Composite metal foil, substrate with carrier, and flexible coverlay sheet

Abstract

The application discloses a composite metal foil, a substrate with a carrier and a flexible foil-coated plate. The composite metal foil comprises a carrier layer, a stripping layer, a metal foil and a protective layer which are sequentially stacked. The protective layer comprises a covering part and an extending part. The covering part covers the metal foil and is not bonded to the metal foil. The extending part extends along at least two opposite side walls of the composite metal foil and is bonded to the carrier layer. On the one hand, foreign matters can be prevented from adhering to the metal foil. On the other hand, the metal foil can be prevented from being damaged when the protective layer is stripped. In addition, when the protective layer is stripped, the adhesive or the protective layer can also be prevented from leaving residues on the metal foil, so that subsequent pressing is facilitated. When the protective layer is stripped, only the extending part needs to be damaged, and then the protective layer can be removed, so that the process is simple. When the protective layer is stripped, even if the carrier layer is damaged or the carrier layer has residues of the adhesive or the protective layer, the metal foil will not be affected.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of metal foil, in particular to a composite metal foil, a substrate with a carrier and a flexible foil-coated board. BACKGROUND

[0002] With the high-density integration of electronic components, the wiring pattern of the circuit substrate is also increasingly high-density (i.e. forming a fine line board). But when the required line is thin, the line may be disconnected due to the long residence time of the etching liquid. Therefore, the formation of a fine line board requires the use of an extremely thin metal foil.

[0003] In the prior art, when preparing a fine line board, a composite metal foil (including a carrier layer and a metal foil layer) is first laminated with an insulating base film on the side provided with the metal foil layer, thereby obtaining a substrate with a carrier. In use, the carrier layer needs to be peeled off, and then a fine line board is obtained through an etching process.

[0004] Before the composite metal foil and the insulating base film are laminated, foreign matter may sometimes adhere to the metal foil layer. Due to the presence of foreign matter, the metal foil layer and the insulating base film may not be completely laminated, resulting in the explosion of the metal foil layer (i.e. the metal foil layer falls off from the insulating base film) after peeling. In addition, due to the presence of foreign matter, the circuit may sometimes have defects such as disconnection and short circuit when the circuit is formed by subsequent etching, resulting in a decrease in yield. SUMMARY

[0005] The embodiments of the present application provide a composite metal foil, a substrate with a carrier and a flexible foil-coated board, which can protect the metal foil of the composite metal foil, avoid foreign matter adhering to the metal foil, and improve the yield.

[0006] In a first aspect, the embodiments of the present application provide a composite metal foil, comprising a carrier layer, a peeling layer, a metal foil and a protective layer;

[0007] The peeling layer is formed on one side of the carrier layer;

[0008] The metal foil is formed on the side of the peeling layer away from the carrier layer;

[0009] The protective layer comprises a covering portion and an extending portion;

[0010] The covering portion covers the metal foil, and the covering portion is not bonded to the metal foil;

[0011] The extending portion extends along at least two opposite side walls of the composite metal foil, and the extending portion is bonded to the carrier layer.

[0012] Optionally, the extending portion comprises a first portion and a second portion, the first portion is arranged on the side wall of the composite metal foil, and the second portion is bonded to the carrier layer.

[0013] Optionally, the second part is arranged on a side of the carrier layer away from the peeling layer.

[0014] Optionally, there is a space in horizontal direction between each of the at least two opposite edges of the carrier layer and the corresponding edge of the peeling layer, and the at least two opposite edges of the carrier layer are located at the periphery of the corresponding edge of the peeling layer, defining an area between one edge of the carrier layer and the corresponding edge of the peeling layer as a vacant area, and the second part is arranged in the vacant area.

[0015] Optionally, the extension is bonded to the carrier layer through a bonding part, and the bonding part is arranged in a linear and / or dot-like form.

[0016] Optionally, the protective layer is a metal foil or an organic film.

[0017] Optionally, the composite metal foil further comprises a barrier layer arranged between the carrier layer and the peeling layer.

[0018] Optionally, the barrier layer comprises a high-temperature-resistant layer, and the high-temperature-resistant layer is an organic high-temperature-resistant layer; or the high-temperature-resistant layer is made of any one or more of tungsten, chromium, zirconium, titanium, nickel, molybdenum, cobalt and graphite.

[0019] Optionally, the peeling layer is made of any one or more of nickel, silicon, molybdenum, graphite, titanium and niobium; or the peeling layer is made of an organic polymer material.

[0020] Optionally, the metal foil is a copper foil or an aluminum foil; and the carrier layer is a carrier copper, a carrier aluminum or an organic film.

[0021] In a second aspect, an embodiment of the present application provides a substrate with a carrier, comprising a flexible substrate and an intermediate body, the intermediate body being obtained by removing the protective layer from the composite metal foil provided in the first aspect of the present application, and the intermediate body being arranged on one side of the flexible substrate.

