Method for removing organic resin from surface of substrate

Abstract

The present invention relates to a method for removing organic resin from a copper surface on a dielectric substrate comprising conductive through-holes (TH) and / or conductive blind micro-vias (BMVs), the method comprising the following steps: (i) applying an organic paste to the dielectric substrate to fill the through-holes (TH) and / or the blind micro-vias (BMVs) with the organic paste, wherein after step (i), at least a portion of the surface of the dielectric substrate is covered with the organic paste; (ii) curing the organic paste to convert the organic paste into a cured organic resin, where after step (ii) at least a portion of the surface of the dielectric substrate is covered by the organic resin; (iii) chemically treating the dielectric substrate with a non-aqueous composition to remove the organic resin from the surface of the substrate to obtain a chemically treated surface of the substrate, the non-aqueous composition comprising: a) at least one high boiling solvent at a concentration of 80 to 95 wt%, b) at least one organic solvent at a concentration of 80 to 95 wt%; wherein the boiling point of the high boiling point solvent is at least 100 DEG C, b) at least one carboxylic acid, the concentration of the at least one carboxylic acid being from 5% by weight to less than 20% by weight, c) at least one anionic aromatic surfactant, the concentration of the at least one anionic aromatic surfactant being from 0.25% by weight to less than 1.5% by weight, and d) at least one nonionic alkynediol-based surfactant, the concentration of the at least one nonionic alkynediol-based surfactant being from 0.25 wt% to less than 1.5 wt%; (iv-1) mechanically treating the chemically treated surface of the substrate obtained after step (iii) with an abrasion tool to remove residual organic P21 / 017 / WO HS resin from the chemically treated surface of the substrate, thereby obtaining a mechanically treated surface of the substrate; and / or (iv-2) wet-chemically treating the chemically treated surface of the substrate obtained after step (iii) with an oxidizing solution comprising an oxidizing agent to remove residual organic resin from the chemically treated surface of the substrate, thereby obtaining a wet-chemically treated surface of the substrate; (v) optionally depositing an electrically conductive material on the mechanically treated surface obtained after step (iv-1) or on the wet chemically treated surface of the substrate obtained after step (iv-2), preferably electrolessly depositing a coating metal on the mechanically treated surface or on the wet chemically treated surface, obtaining a conductive surface of the substrate; and (vi) optionally electrodepositing a further coating metal on the electrically conductive surface of the substrate obtained after optional step (v) or on the mechanically treated surface of the substrate obtained after step (iv-1) or on the wet chemically treated surface of the substrate obtained after step (iv-2), in this way, an electrolytic metal coated surface is obtained.

Description

Technical Field

[0001] This invention relates to a method for removing organic resin from a copper surface on a dielectric substrate, and to articles obtained by said method, said dielectric substrate comprising conductive through-holes (TH) and / or conductive blind microvias (BMV). The method is particularly suitable for manufacturing articles comprising VIPPO (via-in-pad plating) structures. The invention further relates to the use of a non-aqueous composition for removing organic resin from the surface of said dielectric substrate. Background Technology

[0002] Removing organic coatings used as paint from metal surfaces such as steel or aluminum is known in the automotive industry.

[0003] US 3,790,489 A describes a paint stripping compound for use at elevated temperatures, comprising a caustic base having the following components: alkali metal hydroxides, alkali metal nitrates, alkali metal chlorides, catalysts selected from the group consisting of alkali metal permanganates, manganese dioxide, and Cr₂O₃, and preferably alkali metal carbonates. The components are fused and maintained at a temperature between 800°F (about 426°C) and 900°F (about 482°C) for removal.

[0004] However, under conditions taught in US 3,790,489 A, certain metals such as zinc, aluminum, copper, and magnesium, or metal coatings containing these metals or their alloys, as well as other metal, alloy, and even non-metallic substrates, can be chemically eroded or damaged. Therefore, in the teachings of the prior art, the use of such caustic compositions is generally avoided when removing coatings from metals, such as aluminum, magnesium, and zinc.

[0005] WO 2017 / 194449 A1 teaches a prior art method based on a stripping composition containing high-boiling-point ethylene glycol, wherein stripping from a substrate is achieved by using a non-aqueous stripping composition and a method for stripping an organic coating from the substrate.

[0006] However, in the electronics industry, removing organic resins from substrates is also extremely important. In particular, it is necessary to remove organic resins or residues from dielectric substrates, such as those on copper surfaces, to prevent these resins from acting as "etch resists," which can ultimately lead to short circuits and open circuits in circuit systems, especially during the manufacturing process of printed circuit boards (PCBs).

[0007] Therefore, the need for effective removal of organic resins is increasing during the manufacturing process of printed circuit boards (PCBs). Particularly in terms of increasing signal speed and FC-BGA pitch density, PCB design focus has shifted to the use of through-hole plating (VIPPO), replacing the increasingly traditional dog-bone pad structure used in conventional PCBs. This allows for shorter signal path lengths, thereby reducing capacitance and inductance.

[0008] Typically, for VIPPO designs, a specially designed sealant is used to screen-print a PCB manufactured following a process sequence consisting of: drilling grooves for through-holes and blind microvias; decontamination; activation; electroless copper deposition; and electrolytic copper deposition. During the screen-printing process, a resin film is applied to the PCB surface and allowed to harden in a subsequent curing step. However, this resin film needs to be removed for further processing to build the VIPPO. It is essential to ensure that all sealant is removed from the PCB surface to provide a highly reliable subsequent metal deposition with excellent adhesion and conductivity.

[0009] US2003 / 0074790 A1 relates to a method of manufacturing a resin-filled plate, the method comprising forming a roughened surface in perforations on a conductive layer, followed by filling the perforations with resin; forming a smooth surface on a conductive layer formed on a top and bottom surface of the plate; printing the resin using a mask having openings at locations corresponding to the perforations to selectively fill the perforations with the resin; and curing the resin. The mask may be a sieve or a metal mask. The diameter of the openings in the mask is preferably 1.1 to 2.5 times the diameter of the perforation. The method further comprises mechanically polishing a portion of the resin excessively formed on the surface of the perforations to remove it, thereby smoothing the surface of the plate.

[0010] US 4,991,359 describes a method of treating a metal-plated plate with an aqueous sodium carbonate solution to swell the surface, and then, after or simultaneously with swelling the surface, abrading a resin layer on the swollen surface to remove the hardened and alkali-soluble resin layer.

[0011] This removal is accomplished by mechanically grinding / polishing / grinding the resin-coated PCB surface. Typically, a grinding machine, polishing roller, or grinding belt is used to grind / polish / grind the surface to remove excess sealant from the PCB surface after the via filling process. The grinding head material can be, for example, silicon carbide. Water can also be used during grinding / polishing / grinding. Careful adjustment of the grinding head pressure on the surface is necessary to minimize the risk of potentially grinding through the copper foil or excessively removing resin filler, resulting in an uneven or defective surface.

[0012] Invention Objective

[0013] Therefore, the first objective of the present invention is to overcome the deficiencies of the prior art and to provide a method for improving the removal of organic resins (i.e., cured organic filler pastes) from the copper surface of various dielectric substrates comprising through-holes (TH) and / or blind microvias (BMV).

[0014] Therefore, a second objective of the present invention is to provide surface treatments for various dielectric substrates to avoid damaging the copper surface of the substrate, and in particular to avoid partially removing or weakening the adhesion between the copper surface and the substrate.

[0015] Therefore, a third objective of the present invention is to provide surface treatments for various organic resins that allow the formation of metallic coatings on the respective substrates, the metallic coatings having excellent adhesion (particularly electrolytically deposited copper coatings) and being difficult to peel off, particularly on blind microvias (BMVs) and / or on vias (THs) of the substrate.

[0016] Therefore, the fourth objective of this invention is to provide surface treatments for various dielectric substrates that can be incorporated into the conventional process sequence for manufacturing articles containing VIPPO (via-in-pad plating) structures, for example, into vertical and / or horizontal processes, without requiring significant modifications to other process steps, thereby reducing manufacturing costs. Summary of the Invention

[0017] The first to fourth objectives mentioned above are achieved according to a first aspect of the present invention by a method for removing organic resin from a copper surface on a dielectric substrate, the dielectric substrate comprising conductive through-holes (TH) and / or conductive blind microvias (BMV), the method comprising the following steps:

[0018] (i) An organic paste is applied to the dielectric substrate to fill the through-hole (TH) and / or the blind microvia (BMV) with the organic paste, wherein after step (i), at least a portion of the surface of the dielectric substrate is covered by the organic paste;

[0019] (ii) Curing the organic paste to transform it into a cured organic resin, wherein after step (ii), at least a portion of the surface of the dielectric substrate is covered by the organic resin;

[0020] (iii) The dielectric substrate is chemically treated with a non-aqueous composition to remove the organic resin from the surface of the substrate, thereby obtaining a chemically treated surface of the substrate, wherein the non-aqueous composition comprises or consists of the following:

[0021] a) At least one high-boiling solvent, wherein the concentration of the at least one high-boiling solvent is from 80% to 95% by weight, preferably from 81 wt.% to 91 wt.% by weight, and the at least one high-boiling solvent is selected from the group consisting of alcohols having the general chemical formula R-OH, wherein R is C4-C. 30 Hydrocarbon groups, wherein the boiling point of the high-boiling solvent is at least 100°C.

