Integrated Heat Spreader

Abstract

A heat spreader including an upper surface opposite the bottom surface, and a cavity formed in and extending upwardly from the bottom surface, the cavity including an inner wall extending around the cavity and extending vertically downward from an inner cavity surface of the cavity. The heat spreader further includes an outer periphery extending vertically upward from the bottom surface of the heat spreader and extending around the cavity, and at least one step disposed within the cavity and having a surface positioned at a vertical height less than the vertical height of the inner cavity surface of the cavity.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Provisional Application No. 63 / 327,651, filed April 5, 2022, which claims the benefit of U.S. Provisional Application No. 18 / 121,298, filed March 14, 2023, both of which are incorporated by reference herein in their entireties.

[0002] FIELD OF THE DISCLOSURE The present disclosure relates generally to integrated heat spreaders and methods of forming integrated heat spreaders. [Background technology]

[0003] Heat spreaders are often used in computer chip packages to draw heat away from the chip, semiconductor die, and / or processor and transfer the heat to a heat sink for dissipation. FIG. 1 illustrates a system established in the art that incorporates the use of a heat spreader. Specifically, a substrate 10 is shown positioned beneath a chip, also referred to as a die, 12, which may be positioned adjacent to and beneath a thermal interface material sheet 14. In some applications, the thermal interface material sheet 14 is comprised of various types of polymers, such as silicone. The chip 12 and thermal interface material sheet 14 may be positioned adjacent to a heat spreader 20, which in some embodiments may be positioned within a recessed portion of the heat spreader 20. The heat spreader 20 is positioned adjacent to a second layer of thermal interface material 14. Adjacent to the second layer of thermal interface material 14, the system may include a heat sink 18.

[0004] As a result of the configuration described above, during operation of the chip 12, heat generated by the chip 12 is dissipated through the heat spreader 20 to the heat sink 18. The heat spreader 20 can distribute and spread the heat across the heat spreader 20, facilitating efficient heat transfer to the heat sink 18. In this way, the heat generated by the chip 12 does not cause localized damage to components within the system. The heat distributed by the heat spreader 20 can then be transferred to the heat sink 18 and dissipated.

[0005] As previously discussed, in some cases, the heat spreader 20 may have a recess or cavity configured to receive the chip 12. Figures 2A and 2B illustrate additional embodiments of the heat spreader 20. As illustrated, the heat spreader 20 includes a top side 22 and a bottom side 24 having a cavity 26 extending into the bottom side 24. During operation, the chip 12 (Figure 1) may be placed in the cavity 26. In these embodiments, it may be desirable to have the recess and / or cavity shaped and sized to be optimized to engage the chip 12 that is being installed in the system.

[0006] During manufacturing, the heat spreader 20 may be formed in large quantities by cutting blanks from sheets or strips of bulk material and by using a combination of stamping processes to impart the desired shape and features to the blanks to ultimately produce the desired heat spreader. If the heat spreader 20 includes a cavity 26, the cavity 26 may be formed by stamping material from the blank into a shape and geometry configured to receive a processor or die during operation. During this process of stamping the heat spreader 20 to form the desired shape, the stamping force causes a cold flow of material from areas of high pressure to areas of low pressure. As such, a stamping system may be designed with a desired size and / or shape to create the target shape of the cavity 26. Summary of the Invention

[0007] The present disclosure provides a heat spreader including an upper surface opposite a bottom surface, a cavity formed in the bottom surface and extending upwardly from the bottom surface, the cavity including an inner wall extending around the cavity and extending vertically downward from an inner cavity side of the cavity, the heat spreader further including an outer periphery extending vertically upward from the bottom surface of the heat spreader and extending around the cavity, and at least one step disposed within the cavity and having a surface positioned at a vertical height less than the vertical height of the inner cavity side of the cavity.

[0008] In one form thereof, the present disclosure provides a heat spreader including a top surface opposite a bottom surface and a cavity extending from the bottom surface, the cavity including an inner wall extending around the cavity and extending vertically downward from an inner cavity surface of the cavity, the heat spreader additionally including an outer periphery extending vertically upward from the bottom surface of the heat spreader and extending around the cavity, and four steps positioned within the cavity and disposed at four respective corners of the cavity, each step extending from the outer periphery of the heat spreader to the inner cavity surface of the cavity such that at least a portion of the cavity includes an inclined surface.

