JPH10168596A - Surface treatment of copper foil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a uniform and highly adhesive roughening treatment method which is an easy method without using elements such as arsenic, selenium or tellurium having toxicity. SOLUTION: The surface treatment method for a copper foil is executed by activating, refining and roughening at least one surface of a copper foil after completion of a pickling process in an acidic bath of sulfulic acid contg. 1 to 1000ppm chlorine ions by the activation treatment process involving a positive and negative alternating pulse electrolysis or AC electrolysis and followed by roughening projecting matters of copper by cathode electrolysis in a sulfuric acid and copper sulfate bath near a limiting current density or above, and further, forming a coating layer by copper plating to roughen the copper foil, and subsequently, executing the rust-proof treatment. In such a case, treatment is executed in an aq. soln. contg. a 0.001 to 0.5mol/l org. compd. contg. sulfur in the middle between the acid pickling process and the activation treatment process. Otherwise, the org. compd. contg. sulfur may be contained in a bath in the pickling process. Further, the positive and negative alternating pulse electrolysis time is properly se at 0.2 to 200ms per cycle, and chromate treatment and/or org. substance rust prevention is executed as necessary after roughening in a rust preventing treatment.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a copper foil, particularly to a roughened surface treatment.
The present invention relates to a method for providing a surface treatment having high adhesiveness to an applied resin.

[0002]

2. Description of the Related Art Copper foils are widely used for electronic and electric materials, especially for printed wiring boards. The performance and reliability of printed wiring boards have been improving year by year, and as a result, they have become more complicated and diversified. Strict quality requirements have similarly been imposed on copper foil, which is one of the constituent materials of this printed wiring board.

In the production of printed wiring boards, first, the copper foil is laminated with the rough side of the copper foil together with a synthetic resin-impregnated base material, and heated and pressed by a press to obtain a copper-clad laminate. For a commonly used glass epoxy substrate, it is completed by pressing at 160 ° C. to 170 ° C. for 1 to 2 hours. As copper foil for printed wiring boards, electrolytic copper foil having a rough surface on one side and a glossy surface on one side is overwhelmingly used, and usually copper is electrolytically deposited from a copper electrolytic solution by an electrodeposition apparatus. An original foil called a treated copper foil is manufactured, and then a series of surface treatments are performed by a processing apparatus. Generally, the rough side (non-glossy side) is pickled and roughened to ensure adhesion to the resin. In addition, the adhesive properties such as heat resistance and chemical resistance, and etching properties The process is performed to improve and stabilize, etc., and it is completed. Various techniques have been developed and proposed for these treatments, resulting in highly functional surfaces. Recent densification of printed wiring boards, such as thin printed wiring boards and build-up printed wiring boards, where the resin layer serving as the insulating layer is extremely thin and the copper foil rough surface is large, may cause problems with interlayer insulation. There is.

[0004] In addition, it has been desired to reduce the profile on the roughened surface side, for example, by making the copper foil roughened surface as low as possible by forming a fine line. However, if the adhesive force is not sufficient, a problem of delamination, such as peeling or floating of the copper foil circuit after the production process or product, occurs, so a surface treatment that satisfies both is most preferable, but it is contradictory to each other Because of that, a better way was waiting. On the other hand, the opposite side, the glossy side, requires different properties from the rough side, that is, heat discoloration resistance, solder wettability, resist adhesion, etc. I need a way. However, there is no need for solder wettability especially in the case of application as an inner layer for multilayer printed wiring board applications, and the glossy side conventionally did not need to be roughened, but DT foil (Double treatment) In addition to the use of copper foil, which is referred to as "copper foil", a light surface roughening treatment has been demanded due to an increase in the adhesiveness of the resist and the adhesiveness of the inner layer treatment when forming a printed board.

