heat sink

Abstract

The embodiments herein relate to a heat sink for a wireless unit. The heat sink (200) comprises a base (201) having a surface and a central longitudinal axis (A1), the surface comprising a first portion (202) and a second portion (204) disposed along the central longitudinal axis (A1) such that the first portion (202) is above the second portion (204). The heat sink further comprises a first plurality of protruding members (212) extending from the first portion (202) of the surface, the protruding members from the first plurality of protruding members (212) being fully extended along the surface across the first portion (202) parallel to each other and to the central longitudinal axis (A1), the first plurality of protruding members (212) being uniformly spaced along the first portion (202). The heat sink includes a second plurality of protruding members (214) extending from a second portion (204) of the surface, wherein at least some or some of the second plurality of protruding members (214) extend straight along the surface and are configured at an angle relative to the first plurality of protruding members (212).

Description

[Technical field]

[0001] FIELD OF THE DISCLOSURE Embodiments herein relate to heat sinks, and in particular to heat sinks for wireless units such as remote wireless devices. [Background technology]

[0002] Proper operation of modern electronic devices often requires a way to dissipate heat generated by the electronic components of the device. Thus, thermal management of electronic devices becomes increasingly important. For example, remote radio units (RRUs) are widely used in third generation mobile communication technologies to convert optical signals into radio frequency signals and perform signal amplification. RRUs may be located on cell towers and may generate excessive amounts of heat during operation and thus have increasing thermal demands. Adequate cooling is required to maintain the reliability and functionality of the RRUs and to increase their lifespan.

[0003] Heat sink devices, or heat sinks, are often used to dissipate heat in devices that include electronic components, such as RRUs. Heat sinks are generally passive heat exchanger devices that function to regulate the temperature of electronic and / or mechanical devices by absorbing heat and dissipating it away from the device to the surroundings. Heat sinks transfer heat from heat-generating components to air (or liquid coolant), allowing the heat to dissipate away from the device.

[0004] Although various designs of heat sinks exist, there remains a need for heat sinks having structures that are efficient in dissipating heat and have other beneficial characteristics. Summary of the Invention

[0005] As part of developing the embodiments herein, one or more problems were identified. In particular, electronic devices, e.g., processing units such as RRUs, are often generally constrained in terms of size and have thermal demands that increase over time. At the same time, wind-driven acoustical noise that may be generated by heat sinks coupled to electronic devices also becomes an issue, e.g., due to the effect of the geometric uniformity and size of existing heat sinks.

[0006] Conventional heat sinks generally have fins that extend uniformly vertically along the base of the heat sink. The RRU may be exposed to ambient winds moving from different directions and at different speeds. When the wind moves over the RRU or another object with the heat sink, the cavities between the cooling fins of the heat sink may cause a high-pitched whistling noise. The frequency of the whistling noise is within the range audible to humans and animals, resulting in environmental and health concerns. Moreover, remote wireless products are directly exposed to the environment and are therefore affected by atmospheric wind conditions, which may lead to the extension of some acoustic frequencies that act as an obstacle to nearby settlements.

[0007] Various existing heat sinks are implemented to either address thermal performance or to reduce wind induced acoustic noise (or address other concerns), rather than both thermal performance and noise generation.

[0008] Thus, embodiments of the present disclosure provide a heat sink that simultaneously both improves thermal performance and provides wind induced acoustic noise attenuation / reduction. The heat sink provided herein is a unique natural convection heat sink structure / system, referred to as a hybrid heat sink or interchangeably a heat sink. The heat sink is optimized to operate with less noise than existing heat sinks and may therefore be referred to as a silent hybrid heat sink.

[0009] In an aspect of the disclosure, a heat sink for a wireless unit is provided, the heat sink comprising a base having a surface and a central longitudinal axis, the surface comprising a first portion and a second portion disposed along the central longitudinal axis such that the first portion is above the second portion. The heat sink also comprises a first plurality of protruding members, interchangeably referred to as fins, and a second plurality of protruding members. Thus, the heat sink comprises a first plurality of protruding members extending from a first portion of the surface, the protruding members from the first plurality of protruding members being fully elongated along the surface throughout the first portion, parallel to each other and to the central longitudinal axis, the first plurality of protruding members being uniformly spaced along the first portion. The heat sink further comprises a second plurality of protruding members extending from a second portion of the surface, wherein at least part or some of the second plurality of protruding members extend straight along the surface and are arranged at an angle relative to the first plurality of protruding members.

[0010] Thus, the heat sink may be constructed from two main structural parts, a first part with fins or protruding members as in a conventional heat sink, and a second part with fins angled relative to the fins in the main part and with channels extending therethrough. The fins in the second part may form two separate sets of fins, with the fins in one set angled inward and upward relative to the fins in the other set, i.e., inward and upward from the lower left corner of the second part and inward and upward from the lower right corner of the second part. The first part with fins as may be found in a conventional setup serves to provide thermal cooling, and the second part serves to cool and reduce noise that may be generated by the heat sink during operation. Thus, the first and second parts work together to improve or maximize analog component performance while reducing the impact of analog components on digital components and providing more cooling potential to the digital components. The implementations provided allow for reduced heat sink weight, improved acoustic attenuation, and facilitate fan flow.

