Author Archives: Andi

What are Tactile Switches?

Tactile switches are electromechanical switches that make or break an electrical circuit with the help of manual actuation. In the 1980s, tactile switches were screen-printed or membrane switches that keypads and keyboards used extensively. Later versions offered switches with metal domes for improved feedback, enhanced longevity, and robust actuation. Today, a wide range of commercial and consumer applications use tactile switches extensively.

The presence of the metal dome in tactile switches provides a perceptible click sound, also known as a haptic bump, with the application of pressure. This is an indication that the switch has operated successfully. As tactile switches are momentary action devices, removal of the applied pressure releases the switch immediately, causing the current flow to be cut off.

Although most tactile switches are available as normally open devices, there are normally closed versions also in the market. In the latter model, the application of pressure causes the current flow to turn off and the release of pressure allows the current flow to resume.

Mixing up the names and functions of tactile and pushbutton switches is quite common, as their operation is somewhat similar. However, pushbutton switches have the traditional switch contact mechanism inside, whereas tactile switches use the membrane switch type contacts.

Their construction makes most pushbutton switches operate in momentary action. On the other hand, all tactile switches are momentary, much smaller than pushbutton switches, and generally offer lower voltage and current ratings. Compared to pushbutton switches, the haptic or audible feedback of tactile switches is another key differentiator from pushbutton switches. While it is possible to have pushbutton switches in PCB or panel mounting styles, the design of tactile switches allows only direct PCB mounting.

Comparing the construction of tactile switches with those of other mechanical switches shows a key area of difference, leading to the tactile switches being simple and robust. This difference is in the limited number of internal components that allows a tactile switch to achieve its intended function. In fact, a typical tactile switch has only four parts.

A molded resin base holds the terminals and contacts for connecting the switch to the printed circuit board.

A metallic contact dome with an arched shape fits into the base. It reverses its shape with the application of pressure and returns to its arched shape with the removal of pressure. This flexing process causes the audible sound or haptic click. At the same time, the dome also connects two fixed contacts in the base for the completion of the circuit. On removal of the force, the contact dome springs back to its original shape, thereby disconnecting the contacts. As the material for both the contacts and the dome are metal, they determine the haptic feel and the sound the switch makes.

A plunger directly above the metallic contact dome is the component the user presses to flex the dome and activate the switch. The plunger is either flat or a raised part.

The top cover, above the plunger, protects the switch’s internal mechanism from dust and water ingress. Depending on the intended function, the top cover can be metallic or other material. It also protects the switch from static discharge.

Proximity Sensor Technology

Proximity sensor technologies vary with operating standards, strengths, and determining detection, proximity, or distance. There are four major options for compact proximity sensors useful in fixed embedded systems. It is necessary to understand the basic principles of operation of these four types for determining which to select.

Most proximity sensors offer an accurate means of detecting the presence of an object and its distance, without requiring physical contact. Typically, the sensor sends out an electromagnetic field, a beam of light, or ultrasonic sound waves that pass through or reflect off an object, before returning to the sensor. Compared with conventional limit switches, proximity sensors have the significant benefit of being more durable and, hence, last longer than their mechanical counterparts.

Reviewing the performance of a proximity sensor technology for a specific application requires considering the cost, size, range, latency, refresh rate, and material effect.

Ultrasonic

Ultrasonic proximity sensors emit a chirp or pulse of sound with a frequency beyond the usual hearing range of the human ear. The length of time the chirp takes to bounce off an object and return determines not only the presence of the object but also its distance from the sensor. The proximity sensor holds a transmitter and a receiver in a single package, with the device using the principles of echolocation to function.

Photoelectric

Photoelectric sensors are a practical option for detecting the presence or absence of an object. Typically, infrared-based, their applications include garage door sensing, counting occupancy in stores, and a wide range of industrial requirements.

Implementing photoelectric sensors can be through-beam or retro-reflective methods. The through-beam method places the emitter on one side of the object, with the detector on the opposite side. As long as the beam remains unbroken, there is no object present. An interruption of the beam indicates the presence of the object.

The retro-reflective method requires the emitter and the detector to be on the same side of the object. It also requires the presence of a reflector on the other side of the object. As long as the beam of light returns unimpeded, there is no object detected. The breaking of the beam indicates the presence of an object. Unfortunately, it is not possible to measure distances.