[0022] b) At least one carboxylic acid, wherein the concentration of said at least one carboxylic acid is from 5% by weight to less than 20% by weight, preferably from 4% by weight to 9% by weight, more preferably from 7% by weight to 8% by weight, preferably said at least one hydroxycarboxylic acid, more preferably selected from the group consisting of 2-hydroxypropionic acid, tartaric acid and acetic acid.

[0023] c) At least one anionic aromatic surfactant, wherein the concentration of said at least one anionic aromatic surfactant is from 0.25% by weight to less than 1.5% by weight, preferably from 0.5% by weight to 1% by weight, and preferably said at least one anionic aromatic surfactant is selected from the group consisting of at least one C10-C16-alkylbenzene sulfonic acid and toluene sulfonic acid.

[0024] d) at least one nonionic alkynyldiol-based surfactant, wherein the concentration of the at least one nonionic alkynyldiol-based surfactant is from 0.25% by weight to less than 1.5% by weight, preferably from 0.5% by weight to 1% by weight, and preferably the at least one nonionic alkynyldiol-based surfactant is selected from the group consisting of at least one C8-C12 alkynyl-diol, more preferably 2,4,7,9-tetramethyldecyl-5-yne-4,7-diol;

[0025] (iv-1) Mechanically treating the chemically treated surface of the substrate obtained after step (iii) using an abrasive tool to remove residual organic resin from the chemically treated surface of the substrate, thereby obtaining the mechanically treated surface of the substrate; and / or

[0026] (iv-2) The chemically treated surface of the substrate obtained after step (iii) is subjected to wet chemical treatment with an oxidizing solution containing an oxidizing agent to remove residual organic resin from the chemically treated surface of the substrate, thereby obtaining the wet chemically treated surface of the substrate.

[0027] (v) Optionally depositing conductive material on the mechanically treated surface obtained after step (iv-1) or on the wet chemically treated surface of the substrate obtained after step (iv-2), preferably electroless depositing coating metal on the mechanically treated surface or the wet chemically treated surface to obtain a conductive surface of the substrate.

[0028] (vi) Optionally, an additional coating metal is electrolytically deposited onto the conductive surface of the substrate obtained after optional step (v), or onto the mechanically treated surface of the substrate obtained after step (iv-1), or onto the wet chemically treated surface of the substrate after step (iv-2), to obtain an electrolytically coated surface; and

[0029] (vii) Optionally, the surface of the electrolytic metal coating in step (vi) is structurally processed, and solder pads, preferably tin solder pads, are electrolytically deposited to obtain a VIPPO (via-in-pad plating) structure.

[0030] The total amount of all components of the non-aqueous composition, plus optionally added components, which together constitute 100% (wt.%) of the composition, or in other words, the sum of all components does not exceed 100% by weight.

[0031] The method removes excess organic resin and residual uncured organic paste (plugging paste) from the surface of the substrate, particularly the copper surface of the printed circuit board, while the organic resin is retained within the conductive vias (TH) and / or the conductive blind microvias (BMV).

[0032] The method, particularly the mechanical treatment according to step (iv-1) and / or the wet chemical treatment according to step (iv-2), allows for the efficient removal of loose or weakly adhered surface resin from the substrate, particularly near the vias (TH) and / or blind microvias (BMV) of the dielectric substrate.

[0033] If both treatment steps (iv-1) and (iv-2) are applied, it is preferable to apply the mechanical treatment according to step (iv-1) prior to the wet chemical treatment according to step (iv-2). This may be useful, for example, in cases where the amount of residual uncured organic paste is high or the chemical resistance of the cured organic resin is low. In this case, the wet chemical treatment step (iv-2) can also be used to prepare the surface for subsequent metallization. However, in some cases, it is also useful to begin with step (iv-2) followed by (iv-1). This may be useful, for example, in cases where the chemical resistance of the organic resin is higher.

[0034] Therefore, method steps (iv-1) and / or (iv-2) ensure that the organic resin is completely removed from the surface of the dielectric substrate, particularly from the copper surface, after the prior chemical treatment of the dielectric substrate with a non-aqueous composition during method step (iii), thereby allowing excellent subsequent deposition of the conductive material during step (v) and / or excellent subsequent deposition of the coating metal during step (vi). Preferably, after applying step (iii), applying only step (iv-1) or step (iv-2) is sufficient to complete the cleaning.

[0035] The method avoids damage to the dielectric substrate, copper surface, and / or non-conductive surfaces of the PCB caused by grinding. Preferably, the method excludes the grinding step using a grinding apparatus.

[0036] An effective activation layer is deposited onto the respective treated surface by optionally depositing conductive material on the mechanically treated surface obtained after step (iv-1) or on the wet chemically treated surface obtained after step (iv-2) of the substrate, preferably by electroless deposition of coating metal on the mechanically treated surface or the wet chemically treated surface, which allows additional coating metal to be optionally electrolytically deposited subsequently on the conductive surface of the substrate.

[0037] Furthermore, due to the high efficiency of treatment steps (iii) and (iv-1) or (iv-2), wastewater treatment can be simplified, energy and time consumption can be reduced, and therefore manufacturing costs can be reduced due to existing treatment steps.

[0038] The first to fourth objectives mentioned above are achieved by the article obtained according to the method of the first aspect, based on the second aspect. The article can be further processed by further cleaning and metallization steps to obtain an article containing a VIPPO (via-plated pad) structure.

[0039] The article comprises an excellent metallic coating based on the advantages summarized above.

[0040] The first to fourth objectives mentioned above are achieved according to the third aspect by using a non-aqueous composition according to the method of the first aspect to remove organic resin from the surface of a dielectric substrate to manufacture an article comprising a VIPPO (via in-pad plating) structure, wherein the dielectric substrate comprises through-holes (TH) and / or blind microvias (BMV).

[0041] Brief description of the example

[0042] In the examples, the changes in the chemical treatment steps on the respective substrate surfaces were examined for the resulting optical properties of the nickel-plated surfaces obtained subsequently.

[0043] In the comparative examples, the changes in pH compared to the non-aqueous treatment solution (sample 4) were examined for the resulting optical properties on the copper surfaces obtained subsequently.

[0044] Further details are given in the “Examples” section below. Detailed Implementation

[0045] General definition

[0046] In the context of this invention, the terms "at least one" or "one or more" mean "one, two, three or more three" (and are interchangeable with them).

[0047] In the context of this invention, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0048] In the context of this invention, the terms "deposition," "coating," and "plating" are used interchangeably. In the context of this invention, the terms "layer," "coating," and "deposit" are used interchangeably.

[0049] In the context of this invention, the term "dielectric" means nonmetallic and thus nonconductive.

[0050] In the context of this invention, the term "aqueous solution" means that the aqueous solution contains 50% by weight (wt.) or more of water.

[0051] In the context of this invention, the term "decontamination process" refers to a wet chemical process performed after drilling TH and BMV, specifically involving the removal of residues in the form of particulate matter generated by laser drilling or mechanical drilling of the surface of a dielectric substrate to form vias (TH, also named through-hole vias (THV)) and / or blind microvias (BMV) in the substrate. The wet chemical process comprises at least one etchant, preferably an acidic or alkaline aqueous permanganate solution.

[0052] In the context of this invention, the copper surface of the dielectric substrate to be processed is understood as the copper surface of a copper layer deposited on the dielectric substrate, wherein the substrate includes through-holes (TH) and blind microvias (BMV).

[0053] In conductive through-hole (TH) and conductive blind microvia (BMV), "conductive" means that a copper layer is also deposited on the walls of the TH and BMV to construct the conductive through-hole (TH) and conductive blind microvia (BMV). The copper layer is deposited conformally, and the TH and BMV are not filled with copper.

