Tommy Acchione

nan·o·tech·nol·o·gy [nan-uh-tek-nol-uh-jee, ney-nuh-]
-noun
any technology on the scale of nanometers
(care of dictionary.com)

So it can be cliche to start with the definition straight from the dictionary, but the definition clearly points out the problem with the understanding of nanotechnology...there is very little.  Trying to define nanotechnology broadly is like trying to lump all items in a grocery store that are in a jar into the same aisle.  Just because pickles, peanut butter, and garlic all come in a jar doesn't mean you need to lump them in the "jar aisle". I'm not sure my stomach can handle that shopping experience. 

In a response to this kind of understanding, this week the International Organization for Standardization (ISO, you know like ISO 9000?) released a new technical report to help define and categorize nanotechnology. Instead of treating the technology as one big lump of the same material and "organizing by jars, or jarring it", it is acknowledging that all nano isn't created equal.   In the report, titled ISO/TR 11360:2010, Nanotechnologies – Methodology for the Classification and Categorization of Nanomaterials, it treats the constituents of nanotechnology as part of a family tree.  So your garlic may come in a jar all chopped up, but it is classified with the veggies and onions because it is more closely related.  In much the same way, carbon nanomaterials and gold nanoparticles are nano and "in a jar," but carbon nanomaterials are a separate class of material that can now be classified on a separate tree or "aisle."

So what do you think?  Is this a good way to classify nanotechnology?  Are you glad that ISO is getting involved in the conversation?

Get your free nanotech article!

So I was tempted to just abbreviate and write: Free Nano!  But I fear that it wouldn't have referred to a free nanotechnology article recently published in the Journal of Nature Nanotechnology.  If you are a young engineer, you remember what it was like to have all of the most current journals at your finger tips right there available to you through the school's library home page.  Now, as engineer professionals, magazines, journals, and publications are, for the large part, an expensive part of how we do our job. And, while our company will frequently pick up the tab, it's not clear that a publication is going to be informative and of value to what we are doing ... until it comes.

This is why when a nanotech magazine releases an very interesting article on how graphene sheets fabricated by a CVD and roll-to-roll process have some very promising electronic properties, I suggest reading it!

Graphene is the new entrant to the carbon/nanotech conversation.  With the new processing tools available, it might be able to use carbon in a unique "nano" way.  In this case they are depositing graphene using a chemical vapor deposition process, literally atoms at a time!  Give it a read and let me know what you think!

NanoFoil® is on wikipedia!

Link - en.wikipedia.org/wiki/NanoFoil

 No, we are not responsible for the post, but this is when you realize you've got something special.  Someone out there took the time to write information and do some research about the technology so that the next time you hear the word NanoFoil® and google it, you have a referenced definition.

Wikipedia is the new Encyclopedia Britannica for the internet generation.  Except now, instead of buying lettered tomes as they come out, or waiting for an updated reference to a topic like SAC305 solder material (or for those not solder inclined say Australian Koala Bears), we now have instant gratification.

Now I can't talk about the great things about wikipedia without talking about the concerns.  Being an open forum type encyclopedia, and with thousands of posts being updated daily, there is a lot of room for error.  Many of us young enough to have wikipedia available to us in College remember being told that we could, under no circumstances, use wikipedia as a reference. But now, with Wikipedia's stricter policies on articles, this may soon change, if it hasn't already.

What I can confirm is that this NanoFoil® post is 99% accurate!  The numbers are off by a few percentage points here or there but, for the most part, it is informative and useful.

So what do you think of wikipedia?  Has it made us smarter and able to process and learn more information, or has it made us reliant on "suspect" information?

I've been reading more and more articles about the use of new nanomaterials as a thermal interface material to replace either epoxy or standard soldering techniques.  As an engineer with a background in nanotechnology and, specifically, the use of carbon nanotubes and their properties and as fillers in other materials, I have some experience in what nanotubes are and how they are made into these interface type materials.

The most important thing to remember when dealing with Nanotubes is that their strength DOES NOT lie in numbers.  Most strength and thermal conductivity properties that are off the chart are usually just of one, when you start dealing with bulk carbon nanotubes, property calculations get a little complicated.

Imagine you have a bowl of pasta, and, in that bowl, you have a mixture of fettuccine, or thick and strong pasta,  and cappelini, or thin and stringy pasta.  Individually the fettucini is stronger than the cappelini, but when combined together on your plate you have a new material that has different properties altogether and has strength that is ultimately in the middle of the two pastas.  Now imagine each piece of pasta is less than 100 nanometers in diameter; separating out the nanotubes with the properties that you want can be difficult.  You'd have to get some really small tweezers and a good microscope. It would be just like you were 5 again except without the spaghetti sauce all over your shirt.

