阅读说明：本技术 高频电路用表面处理铜箔及高频电路用表面处理铜箔的制造方法 (Surface-treated copper foil for high-frequency circuit and method for producing surface-treated copper foil for high-frequency circuit ) 是由 米切斯·罗曼 岱瓦仪夫·汤玛士 凯迪·兰仪雅 斯翠尔·迈克尔 于 2021-03-05 设计创作，主要内容包括：本发明涉及高频电路用表面处理铜箔及高频电路用表面处理铜箔的制造方法。本发明是一种表面处理铜箔,其与高频电路的绝缘基板有优异的粘着性,特别是即使在施加高温轧压加工的热负载下,也能够制造一种抑制起泡产生的覆铜层叠体。更具体而言,本发明是一种高频电路用表面处理铜箔,具有形成于厚度35μm以下的铜箔的耐热处理层,其中,该耐热处理层为包含铬、钼、锌以及镍的四级金属氧化物以及其化合物的膜。(The present invention relates to a surface-treated copper foil for high-frequency circuits and a method for producing a surface-treated copper foil for high-frequency circuits. The present invention provides a surface-treated copper foil which has excellent adhesion to an insulating substrate for a high-frequency circuit and, in particular, can produce a copper-clad laminate in which blister generation is suppressed even under a heat load applied by high-temperature rolling. More specifically, the present invention is a surface-treated copper foil for high-frequency circuits, comprising a heat-resistant treatment layer formed on a copper foil having a thickness of 35 μm or less, wherein the heat-resistant treatment layer is a film comprising a quaternary metal oxide of chromium, molybdenum, zinc and nickel and a compound thereof.)

1. A surface-treated copper foil for high-frequency circuits, which has a heat-resistant treated layer formed on a copper foil having a thickness of 35 μm or less,

the heat-resistant treatment layer is a film of a quaternary metal oxide including chromium, molybdenum, zinc, and nickel, and a compound thereof.

2. The surface-treated copper foil for high-frequency circuits as defined in claim 1, wherein the heat-resistant treatment layer has a plating weight of 0.1 to 18mg/m in terms of metal²10 to 45mg/m of chromium²30 to 70mg/m of molybdenum²And 10 to 30mg/m of zinc²Nickel (ii) is used.

3. A method for manufacturing a surface-treated copper foil for a high-frequency circuit, comprising the steps of:

a plating bath using a four-stage metal film comprising, in terms of metal, 0.2 to 6.0g/L of chromium, 1.0 to 9.0g/L of molybdenum, 1.0 to 8.0g/L of zinc, and 1.0 to 7.0g/L of nickel;

pH of 3 to 4 and current density of 0.5 to 5.0A/dm²Surface-treating a copper foil having a thickness of 35 μm or less under the condition of (1); and then

The surface-treated copper foil was left in air for 10 to 50 seconds.

Technical Field

The present invention relates to a surface-treated copper foil for high-frequency circuits, and more particularly, to a surface-treated copper foil having excellent adhesion to an insulating substrate for high-frequency circuits and excellent transmission characteristics in a high-frequency region.

Background

In recent years, with the popularization of information terminals such as smart phones, mobile PCs, and SNS (i.e., social network services and video websites), there has been an increasing demand for processing large amounts of data at high speed. In view of the above, high frequency signals for large capacity information transmission processing are being sought for mobile communication devices typically including cellular phones and electronic devices including computers that process data using networks. Nowadays, development using signals of GHz order is rapidly progressing, and therefore printed wiring boards for high-frequency circuits capable of coping with such high-speed signals are required.

When a printed wiring board for a high-frequency circuit is mounted, a copper-clad laminate to which a copper foil is adhered is used as an insulating substrate in consideration of dielectric loss of a high-frequency signal. For example, resins such as thermosetting polyphenylene ether and modified polyphenylene ether are used for some of the insulating substrates for high-frequency circuits. Such a copper-clad laminate having an insulating material and a copper foil bonded thereto requires a very high-temperature rolling process, and therefore, it is known that blistering (i.e., swelling) occurs at the time of high-temperature rolling. In this case, various surface-treated copper foils have been proposed for the purpose of improving the adhesion between the insulating substrate and the copper foil in order to suppress the occurrence of blisters (for example, patent documents 1 and 2).

