Injection molding method of capacitive sensor, Bluetooth capacitive sensor, vehicle handlebar and vehicle

Abstract

The present invention relates to the field of injection molding, and discloses an injection molding method for a capacitance sensor. The sensor is formed by at least two injection moldings. The method divides the sensor into at least three parts from the inside to the outside, namely a PCBA board, an inner mold, and an outer mold. The PCBA board has a capacitance region, and the capacitance region is configured to protrude from the plane where the PCBA board is located. The inner mold has positioning support points. During injection molding, the inner mold is first injection molded. The inner mold covers all regions of the PCBA board except the capacitance region and the inner mold support positioning points. Then, the outer mold is injection molded. The outer mold completely covers the remaining regions not covered by the inner mold and the inner mold. By adopting the design of two low-pressure injection moldings, effective combination of the materials for the first injection molding and the second injection molding is achieved. Through actual measurement and verification, it can pass the 300-hour 60°C water immersion test and the IPX9K waterproof requirement.

Description

Technical Field

[0001] The present invention relates to the field of injection molding, in particular to low-pressure injection molding, including an injection molding method of a capacitive sensor, in particular to a Bluetooth capacitive sensor and a handlebar for the Bluetooth capacitive sensor, and also in particular to a vehicle including a handlebar with a Bluetooth capacitive sensor. Background Art

[0002] In the current digital key industry, door handles are the best choice for Bluetooth signals because they are located close to the center of the vehicle and are covered with plastic. In order to meet wind resistance, styling and other requirements, more and more car manufacturers choose to use hidden door handles. Since the space for arranging sensors in hidden handles is small, the width is only 18-20mm and the thickness is only 7-8mm. In addition, Bluetooth capacitive sensors generally need to arrange 6 functional lines, including power, ground, CANH, CANL, capacitor hard line, and left and right identification feet. However, the waterproof connectors on the current market are difficult to meet the size requirements, so they are often arranged in the form of a swing line. However, due to the special shape of the handle, it is impossible to set up good drainage conditions. There will be gaps in the bottom cover of the handle, and a disassembly port is usually reserved. Water can enter from the gaps in the bottom cover and the disassembly port. Water will accumulate in the door handle cavity, causing a high degree of penetration of the electronic components inside the handle, greatly increasing the test of waterproofing.

[0003] However, the Bluetooth capacitive sensors arranged on the door handles mainly use two processes: potting and low-pressure injection molding for waterproofing, and some use laser welding plus dispensing or dispensing processes. If the dispensing solution is adopted, it is difficult for the wiring harness and the shell to form a good combination through dispensing, and the hidden door handle has more movements, including translational push-out, unfolding and manual side pulling, which will cause the wiring harness to move. After the wiring harness moves repeatedly, it is easy to have poor dispensing seals and cause water ingress. If the glue pouring solution is adopted, a higher level of waterproofing can be met under the premise of proper material selection and matching, but due to the complex glue pouring process, it is easy to generate trapped air and form bubbles in uniformly thick and small positions, and capacitive touch has strict consistency requirements on the dielectric constant of the touch area medium, and does not allow bubbles in a larger range of lines, so it is generally necessary to cooperate with vacuum equipment to achieve the effect of removing bubbles. The process is complex and the cost is high.

[0004] Low-pressure injection molding is an injection molding technology that works by heating the thermoplastic material to a molten state and then injecting it into the mold through an injection molding machine to form the desired product under a certain pressure.

[0005] Although the low-pressure injection molding process is simple and the molding speed is fast, it is limited by the bonding properties of the materials. When a plastic shell plus low-pressure injection molding solution is used, actual measurements show that it cannot pass higher-level waterproof tests than IPX7, such as IPX8, IPX9K, etc.

