An electroforming device and method for improving the thickness uniformity of a micro-injection mold

Abstract

The present invention provides an electroforming device and method for improving the thickness uniformity of a micro-injection mold. The device includes an electroforming module, an electroforming solution temperature control module, and a cathode rotation control module. The electroforming module includes an electroforming tank and a cathode fixture. The electroforming tank is filled with an electroforming solution and an anode corresponding to the cathode. The cathode fixture is provided with a side sealing liquid groove, and the side sealing liquid groove is used to suppress the edge effect of the cathode of the casting layer. An impact liquid port is arranged in the electroforming tank, and the impact liquid port is aligned with the cathode to make the electroforming solution impact the cathode. In the present invention, under the combined action of the near-cathode insulating shielding baffle and the fixture with side liquid sealing, high-thickness uniformity deposition of the casting layer can be achieved, and the liquid disturbance on the surface of the casting layer can be improved under the action of oblique liquid impact and cathode rotation. By using the device and method provided by the present invention, a micro-injection nickel mold with high thickness uniformity, high replication accuracy, no pore defects in the micro-structure, and a smooth casting layer surface without bubbles can be obtained.

Description

Technical Field

[0001] The present invention relates to the field of microfabrication technology, and particularly to an electroforming device and method for improving the thickness uniformity of a micro-injection mold. Background Art

[0002] With the increasing demand for microfluidic chips, micro-injection molding technology has increasingly appeared in micro-nano science and technology forums and major commercial exhibitions, indicating its broad market prospects. Micro-electroforming is widely used in the production of micro-injection molds because of its simple operation, high replication accuracy, no cutting force, tool wear and the influence of heat energy on the workpiece surface. However, electroforming technology also has some inherent problems. For example, the concentration of the electric field at the edge of the electroformed layer makes the thickness of the middle area of the electroformed layer inconsistent with that of the edge. Seriously, "edge tumors" will form at the edge of the electroformed layer, resulting in abnormal electroforming.

[0003] Regarding this problem, many solutions have been proposed currently. The more common ones include optimizing process parameters, auxiliary cathodes and anodes, insulating shielding baffles, ultrasonic and megasonic, pulse reverse current, etc. There are many factors affecting the non-uniformity of the electroformed layer. Among them, the non-uniform distribution of the electric field on the cathode surface is the most direct reason. The insulating shielding baffle is often used to improve the thickness uniformity of the electroformed layer because of its characteristic of optimizing the electric field distribution. Ma Xin et al. from Central South University improved the uniformity of the 1.5-mm-thick electroformed layer from 33% to 87% by optimizing the size of the shielding baffle (Plating & Finishing, 2014, 34(05): 8-11). The team of Ming Pingmei from Henan Polytechnic University obtained a uniformity of 91.5% for the electroformed layer with a thickness of 75 μm by using a loop-shaped shielding baffle (Acta Armamentarii, 2016, 37(6): 7).

[0004] The currently adopted shielding baffle scheme is not sufficient to take into account both thickness and uniformity at the same time. The adoption of the shielding baffle, especially when the distance between the shielding baffle and the cathode is too close, will seriously affect the disturbance of the liquid at the edge of the electroformed layer, resulting in difficulties in discharging hydrogen on the surface of the electroformed layer and defects such as bubble pitting. In addition, to give full play to the shielding ability of the shielding baffle, it is necessary to make the electric field lines pass through the openings of the shielding baffle as much as possible. Summary of the Invention

[0005] The purpose of the present invention is: aiming at the deficiencies in the above background art, to provide a scheme combining liquid sealing on the side of the cathode fixture and a shielding baffle to optimize the electric field distribution of the entire electroformed layer, improve the thickness uniformity of the electroformed layer, and at the same time adopt a combination of inclined liquid flushing and cathode rotation to enhance liquid disturbance, eliminate the bubbles precipitated on the surface of the electroformed layer during the electroforming process, and improve the micro-structure replication quality.

