Metal laminated substrate with carrier layer, method for manufacturing metal laminated substrate, metal laminated substrate and method for manufacturing metal laminated substrate, and printed wiring board

Abstract

The present invention aims to provide a metal layered substrate with a carrier layer which maintains low adhesion between the carrier layer and an extremely thin metal layer while ensuring high adhesion of the extremely thin metal layer and a low dielectric film. In a metal layered substrate with a carrier layer 1A, an extremely thin metal layered foil 10 composed of three layers including a carrier layer 11, a separation layer 12, and an extremely thin metal layer 13 is layered on at least one side of a low dielectric film 20, characterized in that the bonding strength of the extremely thin metal layer 13 and the low dielectric film 20 is greater than the separation strength of the carrier layer 11 and the extremely thin metal layer 13.

Description

Technical Field

[0001] This invention relates to a metal laminate substrate with a carrier layer and a method for manufacturing the same, as well as a printed circuit board. Background Technology

[0002] Currently, metal foils with a carrier layer are known as components for forming fine wiring (fine pitch). This metal foil with a carrier layer is a laminate of a peelable carrier layer and an extremely thin metal layer, which is laminated with a rigid substrate made of glass epoxy resin, etc., to obtain a metal laminate substrate (metal-clad laminate) with a carrier layer. Alternatively, components with a flexible polymer film laminated on top of the aforementioned rigid substrate are also known, and are used as metal laminate substrates for forming flexible circuit boards. In particular, polymer films using low-dielectric-constant polymers such as polyimide are useful in 5G mobile communication systems for high-frequency circuits.

[0003] Patent Document 1 discloses a copper foil with a carrier having an intermediate layer and an extremely thin copper layer sequentially on one or both sides of the carrier. The extremely thin copper layer is formed by forming a primary particle layer containing copper on the surface of the copper foil, followed by forming a secondary particle layer containing a ternary alloy composed of copper, cobalt, and nickel on the primary particle layer. Furthermore, when the color difference of the roughened surface is measured using a colorimeter as described in JIS Z8730, the color difference Δa* value with white is 4.0 or less, and the color difference Δb* value is 3.5 or less. Additionally, Patent Document 1 also describes a copper-clad laminate with a carrier, in which a rigid substrate such as a paper-based phenolic resin or a polymer film such as a liquid crystal polymer (LCP) is laminated with the aforementioned copper foil with a carrier.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2014-224318 Summary of the Invention

[0007] The problem that the invention aims to solve

[0008] In the aforementioned (Patent Document 1), the bonding of a copper foil with a carrier and a rigid substrate is performed as follows: a substrate such as glass cloth is impregnated with resin, a prepreg is prepared to cure the resin to a semi-cured state, and the copper foil is laminated on the prepreg and heated and pressed. Alternatively, when a polymer film is used instead of a rigid substrate, the copper foil is also bonded by laminating and bonding (thermo-pressing) a substrate such as a liquid crystal polymer under high temperature and high pressure.

[0009] However, especially when hot-pressing low-dielectric films such as liquid crystal polymers or low-dielectric-constant polyimides suitable for high-frequency circuit applications onto metal foils with a carrier, the hot-pressing temperature needs to be set to 280°C or 300°C or higher, taking into account various characteristics such as the melting point of the low-dielectric film. Within this temperature range, problems arise such as the release layer between the carrier layer and the extremely thin metal layer deteriorating, impairing the release properties of the carrier. On the other hand, there is a problem that when the hot-pressing temperature is lowered to maintain release properties, the adhesion between the extremely thin metal layer and the low-dielectric film decreases. Therefore, it is currently difficult to simultaneously maintain the release properties (low adhesion) between the carrier and the extremely thin metal layer and ensure high adhesion between the extremely thin metal layer and the low-dielectric film.

[0010] Therefore, an object of the present invention is to provide a metal laminate substrate with a carrier layer that maintains low adhesion between the carrier layer and the ultrathin metal layer, and ensures high adhesion between the ultrathin metal layer and the low-dielectric thin film, and a method thereof for manufacturing the same. Another object is to provide a metal laminate substrate having a low-dielectric thin film and an ultrathin metal layer laminated together, and a method thereof for manufacturing the same. Yet another object is to provide a printed circuit board obtained from said metal laminate substrate and suitable for use in high-frequency circuits.

[0011] Technical solutions for solving the problem

[0012] The inventors conducted in-depth research and discovered that by employing a specific bonding method and controlling the bonding strength between the ultrathin metal layer and the low-dielectric film, as well as the peel strength between the carrier layer and the ultrathin metal layer, when stacking a low-dielectric thin film and a metal foil containing a carrier layer, a release layer, and an ultrathin metal layer, the aforementioned problems can be solved, and the invention was completed. In other words, the purpose of this invention is as follows.

[0013] (1) A metal laminate substrate with a carrier layer, wherein a metal foil with a carrier layer, comprising at least three layers including a carrier layer, a release layer, and an extremely thin metal layer, is laminated on at least one side of a low-dielectric thin film, wherein,

[0014] The bonding strength between the ultrathin metal layer and the low-dielectric film is greater than the peel strength between the carrier layer and the ultrathin metal layer.

[0015] (2) The metal laminate substrate with a carrier layer as described in (1) wherein there is one or more metal-containing intermediate layers between the low dielectric thin film and the ultrathin metal layer.

[0016] (3) The metal laminate substrate with a carrier layer as described in (2), wherein the intermediate layer contains a metal or alloy thereof selected from the group consisting of copper, iron, nickel, zinc, chromium, cobalt, titanium, tin, platinum, silver and gold.

[0017] (4) The metal laminate substrate with a carrier layer as described in any one of (1) to (3), wherein the low dielectric film is a film of a low dielectric polymer selected from the group consisting of liquid crystal polymer, ethylene fluoride, polyamide and low dielectric constant polyimide.

[0018] (5) The metal laminate substrate with a carrier layer as described in any one of (1) to (4), wherein the peel strength of the carrier layer and the ultrathin metal layer is 0.15 N / cm or more and 0.5 N / cm or less.

[0019] (6) The metal laminate substrate with a carrier layer as described in any one of (1) to (5), wherein the bonding strength between the ultrathin metal layer and the low dielectric film is 2.0 N / cm or more.

