An ultra-thin vapor chamber and a packaging and fixing method thereof

Abstract

This invention provides a thin vapor chamber and its encapsulation and fixing method. The ultra-thin vapor chamber includes a stacked condenser plate and an evaporator plate; a concave cavity is provided on the side of the condenser plate near the evaporator plate, and a capillary core plate and a vapor channel are provided in the concave cavity, with the upper and lower surfaces of the capillary core plate being independently and tightly connected to the lower surface of the concave cavity and the upper surface of the evaporator plate, respectively; thermally conductive adhesive is provided on the outer periphery of the condenser plate and the evaporator plate. This invention, based on LIPO technology adhesive bonding, encapsulates VC vapor chambers with advantages over traditional welding methods, including low temperature, high reliability, reworkability, low stress, and low cost. It provides a comprehensive solution that replaces traditional welding methods and is not limited to substrate selection, allowing for no restrictions on VC material (e.g., copper, aluminum, stainless steel, and other metal heat dissipation materials) and size. This invention is more suitable for fields such as temperature-sensitive, high-reliability, and cost-controlled VC vapor chamber encapsulation and manufacturing.

Description

Technical Field

[0001] This invention belongs to the field of heat dissipation technology for electronic devices, and relates to an ultra-thin heat spreader, specifically an ultra-thin heat spreader and its packaging and fixing method. Background Technology

[0002] Ultrathin vapor chambers (VCs) are core components of thermal management systems for portable electronic devices such as mobile phones. Their efficient two-dimensional heat dissipation and heat dissipation capabilities make them a key technology for solving the problem of concentrated heat generation in high-power chips (such as processors and RF modules), directly impacting device stability and lifespan. In existing mobile phone heat dissipation modules, the thickness of ultrathin vapor chambers is typically controlled within 0.4~0.7mm. The core structure consists of a copper shell, microcapillary structures (sintered or mesh type), and a working fluid. Heat is rapidly conducted and diffused through the phase change cycle of the working fluid. To ensure heat dissipation efficiency, the ultrathin vapor chamber must form a tight connection with the phone's metal support structure (such as the mid-frame or back panel) or heat diffuser sheet, requiring a gapless interface and good thermal continuity. Currently, the industry commonly uses laser welding or high-temperature soldering as the mainstream connection methods. High-temperature fusion fixes the edge of the vapor chamber shell to the metal components, achieving effective heat conduction path continuity.

[0003] However, the aforementioned traditional connection methods suffer from numerous insurmountable technical defects in practical applications, severely restricting the optimized application of ultra-thin heat spreaders in mobile phone thermal management systems. Firstly, the welding process faces significant thermal stress issues. Laser welding or high-temperature soldering both operate at temperatures exceeding 200°C, and the working fluid encapsulated within the ultra-thin heat spreader is prone to vaporization and expansion at high temperatures, leading to shell deformation or even sealing failure. Simultaneously, the ultra-thin copper shell itself has low rigidity, making it highly susceptible to micro-cracks or encapsulation structure damage under high temperatures, directly affecting the heat dissipation performance and lifespan of the heat spreader. Secondly, process yield is difficult to guarantee. Laser welding requires high-precision positioning fixtures and a dedicated protective gas environment, resulting in high process complexity and cost. Welding residues or oxide layers generated during high-temperature reflow can contaminate component surfaces, affecting not only the compatibility of subsequent mobile phone assembly but also... Firstly, it reduces the product qualification rate. Secondly, if defects occur in the welded products, rework is extremely difficult, further increasing production costs. Thirdly, thickness control faces bottlenecks. The solder layer and supporting protective structure required for welding will increase the overall thickness of the heat dissipation module by 50~80μm, which contradicts the current design trend of the mobile phone industry to pursue ultra-thinness and high integration, limiting the room for upgrading the device in terms of appearance and portability. Finally, the reliability of the thermal interface is insufficient. During long-term use, mobile phones will experience frequent temperature cycles. The solder joints are prone to fatigue cracking under the repeated action of thermal expansion and contraction, resulting in increased interface contact resistance, continuous decline in thermal conductivity, and ultimately affecting the long-term heat dissipation stability of the device.

