Dry film laminating method of printed circuit board and printed circuit board
By employing a composite dry film bonding method on printed circuit boards, the problems of poor exposure and circuit breakage during etching during dry film bonding were solved, enabling the production of printed circuit boards with high precision and long bending life, reducing equipment costs and improving production stability.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-01-05
- Publication Date
- 2026-04-10
AI Technical Summary
When applying dry film to printed circuit boards using existing technology, problems such as poor exposure, broken circuits during etching, or electroplating of non-plated areas during selective plating are prone to occur. This is especially true for flexible circuit boards with high precision and high bending life requirements, where it is difficult to fabricate fine lines.
The composite dry film bonding method is adopted. The substrate includes a metal layer and a dielectric layer stacked together. The metal layer in the second region is recessed. First, a composite dry film is attached to the surface of the metal layer away from the dielectric layer. The composite dry film includes a dry film, a bonding adhesive layer and a support film. The modulus of the support film is higher than that of the dry film. After the bonding adhesive layer melts, it fills the recessed space, so that the dry film and the metal layer are tightly bonded and gaps are avoided.
It effectively avoids problems such as poor exposure, circuit breakage during etching, or electroplating of non-plated areas during selective plating, achieving successful resolution of high-precision circuits and long bending life, reducing equipment investment costs, and improving production stability and yield.
Smart Images
Figure CN121842972A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of printed circuit board manufacturing, and particularly relates to a dry film lamination method of a printed circuit board and the printed circuit board. BACKGROUND
[0002] With the development of electronic products in the direction of light and thin, high reliability, especially the through shaft type augmented reality (AR, Augmented Reality) products, extremely harsh requirements are put forward for the flexible circuit board (FPC, Flexible Printed Circuit) of the core component, such as extremely high bending life and high-precision circuit, wherein the bending life requirement reaches more than 200,000 times, and the line width / line spacing needs to reach 50 μm / 50 μm or below.
[0003] In the related art, the flexible circuit board generally includes a first area and a second area recessed relative to the first area. When the circuit is made, dry film needs to be attached on the first area and the second area, and exposure, development, etching or selective plating and other processes are performed. In this process, problems such as poor exposure, circuit side etching breakage during etching, or non-plated area plated with plating layer during selective plating may occur. SUMMARY
[0004] The present application provides a dry film lamination method of a printed circuit board and the printed circuit board, which is used to solve the problem that in the related art, when dry film is attached on the printed circuit board and exposure, development, etching or selective plating and other processes are performed, poor exposure, circuit side etching breakage during etching, or non-plated area plated with plating layer during selective plating may occur.
[0005] In a first aspect, an embodiment of the present application provides a dry film lamination method of a printed circuit board, comprising: providing a substrate, the substrate comprising a metal layer and a dielectric layer arranged in a stack, the substrate having two first areas and a second area located between the two first areas, the metal layer corresponding to the second area being recessed relative to the metal layer corresponding to the first area; attaching a composite dry film on the surface of the metal layer away from the dielectric layer and performing compression, the composite dry film comprising a dry film, a connecting adhesive layer and a supporting film arranged in sequence and in a stack, the dry film being located between the connecting adhesive layer and the metal layer, the modulus of the supporting film being higher than the modulus of the dry film, the dry film corresponding to the second area being recessed relative to the dry film corresponding to the first area, and part of the connecting adhesive layer being fused, solidified and filled in the recessed space defined by the dry film corresponding to the second area, so that the dry film is attached to the metal layer corresponding to the second area; removing the connecting adhesive layer and the supporting film.
[0006] In some embodiments, the adhesion between the connecting adhesive layer and the support film is greater than the adhesion between the connecting adhesive layer and the dry film.
[0007] In some embodiments, the adhesion between the connecting adhesive layer and the dry film is less than the adhesion between the dry film and the metal layer.
[0008] In some embodiments, the support film is a PET film or a PI film, and the connecting adhesive layer is one of a heat-conductive silicone adhesive, a silicone gel, a hot-melt adhesive, and a polyurethane adhesive.
