JP2010050261A - Method of manufacturing wiring board, and wiring board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a wiring board with high insulation reliability between a conductive substrate and via in a wiring board having vias on the conductive substrate through an insulation layer. <P>SOLUTION: The method of manufacturing the wiring board includes a process for preparing the conductive substrate having a through-hole, a process for immersing the substrate in a solution in which aryldiazonium salt having a reactive substituent is dissolved, a process for arranging a resin composition containing organic resin which reacts with the reactive substituent on a wall surface of the through-hole, a process for forming the insulation layer having an electrical insulation property by curing the resin composition, and a process for arranging a conductive layer on an opposite side to the substrate while the insulation layer is sandwiched therebetween. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a wiring board including a conductive core board and a wiring board.

  With recent downsizing and higher performance of electronic devices, semiconductor devices constituting the electronic devices and multilayer wiring boards on which the devices are mounted are required to be smaller and thinner, have higher performance, and have higher reliability. In response to these requirements, bare chip mounting is performed in which a semiconductor element is directly mounted on a printed circuit board. In addition, with the increase in the number of pins of semiconductor elements, the necessity of multilayering a substrate on which the semiconductor elements are mounted is increasing. Furthermore, the increase in the number of pins is also essential for tester boards for testing semiconductors. As an example of the multilayered substrate, there is a built-up type multilayer wiring substrate capable of fine wiring in which insulating layers and conductor layers are alternately stacked on one side or both sides of a base.

  In bare chip mounting, a silicon chip is mounted directly on a printed board (glass cloth-epoxy substrate). The thermal expansion coefficient of the silicon chip is about 3.5 ppm / ° C. The thermal expansion coefficient of an epoxy resin, which is an inexpensive and general-purpose material for the insulating layer, is usually 40 ppm / ° C. or higher even when the thermal expansion coefficient is a resin in which an inorganic filler is mixed to reduce the thermal expansion coefficient. For this reason, the thermal expansion coefficient of the glass cloth-epoxy substrate is 12 to 20 ppm / ° C., and the difference from that of the silicon chip is large. Therefore, there is a problem that the wiring inside the printed board on which the silicon chip is mounted is easily cut off due to a temperature change. Therefore, development of a wiring board having a thermal expansion coefficient close to that of an object to be mounted has been performed. For example, instead of glass cloth, wiring using a material having a thermal expansion coefficient close to the thermal expansion coefficient of an object to be mounted, such as carbon fiber or invar having a thermal expansion coefficient of about 1.0 to 2.0 ppm / ° C. There is an example of using a substrate. A wiring board including a conductive material such as carbon fiber or invar is usually electrically connected between a conductive wiring (via) provided in a through hole (through hole) penetrating both surfaces of an insulating layer and the board. An insulating layer for ensuring insulation is provided. This insulating layer can be provided, for example, by filling an insulating resin inside the through hole of the conductive substrate by a printing method, and further forming a through hole in the filled resin. Wiring is provided in the through hole formed in the resin, for example, by plating.

However, when the resin is filled, voids (voids) are generated due to insufficient filling of the resin, and cracks occur due to temperature changes. The plating solution for forming the wiring is likely to penetrate into the voids and cracks during production. For this reason, there is a possibility that the via and the conductive substrate are electrically connected (short-circuited).
JP 2006-222216 A

  An object of the present invention is to provide a method of manufacturing a wiring board having high insulation reliability between the conductive board and the via in the wiring board including the conductive core board.

According to one aspect of the invention,
Preparing a conductive substrate having a through hole;
Immersing the substrate in a solution in which an aryldiazonium salt having a reactive substituent is dissolved;
Providing a resin composition containing an organic resin capable of reacting with the reactive substituent on the wall surface of the through hole;
Curing the resin composition to form an insulating layer having electrical insulation;
And a step of providing a conductive layer on the opposite side of the substrate with the insulating layer interposed therebetween.

  According to the present invention, a wiring board having high insulation reliability between a via and a conductive substrate can be obtained.

1. Wiring Board FIG. 1 is a schematic cross-sectional view showing an embodiment of a wiring board of the present invention.

  The wiring board 1 of this embodiment includes a substrate 11 having at least one through hole 21, an insulating layer 14 covered in the through hole, and a wiring portion 15 provided on the surface of the insulating layer 14.

  The substrate 11 functions as a core that maintains and shapes the shape of the wiring substrate 1. The substrate 11 is provided with at least one hole (for example, the through hole 21 shown in FIG. 1) penetrating the main surface. The through hole is provided in order to provide a wiring portion 15 that can electrically connect the upper surface and the lower surface of the wiring board. The substrate 11 has a relatively small thermal expansion coefficient of about 10 ppm / ° C. or less in the range of 25 to 200 ° C. As such a substrate having a relatively low thermal expansion coefficient, for example, a sheet in which fibers having a thermal expansion coefficient of about 1.0 to 2.0 ppm / ° C. are woven in a range of 5 to 200 ° C. and the sheet. And a resin substrate that is arranged so as to contain the resin. As the fiber, for example, a fiber made of carbon or invar can be used. These fibers are conductive. As the resin, for example, an epoxy resin, a polyimide resin, or the like can be used. In order to reduce the thermal expansion coefficient, the resin may be mixed with an inorganic filler such as an alumina filler, an aluminum nitride filler, or a silica filler. Specifically, for example, a substrate 11 in which five prepregs (not shown) formed by combining a carbon fiber sheet having a thickness of 0.2 mm and a resin composition are stacked and pressure-bonded can be used. In this case, the thickness of the substrate 11 is approximately 1.0 mm. The number of through holes may be one or more. The shape of the through hole is not particularly limited. The number and shape of the through holes are determined according to the wiring design of the wiring board 1. The diameter of the through hole is 0.5 mm, for example. On the wall surface of the through hole 21, there are usually burrs 12 generated when the through hole 21 is formed. The burr 12 is likely to occur when the resin substrate is used as the substrate 11. The burrs 12 are, for example, exposed conductive fibers contained in the resin substrate.

  In the present embodiment, a substrate 11 in which five prepregs formed by combining a carbon fiber sheet resin composition are laminated and pressure-bonded is used. In the present invention, the substrate 11 is limited to this pressure-bonded material. It is not a thing. As the substrate 11, for example, a substrate made of a metal such as copper or iron or an alloy such as invar can be used. When the through hole 21 is formed in the substrate made of such an alloy, the burr 12 is generated in the through hole 21 as in the case of the resin substrate.

