JP3300160B2 - Copper foil processing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for treating a copper foil used for producing a copper-clad laminate or the like.

[0002]

2. Description of the Related Art A copper-clad laminate for a printed circuit is formed by laminating a copper foil on a paper-phenol resin-impregnated substrate or a glass-epoxy resin-impregnated substrate by heating and pressing, and etching the circuit. By forming a net and mounting elements such as a semiconductor device on the net, a board for electronic equipment is manufactured. In these processes, the copper foil is required to have various performances because adhesion to a base material, heating, immersion in an acid or an alkaline solution, application of a resist ink, soldering, and the like are performed. For example,
The side which is usually referred to as the M surface (roughened surface, the same applies hereinafter) is required to be mainly adhered to the substrate, chemical resistance, and the like, and the normal S surface opposite to the M surface is required. On the side referred to as a surface (glossy surface, the same applies hereinafter), heat resistance, moisture resistance and the like are mainly required. In order to satisfy these demands, a brass layer forming treatment is performed on the M surface of the copper foil (Japanese Patent Publication No. 51-35711).
JP-A-54-6701), chromate treatment, coating of zinc or a mixture of zinc and chromium groups comprising zinc oxide and chromium oxide on both surfaces of M and S (Japanese Patent Publication No. Sho.
No. 8-7077). By the way, in recent years, the demand for miniaturization of printed wiring boards has been increasing more and more, and in order to cope with the improvement in etching accuracy accompanying this, a further lower surface roughness (low profile) is required on the M surface. . However, on the other hand, the surface roughness of the M surface has an anchor effect in bonding to the base material. Therefore, there is a trade-off relationship between the requirement of the low profile on the M surface and the improvement of the adhesive force. It is necessary to compensate for the reduction of the anchor effect by the improvement of the adhesive force by another means.

[0003] A method of applying a silane coupling agent to the M surface has also been proposed as a means for increasing the adhesive force or as a means for increasing the adhesive force accompanying the low profile described above (Japanese Patent Publication No. 2-19994, 63-1
83178, JP-A-2-26097). Examples of this type of silane coupling agent include vinyltriethoxysilane, vinyltris (2-methoxyethoxy) silane, 3-methacryloyloxypropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 2- (3,4- Epoxycyclohexyl) ethyltrimethoxysilane, N-2- (aminoethyl) -3-aminopropyltrimethoxysilane, N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane,
Known are 3-aminopropyltriethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-chloropropyltrimethoxysilane and the like ["Latest technology of polymer additives" 120-134, CMC, 198.
Published on January 6, 2008].

[0004]

By using a coupling agent as described above, the adhesiveness can be improved to some extent. However, as printed circuits are becoming more and more recent, the characteristics required for the copper foil for printed circuits used are becoming increasingly severe. An object of the present invention is to provide a copper foil surface treatment method that can respond to such a demand, that is, in particular, improves the adhesiveness between the copper foil surface and the resin substrate, and improves the rate of peel deterioration after boiling. Things.

[0005]

Means for Solving the Problems As a result of diligent studies, the present inventor has found a treatment method in which a silane coupling agent is applied to a surface of a copper foil which has been subjected to a rust-preventive treatment, after a hydroxyl group has been imparted thereto. . That is, the present invention forms a rust-proofing layer on the surface of a copper foil , and then imparts a hydroxyl group to the rust-proofing layer on the surface of the copper foil subjected to the rust-proofing treatment, and further comprises a coupling agent. The gist of the present invention is a method for treating a copper foil, which is characterized by performing a coating reaction. As the rust prevention treatment used in the present invention, a treatment method known for copper foil can be applied. For example, a chromate treatment, a zinc-chromium group mixture coating treatment, or a combination thereof can be applied. In the case of chromate treatment by immersion, particularly preferred conditions are as follows.