So, now how do we get the properties that we want in these materials? There are, essentially, three things we can do:
1. Separate out the nanotubes we want
2. Combine the Nanotubes with another material to get a composite
3. Use what we know about nanotubes to manipulate carbon to produce better material

Which is the best, cheapest way to get a good thermal interface material?  I'll mull it over while I'm trying to get spaghetti sauce off of my shirt.

After spending a couple of days at some Indium Corporation NanoFoil® customers, I am back in front of my computer working on customer trip reports. So, naturally, I am going to write a blog at the same time.  Being the "new guy" at Indium, I am in a unique position.  At RNT (the company whose assets Indium bought), I worked with a technology that essentially competed directly with solder attach technology, and yet I didn't know much about the stuff, solder that is.  That isn't to say I wasn't well informed, I simply was using a new nanotechnology to try to bond parts in ways that just wasn't done before.

So when i came to Indium, I was rather unindoctrinated when it comes to solder, solder paste, and the like.  So for those solder newbies out there, or even for those who know what they're doing, you and I have a lot of the same questions. So, I thought I'd take some time to show you where I'm getting my answers.

- Chris Nash, My tech service colleague wrote an article on Solder Basics,

- anything on EltroIQ

- The Indium web site has a Knowledge Base that you can sign up for and ask a question or see recent questions and answers

- A colleague of mine in Europe pointed me to an online summary of many microelectronic, assembly, and soldering processes

- Industry web sites such as SMTA, IPC/APEX and IMAPS

That's where I am doing my research. If you know of any other places where I should be looking please comment!

So, I figured while I'm at 30,000 feet in an airplane on free wi-fi (how long have we waited for this? Thank you AirTran®!), it would be a perfect time to make a few comments about bonding with NanoFoil® and the role that pressure plays in the NanoBond® process.  Get it? Pressurized cabin?  Bonding pressure?

If you remember the basics for a second, NanoFoil, whether it is standard or plated with tin solder on both sides, needs to be in intimate contact with the surfaces to be soldered.  Once the NanoFoil is activated (at a thickness of 40 microns) it only stays at 1,500 degrees Celsius for less than a millisecond.  So, if the NanoFoil is not in "intimate contact" with the interfaces that need to be soldered (or "wet"), it will not create a great bond.  By applying pressure, you, the engineer, can maximize contact with the foil. The best way to do that is to use constant pressure and some foam or compliant material.

Constant Pressure: If you were to personally witness the NanoBond process (imagine you are shrunk down to nano-size and can actually see the NanoFoil reaction begin), you would see a wave of molten solder propagating across the bond area as the reaction occurs.  Now, if you were using two static plates to press the assembly together, there would be minimal constant downward pressure while the solder is molten. However, if you were using a spring-loaded, air-driven, or piston-driven pressing device, you would ensure that downward pressure was pressing the assembly together, enabling the molten solder to produce a high quality, low void bond.

Foam (Compliant Material): If you remember nothing else about this flight-induced blog post remember this:

A COMPLIANT LAYER SPREADS THE LOAD EVENLY AND 
HELPS TO MAKE THE MOST SUCCESSFUL NANOBOND. 

It shouldn't be too much of a surprise to learn that, if you use some foam above your component as you are applying pressure, the load will be spread much more evenly.

Well that is all for now. Preparing for a landing. Not me, the pilot. All I have is this wi fi compatible laptop!

Image source.

In my last post, NanoFoil Basics: Activation Part I, I talked about NanoFoil(r) activation properties (remember, I'm not using the term " ignition" because it implies burning, NanoFoil activation is more of a localized flash of heat), and some various ways to ignite the NanoFoil.  To review a bit, the two easiest ways to ignite the NanoFoil are by thermal (a heat source) and electrical energy (a spark).  Mechanical will work, but it requires a very concentrated impact which is very difficult to use or reproduce.

Don't Play Laser Tag with NanoFoil
The last way to activate the NanoFoil is through the use of a laser.  Now this makes sense right?  A form of high energy, very localized can ignite the NanoFoil.  Where it gets tricky is that a laser can also be used to cut NanoFoil as well!  I won't go into the gory details here, but with tweaking of the pulse width and power, a laser can either cut through the NanoFoil to make intricate shapes OR it can ignite the NanoFoil.  There are great processing implications for being able to ignite foil with a laser.  In automation, for example, a laser could be built into a head fixture that simultaneously deposits the NanoFoil, appiles pressure and ignites.  Additionally, having a through hole on the backside of a board where the component sits can give a sightline for activation with a laser.

