A laser TO package structure and a packaging method thereof

Abstract

The application discloses a kind of laser TO packaging structure, including tube seat, tube cap and pin, the upper portion of the middle part of tube seat is equipped with heat sink, heat sink and tube seat are integrally formed structure, the lateral surface of heat sink is vertical plane, heat sink vertical plane is equipped with thermoelectric cooler, the cold face of thermoelectric cooler is equipped with substrate, substrate is equipped with laser chip and thermistor, the upper end of tube cap is equipped with window, window is equipped with light window, light window is super-structured lens or lens, the vertical plane of heat sink is equipped with first reference scale vertically and second reference scale transversely, the inner side wall of tube cap is equipped with getter, the application further discloses a kind of packaging method of laser TO packaging structure.The application realizes the position accurate positioning and orientation of laser chip and light window, improves light beam pointing accuracy, can shorten heat conduction path, is favorable for accurate temperature control and heat dissipation in tube cap sealed cavity, getter improves the reliability of product and eliminates the influence of residual gas on spectrum.

Description

Technical Field

[0001] This invention relates to the field of semiconductor chip packaging technology, and in particular to a laser TO packaging structure and packaging method thereof. Background Technology

[0002] TO packaging is one of the most representative and widely used standard packaging forms in traditional discrete device packaging, with advantages such as robust structure, good heat dissipation performance, and low cost. Its structure usually consists of three parts: a shell, leads, and a sealing structure. The shell protects the internal chip, the leads connect the internal chip to external circuitry, and the sealing structure ensures that the chip is protected from external environmental influences.

[0003] The external structure of a conventional laser TO package includes a socket and a cap, while the internal components consist of a heat sink, a thermoelectric cooler, a thermistor, a substrate, and a laser chip. Specifically, the socket has several pins at its bottom, the thermoelectric cooler is positioned above the socket, the heat sink is positioned above the thermoelectric cooler, the substrate is mounted on the heat sink, and the laser chip and the thermistor are mounted on the substrate.

[0004] This structure has the following significant problems:

[0005] 1. The heat generated by the laser chip needs to be conducted through the substrate to the heat sink, and then to the thermoelectric cooler. The heat conduction path is long and the thermal resistance is high, which seriously affects the temperature control accuracy and heat dissipation effect, and easily leads to the chip junction temperature rise and performance degradation.

[0006] 2. The laser beam emitted by the laser chip needs to be precisely emitted from the center of the optical window to the target position, which places extremely high demands on the spacing and coaxiality between the chip and the optical window. However, in existing structures, the laser chip is placed in a fixed position, lacking an effective reference, making it difficult to adjust the emitted beam pattern and adapt to different application requirements.

[0007] 3. If residual water vapor or carbon dioxide exists within the encapsulation cavity, or if there is a leak, water vapor can easily penetrate the cavity. When water vapor molecules adsorb onto the laser's end face, under laser irradiation, these molecules dissociate and react with the end face material, disrupting the crystal structure and generating surface states. These surface states, acting as non-radiative recombination centers, consume injected carriers without generating photons, leading to heat generation. Simultaneously, the reaction products have poor thermal conductivity, exacerbating localized temperature rise at the end face. This increased temperature further accelerates the oxidation reaction rate, creating a vicious cycle that can ultimately lead to localized melting of the end face material, resulting in catastrophic optical damage, laser chip contamination, efficiency reduction, and even device failure, making long-term stability difficult to guarantee. Carbon dioxide molecules are highly infrared reactive molecules, with strong characteristic absorption peaks in their vibrational and rotational energy levels in the mid-infrared band, reducing the output efficiency of infrared lasers. Furthermore, the combination of carbon dioxide and trace amounts of water vapor can create a weakly acidic environment, which accelerates electrochemical corrosion at wire bonding points, making long-term operational reliability difficult to guarantee.

[0008] The getter can absorb not only water vapor and carbon dioxide, but also oxygen, carbon monoxide, nitrogen, hydrogen, and other gases. Its core principle is to physically adsorb the gases and then irreversibly chemically react with active gases to "solidify" and absorb them, maintaining a high vacuum. Its gas capture mechanism consists of three steps: physical adsorption: van der Waals forces temporarily adsorb onto the surface; chemical adsorption: oxygen, water vapor, carbon dioxide, etc., react with zirconium and vanadium to form stable solid compounds: O2 / CO / CO2 → oxides (ZrO2, VO2), N2 → nitrides (ZrN, VN), H2 → hydrides (ZrH2, VH2); diffusion: the surface compound layer thickens, and the gas diffuses into the internal lattice to form a solid solution for continuous absorption. For water vapor absorption, the highly active Ti, Zr, and V atoms of the getter attack the OH bonds of water molecules, decomposing them into hydrogen atoms (H) and oxygen atoms (O), generating TiO2 and ZrO2. Through this "activation-adsorption-diffusion" cycle, efficient maintenance of the vacuum environment is achieved. However, there are process challenges in coating the inner wall of the cap with getter. The internal space of the cap is small and is a typical "deep cavity structure", which makes it difficult for the inner wall of the cavity to be uniformly covered by the film. This results in uneven distribution of getter on the cap wall. At the same time, coating getter may contaminate the optical window at the top of the cap and reduce the laser output efficiency. Summary of the Invention