Laser Rangefinders

Although expensive, these are highly accurate, and work on the same principle as that of ultrasonic sensors, but using a laser beam rather than a sound wave.

Lasers require lots of power to operate, making laser rangefinders non-suitable for portable applications or battery operations. Being high-power devices, they can be unsafe for ocular health. Although their field of view can be fairly narrow, lasers do not work well with glass or water. 

Inductive

Inductive proximity sensors work only with metallic objects, as they use a magnetic field to detect them. They perform better with ferrous materials, typically steel and iron. A cost-effective solution over a huge range, the limited use of inductive proximity sensors to detect objects reduces their usefulness. Moreover, inductive proximity sensors can be susceptible to a wide range of external interference sources.

What is Tactile Sensing Technology?

Scientists have been exploring the field of soft robotics for use in healthcare systems. They aim to emulate the sense of touch. However, they have not had much success with tactile-sensing technology while fine-tuning dexterity.

In an experimental study, published in the Journal of the Royal Society Interface, scientists made a comparison of the performance of an artificial fingertip with that of neural recordings made from the human sense of touch. The study also describes an artificial biometric tactile sensor, the TacTip, which the scientists had created. According to the study, TacTip offers artificial analogs of the dynamics of the human skin and the nerves that pass information from skin receptors to the central nervous system. In simple words, TacTip is an artificial fingertip that mimics nerve signals on human fingertips.

The researchers created the artificial sense of touch. They used papillae mesh that they 3-D printed and placed on the underside of the compliant skin. This construction is similar to the dermal-epidermal interface on real skin and is backed by a mesh of dermal papillae and biometric intermediate ridges, along with inner pins that are tipped with markers.

They constructed the papillae on advanced 3-D printers. The printers mixed soft and hard materials, thereby emulating textures and effects found in real human fingertips. They actually reconstructed the complex internal structure of the human skin and the way it provides for the sense of touch in human hands.

The scientists described the effort as an exciting development in soft robotics. They claim that 3-D printing tactile skin would lead to more dexterous robots. They also claim that their efforts could significantly improve the performance of prosthetic hands by imbibing them with an in-built sense of touch.

The scientists produced artificial nerve signals from the 3-D printed tactile fingertips. These signals look very similar to the recordings from actual, tactile neurons. According to scientists, human fingers have several nerve endings known as mechanoreceptors that transmit signals through human tactile nerves. The mechanoreceptors can signal the shape and pressure of contact. Earlier, others had mapped electrical signals from these nerves. By comparing the output from their 3-D printed artificial fingertip, the scientists found a startlingly close match to the earlier neural data.

A cut-through section of the 3-D printed tactile skin shows a white plastic that forms the rigid mount for the flexible black rubber skin. Scientists made both parts on advanced 3-D printers. The inside of the skin has dermal papillae, just as the real human skin also has.

In comparing the artificial nerve recordings from the 3-D printed fingertip with the 40-year-old real recordings, the scientists were pleasantly surprised. The complex recordings had many dips and hills over ridges and edges, and the artificial tactile data also showed the same pattern.

However, the researchers feel that the artificial skin still needs more refinement, especially in the sensitivity area pertaining to fine detail. As such, the artificial skin is much thicker than the real skin is. Scientists are now exploring different means of printing 3-D skins that mimic the scale of human skin.

Comparing Polyimide Flex Heaters and Silicone Rubber Heaters

Commercial, industrial, military, and aerospace applications use flexible heaters to deliver particular amounts of heat to specific places. The heaters serve multiple purposes, starting from warming food in cafeterias, drying the condensation on aerospace control panels, to controlling temperatures in medical equipment.

These tiny heaters are unique in the sense they are flexible. It is possible to bend them without compromising their heating operations. As flex heaters are very thin, they can squeeze into inter-component space without dislodging. However, the types of materials that make up these heaters impose certain limitations. These are temperature limitations, and the limitation on how much they can bend. Understanding these limitations is necessary for creating designs suitable for the application.

Flexible heaters are typically made from two types of materials—Polyimide and silicone rubber. The thickness of the materials used defines the amount the heater can safely bend without damage. Polyimide flex heaters with etched foil heating elements can be as thin as 0.0007 inches. This thickness allows Polyimide flex heaters to bend around multiple curves within the application.

In contrast, silicone rubber flexible heaters, with etched foil elements, can only go down to a thickness of 0.03 inches. Those with wire-wound elements can at best be 0.056 inches thin. Therefore, although the heater with etched foil elements can have a bend limitation of 1.5 inches, those with the wire-wound elements can bend still less.

