JPH0633497B2 - Anisotropic copper copper pyrophosphate plating solution - Google Patents

Description

TECHNICAL FIELD The present invention relates to an anisotropic copper copper pyrophosphate plating solution suitable for fine pattern plating and the like.

The anisotropy K as used herein refers to the elongation A of the plating in a direction parallel to a certain plating surface and the elongation B of the plating in a direction perpendicular to the plating surface, and the formula K = B / A It is represented by.

[Conventional technology]

Conventionally, photolithography has been often used in the production of precise printed circuit boards, but it is said that by using the additive method, a circuit board having a high wiring density can be formed, which is a considerably advantageous manufacturing method. .

However, in the printed circuit board using this manufacturing method, it is difficult to manufacture a thick and fine pattern because the anisotropy K does not exceed 1.

For example, when performing a pattern on a lined pattern, the line spacing of the pattern before the pattern is 100 μm,
Anisotropy K of 1 is obtained by adding 50 μm-thickness to it.
Therefore, the mating width also spreads by 50 μm and ends up between the lines. On the other hand, the present inventors have already filed Japanese Patent Application No. 55-1.
In 66614, it was clarified that the value of K was increased by increasing the current density of the metal particles.

Further, in Japanese Patent Application No. 59-87876, the copper ion concentration [Cu ²⁺ ] 25 to 38 g /, the pyrophosphate ion concentration [P ₂ O ₇ ^{4 −} ] / copper ion concentration [Cu ²⁺ ] weight ratio 6.5. 7.5, ammonia concentration [NH _3] = 0.05～0.20Mo
It has been clarified that the value of K is further increased in the copper pyrophosphate plating solution consisting of 1 /, so that it becomes possible to thickly coat a fine printed circuit board.

[Problems to be solved by the invention]

However, in order to increase the value of K, the ammonia concentration [NH ₃ ] in the copper pyrophosphate plating solution is always kept at 0.
It was necessary to keep it at 05 mol / mol or more, and therefore it was inevitable to consume a large amount of aqueous ammonia.

[Means and Actions for Solving Problems]

Therefore, as a result of detailed investigations on the composition conditions of the copper pyrophosphate solution, the present inventors have found that a composition having a high K value and good surface properties even when the ammonia concentration [NH ₃ ] is lower than 0.05 mol / min. I found a thing.

That is, the present invention provides (A) copper ion concentration [Cu ²⁺ ] 22 to 42 g / (B) pyrophosphate ion concentration [P ₂ O ₇ ^{4 −} ] / copper ion concentration [Cu ²⁺ ] (weight ratio) 6 0.0-8.0 (C) Ammonia concentration [NH ₃ ] 0.01-0.05 mol / less (D) Aluminum ion concentration [Al ³⁺ ] 0.1-500 mg / (E) pH is 8.2 Anisotropic copper copper pyrophosphate plating solution of 9.0.

In order to prepare the composition of the present invention, potassium pyrophosphate and copper pyrophosphate are added to a commercially available copper pyrophosphate plating solution, and further ammonia water and an aluminum ion-containing aqueous solution are added to adjust the composition conditions, or potassium pyrophosphate is added. It is also possible to dissolve copper pyrophosphate in a predetermined amount in water and then add ammonia water and an aqueous solution containing aluminum ions. In addition, additives and stabilizers which are usually used may be added if necessary.

In the present invention, the ratio of the weight concentration of the pyrophosphate ion P ₂ O ₇ ^{4− to} the copper ion Cu ^{2+ is} called the P ratio.

The range of the P ratio is 6.0 to 8.0, preferably 6.0 to 7.
8, and more preferably 6.3 to 7.5. When the P ratio is lower than 6.0, so-called clouding occurs. On the other hand, when it is higher than 8.0, the limiting current density becomes low and it becomes easy to burn. Copper ion concentration [Cu ²⁺ ] is 22 to 42 g /
, Preferably 28 to 42 g /, more preferably 3
It is 0 to 40 g /. When the copper ion concentration is lower than 22 g /, the limiting current density becomes low and it becomes easy to burn.
If it is higher than 2 g / m, cloudiness occurs.

