A glue-free flexible copper clad plate and a preparation method thereof

Abstract

The application provides a glue-free flexible copper-clad plate and a preparation method thereof. The glue-free flexible copper-clad plate comprises a conductive layer, a first film layer and a second film layer which are stacked in sequence. One side surface of the conductive layer is provided with first protrusions, one side surface of the first film layer is provided with second protrusions, and the side of the conductive layer provided with the first protrusions is completely attached to the side of the first film layer provided with the second protrusions. The material of the first film layer is thermoplastic material, and the material of the second film layer is thermosetting material. The glue-free flexible copper-clad plate has good heat resistance, high dimensional stability, small thickness, high bending resistance and strong bonding force between the conductive layer and the first film layer.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of flexible copper clad laminate (FCCL) and magnetic material, and particularly relates to a glue-free flexible copper clad laminate and a preparation method thereof. BACKGROUND

[0002] Flexible printed circuit (FPC) is a special basic material for connecting electronic components, which has excellent performance such as lightness, thinness, structural diversity, bending resistance, etc. It can be widely used in fields such as folding mobile phones, liquid crystal displays, notebook computers, etc. Flexible copper clad laminate is one of the basic elements for making FPC. The traditional FCCL is a three-layer structure, copper layer, adhesive, base film, which is referred to as 3L-FCCL. The adhesive in 3L-FCCL is mainly epoxy, which has relatively poor thermal stability compared to polyimide (PI) substrate, resulting in the decrease of thermal stability and dimensional stability of FCCL, and the thickness of the substrate is relatively large. In recent years, with the rapid development of electronic industry, electronic products further develop towards miniaturization, lightness and high-density assembly, and the industry has begun to pay close attention to the research and application of glue-free flexible copper clad laminate. Compared with the adhesive copper clad laminate, the glue-free flexible copper clad laminate does not need adhesive, so it has good heat resistance, good dimensional stability and high reliability; at the same time, the glue-free flexible copper clad laminate is very thin and has high bending resistance.

[0003] At present, the main methods for preparing glue-free flexible copper clad laminate are coating method, lamination method and plating method. However, only the coating method cannot prepare double-sided panels; the lamination method has various structures and high peeling strength, but the thickness of copper foil is limited, and ultra-thin copper foil cannot be used. If ultra-thin copper foil is used, wrinkles are easily generated during coating or lamination, and even fracture occurs, which limits the application of the glue-free flexible copper clad laminate in high-end precision electronic products such as liquid crystal (plasma) display, liquid crystal (plasma) television based on high-density interconnection substrate (HDI) technology and flexible chip (COF) technology. The sputtering method can prepare single and double-sided panels, and the thickness of copper foil can be very thin and customized, which is suitable for ultra-fine lines and is the most promising method for preparing glue-free flexible copper clad laminate. However, when sputtering or plating method is used, the problem of the bonding force between the conductive layer and the insulating film layer is easily generated, and the problem of peeling between the insulating film layer and the conductive layer is easily generated during subsequent circuit design.

[0004] CN107517580A discloses a composite flexible copper clad laminate (FCCL) material with electromagnetic shielding function and a manufacturing method thereof. The composite FCCL material has a layered structure, which includes at least one conductive layer and at least one insulating layer, the conductive layer and the insulating layer are arranged alternately, and each layer is bonded by an adhesive. The composite FCCL material includes at least one basic layered structure, and the basic layered structure includes a magnetic adhesive base insulating layer, an adhesive intermediate layer and a metal conductive foil layer. However, the thermal stability and dimensional stability of the composite FCCL material with electromagnetic shielding function are poor, and the thickness of the substrate is relatively large.

[0005] CN111479395A discloses a preparation method of a glue-free flexible copper-clad plate. Specifically, it discloses a structural general formula of a thermoplastic polyimide film and a preparation method thereof, a glue-free flexible copper-clad plate prepared based on the thermoplastic polyimide film and a preparation method thereof. However, in the preparation method, the thermoplastic polyimide film, i.e., the thermoplastic PI film, is hot-molded with a copper foil. The method produces a single-layer polyimide film. Since the thermoplastic polyimide is prone to dimensional change under high temperature, the glue-free flexible copper-clad plate obtained by the preparation method has poor thermal stability.

