KR20140143764A - Method for promoting adhesion between dielectric substrates and metal layers - Google Patents

Abstract

The present invention relates to novel processes for metallization of dielectric substrate surfaces that are applied with an organosilane composition and then oxidized. The method allows the metal plated surfaces to exhibit high adhesion between the substrate and the plated metal while simultaneously leaving the smooth substrate surface intact.

Description

[0001] METHOD FOR PROMOTING ADHESION BETWEEN DIELECTRIC SUBSTRATES AND METAL LAYERS [0002]

The present invention relates to novel processes for metallization of a dielectric substrate surface coated with a silane composition. The method allows the metal plated surfaces to exhibit high adhesion between the substrate and the plated metal while simultaneously leaving the smooth substrate surface intact.

Various methods of metallizing dielectric substrate surfaces are known. In wet chemical methods, the surfaces to be metallized are first metallized, electrolytically metallized, or directly electrolytically metallized, if necessary, after being first catalysed and then electrolessly metallized, after appropriate pretreatment .

EP 0 616 053 A1 discloses a method for the direct metallization of dielectric substrate surfaces, wherein the surfaces are first treated with a cleaner / conditioner solution and then treated with an activator solution, for example a palladium Treated with a solution of a colloidal solution and then with a solution comprising a compound of a metal which is more precious than tin as well as alkali hydroxide and complexing agent. The surfaces may then be treated in a solution containing a reducing agent and finally metallized by electrolysis.

WO 96/29452 relates to a process for the selective or partial electrolytic metallization of the surfaces of substrates made from an electrically nonconductive, i. E., Dielectric material, secured to plastic-coated holding elements, for the purpose of a coating process. The proposed process comprises: a) pre-treating the surface with an etching solution containing chromium (VI) oxide; B) treating the surface with a colloidal acidic solution of palladium- / tin compounds, taking care to prevent prior contact with the adsorption-enhancing solution; c) a solution comprising a soluble metal compound that can be reduced by the tin (II) compound, an alkali or alkaline earth metal hydroxide, and a complexing agent for the metal in an amount sufficient to prevent precipitation of at least the metal hydroxide Processing; d) treating the surface with an electrolytic metallization solution. Such methods are particularly suitable for ABS (acrylbutadiene styrole) and ABS / PC (polycarbonate) based plastic substrates.

Alternatively, conductive polymers may be formed on the dielectric substrate surface to provide a first conductive layer for subsequent metal plating of the surface.

US 2004/0112755 A1 discloses a method of making a substrate, comprising: contacting a substrate surface with a water soluble polymer, for example, thiophene; Treating the substrate surface with a permanganic acid solution; Treating the substrate surface with an acidic aqueous solution or acidic microemulsion of an aqueous base comprising at least one thiophene compound and at least one alkanesulfonic acid selected from the group consisting of methanesulfonic acid, ethanesulfonic acid and ethane disulfonic acid, ; Direct electrolytic metallization of an electrically non-conductive substrate surface comprising electrolytically metallizing the substrate surface.

US 5,693,209 relates to a process for direct metallization of a circuit board having nonconductive surfaces, comprising the steps of: reacting an alkaline permanganate alkali solution with a nonconductive surface to form chemically adsorbed manganese dioxide on a nonconductive surface; Forming an aqueous solution of a weak acid and a pyrrole or pyrrole derivative and a soluble oligomer thereof; Contacting an aqueous solution comprising a pyrrole monomer and an oligomer thereof with a nonconductive surface chemically adsorbed on manganese dioxide to form an adhesive, electrically conductive, insoluble polymer product on the surface of the nonconductive body; And direct electrodeposition of the metal onto the nonconductive surface where the insoluble adhesive polymer product is formed. The oligomer is advantageously formed in an aqueous solution comprising 0.1 to 200 g / l of the pyrrole monomer at a temperature between room temperature and the point of the solution.

US 4,976,990 relates to electroless metallization of dielectric through-hole surfaces in metallization of dielectric substrate surfaces, especially in double-sided or multilayer printed circuit boards. The methods involve roughening the surface and subsequently applying the silane composition to such a treatment surface. The substantial roughening of the surface occurs when the process is performed in the processing steps of this sequence. The method disclosed in this patent comprises, in lines 61 to 65, a micro-etching solution used to remove the oxide film from the metal foil. However, the method is not suitable for obtaining good adhesion between a substrate material and a subsequent plated metal layer in accordance with the method of the present invention.

A similar method is disclosed in WO 88/02412.

EP 0 322 233 A2 employs polymerizable silane, application of a solution containing diborane, etching in solutions containing sodium hydroxide and hydrogen peroxide, and finally application of a silver metal layer to form ultrafine And a method for generating a pattern. Such a method is not suitable for producing an adhesive metal film on a substrate according to the method of the present invention.

All of the methods described require substantial roughening of the surface of the non-conductive dielectric substrate prior to metallization to ensure sufficient adhesion between the substrate and the plated metal layer. Since roughening is used to prepare the surface of a dielectric substrate, it has generally been considered necessary. This is because the roughening has been considered necessary to achieve good adhesion between the substrate and the metal layer.

However, a rough surface gives the functionality of a metal plated surface for use as a conductor line, for example, in electronic device applications.

Continued miniaturization of features, such as HDI printed circuit boards, IC substrates, etc., requires more advanced manufacturing methods than conventional methods such as the formation of circuits by printing and etch methods. Such features require that the surface of the substrate be roughened to a limited extent.

It is an object of the present invention to provide a method for metallization of a dielectric substrate surface without substantially roughening the surface while still achieving high adhesion between the substrate and the metal layer.

This object is achieved by a method of treating the surface of the dielectric substrate to prepare a surface of the dielectric substrate for subsequent wet chemical plating,

(i) treating the surface with a solution comprising at least one organosilane compound;

(ii) treating the surface with a solution comprising an oxidizing agent selected from aqueous acidic or alkaline solutions of the permanganate salt, and then

(iii) metallizing the substrate after step (ii) with a wet chemical plating process

In this order.

