Category Archives: Guides

What are Stepper Motors Good For?

Stepper motors rotate in discrete steps. These are DC motors with multiple coils arranged in groups or phases. Energizing each phase sequentially enables the shaft of the motor to rotate in single steps. It is possible to achieve very fine positioning and speed control with a computer controlling the stepping. This allows use of stepper motors for several industrial applications involving precision motion control. As stepper motors come in various sizes, styles, and electrical characteristics, it is important to know the parameters that allow selecting the right motor for the job.

Stepper motors are good for three things—positioning, speed control, and generating low-speed torque. As they move in repeatable and precise steps, stepper motors are appropriate for applications requiring meticulous positioning such as in 3-D printers, XY plotters, CNC machines, and camera platforms. With their precise incremental movement, stepper motors allow excellent control of their rotational speed suitable for robotics and process automation. Where regular DC motors generate very little torque at low speeds, stepper motors are the opposite, generating their maximum torque at low speeds. This makes then the right choice for applications requiring high precision at low speeds.

It is also necessary to know the limitations of stepper motors—low efficiency, limited high-speed torque, and no feedback. Stepper motors are notoriously low efficiency devices, as their current consumption is independent of the load they are driving. Moreover, when it is stationary and not doing work, a stepper motor draws the maximum current. The low efficiency of these motors manifests itself in the high amount of heat they generate. Contrary to that of other motors, stepper motors exhibit lower torque at high speeds than they do at low speeds. Even for steppers optimized for better high-speed operation, achieving that requires them to be paired with appropriated drivers. Servomotors achieve their positions aided by integral feedback. However, steppers have no such provision, achieving high precision when running open loop. Limit switches or home detectors are necessary for safety and for achieving a reference position.

Selecting a stepper motor for a specific task requires considering three major characteristics—motor size, step count, and gearing. The general concept is larger motors will deliver higher power. Manufacturers specify motor power in torque ratings, and NEMA numbers to specify their frame sizes. To decide whether the motor has the strength to meet your requirement, look at its torque ratings. While NEMA 57 is a monster size, 3-D printers and CNC mills usually use a NEMA 17 size motor. The NEMA numbers also specify standardized faceplate dimensions for mounting the motor.

The step count defines the positioning resolution. A motor can have a specific number of steps per revolution, which usually ranges from 4-400. For instance, step counts commonly available are 24, 48, and 200. Resolution of a stepper motor is specified in degrees per step. For instance, a motor rotating 1.8 degrees per step is actually rotating at 200 steps per revolution. A higher resolution motor usually sacrifices speed and torque. Therefore, motors with high step counts have lower RPMs and lower torques than do similar sized but low-step-count motors running at similar speeds.

Working with Gas Sensors and the Raspberry Pi

Many devices predicted by earlier science fiction stories and movies have come true. Among them are gas detectors as envisaged by the TV series Star Trek. If you have a single board computer such as the Raspberry Pi (RBPi), you can use it to detect the type of gas and air quality around you. Of course, you will need to couple the RBPI with a gas sensor, and among the popular gas sensors available are the BME680 from Bosch, and the CCS811 from AMS.

Gas sensors are helpful in sniffing out volatile organic compounds, many of them not only poisonous but also flammable. Volatile organic compounds may be natural or manmade, including paints and coatings that require solvents to spread in a protective or decorative coating. Where earlier the paint and coating industry used toxic chemicals, they are now shifting towards aqueous solvents. Natural volatile organic compounds may come from direct use of fossil fuels such as gasoline or as indirect byproduct such as automobile exhaust gas.

Some volatile organic compounds may also be carcinogenic to humans. Among them are chemicals such as benzene, methylene chloride, perchloroethylene, MTBE, Formaldehyde, and more.

BME680

Bosch developed this tiny sensor BME680 specifically for applications involving mobiles and wearables that require low power consumption. This one sensor has high linearity, and measures temperature, humidity, pressure, and gas with high accuracy. This 8-pin LGA package is only 3 X 3 X 0.95 mm, and Bosch has optimized its power consumption based on the specific operating mode.

With high EMC robustness and long-term stability, the BME680 measures indoor air quality, while detecting a broad range of gases and volatile organic compounds. For instance, the BME680 can detect formaldehyde from paints, and other volatile organic compounds from paint strippers, lacquers, furnishings, cleaning supplies, glues, office equipment, alcohol, and adhesives.