The ammonia concentration [NH ₃ ] is generally 0.01 to 0.20.
Although the plating is performed at mol / mol, in the present invention, the feature is exhibited at 0.01 to less than 0.05 mol / mol. When the ammonia concentration is lower than 0.01 mol /, the limiting current density is lowered and the current density range where a predetermined gloss is obtained is narrowed. Also, the ammonia concentration is 0.05m
When it becomes ol / or more, the amount of ammonia consumed increases, and it is necessary to replenish a large amount of ammonia water to keep the concentration constant, which requires a lot of manpower for management. When it is 0.20 mol / or more, the malleability of copper is significantly deteriorated and the internal stress is considerably increased.

Aluminum ion concentration [Al ³⁺ ] is 0.1 to 500 m
g /, preferably 0.1 to 200 mg /, more preferably 1.0 to 100 mg /. When the aluminum ion concentration is 0.1 mg / or less, the effect of improving the anisotropy does not appear. If it exceeds 500 mg /, phenomena such as abnormal protrusions and poor adhesion occur. Any method may be used for dissolving aluminum ions in the plating solution. For example, a commercially available reagent such as aluminum nitrate Al (NO ₃ ) ₃ may be used to dissolve it in the plating solution. May be. Alternatively, metallic aluminum may be directly immersed in the plating solution to be dissolved. I'm not sure why aluminum ions increase anisotropy,
The presence of aluminum ions in the plating solution seems to cause the crystal growth direction of the plating copper to be a specific direction.

Under the above composition conditions, the pH is 8.2 to 9.
It should be between 0 and 0, but if the pH is lower than this, KOH is used. If the pH is high, polyphosphoric acid or citric acid or a pH adjuster commercially available from each plating solution manufacturer is used. The pH is adjusted to 0, preferably 8.4 to 8.8.

The current density of the cathode is 3 to 50 A / dm ² , preferably 5 to 20 A / dm ² . In order to increase the value of K, the higher the current density of the cathode, the better. The upper limit is determined by the burn phenomenon.

Agitation is necessary, and air agitation, pump agitation, cathode oscillation, or a combination thereof may be used. For example, in the case of air agitation, the air flow rate is 0.01 to 2.00 M ³ /
M ² minutes (volume in the standard state of the amount of air flowed per minute per unit area of the plating layer liquid) is preferable. The bath temperature during plating is preferably 50 to 60 ° C., as is generally done.

Any base material may be used as the base of the plating, as long as it has conductivity, and examples of the metal include copper, nickel, and aluminum.

There is no particular problem with the plating device and the like as long as it is commonly used.

Hereinafter, in order to further clarify the embodiments of the present invention, examples will be described.

Examples 1 to 3 Insulating polyimide film (trade name, manufactured by Dyupon Co .;
"Kapton", thickness: 25 μm) and 5 μm thick copper foil on a phenol resin adhesive (BOSTICK brand name: XA
-564-4) is used for adhesion. Next, a negative resist (trade name, manufactured by Eastman Kodak Co., Ltd .; "Microresist 747-110cst") was dried to a resist thickness of 3
It is coated on a copper surface to a thickness of -5 μm, pre-baked, and then exposed with a high-pressure mercury lamp through a circuit pattern mask to obtain a dedicated developing solution (trade name: Micro Resist Developer, manufactured by Eastman Kodak Co.) and a rinse solution ( The resist was formed into a circuit pattern by developing with Eastman Kodak Co., Ltd .; Microresistance) and post-baking. Then, the copper foil was removed by etching with a 50% ferric chloride solution. Further, the resist on the copper foil is removed using a resist remover (trade name: "J-100" manufactured by Nagase Kasei Co., Ltd.). As a result, the film thickness is 5 μm and the width is 130 μm.
m, and a linear pattern having an array pitch of 200 μm was obtained.