[0009] In another form thereof, the disclosure provides a method of forming a heat spreader, the method including stamping a central surface of a sheet of material with a die and press of a stamping system to move material outwardly from the central surface to form a cavity and forming an outer perimeter extending along the cavity, holding the material of the cavity constant such that a thickness of the cavity remains constant, and during the step of holding the material, stamping the outer perimeter to move material inwardly from the central surface to define steps in corners of the cavity. [Brief description of the drawings]

[0010] The above-described and other features of the invention, as well as the manner of achieving them, will become more apparent, and the invention itself will be better understood, by referring to the following description of the embodiments of the invention in conjunction with the accompanying drawings, in which: [Figure 1] 1 illustrates a schematic diagram of an exemplary use of a heat spreader. [Figure 2A] 1 illustrates a heat spreader as is commonly known in the art. [Figure 2B] 1 illustrates a heat spreader as is commonly known in the art. [Diagram 3] 1 illustrates a schematic diagram of an exemplary press machine that may be used to manufacture a heat spreader according to an embodiment of the present disclosure. [Figure 4A] 1 illustrates a heat spreader according to an embodiment of the present disclosure. [Figure 4B] 4B illustrates a cross-sectional view of the heat spreader of FIG. 4A taken along line 4B-4B, in accordance with an embodiment of the present disclosure. [Figure 4C] 4C illustrates an enlarged cross-sectional view of a portion of the heat spreader shown in FIG. 4B illustrating a stage according to an embodiment of the present disclosure. [Figure 5A] 1 illustrates a heat spreader after a first step of fabrication according to an embodiment of the present disclosure. [Figure 5B] 5B illustrates a cross-sectional view of the heat spreader of FIG. 5A taken along line 5B-5B, in accordance with an embodiment of the present disclosure. [Figure 6A] 5B illustrates the heat spreader of FIG. 5A after a second step of fabrication, according to an embodiment of the present disclosure. [Figure 6B] 6B illustrates a cross-sectional view of the heat spreader of FIG. 6A taken along line 6B-6B, in accordance with an embodiment of the present disclosure. [Figure 7A] 13 illustrates a bottom view of an additional embodiment of a heat spreader according to an embodiment of the present disclosure. [Figure 7B] 7B illustrates an enlarged bottom view of a portion of the heat spreader of FIG. 7A showing steps according to an embodiment of the present disclosure. [Figure 7C]7C-7C, in accordance with an embodiment of the present disclosure, is a cross-sectional view of the stage shown in FIG. 7B taken along line 7C-7C. [Figure 8A] 13 illustrates a bottom view of an additional embodiment of a heat spreader according to an embodiment of the present disclosure. [Figure 8B] 8B illustrates an enlarged bottom view of a portion of the heat spreader of FIG. 8A showing steps according to an embodiment of the present disclosure. [Figure 8C] 8C-8C, according to an embodiment of the present disclosure, is a cross-sectional view of the step shown in FIG. 8B taken along line 8C-8C. [Figure 9A] 13 illustrates a bottom view of an additional embodiment of a heat spreader according to an embodiment of the present disclosure. [Figure 9B] 9B illustrates an enlarged bottom view of a portion of the heat spreader of FIG. 9A showing steps according to an embodiment of the present disclosure. [Figure 9C] 9C-9C, according to an embodiment of the present disclosure, is a cross-sectional view of the step shown in FIG. 9B taken along line 9C-9C.

[0011] Corresponding reference characters indicate corresponding parts throughout the several views. Unless otherwise noted, the drawings are drawn to scale and to proportion. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] FIG. 3 generally illustrates a stamping system 100 that may be used to form a heat spreader, as will be further described with reference to FIGS. 4A-8B. Specifically, the stamping system 100 includes a plate 102 for fixing a die 104 in place. The die 104 and the plate 102 are fixed such that the die 104 and the plate 102 remain stationary during the stamping process. The stamping system 100 further includes a ram 106 configured for repeated vertical up and down motion. In operation, a material, e.g., a sheet of metal, may be placed on the die 104, and the punch 106 may be actuated by the ram to move downwardly onto the material. During this process, the punch 106 is forced downwardly onto the material in the stamping system 100 to press the material to conform to the shape of the die 104 and / or punch 106. For example, as illustrated, the die 104 has a protrusion that extends upward, while the punch 106 has a corresponding V-shaped groove. As a result, once compressed, the workpiece between the die 104 and punch 106 will have protrusions that match the shape of the protrusions of the die 104 and the grooves of the punch 106. Although the die 104 and / or punch 106 are illustrated as having protrusions, they may have a variety of shapes and configurations. For example, the die 104 and / or ram 106 may have a flat profile, a dome-shaped profile, or an otherwise irregularly shaped profile. The stamping system 100 may be used to form the heat spreader 120, as described further below, using the die 104 and punch 106 to perform one or more steps to cold-form a blank of material into the desired shape and configuration of the heat spreader 120.