As described above, complicated treatments have been developed on both surfaces of a copper foil in order to meet various demands. In the prior art, various techniques relating to the roughening treatment have been proposed. For example, Japanese Patent Publication No. 53-38700 discloses a method in which a three-stage electrolytic treatment is performed in an acidic electrolytic bath containing arsenic.
No.-39327, JP-B-54-38053, a method of electrolysis at around the limiting current density in an acidic copper electrolytic bath containing arsenic, antimony, bismuth, selenium, and tellurium, and JP-B-62-56677 and JP-B-62 No. 56678 proposes a method in a copper electrolytic bath to which molybdenum, vanadium or both are added. Japanese Patent Publication No. 61-54592 and Japanese Patent Application Laid-Open No. 4-202796 propose a surface treatment roughening method using alternating current electrolysis.

However, in the above-mentioned conventional methods, the use of substances harmful to the human body such as arsenic, antimony, bismuth, selenium, and tellurium has been extremely limited due to environmental problems. There is also a concern about the accumulation of harmful components in the reuse of printed boards, and alternative methods are strongly required. On the other hand, the method based on the addition of molybdenum, vanadium or the like is not yet sufficient in terms of adhesive strength, uniformity, residual copper, and the like, and the required high reliability cannot be obtained. Further, a roughening treatment using only AC electrolysis cannot provide a sufficient adhesive force, and is not practical.

[0007]

SUMMARY OF THE INVENTION The present inventors have studied various problems of the prior art described above, and have found that uniform and high adhesion can be obtained by an easy method without using toxic elements such as arsenic, selenium and tellurium. The resulting surface roughening method was developed and completed.

[0008]

[Means for Solving the Problem] Means for solving the problem are as follows: at least one surface of the copper foil is subjected to an alternating pulse electrolysis in a sulfuric acid acid bath containing 1 ppm to 1000 ppm of chloride ions after an acid washing step. Or by an activation treatment step by performing AC electrolysis, activation, fine roughening, and then, by sulfuric acid, cathodic electrolysis at or near the critical current density in a copper sulfate bath, roughening of copper protrusions. Perform, further, to form a coating layer by copper plating to roughen the copper foil,
Then, a surface treatment method for the copper foil characterized by performing a rust prevention treatment.If necessary, a sulfur-containing organic compound is added in an amount of 0.001 to 0.5 mol / l between the pickling step and the activation treatment step. The copper foil may be treated with an aqueous solution containing the acid, or the bath of the pickling step may contain an organic compound containing sulfur. Further, the positive and negative alternating pulse electrolysis time is appropriately set to 0.2 to 200 ms per cycle, and after the surface is roughened, the rust preventive treatment is carried out, if necessary, by chromate treatment and / or organic matter rust preventive treatment. Is a method for surface treating a copper foil.

The surface roughening method of the present invention basically includes three steps. The first stage is a pickling step of pickling the untreated copper foil to remove surface oxides and stains. It is preferable to use an aqueous sulfuric acid solution for the acid cleaning. 1 for sulfuric acid concentration
0 to 200 g / l is appropriate. The treatment time is 2-60 seconds, and the bath temperature is 10-50 ° C. In the second stage, chloride ions are
This is an activation process in which positive and negative alternating pulse electrolysis or alternating current electrolysis is performed in a sulfuric acid acid bath containing 00 ppm. As bath composition,
For example, 100 g / l sulfuric acid and 10 ppm sodium chloride. The sulfuric acid concentration is preferably between 10 and 200 g / l. The chlorine concentration is preferably 1 to 1000 ppm, and if it is 1 ppm or less, the degree of activation and coarsening is low.
If the content is more than 00 ppm, the corrosion of the copper surface becomes severe, and the fixation and uniformity of the copper projection are hindered. Normally, ion-exchanged water is used as industrial water to recycle water industrially, so water does not contain chlorine. However, when tap water is used, water contains nearly 10 ppm of chlorine. However, since the alternating pulse electrolysis or the alternating current electrolysis according to the present invention consumes chlorine, the chlorine must be continuously or intermittently added. As a method for adding chlorine, an alkali metal such as hydrochloric acid, sodium chloride, or potassium chloride, or a chloride of an alkaline earth metal is used.

