By collecting and analyzing more relevant measurement data, electronic cooling systems can be designed for improved performance, reliability, and cost. It’s essential these measurements be as accurate as possible. Critical data points include component temperature, air temperature, air flow rate, and often air pressure. Accuracy becomes even more important when performing accelerated testing as seen in this post.
Research-grade instruments and specialized sensors, properly calibrated and operated, can measure chip temperatures and surrounding elements, such as local airflow. Separate instruments can be used to quantify specific conditions, but more real-use data is obtained when all points are collected simultaneously. Taken over a range of time and conditions, simultaneous measurements provide more accurate, actionable information. They also reduce the cost and set-up time for multiple studies.
Fig 1 – Input Ports for a Laboratory Instrument that Simultaneously Measures Air Velocity, Temperature and Pressure. [ATS]Fig 2 – High-quality Thermal Data Reduces Uncertainties in Cooling Solutions than Calculated Data. [ATS]
Accelerated Product Reliability Testing
Reliability testing at different temperatures and conditions is commonly performed to identify expected product life. When an electronic system is running, it continuously experiences temperature and power cycling. These fluctuations are typically normal, but should be factored into a comprehensive thermal profile study.
It’s not practical to wait years to see if a component fails. Accelerated life testing provides faster predictions. A commonly used predictive tool is the Arrhenius model shown below.
Accelerated life testing using the Arrhenius model is a method for predicting how long a product will last under normal conditions by running it at elevated temperatures for a shorter time. The temperature increase speeds up the same failure processes that would eventually occur in the field—compressing years of life into weeks of testing.
Accelerated life testing Arrhenius calculators can help estimate field lifetime, test duration, acceleration factors, activation energy, and field failure rates. These tools are useful when real-time qualification can’t be done. This is typical with electronic components and devices that need fast market introduction. One such calculator is found here: Accelerated Life Test Arrhenius Calculator. [1]
The Arrhenius Model handles pure thermal stress, while the Eyring Model includes temperature plus other active forces like humidity or voltage. [1,2]
Highly Accurate Thermal Instruments
Besides its design, a thermal instrument’s construction and calibration should be high quality, and not a source of more errors. Accurate, research-grade instruments are essential for valid engineering practices. Without them, reliability predictions for a new product are actually less reliable themselves.
Fig 3 – Candlestick Sensors are Thin Profile (0.5 mm) with a Small Base (9.5 mm dia) for Collecting Air Temperature and Velocity Data at Single or Multiple Locations. [ATS]Fig 4 – Here, Air Temperature and Velocity Measurements are Taken Every Second by an eATVS-8 Instrument. stageVIEW Software Provides a Wide Range of Data Collection Choices. [ATS]
Here are some of the ATS instruments available for temperature and velocity measurement and providing the highest-quality thermal reliability test results.
Conclusion
Temperature has a significant effect on reaction rate and the subsequent reliability prediction. Small errors in temperature and airflow measurements can significantly impact reliability predictions. Such errors typically occur in the measurement process or from using inaccurate instruments.
If thermal data is inaccurate, outcomes can include over-designed systems, cost overruns, and products not shipping.
Laboratory-quality thermal instruments can reduce or eliminate measurement and calculation mistakes, leading to higher quality, faster to market and ultimately lower cost products. Just as important, collected data needs to be correctly interpreted. Expert thermal engineers can do just that with data provided or that they obtain themselves.
More information on these topics can be seen at these ATS videos:
How to Properly Measure Air Velocity in Electronic Systems [Link] [3]
How to Perform and Understand Temperature Measurement within Electronic Systems [Link] [4]
Thanks to faster boot-up times and enhanced reliability and performance, solid-state drives (SSD) have grown in popularity with consumers in the past decade. From laptops to portable hard drives to telecommunications applications, solid-state drives are eclipsing hard disk drives, particularly as the price of SSD technology lowers, making it more cost-effective for system designers.
What makes the SSD different? Solid-state drives have no moving parts. There is no mechanical arm to read and write data. Instead SSD use embedded processors to control the processes related to storing, retrieving, caching, encrypting, and cleaning up data.
Apple is one of many laptop companies that have turned to solid-state drives for laptops because of improved boot times and better battery efficiency. (Wikimedia Commons)
As explained by Storage Review, “Conversely, a hard disk drive uses a mechanical arm with a read/write head to move around and read information from the right location on a storage platter. This difference is what makes SSD so much faster. As an analogy, what’s quicker? Having to walk across the room to retrieve a book to get information or simply magically having that book open in front of you when you need it? That’s how an HDD compares to an SSD; it simply requires more physical labor (mechanical movement) to get information.” [1]
Consumers and engineers alike are turning to SSD and that has made a number of companies jump into the market, although, according to a recent report that counted global sales through 2016, Samsung (21 percent) and Kingston (16) percent remain the largest retailers of SSD in the world. All the other companies listed, including Intel, SanDisk, and Toshiba, all had percentages in the single digits. [2]
The benefits of SSD are well-known: System boot times that are typically 1/3-1/4 of HDD, half of the power draw for longer battery life, much larger storage capacity, reduced noise during use, and greater mean time between failure (MTBF).
