JP3739929B2 - Copper foil for printed wiring board and method for producing the same - Google Patents

Description

【００４１】
【表２】

【００４２】
【発明の効果】
表１に示す通り、本発明の銅箔は、ピール強度、耐塩酸劣化率、粉落ち共毒性の強いヒ素を用いたもの（従来技術の一つ）と遜色ない性能を有するものである。これに対し、従来技術の他例（毒物を含まない）として挙げたモリブデン単用の銅箔は、ピール強度が低く、粉落ちも多く実用上問題の大きいものであることがわかる。
すなわち本発明に従えば、プリント配線板用銅箔としての所定の性能を充分に満足する環境に優しい銅箔及びそのための製造方法を提供することができる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a copper foil for printed wiring boards and a method for producing the same.
[0002]
[Prior art]
In order to join the copper foil for printed wiring board to the base material, the adhesive strength is improved, and in order to satisfy the required electrical characteristics, etching characteristics, heat resistance, chemical resistance as a printed wiring board, The surface of the copper foil to be joined was subjected to a roughening treatment, and further, the surface subjected to the roughening treatment was subjected to galvanization or nickel plating, and further, the galvanization or nickel plating was performed. Various devices have been devised, such as chromate treatment on the surface.
[0003]
Specific examples of these methods that are frequently used recently include the following.
[0004]
(1 ) Method disclosed in Japanese Examined Patent Publication No. 40-15327 A copper foil is used as a cathode in an acidic copper electrolytic bath, and electrolysis is performed in the vicinity of the limiting current density, so-called "bake plating" is applied to roughen the surface. This is a method for obtaining a chemical surface.
[0005]
(2) Covering the surface of the fine protrusions on the roughened surface subjected to the method “ bake plating” disclosed in US Pat. No. 3,293,109 with a thin layer of copper (so-called “capsule layer”), A method of stably fixing a fine projection group on the roughened surface of a copper foil.
[0006]
(3 ) Method disclosed in Japanese Examined Patent Publication No. 54-38053 In order to prevent the formation of relatively coarse dendritic protrusions and to obtain a roughened surface comprising a group of protrusions that are finer and uniform on the entire surface. A method of adding at least one of selenium, tellurium, arsenic, antimony, and bismuth to 0.01 to 1 g-M / l (M = Se, Te, As, Sb, Bi) in an electrolytic solution of an acidic copper electrolytic bath .
[0007]
(4 ) Method disclosed in JP-B-53-39327 At least one of selenium, tellurium, arsenic, antimony and bismuth is added in an amount of 0.03 to 5 g-M / l (M = Se, Te, As, "Sb, Bi)" Bake plating "is performed in an acidic copper electrolytic bath containing the added electrolyte, and the surface of the formed fine dendritic protrusions is covered with a thin layer of ordinary copper plating, and the protrusions are removed. Is a method to improve the adhesion strength to the base material while preventing powder and improving the powder transfer characteristics.
[0008]
However, many compounds containing selenium, tellurium, arsenic, antimony and bismuth are considered to be poisonous, deleterious, or similar, and as a result of these elements being incorporated into the electrodeposited copper during electrolysis, When reclaiming or discarding a foil or a printed wiring board using the same, or when disposing of an etching waste solution containing these elements, utmost care must be taken against environmental pollution. Furthermore, the effect obtained by adding these elements is small for those having low toxicity.
[0009]
On the other hand, those using electrolytes that do not contain these metals, that is, those that have a “bake plating layer” made only of copper, even if a normal copper plating layer is formed on the “bake plating layer” Even so, the fine protrusions themselves of the “bake plating layer” are rough, and the fine protrusion groups are not uniform. When rubbing the surface of the adherend surface of the copper foil having such a “bake plating layer”, a considerable amount of fine copper powder is peeled off, and the copper-clad laminate laminated with the resin substrate is etched. Later, there were defects such as copper powder remaining on the surface of the substrate.
[0010]
Improvements to these drawbacks include: a. A method of performing a roughening treatment using an electrolytic solution to which benzoquinolines are added (Japanese Patent Publication No. 56-44196); b. A method of performing a roughening treatment using an electrolytic solution to which molybdenum and / or vanadium is added (Japanese Patent Publication No. Sho 62-56777); c. A method of supplying a pulse current to an electrolytic bath for roughening treatment (Japanese Patent Laid-Open Nos. 58-16479 and 63-17597) has been proposed. As compared with the copper foil obtained by the roughening treatment using the electrolytic solution containing a strong elemental compound, only inferior ones in terms of peel strength, powder fall, and the like were obtained.
