Voice coil motor base containing metal circuit molding and preparation method thereof

Abstract

The invention discloses a voice coil motor base formed by a metal circuit and a preparation method of the voice coil motor base, and relates to the technical field of voice coil motors, the voice coil motor base is formed by a plurality of electronic components, a double-layer circuit welded with the electronic components, and a plastic body which is directly embedded into the metal circuit and is formed by injection molding, so that the metal circuit is tightly combined with a plastic base; the metal circuit is manufactured by adopting a precision stamping and electroplating process and has excellent conductivity and corrosion resistance; the preparation method comprises the steps of preparation of the metal circuit, injection molding and post-processing, so that firm connection and accurate alignment between the metal circuit and the plastic base are ensured; the close combination of the metal circuit and the electronic element and the optimized circuit design improve the stability and reliability of signal transmission and reduce signal interference, thereby improving the response speed and control precision of the voice coil motor, and effectively improving the performance and reliability of the voice coil motor.

Description

Technical Field

[0001] The present invention relates to the technical field of voice coil motors, and particularly to a voice coil motor base with a formed metal circuit and a preparation method thereof. Background Art

[0002] As a device that can efficiently convert electrical energy into mechanical energy, the voice coil motor (VCM) plays a crucial role in today's electronic device field. It is widely used in the automatic focusing system of mobile phone cameras, enabling the mobile phone to quickly and accurately focus when taking pictures, improving the shooting effect; at the same time, there have been qualitative leaps in terms of noise and volume, completely enhancing the user experience to a higher level.

[0003] However, there are significant defects in the current connection methods of traditional voice coil motor bases. In the welding method, thermal stress is inevitably generated during the welding process. This thermal stress may cause the connection between the circuit components and the base to become loose, thereby affecting the overall stability and reliability of the voice coil motor. During actual use, frequent vibrations or temperature changes may cause the circuit components that were originally not firmly connected due to the influence of thermal stress to separate from the base, resulting in the failure of the camera's automatic focusing function.

[0004] While the assembly method seems relatively simple to operate, it is prone to assembly errors. For a voice coil motor with extremely high precision requirements, such errors will seriously affect its performance. In the imaging focusing system, even extremely small assembly errors may lead to inaccurate focusing, thereby causing imaging errors and affecting the normal operation of taking pictures or videos.

[0005] In addition, traditional preparation methods also face the problems of high manufacturing costs and low production efficiency. The complex welding process and delicate assembly process not only require professional equipment and technicians, but also consume a large amount of time and raw materials, increasing the production cost and reducing the production efficiency, making it difficult to meet the growing market demand.

[0006] In view of this, the present application is specifically proposed. Summary of the Invention

[0007] The purpose of the present invention is to provide a voice coil motor base with a formed metal circuit and a preparation method thereof, so as to solve the problems raised in the above background art.

[0008] To solve the above technical problems, a voice coil motor base with a formed metal circuit provided by the present invention includes:

[0009] A metal circuit, which is composed of at least one conductive layer and forms a predetermined circuit pattern through precision stamping and electroplating processes.

[0010] Plastic base, the plastic base includes at least one accommodation cavity for accommodating the metal circuit;

[0011] Bonding layer, the bonding layer is located between the metal circuit and the plastic base, and is used to achieve the tight bonding of the metal circuit and the plastic base; the metal circuit is embedded in the cavity of the plastic base and is firmly connected to the plastic base through the bonding layer.

[0012] Further, the metal circuit includes a plurality of parallel and spaced metal branches. One end of each metal branch forms a pin end, and the other end forms a solder pad end. The pin end and the welding end are respectively used for connecting and fixing to electronic components. The thickness of the metal circuit is between 0.05 mm and 0.2 mm, and the line width of the metal circuit is between 0.1 mm and 0.3 mm.

[0013] Further, the bottom surface of the plastic base is a plane, and a square bottom cavity is recessed in the middle of its bottom surface. Positioning holes for fixing the plastic base are provided at the four corners of its bottom surface. An inner hole is provided at the center of the plastic base, and a retaining wall is provided at the upper end of the inner hole. Positioning posts are respectively provided at the four corner positions of the upper surface of the plastic base. Four-corner bosses are also installed on the top surface of the plastic base, and a relief hole adapted to the positioning post is provided on the four-corner bosses;

[0014] It further includes a positioning seat provided on the inner wall of the four-corner boss. A positioning groove for positioning and fixing the welding end of the metal circuit to ensure the precise position of the metal circuit in the plastic base is formed on the positioning seat.

[0015] Further, a heat-conducting bottom plate is embedded in the inner bottom wall of the plastic base, and an elastic frame that can deform in the vertical direction is also sandwiched between the top surface of the heat-conducting bottom plate and the bottom surface of the bonding layer;

[0016] A metal corrugated plate is provided in the heat exchange cavity surrounded by the heat-conducting bottom plate, the bonding layer and the elastic frame. In the natural state, the upper and lower sides of the metal corrugated plate are respectively in contact with the bonding layer and the heat-conducting bottom plate.

[0017] Further, the metal corrugated plate is composed of a high heat-conducting metal plate. Its edge is fixed to the outer wall of the retaining wall, and a gap is left between its outer edge and the inner wall of the elastic frame to leave space for the deformation of the metal corrugated plate; the wave crest extending upward of the metal corrugated plate is directly below the heat generation point of the metal circuit.

[0018] Further, a sealed space is provided inside the plastic base. Liquid inlet and outlet holes communicating with the sealed space are provided on the plastic base. The inside of the sealed space is filled with a coolant through the liquid inlet and outlet holes. An external heat-conducting fin extending into the sealed space and in contact with the coolant is connected to the bottom surface of the heat-conducting bottom plate;

[0019] An inner heat-conducting fin is also slidably installed inside the outer heat-conducting fin. The top end of the inner heat-conducting fin extends upward and is connected to the bottom surface of the bonding layer. The bottom end of the inner heat-conducting fin extends into the sealed space and is connected to an extension piece. The extension piece is rotatably arranged at the bottom end of the inner heat-conducting fin. A flexible bag is also sleeved on the outer wall of the inner heat-conducting fin extending into the sealed space. The inside of the flexible bag is filled with a filler, and the filler is sodium bicarbonate powder or ether.

