JP2005317986A - Process for producing printed wiring board by use of liquid thermosetting resin composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a process for producing a reliable printed wiring board which is excellent in various properties such as insulating reliability, resistance to heat, resistance to moisture, and PCT resistance without suffering from such defects as the occurrence of cracks and deterioration of insulation reliability during the course of heat cycle, and the ply separation of the insulating resin layer or cover plating formed on cured products filled in hole parts. <P>SOLUTION: In the process for the production of a printed wiring board by stacking an interlaminar resin insulating layer and a conductive circuit on a surface of a wiring board having a conductive circuit pattern including a hole part, a hole filling process is performed by filling the hole parts with a liquid thermosetting resin composition which comprises liquid epoxy resin, a curing catalyst, and a filler, and is characterized by exhibiting a viscosity at 25°C of not more than 1,500 dPas, a gel time of not less than 300 seconds at a temperature at which the composition exhibits a melt viscosity of not more than 10 dPas, and a gel time at 130°C of not more than 600 seconds, and effecting precure of the composition by heating at a temperature in the range of 90 to 130 °C in which the reaction rate of epoxy group is in the range of from 80 to 97%, then polishing and removing parts of the precured composition protruding from a surface defining the hole parts, and further heating the precured composition till final curing which is carried out at a temperature in the range of 140 to 180°C. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention relates to a method for producing a printed wiring board using a liquid thermosetting resin composition. More specifically, the present invention relates to permanent filling such as via holes and through holes in printed wiring boards such as multilayer boards and double-sided boards with good workability. The present invention relates to a method for manufacturing a printed wiring board.
In the present specification, the “hole” is a general term for a via hole, a through hole, or the like formed in the manufacturing process of the printed wiring board.

  In recent years, the pattern of printed wiring boards has been made thinner and the mounting area has been reduced, and further reductions in the size and functionality of printed wiring boards are expected in order to respond to the downsizing and enhancement of functionality of devices equipped with printed wiring boards. It is rare. Therefore, the printed wiring board forms a resin insulation layer on the top and bottom of the core substrate, and after forming the necessary conductor circuit, further forms the resin insulation layer, to the build-up method of the method of forming the conductor circuit, In addition, the mounting components are evolving into area array types such as BGA (ball grid array) and LGA (land grid array). Under such circumstances, it is desired to develop a permanent hole filling composition excellent in filling properties, polishing properties, cured product characteristics, and the like for filling holes such as through holes and via holes.

In general, thermosetting epoxy resin compositions are widely used as permanent hole filling compositions for printed wiring boards because their cured products have excellent mechanical, electrical, and chemical properties and good adhesion. It has been.
In addition, permanent hole filling of a printed wiring board using such an epoxy resin composition is generally a step of filling the hole portion of the printed wiring board with the epoxy resin composition, a state where the filled composition can be heated and polished And a step of polishing and removing a portion protruding from the surface of the hole of the precured composition, and a step of further heating the precured composition to perform main curing.

In the permanent hole filling process of the printed wiring board, voids are inevitably generated due to air entrainment or the like when filling the hole portion such as a through hole or a via hole with the epoxy resin composition. Such voids are difficult to remove completely even after preliminary curing or main curing, and cannot be eliminated. Such a phenomenon becomes more prominent as the depth of the hole is deeper (in the case of a through hole, the thicker the core substrate), and the higher the viscosity of the epoxy resin composition. Further, in the permanent hole filling process of the printed wiring board, there is a problem that cracks occur during preliminary curing.
Furthermore, there is a problem that the shrinkage at the time of heat curing is large, and a gap is generated between the through hole wall after the main curing.

  When voids, cracks, etc. occur in the cured resin composition filled in the hole of the printed wiring board in this way, this part exhibits hygroscopicity, and PCT resistance under high temperature and high humidity (pressure cooker resistance) In addition, cracks during the heat cycle of the printed wiring board and deterioration of insulation reliability are caused. Furthermore, it becomes a factor of delamination of the insulating resin layer and the lid plating formed on the cured material filled in the hole.

  Therefore, the present invention has been made in view of the circumstances as described above, and can fill a via hole, a through hole, etc. of a printed wiring board with good workability, generation of cracks during heat cycle, and insulation. High reliability with excellent insulation reliability, heat resistance, moisture resistance, PCT resistance, etc. without deterioration of reliability, delamination of insulating resin layer and lid plating formed on the cured material filled in the hole An object of the present invention is to provide a method for manufacturing a reliable printed wiring board.

In order to achieve the above object, according to the present invention, in manufacturing a printed wiring board by laminating an interlayer resin insulation layer and a conductor circuit on the surface of a wiring board on which a conductor circuit pattern including a hole is formed,
(A) A liquid thermosetting resin composition comprising (A) a liquid epoxy resin, (B) a curing catalyst, and (C) a filler, having a viscosity at 25 ° C. of 1500 dPa · s or less and a melt viscosity of 10 dPa A step of filling the hole with a liquid thermosetting resin composition having a gel time at a temperature of s or less of 300 seconds or more and a gel time at 130 ° C. of 600 seconds or less;
(B) heating the filled composition to 90 to 130 ° C. and pre-curing so that the reaction rate of epoxy groups is 80 to 97%;
(C) Polishing and removing the portion of the precured composition protruding from the surface of the hole, and (d) Filling the hole including a step of further curing the precured composition at 140 to 180 ° C. A method of manufacturing a printed wiring board including processing is provided.