[ Prior art documents ]

[ patent document ]

[ patent document 1] JP 2017-

[ patent document 2] JP 5764700B

[ patent document 3] JP 6294862B.

Insulating substrates for high-frequency circuits are being actively developed, and from now on, surface-treated copper foils that can sufficiently satisfy the adhesion to insulating substrates have been required every time a new insulating substrate is developed.

Disclosure of Invention

[ problems to be solved by the invention ]

The purpose of the present invention is to provide a surface-treated copper foil which has excellent adhesion to an insulating substrate for a high-frequency circuit, and in particular, which can produce a copper-clad laminate in which the occurrence of blistering is suppressed even when a heat load of high-temperature rolling is applied.

[ means for solving problems ]

The invention provides a surface-treated copper foil for high-frequency circuits, which is a heat-resistant treated layer having a copper foil with a thickness of 35 [ mu ] m or less, wherein the heat-resistant treated layer is a film comprising a quaternary metal oxide of chromium, molybdenum, zinc and nickel and a composite thereof.

The heat-resistant treatment layer of the present invention has a plating weight of 0.1 to 18mg/m in terms of metal²10 to 45mg/m of chromium²30 to 70mg/m of molybdenum²And 10 to 30mg/m of zinc²Nickel (ii) is used.

The method for manufacturing the surface-treated copper foil comprises the following steps: a plating bath for a four-stage metal film comprising, in terms of metal, 0.2 to 6.0g/L of chromium, 1.0 to 9.0g/L of molybdenum, 1.0 to 8.0g/L of zinc, and 1.0 to 7.0g/L of nickel; at a pH of 3 to 4 and a current density of 0.5 to 5.0A/dm²Under the conditions of (1), a copper foil having a thickness of 35 μm or less is subjected to surface treatment.

[ Effect of the invention ]

The surface-treated copper foil of the present invention has excellent adhesion to an insulating substrate for high-frequency circuits, and therefore, when the copper foil is rolled at a high temperature, particularly when subjected to a heat load of 290 ℃ for 1 hour, a copper-clad laminate in which the occurrence of blistering is suppressed can be produced. The surface-treated copper foil of the present invention can be produced efficiently by forming a heat-resistant treatment layer, which is a film containing a quaternary metal oxide and a compound thereof, using a plating bath for a quaternary metal film containing chromium, molybdenum, zinc, and nickel at a specific concentration.

Drawings

FIG. 1 is a photograph showing a comparison for evaluating the occurrence of foaming, and

fig. 2 is a graph showing the results of XPS analysis performed on the surface-treated copper foil of this example.

Detailed Description

The present invention will be described in detail below. In the present invention, a heat-resistant treatment layer is formed on the surface of a copper foil having a thickness of 35 μm or less, and the heat-resistant treatment layer is a film containing a quaternary metal oxide of chromium, molybdenum, zinc, and nickel, and a compound thereof. In this case, even when the surface-treated copper foil is bonded to an insulating substrate for high-frequency circuits which is required to be subjected to high-temperature rolling to form a copper-clad laminate and heat treatment is performed at 290 ℃ for 1 hour, no blister or protrusion is generated.

In the surface-treated copper foil of the present invention, the plating weight of the quaternary metal film constituting the heat-resistant treated layer is more preferably 0.1 to 18mg/m in terms of metal²10 to 45mg/m of chromium²30 to 70mg/m of molybdenum²And 10 to 30mg/m of zinc²Nickel (ii) is used. If the plating weight is less than the lower limit of each element, blistering or bulging is likely to occur, and if the plating weight exceeds the upper limit of each element, high-frequency characteristics are deteriorated.

The heat-resistant treated layer is formed of a film of a quaternary metal oxide of chromium, molybdenum, zinc and nickel and a compound thereof. The mixed oxide of the four metals raises the melting point of the heat-resistant treatment layer itself. Further, in the production of the quaternary metal oxide and the compound thereof, the film is easily and strongly adhered to the chromate treatment layer and the silane coupling treatment layer.

