JP2002198625A - Method for manufacturing copper foil with resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a copper foil with resin of uniform thickness at a low cost. SOLUTION: A 9 μm-thick copper foil with resin is obtained by forming a 20 to 200 nm-thick oxide film in a surface wherein at least one copper foil of a pair of copper foils is in contact with the other copper foil, performing cold rolling so that one copper foil is 9 μm or less thick with a pair of copper foils laminated, applying a thermosetting resin composition to a surface of a 9 μm-thick copper foil, making a thermosetting resin composition a half-setting B stage mode as required, and peeling off a pair of copper foils. A copper foil of a uniform thickness can be obtained by carrying out cold rolling with a pair of copper foils laminated. Peeling property is improved by forming a 20 to 200 nm-thick oxide film in an interface between a pair of copper foils before cold rolling.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a resin-coated copper foil used for a printed wiring board, and more particularly to a resin capable of inexpensively producing a resin-coated copper foil having a uniform thickness of the copper foil. The present invention relates to a method for producing a coated copper foil.

[0002]

2. Description of the Related Art As a conventional method for producing a copper foil with a resin,
For example, there is one disclosed in JP-A-10-146915.

In this method, an ultra-thin copper foil having a thickness of 9 μm or less is formed on a carrier (reinforcing material) such as aluminum or copper by plating, and the surface of the copper foil with the carrier is cured by light and heat. The present invention is to produce a resin-coated copper foil in which a conductive resin composition is applied and the resin composition is B-staged by heat as required. Thereafter, a copper foil with a resin is arranged on one or both sides of the printed wiring board, and the printed wiring board is manufactured by being continuously or discontinuously bonded under pressure and heating.

According to this method, since the copper foil is formed on the carrier, the transfer to the coating step becomes easy even with an extremely thin copper foil. In addition, since a copper foil having a thickness of 9 μm or less is used, an etching time for forming a circuit pattern on the copper foil can be reduced, and the etching accuracy is improved.
The density of the printed wiring board can be increased.

There is also known a method of using a copper foil having a thickness of 12 μm or more and etching the same to obtain a copper foil having a thickness of 9 μm or less.

[0006]

However, according to the conventional method for producing a resin-coated copper foil, since a very thin copper foil is formed by plating, there is a problem that variations in thickness and minute pinholes cannot be avoided. is there. In addition, the use of a technique called plating requires the use of a large amount of chemicals.
It is necessary to invest a large amount of equipment costs for waste liquid treatment.

Further, in the method of using a copper foil of 12 μm or more and etching the same, not only is it technically difficult to perform uniform etching, but also an extra step is required.
It is extremely disadvantageous in terms of cost.

Accordingly, an object of the present invention is to provide a method for producing a resin-coated copper foil, which can produce a resin-coated copper foil having a uniform thickness of the copper foil at low cost.

[0009]

According to the present invention, in order to achieve the above object, an oxide film having a thickness of 20 to 200 nm is formed on a surface of at least one of a pair of copper foils in contact with the other copper foil. Then, the pair of copper foils are cold-rolled in a stacked state, a thermosetting resin is applied to a surface of at least one of the copper foils of the pair of copper foils, and the pair of copper foils is peeled off. A method for producing a resin-coated copper foil is provided.
By cold rolling in a state where a pair of copper foils are overlapped, a copper foil having a uniform thickness can be obtained. Before cold rolling,
By forming an oxide film having a thickness of 20 to 200 nm on the interface between the pair of copper foils, the peelability is improved.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for manufacturing a resin-coated copper foil according to a first embodiment of the present invention will be described. First, an oxide film having a thickness of 20 to 200 nm is formed on a surface of at least one of the pair of copper foils that contacts the other copper foil. Next, a pair of copper foils are overlapped and cold-rolled so that at least one of the copper foils has a thickness of 9 μm or less. Next, 9 μm
A thermosetting resin composition is applied to the surface of the copper foil as described below, and the thermosetting resin composition is converted into a semi-cured B stage as needed. Next, the pair of copper foils is peeled off. Thus, a resin-coated copper foil in which a resin layer is formed on a copper foil of 9 μm or less is manufactured.

As the copper foil, an electrolytic copper foil or a rolled copper foil can be used. When using an electrolytic copper foil, if the surface roughness Rz is about 6 μm as a material for rolling,
Although it depends on the degree of rolling, the surface roughness Rz is 3 after cold rolling.
A moderate roughness of not more than μm remains, and good adhesion to the resin is obtained. When a rolled copper foil is used, its surface is a smooth surface to which the surface of the roll is transferred. If this smooth surface does not have sufficient adhesiveness, perform normal electrodeposition roughening or mechanical roughing such as shot blasting before applying the resin, or remove the surface of the rolling roll. The surface may be roughened by rolling to an appropriate roughened surface.

