Flexible circuit board based on nanoimprint technology and manufacturing method thereof

Abstract

The invention discloses a flexible circuit board based on a nanoimprint technology and a manufacturing method thereof. The manufacturing method of the flexible circuit board based on the nanoimprint technology comprises the following steps: providing a flexible film as a substrate material; covering the substrate material with a photocuring material or a thermosetting material with a preset thickness H, wherein the photocuring material or the thermosetting material has a volume resistance gt; 1016 omega / cm < 2 >, and the surface resistance is gt; 1016 ohm / cm, and the breakdown voltage gt; 370 kV / mm; the thickness of the cured light-cured material or thermosetting material is H1, H1 is larger than or equal to 0.6 * H and smaller than or equal to 0.9 H, the elongation at break is larger than 20%, the tensile strength is larger than 120 MPa, the elastic modulus ranges from 0.1 GPa to 3.5 GPa, the peel strength is larger than 0.5 N / mm, and the thickness of the cured light-cured material or thermosetting material is smaller than or equal to 0.6 * H and smaller than or equal to 0.9 H. The glass transition temperature is higher than 290 DEG C, the thermal decomposition temperature is higher than 350 DEG C, and the thermal expansion coefficient is smaller than or equal to 50 ppm / K.

Description

Technical Field

[0001] The present invention relates to the technical field of circuit boards, and in particular to a flexible circuit board based on nanoimprint technology and a manufacturing method thereof. Background Art

[0002] Chip on Film (COF) is an advanced packaging technology that directly packages integrated circuits (ICs) onto flexible films. It is widely used in display drivers, touch screen controls, sensors, and other fields. The line width and line spacing of FPC substrates currently used in the COF industry are generally 10-20μm. Flexible circuit boards with smaller line widths and line spacings are difficult to achieve using current additive and semi-additive methods. This presents a bottleneck in circuit board manufacturing technology. However, finer lines can integrate more functional circuits within the same area, supporting more complex circuit designs and achieving more functions. Therefore, new technical solutions are needed to produce flexible circuit boards with line widths and line spacings less than 10μm.

[0003] The above content is only used to assist in understanding the technical solution of the present invention and does not constitute an admission that the above content is prior art. Summary of the Invention

[0004] The main purpose of the present invention is to provide a flexible circuit board based on nanoimprint technology and a manufacturing method thereof, aiming to solve the above-mentioned technical problems in the prior art.

[0005] To achieve the above objectives, the present invention provides a method for manufacturing a flexible circuit board based on nanoimprint technology, the method comprising:

[0006] Providing a flexible film as a base material;

[0007] A photosetting material or a thermosetting material with a preset thickness H is covered on the base material, and the volume resistance of the photosetting material or the thermosetting material is greater than 10 16 Ω / cm 2 , surface resistance>10 16 Ω / cm, breakdown voltage>370kV / mm;

[0008] Nanoimprint technology is used on the photocurable material or thermosetting material to imprint a pattern on a mold on an imprinting device onto the photocurable material or thermosetting material, and demolding is performed after curing. The photocurable material or thermosetting material after curing has a thickness of H1, 0.6*H≤H1≤0.9H, an elongation at break greater than 20%, a tensile strength greater than 120 MPa, an elastic modulus between 0.1 GPa and 3.5 GPa, a peel strength greater than 0.5 N / mm, a glass transition temperature greater than 290° C., a thermal decomposition temperature greater than 350° C., and a thermal expansion coefficient less than 50 ppm / K.

[0009] The base material after demoulding is subjected to a semi-additive method to realize the production of metal circuits and the conduction of circuits between different layers.

[0010] Preferably, in the method for manufacturing a flexible circuit board based on nanoimprint technology, the dielectric constant of the photocurable material or the thermocurable material is less than 4.5, and the dielectric loss factor is less than 0.03.

[0011] Preferably, in the method for manufacturing a flexible circuit board based on nanoimprint technology, the photocurable material is photosensitive polyimide, and the thermosetting material is thermosetting polyimide resin.

[0012] Preferably, in the method for manufacturing a flexible circuit board based on nanoimprint technology, the step of using nanoimprint technology on the photocurable material or thermosetting material to imprint the pattern on the sub-mold on the imprinting device on the photocurable material or thermosetting material, and before the step of demolding after curing, further comprises:

[0013] Make a master mold according to the design data;

[0014] The master mold is transferred to the daughter mold to obtain the imprint mold.

