Electromagnetic pulse auxiliary rapid hot pressing system for ultrathin multilayer FPC (Flexible Printed Circuit)

Abstract

The invention discloses an electromagnetic pulse auxiliary rapid hot pressing system for an ultrathin multi-layer FPC, and the system comprises a processing table which is provided with a circulating conveying mechanism, the processing table is provided with a support beam, the lower part of the support beam is symmetrically provided with connecting frames at the rear side of the processing table through a pressing cylinder, the lower parts of the connecting frames are provided with sealing covers, and the circulating conveying mechanism is provided with an adaptive tool. A partition plate is arranged in the sealing cover, an electromagnetic hot-pressing array is arranged on the lower side of the partition plate, a detection mechanism is arranged on the partition plate, an air exchange mechanism is further arranged on the sealing cover, feeding and discharging mechanisms are symmetrically arranged on the front side of the support beam, and a main controller is arranged above the support beam; the ACF is directly heated through electromagnetic pulses, the heating rate is increased, the process time is shortened, single-block regulation and control can be achieved through an array type hot-pressing structure, the applicability is good, meanwhile, bonding bubbles can be reduced through vacuum pumping in the initial stage of hot-pressing, inert gas is filled in the high-temperature stage, FPC copper foil oxidation or ACF conductive particle oxidation failure is restrained, and the FPC hot-pressing quality is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of flexible circuit board production equipment, and particularly relates to an electromagnetic pulse assisted rapid hot pressing system for ultra-thin multilayer FPC. BACKGROUND

[0002] Flexible printed circuit board (FPC) is widely used in consumer electronics, 5G communication, medical electronics and other fields due to its lightness, thinness and bendability; with the development of miniaturization and high integration of electronic devices, the demand for ultra-thin multilayer FPC (number of layers ≥8, single layer thickness ≤25 μm) has increased dramatically, and its manufacturing process has put forward higher requirements for hot pressing equipment.

[0003] Traditional FPC hot pressing equipment mostly adopts "hot plate conduction heating" or "hot oil circulation heating" mode, and heat is transferred to the adhesive or conductive layer on the surface of the FPC through a metal hot plate, and then the interlayer adhesion is achieved through pressure.

[0004] However, local heat loss of the hot plate or interlayer thermal resistance difference of the FPC during heating of the traditional equipment easily causes temperature gradient, resulting in uneven ACF curing and weak interlayer bonding force; and the response lag of the traditional hydraulic or pneumatic pressure system easily leads to fine line damage or large size board warping; at the same time, the copper foil or plating layer on the surface of the FPC in the high temperature environment during hot pressing is easily oxidized by oxygen, which affects the conductive performance, therefore, the present application proposes an electromagnetic pulse assisted rapid hot pressing system for ultra-thin multilayer FPC to solve the problems in the prior art. SUMMARY

[0005] In view of the above problems, the purpose of the present application is to propose an electromagnetic pulse assisted rapid hot pressing system for ultra-thin multilayer FPC, which directly heats the ACF through electromagnetic pulse, greatly improves the heating rate, and at the same time, the heating is uniform, which shortens the process time and improves the production capacity; the array type hot pressing structure is adopted, which is combined with the pressure sensor and the embedded thermocouple for real-time monitoring, so that dynamic regulation and control can be realized, and fine line damage or large size board warping can be effectively avoided; through the setting of the air exchange mechanism, vacuum is extracted at the initial stage of hot pressing to remove the interference of air and moisture, reduce the residual bubbles between the layers, fill inert gas at the high temperature stage, inhibit the oxidation of FPC copper foil or ACF conductive particles, and improve the hot pressing quality of FPC.

[0006] In order to achieve the purpose of the present application, the present application realizes the technical scheme as follows: an electromagnetic pulse assisted rapid hot pressing system for ultra-thin multi-layer FPC, comprising a processing table, a circulating conveying mechanism, a support beam, a sealing and pressing mechanism and a feeding and discharging mechanism, the circulating conveying mechanism is arranged on the processing table, the support beam is arranged on the processing table and is fixedly connected with the processing table across the front and rear sides of the circulating conveying mechanism, the sealing and pressing mechanism comprises a pressing cylinder, a connecting frame, a sealing cover, an adaptive tool, a partition plate, an electromagnetic hot pressing array, an air exchange mechanism and a detection mechanism, the connecting frame is arranged on the rear side of the processing table below the support beam through the pressing cylinder, the sealing cover is fixedly arranged below the connecting frame, the adaptive tool is arranged on the circulating conveying mechanism, a plurality of adaptive tools are arranged for circulating processing, the partition plate is arranged in the sealing cover, the electromagnetic hot pressing array is arranged on the lower side of the partition plate, the detection mechanism is arranged on the partition plate, the air exchange mechanism is further arranged on the sealing cover, the feeding and discharging mechanism is symmetrically arranged on the front side of the support beam, and the main controller is arranged above the support beam for intelligent automatic control of the whole equipment.

[0007] Further improvement lies in that the circulating conveying mechanism comprises a circulating conveying groove, an infrared sensor, a limiting cylinder and a limiting frame, the circulating conveying groove is arranged on the processing table, the infrared sensor is arranged on the side of the circulating conveying groove at the positions of the feeding and discharging mechanism and the sealing and pressing mechanism, the infrared sensor at the position of the feeding and discharging mechanism is provided with two groups of detectors for the feeding position and the discharging position, respectively, the limiting frame is arranged on the processing table at the position of the feeding and discharging mechanism in the circulating conveying groove through the limiting cylinder, the adaptive tool is placed in the circulating conveying groove for circulating conveying, and the infrared sensor is electrically connected with the main controller.

