FAQ's | Questions and answers on the subject of electronics cooling

The decision whether it is worthwhile to use a special profile for a heat sink depends on various factors, such as:

Power of the component to be cooled: The higher the power of the component, the greater the amount of heat that needs to be dissipated. In such cases, a special profile may be useful to ensure better heat dissipation.

Ambient conditions: The environmental conditions in which the heat sink is used can also have a major impact. If the ambient temperature is high or the heatsink is used in an environment with limited airflow, a special profile can help to improve heat dissipation.

Space requirements: If the available space is limited, a special profile can help improve cooling performance without having to increase the size of the heat sink.

Cost-effectiveness: Using a custom profile may involve higher costs, especially if it is a one-off. It is important to weigh up whether the benefits of the custom profile justify the extra cost.

In summary, it is worthwhile to set up a special profile for a heat sink if the performance of the component to be cooled is high, the ambient conditions are unfavourable, the available space is limited and the advantages of the special profile justify the additional costs.

It is important for designers to know that, especially for "large" profiles with a wrap circle of >350mm, limit dimensions and shape tolerances according to the standards below can assume values that are significantly higher than the values of the more familiar DIN ISO 2768-1 or DIN ISO 2768-2 (standard for general tolerances for length and angle dimensions as well as shape and position).
For example, the cross-sectional dimensions of a profile with a wrap circle of 200mm to 300mm may include maximum deviations of ±2.5mm; the convexity or concavity in this case may be up to 1.8mm.

The valid standards for limit dimensions and shape tolerances of extruded profiles made of aluminium and aluminium alloys are:
- DIN EN 12020-2: valid for wrap-around circles of >350mm, replaces DIN 17615-3, which is no longer valid.
- DIN EN 755-9: valid for wrap-around circles of >800mm, replaces DIN 1748-4 which is no longer valid.

DIN EN 12020-2 differs from DIN EN 755-9, apart from the size restriction, in the following aspects in particular:
- Valid for precision profiles exclusively of the alloys EN AW-6060 and EN AW-6063.
- Mainly for architectural applications
- Stricter requirements with regard to visible surfaces
- Tighter limit dimensions and shape tolerances

Since DIN EN 755-9 does not have a lower limit with regard to the wrap circle, pressing plants can also produce profiles with a wrap circle >350mm according to DIN EN 755-9 if the tolerances of 12020-2 are too low for reliable production.
In addition, special agreements deviating from the standards may be necessary between manufacturer and buyer for complex profiles. 

If the tolerances of these standards do not fit the application, ALUTRONICers are ready to work with the designer to develop and manufacture customised adaptations through machining and surface processing.

The mass and surface area of a heat sink are two important factors that can affect heat dissipation. A heat sink with a larger mass tends to be able to absorb and store more heat before releasing it to the environment. A larger surface area, on the other hand, can dissipate more heat to the environment.

The ratio of mass to surface area depends on the shape of the heat sink. A heatsink with a larger surface area relative to mass tends to dissipate heat more effectively than a heatsink with a smaller surface area relative to mass.

However, there are other factors to consider, such as the performance of the component that needs to be cooled and the environmental conditions. A small heat sink with a low mass may be more effective than a large heat sink with a higher mass and larger surface area under certain conditions.

Therefore, it is important to consider various factors when choosing a heat sink to ensure effective heat dissipation.

LME (London Metal Exchange) is the abbreviation for the London Metal Exchange, which is one of the oldest and largest metal trading centres in the world.
Along with Singapore and New York, the reference prices for metals, including aluminium, are determined here daily on the basis of supply and demand.
As a raw material price, the LME price for aluminium is a factor that fundamentally influences the costs of extruded aluminium profiles.
However, the prices of extruded profiles are not only dependent on the LME price, there are also other influencing factors such as:
 

• Exchange rate: as the aluminium price is traded on the exchange in US dollars, changes in exchange rates also affect prices.
• Billet premium: For the production of extruded profiles, the aluminium billets have to be remelted into special billets, the costs for this are called "billet premium".
• Special surcharges: These include, for example, costs as a result of sharply increased energy prices.
• Profile cross-section: The larger and more complex the profile, the higher the price usually is.
• Surface condition: A surface treatment such as anodising, coating or special optical requirements increase the costs.
• Quantity: The larger the order quantity, the lower the price per unit can be.
• Competition: If there are many suppliers of a certain type of extrusion on the market, this can lead to lower prices, while a limited number of suppliers can lead to higher prices.
• Transport costs: Transport costs can be factored into the price depending on the delivery route and transport medium.

