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Title:
HEAT SINK CLAMPING DEVICE
Document Type and Number:
WIPO Patent Application WO/2019/173303
Kind Code:
A1
Abstract:
A heat sink assembly includes a heat sink configured to be attached to an electronic assembly and to secure at least one component package thereto and at least one clamping device configured to be secured to the heat sink and to engage the at least one component package. The heat sink includes a connecting feature and the at least one clamping device includes a mating connecting feature. The heat sink assembly further includes at least one fastener to engage the at least one clamping device. The connecting feature of the heat sink is configured to releasably secure the mating connecting feature of the at least one clamping device therein to releasably secure the at least one clamping device to the heat sink.

Inventors:
KUMARSWAMY, Chandankumar (#831 37th Cross, 20TH Main4TH "T" Block, Jayanagar, Bangalore 1, 560041, IN)
SIVANPANDIAN, Nellaiappan (Flat #403, Shravanthi Pride-12ND Main, 12TH "A" Cross,J.P. Nagar 3RD Phase, Bangalore 8, 560078, IN)
MOORTHI, Ganesh (Ahad Euphoria, Wing-9 101,Chikkakaenahalli, Sarjapur Road, Bangalore 5, 560035, IN)
KUMAR, Santhosh, G. (No. 28 3rd Floor, 5th House 9th Main,Behind Manjushree Wines Building,A. Dasarahalli, Bangalore 9, 560079, IN)
Application Number:
US2019/020703
Publication Date:
September 12, 2019
Filing Date:
March 05, 2019
Export Citation:
Click for automatic bibliography generation   Help
Assignee:
SCHNEIDER ELECTRIC IT CORPORATION (132 Fairgrounds Road, West Kingston, RI, 02892, US)
International Classes:
H01L23/40
Foreign References:
DE3446569A11986-07-03
US5077638A1991-12-31
EP2737526A12014-06-04
US20160073549A12016-03-10
Other References:
None
Attorney, Agent or Firm:
NOE, Keith, F. et al. (Lando & Anastasi, LLPRiverfront Office Park, One Main Street,Suite 110, Cambridge MA, 02142, US)
Download PDF:
Claims:
CLAIMS

1. A heat sink assembly comprising:

a heat sink configured to be attached to an electronic assembly and to secure at least one component package thereto, the heat sink including a connecting feature;

at least one clamping device configured to be secured to the heat sink and to engage the at least one component package, the at least one clamping device including a mating connecting feature; and

at least one fastener to engage the at least one clamping device to the heat sink, wherein the connecting feature of the heat sink is configured to releasably secure the mating connecting feature of the at least one clamping device therein to releasably secure the at least one clamping device to the heat sink.

2. The heat sink assembly of claim 1, wherein the heat sink includes an upright body portion and a top flange portion that extends perpendicularly from the body portion.

3. The heat sink assembly of claim 2, wherein on one side of the body portion of the heat sink, the heat sink further includes a plurality of fins that are spaced apart from one another and extend horizontally from the body portion, and on an opposite side of the body portion, the heat sink further includes a plurality of fins that are spaced apart from one another and extend horizontally from the body portion.

4. The heat sink assembly of claim 3, wherein the top flange portion includes at least one threadable opening, the at least one fastener being threadably received within the at least one threadable opening to apply a clamping force on the at least one clamping device against the at least one component package.

5. The heat sink assembly of claim 2, wherein the connecting feature of the heat sink includes a channel formed at an intersection of the body portion and the top flange portion, the channel extending along a length of the heat sink and being accessible through two open ends provided at the ends of the heat sink.

45

6. The heat sink assembly of claim 5, wherein the at least one clamping device further includes an upright body segment and a top flange segment that extends

perpendicularly from the body segment.

7. The heat sink assembly of claim 6, wherein the top flange segment of the at least one clamping device includes an engagement surface that is provided to engage the at least one fastener through a threadable opening in the top flange portion of the heat sink.