[0054] In the context of this invention, the term "alkyl" refers to an alkyl group having 1 to 18 carbon atoms (C1-C1). 18 A saturated straight-chain or branched monovalent hydrocarbon group, wherein the alkyl group may optionally be independently substituted by one or more substituents described below. Examples of alkyl groups include, but are not limited to, methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl and their higher homologs, as well as all their isomers.

[0055] In the context of this invention, the term "alkynyl" (also referred to as "alkynyl group") means having at least one triple bond and having 8 to 12 carbon atoms (C2-C4). 30 The alkyne group is an unsaturated straight-chain or branched monovalent hydrocarbon group, wherein the alkyne group may optionally be independently substituted by one or more substituents described below. Examples of alkyne groups include, but are not limited to, oct-4-yne, dec-5-yne, or dodeca-6-yne.

[0056] In the context of this invention, the term "aromatic" refers to an aryl group derived by removing a hydrogen atom from a single carbon atom in the parent aromatic ring system, having 6 to 20 carbon atoms (C6-C4). 20 Aryl groups are monovalent aromatic hydrocarbon groups. Aryl groups also include bicyclic groups comprising an aromatic ring fused to an aromatic carbide ring. Typical aryl groups include, but are not limited to, groups derived from benzene (phenyl), substituted benzene, naphthalene, etc. Aryl groups may optionally be independently substituted by one or more substituents as described below.

[0057] Alkyl, alkynyl and aryl groups can each be substituted, wherein at least one hydrogen atom can be substituted by a halogen atom.

[0058] In the context of this invention, the term "hydrocarbon group" refers to a chemical group having a straight-chain or branched backbone exclusively composed of carbon atoms, wherein two adjacent carbon atoms are bonded together by a single, double, or triple bond, or are members of an aromatic ring, wherein this backbone further includes hydrogen atoms bonded to the carbon atoms. These hydrogen atoms may be partially replaced by halogen atoms, thereby forming part of a hydrocarbon group. Hydrocarbon groups do not include hydroxyl groups. More preferably, the hydrocarbon group may be a straight-chain or branched alkyl, straight-chain or branched alkenyl, straight-chain or branched alkyne, cycloalkyl, or cycloalkenyl, including bicyclic, tricyclic, and higher condensed alicyclic groups. These compounds are aliphatic hydrocarbon groups. Furthermore, the hydrocarbon group can preferably be aryl, arylalkylene, arylalene, arylynylene, arylcycloalkylene, or arylcycloalkylene, including bicyclic, tricyclic, and higher condensed aryl groups, wherein the alkylene in the arylalkylene, the alkenyl in the arylalene, and the alynylene in the arylynylene are all straight-chain or branched groups, as before, and wherein the cycloalkylene in the arylcycloalkylene and the alynylene in the arylcycloalkylene can form higher condensed alicyclic ring systems. In these latter cases, the bifunctional group has a bond with the OH group of the high-boiling alcohol. The hydrocarbon group that is arylalkylene, arylalene, arylynylene, arylcycloalkylene, or arylcycloalkylene is an arylaliphatic group. In these latter cases, the bifunctional group has a bond with the OH group of the high-boiling alcohol. Hydrogen atoms bonded to cycloalkyl, cycloalkylene, cycloalkenyl, cycloalkenyl, and aryl groups may be partially substituted with halogen atoms, and further may be substituted with alkyl, alkenyl, and / or alkynyl groups. More specifically, as used herein, the term 'C4-C'... 30 A 'hydrocarbon group' refers to a group having a skeleton comprising 4 to 30 carbon atoms, including all skeletal carbon atoms in alkyl, alkenyl, and / or alkynyl groups containing hydrogen atoms substituted with cycloalkyl, cycloalkylene, cycloalkenyl, and aryl groups. Even more specifically, as used herein, the term 'C4-C'... 20 A 'hydrocarbon group' refers to a group having a skeleton comprising 4 to 20 carbon atoms, including all skeletal carbon atoms as described previously herein. Similarly, as used herein, the term 'C4-C'... 10 A 'hydrocarbon group' refers to a group having a skeleton comprising 4 to 10 carbon atoms, including all skeletal carbon atoms as described previously herein. Therefore, as used herein, the term 'C1-C'... 20 A 'hydrocarbon group' refers to a group having a skeleton comprising 1 to 20 carbon atoms, including skeletal carbon atoms as previously described. The term 'C1-C' refers to a group having only one carbon atom ('C1 hydrocarbon group'). 20 In the sense of a 'hydrocarbon group', this group is methyl; and in the context of the term 'C1-C' referring to a group with two carbon atoms ('C2 hydrocarbon group'), it is methyl.20 In terms of the meaning of 'hydrocarbon group', this group is ethyl, vinyl, or ethynyl.

[0059] In the context of this invention, the term "about" in relation to concentration values ​​(wt.% or wt.-%), temperature values, processing time values, or thickness values ​​means the exact (average) value given and the range of concentration values, temperature values, processing time values, or thickness values ​​relative to this average value ±30%. For example, "about 3 wt%" precisely means 3 wt% and the range from 3 wt% to 30% of 3 wt% (= 3 wt% - 0.9 wt% = 2.1 wt%) to 3 wt% + 30% of 3 wt% (= 3 wt% + 0.9 wt% = 3.9 wt%), thus yielding a range of 2.1 wt% to 3.9 wt%. The range of values ​​given with respect to operating temperature, or processing time, or thickness, defined by "about", is correspondingly understood as a relative percentage of the temperature value based on a ℃ scale (±30% of 40℃ is ±12℃).

[0060] First aspect

[0061] According to a first aspect, the present invention relates to a method for removing organic resin from a copper surface on a dielectric substrate, said dielectric substrate comprising conductive through-holes (TH) and / or conductive blind microvias (BMV), said method comprising the following steps:

[0062] (i) An organic paste is applied to the dielectric substrate to fill the through-hole (TH) and / or the blind microvia (BMV) with the organic paste, wherein after step (i), at least a portion of the surface of the dielectric substrate is covered by the organic paste;

[0063] (ii) Curing the organic paste to transform it into a cured organic resin, wherein after step (ii), at least a portion of the surface of the dielectric substrate is covered by the organic resin;

[0064] (iii) Chemically treating the dielectric substrate with a non-aqueous composition to remove the organic resin from the surface of the substrate, thereby obtaining a chemically treated surface of the substrate, the non-aqueous composition comprising:

[0065] a) At least one high-boiling solvent, wherein the concentration of the at least one high-boiling solvent is from 80% to 95% by weight, preferably from 81 wt.% to 91 wt.% by weight, and the at least one high-boiling solvent is selected from the group consisting of alcohols having the general chemical formula R-OH, wherein R is C4-C. 30 Hydrocarbon group, wherein the boiling point of the high-boiling solvent is at least 100°C;

[0066] b) At least one carboxylic acid, wherein the concentration of the at least one carboxylic acid is from 5% to 20% by weight, preferably from 4% to 9% by weight, more preferably from 7% to 8% by weight, and preferably the at least one carboxylic acid is at least one α-hydroxycarboxylic acid, more preferably 2-hydroxy-propionic acid;

[0067] c) at least one anionic aromatic surfactant, wherein the concentration of said at least one anionic aromatic surfactant is from 0.25% by weight to less than 1.5% by weight, preferably from 0.5% by weight to 1% by weight, and preferably said at least one anionic aromatic surfactant is selected from the group consisting of at least one C10-C16 alkylbenzene sulfonic acid; and

[0068] d) at least one nonionic alkynyldiol-based surfactant, wherein the concentration of the at least one nonionic alkynyldiol-based surfactant is from 0.25% by weight to less than 1.5% by weight, preferably from 0.5% by weight to 1% by weight, and preferably the at least one nonionic alkynyldiol-based surfactant is selected from the group consisting of at least one C8-C12 alkynyl-diol, more preferably 2,4,7,9-tetramethyldecyl-5-yne-4,7-diol;

[0069] (iv-1) Mechanically treating the chemically treated surface of the substrate obtained after step (iii) using an abrasive tool to remove residual organic resin from the chemically treated surface of the substrate, thereby obtaining the mechanically treated surface of the substrate; and / or

[0070] (iv-2) The chemically treated surface of the substrate obtained after step (iii) is subjected to wet chemical treatment with an oxidizing solution containing an oxidizing agent to remove residual organic resin from the chemically treated surface of the substrate, thereby obtaining the wet chemically treated surface of the substrate.

[0071] (v) Optionally depositing conductive material on the mechanically treated surface obtained after step (iv-1) or on the wet chemically treated surface of the substrate obtained after step (iv-2), preferably electroless depositing coating metal on the mechanically treated surface or the wet chemically treated surface to obtain a conductive surface of the substrate.