Figure 1 illustrates a method of manufacturing a fine line circuit known in the art as a semi-additive process (SAP).
Figure 2 shows the surface after permanganate treatment of the GX92 substrate material according to Example P12.
Figure 3 shows the surface after permanganic treatment of the GX92 substrate material treated with an alkaline permanganic acid solution according to the conditions known in the state of the art.

According to the present invention, the substrate is first treated in step (i) with a composition comprising an organosilane compound.

The organosilane compound is preferably applied as a solution, preferably as a solution of an organic solvent having a high boiling point in the range of 60 to 250 占 폚 and more preferably in the range of 80 to 200 占 폚. Within the meaning of the present invention, the organic solvent is a polar organic solvent suitable for dissolving the silane compound.

Suitable organic solvents include alcohols, ethers, amines and acetates. Examples are ethanol, 2-propanol, tetrahydrofuran, ethylene glycol, diethylene glycol, 2-isopropoxyethanol (IPPE), di (propylene glycol) methyl ether acetate (DPGMEA) , N-methylpyrrolidone (NMP), dimethylformamide, dimethylacetamide, ethanolamine, propylene glycol methyl ether acetate (PMA), half-esters and half-ethers of ethylene glycol.

The concentration of the organosilane may vary over a wide range depending on the application and the particular organosilane compound. Suitable concentrations can be obtained by routine experimentation. Suitable concentrations will generally vary as low as 0.2 wt.% To 30 wt.%, Preferably 0.5 wt.% To 20 wt.%, Even more preferably 1 wt.% To 8 wt.%.

Contacting the dielectric substrate with a solution containing an organosilane according to process step (i) by dipping or immersing the substrate in the solution; Or by spraying a solution onto the substrate. Contacting the substrate with a solution comprising the organosilane according to process step (i) is performed at least once. Alternatively, the contacting may be carried out several times, preferably two to ten times, more preferably two to five times, even more preferably one to three times. The most preferable contact is one to two times.

Contacting the substrate with a solution comprising an organosilane according to method step (i) is carried out for a time period ranging from 10 seconds to 20 minutes, preferably from 10 seconds to 10 minutes, and most preferably from 10 seconds to 5 minutes do.

Contacting the substrate with a solution comprising organosilane according to process step (i) is carried out at a temperature in the range of from 15 to 100 캜, preferably from 20 to 50 캜, most preferably from 23 to 35 캜.

The organosilane compound is preferably a compound represented by the following formula

A _(4-x) SiB _x

Lt; RTI ID = 0.0 >

In the equation

Each A is independently a hydrolysable group and

x is 1 to 3,

Each B is independently selected from the group consisting of C ₁ -C ₂₀ alkyl, aryl,

C _n H _2n X

≪ / RTI > is selected from the group consisting of

In the equation

n is from 0 to 15, preferably from 0 to 10, even more preferably from 1 to 8, most preferably 1, 2, 3, 4

X is selected from the group consisting of amino, amido, hydroxy, alkoxy, halo, mercapto, carboxy, carboxyester, carboxamide, thiocarboxamide, acyl, vinyl, allyl, styryl, epoxy, epoxycyclohexyl, glycidoxy, Is selected from the group consisting of isocyanato, isocyanato, thiocyanato, thioisocyanato, ureido, thioureido, guanidino, thioglycidoxy, acryloxy and methacryloxy groups; Or X is a residue of a carboxy ester; Or X is Si (OR) ₃ , wherein R is a C ₁ -C ₅ alkyl group.

Preferably, the hydrolysable group A is selected from the group consisting of -OH, -OR ¹ , wherein R ¹ is C ₁ -C ₅ alkyl, - (CH ₂ ) _y OR ² wherein y is 1, 2 or 3 R ² is H or C ₁ -C ₅ alkyl, -OCOR ³ wherein R ³ is H or C ₁ -C ₅ alkyl.

If B is an alkyl group it is preferably C ₁ -C ₁₀ alkyl, even more preferably a C ₁ -C ₅ alkyl group such as methyl, ethyl, propyl or isopropyl. Preferred aryl groups are phenyl and benzyl groups which are substituted or unsubstituted. Preferred is an amino aryl group -NH (C ₆ H _5).

Within the meaning of the present invention, the functional group X can be further functionalized. For example, X = amino includes alkylamine or arylamine substituted amines such as 3- (N-styrylmethyl-2-aminoethylamino).

When the functional group X is Si (OR) ₃ , R is preferably methyl, ethyl, propyl or isopropyl.

Examples of specific classes of compounds in the above formulas are vinylsilane, aminoalkylsilane, ureidoalkylsilane ester, epoxyalkylsilane and methacryloalkylsilane ester, wherein the reactive organic functionalities are vinyl, amino, Epoxy, and methacryloxy. Examples of vinylsilanes are vinyltrichlorosilane, vinyltriethoxysilane, vinyltrimethoxysilane, vinyl-tris- (beta (2) -methoxyethoxy) silane and vinyltriacetoxysilane. Examples of aminoalkylsilanes which are preferred organosilanes for use in the present invention include gamma (3) -aminopropyltriethoxysilane, gamma-aminopropyltrimethoxysilane, N-beta- (aminoethyl) Gamma-aminopropyltrimethoxysilane, and N '- (beta-aminoethyl) -N- (beta-aminoethyl) -gamma-aminopropyltrimethoxysilane. Suitable ureidoalkylsilane esters are gamma-ureido alkyltriethoxysilane, while suitable epoxyalkylsilanes include beta- (3,4-epoxycyclohexyl) -ethyltrimethoxysilane and gamma glycidoxypropyltrimethoxysilane to be. Useful methacryloxy silane esters are gamma-methacryloxypropyltrimethoxysilane and gamma-methacryloxypropyl-tris- (beta-methoxyethoxy) silane.