8. The heat sink assembly of claim 6, wherein on one side of the body segment, the at least one clamping device further includes a plurality of fins that are spaced apart from one another and extend horizontally from the body segment.

9. The heat sink assembly of claim 6, wherein the mating connecting feature of the at least one clamping device further includes a mount configuration having a cross section configured to fit within the channel.

10. The heat sink assembly of claim 9, wherein the mount configuration extends from the body segment by a tab segment.

11. The heat sink assembly of claim 9, wherein the channel is sized to receive the mount configuration of the clamping device to releasably secure the clamping device to the heat sink, the arrangement being such that the mount configuration of the clamping device is inserted into the channel of the heat sink, and is capable of being slid within the channel to position the clamping device along a length of the body portion of the heat sink.

12. The heat sink assembly of claim 11 , wherein the at least one component package includes two or more component packages, the at least one clamping device includes two or more clamping devices, and the at least one fastener includes two or more fasteners.

13. The heat sink assembly of claim 11 , wherein the at least one fastener being threadably received within the at least one threadable opening to apply a clamping force on the at least one clamping device against the at least one component package.

14. The heat sink assembly of claim 1, wherein the at least one component package includes one of a power device, a transistor package and a diode package.

15. A method of repairing a PCB assembly, when component packages are accessible on the PCB assembly, the method comprising:

unscrewing a fastener of a clamping device that is secured to a heat sink, and removing the clamping device by sliding the clamping device with respect to the heat sink; replacing a component package held secure by the clamping device on the heat sink; and

re- securing the clamping device to the heat sink with the fastener by sliding the clamping device with respect to the heat sink and screwing the fastener.

16. The method of claim 15, wherein a connecting feature of the heat sink is configured to releasably secure a mating connecting feature of the at least one clamping device therein to releasably secure the at least one clamping device to the heat sink.

17. The method of claim 16, wherein the connecting feature of the heat sink includes a channel formed at an intersection of a body portion and a top flange portion of the heat sink, the channel extending along a length of the heat sink and being accessible through two open ends provided at the ends of the heat sink.

18. The method of claim 17, wherein the mating connecting feature of the at least one clamping device further includes a mount configuration having a cross section configured to fit within the channel.

19. The method of claim 18, wherein the channel is sized to receive the mount configuration of the clamping device to releasably secure the clamping device to the heat sink, the arrangement being such that the mount configuration of the clamping device is inserted into the channel of the heat sink, and is capable of being slid within the channel to position the clamping device along a length of the body portion of the heat sink.

20. A method of repairing a PCB assembly, when component packages are not accessible in the PCB assembly, the method comprising:

partially loosening a fastener of a clamping device that is secured to a heat sink until the clamping device is loosened enough to disengage a component package;

removing the heat sink from the substrate;

replacing the component package held secure by the clamping device on the heat sink;

re-securing the heat sink on the substrate; and

fastening the fastener to secure the clamping device to the heat sink.

Description:
HEAT SINK CLAMPING DEVICES

BACKGROUND

1. Field of Disclosure

The present disclosure relates generally to the field of electronics and, more particularly, to devices and methods that dissipate heat from electronic components.

2. Discussion of Related Art

Modern electronic components produce excessive amounts of heat during operation. To ensure that the components do not overheat, system designers attach convective heat sinks to cool these components, by providing an efficient heat transfer path from the devices to the environment. A typical convective heat sink is designed to transfer heat energy from the high temperature component to lower temperature of the surrounding air. Such typical heat sinks attach to the components through a base and include fins or pins to increase the surface area of the heat sink within a given space.

When securing transistors and/or diodes on a heat sink, it is desirable to ensure these components are tightly attached on heat sink for good heat conduction, and to ensure that the heat sink assembly is tightly secured on a substrate, such as a printed circuit board (“PCB”). It is further desirable for a quicker and easier assembly process in production or product repair, especially since existing assembly designs are somewhat complicated.

