A guide to PCB spacers
What is the purpose of spacers?
Types of PCB component spacers
How to choose spacers and pillars
What is the purpose of spacers?
Also known as screw spacers, spacer screws or bolt spacers, these are used to support and electrically connect and position components within PCB assemblies.
Spacers are typically small, hollow tubes positioned between the PCB and its surface. The purpose of the spacer’s hollow body is to enable a bolt or screw to pass through it. A spacer creates a clearance gap and will spin until the screw is tightened.
Spacers are a broad category. For instance, standoffs perform the same function as spacers – hence the name “standoff spacers.” But spacers and standoffs are different.
Standoffs are threaded while spacers are not. If you hear the term “threaded spacer,” it’s a standoff being referred to. You can learn more in our Guide to standoffs.
PCB pillars
PCB pillars are also types of spacers, sometimes referred to as supports. These are handy when drilling into the chassis or enclosure is not possible. Drilled holes are made into the PCB itself where the pillar snaps or clips into place. For our purposes here, we’re including pillars, as your application may require them.
Types of PCB component spacers
PCB spacers and supports – or pillars – vary in style. Below are popular choices:
- Installed by hand
- Does not require assembly equipment
- Available in:
- Nylon 6/6
- Heat-stabilized nylon 6/6, operating temperature range: -40°F to 257˚F, UL94 V-2
- Polystyrene, operating temperature range: 68°F to 176°F, UL94 HB
- PVC, operating temperature range: -40°F to 176°F, UL94-V0
- POM, operating temperature range: -40°F to 221°F, UL94 HB
Use for: Ease of assembly
- No through hole required on PCB, which allows for easy access to the underside of the board
- Flanged base to keep them steady
- Flat Rest on one side and a Locking Arrowhead on the opposite side
- Operating temperature range: -40°F to 185 °F, nylon 6/6, UL94 V-2
Use for: Heavily loaded circuit boards
Support pillar – arrowhead snap lock
- Arrowhead design
- Dual locking support
- Available in several sizes and styles for different spacers, hole sizes and panel thicknesses
- Operating temperature range: -40°F to 185°F, nylon 6/6
Use for: Ease of fitting into chassis and PCB
- Beads that can also be used as spacers
- Installed by hand
- Does not require assembly equipment
- Suitable for wide range of applications
- Ceramic, with operating temperature of up to 3092°F
Use for: Applications exposed to extreme heat
Support pillar – collar spacer
- Two-piece application with pin that snaps into retainer
- Designed to capture the PCB
- Combination of mating parts forms a completely enclosed nylon spacer
- Operating temperature range: -40°F to 185 °F, nylon 6/6, UL94 V-2
Use for: Holds spacer securely on PCB for assembly into a machine or system
Support pillar – self retaining
- Can be used as a self-tapping screw
- Snap onto the PCB and maintains spacing, even when screw is removed
- Operating temperature range: -40°F to 185 °F, nylon 6/6, UL94 V-2
Use for: Insulating the head of the screw
- Spacers snap together to stack multiple PCBs
- Locking arrowhead
- Operating temperature range: -40°F to 185 °F, nylon 6/6, UL94 V-2
Use for: Stacking PCBs
Locking teardrop, cupped 2 sides
- Double-sided adhesive tape with release tab for quick installation
- Locks onto the board
- Releasable with a pinch
- Guides circuit boards
- Operating temperature range: -40°F to 185 °F, nylon 6/6, UL94 V-2
Use for: providing good spacing
- Fir tree fasteners on both ends for secure lock
- Flexible blind hole mount
- Operating temperature range: -40°F to 185 °F, nylon 6/6, UL94 V-2
Use for: locking into restricted spaces
How to choose spacers and pillars
Understanding the application or environment that your spacer will be operating in is essential when choosing the right solution. Before making your decision, here are some key questions:
- What type of PCB substrate are you working with?
