RFPC and manufacturing method thereof

Abstract

The invention discloses an RFPC and a manufacturing method thereof. The manufacturing method comprises the following steps: performing drilling, black hole treatment, electroplating, dry film attachment treatment, pattern exposure and DES treatment on a flexible copper-clad plate in inner layer manufacturing to form an inner conductive layer; carrying out oil printing, exposure, development and curing treatment on the inner conductive layer to form a covering layer; the method comprises the following steps of: attaching EMI (Electro-Magnetic Interference) with a PI (Polyimide) insulating layer to the middle part of a covering layer, carrying out hot pressing treatment on RFPC (Radio Frequency Poly Carbonate) attached with the EMI, then removing a release film of the EMI, and finally carrying out thermocuring treatment on the RFPC attached with an EMI film. And carrying out lamination press-fit, resistance welding, laser uncovering and gold immersion treatment on the EMI attached part. The EMI is attached to the inner layer of the RFPC in advance in the inner layer manufacturing process, the problems that due to the fact that obvious height difference exists in the structure of the RFPC after the outer layer is uncovered, local bubbles of the EMI exist, and pressing is not compact are solved, and therefore the production efficiency and the quality yield of the RFPC are improved, and the material supplementing situation caused by insufficient yield is effectively reduced.

Description

Technical Field

[0001] The present application relates to the technical field of FPC preparation, and in particular to an RFPC and an RFPC preparation method. Background Art

[0002] With the rapid development of the electronics industry, electronic products have increasingly higher requirements for the quality of RFPC bonding boards, and the demand is also increasing. Product types are gradually developing in the direction of high precision and high technology. In order to improve the electromagnetic compatibility performance of RFPC, it is usually necessary to add EMI film to the RFPC area to prevent signal crosstalk and external interference. The existing technology generally adopts a process scheme of sticking EMI after the outer layer is opened. There are many significant problems. The EMI film attachment area is located in the inner layer of RFPC, and there is a significant height difference in the structure after opening the cover. The film sticking operation must rely on manual or special jigs, which has low production efficiency and low sticking accuracy, affecting batch consistency. Since it is difficult to achieve complete filling of consumables in the high and low difference areas, it is very easy to produce local bubbling and poor pressing of the EMI film during the pressing process. The defective rate is as high as 30% to 50%, which seriously affects the shielding performance, structural reliability and delivery progress of the product. Summary of the Invention

[0003] The present application aims to solve at least one of the technical problems existing in the prior art. The present application provides an RFPC and a manufacturing method thereof, which can pre-attach EMI to the inner layer of the RFPC, thereby improving the EMI attachment accuracy and reducing the defective rate of the RFPC.

[0004] According to the embodiment of the first aspect of the present application, the RFPC manufacturing method includes the following steps:

[0005] S1 inner layer production, including:

[0006] S1.1 Inner layer circuit production: Drill holes, black hole treatment, electroplating, dry film attachment, pattern exposure, DES treatment are performed on the flexible copper clad laminate to form the inner conductive layer;

[0007] S1.2 performing printing, exposure, development and curing on the inner conductive layer to form a covering layer;

[0008] S1.3 EMI attachment: attach an EMI with a PI insulation layer to the middle of the cover layer;

[0009] S1.4 EMI fast pressing: hot pressing the RFPC with EMI attached;

[0010] S1.5 EMI release film removal;

[0011] S1.6 EMI curing: performing thermal curing on the RFPC to which the EMI is attached;

[0012] S2 outer layer making, comprising:

[0013] S2.1 Laminating and pressing: laminating and pressing the PP layer and the FR4 layer containing the copper foil layer on the EMI in sequence on the circumferential side of the EMI and performing heat pressing treatment; performing dry film attachment, pattern exposure, and DES treatment on the copper foil layer of the FR4 layer to form an outer layer conductive layer and a pad area;

[0014] S2.2 Solder resist and laser uncovering: performing solder resist treatment on the outer layer conductive layer to form a solder resist layer, and performing laser uncovering treatment on the solder resist layer to form a pad area;

[0015] S2.3 Gold plating: performing gold plating treatment on the pad area to form a surface solderable metal layer.

[0016] According to some embodiments of the present application, the heat pressing treatment in the step S2.1 laminating and pressing comprises heat pressing at a temperature of 200°C, a pressure of 40kg / cm 2 for 2 hours to determine whether the EMI is damaged, discolored, or blistered abnormally during the heat pressing treatment.