[0015] Preferably, in the method for manufacturing a flexible circuit board based on nanoimprint technology, the step of fabricating metal circuits and conducting circuits between different layers by a semi-additive method on the demoulded base material includes:

[0016] The demoulded base material is subjected to drilling treatment, metallization treatment, conductive layer plating treatment, leveling treatment, seed layer etching treatment, tinning treatment, and printing protective ink treatment to obtain the flexible circuit board.

[0017] Preferably, in the method for manufacturing a flexible circuit board based on nanoimprint technology, the leveling process is a half-etching and / or chemical grinding process.

[0018] Preferably, in the method for manufacturing a flexible circuit board based on nanoimprint technology, in the step of performing drilling, metallization, conductive layer plating, leveling, seed layer etching, tinning, and printing protective ink treatment on the demoulded base material to obtain the flexible circuit board,

[0019] In the leveling process, chemical mechanical polishing is used, which includes:

[0020] A softened layer is formed by chemically reacting the chemical reagent in the polishing liquid with the surface of the conductive layer after the conductive layer is plated;

[0021] The softened layer on the surface is rubbed with a preset pressure by mechanical grinding to remove the softened layer on the surface, and this process is repeated until the conductive layer reaches a target thickness.

[0022] Preferably, in the method for manufacturing a flexible circuit board based on nanoimprint technology, the chemical reagents include at least oxides, complexes, and reaction inhibitors;

[0023] The step of chemically reacting the chemical reagent in the polishing liquid with the surface of the conductive layer after the conductive layer is plated to form a softened layer comprises:

[0024] The oxide in the chemical reagent chemically reacts with the surface of the conductive layer after the conductive layer is plated to generate a metal oxide of the conductive layer;

[0025] The metal oxide reacts with the complex in the chemical reagent to form a complex of a conductive layer, namely the softening layer;

[0026] The reaction limiting agent prevents the metal oxide and the complex in the chemical reagent from continuously reacting, so that the reaction only occurs in the surface layer of the conductive layer.

[0027] Preferably, in the method for manufacturing a flexible circuit board based on nanoimprint technology, the conductive layer is a copper layer;

[0028] The step of chemically reacting the chemical reagent in the polishing liquid with the surface of the conductive layer after the conductive layer is plated to form a softened layer comprises:

[0029] The oxide in the chemical reagent chemically reacts with the surface of the copper layer after the conductive layer is plated to generate copper oxide;

[0030] The copper oxide reacts with the complex in the chemical reagent to form a copper complex, namely the softening layer;

[0031] The step of removing the softened layer on the surface by rubbing the softened layer on the surface with a preset pressure by mechanical grinding, and repeating this process until the conductive layer reaches a target thickness, comprises:

[0032] The surface of the copper layer is rubbed at a pressure of 5-50 kPa by a rotating polishing structure and abrasive particles suspended in the polishing liquid, and the softened layer is mechanically scraped off to remove excess copper layer, and this process is repeated until the copper layer reaches the target thickness.

[0033] Preferably, in the method for manufacturing a flexible circuit board based on nanoimprint technology, in the step of performing drilling, metallization, conductive layer plating, leveling, seed layer etching, tinning, and printing protective ink treatment on the demoulded base material to obtain the flexible circuit board,

[0034] The metallization treatment includes: vacuum sputtering a seed layer on the surface of the structure, the thickness of the seed layer being 300-600 nm;

[0035] The conductive layer plating process includes: electroplating a conductive layer on the surface of the metallized structure to form a metal circuit in the middle of the printed pattern and achieve conduction between layers.

[0036] To achieve the above objectives, the present invention provides a method for manufacturing a flexible circuit board based on nanoimprint technology, the method comprising:

[0037] Providing a flexible film as a base material;

[0038] The base material is covered with a photocurable material or a thermosetting material, and pre-cured to make the surface dry. The pre-cured photocurable material or thermosetting material has a preset thickness H, and the volume resistance of the photocurable material or thermosetting material is greater than 10 16 Ω / cm 2 , surface resistance>10 16 Ω / cm, breakdown voltage>370kV / mm;

[0039] Nanoimprint technology is used on the photocurable material or thermosetting material to imprint the pattern on the sub-mold on the imprinting device on the photocurable material or thermosetting material, and demolding is performed after curing in a nitrogen environment, wherein the imprinting mold on the imprinting device is imprinted at a pressure of 0.5-0.6 MPa and a line speed of 1.5-2 m / min during imprinting. After curing, the thickness of the photocurable material or thermosetting material is H1, 0.6*H≤H1≤0.9H, the elongation at break is greater than 20%, the tensile strength is greater than 120 MPa, the elastic modulus is between 0.1 GPa and 3.5 GPa, the peel strength is greater than 0.5 N / mm, the glass transition temperature is greater than 290°C, the thermal decomposition temperature is greater than 350°C, and the thermal expansion coefficient is less than 50 ppm / K;

[0040] The demoulded base material is subjected to drilling treatment, metallization treatment, conductive layer plating treatment, leveling treatment, seed layer etching treatment, tinning treatment, and printing protective ink treatment to obtain the flexible circuit board;

[0041] The metallization treatment includes vacuum sputtering a layer of 30nm-60nm thick chromium metal on the surface of the structure, and then vacuum sputtering a layer of metal copper as a seed layer, and the thickness of the seed layer is 300-600nm.

