Integrated Heat Spreader

Abstract

The heat spreader includes a top surface opposite the bottom surface and a cavity extending from the bottom surface, the cavity defined by a profile having at least two steps such that the cavity includes a first surface spaced a first distance from the bottom surface of the cavity and a second surface spaced a second distance from the bottom surface of the cavity, the first distance being less than the second distance. The heat spreader further includes a lid defined by a thickness extending between the bottom surface of the cavity and the top surface of the heat spreader.

Description

[Technical field]

[0001] (CROSS REFERENCE TO RELATED APPLICATIONS) This application claims priority to U.S. Patent Application No. 18 / 124,982, filed March 22, 2023, and U.S. Provisional Patent Application No. 63 / 336,199, filed April 28, 2022, both of which are incorporated by reference in their entireties herein.

[0002] FIELD OF THEINVENTION 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 a top surface opposite a bottom surface and a cavity extending from the bottom surface, the cavity defined by a profile having at least two steps such that the cavity includes a first surface spaced a first distance from a bottom surface of the cavity and a second surface spaced a second distance from the bottom surface of the cavity, the first distance being less than the second distance. The heat spreader further includes a lid defined by a thickness extending between the bottom surface of the cavity and the top surface of the heat spreader.

[0008] In one form thereof, the present disclosure provides a heat spreader including a top surface opposite a bottom surface, a plurality of sides defining a generally rectangular shape of the heat spreader, a cavity extending from the bottom surface, the cavity being defined by a contour having at least two steps such that the cavity includes a first surface spaced a first distance from the bottom surface of the cavity, a second surface spaced a second distance from the bottom surface of the cavity, the first distance being less than the second distance, and a perimeter extending along the plurality of sides of the heat spreader. The heat spreader further includes the three steps of the cavity including a first step extending downwardly from the bottom surface of the cavity, a second step extending downwardly and laterally outwardly from the first step, and a third step extending downwardly and laterally outwardly from the second step and vertically above the perimeter.

[0009] In another of its forms, the disclosure provides a method of forming a heat spreader, the method including stamping a bottom surface of a sheet of material with a die and press of a stamping system such that the cavity has a bottom surface and a top surface to semi-shear the material to form the cavity, holding the material at the bottom and top surfaces of the cavity during the step of holding the material at the bottom and top surfaces of the cavity, and stamping at least a portion of the sheet of material to form a first step extending around the cavity, holding the material of the cavity and the first step constant. The method further includes stamping at least a portion of the sheet of material to form a second step extending around the cavity and the first step during the step of holding the material of the cavity and the first step constant. [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 an exemplary press machine that may be used to manufacture a heat spreader according to an embodiment of the present disclosure. [Figure 4] 1 illustrates a bottom perspective view of an exemplary heat spreader, according to an embodiment of the present disclosure. [Figure 5A] 5 illustrates a bottom view of the exemplary heat spreader of FIG. 4. [Figure 5B] 5B illustrates a cross-sectional view of the example heat spreader of FIG. 5A taken along line 5B-5B. [Figure 6A]1 illustrates a top view of a workpiece according to an embodiment of the present disclosure. [Figure 6B] 6B illustrates a cross-sectional view of the workpiece of FIG. 6A taken along line 6B-6B, according to an embodiment of the present disclosure. [Figure 6C] 6B illustrates a cross-sectional view of the workpiece of FIG. 6A in a schematic exemplary press machine in a first configuration before pressing, according to an embodiment of the present disclosure. [Figure 6D] 6C illustrates a cross-sectional view of the workpiece of FIG. 6A in the schematic exemplary press machine of FIG. 6C in a first configuration after pressing, according to an embodiment of the present disclosure. [Figure 7A] 1 illustrates a top view of a partially formed heat spreader according to an embodiment of the present disclosure. [Figure 7B] 7B illustrates a cross-sectional view of the partially formed heat spreader of FIG. 7A taken along line 7B-7B. [Figure 7C] 7C illustrates an enlarged view of a portion of the cross-sectional view of the partially formed heat spreader of FIG. 7B. [Figure 8A] 7B illustrates a cross-sectional view of the partially formed heat spreader of FIG. 7A within a schematic exemplary press machine in a second configuration before pressing, according to an embodiment of the present disclosure. [Figure 8B] 8B illustrates a cross-sectional view of the partially formed heat spreader of FIG. 7A within the schematic exemplary press machine of FIG. 8A in a second configuration after pressing. [Figure 8C] 1 illustrates a top view of a partially formed heat spreader according to an embodiment of the present disclosure. [Figure 8D] 8D illustrates a cross-sectional view of the partially formed heat spreader of FIG. 8C taken along line 8D-8D. [Figure 8E] 8E illustrates an enlarged view of a portion of the cross-sectional view of the partially formed heat spreader of FIG. 8D. [Figure 9A] 8D illustrates a cross-sectional view of the partially formed heat spreader of FIG. 8C within a schematic exemplary press machine in a third configuration before pressing, according to an embodiment of the present disclosure. [Figure 9B]9B illustrates a cross-sectional view of the partially formed heat spreader of FIG. 8C within the schematic exemplary press machine of FIG. 9A in a third configuration after pressing. [Figure 9C] 1 illustrates a top view of a heat spreader according to an embodiment of the present disclosure. [Figure 9D] 9D illustrates a cross-sectional view of the heat spreader of FIG. 9C taken along line 9D-9D. [Figure 9E] 9E illustrates an enlarged view of a portion of the cross-sectional view of the heat spreader of FIG. 9D.

