JP4499502B2 - Leveling agent for plating, additive composition for acidic copper plating bath, acidic copper plating bath, and plating method using the plating bath - Google Patents

Description

  The present invention relates to a leveling agent for plating, an additive composition for an acidic copper plating bath, an acidic copper plating bath, and a plating method using the plating bath.

  In recent years, electronic devices such as mobile phones, personal computers, videos, and game machines have been used with higher density and smaller components, and printed circuit boards on which they are mounted have been required to have higher circuit density. Yes. Further, in the circuit mounting described above, in general, a minute hole such as a blind via hole or a through hole is provided in a laminated plate, and connection between each circuit layer is performed by a metal deposited in the minute hole.

  For example, with respect to the blind via hole, connection between layers is conventionally performed by blind via hole plating for forming a metal film on the inner side surface and the bottom surface of the blind via hole. On the other hand, with respect to the through holes, the connection between the layers of the substrate is conventionally performed by a through hole plating method in which a metal film is uniformly formed on the inner surface of the through holes.

  However, with the increase in the density of the circuit described above, the through holes and blind via holes used for interlayer connection of both surfaces or multilayer substrates are also required to have a smaller diameter and a higher aspect.

  As for the above-described blind via hole plating and through-hole plating, a number of plating additives and plating baths have been developed and put on the market. However, some acid copper plating additives and plating baths that have been provided in the past (general plating baths) are excellent in plating appearance such as leveling of the plating surface, but the interior of blind via holes and through holes Others (high performance plating baths) are excellent in blind via holes and through-holes and corner plating, but the plating surface has poor plating coverage. There has been no additive or plating bath for acidic copper plating that is inferior in plating appearance such as leveling properties and satisfies all of these characteristics.

Under such circumstances, the present invention is excellent in any of the plating appearances such as the inside of blind via holes and through-holes, the cornering portion with plating and the leveling property of the plating surface in the acidic copper plating process. It is a first object to provide a novel leveling agent for plating that gives properties.
In addition, a second object of the present invention is to provide an additive composition for an acidic copper plating bath that includes the above leveling agent for plating and has the above-described excellent characteristics.
Moreover, this invention makes it the 3rd objective to provide the acidic copper plating bath containing the said additive composition.
In addition, the present invention uses the acidic copper plating bath and performs high-reliability copper plating on a substrate having micropores such as through holes and blind via holes, or a resin film whose surface is coated with a metal such as copper. A fourth object is to provide a method.

As a result of intensive studies to achieve the above-mentioned object, the present inventors have found that a diallyldialkylammonium alkyl sulfate-sulfur dioxide copolymer having a specific structure has an excellent function as a leveling agent for plating, And it discovered that the above-mentioned objectives could be achieved by using this copolymer in the additive composition for plating, and came to complete this invention based on this knowledge.
That is, the present invention
(1) General formula (I)

(In the formula, R ¹ and R ² are each independently a methyl group, an ethyl group or a hydroxyethyl group, but R ¹ and R ² are not both a hydroxyethyl group, and R ³ is a methyl group or an ethyl group. )
A diallyldialkylammonium alkyl sulfate unit represented by formula (II):

A leveling agent for plating comprising a diallyldialkylammonium alkyl sulfate-sulfur dioxide copolymer containing a sulfur dioxide unit represented by:
(2) In the general formula (I), the leveling agent for plating according to the above (1), wherein R ¹ is an ethyl group, R ² is a methyl group, and R ³ is an ethyl group,
(3) The leveling agent for plating according to the above (1) or (2), which is an alternating copolymer having a diallyldialkylammonium alkylsulfate unit / sulfur dioxide unit molar ratio of 1/1.
(4) (A) For an acidic copper plating bath characterized by including the leveling agent for plating as described in the above item (1), (2) or (3), (B) a polymer component and (C) a brightener component Additive composition,
(5) Acid copper as described in said (4) term containing (A) component 0.01-5 g / L, (B) component 0.01-10 g / L, and (C) component 0.02-200 mg / L Additive composition for plating bath,
(6) (B) The polymer component is at least one selected from polyethylene glycol, polypropylene glycol, pluronic surfactant, tetronic surfactant, polyethylene glycol glyceryl ether and polyethylene glycol dialkyl ether. Additive composition for acidic copper plating bath according to (4) or (5) above,
(7) (C) The brightener component is at least one selected from mercaptoalkyl sulfonates, organic disulfide compounds, and dithiocarbamic acid derivatives, as described in (4), (5) or (6) above Additive composition for acidic copper plating bath,
(8) The basic bath composition containing (D) copper ions of 5 to 75 g / L, (E) organic acids and / or inorganic acids of 20 to 300 g / L, and any one of the above items (4) to (7) An acidic copper plating bath comprising the additive composition for an acidic copper plating bath described in 1.
(9) Furthermore, (F) acidic copper plating bath as described in the said (8) term containing 10-100 mg / L of chlorine ions,
(10) A method for plating a substrate, characterized in that a substrate that has been perforated and subjected to a conductive treatment is plated with the acidic copper plating bath described in (8) or (9) above, and (11) Surface A resin film plating method, wherein the resin film having a metal coating formed thereon is plated with the acidic copper plating bath described in (8) or (9) above,
Is to provide.

