Thermal Interface Material

Here is a question that was posted and answered on our website back in 2006, I think it is still quite relevant:

Question: “Why does your Application Note for cleaning of indium ribbon for thermal interface recommend a mild (5-10%) HCl acid solution, yet [the] MSDS for Indalloy #4 (100%) says to avoid contact with acid? My past indirect experience with indium usage indicated some cleaning procedure of the oxides was necessary to achieve good thermal contact resistance.”

Answer: “Thanks for contacting the Indium Corporation with your request. If the indium ribbon is stored and handled (stored unopened in an argon or nitrogen pack – placed in a dry box) properly and it solders well in your process, this procedure should not be necessary. When following this procedure, the HCl solution should be applied to the indium metal to clean it thoroughly, and then dried with nitrogen.”

If you want to know more about metal thermal interface materials (TIMs) (handling, preparation, or process parameters), send an email to our global technical team at: askus@indium.com. They are ready to answer your question!

~Jim

最近又有些客户在询问我们公司的铟indium，用作散热材料(TIM--thermal interface material)。其中一个客户是做工业用的激光器。这个客户希望在他的瓷片间隔的两端用一种高效能的散热材料。

纯铟是一种散热效能极高的金属材料，热传导率能到达86W/cm.⁰C. 而且铟是一种软金属，能够“型变”。如果接触面两端有一定的压力，能够很好的把铟夹在中间，那么散热效能更好。

Indium 公司还有一种以铟或是铟锡为材料做成的TIM,叫做HeatSpring^R. HeatSpring^R 的特别之处是我们做了一定的表面加工处理，使其能够和两个接触面更好的全接触，达到全面散热的功效，而不是因为有些地方有接触，有些地方没有接触，导致局部过热。如果切开看HeatSpring^R 的横截面，你会发现它的横截面不是平的，而是有点像高低起伏的锯齿形状。

下面这两张图能够更好的说明HeatSpring^R 随着时间的增加，在热循环(thermal cycle)测试中热传导效能保持得很好。两外一张说明HeatSpring^R在一定的压力下，热传导性能大大好于别的一些thermal grease, thermal pad等硅胶材料。

目前，HeatSpring^R 被广泛地应用在IGBT,RF/PA（Power Amplifier功率放大器），TIM1,TIM2, 高功率高亮度LED，各种激光器的散热等方面。

Cheers!

Pic: Indium Corporaiton   

A new patent has been published for a liquid metal gallium plus carbon nanotube thermal interface that may capture considerably more of the thermal conductivity benefit claimed by researchers of carbon nanotubes (CNTs) than has been possible outside of a laboratory setting previously.  

Admittedly, I am embarrassed not to have come up with this thermal management concept myself! I was so close, and yet so far away. Previously, documented back to 2008, I described how conductive metals are in their liquid state. Those atoms get moving and shaking, and the heat passes right through! 

I also balked at those touting their CNTs…. The technology wasn’t there! Carbon Nanotubes cannot be affordably grown on substrates to make a commercially-affordable thermal interface material, and if you grow them, cut them down, and try to re-apply them, they are no longer oriented to directly connect substrate layers, and the resultant interfacial resistance between tubes adds up fast. 

Well, this patent reveals that Foxconn put 2 and 2 together to make what I’m gambling to be an outright GREAT Thermal Interface Material!!! This patent calls for carbon nanotubes suspended in liquid metal. That liquid metal fills in all the tube-to-tube gaps, and as fast as the heat comes in, it moves on out!

So, for those of you with carbon nanotubes, Indium has the liquid metal, numerous types in fact, to suspend them and make a great thermal interface material.

I love learning new technology, just wish that I had the clarity to have pursued something so obvious myself!

Have fun testing!

Amanda

A fisherman and tech guy at heart.
Ross Berntson
VP Sales Marketing and Tech Support

Here is a story of a PC, a thermal management problem, an advanced metal thermal interface material, a family that was about to mutiny, and a glazed donut. Spoiler alert: This story has a very happy ending.