[0022] The intermediate body comprises a carrier layer, a peeling layer and a metal foil.

[0023] The peeling layer is formed on one side of the carrier layer.

[0024] The metal foil is formed on a side of the peeling layer away from the carrier layer.

[0025] The metal foil is attached to the flexible substrate.

[0026] In a third aspect, an embodiment of the present application provides a preparation method of a flexible foil-coated plate, comprising:

[0027] A flexible substrate and a composite metal foil are provided; the composite metal foil includes a carrier layer, a release layer, a metal foil, and a protective layer; the release layer is formed on one side of the carrier layer; the metal foil is formed on the side of the release layer away from the carrier layer; the protective layer includes a cover portion and an extension portion; the cover portion covers the metal foil and is not bonded to the metal foil; the extension portion extends along at least two opposing sidewalls of the composite metal foil and is bonded to the carrier layer;

[0028] The protective layer is removed to obtain an intermediate, which includes a carrier layer, a release layer, and a metal foil.

[0029] The metal foil of the intermediate is bonded to the flexible substrate;

[0030] Peel off the carrier layer to separate it from the metal foil, thus obtaining a flexible foil-coated board.

[0031] Fourthly, embodiments of the present invention provide a flexible foil-coated board, which is prepared by the method for preparing a flexible foil-coated board as provided in the third aspect of the present invention, comprising: a flexible substrate and a metal foil coated on the flexible substrate.

[0032] The composite metal foil provided in this invention includes a carrier layer, a release layer, a metal foil, and a protective layer stacked sequentially. The protective layer includes a covering portion and an extension portion. The covering portion covers the metal foil but is not bonded to it. The extension portion extends along at least two opposite sidewalls of the composite metal foil and is bonded to the carrier layer. This design prevents foreign matter from adhering to the metal foil and avoids damage to the metal foil during the peeling of the protective layer. Furthermore, peeling the protective layer also prevents adhesive residue or protective layer residue from remaining on the metal foil, facilitating subsequent lamination. Peeling the protective layer simply requires breaking the extension portion and then removing the protective layer, simplifying the process. Even if the carrier layer is damaged or has adhesive residue or protective layer residue, peeling the protective layer will not affect the metal foil. Attached Figure Description

[0033] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments.

[0034] Figure 1 This is a schematic diagram of the structure of a composite metal foil provided in an embodiment of the present invention;

[0035] Figure 2 for Figure 1 A magnified view of a portion of the junction A between the metal foil and the covering part;

[0036] Figure 3 for Figure 1 A bottom view of a composite metal foil;

[0037] Figure 4 This is a schematic diagram of another composite metal foil provided in an embodiment of the present invention;

[0038] Figure 5 for Figure 4 Top view of composite metal foil;

[0039] Figure 6 This is a schematic diagram of another composite metal foil provided in an embodiment of the present invention;

[0040] Figure 7 This is a schematic diagram of the structure of a substrate with a carrier provided in an embodiment of the present invention;

[0041] Figure 8 A schematic diagram of another substrate with a carrier provided in an embodiment of the present invention;

[0042] Figure 9 A flowchart illustrating a method for preparing a flexible foil-coated board for implementing this invention;

[0043] Figure 10 This is a schematic diagram illustrating the separation of the carrier layer and the metal foil in an embodiment of the present invention;

[0044] Figure 11 This is a schematic diagram of the structure of a flexible foil-coated board provided in an embodiment of the present invention.

[0045] Figure label:

[0046] 110, Carrier layer; 120, Release layer; 130, Metal foil; 140, Protective layer; 141, Covering portion; 142, Extension portion; 1421, Adhesive portion; 1422, First part; 1423, Second part; 150, Barrier layer; 151, Metal bonding layer; 152, High temperature resistant layer; 100, Intermediate; 200, Flexible substrate. Detailed Implementation

[0047] To make the technical problems solved by the present invention, the technical solutions adopted, and the technical effects achieved clearer, the technical solutions of the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0048] In the description of this invention, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0049] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0050] To address the above problems, embodiments of the present invention provide a composite metal foil. Figure 1 This is a schematic diagram of the structure of a composite metal foil provided in an embodiment of the present invention, as shown below. Figure 1 As shown, the composite metal foil includes a carrier layer 110, a release layer 120, a metal foil 130, and a protective layer 140.

[0051] The release layer 120 is formed on one side of the carrier layer 110, and the metal foil 130 is formed on the side of the release layer 120 away from the carrier layer 110. The release layer 120 is made of a brittle material, and during subsequent peeling, the separation surface can be the interface between the carrier layer 110 and the release layer 120, or the interface between the release layer 120 and the metal foil 130, or it can be peeled off from the middle of the release layer 120.