In uninterruptible power supplies (UPSs), approximately ten percent of field repair calls are for power device replacement. These power devices are mounted on heat sinks, and service engineers need to remove the heat sink to replace the failed power devices. Specifically, an existing heat sink and PCB layout assembly typically requires complete disassembly of the heat sink(s) and the power device(s), even for a single power device failure. The heat sink typically requires complete detachment from the PCB by de soldering every power device. During this process, there is a possibility of damaging neighboring power devices during present replacement methods.

When securing a heat sink to a PCB, especially for heavy heat sinks, the heat sink is secured to the PCB from a bottom side of the PCB. In addition, screws that are used to secure transistors and/or the mounting devices usually cannot be removed from a completed PCB assembly having a PCB, heat sinks, and large components. The large components are located near the screws that block the way to unscrew heat sinks from the PCB. In general, a technician disassembling the heat sinks needs to unsolder all of the large components located near the heat sinks, or unsolders all of the transistors on the heat sinks, and then detaches the full heat sink assembly from the PCB. This process takes time and effort in PCB assembly repair in replacing transistors and/or diodes.

One known power device replacement method involves (1) unfastening and removing a PCB assembly from a UPS, (2) de-soldering all power device leads from a PCB, (3) unfastening a heat sink from the PCB, (4) replacing faulty power device(s) from the heat sink, (5) replacing all other power devices on that heat sink, a part of failure prevention due to de-soldering and handling, (6) mounting the heat sink to the PCB by aligning the device leads, and (7) fastening the heat sink to the PCB and solder all the leads.

SUMMARY OF DISCLOSURE

One aspect of the disclosure is directed to a heat sink assembly comprising a heat sink configured to be attached to an electronic assembly and to secure at least one component package thereto and at least one clamping device configured to be secured to the heat sink and to engage the at least one component package. The heat sink includes a connecting feature and the at least one clamping device includes a mating connecting feature. The heat sink assembly further includes at least one fastener to engage the at least one clamping device. The connecting feature of the heat sink is configured to releasably secure the mating connecting feature of the at least one clamping device therein to releasably secure the at least one clamping device to the heat sink.

Embodiments of the heat sink assembly further may include configuring the heat sink to have an upright body portion and a top flange portion that extends perpendicularly from the body portion. On one side of the body portion of the heat sink, the heat sink further may include a plurality of fins that are spaced apart from one another and extend horizontally from the body portion, and on an opposite side of the body portion, the heat sink further includes a plurality of fins that are spaced apart from one another and extend horizontally from the body portion. The top flange portion may include at least one threadable opening, the at least one fastener being threadably received within the at least one threadable opening to apply a clamping force on the at least one clamping device against the at least one component package. The connecting feature of the heat sink may include a channel formed at an intersection of the body portion and the top flange portion, the channel extending along a length of the heat sink and being accessible through two open ends provided at the ends of the heat sink. The at least one clamping device further may include an upright body segment and a top flange segment that extends perpendicularly from the body segment. The top flange segment of the at least one clamping device may include an engagement surface that is provided to engage the at least one fastener through a threadable opening in the top flange portion of the heat sink. On one side of the body segment, the at least one clamping device further may include a plurality of fins that are spaced apart from one another and extend horizontally from the body segment. The mating connecting feature of the at least one clamping device further may include a mount configuration having a cross section configured to fit within the channel. The mount configuration may extend from the body segment by a tab segment. The channel may be sized to receive the mount configuration of the clamping device to releasably secure the clamping device to the heat sink. The arrangement is such that the mount configuration of the clamping device is inserted into the channel of the heat sink, and is capable of being slid within the channel to position the clamping device along a length of the body portion of the heat sink. The at least one component package may include two or more component packages, the at least one clamping device may include two or more clamping devices, and the at least one fastener may include two or more fasteners. The at least one fastener may be threadably received within the at least one threadable opening to apply a clamping force on the at least one clamping device against the at least one component package. The at least one component package may include one of a power device, a transistor package and a diode package.