[0013] 4A illustrates a bottom view of one embodiment of a heat spreader 120 that may be formed from a stamping process using, for example, the stamping system 100 of FIG. 3 or a variation thereof. The heat spreader 120 defines a rectangular shape having a first side 122a, a second side 122b, a third side 122c, and a fourth side 122d. A width W1 of the heat spreader 120 is defined by the distance between the first side 122a and the third side 122c, while the heat spreader 120 defines a height H1 defined by the distance between the second side 122b and the fourth side 122d. In some embodiments, the width W1 is approximately equal to the height H1 such that the heat spreader 120 is defined by a square shape, but in the illustrated embodiment, the width W1 is greater than the height H1.

[0014] The heat spreader 120 additionally includes a central surface that defines a cavity 124 extending from the bottom surface 121 of the heat spreader 120. The cavity 124 includes a first side 123a, a second side 123b, a third side 123c, and a fourth side 123d. Each of the sides 123a-d may be parallel to a respective one of the sides 122a-d of the heat spreader 120. The cavity 124 is defined by a width W2 and a height H2, where the width W2 is less than the width W1 and the height H2 is less than the height H1. The heat spreader 120 additionally defines an outer perimeter 126 that extends along and between the sides 122a-d of the heat spreader 120 and the sides 123a-d of the cavity 124. In this embodiment, outer perimeter 126 includes a substantially constant width W3 around heat spreader 120, although in various embodiments width W3 may vary depending on positioning around heat spreader 120. For example, width W3 may be smaller along one or more of sides 122a-d.

[0015] 4A, the heat spreader 120 includes a plurality of steps 130 positioned within the cavity 124 and adjacent the periphery 126. More specifically, as illustrated in FIG. 4A, the plurality of steps 130 includes a first step 130a positioned at a corner generally defined between the first side 123a and the second side 123b, a second step 130b positioned at a corner generally defined between the third side 123c and the second side 123b, a third step 130c positioned at a corner generally defined between the third side 123c and the fourth side 123d, and a fourth step 130d positioned at a corner generally defined between the first side 123a and the fourth side 123d. As will be described further, the stages 130 are configured to provide an engagement surface between the heat spreader 120 and additional heat spreaders that may be stacked on top of the heat spreader 120. In other words, the stages 130 function to ensure that a surface of the cavity 124 does not contact the top surface of an adjacent heat spreader when stacked on top of each other.

[0016] FIG 4B illustrates a cross-sectional view of the heat spreader 120 of FIG 4A taken along line 4B-4B. Specifically, the cavity 124 is illustrated opposite the top surface 128 of the heat spreader 120. The heat spreader 120 defines a thickness T1 that may be greater than a thickness T2 of the outer perimeter 126. This varying thickness between the outer perimeter 126 and the heat spreader 120 may be the result of a stamping process used to form the heat spreader 120, which is described further below with reference to FIGS. 5A-6B.

[0017] The stages 130 will now be further described with reference to Figures 4B and 4C. Referring to the cross-sectional view of Figure 4C, one of the stages 130, illustratively the second stage 130b, is shown. The following description is made with respect to the second stage 130b, but the description may apply to any one of the stages 130, all of which may have the same shape, size, and geometry as the second stage 130b described herein. As illustrated, the cavity 124 has an inner wall 134 (Figure 4C) that may extend around the entirety of the cavity 124. As illustrated, the inner wall 134 extends in a direction toward the top surface 128 of the heat spreader 120 and intersects with a raised surface 136 of the second stage 130b. As illustrated, the raised surface 136 has a vertical height that is positioned lower than the vertical position of the inner cavity surface 140 of the cavity 124. In other words, the raised surface 136 extends vertically downward from the inner cavity surface 140 of the cavity 124. The second step 130b additionally includes an inclined surface 138 that intersects with the inner cavity surface 140 of the cavity 124. In these embodiments, the inner wall 134 may extend all around the cavity 124 such that in the first step 130a, the inner wall 134 intersects with the raised surface of the first step 130a, in the third step 130c, the inner wall 134 intersects with the raised surface of the third step 130c, and in the fourth step 130d, the inner wall 134 intersects with the raised surface of the fourth step 130d.