[0052] A protective layer 140 covers the metal foil 130 to prevent foreign matter from adhering to the metal foil 130. The protective layer 140 includes a covering portion 141 and an extension portion 142. The covering portion 141 covers the metal foil 130 but is not bonded to the metal foil 130. Figure 2 for Figure 1 A magnified view of a portion of the junction A between the metal foil and the covering, as shown below. Figure 2As shown, the surface of the metal foil 130 is not directly bonded to the covering portion 141, but rather there is a certain gap, or the surface of the metal foil 130 is in contact with the covering portion 141, but there is no adhesion between the contact surfaces. Through the above design, on the one hand, foreign matter can be prevented from adhering to the metal foil 130, and on the other hand, damage to the metal foil 130 can be avoided when peeling off the protective layer 140. Furthermore, since the covering portion 141 is not bonded to the metal foil 130, when peeling off the protective layer 140, residues of adhesive or the protective layer 140 can be avoided on the metal foil 130, facilitating subsequent pressing.

[0053] The extension 142 extends along at least two opposing sidewalls of the composite metal foil and is bonded to the carrier layer 110. When peeling off the protective layer 140, only the extension 142 needs to be broken, and then the protective layer 140 can be peeled off, simplifying the process. Furthermore, since the carrier layer 110 needs to be peeled off subsequently, bonding the extension 142 of the protective layer 140 to the carrier layer 110 ensures that even if the carrier layer 110 is damaged during the peeling off of the protective layer 140, or if adhesive residue remains on the carrier layer 110 or the protective layer 140 itself, it will not affect the metal foil 130.

[0054] The composite metal foil provided in this invention includes a carrier layer, a release layer, a metal foil, and a protective layer stacked sequentially. The protective layer includes a covering portion and an extension portion. The covering portion covers the metal foil but is not bonded to it. The extension portion extends along at least two opposite sidewalls of the composite metal foil and is bonded to the carrier layer. This design prevents foreign matter from adhering to the metal foil and avoids damage to the metal foil during the peeling of the protective layer. Furthermore, peeling the protective layer also prevents adhesive residue or protective layer residue from remaining on the metal foil, facilitating subsequent lamination. Peeling the protective layer simply requires breaking the extension portion and then removing the protective layer, simplifying the process. Even if the carrier layer is damaged or has adhesive residue or protective layer residue, peeling the protective layer will not affect the metal foil.

[0055] Based on the above embodiments, the extension includes a first part and a second part, the first part being disposed on the sidewall of the composite metal foil, and the second part being bonded to the carrier layer.

[0056] For example, in one embodiment, such as Figure 1 As shown, the extension 142 includes a first portion 1422 and a second portion 1423. The first portion 1422 is disposed on the sidewall of the composite metal foil, and the second portion 1423 extends to the surface of the carrier layer 110 away from the release layer 120 (i.e., the back side of the carrier layer 110). The second portion 1423 is bonded to the back side of the carrier layer 110 by an adhesive portion 1421.

[0057] Figure 3 forFigure 1 A bottom view of a composite metal foil, as shown below. Figure 3 As shown, the extension 142 extends along two opposite sidewalls of the composite metal foil, forming a second portion 1423 disposed in the edge region where two opposite edges of the back surface of the carrier layer 110 are located. The second portion 1423 is bonded to the back surface of the carrier layer 110 by an adhesive portion 1421. The adhesive portion 1421 is configured in the form of a line and / or a dot. In this embodiment, the adhesive portion 1421 is configured in the form of a line and extends along the edge of the back surface of the carrier layer 110.

[0058] It should be noted that the above embodiment describes the present invention by taking the extension portion extending along two opposite sidewalls of the composite metal foil and the second portion formed being disposed in the edge region where two opposite edges of the back side of the carrier layer are located. In other embodiments of the present invention, the extension portion may also extend along three or four sidewalls of the composite metal foil and the second portion formed being disposed in the edge region where three or four edges of the back side of the carrier layer are located. The present invention does not limit this.

[0059] Figure 4 This is a schematic diagram of another composite metal foil structure provided in an embodiment of the present invention. This embodiment provides another way to connect the carrier layer and the protective layer.

[0060] like Figure 4 As shown, the composite metal foil includes a carrier layer 110, a release layer 120, a metal foil 130, and a protective layer 140. The release layer 120 and the metal foil 130 are sequentially stacked on the carrier layer 110. At least two opposite edges of the carrier layer 110 are horizontally spaced from two corresponding edges of the release layer 120, and these at least two opposite edges are located outside the corresponding edges of the release layer 120. That is, the edge region containing at least two opposite edges on the front side of the carrier layer 110 is not covered by the release layer 120. Alternatively, the carrier layer 110, after covering the release layer 120, has at least two opposite empty spaces on its end face near the release layer 120. If the area formed between one edge of the carrier layer 110 and a corresponding edge of the release layer is defined as an empty area, the second part 1423 is disposed in the empty area.

[0061] The protective layer 140 includes a covering portion 141 and an extension portion 142. The covering portion 141 covers the metal foil 130, but the covering portion 141 is not bonded to the metal foil 130.