Another aspect of the disclosure is directed to a method of repairing a PCB assembly, when component packages are accessible on the PCB assembly. In one embodiment, the method comprises: unscrewing a fastener of a clamping device that is secured to a heat sink, and removing the clamping device by sliding the clamping device with respect to the heat sink; replacing a component package held secure by the clamping device on the heat sink; and re-securing the clamping device to the heat sink with the fastener by sliding the clamping device with respect to the heat sink and screwing the fastener. Embodiments of the method further may include a connecting feature of the heat sink being configured to releasably secure a mating connecting feature of the at least one clamping device therein to releasably secure the at least one clamping device to the heat sink. The connecting feature of the heat sink may include a channel formed at an intersection of a body portion and a top flange portion of the heat sink, the channel extending along a length of the heat sink and being accessible through two open ends provided at the ends of the heat sink. The mating connecting feature of the at least one clamping device further may include a mount configuration having a cross section configured to fit within the channel. The channel may be sized to receive the mount configuration of the clamping device to releasably secure the clamping device to the heat sink. The arrangement is such that the mount configuration of the clamping device is inserted into the channel of the heat sink, and is capable of being slid within the channel to position the clamping device along a length of the body portion of the heat sink.

Yet another aspect of the present disclosure is directed to a method of repairing a PCB assembly, when component packages are not accessible in the PCB assembly. In one embodiment, the method comprises: partially loosening a fastener of a clamping device that is secured to a heat sink until the clamping device is loosened enough to disengage a component package; removing the heat sink from the substrate; replacing the component package held secure by the clamping device on the heat sink; re-securing the heat sink on the substrate; and fastening the fastener to secure the clamping device to the heat sink.

BRIEF DESCRIPTION OF THE DRAWINGS

Various aspects of at least one embodiment are discussed below with reference to the accompanying figures, which are not intended to be drawn to scale. Where technical features in the figures, detailed description or any claim are followed by references signs, the reference signs have been included for the sole purpose of increasing the intelligibility of the figures, detailed description, and claims. Accordingly, neither the reference signs nor their absence are intended to have any limiting effect on the scope of any claim elements.

In the figures, each identical or nearly identical component that is illustrated in various figures is represented by a like numeral. For purposes of clarity, not every component may be labeled in every figure. The figures are provided for the purposes of illustration and explanation and are not intended as a definition of the limits of the disclosure. In the figures:

FIG. 1 is a perspective view of a heat sink assembly of an embodiment of the present disclosure;

FIG. 2 is a perspective view of the heat sink assembly with component packages removed;

FIG. 3 is a perspective view of a heat sink of the heat sink assembly;

FIG. 4 is a perspective view of a clamping device of the heat sink assembly;

FIG. 5 is a perspective view of the heat sink assembly showing a clamping device prior to being secured to the heat sink;

FIG. 6 is a cross-sectional view of the heat sink assembly;

FIGS. 7A-7D show temperature profiles of the heat sink inside an enclosure, the heat sink and the component packages, the heat sink alone and the heat sink and clamping devices, respectively; and

FIG. 8A-8C show temperature profiles of the heat sink fins, airflow velocity profile (side view) and airflow velocity profile (front view).

DETAILED DESCRIPTION

Traditional heat sinks suffer from several disadvantages, such as being increasingly large, heavy and costly, as well as being difficult to repair and replace. Accordingly, there is a need for a more efficient device, system and method of heat dissipation that would be lighter and easier to construct, assemble and repair or replace. Aspects and embodiments are directed to methods of fabricating heat dissipation devices that overcome the limitations and drawbacks of conventional solutions, while providing a solution that is functionally uncomplicated and easy to implement. As used herein, the term“heat-generating component” may refer to any electronic components or a group of components that generate heat, for example semiconductor devices, such as bipolar junction transistors, MOS-FETs, diodes or IGBTs, to name a few.