[0018] The raised surfaces 136 of the multiple steps 130 allow for stacking of the heat spreaders 120 without contact between the top surface 128 of one of the heat spreaders 120 and the inner cavity surface 140 of the cavity 124 of an adjacent heat spreader 120. After fabrication, the heat spreaders 120 may require bulk shipping. During shipping, the heat spreaders 120 may be stacked together in a tube. However, the cavity 124 of each heat spreader 120 may include precision surfaces that ideally do not contact any of the surfaces of the adjacent heat spreaders 120. As will be further described below, the steps 130 allow for flexibility in the shape and / or geometry of the heat spreaders 120 while reducing the likelihood of damage to sensitive surfaces within the cavity 124 during handling and shipping.

[0019] More specifically, when the various heat spreaders 120 are stacked, the top surface 128 of the second heat spreader 120 can be "nested" or received within the cavity 124 of the first heat spreader 120, and when so received, the top surface 128 of the second heat spreader 120 contacts the raised surfaces of the multiple steps 130 of the next adjacent heat spreader 120 without contacting the remainder of the completed heat spreader surface 140 within the cavity 124. In this manner, after stacking of the multiple heat spreaders 120, the inner surface 140 of the cavity 124 is protected from damage due to contact with the top surface 128 of the second heat spreader 120, since the steps 130 maintain the spacing between the inner cavity surface 140 and the adjacent top surface of the second heat spreader 120. 4C, for example, illustrates the second heat spreader 120 in phantom lines and illustrates the engagement between its top surface 128 and the raised surface 136 of the second tier 130b. The configuration of the raised surface 136 combined with the outer periphery 126 of the heat spreader 120 having a reduced thickness T2 compared to thickness T1 allows the heat spreaders 120 to be stacked on top of each other without the top surface 128 of one heat spreader 120 contacting the inner cavity surface 140 of the cavity 124 of an adjacent heat spreader 120. Furthermore, the only point of contact between the two stacked heat spreaders 120 is between the tier 130 and the adjacent top surface 128. In an embodiment, the inner cavity surface 140 of the cavity 124 may have a surface coating, such as gold plating, that protects it from damage or degradation due to contact between it and the top surface 128 of the adjacent heat spreader 120, thereby preserving maximum performance benefits from any such coating during use.

[0020] 5A-6B illustrate various stages of manufacturing the heat spreader 120 of FIG. 4A having multiple stages 130. The heat spreader 120 of FIG. 5A-6B may be formed using the stamping system 100 shown in FIG. 1 or variations thereof. In some embodiments, the blank sheet of material is a sheet of copper. However, in other embodiments, other suitable materials may be incorporated.

[0021] Referring first to FIG. 5A, the heat spreader 120 is illustrated in a partially completed state after a blank sheet of material is inserted into the stamping system 100 and a die 104 is stamped onto surface A of the heat spreader 120 to partially form a cavity 124. The die 104 and punch 106 are shaped such that only surface A is pressed by the stamping system 100, so that the material is pressed outwardly to form a raised surface where the multiple steps 130 (FIG. 4A) are present. Specifically, the stamping process causes the material to press or flow from surface A to the four corners of the newly formed cavity 124. FIG. 5B illustrates a cross-sectional view taken along line 5B-5B of FIG. 5A. As illustrated, the material of the original blank sheet of material has been pressed outwardly to form the cavity 124, creating raised portions in the four corners where the multiple steps 130 are ultimately present. After this first stamping process is complete, heat spreader 120 is defined by thickness T1 and does not include outer perimeter 126 having thickness T2 (FIG. 4B), which will be completed during the next step, as further described with respect to FIGS. 6A and 6B.

[0022] Specifically, the partially formed heat spreader 120 as shown in FIG. 5B is inserted into the stamping system 100 having a new arrangement for the die 104 and punch 106, and the material undergoes a second stamping process as further described with reference to FIGS. 6A-6B. During this step, the stamping system 100 is modified such that the die 104 and punch 106 are configured to hold the material at surface A constant while pressing down on the material from surface B (FIG. 5B). In this manner, the material from surface B is pressed and directed to flow into the corners of the cavity 124 to form the inner wall 134 of the heat spreader 120. Additionally, during this step, the stamping system 100 is configured to hold the material at surface F constant such that as the material is pressed from surface B into the corners of the cavity, the outer perimeter 126 is formed with the desired thickness T2 (FIG. 4B).

