Patent Application
20110162828
The subject matter described herein relates generally to cooling an object and, more specifically, to cooling an electronic component using a thermal plug and a heat sink.
At least some known heat sinks absorb and/or dissipate heat from an object. Moreover, at least some known heat sinks are used in a variety of applications including refrigeration, heat engines, and cooling electronic devices. With recent technological developments in electronic devices, considerable efforts have been made to develop heat sinks that are reliable and efficient.
Some known heat sinks include a thermal plug that facilitates transferring heat from an electronic device to the heat sink. To reduce a thermal resistance of some known plugs, a surface of the plug is positioned parallel to a surface of the electronic device. When a surface of at least some known plugs are positioned in a non-parallel arrangement to the surface of the electronic device, such known plugs contact only a highest point of the electronic device, which results in an increase in thermal resistance and, in at least some instances, an overheating of the electronic device.
In one aspect, a method is provided for assembling a heat sink assembly. A heat sink body that defines a heat sink cavity therein is provided. At least a portion of a thermal plug is positioned within the heat sink cavity. The thermal plug includes a first plug member and a second plug member. The first plug member defines a socket therein, and the second plug member is movable within the socket. A printed circuit board is positioned with respect to the thermal plug. The printed circuit board includes an electronic device. The second plug member is movable such that a surface of the thermal plug is substantially parallel to a surface of the electronic device.
In another aspect, a plug is provided for use with a heat sink body and an electronic device. The plug includes a first plug member and a second plug member. The first plug member defines a socket therein. The second plug member is movable within the socket such that a bottom surface of the second plug member is maintained in a substantially parallel position with respect to a top surface of the electronic device.
In yet another aspect, a heat sink assembly is provided for use with a printed circuit board coupled to an electronic device. The heat sink assembly includes a heat sink body and a thermal plug. The heat sink body defines a heat sink cavity therein. The thermal plug is positioned within the heat sink cavity. The thermal plug includes a first plug member and a second plug member. The first plug member defines a socket therein, and the second plug member is movable within the socket such that a bottom surface of the second plug member is maintained in a substantially parallel position with respect to a top surface of the electronic device.
The methods and apparatus described herein relate to cooling an electronic component using a thermal plug having a bottom surface that is substantially flat. The thermal plug is positioned on the electronic component such that a surface of the electronic component is in contact with the bottom surface of the thermal plug. The thermal plug is configured to facilitate positioning the bottom surface of the thermal plug to be substantially parallel to the surface of the electronic component.
In the exemplary embodiment, BGA package 102 includes at least one substrate 110 having a top surface 112 and a bottom surface 114. In the exemplary embodiment, an electronic device 116 is attached to substrate top surface 112, and a plurality of solder balls 118 are disposed on substrate bottom surface 114. As used herein, the term “electronic device” refers to an object to be cooled using a thermal plug such as described herein. Examples of electronic devices include, without limitation, a semiconductor chip, a microprocessor, a digital signal processor, a graphics processing unit, an integrated circuit, and/or any other suitable heat-generating device. In the exemplary embodiment electronic device 116 has a top surface 120 that is substantially flat.
In the exemplary embodiment, PCB 104 includes a layer 122 having a top surface 124 and a bottom surface 126. In the exemplary embodiment, layer 122 is fabricated from a dielectric material. More specifically, in the exemplary embodiment, layer 122 is fabricated from polyimide. It should be appreciated that layer 122 may be fabricated from any suitable material including, without limitation, a thermally conductive plastic material. In one embodiment, a copper plate is coupled to, and is coincident with, layer bottom surface 126.
Additionally, in the exemplary embodiment, PCB 104 includes a plurality of contact pads 130 coupled to layer top surface 124. In the exemplary embodiment, the number of contact pads 130 corresponds to the number of solder balls 118. In the exemplary embodiment, solder balls 118 are attached to contact pads 130. More specifically, each solder ball 118 attaches to a corresponding contact pad 130, thereby coupling BGA package 102 to PCB 104.