[0006] CN112549688A discloses a preparation method of a flexible copper-clad plate. The method includes: providing a high-molecular fiber non-woven fabric, hot-pressing the high-molecular fiber non-woven fabric, and / or impregnating the high-molecular fiber non-woven fabric in a high-molecular solution or melt and then solidifying and forming to make the high-molecular fiber non-woven fabric form a dense high-molecular film, wherein the hot-pressing temperature is at least 20℃ lower than the thermal decomposition temperature of the high-molecular fiber non-woven fabric; providing a metal material, and pressing the high-molecular film and the metal material to obtain the flexible copper-clad plate. The flexible copper-clad plate includes the high-molecular film and the metal material layer. However, the bonding force between the high-molecular film and the metal material in the flexible copper-clad plate is poor. During use, the flexible copper-clad plate is prone to damage due to the falling of the high-molecular film.

[0007] The copper-clad plates disclosed in the prior art all have unavoidable defects and cannot meet the requirements of good heat resistance, good dimensional stability, small thickness, high bending resistance, and strong bonding force between the copper layer and the base film. Therefore, it is crucial to develop and design a new type of glue-free flexible copper-clad plate. SUMMARY

[0008] In view of the deficiencies of the prior art, the purpose of the present application is to provide a glue-free flexible copper-clad plate and a preparation method thereof. The glue-free flexible copper-clad plate has good heat resistance, high dimensional stability, small thickness, high bending resistance, and strong bonding force between the conductive layer and the first film layer.

[0009] To achieve this purpose, the present application adopts the following technical solutions:

[0010] In a first aspect, the present application provides a glue-free flexible copper-clad plate, which includes a conductive layer, a first film layer, and a second film layer stacked in sequence.

[0011] One side surface of the conductive layer is provided with a first protrusion, one side surface of the first film layer is provided with a second protrusion, and the side of the conductive layer provided with the first protrusion is completely attached to the side of the first film layer provided with the second protrusion.

[0012] The material of the first film layer is a thermoplastic material, and the material of the second film layer is a thermosetting material.

[0013] The thermoplastic material has a high thermal expansion coefficient and a large size shrinkage rate, but can be fused and pressed at high temperature; the thermosetting material has a low thermal expansion coefficient, high heat resistance, and good dimensional stability after processing.

[0014] The first protrusion of the conductive layer is matched with the thermoplastic material working at high temperature melting state, so that the side of the conductive layer provided with the first protrusion is completely attached to the side of the first film layer provided with the second protrusion, and the bonding force of the conductive layer and the first film layer is enhanced; because the thermoplastic material is easy to change in size at high temperature, the thermosetting material is arranged outside the thermoplastic material, which can improve the heat resistance and dimensional stability of the glue-free flexible copper-clad plate, and also enhance the support of the first film layer to the conductive layer.

[0015] The glue-free flexible copper-clad plate provided by the application has good heat resistance, high dimensional stability, small thickness, high bending resistance, and strong bonding force of the conductive layer and the first film layer.

[0016] As a preferred technical solution of the application, the total thickness of the conductive layer including the first protrusion is D, and the thickness of the first protrusion is H, 1 / 3D<H<1 / 2D.

[0017] In the application, the height of the first protrusion is set to ensure the thickness of the conductive layer, so as to avoid failure in later manufacturing of conductive patterns, so H<1 / 2D is required; in order to ensure the bonding strength of the conductive layer and the first film layer, too low thickness of the first protrusion will result in poor bonding force of the conductive layer and the first film layer, which cannot achieve the purpose of enhancing the bonding force of the conductive layer and the first film layer through the setting of the first protrusion, and the first film layer and the conductive layer are easy to separate during use, thereby causing failure of the glue-free flexible copper-clad plate.

[0018] Preferably, the total thickness of the conductive layer including the first protrusion is 50-100 μm, for example, it can be 50 μm, 60 μm, 70 μm, 80 μm, 90 μm or 100 μm, but is not limited to the listed values, and other values not listed in this range are also applicable.

[0019] The total thickness of the conductive layer including the first protrusion is limited to 50-100 μm, when the total thickness of the conductive layer including the first protrusion is too low, it is difficult to form the first protrusion by etching; when the total thickness of the conductive layer including the first protrusion is too high, it will affect the later manufacturing of conductive patterns.

