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New U-shaped transistor retaining springs


Effective thermal management is known to be essential to ensure the durability, reliability and performance of electronic devices over a period of time specified by the manufacturer. Similarly, the mechanical attachment of the devices on the heat dissipation component to achieve the lowest heat transfer resistance between the contact pair plays a significant role in the overall design. For many applications the way in which semiconductors are fixed is considered by customers to be a cost-reducing factor. Therefore it must be possible to fix the components quickly and easily without neglecting the aspects of mechanical safety and thermal contacting. In addition to the classical device mounting by means of various screw or adhesive connections, so-called transistor retaining springs from Fischer Elektronik provide a very good possibility of fixing transistors on or to a heat sink. The already extensive product range of transistor retaining springs has been extended by new U-shaped spring geometries. The new and in total six different retaining springs are made of a corrosion-protected spring steel. The products with the designation THFA 5 to 10 are adapted in their contour and dimensions to the different types of transistors, such as TO 218, TO 220, TO 247 and TO 3 P. The spring geometry consists of a straight surface which acts as a transistor support surface, whereas an opposite rounding exerts the contact pressure on the component by means of spring action and locks it securely and reliably. Depending on the design, the individual transistor retaining springs contain a locking point for the respective transistor or a special latching geometry, with which the spring can be fixed directly on the PCB in a groove being provided. Furthermore, it is possible to mount transistors on an external fin of a heatsink. In many extruded heatsinks as comb profiles, the external cooling fins are thicker in terms of material thickness, so that transistors can be placed on the fin contour from the outside and fixed securely and quickly by pushing over the THFA retaining springs. In addition to the base of the heatsink, the external cooling fins in conjunction with the U-shaped transistor retaining springs therefore provide an additional component mounting surface.

The listed innovations of the U-shaped transistor retaining springs of the THFA ... series as well as all innovations from Fischer Elektronik can also be found at

Please contact us. For further information and enquiries, please do not hesitate to contact our sales team and technical advisors at Fischer Elektronik.

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Fischer Elektronik GmbH & Co. KG

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58511 Lüdenscheid


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 +49 2351 45754