Heat sink sheet and preparation method and application thereof

Abstract

The invention belongs to the technical field of high-power semiconductor lasers, and discloses a heat sink sheet and a preparation method and application thereof. According to the preparation method provided by the invention, the artificial diamond with very excellent heat-conducting property is used as a substrate material for preparing the heat sink sheet, and the small through holes with specific apertures and specific arrangement intervals are introduced into the artificial diamond; high-temperature reduction treatment, magnetron sputtering tungsten plating treatment, magnetron sputtering copper plating treatment, high-temperature calcination treatment and sectional type hole filling copper electroplating treatment are matched, and high-precision filling of copper on the artificial diamond is achieved through cooperation of all the treatment steps. The obtained diamond / copper composite material has excellent heat-conducting property, electrical conductivity and deformation resistance, the thermal expansion coefficient of the diamond / copper composite material is highly matched with common semiconductor materials such as GaAs, the problems of high-heat-flux heat dissipation and thermal stress failure existing in an existing high-power laser device are effectively solved, and the diamond / copper composite material has very excellent application prospects.

Description

Technical Field

[0001] This invention belongs to the technical field of high-power semiconductor lasers, and particularly relates to a heat sink, its preparation method, and its application. Background Technology

[0002] High-power semiconductor lasers are widely used in laser communication, laser printing, and medical instruments due to their advantages such as high photoelectric efficiency, convenient modulation, small size, and light weight. Among them, laser bars are a type of high-power semiconductor laser, which consists of multiple laser diodes linearly arranged and integrated. They are used for pumping, industrial processing, etc., and require efficient heat dissipation and beam shaping.

[0003] Currently, copper-tungsten alloys are the primary heat sink material for laser bars, but their thermal conductivity is typically less than 220 W / (m·K). As power increases, the heat generated in the active region increases significantly. This not only reduces the laser's output power and electro-optical conversion efficiency but may also shorten its lifespan and even lead to device failure, failing to adequately meet the high-power requirements of laser bars. Furthermore, the heat sink must match the coefficient of thermal expansion (CTE) of the chip. If the CTE is mismatched, thermal stress can cause micro-deformation of the chip, leading to laser beam deflection and affecting the beam quality and collimation of the semiconductor laser array.

[0004] Therefore, developing a heat sink for laser bars with excellent heat dissipation and good matching with the thermal expansion coefficient of the chip is of great significance for the development of high-power laser bars. Summary of the Invention

[0005] The primary objective of this invention is to address the problems of low thermal conductivity, poor compatibility with semiconductor chip materials, and low mechanical reliability of existing heat sink materials used in high-power semiconductor lasers, which lead to "high heat flux density heat dissipation" and "thermal stress failure," and to provide a method for preparing a heat sink sheet.

[0006] The second objective of this invention is to provide a heat sink sheet.

[0007] A third objective of this invention is to provide the application of the above-mentioned heat sink in the fabrication of high-power semiconductor lasers.

[0008] Specifically, the preparation method of the heat sink sheet provided by the present invention includes: S1, forming through holes with a diameter of 0.3 mm to 0.4 mm and a hole spacing of 0.5 mm to 0.6 mm on a sheet-like synthetic diamond, and then performing a high-temperature reduction treatment at a reducing atmosphere and 750°C to 800°C for 1 h to 3 h to obtain a vacuum reduced drilled diamond sheet; S2, taking the vacuum reduced drilled diamond sheet and performing magnetron sputtering tungsten plating treatment to form a metallic tungsten transition layer on the surface of the sheet-like synthetic diamond; S3, taking the vacuum reduced drilled diamond sheet after the magnetron sputtering tungsten plating treatment... A diamond sheet undergoes magnetron sputtering copper plating to form a copper seed layer on the surface of the tungsten transition layer. This is followed by high-temperature calcination, via-filling copper plating, and vacuum annealing to form a copper layer on the surface of the copper seed layer, filling the through-holes with copper, thus obtaining a diamond / copper composite material. S4: The diamond / copper composite material is then subjected to nickel and gold plating to form nickel and gold layers on its surface, resulting in the heat sink. In step S3, the via-filling copper plating includes: at a current density of 0.5 A / dm³. 2 ~2A / dm 2 The first stage of electroplating is carried out for 0.5h to 2h at a current density of 1A / dm². 2 ~3A / dm 2 The second electroplating process is then carried out for 1 to 3 hours.

[0009] Furthermore, in step S1, the thermal conductivity of the sheet-like synthetic diamond is not less than 1200 W / (m K), and the thickness is 0.1 mm to 2 mm.

[0010] Further, in step S1, the method for forming a through hole on the sheet-like synthetic diamond includes: taking the sheet-like synthetic diamond and performing laser drilling.

[0011] Furthermore, in step S1, the laser used in the laser drilling process is selected from an infrared picosecond laser and / or an ultraviolet picosecond laser.

[0012] Furthermore, in step S1, the power of the laser used in the laser drilling process is 20W to 70W.

[0013] Furthermore, in step S1, the reducing atmosphere of the high-temperature reduction treatment is hydrogen and / or methane.

[0014] Furthermore, in step S2, the vacuum degree of the magnetron sputtering tungsten deposition is no greater than 5 × 10⁻⁶. -4The working pressure is 0.3Pa~1Pa, the sputtering temperature is 100℃~500℃, the sputtering current is 0.5A~3A, the sputtering voltage is 300V~600V, the sputtering power is 100W~500W, and the time is 5min~20min.

[0015] Furthermore, in step S2, the thickness of the tungsten transition layer is 100 nm to 200 nm.

[0016] Furthermore, in step S3, the vacuum degree of the magnetron sputtering copper plating process is no greater than 5 × 10⁻⁶. -4 The working pressure is 0.3Pa~1Pa, the sputtering temperature is 100℃~500℃, the sputtering current is 0.5A~3A, the sputtering voltage is 300V~600V, the sputtering power is 100W~500W, and the time is 5min~20min.

[0017] Furthermore, in step S3, the thickness of the copper seed layer is 300 nm to 500 nm.

[0018] Furthermore, in step S3, the atmosphere of the high-temperature calcination treatment is an inert gas, the temperature is 700℃~800℃, and the time is 1h~4h.

[0019] Further, in step S3, the copper plating solution used in the hole-filling electroplating copper treatment includes: 50 g / L to 100 g / L copper sulfate, 50 g / L to 200 g / L sulfuric acid, 30 ppm to 100 ppm chloride ions, 0.5% (v / v) to 1% (v / v) leveling agent and 0.0005% (v / v) to 0.001% (v / v) brightener.

[0020] Furthermore, in step S3, the temperature of the copper plating process for filling holes is 20℃~30℃.