[0020] As a preferred technical solution of the present application, the shape of the first protrusion on the surface of the conductive layer comprises any one of a "sun" character, a "return" character, a "field" character, a "mouth" character or a "eye" character, or a combination of at least two of them, for example, a combination of a "sun" character and a "return" character, a combination of a "return" character and a "field" character, a combination of a "field" character and a "mouth" character, a combination of a "mouth" character and a "eye" character, a combination of a "sun" character, a "return" character and a "field" character, a combination of a "field" character, a "mouth" character and a "eye" character, or a combination of a "sun" character, a "return" character, a "field" character and a "mouth" character.

[0021] The different shapes of the first protrusion on the surface of the conductive layer in the present application result in different contact areas of the first protrusion and the first film layer, and increasing the contact area of the first protrusion and the first film layer can enhance the bonding force between the conductive layer and the first film layer.

[0022] As a preferred technical solution of the present application, the volume of the first protrusion accounts for 10%-30% of the volume of the conductive layer, for example, it can be 10%, 15%, 20%, 25% or 30%, but is not limited to the listed values, and other values not listed in this range are also applicable.

[0023] The proportion of the volume of the first protrusion to the volume of the conductive layer is limited to 10%-30% in the present application, and when the proportion is less than 10% or greater than 30%, the bonding force between the conductive layer and the first film layer is small, and the first film layer and the conductive layer are easy to separate during use, thereby causing the failure of the adhesive-free flexible copper-clad plate.

[0024] As a preferred technical solution of the present application, the total thickness of the first film layer including the second protrusion is C, and 0.5C

[0025] In the present application, the thickness of the first film layer including the second protrusion is set, and when H>C, the first film layer including the second protrusion cannot completely cover the conductive layer including the first protrusion, and the first protrusion contacts the second film layer, which can cause the failure of the first film layer; when 0.5C>H, the bonding force between the conductive layer including the first protrusion and the first film layer including the second protrusion is small, and the first film layer and the conductive layer are easy to separate during use, thereby causing the failure of the adhesive-free flexible copper-clad plate.

[0026] Preferably, the total thickness of the first film layer including the second protrusion is 18-100 μm, for example, it can be 18 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm or 100 μm, but is not limited to the listed values, and other values not listed in this range are also applicable.

[0027] Preferably, the total thickness of the second film layer is 5-200 μm, for example, it can be 5 μm, 20 μm, 40 μm, 60 μm, 80 μm, 100 μm, 120 μm, 140 μm, 160 μm, 180 μm or 200 μm, but not limited to the listed values, other values not listed in the range are also applicable.

[0028] As a preferred technical solution of the present application, the thermoplastic material comprises thermoplastic polyester and / or thermoplastic polyimide.

[0029] Preferably, the thermosetting material comprises thermosetting polyester and / or thermosetting polyimide.

[0030] Preferably, the material of the conductive layer comprises any one or a combination of at least two of copper foil, aluminum foil or copper-beryllium alloy foil, for example, it can be a combination of copper foil and aluminum foil, a combination of aluminum foil and copper-beryllium alloy foil, a combination of copper foil and copper-beryllium alloy foil, or a combination of copper foil, aluminum foil and copper-beryllium alloy foil.

[0031] In a second aspect, the present application provides a preparation method of the glue-free flexible copper-clad plate of the first aspect, the preparation method comprising the following steps:

[0032] (1) The conductive layer has a first protrusion on one side surface, and a solution of thermoplastic material is coated on the surface to form a first film layer;

[0033] (2) The surface of the first film layer is combined with a thermosetting material to form a second film layer.

[0034] As a preferred technical solution of the present application, the preparation method further comprises etching the surface of the conductive layer to form the first protrusion.

[0035] The first protrusion formed by etching in the present application is an integral structure with the conductive layer, has strong bonding force, and is not easy to fall off.

[0036] As a preferred technical solution of the present application, the solution of thermoplastic material completely covers the first protrusion.

[0037] As a preferred technical solution of the present application, the combination comprises hot-pressing combination.

[0038] Compared with the prior art, the present application has the following beneficial effects:

[0039] The glue-free flexible copper-clad plate of the present application has good heat resistance, high dimensional stability, small thickness, high bending resistance, and strong bonding force between the conductive layer and the first film layer. BRIEF DESCRIPTION OF DRAWINGS

[0040] Figure 1A vertical sectional view of a non-glue flexible copper-clad plate in one embodiment of the present application.