The at least one organosilane compound may be a monomeric organosilane compound or an oligomeric organosilane compound and is obtained by (partial) hydrolysis and condensation of the monomeric organosilane compound according to the present invention prior to deposition on the surface of the dielectric substrate.

The hydrolysis and condensation of organosilane compounds is well known in the art. For example, a monomeric organosilane compound reacts with an acidic catalyst, such as acetic acid or dilute hydrochloric acid, to a clear solution of an oligomeric organosilane compound derived from the monomeric organosilane compound.

Such oligomeric silanes derived from monomeric organosilane compounds by hydrolysis according to the present invention should be included within the scope of the present invention.

Optionally, the substrate may be heat treated after method step (i). Such treatment is generally carried out at a temperature between 60 and 200 ° C, more preferably between 80 and 150 ° C. The treatment time may vary, for example, between 1 and 30 minutes, preferably between 1 and 10 minutes.

Thereafter, the substrate is treated with a solution comprising an oxidizing agent in step (ii) selected from aqueous acidic or alkaline solutions of permanganate salts.

Surprisingly, oxidizers other than permanganates, such as mixtures of hydrogen peroxide and sulfuric acid or chromic acid, are not suitable for the process according to the invention because they lead to a sufficient adhesion between the substrate and subsequently the plated metal layer It was because I did not. This is unexpected because the prior art teaches that all oxidizers result in essentially the same surface modification.

Alkaline solutions of permanganates, such as sodium permanganate or potassium, are preferred. The solution preferably comprises 20 - 100 g / l permanganate ion and 10 - 40 g / l hydroxide ion. A preferred hydroxide ion source is sodium hydroxide or potassium.

Contacting the dielectric substrate with a solution containing an oxidizing agent according to method step (ii) comprises dipping or immersing the substrate in the solution; Or by spraying a solution onto the substrate.

Contacting the substrate with a solution comprising an oxidizing agent according to process step (ii) is carried out for a period of time ranging from 30 seconds to 30 minutes, preferably from 30 seconds to 10 minutes.

Contacting the substrate with a solution comprising an oxidizing agent according to method step (ii) is carried out at a temperature in the range of from 20 to 95 캜, preferably from 50 to 85 캜.

In one embodiment of the invention, the method comprises the steps of:

(i) treating the surface with a solution comprising at least one organosilane compound at a temperature between 15 and 50 < 0 > C for a time period between 10 seconds and 10 minutes

(ii) Average surface roughness Ra of 20 to 100 g / l for a time period between 1 and 30 minutes at a temperature between 20 and 95 ° C to obtain a roughened surface of less than 150 nm Treating the surface with a solution comprising an oxidizing agent selected from an alkaline aqueous solution of permanganate ions.

Surface roughness Ra of less than 150 nm may be between 50 and 150 nm, preferably between 60 and 130 nm, and even more preferably between 70 and 120 nm.

Various types of dielectric substrates can be metallized by the method according to the present invention. The metallization is performed by a wet chemical plating method. Such plating methods include electroless, immersion and electrolytic plating processes, usually performed in aqueous solutions.

The dielectric substrates to be metallized can be selected from the group including plastics, plastic-glass, and plastic-ceramic composites.

Plastics include acrylonitrile-butadiene-styrene-copolymer (ABS copolymer); Polyamide; A mixture of at least one other polymer different from the ABS copolymer and the ABS copolymer; Polycarbonate (PC); ABS / PC blend; Epoxy resin; Bismaleimide-triazine resin (BT); Cyanate ester resins; Polyimide; Polyethylene terephthalate (PET); Polybutylene terephthalate (PBT); Polylactic acid (PLA); Polypropylene (PP); ≪ / RTI > and polyesters.

Also, dielectric substrates used in the manufacture of printed circuit boards can be used. Such materials typically consist of an epoxy-based material, such as an epoxy blend, such as an epoxy-benzotriazole blend, an epoxy-cyanate-blend, an epoxy-propylene blend or an epoxy-polyimide blend.

Various methods of plating metal on a substrate by applying a wet chemical plating method to step (iii) are known to those skilled in the art. According to the present invention, the wet chemical plating method is preferably an electrolytic plating method, an immersion plating process or an electroless plating method.

Next, the dielectric substrates, for example plastic objects, can be metallized after activation by using electroless metallization methods or alternatively by using a direct plating method (electroplating method) . The object is first cleaned, for example, by applying a noble metal or conductive polymer, and then finally metallized.

Typical activation of dielectric substrates such as printed circuit boards for subsequent metal plating is performed as follows:

Preferably, the first conductive layer comprises copper and is deposited by electroless plating. Preferably in this case, the substrate is activated by deposition of a solution containing noble metal-containing colloid or noble metal ions, for example, before electroless deposition of copper. The most preferred activation is due to the deposition of palladium-tin colloid or palladium ions. Such methods are well known in the art and known to those skilled in the art.

Instead of copper, the first conductive layer may comprise nickel.

Exemplary, non-limiting pretreatment processes, particularly for printed circuit board laminates and other suitable substrates, include the following steps:

a) contacting the substrate with a solution of an activator comprising a colloidal or ionic catalytic metal, such as a noble metal, preferably palladium, to render the surface of the substrate catalytically active;

And, optionally, especially where the activator comprises an ionic catalytic metal,

b) contacting the substrate with a reducing agent, wherein the metal ions of the ionic activator are reduced to metal elements,

Alternatively, if the activator comprises a colloidal catalytic metal,

c) contacting the substrate with an accelerator, wherein contacting the substrate with an accelerator wherein components of the colloid, e.g., protective colloid, are removed from the catalytic metal.

The method according to the invention is particularly suitable for the fabrication of fine line circuits. This is shown in FIG.

