CN111508914A - Double-sided plush heat conduction blanket for electronic packaging thermal interface material - Google Patents

Abstract

The application discloses a double-sided plush heat conduction blanket for an electronic packaging thermal interface material, wherein the double-sided plush heat conduction blanket for the electronic packaging thermal interface material comprises a layer of base cloth and upright metal fluffs, wherein the base cloth is composed of metal fibers, the number of the metal fibers on the cross section of the base cloth is more than 5, the thickness of the base cloth is 0.05-1.6 mm, the metal fluffs are respectively arranged on the upper surface and the lower surface of the base cloth, the section coverage rate of the metal fluffs is more than 20%, the height of the metal fluffs relative to one side of the base cloth is 0.1-1.0 mm, the diameter of the metal fluffs is 0.005-0.1 mm, and the double-sided plush heat conduction blanket has the characteristics of directional heat transfer and shock absorption of heat along the metal fluffs.

Description

Double-sided fleece thermally conductive blanket for electronic packaging thermal interface material

technical field

The present invention relates to an electronic packaging thermal interface material, in particular to a double-sided fleece thermal conductive blanket used for the electronic packaging thermal interface material.

Background technique

Thermal interface material (Therm Interface Materials, TIM) refers to the interface connection material filled between the chip and the heat dissipation substrate, or between the heat dissipation substrate and the heat sink. The main function is to reduce the interface thermal resistance and improve the heat transfer efficiency. The chip, the heat dissipation substrate and the heat sink are all rigid bodies. If the chip and the heat dissipation substrate, or the heat dissipation substrate and the heat sink are in direct contact, the contact part is only a small amount of convexity due to the surface flatness and roughness of the rigid body components. There are gaps between most of the surfaces, and these gaps are filled with air, and the thermal conductivity of the air is extremely low, only about 0.02W/(m.K). The air gap makes it difficult for the heat to dissipate in time, resulting in overheating of the chip.

In order to fill the gap between various components in electronic products, the thermal interface material is required to be soft and compressible, and can adapt to the size of the gap. At present, the thermal interface material with the largest amount is thermally conductive silicone grease, which is a viscous liquid with strong viscosity. In order to improve the thermal conductivity, it is filled with AlN, ZnO, Al ₂ O ₃ , SiC, aluminum powder, The advantages of silver powder, graphite powder and diamond powder are that they can fully fill the air gap, are cheap and easy to use. But it also has certain defects, such as low thermal conductivity, only 1~4W/(mK), and there is a serious "extrusion effect". The so-called "extrusion effect" is due to the fact that thermal grease is a viscous liquid. During the change process, due to the effect of thermal expansion and contraction, there is a small reciprocating deformation between the chip and the heat dissipation substrate, between the heat dissipation substrate and the heat sink. This small and reciprocating deformation will cause the thermal grease to be squeezed out, resulting in The contact between them is insufficient, the heat dissipation capacity is reduced, and the thermal resistance is increased.

In addition, thermal grease is easy to age when used at high temperature for a long time, cannot be reused after dismantling, and cannot be recycled and reused. Commonly used thermal interface materials are thermal pads. High thermal conductivity fillers are added to elastic polymers to form solid thermal pads with certain flexibility. The thermal conductivity is generally 0.8 ~ 3W/(m.K), and the thickness after installation is generally 0.2～1mm.

In electronic packaging, the packaging pressure is very small, and excessive packaging pressure may damage the chip. The thermal interface material acts as an intermediary for heat transfer. For example, when the heat dissipation substrate and the heat sink are packaged together, the thermal interface material receives the heat from the heat dissipation substrate and transfers the heat to the heat sink. The heat dissipation substrate and the heat sink are rigid bodies. , the gap between the two is not uniform, there is a large gap at one end and a small gap at the other, and the surface of the heat dissipation substrate and the heat sink is not completely smooth, with a certain roughness, and the surface has many tiny bumps and pits. Therefore, as an excellent thermal interface material, it must have a certain degree of flexibility and compressibility in the thickness direction. Under a slight packaging pressure, it can adapt to the packaging gaps of different sizes and fill the uneven pits. , close to the surface of the heat sink and heat sink.

The thermal conductivity of metal materials is much higher than that of polymer materials, but conventional metal materials are rigid, have no flexibility, and are almost incompressible under slight packaging pressure. Even if a relatively compliant copper foil or aluminum foil with a thickness of 0.02mm is used, under slight packaging pressure, there is no compressibility in the thickness direction, and it cannot adapt to packaging gaps of different sizes, nor can it fill uneven surface pits. Therefore, At present, except for liquid metal and brazing alloy, no metal-based thermal interface material has been put into industrial application. If metal is to be used as thermal interface material, the metal material must be soft and compressible.

Therefore, the present invention needs to solve the problem that the conventional metal is rigid and incompressible under slight packaging pressure, so that the metal material is soft and compressible.

IGBT (Insulated Gate Bipolar Transistor, Insulated Gate Bipolar Transistor) is a fully controlled voltage-driven power semiconductor device, which has the advantages of low driving power, fast switching speed and reduced saturation voltage. IGBT module is composed of IGBT and FWD. (Free Wheeling Diode, freewheeling diode chip) Modular semiconductor products encapsulated by specific circuit bridges are the core devices for energy conversion and transmission. They are used in rail transit, smart grid, aerospace, electric vehicles and new energy equipment, etc. It has a wide range of applications. For example, in the electric vehicle charging pile, the IGBT chip plays the role of AC-DC conversion. During the charging process, the AC power is converted into the DC power required by the battery. When driving, the DC power output by the battery is converted into AC power to supply the AC motor. The IGBT chip also needs to regulate the entire vehicle voltage in real time. IGBT is also the core component of the rail transit electric drive control system. The traction electric drive system is the key to the control of high-speed rail and heavy-duty trains. There are two important power modules inside the electric locomotive, namely the main traction converter and the auxiliary converter. The main traction converter provides power for the traction locomotive, with the highest power and voltage, and the working conditions are harsh. The auxiliary converter supplies power for other non-power currents, such as air conditioners, lights, and backup power supplies. The control of the current, voltage and frequency of the main traction converter and the auxiliary converter is realized by the IGBT module. Take the IGBT module for a 7200-kilowatt high-power AC electric locomotive as an example, an IGBT module is encapsulated with 36 chips, which can realize the rapid conversion of current in one millionth of a second. Different from ordinary electronic product chips, IGBT is a power chip, which converts and controls current and voltage. The output power ranges from several KW to thousands of KW, and the current reaches hundreds of amperes. At 175℃, the working temperature of the IGBT package module is higher than that of the ordinary chip. The experiment shows that the failure rate caused by temperature doubles for every 10℃ increase in the working temperature of the chip.

The IGBT module consists of four-layer components and three-layer connections, and adopts the stacked packaging technology. The four-layer structure from top to bottom is IGBT chip, DBC (Direct Bonding Copper) board, heat dissipation substrate, and heat sink. The DBC board is on a ceramic substrate. Double-sided copper-clad motherboard. The three-layer connection is that the IGBT chip and the copper layer of the DBC board are connected by bonding wires and brazing, the DBC board and the heat-dissipating substrate are connected by brazing, and the heat-dissipating substrate and the heat sink are connected by thermal interface material thermal grease , while the substrate and the heat sink are fastened with fasteners. The IGBT chip improves the packaging density through the welding technology, the package is compact, the interconnection length of the wires between the chips is shortened, and the operation speed of the device is improved.

In the three-layer connection of the package, the interface between the first layer of IGBT chip and the DBC board, and the interface between the second layer of DBC board and the heat dissipation substrate is a solder connection, and the soldering material is Sn-Pb series or Sn-Ag series metal solder , high thermal conductivity, generally 20 ~ 80W/(m.K), good heat dissipation performance, and the thermal interface material between the third layer of heat dissipation substrate and the heat sink is thermally conductive silicone grease, the thermal conductivity is only 0.4 ~ 4W/(m.K) time, and there is a serious "crowding out effect". The heat is conducted from the IGBT chip to the DBC board, the heat dissipation substrate, and the heat sink in turn. Between the IGBT chip and the DBC board, and between the DBC board and the heat dissipation substrate, the heat can be transferred smoothly through the metal brazing material, and between the heat dissipation substrate and the heat sink. It is connected by thermal grease, which has a low thermal conductivity, which seriously restricts the transmission of heat and forms a cooling bottleneck, so that the heat generated by the IGBT chip cannot be transferred to the heat sink smoothly, resulting in an increase in the temperature of the chip and a decrease in reliability.