[0004] The shortcomings of the existing technology have made the connection method between the ultra-thin heat spreader and the metal support structure a bottleneck in the optimization of mobile phone thermal management systems. It cannot meet the design requirements of ultra-thin and highly integrated devices, and also suffers from poor structural reliability and high manufacturing costs. There is an urgent need to develop a new connection technology to solve key problems such as structural deformation and failure caused by excessive welding temperature, high process complexity, thickness redundancy and insufficient interface thermal stability, thereby promoting the development of mobile phone thermal management systems towards a more efficient, reliable and thinner direction. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide an ultrathin vapor chamber plate and its encapsulation and fixing method. This invention replaces welding with a method of fixing the ultrathin vapor chamber plate using low-pressure overmolding (LIPO) adhesive coating, solving the problems of structural deformation and failure caused by high welding temperatures, reducing process complexity and cost, and improving interface thermal stability and mechanical reliability.

[0006] To achieve this objective, the present invention adopts the following technical solution: This invention provides an ultrathin heat spreader, which includes a stacked condenser plate and an evaporator plate; The condenser plate has a concave cavity on the side near the evaporator plate. A capillary core plate and a steam channel are provided in the concave cavity, and the upper and lower surfaces of the capillary core plate are independently and tightly connected to the lower surface of the condenser plate and the upper surface of the evaporator plate, respectively. Thermally conductive adhesive is provided on the outer periphery of the condenser plate and the evaporator plate.

[0007] The ultrathin heat spreader provided by this invention uses thermally conductive adhesive to encapsulate and fix the condenser plate and the evaporator plate, which can further improve the interfacial thermal stability and mechanical reliability of the heat spreader, and the process is simple and low cost.

[0008] Preferably, the material of the condenser plate includes copper or a copper-based alloy.

[0009] Preferably, the evaporation plate is made of any one of copper alloy, aluminum alloy, or stainless steel.

[0010] Preferably, the shear strength of the adhesive used to bond the condenser plate and the evaporator plate is ≥20MPa, for example, it can be 20MPa, 21MPa, 22MPa, 23MPa, 24MPa or 25MPa, etc., but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0011] By controlling the shear strength of the thermally conductive adhesive, this invention further ensures the adhesion between the condenser plate and the evaporator plate, thereby improving the service life of the ultra-thin heat spreader plate.

[0012] As a preferred embodiment of the present invention, the thickness of the condenser plate is 0.25~0.4mm, for example, it can be 0.25mm, 0.28mm, 0.31mm, 0.34mm, 0.37mm or 0.4mm, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0013] Preferably, the depth of the concave cavity is 0.2~0.3mm, for example, it can be 0.2mm, 0.22mm, 0.24mm, 0.26mm, 0.28mm or 0.3mm, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0014] Preferably, the thickness of the capillary core plate is 0.1~0.2mm, for example, it can be 0.1mm, 0.12mm, 0.14mm, 0.16mm, 0.18mm or 0.2mm, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0015] Preferably, the thickness of the evaporation plate is 0.2~0.4mm, for example, it can be 0.2mm, 0.24mm, 0.28mm, 0.32mm, 0.36mm or 0.4mm, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0016] Preferably, the thermally conductive adhesive comprises epoxy UV adhesive.

[0017] Preferably, the thermal conductivity of the thermally conductive adhesive is ≥3W / mK, for example, it can be 3W / mK, 3.1W / mK, 3.2W / mK, 3.3W / mK, 3.4W / mK or 3.5W / mK, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0018] In this invention, the thermal conductivity of the thermally conductive adhesive used in the encapsulation and curing process is not less than 3 W / mK to meet heat dissipation requirements. Furthermore, the viscosity of the epoxy UV adhesive is 25000 mPa·s at 25°C.