[0006] Therefore, in order to overcome the above problems, the applicant designs a method of injection molding a capacitive sensor by means of two - stage low - pressure injection molding. Summary of the Invention

[0007] The object of the present invention is to solve the above - mentioned technical problems, and the technical solution adopted is: in the first aspect, the present application provides an injection - molding method for a capacitive sensor. The sensor is injection - molded at least twice. The method divides the sensor into at least three parts from the inside to the outside: a PCBA board, an inner mold, and an outer mold. Among them, the PCBA board has a capacitive area, and the capacitive area is configured to protrude from the plane where the PCBA board is located. Among them, the inner mold has positioning support points. During injection molding, the inner mold is first injection - molded. The inner mold covers the area of the PCBA board except for the capacitive area and the positioning support points. Then, the outer mold is injection - molded. The outer mold covers the remaining area not covered by the above - mentioned inner mold and the inner mold completely.

[0008] The low - pressure injection - molding process is simple, environmentally friendly, and efficient, and can prevent air bubbles from generating in the capacitive area, effectively ensuring touch consistency.

[0009] In the arrangement of digital keys, the door handle is still a preferred arrangement option. However, for a hidden door handle, since it cannot prevent water from entering itself and is prone to water accumulation, it poses higher requirements for the waterproof design of the sensor. And the integrated capacitive touch function has high requirements for consistency and does not allow large air bubbles to be generated. This design is based on the low - pressure injection - molding process, optimizes its waterproof performance, and adopts a design of two - stage low - pressure injection molding to achieve an effective combination of the materials for the first injection and the second injection.

[0010] And the present application uses secondary low - pressure injection molding, combined with two - stage injection molding of an inner mold and an outer mold. The same material is used for the two - stage molding. After the inner mold is injection - molded, it is placed in the mold of the outer mold and injection - molded again. Under the action of the high temperature and pressure of the mold, excellent bonding property is formed. It is actually measured that the inner and outer molds can withstand a tensile force value of more than 300 N without cracking.

[0011] In some embodiments, the inner mold has a recessed part forming a groove site. When the injection molding of the inner mold is completed, the groove site of the inner mold exposes at least a part of the PCBA board.

[0012] Moreover, the length of the exposed part of the PCBA board from the positioning support point is more than 3 mm.

[0013] The exposed part is a supporting rib position, called a support rib. Its main function is to form a certain gap between the PCBA board and the inner - mold cavity for glue injection. The existence of the support rib enables the glue to fully fill the gap between the PCBA board and the inner - mold cavity, ensuring the quality and accuracy of glue injection.

[0014] In addition, more and denser support ribs can effectively reduce the strain on the PCBA board. Strain is the deformation of a material under the action of force, and excessive strain may cause problems such as cracking or deformation of the PCBA board. Therefore, by increasing the number and density of support ribs, the strength and stability of the PCBA board can be improved, and the impact of strain can be reduced.

[0015] After the inner mold injection molding, the process of outer mold injection molding will be carried out immediately. This has a certain protective effect against electrostatic damage and prevents the PCBA board from being damaged by static electricity during the injection molding process. Static electricity is often destructive to electronic components, and attention needs to be paid to preventing the generation and conduction of static electricity when handling the PCBA board to ensure product quality and reliability.

[0016] Improve the reliability, working temperature control, maintenance efficiency and anti-interference ability of electronic devices, thereby enhancing product quality and performance.

[0017] In some embodiments, the positioning support points are configured as portions extending outward, wherein at least two positioning support points are evenly arranged, and the distance between the two positioning support points is within 50 mm.

[0018] By evenly arranging at least two positioning support points, the position of the PCBA board can be better fixed, and it is used for the positioning and fixing of the outer mold in the second injection molding. Reduce the shaking and displacement of the PCBA board, improve the stability of the entire electronic device, and reduce the instability problems caused under transportation or mechanical vibration conditions.

[0019] By setting two or more positioning support points, better alignment guidance can be provided during the installation process. Operators can ensure the correct placement of the PCBA board according to the positioning support points and align it with other components or connectors. This can improve the assembly accuracy and efficiency, and reduce assembly errors and adjustment steps.