[0041] Figure 2 A plan view of a conductive layer containing first protrusions in the shape of a "day" in one embodiment of the present application.

[0042] Figure 3 A plan view of a conductive layer containing first protrusions in the shape of a "day" in one embodiment of the present application.

[0043] Figure 4 A plan view of a conductive layer containing first protrusions in the shape of a "day" in one embodiment of the present application.

[0044] Figure 5 A plan view of a conductive layer containing first protrusions in the shape of a "day" in one embodiment of the present application.

[0045] Figure 6 A plan view of a conductive layer containing first protrusions in the shape of a "day" in one embodiment of the present application.

[0046] Wherein, 1-conductive layer; 2-first protrusion; 3-second protrusion; 4-first film layer; 5-second film layer. DETAILED DESCRIPTION

[0047] It should be understood that, in the description of the present application, the terms "upper", "lower", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship shown in the drawings based on the orientation or positional relationship, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second", and the like are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined with "first", "second" and the like can explicitly or implicitly include one or more of the features.

[0048] It should be noted that, in the description of the present application, unless otherwise explicitly specified and limited, the terms "provided", "connected", "connected" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium, or it can be connected inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood through specific circumstances.

[0049] The technical solutions of the present application are further illustrated below through specific embodiments.

[0050] In one specific embodiment, as shown in the drawings, the present application provides a glue-free flexible copper-clad plate, which comprises a conductive layer 1, a first film layer 4 and a second film layer 5 stacked in sequence. Figure 1

[0051] One side surface of the conductive layer 1 is provided with a first protrusion 2, one side surface of the first film layer 4 is provided with a second protrusion 3, and the side of the conductive layer 1 provided with the first protrusion 2 is completely attached to the side of the first film layer 4 provided with the second protrusion 3.

[0052] The material of the first film layer 4 is a thermoplastic material, and the material of the second film layer 5 is a thermosetting material.

[0053] The thermoplastic material has a high thermal expansion coefficient and a large size shrinkage rate, but can be fused and pressed at high temperature; the thermosetting material has a low thermal expansion coefficient, high heat resistance, and good dimensional stability after processing.

[0054] The conductive layer 1 is provided with a first protrusion 2 on one side surface, and the first protrusion 2 cooperates with the thermoplastic material that can work at a high-temperature fusion state, so that the side of the conductive layer 1 provided with the first protrusion 2 is completely attached to the side of the first film layer 4 provided with the second protrusion 3, thereby enhancing the bonding force between the conductive layer 1 and the first film layer 4; since the thermoplastic material is prone to dimensional changes at high temperature, the thermosetting material is provided on the outer side of the thermoplastic material, which on one hand improves the heat resistance and dimensional stability of the glue-free flexible copper-clad plate, and on the other hand enhances the support of the first film layer 4 to the conductive layer 1.

[0055] The glue-free flexible copper-clad plate provided by the present application has good heat resistance, high dimensional stability, small thickness, high bending resistance, and strong bonding force between the conductive layer 1 and the first film layer 4.

[0056] As a preferred technical solution of the present application, the total thickness of the conductive layer 1 including the first protrusion 2 is D, the thickness of the first protrusion 2 is H, and 1 / 3D<H<1 / 2D.

[0057] In the present application, the height of the first protrusion 2 is set to ensure the thickness of the conductive layer 1, so as to avoid failure in later production of conductive patterns, and therefore H<1 / 2D is required; in order to ensure the bonding strength between the conductive layer 1 and the first film layer 4, too low height of the first protrusion 2 will result in poor bonding force between the conductive layer 1 and the first film layer 4, which cannot achieve the purpose of enhancing the bonding force between the conductive layer 1 and the first film layer 4 through the setting of the first protrusion 2, and the first film layer 4 and the conductive layer 1 are prone to separation during use, thereby causing failure of the glue-free flexible copper-clad plate. ​

[0058] Further, the total thickness of the conductive layer 1 including the first protrusion 2 is 50-100 μm.

[0059] The total thickness of the conductive layer 1 including the first protrusion 2 is limited to 50-100 μm. First, the conductive layer 1 including the first protrusion 2 is thick enough to ensure that the first protrusion 2 can be formed by etching. Second, this thickness does not affect the later production of the conductive pattern.