[0021] Furthermore, in step S3, the temperature of the vacuum annealing treatment is 200℃~300℃, and the time is 1h~3h.

[0022] Furthermore, step S3 includes a grinding and polishing process. After the grinding and polishing process, the copper layer thickness of the diamond / copper composite material is 10μm to 20μm, and the roughness Ra is not greater than 0.2μm.

[0023] Further, in step S4, the nickel plating solution used in the nickel plating process includes: 200 g / L to 300 g / L of nickel sulfate, 30 g / L to 60 g / L of nickel chloride, and 30 g / L to 45 g / L of boric acid, with a pH of 3.5 to 4.5.

[0024] Furthermore, in step S4, the electroplating nickel treatment temperature is 50℃~60℃, and the current density is 1A / dm³. 2 ~3A / dm 2 The time is 10 to 20 minutes.

[0025] Furthermore, in step S4, the thickness of the nickel layer is 3μm to 7μm.

[0026] Further, in step S4, the gold plating solution used in the gold plating process includes: 2 g / L to 10 g / L of potassium gold cyanide, 50 g / L to 100 g / L of potassium cyanide and 10 g / L to 30 g / L of conductive salt, with a pH of 10 to 12.

[0027] Furthermore, in step S4, the conductive salt is potassium carbonate.

[0028] Furthermore, in step S4, the temperature for the electroplating gold treatment is 40℃~70℃, and the current density is 0.1A / dm³. 2 ~1A / dm 2 The time is 5 to 20 minutes.

[0029] Furthermore, in step S4, the thickness of the gold layer is 1 μm to 2 μm.

[0030] The heat sink sheet provided by the present invention is prepared by the above-described method for preparing heat sink sheets.

[0031] Furthermore, the heat sink sheet has an electrical conductivity of not less than 60% IACS, a thermal conductivity of not less than 800 (mK), a bending strength of not less than 300MPa, and a coefficient of thermal expansion of 5.9ppm / K to 6.4ppm / K.

[0032] The present invention also provides the application of the above-mentioned heat sink in the fabrication of high-power semiconductor lasers.

[0033] Beneficial effects:

[0034] The preparation method provided by this invention uses synthetic diamond, which has excellent thermal conductivity, as the substrate material for heat sink preparation. By introducing through-holes with specific apertures and spacings into the synthetic diamond, and combining this with high-temperature reduction treatment, magnetron sputtering tungsten plating treatment, magnetron sputtering copper plating treatment, high-temperature calcination treatment, and segmented hole-filling electroplating copper treatment, the high-precision filling of copper into the synthetic diamond is achieved through the synergistic cooperation between the various processing steps. The resulting diamond / copper composite material has excellent thermal conductivity, electrical conductivity, and resistance to thermal expansion, and its coefficient of thermal expansion is 5.9ppm / K to 6.4ppm / K, which has a high degree of matching with common semiconductor materials such as GaAs. This effectively solves the problems of high heat flux density heat dissipation and thermal stress failure in existing high-power laser devices, and has excellent application prospects in high-power semiconductor lasers. Attached Figure Description

[0035] Figure 1 This is a schematic flowchart of the method for preparing the heat sink sheet provided in Example 1 of the present invention;

[0036] Figure 2 This is a physical image of the heat sink sheet provided in Embodiment 1 of the present invention;

[0037] Figure 3 This is a schematic cross-sectional view of the heat sink sheet provided in Embodiment 1 of the present invention. Detailed Implementation

[0038] Based on addressing the problems of unsatisfactory heat dissipation and mismatch between the thermal expansion coefficient and the chip in existing heat sink materials used in high-power laser devices, the inventors of this invention, through extensive and in-depth thinking and numerous experiments, discovered that by introducing through-holes into the artificial diamond as the substrate material for the heat sink, and by adjusting the diameter and spacing of the through-holes to control the volume fraction of the introduced metallic copper, the expansion coefficient of the diamond / copper composite material can be controlled. Furthermore, the diamond / copper composite material retains excellent thermal conductivity, thus effectively meeting the requirements for heat sink materials in high-power semiconductor lasers such as laser bars.

[0039] However, the inventors discovered through numerous experiments that copper and carbon have strong chemical inertness, making it difficult for them to directly bond with the diamond surface. Furthermore, the introduction of through-holes complicates the surface structure of synthetic diamonds, and conventional methods such as electroplating and chemical deposition cannot achieve high-precision filling of copper in the through-holes. Moreover, the resulting copper layer suffers from uneven thickness and structural defects. Even the introduction of metals such as tungsten and nickel as transition layers cannot effectively solve these problems. The heat sink material prepared has issues such as incomplete copper filling, uneven material surface and thickness, and poor mechanical reliability, resulting in a high product defect rate.

[0040] Therefore, the inventors conducted further in-depth research and numerous experiments, creatively discovering that setting the aperture of the through-holes in synthetic diamond to 0.3mm–0.4mm and the spacing between holes to 0.5mm–0.6mm, and subjecting them to high-temperature reduction treatment at 750℃–800℃ in a reducing atmosphere before the formation of other metal layers, can effectively improve the condition of the surface of the synthetic diamond, the inner wall of the through-holes, and the connecting bends, and introduce a tungsten transition layer. Simultaneously, a progressive copper layer formation method is employed—first, a copper seed layer is formed using magnetron sputtering and then subjected to high-temperature calcination, followed by segmented through-hole electroplating and vacuum annealing—to achieve high-precision filling of copper within the through-holes. This results in full copper filling within the through-holes, with a uniform copper layer thickness and a smooth surface on the diamond surface. The resulting diamond / copper composite material possesses excellent thermal conductivity, electrical conductivity, and resistance to deformation, and its coefficient of thermal expansion is highly compatible with common semiconductor materials such as GaAs, making it well-suited for use as a heat sink material in high-power semiconductor lasers. Based on this, the technical solution of the present invention is obtained.

[0041] In this invention, the preparation method of the heat sink sheet specifically includes: S1, forming through holes on a sheet-like synthetic diamond and then performing high-temperature reduction treatment in a reducing atmosphere to obtain a vacuum-reduced drilled diamond sheet; S2, taking the vacuum-reduced drilled diamond sheet and performing magnetron sputtering tungsten plating treatment to form a metallic tungsten transition layer on the surface of the sheet-like synthetic diamond; S3, taking the vacuum-reduced drilled diamond sheet that has undergone the magnetron sputtering tungsten plating treatment and performing magnetron sputtering copper plating treatment to form a metallic copper seed layer on the surface of the metallic tungsten transition layer, and then sequentially performing high-temperature calcination treatment, hole-filling electroplating copper treatment, and vacuum annealing treatment to form a copper layer on the surface of the metallic copper seed layer and fill the through holes with copper to obtain a diamond / copper composite material; S4, taking the diamond / copper composite material and performing nickel plating treatment and gold plating treatment to form a nickel layer and a gold layer on the surface of the diamond / copper composite material to obtain the heat sink sheet.