In the exemplary embodiment, heat sink body 106 has a first surface 132 and a sidewall 134 that at least partially defines a cavity 136. In the exemplary embodiment, heat sink body 106 is fabricated from a material having a high electrical conductivity and/or a high thermal conductivity. More specifically, in the exemplary embodiment, heat sink body 106 is fabricated from aluminum, copper, aluminum alloy, aluminum composite, copper alloy, copper composite, and/or graphite.
In the exemplary embodiment, thermal plug 108 facilitates transferring heat from electronic device 116 to heat sink body 106. In the exemplary embodiment, thermal plug 108 includes a female body or, more broadly, a first plug member 138 and a male heat spreader or, more broadly, a second plug member 140. In the exemplary embodiment, first plug member 138 and second plug member 140 are fabricated from a material having a high electrical conductivity and/or a high thermal conductivity. More specifically, in the exemplary embodiment, first plug member 138 and second plug member 140 is fabricated from aluminum, copper, and/or silver.
In the exemplary embodiment, at least a portion of first plug member 138 and/or at least a portion of second plug member 140 is plated using an electroless process for environmental protection of the base metal. More specifically, in the exemplary embodiment, at least a portion of first plug member and/or at least a portion of second plug member 140 has an electroless nickel plate finish. In an alternate embodiment, at least a portion of first plug member 138 and/or at least a portion of second plug member 140 is plated with Indium to reduce a contact resistance of first plug member 138 and second plug member 140.
In the exemplary embodiment, top surface 142 and sidewall 146 are configured to substantially align with heat sink body 106 (shown in
In the exemplary embodiment, top surface 142 defines a cavity 148 configured to receive a biasing member therein (not shown in
In the exemplary embodiment, second plug member top surface 152 is configured to substantially align with first plug member 138 (shown in
In the exemplary embodiment, the concave shape of bottom surface 144 and the convex shape of top surface 152 each has a diameter of less than approximately 50.0 mm. More particularly, in the exemplary embodiment, the concave shape of bottom surface 144 and the convex shape of top surface 152 each has a diameter between approximately 10.0 mm and approximately 35.0 mm. Even more particularly, in the exemplary embodiment, the concave shape of bottom surface 144 and the convex shape of top surface 152 each has a diameter of approximately 20.0 mm to 25.0 mm.
As shown in
Referring back to
Referring to
In the exemplary embodiment, a biasing member 160 is positioned between thermal plug 150 and heat sink body 106. More specifically, in the exemplary embodiment, biasing member 160 is positioned within cavity 148 defined by first plug member top surface 142.
Biasing member 160 facilitates reducing a thermal resistance between electronic device 116, thermal plug 150, and/or heat sink body 106. In the exemplary embodiment, biasing member 160 facilitates positioning thermal plug 108 in robust thermal contact with electronic device 116 and/or heat sink body 106. More specifically, biasing member 160 applies a force on thermal plug 108 to facilitate reducing a gap between thermal plug 108 and electronic device 116 to reduce a thermal resistance between electronic device 116, thermal plug 150, and/or heat sink body 106. Moreover, in the exemplary embodiment, biasing member 160 enables thermal plug 108 to apply a substantially even pressure across top surface 120 of electronic device 116. In the exemplary embodiment, biasing member 160 maintains a constant force on thermal plug 108 through normal use, under vibration and shock, and during thermal cycling. In the exemplary embodiment, biasing member 160 is a spring. Alternatively, biasing member 160 may be an elastomeric rubber material and/or a silicone material.
In the exemplary embodiment, biasing member 160 facilitates supporting pressures of up to approximately 50.0 pounds per square inch (psi). More particularly, in the exemplary embodiment, biasing member 160 facilitates supporting pressures of up to approximately 40.0 psi. Even more particularly, in the exemplary embodiment, biasing member 160 facilitates supporting pressures of up to approximately 30.0 psi. In the exemplary embodiment, biasing member 160 enables heat sink assembly 100 to tolerate various pressures exerted between heat sink body 106, biasing member 160, first plug member 138, second plug member 140, and/or electronic device 116, thereby reducing a probability of exerting an uneven force across surface 120 of electronic device 116.