[0072] (vi) Optionally, an additional coating metal is electrolytically deposited onto the conductive surface of the substrate obtained after optional step (v), or onto the mechanically treated surface of the substrate obtained after step (iv-1), or onto the wet chemically treated surface of the substrate after step (iv-2), to obtain an electrolytically coated surface; and

[0073] (vii) Optionally, the surface of the electrolytic metal coating in step (vi) is structurally processed, and solder pads, preferably tin solder pads, are electrolytically deposited to obtain a VIPPO (via-in-pad plating) structure.

[0074] It has been found that the method steps according to the invention result in a more efficient and gentler removal of organic resins, particularly organic epoxy resins, from the respective substrates. This allows for particularly effective cleaning of surfaces on which further electroless deposition of conductive materials and / or electrolytic deposition of additional coating metals can be achieved. In particular, not only is the adhesion of the deposited conductive material and / or the deposited additional coating metals to the copper surface significantly improved, but the adhesion of the deposited conductive material and / or the deposited additional coating metals to the filled TH and BMV organic resins is also significantly improved.

[0075] Steps (i) and (ii)

[0076] Preferably, the organic paste applied during step (i) comprises an epoxy paste, a polyester paste, a polyurethane paste, and an acrylic paste, more preferably, the organic paste applied during step (i) comprises an epoxy paste for subsequent VIPPO application. Preferably, an epoxy paste based on bisphenol A with a molecular weight (MW) of 700 or lower can be used, and said epoxy paste can be derived from, for example, Taiyo America, Inc., 2675 Antler Drive, Carson City, NV 89701, for example as the THP-100DX1 product.

[0077] Preferably, the curing of the organic paste during step (ii) to obtain a cured organic resin includes a thermosetting process, more preferably performed between 130°C and 160°C, and most preferably at 150°C.

[0078] Preferably, the curing of the organic paste performed during step (ii) lasts for 30 to 60 minutes, preferably 45 minutes.

[0079] The cured organic resin derived from the organic paste material is preferably chemically different from the material of the dielectric substrate. This means that in step (iii), the cured organic resin can only be removed from the dielectric substrate, while in step (iii), the dielectric substrate is chemically inert (non-removable).

[0080] Step (iii)

[0081] Therefore, the non-aqueous composition of the present invention used in method step (iii) comprises four key components and optionally additional components, which are as explained above (a)-d).

[0082] By using a non-aqueous composition, efficient removal of cured organic resins from the surface of a substrate can be achieved even at low operating temperatures. This is believed to be due to the maximal effect of the combination of solvent and carboxylic acid with selected surfactants on the dissolution and removal of the polymer resin, which can further help improve subsequent rinsing of the substrate due to the good miscibility of the polymer resin with water.

[0083] Another advantage of this invention is that the preferred surfactant level is lower than that found in prior art strippers. Furthermore, if a low-foaming surfactant or a suitable blend of low-HLB and high-HLB surfactants is used in this invention, these surfactants additionally help to rinse away the non-aqueous solution from the treated portion, and simultaneously, the surfactants control foaming issues in subsequent rinsing steps. Therefore, no actual foaming problems are generated, and no defoamers or other countermeasures are required. Consequently, both the efficiency and cost-effectiveness of the removal process can be improved.

[0084] Due to the intensity and efficiency of removing the organic resin from the substrate, the operating temperature during step (iii) can be reduced compared to the operating temperature required for efficient peeling reported, for example, in US 7,151,080 B2, where the operating temperature is much higher than 100°C. The operating temperature can be reduced considerably to lower values, for example, 30°C to 90°C, more preferably 60°C to 85°C. Similarly, the processing time of step (iii) can be reduced compared to conventional methods because the non-aqueous composition is much more efficient than prior art compositions. This effect is due to the combination of solvent and co-solvent compared to prior art compositions.

[0085] The non-aqueous composition vigorously and effectively removes organic resins from the corresponding substrates during normal or shorter processing times and at normal or lower temperatures without damaging the underlying substrates that have been damaged by prior art strippers.

[0086] This non-aqueous composition further comprises components that are stable under operating conditions, particularly at the operating temperatures required for effective removal of organic resins. Furthermore, the non-aqueous composition meets the safety requirements for workers using it.

[0087] The composition used in step (iii) of the method according to the invention is non-aqueous, meaning that the non-aqueous composition is substantially free of water. Some water may be absorbed from the atmosphere during the process. Preferably, water is not intentionally added to the non-aqueous composition. Typically, the water content in the non-aqueous composition during operation should also be less than 1% by weight, preferably less than 0.5% by weight, more preferably less than 0.1% by weight, and most preferably less than 0.01% by weight. The water contained in the non-aqueous composition does not negatively affect the paint removal performance. Conversely, if the non-aqueous composition contains water, the removal performance of organic pastes and / or cured organic resins will be reduced. However, in any case, when water is present in the non-aqueous composition, the composition generally tends to exhibit chemical corrosivity to soft metals such as aluminum, zinc, copper, and magnesium. This chemical corrosivity is thought to be due to the ionization of acidic or hydroxide compounds present in the non-aqueous composition, such that the ions generated by this ionization may etch these metals. Therefore, by adding water to the non-aqueous composition for process dispensing, the invention is suitable for use on sensitive substrates. Therefore, as used herein, the term 'substantially anhydrous' means a water content at a level that would not cause potassium hydroxide or acid components to ionize to the extent that they would corrode aluminum, magnesium, copper, or zinc substrates.

[0088] The high-boiling-point solvents that can be used in the non-aqueous compositions of the present invention can be selected from a variety of high-boiling-point alcohols, particularly those having the general chemical formula R-OH, whose boiling points are suitable for operating temperatures, for example, from 30°C to 90°C. More preferably, the non-aqueous compositions according to the present invention are operated at temperatures ranging from 60°C to 90°C, most preferably from 65°C to 85°C, wherein the higher values ​​within this range are suitable for resin removal. Thus, according to the present invention, the boiling point of at least one high-boiling-point alcohol will be at least 100°C. The boiling point can be as high as 200°C or 300°C or even higher, with the highest value limited by the energy obtained by heating the non-aqueous composition and the thermal stability of the substrate material.

[0089] According to a preferred embodiment of the present invention, the non-aqueous composition comprises at least one high-boiling-point solvent, said at least one high-boiling-point solvent being a compound having the general chemical formula R-OH, wherein R is an arylalkylene group, wherein the aryl group is preferably C6-C. 10 Aryl, wherein the alkylene group is preferably a C1-C6 alkylene group.

[0090] According to one or even a more preferred embodiment of the invention, the non-aqueous composition comprises at least one high-boiling solvent, said high-boiling solvent being benzyl alcohol (C6H5-CH2-OH) or another phenylalkylene compound, since good removal performance has been demonstrated with benzyl alcohol-based non-aqueous compositions.

[0091] In the most general manner described above for the chemical processing steps, the non-aqueous composition contains four key components. In a preferred embodiment, these key components are combined in specified relative proportions: In a preferred embodiment of the invention, the non-aqueous composition may comprise or consist of the following:

[0092] a) 81% to 95% by weight of at least one high-boiling solvent;

[0093] b) 5% to 20% by weight of at least one carboxylic acid, preferably at least one hydroxycarboxylic acid;

[0094] c) at least one anionic aromatic surfactant, preferably at least one C10-C16-alkylbenzene sulfonic acid, in a concentration of 0.25% to 1.5% by weight; and

[0095] d) At least one nonionic alkynyl diol-based surfactant, preferably at least one C8-C12 alkynyl-diol, at a concentration of 0.25% to 1.5% by weight.

[0096] The components described herein constitute 100% by weight of the non-aqueous composition. In cases where the non-aqueous composition contains more than one compound consisting of corresponding components a, b, c, and d, the concentrations previously given herein represent the total concentration of all compounds consisting of the corresponding components among these components.

[0097] In the case of non-aqueous compositions containing components other than those listed above (a, b, c, d), the corresponding percentages will be adjusted accordingly.

[0098] In another preferred embodiment of the invention, the non-aqueous composition further comprises or consists of the following components:

[0099] a) 90% by weight of at least one high-boiling-point solvent, preferably benzyl alcohol;

[0100] b) 8% by weight of at least one α-hydroxycarboxylic acid, preferably 2-hydroxypropionic acid;

[0101] c) 1% by weight of at least one C10-C16 alkylbenzene sulfonic acid, and

[0102] d) 1% by weight of at least one C8-C12 alkyne-diol, preferably 2,4,7,9-tetramethyldecyl-5-yne-4,7-diol.