Apart from applications for indoor air quality measurement, BME680 is also useful for applications such as personalized weather station, measuring skin moisture, detecting change in rooms, monitoring fitness, warning for dryness or high temperatures, measuring volume and air flow, altitude tracking, and more.

CCS811

Compared to the BME680, the CCS811 is only a digital gas sensor. It is meant for monitoring indoor air quality using a metal oxide gas sensor. The gas sensor can detect a wide range of volatile organic compounds. The CCS811 includes a micro-controller unit, an analog to digital converter, and an I2C interface.

With optimized low-power modes, AMS has designed the CCS811 for high volume and reliability. It has a tiny form-factor that saves more than 60% in PCB footprint, while producing stable and predictable behavior regardless of air quality at power up.

Similar to the BME680, the CCS811 also measures the total volatile organic compounds and the equivalent of calculated carbon di oxide. However, the consumption of CCS811 being about 60 mW, it may be necessary to have to supply it with an external supply of 3.3V.

Both sensors need the working I2C bus on the RBPi to interface and function. The software library for the two sensors are available here for the BME680 and here for the CCS811.

Facial and Object Recognition with A Raspberry Pi

f you are using the single board computer Raspberry Pi (RBPi) for vision-related tasks such as facial and object recognition, the NCS or Movidius Neural Compute Stick from Intel could help to boost the rate at which the RBPi carries out its tasks—you actually do not need to employ a server farm for the job.

The RBPi is fully capable of running software for facial image recognition, and hobbyists have long being using the SBC for recognizing faces in videos to identifying obstacles in the path of a robot. However, the rate at which the RBPi carries out such tasks leaves much to be desired, and the NCS helps to improve this rate.

The Movidius NCS from Intel plugs into the RBPi via the USB port. Inside the stick is a Myriad 2 Vision Processing Unit (VDU) with 12 specialized cores that accelerate the vision recognition tasks for the RBPi. Although it consumes only a single watt of power, the low-power VDU processor works at 100 gigaflops. Sometimes, the stick may need higher processing power and it could consume 2.5 W.

Users can watch the video Movidius has released for guidance on how to use the NCS. There is also a text guide to help users figure out the nuances of object recognition using the RBPi and the NCS. The video demonstrates the system recognizing a pair of sunglasses and a computer mouse on the table.

To get the demo running, the user needs to download and install a few software libraries. On the hardware side, apart from the RBPI, you also need a Pi camera.

Movidius initially announced the early version of the NCS in April last. They then released a prototype device, which they named Fathom, before Intel purchased Movidius. According to Dr. Yann LeCun, founding father of Convolutional Neural Networks, and director of AI research at Facebook, Fathom was a significant step forward.

Intel then released NCS, which has broadly the same specifications as the Fathom did, with the exception that the former has a 4 GB memory. This is an improvement of four times over that of the latter, and it helps the NCS to support denser neural networks. With NCS, any robot, big or small, can possess vision capabilities that are state-of-the-art.

According to Intel, the NCS can lower the barriers for those starting with deep learning application development. It actually offers a simple way for users to add a visual recognition system to their prototype devices such as robots, surveillance cameras, and drones.

As the NCS already has 4 GB of internal memory, and handles all the data in a neural network that is locally stored, the NCS does not have to rely on an Internet connection to connect to a server. In actual practice, transferring data to and from a remote server would introduce a huge latency and any high-performing processor to overcome the latency would consume a huge amount of power. The NCS overcomes both the above shortcomings.

The processor on the NCS is more powerful than the RBPi, although it does not actually accelerate the training process of a neural network, which is a computationally intensive process when carrying out vision recognition.

The OpenBCI Cyton Board

OpenBCI stands for Open Brain Computer Interface. According to OpenBCI, they prefer advancements in science to be made only through open forums with concerted efforts and sharing of knowledge by people having different backgrounds. OpenBCI claims to work towards harnessing the power of the open source movement for accelerating ethical innovations of technologies involving the human-computer interface.

OpenBCI offers high quality, but low-cost bio-sensing hardware for interfacing between the human brain and a computer. Their bio-sensing boards are Arduino compatible, providing high-resolution imaging for EEG, ECG, and EMG signals, while recording them. OpenBCI claims hobbyists, makers, and researchers in over 60 plus countries use their BCI devices to interface brain and computer. Applications of BCI devices include powering machines and mapping brain activity. Anyone interested in brain computer interfacing, neurofeedback, and bio sensing can purchase equipment such as electrodes, sensors, boards, and headsets from OpenBCI. The equipment is affordable and of high quality.