[0011] The heat sink according to the embodiments of the present disclosure provides an effective way to both attenuate / break up wind induced acoustic noise and improve the thermal performance of the heat sink system without reducing the thermal potential of cooling critical analog components and improve the thermal performance of the digital components of the equipment employing the heat sink. The heat sink has a robust flow path definition by having additional flow paths on the side inlets of the heat sink structure, which reduces the effects of possible flow obstructions. Furthermore, the side access inlets for the heat sink further allow for extended cooling from outdoor wind variations.

[0012] Embodiments will now be described in more detail with reference to the enclosed drawings. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 shows a diagram of a portion of a conventional heat sink and illustrates, in a simplified manner, the generation of whistling noise due to wind. [Diagram 2] FIG. 1 is a front view of a conventional heat sink. [Diagram 3] FIG. 2 illustrates a front view of a heat sink according to an embodiment of the present disclosure. [Figure 4] 1A-1C show front views of a conventional heat sink (A), a heat sink with an alternative configuration (B), and a heat sink according to an embodiment of the present disclosure (C). [Diagram 5] FIG. 2 illustrates another diagram showing a front view of a heat sink according to an embodiment of the present disclosure. [Figure 6] FIG. 2 illustrates a perspective side view of a heat sink according to an embodiment of the present disclosure. [Figure 7] FIG. 7 illustrates a perspective view of a portion of the fin of the heat sink of FIG. 6, showing the angle of inclination of the portion of the fin due to channels formed in the fin. [Figure 8A] 8A and 8B, respectively, show the shapes of the upper and lower portions of the central channel and the shape of the side channel (FIG. 8C), and are schematic diagrams illustrating the shapes of the channels extending through the fins in the heat sink of FIG. [Figure 8B] 8A and 8B, respectively, show the shapes of the upper and lower portions of the central channel and the shape of the side channel (FIG. 8C), and are schematic diagrams illustrating the shapes of the channels extending through the fins in the heat sink of FIG. [Figure 8C] 8A and 8B, respectively, show the shapes of the upper and lower portions of the central channel and the shape of the side channel (FIG. 8C), and are schematic diagrams illustrating the shapes of the channels extending through the fins in the heat sink of FIG. [Figure 9A] 9A and 9B are schematic diagrams illustrating the airflow path through a conventional heat sink and the airflow path through a heat sink according to an embodiment of the present disclosure. [Figure 9B]9A and 9B are schematic diagrams illustrating the airflow path through a conventional heat sink and the airflow path through a heat sink according to an embodiment of the present disclosure. [Figure 10] FIG. 2 illustrates a perspective side view of a heat sink according to an embodiment of the present disclosure. [Figure 11] 1A-1C show perspective views of example heat sinks in panels A and B according to embodiments of the present disclosure. [Figure 12] FIG. 12 is another perspective view of the heat sink of FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] The embodiments herein relate to a heat sink, also referred to as a hybrid heat sink, that comprises a base having a first upper portion and a second lower portion, with a fin configuration extending from the first portion that is different from the fin configuration extending along the second portion. These two structural parts of the heat sink allow for both improving the thermal performance of the heat sink and attenuating / reducing wind induced acoustic noise that may be generated in the heat sink.

[0015] FIG. 1 shows a schematic of how whistling noise can be generated in a heat sink 100, such as in a conventional natural convection heat sink. The heat sink may be a passive heat sink, where the buoyancy of hot air alone causes the airflow generated across the heat sink. As shown in FIG. 1, as wind 104 travels over the protruding members or fins 106 and 108, such as cooling fins or fins for short, of the heat sink 100, the flow of wind 104 splits over the first fin 106 and the second fin 108, thereby causing a vortex 110. When the vortex 110 hits the second fin 108, a pressure fluctuation 112 can be produced. If the pressure fluctuation 112 is caused by a wind having a certain wind speed, the pressure fluctuation 112 can cause an acoustic feedback loop 114, thereby causing a whistling noise. This noise is audible to humans, animals, and birds, and therefore may be a significant limiting factor during the use of a heat sink such as the heat sink 100.

[0016] 2 shows a front view of a conventional heat sink 100, illustrating the fins 103 extending on a surface of the base 101 along the longitudinal axis A of the base 101 of the heat sink 100. The heat sink 100 may be, for example, a natural convection heat sink. In use, the heat sink 100 may be disposed vertically, with gravity g (vertical force) being shown in FIG. 2 for illustrative purposes. The fins 103 in the conventional heat sink 100 are uniformly spaced along the base 101 such that the fins 103 form parallel rows of fins along the base 101.

[0017] In a conventional heat sink, such as the heat sink 100 shown in FIG. 2, heat may be spread with high efficiency from a heat source, e.g., a high density heat source, through a standard straight fin structure. In this case, the high density heat source needs to spread heat downwards to be cooled more efficiently. However, this has a detrimental effect on the cooling potential of components disposed lower along the path of heat dispersion, e.g., digital components. To improve the condition of the lower components (e.g., digital components) and still utilize, at least in part, the strength of conventional heat sink structures, a heat sink structure according to an embodiment of the present disclosure is provided herein. The heat sink comprises a base having a surface and a central longitudinal axis, the surface comprising a first portion and a second portion disposed along the central longitudinal axis such that the first portion is above the second portion. The heat sink further comprises a first plurality of protruding members extending from a first portion of the surface, the protruding members from the first plurality extending parallel to each other and to the central longitudinal axis, fully across or across the first portion along the surface, and the first plurality of protruding members being uniformly spaced along the first portion. The heat sink also comprises a second plurality of protruding members extending from a second portion of the surface, at least some or some of the protruding members of the second plurality extending straight along the surface and configured at an angle relative to the first plurality of protruding members.

