of the iron to the solder was ~5 seconds. The results look pretty good. The charred flux that you do see is flux that burnt to the iron and was transferred to the solder from the previous preform. I would anticipate this sort of appearance with a flux cored wire, as well, used under these conditions. I believe that with frequent cleaning of the tip, the amount of unsightly flux residue with be minimal, especially if a more appropriate iron temperature were used.” -Eric

 

The bottom image is what happens when you don't clean a soldering iron tip.

Soldering Basics

I’m really excited about a new option for those of us who are prototyping solar assemblies or evaluating new tabbing ribbon materials. I’ve been waiting for something like this – everything you need to solder solar cells together in one package. The turn around time is key too – you may recall an older post where I learned how quickly these materials shipped.

 

On the website where these kits are offered, the description reads:

“Tabbing ribbon kits come with everything you need to evaluate how Indium Corporation materials will work with your solar cells and assembly process. The kits can be used to:
- Evaluate which tabbing ribbon size is best for your design
- Determine which flux is best for your operation
- Experiment with new solder coating alloys
- Assemble a few solar panels”

 

The tabbing ribbon kits come in 3 flavors:

- Standard Sn/Pb/Ag (62Sn/36Pb/2Ag)

- Pb-Free (96Sn/4Ag)

- Low Temp Pb-Free (58Bi/42Sn)

 

I have a feeling the Low Temp Pb-Free kits are really going to be the most popular of the 3 that are offered though. Application temperature ranges will determine which kit to use, but all three versions of the kits are said to offer similar base copper sizes and tolerances:
“The ribbon itself is industry standard CDA 110 (99.9% Cu) core flat wire, coated with a precisely controlled layer of solder. Each ribbon is manufactured using our proprietary softening process so you can increase the yield of your stringing process.” Basically, this means that the softer tabbing ribbon will help eliminate the breakage of thinned cells during the heating/cooling cycle.

It also includes some matching bus ribbon to complete your panel build. If you’re trying to find the right flux, this kit serves dually as a flux evaluation kit as well. The kit is loaded with VOC-Free flux, rosin-based flux, and resin-based tabbing fluxes. I prefer GS-5454 as a flux for most tabbing operations, but you can see how the others stack up as well.

 

Let me know how you like the kit after you try it out!

~Jim

(jhisert@indium.com)

I caught up with Alan Rae after a recent IWLPC committee meeting, where he jokingly asked me to, “Stop asking important questions” - LOL! He was kind enough to give me a few moments of his time to share his wit and wisdom, and answer some technology questions that, yes, I thought were kind of important…

 

[Andy Mackie] You’re increasingly being seen as “Dr Nano” by the electronics industry – how did you arrive as the focus of so much of this technology?

 

[Alan Rae] At the start of my career I was in the structural ceramics business. In the days of “ceramic fever” in the 1980’s the mantra was sub-micron and monosize (monodisperse) for lower temperature processing and better properties. It worked. Then at TAM Ceramics we made “sub-micron” barium titanate and other ceramic materials but we didn’t call it nano then. When I was at Cookson Electronics in the early 2000’s we started to see nanotechnology emerging from the woodwork with people saying the same about nanomaterials for the electronics industry. Then I joined NanoDynamics in 2004 and realized the scope and potential, ranging from semiconductors to touch screens to printable electronics, to LED lighting, to solar power, to materials such as nano solders, dielectrics, conductors…the list is growing but the leitmotiv is the same – small, monosize, tightly-controlled. 

 

[Andy Mackie] OK, so Nanotechnology has been a buzzword for quite a while – is there a clear definition yet, and what current uses are there for nanotechnologies that may not be immediately obvious?

 

[Alan Rae] Well, the definition has been really tough to derive – ISO TC 229 “Nanotechnologies” came up with a definition that one dimension of a particle, needle or plate should be less than 100nm but it’s really tough to define…should all particles be less than 100 nm? 50%? Any? And should it be exactly 100nm? There are a lot of opinions. The Woodrow Wilson Institute lists over 800 consumer products containing nanomaterials on the market now – industrially the products range from semiconductors, to fillers in packaging materials and underfills, to antimicrobial and self-cleaning coatings for phones. Solar panels, especially thin film ones, depend on nanomaterials in their manufacture.

 

[Andy Mackie] What is in the pipeline for nanotech electronics and semiconductor interconnect materials? I know that nanosolders are starting to gain ground in some areas – what else is upcoming?

 

[Alan Rae] Much of the work in nano metals is being done by universities and small companies – for example my small company is working with Purdue and the Air Force to develop a novel solder technology – but commercialization will come by partnering with established companies like Indium Corporation, who have the distribution and technical support so that customers will be comfortable with a new material. Cost and reliability are king. Indium is already in the reactive nano foil business; there are existing and near-term applications for silver, silver-coated copper, alumina coated boron nitride and their combinations in adhesives, shielding materials and thermal interface materials.

 

[Andy Mackie] Several years ago, quantum dots were being promulgated for tunable band-gap detectors and quantum computers. How close are quantum dots to seeing real uses, and what else is on the horizon?

