To avoid device damage, power components have a maximum junction temperature that must not be exceeded. Packages with varying levels of heat resistance are used to encase devices. When building power electronics, the device's heat dissipation, together with any heat sinks, as well as the maximum power dissipated by the device, must all be considered to ensure that the device runs within set parameters. Therefore, you need a Heat Sink Calculator. And the below will show you the detailed information of Online Calculator for Heat Sink.
Heat Sink Calculator Overview
Heat Sink Calculator is used to calculate the junction temperature and power for the power electronic components. You just need to input the values of Maximum Ambient Temperature, Maximum Junction Temperature, Thermal Resistance - Junction to Case and Thermal Resistance 1 (R1). And the value of Thermal Resistance 2 is optional. So the result will be the same whether you input the value of Thermal Resistance 2 (R2).
Overview of Heat Sink Temperature
What is Heat Sink Temperature?
The junction temperature of a semiconductor in an electronic device is the greatest operational temperature that it can endure. The Heat Sink temperature is usually greater than the device's exterior and case temperature. The difference between the junction temperature and the outside, plus case temperature, is equal to the heat transmitted from the junction to the case, multiplied by the junction-case thermal resistance.
An electronic component's maximum junction temperature is always listed on its datasheet. It comes in handy when you need to calculate the needed case-ambient thermal resistance based on the amount of power wasted. The maximum junction temperature is then utilized to select the appropriate heat sink.
How to Calculate Heat Sink Temperature?
A heat sink maintains the temperature of a gadget below the recommended operating temperature. Heat from a device moves from the junction to the case, then from the case to the heat sink, and finally from the heat sink to ambient air with the use of a heat sink. The objective is to lower heat resistance. You may use thermal circuit models and formulae to calculate a device's thermal resistance to see if it needs a heat sink for thermal management. These thermal circuit concepts are comparable to Ohm's law-based resistor circuits.
Equations of Heat Sink Temperature Calculation
To determine the necessity of a heat sink, calculate the junction temperature with the following equation:
Tj=P*(Rcase+R1+R2)+Ta
Where:
Tj = junction temperature
P = power dissipated
Rcase = thermal resistance of device junction to case
R1 = thermal resistance of device junction to air (if no heat sink) or thermal resistance of heat sink
R2 = thermal resistance of device junction to air
Introduction of Heat Sink
In technology, industry, and even natural systems, heat sinks are one of the most popular means of thermal control. Even individuals who are knowledgeable with technology might easily ignore these components since they are so common. We'll go over the fundamentals of heat sink operation, introduce active and passive heat sink topologies, and talk about how various users employ heat sinks in their applications.
What is a Heat Sink?
What is a Heat Sink?
A heatsink is a heat-transfering passive heat exchanger. The heatsink is often a metallic element that may be mounted to a device that emits heat in order to dissipate that heat to a surrounding fluid and prevent the device from overheating.
The device in many applications is an electrical component (e.g., CPU, GPU, ASIC, FET, etc.) with air as the surrounding fluid. Conduction is used to transmit heat from the device to the heatsink. Convection is the predominant mode of heat transfer from the heatsink, however radiation plays a small role.
What Does a Heat Sink Do?
A heat sink is a component that helps to transfer heat away from a hot device. It does this by increasing the device's operating surface area and the amount of low-temperature fluid that flows through it. We find a variety of heat sink aesthetics, design, and final capabilities based on each device's arrangement. In the image at the top of this post, you can see a straight fin heat sink, and in the image below, you can see a flared fin heat sink. Each heat sink is useful in situations with variable temperatures. Heat is moved away from a key component using a heat sink. Almost all heat sinks follow a four-step process to do this objective.
Step 1: The source generates heat
This source might be any system that generates heat and has to be cooled in order to work properly. For example: Chemical, Electrical, Friction, Mechanical, Nuclear and Solar.
Step 2: Heat transfers away from the source
Natural conduction transports heat from the source to the heat sink in direct heat sink-contact situations. The thermal conductivity of the heat sink material has a direct influence on this process. As a result, strong thermal conductivity materials like copper and aluminum are commonly used in heat sink design.
Step 3: Heat distributes throughout the heat sink
Heat will naturally flow through the heat sink by natural conduction as it moves across the thermal gradient from a hot to a cold environment. As a result, the thermal profile of the heat sink will be inconsistent. As a result, heat sinks are frequently hotter at the source and colder towards the sink's extremes.