[0019] Preferably, the thickness of the thermally conductive adhesive is 0.7~1mm, for example, it can be 0.7mm, 0.8mm, 0.9mm or 1mm, but it is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0020] Preferably, the thickness of the thermally conductive adhesive is greater than or equal to the total thickness of the condenser plate and the evaporator plate.

[0021] More specifically, the thickness of the thermally conductive adhesive described in this invention is greater than or equal to the total thickness of the heat spreader after assembly, so as to achieve complete sealing of the heat spreader.

[0022] In this invention, the outer periphery of the condenser plate and the evaporator plate is provided with thermally conductive adhesive of uniform thickness to ensure consistent thermal resistance.

[0023] Secondly, the present invention provides a method for encapsulating and fixing an ultrathin heat spreader as described in the first aspect, the method comprising the following steps: (1) Plasma surface treatment is performed on the bonding surfaces of the condenser plate and the evaporator plate, and then the condenser plate, the fine core plate and the evaporator plate are assembled and pressed to obtain the blank; (2) The blank obtained in step (1) is fixed by a glue-filling fixture, and then glue-filling and curing are performed. The ultra-thin heat spreader is then demolded to complete the encapsulation and fixation of the heat spreader.

[0024] The encapsulation and fixing method provided by this invention does not require high-temperature welding, thus avoiding leakage and deformation of the VC board; this invention uses potting to achieve the encapsulation of the ultra-thin heat spreader, and the encapsulation and fixing method is simple in process and easy to repair; and can further improve the heat dissipation performance of the ultra-thin heat spreader. Furthermore, the glue-pouring process in step (2) specifically includes: fixing the blank with a glue-pouring fixture, pouring glue while it is clamped, inserting a glue plug and then curing it, and finally removing the glue plug for demolding.

[0025] Furthermore, the glue-pouring fixture in step (2) includes a bonding fixture and a silicone mold; the bonding fixture is used to fix the heat spreader; and the silicone mold is used for glue molding.

[0026] Preferably, the dispensing rate of the dispensing process in step (2) is 4.5~5.5μL / s, for example, it can be 4.5μL / s, 4.7μL / s, 4.9μL / s, 5.1μL / s, 5.3μL / s or 5.5μL / s, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0027] As a preferred technical solution of the present invention, the power of the plasma surface treatment in step (1) is 750~850W, for example, it can be 750W, 770W, 790W, 810W, 830W or 850W, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0028] Preferably, the plasma surface treatment time in step (1) is 60~90s, for example, it can be 60s, 65s, 70s, 75s, 80s, 85s or 90s, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0029] Preferably, the surface energy of the bonding surfaces of the condenser plate and the evaporator plate after plasma surface treatment is ≥32dyn / cm, for example, it can be 32dyn / cm, 32.2dyn / cm, 32.4dyn / cm, 32.6dyn / cm, 32.8dyn / cm or 33dyn / cm, etc., but is not limited to the listed values. Other values ​​not listed within the value range are also applicable.

[0030] As a preferred technical solution of the present invention, the pressure of the pressing process in step (1) is 0.45~0.55MPa, for example, it can be 0.45MPa, 0.47MPa, 0.49MPa, 0.51MPa, 0.53MPa or 0.55MPa, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0031] Preferably, the holding time of the pressing process in step (1) is 20~40s, for example, it can be 20s, 24s, 28s, 32s, 36s or 40s, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0032] As a preferred technical solution of the present invention, the curing process in step (2) includes UV curing.

[0033] Preferably, the wavelength of the ultraviolet light used for UV curing is 460~480nm, for example, it can be 460nm, 464nm, 468nm, 472nm, 476nm or 480nm, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable, with 470nm being the preferred value.

[0034] Preferably, the UV energy for UV curing is 750~850 mJ / cm. 2 For example, it could be 750mJ / cm 2 770mJ / cm 2 790mJ / cm 2 810mJ / cm 2 830mJ / cm 2 Or 850mJ / cm 2 This applies to, but is not limited to, the listed values; other unlisted values ​​within the range are also applicable.

