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Mounting a Heatsink on V or L Packages

The V and L Packages

The V and L packages are both popular integrated flyback, PFC, and LLC solutions, particularly in applications requiring a low profile. The total height of the part when mounted to the PCB, without a metal heatsink, will be <3mm.

V Package

L Package


Mounting Heatsink

Increasing the output power capability of the V or L package is easily achieved by mounting the metal heatsink to allow higher power dissipation. The low profile advantage of the V and L packages can be realized in actual board designs by selecting the heatsinks with appropriate size and shape. In a mass production environment, it is essential that the process to mount the heatsink to be simple, repeatable, and requires minimal amount of cycle time. Such consideration will allow the factory to attain the highest level of throughput. The proposed heatsinks discussed below were chosen with manufacturability, low profile, and reduced costs to be the major considerations.

The following are the different types of heatsinks that can be used with the V and L packages:

  • Standard heatsink: Commercially off the shelf heatsink
  • Customized heatsink
  • Clip type (no screw mount) heatsink


Standard Heatsink

Shown below are standard heatsinks used for 50W to 100W application that will also allow low height profile applications of <12.5 mm.

Standard Heatsinks

Heatsink mounted on L package and secured by wave soldering process.

Wave solderable heatsink mounted on V package with total height of 12.5mm

Further Information

1. The standard heatsinks shown above are available for purchase from the Qidong Huitong Screw Factory.

2. View a mechanical outline drawing of the aluminum heatsink with the dimension details.


Customized Heatsink

In some high volume applications the feasibility of developing a customized heatsink solution provides the advantage of optimized size and shape of the heatsink to the specific application.

Assembly drawing for attaching customized heatsink to the V package

The following table lists the part numbers in the above illustration.

Item No.Part NumberDescriptionQty.
1 61-00086-00 Heatsink, custom, copper
0.031" THK
2 66-00120-00 Silicone oil-based thermal
joint compound
3 66-00079-00 Thermal pad TO-220 .009"
4 66-00121-00 Tubing & sleeving-non
shrink. 14AWG Spool


No screw heatsink assembly

This approach offers the advantage of using clips or fasteners to securely place the heatsink instead of the typical screw based approach.

Assembly drawing for the clip type heatsink

Metal heatsink attached by clip on the L package


Recommended vendors:

VendorContact Information
Qidong Huitong Screw Factory No. 867 Middle Nanyuan Road
Qidong City, Jiangsu Province, 226200
Tel: 0513-83103190
FAX: 0513-83346768