Activation Tools
The easiest and cheapest way to ignite foil is with a 9 volt battery.  By hooking up wires to the leads and touching both leads to the foil (essentially shorting the battery and generating heat) you can activate the NanoFoil.  In demonstrations we have also forgone the leads and simply touched the leads of the 9 Volt to the foil.

American Beauty - The most common small production level tool used by customers and here at Indium is the American Beauty resistance soldering tool.  With this tool one lead can be grounded to a press or the part, and a secondary probe can be used to complete the circuit by touching the NanoFoil. Simple, easy, reliable and fits onto a table top, perfect for small scale manufacturing needs.



MPIS (Multi Point Ignition System) - Primarily used for sputtering target bonding with NanoFoil.  For sputtering targets larger than 6 inches, the NanoFoil needs to be activated in multiple locations to reduce voiding.  This needs a full blog post to explain the in-depth details, but the basics are as follows: when the NanoFoil is activated under pressure between two layers of solder, at the wave front of the NanoFoil is molten solder.  If the NanoFoil is activated at one location for a large part, the wavefront of molten solder will spray out the opposite side of the activation causing voiding.  If instead the NanoFoil is activated at opposite points around the part, the wavefront of molten solder meets in the middle and causes minimal to no voiding. 

ESD Sensitivity
A lot of times we get asked: is the NanoFoil ESD sensitive? It is a logical question, with a reactive material that last thing you want is an operator shocking the NanoFoil and activating it.  We have had the NanoFoil sent through standard ESD question, and the company responded in true engineering fashion: "The operator would have to have enough electrostatic energy running through him to kill him 10 times over before the NanoFoil would go off"  And so the short answer is no, the NanoFoil is not susceptible to ESD!

I'm a nano guy, and for me the term "nano" can refer to my college degree, my interest in bug collecting, or my iPod.  For most consumers the word nanotechnology has been overused in marketing campaigns to attract interest, or, in most cases, is a term that is esoteric and unknown at best.  If I were to take a poll of random consumers, Family Feud style, and asked where to find nano (yes I am old enough to know what Family Feud is, it's that show with Louie Anderson right?), I suspect my answers might look like something like this:

1. IPod Nano 8GB
2. IPod Nano 16GB
3. Computers
4. Sunscreen
5. Mork (his catch phrase "Nanu Nanu", and no I'm not old enough to have lived through Mork and Mindy)

While the iPod nano is a microelectronics device that has thousands of small parts and numerous solder alloys and solder pastes, it is not a nano product.

So, just so we're clear, "nano", as I define it, is: a product that has at least one dimension that is on the order of 1 to 1,000 nanometers, OR was fabricated on the order of 1 to 1,000 nanometers. Our NanoFoil® thin film product IS "nano" because, though it can be held in your hands (it is 40 to 60 microns thick by 43.5" x 9"), it is created by depositing nano layers an atom at a time.

A pretty thorough list of nano products has been nicely compiled at the The Project for Emerging Nanotechnologies blog.  As a preview to microelectronics and nanotechnology, you can check out an interview a colleague of mine, Dr. Andy Mackie, conducted with a nano/microelectronics forerunner.

Over the next couple of months I am going to highlight nanotechnology products and why you the consumer, or you the microelectronics expert, should care.  Golf clubs, computers, hand-held electronic devices, drug delivery, and super soldier suits; there is no doubt that nanotech is the science of today, we just have to find it and translate it!

At the heart of it, NanoFoil^® is simply the aluminum and nickel chemical reaction just waiting to happen.  A lot of energy and a lot of heat strapped into thousands of alternating layers of atoms.  Each atomic layer of aluminum is waiting for just the right energy to move into the nickel layer and combine - to release up to 1250 Joules of energy per gram of material and as much as 1500ºC (2730ºF).

But, why don’t nickel and aluminum just react in real life? And more importantly, how do we make the NanoFoil react to release heat precisely where we want it? 

 

The former question is answered by going back to basic chemistry and a concept called activation energy.  Activation energy is defined as that energy that must be overcome in order for a chemical reaction to take place.  In regular use, when aluminum and nickel come into contact with one another they do not react, and this is a good thing. Imagine if your nickel-coated nickel reacted with your aluminum money clip in your pocket…hot!  The activation energy of the reaction is too high to promote this reaction naturally.  ‘

 There are a few ways to reduce this activation energy, the most common being via a catalyst, which is a substance that modifies the transition state which, in turn, lowers the activation energy of the reaction.   In the case of the NanoFoil, instead of a chemical modifier we have taken advantage of a physical modifier, surface area.  By layering the aluminum and nickel atoms very thinly and in a very precise method, we rely on the increase in surface area to decrease the activation energy necessary to start the reaction…in most demos we use only a 9 volt battery!   