[0035] Preferably, the UV curing time is 100~160s, for example, it can be 100s, 110s, 120s, 130s, 140s, 150s or 160s, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0036] As a preferred embodiment of the present invention, the encapsulation and fixing method of the ultrathin heat spreader plate according to the second aspect of the present invention includes the following steps: (1) Plasma surface treatment is performed on the bonding surfaces of the condenser plate and the evaporator plate, and then the condenser plate, the fine core plate and the evaporator plate are assembled and pressed to obtain the blank; The plasma surface treatment has a power of 750~850W and a time of 60~90s; after the plasma surface treatment, the surface energy of the bonding surfaces of the condenser plate and the evaporator plate is ≥32dyn / cm. The pressure for the pressing process is 0.45~0.55MPa, and the holding time is 20~40s; (2) The blank obtained in step (1) is fixed by a glue-potting fixture, and then glue-potting and UV curing are performed. The ultra-thin heat spreader is then demolded to complete the encapsulation and fixation of the heat spreader. The dispensing rate for the dispensing process is 4.5~5.5 μL / s; The wavelength of the ultraviolet light used for UV curing is 470 nm, and the UV energy is 750~850 mJ / cm. 2 The duration is 100~160s.

[0037] In this invention, the repair method for the ultra-thin heat spreader is simple. The repair method includes: softening the thermally conductive adhesive with a hot air gun, then mechanically peeling it off, wiping it with alcohol, and then re-potting and UV curing to achieve repair.

[0038] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0039] Compared with the prior art, the present invention has the following beneficial effects: (1) The packaging and fixing method provided by the present invention has low process risk: The packaging and fixing method provided by the present invention does not require high temperature welding, thus avoiding the risk of leakage and deformation of VC board; (2) The packaging and fixing method provided by the present invention has a simple process, low cost, and reduces the difficulty of rework; (3) The ultrathin heat dissipation plate provided by the present invention has low interfacial thermal resistance and stable thermal conductivity, which further improves the heat dissipation performance. (4) The ultra-thin heat spreader provided by the present invention has strong reliability and can withstand 500 heat cycles (-40~85°C) without cracking; and can withstand 168 hours in a high temperature and high humidity (85°C / 85%) environment without cracking. Attached Figure Description

[0040] Figure 1This is a schematic diagram of the structure of the ultrathin heat spreader provided in Embodiment 1 of the present invention; Figure 2 This is a top view of the ultrathin heat spreader provided in Embodiment 1 of the present invention; Figure 3 The locations of the dispensing port and injection port in the glue-filling process provided in Embodiment 1 of the present invention; Among them, 1 is the condenser plate, 2 is the capillary core plate, 3 is the evaporator plate, and 4 is the thermally conductive adhesive. Detailed Implementation

[0041] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0042] The thermally conductive adhesives used in the following examples and comparative examples are all commercially available epoxy UV adhesives manufactured by Welton Technology Co., Ltd.

[0043] Example 1 This embodiment provides an ultrathin heat spreader, such as Figure 1 and Figure 2 As shown, the ultrathin heat spreader includes a condenser plate 1 and an evaporator plate 3 stacked together; The condenser plate 1 has a concave cavity on the side near the evaporator plate 3. The concave cavity contains a capillary core plate 2 and a steam channel. The upper and lower surfaces of the capillary core plate 2 are respectively and independently and tightly connected to the lower surface of the condenser plate and the upper surface of the evaporator plate 3. Thermally conductive adhesive 4 is provided on the outer periphery of the condenser plate 1 and the evaporator plate 3; The condenser plate 1 is made of pure copper C1100; the evaporator plate is made of pure copper C1100; the shear strength of the thermally conductive adhesive used to bond the condenser plate and the evaporator plate is 23~25MPa. The thickness of the condenser plate 1 is 0.3 mm; the depth of the concave cavity is 0.2 mm; the thickness of the capillary core plate 2 is 0.15 mm; and the thickness of the evaporator plate 3 is 0.3 mm.