A method for the fabrication of fine line circuits as is known in the art is a semiadditive process (SAP), which begins with the dielectric build-up layer 1 and the dielectric build-up layer 1, For example, a copper region, which may be the contact region 2, and a second dielectric layer 3 attached to the backside of the dielectric build-up layer 1. Such a substrate is shown in Fig. At least one opening 4, such as a blind microvia, is formed, for example, by laser drilling in the build-up layer 1, which extends through the substrate to the copper region 2 on the backside of the build- (Fig. 1B). The dielectric surface of the build-up layer 1 is subjected to a desmear process in the next step, which results in a roughened upper surface 5a of the build-up layer 1 and a dielectric sidewall of the at least one opening 4, To the roughened surface 5b (Fig. 1 (c)).

For example, by further depositing a noble metal-containing activator, additional activation of the roughened top surface 5a and roughened sidewalls 5b is required for subsequent electroless plating of copper. Next a conductive seed layer 6, typically made of copper, is deposited on the roughened top surface 5a of the build-up layer 1 and the roughened sidewalls 5b of the at least one opening 4. [ (Fig. 1 (d)). Such a conductive layer 6 usually has a thickness of from 0.8 μm to 1.5 μm, in order to provide a) sufficient electrical conductivity on the roughened upper surface 5a for the continuous electroplating of copper and b) It is also necessary to ensure that sufficient electrical conductivity is provided to the roughened sidewalls 5b of the at least one opening 4 during the plating.

A thicker layer of copper 8 is then deposited on the roughened and activated top surface of the build-up layer 1 into the openings of the patterned resist layer 7, Electroplating is selectively performed on the cottonized and activated dielectric walls (Figs. 1E-1F). The patterned resist layer 7 is removed (FIG. 1 g) and those portions of the conductive layer 6 that are not covered by the electroplated copper 8 are removed by differential etching (FIG. 1 h). Such a process is disclosed, for example, in US 6,278,185 B1 and US 6,212,769 B1.

A method of fabricating a fine line circuit on a printed circuit board comprises the steps of:

(i) a dielectric dielectric build-up layer (1) having a second dielectric layer (3) attached to the backside of the contact region (2) and the n-dielectric build-up layer (1) Providing a substrate,

(ii) forming at least one opening (4) in the build-up layer (1) through the substrate to the contact region (2)

(iii) treating the surface with a solution comprising at least one organosilane compound;

(iv) treating said surface with a solution comprising an oxidizing agent,

(v) depositing a conductive seed layer (6) on the upper surface (5a) of the dielectric build-up layer (1) and on the dielectric side wall (5b) of the at least one opening (4)

(vi) selectively depositing a copper layer 8 in the openings of the resist layer 7 patterned by electroplating

In this order.

Next, the dielectric substrates, for example plastic objects, can be metallized after activation by using electroless metallization methods or alternatively by using a direct plating method (electroplating method) . The object is first cleaned, for example, by applying a noble metal or conductive polymer, and then finally metallized.

Typical activation of dielectric substrates for subsequent metal plating is performed as follows:

Plastics are activated for electroless metallization using an activator including a noble metal and then electroless metallized. The thicker metal layer can then also be applied later electrolytically. In the case of direct plating methods, the etched surface is usually treated with a solution of palladium colloid and then treated with an alkaline solution containing copper ions which form a complex with the complexing agent. Thereafter, the object may then be directly electrolytically metallized (EP 1 054 081 B1).

A suitable metallization sequence in step (iii) comprises the following steps:

A) treating a solution or a compound of the colloid, in particular with a salt of a metal (precious metal) VIIIB or IB of the Periodic Table of the Elements, in particular a palladium / tin colloid;

And

B) Electrolytic metallization step using metallization solution

≪ / RTI >

In one embodiment of the invention, the substrate is a dielectric substrate

iii. The step of metal plating the substrate by applying the wet chemical plating method comprises:

iiia. Contacting the substrate with a noble metal colloidal or noble metal ion containing solution;

iiib. Contacting the electroless metal plating solution with the substrate; And

iiic. Contacting the electrolytic metal plating solution with the substrate

.

In one embodiment of the present invention at least one of the following additional method steps is performed in the whole process step iii.

iii1. Dipping objects or substrates into a pre-dipping solution;

iiia1. Rinsing objects or substrates in the rinsing solution;

iiia2. Treating objects or substrates in a promoting or reducing agent solution;

iiib1. Rinsing objects or substrates in the rinsing solution; And

iiic1. Rinsing the objects or substrates in the rinsing solution.

In these preferred embodiments, these additional method steps are performed when the objects or substrates are metallized using electroless metallization methods, in which the first metal layer is applied to objects or substrates using an electroless method it means.

The promoting solution is preferably a process step iiia. To remove components of the colloidal solution, for example, protective colloids. Method steps iia. A solution of an acid such as sulfuric acid, hydrochloric acid, citric acid or tetrafluoroboric acid is preferably used as an accelerating solution so that a protective colloid (tin compound) is added to the colloid solution Remove.

When a solution of a noble metal ion, for example an acidic solution of a hydrochloric acid solution or a silver salt of palladium chloride, is used in process step (ii) a., A reducing agent solution is used. In this case, the reducing agent solution also hydrochloric acid solution and, for example, include tin (II) chloride, or that other reducing agents, such as NaH ₂ PO ₂ or borane or a boron hydride, such as alkali or soil alkali borane or dimethyl amino borane Lt; / RTI >

On the other hand, it is preferred that the objects or substrates are metallized directly (without electroless metallization) using an electrolytic metallization process rather than electroless metallization.

In this embodiment of the invention, the substrate is a dielectric substrate

iii. The step of metal plating the substrate by applying the wet chemical plating method comprises:

iiia. Contacting the substrate with a noble metal colloid;

iiib. Contacting the substrate with a conversion solution to cause a sufficiently electrically conductive layer to be formed on the surface of the substrate for direct electrolytic metallization; And

iiic. Contacting the electrolytic metal plating solution with the substrate

.