One area of importance for SSD, which is another byproduct of no moving parts, is that they generally produce less heat than HDD. For instance, you are less likely to burn your lap while working on your laptop if it has a solid-state drive. Thermal issues remain for SSD, as they do for any electronic device, but compared to HDD they have fewer cooling requirements. [3]
A recent study out of Carnegie Mellon University (Pittsburgh, Pa.) in collaboration with Facebook, Inc. analyzed the reliability of flash-based SSD. One of the external factors that the researchers considered was temperature. In examining three distinct groups of SSD in a Facebook data center, the study described similar failure rates at a range of 30-40°C, but the failure rates varied greatly as temperatures increased beyond that operating range. Failure rates are explained in the following tables. [4]
This chart from researchers at Carnegie Mellon demonstrates the instability that temperature spikes cause in SSD performance. [4]
The researchers concluded, “In general, we find techniques like throttling, which may be employed to reduce SSD temperature, to be effective at reducing the failure rate of SSDs. We also find that SSD temperature is correlated with the power used to transmit data across the PCIe bus, which can potentially be used as a proxy for temperature in the absence of SSD temperature sensors.”
Temperature is an increasing factor for SSD. Like the rest of the electronics industry, engineers are designing SSD to handle more chips, more channels, more cores, and more controllers to handle a greater level of processing capability. A study from the Computer Architecture and Memory Systems Lab at the University of Texas – Dallas (UT Dallas), presented at HotStorage 2014, reported that there were 64 times as many chips and channels in SSD as there were just 12 years before. Just like the Carnegie Mellon study, the UT-Dallas researchers determined that “device-level protection mechanisms dynamically reduce heat output.” [5]
This chart from UT-Dallas shows the performance degradation that comes from overheating of SSD. [5]
The UT-Dallas study concluded that overheating led to malfunctions in the SSD and that devices with larger data sizes reached the overheating point quicker. According to the report, there was “significant performance degradation at the overheating points” and that overheating and its requisite power throttling “hinder SSD from integrating more resources.” This problem, the study concluded, was “holding back state-of-the-art SSD from achieving potential performance gains.”
As SSD continues to gain a stronghold in the market, including Intel’s recent announcement that it was going to accelerate the deployment of its SSD technology throughout its product line to “enhance user productivity and mobility while reducing IT total cost of ownership,” [6] it is obvious that thermal characterization of SSD and thermal management of systems with SSD are primary concerns for the industry.
There is also a real cost to bad data and SSD are not removed from that risk. From the CPU to the PCB to SSD storage, inaccuracies and outright errors adversely impact device reliability and system design. One model that is commonly used in the characterization of SSD and other data storage products is the Arrhenius Model:
where:
This reliability model has temperature as a key component. These models can be used via pen and paper, computer modeling or on a spreadsheet. But is the Arrhenius model a good model for NAND (negative-AND) flash memory?
Data presented at the Flash Memory Summit in 2014 by IBM showed that reliability models such as Arrhenius are not necessarily accurate for characterizing SSD. Indeed, such a model can end up creating a correct match for just two data points. The presentation recommends that acceleration models be validated. In addition, it is recommended that it is best to test a full device and that doing so will best allow measurement of the total behavior. [7]
The Storage Networking Industry Association (SNIA) also released a test methodology, test suite, and reporting format for SSD to ensure the accuracy and reliability of the data being reported. [8]
Measuring the thermal characteristics of SSD is similar to the process of characterizing a standard semiconductor. A typical test setup for characterization would include a closed-loop wind tunnel, preferably with heater, sensors, thermocouples or RTD and an analog-to-digital capture system or hot wire anemometer. A closed-loop wind tunnel with heater provides an environment for controlled temperatures from ambient to 85°C or more (although most testing will take place lower than 70°C to avoid damaging the device). Thermocouples or sensors will give important data about the junction temperature of the machine as it is in operation within the system and instruments and sensors can be incorporated to see how the SSD reacts to external factors.
It is critical that thermal management is considered not only in the design phase, but that the products are tested to determine the impact of temperature on date storage to avoid errors, lost information and device failure. To make sure that the data is accurate and reliable and to save time and money in the long-run, it is imperative to use research-quality instruments during the test phase.