Even if you are only curious about brain computer interfacing, or a new entrant to this field, to start with you need a bio-sensing board from OpenBCI. Select from three types of boards on offer—the Cyton, the Cyton+ Daisy, and the Ganglion. The difference between these boards lies in the number of electrodes they can handle—additional channels allow greater spatial resolution for diversity in research.

The Ganglion board offers four channels, each sampling at the rate of 200 Hz. The Cyton board has eight channels with a sampling rate of 250 Hz each, while the Cyton+ Daisy allows 16 channels at sample rates of 125 Hz. As each channel allows plugging in only one electrode, larger the number of channels so many more electrodes you can use. A Bluetooth dongle compatible with the Ganglion board allows easy connection to a Windows or Linux computer. The Cyton board is directly compatible to Mac computers and a Bluetooth dongle is not necessary.

As the sample rate of the board connected via the Bluetooth dongle depends on the bandwidth of the dongle, for increased sample rates, OpenBCI recommends the use of their WiFi Shield, which transfers data over Wi-Fi and hence is faster than Bluetooth. Users can control the WiFi Shield through requests over HTTP, allowing sending JSON objects with data in nano volts.

Once you have the board, it is necessary to get a set of electrodes or a headset. As the boards come with male header connectors, electrodes with compatible female headers are necessary. For instance, for EMG or ECG, OpenBCI offers EMG/ECG Snap Electrode Cables with matching Solid Gel Foam Electrodes.

The user can plug in these electrodes directly to bio-sensing board and they are ready to use. Another set of electrodes from OpenBCI, the Gold Cup Electrodes, handles EEG signals that include the EMG and ECG. However, it needs the Ten 20 paste to operate. Attachment to the body is very simple, requiring affixing the electrodes with medical tape. Users can connect their own electrodes as well.

For attaching electrodes to the scalp easily and without using any paste, OpenBCI offers their Mark IV headset, which is a frame with dry electrodes. The headset allows easy monitoring of EEG signals from the brain.

What makes a Soldering Iron?

Solder, usually an alloy of lead and tin, has a low melting temperature. Placed between two metallic objects and heated, solder melts and wets the two metallic surfaces. On cooling, solder forms a bond between the two objects. Originally, a heated iron piece brought the solder to its melting point, hence the name soldering iron. Later, people found copper to be a better replacement for iron piece.

People working with electronic components are the biggest users of the soldering iron today. To suit their needs, the soldering iron has had to undergo several improvements. The latest models can be those of the uncontrolled type or ones where the user can set the temperature of the tip.

The simplest form of uncontrolled soldering iron has an insulated hollow handle that has an electric cable passing through. One end of the cable terminates in a resistive heating coil wrapped around an iron rod, but insulated from it by a layer of mica. A metal tube attached to the handle and insulated from the heater protects the user from the heating coil. At the front of the iron rod, there is a special copper tip that heats up when electricity is allowed to flow through the heating coil. When the tip is sufficiently hot, it is able to melt a solder.

There are several disadvantages of the uncontrolled soldering iron. The continuous heating of the tip causes a layer of oxides to form on it, reducing its ability to melt solder, unless the oxide layer is frequently scraped off. Solder reacts with the impurities in the copper tip and causes pits to appear on its surface. This requires occasional filing to keep the tip free of pits. Some components are temperature sensitive and can be damaged because the soldering iron tip touching them while soldering is much hotter than they can withstand.

The above disadvantages led to the development of temperature-controlled soldering irons, where a temperature feedback from the tip controlled the power fed into the heater, enabling the tip to remain at a certain temperature. By controlling the amount of feedback, the user now had the ability to allow the tip to become cooler or heat up further.

The tip too underwent a lot of change. Rather than use a copper piece throughout, the tip was made with multiple layers of different metals, such as iron, aluminum, and hardened copper. A soldering station helped to house the control electronics to set and adjust the tip temperature, as well as to detect when the iron was actually resting between two bouts of active soldering so the control electronics could reduce the tip temperature at times of rest. As soon as the user picked up the soldering iron, the control electronics pumped in more power input to bring the tip temperature quickly up to the set point.

Earlier, the control electronics for the soldering iron was predominantly analog. The latest models feature a digital control. Analog control was simple where the user could turn a knob to set the temperature. However, the digital ones have more features. Apart from a digital display showing the tip temperature in either Centigrade or Fahrenheit that the user can select, the soldering stations usually have a few preset selections.

What is the Automatic Test Equipment PCB?

