Tag Archives: heat sink

What is electronics thermal management?

Posted on January 6, 2011 by | Leave a comment

We talk a lot here on the ATS Thermal Management blog about thermal management. And there’s a good reason for that of course! That’s what we are fanatical about. Keeping electronics cool so they operate at their best design point.

But, after you peel back boiling points, forced thermal spreaders, heat sinks, liquid cooling, thermal interface material, and more you are left with one critical, salient point about what is electronics thermal management.

To ensure that the device junction temperature (Tj) stays below a set limit.

What is a junction? The Hottest Spot on a Chip

this photo shows the semiconductor junction temperature hot spot

When semiconductor designers make a chip, especially a complex ASIC or something like an Intel server processor, these chips are effectively systems. Packed with circuits, and often in very dense packages, certain parts of the chip have sections that operate with greater frequency than other parts.  The result, those “spots” or “junctions” are very hot.  And so, cooling that junction is the key to all this Thermal Management. That’s our goal.

In fact, the first step in really getting the right solution to your projects thermal challenge is to determine it’s junction temperature. Here’s some handy helps to get you there….

How to calculate a semiconductor junction temperature part 1

How to calculate a semiconductor junction temperature part 2

Once you’ve calculated your junction temperature, you can then have a much better chance of choosing the right heat sink.

Of course, if you ever need help with this ATS is here. You can email us at [email protected] or give us a call at 781-769-2800 We’re always happy to help with your thermal management projects.

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Posted in thermal management, Thermal Science

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Three questions an engineer should ask prior to using thermal epoxy for their heat sinks

Posted on January 5, 2011 by | Leave a comment

We’ve seen a big uptick in use of epoxy by our customers here at ATS. To our engineers that is alarming. While thermal epoxy initially appears to be a good solution for attaching a heat sink to a chip, accomplishing both the attachment and the thermal interface material in one “quick” glue application design engineers and manufacturing engineers should stop and ask themselves the following three questions before deciding to move ahead.

(1) Does it have to be glued?
Many times glue looks like the easy answer since its generally cost-effective and can be easily applied. But the question “does it have to be clued” really stops you short to make you examine potential alternatives. Don’t forget, thermal epoxy can expire and lose it’s properties.

(2) Is the perceived cost/time savings in assembly worth the actual cost of rework?
Many times thermal epoxy is a quick default choice, “just glue it on” has the sound of a quick solution that should work in average applications.  But that’s not the case.While it looks easy, thermal epoxy requires consistent application to the semiconductor the heat sink is being glues onto. To get that consistent application can require some training (a “soft” cost). But the real caution is the rework. No one “expects” reworks but reworking a company’s computer boards is reality. And with thermal epoxy being used for your heat sinks the rework requires either hot air guns (an additional expense) or destruction of the components under the heat sink. The cost of the rework may exceed the cost savings of using epoxy. Don’t forget the cost of  using thermal epoxy for your heat sinks includes training on how to use epoxy, special equipment to remove epoxied heat sinks and the cost of the material (which has a shelf life and many times must be refrigerated).

(3) Is epoxy being chosen to secure your heatsink?
While the epoxy bond is secure, it’s not foolproof. In fact ATS has seen many epoxied heat sinks that fell off during shock and vibe testing. What generally happens is that heat will weaken the epoxy mechanical bond then, when a strong shock or other mechanical stress is applied, the weakened bond with break, leaving your heat sink in free fall and your semiconductors overheating.

Want some alternatives? Check out our blog post series,

How to choose a heat sink attachment method to secure your heat sink and for optimal heat transfer Part 1

How to choose a heat sink attachment method to secure your heat sink and for optimal heat transfer Part 2

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Posted in Heat Sink Attach, heat sink clip, Thermal Interface Material

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How ATS heat sinks helped two tier 1 telecommunications companies implement effective thermal management for their LTE and WiMAX equipment

Posted on November 29, 2010 by | Leave a comment

Advanced Thermal Solutions, Inc (ATS), a leader in offering Innovations in Thermal Management, recently demonstrated that its maxiFLOW heat sink with superGRIP heat sink clip can cool semiconductor-dense and thermally-challenging LTE and WiMAX telecommunications network equipment. Two Tier 1 telecommunications equipment OEMs had faced significant thermal and mechanical challenges on their new designs.

Telecommunications

(Wikimedia Commons)

Deploying ATS thermal management technology allowed them both to ship their network equipment to customers in Japan and the United States, meeting schedules, and winning the confidence of their major customers, both wireless providers.

In example one, an ATS customer was faced with a real dilemma. Having used microTCA and other modular technologies to develop both their WiMAX and LTE telecommunications infrastructure equipment, they faced the challenge of dealing with high heat and restricted air flow in their system. After considering various options, they opted to test ATS’s solution.

The results were dramatic, reducing board temperature 15%. The temperature reduction made it possible for the systems to operate at the designed performance levels, and keep the manufacturer’s development costs in check since no architecture changes or fan additions were necessary. Their U.S. and Japanese wireless customers received their equipment and successfully trialed.

In example two, ATS’s customer was at the start of launching their new 4G LTE telecommunications platform. Early trials showed great promise but thermal issues dogged the design, making reliability a concern. This customer knew their design needed some additional thermal management technology to realize its design specification. They called in ATS to perform root cause analysis of the problem and provide a solution.