The “gel time” is measured by a gelation tester based on the hot plate method of JIS C 2105 18.2, and the torque when rotating the rotating rod in 0.4 ml of the sample held at the measurement temperature. Time to reach 30% of maximum torque.
Further, the “melt viscosity” was measured with a flow tester (die hole diameter: 1.0 mm, die length: 10 mm) while applying a load of 1 kg with a piston after 5 minutes of preheating a 2 ml sample held at the measurement temperature. Viscosity.
The liquid thermosetting resin composition described above has a gel time at 25 ° C. of 1500 dPa · s or less and a melt viscosity of 10 dPa · s or less at a temperature of 300 seconds or more and a gel time at 130 ° C. of 600 seconds or less. In addition to being excellent in filling (workability) of hole portions such as via holes and through holes in a printed wiring board, there are specific effects that voids remain and cracks do not occur. In addition, high filler content is possible, cure shrinkage is small, and the resulting cured product has low hygroscopicity and excellent adhesion, low volume expansion under high temperature and high humidity, insulation reliability and heat resistance Excellent in moisture resistance, PCT resistance and the like.

In a preferred embodiment, the pre-curing step is performed in at least two stages so that the heating temperature in the subsequent stage is higher than the previous stage.
In addition, the term “precured” or “precured product” in the present specification refers to a state where the reaction rate of the epoxy group is 80% to 97%.

  By such a method, filling of via holes, through holes, etc. of printed wiring boards can be performed with good workability, crack generation during heat cycle, deterioration of insulation reliability, hardened material filled in holes. A highly reliable printed wiring board with excellent insulation reliability, heat resistance, moisture resistance, PCT resistance, and other characteristics is produced with good productivity without the insulating resin layer or lid plating delamination formed on the substrate. Can do.

The feature of the method for producing a printed wiring board using the liquid thermosetting resin composition of the present invention is that the filling process of through holes and via holes is performed by two-stage curing of pre-curing and main curing (finish curing). It is in a state where it can be polished after pre-curing, and unnecessary portions of the pre-cured product can be polished and removed very easily by physical polishing.
In addition, the epoxy resin precured product has little shrinkage during the main curing, and the final cured product has excellent insulation reliability, heat resistance and moisture resistance, linear expansion coefficient, water absorption rate under high temperature and high humidity conditions, etc. It is advantageous in that the volume expansion is small, and a highly reliable multilayer printed wiring board can be manufactured.

  Furthermore, in a preferred aspect of the method for producing a printed wiring board of the present invention, the preliminary curing step is performed in at least two stages so that the heating temperature in the subsequent stage is higher than the previous stage. That is, as the primary pre-curing, first, the epoxy resin is not subjected to a crosslinking reaction, and heat treatment is performed at a temperature at which the melt viscosity is 10 dPa · s or less until the voids are removed. Heat treatment is performed at a temperature at which the cross-linking reaction occurs until polishing is possible (epoxy reaction rate 80% to 97%). For example, prior to pre-curing (secondary pre-curing) at 130 ° C., which is a normal pre-curing temperature, primary pre-curing is performed at a temperature lower than this, for example, around 100 ° C. By performing multi-stage pre-curing in this way, it is easy to remove bubbles and suppress the occurrence of voids and cracks during pre-curing.

The first feature of the liquid thermosetting resin composition used in the method for producing a printed wiring board of the present invention is that the viscosity at 25 ° C. is 1500 dPa · s or less. As a result, the printed wiring board has excellent fillability in holes such as through-holes and via holes. Conventionally known and commonly used techniques such as screen printing methods and roll coating methods can be used for printed wiring board via holes and the like. The hole can be filled with the composition with good workability.
The second feature of the composition is that the gel time at a temperature of a melt viscosity of 10 dPa · s or less is 300 seconds or more. By setting the gel time at a melt viscosity of 10 dPa · s or less to 300 seconds or more, voids can be reliably removed.
Furthermore, the third characteristic of the composition is that the gel time at 130 ° C. is 600 seconds or less. If the gel time is over 600 seconds, cracks are likely to occur during preliminary curing.
In addition, although the void tends to remain as the gel time becomes earlier, the remaining of the void can be prevented by regulating the gel time at a temperature of melt viscosity of 10 dPa · s or less to 300 seconds or more. That is, by regulating both the upper limit of the gel time at 130 ° C. and the lower limit of the gel time at a temperature of melt viscosity of 10 dPa · s or less, an appropriate pre-curing speed is achieved, and void remaining and cracking are prevented. be able to.

