Novel crystal batten and disc welding method

Abstract

The invention relates to the technical field of laser manufacturing, and particularly discloses a novel crystal lath and disc welding method which comprises the following steps: plating a gold film on a welding surface of a heat sink and a laser amplification medium, plating a special film layer on the gold film, an indium soldering lug, a heat sink plated with a special film layer and a laser amplification medium plated with a special film layer are assembled into an assembly body, the assembly body is put into a welding furnace, and heating and pressurizing welding are carried out, so that the special film layer and the surface of the indium soldering lug are subjected to an interface microcell eutectic reaction, and a welding seam of a welding surface is filled. According to the technical scheme, pollution and cavities generated by large-range welding flux melting are effectively avoided, due to the fact that the pressure applied by welding is small, the problem that a solid laser is not prone to retreating due to too large stress is solved, the defects generated in the laser welding process are overcome, the performance and working reliability of the laser are guaranteed, and the laser welding quality is improved. And a method is provided for the solid laser to generate higher power and better light beam quality.

Description

Technical Field

[0001] The invention relates to the technical field of laser manufacturing, and in particular to a novel welding method for crystal slats and disks. Background Art

[0002] Solid-state lasers have a wide range of applications and development potential in many fields such as medicine, industrial processing, scientific research, and military. Therefore, high power and high beam quality have become important indicators in the research of laser technology. However, there is a paradox in the research process, that is, as the output power of the laser increases, the beam quality will gradually deteriorate. The main reason for this paradox is the strong thermal effect generated by the laser gain medium itself when the solid-state laser is operated at high power. Breaking through the internal thermal effect is the key to obtaining high-power and high-beam-quality lasers.

[0003] At present, most of the welding and packaging of solid-state lasers are realized by indium solder, mainly using two methods: evaporation indium and indium welding sheet. Evaporation welding is to use indium as a coating to be plated on the welding surface by evaporation. The thickness of the plated indium layer is relatively thin, basically about tens of microns. After exceeding a certain thickness, the surface of the evaporated indium layer is uneven, and the welding layer is thin and uneven, which makes the thermal expansion coefficient between the laser gain medium and the heat sink mismatch, affecting the beam quality of the laser. At the same time, welding defects are also prone to occur, which affects the heat extraction inside the crystal and generates large thermal stress. For example, the patent with the publication number CN109361138A proposes a slab laser gain medium packaging method, which is based on evaporation welding and uses the method of sandwiching transition pieces. To a certain extent, it reduces the welding stress of the laser gain medium and the heat sink, and reduces the thermal distortion of the welding layer when the laser gain medium is working. However, its technical solution uses a temperature of 170-260°C, while the melting point of indium is 156 ℃, in the selected temperature range, indium has melted, which is a typical brazing reaction. There are welding voids easily between the molten indium and the solid gold film and the transition piece, which affects the heat dissipation to a certain extent. The welding and packaging of large-size strips have high requirements for flatness. The inevitable temperature difference in the process of evaporating indium leads to the inconsistency between the thickness of the indium plating layer around the large-size strip and the thickness of the indium plating layer in the middle, resulting in a decrease in flatness. This technical solution does not solve the problem of welding and packaging of large-size strips. Indium soldering is a process in which the indium solder is melted and then solidified. Under the action of gravity and surface tension, the melted solder is not easy to control and may flow to the welding surface of the lower heat sink, resulting in serious uneven distribution of solder in the welding layer, and inevitably uneven heat dissipation and stress distribution, which aggravates the thermal effect of the laser gain medium and seriously affects the performance of the solid-state laser.

[0004] Therefore, it is necessary to propose a new method for welding crystal slats and disks to improve the heat dissipation effect and the performance of solid-state lasers. Summary of the invention

[0005] The purpose of the present invention is to solve the problem that the solder distribution of the existing solid laser welding layer is seriously uneven, resulting in poor heat dissipation effect of the solid laser. A new welding method for crystal strips and discs is now provided.

[0006] The technical solution of the present invention is: A novel method for welding crystal slats and discs comprises the following steps: A gold film is plated on the welding surface of the heat sink and the welding surface of the laser amplifying medium, and a special film layer is plated on the gold film; Assembling an indium solder sheet, a heat sink coated with a special film layer, and a laser amplifying medium coated with a special film layer into an assembly; The assembly is placed in a welding furnace and heated and pressurized for welding. The heating temperature is between 110℃ and 150℃, so that the special film layer and the surface of the indium solder sheet undergo an interface micro-area eutectic reaction and then fully diffuse to complete the welding.

[0007] Furthermore, the special film layer is a silver film or a tin film.