Method steps iiid., Iiie. And iiif. Is performed in the given sequence, but not necessarily immediately after the other. For example, a plurality of rinsing steps may be performed after the method steps. Method steps iid in this embodiment. And iie. Acts as an activation step.

The conversion solution preferably serves to create a layer that is sufficiently electrically conductive on the surfaces of objects or substrates, and subsequently allows direct electrolytic metallization, without the preceding electroless metallization. Method steps iid. Is a palladium / tin colloid, the alkaline solution containing copper ions complexed with a complexing agent is preferably used as a conversion solution. For example, the conversion solution may comprise an organic complexing agent such as tartaric acid or ethylenediaminetetraacetic acid and / or one of its salts, such as a copper salt, such as copper sulfate:

Conversion solution:

(i) soluble metal salts of Cu (II), Ag, Au or Ni or mixtures thereof,

(ii) 0.05 to 5 mol / l of a Group IA metal hydroxide and

(iii) a complexing agent for the metal ion of the metal salt.

The treatment liquid described later is preferably aqueous.

In a preferred embodiment of the present invention, a solution of the colloid of the noble metal of group VIIIB or IB of the element periodic table used in the activation step is an activator solution comprising palladium / tin colloid. The colloidal solution preferably comprises palladium chloride, tin (II) chloride and hydrochloric acid or sulfuric acid. The concentration of palladium chloride is preferably ^5-200 mg / l, particularly preferably 20-100 mg / l and most preferably 30-60 mg / l based on Pd ²⁺ . The concentration of tin (II) chloride is preferably from 0.5 to 20 g / l, particularly preferably from 1 to 10 g / l and most preferably from 2 to 6 g / l based on Sn ²⁺ . The concentration of hydrochloric acid is preferably 100-300 ml / l (37% by weight HCl). In addition, the palladium / tin colloid solution also preferably contains tin (IV) ions which are produced through oxidation of tin (II) ions. The temperature of the colloidal solution is preferably 20-50 ° C and particularly preferably 30-40 ° C. The treatment time is preferably from 0.5 to 10 minutes, particularly preferably from 2 to 5 minutes and most preferably from 3.5 to 4.5 minutes.

Alternatively, the colloidal solution may also comprise other metals of Group VIIIB or IB of the Periodic Table of the Elements, such as platinum, iridium, rhodium, gold or silver or mixtures of these metals. Basically, it is possible that the colloid is not stabilized with tin ions as protective colloid but instead stabilized with other protective colloids used, such as organic protective colloids, such as polyvinyl alcohol.

If a solution of noble metal ions is used in place of the colloid solution in the activation step, it is preferred to use a solution comprising an acid, especially hydrochloric acid and a noble metal salt. The noble metal salt may be, for example, a palladium salt, preferably palladium chloride, palladium sulfate or palladium acetate, or a silver salt, such as acetic acid. Alternatively, noble metal complexes, such as palladium complex salts, such as salts of palladium amino complexes, may also be used. The noble metal compound is present in a concentration of from 20 mg / l to 200 mg / l based on, for example, Pd ²⁺ , based on, for example, a noble metal. The solution of the noble metal compound may be used at 25 占 폚 or at a temperature of from 15 占 폚 to 70 占 폚.

Prior to contacting the objects or substrates with the colloidal solution, the objects or substrates are preferably first contacted with a pre-dipping solution of the same composition as the colloid solution, but without the metal of the colloid and its protective colloid, In the case of a palladium / tin colloid solution, it is meant that the colloidal solution also contains hydrochloric acid if it also contains hydrochloric acid. Objects or substrates are in direct contact with the colloidal solution after treatment in the pre-dipping solution, without rinsing the objects or substrates.

After treating the objects or substrates with the colloidal solution, they are typically rinsed and then contacted with the promoting solution to remove protective colloids from the surfaces of the objects or substrates.

If objects or substrates are treated with a solution of noble metal ions instead of a colloid solution, they will first be subjected to a reduction treatment after being rinsed. The reducing agent solution used in these cases typically comprises hydrochloric acid and tin (II) chloride. The solution of the noble metal compound is a hydrochloric acid solution of palladium chloride. However, it is preferable to use an aqueous solution of NaH ₂ PO ₂ . Further, when the solution of the noble metal compound is a neutral or alkaline solution of complex stabilized Pd sulfate or chloride, it is preferable to use an aqueous solution of DMAB (dimethylaminoborane) or sodium borohydride in the reduction treatment.

For electroless metallization, objects or substrates may first be rinsed with a reducing agent solution or after treatment, and then electrolessly plated with, for example, nickel. For example, a conventional nickel bath containing many substances including nickel sulfate, hypophosphite such as sodium hypophosphite as a reducing agent and an organic complexing agent and a pH adjusting agent (for example, a buffer) something to do.

Alternatively, usually a copper salt, such as copper sulfate or copper hypophosphite, and also a reducing agent such as formaldehyde or hypophosphite, such as an alkali or ammonium salt, or a hypophosphorous acid, and also one or more complexing agents such as Tartaric acid, and an electroless copper bath containing a pH adjusting agent such as sodium hydroxide may be used.

Any metal deposition bath may be used to form subsequent electrolytic metallization, such as nickel, copper, silver, gold, tin, zinc, iron, lead, or alloys thereof. This type of deposition bath is well known to those skilled in the art. A Watts nickel bath is usually used as a bright nickel bath containing nickel sulfate, nickel chloride and boric acid and saccharin as additives. As a bright copper bath, for example, compositions comprising copper sulfate, sulfuric acid, sodium chloride and an organic sulfur compound present as an additive in the low oxidation stage, for example, as an organic sulfide or disulfide, are used .