[0020] Further, the extension piece includes a rotating part rotatably connected to the bottom end of the inner heat-conducting fin and having a disc-shaped structure. A sliding part that can slide radially along it is arranged inside the rotating part. The sliding part has an inclined surface. A trigger piece extending upward and corresponding to the position of the extension piece is arranged on the inner bottom wall of the sealed space. The trigger piece has a wedge-shaped structure, and the inclined surface of the sliding part fits with the inclined surface of the wedge-shaped block.

[0021] Further, a shape memory alloy sheet with a two-way memory effect is also installed on the outer wall of the extension piece. The shape memory alloy sheet is connected to the end of the sliding part extending outward. Each shape memory alloy sheet is perpendicular to the outer wall of the extension piece.

[0022] A preparation method of a metal circuit formed voice coil motor base is characterized by comprising the following steps:

[0023] Step 1, prepare a metal circuit; form a predetermined circuit pattern on a metal plate through precision stamping and electroplating processes;

[0024] Step 2, place the metal circuit at a predetermined position in an injection mold through an automated device and close the mold; inject molten plastic material into the mold to cool and solidify the plastic material in the mold to form a plastic base containing the metal circuit;

[0025] Step 3, take out the plastic base from the mold and perform cutting, tray loading and inspection.

[0026] Further, in Step 1, the conductive material of the metal circuit layer is one of copper, aluminum or alloy materials, and the accuracy of its circuit pattern is controlled within ±0.1 mm; in Step 2, the plastic material for injection molding is a thermoplastic resin or a thermosetting resin, and the resin undergoes chemical bonding or physical adsorption with the metal circuit during the injection molding process to form a bonding layer;

[0027] It also includes a step of surface treatment of the plastic base after Step 3 to improve the appearance quality and durability of the plastic base.

[0028] Compared with the prior art, the beneficial effects of the present invention are:

[0029] 1. The present invention, a voice coil motor base with a metal circuit formed thereon and its preparation method, has multiple advantages. Firstly, by directly forming the metal circuit on it, the external circuit board and wire connections are reduced, greatly reducing the volume and weight of the voice coil motor, which is beneficial for the miniaturization design of electronic devices. Secondly, the tight combination of the metal circuit and [object not specified] and the optimized circuit design improve the stability and reliability of signal transmission, reduce signal interference, and thus enhance the response speed and control accuracy of the voice coil motor. Moreover, the preparation method can flexibly adjust the metal matrix material, parameters of the metal circuit, and preparation process parameters according to different requirements, having wide applicability. In terms of application prospects, with the continuous development of electronic products such as smart phones, tablets, and wearable devices, the requirements for camera performance and miniaturization are getting higher and higher. The voice coil motor base of the present invention can be widely applied to the camera focusing systems of these devices, and can also be applied to other fields that require voice coil motors, such as hard disk drives and optical image stabilization devices, having broad market prospects.

[0030] 2. The present invention has a multi-layer heat dissipation structure design, including a metal corrugated plate, an elastic frame, a coolant, heat dissipation fins, and special fillers and adjustable extension sheets, etc., which can quickly and effectively dissipate the heat generated by the metal circuit, reduce the temperature of the voice coil motor during operation, ensure its stable operation, and extend its service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is a front view structural schematic diagram of the present invention;

[0032] Figure 2 is a bottom view structural schematic diagram of the present invention;

[0033] Figure 3 is a front view exploded structural schematic diagram of the present invention;

[0034] Figure 4 is a bottom view exploded structural schematic diagram of the present invention;

[0035] Figure 5 is a top view structural schematic diagram of the present invention;

[0036] Figure 6 is along Figure 5 the sectional structural schematic diagram of the middle section line A-A;

[0037] Figure 7 is Figure 6 the enlarged structural view of the A position in

[0038] Figure 8 is the structural schematic diagram of the metal circuit of phosphor bronze material;

[0039] Figure 9 is the schematic diagram of the metal circuit of stainless steel material;

[0040] Figure 10 Schematic diagram of the welding structure of the electronic components and the metal circuit of the present invention.

[0041] In the figure: 1. Plastic base; 2. Square bottom cavity; 3. Inner hole; 4. Four-corner convex platform; 5. Positioning column; 6. Positioning seat; 7. Bonding layer; 8. Positioning hole; 9. Retaining wall glue groove; 10. Relief hole; 11. Accommodating cavity; 12. Metal corrugated plate; 13. Sealed space; 14. Liquid inlet and outlet hole; 15. Heat exchange cavity; 16. Elastic frame; 17. Heat-conducting bottom plate; 18. Outer heat-conducting fin; 19. Inner heat-conducting fin; 20. Flexible capsule; 21. Filler; 22. Triggering member; 23. Extension piece; 24. Shape memory alloy sheet. Specific embodiments

[0042] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. 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.

[0043] Please refer to Figures 1 - 10 , the present invention provides a technical solution: a voice coil motor base containing a metal circuit formed, including:

[0044] A metal circuit, which is composed of at least one conductive layer and forms a predetermined circuit pattern through precision stamping and electroplating processes;

[0045] A plastic base 1, which includes at least one accommodating cavity 11 for accommodating the metal circuit;

[0046] A bonding layer 7, which is located between the metal circuit and the plastic base 1 and is used to realize the tight combination of the metal circuit and the plastic base 1; the metal circuit is embedded in the accommodating cavity 11 of the plastic base 1 and is firmly connected to the plastic base 1 through the bonding layer 7.