[0103] Components a, b, c, and d constitute 100% by weight of the non-aqueous composition.

[0104] The operating temperature of method step (iii) can be set to at least about 30°C, preferably at least about 40°C, more preferably at least about 60°C, and even more preferably at least about 65°C. Furthermore, the operating temperature of method step (iii) can be set to at most about 150°C or even higher, more preferably at most about 90°C, and even more preferably at most about 85°C, most preferably 80°C. According to an even more preferred embodiment of the invention, the operating temperature of method step (iii) is about 65°C to about 85°C.

[0105] Most preferably, step (iii) is performed at a temperature of 60°C to 90°C, or even more preferably 65°C to 85°C, and most preferably 80°C.

[0106] Preferably, step (iii) is performed for a duration of 1 to 15 minutes, more preferably 2 to 5 minutes.

[0107] The removed resin material typically remains in the non-aqueous composition and accumulates in the non-aqueous bath over time. In cases where partially removed portions still contain resin plaques, these portions are transferred to a rinsing bath, where the resin can be removed in this rinsing step. This reduces the rate of resin accumulation in the non-aqueous bath and advantageously extends the bath life.

[0108] The non-aqueous composition can also be sprayed onto the substrate surface to be removed. The spraying can be used in combination with immersion soaking, which occurs before or after spraying, or both.

[0109] The preferred operating mode for removing resin from the substrate includes the following sub-steps of method step (iii):

[0110] iii-a) Providing the non-aqueous composition of the present invention in a canister device;

[0111] iii-b) Contact the substrate with the non-aqueous composition in the canister device to remove the organic resin;

[0112] iii-d) Complete removal of organic resin from the substrate by applying high-pressure water jet to the substrate surface.

[0113] The pressure of the high-pressure water jet applied in steps iii-d is typically between 5 bar and 250 bar.

[0114] In step iii-a) and / or step iii-b), preferably in step iii-b), the non-aqueous composition is heated to a temperature of 30°C to 90°C, preferably 65°C to 85°C, for a period of 1 minute to 15 minutes, thereby removing the resin from the substrate or loosening the resin.

[0115] Step (iv-1) or step (iv-2)

[0116] Additional method steps (iv-1) and / or (iv-2) allow for the efficient removal from the surface of the substrate of any residual organic resin that was not removed from the surface in the preceding method step (iii).

[0117] Preferably, the first rinsing step is performed between step (iii) and step (iv-1) or between step (iii) and step (iv-2):

[0118] (r-1) Rinse the chemically treated surface of the substrate obtained after step (iii) with a first rinsing solution, more preferably containing distilled water.

[0119] The first rinsing step allows for effective treatment of the substrate surface after method step (iii) and before the subsequent mechanical treatment in step (iv-1) or the wet chemical treatment in step (iv-2).

[0120] Preferably, after step (iv-1) or after step (iv-2), the following second rinsing step is performed:

[0121] (r-2) Rinse the mechanically treated surface of the substrate obtained after step (iv-1) or the chemically treated surface of the substrate obtained after step (iv-2) with a second rinsing solution, wherein the second rinsing solution more preferably contains an acidic aqueous solution, the acidic aqueous solution most preferably containing sulfuric acid.

[0122] The second rinsing step allows for effective treatment of the substrate surface prior to the optional deposition of conductive metal during step (v) and / or the optional electrolytic deposition of additional coating metal during step (vi).

[0123] Preferably, steps (iii) (or (iii-b)) and / or (iv-2) are performed in the presence of ultrasonic waves provided by an ultrasonic transmitter.

[0124] More preferably, during step (iii) (or (iii-b)), the ultrasonic parameters of the ultrasonic device are 40 kHz.

[0125] More preferably, during step (iv-2), the ultrasonic parameters of the ultrasonic device are 40 kHz and 120 kHz.

[0126] Preferably, step (iv-1) involves contacting the chemically treated surface of the substrate with a rotating brush, wherein the rotating brush more preferably comprises nylon filaments and ceramic elements, the rotating brush allowing for gentle and mild cleaning of the copper surface.

[0127] By applying this rotating brush after the chemical treatment in step (iii) (or (iii-b)), effective mechanical removal of any residual organic resin during the mechanical removal step (iv-1) can be ensured. In particular, the ceramic element attached to the nylon filaments of the rotating brush allows for particularly efficient removal of organic resin. This gentle brushing effectively avoids damage to the copper surface.

[0128] Preferably, step (iv-1) is performed at room temperature, preferably 20°C to 25°C.

[0129] Preferably, step (iv-1) is performed for 15 seconds to 5 minutes, more preferably 30 seconds to 60 seconds.

[0130] Preferably, step (iv-1) is performed on the wet surface of the substrate.

[0131] Preferably, step (iv-2) is performed at a temperature of 55°C to 90°C, more preferably 65°C to 85°C.

[0132] Preferably, step (iv-2) is performed for a duration of 2 to 10 minutes, more preferably 12 minutes.

[0133] Preferably, the oxidant used during step (iv-2) comprises sodium permanganate or potassium permanganate.

[0134] Preferably, the oxidant is present in the solution in an amount of 35 g / L to 70 g / L based on the total volume of the oxidizing solution.

[0135] Preferably, step (iv-2) optionally includes at least two sub-steps (de) after the rinsing step:

[0136] The application utilizes the (de-2) etching step and (de-3) reduction step using the oxidation solution. These sub-steps may include applying a treatment solution containing a treatment agent, as shown below. Optionally, sub-step (de) includes a (de-1) swelling step performed before the (de-2) etching step, wherein sub-step (de-1) includes applying a first treatment agent, preferably a swelling agent, to the surface of the substrate to obtain a swollen surface of the substrate.

[0137] Preferably, only the (de-2) etching step and the (de-3) reduction step in step (iv-2) are used.

[0138] In one embodiment of the invention, sub-step (de) includes sub-steps (de-2) and (de-3), wherein sub-step (de-2) includes applying an oxidant as a second treatment agent to the surface of the substrate, and more preferably applying potassium permanganate to obtain an etched surface of the substrate, and wherein sub-step (de-3) includes applying a third treatment agent, preferably a reducing agent, to the surface of the substrate, preferably to the etched surface of the substrate.

[0139] The sub-steps using the first, second, and third treatment agents are preferably performed in an aqueous treatment solution.

[0140] Preferably, the first treatment agent, more preferably the swelling agent, comprises an organic solvent and penetrates into the exposed resin surface of the perforations and BMV, wherein the organic solvent is most preferably selected as ethylene glycol ether and / or lactam. Most preferably, the swelling agent is selected as commercially available Securiganth MV swelling agent.

[0141] Preferably, the first treatment agent, more preferably the swelling agent, is applied at a concentration of 200 ml / l to 500 ml / l based on the total volume of the first treatment solution.

[0142] Preferably, the pH of the first treatment solution containing the swelling agent is 9.5 to 12.

[0143] Preferably, the sub-step (de-1) is performed at a temperature of 55°C to 85°C, more preferably 60°C to 70°C.

[0144] Preferably, the sub-step (de-1) is performed for a duration of 2 to 15 minutes, preferably 5 to 10 minutes.

[0145] Preferably, the oxidation solution used as the second treatment solution is selected as an alkaline oxidation solution, which preferably contains potassium permanganate. Most preferably, the etchant is selected as commercially available Securiganth MV P-Etch.

[0146] Preferably, the oxidant used as the second treatment agent comprises potassium permanganate, and is applied at a concentration of 35 g / L to 70 g / L based on the total volume of the oxidizing solution used as the second treatment solution.

[0147] Preferably, the sub-step (de-2) is performed at a temperature of 55°C to 90°C, more preferably 65°C to 85°C, and most preferably 75°C.

[0148] Preferably, the sub-step (de-2) is performed for a duration of 2 to 20 minutes, more preferably 12 minutes.

[0149] Preferably, the third treatment agent, more preferably the reducing agent, comprises an acid, most preferably sulfuric acid or hydrochloric acid (i.e., a reducing agent capable of reducing the metal residues from the previous step, such as citric acid, ascorbic acid diphosphate), most preferably hydroxyammonium sulfate or hydrogen peroxide, and a polymer containing nitrogen atoms and / or positively charged nitrogen atoms. Most preferably, the reducing agent is selected as a commercially available Securiganth MV reducing conditioner.

