TWI868201B - Carrier layer metal laminate substrate and manufacturing method thereof, metal laminate substrate and manufacturing method thereof, and printed circuit board - Google Patents

Abstract

The purpose of the present invention is to provide a carrier layer metal laminate substrate that maintains low adhesion between a carrier layer and an ultra-thin metal layer while ensuring high adhesion between the ultra-thin metal layer and a low dielectric film. The carrier layer metal laminate substrate (1A) is characterized in that a carrier layer metal foil (10) composed of three layers including a carrier layer (11), a peeling layer (12) and an ultra-thin metal layer (13) is laminated on one surface of a low dielectric film (20), and the bonding strength between the ultra-thin metal layer (13) and the low dielectric film (20) is greater than the peeling strength between the carrier layer (11) and the ultra-thin metal layer (13).

Description

Carrier layer metal laminate substrate and manufacturing method thereof, metal laminate substrate and manufacturing method thereof, and printed circuit board

The present invention relates to a carrier layer metal laminate substrate and a manufacturing method thereof, a metal laminate substrate and a manufacturing method thereof, and a printed circuit board.

In the past, a metal foil with a carrier layer was known as a member 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, and a metal laminate substrate (metal laminate board) with a carrier layer can be obtained by laminating it with a hard substrate made of glass epoxy resin or the like. In addition, a metal laminate substrate with a flexible polymer film laminated instead of the hard substrate is also known, and is used as a metal laminate substrate for forming a flexible wiring substrate. In particular, low-dielectric polymer films such as low-dielectric polyimide are used as polymer films, which are useful for high-frequency circuits in fifth-generation mobile communication systems (5G).

(Patent Document 1) discloses a copper foil with a carrier having an intermediate layer and an ultra-thin copper layer formed on one or both sides of a carrier, wherein the ultra-thin copper layer forms a primary particle layer containing copper on the surface of the copper foil, and then forms a secondary particle layer containing a ternary alloy composed of copper, cobalt and nickel on the primary particle layer, and the copper foil with a carrier having a color difference △a* value of less than 4.0 and a color difference △b* value of less than 3.5 when the color difference of the roughened surface is measured according to the color difference system described in Japanese Industrial Standard JIS Z8730 with respect to white is a copper foil for high-frequency circuits. In addition, (Patent Document 1) also describes a carrier-bonded copper laminate in which a hard substrate such as a paper-based phenolic resin or a polymer film such as a liquid crystal polymer (LCP) is laminated with the aforementioned carrier copper foil.

[Prior Art Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Publication No. 2014-224318

In the aforementioned (Patent Document 1), when bonding the carrier copper foil and the hard substrate, the resin is impregnated into the base material such as glass cloth, and the glass fiber adhesive sheet is prepared to cure the resin to a semi-cured state, and the copper foil is overlapped on the glass fiber adhesive sheet and heated and pressurized. In addition, when a polymer film is used instead of a hard substrate, the copper foil is also laminated (thermocompression bonding) to the base material such as liquid crystal polymer under high temperature and high pressure.

However, in particular, when a low dielectric film such as a liquid crystal polymer or polyvinyl fluoride or low dielectric imide suitable for high frequency circuits is attached to a carrier metal foil by heat pressing, the temperature of heat pressing must be above 280°C or above 300°C in consideration of the melting point and other characteristics of the low dielectric film. In such a temperature range, the peeling layer between the carrier layer and the ultra-thin metal layer is degraded, which may impair the peeling property of the carrier. On the other hand, if the temperature of heat pressing is lowered in order to maintain the peeling property, the adhesion between the ultra-thin metal layer and the low dielectric film is reduced. In other words, it has always been difficult to maintain the peeling property (low adhesion) between the carrier and the ultra-thin metal layer, and to ensure the high adhesion between the ultra-thin metal layer and the low dielectric film.

Here, the purpose of the present invention is to provide a carrier layer-attached metal laminate substrate and a manufacturing method thereof that maintains low adhesion between the carrier layer and the ultra-thin metal layer and ensures high adhesion between the ultra-thin metal layer and the low dielectric film. In addition, the purpose is to provide a metal laminate substrate on which a low dielectric film and an ultra-thin metal layer are laminated and a manufacturing method thereof. Furthermore, the purpose is to provide a printed circuit board that can be obtained from the aforementioned metal laminate substrate and is suitable for use as a high-frequency circuit.

As a result of careful research, the inventor of this case found that when laminating a low dielectric film and a carrier layer metal foil composed of a carrier layer, a peeling layer and an ultra-thin metal layer, a specific bonding method is adopted to respectively control the bonding strength between the ultra-thin metal layer and the low dielectric film, and the peeling strength between the carrier layer and the ultra-thin metal layer, so as to solve the above-mentioned problems and complete the present invention. That is, the gist of the present invention is as follows.

(1) A carrier layer-attached metal laminate substrate having a carrier layer metal foil composed of at least three layers including a carrier layer, a peeling layer and an ultra-thin metal layer laminated on at least one side of a low dielectric film, wherein the bonding strength between the ultra-thin metal layer and the low dielectric film is greater than the peeling strength between the carrier layer and the ultra-thin metal layer.

(2) The metal multilayer substrate with a carrier layer described in (1) above has one or more metal-containing intermediate layers between the low dielectric film and the ultra-thin metal layer.

(3) The carrier layer metal laminate substrate described in (2) above, wherein the intermediate layer comprises any metal selected from the group consisting of copper, iron, nickel, zinc, chromium, cobalt, titanium, tin, platinum, silver and gold, or its alloy.

(4) A metal laminate substrate with a carrier layer as described in any of (1) to (3) above, and a low dielectric film, which is a low dielectric polymer film selected from the group consisting of liquid crystal polymer, polyvinyl fluoride, polyamide and low dielectric polyimide.

(5) A metal laminate substrate with a carrier layer as described in any one of (1) to (4) above, wherein the peeling strength between the carrier layer and the ultra-thin metal layer is greater than 0.15 N/cm and less than 0.5 N/cm.

(6) In the metal laminate substrate with a carrier layer described in any one of (1) to (5) above, the bonding strength between the ultra-thin metal layer and the low dielectric film is 2.0 N/cm or more.