[0047] Referring to Figure 8 or Figure 9 , the metal circuit includes a plurality of parallel and spaced metal branches, one end of each metal branch forms a pin end, and the other end forms a solder end. The pin end and the welding end are respectively used to connect and fix to electronic components. The thickness of the metal circuit is between 0.05 mm and 0.2 mm, and the line width of the metal circuit is between 0.1 mm and 0.3 mm.

[0048] Specifically, the voice coil motor base with metal circuit forming includes a plastic base 1. The plastic base 1 serves as the basic structure of the entire base, bearing the role of supporting and fixing other components. The material selection of the metal circuit is crucial. In the present invention, one or a combination of aluminum, copper, or aluminum alloy is selected. Aluminum has the advantages of light weight, low cost, and good workability; copper has excellent electrical conductivity, which can effectively reduce circuit transmission loss; aluminum alloy combines the characteristics of aluminum and other metals, such as increased strength. The surface roughness Ra value of the metal circuit is controlled between 0.2 - 1.6. Appropriate surface roughness is helpful for the subsequent deposition and adhesion of the metal circuit.

[0049] The metal circuit is formed on the surface of the metal substrate through physical vapor deposition or electroless plating process. The metal circuit is electrically connected to the coil assembly of the voice coil motor for transmitting electrical signals. The thickness of the metal circuit is between 5 - 50μm. This thickness range can not only ensure good electrical conductivity but also not overly increase the weight and volume of the base. The line width of the metal circuit is between 0.1 - 0.3mm and can be adjusted according to specific circuit design requirements. The metal circuit contains at least one signal transmission line and one grounding line, and the spacing between the signal transmission line and the grounding line is between 0.15 - 0.3mm. A reasonable spacing design can reduce signal interference and ensure the stability of signal transmission.

[0050] A preparation method for a voice coil motor base with metal circuit forming includes the following steps:

[0051] Step 1: Prepare the metal circuit; form a predetermined circuit pattern on the metal sheet through precision stamping and electroplating processes;

[0052] Step 2: Place the metal circuit at a predetermined position in the injection mold through an automated device and close the mold; inject molten plastic material into the mold, and let the plastic material cool and solidify in the mold to form a plastic base containing the metal circuit;

[0053] Step 3: Take out the plastic base from the mold and perform cutting, tray loading, and inspection.

[0054] In Step 1, the conductive material of the metal circuit layer is one of copper, aluminum, or alloy material, and the accuracy of its circuit pattern is controlled within ±0.1mm; in Step 2, the plastic material for injection molding is thermoplastic resin or thermosetting resin, and this resin undergoes chemical bonding or physical adsorption with the metal circuit during the injection process to form a bonding layer;

[0055] It also includes a step of surface treatment of the plastic base after Step 3 to improve the appearance quality and durability of the plastic base.

[0056] Preparation plan:

[0057] Metal circuit deposition

[0058] A metal layer is deposited on the surface of the pretreated metal substrate by physical vapor deposition or electroless plating process to form a preliminary shape of the metal circuit.

[0059] · Physical vapor deposition: The process parameters of physical vapor deposition are a vacuum degree of 1×10 -3 -1×10 -5 Pa. In this vacuum degree range, the interference of impurity gases to the deposition process can be reduced. The deposition temperature is 100 - 500°C. For different metal materials and deposition processes, appropriate temperatures can be selected. For example, for the sputtering deposition of copper, the temperature can be between 200 - 300°C, and the deposition rate is 0.1 - 10μm / min. Physical vapor deposition can adopt sputtering deposition or evaporation deposition. The target material of sputtering deposition is the same as the target metal material of the metal circuit. For example, if a copper circuit is to be deposited, a copper target is selected, and metal atoms are sputtered onto the metal substrate surface to form a metal layer through ion bombardment of the target; the evaporation source material of evaporation deposition is the target metal of the metal circuit or its compound, and the evaporation source material is evaporated at high temperature and deposited on the metal substrate.

[0060] · Electroless plating process: The components of the electroless plating solution include metal salts, reducing agents, complexing agents, and buffering agents. Metal salts provide the source of metal ions. For example, copper sulfate can be used for copper plating; reducing agents are used to reduce metal ions to metal atoms, and commonly used ones include formaldehyde, etc.; complexing agents can stabilize metal ions in the plating solution, such as ethylenediaminetetraacetic acid (EDTA); buffering agents can maintain the pH value of the plating solution stable, such as boric acid. The temperature of the plating solution is controlled at 30 - 80°C, and the pH value is between 4 - 10. By controlling these parameters, the deposition rate and coating quality of electroless plating can be adjusted.

[0061] Metal circuit forming

[0062] Utilize the plastic properties of the metal material by stamping. At room temperature, the metal sheet is separated or deformed through the action of a mold. When the slider of the press moves downward, the upper die and the lower die close, and the sheet is subjected to stress such as extrusion and stretching in the gap of the mold to form a predetermined circuit pattern, and the pattern accuracy is controlled within ±0.1mm.

[0063] Post-treatment

[0064] The formed metal circuit is cleaned and dried to remove impurities such as residual etching solution and photoresist on the surface, and then the metal substrate is passivated. Methods such as chromate passivation and phosphate passivation can be used to improve its corrosion resistance and extend the service life of the voice coil motor base.

[0065] Example 1: Phosphor bronze is selected as the substrate of the metal circuit, with a thickness of 0.08mm and a size of 36mm * 36mm. First, a high-precision stamping and electroplating process is performed on the phosphor bronze substrate to form a circuit pattern;

[0066] Design an injection mold. The shape of the inner cavity of the mold matches the shape of the metal circuit layer, and a positioning structure is provided to fix the position of the metal circuit layer. Preheat the injection mold to a set temperature to ensure the smooth flow and curing of the plastic material during the injection process.

