How do you design PCBs for extreme environments?

1 Choose the right materials

The first step in designing PCBs for extreme environments is to choose the right materials for your board and its layers. The materials should be able to withstand the expected temperature range, moisture level, mechanical stress, and chemical exposure of your application. For example, you may want to use high-temperature laminates, such as polyimide, instead of standard FR-4, if your PCB will operate above 150°C. You may also want to use thicker copper traces, vias, and pads, to reduce the risk of thermal expansion and contraction, which can cause cracks and breaks. Additionally, you may want to use gold or silver plating, instead of tin or lead, to prevent oxidation and corrosion.

2 Choose the right components

The next step in designing PCBs for extreme environments is to choose the right components for your circuit. The components should be rated for the expected temperature range, humidity level, vibration frequency, shock intensity, and radiation dose of your application. For example, you may want to use ceramic capacitors, instead of electrolytic ones, if your PCB will operate in high temperatures or high altitudes. You may also want to use surface-mount devices (SMDs), instead of through-hole ones, to reduce the risk of solder joint failure and board deformation. Additionally, you may want to use ruggedized or military-grade components, which are designed to meet higher standards of quality and durability.

3 Optimize the layout

The third step in designing PCBs for extreme environments is to optimize the layout of your board and its components. The layout should minimize the length and complexity of the traces, reduce the number and size of the holes, avoid sharp corners and angles, and maintain adequate spacing and clearance between the elements. These measures can help reduce the parasitic capacitance, inductance, and resistance of your circuit, as well as the noise and interference from external sources. They can also help improve the thermal management, mechanical stability, and electrical isolation of your PCB.

4 Add protection

The fourth step in designing PCBs for extreme environments is to add protection to your board and its components. The protection should shield your PCB from the environmental factors that can damage or degrade it, such as dust, moisture, chemicals, heat, cold, shock, vibration, and radiation. For example, you may want to use conformal coating, which is a thin layer of polymer that covers the entire board and its components, to prevent corrosion, short circuits, and electrical breakdown. You may also want to use potting or encapsulation, which is a thick layer of resin that fills the gaps and cavities of the board and its components, to provide mechanical strength, thermal dissipation, and vibration damping. Additionally, you may want to use shielding, which is a metal or composite layer that surrounds the board and its components, to block electromagnetic interference and radiation.

5 Test and validate

The final step in designing PCBs for extreme environments is to test and validate your board and its components. The testing and validation should simulate the actual environmental conditions that your PCB will face in your application, such as temperature, humidity, vibration, shock, corrosion, radiation, and electromagnetic interference. You should also test and validate your PCB for its functionality, performance, reliability, and lifespan, using appropriate instruments, methods, and standards. For example, you may want to use thermal cycling, which is a process of exposing your PCB to alternating high and low temperatures, to check for thermal stress and fatigue. You may also want to use HALT (highly accelerated life testing), which is a process of applying increasing levels of stress to your PCB, to identify its weak points and failure modes. Additionally, you may want to use HASS (highly accelerated stress screening), which is a process of applying a predefined level of stress to your PCB, to detect any defects or faults before deployment.

6 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?