Method for pasting EMI shielding film and PI reinforcing sheet on flexible circuit board surface

Abstract

This invention provides a method for attaching an EMI shielding film and a PI reinforcing sheet to the surface of a flexible circuit board, comprising the following steps: punching out a first component from an EMI shielding film strip and simultaneously heating the first component to pre-bond it to the flexible circuit board; punching out a second component from a PI strip and simultaneously heating the second component to pre-bond it to the flexible circuit board; further hot-pressing the flexible circuit board in a hot press, wherein the inner surface of the upper platen of the hot press has a first working area and a second working area with a depth difference equal to the thickness difference between the first and second components, and the relatively deeper first working area corresponds to the thicker of the first and second components, and the shallower second working area corresponds to the thinner of the first and second components. In this invention, the first and second components are pre-bonded to the surface of the flexible circuit board to prevent positional shifting of the first and second components during transfer. The simultaneous hot-pressing of the first and second components improves efficiency.

Description

Technical Field

[0001] This invention relates to the field of flexible circuit board manufacturing, and more particularly to a method for attaching EMI shielding film and PI reinforcing sheet to the surface of a flexible circuit board. Background Technology

[0002] Flexible printed circuit boards (FPCs), also known as "flexible boards," are printed circuits made from flexible insulating substrates. Flexible circuits offer excellent electrical performance, meet the design needs for smaller and higher-density installations, and help reduce assembly steps and enhance reliability. They are widely used in fields such as 5G communications, the metaverse, intelligent robots, and new energy vehicles.

[0003] Applying a shielding film to the surface of a flexible circuit board can reduce electromagnetic interference (EMI). Applying polyimide (PI) reinforcing plates to specific areas of the flexible circuit board can increase the strength of those areas and improve the reliability of electrical component connections.

[0004] Existing methods for applying EMI shielding film and PI reinforcing sheets to the surface of flexible printed circuit boards (PCBs) are performed separately. First, a die-cutting machine is used to cut the designed EMI shielding film from a strip of EMI shielding film with hot melt adhesive, and the EMI shielding film is placed on the PCB surface. Then, the PCB is transferred to a hot press and heated to melt the hot melt adhesive on the EMI shielding film, thus adhering the EMI shielding film to the PCB surface. Next, a designed PI reinforcing sheet is cut from a strip of PI material with hot melt adhesive, and the PI reinforcing sheet is placed on the PCB surface. The PCB is then transferred to a hot press again and heated to melt the hot melt adhesive on the PI reinforcing sheet, thus adhering the PI reinforcing sheet to the PCB surface. Alternatively, the PI reinforcing sheet can be applied to the PCB surface first, followed by the EMI shielding film.

[0005] The problem with existing methods is that the EMI shielding film and PI reinforcing sheet are not fixed on the surface of the flexible circuit board because they are not hot-pressed. During the process of transferring the flexible circuit board to the hot press, the positions of the EMI shielding film and PI reinforcing sheet are prone to shift. Hot-pressing the EMI shielding film and PI reinforcing sheet separately is inefficient. Summary of the Invention

[0006] To address at least one problem of the prior art, the present invention provides a method for attaching an EMI shielding film and a PI reinforcing sheet to the surface of a flexible circuit board.

[0007] The method for attaching EMI shielding film and PI reinforcing sheet to the surface of a flexible circuit board is applicable to attaching EMI shielding film and PI reinforcing sheet to a flexible circuit board, and includes the following steps:

[0008] It provides EMI shielding film tape, PI tape and flexible circuit board, wherein one surface of the EMI shielding film tape is covered with a first hot melt adhesive and one surface of the PI tape is covered with a second hot melt adhesive.

[0009] The flexible circuit board is horizontally adsorbed onto the surface of the first adsorption heating platform. The EMI shielding film strip is placed horizontally above the flexible circuit board with the first hot melt adhesive facing downwards. A first punch with a first temperature is used to perform a first punching operation on the EMI shielding film strip to punch out a first component from the EMI shielding film strip. The first punch adsorbs the first component at its end and sends the first component to the surface of the flexible circuit board, then pauses for a first time to pre-bond the first component onto the flexible circuit board.