 
In summary, the LME price for aluminium as a raw material price is an important factor in determining the cost of extruded profiles.
The actual price can deviate significantly from this for the reasons mentioned above

The decision as to whether forced ventilation is necessary or not depends on various factors, such as:

Performance of the component to be cooled: The higher the power of the component, the greater the amount of heat that must be dissipated. If the heat dissipation of the component exceeds the capacity of the heat sink, forced ventilation may be necessary.

Ambient conditions: The environmental conditions in which the heat sink is used can also have a major impact. If the ambient temperature is high or the heatsink is used in an environment with limited airflow, forced ventilation may be necessary to improve heat dissipation.

Space requirements: If available space is limited, forced ventilation may be required to improve cooling performance without increasing the size of the heatsink.

Cost-effectiveness: Forced ventilation may come at a higher cost, especially if achieved through additional components such as fans or heatsinks. It is important to weigh whether the benefits of forced ventilation justify the additional cost.

Overall, it can be said that forced ventilation may or may not be necessary depending on the performance of the component being cooled, the environmental conditions, the space available and the cost factors. If the heat sink alone is not able to effectively dissipate heat, forced ventilation may be required to improve cooling performance.

The performance data, or more precisely the thermal resistance Rth of heat sinks, is generally determined empirically, i.e. in the laboratory, by applying an impressed power loss PV as a heat flow to the heat sink via its baseplate and determining the temperature difference Du between the heat sink and the environment. Alternatively, this determination can also be carried out by simulation programs.

The determined value of the thermal resistance is therefore the only thermal parameter with which heat sinks of different designs, materials and manufacturers can be compared.

This is particularly worth mentioning because this "characteristic value" depends on the following influencing variables and measurement parameters, among others:

• Ratio of the heating surface of the heat source to the base surface of the heat sink
• (absolute) temperature of heat sink and environment
• Radiation losses of the heat source
• (absolute) power of the heat source
• Position of the temperature measurement point on the heat sink
• When determining thermal resistances with forced convection, further influences such as flow type and flow losses are added (see also à pressure chamber).

It is worth noting that there are neither guidelines nor standards regarding the determination of thermal resistance, according to which the data must be recorded.

A serious manufacturer of heat sinks will therefore not only state exactly under which conditions he has measured the thermal resistance, he will also choose a practical measuring method in order to be able to present realistic results.

At ALUTRONIC, all values given in the catalogue have been measured under the following conditions, unless otherwise stated in the data sheet:

• Natural convection
• Matt black anodised heat sink
• Vertical arrangement of fins
• A heat source with 40% of the floor area in the centre of the heat sink
• Temperature measurement between semiconductor and heat sink mounting surface
• Use of heat-conducting paste
• Measurement of the ambient temperature at a distance of one metre (1m) from the object to be measured

First of all: A heat pipe is not a heat sink and cannot replace one, but a heat sink is often needed to operate a heat pipe.

In somewhat unscientific, but therefore understandable terms, a heat pipe is a tubular component that exploits the phenomenon that a relatively large amount of energy is required for evaporation in order to change the aggregate state of substances, e.g. from liquid to gaseous. This amount of energy is released again when the state of aggregation is changed back from gaseous to liquid, i.e. condensation.

In scientific terms, a passive component, also generally referred to as a heat pipe, uses the enthalpy of evaporation of the medium in it as a heat exchanger between at least two points, which are referred to as heat source (= evaporator) and heat sink (= condenser). The transport zone is located between these two points.

Due to special structures in the interior that promote capillary action, the heat pipe can be operated in any position within certain limits, which distinguishes it from the 2-phase thermosiphon.

The following aspects are important in practice:

• The ability of a heat pipe to transport a certain amount of heat depends on length, cross-section, internal structure, working medium, position, thus a heat pipe should be matched to the application.
• A heat pipe can only be operated within its operating limits, which result from the application in terms of temperature and heat flow. In detail, these limits are viscosity limit, sound velocity limit, interaction limit, capillary force limit and boiling limit.
• The heat conduction is up to 1000 times better compared to a solid copper rod of identical outer geometry.
• Gravity has a positive or negative effect on the return transport of the liquid medium, depending on its position; the influence factor on the heat flow is between 0.6 and 1.6.

An anodised layer, also known as an anodised aluminium layer, is an artificial oxide layer created on the surface of aluminium. Anodising the aluminium creates a dense and hard oxide layer on the surface of the metal, which forms a protective layer and offers a variety of benefits, including:

Corrosion protection: the anodised layer protects the aluminium from corrosion and oxidative decomposition. The layer is resistant to most chemicals, including acids and alkalis.

Improved hardness and wear resistance: The anodised layer increases the hardness and wear resistance of the aluminium surface, which helps to make it more resistant to scratches and wear.

Electrical insulation: The anodised layer has high dielectric strength and can act as electrical insulation.