[0009] The purpose of this invention is to provide a laser TO packaging structure and packaging method thereon to solve the problems mentioned in the background art.

[0010] To achieve the above objectives, the technical solution adopted by the present invention is as follows: a laser TO packaging structure, including a tube socket, a tube cap disposed above the tube socket, and a plurality of pins vertically passing through the tube socket. A vertically arranged heat sink is disposed above the middle part of the tube socket. The heat sink and the tube socket are integrally formed. The side of the heat sink facing the center of the tube socket is a vertical plane. A thermoelectric cooler is mounted on the vertical plane of the heat sink. A substrate is disposed on the side of the thermoelectric cooler away from the heat sink. A laser chip and a thermistor are mounted on the substrate. The heat sink, thermoelectric cooler, substrate, laser chip, and thermistor are all disposed inside the tube cap. A window is provided at the upper end of the tube cap. A light window is provided on the window. The light window is a meta-lens or a lens. A vertically arranged first reference scale and a horizontally arranged second reference scale are provided on the vertical plane of the heat sink. A getter is provided on the inner sidewall of the tube cap.

[0011] Further optimization involves the heat sink having a semi-cylindrical or cuboid structure with a vertical plane approaching the center of the tube seat.

[0012] Further optimization involves sealing the tube cap with the tube seat, sealing the light window with the tube cap, and sealing the internal cavity of the tube cap with inert gas.

[0013] Further optimizations include a sealed connection between the tube cap and the tube seat, a sealed connection between the light window and the tube cap, and a sealed cavity inside the tube cap that is in a vacuum state.

[0014] Further optimization involves using a non-evaporable film-type getter.

[0015] Further optimization involves the optical window being a metalens with a microstructure column array arranged in its central region.

[0016] This invention also discloses a packaging method for a laser TO packaging structure, which, based on the aforementioned laser TO packaging structure, includes the following steps:

[0017] Step 1: Mount the thermistor. Use a pick-and-place machine to mount the thermistor onto the corresponding mounting area on the substrate.

[0018] Step 2: Mount the laser chip and use a eutectic bonding machine to bond the eutectic region of the laser chip and the substrate onto the eutectic bonding platform for eutectic bonding.

[0019] Step 3: Mount the thermoelectric cooler. Use a pick-and-place machine to mount the thermistor and laser chip onto the side of the thermoelectric cooler away from the heat sink.

[0020] Step 4: The thermoelectric cooler is mounted on the tube socket. The hot side of the thermoelectric cooler is mounted on the vertical plane of the heat sink on the tube socket using a pick-and-place machine. The position of the thermoelectric cooler is adjusted with reference to the first and second reference scales so that the emitted light from the laser chip is at the center of the optical window.

[0021] Step 5, wire bonding: The lead ends of the thermistor, laser chip and thermoelectric cooler are respectively wire bonded to the lead posts on the tube socket using conductive wire on a wire bonding machine to form an electrical interconnect;

[0022] Step 6, Getter preparation: In a vacuum environment, place getter on the inner wall of the cap.

[0023] Step 7, capping and activating the getter: The getter is activated by heating in the pre-capping heating zone of the capping equipment, and then the cap is welded to the pipe seat to complete the capping action.

[0024] Further optimization includes the following method for placing a getter inside the cap:

[0025] (1) Select sheet stainless steel sheet, and then plate one side of the stainless steel sheet with titanium zirconium vanadium or zirconium vanadium iron getter.

[0026] (2) Cut the stainless steel sheet to the required size according to the inner wall height and inner diameter of the cap;

[0027] (3) Roll up the cut stainless steel sheet to form a tube, with the side containing the getter facing inward. The diameter of the tube stainless steel sheet is greater than or equal to the inner diameter of the cap. Use clamp pliers to shrink the tube stainless steel sheet and then insert it into the inner wall of the cap. After releasing the clamp pliers, the tube stainless steel sheet uses the elasticity of the material to achieve a tight fit with the cap, forming a stable structure.

[0028] (4) The stainless steel sheet coated with getter is welded to the pipe cap by laser welding.