Background: Our kitchen computer is an HP Slim Line with an AMD Athlon 32 bit processor.  The entire family uses it – and it is now fully cluttered with downloads, games, school programs – you name it.  The tray is filled with programs from who knows where.  In other words, it is the typical family computer – cluttered, SLOW, and NOISY.

Scene 1: My family began complaining about the computer’s resultant speed.  Being a tecchie, I immediately activated the CPU monitor, learning that it often was not running at full speed. The family also complained that simply booting the computer up was taking forever.

The complaints grew more dramatic with every passing day.

Scene 2: My personal complaint was that the fan was excessively noisy.  During dinner and breakfast, with no one working on the computer, the fan would cycle on and off at FULL SPEED. WRRRRRRR (fan noise)  – pause – WRRRRRR – pause –  WRRRRRR.  Aaargh!

Scene 3 (things get intriguing): Initially, I thought the fan was bad.  However, my tech support mind got going and I hypothesized that what we had on our hands was a thermal management challenge. I decided to replace the Thermal Interface Material (TIM) with Indium’s high-end metal Heat-Spring® Thermal Pad.   Mindy Macisco, Product Support Specialist for TIMs, had some of our advanced Heat-Springs® on her desk and gave me one to try.

Scene 4 (taking action):
REMOVING THE POLYMER BASED TIM
With no difficulty, I pulled off the case, unscrewed the heat sink, and observed the grease-type TIM on the backside of the lidded package.  The heat sink was an integrated heat-pipe and fan assembly with spring loaded 4-point screw fasteners.  I grabbed my putty knife from my shop and set to work on removing the grease, thinking it would be a sticky mess.  Nope.  It had dried into a flaky crust (image - left). It scraped off cleanly, with almost NO greasiness.  I was reminded of glaze falling off an old dried-up donut (image - right).   I used a little WD-40 to do the final cleaning.

INSTALLING THE HEAT-SPRING®
Installing the Heat-Spring® thermal pad was easy. I simply placed the TIM in the center of the CPU lid and began reassembling with a random tightening of the screws (tightening each a little bit before seating them completely).  As my friend Guido says, ‘Easy peasy’.

Scene 5 (resolution):
RESULTS
For the family, the computer is instantly faster!  For me, no more WRRRRRRRRRR.  The Heat-Spring® metal thermal interface material solved BOTH problems!!!

Fade to black as I head out the door with my fly rod!

Power amplifiers and transistors come in many shapes and sizes. The performance requirements vary as well. Attaching them can be a critical aspect of your design.

Both Pb and Pb-free alloys can be manufactured as a solder preform with a flux coating.(Learn more)  Selecting the right alloy and flux coating can be crucial to meeting your void criteria.  

A high-tech SOLDERING solution might include NanoFoil®, which effects a solder joint while minimizing heat exposure to your components.

There are also thermal interface materials such as the HEAT-SPRING® which utilize the unique properties of indium to create a superior thermal connection, similar to a solder joint.

There are many different attachment methods available, contact me with your design parameters and we can find your solution.  

Sampling, receiving, and testing indium Heat-Spring® compressible thermal interface materials are easier than ever! Not only are standard samples (solder research bundle kits) available for testing on the indium E-Commerce thermal interface material website, but now a Heat-Spring® video has been released depicting exactly what you can expect – what they look like, how they are packaged, how they are handled, and how you can get them. 

 

So watch, learn, and all-the-while enjoy the jiggy music that this new video has to offer!

Then, if you still have questions, before or after you receive your samples, give me a shout!

Note: These compressible thermal interface material samples are offered in limited varieties meant to suit the majority, however custom-engineered thermal interface materials are also available for your outside-the-box needs. 