[0017] According to some embodiments of the present application, the step S2.3 gold plating comprises oil removal and nickel / gold liquid immersion treatment at a temperature of 90°C to determine whether the EMI is damaged, discolored, or blistered abnormally during the gold plating.

[0018] According to some embodiments of the present application, the processed EMI is compared with a standard EMI appearance image.

[0019] According to some embodiments of the present application, the EMI is formed by stacking a release film, a PI insulating film, a shielding film, a conductive adhesive film, and a carrier film in sequence.

[0020] According to some embodiments of the present application, the PI insulating film is a black polyimide film.

[0021] According to some embodiments of the present application, the PI insulating film has a thickness of 4.5-5.5μm, the shielding film has a thickness of 0.18-0.22μm, and the conductive adhesive film has a thickness of 6.3-7.7μm.

[0022] According to some embodiments of the second aspect of the present application, the RFPC is made by the RFPC making method described in the above embodiments.

[0023] According to some embodiments of the present application, it includes an inner conductive layer, a covering layer, EMI, a PP layer, an FR4 layer, an outer conductive layer and a solder resist layer; the inner conductive layer includes a flexible copper clad laminate, a first copper plating layer is provided on both sides of the flexible copper clad laminate, the covering layer is provided on the first copper plating layer, the EMI is provided in the middle of the covering layer, the PP layer is provided on the peripheral side of the EMI, the FR4 layer is provided on the PP layer, the outer conductive layer is provided on the FR4 layer, and the solder resist layer is provided on the outer conductive layer.

[0024] According to some embodiments of the present application, the flexible copper clad laminate includes a polyimide-based film and metal foils arranged on both sides of the polyimide-based film, and the outer conductive layer includes a copper foil layer and a second copper plating layer, and the second copper plating layer is arranged on the copper foil layer.

[0025] The RFPC and the manufacturing method thereof according to the embodiments of the present application have at least the following beneficial effects:

[0026] The RFPC and its manufacturing method of the present application form an inner conductive layer by drilling and black hole processing, electroplating, dry film attachment processing, graphic exposure, and DES processing on the flexible copper clad laminate during the inner layer production; printing oil, exposure, development and curing processing are performed on the inner conductive layer to form a covering layer; EMI with a PI insulating layer is attached to the middle of the covering layer, and the RFPC attached with EMI is subjected to heat pressing processing, and then the release film of EMI is removed, and finally the RFPC attached with EMI film is subjected to heat curing processing. The attached EMI is laminated, soldered, laser opened and gold-plated. Attaching EMI to the inner layer of RFPC in advance during the inner layer production can solve the problem of obvious height difference in the structure of RFPC after the outer layer is opened, which causes EMI local bubbles and poor compaction, thereby improving the production efficiency and quality yield of RFPC and effectively reducing the situation of refilling due to insufficient yield. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The present application is further described below with reference to the accompanying drawings and embodiments, wherein:

[0028] Figure 1 This is a schematic diagram of the structure of an RFPC according to an embodiment of the present application;

[0029] Figure 2 This is a structural diagram of EMI according to an embodiment of the present application.

[0030] Reference numerals:

[0031] Polyimide base film 11; metal foil 12; first copper plating layer 13; cover layer 14; PP layer 15; FR4 layer 16; copper foil layer 17; second copper plating layer 18; solder mask layer 19; EMI 20; release film 21; PI insulating film 22; shielding film 23; conductive adhesive film 24; carrier film 25. DETAILED DESCRIPTION

[0032] The following describes in detail embodiments of the present application. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application and are not to be construed as limiting the present application.

[0033] In the description of this application, it should be understood that if the terms "center", "middle", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "axial", "radial", "circumferential" and the like appear, the orientation or position relationship indicated is based on the orientation or position relationship shown in the accompanying drawings, which is only for the convenience of describing this application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on this application. In addition, features defined as "first" and "second" may explicitly or implicitly include one or more of such features. In the description of this application, unless otherwise specified, "multiple" means two or more.

[0034] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on the specific circumstances.

[0035] Refer to the following Figures 1 to 2 The RFPC manufacturing method in the embodiment of the present application is described.