An oxide film having a thickness of 20 to 200 nm is formed on one copper foil surface before the pair of copper foils are stacked, because if the stacked surface is a clean copper surface, it is cooled after rolling. This is because they are pressed against each other, and the peelability is extremely deteriorated. Oxide film thickness is 20nm
If it is less than 200 nm, there is no effect. On the contrary, if it exceeds 200 nm, the oxide film is peeled off, and the effect is lost. The thickness of the oxide film is represented by a value measured by a cathode reduction method described in a document (edited by the Japan Copper and Brass Association; copper product data book (1997) 125). This is the same for the values shown in the following embodiments. The method for forming the oxide film is not particularly limited, such as a method of heating in an oxidizing atmosphere such as the air, a method of treating with a chemical such as a blackening treatment, and the like. Further, when a resin such as a polyimide resin is directly applied as a resin on the copper foil, the bonding temperature increases, so that oxidation of the copper foil progresses and adversely affects the adhesiveness. Therefore, in such a case, it is preferable to apply a single-layer or multi-layer plating of Ni, Zn, Sn, or the like to the copper foil in advance, or further perform a chromate treatment.

The resin composition to be coated is not particularly limited, but may be an epoxy resin, a polyimide resin,
A resin composition containing a polyfunctional cyanate compound or the like is suitable. As a coating method, the varnish-shaped resin composition may be coated using a coating machine such as a roll coater or a curtain coater, or a film-shaped resin composition may be used as a usual so-called laminator. It can be easily applied by bonding using The coated resin may be completely cured and used for a single-layer printed wiring board, or it may be used for a multilayer printed wiring board if it is kept in a so-called semi-cured B stage.

According to the first embodiment, one of the pair of copper foils serves as a carrier. Therefore, by taking the copper foil directly to the resin coating process, the manufacturing process with extremely high workability can be achieved. It can be. The copper foil used and peeled off as a carrier may be used as scrap for recycling. In addition, since the method of double rolling is employed, a copper foil having an extremely uniform thickness can be obtained. In the copper plating method, it is technically difficult to maintain in-plane thickness uniformity, particularly when the area is large, but in the rolling method, uniformity can be easily achieved by using an X-ray or radiation thickness gauge. Can be maintained. In addition, since the copper surface on one side has been subjected to an oxidation treatment before overlapping, the peelability after rolling is extremely good. Furthermore, when bonding the resin in the state of overlapping after rolling,
It can be peeled off well even after receiving the heating together with the pressure. In addition, it can be used alone as a fine pattern printed wiring board, or as a laminated material of a build-up multilayer printed wiring board formed by multilayering on a printed wiring board serving as a core.

Next, a method for manufacturing a resin-attached copper foil according to a second embodiment of the present invention will be described. First, a thickness of 20 to 200 n is applied to the surface of at least one of the pair of copper foils.
An oxide film of m is formed. Next, a pair of copper foils are overlapped and cold worked so that the thickness of each of the copper foils is 9 μm or less. Next, a thermosetting resin composition is applied to the surfaces of both copper foils, and the thermosetting resin composition is converted into a semi-cured B stage as needed. Next, the pair of copper foils is peeled off. As a result, a pair of resin-coated copper foils each having a resin layer formed on a copper foil of 9 μm or less is manufactured.

According to the second embodiment, each of the pair of copper foils can be made of resin-coated copper foil, so that the manufacturing cost can be lower than that of the first embodiment.

[0017]

Embodiments Embodiments 1 and 2 of the present invention will be described. <Example 1> Table 1 shows the test results of the peelability in Example 1.

[Table 1] Two copper foils having a thickness of 100 μm and 15 μm were prepared. The copper foil having a thickness of 100 μm was subjected to atmospheric oxidation heating to form an oxide film having a film thickness shown in Table 1, and then a copper foil having a thickness of 15 μm was formed. The foil was superimposed and cold rolled so that a copper foil having a thickness of 15 μm became 5 μm. Table 1 shows the results of the peelability of both after the cold rolling was completed. After performing the degreasing and cleaning of the surface of the copper foil after the cold rolling, a thermosetting resin composition (for example, an interlayer insulating material TBR-27 manufactured by Tamura Corporation) is roll-coated on the surface of the copper foil having a thickness of 5 μm. wet
Was applied to a thickness of 70 μm, and the solvent component was volatilized and dried in a drying oven at 120 ° C. to obtain a copper foil with resin. next,
The copper foil with resin was peeled off. Table 1 shows the results of the peelability at this time. What was successfully peeled off (N in Table 1)
o. With respect to (3, 4, 5), the resin surface of the resin-coated copper foil is the same as the substrate circuit surface on both surfaces of the substrate having the heat resistance grade FR-4 of the American Electrical Manufacturers Association in which the predetermined circuit is formed on both surfaces. Layered so that it touches, pressure 1 kg / cm ² , temperature 18
Hot pressing was performed for 1 hour at 0 ° C. to obtain a multilayer wiring board.

