Here’s a brief list of our capabilities:

Material

• Aluminum
• Metals
• Plastics
• Stainless Steel

Our Norwood MA facility does the rapid prototyping and low volume production,  here is a list of our equipment:

Machining Center

Saws & Shears

What else we got?
We have lots of stuff to talk about, but, rather than discuss the parts and pieces of our rapid prototyping and high volume manufacturing, its’ better to talk about examples, and we’ll be doing some of that this week here on ATS’s blog.  In addition, we’ll be highlighting a very important engineering article on how to manufacture cold plates.

Consumer electronics are now being used in places that were once exclusive to business and military electronics. Products like Apple’s iPhone and iPad are sophisticated technologies with powerful processors housed in small spaces with restricted airflow. As a result, these devices, and others like them, are providing many new benefits, but they also bring higher thermal management needs. Attendees will learn the available cooling options, and important factors such as the importance of spreading resistance in component and system thermal management.

The webinar is going to be chock full of great information cooling consumer electronics.    The webinar is free and taught by Dr. Kaveh Azar, one of the worlds foremost authorities on heat transfer.  Click here to register: “Thermal Management of Consumer Electronics“

Use cases include:

• Consultants:   Are  you on premise with your client?  Once you understand your needs for a heat sink, use our heat sink design tool to get a product fast.
• Field Engineers:  If your in the field, taking notes on what heat sink to use might be impractical.   Use our heat sink design application to punch in the parameters for a heat sink and get it done right there.
• Students:  If your in the lab working on your next project, why not use our convenient application on your Android device to get our project that much quicker to completion

You say you use an iPhone?  Well, we have an App for that too!  Apple iPhone Heat Sink Design App

And for a more robust alternative to a thermocouple, consider ATS Spot Sensor,  you can learn more about our spot sensor at this link or get a quote at this link.

Thanks for your patience!

4 — Infrared Thermography

Infrared thermography works on the basis of the IR waves emitted from a heated surface. The infrared system captures the waves, and based on internal calibration converts them into temperature. The following are required for IR-based measurements:

• Infrared imaging system — The market offers a broad range, but a worthy system starts at around $30-70k. For IR microscopy (down to 5mm only-lower limit of IR wave-length), the system starts at $180k.
• Signal processing equipment.
• Knowledge of emissivity – if the test specimen must be coated with a known emissivity material.
• Calibration.

Figures 5a and 5b show a typical IR image of heat-emitting surfaces:

5a shows and IR image of a PCB in forced convection air flow[3]

5b shows and IR image of a PCB in forced natural convection air flow[3]

The following points are noteworthy when using an IR camera for temperature measurement:

• Application accuracy is a function of emissivity.
• The measurement situation must duplicate the actual environment, as far     as air velocity, temperature and air flow distribution are concerned.
• The IR camera is sensitive to reflected radiation.
• Carbon dioxide and water vapor absorb significant energy and may cause significant error.
• In an electronics application, surfaces typically have different emissivities thus, one must make the emissivity uniform before measurement of known emissivity (black paint or powder).
• In most IR equipment, the temperature readout is the average over an area. Therefore, temperature peaks may be ignored as the result of integration. To remedy the situation, better IR optics must be used to reduce the area where integration occurs.

5 — Optical Probes

Optical sensors are light-emitting devices that illuminate the test body with source radiation, and can detect reflected radiation, or simulated radiation such as fluorescence. Although not broadly used, optical probes are used at the die or component level. Figure 6 shows one such a probe.

Figure 6. Optical Probe For Surface Temperature Measure-ment — The Probe Either Touches The Surface Or Captures The Reflected light From A Fluorescent Treated Surface.

 6 — Liquid Crystal Thermography

LC thermography works on the basis of visible light reflected from a surface treated with the LC material. The system captures the reflected wavelengths, and based on internal calibration, converts them into temperatures. Liquid crystals (LCs) are cholesteric materials. When applied to a heated surface they realign and reflect light at a different wavelength. The reflected light shows the standard colors seen in a rainbow. Figure 7 shows the application of LCs on an IC.

Figure 7. Color display of liquid crystal applied on an IC. Blue reveals the circuit’s hottest point, and black shows that the temperature is outside the range of the crystal material [3].

