WO2023287384A1

WO2023287384A1 - A heat sink with tree-structured fins

Info

Publication number: WO2023287384A1
Application number: PCT/TR2022/050725
Authority: WO
Inventors: Seyfi ŞEVİK; Özgür ÖZDİLLİ
Original assignee: Hi̇ti̇t Üni̇versi̇tesi̇ Rektörlüğü
Priority date: 2021-07-14
Filing date: 2022-07-07
Publication date: 2023-01-19

Abstract

The invention is a heat transfer product developed for the cooling of electronic components of a heat sink with a curved base and a plurality of pin-type tree-structured wavy fins extending vertically on the base.

Description

A HEAT SINK WITH TREE-STRUCTURED FINS

TECHNICAL FIELD

BACKGROUND OF THE INVENTION

With the developing technology, electronic components are produced more functionally and with higher performance. However, with this increase in performance, the unwanted heat formations produced by the components also increase. Electronic components deteriorate or fail to perform adequately when exposed to high heat. In order to avoid this situation, active (forced air by a fan or liquid stream circulated by a pump) or passive (Natural) heat sinks that can be mounted on electronic components are used to quickly and efficiently remove the high heat produced. The heat sinks (coolers) are used to increase the surface area available for heat transfer from a component or device, thereby increasing the amount of heat that can be dissipated.

Heat sinks consist of products with high thermal conductivity coefficients such as aluminum and copper in different forms. Aluminum alloys are widely used, especially due to their high-strength, lightweight construction, and relatively low cost. About two-thirds of the aluminum alloys used are the 6XXX series, which has a good specific strength, toughness, higher corrosion resistance, better weldability, and contains silicon and magnesium. Generally, two different heat sink geometries are used for cooling heat-generating electronic equipment. These are plate-fin heat sinks and pin heat sinks.

Despite the temperature increase in electronic devices, there is a need to ideally produce heat sink designs that can prevent the decrease in performance in general functions and allow to keep material and production costs at a minimum. Therefore, there is a growing demand for alternative geometries in heat sink products that can provide greater design freedom and lower weight without sacrificing safety.

Similar to the above systems; light-emitting diodes (LEDs) have been finding a lot of applications recently. However, LEDs generate high heat while operating. This heat must be removed from the product so that the life of the LEDs can be extended and the operating performance can be increased. In other words, the LED junction temperature must be kept within the appropriate operating range. Therefore, copper, aluminum, and ceramic heat sinks are commonly used to remove heat from LEDs.

There are generally three ways to increase heat transfer; a) expanding the surface area, b) increasing the path length of the fluid, and c) using a product with a high thermal conductivity coefficient. In addition to these; creating turbulence on the fluid with the help of a fan and increasing the fluid mass flow rate also increase the heat distribution performance, which is called forced convection. These criteria are also taken into account when designing the heat sink. In heat sinks, having close temperature values at every point of the heat sink; that is, the fins at the furthest point of the product are also required to work. Traditionally, in pin fin heat sinks, geometric changes are attempted on the pin fin.

Users, especially gaming computer users, want heat sinks to provide visuality in addition to their performance-enhancing effects, so the demand for visual and illuminated products is increasing.

BRIEF DESCRIPTION OF THE INVENTION

The heat sink, which is the subject of the invention, comprises a base plate (10) and a thin plate (12) tapering towards the edges in contact with the product to be heat removed, and with a convex (11), and a plurality of Y-type center fins (21) extending substantially vertically above this base, a plurality of pin-type wavy fins (20), further comprising V-type side fins (22); also, it has two-channel, multi-channel and without channel embodiments.

In the product without a channel, the fins have plate-type wavy fins, while the channeled product has pin-type wavy fins. Alternatively, even if the product is produced without channels, channels can be opened depending on the intended use of the product and optionally. Thus, a product without a channel can be shaped to serve different purposes. The production of products with and without channels can be carried out by known methods such as wire erosion, extrusion, casting, or additive manufacturing. In the product without a channel, while the mass increases significantly, however, its heat dissipation performance drops slightly compared to the channeled product in Figure 4. As the number of channels increases, the performance of the heat sink increases accordingly, but after the optimum number is exceeded, the performance reverses. For this reason, the heat sink is designed with at least two channels and at most five channels, which are determined in optimum geometry so that the channel and fin lengths are equal. Since it will significantly affect the heat distribution in the middle part of the product, that is, in the center of the heat source, one duct cannot be placed (it can be placed on the edge areas of the product, but in this case, it will create an imbalance by disrupting the thermal balance), it has been found appropriate to produce the product with at least two channels, since it cannot be made with a single channel. However, the invention is designed with a maximum of five channels to equally share the fin width and channel width, which ensures the strength of the heat sink, effective air circulation, and optimum design in heat dissipation.