(7) The carrier layer metal laminate substrate described in any one of (1) to (6) above, wherein the peeling layer is an organic peeling layer or an inorganic peeling layer.

(8) A metal laminate substrate with a carrier layer as described in any of (1) to (7) above, wherein the thickness of the ultra-thin metal layer is not less than 0.5 μm and not more than 10 μm.

(9) The method for manufacturing a carrier layer metal laminate substrate described in (2) above comprises: Preparing a low dielectric film and a carrier layer metal foil composed of at least three layers including a carrier layer, a peeling layer and an ultra-thin metal layer, activating at least one side of the low dielectric film by sputter etching, and then A method for manufacturing a metal-layered substrate with a carrier layer, comprising the steps of forming a metal-containing intermediate layer by sputter plating, activating the surface of the intermediate layer by sputter plating, activating the surface of the extremely thin metal layer by sputter plating, and bonding the activated surfaces to each other by rolling at a reduction rate of 0 to 30%.

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

(11) The method for manufacturing a metal laminate substrate with a carrier layer described in (9) or (10) above, wherein after the roll bonding, heat treatment is performed at a temperature of not less than 160°C and not more than 300°C.

(12) A metal-layer substrate, wherein an extremely thin metal layer is layered on at least one side of a low dielectric film via an intermediate layer containing metal, and the bonding strength between the low dielectric film and the extremely thin metal layer is greater than 2.0 N/cm.

(13) The metal layer substrate described in (12) above, wherein the intermediate layer comprises any metal selected from the group consisting of copper, iron, nickel, zinc, chromium, cobalt, titanium, tin, platinum, silver and gold, or its alloy.

(14) The metal layer substrate described in (12) or (13) above is layered with a roughened particle layer containing any metal selected from the group consisting of Cu, Co and Ni or its alloy, and/or a rust-proof layer containing any metal selected from the group consisting of Cr, Ni and Zn or its alloy on the surface of the intermediate layer side of the extremely thin metal layer.

(15) A metal layer substrate as described in any one of (12) to (14) above, wherein the thickness of the ultra-thin metal layer is not less than 0.5 μm and not more than 10 μm.

(16) A method for manufacturing 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 a metal, and the method comprises the step of peeling off the carrier layer of the metal laminate substrate with a carrier layer described in (2) above.

(17) A printed circuit board having a circuit formed on an intermediate layer and an extremely thin metal layer of a metal multilayer substrate described in any one of (12) to (15) above.

This specification contains the contents disclosed in Japanese Patent Application No. 2019-154167 and No. 2020-013319, which are the basis of the priority rights of this case.

According to the present invention, in the metal layer-mounted substrate with a carrier layer, it is possible to maintain the low adhesion between the carrier layer and the ultra-thin metal layer, and ensure the high adhesion between the ultra-thin metal layer and the low dielectric film. In addition, a metal layer-mounted substrate with a low dielectric film and an ultra-thin metal layer can be obtained. This metal layer-mounted substrate is suitable for use in high-frequency circuits.

1A: Metal laminate substrate with carrier layer

1B: Metal laminate substrate with carrier layer

2: Metal layer substrate

10: Carrier layer metal foil

11: Carrier layer

12: Peel off layer

13: Extremely thin metal layer

13a: Surface of extremely thin metal layer

20: Low dielectric film

20a: Surface of low dielectric film

30: Middle layer

30a: Surface of the middle layer

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

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

[Figure 3A] is a diagram showing the manufacturing steps of the carrier layer metal laminate substrate related to the second embodiment of the present invention.

[Figure 3B] is a diagram showing the manufacturing steps of the carrier layer metal laminate substrate related to the second embodiment of the present invention.

[Figure 4] is a diagram showing the manufacturing steps of a metal laminate substrate related to an embodiment of the present invention.

[Figure 5] is a scanning electron microscope (SEM) image of the peeled surface when peeling between the extremely thin copper layer and the low dielectric film for the metal laminate substrate with a carrier layer in Example 5.

The present invention is described in detail below.

FIG1 shows a cross section of a carrier layer metal laminate substrate related to the first embodiment of the present invention. The carrier layer metal laminate substrate 1A shown in FIG1 is roughly composed of a carrier layer metal foil 10 composed of a carrier layer 11, a peeling layer 12 and an ultra-thin metal layer 13, and a low dielectric film 20 stacked in sequence.

Furthermore, although not shown in FIG. 1 , a roughened particle layer or a rust-proof layer, a treatment layer formed by a silane coupling agent, etc. may be deposited on the surface of the low dielectric film 20 side of the ultra-thin metal layer 13. These layers may be deposited in any one type of layer or in a plurality of types of layers. The roughened particle layer may contain, for example, any metal selected from the group consisting of Cu, Co, and Ni or its alloy. Specifically, a cobalt-nickel alloy layer and a copper-cobalt-nickel alloy layer may be listed. In addition, the rust-proof layer may contain, for example, any metal selected from the group consisting of Cr, Ni, and Zn or its alloy. Specifically, chromium oxide coating treatment, chromium oxide and zinc/zinc oxide mixture coating treatment, Ni plating, etc. can be listed. Furthermore, as silane coupling agents, olefinic silanes, epoxy silanes, acrylic silanes, amino silanes, and alkyl silanes can be listed, but they are not limited to these. The application of silane coupling agents can be appropriately carried out by spraying with a spray, applying with a coater, dipping, etc.

The carrier layer 11 is in the shape of a thin sheet and functions as a supporting material or protective layer for preventing wrinkles or breaks on the carrier layer metal laminate substrate 1A and scratches on the ultra-thin metal layer 13. The carrier layer 11 may be a foil or plate made of copper, aluminum, nickel, and alloys thereof (stainless steel, brass, etc.), or a resin coated with metal on the surface. Copper foil is the best.