[0006] To achieve the above purpose, the present invention provides an electroforming device for improving the thickness uniformity of a micro-injection mold, including an electroforming module, an electroforming solution temperature control module, and a cathode rotation control module;

[0007] The electroforming module includes an electroforming tank and a cathode fixture. The cathode fixture is used to fix the cathode. The electroforming tank is filled with electroforming solution and an anode corresponding to the cathode. The cathode fixture is provided with a side liquid-sealing groove and a shielding baffle. The side liquid-sealing groove is used to suppress the edge effect of the cathode of the cast layer. An impact liquid port is arranged in the electroforming tank. The impact liquid port is aligned with the through hole of the shielding baffle and the cathode, and the electroforming solution impacts the cathode.

[0008] The cathode rotation control module is used to control the rotation of the cathode fixture.

[0009] The electroforming solution temperature control module is used to control the temperature of the electroforming solution in the electroforming tank.

[0010] Furthermore, the impact liquid port is inclined relative to the cathode for inclined liquid impact.

[0011] Furthermore, the cathode fixture includes an upper cathode plate and a lower cathode plate. The cathode is located between the upper cathode plate and the lower cathode plate. At the same time, a conductive ring, a support gasket, a micro spring, and an O-ring are also arranged. The conductive ring contacts the cathode to supply power to the cathode. The micro spring is arranged in the first annular groove of the lower cathode plate and contacts the conductive ring to press the conductive ring and the cathode tightly. The support gasket is located between the cathode and the upper cathode plate to prevent the cathode from breaking during extrusion. A through hole is opened in the center of the lower cathode plate. The O-ring is arranged in the second annular groove of the lower cathode plate and contacts the lower surface of the cathode to form a seal. The O-ring, the cathode, and the lower cathode plate form a side liquid-sealing groove.

[0012] Furthermore, the upper cathode plate is also provided with a wire hole, and the wire connected to the conductive ring is led out from the wire hole.

[0013] Furthermore, the shielding baffle includes a shielding baffle fixing part and a shielding baffle dismounting and assembling part. The shielding baffle fixing part is installed in the electroforming tank by bolts. The shielding baffle dismounting and assembling part is nested and matched with the shielding baffle fixing part. The shielding baffle fixing part and the shielding baffle dismounting and assembling part are both provided with through holes.

[0014] Furthermore, the installation distance of the shielding baffle fixing part can be adjusted, and the shielding baffle dismounting and assembling part has various specifications.

[0015] Furthermore, the cathode rotation control module includes a rotating shaft. The rotating shaft is rotatably arranged on a support plate, and both ends of the rotating shaft are respectively connected to the upper cathode plate of the cathode fixture and a coupling. The coupling is connected to a stepping motor.

[0016] A conductive slip ring is provided on the rotating shaft, and the conductive slip ring is used for connecting the circuit of the cathode fixture;

[0017] The support plate is connected to a support plate driving mechanism, and the support plate driving mechanism is used to drive the support plate to move so that the cathode fixture is docked with or separated from the electroforming tank.

[0018] Furthermore, an electroforming solution circulation and filtration module is also provided. The electroforming solution circulation and filtration module includes a flange adapter, a circulation pipe, a magnetic pump, and a filter. The flange adapter is used for connecting the circulation pipe to the flushing port, and the magnetic pump and the filter are both arranged on the circulation pipe.

[0019] Furthermore, an electroforming solution temperature control module is also provided. The electroforming solution temperature control module includes a water bath, a U-shaped heating pipe, a relay, a temperature sensor, and a temperature controller. The U-shaped heating pipe and the temperature sensor are evenly arranged in the water bath. The temperature controller is electrically connected to the temperature sensor for receiving the signal of the temperature sensor. The relay is used to control the heating of the U-shaped heating pipe, and the electroforming tank is fixed on the water bath.