[0010] The flexible circuit board is horizontally adsorbed onto the surface of the first adsorption heating platform or another second adsorption heating platform. The PI strip is placed horizontally above the flexible circuit board with the second hot melt adhesive side facing down. A second punch with a second temperature is used to perform a second punching operation on the PI strip to punch out a second component from the PI strip. The second punch adsorbs the second component at its end and sends the second component to the surface of the flexible circuit board, then pauses for a second time to pre-bond the second component onto the flexible circuit board.

[0011] The flexible circuit board is transferred to a hot press for hot pressing. The hot press includes an upper pressure plate with a first working area and a second working area. The first working area is opposite to the thicker of the first component and the second component, and the second working area is opposite to the thinner of the first component and the second component. The first working area is deeper than the second working area, and the depth difference is equal to the thickness difference between the first component and the second component.

[0012] In some embodiments, the method of covering the PI material strip with hot melt adhesive is as follows: after bonding the PI material strip and the hot melt adhesive strip, hot pressing is performed at a temperature of 80-100°C and a pressure of 4-8 MPa.

[0013] In some embodiments, the first adsorption heating platform has a heating rod inside, and a plurality of air intake holes are arranged on the surface of the first adsorption heating platform.

[0014] In some embodiments, the first temperature is 100-120°C and the first time is not less than 2 seconds; the second temperature is 100-120°C and the second time is not less than 2 seconds.

[0015] In some embodiments, the first punch has a first hollow inner cavity extending axially, the lower port of the first hollow inner cavity is located on the lower end face of the first punch, the upper port is located on the side wall of the first punch, and the upper port is connected to an air extraction device through a first air suction pipe.

[0016] In some embodiments, the first punch corresponds to the first die, the first die has a first hole that matches the cross-sectional shape of the first punch, the first punch passes through the first hole, the EMI shielding film strip passes laterally through the first die, and the movement path of the first punch intersects with the EMI shielding film strip.

[0017] The upper end of the first punch is mounted on the first mounting block, and one end of the first suction pipe passes through the side of the first mounting block and is threadedly connected to the upper port of the first punch.

[0018] In some embodiments, the second punch has a second hollow inner cavity extending axially, the lower port of the second hollow inner cavity being located on the lower end face of the second punch, the upper port being located on the side wall of the second punch, and the upper port being connected to an air extraction device via an air suction pipe.

[0019] In some embodiments, the second punch corresponds to the second die, the second die has a second hole adapted to the cross-sectional shape of the second punch, the second punch passes through the second hole, the PI strip passes laterally through the second die, and the movement path of the second punch intersects with the PI strip;

[0020] The upper end of the second punch is mounted on the second mounting block, and one end of the second suction pipe passes through the side of the second mounting block and is threadedly connected to the upper port of the second punch.

[0021] In some embodiments, after the first and second components are pre-attached to the surface of the flexible circuit board, a layer of release paper is covered on the surface of the flexible circuit board.

[0022] In some implementations, the second working area is flush with the inner surface of the upper pressure plate, and the first working area is formed as a groove.

[0023] The beneficial effects of this invention are that the first component and the second component are pre-attached to the surface of the flexible circuit board, preventing positional misalignment of the first and second components during the transfer of the flexible circuit board. Simultaneous thermoforming of the first and second components improves efficiency. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the structure of an EMI shielding film strip according to an embodiment of the present invention.

[0025] Figure 2 This is a schematic diagram of the structure of a PI strip according to an embodiment of the present invention.

[0026] Figure 3 This is a schematic diagram of performing the first punching operation according to an embodiment of the present invention.

[0027] Figure 4 This is a schematic diagram of the first punch structure according to an embodiment of the present invention.

[0028] Figure 5 This is a schematic diagram illustrating the execution of the second punching operation according to an embodiment of the present invention.

[0029] Figure 6 This is a schematic diagram of the second punch structure according to an embodiment of the present invention.

[0030] Figure 7 This is a schematic diagram of the hot pressing operation of an embodiment of the present invention when the upper pressure plate is not closed.

[0031] Figure 8 This is a schematic diagram of the upper pressure plate being closed during the hot pressing operation according to an embodiment of the present invention.