[0036] according to Figures 1 to 2 As shown, the RFPC manufacturing method of an embodiment of the present application includes the following steps:

[0037] S1 inner layer production, including:

[0038] S1.1 Inner layer circuit production: A flexible copper-clad laminate with a polyimide substrate and double-sided metal foil 12 is selected as the starting material. First, the flexible copper-clad laminate is cut into the required size, drilled, and black-hole treated to increase the adhesion of the hole wall to facilitate the subsequent adsorption of the electroplating layer. Then, an electroplating process is performed to form a first copper-plated layer 13 on the metal foil 12. Then, a dry film is attached to the first copper-plated layer 13, and a pattern exposure and a DES process (development, etching, and stripping) are performed to form an inner conductive layer with a circuit pattern;

[0039] S1.2 printing ink on the inner conductive layer (printing ink treatment), exposing, developing and heat curing to form a covering layer 14;

[0040] S1.3 EMI20 attachment: Prefabricate EMI20, which includes a release film 21, a PI insulating film 22, a shielding film 23, a conductive adhesive film 24, and a carrier film 25. Attach the EMI20 with the PI insulating layer to the central window area of ​​the cover layer 14;

[0041] S1.4 EMI20 quick pressing: Perform heat pressing on the RFPC with EMI20 attached to ensure that the EMI20 is fully adhered to the cover layer 14;

[0042] S1.5 Removal of EMI20 release film 21: After the rapid pressing is completed and cooled, the release film 21 on the surface of EMI20 is torn off to expose the PI insulation film 22 in preparation for subsequent lamination and pressing;

[0043] S1.6 EMI20 curing: Perform thermal curing on the RFPC to which EMI20 has been attached.

[0044] S2 outer layer production, including:

[0045] S2.1 Lamination and Lamination: The RFPC with EMI20 attached is stacked and assembled with the rigid materials of the PP layer 15 and the FR4 layer 16 containing the copper foil layer 17. The whole is laminated and hot-pressed to form an overall rigid-flexible RFPC hard-flex board. After the lamination is completed, a second dry film is attached to the outer copper foil layer 17 of the FR4 layer 16, and a second pattern exposure and second DES treatment (development, etching and stripping) are performed to obtain the outer conductive pattern with the circuit pattern and the pad area.

[0046] S2.2 Solder mask and laser decapping: Solder mask treatment is performed on the surface of the outer conductive layer to form a solder mask layer 19; a pad area is formed on the solder mask layer 19 by laser decapping;

[0047] S2.3 Immersion Gold: Perform immersion gold treatment on the pad area to form a metal layer that can be soldered on the surface.

[0048] The RFPC production method of the present application can attach the EMI20 with a PI insulation layer to the inner layer of the RFPC in advance during the inner layer production, thereby solving the problem of obvious height difference in the structure of the RFPC after the outer layer is opened, which causes local bubbles and poor compaction of the attached EMI20, improves the production efficiency and quality yield of the RFPC, and effectively reduces the need for material replenishment due to insufficient yield.

[0049] In some embodiments, a chemical cleaning process is further performed between the electroplating process and the dry film attachment to clean the surface of the first copper plating layer 13 and remove impurities and residues in preparation for the film attachment.

[0050] In some embodiments, after forming the inner conductive layer having the circuit pattern, an AOI process is further included to use a machine to detect whether the circuit pattern has defects such as short circuits and open circuits.

[0051] In some embodiments, between step S1.1 and step 1.2, it also includes one sandblasting, false pasting, fast pressing, punching, XR punching, and secondary sandblasting. First sandblasting: Use fine abrasives to clean the surface of the inner conductive layer to enhance the subsequent pressing adhesion. False pasting: Pre-pasting, do a preliminary bonding test. Fast pressing: Perform the first hot pressing to form a stable structure for the inner conductive layer as a whole. Punching and XR punching: Punch out positioning holes, which are marking holes for X-Ray alignment to ensure the accuracy of subsequent EMI20 attachment. Second sandblasting: Clean the surface of the inner conductive layer again and prepare printing ink.

[0052] In some embodiments, after performing exposure, development, and thermal curing to form the cover layer 14 in step S1.2, a flying probe process is further performed to quickly detect whether the inner conductive layer circuit is conductive by using a probe.

[0053] In some embodiments, a browning treatment is further included between the S1 inner layer production and the S2 outer layer production, and the surface of the RFPC to which the EMI 20 is attached is chemically roughened to enhance adhesion.

[0054] according to Figure 1 and Figure 2 As shown, in one embodiment of the present application, in step S2.1 lamination pressing, the hot pressing treatment includes a temperature of 200°C and a pressure of 40 kg / cm 2 After 2 hours of hot pressing under the same conditions, and after the hot pressing is completed and cooled, it is determined whether the EMI20 is damaged, discolored, or blistering during the hot pressing process.

[0055] The RFPC manufacturing method of the present application is to attach the EMI20 with PI insulation layer to the inner layer of RFPC in advance during the inner layer manufacturing, and then perform subsequent lamination and pressing. 2After 2 hours of hot pressing under the same conditions, the obvious damage, delamination, discoloration or blistering of EMI20 is greatly reduced, and the production efficiency and quality yield of RFPC are improved.

[0056] according to Figure 1 and Figure 2 As shown, in one embodiment of the present application, step S2.3, immersion gold treatment, includes degreasing the surface of the RFPC (refrigerated printed circuit board) after step S2.2, followed by immersion in a nickel / gold solution at 90°C. During the immersion process, several RFPCs are randomly inspected to determine whether EMI20 has been damaged, discolored, or blistered due to chemical reactions.

[0057] The EMI20 RFPC with a PI insulation layer in this application exhibits no significant corrosion to the EMI20 during the gold deposition process using the 90°C nickel / gold solution. Observation revealed no surface damage, color change, or blistering on the EMI20 surface, demonstrating excellent structural integrity, with no edge formation or delamination, and consistent color. The PI insulation layer and overall EMI20 structure in this application exhibit excellent chemical and heat resistance, and are stable in various chemical solutions used in the RFPC gold deposition process.

[0058] according to Figure 1 and Figure 2 As shown, in one embodiment of the present application, several samples are randomly sampled for appearance inspection to determine the heat resistance and pressure resistance of EMI20 during the RFPC pressing process, and to observe whether EMI20 has abnormalities such as cracking, warping, delamination, and blistering, and the image comparison method is used to judge and analyze the appearance changes.

[0059] a. Take a comparison image (established from the standard EMI20 appearance):

[0060] After the EMI20 coating was attached and cured (before lamination and immersion gold treatment), several samples were placed under a standard light source and a high-definition microscope camera was used to capture fixed-point images of the EMI20 coating area. The captured images served as standard EMI20 appearance images. The captured areas included the EMI20 coating edge outline and the center of the EMI20 coating.

[0061] b. Post-process image acquisition:

[0062] After lamination and pressing (temperature 200℃, pressure 40kg / cm 2 , time 2h) and immersion gold (90℃ nickel / gold solution) treated RFPC samples, and the images were collected using the same light source, the same magnification and the same angle.

[0063] c. Image comparison and judgment:

[0064] Compare the processed image side by side with the standard EMI20 appearance image to determine:

[0065] Whether it is damaged: if there are obvious cracks, tears, openings on the edge of the film, etc.

[0066] Whether there is blistering: whether there is visible bulging or delamination;

[0067] Whether there is discoloration: including visible color changes from black to brown, gray, or loss of surface gloss;

[0068] d. Judgment criteria:

[0069] If there is no obvious structural damage after comparison with the standard diagram and the difference is not noticeable to the naked eye, the EMI20 is judged to be in a stable state; otherwise it is considered abnormal.

[0070] The image comparison method described above allows for a quick and visual assessment of the integrity and stability of EMI20 after lamination, lamination, and immersion gold coating. Practical verification results demonstrate that the EMI20 film structure of this application exhibits no cracks, delamination, or significant color difference after processing, when compared to the standard EMI20 appearance image. Overall, the structure is stable and the appearance is consistent.

[0071] In the prior art, conventional EMI20 insulation layers use epoxy resin ink materials. However, epoxy resin inks are only resistant to high temperatures up to 160°C. When the temperature exceeds 200°C, the ink on the insulation layer will be damaged, peeled off, and discolored. In addition, epoxy resin ink materials are not resistant to alkaline chemicals. The insulation layer that comes into contact with alkaline chemicals will be damaged, peeled off, and discolored. Figure 2 As shown, in one embodiment of the present application, EMI20 is formed by stacking a release film 21, a PI insulating film 22, a shielding film 23, a conductive adhesive film 24 and a carrier film 25 in sequence. The EMI20 insulating layer of the present application is made of polyimide PI material. The PI insulating layer is resistant to high temperatures greater than 300°C, high-intensity pressure, and an elastic modulus greater than 200GPa, which can meet the temperature and pressure conditions during the RFPC lamination and pressing process; at the same time, the PI insulating layer is acid and alkali resistant, and can be immersed in 10% sulfuric acid for 30 minutes or in 10% sodium hydroxide for 30 minutes without damage or discoloration, and can meet the immersion of RFPC in the liquid during the gold plating process. The RFPC of EMI20 with a PI insulating layer of the present application can remain stable and not damaged during the lamination and gold plating process.