 The second question is a frequent one fielded by Indium engineers, and worth a deeper look!

 How is the NanoFoil Activated/Ignitied?

The reason I will use the term "activation" over "ignition" is that ignition implies the beginning of a sustained burn, where the NanoFoil is a reaction that lasts for less than a millisecond, and only requires activation.

The reaction will start with 250ºC of localized heat, or a very localized form of energy.  The trick is getting a very concentrated form of energy to come into contact with the NanoFoil.  Touching the NanoFoil with the point of a resistance soldering iron that is at 250ºC is much more likely to activate the NanoFoil than throwing the NanoFoil on a hot plate that has been heated to 250ºC.  In general, there are three types of energy you can put into foil to activate it.

1. Mechanical Energy
2. Thermal Energy
3. Electrical Energy
   

Mechanical Energy – In the case of mechanical energy, dropping the NanoFoil on a concrete or hard surface could activate it IF it lands on its edge and all of the impact energy is concentrated on the corner.  Generally, the NanoFoil does not go off with contact, but friction between the NanoFoil and itself, in the form of a small shard, has produced enough energy to activate the NanoFoil.

Thermal Energy – In the case of thermal energy, as discussed above, a concentrated amount of 250C heat will activate the NanoFoil.  In the case of ohmic heating, which is what we do in demos, by shorting the leads of a battery, the current must be 100-120Amps for a 15um contact diameter, and 250-300 Amps for a 300µm contact diameter.  A hot filament or flame, such as a lighter, will also activate the NanoFoil.

Electrical Energy – In this case a spark will activate the NanoFoil, but it is about concentration of power, or power density.  With a momentary point contact from an electrical probe, 10 Amps and 5 Volts is sufficient as long as it is POINT contact.  The foil can be activated remotely through the use of a dedicated trace on a board, and this requires testing to determine the amount of energy that will travel the distance of the trace.

In my next blog post I will talk about Laser Ignition, ESD sensitivity, and some of the tools that Indium has developed to control the activation.

Having worked with NanoFoil® for over two years, I've tried just about every way possible to explain what it is, where it comes from, and why it is useful. My interchanges with engineers and non-engineer friends and colleagues used to go like this...

Tommy: NanoFoil...it's kind of like aluminum foil in thickness and look, but a little stiffer and when you put energy into it, like a spark, it heats to 1500 degrees Celsius (which is hotter than lava in a volcano) for less than a millisecond!

My engineering and non-engineering friends display puzzled looks, you know the ones you get when you start explaining that your favorite sport is water polo and it has nothing to do with horses...ok the look you have right now

Engineering Friend: Umm so what can I blow up with it?

Non-Engineering Friend: So wait, if it's that fast and that hot, I bet you could make really fast grilled cheese. Have you called Healthy Choice yet?

Good Grief!

  NanoFoil should, in no circumstances, be used with your sandwich products!


What is NanoFoil...if it's not for the food preparation market what does it have to do with indium and solder?

NanoFoil® is a thin film heat source. At the heart of it, that is the simplest definition.
 
Whether you've heard of the product and use it, you're new to the technology, or you are just interested in nanotechnology, this product is not only cool but useful!

Expanding on the definition: NanoFoil is a thin film layer made up of thousands of alternating nanolayers of aluminum and nickel. When localized energy, like a spark or intense heat (think soldering iron) is applied, a reaction (below) occurs between all the layers - and the foil (40-80microns in thickness - think human hair) heats up to 1,500°C for less than a milisecond.

Al + Ni -> AlNi  (You didn't know there'd be chemistry involved did you?)

So you see why it isn't great for melting grilled cheese now, right?  It would only singe the outer bread layer, at best.

There are many applications for NanoFoil, but it is most commonly used for joining two components together. That is, components that have solder pre-applied (pre-tinned). In this situation, the NanoFoil, as the heat source, remelts the solder and reflows the joint WITHOUT the heating the nearby components or substrates!

So, while I won't be calling Healthy Choice any time soon, there are many applications where NanoFoil is useful...LEDs and CPV bonding for thermal management, and sputtering target bonding for higher power just to name a few.

Stay tuned (subscribe via RSS or email - below) for more applications and for more about how NanoFoil is used to bond, and just more about nanotechnology.  If you think I got some weird looks from my friends about NanoFoil, imagine what they said when I told them about the nano...pants?

See www.rntfoil.com for more information.