 

[Alan Rae] Quantum dots are unique and have great potential in medical imaging and as frequency shifters for LEDs. The markets haven’t developed yet because of the cost and because some of the best dots are cadmium (toxic metal) based. I’m working with a group at University of Buffalo which has a silicon quantum dot process that looks like a promising alternative. Quantum dots will have their time…but not just yet. In terms of new developments – they range from core shell and modulated structures for thermoelectric to replacing indium tin oxide with carbon nanotubes or graphene. The US National Nanotechnology Initiative tracked $1.6 billion in Government spending (check out www.nano.gov) in the last year at Universities and small businesses and NSF has set up centers of excellence at Cornell and other great universities that are really working hard to translate science into technology so we can make practical products.

=======

Alan, many thanks for your time, and for sharing your insights with us.

Cheers!  Andy

Soldering through-hole connectors can be a tedious task.  Connector Specifier recently highlighted an article by principal engineer, Paul Socha discussing how connected preforms can be used to streamline the soldering process.

Many through-hole connectors can be hand soldered successfully using solid or flux cored wire.  Others are more difficult for reasons including long pins, thick boards, or difficult-to-reach connections.  Connected (integrated) preforms relieve these issues by supplying custom preforms to match the application.  

To read the article and to learn more about connected preforms and how to design them for your needs, visit Connector Specifier. 

The junction temperature in an LED (the p-n junction temperature) is most critical to consider for LED cooling. If this temperature rises above the prescribed level recommended by the LED manufacturer, the lifetime of the LED as well as its intensity and color may be affected.   

As with most electronic systems, the LED assembly location where the highest temperatures are reached is the junction temperature. Many thermal management materials may be used to control this temperature, such as heat pipes or metal core boards, but each of these carry their own thermal resistance. An optimal cooling design is one which includes the lowest sum of thermal resistances for the system.

Ideally, no one thermal management material will be a bottle neck for thermal dissipation, however the materials closest to the heat source are most critical. High performance thermal management materials should be considered here. If the highest resistance measured is at the interface junction, the junction temperature will be raised more than if the bottleneck in resistance were at any other location. 

There are various types of LED assemblies, but a typical high power LED is depicted here. In this type of assembly, implementation of high performance thermal management materials would be most critical in the die attach material, heat sink slug, and solder as these are closest to the heat source and will have the greatest impact on dissipating the heat away from the p-n junction.

This year we tried to plan something a little different for APEX.  Instead of the normal booth, we used the space as a meeting place for people to come and talk with other engineers (from Indium and other companies), charge their cell phone, and eat a healthy snack.  If you have been to any tradeshow in your life you'll understand – this was an oasis.

 

Many people that did not participate in APEX are asking what it was like, especially in light of the predicted drop in attendance.  We spoke with a few of the Indium members who made it out to Vegas this year to sum up APEX 2009:

 

Rick Short told us "…attendance was 25 to 30% lower than in 2008.  That said, the quality of the attendee was unusually high (KEY decision makers) and the number of really good leads that we captured was high.  We spent about 25% of what we spent in 2008 on the exhibit and did much better (leads)."

 

Dave Sbiroli mentioned "It's the same core group of industry experts that attend the show" in reference to the technical presentations and industry meetings.

 

Brandon Judd commented "Although we are in the middle of an economic downturn, there was definitely no lack of interest in Indium's solder products at this year's APEX EXPO in Las Vegas.  In fact, it was quite the contrary.  Several customers, both current and potential, approached our booth with new and exciting applications that show there just may be a light at the end of the tunnel for our industry."

 

Tim Jensen had this to say, "This year's APEX was probably the best in recent history.  While the attendance was down from last year, those who did attend came with a specific purpose: to educate themselves and solve their current issues.  At Indium Corporation, we were busy educating customers on the implications of going halogen-free and helping to address their current Pb-Free production challenges."

Indium公司的焊接材料事业部门响应业界环保的大趋势，又推出了一款全新的无卤素焊锡膏Indium 8.9HF。这款solder paste的助焊剂和助焊剂残留均满足无卤要求，有卓越的印刷转移率和停滞后响应速度，无枕头现象，也不会不发生坍塌。我们为大家录制的无卤素相关小短片终于快"上影"了，争取下周吧。

How hot are you setting your solder iron for hand soldering using solder wire or preforms? If you are cranking up the solder iron temperature because you have transitioned to lead-free solders, think again.

For both Sn63 and SAC solders, the suggested hand soldering temperature is 315°C. Using this temperature, the solder iron tip temperature is significantly hotter than the liquidus temperature of either alloy, although there is a 34° C differential or more between the liquidus temperature of these two alloys.

Hand soldering relies on the thermal conduction of heat from the solder iron tip to a solder alloy, relying on Fourier's law for thermal transfer. The hot temperature of the solder iron tip will quickly rise the solder temperature to its melting temperature at this setting. If the solder iron tip temperature is set higher you can quickly lose control of the solder quality.

One of the biggest issues associated with high temperature hand soldering has more to do with the flux than the solder alloy. Most solder fluxes, regardless of form (liquid, tacky, or flux core) are designed to withstand temperatures up to 350°C. Above these temperatures, they begin to decompose and blacken.

Solder alloy oxidation is also an issue associated with high temperature hand soldering. As a solder is exposed to high temperatures, the rate it oxidizes increases. Fluxes aid to remove surface oxides, but at high soldering temperatures, fluxes are quickly exhausted.

For optimal solder results, keep the solder iron tip temperature low.