[0020] Furthermore, a pH monitoring module, a heat dissipation module, a cleaning module, and a power supply module are also included;

[0021] The pH monitoring module includes a pH detector, a composite electrode connector, and a composite electrode. The composite electrode is installed in the composite electrode connector. Both ends of the composite electrode connector are connected to the circulation pipe, and the composite electrode is electrically connected to the pH detector;

[0022] The heat dissipation module includes several heat dissipation fans, and the heat dissipation fans are used for heat dissipation and temperature reduction;

[0023] The cleaning module includes an ultrasonic cleaner, and the ultrasonic cleaner is used for ultrasonic cleaning of the cathode and the products;

[0024] The power supply module includes a power switch panel, and the power switch panel is used for power switch control.

[0025] The present invention also provides an electroforming method for improving the thickness uniformity of a micro-injection mold, including a photolithography step and an electroforming step. The photolithography step includes fabricating a mask plate, spin-coating a photoresist on a silicon substrate, exposure, development, deep plasma etching, and cleaning to form a silicon wafer with microstructures. Conductivization treatment is performed on the silicon wafer with microstructures, specifically by first depositing a 5 - 10 nm layer of Cr or Ti as an adhesion layer in a magnetron sputtering instrument or an evaporation coater, and then depositing a 30 - 50 nm layer of Au or Pt as a conductive layer to form a cathode;

[0026] The electroforming step includes installing the treated cathode in a cathode fixture, turning on a water bath heating switch, setting the water bath temperature to 45°C on a temperature controller, turning on a power switch to set power parameters, replacing a flushing port as needed, adjusting the distance between the shielding baffle fixing and the lower cathode plate and the size of the shielding baffle disassembly and assembly parts, dripping a wetting agent on the surface of the cathode installed in the cathode fixture, connecting a cathode power cord, then adding an electroforming liquid so that the electroforming liquid completely submerges the cathode fixture, turning on a circulation filtration module, and turning on a cathode rotation controller to control cathode rotation;

[0027] After running for a period of time, turn on the power switch to energize the cathode and anode, and finally close the upper cover of the electroforming tank and the water bath tank and wait for the electroforming to end. Remove the cathode fixture and take out the casting layer and the cathode as a whole, clean them in an ultrasonic cleaner, and then use a wire cutting machine to remove the 2mm wide unstructured part on the edge, and then place the casting layer and the cathode in a NaOH solution to dissolve and separate them. After separation, put the casting layer into the ultrasonic cleaner again for cleaning, and finally blow dry the surface with nitrogen.

[0028] The above scheme of the present invention has the following beneficial effects:

[0029] The electroforming scheme for improving the thickness uniformity of a micro injection mold provided by the present invention adopts a side liquid sealing fixture to suppress the cathode edge electric field, and a scheme combining oblique liquid flushing with cathode rotation to enhance liquid disturbance. Under the joint action of a near-cathode insulating shielding baffle and a fixture with side liquid sealing, high uniformity deposition of the casting layer can be achieved. Under the action of oblique liquid flushing and cathode rotation, a high-thickness uniformity injection nickel mold with high replication accuracy, no pore defects in the microstructure, and a smooth casting layer surface without bubbles can be obtained.

[0030] Other beneficial effects of the present invention will be described in detail in the subsequent specific implementation section. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a three-dimensional schematic diagram of the overall structure of the present invention;

[0032] Figure 2 It is a top view of the overall structure of the present invention;

[0033] Figure 3 It is a rear view of the overall structure of the present invention;

[0034] Figure 4 is a schematic diagram of a cathode fixture of the present invention;

[0035] Figure 5 It is a schematic diagram of the support plate driving mechanism of the present invention;

[0036] Figure 6 This is a sample diagram of a mold prepared using the present invention.