LIST OF FIGURES

Figure 1. Left side view Figure 2. Top view Figure 3. Side View

Figure 4. 3D view of the heat sink

Figure 5. Double fin structure of the heat sink

Figure 6. 3D view of the heat sink without channel

Figure 7. Maximum surface temperatures and thermal resistances on the heat sink against the heat power applied in natural convection

Figure 8. Maximum and average surface temperatures on the heat sink against the applied heat power

Equivalents of numbering used in figures: 10. Base plate

11. Convex

12. Thin plate

12.1. Mounting space for additional apparatus 20. Wavy fins 21. Y-type center fins

22. V-type edge fins

23. Channel DETAILED DESCRIPTION OF THE INVENTION

The heat sink, which is the subject of the invention, comprises a base plate (10) and a thin plate (12) tapering towards the edges in contact with the product to be heat removed, and with a convex (11), and a plurality of Y-type center fins (21) extending substantially vertically above this base, a plurality of pin-type wavy fins (20), further comprising V-type side fins (22); also, it has two-channel (Not shown in the figures) (23), multi-channel (23) and without channel (Figure 6) embodiments (Figures 2-4). In the product without a channel, the fins have plate-type wavy fins, while the channeled product has pin-type wavy fins. Alternatively, even if the product is produced without channels, channels can be opened depending on the intended use of the product and optionally. Thus, a product without a channel can be shaped to serve different purposes. The production of products with and without channels can be carried out by known methods such as wire erosion, extrusion, casting, or additive manufacturing. In the product without a channel (Figure 6), while the mass increases significantly, however, its heat dissipation performance drops slightly compared to the channeled product shown in Figures 2-4. As the number of channels increases, the performance of the heat sink increases accordingly, but after the optimum number is exceeded, the performance reverses. For this reason, the heat sink is designed with at least two channels and at most five channels, which are determined in optimum geometry so that the channel and fin lengths are equal. Since it will significantly affect the heat distribution in the middle part of the product, that is, in the center of the heat source, one duct cannot be placed (it can be placed on the edge areas of the product, but in this case, it will create an imbalance by disrupting the thermal balance), it has been found appropriate to produce the product with at least two channels, since it cannot be made with a single channel. However, the invention is designed with a maximum of five channels to equally share the fin width and channel width, which ensures the strength of the heat sink, effective air circulation, and optimum design in heat dissipation.

In the creation of the invention, the cooling of electronic components such as chips and LEDs, which are among the possible areas of use, was taken into consideration and it was foreseen that the product subject to the patent could keep the product to be cooled under the expected junction temperatures.

To reduce the temperature gradient between the Y-type center fins (21 ) and the V-type side fins (peripheral pins) (22) of the invention, and due to the center of the heat sink being typically warmer than the outer fins, the surface area of the fins has been increased (Figure 1). Considering this situation, in order to provide strength and dissipate heat at the maximum level;

- Distributed to form an arc of 180-degree, the initial body at the base in a Y shape that will create a maximum thickness of two millimeters and followed by Y-type center fins with a two-finned structure (21) (Figure 5) and V- shaped side fins (22) in V-shape with a two-finned structure directly from the base without an initial fuselage,

- and an eight-millimeter high convex (11) to provide optimum heat distribution, a base (20), which is in contact with the component in a way that does not allow an air layer that will create thermal resistance between it and the component.

Y-type center fins (21) and V-type edge fins (22) are distributed on the 180- degree arc created instead of being placed perpendicular to the base plate (20), they were placed in a configuration that facilitates heat dissipation, by spreading the fins in a broad structure, that is, at an angle from the center to the edges.