[0008] Furthermore, the thickness of the silver film or the tin film is 100 nm-1000 nm.

[0009] Furthermore, the thickness of the indium solder sheet is 0.1 mm-0.8 mm.

[0010] Furthermore, the welding furnace is in a vacuum state during welding of the assembly.

[0011] Furthermore, the pressure applied during welding of the assembly is 0.1Mpa-0.5Mpa.

[0012] Furthermore, the laser amplifying medium is a crystal slab or disk.

[0013] The invention discloses a novel method for welding crystal slabs and disks. The method utilizes the interface eutectic reaction between a special film layer and an indium solder to obtain a micro-region liquid phase. Thus, the indium solder is ensured not to melt and the rapid reaction between the indium and the gold film is accelerated to complete the welding of the solid laser. The unmelted indium solder sheet will not have welding voids during welding, thereby ensuring the heat dissipation effect. The invention mainly relies on the special film layer and the indium solder to be closely fitted under a certain pressure to better realize the mutual diffusion of metal atoms. A low-melting-point eutectic liquid phase is formed at the welding interface at a temperature lower than the melting point of indium as a connection medium for completing welding. Indium reacts rapidly with the gold film through the liquid phase to generate another connection medium for completing welding. The two connection media are interdependent to form a welding joint with uniform composition. Since a local liquid phase appears at the welding interface, the reaction speed is accelerated and the connection pressure is reduced, so the stress generated at the welding surface is small. In addition, the liquid phase of the low-melting-point eutectic can fill the voids at the welding interface, thereby improving the heat dissipation effect of the solid laser and further improving the power and working reliability of the solid laser. Compared with the traditional technology, the technical solution adopts a temperature lower than the melting point of the solder to effectively avoid the pollution and voids caused by the melting of a large range of solder. Since the indium solder sheet is not melted, the thickness of the solder can be controlled, thereby solving the problem of thermal expansion coefficient mismatch between the heat sink and the laser amplification medium, and also solving the thermal expansion coefficient mismatch problem existing in the welding package of laser amplification media of various sizes, especially the welding package of large-size strips, which can not only ensure the welding effect, but also eliminate thermal stress, and ensure the light output efficiency and working stability of the laser; in addition, since the pressure applied during the welding process is relatively small, the problem of excessive stress and difficulty in retreat of the solid laser is avoided, the defects generated during the laser welding process are solved, the performance and working reliability of the laser are guaranteed, and a method is provided for the solid laser to generate higher power and better beam quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a flow chart of the present invention; Figure 2 This is a schematic diagram of the structure of assembly a in Example 2 of the present invention; Figure 3 This is a schematic diagram of the structure of assembly b in Example 3 of the present invention; Figure 4 This is a flow chart of Example 1 of the present invention.

[0015] Figure numerals: 11, heat sink under the slat; 12, heat sink on the slat; 13, disk heat sink; 2, gold film; 3, special film layer; 4, indium solder sheet; 5, crystal slat; 6, disk. DETAILED DESCRIPTION

[0016] In order to make the technical means, technical features, invention objectives and technical effects achieved by the present invention easy to understand, the present invention is further explained below with reference to specific illustrations.

[0017] Embodiment 1: like Figure 4 As shown, this embodiment provides a novel method for welding crystal slats and disks, comprising the following steps: S01: The heat sink and the crystal slab 5 or the gold film 2 of the welding surface of the disc 6 is coated with a special film layer 3; S02: The heat sink, indium solder sheet 4, crystal slab 5 or disc 6 are assembled in sequence into an assembly; S03: The assembly is moved into a welding furnace, heated and pressurized for welding, and an interface micro-region eutectic reaction occurs between the special film layer 3 and the surface of the indium welding sheet 4, and then the welding is completed by sufficient diffusion.

[0018] In S01, in order to ensure the welding effect and the light emitting effect of the laser, a special film layer 3 is plated on the gold film 2 on the welding surface of the heat sink and the crystal slab 5 and the disk 6. The special film layer 3 and the indium solder sheet 4 need to undergo a eutectic reaction at the interface to produce an interface micro-region liquid phase, so a silver film or a tin film can be selected.

[0019] Preferably, to ensure the welding effect, the heat sink and the welding surfaces of the crystal slab 5 and the disk 6 are provided with a gold film 2, and the special film layer 3 plated on the gold film 2 is a silver film or a tin film, and the thickness of the silver film or the tin film is 100nm-1000nm.

[0020] Specifically, the heat sink in the solid laser composed of crystal slabs 5 is divided into a slab upper heat sink 12 and a slab lower heat sink 11 , and the heat sink in the solid laser composed of disks is a disk heat sink 13 .