[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. 4-9B. 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 punch 106 configured to repeatedly move up and down in a vertical direction. 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 a 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 punch 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] Stamping system 100 can be optimized and used in a process to create a target shape and / or configuration of heat spreader 20 shown in FIGS. 2A and 2B or heat spreader 120 as described further herein.

[0014] FIG. 4 illustrates a bottom perspective view of an exemplary heat spreader 120 that may be formed using stamping system 100 (FIG. 3) having an alternative configuration of die 104 and punch 106. As shown, FIG. 4 includes a bottom surface 121 opposite top surface 119 (FIG. 5B). Heat spreader 120 is defined by a generally rectangular shape having a number of sides 122. Illustratively, the number of sides 122 include a first side 122a, a second side 122b, a third side 122c, and a fourth side 122d. Disposed along and extending laterally therefrom each side 122 of heat spreader 120 is a perimeter 126. Additionally, a cavity 124 extends upwardly and inwardly into heat spreader 120 from bottom surface 121. The cavity 124 includes a bottom surface 125 having a generally rectangular shape having a length L1 and a width W1. The cavity 124 includes a first inner wall 128 extending vertically downward from the bottom surface 125 of the cavity 124. The first inner wall 128 is defined by a thickness T1 that is substantially constant about (i.e., equal along) the entire circumference of the first inner wall 128. Extending laterally outward in each direction from the bottom edge of the inner wall 128 (i.e., toward each of the sides 122 of the heat spreader 120) is a first stepped surface 130 that extends around the periphery of the first inner wall 128 of the cavity 124.

[0015] The cavity 124 includes a second inner wall 134 extending vertically downward from the first stepped surface 130. The second inner wall 134 is defined by a thickness T2. Like the thickness T1, the thickness T2 may be substantially constant (i.e., equal) around the entire circumference of the second inner wall 134. Extending laterally from the second inner wall 134 is a second stepped surface 135. As shown, the heat spreader 120 includes a third inner wall 138 extending vertically downward from the second stepped surface 135. The third inner wall 138 defines a thickness T3 and extends vertically to connect to the bottom surface 121 of the heat spreader 120. In other words, the bottom surface 121 extends laterally outward from a top of the third inner wall 138. Like thickness T2, thickness T3 may be substantially constant (ie, equal) around the entire circumference of third inner wall 138.

[0016] Thus, the cavity 124 defines a plurality of steps 146, including a first step 146a and a second step 146b, formed by various stepped surfaces and interior walls. Although shown as including two steps between the bottom surface 125 of the cavity 124 and the bottom surface 121 of the heat spreader 120, various other embodiments may include any number of steps. For example, the plurality of steps 146 may include three or more steps, as needed or desired for a particular application. Generally speaking, an increased number of steps 146 may be used to increase the overall depth of the cavity 124 without requiring a larger overall thickness T4 of the lid 123 and heat spreader 120.

[0017] 5A illustrates a bottom view of the heat spreader 120 showing the cavity 124 extending into the bottom surface 121. As shown, the first stepped surface 130 includes a first portion 132a, a second portion 132b, a third portion 132c, and a fourth portion 132d. The first portion 132a is defined by a width W2, the second portion 132b is defined by a width W3, the third portion 132c is defined by a width W2, and the fourth portion 132d is defined by a width W3. As shown, the width W2 may be approximately equal to the width W3. However, in other embodiments, the width W2 may be greater than or less than the width D3.

[0018] Further, the second stepped surface 135 includes a first portion 136a, a second portion 136b, a third portion 136c, and a fourth portion 136d. The first portion 136a is defined by a width W4, the second portion 136b is defined by a width W5, the third portion 136c is defined by a width W4, and the fourth portion 136d is defined by a width W5. As shown, the width W4 may be less than the width W5, but in various other embodiments, the width W4 and the width W5 may be equal. In further embodiments, the width W4 may be greater than the width W5. However, various other configurations for the width of each portion 136 may be incorporated. For example, each portion 136 may have a different width, or each portion 136 may have the same width.