[0067] Select LCP resin material as the injection material, and optimize the temperature and pressure parameters of the injection process according to the physical property table of the resin material. Maintain for a certain period of time at the set temperature and pressure to cool and cure the plastic material in the mold, forming a plastic base 1 containing a metal circuit layer.

[0068] Example 2

[0069] Similar to Example 1, select stainless steel as the metal circuit substrate with a thickness of 0.08 mm and a size of 36 mm * 36 mm. Form a first metal circuit and a second metal circuit arranged in a double-layer interval with the metal circuit in Example 1. Through an integrally injection-molded plastic body, add a step of ultrasonic cleaning the plastic base (1) in the post-treatment step to further improve the cleanliness and durability of the base.

[0070] Conduct performance tests on the voice coil motor bases with metal circuit forming prepared in Example 1 and Example 2, including conductivity tests (measuring the resistivity of the metal circuit using the four-probe method), adhesion tests (testing the bonding force between the metal circuit and the metal substrate using the cross-cut method), and performance tests after overall assembly with the voice coil motor (such as focusing speed, positioning accuracy, etc.). The results show that the voice coil motor base of the present invention has good conductivity, strong adhesion, and can significantly improve the overall performance of the voice coil motor.

[0071] Advantages and application prospects;

[0072] The voice coil motor base with metal circuit forming and its preparation method of the present invention have many advantages. First, by directly forming the metal circuit on the metal substrate, the external circuit board and wire connection are reduced, greatly reducing the volume and weight of the voice coil motor, which is beneficial to the miniaturization design of electronic devices. Second, the tight combination of the metal circuit and the metal substrate and the optimized circuit design improve the stability and reliability of signal transmission, reduce signal interference, thereby enhancing the response speed and control accuracy of the voice coil motor. Moreover, the preparation method of the present invention can flexibly adjust the metal substrate material, the parameters of the metal circuit, and the preparation process parameters according to different requirements, with wide applicability. In terms of application prospects, with the continuous development of electronic products such as smart phones, tablet computers, and wearable devices, the requirements for camera performance and miniaturization are getting higher and higher. The voice coil motor base of the present invention can be widely applied to the camera focusing systems of these devices, and can also be applied to other fields that require voice coil motors, such as hard disk drives and optical image stabilization devices, with broad market prospects.

[0073] For a more detailed description: A preparation method of a voice coil motor base with metal circuit forming: includes the following steps:

[0074] Step a: Prepare the metal circuit, and form a predetermined circuit pattern on the metal sheet through precision stamping and electroplating processes.

[0075] First, according to the circuit design requirements of the voice coil motor base, select a suitable metal sheet. For example, considering conductivity and cost factors, copper is preferably selected. If there are strict requirements for weight and slightly lower requirements for conductivity, aluminum or its alloy materials can be selected.

[0076] Use a high-precision stamping die and perform stamping operations on a stamping device. The accuracy of the stamping die determines the initial shape accuracy of the circuit pattern, and the manufacturing tolerance of the die needs to be controlled within ±0.05 mm. During the stamping process, precisely control the pressure, speed, and stroke of the stamping device to ensure that the metal sheet is stamped into the predetermined pattern. For example, for complex multi-layer circuit patterns, multiple stamping steps may be required, and the positioning accuracy between each stamping needs to be controlled within ±0.05 mm to ensure the accurate superposition of each layer of the pattern.

[0077] After stamping, perform the electroplating process. The electroplating solution formula is prepared according to the selected metal sheet and circuit performance requirements. For example, for copper sheets, acidic copper plating solution is usually used to enhance the conductivity and corrosion resistance of the circuit. During the electroplating process, strictly control parameters such as electroplating time, current density, and temperature. Generally, the electroplating time is determined according to the required coating thickness. For example, for a common coating thickness of 0.05 - 0.1 mm, the electroplating time is about 15 - 30 minutes; the current density is controlled at 1 - 3 A / dm 2; The temperature is maintained at 25 - 35°C. By precisely controlling these parameters, a uniform and dense electroplated layer is formed on the surface of the metal circuit, ensuring that the accuracy of the circuit pattern is controlled within ±0.1 mm.

[0078] Step b: Place the metal circuit at a predetermined position in the injection mold through an automated device and close the mold.

[0079] An automated robotic arm with high-precision positioning function is used. The positioning accuracy of the robotic arm can reach ±0.05 mm. Before grasping the metal circuit, the position and posture of the metal circuit are accurately identified through a vision recognition system, compared with a preset standard image, and the deviation value is calculated.

[0080] Based on the deviation value, the automated robotic arm adjusts the grasping position and angle in real time to ensure that the metal circuit is accurately placed at the predetermined position in the injection mold. During the placement process, the movement of the robotic arm is stable to avoid the position deviation of the metal circuit caused by vibration or collision.

[0081] At the welding end of the metal circuit, positioning grooves or protrusions are pre-formed by stamping or etching processes. At the same time, positioning protrusions or grooves matching the positioning grooves or protrusions are set at the corresponding positions of the injection mold. When the metal circuit is placed in the mold, these positioning structures cooperate with each other to further ensure the accurate position of the metal circuit in the plastic base, and the positioning accuracy can be improved to ±0.03 mm.

[0082] After confirming that the metal circuit is placed in place, the moving mold and the stationary mold of the injection mold are slowly closed under the drive of the mold closing mechanism. During the mold closing process, the mold closing pressure is monitored in real time through a pressure sensor to ensure that the mold closing pressure is uniform and meets the set value. Generally, the mold closing pressure is controlled between 10 - 30 MPa to ensure the sealing performance and molding effect of the mold.

[0083] Step c: Inject molten plastic material into the mold, and let the plastic material cool and solidify in the mold to form a plastic base containing the metal circuit.

[0084] According to the usage environment and performance requirements of the voice coil motor base, select a suitable plastic material, namely thermoplastic resin (such as ABS, PC, etc.) or thermosetting resin (such as epoxy resin, phenolic resin, etc.).