If a direct electroplating process is used, that is, the first metal layer is not electrolessly deposited, but is electrochemically deposited after processing of objects or substrates with the conversion solution and after optional subsequent rinsing, the electrolytic metallization bath, For example, a nickel strike bath, which is preferably constructed based on a watt nickel bath, is used. For example, baths of this type include nickel sulfate, nickel chloride and boric acid and saccharin as additives.

The treatment of objects or substrates of the process according to the invention is preferably carried out in a conventional dipping process wherein the objects or substrates are dipped into solutions in containers in which each treatment takes place. In this case, objects or substrates may be fastened to a rack or filled into drums and dipped into solutions. Fixation to the racks is desirable because a more directed directed transmission of ultrasound energy to objects or substrates is possible through the racks. Alternatively, objects or substrates may be processed in so-called ken-bonded processing plants where they are placed, for example, on ladders, continuously transported in a horizontal direction through the plant, .

In another embodiment of the present invention, direct metallization can be obtained by employing a conductive polymer on the surface of the dielectric substrate, for example as described in US 2004/0112755 A1, US 5,447,824, and WO 89/08375 A have.

EP 0 457 180 A2 discloses a method of metallizing dielectric substrates, which comprises first forming a manganese dioxide layer on a substrate and then treating the surface with an acidic solution comprising pyrrole and methanesulfonic acid. Instead of pyrrole, the solution may also contain thiophene. Due to this treatment, an electrically conductive polymer layer is formed. The electrically conductive layer may eventually be electrolytically metallized. Alternatively, thiophene and aniline may be applied instead of pyrrole. Such a method is suitable for use as an activation step and subsequently to metallize non-conductive substrates according to the present invention.

In this embodiment of the invention, the substrate is a dielectric and the following additional method steps are carried out for the metallization of the substrate in step iii:

iiic. Contacting the substrate with a water soluble polymer;

iiid. Treating the substrate with a permanganic acid solution;

iiie. Treating the substrate with an acidic aqueous solution or an acidic microemulsion of an aqueous base comprising at least one thiophene compound and at least one alkanesulfonic acid selected from the group comprising methanesulfonic acid, ethanesulfonic acid and ethane disulfonic acid, ;

And

iv. The step of metal plating the substrate by applying the wet chemical plating method comprises:

ivb. Contacting the electrolytic metal plating solution with the substrate

.

Step ic. The water-soluble polymer used in the present invention is preferably a copolymer of polyvinylamine, polyethyleneimine, polyvinylimidazole, alkylamine ethylene oxide copolymer, polyethylene glycol, polypropylene glycol, ethylene glycol and polypropylene glycol, polyvinyl alcohol, poly Acrylate, polyacrylamide, polyvinylpyrrolidone, and mixtures thereof. The concentration of the water-soluble polymer is in the range of 20 mg / l to 10 g / l.

The solution of the water-soluble polymer is prepared by dissolving the polymer in a solvent such as ethanol, propanol, ethylene glycol, diethylene glycol, glycerin, dioxin, butyrolactone, N-methylpyrrolidone, dimethylformamide, dimethylacetamide, And a water-soluble organic solvent selected from the group consisting of water-soluble organic solvents. The water-soluble organic solvent may be used by being poured into pure form or water. The concentration of the water-soluble organic solvent is in the range of 10 ml / l to 200 ml / l. The solution of the water soluble polymer is maintained at a temperature in the range of from 25 캜 to 85 캜, Lt; / RTI > for 15 seconds to 15 minutes.

Next, the dielectric substrate is subjected to the step id. Lt; / RTI > solution. The permanganate ion source may be any water soluble permanganate compound. Preferably, the source of copper ions is selected from sodium permanganate and potassium permanganate. The concentration of the permanganate ions is in the range of 0.1 mol / l to 1.5 mol / l. The permanganic acid solution may be acidic or alkaline. Preferably, the permanganic acid solution has a pH value in the range of 2.5 to 7. Step id. , A layer of MnO ₂ is formed in the sidewalls of the blind microvias (BMV).

Subsequently, Preferably in a solution comprising a thiophene compound and an alkanesulfonic acid.

Thiophene compounds are preferably selected from 3-hetero substituted thiophenes and 3,4-heterosubstituted thiophenes. Most preferably, the thiophene compound is selected from the group consisting of 3,4-ethylenedioxythiophene, 3-methoxythiophene, 3-methyl-4-methoxythiophene and derivatives thereof. The concentration of the thiophene compound ranges from 0.001 mol / l to 1 mol / l, more preferably from 0.005 mol / l to 0.05 mol / l.

The alkanesulfonic acid is selected from the group comprising methanesulfonic acid, ethanesulfonic acid, methane disulfonic acid, ethane disulfonic acid, and mixtures thereof. The concentration of alkaline sulfonic acid is set by adjusting the desired pH value of the solution used in step ie. Preferably, the pH value of the solution is set in the range of 0 to 3, more preferably in the range of 1.5 to 2.1.

Plating of copper as a metal is particularly preferred for the purposes of the present invention. The overall thickness of the copper layer or layers deposited in the printed circuit board applications is generally between 1 and 50 microns, more preferably between 4 and 30 microns.

Examples

The following experiments are intended to illustrate the benefits of the present invention and do not limit its scope.

The different silanes employed in the experiments are listed and specified in Table 1. The following organic solvents were used to dissolve the silane: isopropanol (bp 82 ° C: hereinafter IPA), and 2-isopropoxyethanol (bp 142 ° C, IPPE).

Sample No. P1, P6 to P9, P11 to P 20, and the first has been treated with a silane composition, and then the MnO ₄ - has been treated in an aqueous solution containing the ions. For Sample Nos. P2, the process sequence has been changed: MnO ₄ - ions is treated in an aqueous solution containing the first and followed by the following after processing in the silane composition (comparative example). For Sample No. P3, treatment in an aqueous solution containing MnO ₄ - ions was omitted and only the silane composition was applied (also Comparative Example). Sample No. P4 was processed in an aqueous solution containing only MnO ₄ - ions, without any silane treatment (Comparative Example). To Sample No. P5 and P10 was first treated with a solvent matrix without the silane compound and then with MnO ₄ - has been treated in an aqueous solution containing ions (comparative example). Following the permanganate treatment step, the reducing agent step is always followed by removal of the manganese (IV) oxide. Corresponding process conditions are provided in Table 1.