[0037]

Description of the Attached Drawing Reference Signs

[0038] 1 - Electroforming tank; 2 - Cathode fixture; 3 - Upper cathode plate; 4 - Lower cathode plate; 5 - Cathode; 6 - Conductive ring; 7 - Support gasket; 8 - Micro spring; 9 - O-ring; 10 - Wire hole; 11 - Flushing port; 12 - Anode; 13 - Shielding baffle; 14 - Shielding baffle fixing part; 15 - Shielding baffle disassembly and assembly part; 16 - Coaxial positioning part; 17 - Flange adapter; 18 - Circulation pipe; 19 - Magnetic pump; 20 - Filter; 21 - Water bath tank; 22 - U-shaped heating pipe; 23 - Relay; 24 - Temperature sensor; 25 - Temperature controller; 26 - Rotating shaft; 27 - Support plate; 28 - Coupling; 29 - Stepper motor; 30 - Outer shell; 31 - Cathode rotation controller; 32 - Driver; 33 - Bearing support; 34 - Conductive slip ring; 35 - Support frame; 36 - First hinge part; 37 - Micro hydraulic support rod; 38 - Second hinge part; 39 - Third hinge part; 40 - pH detector; 41 - Composite electrode connecting part; 42 - Composite electrode; 43 - Cooling fan; 44 - Ultrasonic cleaner; 45 - Power switch panel. Detailed Embodiment

[0039] To make the technical problems, technical solutions and advantages to be solved by the present invention clearer, the following will be described in detail with reference to the attached drawings and specific embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention. In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0040] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the attached drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to the present invention. In addition, the terms "first", "second", "third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0041] In the description of the present invention, it should be noted that unless otherwise clearly specified and defined, the terms "installation", "connection", and "coupling" should be understood in a broad sense. For example, it can be a locking connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0042] As Figures 1 - 3 shown, an electroforming device for improving the thickness uniformity of a micro-injection mold according to an embodiment of the present invention includes an electroforming module, an electroforming solution temperature control module, a cathode rotation control module, a pH monitoring module, an electroforming solution circulation and filtration module, a heat dissipation module, a power supply module, a cleaning module, etc.

[0043] The electroforming module includes an electroforming tank 1 and a cathode fixture 2. At the same time, as Figure 4 shown, the cathode fixture 2 includes an upper cathode plate 3 and a lower cathode plate 4. There is a gap between the upper cathode plate 3 and the lower cathode plate 4 for clamping the cathode 5. To ensure electroforming operation, a conductive ring 6, a support gasket 7, a micro spring 8, an O-ring 9, etc. are also arranged at the gap. Specifically, the conductive ring 6 contacts the cathode 5 to supply power to the cathode 5. The micro spring 8 is arranged in the first annular groove of the lower cathode plate 4 and contacts the conductive ring 6 to press the conductive ring 6 and the cathode 5 tightly to ensure close contact. The support gasket 7 is located between the cathode 5 and the upper cathode plate 3 for support and to prevent the cathode 5 from breaking during extrusion. Sealing gaskets are also arranged on the outer sides of the upper cathode plate 3 and the lower cathode plate 4 to seal the outer sides of the upper cathode plate 3 and the lower cathode plate 4. A through hole is opened in the center of the lower cathode plate 4. To prevent the electroforming solution from entering the gap of the cathode fixture 2 through the through hole of the lower cathode plate 4, the O-ring 9 is arranged in the second annular groove of the lower cathode plate 4 and contacts the lower surface of the cathode 5 to form a seal. At the same time, the O-ring 9 can also form a side liquid sealing groove with a certain size with the cathode 5 and the lower cathode plate 4 to suppress the edge effect of the casting layer of the cathode 5 and achieve high-thickness electroforming.

[0044] Among them, the upper cathode plate 3 is also provided with a wire hole 10. The wire connected to the conductive ring 6 is led out from the wire hole 10 and connected to a power supply to continuously supply power to the cathode 5.

[0045] The electroforming tank 1 is filled with an electroforming solution, and the electroforming solution can enter through the through hole of the lower cathode plate 4 and contact the lower surface of the cathode 5 (within the area of the O-ring 9). In this embodiment, the spraying method of the flushing port 11 is adopted.