[0072] according to Figure 2 As shown, in one embodiment of the present application, the PI insulating film 22 is a black polyimide film.

[0073] according to Figure 2As shown, in one embodiment of the present application, the thickness of the PI insulating film 22 is 4.5μm-5.5μm, the thickness of the shielding film 23 is 0.18μm-0.22μm, and the thickness of the conductive adhesive film 24 is 6.3μm-7.7μm. The thickness of the PI insulating film 22 is preferably 5μm, the thickness of the shielding film 23 is preferably 0.2μm, and the thickness of the conductive adhesive film 24 is preferably 7μm.

[0074] according to Figure 1 and Figure 2 As shown, an RFPC according to an embodiment of the present application is manufactured by the above-mentioned RFPC manufacturing method.

[0075] according to Figure 1 and Figure 2 As shown, in one embodiment of the present application, the RFPC includes an inner conductive layer, a cover layer 14, EMI 20, a PP layer 15, a FR4 layer 16, an outer conductive layer, and a solder resist layer 19. The inner conductive layer includes a flexible copper clad laminate, and a first copper plating layer 13 is provided on the upper and lower sides of the flexible copper clad laminate. The cover layer 14 is provided on the first copper plating layer 13, the EMI 20 is provided in the middle of the cover layer 14, the PP layer 15 is provided around the EMI 20, and the FR4 layer 16 is provided on the PP layer 15. The outer conductive layer is provided on the FR4 layer 16, and the solder resist layer 19 is provided on the outer conductive layer. The first copper plating layer 13, the cover layer 14, the EMI 20, the PP layer 15, the FR4 layer 16, the outer conductive layer, and the solder resist layer 19 are symmetrically provided on both sides of the flexible copper clad laminate.

[0076] according to Figure 1 and Figure 2 As shown, in one embodiment of the present application, the flexible copper clad laminate includes a polyimide base film 11 and metal foils 12 arranged on both sides of the polyimide base film 11, and a first copper plating layer 13 is arranged on the metal foil 12. The outer conductive layer includes a copper foil layer 17 and a second copper plating layer 18, the copper foil layer 17 is arranged on the FR4 layer 16, and the second copper plating layer 18 is arranged on the copper foil layer 17.

[0077] The following are the specific process steps of the RFPC manufacturing method of this application:

[0078] S1. Inner layer production:

[0079] S1.1 Inner layer circuit production: flexible copper clad laminate

[0080] Cutting: Select flexible copper-clad laminate with polyimide substrate + copper foil and cut it into production panels according to the drawing size;

[0081] Drilling: forming inner layer positioning holes on the flexible copper clad laminate;

[0082] Black hole: chemical pretreatment of the hole wall after drilling to improve the adhesion of the conductive layer on the hole wall;

[0083] Electroplating: chemical copper deposition, followed by electroplating to thicken the copper layer, forming a through-hole conductive structure;

[0084] Cleaning: remove electroplating residue and surface impurities to prepare for film attachment;

[0085] Dry film attachment: attach a photosensitive dry film on both sides of the copper surface to protect and form patterns;

[0086] Pattern exposure: expose the pattern on the dry film and transfer it by UV irradiation;

[0087] DES processing (development, etching, stripping): after development, etch the exposed copper layer to retain the pattern area and complete the fabrication of the double-sided conductive pattern to form the inner conductive layer.

[0088] AOI processing: detect pattern accuracy, open circuit, short circuit and other defects.

[0089] Primary sandblasting: use fine abrasive to clean the surface and enhance subsequent adhesion;

[0090] False attachment processing: pre-attach auxiliary film or positioning test material for preliminary attachment test;

[0091] Fast pressing: the first heat pressing to form a stable structure for the inner conductive layer as a whole;

[0092] Punching and X-R hole processing: punching positioning holes and marking holes for X-ray alignment to ensure the accuracy of EMI20 attachment;

[0093] Secondary sandblasting: clean the surface of the inner conductive layer again to prepare for printing.