Hereinafter, each component of the liquid thermosetting resin composition used in the method for producing a printed wiring board of the present invention will be described in detail.
First, as the epoxy resin (A), any known resin can be used. Specific examples include various epoxy resins such as bisphenol A type, bisphenol F type, bisphenol S type, phenol novolac type, and cresol novolac type. These can be used singly or in combination of two or more according to the demand for improving the properties of the coating. However, the viscosity of the composition needs to be 1500 dPa · s or less at 25 ° C.
In addition, other thermosetting resins, such as a phenol resin, can be used together within the said viscosity range.

  Any curing catalyst (B) may be used as long as it has the effect of promoting the curing reaction of the epoxy resin so that the gel time at 130 ° C. is 600 seconds or less depending on the epoxy resin used, as described above. It can be used and is not limited to a specific one. Among these, an imidazole derivative is preferable in that the gel time at 130 ° C. is easily adjusted to 600 seconds or less, and examples thereof include 2-methylimidazole, 4-methyl-2-ethylimidazole, 2-phenylimidazole, 4- Methyl-2-phenylimidazole, 1-benzyl-2-methylimidazole, 2-ethylimidazole, 2-isopropylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1- And cyanoethyl-2-undecylimidazole. Specific examples of commercially available products include imidazoles such as trade names 2E4MZ, C11Z, C17Z, and 2PZ, and AZ INE compounds of imidazoles such as trade names 2MZ-A and 2E4MZ-A, and trade names 2MZ-OK and 2PZ-. Examples thereof include isocyanurate of imidazole such as OK, and imidazole hydroxymethyl compounds such as trade names 2PHZ and 2P4MHZ (the trade names are all manufactured by Shikoku Kasei Kogyo Co., Ltd.).

  Besides imidazole, dicyandiamide and its derivatives, melamine and its derivatives, diaminomaleonitrile and its derivatives, diethylenetriamine, triethylenetetramine, tetramethylenepentamine, bis (hexamethylene) triamine, triethanolamine, diaminodiphenylmethane, organic acid Amines such as hydrazide, 1,8-diazabicyclo [5.4.0] undecene-7 (trade name DBU, manufactured by San Apro), 3,9-bis (3-aminopropyl) -2,4,8 , 10-tetraoxaspiro [5.5] undecane (trade name ATU, manufactured by Ajinomoto Co., Inc.), or an epoxy using an organic phosphine compound such as triphenylphosphine, tricyclohexylphosphine, tributylphosphine, or methyldiphenylphosphine As gel time at 130 ° C. Depending on the fat is less than or equal to 600 seconds, can be used alone or in combination of two or more. However, when aromatic amines are used, the resin composition after heat-curing shrinks greatly, and it is preferable because voids are likely to form between the through-hole walls after curing and voids in the cured product in the hole filling portion. Absent. Among these curing catalysts, dicyandiamide, melamine, acetoguanamine, benzoguanamine, 3,9-bis [2- (3,5-diamino-2,4,6-triazaphenyl) ethyl] -2,4,8 , 10-tetraoxaspiro [5.5] undecane and derivatives thereof, and their organic acid salts and epoxy adducts are known to have adhesion and rust prevention properties with copper. In addition to acting as a curing catalyst for the resin, it can contribute to the prevention of discoloration of copper in the printed wiring board.

  The blending amount of the curing catalyst (B) as described above may be a quantitative ratio such that the gel time at 130 ° C. is 600 seconds or less depending on the epoxy resin used. In general, the epoxy resin (A) 100 3 parts by mass or more and 20 parts by mass or less, preferably 5 parts by mass or more and 15 parts by mass or less are appropriate per part by mass. When the blending amount of the curing catalyst (B) is less than 3 parts by mass, the pre-curing rate of the resin composition generally decreases as the gel time exceeds 600 seconds, and voids and cracks are likely to occur. On the other hand, when the blending amount of the curing catalyst (B) exceeds 20 parts by mass, generally the preliminary curing rate of the resin composition becomes too fast and voids are likely to remain, which is not preferable.

As the filler (C), all conventionally known inorganic fillers and organic fillers can be used, and the filler (C) is not limited to a specific one. Especially, in the liquid thermosetting resin composition of the present invention, filling into a through hole or the like is possible. In order to enable high filler blending without impairing the workability (workability), it is preferable to include a spherical filler and a pulverized filler as the filler (C). In a particularly preferred embodiment, spherical fillers include spherical fine fillers and spherical coarse fillers.
Among these fillers, the spherical fine filler and the spherical coarse filler play a role of increasing the filler content, while the pulverized filler plays a role of preventing a decrease in filling property due to a change in viscosity and thixotropy. In particular, in order to effectively exert such a role, the average particle size of the spherical fine filler is 0.1 μm or more and less than 3 μm, more preferably 1.0 to 2.0 μm, and the average particle size of the spherical coarse filler is 3 μm or more and less than 25 μm, more preferably 4 to 10 μm, and the average particle size of the pulverized filler is preferably 25 μm or less, more preferably 10 μm or less. In addition, it is preferable that the average particle diameter difference of a spherical fine filler and a spherical coarse filler is 2-12 micrometers.

