Patent Application
20250214088
The present disclosure relates to methods and apparatus for removing a ferromagnetic liquid from a surface.
A thermal interface material (“TIM”) is any material that is inserted between two components in order to enhance the thermal coupling between the two components. A TIM is often inserted between a heat-producing device such as an integrated circuit and a heat-dissipating device such as a heat sink. At the interface of each component, a thermal resistance exists and impedes heat dissipation. An effective TIM may be positioned in contact with both of the two components to reduce the thermal resistance at each interface. A few TIMs include a thermal grease, thermal paste, thermal adhesive, thermal gap filler, thermally conductive pads, and liquid metal.
Compared to conventional TIMs such as thermal grease and solder, liquid metal (LM) TIMs offer several advantages owing to their intrinsically high thermal and electrical conductivities, flexibility, and low melting points. Moreover, their unique properties, such as a low vapor pressure, subcooling, and biocompatibility, enable their use in various thermal management applications. However, when cleaning up liquid metal from a thermal interface between two components on a system board of a computer, liquid metal may accidentally drop or leak onto the system board and pose a hazard to the system board.
Attempts to wipe up liquid metal with conventional cleaning supplies are largely unsuccessful because liquid metal does not readily cling to or absorb into cleaning wipes or cotton swabs. Furthermore, it can be quite difficult to protect the system board by masking before moving major components like a heat sink.
Some embodiments provide a method of removing a deposit of a ferromagnetic liquid from a surface. The method may include separating a first component from thermal engagement with a second component, wherein a ferromagnetic liquid thermal interface material is disposed between the first component and the second component to increase heat conduction from the first component to the second component. The method may further include using a removal device that includes at least one magnet to remove an amount of the ferromagnetic liquid thermal interface material that remains on a surface of the first component after the second component has been separated from the first component, wherein the ferromagnetic liquid thermal interface material is magnetically attracted to the removal device by the at least one magnet.
Some embodiments provide a device for removing a ferromagnetic liquid from a surface. The device may include at least one magnet capable of attracting the ferromagnetic liquid and a liquid-permeable material covering at least one surface of the at least one magnet. The liquid-permeable material is configured to directly contact a deposit of the ferromagnetic liquid disposed on a surface and the at least one magnet is configured to draw the ferromagnetic liquid into the liquid-permeable material and retain the ferromagnetic liquid within the liquid-permeable material.
Some embodiments provide a method of removing a deposit of a ferromagnetic liquid from a surface. The method may include separating a first component from engagement with a second component, wherein a ferromagnetic liquid is disposed between the first component and the second component. The method may further include using a removal device that includes at least one magnet to remove an amount of the ferromagnetic liquid that remains on a surface of the first component after the second component has been separated from the first component, wherein the ferromagnetic liquid is magnetically attracted to the removal device by the at least one magnet.
The ferromagnetic liquid may be any known liquid with ferromagnetic properties or components. Some ferromagnetic liquids may be formulated or infused with ferromagnetic particles, such as an iron or nickel powder, iron or nickel filings, or other magnetic materials. A ferromagnetic liquid may be strongly attracted to a magnet secured or embedded in a removal device, such as a cleaning wipe, swab or syringe. Embodiments herein have been shown to greatly improve the capturing and clearing of a ferromagnetic liquid from both flat surfaces and the finest structures, such as crevices. Furthermore, the embodiments may improve retention of the ferromagnetic liquid within the removal device to prevent redepositing of the ferromagnetic liquid elsewhere. The ferromagnetic liquid may have a wide range of viscosity that includes a grease or paste at the higher end of the viscosity range. Non-limiting examples of a ferromagnetic liquid include a thermal interface material (TIM) that enhances thermal conduction between two components, an electrical interface material that enhances electrical conduction between two components, or a mechanical interface material that performs some beneficial mechanical purpose, such as reducing friction between two components.
In some embodiments, the liquid thermal interface material may be a liquid metal. For example, a ferromagnetic liquid metal thermal interface material may include an alloy of gallium, indium and tin that has been infused with iron powder or filings. Galinstan® (a registered trademark of the Geratherm company) is a brand name for an alloy composed of gallium, indium, and tin which melts at −19° C. (−2° F.) and is thus liquid at room temperature. Galinstan is believed to be composed of 68.5% Ga, 21.5% In, and 10.0% Sn (by weight). Galinstan is highly corrosive and should not be spread indiscriminately or allowed to accidentally drip onto components that are not resistant to Galinstan.