[0008] Further improvement lies in that the electromagnetic hot pressing array comprises a micro servo cylinder, a pressure sensor, a quick-release electric connection mechanism, a fused quartz pressing plate, a high-frequency coil, an electromagnetic pulse generator, a pressing bearing plate, an electric heating wire, an embedded thermocouple and an upper lifting mechanism, the micro servo cylinder is symmetrically arranged on the partition plate, the pressure sensor is arranged on the telescopic end of the micro servo cylinder downwards, the range of the pressure sensor is 0-500N, and the accuracy is ±0.1%FS, the fused quartz pressing plate is arranged below the pressure sensor through the quick-release electric connection mechanism, the fused quartz pressing plate can be quickly disassembled and assembled, and the fused quartz pressing plate is convenient for maintenance and replacement, the high-frequency coil is embedded in the fused quartz pressing plate, the electromagnetic pulse generator is arranged on the sealing cover, the pressing bearing plate is detachably arranged on the upper surface of the adaptive tool, the electric heating wire is embedded in the pressing bearing plate, the high-frequency coil is also embedded in the pressing bearing plate, the embedded thermocouple is arranged on the lower surface of the fused quartz pressing plate and the upper surface of the pressing bearing plate, and the embedded thermocouple is used for detecting the FPC hot pressing temperature, and the upper lifting mechanism is arranged on the processing table below the sealing cover.

[0009] Further improvement lies in that the quick release electrical connection mechanism comprises a plug-in mounting seat, a connecting sleeve seat and an electrical connection adapter, the plug-in mounting seat is arranged below the pressure sensor, the connecting sleeve seat is fixedly arranged at the middle of the upper side of the fused quartz pressing plate, the connecting sleeve seat is adapted with the plug-in mounting seat, the electrical connection adapter is arranged between the lower side of the plug-in mounting seat and the inner side of the connecting sleeve seat, for electrical connection and signal transmission, the high-frequency coil and the embedded thermocouple at the lower side of the fused quartz pressing plate are electrically connected with the electrical connection adapter, and the electrical connection adapter and the pressure sensor are electrically connected with the main controller.

[0010] Further improvement lies in that the upward top mechanism comprises a jacking cylinder, a jacking adapter seat and a positioning adapter groove, the jacking cylinder is arranged on the processing table directly below the sealing cover, the jacking cylinder is provided with the jacking adapter seat at the telescopic end, the positioning adapter groove is arranged at the lower side of the adapter tool, and the electrical connection adapter is arranged in the positioning adapter groove and on the jacking adapter seat, for electrical connection and signal transmission, the electric heating wire and the embedded thermocouple on the upper surface of the adapter tool are electrically connected with the electrical connection adapter, and the electrical connection adapter is electrically connected with the main controller.

[0011] Further improvement lies in that the micro servo cylinder is arranged in an array shape, a direct drive servo motor is arranged above the micro servo cylinder, the direct drive servo motor is connected with the micro servo cylinder for driving, and the direct drive servo motor is electrically connected with the main controller.

[0012] Further improvement lies in that the air exchange mechanism comprises a vacuum pump, an inert gas tank, a gas injection pump, a vacuum pipe, a gas injection pipe, a mass flow controller and an electric control valve, the vacuum pump and the inert gas tank are arranged above the sealing cover, the gas injection pump is connected with the inert gas tank through a pipeline at one side, the vacuum pipe is connected between the vacuum pump and the lower cavity of the sealing cover, the gas injection pipe is connected between the gas injection pump and the lower cavity of the sealing cover, the mass flow controller is arranged on the gas injection pipe, for adjusting and controlling the flow of inert gas injection, the electric control valve is arranged on the gas injection pipe below the mass flow controller and on the vacuum pipe, the electric control valve is electrically connected with the main controller, for pipeline conduction and disconnection.

[0013] Further improvement lies in that the detection mechanism comprises a quartz glass window, a CCD camera, a fill light, a through hole and a laser displacement sensor, the quartz glass window is arranged at the center of the partition plate, the CCD camera is arranged above the quartz glass window, the fill lights are symmetrically arranged in the sealing cover below the partition plate, are LED cold light sources with a wavelength of 520mm, and can avoid thermal interference, the through holes are symmetrically arranged on the partition plate, are arranged above the module gap of the electromagnetic hot pressing array, and the laser displacement sensor is arranged on the partition plate above the through holes.

[0014] Further improvement lies in that the feeding and discharging mechanism comprises a feeding and discharging conveying belt, fixed side plates, movable grooves, movable seats, a material taking cylinder, a suction disc rack and a horizontal cylinder, feeding and discharging conveying belts are symmetrically arranged on the processing tables on the two sides of the support beam, respectively, as shown in the drawings, the left side is a feeding conveying belt for conveying pre-bonding FPC, and the right side is a discharging conveying belt for conveying FPC after hot pressing, fixed side plates are symmetrically arranged on the two sides of the support beam above the feeding and discharging conveying belts, the fixed side plates are provided with movable grooves, the movable grooves are provided with movable seats, the movable seats are provided with the suction disc rack through the material taking cylinder at the lower side of the movable seats, negative pressure suction discs are distributed at the lower side of the suction disc rack, and the horizontal cylinder is arranged between the movable seat and the fixed plate and used for switching the position of the suction disc rack.

[0015] Further improvement lies in that the upper surface of the adapter tool is provided with a sealing adapter groove, the sealing adapter groove is internally provided with a sealing rubber pad structure, and the sealing adapter groove corresponds to the lower edge of the sealing cover, so that the sealing effect is guaranteed.