[0085] Add the selected plastic material into the barrel of the injection molding machine, and heat the plastic material to the molten state through the heating device in the barrel. For thermoplastic resins, the heating temperature depends on the specific material. For example, ABS resin is generally heated to 200 - 250°C, and PC resin is heated to 260 - 320°C. For thermosetting resins, in addition to heating to make it reach a flowable state, the curing reaction conditions also need to be controlled.

[0086] The molten plastic material is pushed by the screw of the injection molding machine and injected into the closed mold cavity through the runner and gate at a certain pressure and speed. The injection pressure is generally controlled between 50 - 150 MPa, and the injection speed is adjusted according to the mold structure and product shape, usually between 50 - 200 mm / s. During the injection process, ensure that the plastic material can evenly fill the mold cavity, especially around the metal circuit, to avoid defects such as material shortage and bubbles.

[0087] After being injected into the mold cavity, the plastic material is cooled through the cooling system of the mold. The cooling medium is generally circulating water or heat-conducting oil, and the cooling temperature is controlled according to the characteristics of the plastic material. For example, the cooling temperature of thermoplastic resins is generally between 30 - 80 °C. The cooling time depends on the product thickness and mold structure, generally between 10 - 60 seconds, to allow the plastic material to fully cool and solidify, closely combine with the metal circuit, and form a plastic base containing the metal circuit. During the cooling process, due to the different thermal expansion coefficients of the plastic material and the metal circuit, certain internal stresses may be generated. Therefore, it is necessary to optimize the design of the cooling system and control of the cooling parameters to minimize the internal stresses and improve the product quality.

[0088] During the injection process, chemical bonding or physical adsorption occurs on the surface between the plastic material and the metal circuit, forming a bonding layer. To enhance this bonding force, the metal circuit surface can be pre-treated chemically, such as micro-etching the surface of the copper circuit to increase surface roughness, or coating a layer of coupling agent to promote chemical bonding between the plastic material and the metal circuit.

[0089] Step d: Remove the plastic base from the mold and perform necessary processing steps, such as cutting, palletizing, and inspection.

[0090] When the plastic base has cooled and solidified to meet the demolding requirements, the moving mold and the stationary mold of the injection mold open, and the plastic base is ejected from the mold cavity through the ejection mechanism. The ejection position and ejection force of the ejection mechanism need to be accurately calculated and adjusted to ensure that the plastic base can be smoothly demolded without deformation or damage.

[0091] The demolded plastic base may carry some gate, runner waste, and flash, etc., which need to be removed through the cutting process. High-precision cutting equipment, such as a laser cutting machine or a punching die, is used to cut the plastic base according to the design dimensions of the product. The cutting accuracy is controlled within ±0.1 mm to ensure that the product dimensions meet the requirements.

[0092] After cutting, the plastic bases are placed on a specific tray or rack according to certain rules, which is convenient for subsequent handling, storage, and transfer. During the palletizing process, pay attention to avoiding mutual collision and scratching between the plastic bases to prevent surface damage.

[0093] Conduct a comprehensive inspection on the plastic base after arranging it on the plate. The inspection contents include appearance inspection, such as whether there are defects like bubbles, scratches, deformations, etc.; dimension measurement, using measuring tools (such as calipers, micrometers, etc.) to measure key dimensions to ensure they are within the tolerance range; electrical performance testing, using professional testing equipment to detect whether electrical parameters such as the conductivity and resistance value of the metal circuit meet the design requirements. For unqualified products, mark and isolate them, analyze the reasons and take corresponding corrective measures.

[0094] Step e: Conduct surface treatment on the plastic base after being processed in step d to improve the appearance quality and durability of the plastic base.

[0095] Spraying treatment: Adopt electrostatic spraying or air spraying methods to evenly spray a layer of protective paint on the surface of the plastic base. Before spraying, first clean the surface of the plastic base to remove impurities such as oil stains and dust, and ultrasonic cleaning or chemical cleaning methods can be used. Then, select a suitable protective paint according to the appearance requirements and usage environment of the product, such as polyurethane paint, acrylic paint, etc. For electrostatic spraying, adjust parameters such as the voltage of the spray gun, the distance between the spray gun and the workpiece, and the spraying speed. Generally, the voltage is controlled between 60 - 100 kV, the distance between the spray gun and the workpiece is maintained at 200 - 300 mm, and the spraying speed is between 10 - 30 cm / s, so that the paint can be evenly adsorbed on the surface of the plastic base. For air spraying, control the air pressure between 0.3 - 0.5 MPa to ensure that the paint mist particles are fine and evenly distributed. After spraying, send the workpiece into the drying furnace for drying and curing. The drying temperature and time depend on the characteristics of the paint. For example, polyurethane paint is generally dried at 60 - 80 °C for 1 - 2 hours. Through spraying treatment, the hardness and gloss of the plastic base surface can be effectively improved, making its appearance more beautiful, while enhancing the resistance to the external environment and extending the service life. For example, in the application scenario of the base of the voice coil motor of a mobile phone camera, the plastic base after spraying treatment can better resist friction and minor collisions during daily use and maintain a good appearance.