  The insulating layer 14 is provided on the front surface, back surface, side end surface, and wall surface of the through hole of the substrate 11 provided with the through hole 21. The insulating layer 14 has an insulating property capable of electrically insulating the substrate 11 and the wiring portion 15. On the wall surface of the through hole of the substrate 11, there is usually a burr 12 generated when the through hole 21 is formed. The insulating layer 14 is formed so as to cover the burr 12. The insulating layer 14 includes a through hole 22 along the extending direction of the through hole 21 of the substrate 11.

  At the interface between the substrate 11 and the insulating layer 14, a group represented by the following general formula (1) forms a covalent bond with an atom contained in the substrate 11.

  Ar represents a substituted or unsubstituted aromatic group, or a substituted or unsubstituted heterocyclic group.

  Ar is, for example, an aromatic group having 5 to 36 carbon atoms, or an aromatic heterocyclic group containing a hetero atom such as an oxygen atom, a nitrogen atom, or a sulfur atom. A specific example of Ar is represented by the following structural formula, for example.

However, in said structural formula, R < ¹ > -R < ⁸ > is group selected from a hydrogen atom, a C1-C6 alkyl group, a C1-C6 alkoxy group, and a hydroxyl group. R ^{1 to} R ⁸ may be the same as or different from each other. Linking group Z is a group selected O, S, from the SO _2.

  Among these, a 1,4-phenylene group is preferably used from the viewpoints of solubility, availability, and structural simplicity.

The linking group Y is a group formed by a reaction between an epoxy group and a functional group selected from a hydroxyl group, a carboxyl group, and an amino group. Linking group Y is ^{specifically, -NHR 2 -, - N (} R 2 -) R 3 -, - O-R 2 -, - COO-R 2 - , and the like. R ² and R ³ are groups selected from —CH ₂ —CH (OH) — and —CH (OH) —CH ₂ —, which may be the same or different. , —CH ₂ —CH (OH) —.

R ¹ is a group excluding the epoxy group involved in the formation of the linking group Y among the epoxy groups included in the epoxy resin and the epoxy-modified polyimide resin. Examples of suitable aromatic bifunctional epoxy resins include bifunctional epoxy resins such as bisphenol A type epoxy, bisphenol S type epoxy, and bisphenol F type epoxy. Are triglycidyl isocyanurate, VG3101L manufactured by Mitsui Chemicals, and examples of the aromatic tetrafunctional epoxy resin include Araldite MTO163 manufactured by Ciba Geigy. Examples of suitable alicyclic epoxy resins include bifunctional epoxy resins such as Araldite CY179 (Ciba Geigy) and EHPE-3150 (Daicel Chemical), trifunctional epoxy resins such as Eporide GT300 (Daicel Chemical), and Epolide GT400. A tetrafunctional epoxy resin such as (Daicel Chemical Company) can be used. Moreover, 37N made from Arlon is mentioned as an example of an epoxy-modified polyimide resin.

  The epoxy resin also includes a resin obtained by a reaction between an epoxy group included in the epoxy resin and a curing agent, and the epoxy-modified polyimide resin includes an epoxy group and a curing agent included in the epoxy-modified polyimide resin. The resin obtained by reacting with is also included. Any curing agent may be used as long as it is useful for curing the epoxy compound to be used, but it is preferable to select the curing agent so as not to impair the properties of the insulating layer. As such a curing agent, for example, a phenol resin, an amine compound, a cyanate ester resin, and an acid anhydride can be used. As the phenol resin, an aralkyl type phenol resin (for example, trade name “XLC-LL” manufactured by Mitsui Chemicals, Inc.) or a phenol novolak resin (for example, trade name “PSM-4300” manufactured by Gunei Chemical Co., Ltd.) should be used. Can do. Specific examples of amine compounds include diethylenetriamine, triethylenetetramine, diethylaminopropylamine, N-aminoethylpiperazine, mensendiamine, m-xylenediamine, metaphenylenediamine, diaminodiphenylmethane, diaminodiphenylsulfone, and diaminodicyclohexylmethane. Can be used. Specific examples of the cyanate ester resin include Prime Set (Lonza) PT-15, PT-30, PT-60S, CT-90 and BA-230S, and phenol novolac cyanate ester. Specific examples of acid anhydrides include trimellitic anhydride, pyromellitic anhydride, benzophenone tetracarboxylic anhydride, maleic anhydride, succinic anhydride, methylbutenyltetrahydrophthalic anhydride, tetrahydrophthalic anhydride, tetrahydromethyl. Examples thereof include phthalic anhydride, methyl nadic anhydride, hexahydrophthalic anhydride, and mixtures thereof. Depending on the properties required for the insulating layer, a mixture of a plurality of curing agents may be used. The epoxy resin and the epoxy-modified polyimide resin are thermosetting resins, and the product obtained by reaction takes a rigid three-dimensional network structure.

  Since the insulating layer 14 is chemically adsorbed to the wall surface of the through hole of the substrate 11 by the covalent bond between the group represented by the above formula (1) and the atoms contained in the substrate 11, the insulating layer 14 and the substrate 11 High adhesion. The resin substrate in which the substrate 11 includes carbon fibers forms a covalent bond with the group represented by the formula (1) through the carbon atoms included in the carbon fibers. When the board | substrate 11 is a resin substrate containing a metal fiber, group represented by Formula (1) forms a covalent bond with the metal element contained in a metal fiber. Examples of the metal that can be covalently bonded to the group represented by the formula (1) include copper, iron, nickel, and the like.

  The fact that the atoms constituting the fibers contained in the resin substrate and the group represented by the formula (1) are covalently bonded is, for example, that the vicinity of the boundary between the substrate 11 and the insulating layer 14 is obtained by cutting the wiring substrate. It can confirm by measuring a reflected infrared absorption spectrum about the exposed sample.

