Patent ID: 12238856

DESCRIPTION OF EXAMPLE EMBODIMENTS

Overview

In an embodiment, a heat sink component comprises a cold plate including a first surface configured to engage a circuit component and a second surface opposing the first surface, and a plurality of fins extending transversely from the second surface of the cold plate. The first surface includes a non-planar surface portion and a planar surface portion surrounding the non-planar surface portion. The non-planar surface portion of the cold plate provides an adaptive contour to complement a surface of a circuit component that experiences thermal warpage due to change in temperature during operation.

In another embodiment, an apparatus comprises a printed circuit board (PCB), a circuit component coupled with the PCB, and a heat sink component coupled with the circuit component. The heat sink component comprises a cold plate including a first surface configured to engage a surface of the circuit component and a second surface opposing the first surface, and a plurality of fins extending transversely from the second surface of the cold plate, where the first surface includes a non-planar surface portion and a planar surface portion surrounding the non-planar surface portion.

In a further embodiment, a method comprises providing a cold plate for a heat sink including a first surface configured to engage a circuit component and a second surface opposing the first surface, contouring the first surface to include a non-planar surface portion and a planar surface portion surrounding the non-planar surface portion, and providing a plurality of fins extending transversely from the second surface of the cold plate.

EXAMPLE EMBODIMENTS

Described herein is an apparatus or cooling system for a circuit component that comprises a heat sink component including a base or cold plate and cooling fins extending transversely from the cold plate. The cold plate includes a convex curvature along its lower or component engaging side that has been adapted to precisely conform with a warpage that develops along the upper or engaging side of the circuit component during operations with increasing temperatures of the circuit component.

The circuit component can comprise any type of integrated circuit component, such as an Application Specific Integrated Circuit (ASIC), where the circuit component is coupled or integrated with a printed circuit board (PCB) (e.g., in a die package) within the housing of an electronic device. While an ASIC component is described as the circuit component in example embodiments (e.g., as shown in the drawings), the cooling system with heat sink component can be implemented with any other type of circuit component including, without limitation, a processor and/or any other circuit component associated with a central processing unit (CPU) component, a graphics processing unit (GPU), a neural processing unit (NPU), etc. The PCB including a heat sink component coupled with a circuit component as described herein can be implemented for use in any type of computing or other electronic device including, without limitation, networking devices such as routers, switches, hubs, access points, etc.

Referring to the example embodiments depicted inFIGS.1A,1B and1C, a circuit component110is generally depicted (alone inFIGS.1A and1Band with a conventional heat sink structure as shown inFIG.1C). As previously noted, the circuit component can comprise an ASIC, e.g., provided as a die package. The top or heat sink facing surface115of the component110(which can be the component top surface or an outer surface of a package cover or lid) is generally planar but includes a slight convex curvature at or approaching a central surface area location of the surface115. The curvature of the component top surface is somewhat exaggerated in the figures in order to clearly demonstrate the temperature warpage effect and other features of the embodiments described herein. At lower (e.g., ambient) temperatures T1(e.g., T1is about 25° C. to about 30° C.), the surface115has a slight convex curvature as shown inFIGS.1A and1C.

As the temperature of the component110increases toward a greater temperature and approaches a maximum rated temperature T2for the component (e.g., T2can be 100° C. or greater, such as about 180° C. to about 190° C. or even greater depending upon a particular configuration), the surface115of the component110exhibits a slight warpage within the convex surface area, where the slight warpage is concave and depicts a “smile” along the surface115(as shown inFIGS.1A and1B). Thus, the contour of a portion of the surface of the component110undergoes a shape inversion (e.g., convex to concave) caused by the change (increase) in temperature.