[0023] During this step of pressing down the material from surface B, the material on surface A is fixed in place to maintain the depth of the cavity 124. In other words, the material on surface A is fixed so that the material cannot flow to other areas of the heat spreader 120. In parallel with squeezing the material of surface B and holding the material of surface A constant, the material on surface E is squeezed and / or compressed by the die 104 (FIG. 3) and punch 106 (FIG. 3). The combination of holding the material of surface A while pressing the material of surface E causes the material from surface E to fill surface B' (FIG. 5A), thereby completing the formation of the multiple steps 130 and further defining the inner wall 134 of the cavity, as shown in FIG. 6A. In other words, the steps 130 and the inner wall 134 are "sharpened" by the flow of material during the second stamping process.

[0024] Additionally, this process results in an outer perimeter 126 being formed with a thickness T2 (FIG. 4B), which may be less than thickness T1 (FIG. 4B). The resulting shape of the now completed heat spreader 120 is shown in cross-section in FIG. 6B, and a first step 130a that may be formed from the process described above is shown, for example, in FIG. 4C.

[0025] In one embodiment, each of the steps 130 may be formed with an angled surface 138 as shown in FIG. 4C. The angled surface 138 may act as a draft surface during the second step of manufacturing. In other words, the angled surface 138 specifically helps facilitate the flow of material along a desired direction during the second step of the stamping process. Additionally, as previously described, the angled surface 138 also acts as a contact point for engaging the top surface 128 of an adjacent heat spreader 120. The engagement of the top surface 128 of the first heat spreader 120 with the angled surface 138 of the second heat spreader 120a (FIG. 4C) reduces the contact area required between the heat spreaders, reducing the possibility of damage or contamination to the heat spreaders during stacking as described above.

[0026] Although the above method is described for forming the heat spreader 120 as shown in Figures 4-4C, the process may be applied to form various configurations of the heat spreader 120 and the stages 130. For example, the shape of the die 104 (Figure 3) and / or punch 106 (Figure 3) may be changed or modified to create varying embodiments of the stages 130 as needed or desired for a particular application. For example, variations of stages incorporated into the heat spreader 120 are further described herein with reference to Figures 7A-9C.

[0027] FIG. 7A illustrates the heat spreader 120 of FIG. 1 having multiple stages 230. Similar to the multiple stages 130 shown in FIGS. 4A-4C, the multiple stages 230 are positioned at each corner of the heat spreader 120. More specifically, a first stage 230a is positioned between the first side 122a and the fourth side 122d, a second stage 230b is positioned between the first side 122a and the second side 122b, a third stage 230c is positioned between the second side 122b and the third side 122c, and a fourth stage 230d is positioned between the third side 122c and the fourth side 122d. Although illustrated as having four stages 230, any number of stages may be incorporated. 8A-8C, the heat spreader 120 may include two stages. In other embodiments, the heat spreader 120 may include four or more stages 230.

[0028] FIG. 7B illustrates a top close-up view of a first step, more specifically, a second step 230b, of the plurality of steps 230. The following description is made with respect to the second step 230b, but may be applied to any of the plurality of steps 230. As illustrated, the second step 230b may have an irregular shape defined by a first curved surface 242 and a second curved surface, the second curved surface being defined by the inner wall 134 of the cavity 124. FIG. 7C illustrates an exaggerated view of a cross-sectional profile of the second step 230b taken along the line 7C-7C shown in FIG. 7B. As illustrated, the second step 230b includes an angled portion 234 that intersects with the inner wall 134 of the heat spreader 120 and the inner cavity surface 140 of the cavity 124. An angled portion 234 extends from the outer periphery 126 of the heat spreader 120, and a flat portion 238 extends from the angled portion 234. The angled portion 234 may extend downwardly at an angle of approximately 2 degrees to 4 degrees relative to the longitudinal axis L (FIG. 4B) of the heat spreader 120. The flat portion 238 extends from the angled portion 234 and merges with a cliff portion 240 that connects to an inner cavity surface 140 of the cavity 124. Similar to the multiple steps 130 described with reference to FIGS. 4A-4C, the profile of the multiple steps 230 facilitates reducing contact between the inner cavity surface 140 of the cavity 124 and the top surface 128 of an adjacent heat spreader 120 when the heat spreaders 120 are stacked together. For example, the second heat spreader 120a is shown in phantom lines as resting on the angled portion 234 of the second tier 230b such that a very small contact area, approaching line or point contact, is formed between the top surface of the adjacent heat spreader 120a and the tier 230. Therefore, the second heat spreader 120a does not contact the inner cavity surface 140 of the cavity 124, avoiding damaging the surface of the cavity 124. In other embodiments, the second heat spreader 120a may engage the flat portion 238 of the second tier 230b while still protecting and preserving the functional surface of the cavity 124.