[0021] To ensure the welding effect, in S02, the thickness of the indium welding sheet 4 is 0.1 mm-0.8 mm.

[0022] In order to ensure the effect of welding the assembly and the light quality of the laser, the welding furnace is in a vacuum state when welding the assembly a or b in S03 to prevent the generation of oxide film / oxidizing substances that affect the welding quality.

[0023] In order to ensure sufficient diffusion between atoms and complete welding, the pressure applied during assembly welding is 0.1MPa-0.5MPa.

[0024] In order to ensure local liquefaction of the interface micro-area between the indium solder sheet 4 and the special film layer 3, and to allow the atoms between the indium solder sheet 4 and the gold film 2 to fully diffuse and react, thereby achieving an excellent welding effect, the temperature range during the welding process is 110°C-150°C.

[0025] Embodiment 2: The similarities between this embodiment and the first embodiment are not repeated here. The difference between the present embodiment and the first embodiment is as follows: Figure 2 As shown, a novel method for welding crystal slats and disks comprises the following steps: (1) selecting a Nd:YAG crystal slat 5 with a size of 200 mm*60 mm*10 mm, plating a gold film 2 on the upper and lower welding surfaces of the crystal slat 5, and then selecting silver as a special film layer 3 that reacts eutectic with indium at the interface to produce a liquid medium, wherein the thickness of the plated gold film 2 is 400 nm, and the thickness of the silver film is 200 nm; similarly, a gold film 2 is plated on the lower heat sink 11 and the upper heat sink 12 of the slat with a reserved cooling channel, and a silver film is plated on the gold film 2, and the coating thickness is consistent with the crystal slat 5.

[0026] (2) The assembly is assembled in the order of lower strip heat sink 11 - indium solder sheet 4 - crystal strip 5 - indium solder sheet 4 - upper strip heat sink 12 into an assembly a, wherein the thickness of the indium solder sheet is 0.4 mm.

[0027] (3) Move assembly a into a vacuum welding furnace, evacuate the welding furnace chamber to a vacuum state according to the procedure, apply a pressure of 0.3 MPa and start the heating program to increase the temperature. When heated to 146°C, a liquid phase is generated in the interface micro-region and then the temperature is kept for 5 minutes. The temperature is then lowered to 120°C and kept for 30 minutes. The heating is turned off and the furnace is naturally cooled to room temperature. Assembly a is taken out to complete the welding.

[0028] Embodiment three: The similarities between this embodiment and the first embodiment are not repeated here. The difference between the present embodiment and the first embodiment is as follows: Figure 3 As shown, a novel method for welding crystal slabs and disks comprises the following steps: (1) a Nd:YAG disk 6 of size φ80mm*5mm is selected, and silver is selected as a special film layer 3 on the gold-plated film 2 on the lower welding surface thereof, which reacts with indium at the interface to produce a liquid medium, wherein the thickness of the gold-plated film 2 is 400nm, and the thickness of the silver film is 100nm; similarly, a silver film is plated on the gold film 2 on the welding surface of the disk heat sink 13, and the thickness of the coating is consistent with the disk crystal.

[0029] (2) The disk heat sink 13 - indium solder sheet 4 - disk 6 are assembled in the order of assembly b, wherein the thickness of the indium solder sheet 4 is 0.1 mm.

[0030] (3) Move assembly b into a vacuum welding furnace, evacuate the welding furnace to a vacuum state according to the procedure, apply 0.1 MPa and pressure, and heat it at the same time. When it is heated to 150°C, a liquid phase is generated in the interface micro-region, and then keep it warm for 5 minutes, cool it down to 120°C, keep it warm for 30 minutes, turn off the heating and cool it naturally to room temperature, take out assembly b, and complete the welding.

[0031] The special film layers of Examples 2 and 3 are both silver films. During the welding process, they are first heated to a certain temperature. The metal atoms between the indium solder sheet and the silver film diffuse with each other to produce a eutectic reaction, so that a liquid alloy is formed at the welding interface as a connection medium to complete the welding. In order to ensure that the liquid metal alloy fills the capillary gap, a uniform liquid film is formed at the connection interface and it is necessary to briefly keep it warm at this temperature. Indium reacts quickly with the gold film 2 through the liquid phase to generate another connection medium to complete the welding. The connection temperature is then reduced to a certain temperature for insulation to homogenize the solid phase components of the two connection interfaces. The two connection media are interdependent to form a welding joint with uniform composition. Due to the appearance of a local liquid phase at the welding interface, the reaction speed is accelerated and the connection pressure is reduced. The welding thickness is uniform, the heat dissipation effect is excellent, and the stress caused by welding is also small and easy to retreat, which improves the beam quality of the laser.