[0150] Preferably, the third treatment agent, more preferably the reducing agent, is applied at a concentration of 75 ml / l to 125 ml / l based on the total volume of the third treatment solution.

[0151] More preferably, the third treatment agent, and more preferably the reducing agent, comprises 50 w / w% sulfuric acid at a volume of 80 ml / l to 100 ml / l based on the total volume of the second treatment solution.

[0152] Preferably, sub-step (de-3) is performed at a temperature of 40°C to 55°C, more preferably 40°C to 50°C, and most preferably 50°C.

[0153] Preferably, the sub-step (de-3) is performed for a duration of 0.5 to 5 minutes, preferably 4 minutes.

[0154] Preferably, the sub-step (de-3) is followed by a cleaning treatment step using a cleaning solution containing a cleaning agent. This cleaning solution will contain additives capable of removing dirt or organic residues on the substrate by using at least one inorganic and / or organic base (such as amines, such as ammonia or aliphatic amines and the like) or inorganic acids (such as sulfuric acid, hydrochloric acid) or organic acids (such as sulfonic acid, carbonic acid, acetic acid, glycolic acid), preferably also including additives as surfactants capable of reducing the surface tension of water, and optionally and more preferably polymers capable of adsorbing onto the previously treated surface to form a conditioned surface, such as polymers having nitrogen atoms and / or quaternized nitrogen atoms. Most preferably, the cleaning agent is selected from commercially available Securignath MV Cleaner C1 V8, Securignath MV Cleaner 902PF, Securignath MV Cleaner GFR-S1, or Cleaner Cupra Pro S2 EU.

[0155] Preferably, the cleaning agent contains 0 g / L to 30 g / L of sodium hydroxide based on the total volume of the cleaning solution.

[0156] Preferably, the cleaning step is performed at a temperature of 30°C to 70°C, more preferably 50°C to 60°C, and most preferably 60°C.

[0157] Preferably, the first cleaning step is performed for a duration of 0.5 to 6 minutes, more preferably 1 to 5 minutes.

[0158] Optional step (v)

[0159] Preferably, method step (v) is performed by adding a metal activating composition to deposit, for example, a metal layer on a wet-chemically treated surface of a substrate, particularly on a wet-chemically treated surface of a cured organic resin within TH and / or BMV, followed by reduction. The metal layer may be deposited, for example, as palladium or copper, in thin film, colloidal, or ionic form. The metal layer may be a pure metal layer or may contain additional metals as a metal alloy.

[0160] Preferably, the metal-activating composition comprises at least one source of, for example, palladium or copper ions. Furthermore, the solution may contain other metal ion sources, such as ruthenium, rhodium, palladium, osmium, iridium, platinum, copper, silver, nickel, cobalt, gold, and mixtures thereof. Palladium or copper ions, as well as the other metal ions, are adsorbed on the wet-chemically treated surface of the substrate and subsequently reduced, or adsorbed in the form of reduced metals (e.g., colloids or particles, such as palladium or copper colloids), wherein the palladium colloid may contain tin, or the copper colloid may contain palladium.

[0161] Preferably, the activating composition is selected as Neoganth MV activator, which is commercially available from Atotech Deutschland GmbH & Co. KG.

[0162] Preferably, the activating composition may contain carbon, a conductive polymer, or metal ions or metal colloids containing, for example, copper, palladium, palladium-tin, for subsequent direct metallization by electrolysis.

[0163] Optional step (vi)

[0164] The electrolytic deposition of the additional coating metal according to method step (vi) allows the metal coating to be effectively deposited on the substrate surface to obtain an electrolytically coated surface.

[0165] Preferably, the additional coating metal used during the electrolytic deposition step (vi) is selected from copper, nickel, or alloys thereof, and more preferably copper.

[0166] Preferably, the electrolytic deposition step (vi) is performed by applying an electrolytic copper plating bath, which is well known in the art for this purpose.

[0167] Preferably, the electrolytic copper plating bath comprises copper ions, an electrolyte (typically a strong acid, such as sulfuric acid, fluoroboric acid, or methanesulfonic acid), chloride ions, optionally one or more leveling agents, optionally one or more brightening agents, and optionally one or more carriers. These compounds are known in the art and are disclosed, for example, in WO 2017 / 037040 A1 (page 21, line 1 to page 22, line 27).

[0168] Preferably, step (vi) is performed for a duration of 30 to 120 minutes, preferably 90 minutes, and / or at a temperature of 10°C to 50°C, preferably 32°C.

[0169] Preferably, step (vi) is performed by applying a current density of 1 ASD to 25 ASD, and more preferably by applying a current density of 3 ASD to 15 ASD.

[0170] Preferably, method steps (i), (ii), (iii), (iv), (v) and / or (vi) are performed in a horizontal or vertical process.

[0171] This allows the method according to the first aspect to be effectively applied to several manufacturing scenarios, thereby increasing the flexibility of the method.

[0172] According to the present invention, horizontal or vertical process refers to the orientation of the substrate in the corresponding method steps (i), (ii), (iii), (iv), (v) and / or (vi).

[0173] During the horizontal process, a substrate, specifically shaped as a plate, is transferred horizontally via method steps (i), (ii), (iii), (iv), (v), and / or (vi) such that the lower side of the substrate faces the base plate and the upper side of the substrate faces away from the base plate. During the horizontal process, the substrate is preferably conveyed by a transport device for processing in different processing modules during the respective method steps (i), (ii), (iii), (iv), (v), and / or (vi).

[0174] During the vertical process, a substrate, specifically shaped as a plate, is transferred vertically via method steps (i), (ii), (iii), (iv), (v) and / or (vi) such that the side edges of the substrate face the base plate and the opposite side edges of the substrate face away from the base plate.

[0175] substrate

[0176] Preferably, the conductive through-holes (TH) and / or conductive blind microvias (BMVs) of the dielectric substrate include copper surfaces deposited on the walls of the TH and BMV within the dielectric substrate. The copper layer on the copper surface is conformally deposited (thin and conforming to the wall surface structure), wherein the TH and BMV are not filled with copper.

[0177] Preferably, after step (ii), the organic resin completely fills the conductive TH and conductive BMV, and wherein the organic resin is not removed from the conductive TH and conductive BMV during steps (iii), (iv-1), or (iv-2).

[0178] Preferably, the substrate according to the invention comprises a plate for HDI, MLB production and / or IC substrate articles having fine features, more preferably a plate for horizontal plating applications comprising through-holes (TH) with an aspect ratio of 1:3 to 1:18 and / or blind microvias (BMV) with an aspect ratio of 1:0.5 to 1:2.3, or more preferably a plate for vertical plating applications comprising through-holes (TH) with an aspect ratio of 1:3 to about 1:30 and / or blind microvias (BMV) with an aspect ratio of 1:1 or down to 1:1.15 to 1:2.3.

[0179] Preferably, the deposition of the conductive material according to method step (v) is performed using a palladium species, a conductive polymer, or a carbon species as an activating composition.

[0180] Preferably, the substrate, particularly a dielectric substrate having at least one dielectric surface to be treated, comprises an organic polymer selected from resins and / or plastics and blends thereof, wherein the resins and plastics are more preferably selected from the group consisting of: epoxy resins, isocyanate resins, bismaleimide triazine resins, phenylene resins, polyesters, and even more preferably selected from polyethylene terephthalate (PET), polyimide (PI), polytetrafluoroethylene, acrylonitrile-butadiene-styrene (ABS) copolymers, polyamides (PA), polycarbonate (PC), liquid crystal polymers (LCPs) as cyclic olefin copolymers (COCs), Ajinomoto stacked films (ABF, ABF / epoxy type substrates), or plastics for preparing optically imageable dielectrics, as well as mixtures and blends of the foregoing materials, or composite materials based on a mixture of non-conductive filler particles and / or glass fibers as glass fillers and / or silicon fillers with the organic polymer. The substrate may also be a glass substrate or a silicon substrate.

[0181] Dielectric substrates, which are resin or plastic materials, preferably contain materials that are typically used in the electronics industry for metallization. The materials of the dielectric substrates are chemically different from those of cured organic resins derived from organic pastes.

[0182] Preferably, the organic polymer comprises a polyimide resin or an epoxy resin, wherein the polyimide resin can be modified by adding polysiloxane, polycarbonate, polyester, etc.

[0183] Preferably, the epoxy resin can be a glass-filled epoxy board material comprising a combination of epoxy resin and glass filler, or the epoxy resin can be modified to have a low coefficient of thermal expansion and a high glass transition temperature, thereby constituting a glass-filled epoxy board material with a high glass transition temperature.