Therefore, applications with curved and bent surfaces prefer using Polyimide flex heaters, and those with flat surfaces can do with either Polyimide or silicone rubber.

The range of temperatures offered by a flexible heater depends on the elements and the types of materials it uses. The application defines the temperature desired from the flex heater, depending on the ability of the system to remove the heat and disperse it away from the heater. The heat transfer is important to prevent the heater from overheating and malfunctioning.

Silicone heaters have an operating range of -70 °F (-56.66 °C) to +400 °F (204.44 °C). This makes them ideal for medium to higher temperature applications. However, they tend to fail if the environment cools below the minimum temperature.

On the other hand, Polyimide flex heaters can operate between -320 °F (-195.55 °C) and +392 °F (+200 °C). This makes Polyimide flex heaters suitable for applications working in very low temperatures, such as in spacecraft and satellites. They can help keep electronics functioning in such low temperatures.

Apart from the outer silicone rubber or the Polyimide covering, there are other structures also that add to the overall thickness. These are the solder tabs, wire connections, and other electronics that must connect to the heater.

Both silicone and Polyimide flex heaters with etched foil elements can have a maximum size of 10 X 70 inches. Their size cannot be larger as the heat produced will not be uniform. On the other hand, wire-wound elements can be as big as 36 X 144 inches. However, the wire-wound elements are strictly for silicone heaters, and suitable for large applications.

MEMS Pressure Sensors in Industrial Applications

A wide range of industrial applications requires the usage of pressure sensors. Continuous improvements in these sensors are necessary for new applications, including their use in more common applications like measuring fluid and steam pressure.

Recent power sensor technologies have made available devices with reduced size, better economics, more integration capabilities, and wider operating supply voltages, enabling OEMs to deploy sensors for applications like the Internet of Things. Additionally, with these sensors, it is possible to create products that are not only more sustainable but also feature additional embedded innovative features and less power consumption.

Along with a focus on applications, these sensors demonstrate a variety of methods and techniques for detecting pressure in industrial settings. Most notable among these are the MEMS or micro-electric-mechanical sensor technology.

Pressure is the force on a surface with a given surface area. Commonly, units for pressure measurement include the Bar, Pascal, and PSI or pounds per square inch. The sensor for a specific application typically defines the units it uses. For instance, it is customary to use bars or millibars to indicate pressure value in water-level applications. The automobile industry uses PSI to indicate pressure, such as in tires.

While measuring vertical distance or altitude, barometric air pressure is a common indicator. The reference here is the air pressure at sea level, which is equivalent to 1013.25 Mb or millibar. As the altitude changes, so do the air pressure.

In industrial applications, pressure sensors are generally of three types. These are the gauge pressure, absolute pressure, and differential pressure sensors.

A gauge pressure sensor uses the atmospheric or ambient pressure as its reference. This is typically 1013.25 Mb or 14.7 PSI at sea level. If the measurement is above ambient, it represents positive pressure, while a measurement below ambient is negative pressure. These sensors are useful in applications that require pressure measurement over longer periods, with little or no calibration.

Absolute pressure sensors use vacuum as the reference, with the absolute pressure of a full vacuum being zero PSI. Most absolute pressure sensors detect pressure below the atmospheric pressure. Altimeters are absolute pressure sensors using gauge pressure sensors.

Differential pressure sensors use a second pressure as a reference. This second pressure may be higher or lower than the pressure under measurement, or the atmospheric pressure. Differential pressure sensors are useful for measuring flow rates.

Industrial applications for pressure sensors have now evolved to the level where most sensors are smaller, smarter, and more conscious of energy consumption.

The various types of pressure sensors in use in the industrial environment, and the progress of MEMS technology, has enabled the semiconductor industry to make pressure sensors economical in high volumes.

With embedded compensation, low power consumption, and small size, these MEMS pressure sensors come in robust packaging. This allows wider use of MEMS sensors in industrial environments than was possible before. Most modern industrial systems now use a mixture of sensor technologies that not only run more efficiently but also waste much less energy. MEMS technology is the one leading in sensor applications in most industrial settings.