The compositions are provided in Table 1. The treatment time was 1 minute at ambient temperature.

The base material used is Ajinomoto Co .; Inc. < / RTI > ABF GX92. For the experiments, samples (7.5 x 15 cm) were cut in panels pre-cured for 30 minutes at a temperature of 100 ° C for 30 minutes and then at a temperature of 180 ° C for 30 minutes.

All solutions were freshly formed. The amount of silane was given as percent by weight and 3 wt.% For all experiments performed.

Silane Application: The solution (except P4) was sprayed onto the substrate using an ExactaCoat spray device by Sonotek. For Examples P5 and P10, the solvent is applied in the same manner without containing silane. The following parameters were set for all investigations:

Flow rate: 1.4 ml / min. (6 ml / min.)

Nozzle distance: 4 cm

Nozzle speed: 40 mm / s

Overlap: 14.2 mm

Nitrogen flow: 0.8 - 1.0 mPa

One spray cycle

The panels were then held for 10 minutes before being fired at 105 ° C for 5 minutes. The panels were cooled to room temperature and sent to the permanganate etchant (except for sample P3).

Sample P2 was first processed through a permanganate etchant and a reducing solution and then sprayed. The second MnO ₄ - etching step was not included.

Further Comparative Examples P21 and P22 were carried out in solutions containing sulfuric acid and hydrogen peroxide.

Example P21 was carried out according to the previous process sequence, wherein the solutions containing the oxidizer were included in a volume ratio of 3 to 1 concentrated sulfuric acid and 30 wt.% Hydrogen peroxide. The treatment was carried out at a temperature of 60 DEG C for 10 seconds. Subsequent metal plating, despite obtaining a fairly high roughness value, resulted in very poor adhesion of the metal layer to the surface substrate and thus made this process unsuitable for the production of the adhesive metal layer for the purposes of the present invention. Higher treatment times and / or higher temperatures resulted in complete removal of the resin layer and subsequently did not lead to adhesion of the plated metal layer. Example P22 was carried out according to the previous process sequence wherein the solutions containing oxidant contained 20 ml / l concentrated sulfuric acid and 20 ml / l 30 wt.% Hydrogen peroxide. The treatment was carried out at a temperature of 25 캜 for 5 minutes. The treated surface exhibited low illuminance and very poor adhesion of the subsequently plated metal layer and made this solution to make the adhesive metal layer which is the object of the present invention.

Figure 2 shows the surface after permanganate treatment of the GX92 substrate material according to Example P20. Measurements were performed on a Zeiss Gemini SEM at a voltage of 5 kV, magnification: 5000 x.

The measured illuminance Ra was 109 nm as measured by an Olympus LEXT 3000 confocal laser microscope.

Figure 3 shows an SEM image of the surface after permanganate treatment without prior application of silane of GX92 substrate material. This corresponds to a method known in the art involving aqueous swellings followed by permanganate etching. The permanganate concentration was 60 g / ℓ, the NaOH concentration was 45 g / ℓ, the treatment time was 20 min and the temperature was 80 ℃. The illuminance Ra measured by the confocal laser microscope described above was 200 nm. Such roughness may be too high for the fabrication of fine line circuits.

Thereafter, the samples were metal plated according to the process parameters provided in Table 2. Table 2 consists of a process sequence that was finally applied to form a 0.8 micron electroless copper and 30 micrometer electrolytically deposited copper on the GX92 substrate material.

The peel strength measurement of the plated metal layer on the substrate was carried out by delivering the samples in stripes 1 cm wide and 3 cm long after the final annealing. Peel strength measurements were performed with an Erichsen Wuppertal 708 strain gauge using a Chatillon LTCM-6 pulling mechanism. Adhesion values for all samples are shown in Table 1, column 5 ("peel").

Field Emission Scanning Electron Microscopy (FE-SEM) was performed using a LEO 1530 with a 5 kV accelerating voltage and a silicon drift detector (Xmas 80, Oxford). Images were recorded at 5000 magnifications. The dielectric surface was measured after etching the plated copper using sulfuric acid / hydrogen peroxide (50 ml / l H ₂ SO ₄ , 53 ml / l H ₂ O _{2 in} water at 40 ° C). Samples were sputtered with iridium prior to measurement.

For commercial processes, for example, flip chip ball grid arrays, adhesion values typically greater than 4-5 N / cm are needed. This depends on the type of application.

Average illuminance values (Ra) were measured on an Olympus LEXT 3000 confocal laser microscope. The roughness values were collected for a surface area of 120 [mu] m x 120 [mu] m. The average roughness value (Ra) for all the samples is shown in Table 1, column 6 (average roughness Ra).

Sufficient adhesion between the plated metal layer and the substrate can only be obtained by processing the samples according to the process according to the invention, i.e. the step of permanganate treatment after the silane-based treatment of the substrate surface. All other combinations of the process sequences shown in Table 1 result in very low adhesion of the plated metal layer, which is not acceptable for commercial applications.

The lowest adhesion values were only coated with silane (without any permanganate treatment) and then with metalized sample P3. A slight increase in initial adhesion was seen when the permanganate treatment was applied prior to the metal plating steps of the substrate (Sample No. P4). This increase was caused by additional roughening of the surface due to the permanganate stage. However, all samples that had not been processed through the permanganate after the silane coating showed a blister on the surface after the final copper annealing. Therefore, permanganate rinses are preferred after silane coating.