最近有一个客户，在咨询我们公司的散热材料，用以更好地解决他们产品中IR Detector （红外探测器）的散热问题。

根据百度的介绍“红外探测器(Infrared Detector)是将入射的红外辐射信号转变成电信号输出的器件。红外辐射是波长介于可见光与微波之间的电磁波，人眼察觉不到。要察觉这种辐射的存在并测量其强弱，必须把它转变成可以察觉和测量的其他物理量。一般说来，红外辐射照射物体所引起的任何效应，只要效果可以测量而且足够灵敏，均可用来度量红外辐射的强弱。现代红外探测器所利用的主要是红外热效应和光电效应。这些效应的输出大都是电量，或者可用适当的方法转变成电量。”  

就是因为有大量的电量，就会产生热，就会有散热问题(Thermal Issue)。 目前，客户的IR Detector下面用的是TEC半导体致冷器, IR detector和TEC之间用的是环氧树脂 epoxy. 但是因为epoxy的导热效能一般只有2w/mk, 容易老化(bake out)，各个接触面也很有可能不均匀(pump out), 而且使用起来比较麻烦messy, 所以现在有更多的朋友们在寻求更好的解决办法。

Indium公司提供的TIM（thermal interface materials）都是基于金属材料。 很多金属材料本身就比化学材料有更好的导热性thermal conductivity。 Indium公司专利的可压缩性TIM---HeatSpring （compressible TIM），导热效能高86w/mk, 不会老化，接触面均匀，使用方便。“There are lots of HEAT in the world this year; It is the ‘HOTTEST’year for TIM!”。在这许多电子产品微型化，多性能，高功率，对散热的要求越来越高的“大热年”里，我们十分乐意和你一起分享更多关于Indium公司TIM材料方面的信息，为你度身订造出更好的解决方案！欢迎随时联系我们 askus@indium.com !

Cheers!

Pic: Google Image

昨天先生终于带回来了刚刚上市的Kinect! 我们也一起感受了这个新技术产品带来的游戏娱乐。

以前的Wii或是别的电脑/电视游戏，游玩者都拿着或是触摸一些固定的设备---感应器，遥控器，键盘，或是鼠标等。Kinect的发明，能遥控感应人体各个部位动作发出的信号，不需要人体在“附加”其他硬件；这让游玩者更能全身心地享受游戏的乐趣。

出于好奇（我不想那么快就拆了家里新的Kinect）, 我上网查了一下Kinect的组成，特别是电路板的构造。乍看之，其实也不是特别复杂的板子或是特别密或是小的难组装的元器件。Kinect是用小风扇和heat sink来处理散热问题的，其实也可以考虑我们Indium公司提供的一系列散热材料(TIM---Thermal Interface Materials) J

在玩Kinect的过程中(这里指英文版本的)，如果你想换代表自己的小人图像，可以选择“Change Avatar”(中文就是改变人物图像的意思)。大家都知道Avatar阿凡达是一部著名的电影。这让我想起了电影中各种的高科技，特别是人可以在“空中”随时调出一台电脑的界面，并且电脑界面根据人手指的“非触摸”动作，能够执行指令！ 哈哈，不知道那一天有多远。

还是那句我很喜欢的老话“科技以人为本”！

Cheers!

Pic:
1. http://www.simplemobilereview.com/new-xbox-360-4gb-ships-aug-3-and-kinect-and-connect-bundle-for-holiday-season/
2. http://www.gamesradar.com/xbox360/kinect-sports/news/naked-kinect-pics-are-sexy-geek-porn/a-2010080611184826095/g-2010061320105946075
3. Youtube video

PS: 先生最近在研究的项目之一，就是把Kinect这种人体动作“非触摸指控”的技术，应用到电脑中来。热切期待中！

I have previously discussed various reasons why thermal considerations in a device cannot be an afterthought. There are various methods for handling the thermal needs of a device before it becomes a problem. One of my well-known colleagues, Ross Wilcoxon, Principal Mechanical Engineer at Rockwell Collins, knows a great deal about these. His article, “a spreadsheet based matrix solution for a thermal resistance network: part 1” was highlighted in Electronics Cooling Fall 2010, and in it he discusses a method using Excel to do thermal resistance modeling. 