IGBT is mainly used to realize the rapid switching of current, which will generate large power loss, so heat dissipation is an important factor affecting its reliability. In the seven-layer structure of IGBT, the mismatch of thermal expansion coefficient will bring very large thermal stress to each layer. In the case of temperature difference, the deformation of each layer material is different, and different parts of the same layer material will also Because the difference in temperature distribution leads to different degrees of deformation, there will be a problem of excessive local stress, which may lead to cracking of the material. On the other hand, due to the high speed and large bumps of cars and trains, IGBT modules for new energy vehicles and rail transit have long been subjected to random shock loads generated by vehicle vibrations, under the combined action of thermal stress and vibration stress. , it may cause cracks and dislocations between the chip and the DBC board, the DBC board and the heat dissipation substrate, and the heat dissipation substrate and the heat sink, resulting in the failure of the IGBT module.

As a thermal interface material for IGBT packaging, especially for new energy vehicles, high-speed rail, and aerospace IGBT modules that work under bumpy and vibrational conditions, they are subject to large thermal stress and certain random impact stress. Under the action of stress, the package gap may fluctuate to a certain extent. It is required that the thickness of the thermal interface material can fluctuate with the fluctuation of the gap size. Random impact stress improves the reliability of IGBT modules, which puts forward higher requirements for packaging materials, requiring better flexibility, compressibility and resilience.

Therefore, for the thermal interface material for IGBT module packaging, in addition to high thermal conductivity, so that the heat can be smoothly transferred from the heat dissipation substrate to the heat sink, it must also have a certain energy absorption and shock absorption to reduce thermal stress and vibration stress, and greatly improve the IGBT Module reliability.

Patent Application No. 201310659254.X discloses a thermally conductive fabric used as a flexible heat sink, wherein the thermally conductive fabric includes three layers: a surface layer, a base layer and an inner layer. The surface layer is a pure copper wire textile layer, the base layer is a 1:1 blended fabric of copper wire and thermally conductive fiber, and the inner layer is a pure copper wire textile layer. The base layer is provided with a thermally conductive fleece perpendicular to the surface of the base layer, and the thermally conductive fleece passes through the surface layer and the inner layer. The surface layer, the base layer and the inner layer are bonded together by silicon-based glue, and the three-layer copper fabric is bonded by two layers of silicon-based glue. Due to the low thermal conductivity of silicon-based glue, which is lower than 5W/m.K, the thermal conductivity of copper fabric is Therefore, the two layers of silicon-based glue become a heat dissipation barrier layer, forming a heat dissipation bottleneck, which will seriously reduce the thermal conductivity of the copper fabric. The thermally conductive fabric includes a thermally conductive fleece made of carbon fibers passing through the outer layer and the inner layer. Although carbon fiber has high strength, it has poor plasticity and low elongation, generally less than 2%, and its transverse mechanical properties are only about 1% of its longitudinal mechanical properties. Thermally conductive fleece made of carbon fiber is relatively brittle and easy to break after bending. . When the thermal interface material is installed in the gap between the various components in the electronic product, the width of the gap may be smaller than the overall thickness of the thermal conductive fabric, and the carbon fiber thermal conductive fleece is easy to break after bending, and cannot be under the action of resilience. It is close to the surface of electronic components. Therefore, the thermally conductive fabric disclosed in 201310659254.X cannot be used for gaps smaller than its thickness due to its lack of compressibility and resilience. In fact, the purpose of the invention of 201310659254.X It is used as a flexible heat sink, not a thermal interface material connecting the chip and the heat sink, so there is no need to solve the problem of compressibility and resilience.

In addition, US Patent US20040071870A1 discloses a thermal interface material inspired by gecko feet, which incorporate a structure that enables the gecko to run on a glass ceiling or crawl on a slippery glass wall, gecko toes The main features of the structure are: there are thousands of bristles about 5 microns in the pad, and the top of each bristles contains hundreds of fibers with a diameter of about 100 nanometers, each bristles can produce 200μN of cohesive force, This cohesive force is known as the van der Waals force. The main purpose of the adhesive material disclosed in US Patent US20040071870A1 is to generate surface adhesive force, and the technical key to generate surface adhesive force is to use nano-scale fluff, such as carbon nanotubes.

SUMMARY OF THE INVENTION

One object of the present invention is to provide a double-sided fleece thermally conductive blanket for electronic packaging thermal interface material, wherein the double-sided fleece thermally conductive blanket for electronic packaging thermal interface material can be compressed and resilient, especially after stress is removed It can rebound to the initial state and has the performance of energy absorption and shock absorption, especially suitable for the packaging of IGBT modules.

Another object of the present invention is to provide a thermally conductive blanket used as a thermal interface material for electronic packaging, wherein the double-sided fleece thermally conductive blanket for thermal interface material for electronic packaging has directional heat transfer performance.

Another object of the present invention is to provide a thermally conductive blanket used as a thermal interface material for electronic packaging, wherein the double-sided fleece thermally conductive blanket for thermal interface material for electronic packaging can adapt to the gap between a chip and a heat dissipation substrate, or between a heat dissipation substrate and a heat sink and its thermal conductivity is greater than that of the thermal interface material of thermal silicone grease in the prior art, and has better heat transfer and heat dissipation functions.

In order to achieve at least one of the above objects of the present invention, the present invention provides a double-sided fleece thermally conductive blanket for electronic packaging thermal interface materials, wherein the double-sided fleece thermally conductive blanket for electronic packaging thermal interface materials includes:

A layer of base cloth, wherein the base cloth is composed of metal fibers, wherein the thickness of the base cloth is 0.05-1.6 mm; and

The standing metal fluff, wherein the metal fluff is respectively arranged on the upper and lower sides of the base cloth, wherein the single side height of the metal fluff relative to the base cloth is 0.1-1.0 mm, and the diameter of the metal fluff is 0.1-1.0 mm. 0.005-0.1 mm, wherein the yield strength of the metal fluff is greater than half of the theoretical critical destabilizing stress.

According to an implementation of the present invention, the number of metal fibers in the cross-section of the base cloth is 5 or more.

According to an embodiment of the present invention, the base cloth is a woven metal cloth formed by weaving metal yarns, and the thickness of the woven metal cloth is 0.2-1.2 mm.

According to an embodiment of the present invention, the base cloth is a non-woven metal cloth formed by using metal fibers in a non-woven manner.

According to another aspect of the present invention, the present invention provides a double-sided fleece thermally conductive blanket for electronic packaging thermal interface material, wherein the double-sided fleece thermally conductive blanket for electronic packaging thermal interface material comprises:

A layer of base fabric, wherein the base fabric is implemented as being made of metal foil, wherein the metal foil has a thickness of 0.01 to 0.08 mm, wherein the metal foil is provided with a plurality of flocking through holes; and

The standing metal fluff, wherein the metal fluff is respectively arranged on the upper and lower sides of the base cloth, wherein the single side height of the metal fluff relative to the base cloth is 0.1-1.0 mm, and the diameter of the metal fluff is 0.1-1.0 mm. 0.005-0.1 mm, wherein the metal fluff traverses the flocking through hole to form metal fluff on the upper and lower sides of the base fabric, wherein the yield strength of the metal fluff is greater than half of the theoretical critical destabilizing stress.

According to an implementation of the present invention, the hole diameter of the flocking through hole is 0.5-2 mm, and the distance between the centers of two adjacent flocking through holes is 1.5-2 times the hole diameter.

According to an implementation of the present invention, the material of the metal base cloth and the metal fluff is selected from one or more of pure copper, pure aluminum, pure magnesium, pure iron, copper alloy, aluminum alloy, magnesium alloy, and steel alloy. The combination.