[0020] The evenly arranged positioning support points can provide an even force distribution and reduce local stress concentration on the PCBA board. This helps to reduce the risk of deformation of the board and improve the durability and long-term use reliability of the PCBA board.

[0021] Enhance the stability, assembly accuracy, durability and maintenance convenience of electronic devices. Contribute to improving product quality, reducing the risk of failure, and simplifying the production and maintenance processes.

[0022] In some embodiments, the positioning support points are convex points protruding outward, and the convex points are configured in a hemispherical shape and form point contact with the inner cavity surface of the outer mold core.

[0023] The inner mold support positioning is designed as a hemispherical point, forming a point contact with the inner cavity surface of the outer mold core, minimizing the contact of the inner mold with the outside world. After the outer mold is injection-molded, only the support positioning points of the inner mold are in contact with the outside world, reducing the risk of water ingress.

[0024] Using a positioning support point in the shape of a hemispherical point can provide more precise positioning. The convex point in the shape of a hemisphere can provide a stable positioning position when forming a point contact with the inner cavity surface of the outer mold core, ensuring the accurate positioning and alignment of the PCBA board.

[0025] The convex point in the shape of a hemispherical point can provide a uniform contact pressure distribution. This helps to optimize the force transmission and dispersion, reducing the risk of concentrated stress on the PCBA board. By reasonably distributing the force, local stress concentration can be reduced, improving the durability and reliability of the PCBA board.

[0026] Using a convex point in the shape of a hemispherical point can increase the contact area of the positioning support point. This can improve the ability of the PCBA board to resist vibration and shock. The convex point in the shape of a hemisphere can absorb and disperse the energy of external vibration, reducing the impact on the PCBA board and protecting the integrity of the electronic components.

[0027] The hemispherical point shape enables precise positioning, optimizes force transmission, and enhances the anti-vibration ability, helping to improve the assembly quality and protect the integrity of the PCBA board.

[0028] Preferably, the clearance distance between the capacitor region and the inner cavity surface of the inner mold core is within 0.2 mm.

[0029] Preferably, the clearance distance between the capacitor region and the inner cavity surface of the outer mold core is between 0.9 mm and 1 mm.

[0030] The capacitance touch increment value is inversely proportional to the sensing distance, and the sensing distance should be minimized. Since there is a minimum wall thickness requirement for low-pressure injection molding, which is about 0.9 mm, the capacitor region should have a clearance of within 0.2 mm from the inner cavity surface of the inner mold core to prevent the glue from flowing into this region. The outer mold completely encloses the capacitor region, and the distance between the inner cavity of the outer mold core and the capacitor region should be 0.9 mm - 1 mm. The wall thickness here is relatively thin, and an exhaust insert should be made to avoid air entrapment, which may cause incomplete filling and water leakage from the inner mold due to insufficient injection.

[0031] In addition, effectively reduce the movement and vibration of the capacitor during installation and use. This can avoid problems such as collision, damage, or unstable contact of the capacitor, improving the reliability and service life of the capacitor. An appropriate clearance distance can play a role in isolation and shielding, reducing the influence of external electromagnetic interference on the capacitor.

[0032] Improve the assembly accuracy and consistency. An appropriate clearance distance helps to accurately place the capacitor and make it closely fit with the inner cavity surface of the mold core, improving the assembly accuracy and reliability of the PCBA board.

[0033] Suitable space can also be provided to optimize the heat dissipation effect. An appropriate gap distance can promote air flow, improve the heat dissipation efficiency, effectively reduce the temperature of the capacitor, and extend its service life and performance stability.

[0034] In a second aspect, the present application provides a Bluetooth capacitive sensor, which is injection molded by the above method.

[0035] In a third aspect, the present application provides a vehicle handlebar, which includes a housing and the above Bluetooth capacitive sensor.