The wiring portion 15 is provided so as to be in contact with the through hole 22 provided in the insulating layer 14. The wiring unit 15 can electrically connect both surfaces of the substrate 11. In the wiring substrate shown in FIG. 1, the wiring layer 15 is layered. However, the form of the wiring layer 15 may be any form that can electrically connect both surfaces of the substrate 11. FIG. 2 is a schematic cross-sectional view showing another embodiment of the wiring board of the present invention. Hereinafter, the same components as those described above are denoted by the same reference numerals. Further, description overlapping with the above-described components is omitted. In the wiring board of the present invention, for example, as in the wiring board shown in FIG. 2, the wiring portion 15 may be provided so as to fill the inside of the through hole 22. The material constituting the wiring board 15 is not particularly limited as long as it has conductivity, and for example, copper can be used.
2. Wiring Board Manufacturing Method An embodiment of a wiring board manufacturing method of the present invention will be described with reference to FIGS.

3-5 is typical sectional drawing which shows one Embodiment of the manufacturing method of the wiring board of this invention. The method for manufacturing a wiring board according to the present embodiment includes a first step of preparing a conductive substrate having a first through hole, and the first through hole in an aqueous solution in which an aryldiazonium salt having a reactive substituent is dissolved. A second step of immersing the organic resin, a third step of providing an organic resin capable of reacting with the reactive substituent in the first through hole, a fourth step of curing the organic resin and forming an insulating layer, A fifth step of providing a second through hole in the insulating layer; and a sixth step of providing a conductive wiring in the second through hole. Hereinafter, the first to sixth steps will be described in order.
(1) First Step In the first step, as shown in FIG. 3A, a substrate 11 having a first through hole 21 and having conductivity is prepared. As a material constituting such a substrate, as described in the description of the wiring substrate, for example, a sheet in which fibers having a coefficient of thermal expansion of about 1.0 to 2.0 ppm / ° C. are knitted and the sheet is contained. And a resin substrate having a relatively low coefficient of thermal expansion.

  Hereinafter, a specific example of the first step will be described. First, by stacking, for example, five prepregs made by combining a carbon fiber sheet having a thickness of 0.2 mm, in which carbon fibers are knitted into a sheet, and an epoxy resin composition, these are bonded by, for example, vacuum pressing. Then, a flat conductive core substrate (resin substrate) is formed. The pressure bonding of the prepreg is not limited to the vacuum pressing method, and may be performed using a laminator such as a vacuum laminator, a laminated plate pressing machine, or the like. The thickness of the formed core substrate is approximately 1.0 mm.

Next, first through holes (through holes) 21 penetrating from the front surface to the back surface are formed in the formed conductive core substrate (see FIG. 3A). For example, a dry etching method using a UV-YAG laser, a carbon dioxide laser, an excimer laser, a mechanical drill method (cutting method), or the like can be used to form the through hole. The diameter of the 1st through-hole 21 shall be 0.5 mm, for example. At this time, a burr 12 made of carbon fiber is generated on the wall surface of the first through hole 21.

In addition, you may perform the degreasing | cleaning process which used the acidic or alkaline solution with respect to the board | substrate 11 in which the 1st through-hole 21 was formed as needed.
(2) Second Step In the second step, the substrate having the first through hole is immersed in an aqueous solution in which the aryldiazonium salt having a reactive substituent is dissolved. The aryldiazonium salt having a reactive substituent is represented by the following general formula (2).

Ar represents a substituted or unsubstituted aromatic group or a substituted or unsubstituted heterocyclic group as in the general formula (1). R ⁴ is a reactive substituent in the present embodiment. R ⁴ is a functional group showing reactivity with the organic resin in the third step. As will be described later, an organic resin having an epoxy group is preferably used as the organic resin from the viewpoint of ensuring insulation between the wiring portion 15 and the substrate 11 and excellent reactivity.

Examples of the functional group R ⁴ having reactivity with an organic resin having an epoxy group include a hydroxyl group, a carboxyl group, and an amino group. X ⁻ is an arbitrary anion. Specific examples of X ⁻ in the formula (2) are exemplified by halogen anions such as a fluorine anion, a chlorine anion, a bromine anion and an iodine anion; an acetate anion, a trifluoroacetate anion, a sulfate anion and a hydrogen sulfate anion. Methane sulfate anion, trifluoromethane sulfate anion, perchlorate anion, tetrafluoroborate anion, hexafluorophosphate anion, hexachloroantimonate anion, and the like. Among these, tetrafluoroborate anions are exemplified as one preferable from the viewpoint of reactivity and convenience.

  By the second step, the wall surface of the first through hole 21 is covered with the organic film 13. The organic film 13 is a film in which the aryldiazonium salt represented by the general formula (2) forms a bond with atoms constituting the substrate 11. For example, when the substrate 11 is a resin substrate formed by overlapping a prepreg in which a carbon fiber sheet and an epoxy resin composition are combined, the atoms constituting the carbon fibers contained in the resin substrate and the aryldiazonium salt are represented by the following formulae: A bond is formed on the wall surface of the through hole 21 by the reaction shown in (3). Since the bond between the atoms constituting the fibers contained in the conductive core substrate and the group from which the diazonium group is eliminated from the aryldiazonium cation is highly covalent, the adsorption between the wall surface of the first through-hole 21 and the organic film 13 is strong. It is considered that chemisorption is dominant over physical adsorption by hydrogen bonding, van der Waals force, and the like.

  The bond between the atoms constituting the fibers contained in the conductive core substrate and the group from which the diazonium group is eliminated from the aryldiazonium cation is covalent. For example, the substrate 11 after being immersed in an aryldiazonium aqueous solution This surface can be confirmed by measuring a reflection infrared absorption spectrum.

Specifically, for example, p-carbophenyl as an aryldiazonium salt
When using a Diazonium tetrafluoroborate, peaks derived from C = C stretching vibration phenylene contained in the Ar groups shown in the formula (3) appears at wave number of 1590 cm ^-1 and 1660 cm ^-1.

  In addition, when the board | substrate 11 consists of alloys, such as metals, such as copper and iron, and Invar, a bond is formed in the wall surface of the through-hole 21 by reaction of following formula (4). This bond is also strong in covalent bond, and it is considered that chemical adsorption is dominant in the adsorption between the wall surface of the first through hole 21 and the organic film 13.

  However, M is a copper atom, an iron atom, or a nickel atom.