K ₂ Cr ₂ O ₇ : 1 to 5 g / l pH: 2.5 to 4.5 Temperature: 40 to 60 ° C. Time: 3 to 8 seconds In the case of electrolytic chromate treatment, particularly preferred conditions are as follows. is there. K ₂ Cr ₂ O ₇ (or Na ₂ Cr ₂ O ₇ , CrO ₃ ):
0.2 to 20 g / l Acid: phosphoric acid, sulfuric acid, organic acid pH: 1.0 to 3.5 Temperature: 20 to 40 ° C Current density: 0.1 to 5 A / dm ² hours: 0.5 to 5 seconds In addition, the zinc-chromium group mixture coating treatment forms a mixed coating layer of chromium oxide and zinc or zinc oxide. As a plating bath, for example, K ₂ Cr ₂ O ₇ , Na ₂
Bichromate such as Cr ₂ O ₇ or at least one such as CrO ₃
Species and zinc or a water-soluble zinc salt, such as ZnO or Zn
A mixed aqueous solution of at least one of SO ₄ .7H ₂ O and the like and an alkali hydroxide is used. Particularly preferred plating bath compositions and electrolysis conditions in this case are as follows. K ₂ Cr ₂ O ₇ (or Na ₂ Cr ₂ O ₇ , CrO ₃ ): 2
To 10 g / l NaOH or KOH: 10~50g / l ZnO or ZnSO ₄ · 7H ₂ O: 0.05~10g
/ L pH: 7 to 13 Bath temperature: 20 to 80 ° C Current density: 0.05 to 5 A / dm ² hours: 5 to 30 seconds Anode: Pt-Ti plate, stainless steel plate, etc. The following conditions are also preferable.

K ₂ Cr ₂ O ₇ : _{2 to} 10 g / l Zn: 0.1 to 0.5 g / l pH: 3.5 to 5 Bath temperature: 40 to 70 ° C. Current density: 0.1 to 0.5 A / Dm ² hours: 1 to 3 seconds The above rust-proofing treatment of the copper foil surface can also be performed via a barrier layer made of zinc, zinc alloy, tin or tin alloy or the like on the copper foil surface. In the treatment method of the present invention, after the above rust prevention treatment, a hydroxyl group is provided to the formed rust prevention treatment layer.

The hydroxyl group can be imparted by subjecting the rust-proofed copper foil to a heat treatment in the presence of steam or immersing it in boiling water. The rust-proofed copper foil is treated with N
It can also be carried out by immersion in a solution or dispersion of a, Li, Si, Zr or Ti metal alkoxide, or by applying and drying these solutions on the surface. In this case, the metal hydroxide formed by hydrolyzing the metal alkoxide is bonded to the rust-proofing layer on the copper foil surface. The hydroxyl group can also be provided by treating the rust-preventive layer on the copper foil surface with an alkali. As such an alkali, sodium hydroxide, potassium hydroxide, or the like can be used, and the alkali can be obtained by immersing or applying a copper foil in these solutions.

Next, in the treatment method of the present invention, a coupling agent is applied to the surface of the copper foil after introducing a hydroxyl group. As the coupling agent, a silane coupling agent is preferable. For example, vinyltriethoxysilane, vinyltris (2-methoxyethoxy) silane, 3-methacryloyloxypropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 2- ( 3,4-epoxycyclohexyl) ethyltrimethoxysilane, N-2-
(Aminoethyl) -3-aminopropyltrimethoxysilane, N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, 3-aminopropyltriethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, Examples include 3-mercaptopropyltrimethoxysilane, 3-chloropropyltrimethoxysilane, imidazolesilane, tetraethoxysilane and the like.