According to the present invention, in the acidic copper plating process, for a new plating that gives excellent properties in any of the plating appearances such as the inside of the blind via hole and the through hole, the plating around the corner portion and the leveling property of the plating surface Leveling agents were provided.
In addition, by using this novel plating leveling agent as one component, an acidic copper plating bath additive composition having the above-described excellent characteristics and an acidic copper plating bath containing the additive composition were provided.
In addition, by using the acidic copper plating bath, it is more reliable than conventional products for substrates with minute holes such as through holes and blind via holes, or resin films whose surfaces are coated with metals such as copper. The copper plating process can be performed.

First, the leveling agent for plating of this invention is demonstrated.
The leveling agent for plating of the present invention has the general formula (I)

(In the formula, R ¹ and R ² are each independently a methyl group, an ethyl group or a hydroxyethyl group, but R ¹ and R ² are not both a hydroxyethyl group, and R ³ is a methyl group or an ethyl group. )
A diallyldialkylammonium alkyl sulfate unit represented by formula (II):

It comprises a diallyldialkylammonium alkylsulfate-sulfur dioxide copolymer containing a sulfur dioxide unit represented by:

In the copolymer, diallyldialkylammonium alkylsulfate units include diallyldimethylammonium methylsulfate units, diallylethylmethylammonium methylsulfate units, diallyldiethylammonium methylsulfate units, diallyl (hydroxyethyl) methylammonium methylsulfate units. Fate unit, diallylethyl (hydroxyethyl) ammonium methyl sulfate unit, diallyldimethylammonium ethyl sulfate unit, diallylethylmethylammonium ethyl sulfate unit, diallyl diethylammonium ethyl sulfate unit, diallyl (hydroxyethyl) methylammonium ethyl sulfate Unit, diallylethyl (hydroxyethyl) ammonium ethyl Although Sulfate unit can be preferably exemplified, in the general formula (I) R ¹ is ethyl, R ² is a methyl group, R ³ is diallyl methyl ammonium ethyl sulfates units an ethyl group is particularly preferred. In the present invention, hydroxyethyl is preferably 2-hydroxyethyl.

  From the viewpoint of production, the copolymer is a copolymer of diallyldimethylammonium methylsulfate and sulfur dioxide, a copolymer of diallylethylmethylammonium methylsulfate and sulfur dioxide, diallyldiethylammonium ethylsulfate, A copolymer of sulfur dioxide and a copolymer of diallylethylmethylammonium ethylsulfate and sulfur dioxide are preferred, but a copolymer of diallylethylmethylammonium ethylsulfate and sulfur dioxide is particularly preferred.

  In the production of the copolymer, the monomer molar ratio of diallyldialkylammonium alkylsulfate / sulfur dioxide is usually 0.5 / 0.5 or more from the viewpoint of the stability of the copolymer obtained, preferably 0.5 / 0.5 to 0.95 / 0.05, more preferably 0.5 / 0.5 to 0.8 / 0.2, still more preferably 0.5 / 0.5 to 0.6 / 0.4, particularly preferably 0.5 / 0.5.

  When the monomer molar ratio is 0.5 / 0.5, the obtained copolymer is considered to be represented by a cyclized alternating copolymer such as the following (III).

当該共重合体の分子量は、ゲルパーミエーションクロマトグラフィー（ＧＰＣ）法によるポリエチレングリコール換算の重量平均分子量で、通常３００〜５０，０００、好ましくは５００〜２５，０００、より好ましくは８００〜１０，０００の範囲である。

The molecular weight of the copolymer is a weight average molecular weight in terms of polyethylene glycol by gel permeation chromatography (GPC), and is usually 300 to 50,000, preferably 500 to 25,000, more preferably 800 to 10,000. Range.

Although there is no restriction | limiting in particular in the manufacturing method of the said copolymer, For example, a desired copolymer can be manufactured efficiently by the method shown below.
That is, in the polar solvent, the general formula (IV)

(In the formula, R ¹ and R ² are each independently a methyl group, an ethyl group or a hydroxyethyl group, but R ¹ and R ² are not both a hydroxyethyl group, and R ³ is a methyl group or an ethyl group. )
The copolymer is obtained by copolymerizing a diallyldialkylammonium alkyl sulfate represented by the following formula with sulfur dioxide.

  The diallyldialkylammonium alkyl sulfate used as the monomer can be produced, for example, by an alkylation reaction by a reaction of diallylalkylamine and dialkylsulfuric acid.

  Diallyldimethylammonium methylsulfate, diallylethylmethylammonium methylsulfate, and diallyl (hydroxyethyl) methylammonium methylsulfate are methyl compounds that are reacted by adding dimethylsulfuric acid to diallylmethylamine, diallylethylamine, and diallyl (hydroxyethyl) amine, respectively. It can be produced by a chemical reaction.