[0094] S1.2 on the inner conductive layer

[0095] Printing: print the covering ink on the surface of the inner conductive pattern;

[0096] Exposure, development and curing: expose and develop the ink pattern, and then heat cure to form the covering layer 14.

[0097] Flying needle processing: test the continuity of the inner conductive pattern to ensure the integrity of the inner circuit.

[0098] S1.3 EMI20 attachment: attach EMI20 with PI insulating layer in the middle of the covering layer 14.

[0099] S1.4 EMI20 fast pressing: heat press the RFPC with attached EMI20.

[0100] S1.5 EMI20 release film 21 removal.

[0101] S1.6 EMI20 curing: Perform thermal curing on the RFPC attached with EMI20.

[0102] Browning treatment: Chemically roughen the surface of the RFPC to which EMI20 has been attached to enhance adhesion.

[0103] S2 outer layer production:

[0104] S2.1 Lamination and Lamination: The RFPC with EMI20 attached is stacked and assembled with the rigid materials of the PP layer 15 and the FR4 layer 16 containing the copper foil layer 17. The whole is laminated and hot-pressed to form an overall rigid-flexible RFPC. After lamination, a second dry film is attached to the outer copper foil layer 17 of the FR4 layer 16, and a second pattern exposure and second DES treatment (development, etching and stripping) are performed to obtain the outer conductive pattern with the circuit pattern and the pad area.

[0105] Second drilling: Drill again to form an outer positioning hole that penetrates the rigid-flexible layer.

[0106] Copper plating: Chemical copper plating is performed on the holes after the second drilling to prepare the base for subsequent electroplating.

[0107] Electroplating: Copper is plated inside the hole and on the outer copper surface to construct a multi-layer conductive path and form a second copper plating layer 18.

[0108] Circuit: The outer layer is coated with dry film, exposed, developed and etched to form the outer circuit pattern.

[0109] S2.2 Solder mask and laser decapping: Solder mask treatment is performed on the surface of the outer conductive layer to form a solder mask layer 19; a pad area is formed on the solder mask layer 19 by laser decapping;

[0110] Routing plate: Mechanical milling of the shape and preliminary cutting of the plate edge.

[0111] Three times sandblasting: remove residual glue and oxidized impurities on the surface and prepare for immersion gold.

[0112] S2.3 Immersion Gold: Perform immersion gold treatment on the pad area to form a metal layer that can be soldered on the surface.

[0113] Laser cutting: Precisely trim and cut the finished product shape and window outline.

[0114] Electrical testing: Use high-density probes to fully inspect the board to ensure that all paths are conductive and there are no short circuits.

[0115] Printing: Printing QR code, SN, LOGO or batch number.

[0116] FR4 reinforcement: Attach an enhanced FR4 reinforcement board to the soldering surface or the back of the socket.

[0117] Press FR4 reinforcement: Perform local hot pressing to firmly bond the reinforcement plate to the main body.

[0118] Reinforcement and curing: Perform thermal curing treatment to enhance mechanical strength and structural stability.

[0119] Routing plate: Perform final contour routing and remove process edges.

[0120] S3.FQC / FQA / Packing and Shipping:

[0121] FQC: Check appearance, size, bruises, bubbles, creases and other defects.

[0122] FQA: Perform final sampling inspection of functionality, electrical properties, marking, and dimensions.

[0123] Packing and shipping: Pack and seal the boxes according to order requirements, affix barcode labels, and arrange logistics delivery.

[0124] This application is to precisely attach the EMI20 film with PI insulation layer, metal shielding layer and conductive adhesive layer to the window area of ​​the cover layer 14 after the inner conductive pattern is completed, combined with 200℃, 40kg / cm 2 The rapid pressing treatment under certain conditions and subsequent heat curing allow the EMI20 film to be firmly embedded in the flexible copper-clad laminate structure, achieving stable conduction with the copper pad. The FPC manufacturing method of this application effectively avoids the difficulty of high-low bonding caused by the traditional method of attaching EMI20 after opening the outer layer, eliminates the bubbling and failure of EMI20 to press, and significantly improves the attachment yield from the original 30-50% to more than 97%, with the position accuracy controlled within ±0.1mm. At the same time, the black PI insulation layer used in the EMI20 film can stably withstand high-temperature hot pressing and 90°C chemical gold deposition process without damage, discoloration, or delamination, significantly improving the electromagnetic shielding performance, process compatibility, and mass production stability of the RFPC structure.