Digital Planar Liquid Flow Sensor

The chemical industry often requires measuring liquid flow in fluidic manifold systems. These often involve high-volume applications but with severe space limitations. For such applications, Sensirion offers a digital planar liquid flow sensor, the LPG10-1000. The sensor uses a planar microfluidic glass substrate that has down-mounted fluidic ports. Measuring only 10 x 10 x 2.35 mm, the LPG10-1000 is a highly compact unit capable of being integrated into any fluidic manifold system.

The sensor combines a digital microsensor and a microfluidic chip to measure the liquid flowing inside the planar glass substrate. The presence of the digital microsensor chip ensures full signal processing functionality. Its digital output is linearized, temperature compensated, and fully calibrated.

LPG10-1000 from Sensirion is an intelligent sensor providing solutions for measuring flow rates from a few microliters per minute to about 1ml per minute. Sensirion has provided a special glass for the wetted material, and it ensures optimum compatibility with the pharmaceutical and biological processes. The low thermal mass of the sensor allows response times lower than 30 ms. The sensor has built-in features for detecting real-time failures like leaks, air bubbles, and clogging.

The Sensirion sensor LPG10-1000 offers several advantages for measuring liquid flow. Its tiny size makes it extremely convenient for integration, even in small spaces. The engineering simplicity of the sensor’s design offers excellent repeatability. The output signal is digital, linearized, and calibrated. Media compatibility is excellent, and chemical resistance is high.

Sensirion has used the media isolated sensing principle for its sensor, as there is no direct sensor contact with the fluid it is measuring. The glass they use is of the inert type, so it is bio-compatible with the chemical process. The sensor offers a digital I2C interface for electronic compatibility.

The LPG10-1000 sensor offers a full-scale flow rate of 1000 microliters, and a sensor output limit of 1500 microliters. The response time for detecting the flow is about 40 ms, with 120 ms from power-up. The operating range for the sensor covers +5 to +50 °C, while the specified temperature range for storage is -40 to +60 °C. The sensor can operate reliably in 0 to 95% humidity and non-condensing conditions. The recommended maximum operating pressure is under 3 bar or 43 psi, and the sensor can withstand a burst pressure of up to 7 bar or 101 psi.

For a full-scale 16-bit output, the digital sampling time of the sensor is 74 ms. However, for a 9-bit output, the sampling time can drop to as low as 1 ms. The sensor operates within a supply voltage range of +3.3 to +3.6 VDC, consuming less than 6 mA operating current.

The internal substrate channel glass material is borosilicate and has a down mount fluidic connection. The introduction of the sensor in a fluidic manifold system causes a pressure drop of only 0.1 millibars at full-scale flow rates. The total internal volume of the sensor is about 11.7 microliters. The cross-sectional flow channel of the sensor measures about 0.9 x 0.9 mm, and the total mass of the sensor is only 0.32 grams.

Cleaning Solar Panels without Water

Most installations of solar panels are in desert areas that provide plentiful amounts of sunshine. While the desert property is cheap, winds are also common. When the wind blows, it carries a huge amount of dust, which forms a layer on the solar panels. Dust on the solar panel reduces their performance, and the electrical output from the panel can reduce by about 30% with only a month of exposure to the elements.

For a 150 MW solar panel installation, even a 1% drop in the output could translate to a loss in yearly revenue to the tune of US$200,000. According to researchers, a reduction of 3 to 4% power output from solar plants all over the world could lead to an annual loss of nearly US$3.3 billion to US$5.5 billion. Therefore, it is essential to keep solar panels clean, and the most common technique presently is by using water.

However, keeping solar panels clean presently requires an annual supply of nearly 10 billion gallons of water. This is enough water necessary for a million people in developing countries. Cleaning solar panels without water is a labor-intensive task, and carries with it the high risk of scratching and damaging the surface of the panels, which also leads to a reduction in the efficiency of the cells.

MIT researchers have come up with an innovative method of cleaning the surface of solar panels. The method does not require the use of water, is contactless, and is automatic.

This innovative new method from MIT uses electrostatic repulsion. This makes the dust particles jump off the panels and does not require water or brushes. When activated, the system runs an electrode just above the surface of the panel. This results in the dust particles acquiring an electrical charge. The solar panels have a transparent conductive layer on top of their glass covering, and this is only a few nanometers thick. The system applies the same electric charge to this transparent conductive layer.

The same charge on the conductive layer and the dust particles makes them repel each other. As the conductive layer cannot move, the dust particles fall off the panel because of the repulsion. The researchers had to change the voltage until they found a range that overcame the adhesion forces and the pull of gravity and allowed the dust to lift away. They then automated the system using guide rails on the sides of the panel and an electric motor.