The current density is 5 to 100 A / dm ² , and a suitable electric quantity is 20 to 1000 coulombs / dm ² . Temperature is 10-50 ℃
Is good. In the case of positive and negative alternating pulse electrolysis, both the on and off times of the current are 0.1 to 100 ms, the off time is 0 to 100 ms,
In addition, one cycle is 0.2 to 200 ms, and the efficiency of activation and fine surface roughening is low even if each cycle is too short or too long. Further, the waveform is not limited to a rectangular wave, a sine wave, or the like. However, it is preferable that the positive / negative ratio of the pulse electric quantity is equal, that is, 0.7 to 1.3. If the ratio is out of this range, the activation of the rough surface is reduced. In AC electrolysis, the positive / negative ratio of the current value is the same. Although a direct current may be overlapped with this, the positive / negative ratio is also set to 0.7 to 0.7 as in the alternating pulse electrolysis.
1.3 is better. The second stage treatment activates the surface of the copper foil and forms very fine irregularities, thereby improving the uniformity of the subsequent third stage roughening treatment. When the above-mentioned second stage treatment is not performed, the rough surface shape composed of copper projections obtained by the surface roughening treatment of the third stage occurs as a very uneven and coarse dendritic material. , Copper remains on the etched substrate surface. This defect is fatal for a printed wiring board. By applying the second-stage treatment, the third-stage surface-roughening treatment is made uniform, the surface roughness is reduced, and the adhesive strength is increased.

The micro-roughening in the second stage is a repetition of copper elution and deposition in a thin copper surface layer, which is completely different from the form of a cathode deposit. In the third step, surface treatment is performed by a known roughening method. That is, for example, dendritic or granular copper is deposited, and then copper plating is applied thereon to prevent the projections from falling off, thereby forming coated copper to form a rough copper surface. Formation of the copper protrusions is _{CuSO 4 · 5H 2 O 50 g} / l H 2 SO 4 100 g / l room temperature, a current density of 10A / dm ^2, 12
Seconds cathodic electrolysis then coated copper plating CuSO of _{4 · 5H 2 O 250 g /} l H 2 SO 4 100 g / l 50 ℃, current density of 5A / dm ^2, 80
Cathodic electrolysis for seconds The rough surface is completed.

Next, if necessary, treatments for imparting heat resistance and chemical resistance are performed.
A barrier layer of Co-Mo, W or Cu-Zn such as 8-19550 may be formed. In order to further increase the rust-preventing ability, a chromate treatment, an organic rust-prevention treatment typified by benzotriazole, and a silane coupling agent treatment are performed. Thus, a copper foil for a printed wiring board is completed. Normally, the glossy side of the copper foil was not required to be roughened except for the double-sided treated copper foil (DT foil) used for the inner layer of the multilayer board.
In recent years, in the manufacture of printed wiring boards,
In order to omit the soft etching step and to increase the adhesion force of the inner layer treatment, there is a demand for a DT foil which has been subjected to fine uniform and light roughening treatment in advance.

Therefore, in the above-mentioned method of the present invention, both sides of the copper foil are subjected to the second pickling step, the second step of the activation step,
That is, activation and fine roughening are performed by alternating positive and negative pulse electrolysis or alternating current electrolysis in a sulfuric acid acid bath containing 1 ppm to 1000 ppm of chlorine ions. The method of roughening copper fine projections by performing cathodic electrolysis at or near the limit current density in a bath, and further performing a process of forming a coating layer by copper plating on the rough surface side is a double-sided treatment. It can be proposed as an improvement of copper foil. Note that the above treatment may be performed with the rough surface and the glossy surface reversed in the copper foil treatment. In this case, at the time of preparing the copper-clad laminate, the surface which was the untreated copper foil on the glossy side is first bonded to the resin. In such a method, after molding with resin, the surface that is not bonded to the resin has higher adhesion with the resist after molding with resin than on the case where no treatment is applied to one side, and the adhesion is good, so the printed board manufacturer In the inner layer processing step,
This eliminates the need for a soft etching step as a pretreatment. In addition, the copper foil surface treatment can be performed very easily on the copper foil manufacturer side, since the copper foil surface treatment process requires only a lighter treatment than the conventional method of producing a double-sided copper foil.

