Online Catalog

Shoulder Screw


Shoulder Screws are an extremely reliable attachment method.
Several standard screws are available, while springs generate the appropriate mounting force/pressure. Alpha can design and produce the entire assembly, including the heat sink, shoulder screws, springs, and thermal interface material.

Shoulder Screw
1. Shoulder Screw Specification









Availability /

Price / Order

Data Sheet Other
SS diagram 10.00 3.90 M2.5 5.00 catalog RoHS REACH DXF
13.20 4.20 M3 4.20 catalog
16.00 5.00 catalog
19.00 4.20 catalog
22.00 4.00 catalog
10.00 4.78 5.00 catalog
12.00 4.00 catalog
13.00 3.50 catalog
5.00 catalog
13.72 5.84 catalog
16.00 7.00 catalog
16.51 5.84 catalog
19.00 7.00 catalog
19.30 5.00 catalog

2. Features & Explanation of shoulder screws

Shoulder screws consist of the "Head", the "Shoulder", and the "Thread" sections.

Features of shoulder screws

Within the shoulder section, an E-ring can be inserted into the groove, making the screw captive to the heat sink. Captive hardware allows the heat sink to be easily assembled and disassembled from the PCB without the inconvenience of loose hardware. Captive hardware also reduces the total number of components, simplifying the BOM.

The shoulder screws can be used with board mounted threaded inserts or standoffs. If the treaded inserts are on the backside of the PCB, the shoulder diameter needs to be larger than the hole in the PCB. When the shoulder screws are tightened, the shoulder will bottom on the PCB surface or the standoff. Once the shoulder makes contact, the heat sink is properly installed.

Stable & Robust

Shoulder screws offer the most reliable and rugged attachment method possible. Passed all shock and vibration testing.

Safe & Simple

Captive hardware and simple installation minimizes possibility of error and damage.

Prevent Board Warpage

A standard or custom backing plate is an option for high attachment forces.

Flexible Design

Hole location and attachment forces can be customized for each specific application.

Attachment Force

Appropriate attachment force/pressure can be consistently generated through screw/spring selection.

High Performance

High performance interface materials including phase change and thermal grease can be used instead of tape or epoxy.

3. Spring Selection

Please visit Spring Selection page.

4. Mounting components for PCB attachment

As discussed above, there are several different hardware components that can be used to attach shoulder screw heat sinks to the PCB. Final heat sink design will depend on which mounting component is used. Please review the specification of each mounting component and how the component is used to attach the heat sink to the PCB.
Alpha's standard shoulder screw thread specification is M3. If you need additional information regarding these components, please contact Alpha sales.

Press-in or Soldered Inserts and Spacers *



PEM and MAC8


Common nuts


Backing Plate


Installed on PCB surface (component side).
Nut required on backside of PCB.

Backing Plate/Stiffener

Backing plate is installed on the backside of the PCB. It provides attachment hardware and additional stiffness, preventing excessive bowing of the PCB. Alpha's standard backing plates.

*Alpha does not provide these components as standard parts.

5. Installing Procedure and other components
6. Standard Shoulder Screw Attached Heat Sinks

Shoulder Screw Alpha offers the following standard shoulder screw attached heat sinks:

Typical attachment methods
Test Report (Shock and Vibration)

Back to Top

© 2019 Alpha Novatech, Inc.