[0016] The application has the beneficial effects that the application directly heats the ACF through electromagnetic pulses, greatly improves the heating rate, and uniformly heats, thereby shortening the process time and improving the production capacity;

[0017] The array type hot pressing structure is adopted, the pressure sensor and the embedded thermocouple are used for real-time monitoring, dynamic regulation and control can be realized, and the fine line is effectively prevented from being pressed and the large-size plate is effectively prevented from being warped;

[0018] Through the setting of the air exchange mechanism, the vacuum is extracted in the initial hot pressing stage, the interference of air and moisture is removed, the residual air bubbles between the layers are reduced, inert gas is filled in the high-temperature stage, the oxidation of the FPC copper foil or the oxidation failure of the ACF conductive particles is inhibited, the FPC hot pressing quality is improved, and the defects existing in the traditional production process are solved. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 It is a front view of the application.

[0020] Figure 2 It is a side view of the application.

[0021] Figure 3 It is a side view structure diagram of the application.

[0022] Figure 4 It is a front view structure diagram of the sealing cover of the application.

[0023] Figure 5 It is a side view structure diagram of the sealing cover of the application.

[0024] Figure 6 It is a quick-release electrical connection mechanism and a fused quartz pressing plate structure diagram.

[0025] Figure 7 Figure 3 is a sectional view of the upper mechanism of the application matched with the profile structure of the fitting tool.

[0026] 1, processing table; 2, support beam; 3, down pressure cylinder; 4, connecting frame; 5, sealing cover; 6, fitting tool; 7, partition plate; 8, main controller; 9, circulating conveying groove; 10, infrared sensor; 11, limiting cylinder; 12, limiting frame; 13, miniature servo cylinder; 14, pressure sensor; 15, fused quartz pressing plate; 16, high-frequency coil; 17, electromagnetic pulse generator; 18, heating wire; 19, embedded thermocouple; 20, plug-in mounting seat; 21, connecting sleeve; 22, electrically connected adapter head; 23, jacking cylinder; 24, jacking adapter seat; 25, positioning adapter groove; 26, direct drive servo motor; 27, vacuum pump; 28, inert gas tank; 29, gas injection pump; 30, vacuum pipe; 31, gas injection pipe; 32, mass flow controller; 33, electrically controlled valve; 34, quartz glass window; 35, CCD camera; 36, light supplement lamp; 37, through hole; 38, laser displacement sensor; 39, feeding and discharging conveying belt; 40, fixed side plate; 41, movable groove; 42, movable seat; 43, material taking cylinder; 44, suction cup frame; 45, horizontal cylinder; 46, sealing adapter groove; 47, pressing bearing plate. DETAILED DESCRIPTION

[0027] In order to deepen the understanding of the application, the application will be further described in conjunction with the embodiments below. The embodiments are only used to explain the application and do not constitute a limitation on the protection scope of the application.

[0028] According to the application, the sealing cover and the fitting tool cooperate to provide a closed space for the air exchange mechanism, which can maintain the vacuum degree and the gas purity. Figures 1-7 As shown in FIG. 1, the present embodiment provides an electromagnetic pulse assisted rapid hot pressing system for ultra-thin multi-layer FPC, which comprises a processing table 1, a circulating conveying mechanism, a support beam 2, a sealing and pressing mechanism, and a feeding and discharging mechanism. The processing table 1 is provided with the circulating conveying mechanism. The processing table 1 is provided with the support beam 2, which is fixedly connected with the processing table across the front and rear sides of the circulating conveying mechanism. The sealing and pressing mechanism comprises a down pressure cylinder 3, a connecting frame 4, a sealing cover 5, a fitting tool 6, a partition plate 7, an electromagnetic hot pressing array, an air exchange mechanism, and a detection mechanism. The connecting frame 4 is symmetrically arranged below the support beam 2 at the rear side of the processing table 1 through the down pressure cylinder 3. The sealing cover 5 is fixedly arranged below the connecting frame 4. The fitting tool 6 is arranged on the circulating conveying mechanism. The fitting tool is placed in multiple groups for circulating processing. The sealing cover 5 is provided with the partition plate 7. The electromagnetic hot pressing array is arranged at the lower side of the partition plate 7. The detection mechanism is arranged on the partition plate 7. The sealing cover 5 is further provided with the air exchange mechanism. The support beam 2 is symmetrically provided with the feeding and discharging mechanism at the front side. The support beam 2 is provided with a main controller 8 above for intelligent automatic control of the entire equipment.

[0029] The sealing cover and the fitting tool cooperate to provide a closed space for the air exchange mechanism, which can maintain the vacuum degree and the gas purity.

[0030] The circulating conveying mechanism comprises a circulating conveying groove 9, an infrared sensor 10, a limiting cylinder 11 and a limiting frame 12, the circulating conveying groove 9 is arranged on the processing table 1, the infrared sensor 10 is arranged on the side of the circulating conveying groove 9 at the positions of the feeding and discharging mechanism and the sealing and pressing mechanism, the infrared sensor 10 at the position of the feeding and discharging mechanism is provided with two groups of sensors for detecting the feeding position and the discharging position respectively, the limiting frame 12 is arranged on the processing table 1 at the position of the feeding and discharging mechanism in the circulating conveying groove 9 through the limiting cylinder 11, the adaptive tooling 6 is placed in the circulating conveying groove 9 for circulating conveying, and the infrared sensor 10 is electrically connected with the main controller 8.