[0029] Further optimization is achieved by the following process for plating getter onto the stainless steel sheet:

[0030] a. Cleaning treatment: First, ultrasonically clean the stainless steel sheet, then rinse it with deionized water, and finally dry it with hot air.

[0031] b. Deoxidation / Activation: Argon plasma etching is performed on the stainless steel sheet after the decontamination treatment to remove the surface oxide layer and contaminants of the stainless steel sheet;

[0032] c. Vacuuming: Place the etched stainless steel sheet into the coating chamber, evacuate the vacuum, and then fill the coating chamber with argon gas to the preset working pressure.

[0033] d. Target pre-sputtering: Pre-sputter the coating layer with the target for 5–10 min to remove the oxide layer on the target surface;

[0034] e. Film deposition: Multiple layers of film are deposited sequentially from bottom to top on the surface of a stainless steel substrate, including a chromium underlayer, a titanium-zirconium-vanadium or zirconium-vanadium-iron main getter layer.

[0035] Beneficial effects: The laser TO packaging structure of the present invention, by setting a first reference scale and a second reference scale on the heat sink, enables the thermoelectric cooler and the substrate to have precise position reference during the mounting process, thereby achieving precise alignment of the laser chip and the optical window before the capping.

[0036] The thermoelectric cooler and the laser chip are directly connected through a substrate. Removing the heat sink allows the substrate to be directly bonded to the thermoelectric cooler, which can shorten the heat conduction path and facilitate precise temperature control and heat dissipation within the sealed cavity of the cap.

[0037] By adjusting the position of the thermoelectric cooler on the heat sink, the laser chip and the optical window can be aligned, thereby improving the beam pointing accuracy.

[0038] By placing a getter on the inner wall of the cap, residual oxygen and water vapor in the sealed cavity can be absorbed, maintaining a water-free and oxygen-free environment inside, avoiding oxidation and contamination of the laser chip end face, ensuring that there is no risk of contamination inside the sealed cavity, and preventing the generation of metal vapor that could affect the optical window.

[0039] This laser TO packaging structure enables precise temperature control within the packaging space, and provides a positional reference scale during chip mounting. The internal components operate stably and have a long service life. It effectively solves the problems of poor temperature regulation accuracy caused by long heat conduction paths and high thermal resistance in existing technologies, lack of reference positions for chip mounting during TO packaging, insufficient reliability due to residual moisture, oxygen, and carbon dioxide during long-term operation of the device, and the influence of residual gases on the spectrum. At the same time, it solves the technical problem that existing processes cannot deposit getter inside the cap. Attached Figure Description

[0040] Figure 1 This is a schematic diagram of the internal structure of the laser TO package structure disclosed in this invention;

[0041] Figure 2 This is an isometric structural diagram of the laser TO packaging structure disclosed in this invention;

[0042] Figure 3 This is a partial structural schematic diagram of the laser TO packaging structure disclosed in this invention;

[0043] Figure 4 This is a schematic diagram of the TO package structure of a laser with a metalens as the optical window disclosed in this invention.

[0044] Figure 5 This is a schematic diagram of the elliptic beam shaping of laser light by the meta-lens disclosed in this invention;

[0045] Figure 6 This is a simplified diagram showing the packaging method steps of the laser TO packaging structure disclosed in this invention;

[0046] Figure 7 This is a simplified diagram of the steps of the method for plating getter inside the pipe cap disclosed in this invention;

[0047] Figure 8 This is a flow chart of the preparation process of the getter plating inside the pipe cap disclosed in this invention.

[0048] Reference numerals: 1-tube socket, 2-tube cap, 21-window, 3-pin, 4-heat sink, 41-first reference scale, 42-second reference scale, 5-thermoelectric cooler, 6-substrate, 7-laser chip, 8-thermometer, 9-optical window, 10-lead post. Detailed Implementation

[0049] The following are specific embodiments of the present invention, which are described in conjunction with the accompanying drawings. However, the present invention is not limited to these embodiments.

[0050] like Figure 1-3 As shown, this application discloses a laser TO package structure, including a tube base 1, a tube cap 2 disposed above the tube base 1, and several pins 3 vertically passing through the tube base 1. A vertically arranged heat sink 4 is disposed above the middle of the tube base 1. The heat sink 4 and the tube base 1 are integrally formed. The side of the heat sink 4 facing the center of the tube base 1 is a vertical plane. A thermoelectric cooler 5 is mounted on the vertical plane of the heat sink 4. A substrate 6 is disposed on the side of the thermoelectric cooler 5 away from the heat sink 4. A laser chip 7 and a thermistor 8 are mounted on the substrate 6. The heat sink 4, thermoelectric cooler 5, substrate 6, laser chip 7 and thermistor 8 are all disposed inside the tube cap 2. A window 21 is provided at the upper end of the tube cap 2. A light window 9 is provided on the window 21. The light window 9 is a super lens or a lens. A vertically arranged first reference scale 41 and a horizontally arranged second reference scale 42 are provided on the vertical plane of the heat sink 4. A getter is provided on the inner sidewall of the tube cap 2.