[0019] FIG. 5B illustrates a cross-sectional view of the heat spreader 120 taken along line 5B-5B of FIG. 5A. As shown, the cavity 124 extends upwardly from the bottom surface 121 and includes a bottom surface 125, a first stepped surface 130, and a second stepped surface 135 that extend around the entire perimeter of the cavity 124. The cavity 124 defines an overall depth D1 that extends from the bottom surface 125 to the bottom surface 121 of the heat spreader 120. Additionally, as shown, a perimeter 126 extends laterally outward from each side 122 of the heat spreader 120. Specifically, in the cross-sectional view of FIG. 5B, the perimeter 126 is shown extending from the first side 122a and the third side 122c, it being understood that the perimeter 126 extends around the perimeter of all sides 122 of the heat spreader 120. Additionally, as shown, the heat spreader 120 includes a lid 123 defined as material extending between a bottom surface 125 of the cavity 124 and a top surface 119 of the heat spreader 120. As shown, the lid 123 is defined by a thickness T4. In an embodiment, the thickness T4 may have a value in the range of about 1 mm to 4 mm. Further, the depth D1 may have a value of about 50% of T4. For example, the depth D1 may be in the range of 0.5 mm to 2.0 mm. However, as the number of steps 146 increases, the depth D1 may increase accordingly.

[0020] The configuration of the first stepped surface 130 and the second stepped surface 135 of the cavity 124 is such that the overall depth D1 of the cavity 124 may be maximized while achieving the desired thickness T4 of the lid 123. Specifically, this may be completed through various stamping processes that partially shear the material of the heat spreader 120 in repeated steps to create various steps 146 that allow the depth D1 to be achieved. In an exemplary embodiment, the partial shear step may be a half shear step, in which the material is displaced by approximately half the thickness T4, as will be further described. This method is further described with reference to FIGS. 6A-9E.

[0021] FIG. 6A illustrates a blank sheet 140, which may be formed from a metal such as copper. The blank sheet 140 may also be referred to herein as a workpiece, which may be cut or otherwise produced from a larger piece of sheet stock. FIG. 6B illustrates a cross-sectional view of the blank sheet 140 showing a top surface 142 and a bottom surface 144 of the blank sheet 140. The blank sheet 140 defines a thickness T5 extending between the bottom surface 144 and the top surface 142. The blank sheet 140 is inserted into a stamping system 200 of FIG. 6C and undergoes processing to reconfigure the blank workpiece 140 into a desired shape of the finished target configuration of the heat spreader 120 shown in FIG.

[0022] As shown in FIG. 6C, the stamping system 200 includes a die 204 and a punch 206, which may be similar to the die 104 and punch 106 described and illustrated above in connection with FIG. 3. As shown, the die 204 has a top surface 208 having a first planar portion 209a, a second planar portion 209b extending from the first planar portion 209a, and a third planar portion 209c extending from the second planar portion 209b. The second planar portion 209b is positioned vertically upward from the first planar portion 209a and the third planar portion 209c, respectively. Furthermore, the second planar portion 209b may define a height H14 that is greater than the height H2 of the first planar portion 209a and the third planar portion 209c. Additionally, as shown, the punch 206 includes a bottom surface 210 having a flat and / or planar profile. In an embodiment, the bottom surface 210 is configured to hold the material of the blank sheet 140 in place such that the geometry of the top surface 142 of the blank sheet 140 remains constant.

[0023] The stamping system 200 further includes a plurality of lower die inserts 214, illustratively a first lower die insert 214a and a second lower die insert 214b. Although two lower die inserts 214 are shown in cross section in FIG. 6C, it is understood that four lower die inserts 214 are provided to correspond to each of the four edges around the entire circumference of the workpiece 140. Each lower die insert 214a, 214b is positioned on a side of the die 204. In other words, the die 204 is sandwiched between the lower die inserts 214a, 214b. As shown, the lower die insert 214 is defined by a height H1 that is approximately equal to a height H2 of the first planar portion 209a and the third planar portion 209c of the die 204.

[0024] Additionally, the stamping system 200 includes a plurality of side inserts 216, illustratively a first side insert 216a and a second side insert 216b, with additional side inserts 216 not shown but corresponding to the two additional lower die inserts described above. The first side insert 216a and the second side insert 216b are positioned adjacent to the first lower die insert 214a and the second lower die insert 214b. In this manner, the lower die insert 214 and the die 204 are sandwiched between the first side insert 216a and the second side insert 216b. As shown, the side insert 216 defines a height H3 that is greater than the height H2 of the lower die insert 214.