[0018] Thus, in a heat sink constructed using a combination of fins in a conventional configuration and angled fins, the angled fin structure, sometimes referred to as a delta part or section, is configured to change the heat transfer dynamics in both the conduction path and the air flow path. Thus, less heat is transferred to the bottom side of the heat sink because of the cooler air and improved inflow properties, such as a larger inlet area altogether, bottom plus side as inlet, rather than just the bottom as in a conventional heat sink, more heat is conducted to the sides where it is dissipated more efficiently. The bottom part is generally cooler since heat is not conducted downward as in existing systems, thereby reducing the impact from analog components on digital components. In embodiments herein, this bottom part can be further enhanced by forming channels or cuts in the fins of the bottom part, as described in more detail below with reference to FIG. 4 (panel C), FIG. 5, FIG. 6, FIG. 9B, FIG. 10, FIG. 11, and FIG. 12.

[0019] FIG. 3 shows a front view of a hybrid heat sink 200 according to an embodiment of the present disclosure. The heat sink 200 comprises a base plate or base 201 having a surface and a central longitudinal axis A1. The surface is not separately labeled herein as it coincides with the base 201 in FIG. 3, and comprises a first portion 202 and a second portion 204 disposed along the central longitudinal axis A1 such that the first portion 202 is above the second portion 204. The heat sink 200 also comprises a first plurality of protruding members or fins 212 and a second plurality of protruding members or fins 214. The first plurality of protruding members 212 and the second plurality of protruding members 214 may be plates, e.g., metal plates, having a uniform height throughout their length. The first plurality of protruding members 212 have the same length. The protruding members from the second plurality of protruding members 214 may have different lengths, as shown in FIG. 3.

[0020] The first portion 202 having the first plurality of protruding members 212 serves to provide thermal cooling. The second portion 204 having the second plurality of protruding members 214 is configured to reduce or attenuate acoustic noise that may be generated by wind or other air movement.

[0021] The first plurality of protruding members 212 extend from the first portion 202 of the surface, and the protruding members from the first plurality of protruding members 212 extend substantially parallel to each other and to a longitudinal axis of the heat sink 200, such as the central longitudinal axis A1, along the surface across or across the first portion 202. The protruding members from the first plurality of protruding members 212 may extend substantially parallel to each other along the surface, i.e., they are parallel or parallel within an angular interval, such as within an angular interval due to manufacturing variations, tolerances, and imprecision. The first plurality of protruding members 212 are substantially straight (i.e., straight or straight within an angular interval, such as within an angular interval due to manufacturing variations, tolerances, and imprecision) and uniformly spaced along the first portion 202. As shown in FIG. 3, the first plurality of protruding members 212 extend along the surface in parallel rows in a manner that is the same as or similar to the protruding members 103 of the conventional heat sink 100 of FIG.

[0022] The second plurality of protruding members 214 extend from the second portion 204 of the surface. As shown in Fig. 3, at least some or some of the protruding members of the second plurality of protruding members 214 are configured to extend straight along the surface and angled relative to the first plurality of protruding members 212. The protruding members from the second plurality of protruding members 214 may be in the form of elongated plates, the surfaces of which are perpendicular to the surface of the base 201, and which are disposed on the second portion 204 of the surface in an angled manner relative to the first plurality of protruding members 212.

[0023] For example, along the horizontal axis B1, there may be a space between the second plurality of protruding members 214 and the first plurality of protruding members 202. That space may be infinitesimally small. Alternatively, some or all of the protruding members from the first plurality of protruding members 212 may extend further along the second portion 204 of the base 201 in an angled setting such that they each also form a projection member of the second plurality of protruding members 214.

[0024] In an embodiment, first plurality of protruding members 212 and second plurality of protruding members 214 are perpendicular to a surface of base 201. By way of example, a number of protruding members are shown in FIG. 3. Heat sink 200, as well as other heat sinks according to embodiments of the present disclosure, may include any suitable number of protruding members of first plurality of protruding members 212 and any suitable number of protruding members of second plurality of protruding members 214.

[0025] As further shown in Figure 3, the second plurality of protruding members 214 comprises two sets of protruding members, shown on the left and right sides, respectively, that are angled inwardly and upwardly relative to one another, i.e., toward the central longitudinal axis A1. In Figure 3, the fins in one set extend along the base 201 such that the fins are angled inwardly and upwardly from the left side of the base 201, and the fins in the other set extend along the base 201 such that the fins are angled or tilted inwardly and upwardly from the right side of the base 201. It should be noted that the protruding members of the second portion 204 may also be considered to extend outwardly and downwardly away from the part of the central longitudinal axis A1 that extends through the second portion 204.

[0026] The second portion 204 of the surface of the base 201 comprises a third portion 206 and a fourth portion 208. A third plurality of protruding members 216 extends from and along the third portion 206 and a fourth plurality of protruding members 218 extends from and along the fourth portion 208, with the third plurality of protruding members 216 and the fourth plurality of protruding members 218 angled inwardly and upwardly relative to one another.