  The chemical reactions represented by the formulas (3) and (4) proceed under acidic conditions and at room temperature. After immersing the substrate 11 in the aqueous solution in which the aryldiazonium salt is dissolved, it is preferable to perform water washing to remove the unreacted aryldiazonium aqueous solution from the substrate 11.

In addition, when the board | substrate which has the 1st through-hole 21 is immersed in the aqueous solution which the aryl diazonium salt which has a reactive substituent melt | dissolved, an organic film will also be normally formed in the surface of the board | substrate 11, a back surface, and a side end surface. Further, unlike the first through-hole 21, there are no burrs on the front surface, the back surface, and the side end surfaces of the substrate 11, so that the adhesion of the insulating layer 14 to be described later is ensured even if no organic film is formed on these surfaces. it can.
(3) Third Step Next, in the third step, in the first through hole 21 covered with the organic film 13, a resin composition 14 containing an organic resin capable of reacting with the reactive substituent of the organic film 13 is provided. Provide. The means for providing the resin composition in the first through hole 21 is not particularly limited. As means for providing the resin composition, for example, the following method can be suitably used. First, a liquid resin composition containing an organic resin capable of reacting with a reactive substituent is applied on an arbitrary sheet, and further dried to form a dry film of the resin composition. Thereafter, a dry film is laminated on the substrate 11 obtained in the second step, and the resin composition 14 is filled in the first through holes 21.

The resin composition contains, as a main ingredient, one or more kinds of compounds selected from monomers, oligomers or polymers having an epoxy group capable of reacting with the reactive substituent R ⁴ provided on the surface of the substrate 11. Contains a curing agent for initiating, accelerating and adjusting curing. The resin composition may further contain a curing accelerator that accelerates curing.

The main agent is an epoxy resin that has two or more epoxy groups in the molecule and can be formed into a film by curing, and the cured product has sufficient properties as an insulating layer in a circuit board, such as peel (peel) strength, It is preferable to select one that can provide tensile elongation, resistance in the plating process, and the like.

  A preferable epoxy resin as the main agent is an alicyclic or aromatic epoxy resin. This epoxy resin has a functionality of 2 or more, more preferably 2 to 4 functionality. Examples of suitable aromatic bifunctional epoxy resins include bifunctional epoxy resins such as bisphenol A type epoxy, bisphenol S type epoxy, bisphenol F type epoxy, and the like. Examples of glycidyl isocyanurate, VG3101L manufactured by Mitsui Chemicals, and aromatic tetrafunctional epoxy resin include Araldite MTO163 manufactured by Ciba Geigy. Examples of suitable alicyclic epoxy resins include bifunctional epoxy resins such as Araldite CY179 (Ciba Geigy) and EHPE-3150 (Daicel Chemical), trifunctional epoxy resins such as Eporide GT300 (Daicel Chemical), and Epolide GT400. A tetrafunctional epoxy resin such as (Daicel Chemical Company) can be used. In particular, by including a low molecular weight epoxy resin generated from these trifunctional or tetrafunctional epoxy resins, the intermolecular network structure in the insulating film formed from the resin composition is strengthened, and the insulation and mechanical properties are improved. It is possible to provide an excellent insulating layer.

  As described above, the epoxy resin can be used by mixing two or more kinds so as to provide sufficient properties as an insulating layer, and a mixture of an alicyclic epoxy resin and an aromatic epoxy resin is used. Is preferred. In this case, the epoxy resin mixture contains at least one epoxy resin having a functionality of 3 or more, thereby forming an insulating layer having high peel strength, high tensile elongation, and high glass transition temperature (Tg). This is particularly advantageous. Preferably, the epoxy resin composition of the present invention includes at least one trifunctional or higher functional epoxy resin in addition to at least a bifunctional alicyclic epoxy and an aromatic epoxy resin.

  In addition to the above epoxy resin, for example, an epoxy-modified polyimide resin can be used as the main agent. Epoxy-modified polyimide resin is a polyamic acid intermediate obtained by polymerizing diamine and tetracarboxylic dianhydride (at least one of them, usually at least diamine has a hydroxyl group) in an aprotic polar solvent. Is a solvent-soluble polymer obtained by epoxidizing a polyimide having a hydroxyl group in the side chain, which is synthesized by polyimidating this intermediate.

  As the epoxy-modified polyimide resin, a commercially available product name “37N” manufactured by Arlon may be used.

Any curing agent may be used as long as it is useful for curing the epoxy compound to be used, but it is preferable to select the curing agent so as not to impair the properties of the insulating layer. As such a curing agent, for example, a phenol resin, an amine compound, a cyanate ester resin, and an acid anhydride can be used. As the phenol resin, an aralkyl type phenol resin (for example, trade name “XLC-LL” manufactured by Mitsui Chemicals, Inc.) or a phenol novolak resin (for example, trade name “PSM-4300” manufactured by Gunei Chemical Co., Ltd.) should be used. Can do. Specific examples of amine compounds include diethylenetriamine, triethylenetetramine, diethylaminopropylamine, N-aminoethylpiperazine, mensendiamine, m-xylenediamine, metaphenylenediamine, diaminodiphenylmethane, diaminodiphenylsulfone, and diaminodicyclohexylmethane. Can be used. Specific examples of the cyanate ester resin include Prime Set (Lonza) PT-15, PT-30, PT-60S, CT-90 and BA-230S, and phenol novolac cyanate ester. Specific examples of acid anhydrides include trimellitic anhydride, pyromellitic anhydride, benzophenone tetracarboxylic anhydride, maleic anhydride, succinic anhydride, methylbutenyltetrahydrophthalic anhydride, tetrahydrophthalic anhydride, methyltetrahydro Examples thereof include phthalic anhydride, methyl nadic anhydride, hexahydrophthalic anhydride, and mixtures thereof. Depending on the properties required for the insulating layer, a mixture of a plurality of curing agents may be used.

  The amount of the curing agent used may be appropriately determined in consideration of the characteristics of the insulating layer to be formed, etc., but usually the active hydrogen equivalent of the curing agent is 0.8 to 1 with respect to 1 equivalent of the epoxy group in the composition. It is preferable to blend in an amount such that .1.

  As a hardening accelerator, what is necessary is just to use a suitable thing according to the epoxy compound to be used and the kind of the hardening | curing agent. Examples of such curing accelerators include imidazole compounds, triphenylphosphine, tertiary amines, and acetylacetonate complexes of Cu (II), Co (II), Zn (II), and Mn (II). be able to.