[0051] In this application, the laser TO package structure is applied in the laser field. It features a robust structure, excellent heat dissipation, and low cost, representing a miniaturized and highly reliable semiconductor device package structure. It includes a socket 1, a cap 2, leads 3, a heat sink 4, a thermoelectric cooler 5, a substrate 6, a laser chip 7, and a thermistor 8. The socket 1 serves as the basic support structure for the package, supporting the heat sink 4 and the thermoelectric cooler 5, substrate 6, laser chip 7, and thermistor 8 mounted on it. It also houses the leads 3 and serves as a heat conductor and dissipator. The cap 2 connects to the socket 1 to form a closed cavity, isolating it from external gases, moisture, dust, and mechanical impacts. The leads 3 provide electrical connections between the components within the closed cavity and external circuitry. These connections are achieved through lead posts 10 located above the socket 1, transmitting laser drive current, control signals from the thermoelectric cooler 5, and temperature feedback signals from the thermistor 8. The heat sink 4 acts as a highly efficient heat-conducting medium, rapidly dissipating the heat generated by the laser chip 7 to the external environment, increasing the heat dissipation area and reducing thermal resistance. The thermoelectric cooler 5, based on the Peltier effect, controls cooling or heating by the direction of current, enabling precise temperature regulation of the laser chip 7. The substrate 6 is used for mounting the laser chip 7 and the thermistor 8, as well as providing electrical interconnection and mechanical support. The laser chip 7, as a light-emitting element, outputs laser light of a specific wavelength. The thermistor 8, located on the surface of the substrate 6 and on the same side as the light-emitting end of the laser chip 7, is used to sense the temperature of the laser chip 7 in real time and accurately, converting temperature changes into electrical signals, thus forming a temperature monitoring and closed-loop control circuit to ensure stable laser operation. The optical window 9 is used for the transmission of the laser light emitted by the laser chip 7, achieving efficient laser transmission and shaping, and optimizing laser output characteristics.

[0052] In this application, the side of the heat sink 4 facing the center of the tube seat 1 is a vertical plane, which facilitates the installation of the thermoelectric cooler 5 and increases the contact area with the thermoelectric cooler 5, thereby improving heat dissipation capacity. The thermoelectric cooler 5 can be adjusted horizontally and vertically relative to the heat sink 4. The position of the thermoelectric cooler 5 can be adjusted according to manufacturing requirements, so that there is a reference scale when the thermoelectric cooler 5 is mounted, thereby achieving precise alignment between the laser chip 7 and the optical window 9. The optical window 9 can be set as a planar optical window, a spherical or aspherical optical window, a curved optical window, or a meta-lens optical window as required. The heat sink 4 has a vertically arranged first reference scale 41 and a horizontally arranged second reference scale 42 on its vertical plane. The first reference scale 41 and the second reference scale 42 serve as references for the position of the thermoelectric cooler 5 and the substrate 6 mounted on it. That is, before sealing, the position of the thermoelectric cooler 5 and the substrate 6 can be precisely adjusted, thereby achieving precise adjustment of the position of the laser chip 7, and finally achieving position adjustment of the laser chip 7 relative to the optical window 9, including vertical and horizontal position adjustment, and in conjunction with different optical windows 9, achieving adjustment of the emitted light pattern. During the fabrication of the laser TO package structure, based on the shape of the emitted beam, before the product is cured, the laser chip 7, substrate 6, and thermoelectric cooler 5 can be moved as a whole on the heat sink 4, so that the light outlet of the laser chip 7 is positioned at the focal point of the optical window 9. This fixes the positions of the thermoelectric cooler 5, substrate 6, and laser chip 7, thus determining the specific position of the thermoelectric cooler 5 on the graduated heat sink 4 in this patent. The first reference scale 41 and the second reference scale 42 serve as reference standards for the die bonding or eutectic bonding process of this type of product, eliminating the need for redesign as in traditional processes. If the beam pattern needs to be precisely centered on the emitting lens, the left and right positions can be adjusted, and the front and back positions can be adjusted according to the different focal lengths of the lens in the optical window 9. This allows the thermoelectric cooler 5, substrate 6, and laser chip 7 to be positioned on the heat sink 4 with reference to the first reference scale 41 and the second reference scale 42 according to different optical windows 9 and beam pattern requirements.

