INTRODUCTION
The function of a heatsink is to increase the surface
area available for the transfer of heat from a
component or device thereby increasing the amount of
heat that can be dissipated.
The following products/services are available:
1 A range of Standard heatsinks and accessories
which permit optimum flexibility in the design of
Electrical and Electronic equipment requiring
heatsink applications.
2 Custom designed heatsinks. We have facilities
available which enable us to provide design and
manufacturing of custom and specialised heatsinks
to your requirements.
The main factors to consider when selecting a
heatsink are:-
1 Geometry
2 Thermal Resistance
3 Cost
Defining the necessary heatsink performance.
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.
The basic equation for thermal equilibrium is:-
Temperature difference
across the system
Power dissipated =
Sum of all the thermal
resistance in the heat
flow path.
Thus PD = Tj - Ta
Øjc + Øcs + Øsa
Where PD = Power dissipation (W)
Tj = Max allowable junction temp (ºC)
(specified by device manufacturer)
Ta = Ambient temperature (ºC)
Øjc = Thermal resistance junction to
case (ºC/W)
(specified by device manufacturer)
Øcs = Thermal resistance, case to
heatsink (ºC/W)
Øsa = Thermal resistance, heatsinks to
ambient air (ºC/W)
The maximum value for thermal resistance heatsink to
air (sa) is usually determined by rearranging
equation 1 to the following:
Øsa = Tj - Ta - (Øjc + Øcs)
PD
The result of the above equation provides a thermal
resistance value which must be equalled or bettered
by the heatsink selected.
A semi-conductor device is to be operated with its
junction temperature not exceeding 80ºC whilst dissi-
pating 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.
Øsa = 80 - 40 - (1.25 + 0.50)
16
= 0.75ºC/W
The heatsink therefore must have a thermal resistance
which does not exceed 0.75ºC/W.
HEATSINK SELECTION
EQUATION 1
EQUATION 2
EXAMPLE
Thermal Performance of any heatsink is influenced by
many factors and for this reason all performance fig-
ures 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.
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GENERAL INFORMATION
Aluminium Alloy to BS1474 6063, T6. For heatsink lengths up to 87.5mm one single notch in
each flange centrally along its length.
For heatsink lengths from 88mm to 150mm three
notches in each flange 38mm apart.
Some heatsinks have standard solderable pins for flow
soldering to circuit boards. Non standard pins and
studs can also be fitted.
A full range of standard clips are available from stock.
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.
Length Tolerances: +/- 0.4mm
Tighter Tolerances can be offered if required.
Performance figures given are for natural convection
operating conditions and are for a 60ºC temperature
rise with a centrally mounted heat source and vertically
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
guide to heatsink selection.
It is recommended that the effectiveness of any
heatsink is confirmed in the specific operating
environment in which it will be subjected
In some circumstances exposed heatsink surfaces
may become very hot. Contact with these surfaces
may cause burns damage to skin.
■Plain
■Matt black anodised
■Alocromed
■Powder Coated
■Wet spray painted
■Clear anodised
■Coloured anodised
■Standard hole patterns for popular devices
TO3/TO66/TO220 etc.
■Non standard hole patterns to customers own
requirements.
MATERIAL INSTALLATION NOTCHES
STANDARD NOTCH DIMENSIONS
STUDS AND SOLDERABLE PINS
CLIPS
DIMENSIONS
SURFACE FINISH
HOLE PATTERNS
PERFORMANCE
SAFETY
C
L
38 38
C
L
6.4
6.4
FULL RADIUS
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FORCED AIR COOLING
EXAMPLE
This graph may be used as a guide to determine the Thermal resistance of any extruded section with forced
convection.
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.
1.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
123456
MULTIPLICATION FACTOR X C/W
AIR VELOCITY Meters/Second (m/s)
0
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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CUSTOM DESIGN
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
■FREE ISSUE OR TOTAL SUPPLY CAPACITY.
■AUTOMATIC AND MANUAL SAW CUTTING.
■CNC MACHINING, DRILLING AND TAPPING.
■PRESSWORK, FORMING AND BENDING.
■BRUSH AND VIBRO DEBURRING.
■SULPHURIC AND CHROMIC ANODISING.
■POWDER AND WET SPRAY PAINTING.
■WET SPRAY PAINTING ON PLASTICS.
■ALOCROM 1000 AND 1200 FINISHES.
■ASSEMBLY WORK
■SPECIAL PACKING
■TOOL AND JIG MAKING.
For those customers that require their own specific heatsink we can offer facilities for design, technical drawing
and prototype manufacture.
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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SPRING CLIPS
PRODUCT RANGE
Using our spring clips to fix plastic packages eg. TO220 and TO3P type devices offers several advantages over
conventional methods:-
■OPTIMISES THERMAL TRANSFER.
■SAVES TIME.
■SAVES COST.
■REDUCES INVENTORY.
■ENABLES SINGLE SUPPLY SOURCE FOR
HEATSINKS AND CLIPS.
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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SPRING CLIPS
CLIP
REF
CLIP 04 CLIP 05 CLIP 06
HEATSINKS
PPM
PPR
921 AB
DOUBLE CLIP (2 X CLIP 05)
FOR USE WITH
PRESSED
ALUMINIUM
LOUVRE SINKS
CLIP 01 CLIP 02 CLIP 03
CLIP
REF
HEATSINKS
PP
PPN
PPB
PPD
PPT
PPM
PPR
921 AB
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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