As shown inFIG.1C, a conventional heat sink component130includes a base or cold plate that engages the surface115of the component110to effect heat transfer between the components so as to cool the component during operations. At the lower temperature T1, there is a slight gap that may exist between the slightly non-planar surface area portion of the heat sink facing surface115and a lower or component engaging surface of the heat sink130. As further shown inFIG.1C, a filler material120, such as grease or a phase change material (PCM) or a thermal pad), can be applied between the heat sink component130and the circuit component110. However, such filler material120is not as effective at facilitating heat transfer between the heat sink and the circuit component resulting in less effective cooling of the circuit component at the greater temperature T2. In addition, the gap between heat sink component and circuit component becomes even larger (at the concave portion or “smile” of surface115) at the greater temperature T2.

Referring toFIGS.2A and2B, a heat sink component200is provided to account for the anticipated high temperature/thermal warpage that occurs along the surface115of the circuit component110. The heat sink component200includes a base plate or cold plate210and a plurality of thin cooling fins220extending transversely from an outward surface212of the cold plate210. The cold plate, fins and any other components of the heat sink component are constructed of suitable materials (e.g., copper, aluminum, etc.) that facilitate effective heat transfer at a suitable rate between the circuit component and the heat sink component.

An opposing, circuit component engaging surface215of the cold plate210includes a slightly curved and convex surface area portion230surrounded by a generally planar portion231and that is aligned on the surface215so as to correspond and engage with the inverted concave surface portion along surface115that occurs due to thermal warpage at higher temperatures of the component110. As shown inFIG.3, the heat sink component200is coupled or connected with the circuit component110such that the lower or component engaging surface215of the heat sink component200engages with the top or heat sink component engaging surface115, where the surface area portion230with adaptive convex curvature conforms precisely with the concave warpage at the surface115of the component110at the upper operating temperature T2. The precise conformity of the surface215of the cold plate210with the surface115of the circuit component110facilitates maximum surface area contact between the heat sink component and the circuit component when heat transfer/cooling is most desired (i.e., at the upper operating temperatures).

In certain example embodiments, the cold plate of the heat sink component can comprise a solid block material. In such embodiments, the contouring of the circuit component engaging surface can be machined to provide a contour adapted to correspond with the warped contour of the circuit component to be cooled, where the contour is determined as noted herein. The circuit component engaging surface of the solid cold plate can be precisely contoured using any suitable machining process, e.g., computerized numeric control (CNC) machining techniques that provide extremely precise contouring of a surface within very low tolerance levels. For example, a 5-axis CNC machining device can be used to create a very precise curvature along the circuit component engaging surface of the solid cold plate (e.g., within tolerance levels within 0.125 mm, or even as low as 0.025 mm).

In other example embodiments, the cold plate comprises a hollow member including an enclosed chamber (e.g., vapor chamber) to enhance thermal properties of the heat sink. Referring toFIGS.4A and4B, an embodiment of a cold plate210for the heat sink component is hollow and includes an upper wall including the top surface212from which cooling fins220extend, a lower wall including the circuit component engaging surface215that is separated from the top wall, and side walls214that extend between and connect the upper and lower walls to define an enclosure or vapor chamber218within the cold plate210. A plurality of pillars250formed of a suitably rigid material also with suitable heat transfer properties (e.g., copper pillars) are provided within the vapor chamber218and also extend between the upper and lower walls including surfaces212,215.

The pillars250can be provided in any suitable configuration or arrangement within the vapor chamber218, such as in a series of rows and columns as shown in the plan view ofFIG.4B. The pillars within a region232of the surface215can vary in length, with pillars250arranged closer to a center of the region232having a greater length in comparison to pillars250disposed closer to an outer periphery of the region232. Specifically, the pillars250within the region232increase in length or pillar height in a direction that extends from the outer periphery of the region232toward a center of the region232. The variance in pillar heights within the region232results in a bowing of the circuit component engaging surface215in relation to the upper or top surface212, which results in the formation of the convex surface area portion230at the surface215that corresponds with the region232. For example, as depicted inFIG.4A, the pillars can increase in length or height an amount of about 100 to 150 micrometers at the maximum lengths (i.e., closest to the center of region232). In addition, surfaces forming the cold plate210can be constructed such that the lower or circuit component engaging surface215has a flexibility that is slightly greater in relation to the top surface212such that the increasing pillar heights cause the surface215to bow while surface212remains relatively planar. The lengths of the pillars250can be precisely controlled (e.g., by forming copper pillars in a build-up process within the vapor chamber) so as to define with high precision the convex curvature of the convex surface area portion230along the surface215. The pillars are also sufficiently strong to withstand compressive forces when the cold plate210is engaged with the circuit component110at a lower temperature T1in which there is no significant heat induced warpage of the circuit component surface115.