Then, an appropriate amount of potassium pyrophosphate, copper pyrophosphate and water are added to a copper pyrophosphate plating solution (trade name of "Hashiyo Murata Co., Ltd .;" pyrodon conc "), and the composition becomes a copper ion concentration of 34 g /, P ratio = 7. Adjust and adjust the concentration to 28
% Ammonia water converted to ammonia 0.03mo
After adding it to a concentration of 1 /, dissolve the aluminum nitrate reagent so that the aluminum ion concentration becomes 30 mg /, and further adjust the pH of the prepared plating solution to 5% with KOH 5% solution or adjust the pH. The above linear copper pattern was subjected to a current density of 5.8 A / dm ² , air agitation of 0.1 M ³ / M ² minutes, and a bath temperature of 55 ° C. using a plating solution to which a solution (manufactured by Hashiyo Murata) was added. I went to Metuki. From the width and thickness of the copper linear pattern obtained as a result, K
= 1.95, and high anisotropy was exhibited. Further, in Examples 2 to 3, using a plating bath in which the aluminum ion concentration was adjusted as shown in Table 1 and the pH was further adjusted, plating was performed on the same kind of copper linear pattern as the above under the same conditions. Table 1 shows the results of measuring the thickness and width of the resulting pattern.
Shown in.

In all cases, the physical properties of copper were practically sufficient.

Comparative Example 1 A copper foil having a thickness of 5 μm is adhered onto an insulating substrate by using a phenol resin adhesive (trade name: “XA-564-4” manufactured by BOSSTICK). Next, a negative resist (trade name, manufactured by Eastman Kodak Co., Ltd .; “Microresist 747-110
cst ”) is dried and then applied to a copper surface so that the resist thickness becomes 3 to 5 μm, prebaked, exposed with a high pressure mercury lamp through a circuit pattern mask, developed with a dedicated developing solution and a rinsing solution, and post-baked. Bake to form a resist in a circuit pattern. Subsequently, the copper foil was removed by etching with a 50% ferric chloride solution. Further, a resist remover (“J-100” manufactured by Nagase Kasei Co., Ltd.) is used to remove the resist on the copper foil. As a result, the film thickness is 5 μm and the width is 13
A linear pattern of 0 μm and array pitch of 200 μm was obtained. Next, an appropriate amount of potassium pyrophosphate, copper pyrophosphate and water was added to a copper pyrophosphate plating solution (trade name of "Hashiyo Murata Co., Ltd .;" pyrodon conc "), and the composition thereof was a copper ion concentration of 34 g /, P ratio = 7.0. Then, an appropriate amount of 28% concentration ammonia water is added, and the concentration is adjusted to 0.03 mol / in terms of ammonia, and the pH of the prepared plating solution is adjusted to 8.7% KOH 5% solution. Alternatively, a pH adjusting solution (manufactured by Hersho Murata) was added.

The linear copper pattern was formed at a current density of 5.8 A using a plating solution containing no such aluminum ions.
/ Dm ² , air agitation 0.1M ³ / M ² minutes, bath temperature was 55 ° C. When K was calculated from the width and thickness of the copper linear pattern obtained as a result, it was 1.58.