After performing both CFD and physical tests, the problem was identified. ATS’s maxiFLOW and superGRIP technologies were then deployed in the customer’s system. Resultant tests successfully improved reliability, while only adding single digit percentages to the product cost.

Both these examples show the advantage of ATS thermal management technology in telecommunications equipment.

Learn more about how your next or current telecommunications equipment project can be cooled so it can operate at its peak performance level, visit https://www.qats.com/Consulting/Custom-Cooling-Solutions.

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Posted in Case Studies

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Porous copper material unveiled giving microchannel waterblocks some real competition

Posted on November 11, 2010 by | Leave a comment

Just this week Elektron Ventures released a new porous copper material that in liquid cooling devices is reported to be three to ten times more effective at transferring heat into a passing coolant than a microchannel water block of similar size.

We’ve covered microchannel technology before here on ATS’s blog since it’s such an important technology for use in liquid cooling at the semiconductor level. In fact you can read many of those back posts and resources on microchannel technology, research and application at this link here: ATS Blog Microchannel Roundup. But let’s get back to Elektron’s porous copper.

Known as AdvarienCU, the open cell copper foam allows significant controllable porosity from 50 – 85%, resulting in a vast specific surface area, making AdvarienCu an extremely effective material for exchanging heat into a passing cooling fluid. AdvarienCu’s open cell porous structure allows coolant fluid to carry heat away to a radiator more effectively than expensive micro-machined structures and removes the need to install a bulky fan.

Tests by a leading academic research group found AdvarienCu-based liquid cooling devices to be three to ten times more effective at transferring heat into a passing coolant than a microchannel water block of similar size.

That’s quite a bump up in performance and certainly worth at least exploring for any upcoming microchannel applications your team may have in your next thermal management project.

You can learn more about Advarien here at their site: AdvarienCU

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Posted in Heat Sink Material

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How Heat Sink Anodization Improves Thermal Performance (part 2 of 2)

Posted on November 10, 2010 by | 14 comments

In part 1 of this 2 part article, we discussed heat sink anodization, and how it affects radiation cooling in thermal management. In part 2 we’ll cover the heat sink anodization process and different types of anodization.

A typical anodizing process has five steps: cleaning, pretreatment, anodizing, coloring and sealing. First, alkaline and acidic cleaners are used to remove any residual grease or dirt on the surface. Next, the surface is etched using sodium hydroxide to remove minor surface imperfections. At this stage, a thin layer of metal is removed to create a matte or dull finish. This surface is then brightened to a near mirror finish with a concentrated mixture of phosphoric and nitric acids which chemically smooths the metal surface. The surface is now ready to be anodized by passing an electrical current through an acid electrolyte bath in which the metal is immersed. The coating thickness and surface characteristics are tightly controlled to meet end product specifications [3].

Coloring can be achieved in a number of different ways. The most technically advanced color quality is obtained from the two-step electrolytic coloring method. The anodized part is immersed in a bath containing an inorganic metal salt, and then current is applied which deposits the salt in the base of the pores. The resulting color is dependent on the metal used, the processing conditions and the dye intensity of the organic dyes. Commonly used metals in inorganic salt baths include tin, cobalt, nickel, and copper [3].

Even though the main concept of surface anodizing is the same, the process could differ in terms of the acidic electrolyte used. One of these is chromic acid, or type 1, anodizing. In this process, the color will vary from clear to dark gray depending on the alloy. Copper alloys only yield gray colors. The thickness of the surface anodizing for this process usually ranges from 0.5 to 7.6 microns [3]. Because the anodized thickness in type I is not thick, it is not as readily dyed as the other types of anodized surfaces uses sulfuric acid. This is known as type II anodizing and can produce an anodized layer with a thickness from 1.8 to 25.4 microns. Because the thickness of type II anodizing is sufficiently large, an organic dye or color could be easily applied with the two-step electrolytic coloring method.

Type III anodizing refers to hard coat anodizing (hard anodizing) with a thickness from 12.7 to 115 microns. This method is often used where the environment is harsh and extreme and the anodizing must protect the part against long term corrosion, weather and wear damages. The thickness for these three types of surface anodizing is summarized in Table 1.

heat sink anodization types

References:

  1. Radiation Heat Transfer and Surface Area Treatment, Qpedia Thermal eMagazine, June 2008.
  2. Edwards, J., Coating and Surface Treatment Systems for Metals, Finishing Publications Ltd. and ASM International, 1997.
  3. Aluminum Anodizer Council Web Forum.
  4. Gustavsen, A. and Berdahl, P. Spectral Emissivity Of Anodized Aluminum And Thermal Transmittance Of Aluminum Windows Frames, Nordic Jounnal Of Building Physics, Vol.3, 2003.
  5. Ozisik, N.,Heat Transfer: A Basic Approach, McGraw-Hill, 1984.
  6. Highly Emissive Ion Beam Textured Surfaces for Improved Cooling of Electronic Devices, Electronics Cooling Magazine, September 1997.
  7. Chi, T. , Ballinger, R., Olds, R., and Zecchino, M., Surface Texture Analysis Using Dektak Stylus Profilers, Veeco Instruments, Inc.

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Posted in heat sink

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