Any filler (C) having such a form may be used as long as it is used as a normal resin filler. For example, extender pigments such as silica, precipitated barium sulfate, talc, calcium carbonate, silicon nitride and aluminum nitride, and metal powders such as copper, tin, zinc, nickel, silver, palladium, aluminum, iron, cobalt, gold and platinum The body is mentioned.
Such fillers are classified into spherical fillers and pulverized fillers other than spherical shapes depending on their shapes, but spherical fillers are classified into spherical fine fillers and spherical coarse fillers as described above according to their average particle size. . As the spherical fine filler and the spherical coarse filler, spherical silica is preferable. Among the fillers (inorganic fillers), silica is particularly excellent in low hygroscopicity and low volume expansion. Silica may be a mixture thereof regardless of melting or crystallinity.
The shape of the pulverized filler includes shapes other than spherical shapes, such as needle shape, plate shape, scale shape, hollow shape, indefinite shape, hexagonal shape, cubic shape, and flake shape.

In such a filler, the mixing ratio of the spherical fine filler and the spherical coarse filler is preferably 40 to 10:60 to 90 in terms of mass ratio. More preferably, it is 30-20: 70-80.
Moreover, it is preferable that the compounding quantity of a grinding | pulverization filler is 5-20 mass% of the filler whole quantity. If the amount is less than 5% by mass, the fluidity of the composition becomes too high. On the other hand, if the amount exceeds 20% by mass, the fluidity of the composition deteriorates, and in any case, the filling property is lowered.
The total amount of the mixed filler is preferably 40 to 95% by mass of the total amount of the composition. If it is less than 40% by mass, the obtained cured product cannot exhibit sufficient low expansibility, and further, the polishing properties and adhesion are insufficient. On the other hand, when it exceeds 95% by mass, it is difficult to form a liquid paste, and printability, hole filling and filling properties cannot be obtained.

In the liquid thermosetting resin composition of the present invention, a coupling agent (D) such as a titanate coupling agent, a silane coupling agent, or an aluminum coupling agent may be added in addition to the above-described components. preferable. The method of adding these coupling agents may be either a method of adding directly to the composition or a method of adding a filler (C) pretreated with a coupling agent in advance. Among these coupling agents, it is preferable to use a titanate coupling agent.
The presence of the coupling agent in the liquid thermosetting resin composition improves the wettability of the resin and filler, and lowers the viscosity of the composition. Therefore, the viscosity and gel time characteristics defined in the present invention are maintained. However, the filler can be highly compounded. Further, even when a large amount of filler is blended, the viscosity can be easily adjusted, and voids remaining and cracks can be greatly reduced.

Examples of titanate coupling agents include tetranormal butyl titanate, isopropyl tris (dioctyl pyrophosphate) titanate, isopropyl tri-n-dodecylbenzenesulfonyl titanate, tetra (2,2-diallyloxymethyl-1-butyl) bis (di-). Tridecyl) phosphite titanate, tetraisopropyl bis (dioctyl phosphite) titanate, tetraoctyl bis (ditridecyl phosphite) titanate, isopropyl triisostearoyl titanate, bis (dioctyl pyrophosphate) oxyacetate titanate, bis (dioctyl pyrophosphate) ethylene Examples thereof include titanate and isopropyltri (N-aminoethyl-aminoethyl) titanate.
The silane coupling agent has an alkoxysilane group to which at least two methoxy groups, ethoxy groups, propoxy groups, butoxy groups and the like are bonded at one end, and an amino group at the other end. Any known compound having an amine-based end group such as a urea group can be used. Specific examples include γ-ureidopropyl triethoxysilane, γ-aminopropyl triethoxysilane, N-β- (aminoethyl) -γ-aminopropyl triethoxysilane, and the like.
Examples of the aluminum coupling agent include (alkyl acetoacetate) aluminum diisopropylate.
These coupling agents (D) can be used alone or in combination of two or more, and the blending amount thereof is preferably 0.1 to 5 parts by mass per 100 parts by mass of the filler (C).

In the liquid thermosetting resin composition of the present invention, since an epoxy resin is appropriately selected and used so that the viscosity is 1500 dPa · s or less, it is not always necessary to use a diluting solvent, but the viscosity of the composition is adjusted. In order to do so, a diluent solvent may be added to such an extent that no voids are generated.
Diluting solvents include ketones such as methyl ethyl ketone and cyclohexanone; aromatic hydrocarbons such as toluene, xylene and tetramethylbenzene; methyl cellosolve, butyl cellosolve, methyl carbitol, butyl carbitol, propylene glycol monomethyl ether, dipropylene glycol mono Glycol ethers such as ethyl ether and triethylene glycol monoethyl ether; Esters such as ethyl acetate, butyl acetate and acetic acid ester of the above glycol ethers; Alcohols such as ethanol, propanol, ethylene glycol and propylene glycol; Octane And aliphatic hydrocarbons such as decane; petroleum solvents such as petroleum ether, petroleum naphtha, hydrogenated petroleum naphtha, and solvent naphtha.