- What kind of material is the mounting panel?
- Are there any space limitations?
- What other circuitry is present on the PCB?
Two critical areas are the PCB substrate and space limitations.
This depends on the dielectric properties you require from your PCB. More often you’ll be using fiberglass such as FR-4 or paperboard PCBs. Fiberglass PCBs deliver strength and flexibility so it’s best to use a snap fit spacer, as shown here.
Paperboard PCBs are more rigid and can fracture without the right support. You can use a push spacer to give support without penetrating the PCB, even when there is no mounting point.
Space limitations
The clearance space required between two PCBs directly affects the size of spacer or support you choose. If there is a need to stack multiple PCBs, then an active element such as a wing or arrowhead is recommended, particularly when using boards with lower weight tolerances. The table above gives a great example of a support pillar designed for stacking multiple PCBs.
Spacer materials
Knowing the material your application demands is vital when choosing the right spacer. Material can directly influence tensile strength, conductivity, prevention of short-circuits, temperature stability and conformance to legislation such as RoHS, Reach and UL94.
PCB spacers: metal
Metal screw spacers include brass, stainless steel and aluminum.
Aluminum is the most lightweight of metals and the least expensive. It’s non-magnetic and like all metals, stands up to high temperatures. Stainless steel, especially when plated with zinc, is excellent for corrosion resistance. Brass is a common material for standoffs and less so for spacers. It’s also non-magnetic, and can be soldered for grounding purposes.
Key benefits of metal:
- Keeps electrical conductivity when looking to maintain a circuit
- High tensile strength and impact resistance
- Enhanced heat resistance, perfect for high temperature environments
PCB spacers: plastic
We recommend plastic bolt spacers in nylon 6/6, heat-stabilized nylon 6/6, PVC, Polyoxymethylene (POM) and polystyrene (PS). Nylon is chemical resistant, but it should be avoided for applications that will be exposed to dampness and humidity. Over time, nylon tends to absorb moisture.
Heat-stabilized nylon 6/6 improves thermal properties, maintaining the mechanical properties of the material in temperatures of up to 257˚F. PS offers good thermal and electrical insulation. PVC is also good for electrical insulation and has good chemical resistance. POM, also known as Acetal, is good for heat resistance and has higher stiffness and lower friction than other plastics.
Key benefits are:
- Non-conductive of electricity, mitigating the risk of short-circuits
- Good resistance to corrosive substances
- Cost effective for manufacturing in high volumes
- Perfect when weight needs to be kept to a minimum
PCB spacers: ceramic
Used in industrial and mechanical applications rather than electronics. Ceramic beads and spacers are typically straight tubes for spacing hot resistors off the PCB or interlocking for flexible wire protection.
Key benefits are:
- Excellent insulation properties
- Non-conductive under extreme temperature loads
Plastic spacers for PCBs: at a glance
All plastics offer good electrical insulation. Below shows you attributes of individual plastics.
| Best for: | Nylon 6 |
Heat-stabilized nylon 6/6 |
PVC |
POM |
PS |
| Chemical resistance |
✔ |
✔ |
|||
| Thermal insulation |
✔ |
✔ |
|||
| Heat resistance |
✔ |
✔ |
|||
| Stiffness |
✔ |
||||
| Low friction |
✔ |
Mounting types
Finally, the mounting type you choose is determined by your application and spacer material. Here are some examples of mounting types:
Pushes into a panel/chassis hole, for a secure but easily releasable fix.
Quickly pushes into a panel/chassis hole, saving time in mass installation.
cupped base that provides a tight fit to the board as well as covering the hole completely.
Adhesive tape eliminates the need for a mounting hole, providing time and space efficiencies.
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 to ensure the spacers you’ve chosen are exactly what you need.
If you’re not quite sure which spacer 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.
Questions?
Email us at sales@essentracomponents.com or speak to one of our experts for further information on the ideal solution for your application 800-847-0486.