[0062] The extension 142 extends along two opposing sidewalls of the composite metal foil. The extension 142 includes a first portion 1422 and a second portion 1423. The first portion 1422 is disposed on the sidewall of the composite metal foil, and the second portion 1422 is disposed on the edge region of the carrier layer 110 not covered by the release layer 120. The second portion 1423 is bonded to the edge region of the carrier layer 110 not covered by the release layer 120 via an adhesive portion 1421.

[0063] Figure 5 for Figure 4 A top view of a composite metal foil, as shown below. Figure 5 As shown, the extension 142 extends along two opposing sidewalls of the composite metal foil, forming a second portion 1423 disposed on the edge region of the carrier layer 110 not covered by the release layer 120. The second portion 1423 is bonded to the edge region of the carrier layer 110 not covered by the release layer 120 by an adhesive portion 1421. The adhesive portion 1421 is configured in the form of a line and / or dots. In this embodiment, the adhesive portion 1421 is configured in the form of a line and extends along the edge of the carrier layer 110 not covered by the release layer 120.

[0064] It should be noted that the above embodiment describes the present invention by taking the extension portion extending along two opposite sidewalls of the composite metal foil to form a second part of the edge area on the carrier layer that is not covered by the release layer. In other embodiments of the present invention, the extension portion may also extend along three or four sidewalls of the composite metal foil to form a second part of the edge area on the carrier layer that is not covered by the release layer. The present invention does not limit this.

[0065] In the above embodiments, the protective layer 140 only needs to cover the surface of the metal foil 130 and prevent the adhesion of foreign matter, and is not particularly limited. The protective layer 140 can be a metal foil or an organic film. For example, the protective layer 140 can be an aluminum foil, copper foil, polyimide film, or resin film.

[0066] When the protective layer 140 is an organic film, the protective layer 140 and the carrier layer 110 can be pressed together by hot pressing to form an adhesive portion 1421. When the protective layer 140 is a metal foil, the protective layer 140 and the carrier layer 110 can be connected by ultrasonic welding to form the adhesive portion 1421. The adhesive portion 1421 can be formed by any method that can bond the protective layer 140 and the carrier layer 110 in a way that makes them difficult to peel off; this invention is not limited thereto.

[0067] Based on the above embodiments, the carrier layer 110 can be a carrier copper, a carrier aluminum, or an organic thin film. The metal foil 130 can be a copper foil or an aluminum foil. Specifically, in this embodiment of the invention, the preparation of a composite copper foil is used as an example to illustrate the invention, with the carrier layer 110 being a carrier copper and the metal foil 130 being a copper foil.

[0068] The release layer 120 is made of any one or more materials selected from nickel, silicon, molybdenum, graphite, titanium, and niobium; or, the release layer 120 is made of an organic polymer material. In this art, hot pressing is typically used to bond one side of the composite metal foil to the substrate, as this bonding process requires high temperatures. When the release layer 120 is made of any one or more materials selected from nickel, silicon, molybdenum, graphite, titanium, and niobium, the release layer 120 oxidizes under the high temperature of hot pressing, becoming brittle and thus easier to peel off. When the release layer 120 is made of an organic polymer material, the release layer 120 softens under the high temperature of hot pressing, thus facilitating peeling.

[0069] In composite metal foils, the release layer 120 is usually very thin. During the hot pressing process of composite metal foil and substrate, if the carrier layer 110 and metal foil 130 are made of the same material (e.g., both are copper), the carrier layer 110 and metal foil 130 are prone to interdiffusion under high temperature conditions, which leads to the carrier layer 110 and metal foil 130 bonding together. This makes it difficult to peel the carrier layer 110 and metal foil 130 apart, resulting in more pinholes in the metal foil 130, which is not conducive to the subsequent fabrication of micro-circuits.

[0070] To address this issue, in some embodiments of the present invention, the composite metal foil may further include a barrier layer to block the diffusion path between the carrier layer and the metal foil, thereby preventing the carrier layer and the metal foil from interdiffusion at high temperatures, which would make it difficult to peel the carrier layer and the metal foil apart, thus reducing the number of pinholes in the metal foil.

[0071] Figure 6 This is a schematic diagram of another composite metal foil provided in an embodiment of the present invention. This embodiment is based on... Figure 1 Further improvements made to the illustrated embodiments, as those skilled in the art will understand, are also applicable to the present invention. Figure 4 The embodiments shown are not described in detail here.

[0072] like Figure 6 As shown, in Figure 1 Based on the illustrated embodiment, the composite metal foil may further include a barrier layer 150 disposed between the carrier layer 110 and the release layer 120. The barrier layer 150 is used to block the diffusion path between the carrier layer 110 and the metal foil 130, preventing mutual diffusion between the carrier layer 110 and the metal foil 130 at high temperatures.

