LS300

- **INDEX PRINT** 

- INTRODUCTION 2 

- ~~e~~ e The function of a heatsink is to increase the surface EQUATION 1 

- area available for the transfer of heat from a a component or device thereby increasing the amount of Thus PD = Tj - Ta heat that can be dissipated. Øjc + Øcs + Øsa 

- **The following products/services are available:** Where PD = Power dissipation (W) **1 A range of Standard heatsinks and accessories** Tj = Max allowable junction temp (ºC) which permit optimum flexibility in the design of (specified by device manufacturer) Electrical and Electronic equipment requiring Ta = Ambient temperature (ºC) = 

- heatsink applications. Øjc Thermal resistance junction to case (ºC/W) 

- **2 Custom designed heatsinks.** We have facilities (specified by device manufacturer) 

- available which enable us to provide design and Øcs = Thermal resistance, case to manufacturing of custom and specialised heatsinks heatsink (ºC/W) 

   - **2 Custom designed heatsinks.** We have facilities available which enable us to provide design and manufacturing of custom and specialised heatsinks to your requirements. 

- Øsa = Thermal resistance, heatsinks to ambient air (ºC/W) 

## HEATSINK SELECTION hs 

The maximum value for thermal resistance heatsink to air (sa) is usually determined by rearranging equation 1 to the following: 

The main factors to consider when selecting a heatsink are:- 

- 1 Geometry 

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- 2 Thermal Resistance 

- 3 Cost 

## **Defining the necessary heatsink performance.** 

The result of the above equation provides a thermal resistance value which must be equalled or bettered by the heatsink selected. 

In order to calculate the maximum acceptable thermal resistance for the heatsink so that  the device being cooled does not overheat it is first necessary to define the thermal parameters under which it is to operate. 

## EXAMPLE hs 

The basic equation for thermal equilibrium is:- 

A semi-conductor device is to be operated with its junction temperature not exceeding 80ºC whilst dissipating 16 watts to ambient air at a temperature of40ºC. The thermal resistance, junction to case, is specified by the manufacturer as 1.25ºC/W and the thermal resistance, case to sink (using an insulating washer and thermally conductive compound) is taken as 0.50ºC/W. 

Temperature difference across the system Sum of all the thermal resistance in the heat flow path. 

Power dissipated = 

Thermal Performance of any heatsink is influenced by many factors and for this reason all performance figures quoted should be treated as indicative only. It is recommended that the effectiveness of any heatsink is tested in the specific  operating  environment  in  which it  will  be subjected. 

Øsa  =  80 - 40 - (1.25 + 0.50) 

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=  0.75ºC/W 

The heatsink therefore must have a thermal resistance which does not exceed 0.75ºC/W. 

**INDEX** 

GENERAL INFORMATION 3 ~~e~~ e MATERIAL INSTALLATION NOTCHES EE Aluminium Alloy to BS1474 6063, T6. For heatsink lengths up to 87.5mm one single notch in each flange centrally along its length. DIMENSIONS Profile Tolerances: All profile dimensions are toleranced within BS1474 and this should be taken into consideration when designing our profiles into your equipment. Further details of specific tolerances can be supplied if required. _CL_ Po ~~ia~~ Length Tolerances: +/- 0.4mm For heatsink lengths from 88mm to 150mm three Tighter Tolerances can be offered if required. notches in each flange 38mm apart. 

SURFACE FINISH Po I Plain I Wet spray painted I Matt black anodised I Clear anodised I Alocromed I Coloured anodised I Powder Coated 

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38 38<br>CL<br>STANDARD NOTCH DIMENSIONS<br>**----- End of picture text -----**<br>


HOLE PATTERNS Po I Standard hole patterns for popular devices STANDARD NOTCH DIMENSIONS TO3/TO66/TO220 etc. Po I Non standard hole patterns to customers own requirements. _6.4_ PERFORMANCE _6.4_ Performance figures given are for natural convection operating conditions and are for a 60ºC temperature rise with a centrally mounted heat source and vertically _FULL RADIUS_ ~~i~~ mounted fins. Under general operating conditions the thermal mounting arrangement of devices is not known and therefore the figures should be used only as a STUDS AND SOLDERABLE PINS po guide to heatsink selection. It is recommended that the effectiveness of any Some heatsinks have standard solderable pins for flow heatsink is confirmed in the specific operating soldering to circuit boards. Non standard pins and studs can also be fitted. 