My inquisitive nature couldn’t let the article stand on its own. I had to tack on a few more questions. Ross was accommodating enough to help me out.  

[Amanda Hartnett] Why is it important to characterize the thermal resistance of each material used in a device?  
 

[Ross Wilcoxon] It may not be - sometimes the best lesson learned from a resistance network analysis (or any modeling effort for that matter) is determining which things are really important to the final results (component temperatures, reliabilty, etc.) and which things aren't.  For example, if the aluminum chassis in a system plays a critical part in the overall thermal resistance and has a large temperature gradient, then it is pretty important to know what alloy it is so that you can better estimate its thermal conductivity.  On the other hand, if the chassis is pretty much uniform in temperature, then knowing exactly what its thermal conductivity is probably doesn't matter so much.
 

[Amanda Hartnett] What information is needed from the material vendors in order to complete a resistance network analysis?
 

[Ross Wilcoxon] Obviously, thermal conductivity is a good start and if you are doing a transient analysis (I plan to talk about that in part 3 of the series that I would like to do for Electronics Cooling), information on specific heat and density are pretty important.  For interface materials, the overall interface resistance is needed more than the thermal conductivity.  In many cases, it would be really nice to have data not only for nominal values but also some indication of uncertainty.  The resistances in a thermal network can be calculated using best or worst case numbers as easily as they can with nominal material properties.  It is pretty easy to switch between these values within the spreadsheet and it is a good way to get a feel for how important knowing the precise value really is by looking at how varying between best and worst values impact the overall temperatures.  Also, I have done a few spreadsheet based Monte Carlo simulations for getting my hands around the cumulative effects of uncertainty in things like thermal gap fillers and a thermal test stand.  For that type of analysis, you have to have some understanding of the uncertainty as well as the nominal values.
 

[Amanda Hartnett] Could a model like this be used to characterize the effect of degradation in a single layer?
 

[Ross Wilcoxon] I guess I'm not sure exactly what you mean on this.  If the effect of the single layer (I suppose you mean a thermal interface material) is accounted for in the thermal resistance calculation, sure - you can just apply a factor in the equation to account for something like voiding to say that the effective thermal conductivity of the interface material decreases by X% to assess how much that impacts the overall effect.  I suppose it just comes down to how complicated you get in converting material and geometry parameters into thermal resistance.
 

[Amanda Hartnett] In a typical cooling solution, have you found that one boundary was more critical than another?
 

[Ross Wilcoxon] In a lot of cases, the thermal battle is lost in the first mm of the thermal path (the interface between a component and whatever it is attached to - I bet you like that answer, huh?!) but in a lot of our systems the choke point is in the last mm (moving the heat from the system to the surroundings).  One of the big benefits of network resistance analysis is the fact that you can very easily adjust the resistances, including these boundary conditions, by just changing a couple cells in the spreadsheet. This can give a good feel for which parameters are the most critical and what needs to be better understood.  For example, in the next article for Electronics Cooling (assuming that I get it written), I plan to talk a bit about an analysis that I did for some of our equipment going into a missile pod along with equipment from a number of other suppliers.  At the time of the analysis, we didn't know certain details about things like the surface finish to which we were attaching our module, the specific alloys in the missile pod, etc.  Having a quick-look analysis tool helped us determine which unknowns were really critical for the thermal analysis and we could concentrate in chasing down that information.
 

-----------------------------------
 

Ross – Thank you for your time and for sharing your knowledge and experience!  

I’ve received numerous questions about using gallium liquid metal alloys, so thought I’d present some of my answers for all.  The customer questions are in black, and my responses in red.     

1. Indium’s product data sheet, "Indalloy Metals Liquid at Room Temperature" mentions that "any liquid metal will wet another clean metal surface". Can you please elaborate on the conditions that make such wetting possible? 

As far as wetting, gallium alloys (Indalloy 46L, Indalloy 51E, Indalloy 60, etc.), coat nearly any organic, ceramic, or metal surface. It is difficult to come up with materials used in packaging and processing these alloys that come clean of the alloy after use.   The physics of this affinity is unknown, however the low melting point and surface tension are the source/consequence.