Next, a further improved method in addition to the above method will be described. Between the first and second stage processes, 1-2
As a step, there is a method in which a step of treating the copper foil surface with an aqueous solution of an organic compound containing sulfur is used. Also,
An organic compound containing sulfur may be added to the treatment liquid of the first stage without adding the first and second stages. In addition,
The surface treatment step using the sulfur-containing organic compound aqueous solution was attached to a later step of manufacturing an untreated copper foil, which is a preceding step not described in the present invention, and the wound copper foil was then applied to a processing machine. In this case, the same effect can be easily understood by those skilled in the art. Examples of organic compounds containing sulfur include thiourea, allylthiourea, ethylenethiourea, acetylthiourea, benzothiazolethiol, aminobenzothiazole, aminothiazole, mercaptothiazoline, thioacetamide, mercaptomethylimidazole, thiodipropionic acid, and dithiodipropion. Any compound which is soluble in an aqueous solution or becomes water-soluble via a solvent such as an acid, benzimidazolethiol, thiodiethanol, dithiodiethanol, and mercaptoacetic acid may be used. The concentration of these compounds in aqueous solution is 0.001-0.5mol
/ l is appropriate, the temperature is preferably 10 to 50 ° C, and the processing time is preferably about 1 to 20 seconds. As a treatment method, a method by spraying or showering or an electrolytic treatment in an aqueous solution is performed, but it is better to treat the resin on the side of the first bonding surface with the resin. When the treatment is performed on the non-adhesive surface side, the adhesiveness of the blackening treatment, which is the inner layer treatment in the printed wiring board manufacturing process, may be reduced. After the treatment with the aqueous compound solution, it is preferable to wash with water in order to make the appearance of the treatment uniform. Further, if the subsequent surface roughening treatment is not carried out more than the normal amount of about 20 to 60% in terms of the amount of electricity, it becomes difficult to obtain an adhesive force. It is considered that the adsorbed sulfur compound suppresses the electrodeposition of copper and promotes homogenization.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The method of the present invention can be mass-produced by subjecting an electrolytic copper foil or a rolled copper foil to a surface treatment with a processing machine. As described above, the first stage of the pickling process, and then the second stage of the activation process of performing alternating pulse electrolysis or alternating current electrolysis.
Step treatment, followed by a roughening treatment comprising a sulfuric acid-copper sulfate solution as a third step treatment, and then, if necessary, heat treatment, chemical resistance treatment, further chromate treatment and / or organic rust prevention treatment by a known method. . Further, a step of treating with an aqueous solution of an organic compound containing sulfur may be provided between the first and second stages, or the organic compound containing sulfur may be added to the treatment bath of the first stage treatment.

[0016]

Embodiments of the present invention will be described below. Example (1) Both sides of an untreated electrolytic copper foil having a thickness of 35 μm After immersion in a bath for 10 seconds, 1 cycle 10 ms on both sides in the bath
Alternating pulse electrolysis was performed for 10 s with a square wave of 20 A / dm ² on both the positive and negative sides and 5 ms each on-time. Then only the rough side In a bath of 10 A / dm ² , cathodic electrolysis is performed for 12 seconds, and after washing with water, only the rough side is removed. In a bath of 5 A / dm ² , cathodic electrolysis for 80 seconds, washing with water, In the bath, the glossy surface is immersed and only the rough side is
Cathodic electrolysis was performed at 0.5 A / dm ² for 5 seconds, washed with water, and dried.
The rough surface of this copper foil is laminated as a surface to be adhered to a FR-4 grade glass epoxy resin impregnated substrate, and a pressure of 40 kgf / cm ² is applied.
It was pressed and molded at 70 ° C. for 60 minutes. Table 1 shows the results of examining the properties (adhesive strength, copper residue) of the copper-clad laminate. The glossy side was treated in a normal blackening bath without performing soft etching, laminated on a FR-4 grade glass epoxy resin-impregnated substrate, press-molded in the same manner, and the adhesive strength was measured. The results are also shown in Table 1.

