Keep these 10 criteria in mind and choosing an electronic component enclosure will be easy!
Latest update time：2024-08-28
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Article Overview
This article introduces 10 important criteria to consider when selecting electronic component enclosures, including size, mounting environment, materials, electromagnetic compatibility, environmental sealing, hardware, appearance, availability of products and support, downloadable drawings and support materials, and customization options. These criteria help designers make informed decisions when selecting enclosures, ensuring that the enclosures meet application requirements while improving the overall quality and reliability of the product.
When starting a new project, there are many factors to consider, not the least of which is the enclosure that will house your components. The enclosure is the face of the product and the interface with it, so you want to ensure the quality of the enclosure fully meets the needs of the application.
Based on the experience of enclosure manufacturer
Hammond Manufacturing
, this article describes
10 common yet important criteria to keep in mind when selecting an enclosure.
1. Size
Ideally, the enclosure would be selected before the PCB is designed. This
ensures the correct dimensions for the board
and, if the enclosure has mounting posts, the correct placement of the mounting holes. Sometimes, however, the opposite is true, and the user must select the enclosure for their board.
How large is the PCB? Will it be mounted horizontally or vertically? Many plastic enclosures
have molded slots in the sides
for
direct vertical mounting or
molded mounting bosses on the top and bottom
for horizontal mounting. Extruded aluminum enclosures often have full-length slots in the sides for horizontal mounting of PCBs. Also, consider whether and how much space should be reserved on the exterior surface for indicators, switches, connectors, cable entries, and similar components. What is the height requirement for components mounted on the circuit board or for multiple horizontal circuit boards?
Figure 1: Hammond
1591T Series
Molded plastic housing with internal card guides. (Image source: Hammond Manufacturing)
Figure 2: Hammond
1455 Series
Extruded aluminum housing with a slot for a printed circuit board. (Image source: Hammond Manufacturing)
2. Installation Environment
Where will the product be used? Indoors, outdoors, or both?
When installed outdoors, UV stability is a potential issue for plastic housings, so polycarbonate is the default choice.
For mobile applications like road and rail, are shock and vibration issues a concern? Is there a risk of water or dust intrusion (see point 5 below)? Are contaminants like oil or chemicals likely to be present? Is impact damage a potential concern? Are extreme high or low temperatures expected?
ABS is ideal for indoor and handheld use.
Polycarbonate
offers excellent temperature resistance, UV stability, and impact resistance, making it an ideal material for outdoor and more industrial applications. Metals like die-cast aluminum offer excellent impact and temperature resistance.
Figure 3: Hammond
1554 Series
Polycarbonate housing with transparent cover. (Image source: Hammond Manufacturing)
3. Materials
For small enclosures, the choice is usually between plastics (including ABS and polycarbonate) and metals (including die-cast, folded, or extruded aluminum and steel).
Polycarbonate is often used exclusively for outdoor use because it doesn't become brittle or discolor as easily from sunlight as ABS.
Aluminum housings offer excellent impact resistance and are inherently conductive, but to maintain continuity across the entire housing, painted or anodized surfaces should not cover the mating area. Some extruded housings utilize specialized designs, such as multiple heat sinks, to increase surface area for improved heat dissipation.
Die-cast aluminum
housings offer robustness, corrosion resistance, electrical conductivity, inherently high electromagnetic attenuation, and ease of machining. Die-cast housings are an ideal, low-cost option for applications requiring excellent shock resistance, electromagnetic compatibility, or anticipated exposure to high temperatures, dust, or water.
4. EMC (Electromagnetic Compatibility)
Plastic enclosures have a particular drawback: their lack of EMC attenuation.
This lack of shielding can be problematic if EMI or RFI emissions from internal electronics, or if these electronics are susceptible to external electric fields, are a concern. To address this issue, the inner surface of the plastic enclosure can be coated with various materials to provide the appropriate degree of attenuation, depending on the project requirements. By applying varying thicknesses, the most cost-effective and technically appropriate solution can be achieved.
For metal enclosures, as long as electrical continuity is maintained between the top, bottom, and removable panels, their electromagnetic compatibility is sufficient for most commercial applications. The two halves of the enclosure will be electrically connected using conductive gaskets.
5. Environmental sealing
Will the enclosure be subject to environmental risks such as water or dust? The relevant international standard is
EN 60529
,
which specifies degrees of protection expressed as IPXX,
where the first digit defines the degree of protection against solid objects and the second against the intrusion of water.