[0036] In a fourth aspect, the present application provides a vehicle, which includes a vehicle body and the above vehicle handlebar. Description of the Drawings

[0037] Figure 1 is an exploded view of a capacitive sensor provided by some embodiments of the present invention.

[0038] Figure 2 is a sample diagram of a capacitive sensor applied to a vehicle handlebar provided by some embodiments of the present invention.

[0039] Figure 3 is a schematic diagram after the first injection molding of the inner mold provided by some embodiments of the present invention.

[0040] Figure 4 is Figure 3 an enlarged view of part A in

[0041] Figure 5 is an experimental diagram of step 1 of the IPX9K test on the sample.

[0042] Figure 6 is an experimental diagram of step 2 of the IPX9K test on the sample.

[0043] Figure 7 is an experimental diagram of step 3 of the IPX9K test on the sample.

[0044] Figure 8 is an experimental diagram of step 4 of the IPX9K test on the sample.

[0045] In the figure: PCBA board 1, inner mold 2, outer mold 3, capacitive region 4, positioning support point 5, slot position point 6, exposed part of the PCBA board 7, silicone pad 8, sample 9. Detailed Embodiments

[0046] The present invention will be further described below in conjunction with the drawings and embodiments. The positional relationships described in the text are in the same direction as the positional relationships of the drawings themselves. For the convenience of narration, they do not limit the structure of the present invention.

[0047] In this embodiment, the double low-pressure injection molding process is adopted. The PCBA board 1 has a protruding capacitor area 4, called a capacitor pad, for soldering capacitors, such as Figure 1 shown. First, the inner mold 2 is injection molded. The inner mold covers the PCBA board. The extended part of the outer surface of the injection-molded inner mold has positioning support points 5, which are set in the shape of hemispherical points and form point contact with the inner cavity surface of the outer mold core. Of course, they can also be in the shape of a cone or the like. At the same time, the inner mold forms an inwardly recessed part, which is a groove site 6. The structure of the inner mold is as Figure 3 shown. The groove site exposes the PCBA board. As Figure 4 stated, the inner mold 2 presses on the exposed part 7 of the PCBA board. The inner mold covers the areas of the PCBA board except for the capacitor area and the positioning support points. The glue thickness on both sides of the inner mold PCBA board is evenly arranged to avoid warping and damage caused by uneven shrinkage of the glue after injection molding. Then, the outer mold 3 is injection molded, and the outer mold 3 covers the remaining areas not covered by the above inner mold and completely covers the inner mold. A silica gel pad 8 is also provided on the outer surface of the outer mold 3 corresponding to the position of the capacitor area 4.

[0048] Specifically, two positioning support points 5 are provided on both sides of the inner mold, and the distance between the two is L1 = 50 mm. Of course, in Figure 3 shown, the positioning support points 5 are evenly arranged on the upper surface of the inner mold, and symmetrical and corresponding positioning support points can be provided on the upper surface, lower surface and other side edges of the inner mold. Among them, the length of the exposed part of the PCBA board from the positioning support points in Figure 3 is L2 = 3 mm.

[0049] In addition, in the process requirements of this example, the clearance distance between the capacitor area and the inner cavity surface of the inner mold core is limited to 0.2 mm. The clearance distance between the capacitor area and the inner cavity surface of the outer mold core is 0.9 mm.

[0050] The PCBA board is first connected to the PVC-SR and PVC wire harnesses. Through the double low-pressure injection molding, the method of first injection molding the inner mold and then injection molding the outer mold is used to form a sample 9 as Figure 2 shown.

[0051] Now, the following two waterproof experiments are carried out on the above sample.

[0052] Experiment 1, IPX9K test, a rain spray experiment to measure the waterproof ability of the sample.

[0053] In the IPX9K test, the device will be exposed to high-pressure water jets to simulate harsh environmental conditions, such as extreme rainy days or water pressures that may be encountered during the cleaning process. During the test, the water flow is sprayed at high speed and will be swept at different angles to ensure that the device can effectively prevent water penetration.