Targeted towards verification of the functionality of a specific semiconductor chip, all major test activities use an automatic test equipment printed circuit board (ATE PCB) or simply a test board. Testing semiconductor chips with advanced functionality is necessary for manufacturers to ensure their reliability and functionality to OEM customers, and establish they operate according to their specifications.

In simple terms, the ATE PCB serves as an interface between the specific semiconductor chip and a large test system. The design and assembly of ATE PCBs allows testing an array of a large variety of semiconductor chips that includes field-programmable arrays, system-on-a-chip, memory chips, microprocessors, micro-controllers, and many more. As semiconductor chips are complex, the design and assembly of one ATE PCB makes it capable of testing only one particular type of chip set at a time.

Chipmakers employ a group of experienced project and program managers, along with highly trained engineering personnel for designing and assembling ATE PCBs to achieve the unique chip-testing quality. For this, conventional PCB assembly knowledge and experience is not adequate, and requires enhanced assembly line technical expertise along with highly disciplined administration management. Any misstep towards a successful completion of an ATE PCB can result in considerable loss of time-to-market along with a huge monetary loss.

Compared to conventional commercial and industrial PCBs, ATE PCBs are considerably different, and chipmakers usually differentiate them in three main ways—their larger size, number of layers, and the extra processes necessary. ATE PCBs are highly reliable and extremely robust, and their fabricators take special care to free them of assembly process residues and debris.

As the ATE PCB is so different, it is also difficult to make. This requires program managers associated with ATE PCB projects to have knowledge beyond that required for conventional PCBs, including all the nuances associated with ATE PCBs. They need to understand unconventional illustrations and diagrams, as these are the hallmark of projects involving ATE PCBs.

At the same time, technical personnel associated with the assembly of an ATE PCB need high-level knowledge and skill-set. This includes relevant hardware, tester orientation and configuration, stiffeners, cables, and other paraphernalia related to the ATE PCB. Both the assembly engineers and program managers must thoroughly understand the electronic format input required for designing a custom ATE PCB.

Unlike the netlist format conventional PCBs use, the input for ATE PCBs is usually in the form of map drawings, bitmaps, and ball maps. That means assembly engineers and program managers must be fully capable of creating the appropriate netlist after translating the original data from these unconventional methodologies.

As the ATE PCBs are large, typically measuring 12 x 10 inches or 14 x 14 inches, the pick-and-place systems for assembling these PCBs are also unlike those for populating conventional PCBs. They are capable of handling and populating large footprint boards, such as 20 x 24 inches to 26 x 30 inches.

These pick-and-place machines are extremely precise and highly accurate. Some of the latest machines can easily populate a board with 32 thousand components per hour at 21-µm fine-pitch repeatability. Such advanced machines also have the capability of selective or spot soldering.

Raspberry Pi Control for Pool Temperature and Motor

Owners of swimming pools often have no idea of the temperature of the water in the pool relative to the surrounding air. They also are unable to control the pump schedules unless they put up a mains timer. However, using a single board computer such as the Raspberry Pi (RBPi) makes it easy to display the temperature on a webpage, while it switches the pump automatically on or off based on a preset schedule.

The pool monitoring system does not need a full version of the RBPi, as the RBPiZW, the Zero W version, will be adequate. For instance, the designer, Matt, designed the pool monitoring system for his summer escapes pool that holds 4100 liters of water. Matt designed the RBPiZW system to measure the water and air temperature and log the measurements to a cloud on the Internet. This allows the system to display temperatures on a web page he is able to access from a mobile phone, while allowing him to switch the pump on or off. The system can also place the pump on an automatic mode to follow a specific schedule.

Pool pumps are usually mains powered and contain a filter. Traditionally, users control this with a mains timer, but that precludes the possibility of switching it on when the solar panel supplies free power. For instance, the user may want to replenish the water at the end of the day after heavy use, and this is not possible without tinkering with the timer unit.

Matt housed his RBPiZW monitoring system in a weatherproof box. It offered room to include a 4-way extension block and has a 10 m mains cable running to it from the house. The box houses the RBPiZW and its 5 V power supply. The sensor wiring enters the box through rubberized slots.

According to Matt, the finished system comprises, apart from the pool and pump, a weather-proof box, a 10 m mains extension cable, an RBPiZW, a 5 V charger, a 4-GB micro SD card, two water-proof temperature sensors (DS18B20) each with 3 m cable, bias resistor for the temperature sensors, an Energenie Socket, and an Energenie Pi-mote as add-on.