[0042] To achieve the above-mentioned object, the present invention provides a flexible circuit board based on nanoimprint technology, wherein the flexible circuit board is manufactured using the above-mentioned method for manufacturing a flexible circuit board based on nanoimprint technology.

[0043] The present invention has at least the following beneficial effects:

[0044] The present invention provides a flexible film as a base material; a photosetting material or a thermosetting material with a preset thickness H is covered on the base material, and the volume resistance of the photosetting material or the thermosetting material is greater than 10 16 Ω / cm 2 , surface resistance>10 16 Ω / cm, breakdown voltage>370kV / mm; using nanoimprint technology on the photocurable material or thermosetting material, imprinting the pattern on the sub-mold on the imprinting device on the photocurable material or thermosetting material, and demolding after curing, wherein the thickness of the photocurable material or thermosetting material after curing is H1, 0.6*H≤H1≤0.9H, elongation at break>20%, tensile strength>120MPa, elastic modulus between 0.1GPa and 3.5GPa, peel strength>0.5N / mm, glass transition temperature>290℃, thermal decomposition temperature>350℃, thermal expansion coefficient≤50ppm / K; the base material after demolding is semi-additively processed to realize the production of metal circuits and the conduction of circuits between different layers, so as to achieve an FPC substrate with a line width and line spacing of less than 10μm / 10μm;

[0045] Furthermore, the present invention can realize circuit pattern production without using exposure and development, and can achieve smaller line width and line spacing.

[0046] Furthermore, during the leveling process, the present invention involves a chemical reaction between the chemical reagent and the surface of the conductive layer to form a softened layer. The softened layer is then mechanically polished at a predetermined pressure to rub the surface softened layer. The chemical reagent then chemically reacts with the surface of the conductive layer to form a new softened layer. The surface softened layer is then mechanically polished at a predetermined pressure to rub the surface softened layer. This process is repeated until the conductive layer reaches the target thickness. The chemical reagent then inhibits the metal oxide and its continued reaction with the chemical reagent, limiting the reaction to the surface of the conductive layer. Because the softened layer can only be removed by mechanical polishing after each softened layer is formed, the polishing thickness can be controlled, eliminating the need for continuous polishing. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 A schematic diagram of a first embodiment of a method for manufacturing a flexible circuit board based on nanoimprint technology provided by the present invention;

[0048] Figure 2 A schematic diagram of a second embodiment of the method for manufacturing a flexible circuit board based on nanoimprint technology provided by the present invention;

[0049] Figure 3 This is a schematic diagram of a third embodiment of the method for manufacturing a flexible circuit board based on nanoimprint technology provided by the present invention.

[0050] Reference numerals of the present invention:

[0051] 1-Base material, 2-Photocurable material or thermosetting material, 3-Imprinting equipment, 4-Conductive layer, 5-Seed layer, 6-Protective ink.

[0052] The purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings and in conjunction with the embodiments. DETAILED DESCRIPTION

[0053] The technical solutions of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with the embodiments. It should be noted that the embodiments of the present invention and the features therein may be combined with each other unless there is a conflict.

[0054] In embodiments of the present invention, the term "and / or" describes the association relationship between associated objects, indicating that three possible relationships exist. For example, "A and / or B" can represent three situations: A exists alone, A and B exist simultaneously, and B exists alone. The character " / " generally indicates that the associated objects are in an "or" relationship.

[0055] It should be noted that the terms "first", "second", etc. in the description and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence.

[0056] In the embodiments of the present invention, the term "plurality" refers to two or more than two, and other quantifiers are similar.

[0057] In the present invention, unless otherwise specified, the directional words used, such as "up, down, top, bottom", usually refer to the directions shown in the drawings, or to the components themselves in the vertical, perpendicular or gravity direction; similarly, for ease of understanding and description, "inside and outside" refer to the inside and outside relative to the outline of each component itself, but the above directional words are not used to limit the present invention.