According to an implementation of the present invention, the cross-sectional coverage of the metal fluff is greater than 20%.

Further objects and advantages of the present invention will be fully realized by an understanding of the ensuing description and drawings.

These and other objects, features and advantages of the present invention are fully embodied by the following detailed description, drawings and claims.

Description of drawings

1 shows a schematic diagram of the double-sided fleece thermally conductive blanket structure for electronic packaging thermal interface material according to the present invention and its packaging between a chip and a heat dissipation substrate.

FIG. 2 shows a top view of the metal foil base fabric with flocked through holes in one embodiment of the double-sided fleece thermally conductive blanket for electronic packaging thermal interface materials of the present invention.

Detailed ways

The preferred embodiments described below are given by way of example only, and other obvious modifications will occur to those skilled in the art. The basic principles of the invention defined in the following description may be applied to other embodiments, variations, improvements, equivalents, and other technical solutions without departing from the spirit and scope of the invention.

It should be understood by those skilled in the art that in the disclosure of the present invention, the terms "portrait", "horizontal", "upper", "lower", "front", "rear", "left", "right", " The orientation or positional relationship indicated by vertical, horizontal, top, bottom, inner, outer, etc. is based on the orientation or positional relationship shown in the accompanying drawings, which are only for the convenience of describing the present invention and The description is simplified rather than indicating or implying that the device or element referred to must have a particular orientation, be constructed and operate in a particular orientation, and thus the above terms should not be construed as limiting the invention.

1 and 2 of the specification, a double-sided fleece thermally conductive blanket for electronic packaging thermal interface material according to a preferred embodiment of the present invention will be described in detail below, wherein the thermal interface for electronic packaging is described in detail below. A double-sided fleece thermal blanket of material can be used to connect chips to heat sinks, and to connect heat sinks to heat sinks.

It is worth mentioning that the double-sided fleece thermally conductive blanket for electronic packaging thermal interface material is especially suitable for connecting the heat dissipation substrate and the heat sink in the IGBT module. The double-sided fleece thermally conductive blanket for electronic packaging thermal interface material has no extrusion effect and has compressible and resilient properties, and the double-sided fleece thermally conductive blanket for electronic packaging thermal interface material has good properties. Non-uniform gap adaptability.

The invention mainly solves several problems, one is to make the rigid metal material soft and compressible under the action of slight packaging pressure, and the other is to make the thickness of the thermal interface material fluctuate with the fluctuation of the gap size and absorb energy The two ends of the thermal interface material are always close to the surface of the heat dissipation substrate and the heat sink, and a new thermal interface material that is soft and compressible, absorbs energy and absorbs shock, conducts directional heat conduction, and can adapt to the package gap is proposed.

In order to achieve the above purpose, the present invention proposes a solution of processing metal fluff on both sides of the base cloth. The cloth 10 and the metal fleece 20 standing on both sides are formed. There are several types of intermediate layer base cloth, one is a woven cloth made of metal yarns, woven or knitted, and the second is a non-woven fabric made of metal fibers. The processed non-woven metal cloth, the third type is metal foil with sieve-shaped flocking through holes, and the metal fleece 20 is processed from metal fibers. When used in packaging, the double-sided metal fleece thermal blanket is installed on the heat dissipation substrate and the heat sink. Between the two, the metal fleece 20 is soft, bendable, and resilient. Under the action of thermal stress and vibration stress, the metal fleece 20 can bend or spring back with the magnitude of the stress, so that the thickness of the thermal interface material can increase with the thickness of the thermal interface material. fluctuates with fluctuations in the size of the gap. The metal fluff 20 stands on the base cloth 10, so that the metal fluff is arranged in a directional arrangement, and the two ends of the metal fluff are respectively close to the surface of the heat dissipation substrate and the heat sink, so that the heat is transferred from one end of the metal fluff to the other end, and the directional transmission of heat is realized. Solve the problem of directional heat conduction.

The base cloth 10 has three types: woven metal cloth, non-woven metal cloth, and metal foil with flocking through holes. Woven fabric is made of yarn through weaving or knitting process. The yarn is spun from multiple fibers or multiple strands of yarn. The yarn itself is soft, and the processed fabric is as soft as ordinary cloth. It can shrink in the thickness direction. The non-woven metal fabric is made of metal short fibers through a non-woven process, which is soft and compressible. Both woven and non-woven fabrics are soft, but not necessarily compressible. In order to ensure that the metal base The cloth is compressible, and the number of fibers on the cross-section of the metal cloth is more than 5. Under the action of slight packaging pressure, the metal fibers can slide and move with each other, so it has a certain compressibility, which solves the problem of conventional metal fibers. The problem with the rigidity of the material. In the present invention, metal foil can also be used as the base fabric for the intermediate layer. In order to plant metal fluff on the metal foil, it is necessary to process flocking through holes on the metal foil. In order to improve the rigidity of the metal foil, the metal foil with screen-like flocking through holes has higher flexibility than the non-porous metal foil.

For the double-sided fleece thermally conductive blanket for electronic packaging thermal interface material according to the present invention, the metal fleece 20 is required to have a certain yield strength, still in an elastic state after compression and bending, and can return to the initial state after the pressure is removed.

The longitudinal ends of the metal fluff are closely attached to the surface of the heat dissipation base plate and the heat sink respectively, so that the heat is conducted in the longitudinal direction of the metal fluff. The problem that conventional metal foils are difficult to adhere to the surface of the heat dissipation substrate.

By using the method of processing towering metal fluff on the base cloth, the double-sided fluff thermal conductive blanket for electronic packaging thermal interface material of the present invention has the characteristics of softness, compressibility, resilience, and heat conduction along the direction of the metal fluff. The compression and rebound of the metal fluff of the double-sided fluff thermal conductive blanket used for electronic packaging thermal interface material can absorb a certain amount of shock energy. In addition, its adaptive package gap fluctuation solves the shortcomings of conventional metal materials that are rigid, incompressible, and cannot adapt to package gaps, and solves the problem of directional heat transfer, especially for IGBTs that work under vibration conditions. Chip packaging.

Weaving method refers to the method of interlacing or weaving processing fabrics with yarns (warp, weft), including weaving and knitting processes, which are commonly used in the textile industry. Yarn is processed by spinning process, and is processed into a certain fineness product with various textile fibers. Fiber refers to a material with a very small diameter, generally less than 100 microns, and its length is hundreds or even thousands of times the diameter, and has a certain flexibility. The long, slender, soft, continuous strips made of fibers with certain physical and mechanical properties are collectively referred to as yarns. Yarn is a general term for yarn and thread, and a single yarn section contains multiple fibers.

Since the metal fleece 20 is provided on both sides of the base fabric 10 in the double-sided fleece thermally conductive blanket for electronic packaging thermal interface material of the present invention, the base fabric 10 does not need to be too thick, otherwise the thermal conductivity will be reduced. When the metal base fabric is formed by weaving, the thickness of the metal base fabric formed by weaving is preferably 0.2-1.2 mm, and the thickness is less than 0.2 mm. The yarn is easy to break during the weaving process, and the thickness is greater than 1.2 mm. , the thermal conductivity decreases.

When the base fabric 10 is formed by a non-woven process, it is processed by using short metal fibers. Non-woven technology refers to the combination of oriented or randomly arranged fibers by friction, cohesion or adhesion to form sheets, webs or batts. The main processing steps include web forming and web reinforcement.

Fiber web forming is to form fibers into loose fiber webs. The forming methods of metal fiber webs are mainly mechanical web forming and air laying. Air laying is to make fibers move in a certain flow field and uniformly deposit layers in a certain way. , forming a fiber web, which has the characteristics of isotropy, so the present invention adopts the air-laid method to process the metal fiber web, and after the fiber web is obtained, the metal fibers are entangled with each other by mechanical reinforcement method to reinforce each other, and a non-woven metal mat is obtained. . Mechanical reinforcement methods mainly include acupuncture and hydroentanglement. The needling method is to use needles with hooks on the edges to repeatedly needle the fluffy fiber web. wrap around for reinforcement. The spunlace method is a reciprocating and continuous jetting of multiple high-pressure fine water streams to the fiber web, and under the action of water pressure, the fibers are entangled and strengthened during the movement process. Since the spunlace method requires a subsequent drying process, and the metal non-woven mat is easily oxidized, the present invention adopts the needle punching method to reinforce the metal fiber mesh to obtain the metal non-woven fabric.