[0044] The thermally conductive adhesive 4 is an epoxy UV adhesive; the thermal conductivity of the thermally conductive adhesive is 3.2 W / mK; the thickness of the thermally conductive adhesive is 0.7 mm.

[0045] This embodiment also provides a method for encapsulating and fixing the ultrathin heat spreader as described above, the method comprising the following steps: (1) Plasma surface treatment is performed on the bonding surfaces of the condenser plate and the evaporator plate, and then the condenser plate, the fine core plate and the evaporator plate are assembled and pressed to obtain the blank; The plasma surface treatment has a power of 800W and a time of 60s; after the plasma surface treatment, the surface energy of the bonding surfaces of the condenser plate and the evaporator plate is approximately 32~36dyn / cm. The pressure for the pressing process is 0.5 MPa, and the holding time is 30 seconds. (2) The blank obtained in step (1) is fixed with a glue-filling fixture, and then glue-filling treatment is performed (e.g. Figure 3 (As shown) and UV curing, demolding completes the encapsulation and fixation of the ultrathin heat spreader plate; The dispensing rate for the dispensing process is 5 μL / s; The wavelength of the ultraviolet light used for UV curing is 470 nm, and the UV energy is 800 mJ / cm². 2 The time is 120 seconds.

[0046] The heat spreader provided in this embodiment has a thermal resistance of 0.32 K / W when the heat load reaches 10W, and the maximum temperature difference (ΔT) on the surface of the heat spreader is 3.2°C. The sample was subjected to an environment of 85°C / 85% relative humidity for 168 hours without delamination or cracking. The thermal shock test (-40°C to 85°C) was performed for 500 cycles, and the adhesive layer showed no delamination or cracking, and the thermal resistance change rate was <2%.

[0047] Example 2 This embodiment provides an ultrathin heat spreader, such as Figure 1 and Figure 2 As shown, the ultrathin heat spreader includes a condenser plate 1 and an evaporator plate 3 stacked together; The condenser plate 1 has a concave cavity on the side near the evaporator plate 3. The concave cavity contains a capillary core plate 2 and a steam channel. The upper and lower surfaces of the capillary core plate 2 are respectively and independently and tightly connected to the lower surface of the condenser plate and the upper surface of the evaporator plate 3. Thermally conductive adhesive 4 is provided on the outer periphery of the condenser plate 1 and the evaporator plate 3; The condenser plate 1 is made of pure copper C1100; the evaporator plate is made of aluminum alloy 6061; the shear strength of the thermally conductive adhesive used to bond the condenser plate and the evaporator plate is 22~23MPa. The thickness of the condenser plate 1 is 0.25 mm; the depth of the concave cavity is 0.2 mm; the thickness of the capillary core plate 2 is 0.1 mm; and the thickness of the evaporator plate 3 is 0.4 mm.

[0048] The thermally conductive adhesive 4 includes epoxy UV adhesive; the thermal conductivity of the thermally conductive adhesive is 3.2 W / mK; the thickness of the thermally conductive adhesive is 0.8 mm.

[0049] This embodiment also provides a method for encapsulating and fixing the ultrathin heat spreader as described above, the method comprising the following steps: (1) Plasma surface treatment is performed on the bonding surfaces of the condenser plate and the evaporator plate, and then the condenser plate, the fine core plate and the evaporator plate are assembled and pressed to obtain the blank; The plasma surface treatment has a power of 750W and a time of 90s; after the plasma surface treatment, the surface energy of the bonding surfaces of the condenser plate and the evaporator plate is approximately 32~36dyn / cm. The pressure for the pressing process is 0.45 MPa, and the holding time is 40 seconds. (2) The blank obtained in step (1) is fixed by a glue-potting fixture, and then glue-potting and UV curing are performed. The ultra-thin heat spreader is then demolded to complete the encapsulation and fixation of the heat spreader. The dispensing rate for the dispensing treatment is 4.5 μL / s; The wavelength of the ultraviolet light used for UV curing is 480nm, and the UV energy is 850mJ / cm. 2 The time is 130 seconds.