[0053] In this application, the first reference scale 41 and the second reference scale 42 can be implemented in various ways, including etching and laser scribing. The accuracy can be specified according to the target accuracy requirements of the product. The laser chip 7 is fixed to the substrate 6 by eutectic bonding. The cold side of the substrate 6 and the thermoelectric cooler 5 are cured with silver paste by baking. The hot side of the thermoelectric cooler 5 and the heat sink 4 are cured with silver paste by baking. The hot side of the thermoelectric cooler 5 may not be in contact with the scale parts (first reference scale 41 and second reference scale 42). The extension lines of the scale lines of the first reference scale 41 and the second reference scale 42 can be used as position references or they can be in contact with the scale lines. Because the scale lines are coated with silver paste, and the silver paste fills the scale microgrooves, the impact on overall heat dissipation is minimal.

[0054] In this application, the optical window 9 is a metalens. Its principle is as follows: as a branch application of metasurfaces, metalenses achieve lens functionality by designing the phase distribution of metaatoms as the focusing phase of a diffraction lens. Metasurfaces can arbitrarily modulate the amplitude, polarization, phase, and orbital angular momentum of light, and metalenses have the advantages of multifunctionality and thinness. The phase shift φ(x,y,λ) on the lens surface needs to satisfy the metalens construction formula, which is:

[0055] ,

[0056] Where (x,y) are the coordinates of each nanounit, φ(x,y,λ) is the phase difference of the nanounit relative to the center position of the metalens, λ is the incident wavelength, and f is the designed focal length.

[0057] In this application, the heat sink 4 and the tube base 1 are integrally formed, resulting in high structural strength, eliminating contact thermal resistance, and improving thermal coupling efficiency. The laser chip 7 and thermistor 8 are directly mounted on the thermoelectric cooler 5 via the substrate 6, effectively shortening the heat conduction path and facilitating temperature control and heat dissipation.

[0058] In this application, a getter is provided on the inner wall of the cap 2. The getter is activated by heating (usually 250-450℃ for several minutes). By activating the getter, it can absorb residual oxygen, water vapor, carbon dioxide and other substances in the sealed cavity of the cap 2, maintain the water-free and oxygen-free environment inside the cavity, and avoid oxidation and contamination of the laser chip 7 end face, which would cause performance degradation. At the same time, there is no risk of internal contamination of the cavity and no metal vapor will be generated to affect the optical window. ([1] Song Yi, Feng Yan, Cheng Yongjun, et al. Research status and progress of non-evaporative getter materials [J]. Chinese Journal of Nonferrous Metals, 2021, 31 (08): 2160-2170). At the same time, the getter can also be placed on the tube seat 1.

[0059] like Figure 3 As shown, in one embodiment of this application, the heat sink 4 is any one of a semi-cylindrical structure, a cuboid structure, and a frustum structure, having a vertical plane approaching the center of the tube seat 1. In this embodiment, the heat sink 4 is a semi-cylindrical or cuboid structure, which has high structural strength, ensuring strong support for the thermoelectric cooler 5, and the vertical plane is the mounting surface of the thermoelectric cooler 5. The arc surface of the semi-cylindrical structure can contact the inner wall of the tube cap 2, ensuring the installation firmness of the tube cap 2, and the arc surface increases the surface area of ​​the heat sink 4, improving heat dissipation capacity. Furthermore, the semi-cylindrical heat sink 4 has a large volume, is integrally formed with the bottom tube seat 1, has a large contact area, and is easy to conduct heat. However, the structure of the heat sink 4 is not limited to a semi-cylindrical shape; it can also be a cuboid structure, a frustum structure, or other shapes.

[0060] In another embodiment of this application, the cap 2 is sealed to the base 1, and the optical window 9 is sealed to the cap 2. The internal cavity of the cap 2 is a sealed cavity filled with inert gas. The sealed connection between the cap 2 and the base 1 and the optical window 9 achieves a sealed structure for the internal cavity of the cap 2, which is filled with inert gas. This provides a high-purity, high-stability, and low-risk working environment for the thermoelectric cooler 5, the substrate 6, the laser chip 7, and the thermistor 8. This environment can isolate oxidation and corrosion, extend the service life of each component, suppress thermal disturbances, improve temperature control accuracy, and provide insulation and arc prevention, ensuring the reliability of the internal chips and circuits. It can also reduce scattering and contamination, maintaining laser transmission efficiency.