[0073] Specifically, the barrier layer 150 may include a metal adhesive layer 151 and a high-temperature resistant layer 152. The metal adhesive layer 151 is formed on the carrier layer 110, the high-temperature resistant layer 152 is formed on the metal adhesive layer 151, and the release layer 120 and the metal foil 130 are sequentially formed on the high-temperature resistant layer 152.

[0074] The metal bonding layer 151 is made of any one or more of copper, zinc, nickel, iron and manganese; or, the metal bonding layer 151 is made of one of copper or zinc and one of nickel, iron and manganese. The structure of the metal bonding layer 151 may include, but is not limited to, the following: (1) the metal bonding layer 151 is a single metal layer composed of metal A, wherein metal A is copper or zinc; (2) the metal bonding layer 151 is a single metal layer composed of metal B, wherein metal B is nickel, iron or manganese; (3) the metal bonding layer 151 is a single-layer alloy structure composed of metal A and metal B, such as a single-layer alloy structure made of copper-nickel alloy; (4) the metal bonding layer 151 includes a multi-layer structure composed of alloy layer and single metal layer; wherein the alloy layer of the metal bonding layer 151 is made of metal A and metal B, and the single metal layer of the metal bonding layer 151 is made of metal A or metal B; for example, an alloy layer made of copper-nickel alloy and a single metal layer made of manganese; (5) the metal bonding layer 151 is a multi-layer structure composed of a single-layer structure of metal A and a single-layer structure of metal B, for example, a multi-layer structure composed of copper metal layer and nickel metal layer. When the metal adhesive layer 151 is a multilayer structure composed of a single-layer structure of metal A and a single-layer structure of metal B, the single-layer structure of metal A is disposed between the carrier layer 110 and the single-layer structure of metal B. Since the adhesion between metal A and the carrier layer is relatively strong, and the adhesion between metal B and the high-temperature resistant layer 152 is also relatively strong, by disposing the single-layer structure of metal A between the carrier layer 110 and the single-layer structure of metal B, the barrier layer 150 is not easily separated from the carrier layer 110. By providing the metal adhesive layer 151, the barrier layer 150 can be reliably connected to the carrier layer 110, thereby preventing peeling between the barrier layer 150 and the carrier layer 110.

[0075] The high-temperature resistant layer 152 is an organic high-temperature resistant layer; or, the high-temperature resistant layer 152 is made of any one or more materials selected from tungsten, chromium, zirconium, titanium, nickel, molybdenum, cobalt, and graphite. Exemplarily, the high-temperature resistant layer 152 is a single-layer alloy structure, a multi-layer structure composed of a single metal layer, or a multi-layer structure composed of an alloy layer and a single metal layer. Specifically, the single-layer alloy structure is a single-layer structure made of an alloy material, such as a single-layer structure made of a tungsten-chromium alloy; the multi-layer structure composed of a single metal layer is a multi-layer structure composed of multiple single-layer structures, each made of a single metal, such as a multi-layer structure composed of a tungsten metal layer and a chromium metal layer; the multi-layer structure composed of an alloy layer and a single metal layer is a multi-layer structure composed of multiple single-layer structures, each made of a single metal or alloy material, such as a multi-layer structure composed of a zirconium metal layer and a tungsten-chromium alloy layer. The high-temperature resistant material diffuses slowly at high temperatures, preventing the diffusion of the high-temperature resistant material itself. Simultaneously, the multi-layer high-temperature resistant layer 152 helps to block the diffusion between the carrier layer 110 and the metal foil 130 at high temperatures.

[0076] This invention also provides a substrate with a carrier. Figure 7 This is a schematic diagram of the structure of a substrate with a carrier provided in an embodiment of the present invention, as shown below. Figure 7 As shown, the substrate with a carrier includes an intermediate body 100 and a flexible substrate 200, with the intermediate body 100 disposed on one side of the flexible substrate 200. The intermediate body 100 is formed by the composite metal foil peel-off protective layer provided in the above embodiment.

[0077] like Figure 7 As shown, the intermediate 100 includes a carrier layer 110, a release layer 120, and a metal foil 130. The release layer 120 and the metal foil 130 are stacked sequentially on one side of the carrier layer 110, and the metal foil 130 is bonded to the flexible substrate 200. Specifically, the intermediate 100 and the flexible substrate 200 can be bonded together by hot pressing.

[0078] For example, the flexible substrate 200 can be made of polyimide (PI), which has good flexibility and insulation properties, making it suitable as a substrate for flexible printed circuit boards. The substrate with a carrier can be formed by bonding the composite metal foil 100 and the flexible substrate 200 together using a hot-pressing process. When it is necessary to prepare a micro-circuit board by an etching process, the substrate with the carrier is peeled off, and the carrier layer 110 is removed to obtain a flexible foil-coated board including the flexible substrate 200 and the metal foil 130. The flexible foil-coated board is then etched to obtain a flexible micro-circuit board.

