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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.

Model		A (mm)	B (mm)	Screw size	C (mm)	Download		Availability / Price / Order
						Data Sheet	Other
	SS-10-3.9-M2.5-5	10.00	3.90	M2.5	5.00			Model Name:  Quantity −+ Check availability RFQ Order For US Customer days after order. For Other Area Customer days after order. Contact Alpha SalesClose
	SS-13.2-4.2-M3-4.2	13.20	4.20	M3	4.20
	SS-16-4.2-M3-5	16.00			5.00
	SS-19-4.2-M3-4.2	19.00			4.20
	SS-22	22.00			4.00
	SS-10-4.8-M3-5	10.00	4.78		5.00
	SS-12-4.8-M3-4	12.00			4.00
	SS-13-4.8-M3-3.5	13.00			3.50
	SS-13-4.8-M3-5				5.00
	SS-13.7-4.8-M3-5.8	13.72			5.84
	SS-16-4.8-M3-7	16.00			7.00
	SS-16.5-4.8-M3-5.8	16.51			5.84
	SS-19-4.8-M3-7	19.00			7.00
	SS-19.3-4.8-M3-5	19.30			5.00

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

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.

Please visit Spring Selection page.

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.

PEM and MAC8

Common nuts

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

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

• Introduction
• 1. Select heat sink
• 2. Assemble shoulder screws and springs
• 3. Install E-rings
• 4. Complete pre-assembly of screws and springs
• 5. Install mounting components on the PCB
• 6. Install heat sink from component side
• 7. Finish assembly (With Movies)
• Display all

Guidance for installing procedure.

1. Heat sinks requires thru holes on the corners for shoulder screws.

2. Install shoulder screw and spring through hole.

3. E-ring is inserted into the groove, making the shoulder screw and spring captive.

4. The heat sink is now pre-assembled with shoulder screws and springs.
Thermal interface material can be applied at this time to the heat sink base surface.

5. Install mounting components in the PCB.

6. Gently place the heat sink on top of chip from component side and line up screws with the thru holes/mounting components in the PCB.

7. Tighten the screws in an alternating crisscross pattern.

6. Standard Shoulder Screw Attached Heat Sinks

Alpha offers the following standard shoulder screw attached heat sinks:

LPD**S Series
UB**S Series

7. Related Links

Typical attachment methods
Test Report (Shock and Vibration)

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