The following are salient features of LC material:

• Liquid crystals are organic compounds that can be poured like a liquid, yet reflect light like a crystal.

• Changes in LC optical properties can be produced by externally applied fields (e.g., electrical, magnetic, and thermal).

• Cholesteric liquid crystals progressively exhibit all colors of the visible spectrum when heated over their event temperature range.

• Width and placement of the event temperature range can be controlled by selecting and mixing the appropriate liquid crystals.

• Liquid crystals are commercially available with event temperatures ranging from below 0^oC to 160^oC, with spans ranging from 1 to 50^oC.

An LC thermography system such as the one shown in Figure 8 can provide a very effective temperature-mapping system.

Figure 8:  The thermVIEW System for Macro and Microscopic (down to 1um) Surface Temperature Measurement[4]

Figure 9 shows a typical result of LC thermography at die level:

Figure 9. Temperature distribution across a memory chip (5 x 5 mm) at T_ambient = 25^oC, as shown using Liquid Crystal Thermography [3].

Like any other system for temperature measurement, LC thermography offers distinct advantages and disadvantages. One salient advantage of LC thermography is that it’s not dependent on surface emissivity. A second is that at micron and submicron levels, though not a trivial task, LC thermography allows easier and less costly temperature measurements while enabling 1µm or smaller spatial resolution. One disadvantage of LC thermography is that it is not a pick-up-and-measure system like IR. One must apply the calibrated liquid crystal material to a surface in order to perform the measurement. But, this is similar to the IR system, in that you need to make the surface emissivity uniform if the measured surface has multi-emissivity (e.g., a die or PCB).

In this article, we reviewed six different probes/techniques for temperature measurement. It would be a missed opportunity not to include a word on calibration. Irrespective of the types of measurement and sensors one uses, calibration is of utmost importance. Pay special attention to the calibration process and ensure that the sensors are properly calibrated. Further, one needs to ensure that the chosen sensor is suitable for the type of measurement. As Prof. Frank White states in his Viscous Flow book, “Bad data is worse than no data at all” [5].

To catch up on the series or read from the start, you can click to Part 1 of our series or click over to Part 2 of our series.

References

1. Klinger, D., Nakada, Y., Menendez, M., AT&T Reliability Manual, Van Nostrand Reinhold, 1990.
2. Azar, K., Thermal Measurement in Electronics Cooling, CRC Press, 1997.
3. Advanced Thermal Solutions, Inc., Tutorial Series, “Principles of Temperature Measurement”.
4. thermVIEW™ System, product of Advanced Thermal Solutions, Inc.
5. White, F., Viscous Fluid Flow, McGraw-Hill, 3^rd Ed., 2005.

If  you are in need of sensors for thermal measurement, click now to ATS’s sensor family.   To learn more about ATS ‘ thermVIEW liquid crystal thermal analysis system, click to thermVIEW System.   You can also email or call us with your questions on temperature measurement and one of our engineers will be happy to help you.  Email us at ats-hq@qats.com or call  us at 781-769-2800.

1 — Resistance Thermometer

With these sensors, the resistance of the sensing element changes with temperature. The sensors come in two primary forms: thermistors (lightly doped semiconductors) and metal resistors. Equations 3 and 4 represent the relationships between resistance and temperature for these two sensors, respectively:

Figure 1 shows a surface-mounted RTD (resistance temperature detector) that can be installed onto a surface for temperature measurement:

Figure 1: Surface mounted RTD (photo courtesy of RDF Corporation)

 The following must be considered when using these types of sensors:

1. The sensor (resistor) must be in intimate contact with the test specimen — solder or careful epoxy is recommended.
2. The sensor must be placed in an isothermal region — constant temperature over the sensor.
3. The resistor power dissipation (if in voltage mode) must be minimized to not impact the problem.
4. This sensor is suitable for part-level measurement as it can be embedded directly on the die.

2 — Thermocouples (TC)         

These sensors are far and away the most commonly used devices in the field. Wide flexibility and broad availability enable their use for a variety of temperature measurements. TCs work on the principle that bringing together two wires of different elements or alloys produces a voltage as a result of temperature. Equation 5 provides the governing principle for TCs:

Table 2 shows some of the typical TC types that are used in electronics thermal measurement.