The thickness of the carrier layer 11 is not particularly limited and can be appropriately set according to the desired characteristics such as flexibility. Specifically, it is preferably between 10 μm and 100 μm. If the thickness is too thin, the handling of the metal foil 10 attached to the carrier layer may be impaired, so it is not good. In other words, deformation may occur during handling, and wrinkles or cracks may occur in the extremely thin metal layer 13. In addition, if the carrier layer 11 is too thick, it has too high rigidity as a supporting material, and it may be difficult to peel off the extremely thin metal layer 13, so it is not good. Furthermore, it also leads to an increase in the cost of producing the metal foil 10 attached to the carrier layer.

The peeling layer 12 has the function of reducing the peeling strength of the carrier layer 11 and inhibiting the mutual diffusion between the carrier layer 11 and the ultra-thin metal layer 13 that may be caused when the carrier layer metal foil 10 and the low dielectric film 20 are heated when they are bonded. The peeling layer 12 can be any of an organic peeling layer and an inorganic peeling layer. As the components used for the organic peeling layer, for example, nitrogen-containing organic compounds, sulfur-containing organic compounds, carboxylic acids, etc. can be listed. As nitrogen-containing organic compounds, triazole compounds, imidazole compounds, etc. can be listed. 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 thiolbenzothiazole, trithiocyanate, and 2-benzimidazolethiohydride. Examples of carboxylic acids include monocarboxylic acids and dicarboxylic acids. In addition, components used in inorganic peeling layers include Ni, Mo, Co, Cr, Fe, Ti, W, P, Zn, and chromate-treated films. Furthermore, the formation of the peeling layer 12 can be performed by bringing a solution containing components of the peeling layer 12 into contact with the surface of the carrier layer 11 and fixing the peeling layer components on the surface of the carrier layer 11. When bringing the carrier layer 11 into contact with the solution containing components of the peeling layer 12, the contact can be performed by immersing the carrier layer 11 in the solution containing components of the peeling layer, spraying the solution containing components of the peeling layer, or letting the solution containing components of the peeling layer flow down, and then fixing the solution by drying. Alternatively, a method of forming a film of the components of the peeling layer 12 by a vapor phase method such as evaporation or sputtering can be used.

The thickness of the peeling layer 12 is typically 1 nm to 1 μm, preferably 5 nm to 500 nm, but not limited thereto. If the peeling layer 12 is too thin, it may not be separated from the ultra-thin metal layer 13 sufficiently, and the peeling may be poor. In addition, if the thickness is too thick, the peeling may be performed but the manufacturing cost increases, so it is appropriately set in consideration of these balances.

The metal constituting the ultra-thin metal layer 13 can be appropriately selected according to the characteristics of the use or purpose of the carrier layer metal laminate substrate 1A. Specifically, copper, iron, nickel, zinc, tin, chromium, gold, silver, platinum, cobalt, titanium and alloys based on any of these can be listed. In particular, a layer of copper or copper alloy is preferred. By rolling and bonding these metals with the low dielectric film 20, a flexible substrate for forming fine wiring can be obtained, for example.

The thickness of the ultra-thin metal layer 13 is between 0.5 μm and 10 μm. Preferably, it is between 1 μm and 7 μm. Here, the thickness of the ultra-thin metal layer 13 refers to the average value of the values obtained by taking an optical microscope photograph of the cross section of the carrier layer metal layer substrate 1A and measuring the thickness of the ultra-thin metal layer 13 at any 10 points in the optical microscope photograph.

The manufacturing method of such an ultra-thin metal layer 13 is not particularly limited, and it can be formed on the release layer 12 by wet film forming methods such as electroless plating and electroplating, dry film forming methods such as sputtering and chemical evaporation, or a combination of these.

In this embodiment, when comparing the bonding strength between the ultra-thin metal layer 13 and the low dielectric film 20 and the peeling strength between the carrier layer 11 and the ultra-thin metal layer 13, the bonding strength between the ultra-thin metal layer 13 and the low dielectric film 20 is greater. Thus, when the carrier layer 11 is peeled off from the ultra-thin metal layer 13, the peeling can be performed without causing wrinkles or cracks in the ultra-thin metal layer 13. However, if the values of the bonding strength between the ultra-thin metal layer 13 and the low dielectric film 20 and the values of the peeling strength between the carrier layer 11 and the ultra-thin metal layer 13 are too close, it may be difficult to peel the carrier layer 11 without affecting the interface between the ultra-thin metal layer 13 and the low dielectric film 20. Therefore, the difference between the bonding strength between the ultra-thin metal layer 13 and the low dielectric film 20 and the peeling strength between the carrier layer 11 and the ultra-thin metal layer 13 is preferably 0.25 N/cm or more, more preferably 0.5 N/cm or more, and most preferably 1.5 N/cm or more. As specific numerical values of the bonding strength between the ultra-thin metal layer 13 and the low dielectric film 20, and the peeling strength between the carrier layer 11 and the ultra-thin metal layer 13, the bonding strength between the ultra-thin metal layer 13 and the low dielectric film 20 is preferably 2.0 N/cm or more. In addition, the peeling strength between the carrier layer 11 and the ultra-thin metal layer 13 should be greater than 0, preferably 0.5 N/cm or less. In the region below about 0.05 N/cm, due to the influence of the rigidity of the material to be peeled (carrier layer 11, ultra-thin metal layer 13, low dielectric film 20, other anti-rust layers, etc.), it may be impossible to measure the correct peeling strength. The peel strength of the carrier layer 11 and the ultra-thin metal layer 13 is preferably in the range of 0.15 N/cm to 0.5 N/cm. In addition, in the measurement of the above-mentioned bonding strength value, first, a test piece with a width of 1 cm is made from the carrier layer-metal layered substrate 1A. Then, after removing the carrier layer 11, the surface of the ultra-thin metal layer 13 is electroplated (when the ultra-thin metal layer 13 is copper, for example, copper plating) to form a metal layer (including the ultra-thin metal layer 13) with a thickness of about 10 to 20 μm on the surface of the low dielectric film 20. Next, the metal layer of about 10 to 20 μm thickness and a portion of the low dielectric film 20 are peeled off, and the low dielectric film 20 is fixed to the support, and the metal layer of about 10 to 20 μm thickness is stretched in a 90° direction relative to the low dielectric film 20. The force required for peeling at this time is used as the bonding strength (unit: N/cm). In addition, in the measurement of the peeling strength, first, a test piece with a width of 1 cm is prepared from the carrier layer metal laminate substrate 1A. After partially peeling off the carrier layer 11, the low dielectric film 20 including the extremely thin metal layer 13 is fixed to the support, and the carrier layer 11 is stretched in a 90° direction relative to the low dielectric film 20 including the extremely thin metal layer 13. The force required for peeling at this time is used as the peeling strength (unit: N/cm).