[0009] In some embodiments, a composite dry film is attached to the surface of the metal layer away from the dielectric layer and is subjected to heat pressing.
[0010] In some embodiments, the dry film includes a photosensitive layer and a first release film stacked together, and the first release film is between the photosensitive layer and the connecting adhesive layer.
[0011] In some embodiments, the thickness of the connecting adhesive layer and / or the thickness of the support film is greater than the thickness of the photosensitive layer.
[0012] In some embodiments, before the metal layer is attached to the composite dry film and subjected to pressing, the dry film attaching method of the printed circuit board further includes: attaching the connecting adhesive layer and the support film to the dry film, the dry film and the support film being connected together by the adhesive layer to obtain the composite dry film.
[0013] In some embodiments, after the connecting adhesive layer and the support film are removed, the dry film is subjected to exposure and development.
[0014] In a second aspect, the embodiments of the present application provide a printed circuit board, which is processed by the dry film attaching method of the printed circuit board as described in the first aspect.
[0015] The dry film lamination method of the printed circuit board provided in the embodiment has the beneficial effects that: the substrate includes the metal layer and the dielectric layer which are stacked, the substrate has two first regions and a second region between the two first regions, the metal layer corresponding to the second region is recessed compared with the metal layer corresponding to the first region, and the composite dry film is attached to the surface of the metal layer away from the dielectric layer and is pressed first, the composite dry film includes the dry film, the connecting adhesive layer and the supporting film which are sequentially and stacked, the dry film is between the connecting adhesive layer and the metal layer, the modulus of the supporting film is higher than that of the dry film, so that the dry film corresponding to the second region can be recessed compared with the dry film corresponding to the first region, the connecting adhesive layer is solidified and filled in the recessed space defined by the dry film corresponding to the second region after part of the connecting adhesive layer is melted, so that the dry film can be laminated with the metal layer corresponding to the second region, and no gap is generated between the dry film corresponding to the second region and the corresponding metal layer, thereby avoiding the problems of poor exposure, circuit side etching breakage during etching or non-plating area plated with plating layer during selective plating in the process of removing the connecting adhesive layer and the supporting film and exposing, developing and etching or selective plating of the dry film.
[0016] The printed circuit board provided in the present application has the beneficial effects compared with the prior art, which can be explained by referring to the beneficial effects of the dry film lamination method of the printed circuit board provided in the present application, which will not be repeated here. BRIEF DESCRIPTION OF DRAWINGS
[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiments or prior art description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.
[0018] Figure 1 is a flow chart of the dry film lamination method of the printed circuit board in one of the embodiments of the present application; Figure 2 is a structural schematic diagram of the substrate in one of the embodiments of the present application; Figure 3 is a schematic diagram of the metal layer away from the surface of the dielectric layer in Figure 2 attaching the composite dry film; Figure 4 is a structural schematic diagram of the composite dry film in Figure 3 ; Figure 5 is a schematic diagram of pressing the substrate and the composite dry film in Figure 3 ; Figure 6 is a schematic diagram of removing the connecting adhesive layer and the supporting film of the composite dry film in Figure 5 ; Figure 7 is a structural schematic diagram of the connecting adhesive layer, the supporting film and the second release film in one of the embodiments of the present application; Figure 8 is a structural schematic diagram of the dry film in one of the embodiments of the present application.
[0019] The meanings of the marks in the figures are as follows: 10, substrate; 101, first area; 102, second area; 11, metal layer; 12, dielectric layer; 13, inner circuit layer; 20, composite dry film; 21, dry film; 211, photosensitive layer; 212, first release film; 213, carrier film; 22, connecting adhesive layer; 23, supporting film; 24, second release film. DETAILED DESCRIPTION
[0020] In order to make the objectives, technical solutions and advantages of the present application clearer, the present application will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and should not be used to limit the present application.
[0021] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element.
[0022] In addition, the terms "first", "second" are only used for descriptive purposes and should not be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "a plurality of" is two or more, unless otherwise specifically limited.