Example (2) In Example (1), (B) the treatment in the bath was performed for one cycle time.
30ms, off-time 0ms positive and negative with 20A / dm ^2, each on-time
The treatment was performed in the same manner as in Example (1) except that the treatment was performed for 10 seconds by alternating pulse electrolysis having a rectangular wave of 15 ms, and each characteristic test was performed in the same manner. Table 1 shows the results.

Example (3) In Example (1), the treatment in the bath (B) was carried out for one cycle time.
2ms, Off time 0ms Both positive and negative 15A / dm ² On time 1
The treatment was performed in the same manner as in Example (1) except that the treatment was performed for 20 seconds by alternating pulse electrolysis having a rectangular wave of ms, and each characteristic test was performed in the same manner. Table 1 shows the results.

Example (4) In Example (1), the treatment in the bath (B) was carried out at a current density of 20 A / d.
The treatment was performed in the same manner as in Example (1), except that the treatment was performed by AC electrolysis at m ² and 60 Hz for 20 seconds, and each characteristic test was performed in the same manner. Table 1 shows the results.

Example (5) In the same manner as in Example (1), the rough surface was subjected to a spraying treatment at 20 ° C. for 10 seconds with an aqueous solution of thiourea 0.3 g / l between the treatments of the baths (A) and (B). All were carried out in the same manner as in Example (1) except that the bath was washed with water and that the electrolysis time in the bath (C) was 18 seconds. Each characteristic test was performed in the same manner as in Example (1). Table 1 shows the results.

Example (6) Both sides of an untreated electrolytic copper foil having a thickness of 35 μm Immersion for 10 seconds in the bath In the bath, pulse alternating electrolysis with a rectangular wave of 10 ms per cycle, off time 0 ms, positive and negative 20 A / dm ^{2 and} on time 5 ms each was performed for 10 seconds. Then only the glossy side In a bath of 10 A / dm ² , cathodic electrolysis at 18 A for 18 seconds. In a bath of 5 A / dm ² , cathodic electrolysis for 80 seconds, washing with water, In the bath, leave the rough side immersed and remove only the glossy surface.
Cathodic electrolysis was performed at 0.5 A / dm ² for 5 seconds, washed with water, and dried.
The rough surface of the copper foil was laminated on an FR-4 grade glass epoxy resin-impregnated base material as an adhered surface, and pressed and molded at 40 kgf / cm ² at 170 ° C. for 60 minutes. Table 2 shows the results of examining the characteristics (adhesive strength and copper residue) of the copper-clad laminate.
Shown in Further, the rough surface side was treated in a normal blackening treatment bath without performing soft etching, laminated on an FR-4 grade glass epoxy resin impregnated base material, press-molded in the same manner, and the adhesive strength was measured. The results are also shown in Table 2.

Example (7) In Example (6), the treatment in the bath (B) was carried out at a current density of 15 A / d.
The treatment was performed in the same manner as in Example (6), except that the treatment was performed for 10 seconds by AC electrolysis at m ² and 60 Hz, and each characteristic test was performed in the same manner. Table 2 shows the results.

Example (8) In Example (1), 0.5% of ethylene thiourea was added to the bath (A).
g / l was added, and the treatment with the bath (B) was performed at a current density of 20 / dm ² ,
10 seconds treatment with 60Hz AC electrolysis, and (C)
Example except that the electrolysis time of the treatment in the bath was set to 18 seconds
Processing was performed in the same manner as in (1), and each property test was performed in the same manner. Table 1 shows the results.