[0029] FIG. 8A illustrates an additional embodiment of the heat spreader 120 having multiple stages 330. In the exemplary embodiment of FIG. 8A, the multiple stages 330 include a first stage 330a and a second stage 330b. In this exemplary embodiment, the first stage 330a and the second stage 330b extend from the second side 122b and the fourth side 122d. FIG. 8B illustrates an enlarged bottom view of one of the multiple stages 330, illustratively the second stage 330b. As illustrated, the shape and / or configuration of the second stage 330b is defined by a first curved surface 342 and a second straight surface, with the first curved surface being defined by the inner wall 134.

[0030] FIG. 8C illustrates a schematic cross-sectional profile of the second step 330b taken along line 8C-8C of FIG. 8B with an exaggerated representation of the surface for clarity. Specifically, it is a cross-sectional view of the second step 330b extending between the first sidewall 122a and the third sidewall 122c. As illustrated, the second step 330b includes a first sloped portion 332 coupled to the outer periphery 126 of the heat spreader 120 through a cliff portion 335. Extending from the first sloped portion 332 is a flat portion 334. The flat portion 334 may be at the same vertical height as the inner cavity surface 140 of the cavity 124 or may protrude from the inner surface 140. In other words, the flat portion 334 may be continuous with the inner cavity surface 140 of the cavity 124 or may form a step adjacent to the surface 140. Extending from the flat portion 334 is a second angled portion 336 which is coupled to the outer perimeter 126 through a cliff portion 338. The angled portions 332, 336 may extend downwardly at an angle of about 2 degrees to about 4 degrees relative to the longitudinal axis L (FIG. 4B) of the heat spreader 120. Although described with reference to the second step 330b, the first step 330a may be defined by the same cross-sectional profile as the second step 330b.

[0031] The incorporation of the angled portions 332, 336 in this configuration reduces the contact area between the inner cavity surface 140 of the cavity 124 and the top surface of the adjacent heat spreader 120a. In other words, when at least one heat spreader 120 is stacked on another heat spreader 120a, similar to that described with reference to the multiple tiers 230, the top surface of the heat spreader 120a rests on the angled portions 332, 336 of the multiple tiers 330 with a small contact area approximating line or point contact. For example, FIG. 8C illustrates a portion of a second heat spreader 120a stacked and positioned on a heat spreader 120 such that the second heat spreader 120a engages the angled portions 332, 336 of the second tier 330b and the second heat spreader 120a is spaced apart from the inner cavity surface 140.

[0032] 9A-9C further illustrate additional embodiments of a heat spreader having multiple tiers 430. In an exemplary embodiment, the heat spreader 120 includes a first tier 430a, a second tier 430b, a third tier 430c, and a fourth tier 430d. FIG. 9B illustrates an enlarged top view of one of the tiers 430. Specifically, the third tier 430c is illustrated. The following description is provided with reference to the third tier 430c, but the description may apply to any of the other tiers 430a, 430b, or 430d.

[0033] 9B, the third step 430c may have a generally semi-elliptical and triangular shape. More specifically, the shape of the third step 430c may be defined by a generally arcuate or curved surface 432 and a straight surface 436. As illustrated, the straight surface 436 may extend from the second side 122b to the third side 120c of the heat spreader 122. However, as previously described, any of the other steps of the plurality of steps 430 may have a generally semi-elliptical and / or triangular shape, as well as respective curved and / or straight surfaces extending between various combinations of the first, second, third and fourth sides 122a-d of the heat spreader 120.