The surface-treated copper foil of the present invention may use an untreated electrolytic copper foil. A copper foil having a thickness of 35 μm or less is used. In general, the surface roughness is more preferably Rzjis 1.0 μm or less, and the tensile strength is more preferably 300 to 400N/mm²。

In the surface-treated copper foil of the present invention, it is more preferable to store copper fine particles in advance, perform copper seal plating to fix the copper fine particles to the surface of the copper foil, and form a roughened layer on the surface of the untreated electrolytic copper foil, that is, the bonding surface bonded to the insulating substrate. Then, it is more preferable to form the heat-resistant treated layer of the present invention, which is a film containing chromium, molybdenum, zinc, and a quaternary metal oxide of nickel and a compound thereof, on the surface of the roughened layer.

When the heat-resistant treated layer of the surface-treated copper foil of the present invention is formed, it is preferable to use a plating bath for plating which contains a quaternary alloy of 0.2 to 6.0g/L of chromium, 1.0 to 9.0g/L of molybdenum, 1.0 to 8.0g/L of zinc, and 1.0 to 7.0g/L of nickel in terms of metal.

Plating baths for the plating of quaternary alloys, e.g. with reasonable incorporation of CrO in the bath₃Form of chromium, Na₂MoO₄ ^.2H₂Molybdenum, ZnSO in O form₄ ^.7H₂Zinc in the form of O, and NiSO₄ ^.6H₂Nickel in the form of O. Further, in order to increase the conductivity of the plating bath, it is more preferable to add sodium sulfate. The content of the compound in the plating bath is more preferably 30 to 50 ppm. More preferably, a diluted solution of sodium hydroxide and sulfuric acid is used as the pH adjuster. More preferably, a diluted solution of sodium hydroxide and sulfuric acid is used as the pH adjuster.

The plating conditions of the plating bath for plating the four-stage alloy are more preferably pH3 to 4 and the current density is 0.5 to 5.0A/dm²。

In the surface-treated copper foil of the present invention, it is preferable to form a heat-resistant treated layer formed of a film of a quaternary metal of chromium, molybdenum, zinc and nickel, oxidize the film by leaving the film in the air for 10 to 50 seconds, and then form a chromate treated layer for the purpose of corrosion prevention. The chromium content of the plating weight in the chromate treatment layer is preferably 3 to 5mg/m in terms of metal²。

In the surface-treated copper foil of the present invention, it is more preferable to form a silane coupling agent-treated layer in order to improve the resistance to moisture absorption deterioration when forming a printed wiring board. Suitable silane coupling agents include epoxy, amine, methacrylic, vinyl, mercapto, and acrylic, and more preferably epoxy, amine, and vinyl.

[ examples ]

The examples are described below. The copper foil used in this example was an electrolytic copper foil having a thickness of 18 μm, which was produced using a titanium electrolytic drum, a cathode and an insoluble anode, a copper sulfate electrolyte solution of a predetermined concentration, and predetermined electrolysis conditions. The surface roughness of the M surface side of the electrolytic copper foil was 1.0. mu.m Rzjis, and the surface roughness of the S surface side was 1.0. mu.m Rzjis. The term M surface is a surface on the non-drum surface side of the electrolytic drum, and S surface is a surface on the drum surface side of the electrolytic drum. Note that this electrolytic copper foil was also used in the following comparative examples.

A roughened layer was formed on the surface M of the electrolytic copper foil under the following conditions.

And (3) copper particle treatment:

copper seal plating:

after the formation of the roughened layer, a heat-resistant treatment layer (which is a film of a quaternary metal oxide of chromium, molybdenum, zinc, and nickel, and a compound thereof) was formed under the following conditions. The heat-resistant treated layer was subjected to four-stage metal film plating described below and left in air for 30 seconds.

Plating conditions of the four-stage metal film:

plating bath composition

After the heat-resistant treatment layer was formed, the plating weight of each metal in the heat-resistant treatment layer was measured and shown below.

Plating weight:

after the heat-resistant treatment layer was formed, a chromate treatment layer was formed under the following conditions.