[0058] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, it will be understood by those skilled in the art that in the embodiments of the present invention, many technical details are provided to enable the reader to better understand the present invention. However, even without these technical details and the various changes and modifications based on the following embodiments, the technical solutions claimed in the present invention can be implemented. The division of the following embodiments is for convenience of description and should not constitute any limitation on the specific implementation of the present invention. The various embodiments can be combined with each other and referenced to each other under the premise that there is no contradiction.

[0059] Figure 1 and Figure 3 The schematic diagram of one embodiment of the method for manufacturing a flexible circuit board based on nanoimprint technology provided by the present invention is shown. Figure 1 and Figure 3 .

[0060] In step S101, a flexible film is provided as a base material 1. The size of the base material 1 can be set as needed. In some embodiments, the base material 1 is a polyimide film; in other embodiments, the base material 1 can also be other flexible film-type base materials 1.

[0061] Step S102 is to cover the base material 1 with a photosetting material or thermosetting material 2 of a preset thickness H, wherein the volume resistance of the photosetting material or thermosetting material 2 is greater than 10 16 Ω / cm 2 , surface resistance>10 16 Ω / cm, breakdown voltage>370kV / mm. By making the volume resistance of the photosetting material or thermosetting material 2>10 16 Ω / cm 2 , surface resistance>10 16 Ω / cm can prevent short circuits and leakage between circuits, meeting the required electrical performance. By setting the breakdown voltage of the photocurable or thermosetting material 2 to >370kV / mm, it can withstand the operating voltage and avoid breakdown failure, ensuring voltage resistance. At the same time, to ensure the integrity of signal transmission in the conductive layer, prevent signal crosstalk, and reduce signal attenuation and delay, the photocurable or thermosetting material is also required to have a dielectric constant less than 4.5 and a dielectric loss factor less than 0.03.

[0062] In some embodiments, the photocurable material is a photosensitive polyimide, and the thermosetting material is a thermosetting polyimide resin. In other embodiments, the photocurable material or thermosetting material 2 can also be other materials that meet the properties of the photocurable material or thermosetting material 2 mentioned in the present invention (such as volume resistivity, surface resistivity, breakdown voltage, elongation at break, etc.).

[0063] In some other embodiments, the base material 1 may be covered with a photocurable material or a thermosetting material 2, which is pre-cured to dry the surface. The pre-cured photocurable material or thermosetting material 2 has a preset thickness H, and the volume resistivity of the photocurable material or thermosetting material 2 is greater than 10 16 Ω / cm 2 , surface resistance>10 16 Ω / cm, breakdown voltage>370kV / mm. In some embodiments, the pre-curing temperature can be 100°C, the pre-curing time can be 6 minutes, and the preset thickness H after pre-curing can be 14μm. Of course, in some other embodiments, the pre-curing temperature and pre-curing time can be determined based on the specific material of the selected photocurable material or thermosetting material 2, and the preset thickness H can be set according to actual needs.

[0064] In addition, the base material 1 can be covered with the photocurable material or the thermosetting material 2 by a coating process or a pressing process. In some other embodiments, the coating can also be performed by other processes, as long as the base material 1 can be covered with the photocurable material or the thermosetting material 2.

[0065] In step S103 , nanoimprint technology is used on the photocurable material or thermosetting material 2 to imprint the pattern on the mold on the imprinting device 3 onto the photocurable material or thermosetting material 2 .

[0066] It should be noted that before using nanoimprint technology, a master mold can be prepared based on design data; the master mold is then transferred to a daughter mold to obtain an imprint mold. In some embodiments, the master mold can be made of, but not limited to, silicone, quartz, steel, and the daughter mold can be made of, but not limited to, PET (polyethylene terephthalate), PDMS (polydimethylsiloxane), or daughter mold glue.

[0067] Curing is performed at step S104. After curing, the photocurable or thermosetting material 2 has a thickness of H1, 0.6*H≤H1≤0.9H, an elongation at break >20%, a tensile strength >120 MPa, an elastic modulus between 0.1 GPa and 3.5 GPa, a peel strength >0.5 N / mm, a glass transition temperature >290°C, a thermal decomposition temperature >350°C, and a thermal expansion coefficient ≤50 ppm / K.

[0068] In some embodiments, the imprinting mold on the imprinting device 3 may be imprinted at a pressure of 0.5-0.6 MPa and a line speed of 1.5-2 m / min. In other embodiments, the settings may be made according to specific requirements.

