Environmental knowledge is valuable across wide-ranging applications and has enabled the development of advanced systems. For example, a critical capability of driverless or autonomous vehicles (AVs) is to measure and analyze various characteristics of their surroundings. To accomplish this, devices such as proximity sensors that do not require physical contact are utilized. When measuring temperature, a proximity sensor for thermal analysis is employed.
Proximity Sensors for Thermal Analysis
Before delving into proximity sensors for thermal analysis, let’s review the advantages of proximity sensors in general and establish why they are preferred devices in a wide range of applications.
Attributes of proximity sensors
- Fast response
- Long operational lifecycle
- Unaffected by optical variations
As the list above shows, proximity sensors exhibit some of the most desirable characteristics for electronic components. As contactless devices, these sensors are less susceptible to physical degradation, which shortens the operational lifecycle. Accurately detecting the physical environment, along with local or remote elements, is essential for systems (including applications that protect personnel and/or equipment) that must respond to changes quickly.
One of the most useful applications of proximity sensors is temperature measurement. From thermal control systems aboard spacecraft that maintain ambient conditions to devices that detect fires and activate sprinkler systems, proximity sensors for thermal analysis are versatile components that can be connected to separate electrical circuitry or mounted on the board—as shown in the figure below.
Thermal sensor PCBAs
Thermal sensor PCBAs may be dedicated boards with custom layouts. The central component is typically a thermopile, as shown above. However, digital sensors that can integrate with more complex board constructions are also available. Regardless of the type of proximity sensor for thermal analysis you employ, there are best practices that should guide your design.
DFM for HDI Printed Circuit Boards
Thermal Sensor PCBA Design Tips
Many thermal sensors are deployed on boards where normal operating conditions (NOCs) typically fall within the operating range of the components. For example, 0°C to 70° is common for commercial electronics, as is -40°C to 85 (or 100) °C for industrial environments. Temperature ranges are often significantly wider for space and military applications, and failure modes can be catastrophic if these requirements are not met.
Thermal requirements should be considered for any board design. Neglecting these considerations may adversely affect the PCBA manufacturing process and/or cause component failure modes once deployed. Boards developed to operate in high heat environments or where wide temperature swings are common require additional considerations, which are not covered in this article.
For the best thermal sensor PCBA design, be sure to follow a set of proven guidelines.
Guidelines for Proximity Sensor for Thermal Analysis Board Design
- Include ample thermal relief
Many thermal sensors are similar to high-power ICs, as they can become very hot. Therefore, good thermal dissipation is required.
- Use components with good thermal resistivity
As proximity sensors for thermal analysis boards often are installed in high-temperature environments, you should ensure that other board elements have ample thermal resistance to avoid component failures.
- Choose materials with good thermal characteristics
Board material selection is often overlooked as an important design consideration. You should ensure that board thermal properties such as coefficient of thermal expansion (CTE), decomposition temperature (Td) and glass transition temperature (Tg) meet your design’s environmental requirements.
- Make EMI a priority
For digital thermal sensors, outputs are typically low-level signals. This means that minimizing EMI is critical for accuracy, and good semiconductor routing techniques should be applied.
- Utilize simulations to analyze thermal profiles
One of the most useful PCBA design package features when building boards where thermal considerations are a high priority is thermal simulation. These analyses can help you select components and materials, determine where and how to add thermal relief and decide on other important design choices.
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Following the guidelines above will aid you in designing the best thermal sensor boards for your application. However, it is important to consult with your CM for advice on specifications to optimize the board build process while maintaining design intent. At Tempo Automation, the industry leader for fast PCBA prototyping and on-demand production, we will work with you from Day 1 of design to ensure that your boards are built to meet all your requirements.
And to help you get started on the best path, we furnish information for your DFM checks and enable you to easily view and download DRC files. If you’re an Altium Designer or Cadence Allegro user, you can simply add these files to your PCB design software. For Mentor Pads or other design packages, we furnish DRC information in other CAD formats and Excel.
If you are ready to have your design manufactured, try our quote tool to upload your CAD and BOM files. If you want more information on designing proximity sensor for thermal analysis PCBAs, contact us.