According to the first embodiment of the present invention, when an oxide film having a thickness of 20 to 200 nm is formed
It was found that the peelability was extremely good even after rolling and after being heated. Further, since the two sheets are cold-rolled, a copper foil having a thickness of 9 μm or less can be easily obtained, and the copper foil on one side serves as a carrier.
In the resin coating step, the handling was easy, and workability equivalent to that of a conventional copper foil with resin composed of a copper foil of 12 μm or more could be achieved.

Example 2 An oxide film having a thickness of 100 nm was formed on one of the two copper foils having a thickness of 15 μm by heating in air, and then the two copper foils were overlapped. Cold rolling was performed so that the copper foil became 7 μm. After the surfaces of both copper foils were degreased and cleaned, the resin composition shown in Example 1 was applied to the surfaces of the two copper foils in a wet state to a thickness of 70 μm using a roll coater, and then 120 The solvent component was volatilized and dried in a drying oven at ℃ to obtain a pair of resin-attached copper foils. Next, the pair of superposed copper foils was peeled off. Peelability was extremely good as in Example 1. Example 1 was used to peel off each of the resin-coated copper foils.
Was laminated on a substrate having heat-resistant grade FR-4 from the American Electrical Manufacturers Association to obtain a multilayer wiring board.

According to the second embodiment of the present invention, when an oxide film having a thickness of 20 to 200 nm is formed at the interface of two sheets,
As in Example 1, the peelability was good.

[0021]

As described above, according to the method for producing a resin-coated copper foil of the present invention, the thickness of the copper foil with a thickness of 20 to
Since a 200-nm-thick oxide film is formed and cold-rolled in a state where a pair of copper foils are superposed, a copper foil with a resin having a thickness of 9 μm or less can be manufactured at low cost with good workability. . Moreover, the thickness of the copper foil is uniform because it is rolled, there is no pinhole due to plating, and it can be used alone as a printed wiring board, or after forming a wiring pattern by the photoresist method and printing it by the additive method. Even when used as a wiring board, a printed wiring board having a fine pattern can be obtained. Further, a printed wiring board having a fine pattern can be obtained similarly even when used as a laminate material of a build-up multilayer printed wiring board.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Noboru Hagiwara 5-1-1, Hidakacho, Hitachi City, Ibaraki Prefecture Within Hitachi Cable Research Institute, Ltd. (72) Muneo Kodaira 5, Hidakacho, Hitachi City, Ibaraki Prefecture No. 1-1 F-term in Hitachi Cable, Ltd. R & D Laboratory (Reference) 4D075 AE19 BB05X BB27Z CA48 DA04 DB06 DC19 EA19 EB33 EB35 EB39 4E351 AA01 AA03 AA04 BB01 DD04 GG20 4F100 AA17C AB17B AB33B AK01ABABABABAE BABAE BABAE BABA BAH EJ082 EJ121 EJ172 EJ312 EJ372 GB43 JB13A JL02 JL05 JL14 JM02C YY00B YY00C

Claims (4)

[Claims] 1. An oxide film having a thickness of 20 to 200 nm is formed on a surface of at least one of a pair of copper foils that contacts the other copper foil, and the pair of copper foils is cold-laminated. Rolling, coating a thermosetting resin on the surface of at least one of the copper foils, and peeling off the pair of copper foils. 2. The method for producing a resin-coated copper foil according to claim 1, wherein the step of applying the thermosetting resin includes a step of converting the thermosetting resin into a semi-cured B-stage. 3. The method according to claim 1, wherein the cold rolling is performed so that at least one of the pair of copper foils has a thickness of 9 μm or less. . 4. The cold rolling is performed so that each of the pair of copper foils has a thickness of 9 μm or less, and the thermosetting resin is coated on both surfaces of the pair of copper foils. The method for producing a resin-coated copper foil according to claim 1, wherein: