Wednesday, July 16th, 2008
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Posted by Amanda M. Hartnett
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As previously posted, Indium’s Table of Specialty Alloys and Solders contains hundreds of solder alloys used as thermal interface materials and for each of them, we have listed melting temperatures. The method by which these were calculated is a repeatable one using a piece of equipment called a Differential Scanning Calorimeter.
In this method, a small sample of the solder alloy is input into the system and slowly heated until the solder alloy melts. Throughout the reading, a graph is created, from which the solidus and liquidus temperatures are interpreted.
The graph appears as a steady baseline, and at the melting point of the solder alloy, a peak is generated (See Image). At the point where the peak first deviates from the baseline, the solder alloy has begun to melt. This is the solidus point. At the point where the deviation returns to the baseline, the solder alloy is completely molten. This is the liquidus point. The entire deviation period is defined as a phase change period.
The tolerance of the scan is related to the scan rate. The slower the scan, the more accurate the reading. The tolerance on a typical reading is +/- 3ºC.
If you have a question about the melting temperature of any of our solder alloys or a solder alloy you are purchasing from us, we will be happy to share the differential scanning calorimeter readings with you for your personal interpretation.
Posted 4 days ago by Amanda M. Hartnett |
Tuesday, July 15th, 2008
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Posted by Amanda M. Hartnett
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Heat generation in a power chip. Chip can be cooled by a careful selection of solder TIM and heat sink.
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Devices with pulsing power are often among the most critical to cool due to the temperature-sensitive films they are packaged with. If these films overheat, the resistance running through the package may become altered which complicates the device performance.
There are various common heat sink/solder TIM combinations to choose from depending on the nature of the device. For instance, in the most difficult cases, (those with high frequencies and long thermal cycles) a popular choice is a Copper/Tungsten heat sink used with a TIM closely matched in CTE. One possible choice is gold/germanium preforms, which can be used to create a hermetic package. When the thermal requirements of the pulsing device change however, such as going to a shorter thermal cycle, often the CTE stresses decline and other choices (which are often more economical) in heat sink and solder choice become available.
If you would like help designing your heat sink/TIM design in a pulsed power package, please contact an indium application engineer for material suggestion and design advice.
Posted 5 days ago by Amanda M. Hartnett |
Monday, July 14th, 2008
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Posted by Amanda M. Hartnett
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At some point in our lives each of us has played the “What’s your favorite” game. “What’s your favorite…sport? What’s your favorite….Ice cream?” Well, I want to play the, “What’s your favorite TIM material” game.
I have worked with quite a few types of TIM materials in my lab testing, but surely not as many as my readers. Therefore, I’d like to know what materials you are using and why. What makes them your favorite?
All Answers are appreciated. There is no wrong answer.
It is probably only fair if I begin this forum with a note on my favorite TIM. For many reasons, but most certainly its ease of application and removal, my favorite TIM material is the pure indium Heat Spring. Just like a piece of aluminum foil, an indium preform can be cleanly applied as a preform and cleanly peeled back just as easily.
Posted 6 days ago by Amanda M. Hartnett |
Tuesday, July 8th, 2008
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Posted by Amanda M. Hartnett
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Indium Corporation’s industry leading semiconductor bloggers are hosting a Meet the Bloggers session on Tuesday, July 15, 2008 at Indium Corporation’s Semicon West exhibit, booth #7834, from 2-3pm PST.
The technology experts will lead discussions on topics including:
· Flux deposit measurement using non-contact metrology
· Two upcoming white papers (currently under development):
- Wafer Flux Spin-Coating Topography
- Wafer-Level Flux Printing
· Recent hot semiconductor blog topics, including:
- Semiconductor assembly materials
- Future trends in first- and second-level assembly
- Halogen-free semiconductor assembly materials
- Engineered solders in MEMS assembly
- Thermal interface issues
- Solar device assembly
Indium personnel who will be discussing these topics include Jim Hisert, Paul Socha, Fez Sayed, Dr. Andy Mackie, and Rick Short.
All attendees are welcome to participate in, or observe, the session. Snacks will be served, too!
Indium’s blogs can be seen at www.indium.com/blogs
Posted July 8th, 2008 by Amanda M. Hartnett |
Monday, July 7th, 2008
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Posted by Amanda M. Hartnett
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Run a test with a liquid metal thermal interface materials to determine the efficincy of your cooling stack-up
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Have you ran efficiency tests on your thermal interface materials and received unexpectedly low results? How confident are you that the resistance generated is actually at the thermal interface material?
Using a test with a liquid metal thermal interface material, you can be 99% confident that resistance in your thermal system is or is not due to the thermal interface material. There are multiple liquid metal thermal interface materials to choose from, but one way they can be used is to dispense the material onto the heat spreader, compress it as a thermal interface material, and re-run your test.
Since the interface is metal, it will have a high thermal conductivity and in molten state, the contact resistance will be approaching zero. This is the situation of an ideal interface. If your system is still reading a high resistance, it can be assumed that the heat build-up is not in the interface, but in some other location of the stack-up.
Posted July 7th, 2008 by Amanda M. Hartnett |
Thursday, July 3rd, 2008
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Posted by Amanda M. Hartnett
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Click on the Table of Scpecialty Alloys link on the Indium homepage to view physical properties of more than 200 alloys used for their thermal and mechanical properties.