Compared with the metal base cloth formed by weaving, the metal base cloth formed by non-woven method is more fluffy, soft and compressible, so the thickness of non-woven metal base cloth can be larger than that of woven cloth, but the thickness is too large. , the thermal conductivity is reduced, so the thickness of the metal base fabric formed by non-woven processing should not exceed 1.6mm. On the other hand, when the thickness is less than 0.05mm, the needling reinforcement process becomes more difficult, so the thickness should not be less than 0.05mm. The air-laid process needs to use short metal fibers, the fiber diameter is less than 0.005mm, the fiber processing cost is high, the diameter is greater than 0.05mm, the flexibility is low, and it is not easy to float during air-laying, so its diameter is 0.005 ~ 0.05mm is appropriate. The length of the metal fiber is less than 30mm, and the fibers are not easy to entangle and cohere. When the length is greater than 80mm, it is difficult to air-laid. Therefore, preferably, when the metal base fabric is formed by a non-woven method, the diameter of the metal fiber used during processing is 0.005～0.05mm, length is 30～80mm.

In the above-mentioned embodiment, the forming manner of the metal fluff 20 is similar to the forming manner of the fluff of carpets and fleece in daily life. The textile industry has developed a variety of mature double-sided fluff processing methods, such as floating long-line cutting method, raising method, flocking method, needle punching method and stitching method, which can be used to process the yarn of the present invention. Double-sided fleece thermally conductive blanket for electronic packaging thermal interface materials. The floating long-line cutting pile method is to cut the pile loops formed by pile weft yarns or pile warp yarns floating on the front and back sides of the woven fabric with a certain length, thereby forming double-sided piles. The raising method is also known as brushing and brushing. The fibers on the front and back of the woven fabric or non-woven fabric are hooked and cut through the raising needles on the surface of the card cloth roller of the raising machine to form double-sided fluff. The flocking method includes two methods, the Axminster loom and the tufting loom. The Axminster method is to first cut the fluff into a specified length, and then plant it in a "U" shape or "J" shape consolidation method. Between the ground warp yarn layers of the ground tissue, it is fixed by the weft yarn, and the pile yarn is implanted while weaving the base fabric. The working principle of a tufting loom is similar to that of a sewing machine. Through the up and down reciprocating motion of the tufting needle, the pile yarn worn in the needle eye is implanted into the pre-prepared base fabric, forming loops on the front and back sides, and then tufting the pile. The loops are cut into fluff. Acupuncture method is to use needles with hooks on the edges to repeatedly puncture the fluffy fiber web. While strengthening the fiber web, the hooking hooks the fibers out of the surface of the fiber web to form fluff. The sewing method is to sew the smooth sides of two single-sided fleece fabrics together to form double-sided fleece. The base fabrics of the floating long-line cut pile method and the Axminster method belong to woven fabrics, and the base fabrics of the needle punching method belong to non-woven fabrics. Nonwovens are also possible. After the metal thermally conductive blanket with double-sided fluff is processed by the above method, the fluff can be further regularized, erected and consistent through processes such as shearing and brushing.

The above double-sided fluff processing technology is a relatively mature method in the textile industry. The present invention will not describe in detail. It is only necessary to replace the natural fibers and chemical fibers used in the textile industry with the metal fibers used in the present invention, and those used in the textile industry. Ordinary yarn can be replaced with metal yarn.

In another embodiment of the present invention, the base fabric 10 is implemented as a metal foil. The base fabric 10 is provided with flocking through holes 101 for implanting the metal fluff 20 . After the metal fleece 20 is implanted into the flocking through hole 101 of the base fabric 10 , one end of the metal fleece 20 passes through the flocking through hole 101 , so as to remain on the upper and lower sides of the base fabric 10 . Both sides.

When the base fabric 10 is implemented as a metal foil, the metal fluff 20 can be implanted in the flocking through holes 101 by using a carpet weaving gun or a tufting machine method. Due to the small thickness of the metal foil, it is relatively difficult to use the punching process, so the present invention uses laser drilling to pre-process the flocking through holes 101 on the foil material by a high-energy laser beam to obtain a sieve-shaped metal foil, which is then placed in the foil. The flocking through-holes are implanted with flock yarns, and then the metal fluffs are neatly and stand up through processes such as cutting piles, shearing piles, brushing piles, and the like.

Preferably, when the base fabric 10 is made of metal foil, the flocking through holes 101 are through holes, and the hole diameter d is 0.5-2 mm. Two adjacent flocking through holes 101 The distance L between the centers is 1.5 to 2 times the hole diameter d, that is, L=(1.5 to 2) d.

When the base fabric 10 is made of metal foil, the thickness of the metal foil is 0.01˜0.08 mm.

If the thickness of the foil is less than 0.01mm, it is easy to be torn during the subsequent processing. When the thickness of the foil is greater than 0.08mm, the flexibility becomes low, so the thickness of the metal foil is 0.01-0.08mm. Since the flocking yarn is to be planted on the copper foil, the flocking yarn is a metal yarn spun from many metal fibers, so it is necessary to process the flocking through hole 101 on the copper foil. The diameter of the flocking through hole 101 is small, and the implanted The diameter of the flock yarn is small, the area of the formed metal fluff 20 is small, and the cross-sectional coverage of the metal fluff 20 on the metal foil surface is low, so the diameter of the flocking through hole 101 should not be less than 0.5mm, but if the flocking through hole 101 is flocked The diameter of the flocking yarn is too thick, and it is difficult to cut off when cutting the flock. Therefore, the diameter of the flocking through hole 101 should not exceed 2 mm, so the diameter d of the flocking through hole 101 should be 0.5-2 mm. There is a certain connection strength between the flocking through holes 101, so the distance between the center lines of two adjacent flocking through holes 101 should not be less than 1.5-2 times the hole diameter.

In the present invention, although the base fabric 10 has softness, its compressibility and elasticity are small, so the present invention processes the metal fleece 20 on both sides of the base fabric 10, so that the base fabric 10 can be used as a thermal interface material. The thermally conductive blanket has greater compressibility and resilience.

In the present invention, the one-side height H of the metal fleece 20 relative to the base fabric 10 is 0.1-1.0 mm. If the one-side height H of the metal fleece 20 relative to the base fabric 10 is lower than 0.1 mm, it can be compressed The resistance and resilience are low, higher than 1mm, the thermal resistance will increase, and the material will be wasted, so the height of the metal fluff should be 0.1 ~ 1mm.

In the present invention, the cross-sectional coverage of the metal fluff is greater than 20%. The so-called fluff cross-sectional coverage refers to the percentage of the sum of the cross-sectional area of the fluff and the total area of the base fabric. If the cross-sectional area coverage of the fluff is high, it is used as a packaging material. , the contact area between the fluff and the heat sink and the chip is large, and the heat conduction effect is good. The fluff coverage of traditional flannel or carpet is generally less than 20%. In order to ensure high thermal conductivity, the coverage of metal fluff needs to be greater than 20%. If the cross-sectional coverage of metal fluff is less than 20%, the gap between fluff is large and there are many air gaps. , but will seriously reduce the thermal conductivity.

In the present invention, the metal fluff 20 is made of metal fibers. The smaller the diameter of the metal fibers, the better the flexibility and compressibility, the easier it is to fill the tiny pits on the surface of the chip and the heat sink, increase the contact area, reduce the Small thermal resistance.

For metal fibers, the diameter is 0.005-0.1mm. If the diameter of metal fibers is less than 0.005mm, the fiber processing cost is high. If the metal fibers are too thin, the specific surface area will be large, and it is easy to oxidize and fail. Therefore, the diameter of metal fibers should not be less than 0.005mm. On the one hand, if the diameter of the metal fiber is larger than 0.1 mm, the flexibility is low, so the diameter of the metal fluff 20 is preferably 0.005-0.1. In order to ensure that the metal fluff 20 is still in an elastic deformation state and has a certain resilience after being bent under the packaging pressure, the present invention has a certain plastic yield strength requirement for the metal fibers constituting the metal fluff 20 .