[0020] (7) The metal laminate substrate with a carrier layer as described in any one of (1) to (6), wherein the release layer is an organic release layer or an inorganic release layer.

[0021] (8) The metal laminate substrate with a carrier layer as described in any one of (1) to (7), wherein the thickness of the ultrathin metal layer is 0.5 μm or more and 10 μm or less.

[0022] (9) A method for manufacturing a metal laminate substrate with a carrier layer, comprising manufacturing the metal laminate substrate with a carrier layer described in (2), wherein:

[0023] The process of preparing a low-dielectric thin film and a metal foil with a carrier layer consisting of at least three layers including a carrier layer, a release layer and an extremely thin metal layer;

[0024] The process of activating at least one side of the low-dielectric thin film by sputtering etching, and then sputtering a metal intermediate layer on the surface.

[0025] The process of activating the surface of the intermediate layer by sputter etching;

[0026] The process of activating the surface of the extremely thin metal layer by sputtering etching;

[0027] A process of rolling the activated surfaces together with a reduction rate of 0 to 30%.

[0028] (10) The method for manufacturing a metal laminate substrate with a carrier layer as described in (9), wherein the low dielectric film is a film of a low dielectric polymer selected from the group consisting of liquid crystal polymer, ethylene fluoride, polyamide and low dielectric constant polyimide.

[0029] (11) The method for manufacturing a metal laminate substrate with a carrier layer as described in (9) or (10), wherein after rolling bonding, heat treatment is performed at 160°C or higher and 300°C or lower.

[0030] (12) A metal laminate substrate, wherein an extremely thin metal layer is laminated on at least one side of a low dielectric film via an intermediate layer containing metal, wherein the bonding strength between the low dielectric film and the extremely thin metal layer is 2.0 N / cm or more.

[0031] (13) The metal laminate substrate described in (12), wherein the intermediate layer contains any metal or alloy thereof selected from the group consisting of copper, iron, nickel, zinc, chromium, cobalt, titanium, tin, platinum, silver and gold.

[0032] (14) The metal laminate substrate described in (12) or (13) wherein a coarsening particle layer containing any metal or alloy selected from the group consisting of Cu, Co and Ni, and / or a rust-preventive layer containing any metal or alloy selected from the group consisting of Cr, Ni and Zn is laminated on the surface of the intermediate layer side of the ultrathin metal layer.

[0033] (15) The metal laminate substrate described in any one of (12) to (14), wherein the thickness of the ultrathin metal layer is 0.5 μm or more and 10 μm or less.

[0034] (16) A method for manufacturing a metal laminate substrate, comprising manufacturing a metal laminate substrate on at least one side of a low-dielectric thin film by laminating an extremely thin metal layer through an intermediate layer containing metal, wherein,

[0035] The process includes peeling the carrier layer from the metal laminate substrate with the carrier layer described in (2).

[0036] (17) A printed circuit board formed by forming a circuit through an intermediate layer and an extremely thin metal layer of a metal laminate substrate described in any one of (12) to (15).

[0037] This specification contains the disclosures of Japanese Patent Application Nos. 2019-154167 and 2020-013319, which form the basis of the priority of this application.

[0038] Invention Effects

[0039] According to the present invention, in a metal laminate substrate with a carrier layer, it is possible to maintain both low adhesion between the carrier layer and the ultrathin metal layer and high adhesion between the ultrathin metal layer and the low-dielectric thin film. Furthermore, a metal laminate substrate having a low-dielectric thin film and an ultrathin metal layer stacked together can be obtained. This metal laminate substrate is suitable for high-frequency circuits. Attached Figure Description

[0040] Figure 1 This is a cross-sectional view of a metal laminate substrate with a carrier layer according to the first embodiment of the present invention.

[0041] Figure 2 This is a cross-sectional view of a metal laminate substrate with a carrier layer according to the second embodiment of the present invention.

[0042] Figure 3A This is a diagram illustrating the manufacturing process of a metal laminate substrate with a carrier layer according to the second embodiment of the present invention.

[0043] Figure 3B This is a diagram illustrating the manufacturing process of a metal laminate substrate with a carrier layer according to the second embodiment of the present invention.

[0044] Figure 4 This is a diagram illustrating the manufacturing process of a metal laminated substrate according to an embodiment of the present invention.

[0045] Figure 5 These are scanning electron microscope (SEM) images of each peeling surface of the metal laminate substrate with carrier layer in Example 5 when peeling off the extremely thin copper layer and the low dielectric film. Detailed Implementation

[0046] The present invention will now be described in detail.

[0047] Figure 1 The figure shows a cross-section of the metal laminate substrate with a carrier layer according to the first embodiment of the present invention. Figure 1 The metal laminate substrate 1A with a carrier layer shown is approximately constructed by sequentially stacking a metal foil 10 with a carrier layer consisting of a carrier layer 11, a release layer 12 and an ultrathin metal layer 13, and a low dielectric film 20.

[0048] In addition, although Figure 1Not explicitly described, but a roughening particle layer or a rust-preventive layer, or a silane coupling agent-based treatment layer, may also be deposited on the surface of the low-dielectric film 20 side of the extremely thin metal layer 13. These layers can be formed by stacking any type of layer or multiple layers. The roughening particle layer may contain, for example, any metal or alloy thereof selected from the group consisting of Cu, Co, and Ni. Specifically, examples include cobalt-nickel alloy plating layers and copper-cobalt-nickel alloy plating layers. Furthermore, the rust-preventive layer may contain, for example, any metal or alloy thereof selected from the group consisting of Cr, Ni, and Zn. Specifically, examples include chromium oxide film treatment, a mixture film treatment of chromium oxide and zinc / zinc oxide, and Ni plating layers. Additionally, examples of silane coupling agents include, but are not limited to, olefinic silanes, epoxy silanes, acrylic silanes, amino silanes, and mercapto silanes. The silane coupling agent can be applied by spraying, coating, dipping, or other suitable methods.