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When I need any information on a direct attach solder thermal interface material, my first line of defense is my solder alloy directory, also known as the "Table of Specialty Alloys and Solders".
The information in this literature is available to you as well on Indium’s website. It contains the most popular as well as the unusually-requested solders along with many of their physical properties. Over 200 solder alloys are listed (all of which could be used as a thermal interface material) and at a minimum, you will find the melting temperatures of these materials. For many of the materials, thermal, electrical, and physical properties of each alloy are also listed.
Posted July 3rd, 2008 by Amanda M. Hartnett |
Wednesday, July 2nd, 2008
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Posted by Amanda M. Hartnett
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Design Ideas behind Compressible Metal Interface Materials
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As a Thermal Interface materials supplier, we are always looking for the next best material we can offer the market which will really fill a need. Over a year ago now Indium’s Bob Jarrett came up with a new product which would meet the consumer need for a low pressure compressible metal thermal interface material. This was the advent of the SMA-TIM. The idea hit him when he realized that pure indium held the potential to be a great compressible material. It just needed some minor mechanical alterations to make it more compressible under lower loads.
Previous to this, many of our customers were filling this need using flat indium foils. But under 100PSI, pure indium just wasn’t cutting it in performance. Since the conception of this new material we have been able to aid many of these customers by providing them with a perfectly suited material which would outperform flat indium alone.
Posted July 2nd, 2008 by Amanda M. Hartnett |
Tuesday, July 1st, 2008
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Posted by Amanda M. Hartnett
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Metal Phase Change Materails Dispensed to mold a thermal interface gap, determining physical characteristics needed for a Thermal Interface Material
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Looking for ways to troubleshoot or optimize your Thermal Interface materials? One method which we have contrived to determine the performance of your thermal stack-up excluding the thermal interface material is to use a liquid metal. This is a topic I have discussed at multiple conferences, but will discuss in-depth in a later posting.
Another method that can be used involves placing a phase change metal at the thermal interface to make a mold of the Tthermal interface material gap. Some metal thermal interface materials melt at a low enough temperature to melt during chip operation or under mild heat. At room temperature however, they re-solidify, taking a mold of the thermal interface material gap. By disassembling your thermal stack-up with the phase-change metal, you can view any non-planarity of substrates or surface roughness through inspection of the metal thermal interface material. It is unlikely that the interface material will completely squeeze-out or appear with a smooth mirror-like finish because no machined parts are perfect. This method will demonstrate just how far off perfect your material design has come.
Posted July 1st, 2008 by Amanda M. Hartnett |
Monday, June 30th, 2008
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Posted by Amanda M. Hartnett
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Liquid Metal shear and mechanical properties (viscosity) demonstrated through basic stencil printing.
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Many of my customers are now getting their minds wrapped around the idea of using liquid metals as TIMs. Until they actually have the personal experience of working with it however, they don’t fully grasp what it is like to handle.
The closest thing I am able to compare the indium-gallium liquid metals to is the consistency of mercury. Most of us have had the luxury (although an unfortunate health hazard) to play with mercury broken out of a thermometer as a child. The liquid metals used as thermal interface materials (TIMs) are quite similar in their tendency to coalesce into little balls due to surface tension. Additionally, the viscosity of liquid metal TIMs are nearly identical to mercury.
Viscosity, or the ability to withstand shear, is a very telling property of materials. It is perhaps the most significant property depending on the method of handling and application used for the material. The viscosity of mercury is 1.53 x 10-3 Pa*s and the liquid metals of the indium gallium system are almost identical.
Posted June 30th, 2008 by Amanda M. Hartnett |
Wednesday, June 25th, 2008
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Posted by Amanda M. Hartnett
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Summer Heat Causes Electronics to Overheat If They are not Designed and Handled for the Elements
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Summer is here along with the heat waves that come with it. I am personally prepared with central air and barely-there clothing for when the heat gets most intense; but are my electronic gadgets as prepared?
According to the Office of Zen and Computing, electronic gadgets are not as prepared as one might hope. Although I’m in the business of preventing gadget overheating as a supplier of cooling materials, I realize that often cooling is considered as an afterthought in electronics packaging. Because of that, I recommend following the Office Zen’s recommendations regarding electronic handling in the summer heat.
On their blog entry, they give some great tips such as:
1. Don’t Stack Electronics
“You should never stack electronic devices directly on top of each other. Is your XBox sitting on top of your DVR, which is sitting on top of your DVD player? Go do something about that, right now. Electronic devices get hot enough on their own. When they’re stacked on top of each other, they produce and conduct even higher temperatures.”
2. Position Electronics Away from Heat
“When it comes to where you store your electronics, use common sense. Keep them out of direct sunlight, and if it’s possible, in the path of a fan or air conditioner. Hot air rises, so store things on the basement or ground level of your home.”
3. In Case of Emergency, Shut Down
“If one of your gadgets begins to overheat and malfunction during the hot summer months, shut it down and disconnect it’s power supply. Let it sit and cool down until the casing is no longer hot to the touch, and then try to use it again. Make sure it’s not stacked with any other devices, and keep the area clear to allow for proper airflow.”
I believe each of these tips to be true and suggest that you follow them as a mode of protection for your beloved electronic gadgets.
Posted June 25th, 2008 by Amanda M. Hartnett |
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