[0032] Symbol explanation:

[0033] EMI shielding film tape 1, PI tape 2, flexible circuit board 3, first hot melt adhesive 4, second hot melt adhesive 5, first adsorption heating platform 6, first punch 7, first component 8, second adsorption heating platform 9, second punch 10, second component 11, upper pressure plate 12, first working area 13, second working area 14, first die 15, first hole 16, first hollow cavity 17, first suction pipe 18, first mounting block 19, second die 20, second hole 21, second hollow cavity 22, second suction pipe 23, second mounting block 24, lower pressure plate 25 Detailed Implementation

[0034] The inventors discovered that existing methods for applying EMI shielding films and PI reinforcing sheets to the surface of flexible circuit boards have shortcomings in two aspects. First, during the transportation of the flexible circuit board to the hot press, the EMI shielding film and PI reinforcing sheet are not fixed on the surface of the flexible circuit board, causing their positions to shift. Second, the EMI shielding film and PI reinforcing sheet have different thicknesses, and since the upper and lower plates of the hot press are both flat steel plates, if the EMI shielding film and PI reinforcing sheet are pressed together simultaneously, the thinner material will not be pressed firmly due to insufficient pressure. If pressure is forcibly applied, the thicker material will overflow with adhesive. In other words, the existing method requires one of the EMI shielding film and PI reinforcing sheet to be punched and pressed together first, and then the other two to be punched and pressed together.

[0035] To address the shortcomings of existing technologies, this invention provides a method for attaching an EMI shielding film and a PI reinforcing sheet to the surface of a flexible circuit board, which is used to attach the EMI shielding film and the PI reinforcing sheet to the flexible circuit board.

[0036] It is understood that the EMI shielding film referred to in the method of the present invention is a sheet or film-like functional material known to those skilled in the art that has the function of shielding electromagnetic interference, and the PI reinforcing sheet is a polyimide sheet used to strengthen the component strength of flexible circuit boards.

[0037] The EMI shielding film and the PI reinforcing sheet are adhered to the same side of the flexible circuit board. For example, both the EMI shielding film and the PI reinforcing sheet can be adhered to the front side of the flexible circuit board, or both can be adhered to the back side. There can be at least one EMI shielding film and one PI reinforcing sheet, or multiple sheets. This is not limited here.

[0038] EMI shielding films and PI reinforcing sheets are not large enough to cover the entire flexible circuit board. Instead, films of appropriate size are selected based on functional requirements. If electromagnetic shielding is required for one or more localized areas on the flexible circuit board, EMI shielding films are applied to those areas; if reinforcement is required for one or more areas on the flexible circuit board, PI reinforcing sheets are applied to those areas.

[0039] The embodiments of the technical solution of this application will now be described in detail with reference to the accompanying drawings. These embodiments are only used to more clearly illustrate the technical solution of this application and are therefore merely examples, and should not be used to limit the scope of protection of this application.

[0040] Please combine Figures 1 to 3 , Figure 5 as well as Figures 7 to 8 The method of attaching EMI shielding film and PI reinforcing sheet to the surface of flexible circuit board 3 is applicable to attaching EMI shielding film and PI reinforcing sheet to flexible circuit board 3, and includes the following steps:

[0041] An EMI shielding film strip 1, a PI strip 2, and a flexible circuit board 3 are provided, wherein one surface of the EMI shielding film strip 1 is covered with a first hot melt adhesive 4, and one surface of the PI strip 2 is covered with a second hot melt adhesive 5.

[0042] The flexible circuit board 3 is horizontally adsorbed onto the surface of the first adsorption heating platform 6. The EMI shielding film strip 1 is placed horizontally above the flexible circuit board 3 with the first hot melt adhesive 4 facing downward. The first punch 7 with a first temperature performs a first punching operation on the EMI shielding film strip 1 to punch out the first component 8 from the EMI shielding film strip 1. The first punch 7 adsorbs the first component 8 at its end and sends the first component 8 to the surface of the flexible circuit board 3 and pauses for a first time to pre-bond the first component 8 onto the flexible circuit board 3.

[0043] The flexible circuit board 3 is horizontally adsorbed onto the surface of the first adsorption heating platform 6 or another second adsorption heating platform 9. The PI strip 2 is placed horizontally above the flexible circuit board 3 with the second hot melt adhesive 5 facing downward. The second punch 10 with a second temperature performs a second punching operation on the PI strip 2 to punch out the second component 11 from the PI strip 2. The second punch 10 adsorbs the second component 11 at its end and sends the second component 11 to the surface of the flexible circuit board 3 and pauses for a second time to pre-bond the second component 11 onto the flexible circuit board 3.