[0025] 6C, the stamping system 200 includes a plurality of die plates 218, illustratively a first die plate 218a and a second die plate 218b, with the additional die plates 218 not shown but corresponding to the two additional lower die inserts described above. Each die plate 218a, 218b is positioned adjacent to a side insert 216a, 216b such that the side insert 216, the lower die insert 214, and the die 204 are sandwiched between the die plates 218. As shown, the die plates 218 define a height H4 that may be greater than the height H1 of the die 204, the height H2 of the lower die insert 214, and the height H3 of the side insert 216. Additionally, as shown, the die plates 218 extend vertically and laterally adjacent the entire workpiece 140. In this manner, the stamping system 200 operates as an open tooling system, allowing the material of the blank sheet 140 to extend laterally outwardly beyond the side inserts.

[0026] In addition, stamping system 200 includes a plurality of upper die inserts 220, illustratively a first upper wall 220a and a second upper wall 220b, with additional upper die inserts 220 not shown but corresponding to two additional die inserts as described above. As shown, each of die inserts 220 extends laterally outwardly beyond workpiece 140. Each of die inserts 220 includes a bottom surface having a flat and / or planar contour that may be continuous with the flat contour of bottom surface 210 of punch 206.

[0027] 6C illustrates the blank sheet 140 positioned within the stamping system 200 prior to compressing the punch 206 and die insert 220 onto the blank sheet 140. The compression of the punch 206 and die insert 220 onto the blank sheet 140 is defined by the vertical movement of the die insert 220 and punch 206 onto the blank sheet 140.

[0028] After compression of the blank sheet 140, an intermediate stage of the heat spreader 120 is formed as shown in Figures 7A-7C such that the heat spreader 120 is partially formed. The central portion of the punch 206 presses down on the blank sheet 140 such that the blank sheet 140 is squeezed between the central portion punch 206 and the die 204, while the die insert 220 is forced downward against the central portion of the punch 206, causing the material of the blank sheet 140 to flow upward and laterally outward. This stamping process causes the material to flow outward to form the bottom surface 125 and the periphery 126 of the cavity 124. In particular, this stamping process is a "semi-shear" step that shears the blank 140 and displaces the periphery 126 of the blank 140 from its lid 123 to create the "step" feature shown in Figure 7B and form the cavity 124 and lid 123. In an embodiment, the shear thickness is about 60% or less of the upward thickness T4 (FIG. 5B). As shown in FIG. 6D, the blank 140 is sheared by a step formed by the second planar portion 204 of the die 209b, which contacts the blank sheet 140 to form a first inner wall 128 (FIG. 7B) extending from and around the cavity 124. After this step, both the cavity 124 and the lid 123 are defined by a width W1 (FIG. 7A), and the cavity 124 includes a first depth D1' (FIG. 7B) extending between the bottom surface 125 of the cavity 124 and the bottom surface 121 of the partially formed heat spreader 120. The first depth D1' may have a value of about 60% of the thickness T4 described above. The corresponding height or thickness T1 of the inner wall 128 (FIG. 7C) is equal to D1'. Referring to FIG. 6D, the first stamping process causes material to flow laterally into at least a portion of the vertical space between the side insert 216 and the die insert 220 of the stamping system 200 to form the outer periphery 126 (FIG. 7B).

[0029] To advance toward the target configuration of heat spreader 120 as shown in FIGS. 4-5B, the partially formed heat spreader 120 of FIGS. 7A-7C is inserted into a stamping system 300 for a second stamping process, as described with reference to FIGS. 8A-8E.

[0030] 8A-8B show cross-sectional views of a stamping system 300 that may be similar to the stamping system 200 of FIGS. 6C-6D, but with some variations as described herein. The stamping system 300 includes a die 304 and a punch 306, which may be similar to the die 204 and punch 206. The die 304 includes an upper surface 308 having a first planar portion 309a adjacent to a second planar portion 309b. The second planar portion 309b is positioned adjacent to a third planar portion 309c. Further, the second planar portion 309b may define a height H5 that is greater than the height H6 of the first planar portion 309a and the third planar portion 309c. The punch 306 includes a punch surface having a first planar portion 311a, a second planar portion 311b, and a third planar portion 311c. The second planar portion 311b extends between the first planar portion 311a and the third planar portion 311c and is positioned vertically above the first planar portion 311a and the third planar portion 311c.