This is not the first time that engineers have tried to use an electrostatics-based approach to keeping solar panels clean. However, most approaches used electrodynamic screens and interdigitated electrodes. The problem with such screens is they allow ingress of moisture that can damage the electronics. If the atmosphere is dry, and moisture is not an issue, such as on the surface of Mars, the arrangement could be useful. However, on Earth, this can be a serious problem, because even the desert has ample amounts of moisture.

The researchers have found that as long as the humidity is more than 30%, dust removal was easy. However, the process of dust removal got increasingly more difficult with a decrease in humidity. 

High-Performance MEMS Microphone

With the increasing demand for high-quality microphones for consumer devices, the trend is toward MEMS-type microphones that offer high SNR or signal-to-noise ratio and low THD or total harmonic distortion. Apart from this, the microphones must also exhibit a wide dynamic range and a high AOP or acoustic overload point.

The MEMS microphone IM69D130, from Infineon, meets the above requirements superbly. Infineon has designed its microphone to provide low self-noise or high SNR of 69 dB(A), lower than 1% THD at 128 dBSPL, and an AOP of 130 dB SPL.

IM69D130 has a tight sensitivity of 36±1 dB and a phase tolerance of ±2°. With a low-frequency roll-off of 28Hz, the microphone offers a wide dynamic range of 105 dB. The current consumption of the microphone is only 980 µA, while in low-power mode, it consumes only 300 µA.

Infineon has used its patented Dual Backplate MEMS technology for making this microphone. This has given the IM69D130 microphone a miniaturized symmetrical design similar to that of studio condenser microphones. The design offers high linearity of signal output within a wide dynamic range of 105 dB. Even when the sound pressure levels reach 128 dB SPL, the microphone output has a distortion well below 1%. Infineon’s tight manufacturing tolerances result in a flat frequency response reaching as low as 28 Hz and a very close phase matching between microphones. This is a very important factor for applications using multi-microphone arrays.

The electronics associated with the microphone consist of an ASIC along with an amplifier featuring extremely low noise. There is also a high-performing sigma-delta ADC to convert the analog signal from the microphone to a digital signal. The user can select different power modes to suit specific requirements of current consumption.

Infineon trims each IMD69D130 microphone in production with IFX, their advanced calibration algorithm. This not only results in sensitivity tolerances as low as ±1 dB but also matches the phase response tightly to ±2° between microphones. This is very important for applications requiring beamforming support.

Infineon has designed their IMD69D130 microphones as extremely low-latency digital microphones. Their aim for these microphones is to use them in applications that require active noise cancellation, and where the microphone must process the audio data rather quickly.

The IMD69D130 microphones deliver the best-in-class group delay performances. This allows the benefits of digital microphones to system designs that had to rely on analog microphones up until now. The physical size of these microphones is only 4.00 x 3.00 x 1.20 mm.

There are some key benefits of using IMD69D130 microphones. They offer excellent far-field and soft audio signal pick-up. The output signal from these microphones is clear even when the sound pressure levels are very high. Moreover, these microphones enable the precise steering of audio beams for applications requiring advanced audio algorithms.

Typical applications of these digital MEMS microphones include systems with VUI or voice user interfaces such as IoT devices, home automation, and smart speaker systems. Headphones and earphones benefit from the excellent ANC or active noise cancellation offered by these microphones. Conference systems, camcorders, and cameras benefit from the high-quality audio these microphones capture.

MEMS Microphones for Laptops

In the recent pandemic, people took to virtual meetings using their computers and laptops. However, most often, the substandard quality of the audio led to an unsatisfactory experience. That’s because people’s expectation of consumer devices has increased significantly. They want to make high-quality calls from wherever they may be. They could be on the street, in an open office, or in a crowd.

People expect their devices to have ANC or active noise cancellation, transparent hearing, and voice control. However, these require more sophisticated and better microphones.

For instance, people engaged in video conferencing, want their experience to be as close as possible to a real, face-to-face meeting. Now this depends, to a great extent, on the audio quality, and people expect high-quality audio without having to put on additional devices, such as headphones.

Achieving good quality audio requires the application to use a combination of high-quality hardware and software. It is necessary to have algorithms that provide good noise reduction, reverberation reduction, enhanced beamforming, and good direction of arrival detection. These are essential for high-fidelity transmission and audio recording in a wide variety of conditions and situations. However, the quality of the entire chain is dependent on the primary sensor, the microphone.