Comparative Example 2 A copper foil having a thickness of 5 μm is bonded onto an insulating substrate by using a phenol resin adhesive (trade name: “XA-564-4” manufactured by BOSSTICK). Next, a negative resist (trade name, manufactured by Eastman Kodak Co., Ltd .; “Microresist 747-110
cst ”) is dried and then applied to a copper surface so that the resist thickness becomes 3 to 5 μm, prebaked, exposed with a high pressure mercury lamp through a circuit pattern mask, developed with a dedicated developing solution and a rinsing solution, and post-baked. Bake to form a resist in a circuit pattern. Subsequently, the copper foil was removed by etching with a 50% ferric chloride solution. Further, a resist remover (“J-100” manufactured by Nagase Kasei Co., Ltd.) is used to remove the resist on the copper foil. As a result, the film thickness is 5 μm and the width is 13
A linear pattern of 0 μm and array pitch of 200 μm was obtained. Next, an appropriate amount of potassium pyrophosphate, copper pyrophosphate and water was added to a copper pyrophosphate plating solution (trade name of "Hashiyo Murata Co., Ltd .;" pyrodon conc "), and the composition thereof was a copper ion concentration of 34 g /, P ratio = 7.0. Then, an appropriate amount of ammonia water with a concentration of 28% is added, the concentration is adjusted to 0.03 mol / in terms of ammonia, and the aluminum nitrate reagent is dissolved so that the aluminum ion concentration becomes 1 g /. A KOH 5% solution or a pH adjusting solution (manufactured by HASHIO Murata Co., Ltd.) was added so that the pH of the prepared beaker solution would be 8.7. Using such a plating solution, the above-mentioned linear copper pattern was plated under the conditions of a current density of 5.8 A / dm ² , air stirring of 0.1 M ³ / M ² minutes, and a bath temperature of 55 ° C. Many abnormal protrusions were found on the pattern surface.

Comparative Example 3 A copper foil having a thickness of 5 μm is bonded onto an insulating substrate by using a phenol resin adhesive (trade name: “XA-564-4” manufactured by BOSSTICK). Next, a negative resist (trade name, manufactured by Eastman Kodak Co., Ltd .; “Microresist 747-110
cst ”) is dried and then applied to a copper surface so that the resist thickness becomes 3 to 5 μm, prebaked, exposed with a high pressure mercury lamp through a circuit pattern mask, developed with a dedicated developing solution and a rinsing solution, and post-baked. Bake to form a resist in a circuit pattern. Subsequently, the copper foil was removed by etching with a 50% ferric chloride solution. Further, a resist remover (“J-100” manufactured by Nagase Kasei Co., Ltd.) is used to remove the resist on the copper foil. As a result, the film thickness is 5 μm and the width is 13
A linear pattern of 0 μm and array pitch of 200 μm was obtained. Next, an appropriate amount of potassium pyrophosphate, copper pyrophosphate and water was added to a copper pyrophosphate plating solution (trade name of "Hashiyo Murata Co., Ltd .;" pyrodon conc "), and the composition thereof was a copper ion concentration of 34 g /, P ratio = 7.0. Then, an appropriate amount of 28% concentration ammonia water is added, the concentration is adjusted to 0.03 mol / in terms of ammonia, and aluminum nitrate is dissolved so that the aluminum ion concentration becomes 0.6 g / Further, a 5% KOH solution or a pH adjusting solution (manufactured by Herushiyo Murata Co., Ltd.) was added so that the pH of the prepared plating solution became 8.7.

Using such a plating solution, the linear copper pattern was subjected to current density of 5.8 A / dm ² , air agitation of 0.1 M ³ / M.
^When plating was performed for ² minutes at a bath temperature of 55 ° C., some fine projections were found on the pattern surface.

〔effect〕

When the copper pyrophosphate plating solution of the present invention is used, the anisotropy K is increased and a printed circuit board having a fine film thickness pattern can be manufactured even when the ammonia concentration is less than 0.05 mol /.

Claims (1)

[Claims] 1. (A) Copper ion concentration [Cu ²⁺ ] 22-42
g / (B) pyrophosphate ion concentration _[P 2 O ₇ ^4-] / copper ion concentration [Cu ^2+] (weight ratio) 6.0 to 8.0 (C) ammonia concentration [NH _3] 0.01 Less than 0.05 mol / (D) Aluminum ion concentration [Al ³⁺ ] 0.1-500 mg / (E) Anisotropic copper copper pyrophosphate plating solution having a pH of 8.2-9.0