[0049] The carrier layer 11 is sheet-like and functions as a support material or protective layer to prevent wrinkles or bends in the metal laminate substrate 1A with the carrier layer, thus preventing damage to the extremely thin metal layer 13. Examples of carrier layers 11 include foils or plates made of copper, aluminum, nickel, or their alloys (stainless steel, brass, etc.), or resins with metal coated on their surfaces. Copper foil is preferred.

[0050] The thickness of the carrier layer 11 is not particularly limited and can be appropriately set according to desired characteristics such as flexibility. Specifically, it is preferably set to a thickness of 10 μm or more and 100 μm or less. If the thickness is too thin, the operability of the metal foil 10 with the carrier layer may be impaired, which is not preferred. That is, there is a possibility of deformation during processing, resulting in wrinkles or cracks in the extremely thin metal layer 13. In addition, if the carrier layer 11 is too thick, it will have excessive rigidity as a support material, which may make it difficult to peel off from the extremely thin metal layer 13, which is also not preferred. Furthermore, the cost of producing the metal foil 10 with the carrier layer will also increase.

[0051] The release layer 12 also functions to reduce the peel strength of the carrier layer 11 and to suppress interdiffusion that may occur between the carrier layer 11 and the extremely thin metal layer 13 when heated during bonding of the metal foil 10 with the carrier layer to the low-dielectric film 20. The release layer 12 can be either an organic or inorganic release layer. Examples of components used in organic release layers include nitrogen-containing organic compounds, sulfur-containing organic compounds, and carboxylic acids. Examples of nitrogen-containing organic compounds include triazole compounds and imidazole compounds. Examples of triazole compounds include 1,2,3-benzotriazole, carboxybenzotriazole, N',N'-bis(benzotriazolemethyl)urea, 1H-1,2,4-triazole, and 3-amino-1H-1,2,4-triazole. Examples of sulfur-containing organic compounds include mercaptobenzothiazole, thiocyanuric acid, and 2-benzimidazole thiol. Examples of carboxylic acids include monocarboxylic acids and dicarboxylic acids. In addition, examples of components used for inorganic release layers include Ni, Mo, Co, Cr, Fe, Ti, W, P, Zn, and chromate-treated films. Furthermore, the release layer 12 can be formed by contacting a solution containing the components of the release layer 12 with the surface of the carrier layer 11, thereby fixing the release layer components onto the surface of the carrier layer 11. When contacting the carrier layer 11 with the solution containing the components of the release layer 12, this contact can be performed by immersion in the solution containing the release layer components, spraying the solution containing the release layer components, or allowing the solution to flow down, followed by drying and fixation. Alternatively, a vapor-phase method such as evaporation or sputtering can be used to form the components of the release layer 12.

[0052] The thickness of the release layer 12 is typically 1 nm or more and 1 μm or less, preferably 5 nm or more and 500 nm or less, but is not limited thereto. If the thickness of the release layer 12 is too thin, there is a problem that it cannot be sufficiently separated from the ultrathin metal layer 13, resulting in poor peeling. On the other hand, if the thickness is too large, peeling is possible, but the manufacturing cost increases. Therefore, an appropriate setting is made considering both factors.

[0053] The metal constituting the ultrathin metal layer 13 can be appropriately selected according to the application and characteristics of the metal laminate substrate 1A with the carrier layer. Specifically, examples include copper, iron, nickel, zinc, tin, chromium, gold, silver, platinum, cobalt, titanium, and alloys based on any of them. A layer of copper or a copper alloy is particularly preferred. By rolling and bonding these metals with the low-dielectric thin film 20, for example, a flexible substrate for forming microcircuits can be obtained.

[0054] The thickness of the ultrathin metal layer 13 is 0.5 μm or more and 10 μm or less. Preferably, it is 1 μm or more and 7 μm or less. Here, the thickness of the ultrathin metal layer 13 refers to the average value obtained by measuring the thickness of the ultrathin metal layer 13 at any 10 points in an optical microscope photograph of a cross-section of the metal laminate substrate 1A with the carrier layer.

[0055] There is no particular limitation on the manufacturing method of this ultra-thin metal layer 13. It can be formed on the release layer 12 by wet film formation methods such as electroless electroplating and electroplating, dry film formation methods such as sputtering and chemical vapor deposition, or a combination thereof.

[0056] In this embodiment, when comparing the bonding strength between the ultrathin metal layer 13 and the low-dielectric film 20, and the peel strength between the carrier layer 11 and the ultrathin metal layer 13, the bonding strength between the ultrathin metal layer 13 and the low-dielectric film 20 is greater. Therefore, when peeling the carrier layer 11 from the ultrathin metal layer 13, it can be peeled off without wrinkling or cracking on the ultrathin metal layer 13. However, if the bonding strength values ​​between the ultrathin metal layer 13 and the low-dielectric film 20, and the peel strength values ​​between the carrier layer 11 and the ultrathin metal layer 13, are too close, it may be difficult to peel the carrier layer 11 without affecting the interface between the ultrathin metal layer 13 and the low-dielectric film 20. Therefore, the difference between the bonding strength between the ultrathin metal layer 13 and the low-dielectric film 20 and the peel strength between the carrier layer 11 and the ultrathin metal layer 13 is preferably 0.25 N / cm or more. More preferably, it is 0.5 N / cm or more, and most preferably 1.5 N / cm or more. As for the specific values ​​of the bonding strength between the ultrathin metal layer 13 and the low-dielectric film 20, and the peel strength between the carrier layer 11 and the ultrathin metal layer 13, the bonding strength between the ultrathin metal layer 13 and the low-dielectric film 20 is preferably 2.0 N / cm or more. Furthermore, the peel strength between the carrier layer 11 and the ultrathin metal layer 13 only needs to be greater than 0, preferably 0.5 N / cm or less. However, in the region of approximately 0.05 N / cm, due to the rigidity of the peeling materials (carrier layer 11, ultrathin metal layer 13, low-dielectric film 20, other anti-rust layers, etc.), it is sometimes impossible to measure the accurate peel strength. The peel strength between the carrier layer 11 and the ultrathin metal layer 13 is preferably in the range of 0.15 N / cm or more and 0.5 N / cm or less. In addition, to determine the above-mentioned bonding strength values, a test piece with a width of 1 cm is first prepared using a metal laminate substrate 1A with a carrier layer. Then, after removing the carrier layer 11, electroplating (e.g., copper plating if the thin metal layer 13 is copper) is performed on the surface of the ultrathin metal layer 13 to form a metal layer (including the ultrathin metal layer 13) with a thickness of about 10 to 20 μm on the surface of the low-dielectric film 20. Then, after partially peeling the metal layer and the low-dielectric film 20, the low-dielectric film 20 is fixed to the support, and the metal layer with a thickness of about 10 to 20 μm is stretched relative to the low-dielectric film 20 in a 90° direction. The force required for peeling at this time is used as the bonding strength (unit: N / cm). Furthermore, to measure the peel strength, a test piece with a width of 1 cm is first prepared using a metal laminate substrate 1A with a carrier layer. After partially peeling the carrier layer 11, the low-dielectric film 20 containing the ultrathin metal layer 13 is fixed to the support, and the carrier layer 11 is stretched relative to the low-dielectric film 20 containing the ultrathin metal layer 13 in a 90° direction. The force required for peeling at this point is called the peel strength (unit: N / cm).