[0050] The heat spreader provided in this embodiment has a thermal resistance of 0.48 K / W when the heat load reaches 10W, and the maximum temperature difference (ΔT) on the surface of the heat spreader is 4.8°C. The sample was tested for 168 hours in an environment of 85°C / 85% relative humidity without any delamination or cracking of the adhesive layer. The thermal shock test (-40°C to 85°C) was performed for 500 cycles, and the adhesive layer showed no delamination or cracking, and the thermal resistance change rate was <3%.

[0051] Example 3 This embodiment provides an ultrathin heat spreader, such as Figure 1 and Figure 2 As shown, the ultrathin heat spreader includes a condenser plate 1 and an evaporator plate 3 stacked together; The condenser plate 1 has a concave cavity on the side near the evaporator plate 3. The concave cavity contains a capillary core plate 2 and a steam channel. The upper and lower surfaces of the capillary core plate 2 are respectively and independently and tightly connected to the lower surface of the condenser plate and the upper surface of the evaporator plate 3. Thermally conductive adhesive 4 is provided on the outer periphery of the condenser plate 1 and the evaporator plate 3; The condenser plate 1 is made of pure copper C1100; the evaporator plate is made of stainless steel 316; the shear strength of the thermally conductive adhesive used to bond the condenser plate and the evaporator plate is 20~21MPa. The thickness of the condenser plate 1 is 0.4 mm; the depth of the concave cavity is 0.3 mm; the thickness of the capillary core plate 2 is 0.2 mm; and the thickness of the evaporator plate 3 is 0.4 mm.

[0052] The thermally conductive adhesive 4 includes epoxy UV adhesive; the thermal conductivity of the thermally conductive adhesive is 3.2 W / mK; the thickness of the thermally conductive adhesive is 1 mm.

[0053] This embodiment also provides a method for encapsulating and fixing the ultrathin heat spreader as described above, the method comprising the following steps: (1) Plasma surface treatment is performed on the bonding surfaces of the condenser plate and the evaporator plate, and then the condenser plate, the fine core plate and the evaporator plate are assembled and pressed to obtain the blank; The plasma surface treatment has a power of 850W and a time of 890s; after the plasma surface treatment, the surface energy of the bonding surfaces of the condenser plate and the evaporator plate is approximately 32~36dyn / cm. The pressure for the pressing process is 0.55 MPa, and the holding time is 20 seconds. (2) The blank obtained in step (1) is fixed by a glue-potting fixture, and then glue-potting and UV curing are performed. The ultra-thin heat spreader is then demolded to complete the encapsulation and fixation of the heat spreader. The dispensing rate for the dispensing process is 5.5 μL / s; The wavelength of the ultraviolet light used for UV curing is 460nm, and the UV energy is 750mJ / cm. 2 The time is 160 seconds.

[0054] The heat spreader provided in this embodiment has a thermal resistance of 0.52 K / W when the heat load reaches 10 W, and the maximum temperature difference (ΔT) on the surface of the heat spreader is 5.2°C. The sample was subjected to an environment of 85°C / 85% relative humidity for 168 hours without any delamination or cracking of the adhesive layer. The thermal shock test (-40°C to 85°C) was performed for 500 cycles without any delamination or cracking of the adhesive layer, and the thermal resistance change rate was <3%.

[0055] Example 4 This embodiment describes an ultra-thin heat spreader, the structure of which is the same as in Embodiment 1.

[0056] This embodiment also provides a method for encapsulating and fixing an ultrathin heat spreader as described above. The only difference between this encapsulation and fixing method and that of Embodiment 1 is: In this embodiment, the plasma surface treatment described in step (1) is omitted, and the surface energy of the bonding surfaces of the condenser plate and the evaporator plate is 30 dyn / cm.

[0057] Example 5 This embodiment describes an ultra-thin heat spreader, the structure of which is the same as in Embodiment 1.