Typically, enclosures with an IP54 rating are suitable for general use. For installation in environments where dust and water may be present, IP66, IP67, or IP68 ratings are typically achieved through the use of gaskets. The highest rating, IP69K, provides protection against high-pressure steam cleaning. In North America, the environmental sealing performance of an enclosure is often defined by the NEMA (National Electrical Manufacturers Association) rating. NEMA ratings also specify additional product features and tests not covered by the IP rating, such as functionality in icing conditions and cable connection holes.
Figure 4: Some enclosures, such as the 1551SNAP series
shown here, are designed for applications like environmental sensing and therefore allow for exposure to the elements.
(Image source: Hammond Manufacturing)
6. Hardware
Enclosure panels and covers must be secured to their mating parts. Plastic and die-cast enclosures employ two primary
methods for securing
these parts. They can either be secured directly to the base material using self-tapping screws, or machine screws can be used in conjunction with threaded inserts (or bushings) located in the base. Machine screws are preferred if the device will be opened and closed repeatedly throughout its life, while self-tapping screws are sufficient for "set-and-forget" applications.
Figure 5: Hammond
1591 Series
Economical plastic housing without brass insert (left) and flame-retardant plastic housing with brass insert (right). (Image source: Hammond Manufacturing)
7. Appearance
While aesthetics are certainly personal, users should at least have a general idea of the look and feel they want. Plastic enclosures are available in opaque and translucent materials, a variety of colors, and are lightweight. Many also feature snap-on covers for membrane keyboards and displays.
Extruded enclosures
feature a stylish anodized finish that can be paired with accessories like colored plastic bezels for a more distinctive look. Die-cast aluminum enclosures can be painted in a variety of colors, making them
a great choice for highly customized products like
guitar pedals
. Sometimes, a user just needs a rugged, unadorned die-cast enclosure!
Figure 6: Hammond's
1590 Series
"guitar pedal box" die-cast aluminum enclosure with a painted finish. (Image source: Hammond Manufacturing)
8. Product and Support Availability
Standard enclosures for the electronics and electrical industries are produced by numerous specialized manufacturers in a wide variety of sizes, styles, and types. While molded, extruded, or die-cast enclosures may appear to be simple boxes, they actually embody a wealth of design expertise, resulting in highly versatile enclosures suitable for a wide range of applications and environments. Distributors often carry a large inventory of standard enclosures, and
a recent trend is that distributors now work alongside manufacturers to provide technical support to customers, collaborating with them during the design phase to help select the most appropriate enclosure for their application.
9. Downloadable drawings and supporting materials
Any reputable enclosure manufacturer and distributor will provide a comprehensive library of technical information on their website.
Typical downloadable resources include dimensional drawings in PDF and CAD formats,
which can help with design and modification requirements, technical details, and key product attributes.
Figure
7
: All
Hammond
housings have downloadable dimensional drawings. (Image source:
Hammond Manufacturing
)
10. Customization
All enclosures require some form of modification before use
,
such as adding connector holes or printing labels and logos. Hammond offers in-house machining and printing services with low minimum order quantities. Customization options vary depending on the enclosure type. For example, we can install press-fit hardware (such as standoffs) in metal enclosures, customize the length of extruded aluminum enclosures, and customize the color of plastic enclosures. For more information on enclosure modifications, visit DigiKey's
Custom Enclosures
page.
Figure
8
:
1455
series extruded aluminum enclosures
are available with customizable color bezels, perforations, and printing
. (Image source:
Hammond Manufacturing
)
Conclusion
Not all of these tips will apply to every project, but using them will help designers gain a better understanding of the bigger picture—from understanding the short- and long-term usability of a specific enclosure to determining the perfect enclosure dimensions for the next project. Careful consideration of size and technical requirements, as well as feasibility and aesthetics, ensures that every project, from prototype to launch, runs as smoothly as possible.
Editor's words
Choosing an electronic component enclosure is a multifaceted decision-making process. By following the 10 criteria listed in this article, designers can systematically evaluate different enclosure options and find the best solution for their project. These criteria not only cover the physical properties and environmental suitability of the enclosure, but also consider product usability, aesthetics, and customization requirements, providing strong assurance for a smooth project. What are your main considerations when choosing a component enclosure? What questions and experiences have you had with enclosure selection?
Please leave a comment to share your thoughts!
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