In this specification, the term "bonding strength between an ultra-thin metal layer and a low dielectric film" refers to the bonding strength when the interface between the ultra-thin metal layer and the low dielectric film is peeled off, the bonding strength when the inner part of the ultra-thin metal layer is damaged and the bonding strength when the inner part of the low dielectric film is damaged and the bonding strength when the ultra-thin metal layer is peeled off. When a roughened particle layer or a rust-proof layer, a treatment layer using a silane coupling agent, etc. (collectively referred to as a "treatment layer") is deposited on the surface of the low dielectric film side of the metal layer, it also means the bonding strength in the case of peeling at the interface between the extremely thin metal layer and the treatment layer, the bonding strength in the case of peeling at the interface between the treatment layer and the low dielectric film, and the bonding strength in the case of peeling due to damage to the inside of the treatment layer. In addition, as in the case of the metal-layered substrate with a carrier layer (FIG. 2) described later, in the case of a metal-containing intermediate layer 30 between the low dielectric film 20 and the ultra-thin metal layer 13, the "bonding strength between the ultra-thin metal layer and the low dielectric film" also means the bonding strength in the case of peeling due to the destruction of the inner part of the ultra-thin metal layer. The bonding strength is any of the following situations: the bonding strength at the interface between the primary layer (the treatment layer is the treatment layer if it exists) and the intermediate layer is peeled off; the bonding strength at the interface between the intermediate layer and the low dielectric film is peeled off; the bonding strength at the interface between the intermediate layer and the low dielectric film is peeled off due to the internal destruction of the intermediate layer; and the bonding strength at the interface between the intermediate layer and the low dielectric film is peeled off due to the internal destruction of the low dielectric film.

The low dielectric film 20 is laminated on the extremely thin metal layer 13. As the material of the low dielectric film 20, any low dielectric polymer material that can be used as a flexible substrate can be used, for example, a material having a relative dielectric constant _εr of 3.3 or less and a dielectric loss tanδ of 0.006 or less, but not limited to these. Specifically, a material such as a liquid crystal polymer, polyvinyl fluoride (fluorine resin such as polytetrafluoroethylene), polyamide, isocyanate compound, polyamide imide, polyimide, low dielectric polyimide, polyethylene terephthalate, polyetherimide, etc. can be appropriately selected and used. Liquid crystal polymer, polyvinyl fluoride, polyamide or low dielectric polyimide is preferred. The low dielectric film 20 is a single-layer film or a laminate composed of multiple layers. In the case of multiple layers, any one or more of the multiple layers can be composed of the aforementioned low dielectric polymer material. The layers other than the layer composed of the low dielectric polymer material can be composed of various materials known in the past, such as epoxy resin. In addition, liquid crystal polymer refers to an aromatic polyester resin with p-hydroxybenzoic acid as a basic structure, which exhibits liquid crystal properties in a molten state.

The thickness of the low dielectric film 20 can be appropriately set according to the purpose of the metal laminate substrate. For example, when used as a flexible printed circuit board, the thickness is preferably 10 μm to 150 μm, and more preferably 10 μm to 120 μm. In addition, the thickness of the low dielectric film 20 before bonding can be measured using a micrometer, etc., and the average value of the thickness measured at 10 points randomly selected on the surface of the target low dielectric film. In addition, for the low dielectric film used, it is best that the deviation of all measured values from the average value of the 10-point measurement value is within 10%.

Next, the second embodiment of the present invention is described. FIG2 shows a cross section of a carrier layer metal layer substrate related to the second embodiment of the present invention. As shown in FIG2, this embodiment has a metal-containing intermediate layer 30 between an extremely thin metal layer 13 and a low dielectric film 20. This intermediate layer 30 can be a single layer or two or more layers. As the metal-containing intermediate layer 30, a metal layer formed by evaporation, electroless plating, or sputtering and disposed on the low dielectric film 20 can be cited.

Moreover, although not shown in FIG. 2 , similarly to the carrier layer metal layer substrate related to the first embodiment, a roughened particle layer, a rust-proof layer, a silane coupling agent layer, etc. may be deposited on the surface of the intermediate layer 30 side of the ultra-thin metal layer 13. These layers may be deposited in any one layer or in multiple layers. The roughened particle layer may contain, for example, any metal selected from the group consisting of Cu, Co, and Ni or its alloy, but may not be limited thereto. In addition, the rust-proof layer may contain, for example, any metal selected from the group consisting of Cr, Ni, and Zn or its alloy, but may not be limited thereto.

The intermediate layer 30 preferably includes any metal selected from the group consisting of copper, iron, nickel, zinc, chromium, cobalt, titanium, tin, platinum, silver and gold, or an alloy thereof. In particular, when the extremely thin metal layer 13 is copper or an alloy thereof, the metal constituting the intermediate layer 30 is preferably copper or a copper-containing alloy such as a copper-nickel alloy. When the intermediate layer 30 is, for example, a Cu-Ni alloy, the ratio of Ni to Cu is preferably 10 to 90 at%. However, it is not limited thereto. By providing these intermediate layers 30, not only can the surface of the ultra-thin metal layer 13 or the low dielectric film 20 be protected, but also the adhesion between the ultra-thin metal layer 13 and the low dielectric film 20 can be improved, and the intermediate layer 30 can also be given a unique function (for example, the function of an etching stop layer during etching processing, etc.). The thickness of the intermediate layer 30 is not particularly limited as long as it can play a role in improving adhesion. Specifically, a thickness of 5nm or more and 200nm or less is preferred, and more preferably 10nm or more and 100nm or less is preferred.

Next, the method for manufacturing the carrier layer metal laminate substrate of the present invention is explained by taking as an example the case of manufacturing the carrier layer metal laminate substrate 1B having a metal-containing intermediate layer 30 between a low dielectric film 20 and an extremely thin metal layer 13 as shown in FIG2. The carrier layer metal laminate substrate 1B shown in FIG2 is prepared by preparing a carrier layer metal foil 10 composed of a carrier layer 11, a peeling layer 12, an extremely thin metal layer 13, and a low dielectric film 20, and providing a metal-containing intermediate layer 30 on the surface of the low dielectric film 20, and then these are bonded to each other by various methods such as cold rolling bonding and surface activation bonding, and can be obtained by interlayer adhesion. In addition, during the manufacture of the carrier layer metal laminate substrate 1B, the bonding and/or heat treatment under high pressure may cause the structure of each layer of the carrier layer metal laminate substrate 1B to change significantly before and after the bonding and/or heat treatment, and may damage the characteristics of the carrier layer metal laminate substrate 1B. Therefore, it is best to select bonding/heat treatment conditions that can avoid such structural changes.

The best mode of the method for manufacturing the carrier layer metal laminate substrate 1B is described based on FIG. 3A and FIG. 3B. First, as shown in FIG. 3A, after the surface 20a of the low dielectric film 20 is activated by sputter etching (FIG. 3A (a)), a metal-containing intermediate layer 30 is sputter-formed on the surface 20a of the low dielectric film 20. The conditions for sputtering film formation can be appropriately set according to the type of metal constituting the intermediate layer 30 or the thickness of the intermediate layer 30.

Next, as shown in FIG3B , the surface 30a of the intermediate layer 30 is activated by sputter etching, and the surface 13a of the ultra-thin metal layer 13 of the carrier layer metal foil 10 is activated by sputter etching, and these activated surfaces are bonded to each other by rolling (FIG3B (c)), so that the carrier layer metal laminate substrate 1B can be manufactured (FIG3B (d)). In addition, when the surface 13a of the ultra-thin metal layer 13 includes a roughened particle layer or an anti-rust layer, the surface of the roughened particle layer or the anti-rust layer is activated by sputter etching. At this time, the roughened particle layer or the anti-rust layer can be completely removed by sputter etching, or can be left without being removed. The reduction rate during rolling bonding is 0~30%. Preferably, it is 0~15%. The aforementioned surface activated bonding method can reduce the reduction rate, so that bonding can be performed while maintaining the function (low adhesion) of the peeling layer 12. In addition, wrinkles or cracks do not occur, and an extremely thin metal layer 13 with excellent thickness accuracy can be formed. Furthermore, the undulation of the interface between the extremely thin metal layer 13 and the intermediate layer 30 and the low dielectric film 20 can be reduced, so when the extremely thin metal layer 13 and the intermediate layer 30 are patterned to form a circuit, a precise circuit can be obtained due to excellent thickness accuracy.

Furthermore, the surface 30a of the intermediate layer 30 or the surface 13a of the ultra-thin metal layer 13 before being activated by sputter etching may be subjected to Ni plating, chromate treatment, silane coupling agent treatment, etc., as needed, in order to prevent oxidation or improve adhesion. In addition, the surface 13a of the ultra-thin metal layer 13 may be roughened as needed to improve adhesion with the intermediate layer 30.

For sputter etching, for example, a carrier layer metal foil 10 or a low dielectric film 20 with an intermediate layer 30 to be bonded can be prepared and made into a long roll with a width of 100 mm to 600 mm, and an electrode with a bonding surface of the carrier layer metal foil 10 or the low dielectric film 20 as the grounded electrode is applied between the other electrodes supported by insulation to generate glow discharge, and the area of the electrode exposed in the plasma generated by glow discharge is less than 1/3 of the area of the other electrodes mentioned above. During the sputter etching process, the grounded electrode is in the form of a cooling roller to prevent the temperature of the conveying material from rising.

In the sputter etching process, the surface adsorbents on the carrier layer metal foil 10 or the surface to be bonded of the low dielectric film 20 are completely removed by sputtering with an inert gas under vacuum, and a part or all of the surface oxide layer is removed. It is better to completely remove the copper oxide layer. As an inert gas, argon, neon, xenon, krypton, etc., or a mixed gas containing at least one of these can be used. Although it depends on the type of metal, the adsorbents on the surface of the ultra-thin metal layer 13 or the intermediate layer 30 can be completely removed with an etching amount of about 1nm, especially the copper oxide layer, which can usually be removed at a level of 5nm~12nm ( _SiO2 conversion).

The processing conditions of sputter etching can be appropriately set according to the type of the ultra-thin metal layer 13 or the intermediate layer 30. For example, it can be carried out under vacuum with a plasma output of 100W~10kW and a linear speed of 0.5m/min~30m/min. At this time, the vacuum degree is preferably higher in order to prevent the re-adsorption of substances to the surface, for example, 1×10 ^-5 Pa~10Pa.

The surfaces of the sputter-etched ultra-thin metal layer 13 and the intermediate layer 30 can be pressed together by roller pressing. The pressing wire load of roller pressing is not particularly limited, and can be set in the range of 0.1tf/cm to 10tf/cm, for example. However, in cases where the thickness of the carrier layer metal foil 10 or the low dielectric film 20 for setting the intermediate layer 30 before joining is large, it may be necessary to increase the pressing wire load in order to ensure the pressure during joining, and it is not limited to this numerical range. On the other hand, if the rolling line load is too high, not only the surface of the ultra-thin metal layer 13 or the intermediate layer 30 but also the bonding interface are easily deformed, so the thickness accuracy of each layer of the carrier layer metal laminate substrate 1B may be reduced. In addition, if the rolling line load is high, the processing strain applied during bonding may increase.

The reduction rate during crimping is 30% or less, preferably 8% or less, and more preferably 6% or less. In addition, the thickness can remain unchanged before and after crimping, so the lower limit of the reduction rate is 0%.

In order to prevent the reduction of the bonding strength between the two due to the re-adsorption of oxygen to the surface of the extremely thin metal layer 13 or the intermediate layer 30, the bonding by roller compression is preferably carried out in a non-oxidizing atmosphere, such as a vacuum or an inert gas atmosphere such as Ar.

