CN108511153B - Wireless charging FPC coil and manufacturing method thereof - Google Patents

Abstract

The invention provides a wireless charging FPC coil and a manufacturing method thereof. The wireless charging FPC coil includes an FPC substrate. The thickness of the FPC substrate is not greater than 500um. There are multiple loops of annular lines on the circumferential surface of the FPC substrate. Two adjacent annular circuits are arranged on the circumferential surface of the FPC substrate. The gap between lines ranges from 30um to 40um, and there is AD glue and resin ink in the gap. The manufacturing method of the wireless charging FPC coil is to obtain a copper substrate through development, and obtain an FPC substrate through electroplating. The thickness of the FPC substrate is not greater than 500um. The FPC substrate is laser-lased to form a ring line, and the gap between two adjacent ring lines is The range is 30um-40um; AD glue and resin ink are filled in the gap to make the position of the ring line relatively fixed and the size of the gap relatively fixed. When the FPC substrate area is the same, the invention improves the efficiency of wireless charging FPC coil production. Stability, improved manufacturing accuracy and transmission efficiency and transmission speed of wireless charging FPC coil.

Description

A wireless charging FPC coil and its manufacturing method

Technical field

The present invention relates to the field of wireless charging technology, and in particular, to a wireless charging FPC coil and a manufacturing method thereof.

Background technique

Wireless charging technology is a method that uses the principle of near-field induction to transfer power between two induction coils. The transmission power and transmission speed of the wireless charging coil are key factors that affect charging efficiency. The existing methods of manufacturing induction coils generally use the etching method and the copper wire coil winding method. The etching method uses the conventional FPC production process to cut the raw materials to obtain a copper substrate, and use a drill to drill the copper substrate. , attach dry film to the front and back sides of the copper substrate, place the copper substrate on the negative film, align it up and down, and then expose it to transfer the circuit to the copper substrate through the action of the dry film, and then treat it with a developer. The unexposed dry film is washed away and the dry film that has undergone polymerization reaction after exposure is retained, so that the circuit is basically formed. Finally, at a temperature of 45°C-50°C, the etching solution is sprayed evenly onto the surface of the copper substrate through the nozzle. , an oxidation-reduction reaction occurs with the copper that is not protected by the etching resist, and the unnecessary copper is reacted away. After the substrate is exposed, the circuit is formed through a stripping process. This process is referred to as cutting → drilling → dry film → dry film bit → exposure → development → etching, that is to say, this technology uses the image transfer method to directly etch out the required shape of the induction coil. Since this method uses an etching operation, the copper substrate is directly used as the FPC substrate, so as the etched copper substrate The plate thickness is generally required to be less than 70um. If the thickness of the copper substrate is too large, etching cannot be performed, and the distance between two adjacent etched ring lines is generally greater than 50um. Therefore, the transmission power and transmission speed of the wireless charging coil manufactured by it Smaller; while the copper wire coil winding method uses copper wire to directly wind the coil, its size is generally larger, and the spacing between the ring lines is larger, and because the copper wire coil is easy to deform, the spacing between the ring lines is not fixed. Therefore, the transmitting power of the copper wire coil is small and the transmission efficiency is also low. In summary, the existing manufacturing methods of induction coils have low manufacturing precision, which leads to the problems that the manufactured induction coils have low transmission power and transmission speed, large spacing between ring lines, and easy deformation of the coils.

Contents of the invention

The present invention provides a method for manufacturing a wireless charging FPC coil. The manufacturing method has high manufacturing precision. The distance between the ring lines of the manufactured wireless charging FPC coil is small, and the transmission power and transmission speed are high.

The technical solution adopted by the present invention is a manufacturing method of wireless charging FPC coil, which includes the following steps:

S1. Electroplating the developed ring-shaped copper substrate to increase its thickness to form an FPC substrate. The thickness of the FPC substrate is not greater than 500um;

S2. Apply laser to the FPC substrate, and cut out circular lines from the center of the circle of the FPC substrate outwards. The gap between two adjacent circular lines is in the range of 30um-40um and the gap between the two adjacent circular lines is 30um-40um. There are connecting lines between the ring lines, and the connecting lines extend along the radial direction of the FPC substrate. Each ring line includes a plurality of arc-shaped line segments, and the head and tail ends of the arc-shaped line segments are respectively fixedly connected to Connect online;