As an article from Qpedia Thermal eMagazine explained, “Small errors in temperature and air flow measurements can have a significant effect on reliability predictions. The origin of these errors lies in the measurement process or the use of inaccurate instruments.”
The article continued, “Accurate and high-quality instruments are not only essential for any engineering practice, their absence will adversely impact reliability predictions of a product at hand. No company wants to have its products returned, especially because of thermally induced failures.” [9]
The ATVS-2020™ Automatic Temperature & Velocity Scanner is a patented, multi-channel hot wire anemometer system for single or multi-point measuring of air temperature and velocity. (Advanced Thermal Solutions, Inc.)
Learn more about the instruments that ATS has to offer for SSD thermal characterization in the video below:
Thermal management innovations need to match the rapid pace at which the electronics industry is advancing. As consumers demand new and more powerful devices or greater amounts of information at faster speeds, cooling solutions of the past will not be enough. Today’s cooling solutions must be smaller, lighter, and offer higher performance, but also need to be cost-effective, meet demanding project specifications, and be reliable for many years.
Advanced Thermal Solutions, Inc. (ATS) understands the importance of creating cutting-edge thermal solutions for its customers and has geared its thermal design capability and its research and development to match the innovations taking place in electronics design.
An ATS engineer assembles a rig for testing cold plates in one of ATS’ six state-of-the-art labs. (Advanced Thermal Solutions, Inc.)
To meet the need for innovative solutions, ATS engineers are hard at work in the company’s six state-of-the-art laboratories at the ATS headquarters, located in Norwood, Mass. (south of Boston). Thermal issues of all kinds are recognized, broken down, and resolved and cooling solutions are designed, simulated, prototyped, and rigorously tested in these research-grade facilities.
When someone thinks of a research lab, the initial picture is scientists in white coats working for major corporations, such as IBM, Microsoft, or Google, but the development of new ideas is an essential tool for any company in the technology field. Working with empirical tests in a lab environment pushes concepts from the white board or the computer screen to reality. There comes a time when engineers need to produce tangible data to ensure that a design works as planned.
ATS thermal engineers are no different. They use state-of-the-art instruments and software in each of the six labs to conduct a long list of characterization, quality-assurance, and validation tests. In addition to finding custom cooling solutions for customers, ATS engineers produce thermal management products for commercial uses, including a variety of next generation heat sink, heat pipe, vapor chamber, and liquid cooling designs.
Engineers test ATS instruments using a wind tunnel and sensors in the Characterization Lab. (Advanced Thermal Solutions, Inc.)
Among the most common tests performed in the ATS labs are:
• Measurements of air velocity, direction, pressure and temperature;
• Characterization of heat sink designs, fans and cold plates
• Flow visualization of liquid and air flow
• Image visualization characterization using infrared and liquid crystal thermography.
Smoke flow visualization tests run in ATS wind tunnels demonstrate how air flows through a system. (Advanced Thermal Solutions, Inc.)
Heat pipes and vapor chambers are increasingly common cooling solutions, particularly for mobile devices and other consumer electronics, and ATS engineers are working to expand the company’s offerings for these solutions and to develop next generation technology that optimizes the thermal performance of these products. This research involves advanced materials, new fabrication methods, performance testing, and innovative designs that are ready for mass production.
ATS engineer Vineet Barot sets up a thermal imaging camera for temperature mapping studies in the lab. (Advanced Thermal Solutions. Inc.)
As liquid cooling technology has grown, ATS has met this demand with new instruments and lab capabilities, such as the iFLOW-200™, which measures a cold plate’s thermal and hydraulic characteristics, and full liquid loops to test ATS products under real-world conditions.
ATS engineer Reza Azizian (right) works with intern Vladislav Blyakhman on a liquid cooling loop in the lab. (Advanced Thermal Solutions, Inc.)
The labs at ATS are up to even the toughest electronics cooling challenges that the company’s global customers present. Thanks to its extensive lab facilities, ATS has provided thousands of satisfied customers with the state-of-the-art thermal solutions that they demand.
For more information about Advanced Thermal Solutions, Inc. (ATS) thermal management consulting and design services, visit www.qats.com/consulting or contact ATS at 781.769.2800 or ats-hq@qats.com.
ATS’s Candlestick Sensor measures both air velocity and air temperature in a single sensor. But what heights does it come in? Click our 10 second video to see!
ATS introduced it’s latest instrument, the FSC-200™, designed for controlling fan and fan tray speeds in a variety of applications where air flow control is critical for accurate thermal design. This 2 mintues video shows how the fan speed controller enables engineers to perform a variety of air flow tests during different product design and development stages, without the need to manipulate the fans power supply at the pre-specified ranges.
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