[0011]
[Problems to be solved by the invention]
The present invention has been made in order to solve the problems of the prior art, the surface of the adhesion surface to the substrate is uniform and non-uniform, there is no problem in terms of powder falling, and sufficient between the substrate and the substrate An object of the present invention is to provide a copper foil for a printed wiring board having adhesive strength and excellent in heat resistance or electrical characteristics, and a method for producing the same.
[0012]
[Means for Solving the Problems]
The present invention is a copper foil for a printed wiring board, and a copper plating metal element on the surface to be bonded of the original copper foil is made of molybdenum and at least one of iron, cobalt, and nickel. It is characterized by having a “burnt plating layer”.
[0013]
Here, the film thickness (apparent film thickness) of the “burnt plating layer” is preferably 0.2 to 2.5 μm, and more preferably 0.4 to 1.5 μm. Here, the “apparent film thickness” is a film thickness obtained by converting a granular plating electrodeposited when a “burn plating” treatment current is passed into a smooth plating.
[0014]
The copper foil of the present invention may further have a “copper plating layer” (so-called “capsule layer”) on the “bake plating layer”.
[0015]
Here, the film thickness (apparent film thickness) of the “capsule layer” is preferably 0.2 to 2.5 μm, and more preferably 0.4 to 1.5 μm.
[0016]
In addition, the copper foil of the present invention may be further provided with a “nickel plating layer” or “zinc plating layer” or “nickel plating layer” and “zinc plating” on the above “bake plating layer” or “capsule layer”. A layer "may be formed. In addition, the copper foil of the present invention may further comprise a chromate film on the “capsule layer” or further on the “nickel plating layer”, “zinc plating layer” or “nickel plating layer”, if desired. It may be formed on the “galvanized layer”.
[0017]
On the other hand, the method for producing a copper foil of the present invention uses an acidic copper electrolytic bath, uses the copper foil to be treated as a cathode, electrolyzes at a current density in the vicinity of the limit current density of the bath, and performs a copper burn on A method for producing a copper foil for a printed wiring board for forming a “plating layer”, wherein the burnt plating metal element of the copper burnt plating layer in the form of a solution is 0.001 of molybdenum in the electrolytic solution of the bath. ˜5 g / l and 0.01 to 10 g / l of at least one of iron, cobalt and nickel.
[0018]
Here, if the molybdenum concentration is less than 0.001 g / l, the desired effect is not remarkable. On the other hand, if the molybdenum concentration exceeds 5 g / l, the desired effect does not increase remarkably as compared with the increase in the abundance, so that it is not economical. The “bake plating layer” is not preferable because it is easily powdered. The behavior of iron, cobalt, and nickel outside the specified concentration is the same as that of molybdenum. The form of these additives is not particularly limited as long as it is soluble in the electrolytic solution (although most of these halides are dissolved in the electrolytic solution, which is not preferable because it adversely affects the roughening treatment). ) But representative compounds include the following.
1. Molybdenum: Sodium molybdate (dihydrate)
2. Iron: Ferrous sulfate (7 water salt)
3. Cobalt: Cobalt sulfate (7 hydrate)
4). Nickel: Nickel sulfate (7 water salt)
[0019]
As the acidic copper electrolytic bath, any acid can be used as long as it is a mineral acid, but usually a sulfuric acid bath (containing copper sulfate as copper) is used.
[0020]
The liquid composition and temperature of the copper sulfate-sulfuric acid bath can be selected in a wide range, but the limit current density of the bath shows the respective values by them, so the current density to be used depends on the liquid composition and liquid temperature, Depending on the movement of the liquid, etc., it is also different depending on whether only `` bake plating '' is applied, or whether normal copper plating, zinc plating, nickel plating, etc. are further applied on the capsule. It is necessary to adjust.
[0021]
Illustrative liquid conditions for an acidic copper electrolytic bath suitable for industrial use are as follows.