[0057] In this specification, when "bonding strength between the ultrathin metal layer and the low-dielectric film" is mentioned, it refers not only to the bonding strength when peeled off at the interface between the ultrathin metal layer and the low-dielectric film, but also to the bonding strength when peeled off due to internal damage to the ultrathin metal layer and the low-dielectric film. Furthermore, when a roughening particle layer, rust-preventive layer, or silane coupling agent treatment layer (collectively referred to as "treatment layer") is laminated on the surface of the low-dielectric film side of the ultrathin metal layer, it refers to the bonding strength when peeled off at the interface between the ultrathin metal layer and the treatment layer, the bonding strength when peeled off at the interface between the treatment layer and the low-dielectric film, and the bonding strength when peeled off due to internal damage to the treatment layer. Additionally, the metal laminate substrate with a carrier layer described later in the second embodiment (…) Figure 2 In the case where there is a metal-containing intermediate layer 30 between the low-dielectric thin film 20 and the ultra-thin metal layer 13, "bonding strength between the ultra-thin metal layer and the low-dielectric thin film" also refers to any one of the following: bonding strength when peeled due to internal damage to the ultra-thin metal layer, bonding strength when peeled at the interface between the ultra-thin metal layer (in the case of a processing layer) and the intermediate layer, bonding strength when peeled at the interface between the intermediate layer and the low-dielectric thin film, bonding strength when peeled due to internal damage to the intermediate layer, and bonding strength when peeled due to internal damage to the low-dielectric thin film.

[0058] A low-dielectric thin film 20 is stacked on an extremely thin metal layer 13. As the material for the low-dielectric thin film 20, any low-dielectric polymer material suitable for use as a flexible substrate can be applied; for example, a material with a relative permittivity ε. r The material has a dielectric constant of 3.3 or less and a dielectric loss tangent (tanδ) of 0.006 or less, but is not limited to this. Specifically, materials such as liquid crystal polymers, fluorinated polyethylene (fluorinated resins such as polytetrafluoroethylene), polyamides, isocyanate compounds, polyamide-imides, polyimides, low dielectric constant polyimides, polyethylene terephthalate, and polyether-imides can be appropriately selected and used. Liquid crystal polymers, fluorinated polyethylene, polyamides, or low dielectric constant polyimides are preferred. The low dielectric film 20 is a single-layer film or a multilayer laminate. In the case of multiple layers, any one or more layers in the multilayer can be made of the aforementioned low dielectric polymer material. Layers other than those made of low dielectric polymer materials can be made of various currently known materials such as epoxy resins. Furthermore, liquid crystal polymers refer to aromatic polyester resins with a basic structure such as p-hydroxybenzoic acid that exhibit liquid crystal properties in the molten state.

[0059] The thickness of the low-dielectric thin film 20 can be appropriately set according to the application of the metal laminate substrate. For example, in the case of using it as a flexible printed circuit board, the thickness is preferably 10 μm or more and 150 μm or less, more preferably 10 μm or more and 120 μm or less. Furthermore, the thickness of the low-dielectric thin film 20 before bonding can be measured by a micrometer or the like, referring to the average thickness measured at 10 randomly selected points on the surface of the low-dielectric thin film to be applied. Additionally, for the low-dielectric thin film used, it is preferable that the deviation of the measured values ​​at the 10 points from the average value is within 10% of all measured values.

[0060] Next, the second embodiment of the present invention will be described. Figure 2 The image shows a cross-section of the metal laminate substrate with a carrier layer according to the second embodiment of the present invention. In this embodiment, as shown... Figure 2 As shown, a metal-containing intermediate layer 30 is provided between the ultrathin metal layer 13 and the low-dielectric thin film 20. This intermediate layer 30 can be a single layer or can be stacked in two or more layers. Examples of metal-containing intermediate layers 30 include metal layers disposed on the low-dielectric thin film 20 formed by vapor deposition, electroless electroplating, or sputtering.

[0061] In addition, although Figure 2 Not described herein, but similar to the metal laminate substrate with a carrier layer in the first embodiment, a roughening particle layer, a rust-preventive layer, a silane coupling agent layer, etc., may also be laminated on the surface of the intermediate layer 30 side of the ultrathin metal layer 13. These layers can be of any type or multiple layers. The roughening particle layer may contain, for example, any metal or alloy thereof selected from the group consisting of Cu, Co, and Ni, but is not limited thereto. Similarly, the rust-preventive layer may contain, for example, any metal or alloy thereof selected from the group consisting of Cr, Ni, and Zn, but is not limited thereto.

[0062] The intermediate layer 30 preferably contains any one metal or alloy thereof selected from the group consisting of copper, iron, nickel, zinc, chromium, cobalt, titanium, tin, platinum, silver, and gold. Particularly when the ultrathin metal layer 13 is copper or an alloy thereof, the metal constituting the intermediate layer 30 is also preferably copper, or a copper-nickel alloy, or other copper-containing alloy. When the intermediate layer 30 is, for example, a Cu-Ni alloy, the ratio of Ni to Cu is preferably 10% to 90% in at%. However, this is not a limitation. By providing these intermediate layers 30, not only can the surface of the ultrathin metal layer 13 or the low-dielectric thin film 20 be protected, and the adhesion between the ultrathin metal layer 13 and the low-dielectric thin film 20 be improved, but the intermediate layer 30 can also be endowed with unique functions (e.g., functioning as an etch barrier layer during etching processes). The thickness of the intermediate layer 30 is not particularly limited as long as it can perform functions such as improving adhesion. Specifically, a thickness of 5 nm or more and 200 nm or less is preferred, and 10 nm or more and 100 nm or less is more preferable.