[0023] Reference to "one embodiment", "some embodiments", "an embodiment" or "embodiments" in the present application description means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. The appearances of the phrases "in one embodiment", "in some embodiments", "in other embodiments", "in additional embodiments" and so on in various places in the specification are not necessarily all referring to the same embodiment, although the phrases can be so referred to. Furthermore, the particular features, structures, or characteristics can be combined in any suitable manner in one or more embodiments.
[0024] With the development of electronic products towards light and thin, high reliability, especially the through-axis augmented reality products, the flexible circuit board of its core components is put forward extremely strict requirements, such as extremely high bending life and high-precision lines, among which the bending life requirement reaches more than 200,000 times, and the line width / line spacing needs to reach 50μm / 50μm or below.
[0025] In the related art, the flexible circuit board generally includes a first area and a second area recessed relative to the first area. When making lines, dry film needs to be attached on the first area and the second area, and exposure, development, and etching or selective plating processes are performed. The first area serves as a non-bending area, and the second area serves as a bending area.
[0026] To meet the requirements of extremely high bending life and high-precision lines, the flexible circuit board usually adopts a "layering + selective plating" design scheme.
[0027] Layering design: reducing the number of laminated layers in the bending area to reduce the thickness, thereby improving the bending performance, but this leads to a huge step difference between the non-bending area and the bending area on the board surface.
[0028] Selective plating design: selective electroplating is performed in the non-bending area to thicken the lines, while thin copper is retained in the bending area to maintain excellent ductility and overall thinness, and the copper thickness is controlled to meet the etching requirements of fine and dense lines.
[0029] However, the above design brings a prominent process contradiction: In order to ensure that the dry film can fully fill and cover the huge step of the layered area, prevent light scattering during exposure (resulting in poor exposure), copper plating in the non-plated copper area during selective plating (resulting in short circuit) or line side etching during etching, it is necessary to use a dry film with good filling and large thickness, that is, thick dry film is needed to fill the huge step.
[0030] But making fine lines requires thin dry film: in order to resolve 50μm / 50μm and below fine lines, ensure the clarity and accuracy of the lines, it is necessary to use a thin dry film with high resolution.
[0031] Therefore, the contradiction cannot be solved by using conventional film pasting methods and equipment: if a thin dry film is pasted, the platform step cannot be filled, resulting in poor adhesion of the dry film to the flexible plate circuit board in the bending area, and then causing over-etching or poor plating in the subsequent etching or plating process, resulting in problems such as fine line over-etching, even open circuit, and a series of quality problems; if a thick dry film is pasted, although the step is filled, due to the over-thickness of the thick dry film, the refraction and absorption of light in the thick film layer during exposure causes the bottom of the dry film, especially the edges of the lines and spaces, to be unable to be exposed in place, thereby causing the residual glue to be unable to be completely removed during development, resulting in blurred patterns, residual glue between lines, and even fine lines being completely "stuck" together and unable to be separated, thereby causing the fine lines to be unable to be resolved.
[0032] That is, in the existing manufacturing process, when manufacturing the lines, the dry film needs to be attached on the first area and the second area recessed relative to the first area, and the exposure, development, and etching or selective plating processes are performed. During this process, problems such as poor exposure, line side etching open circuit during etching, or non-plated area being plated with a plating layer during selective plating are prone to occur.
[0033] In view of this, the present application provides a dry film pasting method for a printed circuit board and a printed circuit board. Since the substrate includes a metal layer and a dielectric layer arranged in layers, the substrate has two first areas and a second area between the two first areas, the metal layer corresponding to the second area is recessed relative to the metal layer corresponding to the first area, and a composite dry film is first attached to the surface of the metal layer away from the dielectric layer and is then compressed. The composite dry film includes a dry film, a connecting glue layer, and a supporting film arranged in layers in sequence. The dry film is located between the connecting glue layer and the metal layer, and the modulus of the supporting film is higher than that of the dry film. Therefore, the dry film corresponding to the second area can be recessed relative to the dry film corresponding to the first area. Since part of the connecting glue layer melts, solidifies, and fills the recessed space defined by the dry film corresponding to the second area, the dry film can be attached to the metal layer corresponding to the second area. There is no gap between the dry film corresponding to the second area and the corresponding metal layer. Therefore, after removing the connecting glue layer and the supporting film, the problems of poor exposure, line side etching open circuit during etching, or non-plated area being plated with a plating layer during selective plating are prone to occur during the process of exposing, developing, and etching or selective plating of the dry film.