1. Copper: 5-50g / l
2. Molybdenum: 0.001 to 5 g / l
3. Other: 0.01 to 10 g / l
4). Acid: 10 to 100 g-H ₂ SO ₄ / l
5. Liquid temperature: Room temperature to 50 ° C
[0022]
Further, the amount of circulation of the bath is not particularly limited, but it is preferable that the lower limit is the amount of replenishment of the consumed components of the bath, and the upper limit is that the region near the cathode surface does not become a significant turbulent region.
[0023]
In addition, since the processing time is practically and preferably in the range of several seconds to several tens of seconds, it is preferable to set operation conditions such as liquid composition and current density so that a desired group of fine protrusions can be completed in such a time. .
[0024]
In the method for producing a copper foil of the present invention, subsequent to the step of forming the “burnt plating layer”, a “copper plating layer” or “nickel plating layer”, “zinc plating” is formed on the “burnt plating layer”. Layer ”or“ nickel plating layer ”and“ zinc plating layer ”may be performed, and if desired, further on the“ copper plating layer ”after the“ copper plating layer ”formation step. The step of forming “nickel plating layer” or “zinc plating layer” or “nickel plating layer” and “zinc plating layer” may be performed, and further, the “copper plating layer” formation step or the “nickel” Following the “plating layer” forming step, the “zinc plating layer” forming step or the “nickel plating layer” and the “zinc plating layer” forming step, the “copper plating layer” or the “nickel plating layer”, “zinc plating layer” Or Kell plating layer "and step may be carried out to form a chromate film on the" galvanized layer ". The conditions for these additional steps may follow those of known methods.
[0025]
In addition, the copper foil to be processed in the production method of the present invention may be an electrolytic copper foil or a rolled copper foil. This is because the type of the copper foil is not selected in the method of the present invention.
[0026]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in more detail based on examples. However, the present invention is not limited to these.
[0027]
Example 1
(1) Copper foil to be treated (raw copper foil)
Electrolytic copper foil (untreated copper foil; thickness: 18 μm; mat surface roughness: R _a = 0.6 μm; R _z = 4.2 μm; manufactured by Furukawa Circuit Foil Co., Ltd.)
(2) Formation of burnt plating layer The raw copper foil was subjected to cathodic electrolysis with direct current under the following conditions, and a "bake plating layer" consisting of fine protrusions was electrodeposited on the mat surface of the raw copper foil. .
(1) Electrolyte composition ・ Copper sulfate: 100g-CuSO ₄・ 5H ₂ O / l
・ Sulfuric acid: 120 g-H ₂ SO ₄ / l
・ Molybdenum: 0.6g-Na ₂ MoO ₄・ 2H ₂ O / l
_{Iron: 15g-FeSO 4 · 7H 2} O / l
(2) Electrolyte temperature: 35 ° C
(3) Current density: 40A / dm ²
(4) Processing time: 3.5 sec.
(3) The raw copper foil on which the fine projection group was formed on the capsule plating mat surface was subjected to cathodic electrolysis with direct current under the following conditions, and the fine projection group was covered with a thin copper layer.
(1) Electrolyte composition ・ Copper sulfate: 250g-CuSO ₄・ 5H ₂ O / l
・ Sulfuric acid: 100 g-H ₂ SO ₄ / l
(2) Electrolyte temperature: 50 ° C
(3) Current density: 20 A / dm ²
(4) Processing time: 7.0 sec.
(4) Further, the processing of (2) → (3) was repeated once more.
(5) Surface treatment Nickel-phosphorus plating (0.1 mg / dm ² ) and zinc plating (0.1 mg) on the surface of the obtained copper foil (hereinafter referred to as “roughened copper foil”) to be bonded. / dm ² ), and further a chromate treatment (hereinafter referred to as “surface-treated copper foil”) was prepared.
[0028]
The characteristics of the obtained surface-treated copper foil were evaluated for the following items, respectively.
[0029]
(1) Peel strength Normal surface peel according to 5.7 of JIS C 6481 “Testing method for copper-clad laminates for printed wiring boards” using the obtained surface-treated copper foil pressed and bonded to an FR-4 substrate as a sample. (Normal “stripping strength”) was measured.