[0063] Below, especially as Figure 2 The manufacturing method of the metal laminate substrate with a carrier layer of the present invention will be described using the case of manufacturing a metal laminate substrate 1B with a carrier layer having a metal-containing intermediate layer 30 between a low dielectric thin film 20 and an ultra-thin metal layer 13 as an example. Figure 2 The metal laminate substrate 1B with a carrier layer shown can be obtained by preparing a metal foil 10 with a carrier layer consisting of a carrier layer 11, a release layer 12, and an ultrathin metal layer 13, and a low-dielectric film 20; providing a metal-containing intermediate layer 30 on the surface of the low-dielectric film 20; and then bonding them together by various methods such as cold rolling bonding and surface activation bonding to achieve interlayer adhesion. Furthermore, regarding the high-pressure bonding and / or heat treatment during the manufacture of the metal laminate substrate 1B with a carrier layer, significant changes in the microstructure of each layer of the metal laminate substrate 1B with a carrier layer before and after bonding and / or heat treatment may impair the properties of the metal laminate substrate 1B with a carrier layer. Therefore, it is preferable to select bonding and heat treatment conditions that can avoid such microstructure changes.

[0064] based on Figure 3A and Figure 3B The preferred method for manufacturing the metal laminate substrate 1B with a carrier layer is described. First, as follows... Figure 3A As shown, after the surface 20a of the low-dielectric thin film 20 is activated by sputter etching ( Figure 3A (a) A metal-containing intermediate layer 30 is sputtered onto the surface 20a of the low-dielectric thin film 20. The conditions for sputtering can be appropriately set according to the type of metal constituting the intermediate layer 30 or the thickness of the intermediate layer 30.

[0065] Next, as Figure 3BAs shown, the surface 30a of the intermediate layer 30 is activated by sputter etching, the surface 13a of the extremely thin metal layer 13 of the metal foil 10 with the carrier layer is activated by sputter etching, and these activated surfaces are rolled together. Figure 3B (c)) thereby enabling the fabrication of a metal laminate substrate 1B with a carrier layer. Figure 3B (d) Furthermore, if a coarsening particle layer or a rust-preventive layer is present on the surface 13a of the ultrathin metal layer 13, the surface of the coarsening particle layer or the rust-preventive layer is activated by sputter etching. In this case, the coarsening particle layer or the rust-preventive layer can be completely removed by sputter etching, or it can remain without removal. The reduction rate during rolling bonding is set to 0 to 30%. Preferably, it is 0 to 15%. The above-described surface activation bonding method can reduce the reduction rate, so bonding can be performed while maintaining the function of the release layer 12 (low adhesion). In addition, an ultrathin metal layer 13 with excellent thickness accuracy can be formed without wrinkles or cracks. Furthermore, the undulation of the interface between the ultrathin metal layer 13 and the intermediate layer 30 and the low dielectric film 20 can be reduced. Therefore, when pattern etching is performed on the ultrathin metal layer 13 and the intermediate layer 30 to form a circuit, the thickness accuracy is excellent, and thus, a precise circuit can be obtained.

[0066] Furthermore, on the surface 30a of the intermediate layer 30 or the surface 13a of the ultrathin metal layer 13 before activation by sputter etching, Ni plating, chromate treatment, silane coupling agent treatment, etc., may be performed as needed to prevent oxidation or improve adhesion. In addition, the surface 13a of the ultrathin metal layer 13 may be roughened as needed to improve adhesion with the intermediate layer 30.

[0067] Sputter etching can be performed as follows: For example, a metal foil 10 with a carrier layer or a low-dielectric film 20 with an intermediate layer 30 is prepared as a long roll with a width of 100 mm to 600 mm. The bonding surface of the metal foil 10 with the carrier layer or the low-dielectric film 20 is set as a grounded electrode. An AC current of 1 MHz to 50 MHz is applied between the electrode and the other electrode, which is supported by an insulating layer, to generate a glow discharge. The area of ​​the electrode exposed to the plasma generated by the glow discharge is set to less than 1 / 3 of the area of ​​the other electrode. In the sputter etching process, the grounded electrode is in the form of a cooling roller to prevent the temperature of the transported material from rising.

[0068] In sputtering etching, the bonding surfaces of the metal foil 10 with a carrier layer or the low-dielectric thin film 20 are sputtered under vacuum using an inert gas. This completely removes surface adsorbates and some or all of the oxide layer on the surface. Ideally, the oxide layer of copper should be completely removed. Argon, neon, xenon, krypton, or mixtures containing at least one of these inert gases can be used. Depending on the type of metal, adsorbates on the surface of the extremely thin metal layer 13 or the intermediate layer 30 can be completely removed with an etching depth of approximately 1 nm. In particular, the oxide layer of copper can typically be removed with an etching depth of approximately 5 nm to 12 nm (SiO2 equivalent).

[0069] The sputtering etching conditions can be appropriately set depending on the type of the ultrathin metal layer 13 or the intermediate layer 30. For example, it can be performed under vacuum with a plasma output of 100W to 10kW and a linear velocity of 0.5m / min to 30m / min. To prevent the re-adsorption of substances on the surface, the higher the vacuum level, the better; for example, 1×10⁻⁶ is sufficient. －5 Pa to 10 Pa is sufficient.

[0070] The surfaces of the ultrathin metal layer 13 and the intermediate layer 30, which have undergone sputtering etching, can be pressed together by roll bonding. The rolling line load for roll bonding is not particularly limited; for example, it can be set to a range of 0.1 tf / cm to 10 tf / cm. However, when the thickness of the low-dielectric film 20 with the carrier layer 10 or the intermediate layer 30 before bonding is large, it is sometimes necessary to increase the rolling line load to ensure pressure during bonding, so this value range is not limited. On the other hand, if the rolling line load is too high, not only the surface of the ultrathin metal layer 13 or the intermediate layer 30, but also the bonding interface is prone to deformation, thus potentially reducing the thickness accuracy of each layer in the carrier layer metal laminate substrate 1B. Furthermore, if the rolling line load is high, the processing strain applied during bonding may increase.