[0034] In order to illustrate the technical solutions of the present application, the specific embodiments will be described below in conjunction with the specific drawings.
[0035] Please refer to Figure 1 and Figure 2 , in the first aspect, the embodiments of the present application provide a dry film 21 pasting method for a printed circuit board, which comprises: S100: provide a substrate 10, the substrate 10 includes a metal layer 11 and a dielectric layer 12 which are stacked, the substrate 10 has two first regions 101 and a second region 102 between the two first regions 101, the metal layer 11 corresponding to the second region 102 is recessed compared with the metal layer 11 corresponding to the first region 101.
[0036] Wherein, the metal layer 11 can be a copper layer, an aluminum layer or a silver layer, etc. The dielectric layer 12 can include resin, glass fiber, PI (Polyimide), pure glue, etc. For example, the dielectric layer 12 includes a pure glue and a PI which are stacked. The inner part of the substrate 10 can also be provided with an inner circuit layer 13, and the adjacent inner circuit layers 13 are provided with a dielectric layer 12.
[0037] The first region 101 can be a non-bending region, and the second region 102 is a bending region. The second region 102 is a layered design, and the pure glue between the layers needs to be removed, so that the second region 102 is layered, and the first region 101 is a non-layered region and is protruding compared with the layered region, and the surface of the metal layer 11 is recessed and uneven.
[0038] It should be noted that the second region 102 generally reduces the thickness by locally reducing the number of laminated layers, thereby improving the bending performance, but this causes the metal layer 11 corresponding to the second region 102 to be recessed compared with the metal layer 11 corresponding to the first region 101, so that there is a huge stage difference on the surface of the substrate 10 (for example, for a substrate 10 with more than 6 layers, the single-side stage difference is greater than 50μm, and the overall difference between the upper and lower sides is more than 0.1mm).
[0039] S200: please refer to Figures 3 to 5 The composite dry film 20 is attached to the surface of the metal layer 11 away from the dielectric layer 12 and is pressed, the composite dry film 20 includes a dry film 21, a connecting glue layer 22 and a supporting film 23 which are sequentially and stacked, the dry film 21 is between the connecting glue layer 22 and the metal layer 11, the modulus of the supporting film 23 is higher than that of the dry film 21, the dry film 21 corresponding to the second region 102 is recessed compared with the dry film 21 corresponding to the first region 101, and part of the connecting glue layer 22 is fused and solidified to fill the recessed space defined by the dry film 21 corresponding to the second region 102, so that the dry film 21 is attached to the metal layer 11 corresponding to the second region 102.
[0040] Wherein, the composite dry film 20 can be attached to the surface of the metal layer 11 away from the dielectric layer 12 by manual or film attaching machine and pressed.
[0041] The dry film 21 can include a photosensitive layer 211 and a first release film 212 which are stacked, and the first release film 212 is between the photosensitive layer 211 and the connecting glue layer 22. The thickness of the dry film 21 is suitable for resolving 50 / μm / 50μm and below fine lines, such as thin dry film with a thickness of 20μm-35μm.
[0042] The support film 23 can be a PET (Polyethylene terephthalate) film or a PI film, and the connecting glue layer 22 can be one of a heat-conducting silicone glue, a silicone gel, a hot-melt glue, and a polyurethane glue.
[0043] In the process of attaching the composite dry film 20, the support film 23 and the connecting glue layer 22 work together with the dry film 21 to provide additional rigidity and fill the pressure, ensuring that the dry film 21 is tightly attached to the metal layer 11 corresponding to the second area 102.
[0044] The “bridging effect” of the support film 23: The support film 23 is a material with high modulus (rigidity), for example, the support film 23 is a PET film, and when its thickness increases, its bending stiffness will increase by a cubic order. Therefore, under the pressure, the support film 23 will not completely collapse into the recess space defined by the dry film 21 corresponding to the second area 102 like a thin and soft film, but will tend to “bridge” on the dry film 21 corresponding to the adjacent first area 101, supporting the recess space defined by the dry film 21 corresponding to the second area 102, which provides a flat surface at the pressure bonding site.