[0079] For example, the carrier layer 110 can be a carrier copper, a carrier aluminum, or an organic thin film. The metal foil 130 can be a copper foil or an aluminum foil. Specifically, in this embodiment of the invention, the preparation of a composite copper foil using a carrier layer 110 as a carrier copper and a metal foil 130 as a copper foil is used as an example to illustrate the invention.

[0080] The release layer 120 is made of any one or more materials selected from nickel, silicon, molybdenum, graphite, titanium, and niobium; or, the release layer 120 is made of an organic polymer material. In this art, hot pressing is typically used to bond one side of the composite metal foil to the substrate, as this bonding process requires high temperatures. When the release layer 120 is made of any one or more materials selected from nickel, silicon, molybdenum, graphite, titanium, and niobium, the release layer 120 oxidizes under the high temperature of hot pressing, becoming brittle and thus easier to peel off. When the release layer 120 is made of an organic polymer material, the release layer 120 softens under the high temperature of hot pressing, thus facilitating peeling.

[0081] Figure 8 This is a schematic diagram of another substrate with a carrier provided in an embodiment of the present invention, as shown below. Figure 8 As shown, based on the above embodiments, the intermediate 100 may further include a barrier layer 150, which is disposed between the carrier layer 110 and the release layer 120. The barrier layer 150 is used to block the diffusion path between the carrier layer 110 and the metal foil 130, preventing the carrier layer 110 and the metal foil 130 from interdiffusion at high temperatures.

[0082] Specifically, the barrier layer 150 may include a metal adhesive layer 151 and a high-temperature resistant layer 152. The metal adhesive layer 151 is formed on the carrier layer 110, the high-temperature resistant layer 152 is formed on the metal adhesive layer 151, and the release layer 120 and the metal foil 130 are sequentially formed on the high-temperature resistant layer 152.

[0083] By providing a metal bonding layer 151, the barrier layer 150 can be reliably connected to the carrier layer 110, thereby preventing peeling between the barrier layer 150 and the carrier layer 110. The high-temperature resistant material diffuses slowly at high temperatures, preventing the diffusion of the high-temperature resistant material itself. Simultaneously, the high-temperature resistant layer 152 helps to block the diffusion between the carrier layer 110 and the metal foil 130 at high temperatures. Specifically, the materials and structures of the metal bonding layer 151 and the high-temperature resistant layer 152 have been described in detail in the foregoing embodiments and will not be repeated here.

[0084] The substrate with a carrier provided in this invention includes an intermediate body and a flexible substrate, with the intermediate body disposed on one side of the flexible substrate. The intermediate body is obtained by a composite metal foil release protective layer. The composite metal foil includes a carrier layer, a release layer, a metal foil, and a protective layer stacked sequentially. The protective layer includes a cover portion and an extension portion. The cover portion covers the metal foil but is not bonded to the metal foil. The extension portion extends along at least two opposite sidewalls of the composite metal foil and is bonded to the carrier layer. On the one hand, this prevents foreign matter from adhering to the metal foil; on the other hand, it prevents damage to the metal foil during the release of the protective layer. Furthermore, during the release of the protective layer, it also prevents adhesive residue or protective layer residue from being left on the metal foil, facilitating subsequent lamination. The process is simple: simply break the extension portion and then peel off the protective layer. Even if the carrier layer is damaged or adhesive residue or protective layer residue remains on the carrier layer during the release of the protective layer, it will not affect the metal foil.

[0085] This invention also provides a method for preparing a flexible foil-coated board. Figure 9 A flowchart of a method for preparing a flexible foil-coated board provided for the implementation of this invention is shown below. Figure 9 As shown, the method includes:

[0086] S301 provides flexible substrates and composite metal foils.

[0087] The composite metal foil can be referenced in this invention. Figures 1-7 The composite metal foil includes a carrier layer 110, a release layer 120, a metal foil 130, and a protective layer 140.

[0088] The release layer 120 is formed on one side of the carrier layer 110, and the metal foil 130 is formed on the side of the release layer 120 away from the carrier layer 110.

[0089] A protective layer 140 covers the metal foil 130 to prevent foreign matter from adhering to the metal foil 130. The protective layer 140 includes a covering portion 141 and an extension portion 142. The covering portion 141 covers the metal foil 130 but is not bonded to the metal foil 130.

[0090] The extension 142 includes a first portion 1422 and a second portion 1423. The first portion 1422 is disposed on the sidewall of the composite metal foil, and the second portion 1423 is bonded to the carrier layer 110. For example, the second portion 1423 can be bonded to the carrier layer 110 through the adhesive portion 1421.

[0091] The connection between the protective layer 140 and the carrier layer 110 has been described in detail in the foregoing embodiments, and will not be repeated here.

[0092] For example, the carrier layer 110 can be a carrier copper, a carrier aluminum, or an organic thin film. The metal foil 130 can be a copper foil or an aluminum foil. Specifically, in this embodiment of the invention, the preparation of a composite copper foil using a carrier layer 110 as a carrier copper and a metal foil 130 as a copper foil is used as an example to illustrate the invention.