[0046] Meanwhile, the electroforming module further includes an anode 12 set at 45 degrees, which is installed on the electroforming tank 1 in a suspended manner. The flushing port 11 set at 30 degrees can be obtained by 3D printing and is connected to the electroforming tank 1 through bolts. The outlet shape and size of the flushing port 11 can be replaced according to actual electroforming requirements, and the bubbles generated on the surface of the casting layer due to hydrogen evolution are eliminated by flushing.

[0047] The electroforming module further includes a shielding baffle 13, which includes a shielding baffle fixing part 14 and a shielding baffle disassembly and assembly part 15. Among them, the shielding baffle fixing part 14 is installed in the electroforming tank 1 through bolts, and the shielding baffle disassembly and assembly part 15 is closely fitted with the shielding baffle fixing part 14 in a nested manner, and the shielding baffle disassembly and assembly part 15 has various specifications for replacing and changing the size of the shielding baffle 13. In addition, the distance between the shielding baffle 13 and the lower cathode plate 4 can also be adjusted. The bolts are fixed at different positions of the shielding baffle fixing part 14 by relying on the long strip-shaped bolt holes to complete the adjustment. The minimum distance between the shielding baffle 13 and the lower cathode plate 4 can be 1 mm. It can be understood that the shielding baffle fixing part 14 and the shielding baffle disassembly and assembly part 15 are also provided with through holes, which correspond to the through holes of the lower cathode plate 4. Under the action of the shielding baffle 13, the electric field only exists at the through hole in the middle of the shielding baffle 13. Further, a coaxial positioning part 16 is also provided, which is used to ensure that the centers of the shielding baffle disassembly and assembly part 15, the lower cathode plate 4, and the upper cathode plate 3 are on the same straight line. Among them, the coaxial positioning part 16, the shielding baffle fixing part 14, etc. are all connected to the shielding baffle mounting frame, and the shielding baffle mounting frame is located in the electroforming tank 1 and is connected to the electroforming tank 1.

[0048] The electroforming solution circulation and filtration module includes a flange adapter 17, a circulation pipe 18, a magnetic pump 19, a filter 20, etc. Among them, the flange adapter 17 is used for connecting the circulation pipe 18 and the flushing port 11. The magnetic pump 19, the filter 20, etc. are all arranged on the circulation pipe 18. The electroforming solution in the circulation system flows out of the electroforming tank 1, passes through the magnetic pump 19 and the filter 20 in sequence, and finally sprays out from the flushing port 11. Preferably, the circulation filtration accuracy is 5um, which can effectively filter anode mud and various impurities to achieve smooth deposition on the surface of the casting layer.

[0049] In this embodiment, the electroforming solution temperature control module includes a water bath 21, a U-shaped heating pipe 22, a relay 23, a temperature sensor 24, and a temperature controller 25. Among them, the U-shaped heating pipe 22 and the temperature sensor 24 are evenly arranged in the water bath 21. The temperature controller 25 is electrically connected to the temperature sensor 24, and is used to receive the signal of the temperature sensor 24 to obtain the water temperature, and control the U-shaped heating pipe 22 to heat through the relay 23 to regulate the water temperature. The electroforming tank 1 is fixed on the water bath 21 and is heated to the required temperature by the water bath 21.

[0050] During the electroforming process, the cathode fixture 2 needs to rotate continuously, which is driven by the cathode rotation control module. Specifically, in this embodiment, the cathode rotation control module includes a rotating shaft 26, which is rotatably arranged on a support plate 27, and both ends are respectively connected to the upper cathode plate 3 of the cathode fixture 2 and a coupling 28. The coupling 28 is connected to a stepper motor 29 to transmit the output of the stepper motor 29 to the rotating shaft 26. The stepper motor 29 is also arranged on the support plate 27. The support plate 27 as a whole seals structures such as the rotating shaft 26 and the stepper motor 29 through a housing 30. A cathode rotation controller 31, a driver 32, etc. are also provided. The cathode rotation controller 31 inputs a control program to the driver 32 to control the rotation of the stepper motor 29, and finally realizes the control of the rotation of the cathode 5.