[0045] The “flow and filling” of the connecting glue layer 22: The connecting glue layer 22 (which can be made of epoxy or acrylic) will melt after pressure bonding and heating, with a significant decrease in viscosity, becoming a semi-liquid that can flow. Under the driving of pressure, it will flow to the recess space defined by the dry film 21 corresponding to the second area 102, and completely fill all the space, forming a close intermolecular contact with the underlying dry film 21 and the support film 23; then the connecting glue layer 22 undergoes crosslinking reaction under continuous heating, solidification and setting, changing from semi-liquid to solid and firm state; finally, a solid and firm structure is formed, which fills the recess space defined by the dry film 21 corresponding to the second area 102 and is covered by the support film 23, and the surface is flat and firm, thereby achieving the purpose of “close attachment” of the dry film 21 to the metal layer 11 corresponding to the second area 102.
[0046] Therefore, the connecting adhesive layer 22 and the supporting film 23 can fill the recessed space defined by the dry film 21 corresponding to the second area 102, the core principle being the combination of the "bridging effect" of the supporting film 23 and the "flow filling" of the connecting adhesive layer 22 after being heated and pressed, that is, the supporting film 23 does not completely collapse into the recessed space defined by the dry film 21 corresponding to the second area 102 due to its higher structural rigidity and bending resistance during pressing, while the connecting adhesive layer 22 in the middle becomes a flowable molten state under the action of pressure and heat, and is squeezed into and filled with the recessed space defined by the dry film 21 under the driving force of pressure, and then solidifies and sets, finally firmly combining the supporting film 23 above, the connecting adhesive layer 22 in the middle and the substrate 10 below into a solid and flat overall structure, thereby tightly adhering the dry film 21 at the bottom of the supporting film 23 to the metal layer 11 corresponding to the second area 102, and completing the filling of the recessed space defined by the dry film 21 corresponding to the second area 102.
[0047] It can be understood that when the metal layer 11 corresponding to the second area 102 is recessed deeper than the metal layer 11 corresponding to the first area 101, a connecting adhesive layer 22 and a supporting film 23 with sufficient thickness can be selected to ensure that the connecting adhesive layer 22 and the supporting film 23 can fill the recessed space defined by the dry film 21 corresponding to the second area 102, and the pressing is flat and bubble-free. At the same time, the thickness of the dry film 21, the modulus and stiffness of the connecting adhesive layer 22 and the supporting film 23 should also be considered to achieve the best filling effect.
[0048] S300: Please refer to Figure 6 , remove the connecting adhesive layer 22 and the supporting film 23.
[0049] Among them, the connecting adhesive layer 22 and the supporting film 23 can be removed by manual post-machine peeling.
[0050] For example, the substrate 10 with the composite dry film 20 attached is guided through a roller system and enters a station designed with a peeling knife, which peels off and winds up the connecting adhesive layer 22 and the supporting film 23 from the first release film 212 of the dry film 21 at a specific angle. At this time, only the thin dry film 21 with the first release film 212 protecting it remains on the surface of the substrate 10, which has been perfectly filled with the step.
[0051] It can be understood that the substrate 10 can be first cut into single pieces using a numerical control milling machine or a laser cutting machine, and then the connecting adhesive layer 22 and the supporting film 23 are removed from each single piece, followed by subsequent processes such as exposure and development.