  Further, the liquid thermosetting resin composition of the present invention may be a known and commonly used phthalocyanine blue, phthalocyanine green, iodin green, disazo yellow, crystal violet, titanium oxide, carbon black, naphthalene black or the like. Coloring agents, known conventional thermal polymerization inhibitors such as hydroquinone, hydroquinone monomethyl ether, tert-butylcatechol, pyrogallol, phenothiazine, clay, kaolin, organic bentonite, montmorillonite, etc. Thickeners or thixotropic agents, antifoaming and / or leveling agents such as silicones, fluorines and polymers, imidazole, thiazoles, triazoles, silane coupling agents, etc. Una can be blended additives such conventionally known. In particular, when organic bentonite is used, a precured product portion protruding from the surface of the hole portion is easily formed in a protruding state that can be easily polished and removed, and is excellent in polishing properties.

The liquid thermosetting filling composition of the present invention thus obtained is a via hole or through hole of a printed wiring board using a conventionally used method such as a screen printing method, a roll coating method, a die coating method or the like. It is possible to easily fill the holes such as.
Next, for example, the film is preliminarily cured by heating at about 90 to 130 ° C. for about 30 to 90 minutes. Preferably, the primary preliminary curing is performed at about 90 to 110 ° C. as described above, and then the second preliminary curing is performed at about 110 to 130 ° C. Since the hardness of the cured product preliminarily cured in this manner is relatively low, unnecessary portions protruding from the substrate surface can be easily removed by physical polishing, and a flat surface can be obtained.

Thereafter, the film is again heated at about 140 to 180 ° C. for about 30 to 90 minutes to be fully cured (finish cured). At this time, since the liquid thermosetting resin composition of the present invention has low expansibility, the cured product hardly expands or contracts, and the final curing excellent in dimensional stability, low hygroscopicity, adhesion, electrical insulation, etc. It becomes a thing. The cured product thus obtained is excellent in thermal reliability, heat resistance and moisture resistance, and has almost no volume expansion even under high temperature and high humidity, and is excellent in PCT resistance. The hardness of the precured product can be controlled by changing the precuring heating time and heating temperature.
As described above, according to the permanent hole filling process of the printed wiring board using the liquid thermosetting resin composition of the present invention, the hole of the printed wiring board can be filled with good workability and productivity, and after filling the hole. The cured product has excellent properties and physical properties.
Note that the liquid thermosetting resin composition of the present invention is not only used as a permanent hole filling composition for printed wiring boards, but also because of the excellent characteristics as described above, solder resists, interlayer insulating materials, and IC package sealing. It can use suitably also for other uses, such as a material.

  Hereinafter, a method for producing a printed wiring board of the present invention will be specifically described with reference to the accompanying drawings. The method described below is an example of a method for producing a multilayer printed wiring board by a semi-additive method. However, in the method for producing a printed wiring board in the present invention, a conventional method such as a full additive method, a multi-lamination method, a pin lamination method, etc. Various known methods can be employed.

(1) Formation of a through hole First, as shown in FIG. 1 (a), a through hole is drilled in a substrate 1 laminated with a copper foil 2, and electroless plating is applied to the wall surface of the through hole and the surface of the copper foil. Hole 3 is formed. As the substrate, a glass epoxy substrate, a polyimide substrate, a bismaleimide-triazine resin substrate, a fluororesin substrate, or a resin substrate, a copper-clad laminate of these resin substrates, a ceramic substrate, a metal substrate, or the like can be used. In the case of a substrate with poor plating, such as a fluororesin substrate, surface modification such as a pretreatment agent made of organometallic sodium or plasma treatment is performed.
Next, electrolytic plating is performed for thickening, and a plating film 4 is formed on the substrate surface and the inner wall of the through hole 3 as shown in FIG. As this electrolytic plating, copper plating is preferable.

(2) Filling the hole The liquid thermosetting resin composition of the present invention is filled into the through hole 3 formed in (1) as shown in FIG. Specifically, a mask having an opening in the through hole portion can be placed on the substrate and applied by a printing method or the like, or can be easily filled into the through hole 3 by a dot printing method or the like.
Next, after pre-curing the filler by the method as described above, unnecessary portions of the pre-cured product 5 protruding from the through holes are removed by polishing and flattened as shown in FIG. . Polishing can be suitably performed by belt sander, buffing or the like. Then, it further heats and carries out a main hardening and roughens the exposed surface of the hardened | cured material 5 as needed. When soluble particles are dispersed in the roughening solution in the cured product, the roughened surface is dissolved and removed, and a roughened surface with an excellent anchor effect is formed. It will be excellent in adhesion.

(3) Formation of conductor circuit layer After providing a catalyst nucleus on the surface of the substrate in which the through hole was filled in (2), electroless plating and electrolytic plating were performed, and plating was performed as shown in FIG. A film 6 is formed. Thereafter, an etching resist 7 is formed as shown in FIG. 1F, and the non-resist forming portion is etched. Next, the etching resist 7 is peeled to form the conductor circuit layer 8 as shown in FIG. As the etchant, conventionally known ones such as an aqueous solution of hydrogen sulfate, an aqueous solution of persulfate such as ammonium persulfate, sodium persulfate and potassium persulfate, and an aqueous solution of ferric chloride and cupric chloride can be used.