[0060] Further, as shown in FIG. 2, the shape of the first protrusion 2 on the surface of the conductive layer 1 includes any one of a "day" shape as shown in FIG. 3, a "back" shape as shown in FIG. 4, a "field" shape as shown in FIG. 5, a "mouth" shape as shown in FIG. 6, or a "eye" shape as shown in FIG. 7, or a combination of at least two thereof. Figures 2-6 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6

[0061] The different shapes of the first protrusion 2 on the surface of the conductive layer 1 result in different contact areas between the first protrusion 2 and the first film layer 4. By increasing the contact area between the first protrusion 2 and the first film layer 4, the bonding force between the conductive layer 1 and the first film layer 4 can be enhanced.

[0062] Further, the volume of the first protrusion 2 accounts for 10-30% of the volume of the conductive layer 1.

[0063] The volume of the first protrusion 2 accounts for 10-30% of the volume of the conductive layer 1. When the proportion is less than 10% or greater than 30%, the bonding force between the conductive layer 1 and the first film layer 4 is small, and the first film layer 4 and the conductive layer 1 are easily separated during use, thereby causing the failure of the adhesive-free flexible copper-clad plate.

[0064] Further, the total thickness of the first film layer 4 including the second protrusion 3 is C, and 0.5C

[0065] In the present application, by setting the thickness of the first film layer 4 including the second protrusion 3, when H>C, the first film layer 4 including the second protrusion 3 cannot completely cover the conductive layer 1 including the first protrusion 2, and the first protrusion 2 contacts the second film layer 5, which causes the failure of the first film layer 4. When 0.5C>H, the bonding force between the conductive layer 1 including the first protrusion 2 and the first film layer 4 including the second protrusion 3 is small, and the first film layer 4 and the conductive layer 1 are easily separated during use, thereby causing the failure of the adhesive-free flexible copper-clad plate.

[0066] Further, the total thickness of the first film layer 4 including the second protrusion 3 is 18-100 μm. ​​​​​​

[0067] Further, the total thickness of the second film layer 5 is 5 μm-200 μm.

[0068] Further, the thermoplastic material includes thermoplastic polyester and / or thermoplastic polyimide.

[0069] Further, the thermosetting material includes thermosetting polyester and / or thermosetting polyimide.

[0070] Further, the material of the conductive layer 1 includes any one or a combination of at least two of copper foil, aluminum foil or copper-beryllium alloy foil, such as a combination of copper foil and aluminum foil, a combination of aluminum foil and copper-beryllium alloy foil, a combination of copper foil and copper-beryllium alloy foil, or a combination of copper foil, aluminum foil and copper-beryllium alloy foil.

[0071] Embodiment 1

[0072] The present embodiment provides a preparation method of a glue-free flexible copper-clad plate, which comprises the following steps:

[0073] (1) etching the surface of a copper foil with a thickness of 75 μm to form a first protrusion with a thickness of 30 μm, as shown in FIG. 1, the shape of the first protrusion on the surface of the copper foil is a "sun" character, coating a solution of thermoplastic polyimide on the side surface of the copper foil with the first protrusion, the solution of thermoplastic polyimide completely covers the first protrusion, forming a thermoplastic polyimide film layer with a total thickness of 42 μm including a second protrusion; Figure 2

[0074] (2) hot-pressing the surface of the thermoplastic polyimide film layer with thermosetting polyimide to form a glue-free flexible copper-clad plate including a thermosetting polyimide film layer with a thickness of 80 μm.

[0075] Embodiment 2

[0076] The present embodiment provides a preparation method of a glue-free flexible copper-clad plate, which comprises the following steps:

[0077] (1) etching the surface of an aluminum foil with a thickness of 50 μm to form a first protrusion with a thickness of 20 μm, as shown in FIG. 2, the shape of the first protrusion on the surface of the aluminum foil is a "back" character, coating a solution of thermoplastic polyester on the side surface of the aluminum foil with the first protrusion, the solution of thermoplastic polyester completely covers the first protrusion, forming a thermoplastic polyester film layer with a total thickness of 38 μm including a second protrusion; Figure 3

[0078] (2) hot-pressing the surface of the thermoplastic polyester film layer with thermosetting polyimide to form a glue-free flexible copper-clad plate including a thermosetting polyimide film layer with a thickness of 200 μm.