[0027] 3, the third plurality of protruding members 216 of the third portion 206 and the fourth plurality of protruding members 218 of the fourth portion 208 extend along a surface of the second portion 204 such that a central channel 220 is formed along a central longitudinal axis A1. Note that the central longitudinal axis A1 coincides with the longitudinal axis of the base 201 (not shown), and that the central longitudinal axis A1 is shown to illustrate the symmetry of the third plurality of protruding members 216 and the fourth plurality of protruding members 218 relative to the centerline of the base surface of the heat sink 200.

[0028] The central channel 220 extends between the third plurality of protruding members 216 and the fourth plurality of protruding members 218. The central channel 220 is free of protruding members, and the central channel 220 generally has an inverted trapezoid shape, i.e., may be a strict trapezoid or a trapezoid with some possible small variation from a strict trapezoid shape, e.g., may have a trapezoidal concave side. The shape of the central channel 220 and the portion formed by the channel from the protruding members may also vary due to manufacturing variations. The shape of the central channel 220 may be different in various implementations of the heat sink 200, but the general shape is still an inverted trapezoid. The longitudinal axis (not shown) of the central channel 220 may coincide with the central longitudinal axis A1. The central channel 220 may have a width at its widest part, i.e., at the top, of about 1% to about 10% of the width of the base 201, the width of the base 201 being measured along an axis perpendicular to the central longitudinal axis A1.

[0029] Additionally, it should be appreciated that the topology of the second plurality of protruding members 214, including the third plurality of protruding members 216 and the fourth plurality of protruding members 218, may differ from the topology shown in Figure 3. Additionally, the size and number of channels formed in the third plurality of protruding members 216 and the fourth plurality of protruding members 218 may vary. The number of protruding members in the first plurality of protruding members 212 and the number of protruding members in the second plurality of protruding members 214 may also vary depending on the particular implementation of a heat sink 200 according to an embodiment of the present disclosure.

[0030] The first portion 202 and the second portion 204 may have substantially the same length or height as measured along the central longitudinal axis A1 of the base 201. For example, the first portion 202 may occupy about 50% of the base 201, and the second portion 204 may likewise occupy about 50% of the base 201, with the total length of the first portion 202 and the second portion 204 being considered to be 100%. As used herein, "about" means the number itself and within plus or minus 5% of the stated number. For example, about 50% means 50, and / or any number within the range of 47.5 to 52.5, inclusive. In some implementations, the first portion 202 may occupy about 60% of the base 201, and the second portion 204 may occupy about 40% of the base 201. In some implementations, first portion 202 may occupy approximately 40% of base 201 and second portion 204 may occupy approximately 60% of base 201. The length of first portion 202 and second portion 204 may depend on the details of the equipment or device in which heat sink 200 is used, the nature and requirements of the surrounding environment, and other factors.

[0031] Additionally, the spacing between the protruding members of the first plurality of protruding members 212 and the protruding members of the second plurality of protruding members 214 may depend on the type of device in which the heat sink 200 is used.

[0032] It should be appreciated that the heat sink 200 may have other components that are not shown here for clarity of presentation. The heat sink 200 may be coupled to a radio unit, such as an RRU, or any other device. The heat sink 200 may be used in a massive multiple-input multiple-output (MIMO) system.

[0033] Conventional heat sinks, for example, as shown in FIG. 2, are known to maximize cooling for bulk heat (e.g., temperatures at or about 100° C., a temperature range of 95° C. to 105° C., or other temperature ranges) generated, for example, by analog components, such as (high density) power transistors. However, conventional heat sinks may not assist in cooling digital components, for example, printed circuit board (PCB) components, such as, for example, field programmable gate arrays (FPGAs) and application specific integrated circuits (ASICs). The digital components may heat up to about 90° C. The first and second portions of a hybrid heat sink according to an embodiment of the present disclosure work together to maximize analog component performance while reducing the impact (by the analog components) on the digital components, for example, as shown in FIG. 3. For example, a reduction in the temperature of the digital components may be achieved such that the temperature is lowered, for example, by 5° C., resulting in an absolute temperature of about 85° C. In this manner, the impact of the analog components on the digital components is reduced, thereby improving the thermal performance of the digital components.

[0034] FIG. 4 shows a schematic of the acoustic and thermal design evolution for the heat sink. A general wind from the side direction for the heat sink is also shown schematic with respect to panel C, but the wind description is applicable to the heat sinks shown in panels A and B. FIG. 4 shows a conventional heat sink (panel A), a heat sink with an alternative configuration (panel B), and a hybrid heat sink (panel C) according to an embodiment of the present disclosure. In the examples herein, the conventional heat sink may be for the prior art, FIG. 2 radio, and the alternative configuration is referred to as the other prior art radio. As shown in FIG. 4, panel B, the alternative configuration of the heat sink may include only fins angled with respect to the longitudinal axis of the heat sink (not shown), and longitudinal channels may be formed in the fins. An example of a heat sink with an alternative or similar configuration is described in PCT / SE2018 / 050083, which is incorporated herein by reference in its entirety. While the alternative configuration may help with wind-induced noise, thermal performance may be adversely affected, i.e., reduced, by discontinuities in the fin configuration (where the fins are split into many smaller fins, thus losing useful fin area).