Table 2: Thermocouple Types and Their Respective Voltage Outputs [2]

Of the TC types shown above, E, J, K and T are the most commonly used. Many thermocouple meters on the market can use all of these sensors interchangeably. That’s because the voltage output of these TCs is in the same range; hence, the internal electronics can be designed to accommodate each of them.

There are some unique features about each sensor type that one needs to know. For example:

• E-type —  Though accurate, has a limited range.
• J-type —  Should not be used in a humid environment, since the iron component of the TC will oxidize, resulting in erroneous output.
• K-type —  Though widely used, the voltage output can be negatively impacted if the wire kinks.
• T-type —  Can be an effective heat transfer medium, because of its copper component, either as a fin or a conductor.

It is also important to note that thermocouples measure temperature at the point where the two wires are connected. The smaller the junction, the more precise the temperature that is read. A large TC junction will result in the temperature being averaged over its entire area. Multiple junctions, as shown in Figure 2, will have the same impact. In Figure 2, the multi-junction created as a result of twisting the wires prior to spot-welding the ends (the TC below), creates a significantly larger junction. Whether measuring surface or fluid temperatures, the number reported by this TC will report an average temperature over a 2-3mm junction length.

Thermocouple errors can be attributed to the following areas:

• Poor junction connection
• Galvanic action
• Thermal shunting
• Electrical noise
• Installation problem due to tester

 Figure 2: Single and Multi-junction Thermocouple Sensors [3]

Of the errors listed above, electrical noise is uniquely problematic, especially in today’s high frequency equipment. A TC can be used in a 4-wire format to resolve the electronic noise that may affect the reported temperature. Using a 4-wire thermocouple, as shown in Figure 3, we can measure temperature and electrical noise.

Let us consider a J-type thermocouple formed of Iron and Constantan. All four wires are spot-welded together to form the TC junction. The temperature can be read across any of the Iron and Constantan combinations (?), and the electronic noise can be read across either the two Irons or the two Constantans. Because two similar metals cannot create the Seebeck effect (convert thermal differentials to electric voltage), whatever signal is measured on these wires is the electronic noise in the measurement domain.

 Figure 3: Four-wire Thermocouple System for the Measurement of Electronic Noise and Temperature

Measuring surface temperature is always a challenging process. The following steps will help to increase the accuracy of such measurements:

• Keep installation size as small as possible.
• To reduce conduction errors, bring thermocouple wires away from the              junction, along an isotherm for at least 20 wire diameters.
• Locate the measuring junction as close to the surface as possible.
• To avoid changes in convective or radiative heat transfer, design the installation so that it causes minimum disturbance to any fluid flow or the least possible change in the emissivity of the surface.
• Reduce the thermal resistance between the measuring junction and surface to as low a value as possible.

3 — Diode or Transistor

Diodes and transistors are parts whose electrical properties are a function of temperature. Diodes are broadly used for temperature measurement, either as embedded sensors in functional devices or as a thermal test chips. Figure 4 shows one such thermal test chip for device-level simulation.

Figure 4.  Thermal Test Chip [3]

The following depicts the general considerations for usage of semiconductor materials for temperature measurement:

• Every semiconductor device has at least one electrical parameter that is a              function of temperature.
• Thermal test chips use the thermally sensitive parameter of semiconductor devices to measure chip junction temperature.
• Separate heating and sensing elements are usually used to avoid for electrical switching.
• Thermal calibration of the sensing device is necessary.
• Thermal test chips provide an effective means of measuring chip junction temperature in an actual package configuration.
• Use of materials is subject to availability/suitability for the intended package application.

We’ll conclude our series with part 3, addressing infrared thermography, optical probes and liquid crystal thermography

References:
1. Klinger, D., Nakada, Y., Menendez, M., AT&T Reliability Manual,
Van Nostrand Reinhold, 1990.
2. Azar, K., Thermal Measurement in Electronics Cooling, CRC Press,
1997.
3. Advanced Thermal Solutions, Inc., Tutorial Series, “Principles of
Temperature Measurement”.
4. thermVIEW™ System, product of Advanced Thermal Solutions, Inc.
5. White, F., Viscous Fluid Flow, McGraw-Hill, 3rd Ed., 2005.