S3. Attach a high-viscosity carrier film and a high-temperature dissociation film to the upper and lower surfaces of the FPC substrate respectively. The side where the high-viscosity carrier film is located is the upper surface of the FPC substrate, and the side where the high-temperature dissociation film is located is the FPC. On the lower bottom surface of the substrate, the viscosity of the high-viscosity carrier film is 80g/25mm, and the viscosity of the high-temperature dissociation film is 1000g/25mm;

S4. Use laser or punching to open a window at the position corresponding to the connecting line on the high-viscosity carrier film to expose the connecting line, and then use laser to cut off the connection between the two adjacent annular line gaps. line, making the trajectory of the circular line a complete and continuous circle;

S5. Take a piece of protective film, and apply a layer of AD glue on the adhesive surface of the protective film, then peel off the high-viscosity carrier film on the upper surface of the FPC substrate, put the AD glue side of the protective film facing down, and remove the protective film as a whole Attached to the upper surface of the FPC substrate;

S6. Press the upper surface of the protective film with a rapid laminating machine to fill the gaps between the ring lines with AD glue;

S7. Make the bottom surface of the FPC substrate face up, and bake the FPC substrate for the first time. The first baking reduces the viscosity of the high-temperature dissociation film, then removes the high-temperature dissociation film, and then uses vacuum The printing machine prints the resin ink in the gap between the ring lines, and then bakes it for a second time. The second baking solidifies the resin ink, and finally uses a ceramic brush to remove the resin ink residue that is higher than the surface of the ring line; The temperature range of the first baking and the second baking is 110℃-150℃ respectively, the first baking time is 3min-5min, and the second baking time is 30min-60min;

S8. Attach a protective film to the lower surface of the FPC substrate.

After adopting the above technical solution, the present invention has the following advantages compared with the existing technology:

In the present invention, a process combining etching and electroplating is used to increase the overall thickness of the FPC substrate and improve the transmission efficiency. The laser is used to cut the ring line to reduce the gap between two adjacent ring lines and improve the transmission efficiency and speed. In order to prevent the spring effect, connecting lines are set up during the laser cutting process to make the entire product more stable during laser cutting. Furthermore, AD glue and resin ink are filled in the gaps between the ring lines to make the ring lines more stable. The position is relatively fixed, and the gap size is relatively fixed, which can effectively prevent the ring line from deforming and affecting the gap size. When the FPC substrate area is the same, the present invention improves the stability of the wireless charging FPC coil during production, improves manufacturing accuracy and wireless charging. FPC coil transmission efficiency and transmission speed.

As an improvement, in the S2 step, the FPC substrate is lasered, including the following steps: First, according to the overall thickness of the FPC substrate, determine the specific value of half of its thickness and adjust the laser cutting depth , so that the cutting depth of the laser is equal to half the thickness of the FPC substrate; in the second step, the FPC substrate is laser-cut from the upper and lower surfaces twice, that is, one side is cut, and then Cut the other side so that the ring circuits on both sides are connected to each other to form a complete ring circuit. Since the thickness of the FPC substrate in the present invention is relatively large, in order to facilitate cutting, the FPC substrate is cut separately on both sides.

As an improvement, the thickness of the copper substrate ranges from 10 to 50um. The greater the thickness of the copper substrate, the more difficult it is to cut and drill holes, which affects the processing accuracy of the copper substrate.

As an improvement, the thickness of the FPC substrate is 500um, the thickness range of the protective film is 30-40um, the thickness of the AD glue is 30-50um, and the thickness of the resin ink is 450um-470um, where the AD glue The fluidity is small, and the thickness range of the adhesive layer formed by it is controllable, which facilitates subsequent calculation of the thickness of the printing resin ink.

As an improvement, the number of connecting lines ranges from 8 to 40. The greater the number of connecting lines, the more stable the connection relationship between the ring lines is, which facilitates the subsequent attachment of the high-viscosity carrier film and the high-temperature dissociation film.

The invention also provides a wireless charging FPC coil, which includes an FPC substrate. The thickness of the FPC substrate is not greater than 500um. A multi-turn annular circuit is provided on the circumferential surface of the FPC substrate. Two adjacent annular circuits are provided. The gap range is 30um-40um, and AD glue and resin ink are provided in the gap.