[0054] Experimental steps (such as Figures 5 - 8As described): Step 1, confirmation of the prototype appearance before the experiment: sample appearance inspection, sample function inspection.

[0055] Step 2: Place the samples in the IPX9K rain test chamber.

[0056] Step 3, set the spray flow, pressure, time and angle, etc., and conduct the experiment.

[0057] Step 4: Confirm the appearance of the prototype after the experiment: sample appearance inspection, sample function inspection.

[0058] Table 1 IPX9K test results

[0059] Experiment 2, high temperature water test.

[0060] The waterproof performance of the samples was tested by soaking them in water at 60° for different periods of time.

[0061] Sample status: Model A: secondary injection molding, PCBA without conformal coating; Model B: secondary injection molding, PCBA with conformal coating. “Without conformal coating” means that no waterproof, dustproof or moisture-proof coating materials are used in the manufacturing process of PCBA. Conformal coating is a special coating that is often used to protect electronic devices from erosion by water, dust and humid environments.

[0062] Test conditions:

[0063] 1. Measure after soaking in salt water for 1 hour.

[0064] 2. No electricity, soak in water, water temperature 60 degrees, 30 days, test every day. (Only some days are shown in the table)

[0065] Table 2 Test data results of Model A

[0066] Table 3 Test data results of Model B

[0067] Actual tests have verified that it can pass the IPX9K waterproof requirement and 300 hours of 60°C water immersion verification.

[0068] The present invention is not limited to the above-mentioned embodiments, and various changes can be made within the knowledge scope of ordinary technicians in this field without departing from the purpose of the present invention.

Claims

1. Injection molding method of a capacitive sensor, characterized in that: The sensor is formed by at least two injection molding processes. The method divides the sensor into at least three parts from the inside to the outside, namely the PCBA board, the inner mold, and the outer mold. Among them, the PCBA board has a capacitance area, and the capacitance area is configured to protrude from the plane where the PCBA board is located. Among them, the inner mold has positioning support points. During injection molding, the inner mold is first injection molded, and the inner mold covers the area of the PCBA board except for the capacitance area and the positioning support points. Then, the outer mold is injection molded, and the outer mold covers the remaining area not covered by the above-mentioned inner mold and the inner mold completely. At the same time, both the injection molding of the inner mold and the injection molding of the outer mold adopt the low-pressure injection molding method and use the same material.

2. The injection molding method of the capacitive sensor according to claim 1, characterized in that: The inner mold has a recessed part to form a groove site. When the injection molding of the inner mold is completed, at least a part of the PCBA board is exposed by the groove site of the inner mold.

3. The injection molding method of the capacitive sensor according to claim 2, wherein: The length of the exposed part of the PCBA board from the positioning support point is more than 3 mm.

4. The injection molding method of the capacitive sensor according to claim 1, characterized in that: The positioning support points are configured as parts extending outward. Among them, at least two positioning support points are evenly arranged, and the distance between the two positioning support points is within 50 mm.

5. The injection molding method of the capacitive sensor according to claim 4, characterized in that: The positioning support points are convex points protruding outward, and the convex points are configured in the shape of hemispherical points, forming point contact with the inner cavity surface of the outer mold core.

6. The injection molding method of the capacitive sensor according to claim 1, characterized in that: The clearance distance between the capacitance area and the inner cavity surface of the inner mold core is within 0.2 mm.

7. The injection molding method of the capacitive sensor according to claim 1, characterized in that: The clearance distance between the capacitance area and the inner cavity surface of the outer mold core is between 0.9 mm and 1 mm.

8. A Bluetooth capacitive sensor, characterized in that, It is injection molded by the method according to any one of claims 1 to 7.

9. A vehicle handlebar, characterized in that, It includes a housing and the Bluetooth capacitance sensor according to claim 8.

10. A vehicle, characterized in that, It includes a vehicle body and the vehicle handle according to claim 9.

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