An example method of forming a precise curvature for the circuit component engaging surface of the heat sink component is now described with reference toFIGS.5,6and7. Referring to the flowchart inFIG.5, the surface warpage of a circuit component that occurs over an operational temperature range, e.g., from T1to T2, within a specific environment and/or device configuration is estimated at310. In particular, the circuit component110can comprise an ASIC configured for assembly and integration with a printed circuit board (PCB) in a specific arrangement with other circuit components for a specific device, such as a device400depicted inFIG.8. The operational temperature range for the ASIC circuit component110is based upon the specification requirements of the PCB and operational requirements of the device. Since the precise warpage and shape inversion (e.g., convex to concave shape) imparted to the surface of the ASIC over a specified temperature range (from T1to T2) will be based upon its implementation in a specific environment (e.g., a function of circuit package type, operational temperature range, ASIC to PCB interactions, etc.), tests can be conducted by mounting the ASIC circuit component to the PCB and performing operations over the temperature range T1to T2. During this testing, the surface warpage of the circuit component can be monitored and measured to determine a precise location, size and degree of warpage within the operational temperature range.

In an example embodiment, a Shadow Moiŕe technique is used to precisely measure the change or displacement of the surface contour of the circuit component on the PCB over the operational temperature range T1-T2. Any other suitable technique (e.g., laser scanning over the surface) can also be used to measure how the component surface contour changes (e.g., inversion of a portion of the convex surface to become concave or “smile”) with change in operating temperature. An example set of test data is depicted inFIG.6showing a change in coplanarity (indicating occurrence of warpage) at a particular point or location along the surface of the circuit component over a temperature range of T1=30° C. and T2=120° C. (e.g., in the embodiment ofFIG.6, the coplanarity value changes be about 1.5 mil over this temperature range at this precise location along the surface). Similar measurements can be obtained at a variety of locations along the circuit component surface to provide a precise measurement of how the surface contour changes for the circuit component in the application specific environment and over the operational temperature range of T1to T2. Thus, a precise indication of surface warpage for the circuit component in the specific environment in which it is used can be obtained.

At320, the circuit component engaging surface215of the cold plate210for the heat sink component200is contoured to form the convex surface area portion230utilizing the data obtained from the testing conducted at310. Having specific data with regard to the precise contouring changes/warpage that occur at precise locations along the circuit component surface and, in particular, the maximum contour change/warpage that occurs (e.g., at the upper or limit temperature T2) facilitates contouring of the surface215of the cold plate210in a complementary (i.e., inverse) manner. Contouring of the surface215of the cold plate210to form the convex surface area portion230can be achieved in a manner as previously described herein.

The convex surface area portion230can also be formed along the surface215of the cold plate210so as to avoid any sharp or detrimental apex or peak that might otherwise cause a point load and/or potential damage to the circuit component during use.

Referring toFIG.7, an example embodiment is depicted showing how the surface contour of the convex surface area portion230is defined in segments. The dimension A represents the size, length or diameter of the area defining the convex surface area portion230, and dimension C represents half this length (C=A/2). The lengths B1, B2, B3and B4that extend transverse dimension C define the thickness of the cold plate210at their locations and are arranged sequentially from the center of portion230outward to its peripheral edge. As shown inFIG.7, the cold plate thickness dimension of B1>B2>B3>B4, where B4is at the peripheral edge and represents the general flatness or planarity and constant thickness dimension of the cold plate outside of the convex surface area portion230. The region of portion230defined by dimension C includes curved segments located between B0and B1(represented as segment C1), between B1and B2(represented as segment C2), between B2and B3(represented as segment C3), and between B3and B4(represented as segment C4). In addition, each of segments B1+, B2+and B3+represents a curved section of portion230that extends from the planar dimension (B4) to a respective B1, B2or B3dimension at the respective C1, C2, and C3segments. It is noted that the curvature is symmetrical along either side of the center of dimension A, such that the designations along dimension C, or one half of the curvature, are also applicable along the other half of the curvature.