During the encapsulation process, the double-sided fluff thermally conductive blanket for electronic encapsulation thermal interface material is compressed under the action of encapsulation pressure, and the initially erected metal fluff 20 is deflected under the action of the pressure. During the deformation process, each metal fluff 20 can be approximately considered as a slender round rod with one end fixed and one free end, and the free end is subjected to a pressure P along the axis direction. The unilateral height of 10 is H, the diameter is D, the cross-sectional area A=(πD ² )/4, the elastic modulus is E, and the moment of inertia I=(πD ⁴ )/64. According to the Euler formula for the instability of the compression rod, the critical pressure P _c =(π ² EI)/(4H ² ) for the flexural instability of the metal fluff 20, and the critical compressive stress is σ _c =P _c /A=π ² /64(D/H) ² E. In order to ensure that the metal fleece 20 is still in an elastic state after compression destabilization, the plastic yield strength σ _s of the metal fleece 20 should be greater than the critical compression destabilization stress σ _c , that is, σ _s >σ _c .

It is worth mentioning that the critical stress σ _c estimated here is a large value in practical applications, the main reason is that in the process of bending the metal fluff 20, most of the metal fluff is not completely vertical. straight, but inclined, so the actual flexural stress is much smaller than the theoretical critical compressive stress σ _c . Considering the above practical factors, the actual yield strength of the metal fluff 20 may be appropriately smaller than the theoretical critical compressive destabilization stress. Practice has proved that the plastic yield strength of the metal fluff 20 is greater than _0.5σc to ensure that most of the metal fluff 20 After being deflected, it is still in an elastic state, and the yield strength of the metal fleece 20 should not be too large, which will lead to an increase in the required packaging pressure.

The metal fluff 20 of the double-sided fluff thermal conductive blanket for electronic packaging thermal interface material of the present invention is still in an elastic state after being bent under a slight packaging pressure, and under the action of the resilience, the metal fluff 20 can be tightly The electronic components that form a gap, such as the chip in the IGBT module and the surface of the heat sink, are adhered, so as to realize the close adhesion of the double-sided fluffed thermal conductive blanket for electronic packaging thermal interface material to the chip and the heat sink. Since the ends of the metal fluff 20 on both sides of the base cloth 10 are in close contact with the heat dissipation substrate and the heat sink, respectively, they play the role of directional heat conduction, and the heat conducts heat along the double-sided fluff for electronic packaging thermal interface material. The blanket is guided from the heat dissipation substrate to the heat sink, therefore, the double-sided fleece thermally conductive blanket for electronic packaging thermal interface material of the present invention has the feature of directional thermal conduction. Compared with the conventional thermally conductive silicone grease, the thermal conductivity of the double-sided fleece thermally conductive blanket for electronic packaging thermal interface material of the present invention is much greater than that of the thermally conductive silicone grease in the prior art, and has the advantages of compressibility, resilience, The characteristics of directional heat conduction can not only buffer vibration energy, but also naturally relax the small deformation of IGBT components caused by cyclic thermal stress to a certain extent, and release fatigue thermal stress, which is an advantage that other thermal interface materials do not have.

The double-sided fleece thermally conductive blanket for electronic packaging thermal interface material of the present invention has a similar structure to traditional carpets and fleece, and is composed of the base fabric 10 and the metal fleece 20, so the carpet and fleece can be processed The method is transplanted to process the double-sided fleece thermally conductive blanket for electronic packaging thermal interface material of the present invention, thereby making the processing process simple.

For IGBT modules that work under severe vibration conditions, the double-sided fleece thermal conductive blanket for electronic packaging thermal interface material of the present invention can be stacked and used in multiple sheets to increase the thickness of the thermal interface material and further improve the flexibility of the thermal interface material. , compressible, improve the ability to absorb certain vibration energy, reduce the stress on the module components.

The double-sided fleece thermally conductive blanket used for electronic packaging thermal interface material of the present invention has no adhesiveness. In the case where the thermal interface material and the surface of the heat dissipation substrate are required to have a strong bonding force, the thermal interface material of the metal blanket of the present invention can be combined with the traditional thermal interface material. Thermally conductive silicone grease, thermally conductive adhesive, etc. are used in combination, and silicone grease is dropped into the metal fluff 20 of the double-sided fluff thermal conductive blanket used for electronic packaging thermal interface materials, and then packaged, such as packaged in the heat dissipation substrate and the IGBT module. between the heat sinks, which can improve the bonding force of the double-sided fluffed thermal conductive blanket for electronic packaging thermal interface material with the chip and the heat sink.

The power of the IGBT chip is large, up to thousands of kw, and the operating temperature is high, up to 175 °C, and the operating temperature fluctuates in a wide range. With the temperature gradient from high to low, the materials of the four-layer components are different, and the thermal expansion coefficient is different. With the fluctuation of temperature, there is a fluctuating thermal stress between the components of each layer. On the other hand, for new energy vehicles, high-speed rail and other bumps , IGBT modules working under vibration conditions will be subjected to random or regular vibration shocks, and vibration stress will be generated between components. Under the combined action of long-term cycle thermal stress and vibration stress, the structure fatigue cracking and reduce the reliability of the IGBT module. The double-sided fleece thermal conductive blanket for electronic packaging thermal interface material of the present invention has high thermal conductivity, softness, high compressibility and resilience, and can buffer part of thermal stress and vibration stress, thereby improving the reliability of the IGBT module . The end of the metal fluff 20 on one side of the base cloth 10 of the double-sided fluff thermal blanket for electronic packaging thermal interface material of the present invention is closely attached to the surface of the heat dissipation substrate or heat sink, and the other side of the base cloth 10 The end of the metal fluff 20 on one side is closely attached to the surface of the heat sink or the heat dissipation substrate, so as to realize the directional conduction of heat along the double-sided fluff thermal conductive blanket for electronic packaging thermal interface material.

It is worth mentioning that the base cloth 10 and the metal fluff 20 can be implemented as made of metal fibers, and the materials of the metal fibers are generally copper and copper alloys, aluminum and aluminum alloys, magnesium and magnesium alloys, and Steel alloy material.

It is understood that the thermal conductivity of metals is high, much higher than that of polymer materials and polymers. For example, at room temperature, the thermal conductivity of silver is 429W/(m.K), copper is 401W/(m.K), and gold is 263W/(m.K) ), aluminum 237W/(m.K), tungsten 173W/(m.K), magnesium 148W/(m.K), molybdenum 138W/(m.K), zinc 116W/(m.K), chromium 97.3W/(m.K), nickel 90W/(m.K) ), pure iron 80W/(m.K), platinum 71W/(m.K), tin 67W/(m.K), lead 34.8W/(m.K), vanadium 30.7W/(m.K), zirconium 20W/(m.K), titanium 15W/ (m.K), manganese 7.8W/(m.K).

For alloy materials, C17510 beryllium copper alloy 245W/(m.K), 1050 aluminum alloy 209W/(m.K), 6063 aluminum alloy 201W/(m.K), 6061 aluminum alloy thermal conductivity 155W/(m.K), 5052 aluminum alloy Alloy 138W/(m.K), 7075 aluminum alloy 130W/(m.K), 2024 aluminum alloy 121W/(m.K), Cu-35Zn brass alloy (35wt% zinc) 119W/(m.K), C17200 beryllium copper alloy 105W/ (m.K), AZ31 magnesium alloy 96W/(m.K), C5210 phosphor bronze 63W/(m.K), C72700 copper-nickel-zinc alloy 50W/(m.K), gallium (melting point 29.9℃) 40.6W/(m.K), stainless steel 10～30W /(m.K) (316L and 301 stainless steel 16W/(m.K)), nickel-chromium alloy (containing 20wt% chromium) 13.4W/(m.K), N0440 nickel-copper alloy 13.4W/(m.K), Ti-6Al-4V titanium alloy 6.7W/(m.K).

