A guide to LED mounting hardware
7.5 minutes | 29 Apr 2022
Circuit board light fixtures: Why LEDs?
LEDs (light emitting diodes) are the predominant choice for many lighting tasks. The popularity of this technology comes down to the benefits it offers:
- Low-power consumption
- Low-heat emission
- High-life expectancy
- Vibration resistance
- Colour tunability
- Compact size
How LEDs work
LEDs come in three colours: red, yellow, and blue. Other colours are generated by mixing the RGB LEDs. White is produced in most cases by using a blue LED, coated with a phosphor, similar to that used in fluorescent lamps. When the blue LED is energised, it "excites" the phosphorous coating to generate the white light. If you look into the lens of an LED flashlight, you can see the phosphorous coating.
These diodes have two leads, an anode (+) and a cathode (-):
- The leads connect to DC power supply
- You will see some domed LEDs that have more than one lead. These are actually two different colour LEDs in the same package
For example, a yellow and red LED or a yellow and blue LED may be contained in the same bulb. Each colour will have its own anode and share the cathode. Hence, the three leads. You may also see a four-lead LED lamp, containing all three colours.
LED hardware, explained
LED technology requires certain components to deliver the performance it’s become known for:
- LED light pipes:
Rods that transmit light from an LED to the application’s user interface. The closer the light pipes are to the LEDs, the more efficiently the light is carried. Provides Electrostatic Discharge (ESD) protection by isolating the PCB from potential contact.
- LED holders:
Also known as an LED cover. It holds the LED in place on the printed circuit board or panel.
- LED mounts:
Components that mount LEDs to PCBs and panels at either right angles or 90˚.
- LED spacers:
Raises the LED from the board surface and provides more stability, rigidity, and height conformity. These are also a type of LED mounts called a mount spacer, spacer mount and LED standoffs.
The rigidity and stability of mount and spacers are crucial during manufacturing and when the cabinet or device is open to service, troubleshoot, or repair the PCB or other internal components.
Types of LED Components
Below are examples of some of the components that LED systems need. Applications include:
- Car displays
- Electrical instruments
- Backlight displays
- Projection systems
- Street lighting
- Digital watches
LED light pipes
- Vertical, clear LED pipes
- Available in dome- or flat-head shapes
- Surface-mount LED compatible
- Polycarbonate (PC)
- Operating temperature range: -40˚C to 130˚C, UL94 V-0
Use for: Transporting light from an LED to desired location
- Transmits light at a 10˚ angle
- Available with or without a sealing o-ring
- Operating temperature range: -40˚C to 26.7˚C, UL94 V-0
Use for: Holding a standard through-hole T-1 3/4 LED in place in traffic lights
LED mount – square
- Secure mounting of both two- and three-lead devices
- Symmetrical design with feet on both sides eliminate need for specific side rotation
- Nylon 6/6
- Operating temperature range: -40˚C to 85˚C
- UL94 V-2
Use for: Protecting against heat, shock and vibration
LED mount – 90˚
- Mounted at a 90˚ angle as an LED plastic holder
- Mounted easily by hand
- Two styles accommodate both T-1 and T-1 3/4 LEDs
- Nylon 6/6
- Operating temperature range: -40˚C to 120˚C UL94 V-0
Use for: Mounting the LED parallel to the PCB surface
LED mounting clip & ring
- LED clips are inserted to the front of the panel, with the LED then assembled from rear of panel
- Ring is pressed onto rear of clip for a firm retention
- Two sizes for both a T-1 and T-1 3/4 LEDs
- Nylon 6/6
- Operating temperature range: -40˚C to 120˚C UL94 V-2
Used for: Securing LED bulbs
LED spacer – square
- Spaces LED from board surface
- Ensures product uniformity and production ease
- Square design is good for angled applications
- Two styles to fit both a T-1 and T-1 3/4 LED
- Operating temperature range: 0˚C to 90˚C UL94 V-0
Used for: Minimising shifting and height variation
LED spacers – round, metric
- Enables height control
- Available in three styles to accommodate both T-1 and T-1 3/4 LEDs
- Self-retaining feature for auto insertion and pre-assembly
- Operating temperature range: 0˚C to 50˚C UL94 V-0
Use for: Lead wire retention and stability
LED spacers – round, imperial, moulded
- Fits standard T-1 3/4 LED
- Minimises shifting and height variation
- Ensuring product uniformity and production ease
- Internal tapered dividers guide the lead wires
- Nylon 6/6
- Operating temperature range: -40˚C to 85˚C UL94 V-2
Use for: Preventing leads from shorting
Using leaded LEDs
It’s important to account for the number of leads when you choose LED spacers. Mounts will have holes or slots to pass the leads through before you solder LEDs to PCBs. The sizes of leaded LEDs, also called through-hole LEDs, vary but your LED spacer must have the appropriate number of holes to accept the number of leads attached.
This helps maintain through-hole LED polarity to eliminate short circuiting.
While the T-1 and T-1 3/4 round LED lamps can be soldered directly to the PCB, the lead arrangement leaves room for the lamp to move back and forth, potentially breaking the delicate leads. That's just one reason for using LED spacers and mounts.
Maintaining a consistent LED height can be crucial for many applications. It ensures that lumen output and colour rendering to the exterior of the device remain consistent. For example, you may have seen signage that uses LEDs to form static or moving patterns of text. To ensure that there are no dim or bright spots, LED spacers are used to keep the LEDs on the same horizontal plane.
When specifying spacers, you need to consider:
- Number of leads on the LED
- LED diameter, e.g., T-1 or T-1 3/4
- Distance required from the PCB surface
- And in some cases, whether the LED lamp is round, square, or rectangular
LED light mount options
Sometimes the LED is not mounted directly to a PCB. In fact, there are applications when the PCB is not accessible and longer, flexible leads must be attached between the LED driver and the LED lamp. For example, emergency lighting for fixtures and luminaires will have a charging indicator LED. This round surface mount LED light will protrude from the back plate or diffuser of the luminaire.
However, the driver and backup battery will be installed in the interior of the fixture, often in tandem with the lighting ballast.
To do that, the LED must be secured with an LED light holder to hold the lamp in place. Another LED lens holder allows the light to be observed from an angle. This is useful when the panel enclosure is mounted above eye level. This is accomplished by an internal bevelled lens that can be pointed in various directions.
As we’ve already shown you, some lamp mounting options include those that allow the lamp to be installed at a 90˚ angle. You can learn more in our LED light guide for product and panel building.
Download free CADs and try before you buy
Free CADs are available for most solutions, which you can download. You can also request free samples for most solutions to make sure you’ve chosen exactly what you need. If you’re not quite sure which LED components will work best for your application, our experts are always happy to advise you.
Whatever your requirements, you can depend on fast despatch. Request your free samples or download free CADs now.
Email us at firstname.lastname@example.org or speak to one of our experts for further information on the ideal solution for your application 0345 528 0474.