The Energenie socket is a remote control socket. Additionally, when combined with the Pi-mote, it allows controlling the socket with Python scripts. Being easy to set up, this combination offered an easy hardware for controlling the pump. Matt had only to plug in the Pi-mote into the GPIO header of the RBPiZW.

The DS18B20 waterproof temperature sensors are single-wire interface and many of them can be connected to the GPIO pins. The waterproof sensors come with all cables attached. Although somewhat more expensive than the regular standard sensors, Matt only needed to solder the three wires from each sensor to the appropriate GPIP pins on the back of the Pi-mote to make them work.

Matt placed one of the sensors in a hedge near the pool for measuring the air temperature, while he dipped the other into the pool water to measure the temperature of the water. Each sensor has a 3 m cable length.

Advanced PCB Technologies — High Density Interconnect

Engineers often face a peculiar dilemma. On one hand, they need to enhance the functionalities of electronic gadgets they design so that customers have more value for their money, while they are constrained to use a sleek form factor. Not only does this impose a tremendous challenge to cram many components within a highly restricted space, but the challenge extends to maintaining the quality and integrity of the design as well.

Designers meet the challenge in different ways. They use subminiature passive SMD components, often as small as 0402 (0.4×0.2 mm), special fine pitch ICs in packages such as CSP, TQFP, and BGA, and advanced printed circuit technologies that offer thin flexible, multilayer boards, especially the high density interconnect (HDI) types.

Designers use several advanced technologies in producing HDI boards. For instance, rather than using glass fibers for producing the base substrate, HDI boards use Polyimide and similar materials, as these are flexible, more durable, and can withstand very high temperatures without degenerating.

Designers use special plated through vias to interconnect different layers in a multilayer HDI board. Rather than drill holes in the PCB layers using metal drills, fabricators of HDI PCBs use lasers to drill extremely small microvia holes in the layer, which they later electroplate with copper. Since these microvias can be as small as 15-30 µm, they take up very little space on the PCB, leaving a large area for routing the traces.

Designers use traces with width as small as 20 µm to route the circuits on HDI PCBs. In combination with microvias, these thin traces allow them to achieve extremely high routing densities impossible to achieve on regular boards. This is especially helpful when designing with fine pitch ICs and high pin count BGA IC packages that have a pitch as small as 0.5 mm.

BGAs are surface mounting packages with solder ball arrays on their bottom surface. Large BGAs may have as many as 560 solder balls. With pitch size as small as 0.5 mm, it is nearly impossible for designers to run traces from each pad under the BGA. However, engineers have solved this problem in a rather unique way.

In regular PCB design, using vias within pads is taboo, as this causes dry solders. The plated through via wicks away molten solder, leaving very little solder between the pad and the IC pin. However, designers regularly use via-in-pads in HDI PCBs, as this allows them to save a lot of space that they can use for routing. Molten solder does not travel down the microvia in HDI PCBs, as fabricators fill them up and plate them over. This has another advantage, as filled vias become better conductors of heat.

Another trick a designer often uses for gaining higher routing density in HDI PCBs is placing different types of vias such as blind and buried types. Vias connecting inner layers in a multilayer PCB are buried vias, while those originating on one of the outermost layers and connecting to one of more inner layers are blind vias. Unlike a through via that passes straight through the board, designers can stagger blind and buried vias in different layers to achieve higher routing density.

How mSAP Enhances HDI PCB Capabilities

With 5G technology around the corner, we are looking at the emergence of 5G smartphones. While this requires new manufacturing technologies such as high-density interconnect Printed Circuit Boards (HDI PCB), smartphones need to be less expensive and produced at greater efficiencies.

Customers usually covet compact sleek devices. Therefore, manufacturers need to balance function and form so that their products stand out in a crowd in a competitive marketplace. The smartphone market can be a treacherous place with corporate fortunes rising and falling on the success and failures of specific generations of phones.

Smartphone designers tend to use every millimeter of space within the device enclosure to unlock significant value for the user. This is how they are able to fit in large and high-resolution displays, large batteries, and more sophisticated processors. This allows designers offer more functionality with an enhanced feature set, ultimately improving the overall user experience.

As most of the design of a smartphone is form-factor driven, PCBs in the form of high density interconnects are the major contributors. These HDI PCBs are specially designed circuits differing from conventional PCBs as they provide the designer with more functions per unit area. Their main advantage is finer copper traces, thinner and more flexible base material and laser drilled via holes. Although HDI PCBs have played a crucial role in creating miniature smartphones and other embedded subsystems, 5G technology demands are more severe.