  In addition, diallyl diethylammonium ethyl sulfate, diallylethylmethylammonium ethyl sulfate, diallylethyl (hydroxyethyl) ammonium ethyl sulfate, respectively, add diethyl sulfate to diallylethylamine, diallylmethylamine, diallyl (hydroxyethyl) amine. Can be produced by an ethylation reaction.

  The polar solvent is a solvent that dissolves diallyldialkylammonium alkyl sulfate and sulfur dioxide. Examples thereof include water, methyl alcohol, ethyl alcohol, dimethyl sulfoxide, dimethylformamide, and dimethylacetamide.

  In the production of the copolymer, the polymerization catalyst used for the radical copolymerization reaction is not particularly limited as long as it can polymerize diallyldialkylammonium alkyl sulfate and sulfur dioxide. Organic peroxides such as hydroperoxide and cumene hydroperoxide, aliphatic azo compounds such as 2,2′-azobisisobutyronitrile, inorganic peroxides such as ammonium persulfate and potassium persulfate, ammonium nitrate And nitrates such as potassium nitrate. Moreover, the gas containing oxygen, such as air, a radiation, an ultraviolet-ray, and visible light are also mentioned.

  When producing the copolymer, the copolymer is usually added by adding the polymerization catalyst to a polar solvent solution containing the diallyldialkylammonium alkyl sulfate and sulfur dioxide, and appropriately stirring at room temperature or under heating conditions. Is done. The polymerization temperature is preferably -100 ° C to 80 ° C. The polymerization time is preferably 1 to 100 hours.

  After completion of the reaction, the copolymer can be reprecipitated and filtered by adding a solvent that does not dissolve the copolymer, such as alcohol or acetone.

  The diallyldialkylammonium alkylsulfate-sulfur dioxide copolymer thus obtained is excellent as a plating leveling agent by adsorbing to the projections on the surface of the object to be plated and suppressing plating deposition on the projections. ing. In the additive composition for acidic copper plating baths, the copolymer exhibits excellent properties in all aspects of plating appearance, such as the inside of blind via holes and through-holes, cornering and plating leveling, and plating surface leveling. To do.

Next, the additive composition for acidic copper plating baths of the present invention will be described.
The additive composition for an acidic copper plating bath of the present invention is a composition comprising (A) the above-described leveling agent for plating of the present invention, (B) a polymer component and (C) a brightener component.

  The concentration of the leveling agent for plating as the component (A) is preferably 0.01 to 5 g / L, particularly in the range of 0.5 to 2 g / L in the composition of the final acidic copper plating bath. It is preferable that it exists in.

  The polymer component as the component (B) acts as a wetting agent that improves the wettability of the plating solution. Examples of such a polymer component include polyethylene glycol, polypropylene glycol, pluronic-type surfactant, and tetronic type. Examples of the surfactant include polyethylene glycol / glyceryl ether and polyethylene glycol / dialkyl ether.

  Here, as the polyethylene glycol, those having a repeating number of oxyethylene units of 10 to 500 and polypropylene glycol having a repeating number of oxypropylene units of 1 to 20 are preferably used.

Moreover, as a pluronic-type surfactant, for example, the general formula (V)
_{HO- (C 2 H 4 O)} a - (C 3 H 6 O) b - (C 2 H 4 O) c -H (V)
(Wherein, a and c are each a number of 1 to 30, and b is a number of 1 to 100)
As a tetronic surfactant, for example, a compound represented by the general formula (VI)

(Wherein, d is a number from 1 to 200, and e is a number from 1 to 40)
The compound represented by these can be mentioned.

  Furthermore, as polyethylene glycol glyceryl ether, for example, general formula (VII)

(Wherein f, g and h each represent a number of 1 to 200)
As the polyethylene glycol dialkyl ether, for example, the general formula (VIII)
^{_{R 4 O- (C 2 H 4}} ) i -OR 5 (VIII)
(In the formula, R ⁴ and R ⁵ are each independently a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and i represents a number of 2 to 200)
The compound represented by these can be mentioned.

  In the present invention, as the component (B), these polymer components may be used alone or in combination of two or more. In addition, the concentration of the component (B) is preferably 0.01 to 10 g / L, particularly in the range of 0.4 to 4 g / L in the composition of the final acidic copper plating bath. preferable.

  The brightener component, which is the component (C), has an effect of making the crystal arrangement of plating uniform. Examples of such compounds include mercaptoalkyl sulfonates, organic disulfide compounds, and dithiocarbamic acid derivatives.

Here, as the mercaptoalkyl sulfonate, for example, the general formula (IX)
HS-L ¹ -SO ₃ M (IX)
(In the formula, L ¹ represents a saturated or unsaturated alkylene group having 1 to 18 carbon atoms, and M represents an alkali metal)
The compound represented by these can be mentioned.