The present disclosure is directed to a heat sink assembly and method of assembling and installing the heat sink assembly that increases production efficiency and product reliability, and makes it easier to repair or replace defective power devices. For some kinds of transistor and/or diode packages, such as TO-220 or TO-247 component packages, a heat sink to help heat dissipation is often needed. Such transistors and/or diodes, sometimes referred to as power devices or component packages, are secured on the heat sink with a certain applied pressure. This may result in too many screws and/or individual mounting devices being used to secure the component packages on heat sink, a troublesome PCB assembly overturn process to secure heat sink on PCB assembly in production, and very difficult to replace transistors/ diodes in PCB repair.

The present disclosure is directed to a clamping device for a heat sink assembly that can be used to secure component packages, such as transistors and/or diodes, on a heat sink with stable pressure.

Referring now to the drawings, and more specifically to FIG. 1, a heat sink assembly of the present disclosure is generally indicated at 10. In the shown embodiment, the heat sink assembly 10 includes a heat sink, generally indicated at 12, and several clamping devices, each generally indicated at 14, which are used to secure several component packages, each indicated at 16, to the heat sink. In one embodiment, component packages 16, or power devices, can include transistor and/or diode packages, such as TO-220 or TO- 247 component packages. Other power devices are further contemplated. In a certain embodiment, the heat sink assembly 10 is configured to be secured to a substrate 18, such as a PCB. When assembling and installing the heat sink assembly 10, the component packages 16 are secured to the heat sink 12 by the clamping devices 14, and the assembled heat sink is installed on the substrate by suitable fasteners or securement methods.

Referring to FIGS. 2 and 3, the heat sink 12 includes an upright body portion 20 and a top flange portion 22, which extends perpendicularly from the body portion. The body portion 20 and the top flange portion 22 are generally L-shaped in construction and are fabricated from relatively thick stock material. On one side of the body portion 20, the heat sink 12 further includes a plurality of larger fins, each indicated at 24, which are spaced apart from one another and extend horizontally from the body portion, and a plurality of smaller fins, each indicated at 26, which are spaced apart from one another and extend horizontally from the body portion. On an opposite side of the body portion 20, the heat sink 12 includes a plurality of even shorter fins, each indicated at 28, which are spaced apart from one another and extend horizontally from the body portion. These shorter fins 28 are provided on the same side of the body portion as an area 30 that is provided to engage the component packages 16 when mounting the component packages on the heat sink 12. The number and spacing of the fins 24, 26, 28 may be selected based on the particular application. The fins 24, 26, 28 are provided to remove heat from the substrate 18 and the component packages 16 (via the body portion 20). The top flange portion 22 includes several spaced apart threaded openings, each indicated at 32, that are provided to receive threaded fasteners that are configured to apply clamping forces to the clamping devices 14 to the heat sink 12 in the manner described below.

As will be discussed in greater detail below, the heat sink 10 further includes connecting feature embodying a circular channel 34 formed at an intersection of the body portion 20 and the top flange portion 22. As shown, the circular channel 34 extends along a length of the heat sink 12 from one end of the heat sink to an opposite end of the heat sink, and is accessible through two open ends provided at the ends of the heat sink. Although shown as a circular channel, the channel 34 may embody other shapes, such as trapezoid, square, or hexagon, or some other uniquely shaped configuration used to perform the clamping function described herein. The heat sink 12 may be fabricated from an extrusion process with any suitable material, such as aluminum or aluminum alloys. The heat sink 12 is of typical construction, with the fins 24, 26, 28 being provided to dissipate heat from the component packages 16 and the substrate 18.

Referring additionally FIG. 4, each clamping device 14 is configured to be removably secured to the circular channel 34 provided at the intersection of the body portion 20 and the top flange portion 22 of the heat sink 12. As shown, the clamping device 14 includes an upright body segment 36 and a top flange segment 38, which extends perpendicularly from the body segment. On one side of the body segment 36, the clamping device 14 further includes a plurality of fins, each indicated at 40, which are spaced apart from one another and extend horizontally from the body segment. As with the fins 24, 26, 28 of the heat sink 12, the fins 40 of the clamping device 14 are provided to remove heat from the component package 16 when installed in the manner described herein.