[0069] It should be noted that the photocurable material or thermosetting material 2 needs to have good flexibility after curing to adapt to bending and folding. Therefore, the elongation at break of the cured photocurable material or thermosetting material 2 is greater than 20%, and the tensile strength is greater than 120 MPa. The elastic modulus of the cured photocurable material or thermosetting material 2 is set to 0.1 GPa to 3.5 GPa to ensure that the mold microstructure can be fully filled during the imprinting process, while maintaining the integrity of the pattern during demolding. At the same time, low residual stress can be ensured to avoid warping or delamination of the substrate after curing. The peel strength of the cured photocurable material or thermosetting material 2 is greater than 0.5 N / mm, so that it can have good adhesion to the base material 1 (such as PI) and will not deform or fall off during subsequent processes. The glass transition temperature of the photocurable material or thermosetting material 2 is greater than 290°C, and the thermal decomposition temperature is greater than 350°C to avoid deformation or performance degradation due to thermal stress, thereby ensuring its thermal performance. The thermal expansion coefficient of the photocurable material or thermosetting material 2 is ≤50 ppm / K to ensure good dimensional stability. The above performance not only meets the process requirements in imprinting and subsequent processes, but also meets the reliability of actual products in daily applications.

[0070] In some embodiments, curing can be, but is not limited to, curing in a nitrogen environment. In other embodiments, curing can also be performed in other rare gas environments. The specific curing method can be, but is not limited to, UV curing or thermal curing, and can be set according to actual needs.

[0071] In step S105 , the mold is released. The demoulding process is a conventional technique in the nanoimprint process and will not be described in detail.

[0072] In step S106A, the demolded substrate material 1 is subjected to a semi-additive process to fabricate metal circuits and achieve interconnection between circuits in different layers. In some embodiments, step S106A may include drilling, metallizing, plating a conductive layer 4, leveling, etching the seed layer 5, tinning, and printing protective ink 6 on the demolded substrate material 1 to obtain the flexible circuit board. The leveling process may include, but is not limited to, semi-etching and / or chemical polishing.

[0073] Figure 2 A schematic diagram illustrating a second embodiment of the method for manufacturing a flexible circuit board based on nanoimprint technology provided by the present invention is shown. Figure 2 The provided solution can be a specific implementation of step S106A. Of course, in other implementations, step S106A can also include other solutions that can realize the production of metal circuits and the conduction of circuits between different layers by a semi-additive method on the base material 1 after demolding.

[0074] Step S106 involves drilling. The location and size of the drilled holes can be determined based on the design data. Drilling can achieve connectivity between circuits on different layers. Of course, in some embodiments, if connectivity between circuits on different layers is not desired, drilling may not be necessary. This can be determined based on actual design requirements.

[0075] In step S107, metallization treatment is performed. In some embodiments, a seed layer 5 is vacuum sputtered on the surface of the structure, and the thickness of the seed layer 5 is 300-600 nm. In other embodiments, a 30-60 nm thick layer of chromium metal is first vacuum sputtered on the surface of the structure, and then a layer of copper metal is vacuum sputtered as the seed layer 5, and the thickness of the seed layer 5 is 300-600 nm.

[0076] The seed layer 5 may be, but is not limited to, one or both of chromium metal and copper metal.

[0077] In step S108, a conductive layer 4 is plated. The conductive layer 4 is electroplated on the surface of the metallized structure to form a metal circuit in the middle of the printed pattern, and to achieve conduction between the layers. The metal circuit is used to transmit signals. The metal circuit, together with the photocurable material or thermosetting material 2, constitutes the line width and line spacing of the flexible circuit board, and can achieve a smaller line width and line spacing. In some embodiments, the conductive layer 4 can be a copper layer; in other embodiments, the conductive layer 4 can also be another conductive metal layer, such as silver. The printed pattern is formed into a metal circuit by electroplating, and conduction between the layers is achieved.

[0078] Taking the conductive layer 4 as a copper layer as an example, the copper layer can be electroplated, and the thickness of the copper layer in the non-circuit area after electroplating is about 3-15 μm.

[0079] Leveling treatment is performed at step S109. The conductive layer 4 on the surface of the non-circuit area is removed by the leveling method. In some embodiments, the conductive layer 4 is leveled by half etching. The half etching treatment is a chemical treatment that etches a certain thickness of the surface conductive layer by chemical solution. In other embodiments, the chemical reagents in the polishing liquid react with the surface of the conductive layer 4 after the conductive layer 4 is plated to generate a softened layer; the softened layer on the surface is rubbed with a preset pressure by mechanical grinding to remove the softened layer on the surface, and this process is repeated until the conductive layer 4 reaches the target thickness, and the chemical reagents in the polishing liquid are used to prevent the reaction from continuing.