The new generation smartphones compatible to 5G requires extremely complex RF front ends and antenna configurations involving multiple inputs and multiple outputs—generally known as massive-MIMO. This not only expands the footprint of the RF content within the phone, but also enhances the processing power necessary to control the staggering volume of 5G data. Simultaneously, all the extra features and functionality affects the battery capacity, and hence, the geometry of the phone. Conversely, if the phone geometry is not to increase drastically, the 5G smartphone will have much less space for the HDI PCB inside.

With the reduction in internal space for the PCB, and use of higher 5G frequencies, designers will need to exercise much stricter control on the impedance of traces. Unless they design with extreme precision, the thin traces in HDI PCBs can increase the risk of signal degradation resulting in lapses of data integrity.

PCB designers and fabricators are overcoming these challenges by following the mSAP process. Fabricators of IC substrates generally use this semi-additive process, and HDI PCB fabricators have adopted its modified version.

Typical line to space ratios on the HDI PCBs are 30:30, meaning designers plan for a spacing of 30 µm between adjacent traces of 30 µm width each. Demands of increasing density are forcing fabricators towards line-space ratios of 25:25 and even 20:20, with the help of mSAP. This enables makers of 5G smartphones and other demanding gadgets to achieve unprecedented densities while offering superior geometries with exacting impedance control for their high frequency operation.

Contrary to the subtractive processes used for normal PCB etching, mSAP does the reverse, essentially coating a thin copper trace onto the laminate and subsequently building up its thickness by electroplating over it.

What Are Thermoelectric Modules?

Discovery of the Peltier effect in 1834 led to the development of solid-state heat pumps, but the devices became commercially available only in the 1960s, when the combination of ceramic substrates with advanced semiconductor thermocouple materials made it possible. Solid-state heat pumps or thermoelectric modules utilize the Peltier effect to dissipate heat through a heat exchanger.

While operating, DC current flowing through the thermoelectric module creates heat transfer and a temperature differential across the ceramic surfaces. This causes one side of the thermoelectric module to be hot, while the other side grows cold. Although single-stage standard thermoelectric module can achieve temperature differentials up to 70°C, modern semiconductor materials can exceed this limitation.

Regular cooling technologies such as fans have moving parts that can wear out and need maintenance. However, thermoelectric modules, being solid-state with no moving parts, are highly reliable. While single thermoelectric modules can cool devices well below the ambient temperature, use of multistage thermoelectric modules in a vacuum environment can achieve colder temperatures, down to -100°C.

Simply reversing the polarity of the current flowing through a thermoelectric module can reverse its ability to heat and cool, as the reversal of current direction also changes the direction of heat transfer. This allows achievement of a very precise temperature control under steady state conditions—to the order of ±0.01°C. While heating, thermoelectric modules are much more efficient as compared to conventional resistance heaters, as they can generate heat from two sources—one, the input power supplied, and two, the additional heat generated by the heat pumping action.

A typical thermoelectric module physically measures 30X30X3.6 mm. However, they can have geometric footprints as small as 2X2 mm or as large as 62X62 mm, while being very lightweight. Therefore, thermoelectric modules are well suited for applications with space or weight constraints as compared to much larger cooling technologies offered by conventional compressor-based systems. Some applications also use thermoelectric modules as small power generating sources, converting waste heat into energy in remote locations.

Thermoelectric modules are well suited for applications where active cooling is required for reaching temperatures below ambient with cooling capacity requirements up to 600 W. Design engineers consider using thermoelectric modules when faced with system design criteria such as high reliability, precise temperature control, low weight, compact geometrical constraints, and other environmental requirements. Thermoelectric modules are in use in industries such as food and beverage, consumer, telecom, medical, photonics and many more.

Manufacturers offer several types of thermoelectric modules suitable for different applications. For instance, some have a wide breadth suitable for higher current and higher heat pumping applications and operating temperatures of 80°C. Other modules have several surface finish options such as pre-tinning or metallization to allow soldering the thermoelectric module to the mating conduction surfaces.

For achieving higher temperature differentials, designers stack thermoelectric modules one on top of another to create a multistage module. However, these multistage modules are suitable only for lower heat pumping applications.

Manufacturers design special modules that will work in both heating and cooling modes reversibly. Standard modules are not suitable here as they will be unable to withstand the thermal stresses these applications generate.