Step 4: Heat moves away from the heat sink
This process is dependent on the temperature differential of the heat sink and the working fluid, which is usually air or a non-electrically conducting liquid. The working fluid flows across the heated heat sink's surface, using thermal diffusion and convection to transfer heat away from the surface and into the surrounding environment. To remove heat from the heat sink, this cycle again relies on a temperature gradient. As a result, no convection and consequent heat removal will occur if the ambient temperature is not colder than the heat sink. This is also the point at which the heat sink's overall surface area becomes most useful. A wide surface area allows for more heat diffusion and convection to take place.
Types of Heat Sink
Heat sinks are divided into two categories based on their production techniques and final form forms. The following are the most popular types of air-cooled heat sinks.
Bonded/Fabricated Fins
Most air cooled heat sinks are convection constrained, and if additional surface area can be exposed to the air stream, the overall thermal performance of an air cooled heat sink may typically be greatly enhanced. Thermally conductive aluminum-filled epoxy is used to attach planar fins to a grooved extrusion base plate in these high-performance heat sinks. This method enables a significantly higher fin height-to-gap aspect ratio of 20 to 40, greatly boosting cooling capacity without increasing volume.
Castings
Sand, lost core, and die casting methods are offered in aluminum or copper/bronze, with or without vacuum aid. This technique is employed in high-density pin fin heat sinks that offer the best performance when impingement cooling is applied.
Extrusion
These enable the creation of complex two-dimensional forms capable of dispersing vast amounts of heat. They may be cut, machined, and customized with choices. Cross-cutting produces omni-directional, rectangular pin fin heat sinks, and adding serrated fins enhances performance by around 10% to 20%, although at a slower extrusion rate. The versatility of design possibilities is frequently limited by extrusion restrictions, such as the fin height-to-gap fin thickness. A typical extrusion may achieve a fin height-to-gap aspect ratio of up to 6 and a minimum fin thickness of 1.3mm. With unique die design characteristics, a 10 to 1 aspect ratio and a fin thickness of 0.8” may be accomplished. The extrusion tolerance is degraded as the aspect ratio grows.
Folded Fins
Corrugated sheet metal, whether made of aluminum or copper, expands the surface area and hence the volumetric performance. The heat sink is then epoxy- or braze-attached to a base plate or directly to the heating surface. Because of the availability and fin efficiency, it is not appropriate for high-profile heat sinks. As a result, it is possible to build high-performance heat sinks for applications.
Stampings
Sheet metals made of copper or aluminum are stamped into the necessary forms. They are employed in conventional air cooling of electronic components, and they provide a low-cost solution to low-density thermal issues. They are well suited to high-volume manufacturing because improved tooling and high-speed stamping reduce costs. Taps, clips, and interface materials, among other labor-saving solutions, can be implemented in the manufacturing to assist minimize board assembly costs.
How to Select Heat Sink
How to select a Heat Sink for cooling electronics/electrical devices
When choosing a heat sink that fulfills the needed thermal requirements, it's important to consider a number of factors that impact not just the heat sink's performance but also the system's overall performance. The thermal budget available to the heat sink, as well as the external circumstances around the heat sink, play a big role in deciding the sort of heat sink to use. It is important to note that a single value of thermal resistance can never be ascribed to a heat sink since thermal resistance fluctuates with external cooling conditions.
It is vital to define the air flow as natural, low flow mixed, or high flow forced convection when choosing a heat sink. When there is no externally generated flow and heat transmission is purely dependent on the free buoyant movement of air surrounding the heat sink, natural convection occurs.
When the flow of air is induced by mechanical means, such as a fan or blower, it is known as forced convection. There is no evident differentiation between the mixed and forced flow regimes in terms of flow velocity. When the generated air flow velocity exceeds 12 m/s, it is generally believed in applications that the influence of buoyant force on total heat transfer reduces to insignificant levels (sub 5%). (200 to 400 lfm).
The next step is to figure out how big a heat sink you'll need. The following table depicts the approximate volumetric thermal resistance ranges of a typical heat sink under various flow circumstances.
Flow condition | Volumetric Resistance | |
natural convection | 500-800 | (30-50) |
1.0 (200) | 150-250 | (10-15) |
2.5 (500) | 80-150 | (5-10) |
5.0 (1000) | 50-80 | (3-5) |
Range of volumetric thermal resistance