[0030]
(2) Hydrochloric acid degradation rate After pressing and bonding the obtained surface-treated copper foil to the FR-4 base material, the surface-treated copper foil was etched to a width of 1 mm as a sample, and JIS C 6481 “Printed Wiring Board In accordance with 5.7 of “Copper-laminated laminate test method”, normal peel and post-degradation peel (so that the sample is immersed in a treatment solution at 25 ° C. mixed with the same amount of 35% hydrochloric acid and distilled water for 1 hour "Strength", hereinafter referred to as "peel after deterioration") was measured and obtained by calculation according to the following formula.
Hydrochloric acid deterioration rate (%) = (1− (peel after degradation / normal peel)) × 100
[0031]
(3) A test paper (Toyo filter paper No. 2) was placed on the surface-treated copper foil from which powder was removed, and the test paper was dragged in the horizontal direction by 150 mm while a load (250 g / 20 mmφ) was applied thereto. The copper powder adhering to the test paper was visually observed and evaluated in the order of A <B <C <D <E <F according to the amount of adhesion (A: powder falling “zero”, F: most powder falling) ).
[0032]
The results are shown in Table 1.
[0033]
Example 2
A roughened copper foil and a surface-treated copper foil were produced in the same manner as in Example 1 except that the composition of the electrolytic solution in the treatment (2) was changed to the following, and Example 1 of the surface-treated copper foil was prepared. The same characteristic evaluation was performed. The results are shown in Table 1.
<1> Composition of copper sulfate electrolytic _{solution: 100g-CuSO 4 · 5H 2} O / l
・ Sulfuric acid: 120 g-H ₂ SO ₄ / l
・ Molybdenum: 0.05g-Na ₂ MoO ₄・ 2H ₂ O / l
・ Tungsten: 0.05g-Na ₂ WO ₄・ 2H ₂ O / l
[0034]
Example 3
A roughened copper foil and a surface-treated copper foil were produced in the same manner as in Example 1 except that the composition of the electrolytic solution in the treatment (2) was changed to the following, and Example 1 of the surface-treated copper foil was prepared. The same characteristic evaluation was performed. The results are shown in Table 1.
<1> Composition of copper sulfate electrolytic _{solution: 100g-CuSO 4 · 5H 2} O / l
・ Sulfuric acid: 120 g-H ₂ SO ₄ / l
・ Molybdenum: 0.6g-Na ₂ MoO ₄・ 2H ₂ O / l
_{Iron: 15g-FeSO 4 · 7H 2} O / l
Tungsten: 0.03 g-Na ₂ WO ₄ · 2H ₂ O / l
[0035]
Example 4
A roughened copper foil and a surface-treated copper foil were produced in the same manner as in Example 1 except that the composition of the electrolytic solution in the treatment (2) was changed to the following, and Example 1 of the surface-treated copper foil was prepared. The same characteristic evaluation was performed. The results are shown in Table 1.
(1) Electrolyte composition ・ Copper sulfate: 100g-CuSO ₄・ 5H ₂ O / l
・ Sulfuric acid: 120 g-H ₂ SO ₄ / l
・ Molybdenum: 0.6g-Na ₂ MoO ₄・ 2H ₂ O / l
_{Cobalt: 10g-CoSO 4 · 7H 2} O / l
[0036]
Example 5
A roughened copper foil and a surface-treated copper foil were produced in the same manner as in Example 1 except that the composition of the electrolytic solution in the treatment (2) was changed to the following, and Example 1 of the surface-treated copper foil was prepared. The same characteristic evaluation was performed. The results are shown in Table 1.
(1) Electrolyte composition ・ Copper sulfate: 100g-CuSO ₄・ 5H ₂ O / l
・ Sulfuric acid: 120 g-H ₂ SO ₄ / l
・ Molybdenum: 0.6g-Na ₂ MoO ₄・ 2H ₂ O / l
_{Nickel: 10g-NiSO 4 · 7H 2} O / l
[0037]
Comparative Example 1
A roughened copper foil and a surface-treated copper foil were produced in the same manner as in Example 1 except that the composition of the electrolytic solution in the treatment (2) was changed to the following, and Example 1 of the surface-treated copper foil was prepared. The same characteristic evaluation was performed. The results are shown in Table 1.