[0044] The flexible circuit board 3 is transferred to a hot press for hot pressing. The hot press includes an upper pressure plate 12, which has a first working area 13 and a second working area 14. The first working area 13 is opposite to the thicker of the first component 8 and the second component 11, and the second working area 14 is opposite to the thinner of the first component 8 and the second component 11. The first working area 13 is deeper than the second working area 14, and the depth difference is equal to the thickness difference between the first component 8 and the second component 11.

[0045] The hot melt adhesive referred to in this invention is not sticky at room temperature, but it softens or melts and becomes sticky when heated to a certain temperature.

[0046] EMI shielding film tape 1 and PI tape 2 are elongated tapes, with a hot melt adhesive film attached to one side of each. Specifically, a first hot melt adhesive 4 is attached to one side of EMI shielding film tape 1, and a second hot melt adhesive 5 is attached to one side of PI tape 2. The first hot melt adhesive 4 and the second hot melt adhesive 5 can be made of the same material or different materials. The thickness of the first hot melt adhesive 4 and the second hot melt adhesive 5 can be the same or different. No limitations are placed on the material or thickness here.

[0047] In some embodiments, the EMI shielding film strip 1 comes with a first hot melt adhesive 4, meaning that the EMI shielding film strip 1 with hot melt adhesive can be purchased directly from the market.

[0048] In some embodiments, the method of covering the PI tape 2 with hot melt adhesive is as follows: after bonding the PI tape 2 with the hot melt adhesive tape, hot pressing is performed at a temperature of 80-100°C and a pressure of 4-8 MPa.

[0049] The first punching operation performed on the EMI shielding film strip 1 and the second punching operation performed on the PI strip 2 are performed separately on different equipment. This invention does not limit the order in which the EMI shielding film and the PI reinforcing sheet are pre-attached. Specifically, the first component 8 can be pre-attached to the flexible circuit board 3 on the first equipment, and then the flexible circuit board 3 can be transferred to the second equipment to pre-attach the second component 11. Alternatively, the second component 11 can be pre-attached on the second equipment first, and then the flexible circuit board 3 can be transferred to the first equipment to pre-attach the first component 8.

[0050] The flexible circuit board 3 is laid horizontally and adsorbed onto the upper surface of the first adsorption heating platform 6. The first adsorption heating platform 6 is used to adsorb the flexible circuit board 3 and heat the flexible circuit board 3.

[0051] In some embodiments, the surface of the first adsorption heating platform 6 is distributed with a plurality of suction holes (not shown in the figure), and the first adsorption heating platform 6 has air passages (not shown in the figure) communicating with these suction holes. These air passages are in turn connected to an air extraction device (not shown in the figure) through air guide pipes (not shown in the figure). The air extraction device creates a negative pressure at the suction holes so that the flexible circuit board 3 can be adsorbed by the first adsorption heating platform 6, preventing the flexible circuit board 3 from shifting during the punching process.

[0052] In some embodiments, the first adsorption heating platform 6 includes a heating rod (not shown in the figure). The heating rod heats the first adsorption heating platform 6, and the heat is conducted to the flexible circuit board 3 through the first adsorption heating platform 6, increasing the temperature of the flexible circuit board 3. This facilitates the adhesion of the hot melt adhesive of the EMI shielding film in contact with the flexible circuit board 3, allowing it to bond to the flexible circuit board 3. The heating temperature is controlled so that the temperature of the flexible circuit board 3 does not exceed its allowable temperature limit, such as 140°C, to prevent damage to the flexible circuit board 3 due to excessive temperature.

[0053] As the EMI shielding film strip 1 passes over the flexible circuit board 3, the first punch 7 falls and performs the first punching operation, cutting the first component 8 from the EMI shielding film strip 1. The first component 8 is the EMI shielding film that needs to be pasted onto the surface of the flexible circuit board 3. For example, please refer to... Figure 3 and Figure 4 The EMI shielding film strip 1 passes through the first die 15. The first die 15 has a transversely through feeding channel and a vertically through first hole 16 whose cross-section is adapted to the first punch 7. The first punch 7 passes through the first hole 16, and the first hole 16 intersects with the transverse feeding channel. The first punch 7 falls in the first hole 16 and, in the process of passing through the feeding channel, cuts a first component 8 from the EMI shielding film strip 1 passing through the feeding channel.