Chromate treatment conditions:

after the formation of the chromate treatment layer, a silane coupling agent treatment layer was formed using the following conditions, and the surface-treated copper foil of the present example was produced.

Commercially available amine-based silane coupling agents

Drying conditions 85 ℃ for 10 seconds

Comparative example

A surface-treated copper foil having a roughened layer, a zinc-plated layer, a chromate-treated layer, and a silane coupling agent-treated layer formed in this order on the M surface of an electrolytic copper foil was prepared as a comparative example. The processing conditions except for the zinc plating layer were the same as in the above examples. The galvanized layer was treated under the following conditions.

And (3) galvanizing conditions:

plating bath composition

ZnSO₄·7H₂O Zn 0.8g/L (by metal)

Current density 2A/dm²

Plating time 2 seconds

The plating weight of each element of the surface-treated copper foil in this comparative example was measured and shown below.

Plating weight:

Zn 20mg/m²

Cr 4mg/m²

< evaluation of occurrence of foaming >

The surface-treated copper foils of examples and comparative examples were evaluated for blistering during high-temperature heat treatment using two prepregs for high-frequency circuits. MEGTRON 6 manufactured by Panasonic was used as prepreg A, and DS-7409-DV manufactured by Korea mountain electronics was used as prepreg B.

The rolling conditions of these prepregs:

the copper-clad laminate obtained under the above rolling conditions was processed into a size of 5cm × 5cm, and then heat-treated in an oven at 290 ℃ for 1 hour. For reference purposes, fig. 1 shows a comparison photograph for evaluation of blister occurrence (prepreg a). In FIG. 1, the left side shows an example in which no foaming occurred, and the right side shows a comparative example in which foaming occurred.

In the surface-treated copper foils of the examples, no occurrence of blistering was observed in both prepregs. On the other hand, in the surface-treated copper foil of the comparative example, the occurrence of blistering was observed in both prepregs. From the results, it was found that the formation of bubbles was successfully suppressed even when a heat load of 1 hour and a high temperature of 290 ℃ was applied to the copper-clad laminate by using a copper-clad laminate in which a heat-resistant treated layer composed of a quaternary metal oxide of chromium, molybdenum, zinc and nickel and a compound thereof was formed on the surface of a copper foil and a prepreg for a high-frequency circuit was combined.

Next, the results of X-ray photoelectron spectroscopy analysis performed on the surface-treated copper foil of the above example will be described. The object of analysis was a surface-treated copper foil on which a chromate treatment layer was formed under the same conditions as in the above examples, but which was not subjected to silane coupling treatment. The XPS analyzer used PHI Quantum 2000 (manufactured by ULVAC-PHI). The XPS analyzer has an X-ray source of Al-K alpha with a beam diameter of 10 to 200 μm and then uses an acceleration to 2KeV (corresponding to 10nm/min SiO)₂Sputtering rate of (b) to perform sputter etching on the surface of the surface-treated copper foil to perform analysis in the depth direction. The results are shown in FIG. 2.

Fig. 2 plots the atomic concentrations of the respective elements in the depth direction obtained by the XPS analyzer. The horizontal axis represents depth, and the horizontal axis value corresponds toSilicon oxide (SiO) sputtered with Ar ions accelerated to 2KeV₂) Of the depth of (c). From the results of fig. 2, it was confirmed that four metals of chromium, molybdenum, zinc, and nickel were mixed. And it was confirmed that a small amount of Cr was present in the depth direction of the film. The peak of binding energy with oxygen obtained by XPS analysis was further found to be mixed in the form of oxide since all four metals were placed in the air.

It is presumed from the results of XPS analysis that the surface-treated copper foil of the present example realizes characteristics such as adaptability to high-temperature heat treatment by forming a heat-resistant treatment layer which is a film composed of a quaternary metal oxide of chromium, molybdenum, zinc and nickel and a compound thereof and mixing a plurality of oxides in the film, and therefore, the surface-treated copper foil has an increased melting point and contributes to strong bonding between a chromate treatment layer and a silane coupling agent treatment layer formed after heat-resistant treatment.