[0071] The reduction rate during crimping is 30% or less, preferably 8% or less, and more preferably 6% or less. Furthermore, the thickness can remain unchanged before and after crimping; therefore, the lower limit of the reduction rate is 0%.

[0072] To prevent a decrease in the bonding strength between the two due to the re-adsorption of oxygen on the surface of the extremely thin metal layer 13 or the intermediate layer 30, the roll bonding is preferably carried out in a non-oxidizing atmosphere, such as in a vacuum or an inert gas atmosphere such as Ar.

[0073] Furthermore, the metal laminate substrate 1B with a carrier layer obtained by pressing can be further heat-treated as needed. Heat treatment can remove strain from the extremely thin metal layer 13 or the intermediate layer 30 and improve interlayer adhesion. However, this heat treatment also carries the possibility that, when performed at high temperatures for an extended period, bubbles may form on the carrier layer 11 starting from the peeling layer 12, and the carrier layer 11 may peel off starting from these bubbles; conversely, the adhesion between the carrier layer 11 and the extremely thin metal layer 13 may increase through interdiffusion, making peeling of the carrier layer 11 difficult. Additionally, depending on the combination of the extremely thin metal layer 13 and the intermediate layer 30, intermetallic compounds may form at the interface, leading to a decrease in adhesion (bonding strength). Therefore, the aforementioned heat treatment is performed at a temperature of 160°C or higher and 300°C or lower. More preferably, it is 180°C or higher and 290°C or lower. Alternatively, it is preferable not to perform heat treatment after rolling bonding. Furthermore, if the carrier layer 11 is peeled off and removed from the bonded metal laminate substrate 1B with the carrier layer, heat treatment can be performed within a temperature range in which intermetallic compounds do not form at the interface between the extremely thin metal layer 13 and the intermediate layer 30.

[0074] Next, the metal laminate substrate and its manufacturing method of the present invention will be described. Figure 4 This is a diagram illustrating the manufacturing process of a metal laminated substrate according to an embodiment of the present invention. Figure 4 The metal laminate substrate 2 shown is roughly constructed by laminating an extremely thin metal layer 13 onto one side of a low-dielectric thin film 20 via a metal-containing intermediate layer 30. The metal laminate substrate 2, except for lacking the carrier layer 11 and the release layer 12, is similar to... Figure 2 The metal laminate substrate 2 shown is identical to the metal laminate substrate 1B with a carrier layer, and the structure of each layer is the same as that of each layer in the metal laminate substrate 1B with a carrier layer. This metal laminate substrate 2 can be obtained using the metal laminate substrate 1B with a carrier layer. That is, as shown... Figure 4 As shown, a metal laminate substrate 1B with a carrier layer is prepared. Figure 4 (a)) The carrier layer 11 and the release layer 12 in the metal laminate substrate 1B with the carrier layer are peeled off together. Figure 4 (b)) Thus, a three-layer metal laminate substrate 2 can be obtained. Figure 4 (c)).

[0075] The manufactured metal laminate substrate 2 has, for example, an extremely thin metal layer 13 with a thickness of 0.5 μm or more and 10 μm or less, and can be used as a metal laminate substrate (metal-clad laminate) for fabricating flexible circuit boards. Furthermore, the metal laminate substrate of the present invention is a substrate in which an additional metal layer is deposited on the surface opposite to the low-dielectric thin film of the extremely thin metal layer 13 by electroless plating, electrolytic plating (e.g., copper plating), or the like.

[0076] A printed circuit board with fine circuits can be obtained using a metal laminate substrate 2. During the circuit formation process, the additional metal layer can be formed only in the circuit portion. Specifically, a printed circuit board can be obtained using currently known methods such as the modified semi-additive process (MSAP) or the semi-additive process (SAP). For example, the non-circuit portion of the extremely thin metal layer 13 in the metal laminate substrate 2 is covered, and copper plating is performed on the uncovered portion to form an additional metal layer. After removing the cover, the extremely thin metal layer 13 that was covered and hidden is removed by etching, thereby manufacturing a printed circuit board. Furthermore, the "printed circuit board" in this invention includes not only the laminate for forming circuits but also components on which electronic parts such as ICs are mounted after the circuit is formed.

[0077] exist Figure 1 Metal laminate substrate 1A with carrier layer in the middle Figure 2 Metal laminate substrate 1B with carrier layer in the middle, and Figure 4 In the embodiment of the metal laminate substrate 2, the case where a metal foil 10 with a carrier layer or even an extremely thin metal layer 13 is laminated on one side of the low-dielectric film 20 has been described, but it is not limited to this. That is, an intermediate layer 30, an extremely thin metal layer 13, a release layer 12, and a carrier layer 11 may also be provided on both sides of the low-dielectric film 20 as needed. By using a metal laminate substrate with a carrier layer on both sides of the low-dielectric film 20, it is possible to obtain a flexible printed circuit board with circuits formed on both sides of the low-dielectric film 20.

[0078] Example

[0079] The present invention will now be described in more detail based on embodiments and comparative examples, but the present invention is not limited to these embodiments.

[0080] (Example 1)

[0081] First, a copper foil (MT18FL manufactured by Mitsui Metals & Mining Co., Ltd.) with a carrier layer was prepared as follows: a copper carrier layer with a thickness of 18 μm, on which an ultra-thin copper layer of 1.5 μm thickness was formed by a release layer (organic release layer), and a roughening particle layer and an anti-rust layer were formed on its surface; and a liquid crystal polymer (LCP) film with a thickness of 25 μm as a low dielectric film. After the surface of the LCP film was activated by sputter etching, an intermediate layer (40 nm thick) made of copper was formed by sputtering. Then, the surfaces of the ultra-thin copper layer and the intermediate layer were rolled together to manufacture a metal laminate substrate with a carrier layer as the target product. The line load during pressing was set to 1.5 tf / cm, and the reduction rate of the surface activation bonding was 2.2%. After rolling bonding, heat treatment was performed at 240°C.