[0061] Unlike the above embodiments, in another embodiment of this application, the cap 2 is sealed to the base 1, and the optical window 9 is sealed to the cap 2. The internal cavity of the cap 2 is a sealed cavity, which is in a vacuum state. A sealed structure is formed between the cap 2 and the base 1, and the internal cavity is evacuated to create a vacuum state, which can create an extreme environment free from gas interference, isolate oxidation, corrosion and pollution, extend the service life of various components, eliminate gas convection and heat conduction, improve temperature control accuracy, and have ultra-high insulation strength, eliminating electric arc and discharge. This ensures that no gas molecules scatter the laser in the sealed cavity, and also prevents the adsorption of laser light, thus maximizing laser transmission efficiency.

[0062] Based on the above scheme, the getter is a non-evaporable thin film getter, and the composition is titanium zirconium vanadium alloy, with a titanium atomic fraction of 30%, a zirconium atomic fraction of 30%, and a vanadium atomic fraction of about 40%. The non-evaporable thin film getter retains its own morphology after activation and relies on its surface and interior to continuously react with the gas to get gas. The morphology remains unchanged after activation and there is no pollution. The titanium zirconium vanadium alloy thin film is a non-evaporable getter film with both good gas-getting performance and the lowest activation temperature ([2] Zhang Bo, Wang Yong, Wei Wei, et al. Deposition of TiZrV thin film on the inner wall of pipe by DC magnetron sputtering [J]. High Power Laser and Particle Beam, 2010, 22 (09):2124-2128).

[0063] like Figure 4 and Figure 5As shown, based on the above scheme, the optical window 9 is a metalens with a microstructure column array in its central region. The metalens reduces thickness and weight by 50%-90% compared to traditional lenses, and its phase center almost perfectly coincides with the physical center, eliminating the center deviation of traditional lenses. It can directly shape elliptical or divergent beams into circular, collimated, or focused beams of light in a specific mode, significantly improving beam pointing accuracy. The microstructure column array is located in the central effective optical region of the metalens to achieve high-uniformity phase modulation and focusing / collimation of the incident light. By precisely controlling the diameter, height, duty cycle, and orientation angle of the nanopillars at different radial / azimuth positions, a phase abrupt change matching the target phase distribution (such as spherical wave phase) is formed on the surface of the metalens, thereby achieving the optical functions of a traditional thick lens in an ultra-thin thickness. The microstructure nanopillars are located at the center of the metalens for beam control, and the annular region at the edge of the optical window 9 serves as a substrate for bonding or laser welding to the cap 2.

[0064] like Figure 2 As shown, in another embodiment of this application, the tube socket 1 is provided with a plurality of lead posts 10 for connecting to the thermoelectric cooler 5, the substrate 6, and the thermistor 8. The two electrodes of the thermoelectric cooler 5 are interconnected with the lead posts 10 by gold wires, the substrate 6 is connected to the lead posts 10 by lead wires, and the laser chip 7 is electrically connected to the substrate 6 by lead bonding.

[0065] like Figure 6 As shown, the present invention also discloses a packaging method for a laser TO packaging structure, which, based on the above-mentioned laser TO packaging structure, includes the following steps:

[0066] Step 1: Mount the thermistor 8. The thermistor 8 is mounted on the thermistor mounting area of ​​the substrate 6 and close to the light-emitting end of the laser chip 7 using a pick-and-place machine with solder (solder paste, silver paste, gold-tin alloy, indium, etc.). After heating (heating temperature depends on the solder) and curing, the thermistor 8 and the substrate 6 are bonded together to form an integral unit.

[0067] Step 2: Mount the laser chip 7. Use a eutectic bonding machine to bond the laser chip 7 and the eutectic region of the substrate 6 to the eutectic bonding stage for eutectic bonding. The back of the laser chip 7 and the eutectic region of the substrate 6 are both plated with eutectic solder. The curing temperature depends on the solder. The mounting accuracy is controlled within ±10μm.

[0068] Step 3: Mount the thermoelectric cooler 5. Using a pick-and-place machine, mount the substrate 6, on which the thermistor 8 and laser chip 7 are mounted, onto the side (cold side) of the thermoelectric cooler 5 away from the heat sink 4 using solder (solder paste, silver paste, gold-tin alloy, etc.). The maximum temperature difference between the cold and hot sides of the thermoelectric cooler 5 is 70°C. After curing, the thermoelectric cooler 5, substrate 6, thermistor 8 and laser chip 7 are integrated.

[0069] Step 4: The thermoelectric cooler 5 is mounted on the tube socket 1. The hot side of the thermoelectric cooler 5 is mounted on the vertical plane of the heat sink 4 on the tube socket 1 using a pick-and-place machine with solder (solder paste, silver paste, gold-tin alloy, etc.). The position of the thermoelectric cooler 5 is adjusted with reference to the first reference scale 41 and the second reference scale 42 so that the emitted light of the laser chip 7 is at the center of the optical window 9.