Many metals will form some alloy with the gallium, but the solubility in gallium is limited. The gallium wets the surface and forms a solid gallium-alloy layer, which then acts as a diffusion barrier. In the case of aluminum, gallium forms an amalgam which ends up consuming a large volume of aluminum before a stable solid layer.

2. Do you assume an oxygen atmosphere (gallium oxide does wet most surfaces)? Or, to the opposite, do you refer to the wettability of plasma-clean metal surfaces?

3. Can you let me know if Indium Corporation sells droplet dispensing equipment for liquid solders/metals?

Liquid metals are typically offered in a syringe and various needle gauges can be screwed to the tip to adjust the dispensed droplet size. For dispensing thin layers of liquid metal, such as for a thermal interface, we recommend PVA selective coating equipment.

4.  We are interfacing our thermoelectrics with both steel and aluminum and the hottest point will be around 600°C. Can liquid metals be used for this?

InGa alloys are selected typically because they remain liquid at all times, negating any contact resistance between substrates.  The typical application for these has temperatures up to approximately 100°C or slightly higher.  At these temperatures we have noted some aluminum corrosion by the gallium, which will only become worsened by your elevated temperature. 

There are other alloys which do not contain gallium and have only a slightly higher temperature, such as the Bi/In alloys. At 70°C, the eutectic composition of this alloy will also be liquid in phase, however is much less reactive with your bonding metals, and therefore may be better suited.  

最近在一些客戶拜訪中，許多客戶對我們Indium公司各種形態的銦金屬都頗感興趣。以前，我也只是知道銦在導熱界面材料中(TIM: Thermal Interface Materials)中所起到的重要作用；但是和各種不同application的客戶們交流，也讓我自己更進一步的學習和了解到了銦的其他廣泛用途：

²       indium 低的蒸汽壓常數能使它應用在高真空的環境中

²       indium 自己就能夠冷焊（cold weld）在一起，bonding兩個要組裝的部件

²       indium 加入合金中，能很有效地減低焊接合金的熔點溫度

²       少量的indium也能大大增強焊接材料的抗疲勞表現（thermal fatigue）

²       indium 可以與玻璃，石英等一些陶瓷材料bond在一起

²       indium 有很高的熱膨脹系數(high CTE: Coefficient of Thermal Expansion), 是兩個有很大CTE差別的連接面，都能很好的bond在一起。

Indium公司提供3N (99.9%), 4N(99.99%), 5N(99.999%)或是更高純度的銦金屬。 歡迎聯係  metchem@indium.com.

Pic: Indium Corporation.

最近小忙，少讀書了，也少和大家分享了；不過工作之餘，翻看了一下《A Seat at The Table》一書，覺得裏面有些道理也蠻有啓發的。比如説此書中一直圍繞這個主題來展開了論述“Today, the only thing your customer cares about is value.”

就這個觀點，再對照一下Indium公司的兩個主要系列產品：

²       電路板組裝焊接材料(Solder Materials):  這裡也要分產品而論。對於技術含量較高，工藝使用要求較多的焊錫膏(Solder Paste)材料，重視成品可靠性的客戶們會更多的關注產品帶來的“價值”。 如果只圖便宜的材料，但是用起來“錯漏百出”的，最後還是事倍功半：返工，復修，廢棄率高（特別是浪費貴的不能翻修的板子），產出率低，總體成本也自然高了。 對技術含量較低，工藝已經“模式化”的產品，像錫棒(Solder Bar)，錫綫(Solder Wire),  性价比會更關鍵……在目前日益高漲的金屬原材料市場中，Indium公司考慮到客戶們的成本壓力，也推出了性能可以和SAC305錫棒媲美的有成本優勢的Sn995錫棒。

²       半導體封裝材料(Semiconductor Materials):  整個半導體行業應該算是一個高成本，高投資，高回報（運營得好的話）的三高行業。半導體封裝材料也像是其中的經絡血脈吧，連接各個部分，讓整體最後順暢無阻的工作。半導體各個部分的材料都不便宜，設備更是不菲；對材料性能的表現要求和驗證都很嚴格，畢竟都投資那麽多，不能“功虧一簣”嘛。所以客戶們一般會十分重視產品的價值。 Indium 公司目前提供的半導體材料有：Wafer Flux, Wafer Paste, Micro Spheres, Flip-Chip Flux, Substrate Paste, Ball Attach Flux, Die-Attach Paste/Wire, PoP Fluxes, etc. 