(4) Formation of Interlayer Resin Insulating Layer After that, the surface of the conductor circuit layer is treated by a method such as blackening (oxidation) or reduction treatment as necessary, and then, as shown in FIG. Layer 10 is formed. As the interlayer resin insulating layer, a thermosetting resin, a photocurable resin, a thermoplastic resin, or a composite or mixture of these resins, a glass cloth impregnated resin composite, or an electroless plating adhesive can be used. The interlayer resin insulation layer 10 is formed by applying an uncured liquid of these resin compositions or laminating a film-like resin by thermocompression bonding.

(5) Formation of Via Hole Next, an opening 11 is provided in the interlayer resin insulation layer 10 as shown in FIG. The perforation of the opening 11 is performed by exposure and development processing when the interlayer resin insulating layer 10 is made of a photosensitive resin, and laser light is used when the interlayer resin insulating layer 10 is made of a thermosetting resin or a thermoplastic resin. Examples of the laser light used at this time include a carbon dioxide laser, an ultraviolet laser, and an excimer laser. In the case of drilling with laser light, desmear treatment may be performed. This desmear treatment can be performed by using an oxidizing agent made of an aqueous solution such as chromic acid or permanganate, or may be treated with oxygen plasma or the like.
After the opening 11 is formed, the surface of the interlayer resin insulation layer 10 is roughened as necessary.
Next, after providing a catalyst nucleus for electroless plating on the surface of the interlayer resin insulation layer 10, electroless plating is performed to form a plating film 12 on the entire surface as shown in FIG.
Then, as shown in FIG. 2C, a plating resist layer 13 is formed on the plating film 12. The plating resist layer is preferably formed by laminating a photosensitive dry film, exposing and developing.
Further, electrolytic plating is performed to thicken the conductor circuit portion, and an electrolytic plating film 14 is formed as shown in FIG.
Next, after the plating resist layer 13 is peeled off, the electroless plating film 12 under the plating resist is dissolved and removed by etching, and as shown in FIG. 2D, an independent conductor circuit (including via holes 15) is obtained. Form. As an etchant, an aqueous solution of sulfuric acid monohydrogen peroxide, an aqueous solution of persulfate such as ammonium persulfate, sodium persulfate, or potassium persulfate, an aqueous solution of ferric chloride or cupric chloride, and the like can be suitably used.

FIG. 3 shows a schematic process of another example of the method for producing a printed wiring board. After finishing the core substrate manufacturing process as shown in FIG. 1D, the conductor layers on both surfaces of the core substrate 20 are formed. When etching is performed in accordance with a predetermined pattern, a first conductor circuit layer 21 having a predetermined pattern is formed on both surfaces of the substrate 20 as shown in FIG. 3A, and a conductor circuit connected to the through hole 22 is formed. A land 23 is simultaneously formed on a part of the layer. At this time, in the polishing step of the cured product 5, the conductor layer is also polished at the same time, and the thickness thereof is uniform and flat. Can be obtained.
Next, an interlayer resin insulation layer 24 is formed on both the upper and lower surfaces of the substrate 20 as shown in FIG. Further, as shown in FIG. 3C, via holes 25 are formed in the resin insulating layer located immediately above the lands 23 by a known photolithography technique. Next, a copper plating layer is formed by copper plating in the via hole and on the interlayer resin insulating layer, and an etching resist is formed thereon, and then etching is performed. As a result, a second conductor circuit layer 26 is formed on the interlayer resin insulation layer 24 as shown in FIG. The first and second conductor circuit layers 21 and 26 are electrically connected to each other through the via hole 25, and the conductor circuit layers 21 and 21 on both surfaces of the substrate are also electrically connected to each other via the through hole 22.
Then, as shown in FIG. 3C, a solder resist layer 27 is formed on each resin insulating layer 24 and the second conductor circuit layer 26, and the upper resist layer penetrates through this and forms a conductor circuit. A solder bump 28 standing from the surface of the layer is formed. The conductor circuit layer 30 exposed from the opening 29 formed between the lower resist layers can be plated with Au and Ni to obtain a multilayer wiring board used as a connection terminal. The solder bump 28 is used for connection with an electronic component such as an IC element disposed on the main surface of the wiring board.

  EXAMPLES Hereinafter, the present invention will be described in detail with reference to examples and comparative examples, but the present invention is not limited to the following examples. In the following description, “parts” are all based on mass unless otherwise specified.

Examples 1-12 and Comparative Examples 1-5
Each component listed in Table 1 below was blended at room temperature with a liquid epoxy resin (manufactured by Yuka Shell Epoxy Co., Ltd., trade name Epicoat 828 and Epicoat 807) in the proportions shown in Table 1, and after preliminary mixing, three A thermosetting resin composition was obtained by dispersing the meat in a roll mill.