[0042] In this invention, the diameter of the through-hole is specifically 0.3mm to 0.4mm, such as 0.3mm, 0.31mm, 0.32mm, 0.335mm, 0.34mm, 0.35mm, 0.37mm, 0.39mm, 0.4mm, or any value between them; the hole spacing is specifically 0.5mm to 0.6mm, such as 0.5mm, 0.505mm, 0.51mm, 0.53mm, 0.54mm, 0.55mm, 0.56mm, 0.58mm, 0.6mm, or any value between them. The hole spacing is defined as the straight-line distance between the centers of two adjacent through-holes.

[0043] In this invention, the method of forming a through hole on the sheet-like synthetic diamond is a conventional technique used in the prior art. Those skilled in the art can make an adaptive selection from existing hole-opening techniques according to actual needs, and this invention does not impose any particular limitations on it.

[0044] In some specific embodiments, the method for drilling a small hole through the sheet-like synthetic diamond preferably includes: performing laser drilling on the sheet-like synthetic diamond. More specifically, specific examples of the laser used in the laser drilling process include, but are not limited to, infrared picosecond lasers and / or ultraviolet picosecond lasers; the power of the laser used in the laser drilling process is preferably 20W to 70W, such as 20W, 25W, 30W, 40W, 45W, 50W, 60W, 70W or any value between them.

[0045] In this invention, the thermal conductivity of the sheet-like synthetic diamond is preferably not less than 1200 W / (m K), more preferably 1200 W / (m K) to 2200 W / (m K), such as 1200 W / (m K), 1250 W / (m K), 1300 W / (m K), 1400 W / (m K), 1500 W / (m K), 1800 W / (m K), 2000 W / (m K), 2100 W / (m K), 2200 W / (m K) or any value between them.

[0046] In this invention, the thickness of the sheet-like synthetic diamond is preferably 0.1mm to 2mm, such as 0.1mm, 0.2mm, 0.35mm, 0.4mm, 0.5mm, 0.7mm, 0.9mm, 1mm, 1.2mm, 1.4mm, 1.6mm, 1.8mm, 2mm, or any value between them. In this case, the through-hole has a more ideal aspect ratio, which is beneficial for achieving high-precision copper filling.

[0047] In this invention, in step S1, the reducing atmosphere refers to a gaseous environment with electron-donating or oxygen-removing capabilities, which includes at least a reducing gas. Specific examples of the reducing gas include, but are not limited to, hydrogen and / or methane.

[0048] In this invention, in step S1, the conditions for the high-temperature reduction treatment specifically include a temperature of 750℃ to 800℃, such as 750℃, 753℃, 755℃, 758℃, 760℃, 775℃, 780℃, 790℃, 800℃ or any value between them; and a time of 1h to 3h, such as 1h, 1.1h, 1.2h, 1.3h, 1.5h, 1.8h, 2h, 2.5h, 3h or any value between them.

[0049] In this invention, step S2, the magnetron sputtering tungsten plating treatment refers to the process of depositing tungsten on the surface of a vacuum reduced drilled diamond sheet using magnetron sputtering technology to form a metallic tungsten transition layer. Magnetron sputtering technology is a commonly used technique in the prior art, and those skilled in the art can make adaptive choices according to actual needs. This invention does not impose any particular limitations on it.

[0050] In some specific embodiments, in step S2, the conditions for the magnetron sputtering tungsten plating process include a vacuum degree preferably not greater than 6 × 10⁻⁶. -4 Pa, more preferably 1×10 Pa -6 Pa~6×10 -4 Pa, such as 1×10 -6 Pa, 2×10 -6 Pa, 1×10 -5 Pa, 8×10 -5 Pa, 6×10 -4 Pa or any value between them; the working gas pressure is preferably 0.3Pa to 1Pa, such as 0.3Pa, 0.35Pa, 0.4Pa, 0.45Pa, 0.5Pa, 0.6Pa, 0.75Pa, 0.8Pa, 0.9Pa, 1Pa or any value between them; the sputtering temperature is preferably 100℃ to 500℃, such as 100℃, 120℃, 140℃, 150℃, 180℃, 200℃, 250℃, 280℃, 300℃, 320℃, 360℃, 400℃, 450℃, 500℃ or any value between them; the sputtering current is preferably 0.5A to 3A, such as 0.5A, 0.8A, 0.9A, 1.2A, 1.5A, 2A, 2.5A. The sputtering voltage is preferably 300V to 600V, such as 300V, 310V, 350V, 400V, 420V, 480V, 500V, 550V, 600V, or any value between them; the sputtering power is preferably 100W to 500W, such as 100W, 120W, 150W, 180W, 200W, 250W, 300W, 400W, 500W, or any value between them; the sputtering time is preferably 5min to 20min, such as 5min, 5.5min, 6min, 7min, 8min, 10min, 12min, 14min, 16min, 18min, 20min, or any value between them.

[0051] In this invention, the thickness of the tungsten transition layer is preferably 100nm to 200nm, such as 100nm, 110nm, 120nm, 125nm, 130nm, 138nm, 140nm, 145.5nm, 150nm, 180nm, 200nm or any value between them.

[0052] In this invention, step S3, the magnetron sputtering copper plating process refers to the process of depositing copper on the surface of a tungsten transition layer using magnetron sputtering technology to form a copper seed layer. Magnetron sputtering technology is a commonly used technique in the prior art, and those skilled in the art can make adaptive choices according to actual needs. This invention does not impose any particular limitations on it.

[0053] In some specific embodiments, in step S3, the conditions for the magnetron sputtering copper plating process include a vacuum degree preferably not exceeding 6 × 10⁻⁶. -4 Pa, more preferably 1×10 Pa -6 Pa~6×10 -4 Pa, such as 1×10 -6 Pa, 2×10 -6 Pa, 1×10 - 5 Pa, 8×10 -5 Pa, 6×10 -4 Pa or any value between them; the working gas pressure is preferably 0.3 Pa to 1.0 Pa, such as 0.3 Pa, 0.35 Pa, 0.4 Pa, 0.5 Pa, 0.55 Pa, 0.6 Pa, 0.7 Pa, 0.8 Pa, 0.9 Pa, 1 Pa or any value between them; the sputtering temperature is preferably 100℃ to 500℃, such as 100℃, 120℃, 150℃, 180℃, 200℃, 250℃, 280℃, 300℃, 350℃, 400℃, 450℃, 500℃ or any value between them; the sputtering current is preferably 0.5 A to 3 A, such as 0.5 A, 0.8 A, 1.2 A, 1.5 A, 1.8 A, 2 A, 2.5 A, 2.8 A The sputtering voltage is preferably 300V to 600V, such as 300V, 320V, 350V, 380V, 400V, 450V, 500V, 550V, 600V, or any value between them; the sputtering power is preferably 100W to 500W, such as 100W, 120W, 150W, 180W, 200W, 250W, 280W, 300W, 350W, 400W, 450W, 500W, or any value between them; the sputtering time is preferably 5min to 20min, such as 5min, 7.5min, 10min, 12.5min, 15min, 18min, 20min, or any value between them.