In addition, the carrier layer-attached metal laminate substrate 1B obtained by compression bonding can be further heat-treated as needed. By heat-treating, the strain of the ultra-thin metal layer 13 or the intermediate layer 30 can be eliminated, and the adhesion between the layers can be improved. When the heat treatment is performed at a high temperature for a long time, blisters may appear on the carrier layer 11 starting from the peeling layer 12, and the carrier layer 11 may be peeled off starting from the blisters, or conversely, the adhesion between the carrier layer 11 and the ultra-thin metal layer 13 is improved by mutual diffusion, etc., and the carrier layer 11 may be difficult to peel off. In addition, depending on the combination of the ultra-thin metal layer 13 and the intermediate layer 30, intermetallic compounds are generated at the interface, and there is a tendency for the adhesion (joining strength) to decrease. Therefore, the aforementioned heat treatment is performed at a temperature of 160°C to 300°C. More preferably, it is 180°C to 290°C. Alternatively, it is better not to perform heat treatment after rolling bonding. In addition, after the carrier layer 11 is peeled off/removed from the bonded carrier layer metal laminate substrate 1B, heat treatment can be performed within a temperature range where intermetallic compounds are not generated at the interface of the ultra-thin metal layer 13 and the intermediate layer 30.

Next, the metal layered substrate and its manufacturing method of the present invention are described. FIG4 is a diagram showing the manufacturing steps of the metal layered substrate of one embodiment of the present invention. The metal layered substrate 2 shown in FIG4 is roughly composed of an extremely thin metal layer 13 laminated on one surface of a low dielectric film 20 with a metal-containing intermediate layer 30 interposed therebetween. The metal layered substrate 2 is the same as the carrier layered metal layered substrate 1B shown in FIG2 except that the carrier layer 11 and the peeling layer 12 are not provided, and the structure of each layer is the same as the structure of each layer of the carrier layered metal layered substrate 1B. This metal layered substrate 2 can be obtained from a carrier layer metal layered substrate 1B. That is, as shown in FIG4 , a carrier layer metal layered substrate 1B is prepared (FIG4 (a)), and by peeling off the carrier layer 11 and the peeling layer 12 of the carrier layer metal layered substrate 1B together (FIG4 (b)), a three-layered metal layered substrate 2 can be obtained (FIG4 (c)).

The manufactured metal layer substrate 2 has an extremely thin metal layer 13 with a thickness of, for example, 0.5 μm or more and 10 μm or less, and can be used as a metal layer substrate (metal layer laminate) for manufacturing a flexible circuit board. In addition, the metal layer substrate of the present invention is a type of metal layer added by electroless plating, electroplating (for example, copper plating) or the like on the surface of the extremely thin metal layer 13 on the opposite side of the low dielectric film.

A printed circuit board with a fine circuit formed thereon can be obtained using the metal layered substrate 2. In the step of forming the circuit, the aforementioned additional metal layer may be formed only on the circuit portion. Specifically, a previously known method such as a modified semi-additive process (MSAP process) or a semi-additive process (SAP process) can be appropriately adopted to obtain a printed circuit board. For example, the non-circuit portion on the extremely thin metal layer 13 of the metal layered substrate 2 can be masked, and the uncovered portion can be copper-plated to form an additional metal layer, and the mask can be removed, and the extremely thin metal layer 13 hidden by the mask can be removed by etching to manufacture a printed circuit board. Furthermore, the "printed circuit board" of the present invention includes not only a laminate that forms a circuit, but also a laminate that carries electronic components such as ICs after the circuit is formed.

In the embodiments of the carrier layer metal laminate substrate 1A of FIG. 1 , the carrier layer metal laminate substrate 1B of FIG. 2 , and the metal laminate substrate 2 of FIG. 4 , the carrier layer metal foil 10 or the ultra-thin metal layer 13 is laminated on one surface of the low dielectric film 20, but the present invention is not limited thereto. That is, as required, the intermediate layer 30, the ultra-thin metal layer 13, the peeling layer 12, and the carrier layer 11 may also be provided on both surfaces of the low dielectric film 20. By using a metal laminate substrate having these layers of carrier layers on both sides of the low dielectric film 20, a flexible printed circuit board with circuits formed on both sides of the low dielectric film 20 can be obtained.

[Implementation example]

The present invention is further described below in detail based on embodiments and comparative examples, but the present invention is not limited to these embodiments.

(Implementation Example 1)

First, a carrier layer metal foil (MT18FL manufactured by Mitsui Mining & Smelting Co., Ltd.) was prepared, which had an ultra-thin copper layer of 1.5 μm thickness and a roughened particle layer and anti-rust layer on its surface through a release layer (organic release layer) on a carrier layer of 18 μm thickness composed of copper, and a liquid crystal polymer (LCP) film of 25 μm thickness as a low dielectric film. After the surface of the LCP film was activated by sputter etching, an intermediate layer composed of copper (thickness 40 nm) was formed by sputter plating. Next, the surfaces of the ultra-thin copper layer and the intermediate layer are bonded together by rolling to produce the target carrier layer metal laminate substrate. The line load during the press bonding is 1.5tf/cm, and the reduction rate due to surface activated bonding is 2.2%. After the rolling bonding, heat treatment is performed at 240°C.

(Example 2)

As the carrier layer metal foil, a carrier layer copper foil (MT18FL manufactured by Mitsui Mining & Smelting Co., Ltd.) was used. On the carrier layer composed of copper with a thickness of 18 μm, an extremely thin copper layer with a thickness of 1.5 μm and a roughened particle layer and an anti-rust layer on its surface were provided via an intermediate release layer (organic release layer). In addition, as a low dielectric film, a 100 μm thick LCP film was used. After the surface was activated by sputter etching, an intermediate layer composed of copper (thickness 40 nm) was formed by sputter plating. Next, the surfaces of the ultra-thin copper layer and the intermediate layer are bonded by rolling, and then heat treated to produce a carrier layer metal laminate substrate. The bonding conditions are shown in Table 1. In addition, the reduction rate caused by surface activated bonding is 2.5%.