[0035] A heat sink with a conventional design, shown in Panel A of FIG. 4, generates wind-induced acoustic noise (distinct, troublesome frequencies) when wind blows from the side due to the uniformity of the structure. This requires modifications to the heat sink, which introduce non-uniformities to induce chaotic wind motion to attenuate the noise generation. One example of such a modification is the alternative configuration of the heat sink in Panel B of FIG. 4. However, this configuration adds design complexity and also reduces thermal performance.

[0036] A hybrid heat sink, as described herein, encompasses a combination of standard (or near-standard) and angled fins in accordance with an embodiment of the present disclosure. The hybrid heat sink structure has structural non-uniformities that allow for chaotic and unstable wind motion, which attenuates possible acoustic noise throughout the heat sink. For example, the heat sink shown in panel C of FIG. 4 (similar to heat sink 200 of FIG. 3 but including additional channels formed in the lower portion of the base) allows for both increased thermal performance and reduced wind-induced acoustic noise to be achieved. Moreover, the hybrid structure described herein does not require modifications to the typical fin geometry, which simplifies the manufacture of the heat sink.

[0037] FIG. 5 shows a front view of a heat sink 200a according to an embodiment of the present disclosure. The heat sink 200a is an example of the heat sink 200 (panel C) in FIG. 4. The heat sink 200a includes channels that extend through the fins or protruding members of the lower portion, thereby separating some of the fins into smaller portions. The channels act to separate wind or other air movement in an enhanced manner by providing an additional level of non-uniformity in the geometry. The channels also allow for a reduction in the weight of the heat sink.

[0038] As shown in Figure 5, heat sink 200a comprises a base plate or base 221 having a surface and a central longitudinal axis A2. The surface is not separately labeled herein as it coincides with base 221 in the description of Figure 5, and comprises a first portion 222 and a second portion 224 disposed along central longitudinal axis A2 such that first portion 222 is above second portion 224. Heat sink 200a also comprises a first plurality of protruding members or fins 232 and a second plurality of protruding members or fins 234.

[0039] The first plurality of protruding members 232 extend from the first portion 222 of the surface, and the protruding members from the first plurality of protruding members 232 extend substantially across the entire first portion along the surface, parallel to each other and to the central longitudinal axis A2. The first plurality of protruding members 232 are substantially straight, i.e., straight or straight within an angular interval, such as within an interval of about 1° to about 5°, which may be due to manufacturing variations, tolerances, and imprecision. The first plurality of protruding members 232 are uniformly spaced apart along the first portion 222. As shown in FIG. 5, the first plurality of protruding members 232 extend along the surface in parallel rows in a manner similar to the protruding members 103 of the conventional heat sink 100 of FIG. 2.

[0040] The second plurality of protruding members 234 extend from the second portion 224 of the surface. As shown in FIG. 5, at least some or some of the protruding members from the second plurality of protruding members 234 extend straight along the surface and are configured in an angled manner with respect to the first plurality of protruding members 232. For example, along the transverse axis B2, there may be a space between the second plurality of protruding members 214 and the first plurality of protruding members 202. For example, a space or channel may be formed along or approximately along the transverse axis B2 (i.e., near the transverse axis B2). The space may be infinitesimally small. Alternatively, some or all of the protruding members from the first plurality of protruding members 222 may further extend in an angled setting along the second portion 224 of the base 221 so as to also form a projection member of the second plurality of protruding members 234, respectively. In FIG. 3, the horizontal axis B2 is shown approximately where the boundary is between the first plurality of protruding members 222 and the second plurality of protruding members 234, the area being marked as 223.

[0041] Similar to heat sink 200 (FIG. 3), second portion 224 of the surface of base 201 includes third portion 236 and fourth portion 238. Third plurality of protruding members 246 extend from and along third portion 236. Fourth plurality of protruding members 248 extend from and along fourth portion 238. Third plurality of protruding members 246 and fourth plurality of protruding members 248 are angled upwardly and inwardly relative to one another, i.e., toward central longitudinal axis A2 and toward one another when viewed from a side of base 221.

[0042] As shown in FIG. 5, the third plurality of protruding members 246 of the third portion 236 and the fourth plurality of protruding members 248 of the fourth portion 238 extend along the surface of the second portion 224 such that a central channel 250 is formed along a central longitudinal axis A2. It should be noted that the central longitudinal axis A2 coincides with the longitudinal axis (not shown) of the base 221, and that the central longitudinal axis A2 is shown to show the symmetry of the third plurality of protruding members 246 and the fourth plurality of protruding members 248 with respect to the centerline of the base surface of the heat sink 200a. The central channel 250 generally has an inverted trapezoid shape. The exact shape of the central channel 250 may vary in various implementations of the heat sink 200a, but the general shape is still an inverted trapezoid. The central channel 250 may have a width at its widest part, i.e., at the top, of about 1% to about 10% of the width of the base 221.

[0043] The spacing between the second plurality of protruding members 234 (i.e., between rows of fins) may depend on the spacing between the first plurality of protruding members 232. In an embodiment, the spacing between protruding members of the second plurality of protruding members 234 is less than the spacing between corresponding protruding members of the first plurality of protruding members 232, and some of the protruding members of the second plurality of protruding members 234 are extensions of corresponding protruding members of the first plurality of protruding members 232.