In order to facilitate the mounting of the fan on the product and to draw as much heat as possible from the regions close to the center, a structure was created that allows the use of the upper corner points of the fins. That is, the upper points of the fins are designed to form a rectangular prism. Thus, the necessary equipment can be placed on the smooth prism formed and the fin length can be utilized to the maximum extent. In addition, a two mm wide area (12.1) extending diagonally to the channels (23) has been created on both sides of the heat sink, which allows the installation of fan connectors when necessary for forced airflow (Figure 2). Thus, an area has been created for the plastic parts on which the fan is attached or the metal parts connected to this plastic part to be easily placed on the heat sink, and it has also been possible to use mounting apparatus such as spring push pins.

The wave-free length of the Y-type center fins (21 ) in the middle part of the heat sink is provided with a maximum of 42 mm. This value has been determined as the length that does not exceed the fin height of a standard product, in a thickness that will provide the required strength, and that will provide optimum air passage between the fins, and therefore optimum cooling. If the fin length is longer, a thicker structure will be required to provide the same strength, thus preventing the airflow between the fins. And again, the fins used in the invention are shaped to form waves (tree) for technical reasons such as increasing the surface area and creating turbulence in the cooling fluid.

• Reducing the fin thickness reduces the aluminum mass, and when the thickness is increased, the duct thicknesses are optimized to a maximum of two mm, as the cooling capacity of the heat sink will decrease as a result of the narrowing of the channels and the decrease in air circulation.

• A decreasing volume gap was created from the fin tips to the base in order to break the resistance against the air in the forced airflow and to reach the fin bottoms and the base of the air. But in both natural and forced flow, so that the cooling fluid can remove more heat between the surfaces of the fins close to the center (hottest point), in areas close to the base center, a higher rate of gaps was formed between the fins than the other fin gaps. This is why the Y-type center fins (21 ) are formed in a Ύ” form. Thus, in areas close to the heat source, more heat can be removed from the high-temperature base and convex.

• In order for the cooling fluid to pass between the fin surfaces more easily and to transfer heat, there are spaces between both fins that are higher than the fin width.

• The fins, which are farthest from the center of the heat sink, are kept short as they cannot take an active role in heat dissipation.

The concept of thermal resistance, defined as temperature rise per unit of power, expressed in Celsius per Watt (°C/W) and used to calculate heat removal from the power element, is often used in determining the performance of heat sinks. The lower the thermal resistance of the product, the greater the heat-carrying capacity of the product. Figure 7 shows the maximum surface temperatures and thermal resistances on the heat sink against the applied heat power under natural convection. According to the figure, as the applied heat power increases, the maximum base temperatures increase, while the maximum thermal resistance values decrease. This means that this heat sink can be used without any problems at the heat power values given in the graph. Figure 8 shows the maximum and average surface temperatures on the heat sink against the applied heat power. In the figure, it is seen that both temperatures increase in a strong linear relationship as the heat power applied to the base increases. In addition, since the heat transmission coefficients of the materials used as heat sinks are high, the maximum and average surface temperatures formed on the heat sink are very close to each other. However, it is seen that the difference between the maximum and average temperatures slightly increases as the heat power applied to the base increases. This can be taken into account in sensitive applications.

Claims

1. A heat sink with tree-structured fins characterized by comprising a base plate (10) and a thin plate (12) tapering towards the edges in contact with the product to be heat removed, and with a convex (11 ) and a plurality of pin-type wavy fins (20) further comprising a plurality of Y-type center fins (21) and V-type side fins (22) extending substantially vertically above this base.

2. The heat sink with tree-structured fins of Claim 1 characterized by comprising one of the “without channel” and “at least two channels and at most five channels” structures type.

3. The heat sink with at least two channels and at most five channels with tree- structured fins of Claim 2 characterized by sharing the fin width and channel width equally.

4. The Y-type center fins (21) of Claim 1 characterized by being distributed on a 180-degree arc with an angle from the center to the edges and comprising a thickness of maximum two millimeters, an initial body at the base and a two- finned structure afterwards.

5. The Y-type center fins (21 ) of Claim 4 characterized by comprising a maximum wave-free length of 42 millimeters.

6. The V-type center fins (22) of Claim 1 characterized by being distributed on a 180-degree arc with an angle from the center to the edges and comprising a thickness of maximum two millimeters, a two-finned structure directly from the base without an initial fuselage.

7. The convex (11) of Claim 1 characterized by comprising a height of eight millimeters to provide optimum heat distribution.

8. The heat sink with tree-structured fins of any Claims above characterized by the upper points of the fins form a rectangular prism.

9. The heat sink with tree-structured fins of any Claims above characterized by comprising spaces between each two fins higher than the fin width.