[0054] In this invention, the thickness of the copper seed layer is preferably 300nm to 500nm, such as 300nm, 320nm, 340nm, 350nm, 380nm, 400nm, 430nm, 450nm, 480nm, 500nm or any value between them.

[0055] In this invention, the high-temperature calcination treatment in step S3 refers to the process of optimizing the microstructure of the copper seed layer and the inner wall of the penetrating hole under high-temperature conditions, improving the interfacial bonding force and improving its mechanical and electrical properties. This is a type of technical means commonly used in the prior art. Those skilled in the art can make adaptive choices according to actual needs. This invention does not impose any special limitations on it.

[0056] In some specific embodiments, in step S3, the conditions for the high-temperature calcination treatment include an atmosphere specifically an inert gas, and specific examples of the inert gas include, but are not limited to, argon and / or helium; the temperature is preferably 700℃~800℃, such as 700℃, 710℃, 715℃, 720℃, 725℃, 730℃, 740℃, 750℃, 780℃, 790℃, 800℃ or any value between them; the time is preferably 1h~4h, such as 1h, 1.1h, 1.3h, 1.5h, 1.8h, 2h, 2.1h, 2.3h, 2.5h, 3h, 3.5h, 3.8h, 4h or any value between them.

[0057] In this invention, step S3, the through-hole electroplating copper treatment, refers to the process of depositing metallic copper on the surface of the copper seed layer and inside the through-holes using the principle of electrolysis. This process can be further divided into two electroplating stages: a first stage with increasing current density and a second stage. More specifically, the conditions for the first stage electroplating stage include a current density of 0.5 A / dm³. 2 ~2A / dm 2 , such as 0.5A / dm 2 0.75A / dm 2 0.9A / dm 2 1A / dm 2 1.1A / dm 2 1.3A / dm 2 1.5A / dm 2 1.8A / dm 2 2A / dm 2 Or any value between them; the time is 0.5h to 2h, such as 0.5h, 0.65h, 0.75h, 0.9h, 1h, 1.2h, 1.5h, 1.8h, 2h or any value between them. The specific conditions for the second electroplating treatment include a current density of 1A / dm³. 2 ~3A / dm 2 , such as 1A / dm 2 1.1A / dm 2 1.2A / dm 2 1.3A / dm 2 1.5A / dm 21.8A / dm 2 2A / dm 2 2.3A / dm 2 2.5A / dm 2 2.6A / dm 2 2.9A / dm 2 3A / dm 2 Or any value between them; the time is 1h to 3h, such as 1h, 1.2h, 1.4h, 1.6h, 1.8h, 2h, 2.3h, 2.6h, 2.9h, 3h or any value between them.

[0058] In this invention, the copper plating solution used in the hole-filling electroplating copper treatment in step S3 is a conventional technical means used in the prior art. Those skilled in the art can make adaptive choices according to actual needs, and this invention does not impose any special limitations on it.

[0059] In some specific embodiments, in step S3, the copper plating solution used in the hole-filling copper plating treatment preferably includes: 50 g / L to 100 g / L of copper sulfate, such as 50 g / L, 55 g / L, 58 g / L, 60 g / L, 65 g / L, 70 g / L, 75 g / L, 80 g / L, 85 g / L, 90 g / L, 100 g / L or any value between them; 50 g / L to 200 g / L of sulfuric acid, such as 50 g / L, 55 g / L, 60 g / L, 70 g / L, 80 g / L, 90 g / L, 100 g / L, 120 g / L, 150 g / L, 180 g / L, 200 g / L or any value between them; and 30 ppm to 100 ppm of chloride ions, such as 30 ppm, 35 ppm, 40 ppm, 50 ppm, 60 ppm, etc. 75ppm, 80ppm, 90ppm, 100ppm or any value therein; leveling agents of 0.5% (v / v) to 1% (v / v), such as 0.5% (v / v), 0.55% (v / v), 0.6% (v / v), 0.68% (v / v), 0.7% (v / v), 0.75% (v / v), 0.8% (v / v), 0.9% (v / v), 1% (v / v) or any value therein; and brightening agents of 0.0005% (v / v) to 0.001% (v / v), such as 0.0005% (v / v), 0.0006% (v / v), 0.0007% (v / v), 0.0008% (v / v), 0.0009% (v / v), 0.001% (v / v) or any value therein. The leveling agent refers to a type of compound that can regulate the deposition rate of copper ions on the substrate surface to improve the uniformity and smoothness of the copper layer. It is a commonly used technique in existing copper electroplating technology. Those skilled in the art can make adaptive selections according to actual needs, and this invention does not impose any particular limitations on it. Specific examples include, but are not limited to, dodecyltrimethylammonium chloride. The brightener refers to a type of functional additive that can significantly improve the optical properties of the copper layer surface. It is a commonly used technique in existing copper electroplating technology. Those skilled in the art can make adaptive selections according to actual needs, and this invention does not impose any particular limitations on it. Specific examples include, but are not limited to, sodium polydithiopropane sulfonate.

[0060] In some specific embodiments, the temperature of the hole-filling electroplating copper treatment is preferably 20℃ to 30℃, such as 20℃, 21℃, 22.5℃, 24℃, 26℃, 28℃, 29℃, 30℃ or any value between them.

[0061] In this invention, the vacuum annealing process in step S3 refers to a process of annealing the formed copper layer in a vacuum environment. It is a commonly used technical means in the prior art. Those skilled in the art can make adaptive choices according to actual needs. This invention does not impose any special limitations on it.

[0062] In some specific embodiments, in step S3, the conditions for the vacuum annealing process specifically include a temperature preferably between 200°C and 300°C, such as 200°C, 210°C, 230°C, 250°C, 280°C, 290°C, 300°C, or any value between them; and a time preferably between 1h and 3h, such as 1h, 1.2h, 1.4h, 1.8h, 1.9h, 2h, 2.3h, 2.6h, 3h, or any value between them.

[0063] In this invention, step S3 preferably also includes grinding and polishing. Grinding and polishing is a type of technical means commonly used in the prior art. Those skilled in the art can make adaptive choices according to actual needs. This invention does not impose any particular limitations on it.