[0184] Preferably, the glass filler is selected from borosilicate glass, quartz glass, silicon glass, and / or fluorinated glass. Silicon preferably includes polycrystalline silicon (including doped polycrystalline silicon, such as p-doped and n-doped polycrystalline silicon) as well as monocrystalline silicon, silicon oxide, silicon nitride, and silicon oxygen nitride. The diameter of the different fillers ranges from 0.01 μm to 5 μm, with a preferred average diameter of 0.5 μm.

[0185] The glass fabric, similar to the glass filler, is selected from borosilicate glass, quartz glass, silica glass, and / or fluorinated glass. The glass fabric is woven from individual glass fibers with diameters ranging from a few submicrometers to a few micrometers. The glass fabric provides mechanical stability to the printed circuit board and, together with the resin used, significantly influences the mechanical and thermal properties of the printed circuit board material.

[0186] Preferably, the composite material of the non-conductive layer is a stacked thin film, such as an epoxy-based material. The average diameter of the embedded glass filler is 0.5 μm, with a maximum value of 5.0 μm.

[0187] Second aspect

[0188] According to a second aspect, the present invention relates to a substrate having a chemically treated surface obtained by the method according to the first aspect. More specifically, the present invention relates to an article of manufacture obtained by the method of the first aspect.

[0189] The substrate or the article can be further processed by subsequent cleaning and metallization steps to obtain an article containing a VIPPO (via in-pad plating) structure.

[0190] Preferably, the foregoing content regarding the method according to the first aspect of the invention, and preferably described as preferred, also applies to the substrate of the second aspect of the invention.

[0191] Third aspect

[0192] According to a third aspect, the present invention relates to the use of a non-aqueous composition according to the method of the first aspect for removing organic resin from the surface of a dielectric substrate to manufacture an article comprising a VIPPO (via-in-pad plating) structure, said dielectric substrate comprising a copper surface and conductive through-holes (TH) and / or conductive blind microvias (BMV).

[0193] Preferably, the foregoing content regarding the method according to the first aspect of the invention, and preferably described as preferred, also applies to the use of the third aspect of the invention.

[0194] In preferred applications of non-aqueous compositions, no additional mechanical or wet chemical treatment is required to remove the organic resin as described in the methods above.

[0195] Example

[0196] The following examples provide different samples to illustrate methods for removing organic resin from the surface of a substrate.

[0197] I. Change processing time

[0198] Next, three samples (Sample 1, Sample 2, and Sample 3) are described, each comprising a substrate used during the manufacturing process of a printed circuit board (PCB). The respective substrates are FR-4 dielectric substrates with through-holes (TH), wherein copper layers are deposited on the upper and lower sides of the substrate, and also deposited on the walls of the through-holes (TH).

[0199] In a subsequent step, an epoxy-based organic paste is applied to the dielectric substrate to completely fill the vias (TH), and a 5 μm to 7 μm thick paste layer is also provided on top of the copper layer, the paste layer being deposited on the upper and lower sides of the substrate.

[0200] Subsequently, the organic paste applied to the corresponding substrate is thermally cured by applying a temperature of 150°C under vacuum for 45 minutes. Through this curing process, the epoxy-based organic paste is transformed into a cured organic epoxy resin, which fills the perforations (TH) and covers the copper layers on the upper and lower sides of the substrate.

[0201] Next, the corresponding dielectric substrate is chemically treated with a non-aqueous composition to remove the organic epoxy resin from the surface of the substrate, thereby obtaining the chemically treated surface of the dielectric substrate.

[0202] The non-aqueous compositions (invention examples) of these four samples consist of the following:

[0203] a) 91% by weight of benzyl alcohol;

[0204] b) 6.5% by weight of 2-hydroxy-propionic acid;

[0205] c) 1.25% by weight of at least one C10-C16 alkylbenzene sulfonic acid; and

[0206] d) 1.25% by weight of 2,4,7,9-tetramethyldecyl-5-yne-4,7-diol.

[0207] Sample 1:

[0208] According to Sample 1, the non-aqueous composition was applied at 80°C for 110 seconds.

[0209] Sample 2:

[0210] According to Sample 2, the non-aqueous composition was applied at 80°C for 200 seconds.

[0211] Sample 3:

[0212] According to sample 3, the non-aqueous composition was applied at 80°C for 10 minutes.

[0213] Subsequently, during the first rinsing step, the chemically treated surfaces of the respective dielectric substrates of all samples 1, 2 and 3 are treated for 60 seconds at 60°C with a first rinsing solution containing distilled water, wherein the rinsing step is performed in the presence of ultrasound.

[0214] Subsequently, the rinsed surface of the corresponding dielectric substrate is chemically treated for 12 minutes at 75°C with an oxidizing solution comprising 70 g / L potassium permanganate and 50 g / L sodium hydroxide as oxidants, according to sub-step (de-2). Treatment with the oxidizing solution allows for the effective removal of any residual organic resin from the surface of the corresponding dielectric substrate.

[0215] The second rinsing step is then performed by applying a second rinsing solution, which contains an aqueous sulfuric acid solution, at 50°C for 1 minute.

[0216] Subsequently, according to sub-step (de-3), a reducing agent, serving as the third treatment agent, is applied to the surface of the substrate at 50°C for 4 minutes to obtain a reduced surface of the substrate. The reducing agent comprises 100 ml / L of SecuriganthMV reducing conditioner (based on hydroxyl ammonium sulfate) and 35 ml / L of sulfuric acid. A third rinsing and drying step is then performed.

[0217] The cleaning agent is then applied to the reduced surface of the substrate and left at room temperature for 5 minutes, followed by a fourth rinsing step.

[0218] Subsequently, during the etching step, Securiganth Etching Cleaner C (based on potassium caroate) was applied at 25°C for 1 minute, followed by a fifth rinsing step.

[0219] To analyze the efficiency of removing organic epoxy resin from the upper and lower surfaces of the respective dielectric substrates according to samples 1, 2, and 3, subsequent plating steps were performed by immersing the respective substrates in an electrolytic nickel bath at 40°C for 30 minutes while applying a voltage of approximately 3 ASD. Nickel was used for better visual inspection, but the results for copper deposition were the same (not shown).

[0220] Based on samples 1 to 6, the surfaces of the resulting nickel-coated metal or copper surfaces on the respective substrates were visually analyzed, particularly regarding the presence of any surface defects such as stains, spots, exposed copper, etc., and the surfaces were qualitatively ranked. In this regard, "-" indicates poor surface quality, "--" and "---" indicate even worse surface quality, where organic resin and / or defects such as corrosion are present on the surface, "0" indicates average surface quality, "++" indicates good surface quality, and "+++" indicates excellent surface quality.

[0221] The results are summarized in Table 1.

[0222] Table 1: Optical properties of chemically treated substrates

[0223] sample Optical properties 1 ++ 2 +++ 3 +++

[0224] As can be seen from Table 1, all three samples 1, 2 and 3 show uniform nickel plating, with very few surface defects such as stains, spots, exposed copper, etc., in sample 1. This leads to the conclusion that the non-aqueous composition allows for efficient removal of organic epoxy resin from the corresponding surfaces of the dielectric substrate.

[0225] II. Comparison of the non-aqueous composition of the present invention with the aqueous composition

[0226] Objective: To remove surface epoxy resin without damaging the substrate.

[0227] Three dielectric substrates were treated as described above under -I. with varying processing times, the treatment involving the deposition of an epoxy-based organic compound. After curing, a corresponding dielectric substrate containing a cured organic epoxy layer was chemically treated with the non-aqueous composition of the present invention (sample 4) used above under I.), wherein the process was stopped after an ultrasonic rinsing step. Two dielectric substrates (sample 5 (acidic) and sample 6 (alkaline)) were treated with comparative aqueous compositions to remove the organic epoxy from the surface of the substrates, thereby obtaining the chemically treated surfaces of the dielectric substrates. The optical properties of the copper surface of the chemically treated substrates were then determined, as seen below.

[0228] Sample 4 (Inventive Example)

[0229] a) 90.1% by weight of benzyl alcohol;

[0230] b) 8% by weight of 2-hydroxy-propionic acid;

[0231] c) 1.0% by weight of at least one C10-C16 alkylbenzene sulfonic acid; and

[0232] d) 1.0 wt% of 2,4,7,9-tetramethyldecyl-5-yne-4,7-diol.

[0233] Sample 4, i.e., the non-aqueous composition, was applied at 80°C for 200 seconds.

[0234] Sample 5 – Comparative Acidic Aqueous Composition

[0235] Mix 300 ml of the non-aqueous composition of sample 4 with 700 ml of water and adjust the pH to 3.5.

