Printed circuit boards, or PCBs, are an integral part of almost every type of electronic device. PCBs provide the electrical connections that make a device function, and they make it feasible to mass-produce complex electronics at a reasonable price point. Circuit boards have to be carefully designed and manufactured to ensure device functionality. However, there’s another factor that has to be considered: how to mount a PCB in an enclosure. A PCB must be held in place to keep it (and the components attached to it) safe and in the correct position in its electronics enclosure. There are three ways that printed circuit boards are typically mounted in a PCB enclosure: 
  • Standard mounting bosses
  • Custom mounting standoffs
  • Slide-in mounting rails
In this article, we’ll discuss each method of PCB mounting and how to apply them to your electronics device enclosures. We’ll also discuss the options that Polycase offers for each method of circuit board mounting and how they can help meet the needs of your electronics device application. 

1. Standard Mounting Bosses

Pre-formed mounting bosses are among the easiest and fastest ways to mount PCBs in an enclosure. Mounting bosses are molded protrusions from the inner surface of an enclosure that feature countersunk threading on the opposite side to allow screws to be inserted. Simply line up the holes on your PCB with the mounting bosses, insert your mounting boss screws and tighten the screws until secure. Many of Polycase’s electronics enclosures come with molded in PCB mounting bosses. Some models, like the Polycase JB Series, even include mounting bosses in both the top and bottom surfaces. Other Polycase PCB enclosure models with built-in mounting bosses include: Polycase ML Series, Polycase WC Series and Polycase BT Series. Make sure to pick up some of our PCB mounting boss screws, which are designed specifically to fit the countersunk holes in our built-in mounting bosses. Our mounting bosses are just ¼” tall, which gives them a low profile and helps keep them clear of device components. However, we can also machine down the height of the bosses using our custom CNC enclosure machining upon request. 

2. Custom Mounting Standoffs

Sometimes, you need to choose exactly where your mounting posts will go. For some enclosure buyers, this means purchasing enclosures with custom mounting bosses. However, this typically requires fully custom enclosure fabrication, which can raise your project costs substantially. Fortunately, there are more cost-effective alternatives available from Polycase. Polycase’s MB-01-20 Adhesive PCB Mounting Standoffs are an ideal cost-effective solution for adding custom mounting locations to your enclosure. These durable plastic standoffs are compatible with standard circuit boards. Simply insert them through your circuit board’s mounting holes and their flanged design keeps them locked in place without the need for screws. An adhesive pad on the base keeps the standoff tightly attached to the enclosure. In some cases, you may want to remove the existing mounting bosses from an enclosure and replace them with custom standoffs. Many of our enclosure models are available without mounting bosses—just ask a Polycase representative if an enclosure can be ordered without bosses. If this option isn’t available, we can also remove the bosses from most enclosures using CNC machining. Polycase electronics enclosure customized with MB-01-20 mounting standoffs
enclosure customized with MB-01-20 mounting standoffs

3. Slide-In Mounting Rails

Slide-in mounting rails are an easy and effective solution for mounting PCBs in an electronics enclosure. These rails are molded onto the interior body of the enclosure and designed to allow a circuit board to slide in. Mounting rails are simpler to use than mounting bosses, require no screws and are ideal for applications that require the mounting of multiple circuit boards. The Polycase EX Series is a perfect example of how smoothly PCB mounting rails can be integrated into an electronics enclosure. These extruded aluminum enclosures are manufactured from high-quality extruded aluminum and include PCB mounting rails molded directly into their structure. The EX Series’ mounting rails are designed to allow a standard 0.063” PCB to slide in easily, making them simple to use. These models also come equipped with multiple rails so you can choose the height at which you want to mount your circuit board. Once the circuit board is in place, the precision-molded rails hold it securely and reliably. Polycase EX-53 Extruded Aluminum Enclosure

Polycase EX-53 Extruded Aluminum Enclosure with PCB mounting rails visible

Need some in-depth advice on choosing an electronics enclosure or how to mount a PCB in an enclosure? Talk to Polycase’s enclosure experts today. Just call 1-800-248-1233 or contact us online at any time.
In Circuit Board Enclosures