[0064] In some specific embodiments, in step S3, after the diamond / copper composite material is ground and polished, the thickness of the copper layer is preferably 10μm to 20μm, such as 10μm, 11μm, 12.5μm, 13μm, 14μm, 15μm, 18μm, 19.5μm, 20μm or any value between them; the roughness Ra is preferably not greater than 0.2μm.

[0065] In this invention, step S4, the electroplating of nickel refers to the process of depositing metallic nickel on the surface of diamond / copper composite material using the principle of electrolysis to form a nickel layer. This is a commonly used technical means in the prior art. Those skilled in the art can make adaptive choices according to actual needs. This invention does not impose any particular limitations on it.

[0066] In some specific embodiments, in step S4, the nickel plating solution used in the nickel plating treatment preferably includes: nickel sulfate at a concentration of 200 g / L to 300 g / L, such as 200 g / L, 210 g / L, 230 g / L, 250 g / L, 280 g / L, 300 g / L, or any value between them; and nickel chloride at a concentration of 30 g / L to 60 g / L, such as 30 g / L, 31.5 g / L, 32 g / L, 34 g / L, 38 g / L, 40 g / L, 45 g / L. L, 50 g / L, 55 g / L, 60 g / L or any value between them; boric acid from 30 g / L to 45 g / L, such as 30 g / L, 30.5 g / L, 31 g / L, 32 g / L, 34 g / L, 38 g / L, 40 g / L, 41.5 g / L, 42 g / L, 45 g / L or any value between them; pH = 3.5 to 4.5, such as 3.5, 3.6, 3.78, 3.8, 4, 4.1, 4.3, 4.5 or any value between them.

[0067] In some specific embodiments, in step S4, the conditions for the electroplating nickel treatment specifically include a temperature preferably between 50°C and 60°C, such as 50°C, 50.5°C, 51°C, 53°C, 55°C, 57.5°C, 59°C, 60°C, or any value between them; and a current density preferably 1 A / dm³. 2 ~3A / dm 2 , such as 1A / dm 2 1.1A / dm 2 1.2A / dm 2 1.5A / dm 2 1.8A / dm 2 2.05A / dm 2 2.2A / dm 2 2.4A / dm 2 2.6A / dm 2 2.8A / dm 2 3A / dm 2 Or any value between them; the time is preferably 10 min to 20 min, such as 10 min, 12 min, 15 min, 17.5 min, 19 min, 20 min or any value between them.

[0068] In this invention, the thickness of the nickel layer is preferably 3μm to 7μm, such as 3μm, 3.5μm, 3.8μm, 4μm, 4.5μm, 5μm, 5.5μm, 6μm, 6.8μm, 7μm or any value between them.

[0069] In this invention, step S4, the electroplating gold treatment refers to the process of depositing metallic gold on the surface of a nickel layer using the principle of electrolysis to form a gold layer. This is a commonly used technical means in the prior art. Those skilled in the art can make adaptive choices according to actual needs. This invention does not impose any special limitations on it.

[0070] In some specific embodiments, in step S4, the electroplating gold solution used in the electroplating gold treatment preferably includes: 2 g / L to 10 g / L of potassium gold cyanide, such as 2 g / L, 2.1 g / L, 2.3 g / L, 2.8 g / L, 3 g / L, 3.5 g / L, 4 g / L, 4.5 g / L, 5 g / L, 6 g / L, 8 g / L, 10 g / L, or any value between them; or 50 g / L to 100 g / L of potassium cyanide, such as 50 g / L, 52 g / L, 58 g / L, 60 g / L, 65 g / L. 70 g / L, 80 g / L, 90 g / L, 100 g / L or any value between them; conductive salts of 10 g / L to 30 g / L, such as 10 g / L, 12 g / L, 14 g / L, 16 g / L, 18 g / L, 20 g / L, 22 g / L, 24 g / L, 26 g / L, 28 g / L, 30 g / L or any value between them; pH = 10 to 12, such as 10, 10.3, 10.8, 11, 11.1, 11.3, 11.6, 11.8, 12 or any value between them.

[0071] In some specific embodiments, in step S4, the conditions for the electroplating gold treatment specifically include a temperature preferably between 40℃ and 70℃, specifically 40℃, 40.5℃, 42℃, 45℃, 48℃, 50℃, 55℃, 57℃, 60℃, 65℃, 68℃, 70℃, or any value between them; and a current density preferably 0.1A / dm³. 2 ~1A / dm 2 For example, 0.1A / dm 2 0.15A / dm 2 0.2A / dm 2 0.3A / dm 2 0.4A / dm 2 0.6A / dm 2 0.7A / dm 2 0.9A / dm 2 1A / dm 2Or any value between them; the preferred time is 5 min to 20 min, such as 5 min, 5.6 min, 6 min, 7 min, 7.5 min, 8 min, 10 min, 14 min, 16 min, 18 min, 20 min or any value between them. The conductive salt refers to a class of compounds that can increase the conductivity of the solution, a technique commonly used in existing electroplating processes. Those skilled in the art can make adaptive selections according to actual needs, and this invention does not impose any particular limitations on it.

[0072] In this invention, the thickness of the gold layer is preferably 1μm to 2μm, such as 1μm, 1.05μm, 1.1μm, 1.2μm, 1.3μm, 1.5μm, 1.7μm, 1.9μm, 2μm or any value between them.

[0073] The present invention also provides a heat sink sheet, which is prepared by the above-described method for preparing a heat sink sheet.

[0074] In this invention, the heat sink preferably has a conductivity of not less than 60% IACS, a thermal conductivity of not less than 800 W / (m K), a bending strength of not less than 300 MPa, and a coefficient of thermal expansion of 5.9 ppm / K to 6.4 ppm / K. In this case, the heat sink possesses excellent electrical and thermal conductivity and resistance to thermal deformation, and has a high compatibility with common semiconductor materials such as GaAs. It can well meet the requirements for heat sink materials in high-power laser bars, effectively solving the problems of high heat flux density heat dissipation and thermal stress failure in existing high-power laser devices, and has excellent application prospects.

[0075] The present invention also provides the application of the above-mentioned heat sink in the fabrication of high-power semiconductor lasers.

[0076] The embodiments of the present invention are described in detail below. These embodiments are intended to explain the present invention and should not be construed as limiting the present invention. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in the art or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all commercially available conventional products.