[0080] Since the surface of the structure after step S108 may be uneven, a chemical reagent reacts with the surface of the conductive layer 4 to form a softened layer. The softened layer is then rubbed with a preset pressure by mechanical grinding. The chemical reagent then reacts with the surface of the conductive layer 4 to form a new softened layer. Mechanical grinding is then repeated with a preset pressure. This process repeats until the conductive layer 4 reaches the target thickness. Because the softened layer can only be removed by mechanical grinding after each softened layer is formed, the grinding thickness can be controlled, eliminating the need for endless grinding.

[0081] Among them, in some embodiments, the chemical reagent includes at least an oxide, a complex, and a reaction inhibitor, and the oxide in the chemical reagent chemically reacts with the surface of the conductive layer 4 after the conductive layer 4 is plated to form a metal oxide of the conductive layer 4; the metal oxide reacts with the complex in the chemical reagent to form a complex of the conductive layer 4, that is, the softening layer; the reaction limiter is used to prevent the metal oxide and the metal oxide from continuously reacting with the complex in the chemical reagent, so that the reaction only occurs on the surface of the conductive layer.

[0082] Furthermore, after the softened layer on the surface is removed by grinding, a new reaction will occur again; at this time, the reaction inhibitor can stop the continuous reaction, thereby preventing the reaction from destroying the structure of the conductive layer and affecting reliability.

[0083] Taking the conductive layer 4 as a copper layer as an example, the oxide in the chemical reagent reacts chemically with the surface of the copper layer after the conductive layer 4 is plated to generate copper oxide; the copper oxide reacts with the complex in the chemical reagent to generate a copper complex, i.e., the softened layer; then, the surface of the copper layer is rubbed at a pressure of 5-50KPa by a rotating polishing structure and abrasive particles suspended in the polishing liquid, and the softened layer is mechanically scraped off to remove excess copper layer, and this process is repeated until the copper layer reaches the target thickness, and a reaction inhibitor is used to prevent the continuous reaction.

[0084] In step S110, the seed layer 5 is etched to remove the seed layer on the surface of the thermosetting material or the photosetting material, thereby disconnecting the circuits that do not need to be connected.

[0085] In step S111, tinning is selectively performed on the required metal circuit layer according to the design. This can be achieved through conventional manufacturing processes and will not be described in detail here.

[0086] Step S112 is to print protective ink 6. After tinning, protective ink is printed on the upper and lower surfaces of the flexible circuit board according to the design to protect the metal circuit layer and the tinning layer.

[0087] Figure 3 The third embodiment of the method for manufacturing a flexible circuit board based on nanoimprint technology provided by the present invention is shown in FIG. In order to more specifically illustrate the method for manufacturing a flexible circuit board based on nanoimprint technology provided by the present invention, a specific example is provided below.

[0088] Providing a polyimide film base material 1;

[0089] The photosetting material or thermosetting material 2 is coated or pressed on the base material 1, wherein the volume resistance of the photosetting material or thermosetting material 2 is greater than 10 16 Ω / cm 2 , surface resistance>10 16 Ω / cm, breakdown voltage>370kV / mm, dielectric constant is 3.5, dielectric loss factor is less than 0.003;

[0090] Pre-curing at 100°C for 6 minutes to remove part of the solvent and achieve surface dryness, with a preset thickness H of 14 μm;

[0091] Nanoimprint technology is used on the photosetting material or thermosetting material 2 to imprint the pattern on the pre-made imprint mold on the photosetting material or thermosetting material 2 at a pressure of 0.6 MPa and a line speed of 1.5 m / min to form a circuit pattern with a line width / line spacing of 5 μm / 5 μm;

[0092] Curing is carried out at 200°C for 2 hours under a nitrogen environment. After curing, the thickness of the photocurable material or thermosetting material 2 is 10 μm. After curing, the thickness of the photocurable material or thermosetting material 2 is H1, 0.6*H≤H1≤0.9H, the elongation at break is greater than 20%, the tensile strength is greater than 120 MPa, the elastic modulus is between 0.1 GPa and 3.5 GPa, the peel strength is greater than 0.5 N / mm, the glass transition temperature is greater than 290°C, the thermal decomposition temperature is greater than 350°C, and the thermal expansion coefficient is less than 50 ppm / K.