On an opposite side of the body segment 36, opposite the top flange segment 38, the clamping device 14 includes a mating connecting feature embodying a mount configuration 42 having a circular cross section, the mount configuration extending from the body segment 36 by a tab segment 44. The top flange segment 38 of the clamping device 14 includes an engagement surface 46 that is provided to engage a tip of a screw fastener 48, such as a machine screw fastener, to apply a clamping force on the top flange segment. The circular channel 34 of the heat sink 12 is sized to receive the mount

configuration 42 of the clamping device 14 to releasably secure the clamping device to the heat sink. The arrangement is such that the mount configuration 42 of the clamping device 14 is inserted into the circular channel 34 of the heat sink 12, and is capable of being slid within the circular channel to position the clamping device along a length of the body portion 20 of the heat sink. In the shown embodiment, there are four component packages 16 secured to the side of the body portion 20 of the heat sink 12 and four corresponding clamping devices 14 that are provided to clamp the component packages 16 to the body portion of the heat sink. For each of the four clamping devices 14, the mount configuration 42 of clamping device is inserted into the circular channel 34 and positioned with a respective component package 16 so that the body segment 36 of the clamping device engages its respective component package. It should be understood that the mount configurations 42 of the clamping devices 14 may be inserted into the circular channel 34 at one of the two open ends of the circular channel.

Once positioned, each clamping devices 14 is fixedly secured in place to apply a clamping force by threadably inserting the screw fastener 48 into the threaded opening 32 of the top flange portion of the heat sink and engaging a tip of the screw fastener to the engagement surface 46 of the top flange segment 38 of the clamping device. FIG. 5 illustrates a clamping device 14 prior to being secured to the heat sink 12, with the remaining clamping devices being secured to the heat sink. In this manner, the clamping device 14 is configured to apply a force to the component package 16 that is secured to the body portion 20 of the heat sink 12. The clamping device 14 can be formed as a specific shape to provide adequate clamping force to each component package 16.

It should be noted that the number of clamping devices 14 may be varied based on the number of component packages secured 16 to the body portion 20 of the heat sink 12.

As shown, four clamping devices 14 are provided; however, any number of clamping devices can be provided based on the number of component packages 16. Moreover, the pitch of body segment 36 with respect to the flange segment 38 may be varied depending on the type of component package 16 being secured to the body portion 20 of the heat sink 12. The pressure or force applied to the component package 16 may be manipulated by the pitch or angle of the body segment 36 of the clamping device 14 against the component package. At least one benefit of the design of the clamping device 14 is that the pressure applied by the body segment 36 against the component package 16 is uniform and stable.

Referring to FIG. 6, it should be noted that the construction of the circular channel 34 and the circular mount configuration 42 facilitate the clockwise rotation of the body segment 36 of the clamping device 14 with respect to the heat sink 12 when fastening the screw fastener 48. Specifically, the application of a force by the screw fastener 48 on the top flange segment 38 of the clamping device 14 causes the clockwise rotation of the body segment 36 thereby applying a clamping force on the component package 16. Thus, an increase in force of the screw fastener 48 on the top flange segment 38 of the clamping device 14 increases a clamping force applied by the body segment 36 of the clamping device on the component package 16. Conversely, by unscrewing the screw fastener 48, the clamping force applied by the body segment 36 of the clamping device 14 is decreased or eliminated if the screw fastener ceases to engage the top flange segment 38 of the clamping device.

When repairing a PCB assembly in a first embodiment, when the component packages 16 are accessible on the PCB assembly, the repair process includes (a) unscrewing the screw fasteners 48 and removing the clamping devices 14 by sliding the clamping devices along the circular channel 34 of the heat sink 12, (b) replacing the component packages 16, as required, and (c) re-securing the clamping devices 14 and the screw fasteners 48. In another embodiment, when the component packages 16 are not accessible in the PCB assembly, the repair process includes (a) partially loosening a desired screw fasteners 48 until the associated clamping device 14 is loosened enough to disengage the component package 16, with the heat sink 12, clamping device 14 and fastener 48 being retained together as a partial heat sink assembly, (b) removing the heat sink assembly 10 from the substrate 18, (c) replacing the component packages 16, (d) re-securing the heat sink assembly 10 on the substrate 18, and (e) fastening the desired screw fastener 48 to secure the associated clamping device 14.