Optical effects: The anodised layer can be produced in different colours, providing an option for aesthetics and design customisation.

Improved adhesion: The anodised layer can be used as an adhesion primer to improve the adhesion of adhesives and paints to aluminium.

Thermal insulation: The anodised layer can also provide some thermal insulation, which can be useful in high temperature applications.

In summary, an anodised coating offers a range of benefits from improved corrosion protection to aesthetic and functional properties that can be beneficial in many different applications.

Heat sinks manufactured using the cold extrusion process have several advantages over other manufacturing methods:

Efficient heat dissipation: Heat sinks made by cold extrusion have very high thermal conductivity, which means they can effectively dissipate heat from the heat source.

Less material waste: Cold extrusion processes make it possible to produce complex heat sink shapes from a single piece without a lot of material waste. In contrast, conventional machining methods can produce a lot of material waste.

Lower costs: Cold extrusion makes it possible to produce heat sinks in large quantities quickly and cost-effectively. It is also an automated process, which further improves production efficiency.

High precision: Cold extrusion offers very high precision, allowing complex geometries and tight tolerances to be achieved, resulting in better fit and performance.

Overall, heatsinks produced by cold extrusion offer high efficiency, low material waste, lower cost and high precision, making them an attractive option for many applications.

If you want to design the machining on an aluminium heat sink as cost-efficiently as possible, you should consider the following points:

Material selection: Aluminium is a commonly used material for heat sinks due to its high thermal conductivity and low density. However, there are different aluminium alloys that have different properties and prices. It is therefore worth comparing the properties and costs of the different alloys to make a cost-effective choice.

Design optimisation: Careful design of the heat sink can help minimise material waste and reduce manufacturing costs. It is worth considering design alternatives that have less complex geometries or thinner wall thicknesses to make the best use of the material.

Machining methods: There are various machining processes that can be used to produce aluminium heat sinks, such as milling, turning, drilling and grinding. It is worth reviewing the different processes to select the most appropriate one for the design in question, which will allow fast and accurate machining.

Tool selection: The choice of tools and cutting edges is an important factor in the cost and quality of machining. High-quality tools can be more expensive, but they often offer longer tool life, higher accuracy and better surface finish, which can reduce overall costs.

Automation: Automating manufacturing processes can increase productivity and reduce labour costs. It is worth looking at automating manufacturing processes, such as using CNC machines, to streamline machining processes and reduce manufacturing costs.

By considering these points, you can design machining on an aluminium heat sink to be as cost-effective as possible and reduce production costs.

To find the right standard heat sink for your application, follow these steps:

Determine the heat dissipation: Determine the maximum heat generated by the component to be cooled. This information is important to ensure that the heat sink you choose can dissipate enough heat.

Determine the ambient conditions: Consider the environmental conditions in which the heat sink will operate. For example, if the heatsink will be operated in an environment with high humidity or heavy vibration, choose a heatsink that is suitable for these conditions.

Choose a heatsink with the right size and shape: Pay attention to the dimensions of the heatsink to ensure that it fits your application and that it has enough surface area to dissipate heat. The shape of the heatsink should also fit your application, e.g. a flat heatsink for applications with limited space.

Check the mounting options: Make sure the heatsink can be mounted to your application, e.g. by screwing, clamping or gluing.

Compare the technical data: Check the technical data of the heat sink to make sure it meets the requirements of your application. Pay attention to parameters such as thermal conductivity, thermal resistance, weight, material and price.

Check availability: Make sure that the heat sink you choose is available and can be supplied in sufficient quantities.

By following these steps, you can find the right standard heatsink for your application. If you have difficulty finding the right heatsink, you can contact a specialist dealer or heatsink manufacturer to help you make your choice.

The carbon footprint of a heat sink refers to the amount of greenhouse gas emissions generated during the production of the heat sink. The carbon footprint is usually measured in tonnes of carbon dioxide equivalent (tCO2e) and includes all direct and indirect emissions that occur during the life cycle of the heat sink, including manufacture, transport, use and disposal.

The exact size of a heatsink's carbon footprint depends on many factors, such as the type of material from which the heatsink is made, the manufacturing process, the type of transport, the energy supply used in the manufacture and operation of the heatsink, and the way the heatsink is used and disposed of.

To minimise the carbon footprint of a heat sink, there are several approaches, such as:

Using recycled materials to reduce the need for manufacturing virgin raw materials.
Using renewable energy sources in the manufacture and operation of the heat sink to reduce energy consumption and therefore CO2 emissions
Optimisation of manufacturing methods to minimise waste and emissions
Design optimisation to minimise the size and weight of the heatsink, which reduces transportation and thus CO2 emissions
Longer life of the heat sink to reduce the need for replacement or disposal.
By implementing these approaches, the carbon footprint of a heat sink can be reduced.