Indium公司還為大家提供散熱界面材料(Thermal Interface Materials)，工程焊料(Engineering Solders)，薄膜光付太陽能板製造材料&太陽能板組裝焊接材料(PV Solar Materials)，和銦金屬及其化合物等。 這些材料使用在比較領先的應用中，新興行業，或是細分市場中，客戶們都十分重視產品和服務能給自己帶來的價值。

Cheers!  

Pic: Indium Corporation

PS: 前些日子看了中央4台的《第三屆漢語橋在華留學生漢語比賽》，感慨不已！除了感嘆這些留學生們對“那麽難”的漢語的精湛掌握，對中國文化和歷史的了解，甚至對中國的熱愛；更感慨的是，這些活動也説明了祖國的強大！現在越來越多的留學生們來中國學習，想進一步了解中國，和中國人民交流；中國話也在慢慢傳播到全世界！以前中國學子們苦讀英語，考TOFEL, 雅思，GRE什麽的；現在金髮碧眼的學生們也在場上比拼誰更了解我們的“四書五經”了，哈哈！

剛剛看見一篇挺有意思的文章，標題是“全球LED三大陣營比較及廠商排名”，不禁讓我想起最近確實有更多的客戶問起關於LED的封裝和散熱材料了。

除了傳統用的焊接材料(soldering material)外，最近的好些客戶都問到關於散熱方面的材料，主要是針對高功率，高亮度(High Power High Brightness HP HB)的LED應用。傳統的硅膠(thermal grease)因爲其化學特性，導熱率比較低，而且容易在界面中移動，不能使接觸面都均勻導熱。最重要的是，隨著時間的流逝，硅膠的導熱性能會越來越差，所以現在越來越多的客戶在尋求更好的解決方案。

Indium公司的散熱界面材料（Thermal Interface Materials TIM）， 都是使用導熱係數比較高的金屬/合金，加上特殊的表面處理后，能更完整均勻地接觸導熱界面。而且即使隨著時間流逝，金屬的TIM的導熱性能也能保持穩定。

Indium公司還特意推出的網上的購買，為各種學校/機構/小量使用購買者提供方便。

Cheers!

Image: Indium Corporation.

Indium Corporation has won the Innova Award for Best Technology for its Heat-Spring^® metallic thermal interface material (TIM).

Heat-Spring is a clean, high-performance thermal solution for the increasing demands of high brightness LEDs. It is a compressible metal foil with proven performance in such demanding environments as electronics, aerospace, and power devices.

The compressible TIM provides low thermal resistance as a result of its high thermal conductivity (86W/m-K) and its ability to conform intimately to interface surfaces.

Unlike other thermal interface materials, such as thermal grease that bakes out, dries out, or pumps out during use, the thermal resistance of the Heat-Spring continues to improve with time and power cycling.

According to Jordan Ross, Market Manager for Thermal Materials, “Indium Corporation is honored to be recognized with the Innova Award for our patented Heat-Spring product. With its patented compressible interface design, Heat-Spring provides optimized surface contact, superior thermal conductivity, and enhanced heat flow.”

Sponsored by LED Journal, the Innova Awards feature leading companies within the LED market which have shown, through their products and services, the most innovative and advanced technology breakthroughs in LEDs. The award is designed to recognize companies each year for industry leadership, product development excellence, best new technology, and outstanding LED applications, which will eventually lead to the widespread adoption of LED technology in the marketplace.