(1) Electrolyte composition ・ Copper sulfate: 100g-CuSO ₄・ 5H ₂ O / l
・ Sulfuric acid: 120 g-H ₂ SO ₄ / l
・ Arsenic: 0.4cc / l as 60% H ₃ AsO ₄ (Specific gravity: 1.58)
[0038]
Comparative Example 2
A roughened copper foil and a surface-treated copper foil were produced in the same manner as in Example 1 except that the composition of the electrolytic solution in the treatment (2) was changed to the following, and Example 1 of the surface-treated copper foil was prepared. The same characteristic evaluation was performed. The results are shown in Table 1.
(1) Electrolyte composition ・ Copper sulfate: 100g-CuSO ₄・ 5H ₂ O / l
・ Sulfuric acid: 120 g-H ₂ SO ₄ / l
・ Molybdenum: 0.6g-Na ₂ MoO ₄・ 2H ₂ O / l
[0039]
The roughened copper foils obtained in Examples 1, 4, 5, Example 2, 3 and Comparative Examples 1 and 2 were subjected to roughening treatment on a sulfuric acid-hydrogen peroxide soft etching solution (H ₂ SO ₄ : 100 g / l, H ₂ O ₂ : 30 g / l, n-propanol: 10 cc / l) for 1 minute to dissolve the roughened film, and evaporate the solution to dryness to dissolve the solution. After decomposing and removing hydrogen peroxide contained in the solution, quantitative analysis of the target element in the solution is performed by atomic absorption spectrometry (using a Hitachi Z Corp. Z-6100 polarized Zeeman atomic absorption spectrophotometer). went. The results are shown in Table 2. In addition, data are converted into the abundance in the roughened film.
[0040]
[Table 1]

[0041]
[Table 2]

[0042]
【The invention's effect】
As shown in Table 1, the copper foil of the present invention has performance that is comparable to that using arsenic (a conventional technique) that has strong peel strength, resistance to hydrochloric acid deterioration, and powder fall off co-toxicity. On the other hand, it can be seen that the copper foil for a single molybdenum cited as another example of the prior art (not including a poison) has a low peel strength, a large amount of powder fall off, and a large practical problem.
That is, according to the present invention, it is possible to provide an environment-friendly copper foil that sufficiently satisfies the predetermined performance as a copper foil for printed wiring boards and a manufacturing method therefor.

Claims (9)

  A printed wiring board having a copper burnt plating layer composed of molybdenum and at least one of iron, cobalt and nickel on the surface to be bonded of the raw copper foil. Copper foil.   The copper foil for printed wiring boards according to claim 1, further comprising a copper plating layer on the burnt plating layer.   The copper foil for printed wiring boards according to claim 1, further comprising a nickel plating layer, a zinc plating layer, a nickel plating layer, and a zinc plating layer on the copper burnt plating layer or the copper plating layer.   The copper foil for printed wiring boards according to claim 2 or 3, further comprising a chromate film on the copper plating layer, the nickel plating layer, the zinc plating layer, or the nickel plating layer and the zinc plating layer.   Manufacture of copper foil for printed wiring boards using an acidic copper electrolytic bath, with the copper foil to be treated as a cathode, and electrolyzing at a current density near the limiting current density of the bath to form a copper burnt plating layer on the surface of the copper foil In the method, in the electrolyte solution of the bath, the burnt plating metal element of the copper burnt plating layer in the form of a solution is 0.001 to 5 g / l of molybdenum and at least one of iron, cobalt, and nickel. A method characterized by comprising 0.01 to 10 g / l.   The manufacturing method of the copper foil for printed wiring boards of Claim 5 which performs the process of forming a copper plating layer on this burn plating layer following the process of forming the said burn plating layer.   Next to the step of forming the burnt plating layer or the step of forming the copper plating layer, a nickel plating layer or a zinc plating layer or a nickel plating layer and zinc on the copper burnt plating layer or the copper plating layer. The manufacturing method of the copper foil for printed wiring boards of Claim 5 or 6 which performs the process of forming a plating layer.   Following the step of forming the copper plating layer or nickel plating layer, zinc plating layer or nickel plating layer and zinc plating layer, the copper plating layer or nickel plating layer, zinc plating layer or nickel plating layer and zinc plating layer The manufacturing method of the copper foil for printed wiring boards of Claim 6 or 7 which performs the process of forming a chromate membrane | film | coat on top.   The method for producing a copper foil for a printed wiring board according to any one of claims 5 to 8, wherein the electrolytic bath is a copper sulfate-sulfuric acid bath.