In an alternate embodiment, first plug member sidewall 146 has a screw thread (not shown) that extends around a periphery of first plug member 138. Moreover, in the alternate embodiment, heat sink body sidewall 134 has a corresponding screw thread (not shown) that is configured to engage the screw thread of first plug member 138. In the alternate embodiment, a thermal interface material (TIM) may be applied to the screw threads to increase a contact area and, thus, reduce a thermal resistance. In the alternate embodiment, first plug member 138 is screwed into heat sink body 106 using a torque driver (not shown).
In the exemplary embodiment, a thermal interface material (TIM) 162 is provided between two material surfaces to facilitate reducing a thermal resistance between the two material surfaces. More specifically, in the exemplary embodiment, TIM 162 is applied between two material surfaces to decrease a gap between the two material surfaces and reduce a thermal resistance between the two material surfaces. In the exemplary embodiment, the material surfaces include any combination of heat sink body 106, biasing member 160, first plug member 138, second plug member 140, and electronic device 116. More specifically, in the exemplary embodiment, the material surfaces include any combination of heat sink body first surface 132, heat sink body sidewall 134, first plug member top surface 142, first plug member bottom surface 144, first plug member sidewall 146, second plug member top surface 152, second plug member bottom surface 154, and electronic device top surface 120.
In the exemplary embodiment, TIM 162 is in a film, sheet, and/or foil form or a grease form that is spreadable. In the exemplary embodiment, TIM 162 includes a filler material such as Boron Nitride and/or Aluminum Nitride. One known embodiment of a TIM is the HeatSpring™ material developed by Indium Corporation.
In the exemplary embodiment, a layer (not shown) of an adhesive material is provided to facilitate positioning TIM 162 between the two material surfaces. More specifically, in the exemplary embodiment, a thin layer of the adhesive material is applied on at least one of heat sink body 106, biasing member 160, first plug member 138, second plug member 140, and electronic device 116. Even more specifically, in the exemplary embodiment, a thin layer of the adhesive material is applied on any combination of heat sink body first surface 132, heat sink body sidewall 134, first plug member top surface 142, first plug member bottom surface 144, first plug member sidewall 146, second plug member top surface 152, second plug member bottom surface 154, and electronic device top surface 120. In the exemplary embodiment, the adhesive material is applied using an aerosol adhesive spray. One known embodiment of the aerosol adhesive spray is the Scotch-Weld™ product developed by 3M Corporation.
In the exemplary embodiment, mask 164 shields at least a portion of the material surface to facilitate maintaining contact, and thus thermal conductivity, between two material surfaces. More specifically, in the exemplary embodiment, mask 164 is positioned such that the adhesive material is selectively applied through at least one opening 168 onto at least one of heat sink body first surface 132, heat sink body sidewall 134, first plug member top surface 142, first plug member bottom surface 144, first plug member sidewall 146, second plug member top surface 152, second plug member bottom surface 154, and electronic device top surface 120.
During operation, electronic device 116 generates heat, and thermal plug 108 and/or heat sink body 106 dissipates the heat generated by electronic device 116. More specifically, electronic device 116 generates thermal energy, and thermal plug 108 transfers the thermal energy to heat sink body 106. TIM 162 may be provided between any combination of electronic device 116, first plug member 138, second plug member 140, biasing member 160, and/or heat sink body 106 to further reduce a thermal resistance of heat sink assembly 100.
In the exemplary embodiment, second plug member 140 is positioned 206 with respect to first plug member 138. More specifically, in the exemplary embodiment, a portion of second plug member 140 is positioned in direct contact with first plug member 138 such that first plug member 138 receives a portion of second plug member 140 within socket 150. In the exemplary embodiment, second plug member 140 is oriented such that second plug member top surface 152 faces first plug member bottom surface 144. In the exemplary embodiment, second plug member 140 is placed on the ball of TIM 162 and applies pressure to the ball of TIM 162 such that TIM 162 suitably expands about at least a portion of first plug member bottom surface 144.