[0082] (Example 2)

[0083] The metal foil with a carrier layer used was a copper foil (MT18FL manufactured by Mitsui Metals & Mining Co., Ltd.) with a carrier layer consisting of an 18 μm thick carrier layer, an ultrathin copper layer of 1.5 μm thickness formed by a release layer (organic release layer), and a roughening particle layer and an anti-rust layer formed on its surface. Additionally, as a low-dielectric film, a 100 μm thick LCP film was used. After surface activation by sputter etching, a copper intermediate layer (40 nm thick) was formed by sputtering. Then, the surfaces of the ultrathin copper layer and the intermediate layer were rolled together and heat-treated to manufacture a metal laminate substrate with a carrier layer. The bonding conditions are shown in Table 1. Furthermore, the reduction rate of the surface activation bonding was 2.5%.

[0084] (Examples 3 and 4)

[0085] Except for changing the bonding conditions as shown in Table 1, the same procedure as in Example 2 was followed to manufacture the metal laminate substrate with the carrier layer. The reduction rates in Examples 3 and 4 were 2.5% and 3.5%, respectively.

[0086] (Example 5)

[0087] As a low-dielectric thin film and intermediate layer, similar to Example 1, a component with a copper intermediate layer (40 nm thick) was formed by sputtering on the surface of a 25 μm thick LCP thin film. The bonding conditions were further modified as shown in Table 1. Otherwise, the same procedure as in Example 2 was followed to manufacture a metal laminate substrate with a carrier layer. The reduction ratio was 2.2%.

[0088] (Example 6)

[0089] As a carrier-layer metal foil, a copper foil (manufactured by JX Metals Co., Ltd., JXUT-III) with a carrier layer, on a carrier layer of 18 μm thickness made of copper, was used. An extremely thin copper layer of 3.0 μm thickness was formed by a release layer (inorganic release layer), and a coarsening particle layer and an anti-rust layer were formed on its surface. The bonding conditions were further modified as shown in Table 1. Otherwise, the process was the same as in Example 5 to manufacture the carrier-layer metal laminate substrate. The reduction rate was 4.3%.

[0090] (Example 7)

[0091] As a low-dielectric thin film and intermediate layer, a component was used in which a copper intermediate layer (40 nm thick) was formed by sputtering on the surface of a 25 μm thick low-dielectric polyimide (modified polyimide, MPI) thin film. Otherwise, the same procedure as in Example 4 was followed to manufacture a metal laminate substrate with a carrier layer. The reduction ratio was 2.2%.

[0092] (Example 8)

[0093] As a carrier-layered metal foil, a copper foil (prototype 1) with a carrier layer consisting of an extremely thin copper layer (2.0 μm thick) and a rust-preventive layer (without coarsening particles) on its surface was prepared by applying a release layer (inorganic release layer) to an 18 μm thick carrier layer made of copper. The bonding conditions were further modified as shown in Table 1. Otherwise, the process was the same as in Example 6 to manufacture the carrier-layered metal laminate substrate. The reduction rate was 2.2%.

[0094] (Example 9)

[0095] As a carrier-layered metal foil, a copper foil (prototype 2) with an extremely thin copper layer of only 5.0 μm thickness and a rust-preventive layer (without coarsening particles) on its surface was used, on a carrier layer of 18 μm thickness made of copper. The bonding conditions were further modified as shown in Table 1. Otherwise, the process was the same as in Example 8 to manufacture the carrier-layered metal laminate substrate. The reduction rate was 6.3%.

[0096] (Comparative Example 1)

[0097] Except for changing the bonding conditions as shown in Table 1, the same procedure as in Example 5 was followed to manufacture the metal laminate substrate with the carrier layer. The reduction ratio was 2.2%.

[0098] (Comparative Example 2)

[0099] Except for changing the bonding conditions as shown in Table 1, the same procedure as in Example 6 was followed to manufacture the metal laminate substrate with the carrier layer. The reduction ratio was 4.3%.

[0100] (Comparative Example 3)

[0101] Except for changing the bonding conditions as shown in Table 1, the same procedure as in Example 5 was followed to manufacture the metal laminate substrate with the carrier layer. The reduction ratio was 2.2%.

[0102] (Comparative Example 4)

[0103] Except for changing the bonding conditions as shown in Table 1, the same procedure as in Example 6 was followed to manufacture the metal laminate substrate with the carrier layer. The reduction ratio was 4.3%.

[0104] (Comparative Example 5)

[0105] First, a copper foil with a carrier layer was prepared: a copper foil (MT18FL manufactured by Mitsui Metals & Mining Co., Ltd.) with a carrier layer, on which an extremely thin copper layer of 2.0 μm thickness was formed by a release layer (organic release layer), and a roughening particle layer and an anti-rust layer were formed on its surface; and a liquid crystal polymer (LCP) film with a thickness of 25 μm as a low dielectric film. Next, the copper foil with the carrier layer and the LCP film were bonded together by hot pressing to manufacture a metal laminate substrate with a carrier layer. The hot pressing conditions are shown in Table 2.

[0106] (Compare Examples 6 and 7)

[0107] Except for changing the hot pressing conditions as shown in Table 2, the same procedure as in Comparative Example 5 was followed to manufacture a metal laminate substrate with a carrier layer.

[0108] (Comparative Example 8)

[0109] First, as the carrier layer metal foil, a copper foil (manufactured by JX Metals Co., Ltd., JXUT-III) with a carrier layer consisting of an 18 μm thick copper carrier layer, an ultra-thin copper layer of 3.0 μm thickness formed by a release layer (inorganic release layer), and a roughening particle layer and an anti-rust layer formed on its surface, was prepared. A liquid crystal polymer (LCP) film of 25 μm thickness was also prepared as the low-dielectric film. Next, the copper foil with the carrier layer and the LCP film were bonded together by hot pressing to manufacture a metal laminate substrate with a carrier layer. The hot pressing conditions are shown in Table 2.