  What is necessary is just to determine the usage-amount of a hardening accelerator suitably according to the epoxy resin to be used and the kind of the hardening | curing agent. When using an imidazole compound, triphenylphosphine, and a tertiary amine as a curing accelerator, 1 to 10 parts by weight is usually used with respect to 100 parts by weight of the epoxy resin in the composition. Further, when an acetylacetonate complex of Cu (II), Co (II), Zn (II), and Mn (II) is used as a curing accelerator, it is usually per 1 million parts by weight of the total solid content in the composition. It is used so that the active metal ion content is 100 to 500 parts (100 to 500 ppm).

  You may add a various additive to a resin composition as needed. Examples of such additives include fillers. In particular, the addition of silica powder as a filler is advantageous from the viewpoint of reducing the thermal expansion coefficient of the wiring board. The addition amount of the silica powder should be determined so as not to impair other properties of the insulating layer to be formed. Specifically, 2.5 to 10 parts by weight with respect to 100 parts by weight of the total solid content of the resin composition. It is good to be about. Examples of the additive include a leveling agent, a rust preventive pigment, a repellency inhibitor, an anti-sagging agent, an antifoaming agent, an ultraviolet absorber, a light stabilizer and the like in addition to a filler.

  The resin composition is generally applied in the form of a varnish onto a processing substrate (a core substrate or an insulating layer and a wiring layer formed thereon). In order to obtain a varnish-like composition, the resin composition can contain an appropriate solvent in addition to the above components. Examples of the solvent include acetates such as propylene glycol monoether acetate, and organic solvents such as cyclohexane, dioxane, methyl ethyl ketone (MEK), xylene, and N-methylpyrrolidone.

  In the third step, the resin composition may be usually formed not only on the first through hole 21 but also on the front surface 11a, the back surface 11b, and the side end surface (not shown) of the substrate 11.

  The surface of the first through hole 21 in which the organic layer 13 is provided has higher wettability with respect to the resin composition than the surface of the first through hole 21 in which the organic layer 13 is not provided. For this reason, the resin composition is filled so as to follow the irregular shape of the burr 12 generated when the first through hole 21 is formed. Moreover, the organic film 13 having a reactive substituent and the main agent contained in the resin composition react by heating in the fourth step and are integrated to form the insulating layer 14. As described above, the adsorption of the insulating layer 14 to the first through-hole 21 is dominated by chemical adsorption.

When laminating, it is preferable to laminate a dry film on both surfaces of the substrate 11 from the viewpoint of improving the filling rate of the organic resin into the first through holes 21. Examples of the apparatus used for laminating include an existing vacuum press, a laminated plate press, a laminator, and a vacuum laminator. Lamination may be performed while heating in order to promote the reaction of the resin composition and to improve the filling rate of the organic resin in the first through holes 21. The heating temperature can be appropriately selected according to the compound contained in the resin composition 14.
(4) Fourth Step In the fourth step, the curing reaction is accelerated by heating the resin composition 14 provided on the wall surface of the first through-hole 21 as shown in FIG. Let The epoxy resin and the epoxy-modified polyimide resin contained in the resin composition 14 are thermosetting resins, and the product obtained by reaction takes a rigid three-dimensional network structure.

  Moreover, the reactive substituent which the organic layer 13 has, and the epoxy group contained in the resin composition 14 react by this heating, as shown by following formula (5). At this time, since a reactive functional group contained in the organic layer 13 reacts with an organic resin contained in the resin composition 14, a anchoring (anchor) effect is exhibited. Adhesion with the insulating layer 14 is improved. The heating temperature can be appropriately selected according to the compound contained in the resin composition.

Ar represents a substituted or unsubstituted aromatic group or a substituted or unsubstituted heterocyclic group as in the general formula (1). R ⁴ is a reactive substituent in the present embodiment, similar to that of formula (2). R ⁴ is a functional group that is reactive with the organic resin in the third step, and examples thereof include a hydroxyl group, a carboxyl group, and an amino group. The linking group Y is a linking group formed by a reaction between an epoxy group and a functional group selected from a hydroxyl group, a carboxyl group, and an amino group. Linking group Y is ^{specifically, -NHR 2 -, - N (} R 2 -) R 3 -, - O-R 2 -, - COO-R 2 - , and the like. R ² and R ³ are groups selected from —CH ₂ —CH (OH) — and —CH (OH) —CH ₂ —, which may be the same or different. , —CH ₂ —CH (OH) —. R ¹ is a portion excluding the epoxy group involved in the formation of the linking group Y among the epoxy groups included in the epoxy resin and the epoxy-modified polyimide resin, similarly to that of the general formula (1).

In addition, it can replace with a 4th process by laminating in a 3rd process, heating.
(5) Fifth Step In the fifth step, as shown in FIG. 4A, the second through hole 22 is formed in the cured resin composition, that is, the insulating layer 14. The formation of the second through hole 22 is similar to the formation of the first through hole 21, for example, a dry etching method using a UV-YAG laser, a carbon dioxide gas laser, an excimer laser, and the like, and a mechanical drill method (cutting method). Etc. can be used. The diameter of the second through hole 22 is, for example, 0.2 mm. Furthermore, you may perform the desmear process which removes a resin residue with respect to the 2nd through-hole 22 as needed. The desmear treatment may be performed with a chemical solution such as permanganic acid or may be performed using plasma.

In the third step, the fifth step may not be performed when the resin composition 14 is provided in the first through hole 21 so as to have a shape corresponding to the second through hole.
(6) Sixth Step In the sixth step, as shown in FIG. 4B, the second through hole 22 is covered with a conductive material, and the wiring portion 15 is provided. For example, copper is preferably used as the conductive material. The method for coating the conductive material is not particularly limited, and for example, the conductive material can be coated by an electroless plating method and a subsequent electrolytic plating method. The film thickness of the copper film coated by the electroless plating method is, for example, 0.3 μm, and the film thickness of the copper film coated by the plating method is, for example, 30 μm. The coated conductive material makes it possible to electrically connect both sides of the substrate 11.

