PCB Enclosure Design and Assembly Considerations
PCB enclosures protect your PCB assemblies in several ways. Expert PCB assembly services are essential to their proper function, and PCB assembly services may be able to improve the design.
PCB enclosures are routinely used in both commercial and military applications. PCB enclosures prevent theft of hardware and wiring. PCB enclosures shield printed circuit boards from weather, while offering significant electromagnetic inference prevention. PCB enclosures typically reduce radio frequency interference or RFI.
Enclosures need to be designed to allow access for maintenance and replacement of components, while preventing losses due to theft. Enclosures need to take up as little space as possible without causing the PCB assembly inside to overheat. The design of the enclosure must account for the location of board connectors and mounting holes, while providing enough room for alternative components that may have a different shape than the current components.
PCB assembly services ensure that the enclosure is well built. This is critical, since many PBC enclosures need to last for years. You could ask the PCB assembly service to improve the heat transfer of the enclosure by painting its inside with organic paints or anodizing it with aluminum. Black organic paint on the inside of the PCB enclosure will reduce internal temperatures by about ten percent. A large portion of the heat conducted by the PCB will be conducted to the back side of the PCB. Focus cooling air flow on that side of the PCB, or design the unit to maximize the air gap on the back side of the board. The top row of resistors tends to be about 10% hotter than resistors on the bottom row. If possible, increase the air gap around the top row of resistors, or increase the heat transfer in that portion of the board to prevent overheating.
PCB assembly services can often give advice on the design of the product, such as methods to cool the hardware using convection instead of relying on fans. Or they can assemble the components to ensure that there is adequate airflow through the gaps, instead of letting boards block air flow. Run thermal tests for the assembled printed circuit boards in the PCB enclosure to verify that they do not overheat and that coolant flows over all components. If you need to add forced air convection, the PCB enclosure may need to be modified with holes for the fan and air outlet. Forced convection of at least 150 linear feet per minute reduces the internal temperature by 5% to 10%. Expert PCB assembly services are essential when your PCB assembly must meet high performance criteria, survive in the field a long time or handle a heavy load. An expert PCB assembly service will build PCB assemblies that can handle shocks, temperature swings, humidity and exposure. No one wants to build a cell phone tower that will fail during a storm or the hottest day of the summer, when customer demands will be greatest. The best PCB assembly services will be able to build units that are both eco-friendly, using lead-free solder, and reliable, with well-made solder interconnects.
Expert PCB assembly services will not put mounting holes too close to printed circuit board's edge. Panel connectors should not be flush to the PCB. The PCB enclosure itself should have a minimum number of pieces. Most are designed around a plastic clam shell or metal box, but many PCB assembly services can modify these parts or create a custom PCB enclosure to meet your needs.