By changing the first two main steps in the process sequence, it has been shown that the correct sequence (only the first silane-treated permanganate cleaner) resulted in a significant adhesion increase to 5.5 N / cm. All other combinations (silane alone, MnO ₄ alone and first MnO ₄ followed by silane treatment) exhibited very low adhesion <1.0 N / cm.

The low illuminance values of the processed samples made the process suitable for the fabrication of circuit traces smaller than 10 [mu] m wide. Surface roughness values above 150 nm for such structures are needed so far to obtain sufficient adhesion between the substrate and the plated metal layer. However, higher than 150 nm average illuminance values may be too high for circuit traces smaller than 10 μm in width.

Claims (15)

CLAIMS 1. A method of treating a surface of a dielectric substrate for preparing a surface of a dielectric substrate for subsequent wet chemical plating,
(i) treating the surface with a solution comprising at least one organosilane compound;
(ii) treating said surface with a solution comprising an oxidizing agent selected from aqueous acidic or alkaline solutions of a permanganate
In this order, the surface of the dielectric substrate. The method according to claim 1,
Wherein the permanganate concentration is in the range of 20 - 100 g / l. The method according to claim 1,
The organosilane compound is represented by the formula
A _(4-x) SiB _x
Lt; RTI ID = 0.0 &gt;
In the equation
Each A is independently a hydrolyzable group,
x is 1 to 3,
Each B is independently selected from the group consisting of C ₁ -C ₂₀ alkyl, aryl,
C _n H _2n X,
&Lt; / RTI &gt; and a functional group represented by the following formula
In the equation
n is from 0 to 15, preferably from 0 to 10, even more preferably from 1 to 8, most preferably 1, 2, 3, 4
X is selected from the group consisting of amino, amido, hydroxy, alkoxy, halo, mercapto, carboxy, carboxyester, carboxamide, thiocarboxamide, acyl, vinyl, allyl, styryl, epoxy, epoxycyclohexyl, glycidoxy, Is selected from the group consisting of isocyanato, isocyanato, thiocyanato, thioisocyanato, ureido, thioureido, guanidino, thioglycidoxy, acryloxy and methacryloxy groups; Or X is a residue of a carboxy ester; Or X is Si (OR) ₃ , wherein R is a C ₁ -C ₅ alkyl group. The method of claim 3,
Preferably, the hydrolysable group A is selected from the group consisting of -OH, -OR ¹ , R ¹ is C ₁ -C ₅ alkyl, - (CH ₂ ) _y OR ² , y is 1, 2 or 3 and R ² Is H or C ₁ -C ₅ alkyl, -OCOR ^3, and R ³ is H or C ₁ -C ₅ alkyl. 5. The method of claim 4,
R ¹ , R ² and R ³ are independently selected from methyl, ethyl, propyl and isopropyl. 6. The method according to any one of claims 1 to 5,
Wherein the organosilane compound is selected from the group consisting of vinyl silane, aminoalkyl silane, ureido alkyl silane, methacryloxy silane and epoxy alkyl silane. 7. The method according to any one of claims 1 to 6,
Wherein the organosilane is applied at a concentration between 0.5 wt.% And 20 wt.%. 8. The method according to any one of claims 1 to 7,
Wherein the organosilane is dissolved in a polar organic solvent organic solvent having a boiling point in the range of 60 to 250 占 폚. 9. The method according to any one of claims 1 to 8,
Wherein the organosilane is dissolved in a polar organic solvent selected from diethylene glycol, 2-isopropoxyethanol (IPPE), di (propylene glycol) methyl ether acetate (DPGMEA), and 2-ethyl- A method of treating a surface of a substrate. 10. The method according to any one of claims 1 to 9,
Wherein the oxidant according to step 1 ii) is an alkaline aqueous solution of permanganate ions. 11. The method according to any one of claims 1 to 10,
(i) treating the surface with a solution comprising at least one organosilane compound at a temperature between 15 and 50 &lt; 0 &gt; C for a time period between 10 seconds and 10 minutes
(ii) an alkaline aqueous solution of permanganic acid at a concentration of 20 - 100 g / l for a time period between 1 and 30 minutes at a temperature of 20 and 95 ° C to obtain a roughened surface having an average surface roughness Ra of less than 150 nm And treating said surface with a solution comprising a selected oxidizing agent. 12. The method according to any one of claims 1 to 11,
(iii) metallizing the substrate after step (ii) with a wet chemical plating method. 13. The method of claim 12,
Wherein the metallization is copper metallization. The method according to claim 12 or 13,
(iii) metallizing the substrate after step (ii) with a wet chemical plating method comprises the following steps to make the surface conductive:
(iii) contacting the substrate with an activator solution comprising a colloidal or ionic catalytic metal, such as a noble metal, preferably palladium, to render the surface of the substrate catalytically active;
And, optionally, especially where the activator comprises an ionic catalytic metal,
(iii b) contacting the substrate with a reducing agent, wherein the metal ions of the ionic activator are reduced to metal elements,
Alternatively, when the activator comprises a colloidal catalytic metal,
(iii) contacting the substrate with an accelerator, wherein the colloid, e.g., the components of the protective colloid, are removed from the catalytic metal,
&Lt; / RTI &gt; 13. The method according to any one of claims 1 to 12,
The dielectric substrate has a contact region 2 and a second dielectric layer 3 on at least a portion of the backside side or a dielectric dielectric build-up layer 1 attached to the backside of a dielectric build- Up layer (1) and at least one opening (4) in the build-up layer (1) extending through the substrate to the contact area (2)
(i) treating the surface with a solution comprising at least one organosilane compound as defined in any one of the preceding claims,
(ii) treating the surface with a solution comprising an oxidizing agent as defined in any one of the preceding claims,
(iii) depositing a conductive seed layer (6) on the upper surface (5a) of the dielectric build-up layer (1) and on the dielectric side wall (5b) of the at least one opening (4)
(iv) selectively depositing a copper layer (8) in the openings of the resist layer (7) patterned by electroplating.

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