[0054] The first component 8 is attached to the lower end face of the first punch 7 and falls onto the surface of the flexible circuit board 3 as the first component 8 falls. For example, please refer to... Figure 5The first punch 7 has a first hollow inner cavity 17 extending axially. The lower port of the first hollow inner cavity 17 is located on the lower end face of the first punch 7, and the upper port is located on the side wall of the first punch 7. The upper port is connected to a suction device via a first suction pipe 18. Exemplarily, the upper end of the first punch 7 is disposed on a first mounting block 19, and one end of the first suction pipe 18 passes through the side of the first mounting block 19 and is threadedly connected to the upper port of the first punch 7. During the first punching operation, the suction device draws in air, creating a negative pressure on the lower end face of the first punch 7, causing the punched first component 8 to be adsorbed at the end of the first punch 7.

[0055] During the punching process, the first punch 7 is heated to 100-120℃, and after the first punch 7 delivers the first component 8 onto the flexible circuit board 3, it is held for at least 2 seconds. The first component 8, adsorbed on the lower surface of the first punch 7, is rapidly heated during the falling and holding periods of the first punch 7, thus acquiring a certain degree of adhesion, allowing the first component 8 to be pre-bonded onto the flexible circuit board 3. Because the flexible circuit board 3 is heated by the first adsorption heating platform 6, the adhesive hot melt adhesive on the lower surface of the first component 8 is prevented from losing its adhesion due to contact with the cold flexible circuit board 3, thus avoiding any impact on the pre-bonding effect.

[0056] The flexible circuit board 3 is laid horizontally and adsorbed onto the upper surface of the second adsorption heating platform 9. The second adsorption heating platform 9 is used to adsorb the flexible circuit board 3 and heat the flexible circuit board 3.

[0057] In some embodiments, the surface of the second adsorption heating platform 9 is distributed with a plurality of suction holes, and the second adsorption heating platform 9 has air channels communicating with these suction holes. These air channels are in turn connected to an air extraction device through air guide pipes. The air extraction device creates a negative pressure at the suction holes so that the flexible circuit board 3 can be adsorbed by the second adsorption heating platform 9, preventing the flexible circuit board 3 from shifting during the stamping process.

[0058] In some embodiments, the second adsorption heating platform 9 includes a heating rod, and a plurality of suction holes are arranged on the surface of the second adsorption heating platform 9. The heating rod is used to heat the second adsorption heating platform 9, and the heat is conducted to the flexible circuit board 3 through the second adsorption heating platform 9, increasing the temperature of the flexible circuit board 3. This facilitates the adhesion of the hot melt adhesive of the PI reinforcing sheet in contact with the flexible circuit board 3, allowing it to bond to the flexible circuit board 3. The heating temperature is controlled so that the temperature of the flexible circuit board 3 does not exceed its allowable temperature limit, such as 140°C, to prevent damage to the flexible circuit board 3 due to excessive temperature.

[0059] As the PI strip 2 passes over the flexible circuit board 3, the second punch 10 falls and performs a second punching operation, cutting a second component 11 from the PI strip 2. The second component 11 is the PI reinforcing sheet that needs to be adhered to the surface of the flexible circuit board 3. For example, please refer to... Figure 5 and Figure 6 The PI strip 2 passes through the second die 20, which has a transversely through-flow channel and a vertically through-flow second hole 21 with a cross-section adapted to the second punch 10. The second punch 10 passes through the second hole 21, which intersects with the transverse through-flow channel. The second punch 10 falls into the second hole 21 and, while passing through the through-flow channel, cuts a second component 11 from the PI strip 2 passing through the through-flow channel.

[0060] The second component 11 is attached to the lower end face of the second punch 10 and falls onto the surface of the flexible circuit board 3 as the second component 11 falls. For example, please refer to... Figure 6 The second punch 10 has a second hollow inner cavity 22 extending axially. The lower port of the second hollow inner cavity 22 is located on the lower end face of the second punch 10, and the upper port is located on the side wall of the second punch 10. The upper port is connected to an air extraction device via a second suction pipe 23. Exemplarily, the upper end of the second punch 10 is disposed on the second mounting block 24, and one end of the second suction pipe 23 passes through the side of the second mounting block 24 and is threadedly connected to the upper port of the second punch 10. During the second punching operation, the air extraction device draws in air, creating a negative pressure on the lower end face of the second punch 10, causing the punched second part 11 to be adsorbed at the end of the second punch 10.