[0070] Step 5, wire bonding: The lead ends of the thermistor 8, laser chip 7 and thermoelectric cooler 5 are respectively wire bonded to the lead posts 10 on the tube socket 1 using conductive wire on a wire bonding machine to form an electrical interconnect.

[0071] Step 6, Getter preparation: In a vacuum environment, a getter is placed on the inner wall of the cap 2;

[0072] Step 7, capping and activating getter: Heat and activate the getter in the pre-capping heating zone of the capping equipment, and then weld the cap 2 to the pipe seat 1 to complete the capping action.

[0073] like Figure 7 and Figure 8 As shown, based on the above-described encapsulation method, the present invention also discloses a method for placing a getter inside the cap 2, comprising:

[0074] (1) Select sheet stainless steel, preferably austenitic 316L. The steel sheet has a certain elasticity. Then, the stainless steel sheet is plated with titanium zirconium vanadium or zirconium vanadium iron getter on one side.

[0075] (2) Cut the stainless steel sheet to the required size according to the inner wall height and inner diameter of the cap 2;

[0076] (3) Roll up the cut stainless steel sheet to form a tube, with the side containing the getter facing inward. The diameter of the tube stainless steel sheet is greater than or equal to the inner diameter of the cap 2. Connect the tube stainless steel sheet end to end and then embed it into the inner wall of the cap 2. The tube stainless steel sheet can be connected by a snap-fit ​​or by using clamps to fix the ends together. After shrinking the tube stainless steel sheet with clamps, embed it into the inner wall of the cap 2. After releasing the clamps, the tube stainless steel sheet is secured to the cap 2 by the elasticity of the material, forming a stable structure.

[0077] (4) The stainless steel sheet coated with getter is welded to the cap 2 by laser welding.

[0078] In this invention, the process of plating getter onto the stainless steel sheet is as follows:

[0079] a. Cleaning treatment: First, use organic solvents such as alcohol, acetone, and ether to ultrasonically clean the stainless steel sheet, then clean it with deionized water, and finally dry it with hot air.

[0080] b. Deoxidation / activation: Argon plasma etching is performed on the stainless steel sheet after decontamination. The etching time is 10–30s and the etching power is 50–100W to remove the surface oxide layer and contaminants of the stainless steel sheet and improve the adhesion of the coating layer of the stainless steel sheet.

[0081] c. Vacuuming: Place the etched stainless steel sheet into the coating chamber and evacuate to a background vacuum of ≤5×10⁻⁻⁻⁴. 4 Pa, then fill the coating chamber with argon gas to the preset working pressure;

[0082] d. Target pre-sputtering: Pre-sputter the coating layer with the target for 5–10 min to remove the oxide layer on the target surface;

[0083] e. Film deposition: Multiple layers of film are deposited sequentially from bottom to top on the surface of a stainless steel substrate, including a chromium underlayer, a titanium-zirconium-vanadium or zirconium-vanadium-iron main getter layer.

[0084] The deposition parameters for each film layer are as follows:

[0085] (1) Chromium substrate: sputtering power 50–100W, deposition time 5–10min, film thickness 50–100 nm;

[0086] (2) Titanium-zirconium-vanadium main gas-gathering layer: sputtering power 100–200W, deposition time 20–40min, film thickness 300–800nm.

[0087] After activation, the getter forms a sponge-like porous layered structure, increasing its surface area. The surface atoms gain energy to rearrange themselves, exposing fresh, active metal surfaces and gaining gettering ability. This process must be carried out under high vacuum.

[0088] The activation process is as follows: Before TO encapsulation, the tube cap 2 with getter is placed in a vacuum oven. The oven is evacuated to ≤1×10⁻³ Pa for pre-activation at 100–150℃ for 2–4 hours to remove adsorbed gas from the surface of the getter on the inner wall of the tube cap 2. Then, the temperature is raised to the activation temperature and the activation time is maintained at 2 hours while keeping the vacuum environment. Within 30 minutes after the getter is activated, the TO tube cap 2 and the tube seat 1 are sealed by resistance welding.

[0089] The specific embodiments described herein are merely illustrative of the spirit of the invention. Those skilled in the art to which this invention pertains may make various modifications or additions to the described specific embodiments or use similar methods to substitute them, without departing from the spirit of the invention or exceeding the scope defined by the appended claims.