[0096] Coating treatment: Use physical vapor deposition (PVD) or chemical vapor deposition (CVD) technology to form a thin film on the surface of the plastic base. For PVD technology, such as magnetron sputtering coating, place the plastic base in the working chamber of the vacuum coating equipment, first pump the working chamber to a high vacuum state, generally the vacuum degree reaches 10 -3 -10 -5Pa. Then introduce an appropriate amount of reaction gas (such as argon, etc.), and apply a certain voltage to the target (such as chromium target, titanium target, etc.) to ionize the argon gas to form a plasma. The argon ions in the plasma bombard the target under the action of an electric field, and the sputtered target atoms are deposited on the surface of the plastic base to form a thin film. During the film coating process, parameters such as the coating time, target power, and gas flow rate are controlled to obtain a thin film with the desired thickness and performance. For example, for a chromium film, the coating time is generally 30 - 60 minutes, the target power is controlled at 1 - 3 kW, and the argon gas flow rate is between 5 - 15 sccm. For the CVD technology, place the plastic base in a reaction furnace and introduce gaseous reactants containing the elements that make up the thin film. At a certain temperature and pressure, the gaseous reactants undergo a chemical reaction on the surface of the plastic base to form a solid thin film and deposit on the surface. When depositing a silicon dioxide thin film, the reaction temperature is generally 300 - 500 °C, and the pressure is controlled at 1 - 10 kPa. By precisely controlling the reaction conditions, a uniform and dense thin film can be obtained. This thin film can be a metal film (such as chromium film, titanium film, etc.), which can improve the wear resistance and decorative properties of the plastic base; it can also be a functional thin film, such as an anti-fingerprint film, an oleophobic film, etc., to further improve its use performance and appearance quality. For example, during the use of electronic products, the anti-fingerprint film can effectively reduce the residue of fingerprints and oil stains on the surface of the plastic base and keep the appearance of the product clean.

[0097] Chemical treatment: Immerse the plastic base in a specific chemical solution to modify its surface through a chemical reaction. For some plastic bases made of thermoplastic resins, such as ABS plastic, when using acid etching treatment, it can be immersed in an acid etching solution containing components such as sulfuric acid and chromic acid and treated at a certain temperature and time. The acid etching temperature is generally controlled at 50 - 70 °C, and the treatment time is between 5 - 15 minutes. Through the acid etching reaction, the microscopic structure of the plastic base surface changes, increasing the surface roughness and improving the adhesion of the subsequent coating. For some plastic bases that need to improve weather resistance, a chemical solution containing anti-aging agents, ultraviolet absorbers, etc. can be used for treatment. Immerse the plastic base in this solution, and under appropriate temperature and time conditions, make these functional components adsorb or chemically bond to the surface of the plastic base to improve its weather resistance and keep its stable performance and appearance under different environmental conditions.

[0098] In step a, the conductive material of the metal circuit layer is copper, aluminum, or alloy material, and the accuracy of its circuit pattern is controlled within ±0.1 mm.

[0099] In step b, it also includes forming positioning grooves or protrusions at the welding ends of the metal circuit to cooperate with the positioning protrusions or grooves in the plastic base to further ensure the precise position of the metal circuit in the plastic base.

[0100] In step c, the plastic material for injection molding is a thermoplastic resin or a thermosetting resin, and the resin chemically bonds or physically adsorbs with the metal circuit during the injection process to form a bonding layer.

[0101] The surface treatment in step e specifically includes the above-mentioned spraying treatment, coating treatment, and chemical treatment.

[0102] Refer to Figures 1 - 7 , the bottom surface of the plastic base 1 is a flat surface, a square bottom cavity 2 is recessed in the middle of its bottom surface, positioning holes 8 for fixing the plastic base 1 are provided at the four corners of its bottom surface, an inner hole 3 is provided at the center of the plastic base 1 and a retaining wall is provided at the upper end of the inner hole 3, positioning posts 5 are respectively arranged at the four corner positions of the upper surface of the plastic base 1, four-corner bosses 4 are further installed on the top surface of the plastic base 1, and a relief hole 10 adapted to the positioning post 5 is provided in the four-corner boss 4;

[0103] It further includes a positioning seat 6 provided on the inner wall of the four-corner boss 4, and a positioning groove for positioning and fixing the welding end of the metal circuit is formed on the positioning seat 6 to ensure the precise position of the metal circuit in the plastic base 1.

[0104] It should be noted that: a retaining wall glue groove 9 is further provided on the side walls of the four sides of the plastic base 1.

[0105] Specifically, the bottom surface of the plastic base 1 is a flat surface, and a square bottom cavity 2 is recessed in the middle for placing the metal circuit; the positioning holes 8 at the four corners are used to fix the plastic base 1; the central inner hole 3, the upper retaining wall, the positioning posts 5 at the four corners of the upper surface, the four-corner bosses 4 and the relief holes 10 together constitute a positioning and installation structure; the positioning groove on the positioning seat 6 on the inner wall of the four-corner boss 4 can precisely fix the welding end of the metal circuit to ensure the position accuracy of the metal circuit in the plastic base 1; these structural designs not only facilitate the installation and fixation of the plastic base 1, but also ensure the accurate position of the metal circuit in the plastic base 1 through the precise positioning structure, which is beneficial to improving the stability of the internal structure of the voice coil motor and the accuracy of signal transmission.

[0106] Refer to Figure 6 and Figure 7 , a heat-conducting bottom plate 17 is embedded in the inner bottom wall of the plastic base 1, and an elastic frame 16 that can deform in the vertical direction is further clamped between the top surface of the heat-conducting bottom plate 17 and the bottom surface of the bonding layer 7;

[0107] A metal corrugated plate 12 is provided in the heat exchange cavity 15 surrounded by the heat-conducting bottom plate 17, the bonding layer 7 and the elastic frame 16. In the natural state, the upper and lower sides of the metal corrugated plate 12 are respectively in contact with the bonding layer 7 and the heat-conducting bottom plate 17;

[0108] The metal corrugated plate 12 is composed of a highly heat-conductive metal plate. Its edge is fixed to the outer wall of the retaining wall, and there is a gap between its outer edge and the inner wall of the elastic frame 16 to leave space for the deformation of the metal corrugated plate 12; the wave crest of the metal corrugated plate 12 extending upward is directly below the heat generation point of the metal circuit.