The coupling agent may be directly applied to the surface of the copper foil as it is. However, the coupling agent may be added in an amount of 0.001 to 20% by weight with an alcohol such as water, ethanol or methanol, or a solvent such as acetone, ethyl acetate or toluene. , Preferably 0.0
It is simple and preferable to dilute the solution so as to have a concentration of 1 to 6% by weight and dipping a copper foil in this solution. If the amount is less than 0.001% by weight, the effect of improving the peel strength after boiling is small, and if it exceeds 20% by weight, the effect is saturated and the solubility deteriorates. It should be noted that a small amount of an acid such as acetic acid or hydrochloric acid can be added to the coupling agent solution to promote the hydrolysis of the coupling agent. Since the hydroxyl group is bonded to the copper foil surface via the rustproofing layer, the coupling agent can bond to the copper foil surface by reacting with the hydroxyl group. Then the copper foil is dried. A copper-clad laminate can be obtained by a conventional method using the thus obtained copper foil treated by the treatment method of the present invention. That is, a copper-clad laminate can be obtained by laminating a plurality of resin-impregnated base materials such as a glass-epoxy resin, further laminating a treated copper foil thereon, and applying heat and pressure to laminate.

[0011]

【Example】

Example A brass layer (thickness: 10 to 20 mg / dm ² , Zn / Cu =) was formed on the roughened surface of an electrolytic copper foil (25 cm × 25 cm × 33 μm).
After forming 3/7), a zinc-chromium group mixture is further plated (thickness: 40 to 50 μg / dm ² as Cr, Z
n was 120 to 160 μg / dm ² ) to form a rust preventive layer. Then, the rust-proofed copper foil was placed in boiling water for 1 hour.
Hydroxyl groups were provided on the surface of the copper foil via a rust preventive layer by immersion for a time and surface treatment. Furthermore, it was immersed in a 0.4% by weight aqueous solution of 3-glycidoxypropyltrimethoxysilane to perform a coupling agent treatment. After the treatment, the copper foil was hung with a clip to remove excess liquid, and then dried in a dryer at 100 ° C. for 30 minutes to obtain a surface-treated copper foil.

Comparative Example 1 A surface-treated copper foil was obtained in the same manner as in the example, except that the boiling water treatment (hydroxyl group addition) was not performed. Comparative Example 2 A surface-treated copper foil was obtained in the same manner as in Example except that the coupling agent treatment was not performed. Comparative Example 3 A surface-treated copper foil was obtained by performing only rust prevention treatment without performing boiling water treatment and coupling agent treatment in the example.

Comparative Example 4 A surface-treated copper foil was obtained in the same manner as in the example except that no rust preventive layer was formed. These Examples and Comparative Examples 1 to
The roughened surface of the surface-treated copper foil obtained in 4 was adhered to a substrate in which a glass fiber cloth was impregnated with an epoxy resin to obtain a copper-clad laminate. The normal peel strength of the copper clad laminate was measured by the method specified in JIS C6481. The copper foil of this copper-clad laminate was etched to form a circuit of 0.1 mm width and 10 circuits of 0.2 mm width, and the peel strength after boiling for 2 hours was measured. And the difference from the peel strength was determined, and the% obtained by dividing the difference by the latter was determined as the deterioration rate. The results are shown in the table.

[0014]

[Table 1]

[0015]

As described above, the copper foil treated by the surface treatment method of the present invention can improve the adhesiveness to the resin substrate as indicated by the peel deterioration rate after boiling.

Continuation of the front page (72) Inventor Yukio Ogino 3--17-3 Nishinaminami, Toda City, Saitama Japan Inside Japan Energy Co., Ltd. (56) References JP-A-6-81157 (JP, A) JP-A-61- 76684 (JP, A) JP-A-61-23766 (JP, A) JP-A-62-152579 (JP, A) JP-A 1-150539 (JP, A) JP-A 5-309325 (JP, A) JP-A-4-285179 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C23C 22/83 H05K 1/09

Claims (1)

(57) [Claims] 1. A forming a rustproofing layer on the surface of the copper foil, then
A method for treating a copper foil, comprising: providing a hydroxyl group to the rust-proofing layer on the surface of the copper foil that has been subjected to the rust-proofing step, and applying a coupling agent thereto.