[0034] FIG. 9C illustrates generally the cross-sectional profile of the third tier 430c shown in FIG. 9B with an exaggerated representation of the surfaces for clarity. As illustrated, the schematic cross-sectional profile of the third tier 430c includes an angled portion 436 extending from an inner wall 434 of the cavity. The angled portion 436 may extend downwardly at an angle of about 2 degrees to about 4 degrees relative to the longitudinal axis L (FIG. 4B) of the heat spreader 120. Further, the third tier 430c is additionally defined by a cliff portion 438 that extends vertically downwardly and is coupled with a flat portion 440. As illustrated in phantom, the second heat spreader 120a may engage the straight surface 436 such that contact between the second heat spreader 120a and the inner cavity surface 140 of the cavity 124 is reduced.

[0035] Aspects Aspect 1 is a heat spreader including an upper surface opposite the bottom surface, and a cavity formed in and extending upwardly from the bottom surface, the cavity including an inner wall extending around the cavity and extending vertically downward from an inner cavity surface of the cavity. The heat spreader further includes an outer periphery extending vertically upward from the bottom surface of the heat spreader and extending around the cavity, and at least one step disposed within the cavity and having a surface positioned at a vertical height that is lower than the vertical height of the inner cavity surface of the cavity.

[0036] Example 2 is the heat spreader of Example 1, wherein the heat spreader is defined by a generally rectangular shape having a length, a width, and a depth.

[0037] Example 3 is the heat spreader of Example 2, wherein the cavity has a rectangular shape such that the cavity defines a length and a width.

[0038] Example 4 is the heat spreader of Example 3, wherein the outer perimeter extends between a length of the heat spreader and a length of the cavity, and between a width of the heat spreader and a width of the cavity.

[0039] Example 5 is a heat spreader according to any of Examples 1-4, wherein the cavity includes at least two steps extending parallel to and adjacent to the first and third sides of the cavity and extending the length of the cavity.

[0040] Example 6 is the heat spreader of any of Examples 1-5, wherein the cavity includes at least two steps having a generally rectangular, semi-elliptical, or other irregular shape.

[0041] Example 7 is the heat spreader of any of Examples 1-6, wherein the cavity includes at least four steps positioned adjacent an inner wall of the cavity.

[0042] An eighth embodiment is the heat spreader of any one of the first to seventh embodiments, wherein at least one step has an inclined portion extending from an inner wall of the cavity and a flat surface extending from the inclined surface to a bottom surface of the cavity.

[0043] Aspect 9 is a heat spreader according to any of aspects 1 to 8, wherein at least one step includes a first inclined surface extending from an inner wall of the cavity, a second inclined surface extending from the cavity, and a flat surface extending between the first inclined surface and the second inclined surface.

[0044] Example 10 is the heat spreader of Example 9, wherein the flat surface is continuous with an inner cavity surface of the cavity.

[0045] Example 11 is a heat spreader of any of Examples 1-10, wherein at least one step of the cavity includes a cliff portion extending vertically downward from the outer periphery of the heat spreader to a sloped portion, where the sloped portion joins with a flat portion of the step.

[0046] Example 12 is a heat spreader according to any of Examples 1 to 11, wherein the heat spreader has a total thickness defined by the thickness of the cavity and the bottom surface of the heat spreader, and the outer periphery has a thickness, and the thickness of the outer periphery is less than the total thickness of the cavity.

[0047] A thirteenth aspect of the present invention is the heat spreader according to any one of the first to twelfth aspects, wherein the heat spreader is made of copper.

[0048] A fourteenth aspect is a heat spreader including a cavity extending from within the bottom surface, a top surface opposite the bottom surface, the cavity including an inner wall extending about the cavity and extending vertically downward from an inner cavity surface of the cavity. The heat spreader additionally includes an outer periphery extending vertically upward from the bottom surface of the heat spreader and extending about the cavity, and four steps positioned within the cavity and disposed at four respective corners of the cavity, each step extending from the outer periphery of the heat spreader to the inner cavity surface of the cavity such that at least a portion of the cavity includes an inclined surface.

[0049] Example 15 is the heat spreader of Example 14, wherein the sloped surface of each step is positioned at a vertical height that is lower than the vertical height of the bottom surface of the cavity.

[0050] Example 16 is the heat spreader of Example 14 or Example 15, wherein the heat spreader has a thickness that is greater than a thickness of the outer perimeter.

[0051] Example 17 is a method of forming a heat spreader, the method including: stamping a center surface of a sheet of material with a die and press of a stamping system to move material outward from the center surface to form a cavity and forming an outer periphery extending along the cavity; holding the material of the cavity constant such that a thickness of the cavity remains constant; and, during the step of holding the material, stamping the outer periphery to move material inward from the center surface to define multiple steps within multiple corners of the cavity.