Wandering through the references to indium metal on the internet, I sometimes see it referred to as, "that 'rare' metal."  But is it really so rare?  I recently talked to my colleague, Claire Miko, Director, Metals and Chemicals for Indium Corporation and asked if the reports of the rarity of the metal (like the death of Mark Twain) were greatly exaggerated.

Question:  The element indium is widely used today in many electronic (glass coating, low temperature solder, hermetic sealing and thermal interface material) and solar applications (CIG solar panels), but very little is known about it.  Can you tell us where indium metal comes from?

Claire:  Indium is a by-product of several base metals such as zinc, lead, copper, tin and other poly metallic ores. It is very abundant on the crust of the earth (much more than silver for example and the annual silver production is at least 40 times bigger than the annual indium production). Geographically indium is abundant in South America, Canada, Australia, China and the CIS, i.e. the reserves are widely spread.

 
Question:     Does indium have to be refined after it is mined?

Claire:    Indium is present in the base metal ores at ppm levels. It first needs to be separated from the base ore and concentrated. This is done at the base metal smelter (for example during the refining of zinc, lead, copper, tin etc). It is then further refined and purified at indium refineries.

Question:  Indium Tin Oxide (ITO) is the one of largest indium-containing products today.  How much of the indium mined goes to making ITO?

Claire:   About 50% of the indium refined is used for making ITO. A larger percentage is needed to start the ITO target productions but the sputtering process used (when putting the ITO layer onto the glass) is inefficient and generates a large quantity of indium which is reclaimed and is then recycled and put back into circulation.

Question:     Is there enough indium available to meet the current and future needs of the marketplace?

Claire:   The indium production has always expanded to meet growing demand. Indium production grew from 70MT (metric tonnes/year to over 500MT/year over the last 20 years. At the moment only one-third of the indium mined yearly is being refined in indium metal, another third accumulates in residues that are more expensive to treat but they remain available for future processing, and the last third is currently lost because it does not reach a base metal smelter which has the equipment to separate it from the base metal ore. Investments at these smelters would enable the extraction and refining of these quantities if the need arose.

Question:    Are there recycling programs in place to recover unused ITO from the targets used to deposit it onto the glass surfaces where it is used?  What is the rate of recovery?

Claire:   There is ample capacity to treat spent ITO targets (as per point 3) and the recovery process is now mature and very efficient. The cycle time of this process has also now become very short enabling a very quick return of the refined indium for new consumption.

Question:    Are there any viable alternatives to ITO?

Claire:   A far as we know ITO remains the best material for LCD and other flat panel displays applications. It offers the best performances in terms of optical transparency, electrical resistivity, uniformity of both transparency and resistivity, chemical and mechanical stability, resistance to corrosion, and, finally, uniformity of etching.

The cost of the ITO on 42” TV represents less than $2 and less than 1% of the display cost. It is a small cost to pay to ensure that the quality of the display is maintained. Alternative materials have shown significant process problems with resistivity, uniformity and chemical and mechanical stability.

Thermal News recently interviewed Amanda Hartnett regarding thermal management with metal TIM (thermal interface materials). You can read the full article here:

http://www.thermalnews.com/eprints/Indium_0310.html

I really like this interview, so I’m not going to give away the best parts – I want you to read it yourself. I do, however, want to provide a couple teasers to pique your interest. I’m leaving out the especially cool parts…

“Pure indium, used as a solder TIM, delivers a thermal resistance to…”

“Also, it is important to consider the reworkability of an interface material. TIMs such as … are very simple to rework. Others, such as conductive epoxies, can be quite difficult.”

“When I measure the performance of thermal interface materials, I characterize them based on ... This value is typically more valuable than bulk thermal conductivity. For a compressible TIM, the … assumes the actual contact which will be made between the interface material and it’s mating surfaces. This provides a measurement of thermal performance which is as close to real-world per Watt or per cm2 as I can provide without being application-specific.”

Are you still reading this blog? Go read the article!

~Jim