[0032] Embodiment 4: The similarities between this embodiment and the first embodiment are not repeated here. The difference between the present embodiment and the first embodiment is as follows: Figure 1 As shown, a novel method for welding crystal slats and disks comprises the following steps: plating a gold film on the welding surface of a heat sink and a 210mm*80mm*12mm Nd:YAG slat crystal, plating a special film layer on the gold film, assembling the heat sink, the indium solder sheet and the slat crystal coated with the special film layer into an assembly, placing the assembly into a welding furnace, and welding by heating and pressurizing, so that the special film layer and the surface of the indium solder sheet undergo an interface micro-region eutectic reaction, thereby allowing the indium solder sheet and the gold film to be quickly and fully diffused and connected through the liquid phase generated by the eutectic reaction to complete welding.

[0033] Preferably, the special film layer is a tin film, preferably, the thickness of the tin film is 1000 nm, preferably, the thickness of the indium solder sheet is 0.8 mm, preferably, the welding furnace is in a vacuum state when the assembly is welded, preferably, the pressure applied when the assembly is welded is 0.5 MPa, preferably, the temperature when the assembly is welded is 120°C, and the interface micro-region is kept warm for 5 minutes after the liquid phase is generated, and then the temperature is reduced to 110°C and kept warm for 30 minutes, and then the heating is turned off and naturally cooled to room temperature, the assembly is taken out, and the welding is completed.

[0034] Embodiment five: The similarities between this embodiment and the first embodiment are not repeated here. The difference between the present embodiment and the first embodiment is as follows: Figure 1As shown, a novel method for welding crystal slats and disks comprises the following steps: plating a gold film on the welding surface of a heat sink and a 180mm*70mm*8mm Nd:YAG slat crystal, plating a special film layer on the gold film, assembling the heat sink, the indium solder sheet and the slat crystal coated with the special film layer into an assembly, placing the assembly into a welding furnace, and welding by heating and pressurizing to cause an interface micro-region eutectic reaction between the special film layer and the surface of the indium solder sheet, so that the indium solder sheet and the gold film are quickly and fully diffused and connected through the liquid phase generated by the eutectic reaction to complete welding.

[0035] Preferably, the special film layer is a tin film, preferably, the thickness of the tin film is 500 nm, preferably, the thickness of the indium solder sheet is 0.6 mm, preferably, the welding furnace is in a vacuum state when the assembly is welded, preferably, the pressure applied when the assembly is welded is 0.4 MPa, preferably, the temperature when the assembly is welded is 130°C, and after the liquid phase is generated in the interface micro-region, the temperature is kept for 5 minutes, then the temperature is reduced to 110°C, and the temperature is kept for 30 minutes, and then the heating is turned off and naturally cooled to room temperature, the assembly is taken out, and the welding is completed.

[0036] The above description is only a preferred embodiment of the present invention and is not intended to limit the scope of implementation of the present invention. That is, all equivalent changes and modifications made according to the content of the patent application scope of the present invention should belong to the technical scope of the present invention.

Claims

1. A novel method for welding crystal slats and discs, characterized in that: The following steps are involved: A gold film (2) is plated on the welding surface of the heat sink and the welding surface of the laser amplifying medium, and a special film layer (3) is plated on the gold film (2); Assembling an indium solder sheet (4), a heat sink coated with a special film layer (3), and a laser amplifying medium coated with a special film layer (3) into an assembly; The assembly is placed in a welding furnace and heated and pressurized for welding. The heating temperature is between 110° C. and 150° C., so that the special film layer (3) and the surface of the indium welding sheet (4) undergo an interface micro-region eutectic reaction and then diffuse to complete welding.

2. The novel crystal slat and disc welding method according to claim 1 is characterized in that: The special film layer (3) is a silver film or a tin film.

3. The novel crystal plate and disc welding method according to claim 2, characterized in that: The thickness of the silver film or tin film is 100nm-1000nm.

4. The novel crystal plate and disc welding method according to claim 1, characterized in that: The thickness of the indium solder sheet (4) is 0.1 mm-0.8 mm.

5. The novel crystal slat and disc welding method according to claim 1 is characterized in that: The welding furnace is in a vacuum state during assembly welding.

6. The novel crystal slat and plate welding method according to claim 1 is characterized in that: The pressure applied during assembly welding is 0.1Mpa-0.5Mpa.

7. The novel crystal slat and plate welding method according to claim 1 is characterized in that: The laser amplification medium is a crystal slab (5) or a disk (6).

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