[0077] Example 1

[0078] This embodiment illustrates a method for preparing a heat sink sheet, referring to... Figure 1 The preparation method specifically includes the following steps:

[0079] S1. A 50W infrared picosecond laser is used to perform laser drilling on a sheet of synthetic diamond (size 10×2×0.5mm, thermal conductivity 1500W / (m K)) to form uniformly arranged through holes on the sheet of synthetic diamond. The sheet is then subjected to high-temperature reduction treatment at 750℃ for 2 hours in a hydrogen atmosphere (purity 99.9%) to obtain a vacuum-reduced drilled diamond sheet. The diameter of the through holes is 0.4mm and the hole spacing is 0.6mm.

[0080] S2. Take tungsten target material under a vacuum of 6×10⁻⁶. -4 Under the conditions of working pressure of 0.4 Pa, sputtering temperature of 200℃, sputtering current of 1.5 A, sputtering voltage of 400 V, and sputtering power of 400 W, a vacuum reduction drilled diamond sheet was subjected to magnetron sputtering tungsten plating for 10 min to form a 100 nm thick metallic tungsten transition layer.

[0081] S3, (1) Take a copper target material in a vacuum of 6×10 -4 Under the conditions of Pa, working gas pressure of 0.3 Pa, sputtering temperature of 150 °C, sputtering current of 1.0 A, sputtering voltage of 350 V, and sputtering power of 300 W, vacuum reduction drilled diamond sheets that have undergone magnetron sputtering tungsten plating are subjected to magnetron sputtering copper plating for 15 min to form a copper seed layer with a thickness of 500 nm.

[0082] (2) Take the vacuum reduction drilled diamond sheet that has been treated with magnetron sputtering copper plating and place it in a tube furnace. Calcine it for 3 hours in an argon atmosphere at 800°C and then cool it to room temperature with the furnace.

[0083] (3) Take the vacuum reduction drilled diamond sheet that has been calcined and perform copper plating treatment to fill the hole, so that a copper layer is formed and the through hole is filled with copper. Then, perform vacuum annealing treatment at 250°C for 2 hours, followed by grinding and polishing treatment to obtain diamond / copper composite material. At this time, the thickness of the copper layer is 20μm and the roughness Ra=0.16μm.

[0084] The copper plating solution used in the hole-filling copper plating process includes: 80 g / L CuSO4·5H2O, 100 g / L H2SO4, and 50 ppm Cl. - 8 mL / L dodecyltrimethylammonium chloride and 0.06 mL / L sodium polydisulfide dipropane sulfonate (purchased from Hubei Jianghan New Material Co., Ltd., hereinafter the same); the through-hole electroplating copper treatment includes: at a current density of 0.8 A / dm 2 After the first stage of electroplating was performed at a temperature of 25℃ for 1 hour, the current density was 1.6A / dm². 2 The second electroplating process was carried out for 2 hours at a temperature of 25°C.

[0085] S4. Take the diamond / copper composite material and perform electroplating with nickel and then electroplating with gold in sequence to form a nickel layer with a thickness of 5μm and a gold layer with a thickness of 1.2μm, thus obtaining a heat sink sheet.

[0086] The nickel plating solution used in the nickel plating process includes: 250 g / L NiSO4·6H2O, 50 g / L NiCl2·6H2O, and 40 g / L H3BO3, with a pH of 4.0; the conditions for the nickel plating process include a current density of 3.0 A / dm³. 2 The temperature was 55℃ and the time was 15 min. The gold plating solution used in the gold plating treatment included: 8 g / L KAu(CN), 60 g / L KCN, and 20 g / L K₂CO₃, pH = 11.0; the gold plating treatment conditions included: a current density of 0.5 A / dm³. 2 The temperature was 55℃ and the time was 10 minutes.

[0087] Figure 2 This is a photograph of the heat sink sheet prepared in this embodiment. Figure 3 This is a schematic cross-sectional view of the heat sink sheet prepared in this embodiment. In this heat sink sheet, copper coats the surface of the sheet-like synthetic diamond and fills through-holes. It should be noted that... Figure 3 The text only shows the relative relationships between the structures and does not represent the actual size. The actual size of each part in the heat sink is based on the above text description.

[0088] Example 2

[0089] This embodiment illustrates a method for preparing a heat sink sheet, specifically including the following steps:

[0090] S1. A 50W infrared picosecond laser is used to perform laser drilling on a sheet of synthetic diamond (size 10×1×1mm, thermal conductivity 1500W / (mK)) to form uniformly arranged through holes on the sheet of synthetic diamond. The sheet is then subjected to high-temperature reduction treatment at 800℃ for 2 hours in a hydrogen atmosphere (purity 99.9%) to obtain a vacuum-reduced drilled diamond sheet. The diameter of the through holes is 0.3mm and the hole spacing is 0.5mm.

[0091] S2. Take tungsten target material under a vacuum of 6×10⁻⁶. -4 Under the conditions of working pressure of 0.4 Pa, sputtering temperature of 200℃, sputtering current of 1.5 A, sputtering voltage of 400 V, and sputtering power of 400 W, a vacuum reduction drilled diamond sheet was subjected to magnetron sputtering tungsten plating for 10 min to form a 100 nm thick metallic tungsten transition layer.

[0092] S3, (1) Take a copper target material in a vacuum of 6×10-4 Under the conditions of Pa, working gas pressure of 0.3 Pa, sputtering temperature of 150 °C, sputtering current of 1.0 A, sputtering voltage of 350 V, and sputtering power of 300 W, vacuum reduction drilled diamond sheets that have undergone magnetron sputtering tungsten plating are subjected to magnetron sputtering copper plating for 15 min to form a copper seed layer with a thickness of 500 nm.

[0093] (2) Take the vacuum reduction drilled diamond sheet that has been treated with magnetron sputtering copper plating and place it in a tube furnace. Calcine it for 3 hours in an argon atmosphere at 800°C and then cool it to room temperature with the furnace.

[0094] (3) Take the vacuum reduction drilled diamond sheet that has been calcined and perform copper plating treatment to fill the hole, so that a copper layer is formed and the through hole is filled with copper. Then, perform vacuum annealing treatment at 250°C for 2 hours, followed by grinding and polishing treatment to obtain diamond / copper composite material. At this time, the thickness of the copper layer is 15μm and the roughness Ra=0.18μm.

[0095] The copper plating solution used in the hole-filling copper plating process includes: 80 g / L CuSO4·5H2O, 100 g / L H2SO4, and 50 ppm Cl. - 8 mL / L leveling agent and 0.06 mL / L brightener; the through-hole electroplating copper treatment includes: at a current density of 0.8 A / dm² 2 The first stage of electroplating was carried out at a temperature of 25℃ for 2 hours, with a current density of 2.5A / dm³. 2 The second electroplating process was carried out for 2 hours at a temperature of 25°C.

[0096] S4. Take the diamond / copper composite material and perform electroplating with nickel and then electroplating with gold in sequence to form a nickel layer with a thickness of 5μm and a gold layer with a thickness of 1.2μm, thus obtaining a heat sink sheet.