Yes, there are several ways to influence the carbon footprint of a heat sink:

Purchase decision: Before you buy a heat sink, you can find out about the energy efficiency of the product and choose a more environmentally friendly option. There are energy efficiency labels that can help you identify energy efficient equipment.

Maintenance: Regular maintenance of the heatsink can help improve the energy efficiency of the appliance and thus reduce the carbon footprint. This includes, for example, cleaning the cooling fins and replacing outdated or damaged components.

Use: You can also influence the carbon footprint of the heat sink by the way you use it. For example, you can set the temperature of the unit to the minimum required for your needs and ensure that you switch off the unit when it is not in use.

Disposal: When you dispose of the heat sink at the end of its life, you can ensure that it is properly recycled or disposed of to minimise its impact on the environment.

Yes, the alloy of the heat sink can play a role in its carbon footprint. Some alloys are more energy intensive and carbon intensive to manufacture than others. For example, the production of aluminium alloys is usually more energy intensive than the production of copper alloys.

Higher energy intensity usually means higher greenhouse gas emissions, which can increase the carbon footprint of the product. Therefore, it is important to also consider the materials used when choosing a heat sink.

Some manufacturers, including ALUTRONIC, also use recycled materials or materials from renewable sources to reduce their CO2 emissions. You can look for such products to minimise the carbon footprint of your heat sink.

However, it is also important to note that the choice of material alone is not enough to determine the carbon footprint of a heatsink. The entire life cycle of the product, including manufacturing, transport, use and disposal, contributes to its environmental impact.

Es gibt verschiedene Maßnahmen, die Sie ergreifen können, um die Wärmeableitung Ihres Kühlkörpers zu verbessern:

Platzierung: Stellen Sie sicher, dass der Kühlkörper korrekt auf dem Bauteil montiert ist und der Kontakt zwischen dem Kühlkörper und dem Bauteil eng ist. Eine unzureichende Montage kann die Wärmeableitung beeinträchtigen.

Kühlkörpergröße: Überprüfen Sie, ob die Größe des Kühlkörpers angemessen ist, um die Wärmeabgabe zu bewältigen. Ein zu kleiner Kühlkörper kann die Wärme nicht effektiv ableiten, während ein zu großer Kühlkörper zu teuer sein kann und Platzprobleme verursachen kann.

Kühlkörperdesign: Überprüfen Sie das Design des Kühlkörpers, um sicherzustellen, dass es für den spezifischen Zweck optimiert ist. Ein effektives Kühlkörperdesign kann die Wärmeableitung verbessern.

Lüfter: Wenn Ihr Kühlkörper einen Lüfter hat, stellen Sie sicher, dass er ordnungsgemäß funktioniert und die Luftzirkulation verbessert. Eine schlechte Luftzirkulation kann die Wärmeableitung beeinträchtigen.

Kühlkörpermaterial: Wenn möglich, wählen Sie einen Kühlkörper aus einem Material mit einer hohen Wärmeleitfähigkeit wie Kupfer oder Aluminium. Diese Materialien können dazu beitragen, die Wärmeableitung zu verbessern.

Zusätzliche Wärmeableitung: Wenn der Kühlkörper nicht ausreicht, um die Wärme effektiv abzuleiten, können Sie zusätzliche Wärmeableitungsteile wie Wärmeleitfolien oder Wärmeleitpaste verwenden, um die Wärmeableitung zu verbessern.

When installing and mounting a heat sink, there are several factors to consider to ensure effective cooling. Here are some important points:

Orientation: make sure the heatsink is properly oriented to ensure optimal heat transfer. The heat sink should be oriented so that the largest surface area of the heat sink is in contact with the heat source.

Thermal paste: Use a thermal paste between the heat sink and the component to be cooled. The thermal paste helps to avoid air bubbles between the heat sink and the component and improves heat transfer.

Fastening: Make sure the heat sink is securely fastened to ensure sufficient heat transfer. Inadequate fastening may result in the heat sink not remaining in close contact with the component.

Cleaning: Clean the component to be cooled to ensure that no contaminants or impurities interfere with heat transfer.

Air circulation: Make sure that the air circulation around the heat sink is sufficient. Poor air circulation can result in the heat sink not effectively dissipating its heat to the environment.

Power supply: If the heatsink has a fan, make sure the fan is properly connected and powered for optimal cooling.

Component temperature: Ensure that the operating temperature of the component to be cooled is within the permissible range. Excessive operating temperature can reduce the life of the component and affect its performance.

By following these tips, you can ensure that your heat sink functions optimally and protects the component to be cooled from overheating.