As an organic disulfide compound, for example, the general formula (X)
^{X 1 -L 2 SSL 3 -X 2} (X)
(In the formula, L ² and L ³ are each independently a saturated or unsaturated alkylene group having 1 to 18 carbon atoms, and X ¹ and X ² are each independently a sulfate group or a phosphate group)
The compound represented by these can be mentioned.

  Examples of the dithiocarbamic acid derivative include, for example, the general formula (XI)

(Wherein R ⁶ and R ⁷ each independently represent a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, L ⁴ represents an alkylene group having 3 to 6 carbon atoms, and X ³ represents a sulfate group or a phosphate group)
The compound represented by these can be mentioned.

  In the present invention, as the component (C), one type of brightener component may be used alone, or two or more types may be used in combination. Moreover, it is preferable that the density | concentration of this (C) component is 0.02-200 mg / L in the composition of the final acidic copper plating bath, and exists in the range of 0.2-5.0 mg / L especially. It is preferable.

  The additive composition for an acidic copper plating bath of the present invention having such a composition has excellent characteristics in any of the plating appearances such as the inside of the blind via hole and the through hole, the cornering portion and the leveling property of the plating surface. Have

Next, the acidic copper plating bath of the present invention will be described.
The acidic copper plating bath of the present invention has the basic bath composition containing (D) copper ions of 5 to 75 g / L and (E) organic acid and / or inorganic acid of 20 to 300 g / L. It is a plating bath formed by blending a bath additive composition.

  In this acidic copper plating bath, the compound serving as the copper ion source as the component (D) may be any copper compound that is usually dissolved in an acidic solution, and is not particularly limited. Specific examples of the copper compound include copper sulfate (preferably pentahydrate), copper oxide, copper chloride, copper carbonate, copper pyrophosphate, copper methanesulfonate, copper propanesulfonate, etc., propanol Examples include copper alkanol sulfonates such as copper sulfonate, copper acetate, copper citrate, and organic acids such as copper tartrate and salts thereof. These copper compounds may be used individually by 1 type, and may be used in combination of 2 or more type.

The concentration of the copper ion as the component (D) is preferably 5 to 75 g / L, more preferably 12 to 60 g / L in the composition of the acidic copper plating bath. In particular, when the acidic copper plating bath is for through-hole plating and resin film plating, it is 15 to 25 g / L as copper ions, and when it is for blind via-hole plating, it is 25 to 40 g / L as copper ions. Each is preferred.
The organic acid or inorganic acid as the component (E) is not particularly limited as long as it can dissolve copper.

  Preferable specific examples of the organic acid or inorganic acid include sulfuric acid, alkanesulfonic acids such as methanesulfonic acid and propanesulfonic acid, alkanolsulfonic acids such as propanolsulfonic acid, organic acids such as citric acid, tartaric acid, and formic acid. Is mentioned. These organic acids and inorganic acids may be used alone or in combination of two or more.

  The concentration of the organic acid or inorganic acid of component (E) is preferably 20 to 300 g / L, and more preferably 50 to 250 g / L in the composition of the acidic copper plating bath. In particular, when used for through-hole plating and resin film plating, 50 to 100 g / L is preferable, and when used for blind via-hole plating, 100 to 200 g / L is preferable.

  In the acidic copper plating bath of the present invention, in addition to the components (A), (B), (C), (D) and (E), chlorine ions as the component (F) are added at a concentration of 10 to 100 mg / L. It is preferable to make it contain with 20-70 mg / L especially.

  By using an acidic copper plating bath with such a composition, high-reliability copper plating treatment can be applied to substrates with minute holes such as through-holes and blind via holes, or resin films whose surfaces are coated with metals such as copper. Can be applied.

Next, the plating method of the present invention will be described.
The plating method of the present invention uses the above-mentioned acidic copper plating bath, (1) a method of plating a holed and conductive substrate, and (2) plating a resin film having a metal coating on the surface. There are two aspects of the method of processing.

  In the method (1) of plating the holed and conductive substrate, first, the holed substrate is made conductive. For example, the substrate is formed by drilling a substrate according to a conventional method, and has a hole diameter of 100 to 1000 μm, a hole diameter of about 30 to 300 μm, and a depth (resin layer thickness) of about 30 to 300 μm. A printed circuit board or the like having a blind via hole. In these substrates, through-holes and blind via holes may be mixed in the substrate, and further, trenches (grooves) for fine wiring may be mixed. Specific examples of these substrates include printed boards such as package boards on which IC bare chips are directly mounted.

  The conductive treatment of the substrate can be performed by a normal conductive treatment method, for example, metal (including carbon) coating treatment by electroless plating, sputtering, vapor deposition, or chemical vapor deposition (CVD). Etc. can be performed.

The substrate thus subjected to the conductive treatment is then subjected to copper plating in the acidic copper plating bath. The conditions for performing the copper plating in the acidic copper plating bath may follow the conditions of normal acidic copper plating. That is, the liquid temperature may be about 23 to 27 ° C., a DC power source may be used as a power source, and plating may be performed with a cathode current density of about 0.5 to 5.0 A / dm ² . In general, it is preferable to agitate the bath by aeration or the like. For example, for a substrate having a blind via hole, it is preferable to perform jet agitation in order to improve the ability of plating with respect to the blind via hole.

The plating time in the above method depends on the blind via hole existing on the substrate. That is, the time for copper plating evenly from the side surface portion to the bottom surface portion of the blind via hole on the substrate varies depending on the diameter and depth of the via hole. Therefore, it is necessary to determine the plating time in consideration of this. For example, in order to uniformly plate copper on a hole having a diameter of 60 μm and a depth of 40 μm, plating may be performed at a cathode current density of 2.0 A / dm ² for about 30 minutes. The plating thickness of the other portion is about 12 μm.

The plating time in the case of through-hole plating also varies depending on the diameter of the through-hole and the thickness of the substrate. For example, in order to uniformly plate copper with a substrate thickness of about 1.6 mm and a through-hole diameter of about 300 μm In this case, plating may be performed at a cathode current density of about 3.0 A / dm ² for about 50 minutes, and the plating thickness of the surface (portion other than the through hole) at this time is about 30 μm.

  In this manner, a copper plating film having good contactability with respect to the inside and corner of the blind via hole and through hole and the leveling property of the plating surface is formed, and a highly reliable plating process can be performed.

  Next, in the method of plating the resin film having the metal film formed on the surface (2), first, the metal film is formed on the resin film surface. In this case, a film is formed on the surface of a resin film such as polyimide or polyester having a thickness of about 12 to 50 μm with a metal such as copper, nickel or chromium having a thickness of about 100 to 500 nm by vacuum deposition, sputtering or the like. Is good.

Thus, the conditions which perform copper plating with the acidic copper plating bath of this invention on the resin film in which the metal film was formed in the surface may be the conditions of normal copper sulfate plating. That is, plating may be performed at a liquid temperature of about 23 to 27 ° C. and a cathode current density of about 1 to 3 A / dm ^{2 for} about 10 to 20 minutes. The plating thickness at this time is about 2 to 10 μm. In general, it is preferable to perform liquid agitation by aeration or the like.

  According to this method, even if the resin film having a metal film formed on the surface is plated with a thin thickness of about 3 to 5 μm, a smooth glossy plating surface can be obtained, and as a result, high reliability. Copper plating can be performed.

  When a resin film coated with a very thin metal is plated with a conventional acidic copper plating bath by means of vacuum deposition, sputtering, etc., if the plating thickness is less than 10 μm, the leveling effect of the additive is not exhibited, and the surface There is a problem that a rough surface state with many irregularities is not obtained and a glossy appearance cannot be obtained. On the other hand, by using the acidic copper plating bath of the present invention, even with such a thin plating thickness, the surface becomes a very fine crystalline state, and a good gloss appearance can be obtained. Needless to say, even if the plating thickness is thicker than this, a good gloss appearance can be obtained.

EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by these examples.
Example 1 Production of a novel leveling agent for plating (production of diallylethylmethylammonium ethyl sulfate monomer)
Into a 1 liter four-necked round bottom separable flask equipped with a stirrer, a thermometer, and a Dimroth type reflux condenser, 167.1 g (1.5 mol) of diallylmethylamine was charged and 232.5 g of diethyl sulfate ( 1.5 mol) was slowly added dropwise while maintaining the temperature at 20 to 50 ° C. And it was made to react at 50 degreeC for 24 hours. Next, 212.9 g of water for adjusting to 65% by weight was added to prepare an aqueous diallylethylmethylammonium ethylsulfate monomer aqueous solution, and this aqueous solution was mixed with sulfur dioxide without isolating diallylethylmethylammonium ethylsulfate. This was used for the copolymerization reaction.

(Production of a copolymer of diallylethylmethylammonium ethyl sulfate and sulfur dioxide)
After adding water for adjusting the monomer concentration to the resulting diallylethylmethylammonium ethylsulfate monomer aqueous solution (monomer content 1.5 mol), the sulfur dioxide is added to the monomer while cooling and stirring with ice water. An equimolar amount was added. Next, while maintaining the obtained monomer-sulfur dioxide mixture at a predetermined polymerization temperature, 52.0 g of an aqueous 28.5 wt% ammonium persulfate solution (3.0 wt% based on the monomer) was added in portions and copolymerized. Thus, a copolymer of diallylethylmethylammonium ethyl sulfate and sulfur dioxide was obtained as an aqueous solution.

A portion of the resulting solution was reprecipitated with acetone, and the resulting white solid was filtered off and dried in vacuo at 50 ° C. for 48 hours. The obtained IR spectrum of the white powdery copolymer, -SO ₂ to 1320 cm ^-1 and 1130 cm ^-1 - since the absorption due to sulfate in the absorption and 1220 cm ^-1 due to the observed, Jiariruechiru It is a copolymer of methylammonium ethyl sulfate and sulfur dioxide.