[0051] In addition, a bearing support 33 is also arranged on the support plate 27 for rotatably supporting the rotating shaft 26, further improving the stability of the rotating shaft 26.

[0052] Since the cathode fixture 2 needs to supply power to the cathode 5 through a wire, the wire is led out through the wire hole 10 of the upper cathode plate 3. During the electroforming process, the upper cathode plate 3 rotates continuously. Therefore, in this embodiment, a slip ring 34 is also arranged on the rotating shaft 26, which includes a rotating part and a fixed part. The wire of the upper cathode plate 3 is connected to the rotating part, and the fixed part is connected to the power supply to enable the wire to be smoothly arranged without being hindered by the rotation while ensuring power supply.

[0053] In this embodiment, the support plate 27 can move so that the cathode fixture 2 at the end of the rotating shaft 26 can accurately enter the electroforming tank 1 and dock with the shielding baffle 13, and can be removed from the electroforming tank 1 during material replacement. Therefore, a support plate driving mechanism is provided. At the same time, as Figure 5 shown, the support plate driving mechanism includes a support frame 35, a first hinge 36, a micro hydraulic support rod 37, a second hinge 38 and a third hinge 39. Among them, the support frame 35 is fixedly arranged. One end of the support plate 27 is hinged to the support frame 35 through the first hinge 36. The fixed end of the micro hydraulic support rod 37 is hinged to the support frame 35 through the second hinge 38, and the telescopic end of the micro hydraulic support rod 37 is hinged to the support frame 35 through the third hinge 39. Therefore, it can drive the support plate 27 to rotate around the support frame 35 to adjust the position of the cathode fixture 2. Since the shielding baffle 13, the anode 12, etc. are all arranged at 45 degrees, when the cathode fixture 2 is adjusted to be inclined at 45 degrees, it can dock with the shielding baffle 13, the anode 12, etc. and ensure coaxiality.

[0054] In this embodiment, the pH monitoring module includes a pH detector 40, a composite electrode connector 41, and a composite electrode 42. The composite electrode 42 is installed in the composite electrode connector 41 by bolts. The left and right ends of the composite electrode connector 41 are connected to the circulation pipe 18. The composite electrode 42 installed at this position can avoid the interference of the electric field during the electroforming process on the measurement accuracy, and realize the real-time online monitoring of the pH value of the circulation system under the signal conversion of the pH detector 40, so as to obtain corresponding experimental data.

[0055] In this embodiment, the heat dissipation module includes several heat dissipation fans 43 of different sizes, which are used to cool the magnetic pump 19, the stepping motor 29, and various instrument panels, ensuring that the equipment can operate for a long time.

[0056] In this embodiment, the cleaning module includes an ultrasonic cleaner 44, which facilitates the pre-treatment of the electroforming of the cathode 5, etc. and the post-treatment of the electroformed product. The power supply module includes a power switch panel 45, which is responsible for controlling the power switches of each module.

[0057] Based on the same inventive concept, this embodiment also provides an electroforming method for improving the thickness uniformity of a micro-injection mold by using the above device, which mainly includes two steps: photolithography and electroforming. The photolithography includes making a mask plate, spin-coating photoresist on a silicon substrate, exposure, development, deep plasma etching, and cleaning to form a silicon wafer with microstructures. On this basis, the silicon wafer with microstructures is subjected to a conductivity treatment, specifically by first depositing a 5 - 10 nm layer of Cr or Ti as an adhesion layer in a magnetron sputtering instrument or an evaporation coater, and then depositing a 30 - 50 nm layer of Au or Pt as a conductive layer to form a cathode.

[0058] The processed cathode is installed in the cathode fixture. Turn on the heating switch of the water bath, set the water bath temperature to 45 °C in the temperature controller, and turn on the power switch to set the power parameters to 1 A / dm 2 - 2 h, 2 A / dm 2 - 2 h, 4 A / dm 2 - 10 h. Replace the liquid inlet as needed, adjust the distance between the shielding baffle fixing part and the lower cathode plate, and the size of the shielding baffle disassembly part. Drop a wetting agent on the surface of the cathode installed in the cathode fixture, connect the cathode power line. Then add electroforming solution to completely submerge the cathode fixture, turn on the circulation and filtration module, and turn on the cathode rotation controller to control the rotation of the cathode.