[0058] This embodiment also provides a method for encapsulating and fixing an ultrathin heat spreader as described above. The only difference between this encapsulation and fixing method and that of Embodiment 1 is: In this embodiment, the power of the plasma surface treatment in step (1) is adjusted to 600W, and the surface energy of the bonding surfaces of the condenser plate and the evaporator plate after the plasma surface treatment is 31dyn / cm.

[0059] Compared with Example 1, omitting plasma surface treatment or reducing the power of plasma surface treatment will reduce the surface energy of the bonding surface of the condenser plate and the evaporator plate, thereby reducing the adhesion between the product surface and the thermally conductive adhesive, which will make the adhesive layer susceptible to delamination and cracking.

[0060] Example 6 This embodiment describes an ultra-thin heat spreader, the structure of which is the same as in Embodiment 1.

[0061] This embodiment also provides a method for encapsulating and fixing an ultrathin heat spreader as described above. The only difference between this encapsulation and fixing method and that of Embodiment 1 is: In this embodiment, the wavelength of the ultraviolet light used for UV curing in step (2) is adjusted to 450nm.

[0062] In this embodiment, the shear strength of the thermally conductive adhesive used to bond the condenser plate and the evaporator plate is 19 MPa.

[0063] Example 7 This embodiment describes an ultra-thin heat spreader, the structure of which is the same as in Embodiment 1.

[0064] This embodiment also provides a method for encapsulating and fixing an ultrathin heat spreader as described above. The only difference between this encapsulation and fixing method and that of Embodiment 1 is: In this embodiment, the UV energy for UV curing in step (2) is adjusted to 700 mJ / cm. 2 .

[0065] In this embodiment, the shear strength of the thermally conductive adhesive used to bond the condenser plate and the evaporator plate is 19 MPa.

[0066] Example 8 This embodiment describes an ultra-thin heat spreader, the structure of which is the same as in Embodiment 1.

[0067] This embodiment also provides a method for encapsulating and fixing an ultrathin heat spreader as described above. The only difference between this encapsulation and fixing method and that of Embodiment 1 is: In this embodiment, the UV energy for UV curing in step (2) is adjusted to 900 mJ / cm. 2 .

[0068] In this embodiment, the shear strength of the thermally conductive adhesive used to bond the condenser plate and the evaporator plate is 7 MPa.

[0069] Compared with Example 1, in the encapsulation and fixing method provided in Example 6, the wavelength of the ultraviolet light used in the UV curing process is too low, which will result in the following: when epoxy UV adhesive is used, reducing the ultraviolet light wavelength will prevent the adhesive from curing, thus preventing the curing and encapsulation of the heat spreader. In the encapsulation and fixing methods provided in Examples 7-8, if the UV energy is too low during the UV curing process, the adhesive will not cure completely; if it is too high, the adhesive will over-cur.

[0070] Comparative Example 1 This comparative example provides an ultrathin heat spreader, the only difference between the structure of the ultrathin heat spreader and that of Example 1 is: This comparative example omits the thermally conductive adhesive disposed on the outer periphery of the condenser plate 1 and the evaporator plate 3.

[0071] This comparative example also provides a method for encapsulating and fixing an ultrathin heat spreader as described above. The only difference between this encapsulation and fixing method and that of Example 1 is: This comparative example adjusts step (2) to laser welding, with a welding temperature of 250°C.

[0072] Comparative Example 2 This comparative example provides an ultrathin heat spreader, the only difference between the structure of the ultrathin heat spreader and that of Example 1 is: This comparative example omits the thermally conductive adhesive disposed on the outer periphery of the condenser plate 1 and the evaporator plate 3.

[0073] This comparative example also provides a method for encapsulating and fixing an ultrathin heat spreader as described above. The only difference between this encapsulation and fixing method and that of Example 1 is: This comparative example adjusts step (2) to SAC305 soldering with a soldering temperature of 230°C.

[0074] Compared with Example 1, when the heat spreader is encapsulated using the welding method provided in Comparative Examples 1-2, the maximum stress inside the heat spreader can reach 180 MPa, which is much higher than that of the heat spreader provided in Example 1 (45 MPa); and the manufacturing cost is much higher than that of Example 1, making rework difficult.