[0044] In the heat sink 200a, as shown in FIG. 5, channels 252a, 252b, 252c, and 252d, collectively referred to as channels 252, are formed in the second plurality of protruding members 234. Channels 252a and 252b are formed in the third plurality of protruding members 246, and channels 252c and 252d are formed in the fourth plurality of protruding members 248. The channels 252 are formed such that some protruding members of the second plurality of protruding members 234 may not have channels extending therethrough. In some implementations, all of the protruding members of the second plurality of protruding members 234 may have channels extending therethrough. The channels may be formed through the entire surface of the protruding members such that a lower portion of the channel is formed by the surface of the base 221.

[0045] As shown in Fig. 5, channels 252a and 252b in the third plurality of projecting members 246 are formed such that channels 252a and 252b extend along a line that is angled slightly off to the left in Fig. 5 relative to central longitudinal axis A2. Similarly, channels 252c and 252d are formed in the fourth plurality of projecting members 248 such that channels 252c and 252d extend along a line that is angled slightly off to the right in Fig. 5 relative to central longitudinal axis A2. Channels 252a and 252b are formed symmetrically or nearly symmetrically with respect to channels 252c and 252d.

[0046] The configuration of the second plurality of protruding members or fins 234, and the configuration of channels formed in the second plurality of protruding members, allows for efficient air flow through the heat sink 200a.

[0047] It should be appreciated that the topology of the second plurality of protruding members 224, comprising the third plurality of protruding members 246 and the fourth plurality of protruding members 248, may differ from the topology shown in Figure 5. Additionally, the size and number of channels formed in the third plurality of protruding members 246 and the fourth plurality of protruding members 248 may vary as embodiments herein are not limited in this respect. The number of protruding members in the first plurality of protruding members 232 and the number of protruding members in the second plurality of protruding members 234 may also vary depending on the particular implementation of a hybrid heat sink according to an embodiment of the present disclosure.

[0048] Thus, the heat sink 200 for a wireless unit provided herein comprises: The heat sink comprises a base 201 having a surface and a central longitudinal axis A1, the surface comprising a first portion 202 and a second portion 204 disposed along the central longitudinal axis A1 such that the first portion 202 is above the second portion 204. The heat sink comprises a first plurality of protruding members 212 extending from the first portion 202 of the surface, the protruding members from the first plurality of protruding members 212 extending parallel to each other and to the central longitudinal axis A1, fully extending across the first portion 202 along the surface, the first plurality of protruding members 212 being uniformly spaced along the first portion 202. The heat sink further comprises a second plurality of protruding members 214 extending from the second portion 204 of the surface, wherein at least some or some of the protruding members of the second plurality of protruding members 214 extend straight along the surface and are configured at an angle relative to the first plurality of protruding members 212.

[0049] The second portion 204 may have a plurality of channels 252 , 352 formed through at least some of the protruding members of the second plurality of protruding members 214 .

[0050] The multiple channels may extend along axes that form an acute angle with respect to the central longitudinal axis A1.

[0051] One or more of the plurality of channels 252 may be configured with a trapezoidal shape, with a lower part narrower than an upper part of the one or more channels.

[0052] A first portion 202 for cooling the analog components may be configured above the second portion 204, thereby reducing the impact of the analog components on the digital components, thereby improving the thermal performance of the digital components.

[0053] The second portion 204 of the surface may include a third portion 206 and a fourth portion 208, and the second plurality of protruding members 214 includes a third plurality of protruding members 216 extending from the third portion 206 of the second surface and a fourth plurality of protruding members 218 extending from the fourth portion 208 of the second surface, the third plurality of protruding members 216 and the fourth plurality of protruding members 218 being angled inwardly and upwardly relative to one another.

[0054] The plurality of channels 252 may include a central channel extending between the third plurality of protruding members and the fourth plurality of protruding members. The central channel may have an axis that is coincident with the central longitudinal axis.

[0055] FIG. 6 illustrates a perspective side view of a heat sink 300 according to an embodiment of the present disclosure. The heat sink 300 is an example of the heat sink 200 of FIG. 3 and therefore will not be described in detail herein. As shown in FIG. 6, the hybrid heat sink 300 has a base 301 with a surface having a first upper portion 302 and a second lower or bottom portion 304. A first plurality of protruding members 312 having a configuration similar to a conventional heat sink extends from the first portion 302. A second plurality of protruding members 314 extends from the second portion 304, and channels 350 and 352 are formed in the protruding members 314. As shown in FIG. 6, the surfaces of the first plurality of protruding members 232 and the second plurality of protruding members 234 may be perpendicular to the surface of the base 221.

[0056] Although the boundary between the first and second plurality of protruding members 312, 314 is indicated by line 313, it should be appreciated that the change in shape of the protruding members from the first portion to the second portion may be continuous. In other words, a straight protruding member (in the first portion) may gradually become angled at the end of the first portion where the protruding member begins to become part of the second portion.

[0057] Channel 350 is a central channel between the projection members of the third portion 306 and the fourth portion 308 of the second portion 304. The central channel 305 may be symmetrical about a central longitudinal axis A3 of the base 301. The channel 352 comprises channels 352a, 352b, 352c, and 352d, where channels 352a and 352b are formed in the (third) protruding member of the third portion 306 and channels 352c and 352d are formed in the (fourth) protruding member of the fourth portion 308. It should be appreciated that five channels, including the central channel 350, are shown in FIG. 6 only as an example, as any suitable number of channels or cuts, e.g., less than five or more than five, may be formed through the fins of the second portion 304.