If  you are in need of sensors for thermal measurement, click now to ATS’s sensor family.  Tired of using thermocouples that are finicky and breakable? Try ATS’s spot sensor.  It’s durable and cost effective.  Learn more by clicking to ATS Spot Sensor.   You can also email or call us with your questions on temperature measurement and one of our engineers will be happy to help you.  Email us at ats-hq@qats.com or call  us at 781-769-2800.

It is a generally very well attended webinar, covering what new technologies emerged in 2012 in thermal management, which are useful, and which might not be worth checking. To register, click to our GoToMeeting registration page here: Registration for What is The State of the Art in Thermal Management?

In today’s market, it is very rare to see electronic equipment that has not undergone extensive thermal evaluation, either by measurement or simulation. Inevitably, the temperature of the device junction or case, or the enclosure, has been measured to ensure that the system will operate to its intended specifications.  A quick look at the equations associated with stress in a lead wire, and with the acceleration factor used in reliability calculations, will show why temperature plays such an important role in electronics equipment [1].

Equations 1 and 2 clearly demonstrate the linear and exponential relationships that temperature has in the operation of the electronic components. Concurrently, simulation tools are used extensively in today’s thermal design. But, due to the complexity of the electronics packaging and composite nature of the materials used, the simulation data must be verified in order to ensure reliable data is obtained. In this article, we present different sensors and their application domains in electronics thermal management.

Table 1 shows six primary sensors used in temperature measurement:

Table 1.  Standard Temperature Transducers [2]

In part 2 of our three part series, we’ll start consider each sensor in detail, focusing on the resistor thermometer, thermocouple and diode transistor.

References:
1. Klinger, D., Nakada, Y., Menendez, M., AT&T Reliability Manual,
Van Nostrand Reinhold, 1990.
2. Azar, K., Thermal Measurement in Electronics Cooling, CRC Press,
1997.
3. Advanced Thermal Solutions, Inc., Tutorial Series, “Principles of
Temperature Measurement”.
4. thermVIEW™ System, product of Advanced Thermal Solutions, Inc.
5. White, F., Viscous Fluid Flow, McGraw-Hill, 3rd Ed., 2005.

If  you are in need of sensors for thermal measurement, click now to ATS’s sensor family.  Including our industry leading Candlestick Sensor.   You can also email or call us with your questions on temperature measurement and one of our engineers will be happy to help you.  Email us at ats-hq@qats.com or call  us at 781-769-2800.

ATS has expanded once again this week with our tie up with Weiss Company.  Weiss is a Canadian technical electronics sales organization.  We’re excited to have them on board frankly as they bring quite a bit to the Canadian market space.  But, what’s in it for our customers?

First, they are local to Canada.  So while ATS’ main headquarters are in Norwood, MA (just 20 miles south of Boston), we are close to Canada but not in Canada.  Weiss is there and that will make a big difference bringing ATS support to thermal engineers there.

Second, they aren’t “just” a sales organization.  They are composed of both field sales engineers, (FSE) and certified electronics technicians (CET).  What this means for our customers is that Weiss extends ATS’ support network right into Canada.  The Weiss company has a direct like to our factory and design team.  Customers of Weiss/ATS will have best possible support for their thermal management programs.

Third, they have been in the market for 40 years, so they are a stable company with an  understanding of the needs of our customer’s in Canada.

If you are in Canada, drop Ken Kong at Weiss Co an email and let him know ATS sent you, his email is kkong at jgweiss.com

We had a chance to have a quick phone conversation with their Manager of Business Development, Phil Vogel last week.   Test Equipment Connection has been around since 1993.  They both buy and sell test equipment and provide full support.  He noted that thermal analysis and measurement is a growing need in the technology sector and we couldn’t agree more!   Our latest one day short course on thermal management was sold out!

So, if you need test equipment, such as spectrum analyzers or RF or microwave test equipment or ATS thermal test instruments, visit their web site at http://www.testequipmentconnection.com/ and contact them!

You can read more about it at our press release page.