[0075] In summary, the LIPO technology-based adhesive bonding method for encapsulating VC heat sinks offers advantages over traditional welding methods, including low temperature, high reliability, reworkability, low stress, and low cost. It provides a comprehensive solution that replaces traditional welding methods and is not limited to substrate selection; it allows for unlimited use of VC materials (e.g., copper, aluminum, stainless steel, and other metal heat dissipation materials) and size. This invention is particularly suitable for applications requiring temperature sensitivity, high reliability, and strict cost control in VC heat sink encapsulation and manufacturing.

[0076] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. An ultrathin heat spreader, characterized in that, The ultra-thin heat spreader includes a stacked condenser plate and an evaporator plate; The condenser plate has a concave cavity on the side near the evaporator plate. A capillary core plate and a steam channel are provided in the concave cavity. The upper and lower surfaces of the capillary core plate are independently and tightly connected to the lower surface of the condenser plate and the upper surface of the evaporator plate, respectively. Thermally conductive adhesive is provided on the outer periphery of the condenser plate and the evaporator plate.

2. The ultrathin heat spreader according to claim 1, characterized in that, The material of the condenser plate includes copper or copper-based alloy; Preferably, the evaporation plate is made of any one of copper alloy, aluminum alloy or stainless steel; Preferably, the shear strength of the thermally conductive adhesive used to bond the condenser plate and the evaporator plate is ≥20MPa.

3. The ultrathin heat spreader according to claim 1 or 2, characterized in that, The thickness of the condenser plate is 0.25~0.4mm; Preferably, the depth of the concave cavity is 0.2~0.3mm; Preferably, the thickness of the capillary core plate is 0.1~0.2mm. Preferably, the thickness of the evaporation plate is 0.2~0.4mm.

4. The ultrathin heat spreader according to any one of claims 1-3, characterized in that, The thermally conductive adhesive includes epoxy UV adhesive; Preferably, the thermal conductivity of the thermally conductive adhesive is ≥3W / mK.

5. The ultrathin heat spreader according to any one of claims 1-4, characterized in that, The thickness of the thermally conductive adhesive is 0.7~1mm; Preferably, the thickness of the thermally conductive adhesive is greater than or equal to the total thickness of the condenser plate and the evaporator plate.

6. A method for encapsulating and fixing an ultrathin heat spreader as described in any one of claims 1-5, characterized in that, The encapsulation and fixing method includes the following steps: (1) Plasma surface treatment is performed on the bonding surfaces of the condenser plate and the evaporator plate, and then the condenser plate, the fine core plate and the evaporator plate are assembled and pressed to obtain the blank; (2) The blank obtained in step (1) is fixed by a glue-filling fixture, and then glue-filling and curing are performed. The ultra-thin heat spreader is then demolded to complete the encapsulation and fixation of the heat spreader.

7. The encapsulation and fixing method according to claim 6, characterized in that, The power of the plasma surface treatment in step (1) is 750~850W; Preferably, the plasma surface treatment time in step (1) is 60~90s; Preferably, the surface energy of the bonding surfaces of the condenser plate and the evaporator plate after plasma surface treatment is ≥32dyn / cm.

8. The encapsulation and fixing method according to claim 6 or 7, characterized in that, The pressure for the pressing process in step (1) is 0.45~0.55MPa; Preferably, the holding time of the pressing process in step (1) is 20~40s.

9. The encapsulation and fixing method according to any one of claims 6-8, characterized in that, The dispensing rate of the dispensing process in step (2) is 4.5~5.5μL / s.

10. The encapsulation and fixing method according to any one of claims 6-9, characterized in that, The curing process in step (2) includes UV curing; Preferably, the wavelength of the ultraviolet light used for UV curing is 460~480nm, more preferably 470nm; Preferably, the UV energy for UV curing is 750~850 mJ / cm. 2 ; Preferably, the UV curing time is 100~160s.

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