[0031] The straight line part in the circulating conveying groove is symmetrically provided with synchronous conveying belts, and the two end turning parts are rotary conveying disc structures, which are all driven by motors; the infrared sensor is used for monitoring that the adaptive tooling reaches the feeding position, the discharging position and the hot pressing station, starting the limiting cylinder and the jacking mechanism, the limiting frame above the limiting cylinder blocks the continuous conveying of the adaptive tooling, the jacking mechanism jacks up the adaptive tooling to leave the conveying belt, so that the position is fixed, and then the processing mechanism of the corresponding station is processed, that is, the feeding structure adsorbs the FPC for feeding, the discharging structure adsorbs the completed FPC for hot pressing to discharge, and the hot pressing station presses downward for hot pressing.

[0032] The electromagnetic hot pressing array comprises a micro servo cylinder 13, a pressure sensor 14, a quick-release electrical connection mechanism, a fused quartz pressing plate 15, a high-frequency coil 16, an electromagnetic pulse generator 17, a pressing bearing plate 47, an electric heating wire 18, an embedded thermocouple 19 and a jacking mechanism, the micro servo cylinder 13 is symmetrically arranged on the partition plate 7, the telescopic end of the micro servo cylinder 13 downwardly is provided with the pressure sensor 14, the range of which is 0-500N, and the accuracy is ±0.1%FS, the fused quartz pressing plate 15 is arranged below the pressure sensor 14 through the quick-release electrical connection mechanism, which can realize quick disassembly and assembly of the fused quartz pressing plate, facilitating maintenance and replacement, the high-frequency coil 16 is embedded in the fused quartz pressing plate 15, the electromagnetic pulse generator 17 is arranged on the sealing cover 5, the pressing bearing plate 47 is detachably arranged on the upper surface of the adaptive tooling 6, the electric heating wire 18 is embedded in the pressing bearing plate 47, the high-frequency coil 16 is also embedded in the pressing bearing plate 47, the embedded thermocouple 19 is arranged on the lower surface of the fused quartz pressing plate 15 and the upper surface of the pressing bearing plate 47, which is used for detecting the FPC hot pressing temperature, and the jacking mechanism is arranged on the processing table 1 below the sealing cover 5.

[0033] The high-frequency coil in the pressing bearing plate is a micro coil, which is arranged according to the position distribution of the loop layout in different models of FPC, the pressing bearing plate is a detachable structure, which is replaced according to different models of FPC hot pressing, and the internal circuit is connected through the conductive contact.

[0034] The electromagnetic pulse generator converts the direct current power into high-frequency alternating current (frequency adjustable) of 10-50 kHz, drives the high-frequency coil to generate electromagnetic field, receives the instructions of the integrated control system in the main controller by the built-in frequency / power adjustment controller, and dynamically adjusts the current parameters to control the target temperature and the heating rate.

[0035] The high-frequency coil is made of silver-plated copper wire with a silver-plated copper surface, which is wound at a spacing of 5-10 mm. The current controlled by the electromagnetic pulse generator generates eddy current effect in the adhesive layer or conductive layer inside the FPC, directly heating the material; and cooperates with the electric heating wire to assist in improving the heating rate of the FPC.

[0036] The distribution of the embedded thermocouple can obtain the surface and internal temperature data of the FPC in real time, which is transmitted to the electromagnetic pulse generator through the signal conditioning circuit built in the main controller, and the frequency and power output by the electromagnetic pulse generator are adjusted by the pid algorithm to realize closed-loop temperature control.

[0037] The pressure sensor collects the output pressure value of each micro servo cylinder in real time and transmits it to the main controller as the input parameter of the dynamic control algorithm; the dynamic control algorithm is integrated in the built-in PLC of the main controller, pre-stores the pressure curve of 0.1-0.5 MPa in the initial bonding stage, 1.0-3.0 MPa in the high-temperature curing stage, and 0.5-1.5 MPa in the cooling and pressure maintaining stage, combines the temperature feedback and displacement monitoring data of the laser displacement sensor, and outputs the PWM signal to control the torque of the direct drive servo motor to dynamically adjust the output pressure of each micro servo cylinder.

[0038] The quick-release electrical connection mechanism includes a plug-in mounting seat 20, a connection sleeve 21, and an electrical connection adapter 22. The plug-in mounting seat 20 is arranged below the pressure sensor 14, the connection sleeve 21 is fixedly arranged at the middle of the upper side of the fused quartz pressing plate 15, the connection sleeve 21 is adapted with the plug-in mounting seat 20, the electrical connection adapter 22 is arranged between the lower side of the plug-in mounting seat 20 and the inner side of the connection sleeve 21 for power supply and signal transmission, the high-frequency coil 16 and the embedded thermocouple 19 on the lower side of the fused quartz pressing plate 15 are electrically connected with the electrical connection adapter 22, and the electrical connection adapter 22 and the pressure sensor 14 are electrically connected with the main controller 8.

[0039] The jacking mechanism includes a jacking cylinder 23, a jacking adapter seat 24, and a positioning adapter groove 25. The jacking cylinder 23 is arranged on the processing table 1 directly below the sealing cover 5, the jacking cylinder 23 is provided with the jacking adapter seat 24 at the extension end, the positioning adapter groove 25 is arranged at the lower side of the adapter tool 6, the electrical connection adapter 22 is arranged in the positioning adapter groove 25 and on the jacking adapter seat 24 for power supply and signal transmission, the electric heating wire 18 and the embedded thermocouple 19 on the upper surface of the adapter tool 6 are electrically connected with the electrical connection adapter 22, and the electrical connection adapter 22 is electrically connected with the main controller 8.