[0058] As shown in FIG. 6, some of the protruding members of the third portion 306 having a central channel 350 extending therethrough have corresponding, symmetrically arranged protruding members of the fourth portion 308 that also have a central channel 350 extending therethrough.

[0059] As shown in FIG. 6, the central channel 350 extending between the protruding members of the third portion 306 and the protruding members of the fourth portion 308 may have a generally inverted trapezoid shape, with the sides of the channel being concave such that an upper portion 350a of the channel 350 has a shape as shown in the example of FIG. 8A and a lower portion 350b of the channel 350 has a shape as shown in the example of FIG. 8B. An example of the shape of each of the channels 352, which may have the same or approximately the same shape and size, is shown in FIG. 8C. Thus, one or more of the channels 252, 352 may be configured with a trapezoid shape, with the lower part being narrower than the upper part of the one or more channels. The length of the channel 352, as measured along the central longitudinal axis A3 of the base 301, may be from about 5 mm to about 200 mm, or from about 5 mm to about 100 mm or about 70 mm. It should be noted that the shapes of channels 350a, 350b, and 352 in Figures 8A, 8B, and 8C, respectively, are shown to approximately the same scale for purposes of comparison.

[0060] 6, channels 350 and 352 are formed in the projecting member of second portion 304 such that the edges of the portions of the projecting member that form the channels are straight. However, it should be appreciated that the edges may be rounded or the edges may have other shapes.

[0061] 6, some of the protruding members do not have a channel formed therethrough. Thus, the five protruding members in the upper left corner of the third portion 306, collectively marked with reference numeral 360, are channel-less. Protruding member 362 has a channel 352a extending therethrough, with the upper, widest part of channel 352a formed in protruding member 362.

[0062] 6, the channels 350 can be configured such that the channels 350 extend at an acute angle relative to the central longitudinal axis A3 of the base 301. For example, as shown for channel 352a, the longitudinal axis 355 of the channel 352a extends at an acute angle relative to the central longitudinal axis A3.

[0063] The channels 352a may be formed through at least some of the protruding members from the protruding member 316, so that the resulting portions of the protruding members have a generally trapezoidal shape. Some of the protruding members may be divided into two or three (or other number, depending on the implementation) portions by the channels formed therethrough. The side edges of the resulting portions may be inclined as shown in FIG. 6. As shown in FIG. 7, by way of example, for a portion of the fin or protruding member 364 (also shown in FIG. 6), an angle α is formed between an axis a1 passing through the (right) side of the protruding member 364 and an axis a2 passing through the lower edge of the protruding member 364 disposed on the surface of the base 301. The angle α may range from about 10° to about 60°. In some embodiments, the angle α may be about 33°, but it should be appreciated that the angle α may have other values.

[0064] As explained above, the heat sink 200 according to the embodiment of the present disclosure introduces structural non-uniformity and thus chaotic and unstable wind motion, which attenuates possible acoustic noise throughout the heat sink. The efficiency of acoustic noise reduction can be improved in that the heat sink has a channel formed in its lower part, for example, as shown in FIG. 4 (panel C), FIG. 5 and FIG. 6. FIG. 9A and FIG. 9B show the wind path through a conventional heat sink (FIG. 9A) and the wind path through a hybrid heat sink according to the embodiment of the present disclosure (FIG. 9B). FIG. 9A and FIG. 9B show the general wind from the side direction, the bulk flow of air above the respective heat sink, and the relative flow structure. As shown in FIG. 9A for a conventional heat sink, shown as heat sink 100 (shown in FIG. 2) as an example, the wind can pass through the heat sink 100 with essentially no change in wind direction.

[0065] In contrast, as shown in FIG. 9B for a heat sink 200, shown as heat sink 200a (shown in FIG. 5) by way of example, the wind direction (903) entering the heat sink 200a through a side opening (caused by a channel formed through a protruding member in the lower portion of the heat sink 200a) is changed as the wind / air passes through the channel, as shown by arrow 905. The resulting chaotic and unstable wind motion reduces acoustic noise that may be generated in the heat sink 200a. Thus, the heat sink 200a has a robust flow path definition by having an additional flow path on the side inlet of the heat sink 200a, which reduces the effect of possible flow disturbances. Furthermore, the side access inlet for the heat sink 200a allows for extended cooling from outdoor wind fluctuations or other air movements. Due to the specific structure of the heat sink 200a, the wind direction entering the heat sink 200a through the side of the heat sink 200a is changed to some extent even in the upper portion of the heat sink 200a (907). In this way, both the heat transfer capacity and the noise reduction capabilities of the heat sink are improved.

[0066] 10 shows another example of a heat sink 200, such as a heat sink 1000 having a base 1001 and a first portion 1002 and a second portion 1004 on a surface of the base 1001, according to an embodiment of the present disclosure. The heat sink 1000 is similar to the heat sink 200a (FIG. 5) and the heat sink 300 (FIG. 6), but the channels extend through the protruding members of the second portion 1004 such that the edges of the protruding members are rounded. In this example, the second portion 1004 includes a third portion 1006 and a fourth portion 1008, and the channels 1050 (central channel), 1052a, 1052bm 1052c, and 1052d extend through at least some of the protruding members of the third portion 1006 and the fourth portion 1008.