  The wiring board is usually provided with a wiring portion made of a conductive material not only on the second through hole 22 but also on the front surface 11a, the back surface 11b, and the side end surface (not shown) of the substrate. The form of the wiring portion provided on these surfaces is determined according to the wiring design and is not particularly limited. The wiring portions provided on these surfaces can be provided as follows, for example.

  First, in the sixth step, a conductive material is also coated on the front surface 11a, the back surface 11b, and the side end surfaces (not shown) of the substrate together with the second through holes by the electroless plating method. Next, by laminating the substrate 11 with a dry film resist, a resist layer having a thickness of 50 μm, for example, is formed on the copper film formed on the front and back surfaces of the substrate 11 (not shown). Next, an opening 30 exposing the wiring formation scheduled region is formed in the resist layer 31 by photolithography (see FIG. 4C).

  Next, with the copper film 15 formed by electroless plating as a seed, copper formed on the copper film 15 exposed at the opening 30 of the resist layer 31 and the wall surface of the second through hole 22 by electrolytic plating. For example, a copper film having a thickness of 30 μm is deposited on the film 15 (see FIG. 4D).

  After increasing the film thickness of the copper film 15 by electrolytic plating, the resist layer 31 is removed (see FIG. 5A). Next, the copper film 15 provided in a portion other than the wiring formation scheduled region is removed by panel etching. As the etching solution, for example, a mixed solution of hydrogen peroxide and sulfuric acid is used. In this way, wirings 32a and 32b made of the copper film 15 are formed on the insulating layer 14 formed on the front and back surfaces of the substrate. Further, a wiring made of a copper film is formed on the insulating layer formed on the side end surface of the substrate 11 (not shown). Moreover, the wiring 32c which consists of the copper film 15 is formed in the wall surface of the 2nd through-hole 22 (refer FIG.5 (b)).

  Thus, the wiring board according to the present embodiment is formed.

  In the case of forming a multilayer wiring board, the process of forming an insulating layer and the process of forming a wiring similar to the above are repeated thereafter. For example, five layers of multilayer wiring can be formed on each of the front and back surfaces of the substrate 11. Since the manufacture of a multilayer wiring board by such a build-up technique is well known to those skilled in the art, description thereof is omitted. An overcoat layer may be formed on the top and bottom layers of the substrate 11 on which the multilayer wiring is formed by using, for example, a screen printing technique and a photolithography technique together.

  Thus, according to this embodiment, the organic layer 13 is formed so that the through-hole 21 of the substrate 11 covers the burr 12. The atoms contained in the substrate 11 and the atoms contained in the organic layer 13 form a covalent bond. Moreover, the organic layer 13 improves the wettability with respect to the resin composition of the through-hole 21. For this reason, the resin composition 14 is provided along the concavo-convex shape of the burr 12 generated when the first through hole 21 is formed. The resin composition 14 provided in the through-hole 21 reacts with the organic layer 13 and is cured by heating. At this time, since a reactive functional group contained in the organic layer 13 reacts with an organic resin contained in the resin composition 14, a anchoring (anchor) effect is exhibited. Adhesion with the insulating layer 14 is improved. Therefore, voids are unlikely to occur in the insulating layer 14, and cracks are unlikely to occur due to temperature changes during use of the wiring board. Since the plating solution for forming the wiring hardly penetrates into the insulating layer where no voids or cracks are generated, the wiring provided in the through hole and the conductive substrate are not easily short-circuited. Therefore, according to the present embodiment, a highly reliable wiring board can be provided.

<Example 1>
The wiring board of Example 1 was created by the following method.

  First, five sheets of a prepreg obtained by combining a carbon fiber sheet having a thickness of 0.2 mm and an epoxy resin composition are stacked and stacked by a vacuum press to form a conductive substrate having a thickness of 1.0 mm. Created. The carbon fibers are woven in the X and Y directions (two directions parallel to the substrate and perpendicular to each other). As the epoxy resin composition, an epoxy resin composition containing 10% by weight of an alumina filler and 10% by weight of a silica filler was used. An alumina filler having an average particle size of 7 μm or less and a thermal expansion coefficient of 7 ppm / ° C. was used. A silica filler having an average particle size of 3 μm or less and a thermal expansion coefficient of 3 ppm / ° C. was used. The average thermal expansion coefficient in the X and Y directions of this core material was 2 ppm / ° C., and the average thermal expansion coefficient in the Z direction was 80 ppm / ° C. The temperature range of the coefficient of thermal expansion is in the range of 25 to 200 ° C.

An opening was formed in the main surface of the substrate by the following method. First, about 1000 through-holes with a diameter of 0.5 mm were formed on the main surface of the substrate with a drill. The substrate was subjected to predetermined degreasing / cleaning treatment. Thereafter, the substrate was immersed in an aqueous solution (0.1N) of p-carbophenyl diazonium tetrafluoroborate (0.1 mol) (0.1 N, H ₂ SO ₄ ) for 30 minutes and then washed with water. Thereafter, an epoxy resin sheet was laminated on both surfaces of the substrate by a vacuum press, and the through hole was filled with the epoxy resin. The vacuum press was performed at 200 ° C. for 30 minutes.

  The epoxy resin sheet was prepared by the following procedure. First, 75 parts by weight of a tetrabromobisphenol A type epoxy resin (Dainippon Ink Co., Ltd., trade name “Epicron 153”), cyclohexane alicyclic epoxy resin (Ciba Geigy Co., Ltd., trade name “Araldite CY179”) 25 parts by weight, phenol novolac resin (manufactured by Gunei Chemical Co., Ltd., trade name “PSM-4300”) 40 parts by weight, 2-methyl-4-ethyl-imidazole (manufactured by Shikoku Chemicals) 1.0 part by weight, silica powder ( 10.0 parts by weight manufactured by Nippon Aerosil Co., Ltd. (trade name “Aerosil 200”, particle size: 12 nm) were dissolved in 18 parts by weight of propylene glycol monoether and 29 parts by weight of cyclohexane to prepare a coating solution. Next, this coating solution was applied onto a PET film having a thickness of 100 μm using a doctor blade having a gap of 100 μm and dried to obtain an epoxy resin sheet. The thickness of the epoxy resin on the epoxy resin sheet was 0.05 mm.