  About the viscosity at 25 degreeC of the liquid thermosetting resin composition of Examples 1-12 obtained in this way and Comparative Examples 1-5, the melt viscosity at 100 degreeC, and the gel time at 100 degreeC and 130 degreeC Measurement was performed by the following method, and cracks, voids remaining, filling properties, polishing properties, curing shrinkage, and volume expansion of the cured product filled in the hole of the wiring board were evaluated by the following methods. The test results are shown in Table 2.

Viscosity at 25 ° C:
A sample of 0.2 ml was collected, and a 30 second value at 25 ° C. and a rotation speed of 5 rpm was defined as a viscosity using a cone plate viscometer (manufactured by Toki Sangyo Co., Ltd.).

Melt viscosity measurement:
Measuring device: Shimadzu flow tester CFT-100D (manufactured by Shimadzu Corporation)
Measuring method:
(I) Set the sample stage to the measurement temperature (100 ° C.).
(Ii) Weigh 2 ml of sample with a syringe.
(Iii) The sample is poured into the sample stage, and after 5 minutes of preheating, a load is applied with the piston.
Measurement condition:
Load: 1kg
Die hole diameter: 1.0mm
Die length: 10mm

Gel time measurement:
Measuring apparatus: automatic gelation tester Measuring method: 0.4 ml of a sample is weighed and placed on an iron plate maintained at a measuring temperature (100 ° C., 130 ° C.). A polytetrafluoroethylene rod was rotated on the sample, and the time until the sample torque reached 30% of the maximum torque was measured and used as the gel time.

crack:
Each composition was filled in the through holes by a screen printing method on a glass epoxy substrate (plate thickness 1.6 mm, through hole diameter 0.3 mm) on which through holes had been formed in advance by panel plating. This was put into a hot-air circulating drying furnace, held at 100 ° C. for 20 minutes, then heated to 130 ° C. and pre-cured for 45 minutes to obtain an evaluation sample (I). Thereafter, this evaluation sample (I) is cut at the through-hole portion, the cross section is observed with an optical microscope, the through-hole in which a crack is generated in the sample is NG, and the ratio of NG to the number of holes observed is Calculated. Judgment criteria are as follows.
○: Crack occurrence rate 0%
Δ: Crack generation rate 50% or less ×: Crack generation rate over 50%

Void residue:
The said evaluation sample (I) was cut | disconnected by the through hole part, the cross section was observed with the optical microscope, and the presence or absence of the void in a through hole was confirmed. The through hole in which the void remained was defined as NG, and the ratio of NG to the observed number of holes was calculated.
○: Void residual rate 0%
Δ: Void residual ratio 50% or less ×: Void residual ratio more than 50%

Fillability:
Each composition was filled in the through hole under the following conditions by a screen printing method on a glass epoxy substrate (plate thickness 1.6 mm, through hole diameter 0.3 mm) on which a through hole had been formed in advance by panel plating. This was put into a hot-air circulation type drying furnace, held at 100 ° C. for 20 minutes, then heated to 130 ° C. and pre-cured for 45 minutes. Then, it cut | disconnected in the through hole part, the cross section was observed with the optical microscope, and the filling condition of the composition in a through hole was confirmed.
Version: Metal mask (Metal thickness: 0.1mm)
Squeegee mounting angle: 75 °
Printing speed: 3.0cm / sec
Dropping amount: 2.5mm
Judgment criteria are as follows.
○: The through hole is completely filled.
×: Insufficient filling

Abrasiveness:
The evaluation sample (I) was physically polished with a buffing uniaxial shaft corresponding to # 320 with a buffing machine, and the cured product was removed from the unnecessary cured portion after preliminary curing. The ease of polishing removal was evaluated by the number of passes until complete removal at that time. Judgment criteria are as follows.
○: 2 passes or less △: 3 or 4 passes ×: 5 passes or more

Curing shrinkage:
The evaluation sample (I) was physically polished with a buffing uniaxial shaft corresponding to # 320 with a buffing machine to remove a cured product from an unnecessary cured portion after preliminary curing, and smoothed. Then, it put into the hot-air circulation type drying furnace, main curing was performed at 150 degreeC for 1 hour, and evaluation sample (II) was obtained. This evaluation sample (II) was cut at the through-hole portion, and the cross section was observed with an optical microscope. At that time, the level difference from the substrate surface due to the dent of the composition filled in was regarded as curing shrinkage, and the presence or absence of curing shrinkage was evaluated.