[0109] Specifically, during use, the heat of the metal circuit flows through the heat flow combination layer 7, and its heat is transferred to the heat-conductive bottom plate 17 through the metal corrugated plate 12; in the natural state, the contact mode between the metal corrugated plate 12 and the heat-conductive bottom plate 17 is point contact, and heat dissipation is only carried out for the heat generation points of the metal circuit. Point contact heat dissipation can accurately locate these key heat generation points, directly dissipate heat from the heat source, efficiently take away heat, avoid excessive heat dissipation in the surrounding non-critical areas, and reduce unnecessary heat dissipation design and energy consumption; when the heat of the metal circuit is relatively high, the combination layer 7 is heated and moves downward, and the combination layer 7 presses down on the metal corrugated plate 12, causing it to deform, so that the contact areas between the metal corrugated plate 12 and the combination layer 7 and the heat-conductive bottom plate 17 are all significantly increased, approximately changing from point contact to surface contact; thereby significantly improving the heat exchange efficiency, enabling the metal circuit in this area to have a prominent heat generation power to meet the actual heat dissipation requirements.

[0110] Refer to Figure 6 and Figure 7 As shown in FIGS. 1 and 2, a sealed space 13 is provided inside the plastic base 1. Liquid inlet and outlet holes 14 communicating with the sealed space 13 are opened on the plastic base 1. The inside of the sealed space 13 is filled with a coolant through the liquid inlet and outlet holes 14. An external heat-conductive fin 18 extending to the inside of the sealed space 13 and contacting the coolant is connected to the bottom surface of the heat-conductive bottom plate 17;

[0111] An internal heat-conductive fin 19 is also slidably installed inside the external heat-conductive fin 18. The top end of the internal heat-conductive fin 19 extends upward and is connected to the bottom surface of the combination layer 7. The bottom end of the internal heat-conductive fin 19 extends to the inside of the sealed space 13 and is connected with an extension piece 23. The extension piece 23 is rotatably arranged at the bottom end of the internal heat-conductive fin 19. A flexible bladder 20 is also sleeved on the outer wall of the internal heat-conductive fin 19 extending to the inside of the sealed space 13. The inside of the flexible bladder 20 is filled with a filler 21, and the filler 21 is sodium bicarbonate powder or ether;

[0112] Specifically, when the heat of the internal heat-conducting fin 19 is relatively large, the heat is transferred to the inside of the flexible bladder 20 and contacts the packing 21. After the packing 21 is heated for a long time, it will vaporize and undergo a reversible reaction after returning to a certain temperature. Furthermore, the vaporization of the packing 21 will cause the flexible bladder 20 to expand or contract. The expansion of the flexible bladder 20 can push the internal heat-conducting fin 19 to slide inward into the sealing space 13. On the one hand, it serves as a driving source for triggering the downward movement of the bonding layer 7, enabling the bonding layer 7 to press down the metal corrugated plate 12 after absorbing the temperature of the metal circuit, triggering the deformation of the metal corrugated plate 12 to improve the heat exchange efficiency. On the other hand, it can make the extension piece 23 come into full contact with the coolant inside the sealing space 13, further improving the heat exchange efficiency and achieving a good heat dissipation and protection effect.

[0113] Referring to Figure 7 , the extension piece 23 includes a rotating part rotatably connected to the bottom end of the internal heat-conducting fin 19 and having a disc-shaped structure. The inside of the rotating part is provided with a sliding part that can slide along its radial direction. The sliding part has an inclined surface. On the inner bottom wall of the sealing space 13, there is a trigger member 22 extending upward and corresponding to the position of the extension piece 23. The trigger member 22 has a wedge-shaped block structure, and the inclined surface of the sliding part fits with the inclined surface of the wedge-shaped block.

[0114] Specifically, the extension piece 23 includes a disc-shaped rotating part rotatably connected to the bottom end of the internal heat-conducting fin 19. Inside it, there is a sliding part with an inclined surface that can slide radially. The wedge-shaped block structure of the trigger member 22 on the inner bottom wall of the sealing space 13 fits with the inclined surface of the sliding part. When the internal heat-conducting fin 19 expands and slides downward due to heat, the sliding part contacts the trigger member 22. Due to the action of the inclined surface, the sliding part slides radially, thereby changing the shape of the extension piece 23 and further affecting the heat dissipation effect. This structural design makes the heat dissipation adjustment more sensitive and precise. Through the cooperation of the trigger member 22 and the extension piece 23, the size of the extension piece 23 can be adjusted in a timely manner according to temperature changes, improving the heat dissipation efficiency.

[0115] Referring to Figure 7 , on the outer wall of the extension piece 23, a shape memory alloy sheet 24 with a two-way memory effect is also installed. The shape memory alloy sheet 24 is connected to one end of the sliding part extending outward, and each shape memory alloy sheet 24 is perpendicular to the outer wall of the extension piece 23.

[0116] Specifically, when the temperature of a part of the shape memory metal sheet 24 on the extension sheet 23 reaches the critical temperature, this part of the shape memory metal sheet 24 deforms first and transforms into the high-temperature phase shape. When deforming, the shape memory metal sheet 24 stirs the cooling liquid filled inside the sealed space 13 and drives the extension sheet 23 to rotate around the inner heat conduction fin 19. When the shape memory metal sheet 24 in the high-temperature phase moves to the low-temperature area, it deforms again and transforms into the low-temperature phase shape, and again pushes the extension sheet 23 to rotate. During the rotation of the extension sheet 23, the liquid in the sealed space 13 is stirred and mixed, so that the cooling liquids at different temperatures are quickly balanced and reach the same temperature, thereby playing a role in accelerating heat dissipation.

[0117] As described above, although the present invention has been shown and described with reference to specific preferred embodiments, it should not be construed as a limitation of the present invention itself. Various changes in form and detail may be made without departing from the spirit and scope of the present invention as defined by the appended patent claims.