Next, a through hole having a diameter of 0.2 mm passing through the center of the through hole formed in the substrate was formed in the epoxy resin filled in the through hole using a UV-YAG laser. Next, an electroless copper plating film (a so-called seed layer) was formed on the surface of the substrate and the epoxy resin provided in the through hole of the substrate. Next, a dry film resist having a shape corresponding to the wiring pattern was provided on the surface of the electroless copper plating film. Next, copper was coated on the surface of the seed layer by electrolytic copper plating. At this time, copper was also coated on the through hole having a diameter of 0.2 mm. Next, the dry film resist was peeled off. Subsequently, the electroless copper plating film was subjected to panel etching to obtain a wiring board. As the etching solution, a mixed solution of hydrogen peroxide and sulfuric acid was used.
(Evaluation)
1. Thermal cycle test About the obtained wiring board of Example 1, the resistance value of the copper wiring provided in the through-hole was measured. This resistance value was measured by a 4-terminal method using an Advantest digital multimeter R-6551.

  A thermal cycle test was then performed. The wiring board was left at a temperature of −65 ° C. for 30 minutes, and then left at a temperature of 125 ° C. for 30 minutes. The temperature and time conditions were set to 1 cycle, and a thermal cycle test was repeated for 1000 cycles.

  Subsequently, the resistance value of the copper wiring provided in the through hole was again measured for the wiring board subjected to the thermal cycle test.

The change rate of the resistance value before and after the thermal cycle test of the wiring board was 5% or less, respectively.
2. Appearance evaluation In order to confirm the presence or absence of cracks or voids between the wall surface of the through hole of the conductive substrate and the epoxy resin, the cross section parallel to the substrate of the wiring substrate was observed with a cross-sectional SEM. I was not able to admit. Moreover, the penetration of the copper plating solution between the wall surface of the through hole of the conductive substrate and the epoxy resin was not confirmed.
<Example 2>
In the method for producing the wiring board of Example 1, the epoxy resin composition contains 10% by weight of alumina filler and 10% by weight of silica filler, instead of 5% by weight of the total composition. It contains an aluminum nitride filler and 25% by weight silica filler. The aluminum nitride filler has an average particle size of 8 μm or less and a thermal expansion coefficient of 5 ppm / ° C., and an average thermal expansion coefficient in the X and Y directions of the conductive substrate. The temperature ranges of the average thermal expansion coefficient in the Z direction and the average thermal expansion coefficient were 2 ppm / ° C, 80 ppm / ° C, and 25-200 ° C, respectively, but were 3 ppm / ° C, 70 ppm / ° C, and 25-150 ° C, respectively. Dot, substrate is p-carbophenyl diazonium tetrafluoroborate (0.1 mol) aqueous solution (0.1 N, H ₂ SO ₄₎ ) For 30 minutes, the substrate was immersed in an aqueous solution of p-aminophenyl diazonium tetrafluoroborate (0.1 mol) (0.1N, H ₂ SO ₄ ) for 30 minutes, and an epoxy resin sheet was placed on both sides of the substrate. Instead of laminating by vacuum press and filling the through hole with epoxy resin, cyanate ester-epoxy resin sheet is laminated on both sides of the substrate by vacuum press, except that the through hole is filled with epoxy resin The wiring board of Example 2 was created by the same method as that for creating the wiring board of Example 1.

The cyanate ester-epoxy resin sheet was prepared by the following procedure. First, 65 parts by weight of tetrabromobisphenol A type epoxy resin (Dainippon Ink Co., Ltd., trade name “Epiclon 153”), cyclohexane skeleton alicyclic epoxy resin (Ciba Geigy Co., Ltd., trade name “Araldite CY179”) 25 parts by weight, 10 parts by weight of bisphenol A type polyol epoxy (manufactured by Shin Nippon Chemical Co., Ltd., trade name “BEO-60E”), 87 parts by weight of cyanate ester (manufactured by Lonza Corporation, trade name “PT-30”), silica 6 parts by weight of powder (manufactured by Nippon Aerosil Co., Ltd., trade name “AEROSIL200”, particle size: 12 nm), 0.25 parts by weight of polyacrylate, and 0.01 parts by weight of Co (II) acetylacetonate complex were mixed with propylene glycol monoether. Dissolve in 20 parts by weight of cyclohexane and 29 parts by weight of cyclohexane. It was. Subsequently, this coating liquid was applied onto a PET film having a thickness of 100 μm using a doctor blade having a gap of 100 μm and dried to obtain a cyanate ester-epoxy resin sheet.
(Evaluation)
1. Thermal cycle test With respect to the obtained wiring board of Example 2, the rate of change in resistance value before and after the thermal cycle test was determined in the same manner as in the evaluation of Example 1. The change rate of the resistance value of the wiring board of Example 1 was 5% or less, respectively.
2. Appearance evaluation In order to confirm the presence or absence of cracks or voids between the wall surface of the through hole of the conductive substrate and the epoxy resin, five cross-sections of the wiring substrate parallel to the substrate were observed with a cross-sectional SEM. Was not recognized. Moreover, the penetration of the copper plating solution between the wall surface of the through hole of the conductive substrate and the epoxy resin was not confirmed.
<Example 3>
In the method for producing the wiring board of Example 1, the epoxy resin composition contains 10% by weight of alumina filler and 10% by weight of silica filler, instead of 5% by weight of the total composition. It contains aluminum nitride filler and 25% by weight silica filler. Aluminum nitride filler has an average particle size of 8 μm or less and a coefficient of thermal expansion of 5 ppm / ° C., average thermal expansion in the X and Y directions of the conductive substrate Rate, Z-direction average thermal expansion coefficient, and average thermal expansion coefficient temperature ranges of 2 ppm / ° C, 80 ppm / ° C, and 25-200 ° C, respectively, 3 ppm / ° C, 70 ppm / ° C, and 25-150 ° C, respectively. And the substrate was washed with an aqueous solution (0.1 N, H) of p-carbophenyl diazonium tetrafluoroborate (0.1 mol). Instead of immersing 30 minutes ₂ SO _4), the substrate 4-hydroxyphenyldiazonium tetrafluoroborate
A wiring board of Example 3 was created in the same manner as the wiring board of Example 1 except that it was immersed in a salt (0.1 mol) aqueous solution (0.1N, H ₂ SO ₄ ) for 30 minutes. .
(Evaluation)
1. Thermal cycle test With respect to the obtained wiring board of Example 3, the rate of change in resistance value before and after the thermal cycle test was determined in the same manner as in the evaluation of Example 1. The change rate of the resistance value of the wiring board of Example 1 was 5% or less, respectively.
2. Appearance evaluation In order to confirm the presence or absence of cracks or voids between the wall surface of the through hole of the conductive substrate and the epoxy resin, five cross-sections of the wiring substrate parallel to the substrate were observed with a cross-sectional SEM. Was not recognized. Moreover, the penetration of the copper plating solution between the wall surface of the through hole of the conductive substrate and the epoxy resin was not confirmed.
<Comparative Example 1>
In the method for producing the wiring substrate of Example 1, the substrate was immersed in an aqueous solution of p-carbophenyl diazonium tetrafluorate (0.1 mol) (0.1 N, H ₂ SO ₄ ) for 30 minutes, and the step of further washing with water was not performed. Except for the point, the wiring board of the comparative example 1 was created by the same method as that of the wiring board of the example 1.
(Evaluation)
1. Thermal cycle test With respect to the obtained wiring board of Comparative Example 1, the rate of change in resistance value before and after the thermal cycle test was determined in the same manner as in the evaluation of Example 1. The change rate of the resistance value of the wiring board of Comparative Example 1 exceeded 5%.
2. Appearance evaluation In order to confirm the presence or absence of cracks or voids between the wall surface of the through hole of the conductive substrate and the epoxy resin, five cross sections parallel to the substrate of the wiring substrate were observed by a cross-sectional SEM. Admitted. Further, it was confirmed that the copper plating solution penetrated between the wall surface of the through hole of the conductive substrate and the epoxy resin.
<Comparative example 2>
In the method for producing a wiring board of Example 1, except that the substrate was made into an aqueous solution of p-aminophenyl diazonium tetrafluoroborate (0.1 mol) (0.1 N, H ₂ SO ₄ ), and further washed with water, The wiring board of Comparative Example 2 was created in the same manner as the wiring board creation method of Example 2.
(Evaluation)
1. Thermal cycle test With respect to the obtained wiring board of Comparative Example 2, the rate of change in resistance value before and after the thermal cycle test was determined in the same manner as in the evaluation of Example 1. The change rate of the resistance value of the wiring board of Comparative Example 2 exceeded 5%.
2. Appearance evaluation In order to confirm the presence or absence of cracks or voids between the wall surface of the through hole of the conductive substrate and the epoxy resin, five cross sections parallel to the substrate of the wiring substrate were observed by a cross-sectional SEM. Admitted. Further, it was confirmed that the copper plating solution penetrated between the wall surface of the through hole of the conductive substrate and the epoxy resin.