[0110] (Compare Examples 9 and 10)

[0111] Except for changing the hot pressing conditions as shown in Table 2, the same procedure as in Comparative Example 8 was followed to manufacture a metal laminate substrate with a carrier layer.

[0112] For the metal laminate substrates with carrier layers obtained in Examples 1-9 and Comparative Examples 1-10, the bonding strength between the ultrathin copper layer and the low-dielectric film, the peel strength between the carrier layer and the ultrathin copper layer, and the total thickness were measured. The measurement results are shown in Table 3.

[0113] [Table 1]

[0114]

[0115] [Table 2]

[0116]

[0117] [Table 3]

[0118]

[0119] As shown in Tables 1 and 3, under high heat treatment temperatures (Comparative Examples 1 and 2) and low heat treatment temperatures (Comparative Examples 3 and 4), it is not possible to simultaneously achieve low adhesion between the carrier layer and the ultrathin copper layer and high adhesion between the ultrathin copper layer and the low dielectric film.

[0120] Furthermore, as shown in Tables 2 and 3, when bonding the copper foil with the carrier layer and the low-dielectric film via thermoforming, it is impossible to simultaneously achieve both low adhesion between the carrier layer and the extremely thin copper layer and high adhesion between the extremely thin copper layer and the low-dielectric film. Particularly in Comparative Examples 6, 7, 9, and 10, the low-dielectric film becomes brittle and deteriorates, making it unsuitable as a substrate for metal laminates used to form circuits. Additionally, in Comparative Example 10, the carrier layer and the extremely thin copper layer cannot be peeled off.

[0121] In addition, for each peel surface after the bonding strength was measured in Example 5, observation was performed using scanning electron microscopy (SEM) and surface elemental analysis was performed using EDX. The scanning electron microscope images were then displayed on... Figure 5 As shown in the figure. The analysis results confirmed that no copper was attached to the peeling surface on the LCP side in Example 5. In addition, some LCP with agglomeration and damage was attached to the side of the extremely thin copper layer (the peeling surface is the intermediate layer). Therefore, it can be seen that the peeling was caused by both internal damage to the LCP and the interface peeling between the intermediate layer and the LCP.

[0122] (Examples 10-16)

[0123] By removing the carrier layer from the metal laminate substrate with carrier layer obtained in Examples 1 to 7, a metal laminate substrate having an extremely thin copper layer with a thickness of 1.5 μm to 3.0 μm, including a coarsening particle layer and a rust-preventive layer, is manufactured.

[0124] (Examples 17 and 18)

[0125] By removing the carrier layer from the metal laminate substrate with carrier layer obtained in Examples 8 and 9, a metal laminate substrate having an extremely thin copper layer with a thickness of 2.0 μm to 5.0 μm containing only an anti-rust layer (excluding a coarsening particle layer) is manufactured.

[0126] For the metal laminate substrates obtained in Examples 10-18, the bonding strength, total thickness, and thickness of the ultrathin copper layer and the low-dielectric film were measured. The measurement results are shown in Table 4.

[0127] [Table 4]

[0128]

[0129]

[0130] The metal laminated substrates of Examples 10-16 have a structure consisting of an extremely thin copper layer, a coarsening particle layer, a rust-preventive layer, an intermediate layer (copper), and an LCP or MPI film. Furthermore, the metal laminated substrates of Examples 17 and 18 have a structure consisting of an extremely thin copper layer, a rust-preventive layer, an intermediate layer (copper), and an LCP. For these metal laminated substrates, the layering state of each layer can be determined by depth profile analysis using glow discharge spectroscopy (GDS) or Auger electron spectroscopy (AES), or by cross-sectional observation using transmission electron microscopy (TEM).

[0131] Alternatively, circuit patterns can be formed on an extremely thin copper layer of a metal laminate substrate using photoresist or the like, and fine circuits can be formed on a low-dielectric thin film using a modified semi-additive process (MSAP) or a semi-additive process (SAP).

[0132] Explanation of reference numerals in the attached figures

[0133] 1A Metal laminate substrate with carrier layer

[0134] 1B Metal laminate substrate with carrier layer

[0135] 2 Metal laminated substrate

[0136] 10 Metal foil with carrier layer

[0137] 11. Carrier layer

[0138] 12. Peel-off layer

[0139] 13. Extremely thin metal layer

[0140] 13a Surface of an extremely thin metal layer

[0141] 20 Low-dielectric thin films

[0142] 20a low dielectric thin film surface

[0143] 30 Intermediate Layer

[0144] Surface of the 30a intermediate layer

[0145] All publications, patents and patent applications cited in this specification are incorporated herein by reference.

Claims

1. A method for manufacturing a metal laminate substrate with a carrier layer, wherein, The manufacturing method includes: The process of preparing a low-dielectric thin film and a metal foil with a carrier layer consisting of at least three layers including a carrier layer, a release layer and an extremely thin metal layer; The process of activating at least one side of the low-dielectric thin film by sputtering etching, and then sputtering a metal intermediate layer on the surface. The process of activating the surface of the intermediate layer by sputter etching; The process of activating the surface of the extremely thin metal layer by sputtering etching; The process of rolling the activated surfaces of the intermediate layer and the ultrathin metal layer together with a reduction rate of 0-30%. The low-dielectric film has a metal foil with a carrier layer, consisting of at least three layers including a carrier layer, a release layer, and an extremely thin metal layer, laminated on at least one side. The bonding strength between the ultrathin metal layer and the low-dielectric film is greater than the peel strength between the carrier layer and the ultrathin metal layer. The bonding strength between the ultrathin metal layer and the low-dielectric film is greater than 2.0 N / cm. For the thickness of the low-dielectric film, the deviation of the measured values ​​from the average value at 10 points is within 10% of all measured values. The low-dielectric film is composed of a liquid crystal polymer, which is composed of an aromatic polyester resin. The low-dielectric thin film and the ultra-thin metal layer are provided with one or more metal-containing intermediate layers, which are formed on the low-dielectric thin film by sputtering. The thickness of the ultrathin metal layer is greater than 1 μm and less than 7 μm.

2. The method for manufacturing a metal laminate substrate with a carrier layer according to claim 1, wherein, After rolling and joining, heat treatment is performed at a temperature above 160°C and below 300°C.

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