[0097] The nickel plating solution used in the nickel plating process includes: 250 g / L NiSO4·6H2O, 50 g / L NiCl2·6H2O, and 40 g / L H3BO3, with a pH of 4.0; the conditions for the nickel plating process include a current density of 3.0 A / dm³. 2 The temperature was 55℃ and the time was 15 min. The gold plating solution used in the gold plating treatment included: 8 g / L KAu(CN), 60 g / L KCN, and 20 g / L K₂CO₃, pH = 11.0; the gold plating treatment conditions included: a current density of 0.5 A / dm³. 2 The temperature was 55℃ and the time was 10 minutes.

[0098] Comparative Example 1

[0099] The comparative example uses the method provided in Example 1 to prepare the heat sink sheet. The difference is that in step S1, the temperature of the high-temperature reduction treatment is 500°C and the time is 2 hours. Other conditions are the same, and the heat sink sheet is obtained.

[0100] Comparative Example 2

[0101] The comparative example uses the method provided in Example 1 to prepare the heat sink sheet. The difference is that in step S1, the temperature of the high-temperature reduction treatment is 1000°C and the time is 2 hours. Other conditions are the same, and the heat sink sheet is obtained.

[0102] Comparative Example 3

[0103] The comparative example uses the method provided in Example 1 to prepare the heat sink sheet. The difference is that in step S1, the temperature of the high-temperature reduction treatment is 750°C and the time is 5 hours. Other conditions are the same, and the heat sink sheet is obtained.

[0104] Comparative Example 4

[0105] The comparative example uses the method provided in Example 1 to prepare the heat sink sheet. The difference is that in step S1, the temperature of the high-temperature reduction treatment is 750°C and the time is 0.5h. Other conditions are the same, and the heat sink sheet is obtained.

[0106] Test Example 1

[0107] This test example illustrates the high-temperature reduction treatment effect of the heat sink preparation method provided in the above embodiments and comparative examples. The materials after high-temperature reduction treatment were observed under a microscope at the same magnification, and the results are shown in Table 1.

[0108] Table 1.

[0109]

[0110]

[0111] As shown in Table 1, the high-temperature reduction treatment has a significant impact on the morphology of the vacuum-reduced drilled diamond sheet. Only when the high-temperature reduction treatment is carried out at a temperature of 750℃~800℃ and a treatment time of 1~3h can the free carbon on the laser-cut surface be fully removed without damaging the surface of the sheet-like synthetic diamond.

[0112] Comparative Example 5

[0113] The comparative example uses the method provided in Example 1 to prepare the heat sink sheet. The difference is that in step S1, the diameter of the through hole in the sheet-like synthetic diamond is 1.0 mm, the hole spacing is 1.2 mm, and other conditions are the same, to obtain the heat sink sheet.

[0114] Comparative Example 6

[0115] The comparative example uses the method provided in Example 1 to prepare the heat sink sheet. The difference is that in step S1, the diameter of the through hole in the sheet-like synthetic diamond is 0.1 mm, the hole spacing is 0.3 mm, and other conditions are the same, to obtain the heat sink sheet.

[0116] Comparative Example 7

[0117] The comparative example uses the method provided in Example 1 to prepare the heat sink sheet. The difference is that in step S1, the diameter of the through hole in the sheet-like synthetic diamond is 0.4 mm, the hole spacing is 1.4 mm, and other conditions are the same, to obtain the heat sink sheet.

[0118] Comparative Example 8

[0119] The comparative example uses the method provided in Example 1 to prepare the heat sink sheet. The difference is that in step S1, the diameter of the through hole in the sheet-like synthetic diamond is 0.4 mm and the hole spacing is 0.5 mm. Other conditions are the same, and the heat sink sheet is obtained.

[0120] Comparative Example 9

[0121] This comparative example uses the method provided in Example 1 to prepare the heat sink sheet, except that in step S3, the through-hole electroplating copper treatment includes: at a current density of 2A / dm 2 After the first stage of electroplating was performed at a temperature of 25℃ for 2 hours, the current density was 1.6A / dm³. 2 The second electroplating process was carried out at a temperature of 25°C for 2 hours; all other conditions were the same, and a heat sink sheet was obtained.

[0122] Comparative Example 10

[0123] This comparative example uses the method provided in Example 1 to prepare the heat sink sheet, except that in step S3, the through-hole electroplating copper treatment includes: at a current density of 0.8 A / dm 2 After the first stage of electroplating was performed at a temperature of 25℃ for 2 hours, the current density was 5.0 A / dm². 2 The second electroplating stage was carried out at a temperature of 25℃ for 2 hours; all other conditions were the same, and a heat sink sheet was obtained.

[0124] Test Example 2

[0125] This test example illustrates the effect of copper plating on the filling of holes in the heat sink preparation method provided in the above embodiments and comparative examples. The material after copper plating on the filling of holes was observed under a microscope at the same magnification, and the results are shown in Table 2.

[0126] Table 2.

[0127]

[0128] As shown in Table 2, the pore size and spacing of the through-holes formed on the sheet-like synthetic diamond, the conditions of the high-temperature reduction treatment, and the current density in the copper plating process have a significant impact on the subsequent copper plating effect. The optimal results are achieved when the pore size is set to 0.3mm–0.4mm, the pore spacing to 0.5mm–0.6mm, the high-temperature reduction treatment temperature to 750℃–800℃, the treatment time to 1h–3h, and the first-stage current density in the copper plating process to 0.7A / dm². 2 ~0.9A / dm 2 The current density in the second section is 1.6 A / dm. 2 ~2.5A / dm 2 Only when the copper filling inside the hole is full and the copper layer thickness on the surface is uniform can the hole-filling electroplating treatment effect be achieved.

[0129] Test Example 3

[0130] This test example illustrates the relevant performance of the heat sink provided in the above embodiments and comparative examples. The specific tests include:

[0131] 1. Conductivity: The conductivity of each heat sink was tested according to the ASTM E1004 test standard;

[0132] 2. Bending strength: The bending strength of each heat sink sheet was tested in accordance with the GB / T 3851-2013 test standard;

[0133] 3. Thermal conductivity: The thermal conductivity of each heat sink was tested according to the ASTM E1461 test standard;

[0134] 4. Coefficient of thermal expansion: The coefficient of thermal expansion of each heat sink was tested according to the ASTM E831 test standard, and the results are shown in Table 3.

[0135] Table 3.