  The elemental analysis value of this solid was S = 18.8 to 19.3%. This value is close to that of a 1: 1 molar ratio of diallylethylmethylammonium ethyl sulfate to sulfur dioxide.

  The weight average molecular weight in terms of polyethylene glycol measured by gel permeation chromatography (GPC) of this copolymer was 1600, and the polymerization yield was 95.0%.

This copolymer was used as a leveling agent for an acidic copper plating bath in the following examples (hereinafter referred to as a leveling agent in Example 1).
Example 2 Evaluation of Acid Copper Plating Film Obtained by DC Power Supply Using a sample having a through hole, plating was performed in a copper sulfate plating bath having the composition described later, and uniform electrodeposition (throwing power characteristics) in the through hole and heat resistance physical properties (Crack occurrence rate) was evaluated. The details are as follows.

  As a sample substrate, a CEM-3 substrate (plate thickness 1.6 mm), which is a copper-clad laminate, with a through hole having a diameter of 0.3 mm was used. With respect to this sample substrate, an electroless copper layer was formed in a thickness of 0.4 μm in the through hole and on the surface of the substrate (hereinafter referred to as “conductive treatment”). For this electroless copper plating, a risertron process [manufactured by Sugawara Eugleite Co., Ltd.] was used.

Next, using the plating bath containing the leveling agent of Example 1 having the following composition, the substrate subjected to the conductive treatment was stirred for aeration at 25 ° C. and a cathode current density of 3 A / dm ² for 40 minutes. Acid copper plating was performed below.

<Composition of copper sulfate plating bath>
Copper sulfate 90g / L
Sulfuric acid 180g / L
Chloride ion 40mg / L
Polyethylene glycol ¹⁾ 500mg / L
SPS ²⁾ 1mg / L
Leveling agent of Example 1 1000 mg / L
_{[Note] 1) HO- (C 2 H} 4 O) n -H n = 90
_{2) NaO 3 S-C 3} H 6 -S-S-C 3 H 6 -SO 3 Na

The thus plated substrate was evaluated for “plating appearance”, “throwing power characteristics”, and “crack generation rate” using the following methods. The results are shown in Table 1 together with the plating conditions.
(1) Evaluation of plating appearance The appearance of the sample after plating was visually observed to evaluate the glossiness of the surface.
(2) Evaluation of throwing power The cross section of the substrate pattern portion is polished, and the positions of the through holes shown in FIG. 1 (six positions a to f) are measured, and the cross section is observed with a microscope to determine the plating thickness. It was measured. Then, the throwing power (%) was calculated by substituting the measured value into the following equation.

(3) Evaluation of crack occurrence rate The sample substrate after plating was immersed in a glycerol solution at 260 ° C. for 5 seconds, and then immediately immersed in a trichlorethylene solution at 25 ° C. for 15 seconds. The crack generation rate (%) (the ratio of occurrence of cracks in through-holes existing in the substrate) was confirmed when this was performed as 10 cycles.

Comparative Example 1
Instead of the copper sulfate plating bath in Example 2, plating was performed in the same manner as in Example 2 except that a conventional copper sulfate plating bath (general bath type) having the following composition was used. Each evaluation was performed on the substrate. The results are shown in Table 1 together with the plating conditions.

<Composition of copper sulfate plating bath>
Copper sulfate 90g / L
Sulfuric acid 180g / L
Chloride ion 40mg / L
TH-AD ¹⁾ 1ml / L
TH-comp. A ²⁾ 1 ml / L
Cu-BriteTH-MI ³⁾ 0.2ml / L
[Note] 1), 2), and 3) are product names manufactured by Ebara Eugene Corporation.

  As can be seen from Table 1, although the substrate plated in Example 2 and the substrate plated in Comparative Example 1 both had a glossy appearance and no cracks were observed at high temperatures, Regarding the throwing power characteristics, the value of Example 2 is 77.3%, which is far superior to that of Comparative Example 1 of 68.9%.

Example 3 Evaluation of Acid Copper Plating Film Obtained by DC Power Supply Using a sample having through holes, plating was performed in a copper sulfate plating bath having the composition described later, and the shape of the plating film at the through hole corner portion was evaluated. The details are as follows.

  As a sample substrate, a CEM-3 substrate (plate thickness: 1.6 mm), which is a copper-clad laminate, with a through hole having a diameter of 0.3 mm was used, and the conductive treatment was performed in the same manner as in Example 2.

Next, using the plating bath containing the leveling agent of Example 1 having the following composition, the conductive treatment substrate was subjected to 50 ° C. and a cathode current density of 2.4 A / dm ² for 50 minutes. Acid copper plating was performed under aeration stirring.