It seems like a contradiction in terms doesn’t it?  Why would a thermal management company like ATS teach you to design out your heat sinks?  Wouldn’t we be better business people if we helped you design in more heat sinks?

Well, no.  And here’s why.

At ATS, we are the leader in Innovations in Thermal Management.  And for us, those innovations have to be useful.  There are many innovations in thermal management in the market but most simply aren’t truly practical to deploy except in a lab.

Here’s the link to join our free webinar, Thursday, December 15th, 2PM EST, “How to Design Out Your Heat Sinks with Smart PCB Thermal Design”.

And, many innovations are not products. They are know how, experience and understanding of the vectors involved in todays complex thermal management problems.   And that’s why ATS’s team would teach our customer’s how to design out their heat sinks.  Because we believe in innovations in thermal management that work.   Understanding how to optimize air flow with your PCB works.  Once  your optimization is set, then buy your heat sinks (hopefully from us!).

Can’t make our webinar?  Then visit the following links to reach important resources on this topic:

• Four Printed Circuit Board Thermal Management Stragegies
• ATS’s QooLPCB program for low cost supply of heat sinks for your PCB
• ATS’s PCB Thermal Design Services

ATS is proud to announce our maxiFLOW push-pin heat sink is THE winner of the EDN Hot 100 Products for 2011!  We were the lone selection in the EDN 100 for heat sinks and we are quite proud.  Our award underscores our motto:  Innovation in Thermal Management

• How to Compare the Thermal Performance of Different Heat Sink
• Synthetic Air Jet for Electronics Cooling
• Waste Heat Recovery of Electronic Equipment
• Effect of Cross-Flow on Straight and Inclined Jets

The article, “How to Compare the Thermal Performance of Different Heat Sink” is one we want to highlight.  Some of the key points covered include:

• Effect of materials in comparing heat sinks
• Proper wind tunnel testing
• Data analysis and computation for tests

Qpedia’s current issues are always no cost to our readers.  Our Qpedia back issues are available at no cost for readers who register on qats.com

To read this Qpedia Thermal eJournal article in full, just click to this link:  Long Term Thermal Grease Reliability

To learn more about thermal interface material, join our free webinar on “Understanding and Choosing the Best Thermal Interface Materials to Improve Heat Sink Thermal Performance“, Thursday, November 17th, 2PM

In the meantime we thought we’d list many of the current thermal interface companies in the market today to give you a “one stop” shop to source the right thermal interface material for your next project.   Here’s the list,  all links worked based on testing here at QATS.

• Fujipoly:  Thermal putty and gap fillers.  Don’t discount this stuff!  Worth a look for bridging the IC to the case without a heat sink. Also useful where you need to fill in spaces with odd shapes.  In some applications can be near to phase change material performance
• Chomerics:  One of our favs.  Phase Change Material (PCM) that works almost as good as grease but with none of the mess. You must have the proper pressure over time on the heat sink to the PCM to make this work well.  Obviously, we’d recommend our superGRIP or maxiGRIP for that task.
• Bergquist: Various types of thermal material.  Just announced a new phase change material type.
• 3M: Thermal tape, pads and epoxies
• AI Technology: Phase Change Material and Thermal Grease
• Laird Technology: Gap filler, Phase Change Material, Thermal Grease
• Honeywell:  Phase Change Material and the innovative printable thermal material good to 150 degress C.
• Shin Etsu: Thermal greases, thermal gels, Phase Change Material and more
• Dow Corning Thermal:  Various thermal interface materials in both pads and films
• Locktite Thermal:  I won’t kid you, we aren’t fans of thermal epoxies but in some cases you just have to do it.  Locktite has some nice products for that and we know several telecomm OEMs using them.
• NuSiL:  Offers low outgassing thermal interface material
• Indium:  Metal thermal interface materials

To learn more about thermal interface material, join our free webinar on “Understanding and Choosing the Best Thermal Interface Materials to Improve Heat Sink Thermal Performance“, Thursday, November 17th, 2PM

Register for this webinar by clicking to our registration page here:  Understanding and Choosing the Best Thermal Interface Materials to Improve Heat Sink Thermal Performance

You can register at no cost to you at this link:  https://www2.gotomeeting.com/register/738227666