[0031] In addition, the stamping system 300 includes a plurality of lower die inserts 314, including a first lower die insert 314a and a second lower die insert 314b as shown, with it being understood that additional die inserts 314 are provided around the entire periphery of the die 304. Each lower die insert 314 is positioned on a side of the die 304 such that the die 304 is sandwiched between the lower die inserts 314. Further, the lower die inserts 314 are defined by a height H7 that is less than the height H6 of the first planar portion 309a and the third planar portion 309c. The stamping system 300 also includes a plurality of side inserts 316, illustratively a first side insert 316a and a second side insert 316b, with it being understood that additional side inserts 316 are provided around the entire periphery of the die 304. As shown, the side inserts 316 extend vertically upward to a height H8 that is greater than the height H7 of the lower die inserts 314. Specifically, side inserts 316 extend vertically upward to a height H8 that is approximately equal to a height H6 of first planar portion 309a and third planar portion 309c of die 304. It is understood that stamping system 300 may further include upper die inserts 320, illustratively first and second upper die inserts 320a and 320b, positioned adjacent punch 306, with the additional upper die inserts 320 disposed about the entire periphery of punch 306 such that punch 306 is sandwiched between the upper die inserts 320.

[0032] As shown in the configuration of FIG. 8A, the punch 306 and the die 304 are both in contact with portions of the heat spreader 120 positioned directly below and above the punch 306 and the die 304. More specifically, the second planar portion 311b of the punch 206 and the second planar portion 309b of the die 304 each have a width that extends across the width W1 (FIG. 4) of the cavity 124. A similar correspondence exists for the length dimensions, such that the area of ​​the second planar portion 311b of the punch 206 corresponds to the area of ​​the top surface of the lid 123, and the third planar portion 309b of the die 304 corresponds to the area of ​​the bottom surface 125 of the cavity 124. This correspondence ensures that the material of the lid 123 and the bottom surface 125 of the cavity 124 are held in place to preserve and maintain the geometry during the second step of the stamping process. However, as best seen in Figure 8A, there is a gap between the lower die insert 314 and the portion of the heat spreader 120 directly above the lower die insert 314. As will be further explained with reference to Figure 8B, this gap allows for additional semi-shearing of the partially formed heat spreader 120 material.

[0033] FIG. 8B illustrates the stamping system 300 after actuation thereof performing a second step of the stamping process to further reconfigure the partially formed heat spreader 120. While the central portion of the punch 306 is held in place, the upper die insert 320 is actuated downwardly to perform a second half-shear cut radially outward of the first half-shear cut described above. Thus, the partially formed heat spreader 120 is advanced downwardly into contact with the plurality of lower die inserts 314. As shown, this configuration of the stamping system 300 and the downward actuation of the upper die insert 320 and punch 306 creates a second step feature in the partially formed heat spreader 120, including the second inner wall 134 of the cavity 124 shown in FIG. 8E. The thickness T2 of the second inner wall 134 is achieved by this additional half-shear cut of material less than 60% of the thickness T10, as shown in FIG. 8E. In addition, the second stamping process moves the perimeter 126 downward into engagement with the side inserts 316. The resulting partially formed heat spreader 120 is shown in Figures 8C-8E.

[0034] FIG. 8C illustrates a top view of a partially formed heat spreader 120 having a lid 123 extending from a top surface 119. FIG. 8D illustrates a cross-sectional view of the heat spreader 120 along line 8D-8D of FIG. 8D. As shown, the cavity 124 includes a bottom surface 125 and a first inner wall 128 that extends downwardly from the bottom surface 125 of the cavity 124 and into a first stepped surface 130 of the cavity 124. A second inner wall 134 extends vertically downwardly from the first stepped surface 130 and into a second stepped surface 135. In this manner, the second stepped surface 135 is vertically offset from the bottom surface 125 of the cavity 124 by a thickness T1 of the first inner wall 128. Further, in this embodiment, cavity 124 is defined by a depth D1'' that extends from bottom surface 125 of cavity 124 and bottom surface 121 of heat spreader 120. Due to the additional semi-shearing of the material of heat spreader 120, depth D1'' shown in FIG. 8D is greater than depth D1' of cavity 124 shown in FIG. 7B.

[0035] Continuing processing of the partially formed heat spreader 120 of FIG. 8C to arrive at the exemplary configuration of heat spreader 120 shown in FIGS. 4-5B, the partially formed heat spreader 120 of FIGS. 8C-8E is inserted into an additional stamping system to undergo a further stamping process, as will be further described with reference to FIGS. 9A-9B.

[0036] 9A-9B show a stamping system 400, which may be a variation of the stamping system 100 of FIG. 3. As shown, the stamping system 400 includes a die 404 and a punch 406, which may be similar to the die 104 and punch 106 described and illustrated above with respect to FIG. 3. As shown, the die 404 has an upper die surface having a first planar portion 409a, a second planar portion 409b positioned on the first planar portion 409a, and a third planar portion 409c positioned on the second planar portion 409b. The second planar portion 409b combines with a fourth portion 409d and additional planar portions, not shown, to create an upper annular punch surface that surrounds the central planar portion 409c and corresponds to the first stepped surface 130, as will be described further below. Similarly, first planar portion 409a, in combination with fifth planar portion 409e and additional planar portions not shown, also as described below, surrounds the upper annular punch surface and creates a lower annular punch surface that corresponds to second stepped surface 135. In this manner, the die surface of die 404 is configured to engage bottom surface 125, first stepped surface 130, and second stepped surface 135 of cavity 124, as well as at least a portion of bottom surface 121 of heat spreader 120.