Thus, each designation shown inFIG.7can be defined as follows:A: size (e.g., length, diameter, etc.) of convex surface area portion that aligns with warped surface portion of circuit component.C: A/2C1, C2, C3, C4: equal sized segments, each being C/4 in width.B0, B1, B2, B3, B4: total height/thickness of cold plate including curvature height at such point (B4is normal/planar thickness of cold plate).

The curvature along the surface of the cold plate that is adapted to match the warpage of the circuit component can be defined as follows:B0+, B1+, B2+, B3+: curvature height from planar at each point.B0+: highest curvature height, which is estimated based on Shadow Moiŕe' data (as measured in step310).X: value that is dependent on warpage change of the circuit component in specific environment (as measured in step310).B0=B4+B0+B1=B0=B4+B0+B2=B1−XB3=B2−XB4=B3−X

By setting B1=B0(the highest or greatest curvature point), this results in a flattening of the convex curvature at its greatest height which avoids the formation of a small or sharp apex. This in effect diminishes or prevents a point load from otherwise being applied to the circuit component during use. In other words, the maximum thickness of the heat plate (i.e., B0, B1), as well as the maximum curvature height (i.e., B0+, B1+) of the convex surface area portion230forms a relatively flat plateau or defined length (2C1) instead of being a single apex or point. The flat plateau defines a length in which a thickness of the cold plate (i.e., from upper surface212to lower surface215) is at its maximum and is constant. This defined length, which can be at least 10% (i.e., a minimum of 10%) of the lengthwise or longest dimension of the non-planar (i.e., convex) surface portion (e.g., about 25% of the length A as depicted inFIG.7) is further sufficient to prevent a point load being applied to the circuit component.

At330, the heat sink component200is coupled with the circuit component110so that the convex surface area portion230of the surface215aligns with the area of maximum inverted and concave warpage that is predicted or determined to occur along the surface115of the circuit component110within the temperature range T1-T2.

An example embodiment of an electronic device (e.g., a networking device) that implements the heat sink component system as described herein is depicted inFIG.8. The device400includes a housing410that encloses a PCB420and various electronic components430coupled and/or integrated with the PCB420(e.g., integrated circuit components). Circuit component110is coupled with the PCB420and comprises an ASIC die package. Heat sink component200, including cold plate210and fins220, is applied directly to the top surface (e.g., die package lid or top surface of ASIC) of the circuit component110.

During operations of the device400(e.g., high speed data transfer operations), the circuit component heats up from a temperature T1to an elevated temperature T2, causing warpage to occur at the top surface of the circuit component. The curvature of the heat sink component (implemented as the convex surface area portion230at the circuit component engaging surface215) is adapted to match the inverted concave surface warpage of the circuit component thus ensuring adequate surface area contact and heat transfer between the heat sink component and the circuit component. Thus, adequate cooling of the circuit component is maintained at elevated temperatures causing maximum degree of warpage of the circuit component surface. This in turn minimizes or prevents a thermal runaway event associated with the circuit component during operations of the device.

While embodiments of a heat sink component have been described herein to address thermal warpage of the circuit component resulting in an inverted and concave contouring along its surface, other embodiments of a heat sink component utilizing the concepts described herein can also be provided to complement any other types of contour changes that may occur due to thermal effects on the circuit component. For example, a heat sink can be provided utilizing the concepts as described herein to account for thermal warpage along a surface of a circuit component that includes anyone or combination of contour changes when the circuit component is elevated in temperature over a specific operating temperature range, including changes from planar to concave and/or convex, as well as concave to convex, or any combinations of convex and concave contour changes. Thus, the heat sink component can be provided with a circuit component engaging surface in which a non-planar surface portion is surrounded by a generally planar surface portion, where the non-planar surface portion has a contour that complements in an inverted manner a surface portion of a circuit component that changes in contour (becomes thermally warped) as a result of an increase in temperature of the circuit component.