[0059] After running for 2 minutes, turn on the power switch to supply power to the cathode and the anode. Finally, cover the upper covers of the electroforming tank and the water bath and wait for the electroforming to end. Disassemble the cathode fixture and take out the whole of the casting layer and the cathode, clean it in the ultrasonic cleaner, then dissolve and separate the casting layer and the cathode in a NaOH solution. After separation, put the casting layer into the ultrasonic cleaner again for cleaning, and finally dry the surface with nitrogen.

[0060] The casting layer obtained through the above process has high replication accuracy, no pore defects in the microstructure, a smooth surface without bubbles, a uniformity of up to 95% when the casting layer is 1 mm thick, and a uniformity of up to 85% when the casting layer is 2 mm thick, as Figure 6 shown.

[0061] The above is the preferred embodiment of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle described in the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. An electroforming device for improving the thickness uniformity of a micro-injection mold, characterized in that, It includes an electroforming module, an electroforming solution temperature control module, and a cathode rotation control module; The electroforming module includes an electroforming tank and a cathode fixture. The cathode fixture is used to fix the cathode. The electroforming tank is filled with an electroforming solution and an anode corresponding to the cathode. The cathode fixture is provided with a side liquid sealing groove and a shielding baffle. The side liquid sealing groove is used to suppress the edge effect of the cathode of the casting layer. An impact liquid port is arranged in the electroforming tank, and the impact liquid port is aligned with the through hole of the shielding baffle and the cathode, so that the electroforming solution impacts the cathode; The cathode rotation control module is used to control the rotation of the cathode fixture; The electroforming solution temperature control module is used to control the temperature of the electroforming solution in the electroforming tank; The cathode fixture includes an upper cathode plate and a lower cathode plate. The cathode is located between the upper cathode plate and the lower cathode plate. At the same time, a conductive ring, a support gasket, a micro spring, and an O-ring are also arranged. The conductive ring contacts the cathode to supply power to the cathode. The micro spring is arranged in the first annular groove of the lower cathode plate and contacts the conductive ring to press the conductive ring and the cathode tightly. The support gasket is located between the cathode and the upper cathode plate to prevent the cathode from breaking during extrusion. A through hole is opened in the center of the lower cathode plate. The O-ring is arranged in the second annular groove of the lower cathode plate and contacts the lower surface of the cathode to form a seal. The O-ring, the cathode, and the lower cathode plate form a side liquid sealing groove; The shielding baffle includes a shielding baffle fixing part and a shielding baffle dismounting part. The shielding baffle fixing part is installed in the electroforming tank through bolts. The shielding baffle dismounting part is nested and matched with the shielding baffle fixing part. The shielding baffle fixing part and the shielding baffle dismounting part are both provided with through holes, and correspond to the through hole of the lower cathode plate; A coaxial positioning part is also provided to ensure that the centers of the shielding baffle dismounting part, the lower cathode plate, and the upper cathode plate are on the same straight line. The coaxial positioning part and the shielding baffle fixing part are both connected to the shielding baffle mounting frame. The shielding baffle mounting frame is located in the electroforming tank and connected to the electroforming tank.

2. The electroforming device for improving the thickness uniformity of a micro-injection mold according to claim 1, characterized in that, The impact liquid port is inclined relative to the cathode for inclined liquid impact.

3. The electroforming device for improving the thickness uniformity of a micro-injection mold according to claim 2, wherein, The upper cathode plate is also provided with a wire hole, and the wire connected to the conductive ring is led out from the wire hole.

4. An electroforming device for improving the thickness uniformity of a micro-injection mold according to claim 3, characterized in that, The installation distance of the shielding baffle fixing part can be adjusted, and the shielding baffle dismounting part has various specifications.