After adopting the above technical solution, the present invention has the following advantages compared with the existing technology:

The thickness of the FPC substrate in the present invention is relatively large, the gap between the ring lines is small, the transmission speed and transmission efficiency are high, and AD glue and resin ink are provided in the gap to support and fix the ring lines on both sides of the gap. Prevent the ring line from deforming and increase the stability and strength of the wireless charging FPC coil.

As an improvement, the thickness of the FPC substrate is 500um, the thickness of the AD glue is 30-50um, the thickness of the resin ink is 450um-470um, and the thickness of the FPC substrate is about 500um. In order to ensure transmission efficiency, Based on the transmission speed, its weight is lighter and easier for users to carry.

As an improvement, the upper and lower surfaces of the FPC substrate are respectively provided with protective films to protect the wireless charging FPC coil, prevent the ring circuit from being scratched, and facilitate the transportation of the wireless charging FPC coil.

As an improvement, the FPC substrate is laser cut to form the ring circuit, and the cutting accuracy is high.

Description of drawings

Figure 1 shows the FPC substrate that changes with the production process of wireless charging FPC coils.

Figure 2 is a schematic diagram of the overall structure of the wireless charging FPC coil.

Figure 3 is a cross-sectional view of the gap

As shown in the picture, 1. Copper substrate, 2. FPC substrate, 3. Ring line, 31. Arc line segment, 4. Gap, 5. Connecting wire, 6. AD glue, 7. Resin ink, 8. High viscosity load bearing Film, 9. Protective film.

Detailed ways

As shown in Figure 1, a method of manufacturing a wireless charging FPC coil includes the following steps:

S1. Electroplating the developed ring-shaped copper substrate 1 to increase its thickness to form an FPC substrate 2. The thickness of the FPC substrate 2 is no more than 500um. (The developed ring-shaped copper substrate in the above steps refers to the raw material. It is obtained after the processes of cutting, drilling, dry film application, alignment, exposure and development. The order of each step in cutting, drilling, dry film application, alignment, exposure and development can be carried out according to actual production requirements. Adjustment);

S2. Apply laser to the FPC substrate 2, and cut out the ring circuits 3 from the center of the circle of the FPC substrate 2. During cutting, the gap 4 between the two adjacent ring circuits 3 ranges from 30um to 40um and is adjacent to each other. There is a connecting line 5 between the two ring lines 3. The connecting line 5 extends along the radial direction of the FPC substrate 2. Each ring line 3 includes a plurality of arc line segments 31. The head and tail ends of the arc line segments 31 They are respectively fixedly connected to the connecting wire 5;

S3. Attach the high-viscosity carrier film 8 and the high-temperature dissociation film to the upper and lower surfaces of the FPC substrate 2 respectively. The side where the high-viscosity carrier film 8 is located is the upper surface of the FPC substrate 2, and the side where the high-temperature dissociation film is located is the FPC substrate 2. On the lower bottom surface, the viscosity of the high-viscosity carrier film 8 is 80g/25mm, and the viscosity of the high-temperature dissociation film is 1000g/25mm;

S4. Use laser or punching to open the window at the position corresponding to the connecting line 5 on the high-viscosity carrier film 8 to expose the connecting line 5, and then use laser to cut off the connecting line between the gaps 4 of the two adjacent ring lines 3. 5. Make the trajectory of ring line 3 a complete and continuous circle;

S5. Take a piece of protective film 9, and apply a layer of AD glue 6 on the adhesive surface of the protective film 9, then peel off the high-viscosity carrier film 8 on the upper surface of the FPC substrate 2, and place the AD glue side of the protective film facing Attach the protective film 9 to the upper surface of the FPC substrate 2 as a whole. In this step, due to the low viscosity of the high-viscosity carrier film 8, it can be manually removed;

S6. Press the upper surface of the protective film 9 with a rapid laminating machine to fill the gap 4 between the ring lines 3 with the AD glue 6. The AD glue 6 has a certain fluidity. Use a hot pressing roller to press the AD glue 6 Apply a certain pressure, and at the same time, the temperature provided by the hot pressing roller can slow down the solidification time of AD glue 6 so that it can be fully filled into gap 4;

S7. Make the bottom surface of the FPC substrate 2 face up, and bake the FPC substrate 2 for the first time. The first baking reduces the viscosity of the high-temperature dissociation film, then removes the high-temperature dissociation film, and then uses vacuum printing. The machine prints the resin ink 7 in the gap 4 between the ring lines 3, and then bakes it for a second time. The second baking solidifies the resin ink 7. Finally, a ceramic brush is used to remove the resin ink that is higher than the surface of the ring line 3. 7 residue; the temperature range of the first baking and the second baking is 110℃-150℃ respectively, the first baking time is 3min-5min, the second baking time is 30min-60min; in In this step, because the high-temperature dissociation film has a high viscosity and cannot be removed manually, the high-temperature dissociation film needs to be baked first to make it less viscous;

S8. Attach the protective film 9 to the lower bottom surface of the FPC substrate 2 .