[0040] The micro servo cylinders 13 are arranged in an array, and a direct drive servo motor 26 is arranged above the micro servo cylinders 13, the direct drive servo motor 26 is connected to drive the micro servo cylinders 13, and the direct drive servo motor 26 is electrically connected to the main controller 8.

[0041] Each micro servo cylinder is independently driven, and the displacement of the lower fused quartz pressing plate is accurately controlled by the direct drive servo motor, the response time is less than or equal to 10 ms, the accuracy can reach ±0.01 mm, multi-region independent pressing is realized, and the warping of the large-size FPC is avoided.

[0042] The air exchange mechanism includes a vacuum pump 27, an inert gas tank 28, a gas injection pump 29, a vacuum pipe 30, a gas injection pipe 31, a mass flow controller 32 and an electric control valve 33, the vacuum pump 27 and the inert gas tank 28 are arranged above the sealing cover 5, the inert gas tank 28 is connected with the gas injection pump 29 through a pipeline on one side, the vacuum pipe 30 is connected between the vacuum pump 27 and the lower cavity of the sealing cover 5, the gas injection pipe 31 is connected between the gas injection pump 29 and the lower cavity of the sealing cover 5, the mass flow controller 32 is arranged on the gas injection pipe 31, used for adjusting and controlling the flow of the inert gas injection, the electric control valves 33 are arranged on the gas injection pipe 31 and the vacuum pipe 30 below the mass flow controller 32, the electric control valves 33 are electrically connected to the main controller 8, used for the conduction and disconnection of the pipeline, when vacuumizing, the electric control valve on the gas injection pipe is closed, and the electric control valve on the vacuum pipe is opened; after vacuumizing, the electric control valve on the vacuum pipe is closed, and when the high-temperature curing stage is started, the electric control valve on the gas injection pipe is opened and the gas injection pump is started, the inert gas is injected into the vacuumized cavity to isolate oxygen, so that the thermal oxidation of the FPC is avoided.

[0043] The vacuum pump is a rotary vane vacuum pump, the limit vacuum degree is less than or equal to 10 Pa, the vacuum pump is started before pressing to vacuumize the closed space composed of the sealing cover and the adaptive tooling, remove air and moisture, and avoid the air bubbles remaining between the FPC layers; high-purity nitrogen or argon inert gas is arranged in the inert gas tank, and the inert gas is extracted by the gas injection pump, in the high-temperature stage of the hot pressing, the inert gas is injected into the vacuumized closed space by the gas injection pump to a micro-positive pressure, oxygen is isolated, and the oxidation of the FPC copper foil or the oxidation failure of the ACF conductive particles is inhibited.

[0044] The detection mechanism includes a quartz glass window 34, a CCD camera 35, a light supplement lamp 36, a through hole 37 and a laser displacement sensor 38, the center of the partition plate 7 is provided with the quartz glass window 34, the CCD camera 35 is installed above the quartz glass window 34, the light supplement lamp 36 is symmetrically arranged in the sealing cover 5 below the partition plate 7, which is a LED cold light source with a wavelength of 520mm, avoiding thermal interference, the partition plate 7 is symmetrically distributed with the through hole 37, the through hole 37 is distributed directly above the module gap of the electromagnetic hot pressing array, the laser displacement sensor 38 is arranged above the through hole 37 of the partition plate 7, the laser displacement sensor is sealingly connected with the periphery of the through hole, the laser emission and receiving position is directly opposite to the through hole, and the measurement frequency of the laser displacement sensor is 100Hz.

[0045] The CCD camera can observe the FPC pressing condition in real time through the quartz glass window and the transparent fused quartz pressing plate, and cooperate with the image recognition function of the built-in main controller to obtain the FPC bonding state, bubble residue and the like in real time, so as to provide a visual basis for compensation control; during the pressing process, the CCD camera collects FPC surface images every 20ms, and the system matches the alignment mark image shot before pressing through the SIFT algorithm to calculate the interlayer alignment offset.

[0046] The laser displacement sensor emits laser to the FPC surface through the through hole, receives reflected light and calculates the displacement, i.e. the warping amount, and then transmits the signal to the integrated control system of the main controller, and adjusts the pressure of the micro servo cylinder and the power of the high-frequency coil in combination with the interlayer alignment offset.

[0047] The specific adjustment strategy is that when the local alignment offset is greater than or equal to 2μm, the main controller issues an instruction to control the micro servo cylinder of the corresponding area to increase the pressure by 0.05-0.1MPa, so as to forcibly align the FPC layer; when the warping amount is greater than or equal to 10μm, the power of the high-frequency coil of the corresponding area is reduced, the heating rate of the area is reduced, and the warping caused by thermal expansion is slowed down.

[0048] The feeding and discharging mechanism includes a feeding and discharging conveying belt 39, a fixed side plate 40, a movable groove 41, a movable seat 42, a material taking cylinder 43, a suction cup rack 44 and a horizontal cylinder 45, the feeding and discharging conveying belts 39 are symmetrically and fixedly arranged on the processing tables 1 on both sides of the support beam 2, respectively, and are arranged on both sides of the support beam, as shown in the drawings Figure 1As shown, the left side is the feeding conveyor belt, used to transport pre-bonded FPC, and the right side is the unloading conveyor belt, used to transport FPC that has been hot-pressed. Both are driven by motors. The support beam 2 above the feeding conveyor belt 39 is symmetrically provided with fixed side plates 40 on both sides. The fixed side plates 40 are provided with movable grooves 41. Movable seats 42 are provided in the movable grooves 41. A suction cup frame 44 is provided under the movable seat 42 through the material picking cylinder 43. Negative pressure suction cups are distributed under the suction cup frame. An independent negative pressure pump can also be provided on the fixed side plate to provide negative pressure suction for the negative pressure suction cups to adsorb and release FPC. A horizontal cylinder 45 is provided between the movable seat 42 and the fixed plate for switching the position of the suction cup frame.