[0052] Example 18 is the method of example 17, wherein the plurality of steps includes four steps, the plurality of corners includes four corners, and each of the plurality of steps is disposed at one of the corners of the cavity.

[0053] Example 19 is the method of example 17 or example 18, wherein each of the steps has a sloped portion extending from an inner wall of the cavity and a flat surface extending from the sloped surface to a bottom surface of the cavity.

[0054] Example 20 is a method according to any of Examples 17-19, wherein each step includes a first inclined surface extending from an inner wall of the cavity, a second inclined surface extending from the cavity, and a flat surface extending between the first inclined surface and the second inclined surface.

[0055] While the invention has been described as having an exemplary design, the invention can be further modified within the spirit and scope of the disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the disclosure as come within known or customary practice in the art to which this invention pertains.

Claims

1. 1. A heat spreader comprising: The top surface opposite the bottom surface, a cavity formed in the bottom surface and extending upwardly from the bottom surface, the cavity including an inner wall extending around the cavity and extending vertically downwardly from an inner cavity surface of the cavity; an outer periphery extending vertically upward from the bottom surface of the heat spreader and extending around a cavity; at least one step disposed within the cavity and having a surface positioned at a vertical height that is less than a vertical height of the inner cavity surface of the cavity.

2. The heat spreader of claim 1 , wherein the heat spreader is defined by a generally rectangular shape having a length, a width, and a depth.

3. 2. The heat spreader of claim 1, wherein the cavity includes at least two steps extending parallel to and adjacent to a first side and a third side of the cavity and extending the length of the cavity.

4. 10. The heat spreader of claim 1, wherein the cavity includes at least two steps having a generally rectangular, semi-elliptical, or other irregular shape.

5. The heat spreader of claim 1 , wherein the cavity includes at least four steps positioned adjacent the inner wall of the cavity.

6. The heat spreader of claim 1 , wherein the at least one step has an angled portion extending from the inner wall of the cavity and a flat surface extending from the angled surface to the bottom surface of the cavity.

7. 2. The heat spreader of claim 1 , wherein the at least one step includes a first angled surface extending from the inner wall of the cavity, a second angled surface extending from the cavity, and a flat surface extending between the first angled surface and the second angled surface.

8. 2. The heat spreader of claim 1, wherein the at least one step of the cavity includes a cliff portion extending vertically downward from the outer periphery of the heat spreader to an angled portion that merges with a flat portion of the step.

9. 2. The heat spreader of claim 1 , wherein the heat spreader has an overall thickness defined by a thickness of the cavity and the bottom surface of the heat spreader, and the outer perimeter has a thickness, the thickness of the outer perimeter being less than the overall thickness of the cavity.

10. 1. A heat spreader comprising: The top surface opposite the bottom surface, a cavity extending from the bottom surface, the cavity including an inner wall extending around the cavity and extending vertically downward from an inner cavity surface of the cavity; an outer periphery extending vertically upward from the bottom surface of the heat spreader and extending around the cavity; and four steps positioned within the cavity and disposed at four respective corners of the cavity, each step extending from the outer periphery of the heat spreader to the inner cavity surface of the cavity such that at least a portion of the cavity includes a sloped surface.

11. The heat spreader of claim 10 , wherein the angled surface of each step is positioned at a vertical height that is less than a vertical height of the bottom surface of the cavity.

12. 1. A method of forming a heat spreader, the method comprising: stamping a central surface of a sheet of material with a die and press of a stamping system to displace material outwardly from the central surface to form a cavity and an outer periphery extending along the cavity; holding the material in the cavity constant so that the thickness of the cavity remains constant; and during the step of holding the material, stamping the outer periphery to displace material inwardly from the central plane to define steps within corners of the cavity.

13. The method of claim 12 , wherein the plurality of steps includes four steps, the plurality of corners includes four corners, and each of the plurality of steps is disposed at one of the corners of the cavity.

14. The method of claim 12 , wherein each of the steps has an angled portion extending from the inner wall of the cavity and a flat surface extending from the angled surface to the bottom surface of the cavity.

15. 13. The method of claim 12, wherein each step includes a first angled surface extending from the inner wall of the cavity, a second angled surface extending from the cavity, and a flat surface extending between the first angled surface and the second angled surface.

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