[0093] The release layer 120 is made of any one or more materials selected from nickel, silicon, molybdenum, graphite, titanium, and niobium; or, the release layer 120 is made of an organic polymer material.

[0094] The protective layer 140 can be a metal foil or an organic film. For example, the protective layer 140 can be an aluminum foil, copper foil, polyimide film, or resin film.

[0095] In some embodiments of the present invention, such as Figure 6 As shown, the composite metal foil may further include a barrier layer 150, which is disposed between the carrier layer 110 and the release layer 120. Specifically, the barrier layer 150 may include a metal bonding layer 151 and a high-temperature resistant layer 152. The metal bonding layer 151 is formed on the carrier layer 110, the high-temperature resistant layer 152 is formed on the metal bonding layer 151, and the release layer 120 and the metal foil 130 are sequentially formed on the high-temperature resistant layer 152.

[0096] By providing a metal bonding layer 151, the barrier layer 150 can be reliably connected to the carrier layer 110, thereby preventing peeling between the barrier layer 150 and the carrier layer 110. The high-temperature resistant material diffuses slowly at high temperatures, preventing the diffusion of the high-temperature resistant material itself. Simultaneously, the high-temperature resistant layer 152 helps to block the diffusion between the carrier layer 110 and the metal foil 130 at high temperatures. Specifically, the materials and structures of the metal bonding layer 151 and the high-temperature resistant layer 152 have been described in detail in the foregoing embodiments and will not be repeated here.

[0097] For example, the flexible substrate 200 may be made of polyimide (PI), which has good flexibility and insulation properties and is suitable for use as a substrate for flexible printed circuit boards.

[0098] S302. Remove the protective layer to obtain the intermediate.

[0099] For example, the adhesive portion 1421 is destroyed by mechanical breaking, thereby removing the protective layer 140 and exposing the metal foil 130, thereby obtaining an intermediate including the carrier layer 110, the release layer 120 and the metal foil 130.

[0100] S303, The metal foil of the intermediate is bonded to the flexible substrate.

[0101] For example, the intermediate 100 and the flexible substrate 200 are formed by hot pressing. Under high temperature and pressure, the metal foil 130 is bonded to the flexible substrate 200 to obtain a substrate with a carrier. The structure of the substrate with the carrier is as follows: Figure 8 As shown.

[0102] S304. Peel off the carrier layer to separate the carrier layer from the metal foil, thereby obtaining a flexible foil-coated board.

[0103] Figure 10 This is a schematic diagram illustrating the separation of the carrier layer from the metal foil in an embodiment of the present invention. Figure 11 This is a schematic diagram of a flexible foil-coated board provided in an embodiment of the present invention. Exemplarily, when a micro-circuit board needs to be fabricated using an etching process, the substrate with a carrier is peeled off, and the carrier layer 110 is removed to obtain a flexible foil-coated board comprising a flexible substrate 200 and a metal foil 130. Subsequent etching of this flexible foil-coated board yields the flexible micro-circuit board.

[0104] It should be noted that, in this embodiment, as Figure 10 As shown, the present invention will be described using the interface between the release layer 120 and the metal foil 130 as an example of the separation surface after peeling. In other embodiments of the present invention, the separation surface after peeling may also be the interface between the carrier layer 110 and the release layer 120, or peeled from the middle of the release layer 120. When the separation surface after peeling is the interface between the carrier layer 110 and the release layer 120, or peeled from the middle of the release layer 120, the surface of the metal foil 130 of the resulting flexible coated board will retain all or part of the release layer 120, which can protect the metal foil 130, prevent the surface of the metal foil 130 from being scratched, and prevent the surface of the metal foil 130 from being oxidized, thus avoiding the cost increase caused by the additional step of removing the oxide layer in the subsequent etching process.

[0105] This invention also provides a flexible foil-coated board, see reference. Figure 11 The flexible foil-coated board includes a flexible substrate 200 and a metal foil 130, with the metal foil 130 covering the flexible substrate 200.

[0106] Specifically, the flexible substrate 200 can be made of polyimide (PI), which has good flexibility and insulation properties, making it suitable as a substrate for flexible printed circuit boards. The metal foil 130 can be copper foil or aluminum foil.

[0107] The flexible foil-coated board can be prepared by the method for preparing the flexible foil-coated board provided in the above embodiments of the present invention, the method comprising:

[0108] S301 provides flexible substrates and composite metal foils.

[0109] S302. Remove the protective layer to obtain an intermediate, which includes a carrier layer, a release layer, and a metal foil.

[0110] S303, The metal foil of the intermediate is bonded to the flexible substrate.

[0111] S304. Peel off the carrier layer to separate the carrier layer from the metal foil, thereby obtaining a flexible foil-coated board.