[0049] The upper surface of the adapter tool 6 is provided with a sealing adapter groove 46, and the sealing adapter groove 46 contains a sealing gasket structure. The sealing adapter groove 46 corresponds to the lower edge of the sealing cover 5, ensuring the sealing effect.

[0050] The main controller of this invention has a built-in integrated control system, which includes hardware components such as an industrial PLC, a human-machine interface, a data storage unit, and a remote monitoring interface.

[0051] As the "brain" of the system, the industrial PLC receives data from various sensors and the operating data of various components. Based on the pre-stored process program, it outputs control commands such as adjusting the power of the electromagnetic pulse generator, the thrust of the micro servo cylinder, and the start and stop of the vacuum pump, so as to realize the full-process automated control.

[0052] The human-machine interface is implemented by an industrial-grade touch screen, which displays the operating status of each sub-component in real time, such as temperature curves, pressure distribution cloud maps, and vacuum degree values. Process parameters can be entered, such as target temperature 180℃ and curing time 60 seconds, and historical production records can be viewed.

[0053] The data storage unit is implemented using SSD hard drives, and is equipped with the system's built-in database management function to store data such as process recipes, production data, and equipment logs, and supports data export.

[0054] The remote monitoring interface is implemented by a 5G communication module, which can upload the device status to the cloud platform and support remote fault diagnosis, process optimization and remote upgrades.

[0055] Since this invention uses electromagnetic pulse heating, the electromagnetic pulse will cause certain interference and influence on the circuit board and various sensors after it is generated. Therefore, the following measures are taken to avoid these influences.

[0056] First, the high-frequency alternating current generated by the electromagnetic pulse generator will produce an alternating magnetic field, which will cause eddy current in the closed loop of the traditional FPC circuit, resulting in local overheating or even burning the circuit. In the present application, by arranging a high-frequency coil in the compression carrier plate, a micro high-frequency coil is arranged according to the position distribution of the loop circuit layout in the FPC, which can generate an alternating magnetic field opposite to the high-frequency coil in the upper fused quartz compression plate, so as to offset the alternating magnetic field of the closed loop position in the FPC circuit, thereby reducing the influence of the eddy current generated by the alternating magnetic field on the closed loop during the hot pressing of the upper fused quartz compression plate.

[0057] Meanwhile, a Hall sensor can also be arranged to detect the magnetic field of each region, and the coil current is controlled by an industrial PLC, so that the magnetic flux density of the superimposed magnetic field of the offset magnetic field and the original magnetic field at the FPC circuit is 0. The offset high-frequency coil is triggered synchronously with the electromagnetic pulse generator to adapt to the dynamic change of the high-frequency magnetic field.

[0058] And the position of the closed loop in the FPC circuit is relatively dense, a copper heat sink can be arranged on the corresponding position of the compression carrier plate to improve the heat exchange efficiency and reduce the heat generated by the loop eddy current, thereby further avoiding the influence on the FPC circuit.

[0059] Secondly, the alternating magnetic field generated by the electromagnetic pulse will also affect the detection accuracy and normal work of each sensor in the equipment. For this point, a shielding shell can be arranged outside each sensor, and a sensor with certain anti-electromagnetic interference capability is selected. For the circuit, a twisted shielded cable can be used to further reduce the influence of the alternating magnetic field on the sensor. This setting is only for the sensor structure inside the sealed cover. For the sensor structure outside the sealed cover, a shielding shell can be arranged on the outer side of the sealed cover to avoid the influence of the alternating magnetic field generated during the internal hot pressing.

[0060] Finally, the high-frequency alternating magnetic field generated by the electromagnetic pulse will have a certain influence on the conductive particles in the ACF, thereby affecting the FPC connection reliability. For this problem, the following two points can be solved cooperatively:

[0061] 1. Reduce particle eddy current heating through tight control of electromagnetic pulse parameters

[0062] Optimize the frequency, power and waveform of the electromagnetic pulse to reduce the particle eddy current effect while ensuring efficient heat absorption of the resin matrix (adhesive).

[0063] The size of the eddy current is proportional to the square of the frequency f, that is, I 涡流 ∝f 2 The frequency that minimizes the particle eddy current and maximizes the heat absorption of the resin needs to be selected.

[0064] The skin depth of conductive particles σ = √(2p / ωμ), p is the particle resistivity, ω = 2πf, μ is the magnetic permeability, when σ < r, r is the particle radius, the eddy current is limited to the particle surface, and the heat generation is reduced.

[0065] Resin matrix ρ ≈ 10 12 Ω·m, is an insulator, and under high-frequency magnetic field, heat is absorbed through dielectric loss, and the loss factor tanσ increases first and then decreases with the increase of frequency.

[0066] Through the frequency dynamic adjustment of the electromagnetic pulse generator, 20-30 kHz is selected according to the characteristics of ACF particles, at this time the skin depth of particles σ ≈ 2-3 μm < 5 μm radius, the eddy current is reduced by more than 60%; the resin tanσ reaches the peak value, and the heat absorption efficiency is the highest.

[0067] The system pre-stores the "frequency-particle heating" curve of different ACF models, and automatically matches the optimal frequency.