Claims

1. A voice coil motor base containing a metal circuit formed thereon, characterized in that, Comprising: A metal circuit, which is composed of at least one conductive layer and forms a predetermined circuit pattern through precision stamping and electroplating processes; A plastic base (1), which includes at least one receiving cavity (11) for receiving the metal circuit; A bonding layer (7), which is located between the metal circuit and the plastic base (1) and is used to achieve a tight bond between the metal circuit and the plastic base (1); the metal circuit is embedded in the receiving cavity (11) of the plastic base (1) and is firmly connected to the plastic base (1) through the bonding layer (7).

2. The voice coil motor base with a metal circuit formed as described in claim 1, characterized in that: The metal circuit includes a plurality of parallel and spaced metal branches. One end of each metal branch forms a pin end, and the other end forms a solder pad end. The pin end and the welding end are respectively used for connecting and fixing to electronic components. The thickness of the metal circuit is between 0.05 mm and 0.2 mm, and the line width of the metal circuit is between 0.1 mm and 0.3 mm.

3. The voice coil motor base with a metal circuit formed as described in claim 1, characterized in that: The bottom surface of the plastic base (1) is a plane. In the middle of its bottom surface, a square bottom cavity (2) is recessed. At the four corners of its bottom surface, positioning holes (8) are provided for fixing the plastic base (1). An inner hole (3) is provided at the center of the plastic base (1), and a retaining wall is provided at the upper end of the inner hole (3). Positioning posts (5) are respectively provided at the four corner positions of the upper surface of the plastic base (1). Four corner bosses (4) are also installed on the top surface of the plastic base (1), and a relief hole (10) adapted to the positioning post (5) is provided on the four corner bosses (4); It further includes a positioning seat (6) provided on the inner wall of the four corner bosses (4). A positioning groove for positioning and fixing the welding end of the metal circuit is formed on the positioning seat (6) to ensure the precise position of the metal circuit in the plastic base (1).

4. The voice coil motor base with a metal circuit formed as described in claim 3, characterized in that: A heat-conducting bottom plate (17) is embedded in the inner bottom wall of the plastic base (1). An elastic frame (16) that can deform in the vertical direction is also clamped between the top surface of the heat-conducting bottom plate (17) and the bottom surface of the bonding layer (7); A metal corrugated plate (12) is provided in the heat exchange cavity (15) surrounded by the heat-conducting bottom plate (17), the bonding layer (7) and the elastic frame (16). In the natural state, the upper and lower sides of the metal corrugated plate (12) are respectively in contact with the bonding layer (7) and the heat-conducting bottom plate (17).

5. The voice coil motor base with a metal circuit formed as described in claim 4, characterized in that: The metal corrugated plate (12) is composed of a high heat-conducting metal plate. Its edge is fixed to the outer wall of the retaining wall, and there is a gap between its outer edge and the inner wall of the elastic frame (16) to leave space for the deformation of the metal corrugated plate (12); the wave crest of the metal corrugated plate (12) extending upward is directly below the heat generation point of the metal circuit.

6. A voice coil motor base with a metal circuit formed as described in any one of claims 1-5, characterized in that: A sealed space (13) is provided inside the plastic base (1). An inlet and outlet liquid hole (14) communicating with the sealed space (13) is provided on the plastic base (1). The inside of the sealed space (13) is filled with a coolant through the inlet and outlet liquid hole (14). An external heat-conducting fin (18) extending to the inside of the sealed space (13) and in contact with the coolant is connected to the bottom surface of the heat-conducting bottom plate (17); An inner heat-conducting fin (19) is also slidably installed inside the outer heat-conducting fin (18). The top end of the inner heat-conducting fin (19) extends upward and is connected to the bottom surface of the bonding layer (7). The bottom end of the inner heat-conducting fin (19) extends into the sealing space (13) and is connected to an extension piece (23). The extension piece (23) is rotatably arranged at the bottom end of the inner heat-conducting fin (19). A flexible bag (20) is also sleeved on the outer wall of the inner heat-conducting fin (19) extending into the sealing space (13). The inside of the flexible bag (20) is filled with a filler (21), and the filler (21) is sodium bicarbonate powder or ether.

7. The voice coil motor base with a formed metal circuit as described in claim 6, characterized in that: The extension piece (23) includes a rotating part rotatably connected to the bottom end of the inner heat-conducting fin (19) and having a disc-shaped structure. A sliding part capable of sliding radially along it is arranged inside the rotating part. The sliding part has an inclined surface. A trigger (22) extending upward and corresponding to the position of the extension piece (23) is arranged on the inner bottom wall of the sealing space (13). The trigger (22) has a wedge-shaped structure, and the inclined surface of the sliding part fits with the inclined surface of the wedge.

8. The voice coil motor base with a metal circuit formed as claimed in claim 7, characterized in that: A shape memory alloy sheet (24) with a two-way memory effect is also installed on the outer wall of the extension piece (23). The shape memory alloy sheet (24) is connected to the end of the sliding part extending outward. Each shape memory alloy sheet (24) is perpendicular to the outer wall of the extension piece (23).

9. A preparation method, such as the preparation method of the metal circuit formed voice coil motor base according to any one of claims 1-8, characterized in that: It includes the following steps: Step 1: Prepare a metal circuit; form a predetermined circuit pattern on a metal sheet through precision stamping and electroplating processes; Step 2: Place the metal circuit at a predetermined position in an injection mold through an automated device and close the mold; inject molten plastic material into the mold, and let the plastic material cool and solidify in the mold to form a plastic base containing the metal circuit; Step 3: Take out the plastic base from the mold and perform cutting, tray loading and inspection.

10. A preparation method according to claim 9, characterized in that: In Step 1, the conductive material of the metal circuit layer is one of copper, aluminum or alloy materials, and the accuracy of its circuit pattern is controlled within ±0.1 mm; in Step 2, the plastic material for injection molding is a thermoplastic resin or a thermosetting resin, and this resin chemically bonds or physically adsorbs with the metal circuit during the injection process to form a bonding layer; It also includes a step of surface treatment of the plastic base after Step 3 to improve the appearance quality and durability of the plastic base.

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