[0052] It can be seen from the above that the dry film 21 attaching method of the printed circuit board provided in the embodiment of the present application, since the substrate 10 comprises the metal layer 11 and the dielectric layer 12 arranged in layers, the substrate 10 has two first regions 101 and a second region 102 located between the two first regions 101, the metal layer 11 corresponding to the second region 102 is arranged in a recessed manner compared with the metal layer 11 corresponding to the first region 101, and the composite dry film 20 is first attached to the surface of the metal layer 11 away from the dielectric layer 12 and then is pressed, the composite dry film 20 comprises the dry film 21, the connecting adhesive layer 22 and the supporting film 23 arranged in layers in sequence, the dry film 21 is located between the connecting adhesive layer 22 and the metal layer 11, the modulus of the supporting film 23 is higher than that of the dry film 21, and then the substrate 10 and the composite dry film 20 are pressed, so that the dry film 21 corresponding to the second region 102 can be arranged in a recessed manner compared with the dry film 21 corresponding to the first region 101, since part of the connecting adhesive layer 22 is fused, solidified and filled in the recessed space defined by the dry film 21 corresponding to the second region 102, the dry film 21 can be attached to the metal layer 11 corresponding to the second region 102, and no gap is generated between the dry film 21 corresponding to the second region 102 and the corresponding metal layer 11, so that after the connecting adhesive layer 22 and the supporting film 23 are removed, the problems of poor exposure, circuit side etching breakage during etching or non-plating area plated with a plating layer during selective plating can be avoided during the processes of exposure, development, etching or selective plating of the dry film 21.
[0053] It should be noted that the dry film 21 attaching method of the printed circuit board provided in the embodiment of the present application can not only reliably attach and fill the high platform stage difference area between the first region 101 and the second region 102, but also realize high-resolution circuit manufacturing, and the cost is controllable and the process is stable, so that perfect attachment and filling of the thin dry film 21 to the high platform stage difference area and successful resolution of high-precision circuits can be realized, and the needs of filling and resolution are perfectly balanced. At the same time, without purchasing expensive vacuum film attaching machines, high-quality film attaching effects can be realized by using ordinary film attaching equipment, which greatly reduces the equipment investment and maintenance cost. In addition, the risk of “dry film 21 entering the hole” caused by vacuum film attaching is avoided, the process flow is simplified, and the stability of production and the final yield of products are improved. Moreover, the dry film 21 attaching method of the printed circuit board provided in the embodiment of the present application is not only suitable for large-scale continuous production in a roll-to-roll manner, but also suitable for batch production in a sheet-to-sheet manner, and has strong flexibility and is easy to popularize and apply in existing production lines.
[0054] The dry film 21 attaching method of the printed circuit board provided in the embodiment of the present application has strong universality, and can effectively solve the problems of board surface stage difference caused by various reasons such as HDI (High Density Interconnector), rigid-flexible combined board, local thickening, etc., and is not limited to layered design of flexible circuit boards.
[0055] Optionally, the adhesion between the connecting adhesive layer 22 and the support film 23 is greater than the adhesion between the connecting adhesive layer 22 and the dry film 21.
[0056] In this way, the connecting adhesive layer 22 and the support film 23 can be removed conveniently.
[0057] Optionally, the adhesion between the connecting adhesive layer 22 and the dry film 21 is less than the adhesion between the dry film 21 and the metal layer 11.
[0058] In this way, the dry film 21 and the metal layer 11 can be prevented from being separated when the connecting adhesive layer 22 and the support film 23 are removed.
[0059] In some embodiments, the support film 23 is a PET film or a PI film, and the connecting adhesive layer 22 is one of a heat-conductive silicone, a silicone gel, a hot-melt adhesive, and a polyurethane adhesive.
[0060] By using the above scheme, the structure of the support film 23 and the connecting layer can be relatively simple.
[0061] Optionally, the composite dry film 20 is attached to the surface of the metal layer 11 away from the dielectric layer 12 and is subjected to heat pressing.
[0062] In this way, it can be ensured that part of the connecting adhesive layer 22 is solidified after melting and sufficiently fills the recess space defined by the dry film 21 corresponding to the second region 102, so that the dry film 21 is attached to the metal layer 11 corresponding to the second region 102.
[0063] For example, the composite dry film 20 can be attached to the surface of the metal layer 11 away from the dielectric layer 12 by a film-attaching machine under certain temperature (for example, 110±10°C) and pressure.
[0064] Optionally, the dry film 21 comprises a photosensitive layer 211 and a first release film 212 stacked, and the first release film 212 is located between the photosensitive layer 211 and the connecting adhesive layer 22.