[0068] At the same time, the continuous sine wave can be changed to intermittent pulse wave, and the time of continuous eddy current heating of particles is reduced; through temperature feedback, the temperature of ACF layer is monitored in real time, when the temperature of particle area approaches the threshold value, the electromagnetic pulse generator automatically reduces the power, and ensures that the particle temperature ≤200℃.

[0069] 2, heat-pressing timing coordination control, inhibiting particle displacement

[0070] Through the precise timing cooperation of multi-stage pressure regulation system and electromagnetic pulse heating, it is ensured that the particles are in a stable state in each stage of "resin softening-particle compression-curing and shaping".

[0071] The method of phased pressure-temperature cooperation is adopted:

[0072] Initial fitting stage: electromagnetic pulse output 10-20kW low power, ACF temperature rises to 80-100℃, reaches the resin softening point, at the same time, the servo cylinder group outputs 0.1-0.3MPa low pressure, avoids the displacement of particles under high pressure, and ensures the preliminary fitting of FPC interlayer.

[0073] Particle activation stage: electromagnetic pulse power is increased to 30-40kW, temperature is increased to 120-150℃, servo cylinder group pressure is increased to 0.5-1.0MPa, so that the particles are accurately positioned when the resin viscosity is reduced, and free movement is avoided.

[0074] Curing and pressing stage: when the temperature reaches 180℃, the servo cylinder group pressure is suddenly increased to 2.0-3.0MPa, and lasts for 30-60s, at this time the particles are compressed and deformed before the resin is cured, forming a conductive path, and the rising edge of the pressure is synchronized with the peak value of the temperature, with an error ≤1s.

[0075] The temperature is decreased at a rate of 5 ℃ / s, and the pressure of the servo cylinder group is linearly decreased to 0.5 MPa with the temperature, so as to avoid particle displacement caused by shrinkage during temperature decrease.

[0076] Meanwhile, fine adjustment is performed by dynamic pressure compensation, the laser displacement sensor of the system is reversely calculated through the small deformation of the FPC surface, the displacement of the particle area of the ACF layer is monitored in real time, if the local displacement is greater than or equal to 1 μm (particle deviation), the control system immediately increases the pressure of the servo cylinder in the area by 0.05-0.1 MPa, so as to force the particle to reset.

[0077] Through the cooperation of the above two means, the influence of the high-frequency alternating magnetic field on the conductive particles in the ACF can be effectively avoided.

[0078] The above shows and describes the basic principles, main features and advantages of the present application. Those skilled in the art should understand that the present application is not limited to the above-mentioned embodiments, and the above-mentioned embodiments and descriptions in the specification are only to illustrate the principles of the present application, and various changes and improvements can be made without departing from the spirit and scope of the present application, and these changes and improvements all fall within the scope of the present application. The scope of protection of the present application is defined by the appended claims and their equivalents.

Claims

1. An electromagnetic pulse-assisted rapid hot pressing system for ultra-thin multilayer FPCs, characterized in that: The system includes a processing table (1), a circulating conveying mechanism, a support beam (2), a sealing and pressing mechanism, and a loading and unloading mechanism. The processing table (1) is equipped with a circulating conveying mechanism and a support beam (2). The sealing and pressing mechanism includes a pressing cylinder (3), a connecting frame (4), a sealing cover (5), an adapter tool (6), a partition plate (7), an electromagnetic hot press array, a ventilation mechanism, and a detection mechanism. The support beam (2) is located symmetrically behind the processing table (1) and connected to the pressing cylinder (3). The connecting frame (4) is located below the connecting frame (4). The sealing cover (5) is located below the connecting frame (4). The circulating conveying mechanism is equipped with an adapter tool (6). The sealing cover (5) contains a partition plate (7). The partition plate (7) has an electromagnetic hot press array on its lower side. The partition plate (7) has a detection mechanism. The sealing cover (5) also has a ventilation mechanism. The support beam (2) has a loading and unloading mechanism symmetrically located on its front side. The support beam (2) has a main controller (8) located above it.

2. The electromagnetic pulse-assisted rapid hot pressing system for an ultra-thin multilayer FPC according to claim 1, characterized in that: The circulating conveying mechanism includes a circulating conveying trough (9), an infrared sensor (10), a limiting cylinder (11), and a limiting frame (12). The processing table (1) is provided with a circulating conveying trough (9). The side of the circulating conveying trough (9) is provided with infrared sensors (10) at the locations of the loading and unloading mechanism and the sealing and pressing mechanism. The infrared sensors (10) at the locations of the loading and unloading mechanism are provided with two sets for detecting the loading and unloading positions respectively. The processing table (1) at the location of the loading and unloading mechanism in the circulating conveying trough (9) is provided with a limiting frame (12) through the limiting cylinder (11). The adapter tooling (6) is placed in the circulating conveying trough (9) for circulating conveying. The infrared sensor (10) is electrically connected to the main controller (8).