[0112] Specifically, the structure of the composite metal foil and the preparation method of the flexible cladding have been described in detail in the foregoing embodiments, and will not be repeated here.

[0113] In the description herein, it should be understood that the terms "upper," "lower," "right," etc., refer to the orientation or positional relationship shown in the accompanying drawings, and are used only for ease of description and simplification of operation, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. Furthermore, the terms "first" and "second" are used merely for descriptive distinction and have no special meaning.

[0114] In the description of this specification, references to terms such as "an embodiment," "example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example.

[0115] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style of the specification is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

[0116] The technical principles of the present invention have been described above with reference to specific embodiments. These descriptions are merely for explaining the principles of the invention and should not be construed as limiting the scope of protection of the invention in any way. Based on this explanation, those skilled in the art can readily conceive of other specific embodiments of the invention without inventive effort, and these embodiments will all fall within the scope of protection of the present invention.

Claims

1. A composite metal foil, characterized in that, It includes a carrier layer, a release layer, a metal foil, and a protective layer; The peeling layer is formed on one side of the carrier layer; The metal foil is formed on the side of the release layer away from the carrier layer; The protective layer includes a covering portion and an extension portion; The covering portion covers the metal foil, but the covering portion is not adhered to the metal foil; The extension extends along at least two opposite sidewalls of the composite metal foil, and the extension is bonded to the carrier layer; The composite metal foil also includes a barrier layer disposed between the carrier layer and the release layer. The barrier layer includes a metal bonding layer and a high-temperature resistant layer, wherein the metal bonding layer is formed on the carrier layer and the high-temperature resistant layer is formed on the metal bonding layer. The extension includes a first part and a second part, the first part being disposed on the sidewall of the composite metal foil, and the second part being bonded to the carrier layer; the second part being disposed on the surface of the carrier layer away from the release layer.

2. The composite metal foil according to claim 1, characterized in that, The extension is bonded to the carrier layer via an adhesive portion, which is configured as a line and / or a dot.

3. The composite metal foil according to claim 1, characterized in that, The protective layer is a metal foil or an organic film.

4. The composite metal foil according to claim 1, characterized in that, The high-temperature resistant layer is an organic high-temperature resistant layer; or, the high-temperature resistant layer is made of any one or more materials selected from tungsten, chromium, zirconium, titanium, nickel, molybdenum, cobalt and graphite.

5. The composite metal foil according to claim 1, characterized in that, The release layer is made of any one or more materials selected from nickel, silicon, molybdenum, graphite, titanium, and niobium; or, the release layer is made of an organic polymer material.

6. The composite metal foil according to claim 1, characterized in that, The metal foil is copper foil or aluminum foil; the carrier layer is carrier copper, carrier aluminum or organic thin film.

7. A substrate with a carrier, characterized in that, It includes a flexible substrate and an intermediate, wherein the intermediate is obtained by removing the protective layer from the composite metal foil of any one of claims 1-6, and the intermediate is disposed on one side of the flexible substrate; The intermediate includes a carrier layer, a release layer, and a metal foil; The peeling layer is formed on one side of the carrier layer; The metal foil is formed on the side of the release layer away from the carrier layer; The metal foil is bonded to the flexible substrate; The intermediate also includes a barrier layer disposed between the carrier layer and the release layer. The barrier layer includes a metal bonding layer and a high-temperature resistant layer, wherein the metal bonding layer is formed on the carrier layer and the high-temperature resistant layer is formed on the metal bonding layer.

8. A method for preparing a flexible foil-coated board, characterized in that, include: A flexible substrate and a composite metal foil are provided; the composite metal foil includes a carrier layer, a release layer, a metal foil, and a protective layer; the release layer is formed on one side of the carrier layer; the metal foil is formed on the side of the release layer away from the carrier layer; the protective layer includes a cover portion and an extension portion; the cover portion covers the metal foil and is not bonded to the metal foil; the extension portion extends along at least two opposing sidewalls of the composite metal foil and is bonded to the carrier layer; the extension portion includes a first portion and a second portion, the first portion being disposed on a sidewall of the composite metal foil, and the second portion being bonded to the carrier layer; the second portion being disposed on the surface of the carrier layer away from the release layer. The protective layer is removed to obtain an intermediate, which includes a carrier layer, a release layer and a metal foil. The intermediate also includes a barrier layer disposed between the carrier layer and the release layer. The barrier layer includes a metal bonding layer and a high-temperature resistant layer, wherein the metal bonding layer is formed on the carrier layer and the high-temperature resistant layer is formed on the metal bonding layer. The metal foil of the intermediate is bonded to the flexible substrate; Peel off the carrier layer to separate it from the metal foil, thus obtaining a flexible foil-coated board.

9. A flexible foil-coated board, characterized in that, The flexible foil-coated board is prepared by the method described in claim 8, comprising: a flexible substrate and a metal foil coated on the flexible substrate.

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