A lot of thought goes into designing electronics, but the enclosure that houses the electronics is also critical for protective purposes. The enclosure must protect against the outside environment, preventing contamination from various sources (particulates, water, industrial chemicals, etc.) while offering a stable platform for mounting electronics (think vibration/shock resistance) or cooling elements. However, because the enclosure is closed off to the environment, heat exchange between the internal and external air is a primary concern. VSE’s best practices for PCB enclosure design guidelines ensure your system has the optimal protection and cooling necessary for performance.
PCB Enclosure Design Guidelines: Considerations
| Idealized | Constraints/requirements | |
| Size of components and devices | The enclosure provides ample space for components to prevent an excess concentration of heat |
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| Wire/cable spacing | Includes a wire harness and cable assembly for easier testing, troubleshooting, and assembly |
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| Heat dissipation | Preventing thermal buildup, especially in high-powered systems, extends service lives and limits unplanned maintenance |
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| Venting requirements | Ample venting provides a path for air circulation that encourages thermal dissipation and exchange |
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PCB Enclosure Design Guidelines
Broadly, PCB design enclosure guidelines depend on three practical aspects (size, materials, and thermal management) and a potential practical requirement (security/accessibility).
Size
Form follows function, and an enclosure requires adequate spacing for all its contents and interfacing equipment. Additionally, an overly dense enclosure design prevents adequate cooling by concentrating convection over a smaller area. To avoid under-sizing the enclosure, our engineers at VSE consider all the details of the system:
- As with circuit boards, VSE designs enclosures with all the wires, cables, PCBs (rigid, flex, rigid-flex), and other items that constitute the complete system build. This system layout includes critical features like mounting holes and cable I/O for external items like forced cooling.
- By determining the enclosure’s dimensions from the design, VSE can estimate thermal exchange rates using the exposed surface area. This estimation can decide the overall enclosure design, e.g., whether an enclosure is free-standing or adjoined with other enclosures.
The size of the enclosure will also impact or depend on its location and operations/maintenance. Different features, such as swing-out panels, barriers, mounting, and casters, may require greater enclosure dimensions than those of the internal design alone.
Materials
Materials offer differing thermal conductivity rates, weights, UV resistance, corrosion resistance, and other properties that may make them more (or less) suitable for specific applications and environments. There are four general categories of materials for most enclosures:
- Carbon steel – A cost-effective metallic enclosure that requires paint treatment to prevent corrosion. Its low carbon content also makes it ductile, meaning scratches/dents are more likely to occur with impact and require a protective paint layer reapplication to prevent corrosion. Operates as a moderately thermal conductive surface when painted.
- Stainless steel – Stainless steel offers greater corrosion resistance to various surfaces (brine, alkalis, acids, industrial solvents, etc.), but thermal conductivity is mild.
- Aluminum – Lightweight, highly thermally conductive, and economical aluminum enclosures are excellent for many harsh conditions.
- Plastics – A wide family of materials, but their general benefits are lightweight and ease of modification after installation (e.g., no sanding/finishing is necessary when making new holes or cutouts). Different materials offer varying impact ratings and corrosion resistance. In general, thermal conductivity is mild.
Cooling
While passive cooling design (materials, space within the enclosure, ventilation, etc.) is crucial for performance, many electronic systems require active cooling solutions during standard operation or elevated ambient temperatures. Forced cooling can rely solely on ambient temperatures (e.g., an enclosure installation inside a climate-controlled environment with low thermal dissipation requirements) or may necessitate a more pronounced closed system.
A closed system provides a thermal barrier (and protection from particulates) by separating the internal and external air: a heat exchanger absorbs and ejects the heat from the internal air to the external environment, accelerating the heat dissipation. Crucially, closed-loop systems provide cooling even when the ambient temperature is greater than the enclosure temperature, something that fans alone cannot provide.
Security/Accessibility
Depending on the criticality of the electronics housed within the enclosure, designers may want to limit access. Restricting accessibility to the enclosure may be to protect sensitive client information or prevent exposing operational electronics to the surrounding public. For low-risk enclosures, a simple screw cover or clamping door may be sufficient, but higher-risk installations can use a lock-and-key or padlocking to prevent tampering. Electrical locking mechanisms can provide additional security.
Your Contract Manufacturer for Turnkey Electronics Manufacturing
PCB enclosure design guidelines must balance thermal and environmental concerns for optimal performance, but VSE’s engineering team will ensure optimal performance regardless of application or environment. By partnering with a turnkey manufacturer like VSE, custom enclosure design is no longer an afterthought; how your design fits into its enclosure is a critical facet starting from design review.
By taking a comprehensive approach to manufacturing, VSE can accelerate production timelines and stay ahead of deadlines, even as designs evolve to meet end-user demands. Whatever your design for manufacturing (DFM) needs for electronics manufacturing, VSE is here to help you realize your life-saving and life-changing devices.