[0079] ​​Example 3

[0080] This example provides a method for preparing a non - adhesive flexible copper clad laminate. The preparation method includes the following steps:

[0081] (1) Etch the surface of a copper - beryllium alloy foil with a thickness of 100 μm to form a first protrusion with a thickness of 45 μm. As shown, the shape of the first protrusion on the surface of the copper - beryllium alloy foil is a "field" shape. Coat a solution of thermoplastic polyimide on the surface of the copper - beryllium alloy foil with the first protrusion, and the solution of thermoplastic polyimide completely covers the first protrusion to form a thermoplastic polyimide film layer with a total thickness of 85 μm including a second protrusion; Figure 4 所示,所述第一凸起在铜-铍合金箔表面的形状为“田”字形,在铜-铍合金箔具有第一凸起的一侧表面涂布热塑性聚酰亚胺的溶液,所述热塑性聚酰亚胺的溶液完全覆盖第一凸起,形成总厚度为85μm的包括第二凸起的热塑性聚酰亚胺膜层;

[0082] (2) Thermally press - laminate the surface of the thermoplastic polyimide film layer with a thermosetting polyester to form a non - adhesive flexible copper clad laminate including a thermosetting polyester film layer with a thickness of 5 μm.

[0083] Example 4

[0084] This example provides a method for preparing a non - adhesive flexible copper clad laminate. The preparation method includes the following steps:

[0085] (1) Etch the surface of a copper foil with a thickness of 60 μm to form a first protrusion with a thickness of 25 μm. As shown, the shape of the first protrusion on the surface of the copper foil is a "square" shape. Coat a solution of thermoplastic polyester on the surface of the copper foil with the first protrusion, and the solution of thermoplastic polyester completely covers the first protrusion to form a thermoplastic polyester film layer with a total thickness of 40 μm including a second protrusion; Figure 5 所示,所述第一凸起在铜箔表面的形状为“口”字形,在铜箔具有第一凸起的一侧表面涂布热塑性聚酯的溶液,所述热塑性聚酯的溶液完全覆盖第一凸起,形成总厚度为40μm的包括第二凸起的热塑性聚酯膜层;

[0086] (2) Thermally press - laminate the surface of the thermoplastic polyester film layer with a thermosetting polyester to form a non - adhesive flexible copper clad laminate including a thermosetting polyester film layer with a thickness of 100 μm.

[0087] Example 5

[0088] This example provides a method for preparing a non - adhesive flexible copper clad laminate. The preparation method includes the following steps:

[0089] (1) Etch the surface of an aluminum foil with a thickness of 80 μm to form a first protrusion with a thickness of 35 μm. As shown, the shape of the first protrusion on the surface of the aluminum foil is an "eye" shape. Coat a solution of thermoplastic polyimide on the surface of the aluminum foil with the first protrusion, and the solution of thermoplastic polyimide completely covers the first protrusion to form a thermoplastic polyimide film layer with a total thickness of 38 μm including a second protrusion; Figure 6 所示,所述第一凸起在铝箔表面的形状为“目”字形,在铝箔具有第一凸起的一侧表面涂布热塑性聚酰亚胺的溶液,所述热塑性聚酰亚胺的溶液完全覆盖第一凸起,形成总厚度为38μm的包括第二凸起的热塑性聚酰亚胺膜层;

[0090] (2) thermally compressing the surface of the thermoplastic polyimide layer with the thermosetting polyimide to form a no-glue flexible copper-clad plate including a thermosetting polyimide film layer with a thickness of 150 μm.

[0091] Example 6

[0092] This example provides a method for preparing a no-glue flexible copper-clad plate, which is the same as example 1 except that a first protrusion with a height of 22 μm is formed.

[0093] Example 7

[0094] This example provides a method for preparing a no-glue flexible copper-clad plate, which is the same as example 1 except that a first protrusion with a height of 40 μm is formed.

[0095] Example 8

[0096] This example provides a method for preparing a no-glue flexible copper-clad plate, which is the same as example 1 except that a thermoplastic polyimide film layer including a second protrusion with a total thickness of 25 μm is formed.

[0097] Example 9

[0098] This example provides a method for preparing a no-glue flexible copper-clad plate, which is the same as example 1 except that a thermoplastic polyimide film layer including a second protrusion with a total thickness of 65 μm is formed.