Example (9) In the same manner as in Example (1), after the bath treatment (A), the copper foil was washed with water, and the copper foil rough side was spray-sprayed with a 1 g / l aqueous solution of ethylene thiourea at 20 ° C. for 10 seconds. After washing with water, the treatment was performed in the same manner as in Example (1) except that the treatment in the bath (B) was continued, and the electrolysis time in the treatment in the bath (C) was set to 18 seconds. The test was performed. Table 1 shows the results.

Example (10) In Example (1), after the bath treatment (A), the copper foil was washed with water, and sprayed at 20 ° C. for 10 seconds with a 1 g / l aqueous solution of ethylene thiourea on the copper foil rough side. After washing with water, (B) Both sides were treated in a bath with a current density of 15 A / dm ² and 60 Hz AC electrolysis for 10 seconds,
(C) The treatment was performed in the same manner except that the electrolysis time in the bath was set to 18 seconds, and each characteristic test was performed in the same manner. Table 1 shows the results.

Example (11) In Example (6), 1.0 g / l of aminothiazole was added to the bath (A).
Was treated in the same manner as in Example (6), except that (B) the KCl concentration in the bath was 100 ppm, and each property test was conducted in the same manner. Table 2 shows the results.

Example (12) In Example (6), after the bath treatment (A), the copper foil was washed with water, and the glossy side of the copper foil was sprayed with a 0.2 g / l aqueous solution of thiourea at 20 ° C. for 10 seconds. Then, after washing with water, the treatment was performed in the same manner as in Example (6) except that the treatment current density was 10 A / dm ^{2 in} the bath (B) and the electrolysis time was 18 seconds, and each characteristic test was performed in the same manner. . Table 2 shows the results.

In Tables 1 and 2, "uniformity" was observed by an electron microscope at a magnification of about 500 times, and evaluated as 、, ○, Δ, and × from good.
"Adhesive strength" indicates the peel strength from the base material, J
IS-C-6481-1986 According to the method described in 5.7. The “residual copper on the etched substrate” was removed by etching cupric chloride, and then observed with a stereoscopic microscope at a magnification of 20 times. Those with no residual copper ○ Those with residual copper were evaluated as ×. The blackening treatment conditions are NaClO ₂ 50g / l, Na ₃ PO ₄・ 12H
_The reaction was performed at 2 g of 10 g / l, 8 g / l of NaOH, and 92 ° C. for 2 minutes.

[0029]

[Comparative example]

Comparative Example (1) In Example (1), immerse in the same bath as the bath (A) for 10 seconds and wash with water, then omit the bath (B), and perform the treatment of the baths (C), (D) and (E). This was performed in the same manner as in Example (1). In addition, this copper foil was used in Example (1)
Each characteristic test was performed in the same manner as described above. Table 1 shows the results.

Comparative Example (2) The same treatment as in Comparative Example (1) was carried out except that the electrolysis time in the bath (C) was changed to 18 seconds. In addition, this copper foil was used in Example (1)
Each characteristic test was performed in the same manner as described above. Table 1 shows the results.

Comparative Example (3) The rough surface of an untreated electrolytic copper foil having a thickness of 35 μm was prepared by using (A) of Example (4).
Immerse in the same bath for 10 seconds, wash with water and add no HCl
(B) Current density 20 A / dm ²
The treatment was carried out for 2 seconds, the treatment of bath (C) and bath (D) was omitted, and the same treatment as in Example (1) was carried out in bath (E). In addition, this copper foil
Each characteristic test was performed in the same manner as (1). Table 1 shows the results.
Shown in

Comparative Example (4) The rough surface of the untreated electrolytic copper foil having a thickness of 35 μm was immersed in the same bath as the bath (A) for 10 seconds in Example (1), washed with water, and treated in the bath (B). The treatment was performed with the bath (C) and the bath (E) omitted, and the treatment without the bath (D) was performed. The copper foil was subjected to each property test in the same manner as in Example (1). Table 1 shows the results.