(Examples 3 and 4)

Except for changing the bonding conditions as shown in Table 1, the same method as Example 2 is used to manufacture the carrier layer metal layer substrate. The reduction rates of Examples 3 and 4 are 2.5% and 3.5%, respectively.

(Example 5)

As a low dielectric film and an intermediate layer, a copper intermediate layer (thickness 40nm) was formed by sputtering on the surface of a 25μm thick LCP film as in Example 1. In addition, the metal layered substrate with a carrier layer was manufactured in the same manner as in Example 2 except that the bonding conditions were changed as shown in Table 1. The reduction ratio was 2.2%.

(Implementation Example 6)

As the carrier layer metal foil, a carrier layer copper foil (JXUT-III manufactured by JX Nippon Mining & Metals Corporation) was used. On the carrier layer composed of copper with a thickness of 18 μm, an extremely thin copper layer with a thickness of 3.0 μm and a roughened particle layer and an anti-rust layer on its surface were provided via a release layer (inorganic release layer). In addition, except that the bonding conditions were changed as shown in Table 1, the carrier layer metal layer substrate was manufactured in the same manner as in Example 5. The reduction ratio was 4.3%.

(Implementation Example 7)

As a low dielectric film and intermediate layer, a copper intermediate layer (thickness 40nm) was formed by sputtering on the surface of a 25μm thick low dielectric polyimide (modified polyimide, MPI) film, and a carrier layer metal stacking substrate was manufactured in the same manner as in Example 4. The reduction ratio was 2.2%.

(Implementation Example 8)

As the carrier layer metal foil, a carrier layer copper foil (test material 1) was used. On the carrier layer composed of copper with a thickness of 18 μm, an extremely thin copper layer with a thickness of 2.0 μm and only an anti-rust layer (without roughened particle layer) on its surface were provided via a release layer (inorganic release layer). In addition, except that the bonding conditions were changed as shown in Table 1, the carrier layer metal layer substrate was manufactured in the same manner as in Example 6. The reduction ratio was 2.2%.

(Implementation Example 9)

As the carrier layer metal foil, a carrier layer copper foil (test material 2) was used. On the carrier layer composed of copper with a thickness of 18 μm, an extremely thin copper layer with a thickness of 5.0 μm and only an anti-rust layer (without a roughened particle layer) on its surface were provided via a release layer (organic release layer). In addition, except that the bonding conditions were changed as shown in Table 1, the carrier layer metal layer substrate was manufactured in the same manner as in Example 8. The reduction ratio was 6.3%.

(Comparison Example 1)

The metal layered substrate with a carrier layer was manufactured in the same manner as in Example 5 except that the bonding conditions were changed as shown in Table 1. The reduction ratio was 2.2%.

(Comparison Example 2)

The metal layered substrate with a carrier layer was manufactured in the same manner as in Example 6 except that the bonding conditions were changed as shown in Table 1. The reduction ratio was 4.3%.

(Comparison Example 3)

The metal layered substrate with a carrier layer was manufactured in the same manner as in Example 5 except that the bonding conditions were changed as shown in Table 1. The reduction ratio was 2.2%.

(Comparison Example 4)

The metal layered substrate with a carrier layer was manufactured in the same manner as in Example 6 except that the bonding conditions were changed as shown in Table 1. The reduction ratio was 4.3%.

(Comparison Example 5)

First, prepare a carrier layer metal foil, which has an ultra-thin copper layer of 2.0 μm thickness and a roughened particle layer and an anti-rust layer on its surface through a release layer (organic release layer) on a carrier layer composed of copper with a thickness of 18 μm, and a carrier layer copper foil (MT18FL manufactured by Mitsui Mining & Smelting Co., Ltd.), and a liquid crystal polymer (LCP) film with a thickness of 25 μm as a low dielectric film. Then, the carrier layer copper foil and the LCP film are bonded by hot pressing to produce a carrier layer metal laminate substrate. The hot pressing conditions are shown in Table 2.

(Compare Examples 6 and 7)

The metal laminate substrate with a carrier layer was manufactured in the same manner as in Comparative Example 5 except that the conditions for the heat pressing were changed as shown in Table 2.

(Comparative Example 8)

First, prepare a carrier layer metal foil, which has an ultra-thin copper layer of 3.0 μm thickness and a roughened particle layer and an anti-rust layer on its surface through a release layer (inorganic release layer) on a carrier layer composed of copper with a thickness of 18 μm, and a carrier layer copper foil (JXUT-III manufactured by JX Nippon Mining & Metals Corporation), and a liquid crystal polymer (LCP) film of 25 μm thickness as a low dielectric film. Then, the carrier layer copper foil and the LCP film are bonded by hot pressing to produce a carrier layer metal laminate substrate. The conditions for hot pressing are shown in Table 2.

(Compare Examples 9 and 10)

The metal laminate substrate with a carrier layer was manufactured in the same manner as in Comparative Example 8 except that the conditions for the heat pressing were changed as shown in Table 2.

For the metal laminated substrate with carrier layer obtained in Examples 1 to 9 and Comparative Examples 1 to 10, the bonding strength between the ultra-thin copper layer and the low dielectric film, the peeling strength between the carrier layer and the ultra-thin copper layer, and the total thickness were measured. The measurement results are shown in Table 3.

As shown in Tables 1 and 3, when the heat treatment temperature is high (Comparison Examples 1 and 2) and when the heat treatment temperature is low (Comparison Examples 3 and 4), it is impossible to take into account both the low adhesion between the carrier layer and the ultra-thin copper layer and the high adhesion between the ultra-thin copper layer and the low dielectric film.

In addition, as shown in Tables 2 and 3, when the copper foil attached to the carrier layer is bonded to the low dielectric film by hot pressing, it is impossible to take into account both the low adhesion between the carrier layer and the ultra-thin copper layer and the high adhesion between the ultra-thin copper layer and the low dielectric film. In particular, in Comparative Examples 6, 7, 9, and 10, the low dielectric film deteriorates and becomes brittle, making it unsuitable as a metal layer substrate for forming a circuit. In addition, in Comparative Example 10, the carrier layer and the ultra-thin copper layer cannot be peeled off.