[0093] Demolding treatment;

[0094] Drilling treatment, such as Figure 3 Step S105;

[0095] Metallization treatment: first vacuum sputter a 30nm thick layer of metal chromium on the product surface, and then vacuum sputter a 300nm thick layer of metal copper as the electroplating seed layer 5;

[0096] Copper plating treatment: metal circuits are formed by electroplating process, with a copper plating thickness of 3-15μm;

[0097] Leveling treatment, which removes the surface copper of non-circuit areas by half-etching, specifically involves allowing the oxidant in the polishing liquid to react with the copper surface first to form copper oxide; then allowing the complexing agent to react with the copper oxide to form a softened layer that is easy to remove; then, a rotating polishing pad and abrasive particles (such as SiO2, Al2O3) suspended in the polishing liquid rub the surface at a preset pressure (for example, 5-50 kPa, which can be adjusted according to the thickness of the copper to be ground) to mechanically scrape off the softened layer produced by the chemical reaction, thereby removing the excess copper layer;

[0098] The seed layer 5 is etched to disconnect unnecessary circuits, and then subjected to tinning treatment and printed with protective ink 6 to ultimately obtain a flexible circuit board with a line width / line spacing of 5 μm / 5 μm.

[0099] The present invention also provides a flexible circuit board based on nanoimprint technology, which includes an embodiment of the above-mentioned method for manufacturing a flexible circuit board based on nanoimprint technology. The beneficial effects of the above-mentioned method for manufacturing a flexible circuit board based on nanoimprint technology can also be applied to flexible circuit boards based on nanoimprint technology, so they will not be described in detail here.

[0100] In the description of this specification, reference to terms such as "this embodiment" or "other embodiments" 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 invention. In this specification, the schematic descriptions of the above terms do not necessarily refer to the same embodiment or example.

[0101] The technical features of the above embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features of the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0102] Obviously, the embodiments described above are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, those skilled in the art may make other different forms of changes or modifications without making any creative work, and all of these should fall within the scope of protection of the present invention.

Claims

1. A method for manufacturing a flexible circuit board based on nanoimprint technology, characterized in that: include: Providing a flexible film as a base material; A photosetting material or a thermosetting material with a preset thickness H is covered on the base material, and the volume resistance of the photosetting material or the thermosetting material is greater than 10 16 Ω / cm 2 , surface resistance>10 16 Ω / cm, breakdown voltage>370kV / mm; Nanoimprint technology is used on the photocurable material or thermosetting material to imprint a pattern on a mold on an imprinting device onto the photocurable material or thermosetting material, and demolding is performed after curing. The photocurable material or thermosetting material after curing has a thickness of H1, 0.6*H≤H1≤0.9H, an elongation at break greater than 20%, a tensile strength greater than 120 MPa, an elastic modulus between 0.1 GPa and 3.5 GPa, a peel strength greater than 0.5 N / mm, a glass transition temperature greater than 290° C., a thermal decomposition temperature greater than 350° C., and a thermal expansion coefficient less than 50 ppm / K. The semi-additive method is used to manufacture the metal circuits and conduct the circuits between different layers on the demoulding substrate.

2. The method for manufacturing a flexible circuit board based on nanoimprint technology according to claim 1, wherein: The dielectric constant of the photosetting material or the thermosetting material is less than 4.5, and the dielectric loss factor is less than 0.

03.

3. The method for manufacturing a flexible circuit board based on nanoimprint technology according to claim 1 or 2, characterized in that: The photocurable material is photosensitive polyimide, and the thermosetting material is heat-curable polyimide resin.

4. The method for manufacturing a flexible circuit board based on nanoimprint technology according to claim 1 or 2, characterized in that: The step of using nanoimprint technology on the photocurable material or thermosetting material to imprint the pattern on the sub-mold on the imprinting device onto the photocurable material or thermosetting material, and before the step of demoulding after curing, further comprises: Make a master mold according to the design data; The master mold is transferred to the daughter mold to obtain the imprint mold.

5. The method for manufacturing a flexible circuit board based on nanoimprint technology according to claim 1 or 2, characterized in that: The step of fabricating metal circuits and conducting circuits between different layers by a semi-additive method on the demoulded base material includes: The demoulded base material is subjected to drilling treatment, metallization treatment, conductive layer plating treatment, leveling treatment, seed layer etching treatment, tinning treatment, and printing protective ink treatment to obtain the flexible circuit board.

6. The method for manufacturing a flexible circuit board based on nanoimprint technology according to claim 5, characterized in that: The planarization process is a half-etching and / or chemical grinding process.