5. An electroforming device for improving the thickness uniformity of a micro-injection mold according to claim 4, characterized in that, The cathode rotation control module includes a rotating shaft. The rotating shaft is rotatably arranged on a support plate, and both ends of the rotating shaft are respectively connected to the upper cathode plate of the cathode fixture and a coupling. The coupling is connected to a stepping motor; A conductive slip ring is arranged on the rotating shaft, and the conductive slip ring is used for circuit connection with the cathode fixture; The support plate is connected to a support plate driving mechanism, and the support plate driving mechanism is used to drive the support plate to move, so that the cathode fixture is docked with or separated from the electroforming tank.

6. The electroforming device for improving the thickness uniformity of a micro-injection mold according to claim 5, characterized in that, An electroforming solution circulation and filtration module is also provided. The electroforming solution circulation and filtration module includes a flange adapter, a circulation pipe, a magnetic pump, and a filter. The flange adapter is used for connecting the circulation pipe to the liquid injection port. The magnetic pump and the filter are both arranged on the circulation pipe.

7. An electroforming device for improving the thickness uniformity of a micro-injection mold according to claim 6, characterized in that, An electroforming solution temperature control module is also provided. The electroforming solution temperature control module includes a water bath, a U-shaped heating pipe, a relay, a temperature sensor, and a temperature controller. The U-shaped heating pipe and the temperature sensor are evenly arranged in the water bath. The temperature controller is electrically connected to the temperature sensor and is used to receive the signal from the temperature sensor. The relay is used to control the heating of the U-shaped heating pipe. The electroforming bath is fixed in the water bath.

8. An electroforming device for improving the thickness uniformity of a micro-injection mold according to claim 7, characterized in that, It also includes a pH monitoring module, a heat dissipation module, a cleaning module, and a power supply module. The pH monitoring module includes a pH detector, a composite electrode connector, and a composite electrode. The composite electrode is installed in the composite electrode connector. Both ends of the composite electrode connector are connected to the circulation pipe. The composite electrode is electrically connected to the pH detector. The heat dissipation module includes several heat dissipation fans, which are used for heat dissipation and temperature reduction. The cleaning module includes an ultrasonic cleaner, which is used for ultrasonic cleaning of the cathode and the product. The power supply module includes a power switch panel, which is used for power switch control.

9. An electroforming method for improving the thickness uniformity of a micro-injection mold, using the device as described in claim 8, characterized in that It includes a photolithography step and an electroforming step. The photolithography step includes fabricating a mask plate, spin-coating a photoresist on a silicon substrate, exposure, development, deep plasma etching, and cleaning to form a silicon wafer with microstructures. Conductivization treatment is performed on the silicon wafer with microstructures. Specifically, a 5 - 10 nm layer of Cr or Ti is first deposited as an adhesion layer in a magnetron sputtering instrument or an evaporation coater, and then a 30 - 50 nm layer of Au or Pt is deposited as a conductive layer to form a cathode. The electroforming step includes installing the processed cathode in a cathode fixture, turning on the heating switch of the water bath, setting the water bath temperature to 45 °C in the temperature controller, turning on the power switch and setting the power parameters, replacing the liquid injection port as needed, adjusting the distance between the shielding baffle fixing part and the lower cathode plate and the size of the shielding baffle disassembly and assembly part, dropping a wetting agent on the surface of the cathode installed in the cathode fixture, connecting the cathode power line, then adding electroforming solution to completely submerge the cathode fixture, turning on the circulation and filtration module, and turning on the cathode rotation controller to control the rotation of the cathode. After running for a period of time, turn on the power switch to energize the cathode and the anode. Finally, cover the upper covers of the electroforming bath and the water bath and wait for the electroforming to end. Disassemble the cathode fixture and take out the whole of the cast layer and the cathode, clean it in the ultrasonic cleaner, then place the cast layer and the cathode in a NaOH solution for dissolution and separation. After separation, put the cast layer back into the ultrasonic cleaner for cleaning, and finally dry the surface with nitrogen.

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