Claims

1. A laser TO package structure, comprising a socket, a cap disposed above the socket, and a plurality of pins vertically extending through the socket, characterized in that, A vertically positioned heat sink is located above the center of the tube base. The heat sink and the tube base are integrally formed. The side of the heat sink facing the center of the tube base is a vertical plane. A thermoelectric cooler is mounted on the vertical plane of the heat sink. A substrate is located on the side of the thermoelectric cooler away from the heat sink. A laser chip and a thermistor are mounted on the substrate. The heat sink, thermoelectric cooler, substrate, laser chip, and thermistor are all located inside the tube cap. A window is located at the top of the tube cap. A light window, which is a superlens or a lens, is provided on the window. A vertically positioned first reference scale and a horizontally positioned second reference scale are provided on the vertical plane of the heat sink. A getter is provided on the inner wall of the tube cap.

2. The laser TO packaging structure according to claim 1, characterized in that, The heat sink can be any one of a semi-cylindrical structure, a cuboid structure, or a frustum structure, and has a vertical plane facing the center of the tube seat.

3. The laser TO packaging structure according to claim 1, characterized in that, The cap is sealed to the tube seat, the light window is sealed to the cap, and the internal cavity of the cap is a sealed cavity filled with inert gas.

4. The laser TO packaging structure according to claim 1, characterized in that, The cap is sealed to the base, the light window is sealed to the cap, and the internal cavity of the cap is a sealed cavity with a vacuum inside.

5. The laser TO packaging structure according to claim 1, characterized in that, The getter is a non-evaporable film getter.

6. The laser TO packaging structure according to claim 1, characterized in that, The optical window is a meta-lens with a microstructure column array arranged in its central region.

7. A packaging method for a laser TO package structure, characterized in that, Based on the laser TO packaging structure according to any one of claims 1-6, the following steps are included: Step 1: Mount the thermistor. Use a pick-and-place machine to mount the thermistor onto the corresponding mounting area on the substrate. Step 2: Mount the laser chip and use a eutectic bonding machine to bond the eutectic region of the laser chip and the substrate onto the eutectic bonding platform for eutectic bonding. Step 3: Mount the thermoelectric cooler. Use a pick-and-place machine to mount the thermistor and laser chip onto the side of the thermoelectric cooler away from the heat sink. Step 4: The thermoelectric cooler is mounted on the tube socket. The hot side of the thermoelectric cooler is mounted on the vertical plane of the heat sink on the tube socket using a pick-and-place machine. The position of the thermoelectric cooler is adjusted with reference to the first and second reference scales so that the emitted light from the laser chip is at the center of the optical window. Step 5, wire bonding: The lead ends of the thermistor, laser chip and thermoelectric cooler are respectively wire bonded to the lead posts on the tube socket using conductive wire on a wire bonding machine to form an electrical interconnect; Step 6, Getter preparation: In a vacuum environment, place getter on the inner wall of the cap. Step 7, capping and activating the getter: The getter is activated by heating in the pre-capping heating zone of the capping equipment, and then the cap is welded to the pipe seat to complete the capping action.

8. The packaging method for the laser TO packaging structure according to claim 7, characterized in that, The method for placing a getter inside the cap includes: (1) Select sheet stainless steel sheet, and then plate one side of the stainless steel sheet with titanium zirconium vanadium or zirconium vanadium iron getter. (2) Cut the stainless steel sheet to the required size according to the inner wall height and inner diameter of the cap; (3) Roll up the cut stainless steel sheet to form a tube, with the side containing the getter facing inward. The diameter of the tube stainless steel sheet is greater than or equal to the inner diameter of the cap. Use clamp pliers to shrink the tube stainless steel sheet and then insert it into the inner wall of the cap. After releasing the clamp pliers, the tube stainless steel sheet uses the elasticity of the material to achieve a tight fit with the cap, forming a stable structure. (4) The stainless steel sheet coated with getter is welded to the pipe cap by laser welding.

9. The packaging method for the laser TO packaging structure according to claim 8, characterized in that, The process for plating the stainless steel sheet with getter is as follows: a. Cleaning treatment: First, ultrasonically clean the stainless steel sheet, then rinse it with deionized water, and finally dry it with hot air. b. Deoxidation / Activation: Argon plasma etching is performed on the stainless steel sheet after the decontamination treatment to remove the surface oxide layer and contaminants of the stainless steel sheet; c. Vacuuming: Place the etched stainless steel sheet into the coating chamber, evacuate the vacuum, and then fill the coating chamber with argon gas to the preset working pressure. d. Target pre-sputtering: Pre-sputter the coating layer with the target for 5–10 min to remove the oxide layer on the target surface; e. Film deposition: Multiple layers of film are deposited sequentially from bottom to top on the surface of a stainless steel substrate, including a chromium underlayer, a titanium-zirconium-vanadium or zirconium-vanadium-iron main getter layer.

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