Comparative Example (5) In Example (1), except that the treatment with the bath (B) was omitted and that the bath (C) contained 50 ppm of vanadium pentoxide.
The same was done. Each characteristic test was performed on the copper foil in the same manner as in Example (1). Table 1 shows the results.

Comparative Example (6) The procedure of Example (6) was repeated except that the treatment with the bath (B) was omitted. Each characteristic test was performed on this copper foil in the same manner as in Example (6). Table 2 shows the results.

Comparative Example (7) Using the copper foil obtained in Comparative Example (1), the glossy surface of the copper foil was etched with a soft etching solution (composition H ₂ SO ₄ 100 g / l, 35% H ₂ O ₂ water).
Soft etching was performed at 40 ° C. for 1 minute with 50 ml / l, CuSO ₄ .5H ₂ O 1 g / l), and then the same blackening treatment as in Example (1) was performed. This was similarly laminated on an FR-4 grade glass epoxy resin-impregnated substrate, press-molded, and the adhesive strength was measured to obtain 1.46 kg / cm 2. From these results, it can be seen that the copper foil according to the method of the present invention can achieve the same improvement in adhesive strength as that obtained by applying soft etching.

From the results of the Examples and Comparative Examples, the method of the present invention has higher uniformity of the surface state than the conventional method, has excellent adhesion to resin, and has the effect of reducing the surface roughness.
Furthermore, the surface that has been subjected to the blackening treatment has a higher adhesive strength than the copper foil that is not normally treated, does not need to be roughened by introducing a soft etching process, and has an excellent surface-treated copper foil. Recognize.

[0037]

According to the present invention, the following effects can be obtained. (1) This is a method of roughening without using toxic elements such as arsenic, selenium and tellurium as in the past, and has no adverse effect on the environment and the human body. (2) A uniform and high-adhesion surface-treated copper foil can be obtained, which is suitable for high-density printed wiring boards. (3) Due to the improved double-sided treatment, the adhesiveness with the resin is high, so that the soft etching step and the like in the copper foil inner layer processing step of the multilayer printed wiring board manufacturing can be omitted,
This can contribute to cost reduction in manufacturing a printed wiring board. (4) This surface treatment method is easy to introduce in an actual process, and mass production is possible.

[0038]

[Table 1]

[0039]

[Table 2]

[Brief description of the drawings]

FIG. 1 is an example of a waveform of alternating pulse electrolysis according to the present invention.

FIG. 2 is an example of a waveform of alternating pulse electrolysis according to the present invention.

FIG. 3 is an example of a waveform of AC electrolysis.

Claims (5)

[Claims] At least one surface of a copper foil is activated by a positive / negative alternating pulse electrolysis or an activation process of performing an alternating current electrolysis in a sulfuric acid acid bath containing 1 ppm to 1000 ppm of chloride ions after the pickling step. Fine roughening, followed by roughening of copper projections by performing cathodic electrolysis near or above the limiting current density in sulfuric acid and copper sulfate baths, and further roughening of copper foil to form a coating layer by copper plating. A surface treatment method for a copper foil, comprising performing surface treatment and then performing rust prevention treatment. 2. The copper foil according to claim 1, wherein the copper foil is treated with an aqueous solution containing 0.001 to 0.5 mol / l of an organic compound containing sulfur between the pickling step and the activation treatment step. Surface treatment method for foil. 3. The method according to claim 1, wherein the bath in the pickling step is an aqueous solution containing 0.001 to 0.5 mol / l of an organic compound containing sulfur. 4. The method according to claim 1, wherein the positive and negative alternating pulse electrolysis time is 0.2 to 200 ms per cycle. 5. The copper foil surface treatment method according to claim 1, wherein the rust prevention treatment is performed by chromate treatment and / or organic matter rust prevention.