[0067] It should be appreciated that the heat sink 1000, as well as other heat sinks described herein, have other components that may not be shown. Thus, FIG. 10 further illustrates that the heat sink 1000 includes mounting ports, such as a front mounting port 1015, a side mounting port 1017, and other ports (not shown), for attaching or mounting the heat sink 1000 to an object, such as a wireless unit, e.g., an RRU, or another device or equipment where heat is generated by its electronic components. The object may be located in any outdoor or indoor environment.

[0068] It should be appreciated that in embodiments herein, the height of the protruding members may be the same throughout the heat sink 200. Furthermore, due to factors such as manufacturing constraints, some of the protruding members may have different heights, which does not affect the thermal and noise reduction efficiency of the heat sink.

[0069] Figure 11 shows two examples of heat sinks according to embodiments herein, where the heat sink on the left (panel A) is similar to heat sink 1000 of Figure 10 and the heat sink on the right (panel B) is similar to heat sink 300 of Figure 6. Figure 12 shows another perspective view of the heat sinks of Figure 11. The heat sink on the left (panel A) is similar to heat sink 1000 of Figure 10 and the heat sink on the right (panel B) is similar to heat sink 300 of Figure 6.

[0070] Exemplary embodiments are summarized below. A1. A base having a surface and a central longitudinal axis, the surface comprising a first portion and a second portion disposed along the central longitudinal axis such that the first portion is above the second portion; a first plurality of protruding members extending from a first portion of the surface, the protruding members from the first plurality extending along the surface parallel to one another and to the central longitudinal axis, the first plurality of protruding members being uniformly spaced along the first portion; a second plurality of protruding members extending from a second portion of the surface, the protruding members from the second plurality of protruding members extending along the surface and angled relative to the first plurality of protruding members; A heat sink comprising:

[0071] A2. The second portion of the surface comprises a third portion and a fourth portion; the second plurality of protruding members comprises a third plurality of protruding members extending from a third portion of the second surface and a fourth plurality of protruding members extending from a fourth portion of the second surface, the third plurality of protruding members and the fourth plurality of protruding members being angled inwardly and upwardly relative to one another; The heat sink of embodiment A1.

[0072] A3. the second portion has a plurality of channels formed through at least some of the protruding members of the second plurality of protruding members; The heat sink of embodiment A2.

[0073] A4. The heat sink of embodiment A3, wherein the multiple channels extend along an axis that forms an acute angle with the central longitudinal axis.

[0074] A5. The heat sink of embodiment A3 or embodiment A4, wherein the plurality of channels includes a central channel extending between the third plurality of protruding members and the fourth plurality of protruding members.

[0075] A6. The heat sink of embodiment A5, wherein the central channel has an axis coincident with the central longitudinal axis.

[0076] It will be appreciated that the above description and accompanying drawings represent non-limiting examples of the apparatus taught herein. Thus, the apparatus and techniques taught herein are not limited by the above description and accompanying drawings. Instead, embodiments herein are limited only by the following claims and their legal equivalents.

Claims

1. A heat sink (200) for a wireless unit, said heat sink (200) comprising: a base (201) having a surface and a central longitudinal axis (A1), the surface comprising a first portion (202) and a second portion (204) disposed along the central longitudinal axis (A1) such that the first portion (202) is above the second portion (204); a first plurality of protruding members (212) extending from said first portion (202) of said surface, said protruding members from said first plurality of protruding members (212) extending substantially across said first portion (202) along said surface, parallel to one another and to said central longitudinal axis (A1), said first plurality of protruding members (212) being uniformly spaced along said first portion (202); a second plurality of protruding members (214) extending from the second portion (204) of the surface, at least some or some of the second plurality of protruding members (214) extending straight along the surface and angled relative to the first plurality of protruding members (212); A heat sink (200).

2. the second portion (204) having a plurality of channels (252, 352) formed through at least some of the second plurality of projecting members (214); The heat sink of claim 1 .

3. The heat sink of claim 2, wherein the plurality of channels (252) extend along an axis that forms an acute angle with the central longitudinal axis (A1).

4. The heat sink of claim 2 or 3, wherein one or more of the plurality of channels (252) are configured with a trapezoidal shape with a lower part narrower than an upper part of the one or more channels.

5. 5. The heat sink of claim 1, wherein the first portion (202) for cooling analog components is configured above the second portion (204), thereby reducing an impact of the analog components on digital components, thereby improving thermal performance of the digital components.

6. the second portion (204) of the surface comprises a third portion (206) and a fourth portion (208); the second plurality of protruding members (214) comprising a third plurality of protruding members (216) extending from the third portion (206) of the second surface and a fourth plurality of protruding members (218) extending from the fourth portion (208) of the second surface, the third plurality of protruding members (216) and the fourth plurality of protruding members (218) being angled inwardly and upwardly relative to one another; A heat sink according to any one of claims 1 to 5.

7. The heat sink of any one of claims 2 to 5 and 6, wherein the plurality of channels (252) comprises a central channel extending between the third plurality of protruding members and the fourth plurality of protruding members.

8. The heat sink of claim 7 , wherein said central channel has an axis coincident with said central longitudinal axis.

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