In the exemplary embodiment, TIM 162 is applied to BGA package 102 and, more specifically, applied to electronic device top surface 120. In the exemplary embodiment, BOA package 102 is positioned 208 with respect to second plug member 140. More specifically, in the exemplary embodiment, electronic device 120 is positioned in direct contact with second plug member 140 such that electronic device top surface 120 faces second plug member bottom surface 154.
Moreover, in the exemplary embodiment, TIM 162 is provided 210 between any combination of heat sink body 106, biasing member 160, first plug member 138, second plug member 140, and electronic device 116 to reduce a thermal resistance of heat sink assembly 100. In the exemplary embodiment, a thin layer of the adhesive material is applied on at least one surface in a predetermined pattern to selectively position TIM 162 between any combination of heat sink body 106, biasing member 160, first plug member 138, second plug member 140, and electronic device 116. Additionally, to facilitate positioning TIM 162 in the exemplary embodiment, mask 164 is used to apply the adhesive material in pattern 166 on at least one of heat sink body 106, biasing member 160, first plug member 138, second plug member 140, and electronic device 116. Particularly, in the exemplary embodiment, the adhesive material is applied in pattern 166 on at least second plug member bottom surface 154 and electronic device top surface 120. Upon application of the adhesive material, mask 164 is removed from heat sink assembly 100.
In the exemplary embodiment, heat sink body 106 is securely coupled 212 to PCB 104 to increase a thermal conductivity between heat sink body 106, thermal plug 108, and electronic device 116. In one embodiment, a securing mechanism (not shown) is used to enable heat sink body 106 to apply 214 a constant pressure onto PCB 104 suitable to increase a thermal conductivity between thermal plug 108 and electronic device 116 without crushing electronic device 116. For example, the securing mechanism may include, without limitation, at least one clip, screw, spring, and/or clamp.
In the exemplary embodiment, thermal plug 108 is configured to substantially align second plug member bottom surface 154 with electronic device top surface 120. In the exemplary embodiment, as a pressure between thermal plug 108 and electronic device 116 increases, second plug member 140 moves 216, such as rotates, such that the pressure extends across electronic device top surface 120 substantially evenly. In the exemplary embodiment, second plug member bottom surface 154 is forcibly aligned to be substantially parallel with electronic device top surface 120, thereby maintaining robust thermal contact between thermal plug 108 and electronic device 116.
The methods and systems described herein relate to cooling an electronic component using a thermal plug and a heat sink that has a surface that at least partially defines a cavity. The thermal plug includes a first plug member having a bottom surface and a second plug member having a top surface that is substantially complementary to the bottom surface of the top plug member. The first plug member is positioned within the cavity, and the second plug member is positioned with respect to the first plug member such that the bottom surface of the first plug member is in contact with the top surface of the second plug member. The electronic component is positioned with respect to the second plug member such that a surface of the electronic component is in contact with a bottom surface of the second plug member. The thermal plug is configured to facilitate positioning the bottom surface of the second plug member to be substantially parallel to the surface of the electronic component. The exemplary embodiments described herein reduce a thermal resistance between the electronic component, the thermal plug, and/or the heat sink. Moreover, the exemplary embodiments described herein accommodate a manufacturing variability of at least one component. Further, the exemplary embodiments described herein apply an even pressure across a surface of the electronic component.
Exemplary embodiments of cooling an electronic component are described above in detail. The methods and systems are not limited to the specific embodiments described herein, but rather, operations of the methods and components of the systems may be utilized independently and separately from other operations and/or components described herein. For example, the methods and apparatus described herein may have other industrial and/or consumer applications and are not limited to practice with electronic components as described herein. Rather, one or more embodiments may be implemented and utilized in connection with other industries.
As used herein, an element or step recited in the singular and proceeded with the word “a” or “an” should be understood as not excluding plural said elements or steps, unless such exclusion is explicitly stated. Further, references to “one embodiment” are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features. Moreover, unless explicitly stated to the contrary, embodiments “comprising,” “including,” or “having” an element or a plurality of elements having a particular property may include additional such elements not having that property.
This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.