Thermal grease is the most commonly used thermal interface material in the prior art. Its thermal conductivity is only about 1 to 5W/(m.K), generally 2W/(m.K). The thermal conductivity of copper is 200 times that of thermal grease. Even 316L stainless steel with low thermal conductivity has thermal conductivity three times higher than that of silicone grease, so using metal or/and alloy material as thermal interface material in the present invention can improve the double thermal conductivity of the thermal interface material for electronic packaging. Fleece thermal blanket thermal conductivity. Although pure silver, pure gold, and pure platinum have high thermal conductivity, they are expensive. Lead has neurotoxicity problems, and tin yield strength is too low. These metals are not suitable for thermal interface materials. Most of the other metals and their alloys can be used for processing. Metal fibers are generally used as the material of the thermal interface material of the present invention due to comprehensive consideration of thermal conductivity, cost, processability, etc., copper and copper alloys, aluminum and aluminum alloys, magnesium and magnesium alloys, and steel materials. Copper and copper alloys have high thermal conductivity, but are more expensive, have higher density and higher cost. They are suitable for occasions with high requirements for heat dissipation. Aluminum and aluminum alloys have moderate thermal conductivity, density and cost, and are well machinable. , suitable for most applications, the density of magnesium and magnesium alloys is low, the thermal conductivity is lower than that of aluminum and aluminum alloys, and the workability is low. The rate is low, but the cost of stainless steel fiber is low and the corrosion resistance is high. It is suitable for occasions with high corrosion resistance requirements. In some cases, in order to improve the corrosion resistance or heat resistance of the metal, other metals can be plated on the metal surface, for example, tin plating on the surface of copper wire.

For processing metal woven fabrics, metal non-woven fabrics or metal fluff, the raw materials used are metal fibers. At present, the industry has developed a variety of mature metal fiber processing methods, such as monofilament drawing method, cluster drawing The first two methods can process large-length metal filament fibers, and the cutting method can only produce short fibers. The single-filament drawing method uses multiple dies for continuous drawing, and each die can only draw one long fiber, which has low production efficiency and high cost. The cluster drawing method coats multiple metal wires and then draws them together, which can prepare multiple large-length metal fibers at one time, and has high production efficiency, but the uniformity of wire diameter and surface smoothness are lower than those of the single wire drawing method. The melting and pumping method uses a high-speed rotating roller to dip a liquid thin layer from the alloy melt, and rounds it into filaments through the action of cooling, solidification and its own surface tension, and can prepare medium-length metal fibers. The cutting method uses a tool to scrape metal fibers from solid metal, and can only produce short fibers. The fibers are curved, the surface is rough, and the wire diameter is inconsistent and uneven, but the production efficiency is high. At present, long fibers or short fibers of different materials with wire diameters ranging from 1 to 100 microns are available on the market, and the amount of stainless steel fibers is the largest. These metal long fibers or short fibers are spun into metal yarns, which can be used to weave metal base fabrics. Weaving and knitting methods commonly used in textile technology can be used to process the metal base fabrics used in the present invention.

From the above description, those skilled in the art can understand that, compared with the existing thermal interface materials, the present invention has the following beneficial technical effects:

1. Good energy absorption and shock absorption. The thermal interface material of the present invention has metal fluff on both sides, which can rebound after compression, can adapt to deformation, absorb part of thermal stress and vibration stress, and is especially suitable for IGBTs working under vibration conditions chip, which can improve the reliability of IGBT modules;

2. High thermal conductivity. In the case of using red copper material, its thermal conductivity can reach 100W/(m·K), which is about 30 times that of thermal grease. In the case of using 6063 aluminum alloy material, its thermal conductivity The conductivity can reach 60W/(m·K), which is about 20 times that of thermal grease.

3. It is compressible, resilient, and has good fit. The double-sided fluff thermal conductive blanket used for electronic packaging thermal interface materials of the present invention can adapt to the installation gap under the packaging pressure, and the metal fluff can be closely attached under the action of resilience. The surface of the chip and the heat sink has good adhesion;

4. The heat is directionally conducted, the two ends of the metal fluff are closely attached to the surface of the heat dissipation substrate and the heat sink, and the heat is directionally conducted from the heat dissipation substrate to the heat sink along the metal fluff;

5. No pumping effect, because the thermal interface material of the present invention is solid, there is no liquid pumping effect;

6. No aging, the thermal interface material of the present invention is made of metal fibers, and the materials are copper and copper alloys, aluminum and aluminum alloys, steel alloys, magnesium and magnesium alloys, durable, and there is no aging problem of polymer materials ;

7. Good ease of use, the thermal interface material of the present invention can be cut into the shape of a chip or radiator, and can be placed on the surface of the chip or radiator. It is easy to use, easy to install, easy to replace, easy to clean, and can be reused. It will not flow and contaminate the chip;

8. The thickness can be adjusted, and multiple layers of the thermal conductive blanket of the present invention can be stacked, so as to achieve the effect of further shock absorption and reduction of stress impact;

9. The processing technology is mature and the cost is low. The weaving or non-woven method used is the mature technology of the textile industry, the processing methods are various, and the processing cost is low;

10. The user has a wide range of choices. Metal fiber thermal blankets can be selected, and the corrosion resistance and density are different. Users can choose according to actual needs.

11. After the service life expires, the double-sided fleece thermal conductive blanket for electronic packaging thermal interface material of the present invention can be recycled, while traditional thermal conductive silicone grease cannot be recycled.

Example 1

A double-sided fluff thermal conductive blanket used for electronic packaging thermal interface material, the base fabric and the metal fluff are made of red copper fiber, and the processing method is a floating long-line cutting pile method. The long-line woven fabric, and then the floating long-line pile loop is cut, and then the process of shearing, brushing and other processes is performed to obtain a double-sided fluff thermal conductive blanket for electronic packaging thermal interface material. The base fabric is woven fabric with a thickness of 0.2mm. The height of the single-sided red copper metal fluff is 0.1 mm, the diameter is 0.005 mm, the plastic yield strength is 90 MPa, and the measured thermal conductivity is 101 W/(m·K).

Example 2

A double-sided fluff thermal conductive blanket used for electronic packaging thermal interface material, the base fabric and the metal fluff are made of red copper fiber, and the processing method is a floating long-line cutting pile method. The long-line woven fabric, and then the floating long-line pile loop is cut, and then through the processes of shearing, brushing, etc., to obtain a double-sided fluff thermal conductive blanket for electronic packaging thermal interface materials. The base fabric is woven fabric with a thickness of 0.6mm. The height of the single-sided copper fluff is 0.5 mm, the diameter is 0.01 mm, the plastic yield strength is 90 MPa, and the measured thermal conductivity is 93 W/(m·K).

Example 3

A double-sided fluff thermal conductive blanket used for electronic packaging thermal interface material, the base fabric and the metal fluff are made of red copper fiber, and the processing method is a floating long-line cutting pile method. The long-line woven fabric, and then the floating long-line pile loop is cut, and then through the processes of shearing, brushing, etc., to obtain a double-sided fluff thermal conductive blanket for electronic packaging thermal interface materials. The base fabric is woven fabric with a thickness of 0.9mm. The height of the single-sided copper fluff is 0.3 mm, the diameter is 0.02 mm, the plastic yield strength is 90 MPa, and the measured thermal conductivity is 85 W/(m·K).

Example 4

A double-sided fluff thermal conductive blanket used for electronic packaging thermal interface material, the base fabric and the metal fluff are made of red copper fibers, and the processing method is a tufting machine flocking method. The copper velvet yarn is implanted into the base fabric through the tufting needles of the tufting machine that reciprocate up and down, and loops are woven on the front and back sides of the base fabric. Double-sided fluff thermal blanket encapsulating thermal interface material, the base fabric is woven fabric, the thickness is 1.2mm, the height of single-sided copper fluff is 1.0mm, the diameter is 0.01mm, the plastic yield strength is 90MPa, and the measured thermal conductivity is 79W/ (m·K).