<Composition of copper sulfate plating bath>
Copper sulfate 100g / L
Sulfuric acid 180g / L
Chloride ion 40mg / L
Polyethylene glycol ¹⁾ 500mg / L
SPS ²⁾ 1.5mg / L
Leveling agent of Example 1 1000 mg / L
_{[Note] 1) HO- (C 2 H} 4 O) n -H n = 90
_{2) NaO 3 S-C 3} H 6 -S-S-C 3 H 6 -SO 3 Na

  With respect to the substrate plated in this manner, the cross section of the substrate pattern portion was polished, and the shape of the plating film at the through-hole corner portion was observed with a microscope. FIG. 2 shows a cross-sectional micrograph (200 ×) of the through-hole corner. In FIG. 2, 1 is a copper layer, 2 is an acidic copper plating film, 3 is a nickel plating film (provided for easy observation), and 4 is an insulating resin.

Comparative Example 2
Instead of the copper sulfate plating bath in Example 3, plating was performed in the same manner as in Example 3 except that a conventional copper sulfate plating bath (general bath type) having the following composition was used. About the board | substrate, the shape of the through-hole corner part was evaluated. FIG. 3 shows a cross-sectional photomicrograph (200 ×) of the through-hole corner. 3 are the same as those in the third embodiment.

<Composition of copper sulfate plating bath>
Copper sulfate 100g / L
Sulfuric acid 180g / L
Chloride ion 40mg / L
TH-AD ¹⁾ 2ml / L
TH-comp. A ²⁾ 2 ml / L
Cu-BriteTH-MI ³⁾ 0.2ml / L
[Note] 1), 2), and 3) are product names manufactured by Ebara Eugene Corporation.

As is clear by comparing the shapes of the acidic copper plating film 2 in FIGS. 2 and 3, the substrate plated in Example 3 is compared with the substrate plated in Comparative Example 2 in the through-hole corner portion. It can be seen that the acidic copper plating film is formed thick.
Example 4 Leveling in plating on rolled copper foil Using a flexible printed wiring board (FPC board) provided with a rolled copper foil, the rolled copper foil is plated in a copper sulfate plating bath having the composition described later, and the plating appearance The leveling property was evaluated. The details are as follows.

Using the plating bath containing the leveling agent of Example 1 shown in the composition shown below on the FPC board, acidic copper plating was performed at 25 ° C. and a cathode current density of 1.5 A / dm ² for 50 minutes under aeration stirring. Went.

<Composition of copper sulfate plating bath>
Copper sulfate 90g / L
Sulfuric acid 180g / L
Chloride ion 40mg / L
Polyethylene glycol ¹⁾ 500mg / L
SPS ²⁾ 1mg / L
Leveling agent of Example 1 1000 mg / L
_{[Note] 1) HO- (C 2 H} 4 O) n -H n = 90
_{2) NaO 3 S-C 3} H 6 -S-S-C 3 H 6 -SO 3 Na

  About the FPC board plated in this way, the appearance of the plating film was observed with a microscope, and the leveling property was evaluated. In FIG. 4, the microscope picture (66 times) of the plating film formed by plating to the rolled copper foil of an FPC board is shown.

Comparative Example 3
Instead of the copper sulfate plating bath in Example 4, a rolled copper foil for an FPC board was used in the same manner as in Example 4 except that a conventional copper sulfate plating bath (high performance type) having the following composition was used. Acidic copper plating was performed on the film, and the appearance of the plating film was observed with a microscope to evaluate the leveling property of the plated surface. In FIG. 5, the microscope picture (66 times) of the plating film formed by plating to the rolled copper foil of an FPC board is shown.

<Composition of copper sulfate plating bath>
Copper sulfate 100g / L
Sulfuric acid 180g / L
Chloride ion 40mg / L
Cu-Brite 21MU ¹⁾ 5ml / L
SPS ²⁾ 1mg / L
[Note] 1) Ebara-Udylite Co., Ltd., trade name _{2) NaO 3 S-C 3} H 6 -S-S-C 3 H 6 -SO 3 Na

  As is clear by comparing FIG. 4 and FIG. 5, the plated FPC substrate obtained in Example 4 has a smoother plating film than the plated FPC substrate obtained in Comparative Example 3, It turns out that it is excellent in leveling property.

Example 5 Evaluation of Attaching Property of Plating to Blind Via Hole Using a patterned substrate having a blind via hole (depth 35 μm, hole diameter 50 μm) as a sample substrate, a conductive treatment was performed in the same manner as in Example 1. Next, acidic copper plating was performed on the substrate using the plating bath containing the leveling agent of Example 1 having the following composition at 25 ° C. and a cathode current density of 3 A / dm ² for 25 minutes under aeration stirring. Went.