[0037] Similarly, punch 406 includes a punch surface having a contour configured to engage top surface 119 of heat spreader 120. As shown in FIG. 9A, punch surface of punch 406 includes a first planar portion 411a, a second planar portion 411b, and a third planar portion 411c. Second planar portion 411b combines with fourth planar portion 411d and additional planar portions not shown to create an upper annular punch surface that surrounds central planar portion 411c and corresponds to an upper portion of lid 123 above first stepped surface 130. First planar portion 411a combines with fifth planar portion 411e and additional planar portions not shown to create a lower annular punch surface that surrounds central upper stepped surface and corresponds to an upper portion of lid 123 above what becomes second stepped surface 130 after a second stamping process described below. The various planar portions 411 are vertically offset from one another to seat and tightly engage the contours of the top surface 119 of the heat spreader 120. Thus, in the configuration of Figure 9A, which shows the heat spreader 120 prior to compression of the heat spreader 120 in the stamping system 400, the punch surface of the punch 406 and the opposing die surface of the die 404 are in contact with the portions of the heat spreader 120 directly below and above the punch 406 and die 404, respectively.

[0038] 9A, the stamping system 400 includes a plurality of lower die inserts 414, illustratively a first lower die insert 414a and a second lower die insert 414b. Although two lower die inserts 414 are shown in cross section in FIG. 9A, it is understood that four lower die inserts 414 are provided to correspond to each of the four edges around the entire circumference of the workpiece 140. Each lower die insert 414a, 414b is positioned on a side of the die 404. In other words, the die 404 is sandwiched between the lower die inserts 414a, 414b. As shown, the lower die inserts 414 extend to a height H9 that is less than a height H11 of the first planar portion 409a and the fifth planar portion 409e of the die 404. Moreover, the stamping system 400 further includes a plurality of side inserts 416, illustratively a first side insert 416a and a second side insert 416b, with the additional side insert 416 not shown but corresponding to the two additional lower die inserts described above. It is understood that the first side insert 416a and the second side insert 416b are positioned adjacent to the first lower die insert 414a and the second lower die insert 414b, and the additional die inserts shown here are provided to completely surround the die insert 414. In this manner, the lower die insert 414 and the die 404 are sandwiched between the inserts 416. As shown, the side insert 416 extends to a height H12 that is higher than the height H9 of the lower die insert 414 and is approximately equal to the height H11 of the first planar portion 409a and the fifth planar portion 409e.

[0039] 9A-9B, the stamping system 400 includes a plurality of die plates 418, illustratively a first die plate 418a and a second die plate 418b, with additional die plates 418 not shown but corresponding to the two additional lower die inserts described above. Each die plate 418a, 418b is positioned adjacent to a side insert 416a, 416b such that the side insert 416, the lower die insert 414, and the die 404 are sandwiched between the die plates 418. As shown, the die plate 418 extends to a height H13 that may be greater than the height H11 of the first planar portion 409a and the fifth planar portion 409e, the height H9 of the lower die insert 414, and the height H12 of the side insert 416. Additionally, as shown, the die plate 418 extends vertically upward and laterally adjacent to the workpiece 140. In this manner, the stamping system 400 operates as an open tooling system such that the material of the blank sheet 140 and the partially formed heat spreader 120 can extend laterally outward to form the perimeter 126 .

[0040] Additionally, stamping system 400 includes a plurality of upper die inserts 420, illustratively a first upper die insert 420a and a second upper die insert 420b, with additional upper die inserts 420 not shown but corresponding to the two additional die plates described above. As shown, each of the upper die inserts 420 extends laterally outwardly beyond workpiece 140 and includes a flat / planar profile that may be continuous with the flat / planar profile of bottom surface 410 of punch 406. The various heights of the components of stamping system 400 allow for retention of first inner wall 128, first stepped surface 130, and second inner wall 134 during the final steps of the stamping process.

[0041] 9A , the heat spreader 120 has not yet been compressed within the stamping system 400. Illustratively, the die surface of the die 404 and the opposing punch surface of the punch 406 are positioned in direct contact with the heat spreader 120. However, portions of the heat spreader 120 directly above the plurality of lower die inserts 414 are spaced apart from the lower die inserts 414, and the periphery 126 is shown spaced apart from the side inserts 416 as shown.