Most good-quality microphones that have been around for a long time tend to be large and expensive, and primarily confined to audio recording studios. However, consumer equipment typically requires microphones that are mass-produced with tight manufacturing tolerances, and physically small. MEMS microphones suit these requirements very well.

For a microphone to be qualitatively described as good, it must possess some performance characteristics. The first among them is the SNR or signal-to-noise ratio. SNR of a microphone is the difference in its output between a standard reference signal input and the microphone’s self-noise. All elements of a microphone contribute to its self-noise. This includes the MEMS sensor, package, ASIC, and the sound ports.

SNR is important when the microphone is detecting sounds or voices that are at a distance from it. This is because the input signal decreases with distance, as sound level halves at twice the distance. Further, signal losses can come from the system design, room conditions, and sound channel. A good microphone with a large SNR can capture sound even at large distances. This helps with capturing input signals for algorithms, voice commands, and recording.

The next important characteristic of a good microphone is its THD or total harmonic distortion. This refers to the presence of harmonics in the microphone’s output that are not present in the input signal. The point where the THD reaches 10% is important as this represents AOP or acoustic overload point. At this point, the output from the microphone contains clipping and other noises, because the signal is too loud for the microphone.

The latest MEMS technology allows building of studio-level microphones for consumer devices like laptops. This has been aptly demonstrated by Infineon using their XENSIV IM69D127 and IM73A135 MEMS microphones that are allowing OEMs to build laptops with the next level of audio quality.

Heat Spreading for Thermal Management

Proper thermal management is necessary for ensuring the performance and reliability of electronic devices. Conceptually, this is simple, starting with the transferring of unwanted heat from the source to a larger area for effective cooling by dissipation. However, an implementation may be a difficult task.

Devices that generate heat generally have surfaces that are not large enough or smooth enough. Therefore, they cannot efficiently transfer heat as their thermal impedance is not adequately low. Some devices may not have a planar surface, thereby increasing the challenge of thermal management. Moreover, the challenge can increase with the position of the component to be cooled. If the location of the hot component is deep within the system, extracting the potentially damaging heat may become further complicated.

Many applications depend on thermal greases and pastes for improving thermal conductivity. However, this can be tricky, especially as the coverage may be insufficient, and over-application may result in spillage onto circuit board traces causing short circuits. Another limitation is thermal greases and pastes can only move the heat perpendicular to the surface, and not laterally from the source.

Therefore, designers are now replacing thermal greases and pastes with a variety of TIMs or Thermal Interface Materials. These include fillers and heat spreaders for providing low thermal impedance. This is necessary for the effective transfer of heat while removing any concerns about PCB surface contamination.

TIMs can also meet specific system needs, as their structural design can allow the transfer of heat perpendicularly or laterally. Moreover, TIMs are available in a variety of thicknesses. This enables designers to match them to the requirement of specific applications. They can provide good reliability as they are mechanically stable at elevated temperatures, and they provide high electrical isolation. Furthermore, they are easy to apply.

Placing TIMs between the source of heat and a cooling assembly helps to improve the heat flow through better thermal coupling. Here, two factors improve the efficiency of the thermal coupling. First, TIMs have the ability to conform to surface irregularities. This eliminates pockets of insulating air that actually reduce the thermal conductivity of the interface. Second, TIMs have a high thermal conductivity that is necessary to effectively move heat from the source to the cooling assembly.

Würth Electronik offers TIM (blue) for filling in microscopic irregularities. These irregularities exist on the surfaces of components and cooling assemblies, reducing thermal coupling.

Apart from thermal conductivity, there are other concerns for selecting a specific TIM. One of them is the operating temperature—TIMs are available for different temperature ranges. Another is the distance between the mating surfaces.

Other concerns are whether the TIM needs compression for delivering the optimal amount of thermal transfer and whether the TIM has the withstanding capability for the compression pressure it will face. Würth Electronik offers TIMs with adhesive on one surface that enables mechanical fixing. TIMs may also have to provide electrical isolation.

TIMs made of synthetic graphite offer very high thermal conductivity. The WE-TGS family from Würth Electronik is a synthetic graphite heat spreader. It measures 297 x 210 mm and has a thermal conductivity of 1800 W/mK.