[0065] In this way, the connecting adhesive layer 22 and the support film 23 can be removed from the first release film 212 conveniently and without leaving glue.
[0066] For example, the first release film 212 can be a polyethylene film.
[0067] Optionally, the thickness of the connecting adhesive layer 22 and / or the thickness of the support film 23 is greater than the thickness of the photosensitive layer 211.
[0068] For example, the thickness of the connecting adhesive layer 22 is greater than the thickness of the photosensitive layer 211.
[0069] In this way, it can be ensured that part of the connecting adhesive layer 22 is solidified after melting and sufficiently fills the recess space defined by the dry film 21 corresponding to the second region 102.
[0070] As an implementable manner, the thickness of the support film 23 is greater than the thickness of the photosensitive layer 211.
[0071] In this way, the support film 23 can have higher structural rigidity and bending resistance.
[0072] Optionally, the thickness of the connecting adhesive layer 22 is greater than the maximum recess depth of the metal layer 11 corresponding to the second area 102 relative to the metal layer 11 corresponding to the first area 101.
[0073] In this way, the part of the connecting adhesive layer 22 can be ensured to melt, solidify and sufficiently fill the recess space defined by the dry film 21 corresponding to the second area 102, so that the dry film 21 is tightly attached to the metal layer 11 corresponding to the second area 102.
[0074] For example, the maximum recess depth of the metal layer 11 corresponding to the second area 102 relative to the metal layer 11 corresponding to the first area 101 is 50 μm, the thickness of the connecting adhesive layer 22 is greater than 50 μm, and the sum of the thicknesses of the support film 23 and the connecting adhesive layer 22 is greater than the maximum recess depth of the metal layer 11 corresponding to the second area 102 relative to the metal layer 11 corresponding to the first area 101, which can be 50 μm-100 μm.
[0075] For reference Figures 1 to 8 In some embodiments, before the dry film 21 of the printed circuit board is attached to the composite dry film 20 and is laminated, the method further comprises: attaching the connecting adhesive layer 22 and the support film 23 to the dry film 21, and the dry film 21 and the support film 23 are connected together through the adhesive layer to obtain the composite dry film 20.
[0076] By using the above scheme, the composite dry film 20 can be obtained more conveniently.
[0077] It should be noted that the dry film 21 can further comprise a carrier film 213, which can be a polyester film. Before the dry film 21 is attached to the composite dry film 20 and is laminated, the carrier film 213 is removed. The side of the connecting adhesive layer 22 away from the support film 23 can also be attached to a second release film 24. Before the dry film 21 is attached to the connecting adhesive layer 22 and the support film 23, the second release film 24 is removed.
[0078] Optionally, after the connecting adhesive layer 22 and the support film 23 are removed, the dry film 21 is exposed and developed.
[0079] In this way, the dry film 21 can be attached to the metal layer 11 corresponding to the second area 102, and no gap can be generated between the dry film 21 corresponding to the second area 102 and the corresponding metal layer 11, so that the problems of poor exposure, broken circuit on the line side during etching, or plated layer on the non-plating area during selective plating can be avoided during the processes of exposure, development, and etching or selective plating of the dry film 21.
[0080] For example, the substrate 10 with the dry film 21 can be placed in an exposure machine, the first release film 212 is removed (or not removed in some processes), and standard processes such as pattern exposure, development, and acid etching or selective plating are performed, so that a flexible circuit board with excellent second area 102 and high-precision lines is finally obtained.
[0081] In a second aspect, the embodiments of the present application provide a printed circuit board processed by the dry film 21 attaching method of the printed circuit board as in the first aspect.