[0099] Comparative Example 1

[0100] This comparative example provides a method for preparing a no-glue flexible copper-clad plate, which is the same as example 1 except that step (2) is omitted.

[0101] Comparative Example 2

[0102] This comparative example provides a method for preparing a no-glue flexible copper-clad plate, which is the same as example 2 except that step (2) is omitted.

[0103] Comparative Example 3

[0104] This comparative example provides a method for preparing a no-glue flexible copper-clad plate, which is the same as example 3 except that step (2) is omitted.

[0105] Comparative Example 4

[0106] This comparative example provides a method for preparing a no-glue flexible copper-clad plate, which is the same as example 4 except that step (2) is omitted.

[0107] Comparative Example 5

[0108] The comparative example provides a preparation method of a glue-free flexible copper-clad plate, which is the same as that of Example 5 except that step (2) is omitted.

[0109] Comparative Example 6

[0110] The comparative example provides a preparation method of a glue-free flexible copper-clad plate, which is the same as that of Example 1 except that the thermosetting polyimide is directly hot-pressed on the side surface of the copper foil having the first protrusions.

[0111] Comparative Example 7

[0112] The comparative example provides a preparation method of a glue-free flexible copper-clad plate, which is the same as that of Example 2 except that the thermosetting polyimide is directly hot-pressed on the side surface of the aluminum foil having the first protrusions.

[0113] Comparative Example 8

[0114] The comparative example provides a preparation method of a glue-free flexible copper-clad plate, which is the same as that of Example 3 except that the thermosetting polyester is directly hot-pressed on the side surface of the copper-beryllium alloy foil having the first protrusions.

[0115] Comparative Example 9

[0116] The comparative example provides a preparation method of a glue-free flexible copper-clad plate, which is the same as that of Example 4 except that the thermosetting polyester is directly hot-pressed on the side surface of the copper foil having the first protrusions.

[0117] Comparative Example 10

[0118] The comparative example provides a preparation method of a glue-free flexible copper-clad plate, which is the same as that of Example 5 except that the thermosetting polyimide is directly hot-pressed on the side surface of the aluminum foil having the first protrusions.

[0119] The glue-free flexible copper-clad plates obtained in Examples 1-9 and Comparative Examples 1-10 are tested, and the testing method is as follows:

[0120] (1) Dimensional stability: tested according to IPC-TM-650 method 2.2.4, wherein "+" represents expansion, "-" represents shrinkage, MD represents the direction of mechanical travel, and TD represents the direction perpendicular to the MD direction.

[0121] (2) Bonding strength evaluation method: the prepared glue-free flexible copper-clad plate is sealed on both sides in a heat-sealing press (IDM, L0003-5 type experimental hot press) at a certain temperature and pressure for a certain period of time to obtain a PI / Cu composite film. The peeling test is performed according to the industry standard QB / T 2358-98 to obtain the peeling strength

[0122] (3) Glass transition temperature (Tg) measured by differential scanning calorimetry (DSC): The prepared PI film was tested in a differential scanning calorimeter (TA Instruments, Q100 series) at a temperature rising rate of 10℃ / min to obtain the glass transition temperature.

[0123] (3) Thermal gravimetric evaluation method: The prepared PI film was tested in a thermal gravimetric analyzer (TA Instruments, Q50 series) at a temperature rising rate of 10℃ / min to obtain the 5% weight loss temperature.

[0124] The results are shown in Table 1.

[0125] Table 1

[0126]

[0127]

[0128] From the data in Table 1, it can be seen that

[0129] (1) The heat resistance, dimensional stability, thickness, bending resistance and the bonding strength between the conductive layer and the first film layer of the glue-free flexible copper-clad plate in Examples 1-5 are good.

[0130] (2) From the comparison between Example 1 and Examples 6 and 7, it can be seen that the thickness of the first protrusion in the present application will affect the performance of the glue-free flexible copper-clad plate. In order to ensure the thickness of the conductive layer and avoid failure in the later production of conductive patterns, H<1 / 2D is required; in order to ensure the bonding strength between the conductive layer and the first film layer, too low thickness of the first protrusion will result in poor bonding strength between the conductive layer and the first film layer, which cannot achieve the purpose of enhancing the bonding strength between the conductive layer and the first film layer through the setting of the first protrusion, and the first film layer and the conductive layer are easy to separate during use, thereby leading to failure of the glue-free flexible copper-clad plate, so 1 / 3D<H is required.