Example 5

A double-sided fluff thermal conductive blanket used for electronic packaging thermal interface material, the base fabric and the metal fluff are made of pure aluminum fiber, the metal fluff is processed by the raising method, and the woven metal base fabric is first woven with pure aluminum yarn, Then, the fine fibers on the base fabric are hooked out by the raising needles on the card cloth roller of the raising machine and cut to form pure aluminum fluff, and then the double-sided fluff for electronic packaging thermal interface material is obtained by shearing, brushing and other processes. Thermal interface material for thermal blanket, the base fabric is woven fabric, the thickness is 0.8mm, the height of single-sided pure aluminum fluff is 0.5mm, the diameter is 0.005mm, the plastic yield strength is 50MPa, and the measured thermal conductivity is 63W/(m·K ).

Example 6

A double-sided fluff thermal conductive blanket used for electronic packaging thermal interface material. The base fabric and the metal fluff are made of AZ31 magnesium alloy fiber. Then, the fine fibers on the base fabric are hooked out by the raising needles on the card cloth roller of the raising machine and cut to form magnesium alloy fluff, and then the double-sided fluff for electronic packaging thermal interface material is obtained by shearing, brushing and other processes. Thermal interface material for thermal blanket, the base fabric is woven fabric, the thickness is 1.2mm, the height of single-sided magnesium alloy fluff is 0.5mm, the diameter is 0.05mm, the plastic yield strength is 35MPa, and the measured thermal conductivity is 23.7W/(m· K).

Example 7

A double-sided fluff thermal conductive blanket for electronic packaging thermal interface material, the base fabric and the metal fluff are both 316L stainless steel fibers, the metal fluff is processed by a tufting machine flocking method, and firstly processed by air-laid and acupuncture reinforcement methods Non-woven fabrics are produced. The raw materials for processing non-woven fabrics are stainless steel fibers with a diameter of 0.005 mm and a length of 30 to 60 mm. After obtaining stainless steel non-woven fabrics, the stainless steel fleece yarn is implanted into the base fabric through the tufting needles of the tufting machine that move up and down. , Weaving loops on the front and back sides of the base fabric, after cutting the loops, through shearing, brushing and other processes to obtain a double-sided fluff thermal conductive blanket for electronic packaging thermal interface materials, the base fabric is a non-woven fabric with a thickness of 0.05 mm, the height of the single-sided stainless steel fluff is 0.6mm, the diameter is 0.01mm, the plastic yield strength is 180MPa, and the measured thermal conductivity is 5W/(m·K).

Example 8

A double-sided fluff thermal conductive blanket for electronic packaging thermal interface material, the base cloth and the metal fluff are made of Cu-35Zn alloy fiber, the processing method is acupuncture, and the raw material is Cu- 35Zn alloy fiber, first use the air-laid process to form a fluffy copper alloy fiber net, and then repeatedly puncture the fluffy fiber net with thorns with barbs through the edges. The copper fibers are hooked out of the surface of the fiber web to form metal fluff, and then the double-sided fluff thermal conductive blanket for electronic packaging thermal interface material is obtained by shearing, brushing and other processes. The base fabric is a non-woven fabric with a thickness of 0.05mm, a single-sided copper alloy fluff height of 0.3mm, a fluff diameter of 0.01mm, a plastic yield strength of 130MPa, and a measured thermal conductivity of 18W/(m·K).

Example 9

A double-sided fluff thermal conductive blanket for electronic packaging thermal interface material, the base cloth and metal fluff are made of pure aluminum fibers, the processing method is acupuncture, and the raw materials are pure aluminum fibers with a diameter of 0.05mm and a length of 30-60mm. First, the air-laid process is used to form a fluffy pure aluminum fiber web, and then the fluffy fiber web is repeatedly punctured with barbs on the edges. Metal fluff is formed on the surface of the fiber web, and then through shearing, brushing and other processes, a double-sided fluff thermal conductive blanket for electronic packaging thermal interface material is obtained. The base fabric is a non-woven fabric with a thickness of 0.8 mm, the height of single-sided aluminum fluff is 1.0 mm, the fluff diameter is 0.05 mm, the plastic yield strength is 50 MPa, and the measured thermal conductivity is 43 W/(m·K).

Example 10

A double-sided fluff thermal conductive blanket used for electronic packaging thermal interface materials, the base fabric and the metal fluff are made of 6061 aluminum alloy fiber, the metal fluff is processed by the raising method, and the non-woven fabric is first processed by air-laid and acupuncture reinforcement Woven fabric, the raw material for processing non-woven fabric is 6061 aluminum alloy fiber with a diameter of 0.03mm and a length of 30 to 60mm. After obtaining the aluminum alloy non-woven fabric, the raising needle on the needle cloth roller of the raising machine is used to hook out the base cloth. The microfibers are cut to form metal fluff, and then through shearing, brushing and other processes to obtain a double-sided fluff thermal conductive blanket for electronic packaging thermal interface materials. The base fabric is non-woven fabric with a thickness of 1.2mm. The height is 0.6mm, the diameter is 0.01mm, the plastic yield strength is 55MPa, and the measured thermal conductivity is 38W/(m·K).

Example 11

A double-sided fluff thermal conductive blanket for electronic packaging thermal interface material, the base fabric and the metal fluff are made of red copper fiber, the metal fluff is processed by the raising method, and the non-woven fabric is first processed by the air-laid and acupuncture reinforcement methods. , the raw material for processing non-woven fabrics is copper fiber with a diameter of 0.012mm and a length of 30-60mm. After obtaining the copper non-woven fabric, the fine fibers on the base fabric are hooked out by the raising needles on the card cloth roller of the raising machine and cut to form The metal fluff is then sheared, brushed and other processes to obtain a double-sided fluff thermal conductive blanket for electronic packaging thermal interface materials. The diameter is 0.01mm, the plastic yield strength is 90MPa, and the measured thermal conductivity is 76W/(m·K).

Example 12

A double-sided fleece thermal conductive blanket for electronic packaging thermal interface material, the base fabric and the metal fleece are both 6063 aluminum alloy fibers, the double-sided metal fleece is processed by a sewing method, and the single-sided metal fleece is first processed. The thickness of the cloth is 0.7mm, the height of the single-sided aluminum alloy fluff is 0.8mm, and then two pieces of flannelette with single-sided fluff are sewed together along the smooth surface to obtain a double-sided fluff thermal blanket, and the base fabric is sewn together. The thickness of the aluminum alloy is 0.2mm, the diameter of the aluminum alloy fluff is 0.01mm, the plastic yield strength is 90MPa, and the measured thermal conductivity is 37W/(m·K).

Example 13

A double-sided fluff thermal conductive blanket used for electronic packaging thermal interface material. The base fabric and metal fluff are both made of 6063 aluminum alloy fiber. The metal fluff is processed by the flocking method of a tufting machine. The base fabric is then inserted into the base fabric through the tufting needles of the tufting machine that reciprocate up and down, and the loops are woven on both sides of the base fabric. , that is, a double-sided fleece thermally conductive blanket for electronic packaging thermal interface material is obtained. The base fabric is a woven fabric with a thickness of 0.5mm, the height of the single-sided aluminum alloy fluff is 0.8mm, the diameter is 0.01mm, the plastic yield strength is 110MPa, and the measured thermal conductivity is 53W/(m·K).

Example 14

A double-sided fluff thermal conductive blanket used for electronic packaging thermal interface material, the base fabric is different from the metal fluff material, the base fabric is made of 6063 aluminum alloy fiber, the metal fluff is made of red copper, and the metal fluff is processed by a tufting machine flocking method. First use 6063 aluminum alloy yarn to weave the woven metal base fabric, then insert the copper velvet yarn into the base fabric through the tufting needle of the tufting machine up and down, and weave loops on both sides of the base fabric, and cut the loops. , and then through shearing, brushing and other processes to obtain a double-sided fluff thermal conductive blanket for electronic packaging thermal interface materials. The base fabric is a woven fabric with a thickness of 0.6 mm, a height of 0.2 mm of single-sided copper fluff, a fluff diameter of 0.01 mm, a plastic yield strength of 90 MPa, and a measured thermal conductivity of 79 W/(m·K).