[0082] The printed circuit board provided by the embodiments of the present application is processed by the dry film 21 attaching method of the printed circuit board as in the first aspect. The substrate 10 includes the metal layer 11 and the dielectric layer 12 arranged in layers, the substrate 10 has two first areas 101 and a second area 102 between the two first areas 101, the metal layer 11 corresponding to the second area 102 is recessed compared with the metal layer 11 corresponding to the first area 101, the composite dry film 20 is first attached to the surface of the metal layer 11 away from the dielectric layer 12 and then is pressed, the composite dry film 20 includes the dry film 21, the connecting adhesive layer 22, and the supporting film 23 arranged in layers in sequence, the dry film 21 is located between the connecting adhesive layer 22 and the metal layer 11, the modulus of the supporting film 23 is higher than that of the dry film 21, and then the substrate 10 and the composite dry film 20 are pressed, so that the dry film 21 corresponding to the second area 102 can be recessed compared with the dry film 21 corresponding to the first area 101. Since part of the connecting adhesive layer 22 is melted, solidified, and filled in the recessed space defined by the dry film 21 corresponding to the second area 102, the dry film 21 can be attached to the metal layer 11 corresponding to the second area 102, and no gap can be generated between the dry film 21 corresponding to the second area 102 and the corresponding metal layer 11, so that the problems of poor exposure, broken circuit on the line side during etching, or plated layer on the non-plating area during selective plating can be avoided during the processes of exposure, development, and etching or selective plating of the dry film 21 after the connecting adhesive layer 22 and the supporting film 23 are removed.
[0083] The above examples are only used to illustrate the technical solutions of the present application, but not limit the same; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that the technical solutions recorded in the foregoing examples can be modified, or some technical features can be replaced by equivalent ones; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should be included in the protection scope of the present application.
Claims
1. A dry film lamination method for printed circuit boards, characterized in that, include: A substrate is provided, the substrate including a stacked metal layer and a dielectric layer, the substrate having two first regions and a second region located between the two first regions, wherein the metal layer corresponding to the second region is recessed relative to the metal layer corresponding to the first region; A composite dry film is attached to the surface of the metal layer opposite to the dielectric layer and then pressed together. The composite dry film includes a dry film, a connecting adhesive layer, and a support film arranged sequentially and in layers. The dry film is located between the connecting adhesive layer and the metal layer. The modulus of the support film is higher than that of the dry film. The dry film corresponding to the second region is recessed compared to the dry film corresponding to the first region. After a portion of the connecting adhesive layer melts and solidifies, it fills the recessed space defined by the dry film corresponding to the second region, so that the dry film adheres to the metal layer corresponding to the second region. Remove the adhesive layer and the support film.
2. The dry film lamination method for printed circuit boards according to claim 1, characterized in that, The adhesive force between the adhesive layer and the support film is greater than the adhesive force between the adhesive layer and the dry film.
3. The dry film bonding method for printed circuit boards according to claim 2, characterized in that, The adhesive force between the adhesive layer and the dry film is less than the adhesive force between the dry film and the metal layer.
4. The dry film bonding method for printed circuit boards according to claim 1, characterized in that, The supporting film is a PET film or a PI film, and the connecting adhesive layer is one of thermally conductive silicone, silicone gel, hot melt adhesive, and polyurethane adhesive.
5. The dry film bonding method for printed circuit boards according to claim 1, characterized in that, A composite dry film is attached to the surface of the metal layer opposite to the dielectric layer and then hot-pressed.
6. The dry film bonding method for printed circuit boards according to claim 1, characterized in that, The dry film includes a photosensitive layer and a first release film stacked together, wherein the first release film is located between the photosensitive layer and the adhesive layer.
7. The dry film bonding method for printed circuit boards according to claim 6, characterized in that, The thickness of the adhesive layer and / or the thickness of the support film is greater than the thickness of the photosensitive layer.
8. The dry film bonding method for printed circuit boards according to any one of claims 1 to 7, characterized in that, Before attaching the composite dry film to the surface of the metal layer opposite to the dielectric layer and laminating it, the dry film lamination method for the printed circuit board further includes: The adhesive layer and the support film are attached to the dry film, and the dry film and the support film are connected together by the adhesive layer to obtain the composite dry film.
9. The dry film bonding method for printed circuit boards according to any one of claims 1 to 7, characterized in that, After removing the adhesive layer and the support film, the dry film is exposed and developed.
10. A printed circuit board, characterized in that, The printed circuit board is manufactured by the dry film lamination method for printed circuit boards as described in any one of claims 1 to 9.