[0131] (3) From the comparison between Example 1 and Examples 8 and 9, it can be seen that the total thickness of the first film layer including the second protrusion in the present application will affect the performance of the glue-free flexible copper-clad plate. When C<H, the first film layer including the second protrusion cannot completely cover the conductive layer including the first protrusion, and the first protrusion is in contact with the second film layer, which will lead to failure of the first film layer; when 0.5C>H, the bonding strength between the conductive layer including the first protrusion and the first film layer including the second protrusion is small, and the first film layer and the conductive layer are easy to separate during use, thereby leading to failure of the glue-free flexible copper-clad plate.

[0132] (4) Through the comparison of Example 1 and Comparative Examples 1-5, it can be seen that the second film layer in the present application will affect the performance of the adhesive-free flexible copper-clad plate. Since the thermoplastic material is prone to dimensional change at high temperature, the thermosetting material is arranged outside the thermoplastic material, which can improve the heat resistance and dimensional stability of the adhesive-free flexible copper-clad plate, and also enhance the support of the first film layer to the conductive layer.

[0133] (5) Through the comparison of Example 1 and Comparative Examples 6-10, it can be seen that the second film layer in the present application will affect the performance of the adhesive-free flexible copper-clad plate. The first protrusion arranged on the surface of the conductive layer can cooperate with the thermoplastic material working at high temperature melting state, so that the side of the conductive layer provided with the first protrusion is completely attached to the side of the first film layer provided with the second protrusion, and the bonding force of the conductive layer and the first film layer is enhanced.

[0134] The applicant declares that the above is only a specific embodiment of the present application, but the protection scope of the present application is not limited thereto. It should be understood by those skilled in the art that any changes or replacements within the technical scope disclosed by the present application can be easily thought out by any person skilled in the art, and all of them fall within the protection scope and disclosure scope of the present application.

Claims

1. A glueless flexible copper clad laminate characterized by, The glue-free flexible copper-clad plate comprises a conductive layer, a first film layer and a second film layer which are stacked in sequence. The conductive layer is provided with first protrusions on one side surface, and the first film layer is provided with second protrusions on one side surface, and the side of the conductive layer provided with the first protrusions is completely attached to the side of the first film layer provided with the second protrusions. The first film layer is made of thermoplastic material, and the second film layer is made of thermosetting material. The shape of the first protrusions on the surface of the conductive layer includes any one or a combination of at least two of "Ri" shape, "Hui" shape, "Tian" shape, "Kou" shape or "Mu" shape.

2. The adhesive-free flexible copper clad plate according to claim 1, wherein The total thickness of the conductive layer including the first protrusions is D, the thickness of the first protrusions is H, and 1 / 3D The total thickness of the conductive layer including the first protrusions is 50-100 μm.

3. The adhesive-free flexible copper clad laminate according to claim 1, wherein The volume of the first protrusions accounts for 10-30% of the volume of the conductive layer.

4. The adhesive-free flexible copper clad plate according to claim 2, wherein The total thickness of the first film layer including the second protrusions is C, and 0.5C The total thickness of the first film layer including the second protrusions is 18-100 μm. The total thickness of the second film layer is 5-200 μm.

5. The adhesive-free flexible copper clad laminate according to claim 1, wherein The thermoplastic material includes thermoplastic polyester and / or thermoplastic polyimide. The thermosetting material includes thermosetting polyester and / or thermosetting polyimide. The material of the conductive layer includes any one or a combination of at least two of copper foil, aluminum foil or copper-beryllium alloy foil.

6. A method for producing the adhesive-free flexible copper-clad plate according to any one of claims 1 to 5, characterized by, The preparation method comprises the following steps: (1) The side surface of the conductive layer provided with the first protrusions is coated with a solution of thermoplastic material to form the first film layer. (2) The surface of the first film layer is compounded with thermosetting material to form the second film layer.

7. The preparation method according to claim 6, characterized in that, The preparation method further comprises etching the surface of the conductive layer to form the first protrusions.

8. The preparation method according to claim 6, characterized in that, The solution of thermoplastic material completely covers the first protrusions.

9. The preparation method according to claim 6, characterized in that, The compounding comprises hot-press compounding.

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