Furthermore, each peeled surface after the bonding strength measurement in Example 5 was observed using a scanning electron microscope (SEM) and surface element analysis using EDX was performed. The scanning electron microscope image is shown in Figure 5. The analysis results confirmed that there was no copper attached to the peeled surface on the LCP side of Example 5. In addition, a portion of the cohesive and damaged LCP was attached to the side of the extremely thin copper layer (the peeled surface was the intermediate layer), so it is obvious that the peeling was caused by both the internal destruction of the LCP and the interface peeling between the intermediate layer and the LCP.

(Examples 10 to 16)

By removing the carrier layer from the metal laminate substrate with a 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 roughened particle layer and an anti-rust layer is manufactured.

(Examples 17 and 18)

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

For the obtained metal layer substrates of Examples 10 to 18, the bonding strength, total thickness, and thickness of the ultra-thin copper layer between the ultra-thin copper layer and the low dielectric film were measured. The measurement results are shown in Table 4.

The metal layered substrates of Examples 10 to 16 are composed of an extremely thin copper layer, a roughened particle layer, an anti-rust layer, an intermediate layer (copper), and an LCP or MPI film. In addition, the metal layered substrates of Examples 17 and 18 are composed of an extremely thin copper layer, an anti-rust layer, an intermediate layer (copper), and an LCP. For these metal layered substrates, the element distribution state (Depth Profile) in the depth direction of the GDS or AES can be measured or the cross-section observation using a transmission electron microscope (TEM) can be used to identify the layered state of each layer.

In addition, circuit patterns can be formed on the extremely thin copper layer of the metal laminate substrate using an anti-etching agent, and fine circuits can be formed on the low-dielectric film using a modified semi-additive process (MSAP) or a semi-additive process (SAP).

All publications, patents, and patent applications cited in this specification are incorporated herein by reference in their entirety.

1A: Metal laminate substrate with carrier layer

10: Carrier layer metal foil

11: Carrier layer

12: Peel off layer

13: Extremely thin metal layer

20: Low dielectric film

Claims (16)

A carrier layer metal laminate substrate is a carrier layer metal foil formed by laminating at least three layers including a carrier layer, a peeling layer and an ultra-thin metal layer on at least one side of a low dielectric film. The bonding strength between the ultra-thin metal layer and the low dielectric film is greater than the peeling strength between the carrier layer and the ultra-thin metal layer. The peeling strength between the carrier layer and the ultra-thin metal layer is greater than 0.15N/cm and less than 0.5N/cm. The metal-laminated substrate with a carrier layer as claimed in claim 1 has one or more metal-containing intermediate layers between the low dielectric film and the extremely thin metal layer. A carrier layer metal laminate substrate as claimed in claim 2, wherein the intermediate layer comprises any metal or its alloy selected from the group consisting of copper, iron, nickel, zinc, chromium, cobalt, titanium, tin, platinum, silver and gold. A carrier layer metal laminate substrate as claimed in any one of claims 1 to 3, wherein the low dielectric film is a low dielectric polymer film selected from the group consisting of liquid crystal polymer, polyvinyl fluoride, polyamide and low dielectric polyimide. A metal laminate substrate with a carrier layer as recited in any one of claims 1 to 3, wherein the bonding strength between the ultra-thin metal layer and the low dielectric film is 2.0 N/cm or more. For a carrier layer metal laminate substrate as recited in any one of claims 1 to 3, the release layer is an organic release layer or an inorganic release layer. A metal laminate substrate with a carrier layer as recited in any one of claims 1 to 3, wherein the thickness of the ultra-thin metal layer is greater than 0.5 μm and less than 10 μm. A method for manufacturing a carrier layer metal laminate substrate is the method for manufacturing a carrier layer metal laminate substrate described in claim 2, comprising: preparing a low dielectric film and a carrier layer metal foil composed of at least three layers including a carrier layer, a peeling layer and an ultra-thin metal layer; sputtering the low dielectric film to form a thin film; After activating at least one side of the film, a step of sputtering a metal-containing intermediate layer on the aforementioned surface, a step of activating the surface of the aforementioned intermediate layer by sputtering, a step of activating the surface of the aforementioned ultra-thin metal layer by sputtering, and a step of rolling-bonding the aforementioned activated surfaces at a reduction rate of 0-30%. The manufacturing method of the metal laminate substrate with a carrier layer as claimed in claim 8, wherein the low dielectric film is a low dielectric polymer film selected from the group consisting of liquid crystal polymer, polyvinyl fluoride, polyamide and low dielectric polyimide. A method for manufacturing a metal laminate substrate with a carrier layer as claimed in claim 8 or 9, wherein after the rolling bonding, a heat treatment is performed at a temperature of not less than 160°C and not more than 300°C. A metal-layer substrate is provided, wherein an extremely thin metal layer is layered on at least one side of a low dielectric film with a metal-containing intermediate layer interposed therebetween, and the bonding strength between the low dielectric film and the extremely thin metal layer is greater than 2.0 N/cm. A metal laminate substrate as claimed in claim 11, wherein the intermediate layer comprises any metal selected from the group consisting of copper, iron, nickel, zinc, chromium, cobalt, titanium, tin, platinum, silver and gold, or an alloy thereof. A metal layer substrate as claimed in claim 11 or 12, wherein a coarsened particle layer containing any metal selected from the group consisting of Cu, Co and Ni or its alloy, and/or a rust-proof layer containing any metal selected from the group consisting of Cr, Ni and Zn or its alloy is deposited on the surface of the intermediate layer side of the extremely thin metal layer. For example, the metal layer substrate of claim 11 or 12, wherein the thickness of the ultra-thin metal layer is greater than 0.5μm and less than 10μm. A method for manufacturing a metal-layered substrate comprises laminating an extremely thin metal layer on at least one side of a low dielectric film with a metal-containing intermediate layer interposed therebetween, and comprising the step of peeling off the carrier layer of the metal-layered substrate with a carrier layer of claim 2. A printed circuit board is formed with a circuit in the middle layer and the extremely thin metal layer of any metal layer substrate of claim 11 to claim 14.

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