The term “ferromagnetic liquid” refers to a liquid that can either be attracted by the magnetic field of a magnet (i.e., are magnetically responsive; temporarily induced magnetization) or can provide the magnetic field that attracts other ferromagnetic materials (i.e., are magnetized; permanent magnetization). For example, a liquid containing iron or nickel powder, filings or other particles may be responsive to an external magnetic field and is therefore a ferromagnetic liquid. In a contrasting example, a liquid containing magnetic particles may form a magnetic field that attracts other ferromagnetic materials or components and is therefore a ferromagnetic liquid. Accordingly, the term “ferromagnetic liquid” may refer to both magnetically response liquids and magnetized liquids. Without limitation, a ferromagnetic liquid may be a “ferromagnetic liquid metal” or a “ferromagnetic liquid metal interface material” or “liquid metal thermal interface material.”
Various embodiments are described herein, including the descriptions of
In some embodiments, the first component is an electronic device, and the second component is a cooling device. Electronic devices, such as integrated circuits, pass electrical current and generate heat as a byproduct of that electrical current. In some instances, the heat must be removed with a cooling device to prevent the electronic device from reaching an operating temperature that either damages the electronic device or causes inefficient operation of the electronic device. Non-limiting examples of the cooling device include a heatsink and a liquid cooling plate. A typical heat sink has a base that thermally engages the electronic device and a set of fins extending away from the base, such that air circulation across the surfaces of the fins will absorb heat from the fins and carry that heat away from the heatsink. A typical liquid cooling plate will also thermally engage the electronic component, but the cooling plate has internal channels where a cooling fluid may be circulated between a cooling fluid inlet and a cooling fluid outlet. Accordingly, the cooling fluid absorbs the heat generated by the electronic device and carries that heat away when it passes through the cooling fluid outlet.
In some embodiments, the removal device includes a liquid-permeable cloth sheet secured to the at least one magnet. The term “cloth” refers to a pliable material made usually by weaving, felting, or knitting natural or synthetic fibers and filaments. A “cloth sheet” is one or more pieces of cloth that has a broad surface relative to its thickness. The at least one magnet may be secured in any manner, such as with use of an adhesive, a fastener, pockets, or via quilting. Some manners of securing the at least one magnet may be temporary, such as pockets, and some manners of securing the at least one magnet may be permanent, such as sewing or quilting. Where the at least one magnet is a plurality of magnets, each of the magnets is preferably secured to the same side of the cloth sheet so that the opposite side of the cloth sheet is free from magnets for contacting the ferromagnetic liquid.
Some embodiments may further include placing, such as wiping, blotting or other manner of engaging, the liquid-permeable cloth sheet in contact with the surface of the first component. As the liquid permeable cloth sheet contacts the surface, the at least one magnet attracts the ferromagnetic liquid thermal interface material into the liquid-permeable cloth sheet and retains the ferromagnetic liquid thermal interface material within the liquid-permeable cloth sheet. The liquid-permeable cloth sheet has pore spaces or voids that allow the ferromagnetic liquid to flow therethrough toward the at least one magnet. Specifically, the at least one magnet forms a magnetic field that extends through the thickness of the liquid-permeable cloth sheet such the magnetic field may act upon the ferromagnetic liquid. The pore spaces and/or voids provide a matrix that, in combination with the at least one magnet, supports and retains the ferromagnetic liquid.
In some embodiments, the removal device includes a liquid-permeable swab secured to a distal end of a rod, wherein the distal end of the rod is formed by the at least one magnet. Similar to the liquid-permeable cloth sheet secured to at least one magnet, the liquid-permeable swab may be temporarily or permanently secured to the distal end of the rod that forms the magnet. For example, the liquid-permeable swab may be permanently secured to the rod with an adhesive. In another example, the liquid-permeable swab may be temporarily secured to the rod by configuring the swab like a sock that fits snugly over the distal end of the rod or is otherwise securable over the distal end of the rod. The liquid-permeable swab and magnet may remove a ferromagnetic liquid in substantially the same manner as described for the liquid-permeable cloth sheet and magnet. The primary difference between the liquid-permeable swab and liquid-permeable cloth sheet is the physical configuration (i.e., size and shape). Specifically, a liquid-permeable cloth sheet with at least one magnet may be well-suited for removing ferromagnetic liquid over a large and easily accessible area, such as the top surface of a component. By contrast, a liquid permeable swab with at least one magnet may be well-suited for removing ferromagnetic liquid from a small and difficult to reach area, such as a crevice within a component or between two components.
Some embodiments may further include engaging the liquid-permeable swab with a surface of the first component, wherein the at least one magnet attracts the ferromagnetic liquid thermal interface material into the liquid-permeable swab and retains the ferromagnetic liquid thermal interface material within the liquid-permeable swab. A user may manually manipulate the liquid-permeable swab by holding the rod with their fingers.
In some embodiments, the removal device is a syringe having a needle tip that includes the at least one magnet. The syringe may include a barrel, a plunger that is slidable within the barrel, and the needle tip, wherein the needle tip forms a passageway into the barrel below the plunger. Without limitation, the at least one magnet may be a ring that extends around the opening in the needle tip or a plurality of magnets positioned around the opening in the tip. A preferred syringe is a 1 milliliter (mL) syringe with a tip that is adapted for a 23 gauge needle. The size of the opening in the needle tip is preferably large enough to allow the ferromagnetic liquid to easily flow through the tip despite potentially containing iron filings or having a high viscosity. Furthermore, the plunger of the syringe could have a magnet that helps draw the ferromagnetic liquid into the syringe.