[0042] 9B illustrates the heat spreader 120 positioned within the stamping system 400 after actuation of the stamping system 400. More specifically, the top die insert 420 is actuated downward to compress the portion of the heat spreader 120 directly below the top die insert 420 and directly above the bottom die insert 414. In this manner, the portion of the heat spreader 120 is compressed onto the bottom die insert 414 and the heat spreader 120 undergoes additional semi-shearing of the sidewall of the die 404. As shown, this step of the stamping process creates a third interior wall 138 (FIG. 9E) of the heat spreader 120 such that the cavity 124 includes a first stepped surface 130 and a second stepped surface 135.

[0043] The resulting heat spreader 120 is shown in Figures 9C-9E, which is the same heat spreader 120 as shown in Figures 4-5B. As shown, the heat spreader 120 includes a cavity 124 extending inwardly from the bottom surface 121 and having a depth D1, and a first stepped surface 130 and a second stepped surface 135 extending around the perimeter of the cavity 124. The above-described process of semi-shearing the heat spreader 120 allows the depth D1 to be maximized while still maintaining the desired thickness T4 of the lid 123. In other words, if the cavity 124 was stamped in one step in an attempt to achieve the depth D1, the thickness T4 of the lid would likely need to be increased to accommodate material movement without cracking the heat spreader 120. Thus, the repeated half-shear steps allow the lid 123 to maintain a thickness substantially equal to the thickness T4 shown after completion of the first step of the stamping process of Figures 7A-7C. As explained above, the number of half-shear stamping steps may be decreased or increased depending on the overall geometry of the heat spreader and the desired depth of the cavity.

[0044] Although the methods and stamping systems 200, 300, and 400 described above are used to create the heat spreader 120, the methods and stamping systems described above may be modified to achieve a variation in the target heat spreader 120. For example, the methods and stamping systems may be modified to create a heat spreader 120 having three or more steps extending around the perimeter of the cavity 124.

[0045] Aspects Aspect 1 is a heat spreader including a top surface opposite a bottom surface and a cavity extending from the bottom surface, the cavity defined by a profile having at least two steps such that the cavity includes a first surface spaced a first distance from the bottom surface of the cavity and a second surface spaced a second distance from the bottom surface of the cavity, the first distance being less than the second distance. The heat spreader further includes a lid defined by a thickness extending between the bottom surface of the cavity and the top surface of the heat spreader.

[0046] Example 2 is the heat spreader of Example 1, wherein the first surface is defined by a width and the second surface is defined by a width, the width of the second surface being greater than the width of the first surface.

[0047] Example 3 is the heat spreader of Example 1 or Example 2, wherein the cavity has a depth that extends from a bottom surface of the cavity to a bottom surface of the heat spreader.

[0048] A fourth aspect is the heat spreader according to the third aspect, wherein the depth of the cavity has a value ranging from about 0.5 mm to about 2.0 mm.

[0049] A fifth aspect of the present invention is the heat spreader according to any one of the first to fourth aspects, wherein the thickness of the lid is within a range of about 1.0 mm to about 4.0 mm.

[0050] Example 6 is the heat spreader of any of Examples 1 to 5, wherein the heat spreader is formed from copper.

[0051] Example 7 is the heat spreader of any of Examples 1-6, wherein the heat spreader is defined by a first side, a second side, a third side, and a fourth side.

[0052] Example 8 is the heat spreader of Example 7, wherein the heat spreader includes a perimeter extending laterally outward from each side of the heat spreader.

[0053] Example 9 is the heat spreader of any of Examples 1-8, wherein the lid comprises a width approximately equal to a width of the cavity.

[0054] A tenth aspect is a heat spreader including a top surface opposite a bottom surface, a plurality of sides defining a generally rectangular shape of the heat spreader, a cavity extending from the bottom surface, the cavity being defined by a contour having at least two steps such that the cavity includes a first surface spaced a first distance from the bottom surface of the cavity, a second surface spaced a second distance from the bottom surface of the cavity, the first distance being less than the second distance, and a perimeter extending along the plurality of sides of the heat spreader. The heat spreader further includes that the three steps of the cavity include a first step extending downward from the bottom surface of the cavity, a second step extending downward and laterally outward from the first step, and a third step extending downward and laterally outward from the second step and vertically above the perimeter.

[0055] Example 11 is the heat spreader of Example 10, wherein the perimeter extends laterally outward from each of the multiple sides of the heat spreader.

[0056] Example 12 is the heat spreader of example 10 or example 11, wherein the cavity has a depth that extends from a bottom surface of the cavity to a bottom surface of the heat spreader.

[0057] Example 13 is the heat spreader according to Example 12, wherein the depth of the cavity has a value ranging from about 0.5 mm to about 2.0 mm.