In the present invention, the materials of the high-viscosity carrier film and the high-temperature dissociation film are both carrier films, and their viscosities are different.

In the S2 step, the FPC substrate 2 is laser cut. The laser has good light condensation, the cutting trajectory is easy to control, and the laser cutting accuracy is high. Laser cutting includes two methods. The first one is the two-sided cutting method: first, According to the overall thickness of FPC substrate 2, determine the specific value of half of its thickness and adjust the laser cutting depth so that the laser cutting depth is equal to one-half of the thickness of FPC substrate 2. Secondly, divide FPC substrate 2 into two Laser cutting is performed from the upper and lower surfaces respectively, that is, one side is cut, and then the other side is cut, so that the ring lines 3 on both sides are connected to each other to form a complete ring line 3. The second method is to completely cut one side. , that is, the laser is used to directly cut through the entire FPC substrate 2 at one time, thereby forming each ring of ring circuit 3. This method requires a large power requirement for the laser used in the laser.

The thickness of the copper substrate 1 for development ranges from 10 to 50um, which is convenient for making an initial model for electroplating.

As shown in Figure 3, in the present invention, the protective film 9 is a CVL protective film with a thickness range of 30-40um, the thickness of the AD glue 6 is 30-50um, the thickness of the resin ink 7 is 450um-470um, and the thickness of the resin ink 7 is 450um-470um. The thickness of varies with the thickness of the FPC substrate 2. The number of connecting wires 5 ranges from 8 to 40. For example, connecting wires 5 are 8, 24, 36, etc. The value of connecting wires 5 depends on the width of ring line 3. The smaller the width, the more connecting wires 5 are needed. , the connecting wire 5 is used to prevent the ring line 3 from breaking.

As shown in Figures 2 and 3, the present invention also provides a wireless charging FPC coil, including an FPC substrate 2. The thickness of the FPC substrate 2 is not greater than 500um. A multi-turn annular line 3 is provided on the circumferential surface of the FPC substrate 2. , the gap 4 between two adjacent ring lines 3 ranges from 30um to 40um, and the gap 4 is filled with AD glue 6 and resin ink 7 . The thickness of FPC substrate 2 is 500um, the filling thickness of AD glue 6 is 30-50um, and the filling thickness of resin ink 7 is 450um-470um. Protective films 9 are respectively provided on the upper and lower surfaces of FPC substrate 2, and the ring circuit 3 therein is Obtained by laser cutting, the smaller the gap 4 between the ring lines 3 is, the more the number of ring lines 3 will be under the same area of the FPC substrate, which can improve the signal transmission efficiency.

The invention has a simple structure, the thickness of the FPC substrate 2 is large, and the gap 4 between the ring lines 3 is small. When the power is turned on, the wireless charging FPC coil at the transmitting end can efficiently convert electrical energy into magnetic energy, thereby generating a magnetic field. , the wireless charging FPC coil at the receiving end can sense the magnetic field, thereby converting magnetic energy into electrical energy to achieve the purpose of charging the mobile phone. Therefore, within the same area, the present invention can convert electrical energy into magnetic energy more efficiently and improve transmission power and transmission speed.

The above embodiments are only used to illustrate the technical solution of the present invention, but not to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art will understand that they can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent substitutions for each part of the technical features. These modifications or substitutions do not cause the essence of the corresponding technical solutions to depart from the scope of the technical solutions of the embodiments of the present invention.