It is recommended that the effectiveness of any heatsink is confirmed in the specific operating environment in which it will be subjected 

## SAFETY CLIPS EE 

In some circumstances exposed heatsink surfaces may become very hot. Contact with these surfaces may cause burns damage to skin. 

A full range of standard clips are available from stock. 

**INDEX PRINT** FORCED AIR COOLING 4 ~~e~~ e This graph may be used as a guide to determine the Thermal resistance of any extruded section with forced convection. EXAMPLE Se The thermal resistance of a heatsink is 0.35ºC/W assume the heatsink is placed in a air velocity of 4m/s. Then 0.35ºC/W x 0.3 becomes 0.105ºC/W approx. 

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1.0<br>0.9 htt<br>0.8<br>A} ft |tt| te<br>0.7 AJ}<br>| |<br>0.6 Xt<br>TT<br>0.5 ENG<br>0.4<br>pt N\ |<br>0.3<br>pp [oN]<br>0.2<br>|| | |ty<br>0.1<br>pt [tet]<br>pitt 1 2 3 ty 4 5 6<br>AIR VELOCITY Meters/Second (m/s)<br>0<br>MULTIPLICATION FACTOR X C/W<br>**----- End of picture text -----**<br>


Performance figures are shown as an indication of a heatsinks actual performance. It is recommended that the effectiveness of any heatsink is tested in the specific operating environment in which it will be subjected 

**INDEX** 

5 

## CUSTOM DESIGN 

For those customers that require their own specific heatsink we can offer facilities for design, technical drawing and prototype manufacture. 

## PRODUCT RANGE 

In addition to our extensive range of heatsinks we manufacture components that are complimentary to the Electronics and Telecommunications Industries. Typical items of this nature include:- MODEM CASES, FRONT & REAR PANELS, ELECTRONIC ENCLOSURES, CHASSIS ETC. 

## MANUFACTURING AND FINISHING FACILITIES 

I FREE ISSUE OR TOTAL SUPPLY CAPACITY. I POWDER AND WET SPRAY PAINTING. I AUTOMATIC AND MANUAL SAW CUTTING. I WET SPRAY PAINTING ON PLASTICS. I CNC MACHINING, DRILLING AND TAPPING. I ALOCROM 1000 AND 1200 FINISHES. I PRESSWORK, FORMING AND BENDING. I ASSEMBLY WORK I BRUSH AND VIBRO DEBURRING. I SPECIAL PACKING I SULPHURIC AND CHROMIC ANODISING. I TOOL AND JIG MAKING. 

Performance figures are shown as an indication of a heatsinks actual performance. It is recommended that the effectiveness of any heatsink is tested in the specific operating environment in which it will be subjected 

**INDEX** 

6 

## SPRING CLIPS 

## PRODUCT RANGE ee 

Using our spring clips to fix plastic packages eg. TO220 and TO3P type devices offers several advantages over conventional methods:- 

I OPTIMISES THERMAL TRANSFER. 

I SAVES TIME. 

I ENABLES SINGLE SUPPLY SOURCE FOR HEATSINKS AND CLIPS. 

I SAVES COST. 

I REDUCES INVENTORY. 

SEE BOARD MOUNTING SERIES FOR MORE DETAILS. 

Performance figures are shown as an indication of a heatsinks actual performance. It is recommended that the effectiveness of any heatsink is tested in the specific operating environment in which it will be subjected 

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INDEX PRINT<br>e l <p<br>SPRING CLIPS 7<br>e e<br>CLIP 01 CLIP 02 CLIP 03<br>CLIP<br>REF<br>SO GN<br>PPN<br>PP<br>PPB<br>7 PPT PPD<br>CLIP 04 CLIP 05 CLIP 06<br>CLIP<br>REF<br>DOUBLE CLIP (2 X CLIP 05)<br>hk ee<br>FOR USE WITH<br>PRESSED PPM PPM<br>ALUMINIUM<br>wih<br>LOUVRE SINKS<br>PPR PPR<br>att lt<br>921 AB 921 AB<br>A<br>Performance figures are shown as an indication of a heatsinks actual performance. It is recommended that the effectiveness of any<br>heatsink is tested in the specific operating environment in which it will be subjected<br>HEATSINKS<br>HEATSINKS<br>**----- End of picture text -----**<br>