[0061] During the punching process, the second punch 10 is heated to 100-120℃, and after the second punch 10 delivers the second component 11 onto the flexible circuit board 3, it is held for at least 2 seconds. The second component 11, adsorbed on the lower end face of the second punch 10, is rapidly heated during the falling and holding times of the second punch 10, thus acquiring a certain degree of adhesion, allowing the second component 11 to be pre-bonded onto the flexible circuit board 3. Because the flexible circuit board 3 is heated by the second adsorption heating platform 9, the adhesive hot melt adhesive on the lower surface of the second component 11 is prevented from losing adhesion due to contact with the cold flexible circuit board 3, thus avoiding any impact on the pre-bonding effect.

[0062] The second adsorption heating platform 9 can adopt the same structural design as the first adsorption heating platform 6. The first punch 7 and the second punch 10 are designed according to the shape requirements of the EMI shielding film and the PI reinforcing sheet, respectively. Generally speaking, their cross-sectional shapes and dimensions are different. The first hole 16 of the first die 15 and the second hole 21 of the second die 20 should be designed to match the shape of the punch.

[0063] In some embodiments, after the first component 8 and the second component 11 are pre-attached to the surface of the flexible circuit board 3, a layer of release paper is covered on the surface of the flexible circuit board 3. The release paper can further prevent misalignment of the first component 8 and the second component 11 during the transfer of the flexible circuit board 3.

[0064] The flexible circuit board 3 with the first component 8 and the second component 11 attached is placed in a hot press, with the EMI shielding film and PI reinforcement surface facing upwards, and the flexible circuit board 3 is hot-pressed to make the first component 8 and the second component 11 more fully and firmly bonded to the flexible circuit board 3.

[0065] In some embodiments, please refer to Figure 7 and Figure 8 The hot press includes an upper pressure plate 12 and a lower pressure plate 25. The inner surface of the upper pressure plate 12 is the pressing working surface, which includes a first working area 13 and a second working area 14. The first working area 13 is opposite to the thicker of the first component 8 and the second component 11, and the second working area 14 is opposite to the thinner of the first component 8 and the second component 11. The first working area 13 is deeper than the second working area 14, and the depth difference is equal to the thickness difference between the first component 8 and the second component 11. A flexible circuit board 3 with the first component 8 and the second component 11 pre-bonded to its surface is placed between the upper pressure plate 12 and the lower pressure plate 25, with the side with the first component 8 and the second component 11 attached facing upwards. After the upper pressure plate 12 is closed, the first component 8 falls exactly within the first working area 13, and the second component 11 falls exactly within the second working area 14. Since the first working area 13 is deeper than the second working area 14, and the depth difference is equal to the thickness difference between the first component 8 and the second component 11, when the upper pressure plate 12 is closed and pressure is applied, the first component 8 and the second component 11 bear the same pressure, which makes it possible to simultaneously heat press two materials of different thicknesses in one hot pressing.

[0066] In some embodiments, the second working area 14 is flush with the inner surface of the upper pressure plate 12, and the first working area 13 is formed as a groove.

[0067] In this invention, the first component 8 and the second component 11 are pre-attached to the surface of the flexible circuit board 3 to prevent the positions of the first component 8 and the second component 11 from shifting during the transfer of the flexible circuit board 3. The first component 8 and the second component 11 are simultaneously heat-pressed together, which can improve efficiency.

[0068] The above descriptions are merely some embodiments of the present invention. Those skilled in the art can make various modifications and improvements without departing from the inventive concept of the present invention, and these all fall within the scope of protection of the present invention.