7. The method for manufacturing a flexible circuit board based on nanoimprint technology according to claim 5, characterized in that: In the step of performing drilling, metallization, conductive layer plating, leveling, seed layer etching, tinning, and printing protective ink treatment on the demoulding substrate to obtain the flexible circuit board, In the leveling process, chemical mechanical polishing is used, which includes: A softened layer is formed by chemically reacting the chemical reagent in the polishing liquid with the surface of the conductive layer after the conductive layer is plated; The softened layer on the surface is rubbed with a preset pressure by mechanical grinding to remove the softened layer on the surface, and this process is repeated until the conductive layer reaches a target thickness.

8. The method for manufacturing a flexible circuit board based on nanoimprint technology according to claim 7, wherein: The chemical reagents at least include oxides, complexes, and reaction inhibitors; The step of chemically reacting the chemical reagent in the polishing liquid with the surface of the conductive layer after the conductive layer is plated to form a softened layer comprises: The oxide in the chemical reagent chemically reacts with the surface of the conductive layer after the conductive layer is plated to generate a metal oxide of the conductive layer; The metal oxide reacts with the complex in the chemical reagent to form a complex of a conductive layer, namely the softening layer; The reaction limiting agent prevents the metal oxide and the complex in the chemical reagent from continuously reacting, so that the reaction only occurs in the surface layer of the conductive layer.

9. The method for manufacturing a flexible circuit board based on nanoimprint technology according to claim 8, characterized in that: The conductive layer is a copper layer; The step of chemically reacting the chemical reagent in the polishing liquid with the surface of the conductive layer after the conductive layer is plated to form a softened layer comprises: The oxide in the chemical reagent chemically reacts with the surface of the copper layer after the conductive layer is plated to generate copper oxide; The copper oxide reacts with the complex in the chemical reagent to form a copper complex, namely the softening layer; The step of removing the softened layer on the surface by rubbing the softened layer on the surface with a preset pressure by mechanical grinding, and repeating this process until the conductive layer reaches a target thickness, comprises: The surface of the copper layer is rubbed at a pressure of 5-50 kPa by a rotating polishing structure and abrasive particles suspended in the polishing liquid, and the softened layer is mechanically scraped off to remove excess copper layer, and this process is repeated until the copper layer reaches the target thickness.

10. The method for manufacturing a flexible circuit board based on nanoimprint technology according to claim 5, wherein: In the step of performing drilling, metallization, conductive layer plating, leveling, seed layer etching, tinning, and printing protective ink treatment on the demoulding substrate to obtain the flexible circuit board, The metallization treatment includes: vacuum sputtering a seed layer on the surface of the structure, the thickness of the seed layer being 300-600 nm; The conductive layer plating process includes: electroplating a conductive layer on the surface of the metallized structure to form a metal circuit in the middle of the printed pattern and achieve conduction between layers.

11. A method for manufacturing a flexible circuit board based on nanoimprint technology, characterized in that: include: Providing a flexible film as a base material; The base material is covered with a photocurable material or a thermosetting material, and pre-cured to make the surface dry. The pre-cured photocurable material or thermosetting material has a preset thickness H, and the volume resistance of the photocurable material or thermosetting material is greater than 10 16 Ω / cm 2 , surface resistance>10 16 Ω / cm, breakdown voltage>370kV / mm; Nanoimprint technology is used on the photocurable material or thermosetting material to imprint the pattern on the sub-mold on the imprinting device on the photocurable material or thermosetting material, and demolding is performed after curing in a nitrogen environment, wherein the imprinting mold on the imprinting device is imprinted at a pressure of 0.5-0.6 MPa and a line speed of 1.5-2 m / min during imprinting. After curing, the thickness of the photocurable material or thermosetting material is H1, 0.6*H≤H1≤0.9H, the elongation at break is greater than 20%, the tensile strength is greater than 120 MPa, the elastic modulus is between 0.1 GPa and 3.5 GPa, the peel strength is greater than 0.5 N / mm, the glass transition temperature is greater than 290°C, the thermal decomposition temperature is greater than 350°C, and the thermal expansion coefficient is less than 50 ppm / K; The demoulded base material is subjected to drilling treatment, metallization treatment, conductive layer plating treatment, leveling treatment, seed layer etching treatment, tinning treatment, and printing protective ink treatment to obtain the flexible circuit board; The metallization treatment includes vacuum sputtering a layer of 30nm-60nm thick chromium metal on the surface of the structure, and then vacuum sputtering a layer of metal copper as a seed layer, and the thickness of the seed layer is 300-600nm.

12. A flexible circuit board based on nanoimprint technology, characterized in that: The flexible circuit board is manufactured using the method for manufacturing a flexible circuit board based on nanoimprint technology as described in any one of claims 1 to 11.

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