<Composition of copper sulfate plating bath>
Copper sulfate 90g / L
Sulfuric acid 180g / L
Chloride ion 40mg / L
Polyethylene glycol ¹⁾ 500mg / L
SPS ²⁾ 1mg / L
Leveling agent of Example 1 1000 mg / L
_{[Note] 1) HO- (C 2 H} 4 O) n -H n = 90
_{2) NaO 3 S-C 3} H 6 -S-S-C 3 H 6 -SO 3 Na

  With respect to the substrate plated in this manner, the cross section of the substrate pattern portion was polished, the cross section of the blind via hole was observed with a microscope, and the contact property of the plating to the blind via hole was evaluated. FIG. 6 shows a cross-sectional photomicrograph (200 ×) of the blind via hole after plating. Each symbol is the same as in the third embodiment.

Comparative Example 4
Instead of the copper sulfate plating bath in Example 5, plating was carried out in the same manner as in Example 5 except that a conventional copper sulfate plating bath (general bath type) having the following composition was used. About the board | substrate, the surrounding property with the plating to a blind via hole was evaluated. FIG. 7 shows a cross-sectional photomicrograph (200 ×) of the blind via hole after plating. Each symbol is the same as in the third embodiment.

<Composition of copper sulfate plating bath>
Copper sulfate 100g / L
Sulfuric acid 180g / L
Chloride ion 40mg / L
TH-AD ¹⁾ 2ml / L
TH-comp. A ²⁾ 2 ml / L
Cu-BriteTH-MI ³⁾ 0.2ml / L
[Note] 1), 2), and 3) are product names manufactured by Ebara Eugene Corporation.

  6 and 7, it is clear that the plating substrate obtained in Example 5 has improved plating coverage to the blind via hole than the plating substrate obtained in Comparative Example 4. I understand that

The leveling agent for plating of the present invention is used as one component of an additive composition for an acidic copper plating bath.
The acidic copper plating bath of the present invention containing the additive composition for acidic copper plating baths is highly reliable for a substrate having micropores such as through holes and blind via holes, or a resin film whose surface is coated with a metal such as copper. It is suitably used for copper plating treatment.

It is explanatory drawing which shows the plating thickness measurement position in the through hole for calculating | requiring throwing power. 6 is a cross-sectional micrograph of a through-hole corner portion of a substrate plated in Example 3. FIG. 6 is a cross-sectional photomicrograph of a through-hole corner portion of a substrate plated in Comparative Example 2. FIG. It is a microscope picture figure of the plating film on the rolled copper foil of the FPC board plated in Example 4. It is a microscope picture figure of the plating film on the rolled copper foil of the FPC board plated by the comparative example 3. 6 is a cross-sectional micrograph of a blind via hole of a substrate plated in Example 5. FIG. It is a cross-sectional microscope picture figure of the blind via hole of the board | substrate plated by the comparative example 4.

Explanation of symbols

1 Copper layer 2 Acidic copper plating film 3 Nickel plating film 4 Insulating resin

Claims (11)

Formula (I)

(In the formula, R ¹ and R ² are each independently a methyl group, an ethyl group or a hydroxyethyl group, but R ¹ and R ² are not both a hydroxyethyl group, and R ³ is a methyl group or an ethyl group. )
A diallyldialkylammonium alkyl sulfate unit represented by formula (II):

A leveling agent for plating comprising a diallyldialkylammonium alkylsulfate-sulfur dioxide copolymer containing a sulfur dioxide unit represented by: The leveling agent for plating according to claim 1, wherein in general formula (I), R ¹ is an ethyl group, R ² is a methyl group, and R ³ is an ethyl group.   The leveling agent for plating according to claim 1 or 2, which is an alternating copolymer having a molar ratio of diallyldialkylammonium alkylsulfate units / sulfur dioxide units of 1/1.   (A) An additive composition for an acidic copper plating bath, comprising the leveling agent for plating according to claim 1, 2 or 3, (B) a polymer component, and (C) a brightener component.   The additive composition for an acidic copper plating bath according to claim 4, comprising (A) component 0.01 to 5 g / L, (B) component 0.01 to 10 g / L, and (C) component 0.02 to 200 mg / L. object.   (B) The polymer component is at least one selected from polyethylene glycol, polypropylene glycol, pluronic surfactant, tetronic surfactant, polyethylene glycol glyceryl ether and polyethylene glycol dialkyl ether. Or the additive composition for acidic copper plating baths of 5.   The additive composition for an acidic copper plating bath according to claim 4, 5 or 6, wherein (C) the brightener component is at least one selected from mercaptoalkyl sulfonates, organic disulfide compounds, and dithiocarbamic acid derivatives.   The basic bath composition containing (D) copper ions of 5 to 75 g / L, (E) organic acids and / or inorganic acids of 20 to 300 g / L, for an acidic copper plating bath according to any one of claims 4 to 7. An acidic copper plating bath obtained by blending an additive composition.   Furthermore, (F) The acidic copper plating bath of Claim 8 containing 10-100 mg / L of chlorine ions.   A method for plating a substrate, comprising subjecting a holed and electrically conductive substrate to a plating treatment using the acidic copper plating bath according to claim 8 or 9.   A resin film plating method comprising plating a resin film having a metal film formed on the surface thereof in the acidic copper plating bath according to claim 8 or 9.

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