Alternatively, the clamping device 14 can be replaced by one or more individual clamping devices, which are applied for single component packages 16.

Thus, it should be observed that the heat sink assembly 10 of embodiments of the present disclosure is designed to simplify the heat sink assembly to allow for single faulty power device replacement, to reduce effort and time for faulty power device replacement, to improve heat transfer through secondary surfaces of the power device, and to create uniform pressure on the power devices for effective heat transfer.

The heat sink assembly 10 of embodiments of the present disclosure is intended to lower the cost of repair, as faulty power devices on the heat sink assembly are replaced by without disturbing working power devices. The heat sink assembly 10 further reduces the time required to prepare the heat sink assembly at a repair center. The heat sink assembly 10 improves a heat transfer rate since heat is extracted from both primary and secondary surfaces of power device. The heat sink assembly is configured to apply a uniform pressure on devices with the current mounting devices.

The heat sink assembly 10 of embodiments of the present disclosure addresses the shortcomings of prior heat sink assemblies and related methods. For example, present methods do not allow for single faulty power device replacement without de- soldering all power devices on the heat sink. Present methods require seven steps for repairing the failed power device, which consumes considerable amount of time and effort. No effective heat transfer from secondary surface of the power device as present mounting devices have less contribution for heat transfer. Present heat sink assemblies apply uneven pressure on the device, resulting ineffective heat transfer. Present heat sink assembly on the PCB needs additional effort to locate the device leads to PCB holes. Skilled labor is required. The heat sink assembly and the power devices are assembled at a slide line station without direct reference on a PCB reference desk, which can lead to manual errors.

Advantages of clamping devices 14 for the heat sink assembly 10 of embodiments of the present disclosure enable a method that allows single faulty device replacement without de-soldering all other power devices on the heat sink 12. In one embodiment, a method five steps for repairing the failed power device, which considerably reduces amount of time and effort. The heat sink assembly 10 and related method effectively enhances heat transfer from secondary surfaces of the power device from the proposed mounting approach thereby improving the reliability of the devices. The heat sink assembly 10 and related method applies uniform pressure on the power devices thereby resulting in effective heat transfer. The heat sink assembly 10 on the PCB does not need additional effort to locate the device leads to PCB holes as power devices are mounted independently. The power devices are mounted on the PCB using reference designators eliminating the manual errors. Embodiments of the heat sink assembly 10 include unidirectional fastening of clamping devices 14, which allows individual loosening of power devices without affecting neighboring power devices. Thus, the cost of replacing failed power devices is reduced. Assembly methodology associated with this unique mounting clamp does not need additional effort and time for device mounting thereby enabling quick power device replacement at repair centers. A unique clamp profile with fins facilitates heat transfer from the secondary surfaces of the power device. Also, the clamping device 14 has a flat contour profile to apply uniform pressure on the power devices.

Study of the existing methodology across product ranges indicates that the power devices are mounted on the heat sink assembly 10 with multi-directional fastening. During service repairs, known methods do not allow for single faulty device replacement, which also affects the integrity of nearby power devices. The known methods further consume higher time and effort, which in turn reduces the production throughput. Also, the brackets/mounting devices that are used for holding the devices do not contribute to heat transfer from the secondary surfaces of the power device. Also, the known bracket surfaces do not ensure uniform pressure application on the power devices, which in turn affects the reliability of the entire product. Considering all the above aspects, a unique innovative solution is proposed in this study that has following greater advantages: improved reliability of a product, quick replacement of faulty power devices at service centers, reduced the effort and time during manufacturing, enabled unidirectional fastening, and enhanced heat transfer from secondary surfaces of the power device.