Here, the detailed features of the present invention will be described again.
(Appendix 1)
Preparing a conductive substrate having a through hole;
Immersing the substrate in a solution in which an aryldiazonium salt having a reactive substituent is dissolved;
Providing a resin composition containing an organic resin capable of reacting with the reactive substituent on the wall surface of the through hole;
Curing the resin composition to form an insulating layer having electrical insulation;
And a step of providing a conductive layer on the opposite side of the substrate with the insulating layer interposed therebetween.
(Appendix 2)
The method for manufacturing a wiring board according to appendix 1, wherein the substrate includes a material capable of reacting with the aryldiazonium salt.
(Appendix 3)
The method of manufacturing a wiring board according to appendix 1, wherein the substrate contains carbon.
(Appendix 4)
4. The method for manufacturing a wiring board according to appendix 3, wherein the carbon has a fibrous shape.
(Appendix 5)
The method for manufacturing a wiring board according to appendix 1, wherein the board is made of metal.
(Appendix 6)
The method for producing a wiring board according to appendix 1, wherein the reactive substituent is at least one functional group selected from a hydroxyl group, a carboxyl group, and an amino group.
(Appendix 7)
The method for manufacturing a wiring board according to appendix 1, wherein the organic resin comprises at least one resin selected from an epoxy resin and an epoxy-modified polyimide resin. (Appendix 8)
The method for manufacturing a wiring board according to appendix 1, wherein the organic resin is cured by heating the resin composition.
(Appendix 9)
A conductive substrate with a through hole;
An insulating layer that is in contact with the wall surface of the through hole, forms a covalent bond with the wall surface, and has electrical insulation;
And a conductive layer provided on the opposite side of the substrate with the insulating layer interposed therebetween.

It is a typical sectional view showing one embodiment of a wiring board of the present invention. It is typical sectional drawing which shows another embodiment of the wiring board of this invention. It is typical sectional drawing which shows one Embodiment of the manufacturing method of the wiring board of this invention. It is typical sectional drawing which shows one Embodiment of the manufacturing method of the wiring board of this invention. It is typical sectional drawing which shows one Embodiment of the manufacturing method of the wiring board of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Wiring board 11 Board | substrate 12 Burr 13 Organic layer 14 Insulating layer (resin composition)
DESCRIPTION OF SYMBOLS 15 Wiring layer 21 1st through-hole 22 2nd through-hole 30 Opening part 31 Resist layer 32a-32c Wiring

Claims (6)

Preparing a conductive substrate having a through hole;
Immersing the substrate in a solution in which an aryldiazonium salt having a reactive substituent is dissolved;
Providing a resin composition containing an organic resin capable of reacting with the reactive substituent on the wall surface of the through hole;
Curing the resin composition to form an insulating layer having electrical insulation;
And a step of providing a conductive layer on the opposite side of the substrate with the insulating layer interposed therebetween.   The method for manufacturing a wiring board according to claim 1, wherein the substrate contains carbon.   The method for manufacturing a wiring board according to claim 2, wherein the carbon has a fibrous shape.   The method for manufacturing a wiring board according to claim 1, wherein the reactive substituent is at least one functional group selected from a hydroxyl group, a carboxyl group, and an amino group.   2. The method of manufacturing a wiring board according to claim 1, wherein the organic resin comprises at least one resin selected from an epoxy resin and an epoxy-modified polyimide resin. A conductive substrate with a through hole;
An insulating layer that is in contact with the wall surface of the through hole, forms a covalent bond with the wall surface, and has electrical insulation;
And a conductive layer provided on the opposite side of the substrate with the insulating layer interposed therebetween.