[0236] Sample 5, the comparative acidic aqueous composition, was applied at 80°C for 200 seconds.

[0237] Sample 6 - Comparative Alkaline Aqueous Composition

[0238] Mix 400 ml of the non-aqueous composition of Sample 1 with 600 ml of water and adjust the pH to 12.

[0239] According to Sample 6, an alkaline non-aqueous composition was applied at 80°C for 200 seconds.

[0240] The results are summarized in Table 2.

[0241] Table 2: Optical properties of chemically treated substrates

[0242] sample Optical properties 4 +++ 5 - 6 ---

[0243] As can be seen from Table 2, the non-aqueous composition (sample 4) allows for efficient removal of organic epoxy resin from the corresponding surface of the dielectric substrate, wherein the copper surface does not show corrosion and exhibits a fine copper-like surface color.

[0244] In contrast, the acidic aqueous comparative composition in Sample 5 was primarily able to remove the organic epoxy resin, but on the other hand, it strongly corroded the copper surface and showed many corrosion spots.

[0245] Even worse were the results for Sample 6. Here, the alkaline aqueous comparative composition in Sample 6 failed to adequately remove the organic epoxy resin. A significant portion of the organic epoxy resin remained visible on the surface. Furthermore, the alkaline aqueous comparative composition also strongly corroded the free copper surface, exhibiting numerous corrosion spots, particularly around the perforations.

Claims

1. A method for removing organic resin from a copper surface on a dielectric substrate, said dielectric substrate comprising conductive through-holes (TH) and / or conductive blind microvias (BMV), said method comprising the following steps: (i) An organic paste is applied to the dielectric substrate to fill the through-hole (TH) and / or the blind microvia (BMV) with the organic paste, wherein after step (i), at least a portion of the surface of the dielectric substrate is covered by the organic paste; (ii) Curing the organic paste to transform it into a cured organic resin, wherein after step (ii), at least a portion of the surface of the dielectric substrate is covered by the organic resin; (iii) Chemically treating the dielectric substrate with a non-aqueous composition to remove the organic resin from the surface of the substrate, thereby obtaining a chemically treated surface of the substrate, the non-aqueous composition comprising: a) At least one high-boiling solvent, wherein the concentration of the at least one high-boiling solvent is from 80% to 95% by weight, preferably from 81 wt.% to 91 wt.% by weight, and the at least one high-boiling solvent is selected from the group consisting of alcohols having the general chemical formula R-OH, wherein R is C4-C. 30 Hydrocarbon group, wherein the boiling point of the high-boiling solvent is at least 100°C. b) At least one carboxylic acid, wherein the concentration of said at least one carboxylic acid is from 5% by weight to less than 20% by weight, preferably from 4% by weight to 9% by weight, more preferably from 7% by weight to 8% by weight, and preferably said at least one hydroxycarboxylic acid. c) At least one anionic aromatic surfactant, wherein the concentration of said at least one anionic aromatic surfactant is from 0.25% by weight to less than 1.5% by weight, preferably from 0.5% by weight to 1% by weight, and preferably said at least one anionic aromatic surfactant is selected from the group consisting of at least one C10-C16-alkylbenzene sulfonic acid and toluene sulfonic acid. d) at least one nonionic alkynyldiol-based surfactant, wherein the concentration of the at least one nonionic alkynyldiol-based surfactant is from 0.25% by weight to less than 1.5% by weight, preferably from 0.5% by weight to 1% by weight, and preferably the at least one nonionic alkynyldiol-based surfactant is selected from the group consisting of at least one C8-C12 alkynyl-diol, more preferably 2,4,7,9-tetramethyldecyl-5-yne-4,7-diol; (iv-1) The chemically treated surface of the substrate obtained after step (iii) is mechanically treated with an abrasive tool to remove residual organic resin from the chemically treated surface of the substrate, thereby obtaining the mechanically treated surface of the substrate. and / or (iv-2) The chemically treated surface of the substrate obtained after step (iii) is subjected to wet chemical treatment with an oxidizing solution containing an oxidizing agent to remove residual organic resin from the chemically treated surface of the substrate, thereby obtaining the wet chemically treated surface of the substrate. (v) Optionally depositing conductive material on the mechanically treated surface obtained after step (iv-1) or on the wet chemically treated surface of the substrate obtained after step (iv-2), preferably electroless depositing coating metal on the mechanically treated surface or the wet chemically treated surface to obtain a conductive surface of the substrate. (vi) Optionally, an additional coating metal is electrolytically deposited on the conductive surface of the substrate obtained after optional step (v), or on the mechanically treated surface of the substrate obtained after step (iv-1), or on the wet chemically treated surface of the substrate after step (iv-2), to obtain an electrolytically coated surface. as well as (vii) Optionally, the surface coated with electrolytic metal in step (vi) is subjected to structural treatment, and solder pads, preferably tin solder pads, are electrolytically deposited to obtain a VIPPO (via-in-pad plating) structure.

2. The method according to claim 1, wherein step (iii) and / or step (iv-2) are performed in the presence of ultrasound provided by an ultrasonic transmitter.

3. The method according to claim 1 or 2, wherein step (iv-1) comprises contacting the chemically treated surface of the substrate with a rotating brush, wherein the rotating brush preferably comprises nylon filaments and ceramic elements.

4. The method according to any of the preceding claims, wherein step (iii) is performed at a temperature of 60°C to 90°C, and preferably for a duration of 1 minute to 15 minutes.

5. The method according to any of the preceding claims, wherein step (iv-1) is performed at room temperature and preferably lasts for a duration of 15 seconds to 5 minutes.

6. The method according to any of the preceding claims, wherein step (iv-1) is performed on the wet surface of the substrate.

7. The method according to any of the preceding claims, wherein step (iv-2) is performed at a temperature of 55°C to 90°C, preferably 65°C to 85°C.

8. The method according to any of the preceding claims, wherein step (iv-2) is performed for a duration of 2 to 20 minutes, preferably 12 minutes.

9. The method according to any of the preceding claims, wherein the oxidant used during step (iv-2) comprises potassium permanganate.

10. The method according to any of the preceding claims, wherein the oxidant used during step (iv-2) is present in the solution in an amount of 35 g / L to 70 g / L based on the total volume of the oxidation solution.

11. The method according to any of the preceding claims, wherein step (iv-2) optionally comprises at least two sub-steps (de) after the rinsing step: The process utilizes the (de-2) etching step and the (de-3) reduction step, which employ the oxidizing solution.

12. The method of claim 11, wherein the sub-step (de) comprises a (de-1) swelling step, the (de-1) swelling step being performed prior to the (de-2) etching step.

13. An article of manufacture obtained by means of the method according to any one of claims 1 to 12.

14. Use of a non-aqueous composition, said non-aqueous composition comprising: a) At least one high-boiling solvent, wherein the concentration of the at least one high-boiling solvent is from 80% to 95% by weight, preferably from 81 wt.% to 91 wt.% by weight, and the at least one high-boiling solvent is selected from the group consisting of alcohols having the general chemical formula R-OH, wherein R is C4-C. 30 Hydrocarbon group, wherein the boiling point of the high-boiling solvent is at least 100°C; b) At least one carboxylic acid, wherein the concentration of the at least one carboxylic acid is from 5% by weight to less than 20% by weight, preferably from 4% by weight to 9% by weight, more preferably from 7% by weight to 8% by weight, and preferably the at least one carboxylic acid is at least one hydroxycarboxylic acid; c) at least one anionic aromatic surfactant, wherein the concentration of said at least one anionic aromatic surfactant is from 0.25% by weight to less than 1.5% by weight, preferably from 0.5% by weight to 1% by weight, and preferably said at least one anionic aromatic surfactant is selected from the group consisting of at least one C10-C16-alkylbenzene sulfonic acid and toluene sulfonic acid; and d) at least one nonionic alkynyldiol-based surfactant, wherein the concentration of the at least one nonionic alkynyldiol-based surfactant is from 0.25% by weight to less than 1.5% by weight, preferably from 0.5% by weight to 1% by weight, and preferably the at least one nonionic alkynyldiol-based surfactant is selected from the group consisting of at least one C8-C12 alkynyl-diol, more preferably 2,4,7,9-tetramethyldecyl-5-yne-4,7-diol; The non-aqueous composition is used to remove organic resin from the surface of a dielectric substrate to manufacture an article comprising a VIPPO (via-in-pad plating) structure, the dielectric substrate comprising a copper surface and conductive through-holes (TH) and / or conductive blind microvias (BMV).