Some embodiments may further include positioning the needle tip of the syringe adjacent a pool of the ferromagnetic liquid that remains on the surface of the first component, wherein the at least one magnet attracts the pool of ferromagnetic liquid to an opening that leads to the passageway in the tip. In this position, a user may then actuate (pull) the plunger relative to the barrel to form a suction that pulls the ferromagnetic liquid from the area of the opening through the passageway and into the barrel. Subsequently, the plunger may be pressed into the barrel to dispense the ferromagnetic liquid into a container, such as a waste collection container or a recycling collection container. The syringe may be used to remove ferromagnetic liquid from the surface and dispense the ferromagnetic liquid into a container through any number of cycles.
Some embodiments provide a device for removing a ferromagnetic liquid from a surface. The device may include at least one magnet capable of attracting the ferromagnetic liquid and a liquid-permeable material covering at least one surface of the at least one magnet. The liquid-permeable material is configured to directly contact a deposit of the ferromagnetic liquid disposed on a surface and the at least one magnet is configured to draw the ferromagnetic liquid into the liquid-permeable material and retain the ferromagnetic liquid within the liquid-permeable material.
Embodiments of the device may include any of the structures, configurations, and materials described herein, including the description of methods for removing a ferromagnetic liquid.
In some embodiments, each of the plurality of magnets are secured to a back side of the cloth sheet in a spaced-apart pattern leaving a front side of the cloth sheet for contacting the surface and preventing direct contact between any of the plurality of magnets and the surface.
In some embodiments, the liquid-permeable material is secured to a distal end of a rod, and the distal end of the rod is formed by the at least one magnet. In one option, the liquid-permeable material may be a wad of fibers. In another option, the liquid-permeable material forms a cover or sock that is manually securable to the distal end of the rod and manually removable from the distal end. Such a cover or sock may be disposable so that the rod with the magnet is reusable. Furthermore, the liquid-permeable material may be attached to a liquid-impermeable inside layer or liner that contacts the at least one magnet and prevents the ferromagnetic liquid from contacting the at least one magnet. Accordingly, removal of a temporary cover or sock having a liquid-impermeable inside layer or liner will leave the magnet in a clean state.
Some embodiments may provide a kit, such as a Field Replaceable Unit (FRU) kit, that includes one or more of the removal devices described herein. The kit may optionally further include a replacement component and/or replacement ferromagnetic liquid. For example, the replacement component may be a heat sink and/or the replacement ferromagnetic liquid may be a thermal interface material. The removal devices may be used to clean up the old or used ferromagnetic liquid thermal interface material, such as a liquid metal or other liquid metal or paste. Any replacement component and/or a container of replacement ferromagnetic liquid included in the kit may then be installed in a system. Even if the material to be removed is not a ferromagnetic liquid, the removal device may still be used since the magnets will not interfere with removing non-ferromagnetic liquids.
In one example, a method may begin with use of a syringe with at least one magnet to remove any large quantities of the ferromagnetic liquid from a surface. When no more of the deposits of ferromagnetic liquid may be removed with a syringe, a liquid-permeable cloth sheet with one or more magnets may be used to contact the surface, such as by wiping the cloth sheet over the surface. After removing as much of the ferromagnetic liquid as possible with the cloth sheet, a liquid-permeable swab with a magnet in the distal end may be used to dap up any remaining ferromagnetic liquid in less accessible areas. Optionally, the same or different syringe, cloth sheet and/or swab may also be used to remove ferromagnetic liquid from a cooling device removed from the surface.
In some embodiments, any final film or trace amounts of the ferromagnetic liquid may be removed by applying isopropyl alcohol and then wiping with a cloth, such as a clean cloth sheet with a magnet. The isopropyl alcohol may be applied to the surface having the ferromagnetic liquid film or trace amounts or may be applied to the cloth.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of the claims. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, components and/or groups, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. The terms “preferably,” “preferred,” “prefer,” “optionally,” “may,” and similar terms are used to indicate that an item, condition or step being referred to is an optional (not required) feature of the embodiment.
The corresponding structures, materials, acts, and equivalents of all means or steps plus function elements in the claims below are intended to include any structure, material, or act for performing the function in combination with other claimed elements as specifically claimed. Embodiments have been presented for purposes of illustration and description, but it is not intended to be exhaustive or limited to the embodiments in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art after reading this disclosure. The disclosed embodiments were chosen and described as non-limiting examples to enable others of ordinary skill in the art to understand these embodiments and other embodiments involving modifications suited to a particular implementation.