3. The electromagnetic pulse-assisted rapid hot pressing system for an ultra-thin multilayer FPC according to claim 1, characterized in that: The electromagnetic hot-press array includes a miniature servo cylinder (13), a pressure sensor (14), a quick-release electrical connection mechanism, a fused silica pressure plate (15), a high-frequency coil (16), an electromagnetic pulse generator (17), a pressing support plate (47), a heating wire (18), an embedded thermocouple (19), and an upper lifting mechanism. The miniature servo cylinder (13) is symmetrically arranged on the partition plate (7). The pressure sensor (14) is located with its extension end facing downwards. Below the pressure sensor (14), a fused silica pressure plate (15) is arranged via a quick-release electrical connection mechanism. A high-frequency coil (16) is embedded in the fused silica pressure plate (15). An electromagnetic pulse generator (17) is provided on the sealing cover (5). A pressing support plate (47) is detachably provided on the upper surface of the adapter tooling (6). An electric heating wire (18) is embedded in the pressing support plate (47). A high-frequency coil (16) is also embedded in the pressing support plate (47). An embedded thermocouple (19) is provided on the lower surface of the fused silica pressure plate (15) and the upper surface of the pressing support plate (47). An upper lifting mechanism is provided on the processing table (1) located directly below the sealing cover (5).

4. The electromagnetic pulse-assisted rapid hot pressing system for an ultra-thin multilayer FPC according to claim 3, characterized in that: The quick-release electrical connection mechanism includes a plug-in mounting base (20), a connecting sleeve (21), and an electrical connection adapter (22). The plug-in mounting base (20) is provided below the pressure sensor (14), and the connecting sleeve (21) is provided in the middle of the upper part of the fused silica pressure plate (15). The connecting sleeve (21) is snapped into the plug-in mounting base (20). The electrical connection adapter (22) is provided between the lower side of the plug-in mounting base (20) and the inner side of the connecting sleeve (21). The embedded thermocouple (19) on the lower side of the high-frequency coil (16) and the fused silica pressure plate (15) is electrically connected to the electrical connection adapter (22). The electrical connection adapter (22) and the pressure sensor (14) are electrically connected to the main controller (8).

5. The electromagnetic pulse-assisted rapid hot pressing system for an ultra-thin multilayer FPC according to claim 3, characterized in that: The lifting mechanism includes a lifting cylinder (23), a lifting adapter seat (24), and a positioning adapter groove (25). The lifting cylinder (23) is provided on the processing table (1) located directly below the sealing cover (5). The lifting cylinder (23) has a lifting adapter seat (24) at its telescopic end. The adapter tool (6) has a positioning adapter groove (25) on its lower side. The positioning adapter groove (25) and the lifting adapter seat (24) are also provided with an electrical connection adapter head (22). The heating wire (18) and the embedded thermocouple (19) on the upper surface of the adapter tool (6) are electrically connected to the electrical connection adapter head (22). The electrical connection adapter head (22) is electrically connected to the main controller (8).

6. The electromagnetic pulse-assisted rapid hot pressing system for an ultrathin multilayer FPC according to claim 3, characterized in that: The miniature servo cylinders (13) are arranged in an array of multiple groups. A direct drive servo motor (26) is provided above the miniature servo cylinders (13). The direct drive servo motor (26) is connected to and drives the miniature servo cylinders (13). The direct drive servo motors (26) are all electrically connected to the main controller (8).

7. The electromagnetic pulse-assisted rapid hot pressing system for an ultrathin multilayer FPC according to claim 1, characterized in that: The ventilation mechanism includes a vacuum pump (27), an inert gas tank (28), an injection pump (29), a vacuum tube (30), an injection tube (31), a mass flow controller (32), and an electric control valve (33). The vacuum pump (27) and the inert gas tank (28) are located above the sealing cover (5). The injection pump (29) is connected to one side of the inert gas tank (28). The vacuum tube (30) is connected between the vacuum pump (27) and the lower cavity of the sealing cover (5). The injection tube (31) is connected between the injection pump (29) and the lower cavity of the sealing cover (5). The mass flow controller (32) is located on the injection tube (31). Electric control valves (33) are located on the injection tube (31) and the vacuum tube (30) below the mass flow controller (32). The electric control valves (33) are electrically connected to the main controller (8).

8. The electromagnetic pulse-assisted rapid hot pressing system for an ultra-thin multilayer FPC according to claim 1, characterized in that: The detection mechanism includes a quartz glass window (34), a CCD camera (35), a fill light (36), a through hole (37), and a laser displacement sensor (38). The center of the partition plate (7) is provided with a quartz glass window (34). A CCD camera (35) is installed above the quartz glass window (34). Fill lights (36) are symmetrically arranged inside the sealing cover (5) below the partition plate (7). Through holes (37) are symmetrically distributed on the partition plate (7). The through holes (37) are distributed directly above the module gap of the electromagnetic hot pressing array. A laser displacement sensor (38) is provided on the partition plate (7) above the through holes (37).

9. The electromagnetic pulse-assisted rapid hot pressing system for an ultra-thin multilayer FPC according to claim 1, characterized in that: The loading and unloading mechanism includes a loading and unloading conveyor belt (39), a fixed side plate (40), a movable groove (41), a movable seat (42), a picking cylinder (43), a suction cup frame (44), and a horizontal cylinder (45). The loading and unloading conveyor belt (39) is symmetrically arranged on the processing table (1) on both sides of the support beam (2). The fixed side plate (40) is symmetrically arranged on both sides of the support beam (2) above the loading and unloading conveyor belt (39). The fixed side plate (40) is provided with a movable groove (41). The movable seat (42) is provided in the movable groove (41). The suction cup frame (44) is provided on the lower side of the movable seat (42) through the picking cylinder (43). The horizontal cylinder (45) is provided between the movable seat (42) and the fixed plate.

10. The electromagnetic pulse-assisted rapid hot pressing system for an ultra-thin multilayer FPC according to claim 1, characterized in that: The upper surface of the adapter tool (6) is provided with a sealing adapter groove (46), and the sealing adapter groove (46) contains a sealing gasket structure. The sealing adapter groove (46) corresponds to the lower edge of the sealing cover (5).

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