Example 15

A double-sided fluff thermal conductive blanket used for electronic packaging thermal interface material. The materials of the base cloth and the metal fluff are copper fibers with tin plating on the surface. The metal fluff is processed by the flocking method of a tufting machine. The woven metal base fabric is woven from the thread, and then the tinned copper fiber fleece yarn is implanted into the base fabric through the tufting needles of the tufting machine that reciprocate up and down, and loops are woven on both sides of the base fabric. The process of shearing, brushing and other processes is to obtain a double-sided fluff thermal conductive blanket for electronic packaging thermal interface materials. 0.01mm, the plastic yield strength is 102MPa, and the measured thermal conductivity is 21W/(m·K).

Example 16

A double-sided fluff thermal blanket with double-sided metal fluff used for electronic packaging thermal interface material. The diameter of the copper fibers that make up the metal fluff is 0.01mm, and the plastic yield strength is 90MPa. The flocking through holes with a diameter of 0.5mm are punched by a laser drilling machine, and the distance between the center lines of the two adjacent holes is 0.75mm. The weaving gun inserts the fleece yarn into the flocking through hole, cuts the loop, and then goes through the processes of shearing and brushing to obtain a double-sided fleece thermal conductive blanket. The thermal conductivity measured by the thickness is 83W/(m·K).

Example 17

A double-sided fluff thermal conductive blanket for electronic packaging thermal interface material. The metal foil and metal fluff are made of pure aluminum, the thickness of the aluminum foil is 0.02mm, and the height of the single-sided metal fluff is 0.5mm. The pure aluminum forming the metal fluff The fiber diameter is 0.02mm, and the plastic yield strength is 50MPa. A laser drilling machine is used to punch flocking through holes with a diameter of 1.0mm, and the distance between the center lines of two adjacent holes is 2mm. Holes, cut loops, and then through shearing, brushing and other processes to obtain a double-sided fluff thermal blanket, the measured thermal conductivity is 36W/(m·K).

Example 18

A double-sided fluff thermal conductive blanket for electronic packaging thermal interface material, the foil material is different from the metal fluff material, the metal foil material is aluminum, the metal fluff material is red copper, the thickness of the aluminum foil is 0.06mm, and the height of the single-sided copper metal fluff is 0.8 mm, the diameter of the copper fibers that make up the metal fluff is 0.02mm, and the plastic yield strength is 90MPa. The flocking through holes with a diameter of 2mm are punched by a laser drilling machine, and the distance between the center lines of the two adjacent holes is 3mm. The yarn is inserted into the flocking through hole, and after cutting the loop, the double-sided fluff thermal blanket is obtained by shearing, brushing and other processes, and the measured thermal conductivity is 75W/(m·K).

Example 19

A double-sided fluff thermal conductive blanket for electronic packaging thermal interface material, the foil material is different from the metal fluff material, the metal foil material is 304 stainless steel, the metal fluff material is red copper, the thickness of the 304 stainless steel foil is 0.08mm, and the single-sided copper metal fluff is The height of the metal fluff is 1mm, the diameter of the copper fibers that make up the metal fluff is 0.02mm, and the plastic yield strength is 90MPa. The flocking through hole with a diameter of 1.5mm is punched by a laser drilling machine, and the distance between the center lines of the two adjacent holes is 2.5mm. The carpet weaving gun inserts the pile yarn into the flocking through hole, cuts the pile loop, and then goes through the processes of shearing and brushing to obtain a double-sided pile thermal conductive blanket. The measured thermal conductivity is 47W/(m·K).

To sum up the above 19 embodiments, the summary is as follows: the thermal conductivity of the double-sided fleece thermal conductive blanket used for electronic packaging thermal interface material according to the present invention is high, and the thermal conductivity of the red copper fiber thermal conductive blanket can reach 101W/(m·K) , pure aluminum can reach 63W/(m·K), even 316L stainless steel with low thermal conductivity can reach 5W/(m·K), which are higher than the thermal conductivity of thermal grease (0.4～4W/(m·K). )), the thermal conductivity advantage of the present invention is obvious. As shown in Example 15, the surface tinned copper wire will greatly reduce the thermal conductivity, but will improve the high temperature resistance and oxidation resistance. When selecting metal fibers for processing metal fluff, the yield strength of fibers of the same material has a great relationship with its processing state and heat treatment state. Under the premise that the yield strength is greater than half of the critical buckling stress, try to use a lower yield strength. For fibers with a large height-diameter ratio, the critical buckling stress is very small, generally less than the yield stress of the material. At this time, fibers with a smaller yield stress can be selected, which can reduce the installation pressure.

It should be understood by those skilled in the art that the embodiments of the present invention shown in the above description and the accompanying drawings are only examples and do not limit the present invention. The objects of the present invention have been fully and effectively achieved. The functional and structural principles of the present invention have been shown and described in the embodiments, and the embodiments of the present invention may be modified or modified in any way without departing from the principles.

Claims (10)

1. A double-sided pile heat-conductive blanket for an electronic packaging thermal interface material, wherein the double-sided pile heat-conductive blanket for an electronic packaging thermal interface material comprises:

a layer of base cloth, wherein the base cloth is made of metal fibers, and the thickness of the base cloth is 0.05-1.6 mm; and

the shrunken metal fluff is arranged on the upper surface and the lower surface of the base fabric respectively, wherein the height of the metal fluff relative to one side of the base fabric is 0.1-1.0 mm, the diameter of the metal fluff is 0.005-0.1 mm, and the yield strength of the metal fluff is more than half of the theoretical critical destabilizing stress.

2. The double-sided pile heat conductive blanket for an electronic packaging thermal interface material of claim 1, wherein the base fabric cross-section metal fibers number more than 5.

3. The double-sided plush heat conduction blanket for the electronic packaging thermal interface material as claimed in claim 1, wherein the base fabric is a woven metal fabric formed by weaving using metal yarns, and the thickness of the woven metal fabric is 0.2-1.2 mm.

4. The double-sided pile thermal blanket for an electronic packaging thermal interface material of claim 1, wherein said base fabric is a non-woven metal fabric formed by non-weaving with metal fibers.

5. The double-sided pile thermal blanket for an electronic package thermal interface material of claim 1, wherein the cross-sectional coverage of the metal pile is greater than 20%.

6. The double-sided pile heat conductive blanket for an electronic packaging thermal interface material of claim 1, wherein the material of the metal base fabric and the metal pile is selected from one or a combination of two or more of pure copper, pure aluminum, pure magnesium, pure iron, copper alloy, aluminum alloy, magnesium alloy, and steel alloy.

7. A double sided pile heat blanket for an electronic packaging thermal interface material, wherein the double sided pile heat blanket for an electronic packaging thermal interface material comprises:

a layer of base cloth, wherein the base cloth is made of metal foil, wherein the thickness of the metal foil is 0.01-0.08 mm, and the metal foil is provided with a plurality of flocking through holes; and

the shrunken metal fluff is arranged on the upper surface and the lower surface of the base fabric respectively, the height of the metal fluff relative to one side of the base fabric is 0.1-1.0 mm, the diameter of the metal fluff is 0.005-0.1 mm, the metal fluff penetrates through the flocking through holes to form the metal fluff on the upper surface and the lower surface of the base fabric, and the yield strength of the metal fluff is more than half of the theoretical critical destabilizing pressure stress.

8. The double-sided pile heat conductive blanket for an electronic packaging thermal interface material of claim 7, wherein the hole diameter of the flocked through holes is 0.5-2 mm, and the distance between the centers of two adjacent flocked through holes is 1.5-2 times the hole diameter.

9. The double-sided pile heat conductive blanket for electronic packaging thermal interface material of claim 7 or 8, wherein the material of the metal base fabric and the metal pile is selected from one or a combination of two or more of pure copper, pure aluminum, pure magnesium, pure iron, copper alloy, aluminum alloy, magnesium alloy and steel alloy.

10. The double-sided pile thermal blanket for an electronic package thermal interface material of claim 7, wherein the cross-sectional coverage of the metal pile is greater than 20%.

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