Claims (9)

1. A method of manufacturing a wireless charging FPC coil, which is characterized by including the following steps: S1. Electroplating the developed ring-shaped copper substrate (1) to increase its thickness to form an FPC substrate (2). The thickness of the FPC substrate (2) is no more than 500um; S2. Apply laser to the FPC substrate (2), and cut out circular circuits (3) from the center of the circle of the FPC substrate (2) outwards. The gap between the two adjacent circular circuits (3) The gap (4) ranges from 30um to 40um and there is a connecting line (5) between the two adjacent annular lines (3). The connecting line (5) extends along the radial direction of the FPC substrate (2). A ring of annular lines (3) includes a plurality of arc-shaped line segments (31), the head ends and tail ends of the arc-shaped line segments (31) are respectively fixedly connected to the connecting line (5); S3. Attach a high-viscosity carrier film (8) and a high-temperature dissociation film to the upper and lower surfaces of the FPC substrate (2) respectively. The side where the high-viscosity carrier film (8) is located is the upper surface of the FPC substrate (2). The side where the high-temperature dissociation film is located is the lower surface of the FPC substrate, the viscosity of the high-viscosity carrier film (8) is 80g/25mm, and the viscosity of the high-temperature dissociation film is 1000g/25mm; S4. Use laser or punching to open a window at the position corresponding to the connecting line (5) on the high-viscosity carrier film (8) to expose the connecting line (5), and then use laser to cut off the adjacent The connecting line (5) between the gaps (4) of the two ring lines (3) makes the trajectory of the ring line (3) become a complete and continuous circle; S5. Take a piece of protective film (9), and apply a layer of AD glue (6) on the adhesive surface of the protective film, then peel off the high-viscosity carrier film (8) on the upper surface of the FPC substrate (2), and remove the protective film. Attach the entire protective film to the upper surface of the FPC substrate (2) with the AD glue side facing down; S6. Press the upper surface of the protective film (9) with a rapid laminating machine to fill the gap (4) between the ring lines (3) with the AD glue (6); S7. Make the lower surface of the FPC substrate (2) face up, and bake the FPC substrate (2) for the first time. The first baking reduces the viscosity of the high-temperature decomposition film, and then removes the high-temperature decomposition film. Separate the film, and then use a vacuum printer to print the resin ink (7) in the gap (4) between the ring lines (3), and then bake it for the second time. The second baking solidifies the resin ink (7). Finally, use a ceramic brush to brush off the resin ink (7) residue that is higher than the surface of the ring line (3); the temperature range of the first baking and the second baking is 110°C-150°C respectively. The first baking time is 3min-5min, the second baking time is 30min-60min; S8. Attach the protective film (9) to the lower surface of the FPC substrate (2). 2. The manufacturing method of wireless charging FPC coil according to claim 1, characterized in that, in the step S2, lasering the FPC substrate includes the following steps: first, according to the FPC substrate (2 ), determine the specific value of one-half of the thickness and adjust the cutting depth of the laser so that the cutting depth of the laser is equal to one-half of the thickness of the FPC substrate (2); the second step, The FPC substrate (2) is laser-cut from the upper and lower surfaces twice, that is, one side is cut, and then the other side is cut, so that the annular circuits (3) on both sides are connected to each other to form a complete circle. Loop line(3). 3. The manufacturing method of wireless charging FPC coil according to claim 1, characterized in that the thickness of the copper substrate (1) ranges from 10-50um. 4. The manufacturing method of wireless charging FPC coil according to claim 1, characterized in that the thickness of the FPC substrate (2) is 500um, and the thickness range of the protective film (9) is 30-40um. The thickness of the AD glue (6) is 30-50um, and the thickness of the resin ink (7) is 450um-470um. 5. The manufacturing method of wireless charging FPC coil according to claim 1, characterized in that the number of connecting wires (5) ranges from 8 to 40. 6. A wireless charging FPC coil manufactured according to any one of claims 1 to 5, characterized in that it includes an FPC substrate (2), and the thickness of the FPC substrate (2) is not greater than 500um. The circumferential surface of the above-mentioned FPC substrate (2) is provided with multiple rings of annular circuits (3). The gap (4) between two adjacent annular circuits (3) ranges from 30um to 40um. The gap (4) There are AD glue (6) and resin ink (7). 7. A wireless charging FPC coil according to claim 6, characterized in that: the thickness of the FPC substrate (2) is 500um, the thickness of the AD glue (6) is 30-50um, and the thickness of the AD glue (6) is 30-50um. The thickness of the resin ink (7) is 450um-470um. 8. A wireless charging FPC coil according to claim 6, characterized in that: the upper and lower surfaces of the FPC substrate (2) are respectively provided with protective films (9). 9. A wireless charging FPC coil according to claim 6, characterized in that the FPC substrate (2) is laser cut to form the ring circuit (3).