[0058] Example 14 is the heat spreader of any of Examples 10-13, wherein the heat spreader includes a lid defined by a thickness extending between a bottom surface of the cavity and a top surface of the heat spreader.

[0059] Example 15 is the heat spreader according to Example 14, wherein the lid has a thickness ranging from about 1.0 mm to about 2.0 mm.

[0060] Aspect 16 is a method of forming a heat spreader, the method including stamping a bottom surface of a sheet of material with a die and press of a stamping system such that the cavity has a bottom surface and a top surface to semi-shear the material to form the cavity, holding the material at the bottom and top surfaces of the cavity during the holding of the material at the bottom and top surfaces of the cavity, and stamping at least a portion of the sheet of material to form a first step extending around the cavity, holding the material of the cavity and the first step constant. The method further includes stamping at least a portion of the sheet of material to form a second step extending around the cavity and the first step during the holding of the material of the cavity and the first step constant.

[0061] Example 17 is the method of example 16, wherein the cavity has a depth that extends from a bottom surface of the cavity to a top surface of the heat spreader.

[0062] Example 18 is the method according to Example 17, wherein the depth of the cavity is in the range of about 0.5 mm to about 2.0 mm.

[0063] Example 19 is the method of example 16 or example 17, wherein a central surface of the sheet of material is stamped to form a lid defined by a thickness extending between a bottom surface of the cavity and a top surface of the sheet of material.

[0064] Example 20 is the method according to Example 18, wherein the thickness of the lid is in the range of about 1.0 mm to about 4.0 mm.

[0065] 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 extending from the bottom surface, the cavity comprising: a cavity defined by a contour having at least two steps, the cavity including a first surface spaced a first distance from the bottom surface of the cavity and a second surface spaced a second distance from the bottom surface of the cavity, the first distance being less than the second distance; a lid defined by a thickness extending between the bottom surface of the cavity and the top surface of the heat spreader.

2. 2. The heat spreader of claim 1, wherein said first surface is defined by a width and said second surface is defined by a width, said width of said second surface being greater than said width of said first surface.

3. The heat spreader of claim 1 , wherein the cavity has a depth that extends from the bottom surface of the cavity to the bottom surface of the heat spreader.

4. The heat spreader of claim 3 , wherein the depth of the cavity has a value ranging from about 0.5 mm to about 2.0 mm.

5. The heat spreader of claim 1 , wherein the lid has a thickness ranging from about 1.0 mm to about 4.0 mm.

6. The heat spreader of claim 1 , wherein the heat spreader is formed from copper.

7. The heat spreader of claim 1 , wherein the heat spreader is defined by a first side, a second side, a third side, and a fourth side.

8. The heat spreader of claim 7 , wherein the heat spreader includes a perimeter extending laterally outward from each side of the heat spreader.

9. The heat spreader of claim 1 , wherein the lid includes a width approximately equal to a width of the cavity.

10. 1. A heat spreader comprising: a top surface opposite a bottom surface and a number of sides defining a generally rectangular shape of the heat spreader; A cavity extending from the bottom surface, the cavity comprising: a cavity including a first surface spaced a first distance from the bottom surface of the cavity and a second surface spaced a second distance from the bottom surface of the cavity, the cavity being defined by a contour having at least two steps such that the first distance is less than the second distance; a perimeter extending along the sides of the heat spreader; the three stages of the cavity include a first stage extending downward from a bottom surface of the cavity, a second stage extending downward and laterally outward from the first stage, and a third stage extending downward and laterally outward from the second stage and vertically above the periphery.

11. The heat spreader of claim 10 , wherein the perimeter extends laterally outward from each of the sides of the heat spreader.

12. The heat spreader of claim 10 , wherein the cavity has a depth that extends from the bottom surface of the cavity to the bottom surface of the heat spreader.

13. The heat spreader of claim 12 , wherein the depth of the cavity has a value ranging from about 0.5 mm to about 2.0 mm.

14. The heat spreader of claim 10 , wherein the heat spreader includes a lid defined by a thickness extending between the bottom surface of the cavity and the top surface of the heat spreader.

15. 1. A method of forming a heat spreader, the method comprising: stamping a bottom surface of the sheet of material with a die and press of a stamping system to semi-shear the material to form a cavity, the cavity having a bottom surface and a top surface; retaining the material on the bottom and top surfaces of the cavity; stamping at least a portion of the sheet of material to form a first step extending around a perimeter of the cavity during the step of retaining the material on the bottom and top surfaces of the cavity; holding the cavity and the first stage material constant; and while holding the cavity and the first step of material constant, stamping at least a portion of the sheet of material to form a second step extending around the cavity and the first step.

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