Claims

1. A method for attaching an EMI shielding film and a PI reinforcing sheet to the surface of a flexible circuit board, applicable to attaching an EMI shielding film and a PI reinforcing sheet to a flexible circuit board, characterized in that, Includes the following steps: The company provides EMI shielding film tape, PI tape, and flexible circuit board, wherein one surface of the EMI shielding film tape is covered with a first hot melt adhesive, and one surface of the PI tape is covered with a second hot melt adhesive. The flexible circuit board is horizontally adsorbed onto the surface of the first adsorption heating platform. The EMI shielding film strip is placed horizontally above the flexible circuit board with the first hot melt adhesive facing downwards. A first punch with a first temperature is used to perform a first punching operation on the EMI shielding film strip to punch out a first component from the EMI shielding film strip. The first punch adsorbs the first component at its end and delivers the first component to the surface of the flexible circuit board, then pauses for a first time to pre-bond the first component onto the flexible circuit board. The flexible circuit board is horizontally adsorbed onto the surface of the first adsorption heating platform or another second adsorption heating platform. The PI strip is placed horizontally above the flexible circuit board with the second hot melt adhesive facing downwards. A second punch with a second temperature is used to perform a second punching operation on the PI strip to punch out a second component from the PI strip. The second punch adsorbs the second component at its end and delivers the second component to the surface of the flexible circuit board, then pauses for a second time to pre-bond the second component onto the flexible circuit board. The flexible circuit board is transferred to a hot press for hot pressing, wherein the hot press includes an upper pressure plate, the upper pressure plate has a first working area and a second working area, the first working area is opposite to the thicker of the first component and the second component, the second working area is opposite to the thinner of the first component and the second component, the first working area is deeper than the second working area, and the depth difference is equal to the thickness difference between the first component and the second component.

2. The method for attaching an EMI shielding film and a PI reinforcing sheet to the surface of a flexible circuit board according to claim 1, characterized in that, The method of covering the PI material strip with hot melt adhesive is as follows: after bonding the PI material strip and the hot melt adhesive strip, hot pressing is performed at a temperature of 80-100℃ and a pressure of 4-8MPa.

3. The method for attaching an EMI shielding film and a PI reinforcing sheet to the surface of a flexible circuit board according to claim 1, characterized in that, The first adsorption heating platform has a heating rod inside, and a number of air intake holes are arranged on the surface of the first adsorption heating platform.

4. The method for attaching an EMI shielding film and a PI reinforcing sheet to the surface of a flexible circuit board according to claim 1, characterized in that, The first temperature is 100-120℃, and the first time is not less than 2s; the second temperature is 100-120℃, and the second time is not less than 2s.

5. The method for attaching an EMI shielding film and a PI reinforcing sheet to the surface of a flexible circuit board according to claim 1, characterized in that, The first punch has a first hollow inner cavity extending along the axial direction. The lower port of the first hollow inner cavity is located on the lower end face of the first punch, and the upper port is located on the side wall of the first punch. The upper port is connected to an air extraction device through a first air suction pipe.

6. The method for attaching an EMI shielding film and a PI reinforcing sheet to the surface of a flexible circuit board according to claim 5, characterized in that, The first punch corresponds to the first die, the first die has a first hole that matches the cross-sectional shape of the first punch, the first punch passes through the first hole, the EMI shielding film strip passes through the first die laterally, and the movement path of the first punch intersects with the EMI shielding film strip. The upper end of the first punch is mounted on the first mounting block, and one end of the first suction pipe passes through the side of the first mounting block and is threadedly connected to the upper port of the first punch.

7. The method for attaching an EMI shielding film and a PI reinforcing sheet to the surface of a flexible circuit board according to claim 1, characterized in that, The second punch has a second hollow inner cavity extending along the axial direction. The lower port of the second hollow inner cavity is located on the lower end face of the second punch, and the upper port is located on the side wall of the second punch. The upper port is connected to an air extraction device through an air suction pipe.

8. The method for attaching an EMI shielding film and a PI reinforcing sheet to the surface of a flexible circuit board according to claim 7, characterized in that, The second punch corresponds to the second die, and the second die has a second hole that matches the cross-sectional shape of the second punch. The second punch passes through the second hole, and the PI strip passes through the second die laterally. The movement path of the second punch intersects with the PI strip. The upper end of the second punch is mounted on the second mounting block, and one end of the second suction pipe passes through the side of the second mounting block and is threadedly connected to the upper port of the second punch.

9. The method for attaching an EMI shielding film and a PI reinforcing sheet to the surface of a flexible circuit board according to claim 1, characterized in that, After pre-attaching the first component and the second component to the surface of the flexible circuit board, a layer of release paper is covered on the surface of the flexible circuit board.

10. The method for attaching an EMI shielding film and a PI reinforcing sheet to the surface of a flexible circuit board according to any one of claims 1-9, characterized in that, The second working area is flush with the inner surface of the upper pressure plate, and the first working area is formed as a groove.

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