Volume expansion:
A solder resist was applied over both surfaces of the evaluation sample (II) to form a coating film, and then treated under conditions of PCT (121 ° C., 100% RH) for 96 hours. When the volume expansion of the composition in the hole is large, the solder resist on the through hole is pushed up, and the solder resist is peeled off from the substrate, and the degree of peeling is observed and evaluated with an optical microscope. It is.
○: Solder resist does not peel off ×: Solder resist peels off

表２に示す結果から明らかなように、本発明の実施例１〜１２の液状熱硬化性樹脂組成物によれば、ボイドの残留を生じることなく、穴部への充填性や予備硬化物の研磨性に優れ、また得られる硬化物にはクラックや硬化収縮は発生せず、体積膨張も生じなかった。
これに対し、溶融粘度１０ｄＰａ・ｓ以下の温度（１００℃）でのゲルタイムが３００秒未満の比較例１及び１３０℃でのゲルタイムが６００秒を超える比較例２、４、５の液状熱硬化性樹脂組成物では、いずれも硬化物にクラックが発生するか、又はボイドの残留を生じた。一方、２５℃での粘度が１５００ｄＰａ・ｓを超える比較例３の組成物は、穴部への充填性に劣っており、またボイドの残留も生じた。また、有機ベントナイトを用いた比較例１〜３では研磨性は優れていたが、フィラーを添加しなかった比較例４では、研磨性が劣り、また硬化収縮が生じた。
また、実施例１１と比較例３を比較すれば明らかなように、カップリング剤の添加により、樹脂とフィラーの濡れ性が向上し、液状熱硬化性樹脂組成物の粘度が低下するため、フィラーを多量に配合しても本発明で規定する粘度及びゲルタイムの特性が維持され、ボイドの残留やクラックを全く生じることなく、穴部への充填性や予備硬化物の研磨性に優れていた。

As is apparent from the results shown in Table 2, according to the liquid thermosetting resin compositions of Examples 1 to 12 of the present invention, the filling property to the hole portion and the precured material can be obtained without leaving voids. It was excellent in abrasiveness, and cracks and shrinkage did not occur in the obtained cured product, and volume expansion did not occur.
On the other hand, the liquid thermosetting properties of Comparative Example 1 in which the gel time at a melt viscosity of 10 dPa · s or less (100 ° C.) is less than 300 seconds and Comparative Examples 2, 4, and 5 in which the gel time at 130 ° C. exceeds 600 seconds. In the resin compositions, cracks occurred in the cured product or voids remained. On the other hand, the composition of Comparative Example 3 having a viscosity at 25 ° C. exceeding 1500 dPa · s was inferior in the filling property into the hole, and voids remained. Further, in Comparative Examples 1 to 3 using organic bentonite, the polishing property was excellent, but in Comparative Example 4 in which no filler was added, the polishing property was inferior and curing shrinkage occurred.
Further, as apparent from a comparison between Example 11 and Comparative Example 3, the addition of the coupling agent improves the wettability of the resin and the filler and decreases the viscosity of the liquid thermosetting resin composition. Even when a large amount of is added, the viscosity and gel time characteristics defined in the present invention are maintained, and void filling and cracking are not generated at all, and the hole filling property and pre-cured product polishing property are excellent.

  As described above, by using the liquid thermosetting resin composition of the present invention, it is possible to perform filling of via holes, through holes, etc. of the printed wiring board with good workability, generation of cracks during heat cycle, There is no deterioration in insulation reliability, there is no insulation resin layer formed on the cured material filled in the hole or delamination of the lid plating, etc., and the insulation reliability, heat resistance, moisture resistance, PCT resistance, etc. are excellent. A highly reliable printed wiring board can be manufactured with high productivity.

It is a schematic sectional drawing which shows an example of the manufacturing method of the multilayer printed wiring board by this invention to an intermediate process. It is a schematic sectional drawing which shows the process after an example of the manufacturing method of the multilayer printed wiring board by this invention shown in FIG. It is a schematic sectional drawing which shows the other example of the manufacturing method of the multilayer printed wiring board by this invention.

Explanation of symbols

1,20 Substrate 2 Copper foil 3,22 Through hole 4, 6, 12, 14 Plating film 5 Cured product (precured product)
7 Etching resist 8, 21, 26, 30 Conductor circuit layer 10, 24 Interlayer resin insulation layer 11 Opening 13 Plating resist layer 23 Land 25 Via hole 27 Solder resist layer 28 Solder bump 29 Opening

Claims (2)

In manufacturing a printed wiring board by laminating an interlayer resin insulation layer and a conductor circuit on the surface of a wiring board on which a conductor circuit pattern including a hole is formed,
(A) A liquid thermosetting resin composition comprising (A) a liquid epoxy resin, (B) a curing catalyst, and (C) a filler, having a viscosity at 25 ° C. of 1500 dPa · s or less and a melt viscosity of 10 dPa A step of filling the hole with a liquid thermosetting resin composition having a gel time at a temperature of s or less of 300 seconds or more and a gel time at 130 ° C. of 600 seconds or less;
(B) heating the filled composition to 90 to 130 ° C. and pre-curing so that the reaction rate of epoxy groups is 80 to 97%;
(C) Polishing and removing the portion of the precured composition protruding from the surface of the hole, and (d) Filling the hole including the step of further curing the precured composition at 140 to 180 ° C. A method for producing a printed wiring board comprising processing. The method according to claim 1, wherein the pre-curing step (b) is performed in two stages of primary pre-curing at 90 to 110 ° C and secondary pre-curing at 110 to 130 ° C.

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