[0136]

[0137] As shown in Table 3, compared with Comparative Examples 1-10, the heat sinks provided in Examples 1 and 2 of this invention have a conductivity >60% IACS, exhibiting excellent conductivity and good compatibility with highly integrated circuits; a thermal conductivity >800W / (mK), meeting the thermal conductivity requirements and effectively satisfying the heat dissipation needs of high-power semiconductor lasers; a bending strength >300MPa, demonstrating strong resistance to deformation and high mechanical reliability; and a thermal expansion coefficient of 5.9ppm / K to 6.4ppm / K, showing high compatibility with common semiconductor materials such as GaAs. This effectively meets the requirements for heat sink materials in high-power laser bars, effectively solving the problems of high heat flux density heat dissipation and thermal stress failure in existing high-power laser devices, and demonstrating excellent application prospects.

[0138] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention without departing from the principles and spirit of the present invention.

Claims

1. A method for preparing a heat sink sheet, characterized in that, The preparation method includes: S1. Take a sheet of synthetic diamond and perform laser drilling to form through holes with a diameter of 0.3mm to 0.4mm and a spacing of 0.5mm to 0.6mm on the sheet of synthetic diamond. Then, perform high-temperature reduction treatment at 750℃ to 800℃ for 1h to 3h in a reducing atmosphere to obtain a vacuum reduced drilled diamond sheet. S2. Take the vacuum reduction drilled diamond sheet and perform magnetron sputtering tungsten plating treatment to form a metallic tungsten transition layer on the surface of the sheet-shaped artificial diamond. S3. Take the vacuum reduction drilled diamond sheet that has undergone the magnetron sputtering tungsten plating treatment and perform magnetron sputtering copper plating treatment to form a copper seed layer on the surface of the tungsten transition layer. Then, perform high-temperature calcination treatment, hole-filling electroplating copper treatment and vacuum annealing treatment in sequence to form a copper layer on the surface of the copper seed layer and fill the through holes with copper to obtain a diamond / copper composite material. S4. The diamond / copper composite material is subjected to nickel plating and gold plating to form a nickel layer and a gold layer on the surface of the diamond / copper composite material, thereby obtaining the heat sink sheet. In step S3, the through-hole electroplating copper treatment includes: at a current density of 0.5 A / dm 2 ~2A / dm 2 The first stage of electroplating is carried out for 0.5h to 2h at a current density of 1A / dm². 2 ~3A / dm 2 The second electroplating process is then carried out for 1 to 3 hours.

2. The method for preparing the heat sink sheet according to claim 1, characterized in that, In step S1, the thermal conductivity of the sheet-like synthetic diamond is not less than 1200 W / (m K); Optionally, the thickness of the sheet-like synthetic diamond is 0.1 mm to 2 mm; Optionally, the method of forming a through hole in the sheet-like synthetic diamond includes: taking the sheet-like synthetic diamond and performing laser drilling; Optionally, the laser used in the laser drilling process is selected from infrared picosecond lasers and / or ultraviolet picosecond lasers; Optionally, the power of the laser used in the laser drilling process is 20W to 70W; Optionally, the reducing atmosphere of the high-temperature reduction treatment is hydrogen and / or methane.

3. The method for preparing the heat sink sheet according to claim 1, characterized in that, In step S2, the vacuum degree of the magnetron sputtering tungsten plating process is no greater than 6 × 10⁻⁶. -4 The working pressure is 0.3Pa~1Pa, the sputtering temperature is 100℃~500℃, the sputtering current is 0.5A~3A, the sputtering voltage is 300V~600V, the sputtering power is 100W~500W, and the time is 5min~20min. Optionally, the thickness of the tungsten transition layer is 100 nm to 200 nm.

4. The method for preparing the heat sink sheet according to claim 1, characterized in that, In step S3, the vacuum degree of the magnetron sputtering copper plating process is no greater than 6 × 10⁻⁶. -4 Pa, working gas pressure is 0.3Pa~1Pa, sputtering temperature is 100℃~500℃, sputtering current is 0.5A~3A, sputtering voltage is 300V~600V, sputtering power is 100W~500W, and time is 5min~20min; Optionally, the thickness of the copper seed layer is 300 nm to 500 nm.

5. The method for preparing a heat sink sheet according to claim 1, characterized in that, In step S3, the atmosphere of the high-temperature calcination treatment is an inert gas, the temperature is 700℃~800℃, and the time is 1h~4h. Optionally, the copper plating solution used in the hole-filling electroplating copper treatment includes: 50 g / L to 100 g / L copper sulfate, 50 g / L to 200 g / L sulfuric acid, 30 ppm to 100 ppm chloride ions, 0.5% (v / v) to 1% (v / v) leveling agent and 0.0005% (v / v) to 0.001% (v / v) brightener; Optionally, the temperature for the copper plating process for filling holes is 20°C to 30°C.

6. The method for preparing a heat sink sheet according to claim 1, characterized in that, In step S3, the vacuum annealing process is carried out at a temperature of 200℃ to 300℃ for 1 hour to 3 hours. Optionally, step S3 includes a grinding and polishing process, wherein after the diamond / copper composite material is ground and polished, the copper layer thickness is 10μm to 20μm and the roughness Ra is not greater than 0.2μm.

7. The method for preparing a heat sink sheet according to claim 1, characterized in that, In step S4, the nickel plating solution used in the nickel plating process includes: 200 g / L to 300 g / L nickel sulfate, 30 g / L to 60 g / L nickel chloride, and 30 g / L to 45 g / L boric acid, with a pH of 3.5 to 4.

5. Optionally, the electroplating nickel treatment is performed at a temperature of 50°C to 60°C and a current density of 1 A / dm³. 2 ~3A / dm 2 The time is 10 to 20 minutes; Optionally, the thickness of the nickel layer is 3 μm to 7 μm; Optionally, the gold plating solution used in the gold plating process includes: 2 g / L to 10 g / L of potassium gold cyanide, 50 g / L to 100 g / L of potassium cyanide and 10 g / L to 30 g / L of conductive salt, with a pH of 10 to 12. Optionally, the conductive salt is potassium carbonate; Optionally, the electroplating gold treatment is performed at a temperature of 40°C to 70°C and a current density of 0.1 A / dm³. 2 ~1A / dm 2 The time is 5 to 20 minutes; Optionally, the thickness of the gold layer is 1 μm to 2 μm.

8. A heat sink sheet, characterized in that, The heat sink sheet is prepared by the heat sink sheet preparation method according to any one of claims 1 to 7.

9. The heat sink sheet according to claim 8, characterized in that, The heat sink sheet has an electrical conductivity of not less than 60% IACS, a thermal conductivity of not less than 800 W / (m K), a bending strength of not less than 300 MPa, and a coefficient of thermal expansion of 5.9 ppm / K to 6.4 ppm / K.

10. The application of the heat sink sheet according to claim 8 or 9 in the fabrication of high-power semiconductor lasers.

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