Thus, in example embodiments, a heat sink component comprises a cold plate including a first surface configured to engage a circuit component and a second surface opposing the first surface, and a plurality of fins extending transversely from the second surface of the cold plate. The first surface includes a non-planar surface portion and a planar surface portion surrounding the non-planar surface portion. The non-planar surface portion can comprise a convex surface area portion.

The cold plate can comprise a solid block. Alternatively, the cold plate can include a hollow interior and a plurality of pillars extending within the hollow interior between the first surface and the second surface. The pillars can be disposed at a region corresponding with the non-planar surface portion have varying lengths that bow the first surface to define a curvature of the non-planar surface portion.

In another embodiment, an apparatus comprises a printed circuit board (PCB), a circuit component coupled with the PCB, and a heat sink component coupled with the circuit component. The heat sink component can comprise a cold plate including a first surface configured to engage a surface of the circuit component and a second surface opposing the first surface, and a plurality of fins extending transversely from the second surface of the cold plate, where the first surface includes a non-planar surface portion and a planar surface portion surrounding the non-planar surface portion.

The surface of the circuit component can change in contour with a change from a temperature T1to a temperature T2that is greater than temperature T1, and the non-planar surface portion at the first surface of the cold plate can have a contour that corresponds so as to engage with a surface contour of the surface of the circuit component at the temperature T2.

The surface contour of the surface of the circuit component at the temperature T2can be concave, and the contour of the non-planar surface portion at the first surface of the cold plate can be convex.

The cold plate can comprise a solid block. Alternatively, the cold plate can include a hollow interior and a plurality of pillars extending within the hollow interior between the first surface and the second surface. The pillars can be disposed at a region corresponding with the non-planar surface portion have varying lengths that bow the first surface to define the contour of the non-planar surface portion at the first surface of the cold plate.

The apparatus can comprise a networking device.

In a further embodiment, a method comprises providing a cold plate for a heat sink including a first surface configured to engage a circuit component and a second surface opposing the first surface, contouring the first surface to include a non-planar surface portion and a planar surface portion surrounding the non-planar surface portion, and providing a plurality of fins extending transversely from the second surface of the cold plate.

The method can further comprise determining a change in curvature of a surface of the circuit component coupled with a printed circuit board (PCB) that is caused by thermal warpage over a temperature range from temperature T1to temperature T2, where temperature T2is greater than temperature T1. The contouring the first surface of the cold plate can include contouring the non-planar surface portion so as to correspond and engage with a surface contour of the surface of the circuit component at the temperature T2.

The surface contour of the surface of the circuit component at the temperature T2can be concave, and the contouring the non-planar surface portion at the first surface of the cold plate can comprise forming a convex contour for the non-planar surface portion.

The forming the convex contour for the non-planar surface portion at the first surface of the cold plate can comprise providing a plateau defined as a maximum and constant thickness of the cold plate at the non-planar surface portion, where the plateau has a length that is at least 10% of a lengthwise dimension of the non-planar surface portion.

The method can further comprise coupling the heat sink with the circuit component.

The cold plate can comprise a solid block, and the contouring the first surface to include the non-planar surface portion can comprise machining the first surface to form the non-planar surface portion.

The cold plate can include a hollow interior, and the contouring the first surface to include the non-planar surface portion can comprise providing plurality of pillars extending within the hollow interior between the first surface and the second surface. The pillars can be disposed at a region corresponding with the non-planar surface portion and have varying lengths that bow the first surface to define the convex contour of the non-planar surface portion.

The above description is intended by way of example only. The descriptions of the various embodiments have been presented for purposes of illustration, but are not intended to be exhaustive or limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The terminology used herein was chosen to best explain the principles of the embodiments, the practical application or technical improvement over technologies found in the marketplace, or to enable others of ordinary skill in the art to understand the embodiments disclosed herein.