[0125] In the description of this specification, if the reference terms "one embodiment," "some examples," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples" appear, it means that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples.

[0126] The above describes the implementation methods of the present application in detail in conjunction with the accompanying drawings, but the present application is not limited to the above implementation methods. Various changes can be made within the scope of knowledge possessed by ordinary technicians in the technical field without departing from the purpose of the present application.

Claims

1. A method for manufacturing RFPC, characterized in that: The following steps are involved: S1 inner layer production, including: S1.1 Inner layer circuit production: Drill holes, black hole treatment, electroplating, dry film attachment, pattern exposure, DES treatment are performed on the flexible copper clad laminate to form the inner conductive layer; S1.2 performing printing, exposure, development and curing on the inner conductive layer to form a covering layer; S1.3 EMI attachment: attach an EMI with a PI insulation layer to the middle of the cover layer; S1.4 EMI fast pressing: hot pressing the RFPC with EMI attached; S1.5 EMI release film removal; S1.6 EMI curing: performing thermal curing on the RFPC attached with EMI; S2 outer layer production, including: S2.1 Lamination and pressing: The PP layer and the FR4 layer containing the copper foil layer are sequentially laminated on the cover layer on the peripheral side of the EMI and subjected to heat pressing treatment; the copper foil layer of the FR4 layer is subjected to dry film attachment, pattern exposure, and DES treatment to form the outer conductive layer and the pad area; S2.2 Solder mask and laser decapping: solder mask treatment is performed on the outer conductive layer to form a solder mask layer, and a pad area is formed on the solder mask layer by laser decapping; S2.3 Immersion Gold: Perform immersion gold treatment on the pad area to form a metal layer that can be soldered on the surface.

2. The RFPC manufacturing method according to claim 1, wherein: The hot pressing treatment in step S2.1 lamination pressing includes a temperature of 200°C and a pressure of 40 kg / cm 2 The EMI was subjected to heat pressing for 2 hours to determine whether it was damaged, discolored, or had abnormal bubbles during the heat pressing.

3. The RFPC manufacturing method according to claim 1, wherein: The step S2.3 of immersion gold includes degreasing and immersion in a nickel / gold solution at a temperature of 90° C. to determine whether EMI causes damage, discoloration, or blistering in the immersion gold.

4. The RFPC manufacturing method according to claim 2 or 3, characterized in that: include: The processed EMI is compared with the standard EMI appearance image.

5. The RFPC manufacturing method according to claim 1, wherein: EMI is formed by stacking release film, PI insulation film, shielding film, conductive adhesive film and carrier film in sequence.

6. The RFPC manufacturing method according to claim 5, characterized in that: The PI insulating film is a black polyimide film.

7. The RFPC manufacturing method according to claim 5, characterized in that: The thickness of the PI insulating film is 4.5 μm-5.5 μm, the thickness of the shielding film is 0.18 μm-0.22 μm, and the thickness of the conductive adhesive film is 6.3 μm-7.7 μm.

8. An RFPC, characterized in that: The RFPC is manufactured by the RFPC manufacturing method according to any one of claims 1 to 7.

9. The RFPC according to claim 8, wherein: It includes an inner conductive layer, a covering layer, EMI, a PP layer, an FR4 layer, an outer conductive layer and a solder resist layer; the inner conductive layer includes a flexible copper clad laminate, a first copper plating layer is provided on both sides of the flexible copper clad laminate, the covering layer is provided on the first copper plating layer, the EMI is provided in the middle of the covering layer, the PP layer is provided on the peripheral side of the EMI, the FR4 layer is provided on the PP layer, the outer conductive layer is provided on the FR4 layer, and the solder resist layer is provided on the outer conductive layer.

10. The RFPC according to claim 9, wherein: The flexible copper clad laminate includes a polyimide-based film and metal foils arranged on both sides of the polyimide-based film. The outer conductive layer includes a copper foil layer and a second copper plating layer, and the second copper plating layer is arranged on the copper foil layer.

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