The heat sink assembly 10 and related method of the present disclosure can be used across a wide range of products as it does not ask for any change in standard

components/devices. For example, the heat sink assembly 10 including the clamping device 14 can be used on different types of electronic components/devices. The heat sink assembly 10 and related method of the present disclosure can be considered as a reliable solution due to improved heat transfer from the secondary surface of the devices mounted using the clamping device 14. The solution can be retrofitted to the existing products with a minor modification in heat sink extrusion profile. The heat sink assembly 10 and related method of the present disclosure can be used as a field replacement solution, along with modified heat sink 12. Test results show a reduction in temperature found to range from three percent (3%) to nineteen and one-half percent (19.5%) based on the total power loss from the device.

The results of experimental study showing the difference in temperatures recorded on heat sink surface and TO-247 device cases are tabulated below in Tables 1-3 with fan (forced convection) and without fan (natural convection) conditions for 2.5 Watts (W) (Table 1), 5 W (Table 2) and 10 W (Table 3) power dissipation on each device.

Table 1

Table 2

Table 3

It is found that the temperature of the devices mounted on the heat sink assembly disclosed herein is less compared to the power devices mounted on the existing heat sink in all the cases. And this difference increases with increase in power loss from the power devices. This is evident from the case that the maximum difference in temperature is achieved when power dissipation from each power device is 10 W. Also, when fan runs at low speed, the proposed solution seems to be much effective compared to the system without fan. This is evident from the results that maximum of 16.29 °C temperature difference was observed between existing heat sink and the heat sink disclosed herein for 10 W power loss from the power device.

FIGS. 7 A shows a temperature profile of the heat sink disclosed herein inside an enclosure. FIG. 7B shows a temperature profile of the heat sink disclosed herein and the component packages. FIG. 7C shows a temperature profile of the heat sink disclosed herein alone. FIG. 7D shows a temperature profile of the heat sink and the clamping devices disclosed herein.

FIG. 8 A shows a temperature profile of the heat sink fins. FIG. 8B is a side view showing an airflow velocity profile of the heat sink. FIG. 8C is a front view showing an airflow velocity profile of the heat sink.

Thus, it should be observed that the methods for assembling heat sinks of the present disclosure produce heat sinks that are as efficient as heat sinks that are used with forced cooling. Moreover, a fully top-down screw/unscrew operation for heat sink assembly in PCB assembly production and repair.

It is to be appreciated that embodiments of the devices and methods discussed herein are not limited in application to the details of construction and the arrangement of components set forth in the following description or illustrated in the accompanying drawings. The devices and methods are capable of implementation in other embodiments and of being practiced or of being carried out in various ways. Examples of specific implementations are provided herein for illustrative purposes only and are not intended to be limiting. In particular, acts, elements and features discussed in connection with any one or more embodiments are not intended to be excluded from a similar role in any other embodiments.

Also, the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. Any references to embodiments or elements or acts of the systems and methods herein referred to in the singular may also embrace

embodiments including a plurality of these elements, and any references in plural to any embodiment or element or act herein may also embrace embodiments including only a single element. References in the singular or plural form are not intended to limit the presently disclosed systems or methods, their components, acts, or elements. The use herein of“including,”“comprising,”“having,”“containin g,”“involving,” and variations thereof is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. References to“or” may be construed as inclusive so that any terms described using “or” may indicate any of a single, more than one, and all of the described terms. Any references to front and back, left and right, top and bottom, upper and lower, and vertical and horizontal are intended for convenience of description, not to limit the present systems and methods or their components to any one positional or spatial orientation.

Having thus described several aspects of at least one embodiment, it is to be appreciated various alterations, modifications, and improvements will readily occur to those skilled in the art. Such alterations, modifications, and improvements are intended to be part of this disclosure and are intended to be within the scope of the disclosure. Accordingly, the foregoing description and drawings are by way of example only, and the scope of the disclosure should be determined from proper construction of the appended claims, and their equivalents.

What is claimed is: