JPH11109650A - Production of multilayer printed circuit board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a multilayer printed circuit board of a build-up system which forms via holes of high quality having no gouge or separation and is excellent in interlayer connection reliability. SOLUTION: In this manufacturing method of the multilayer printed circuit board, a photosensitive insulating resin layer is provided on an inner conductor formed in an insulating substrate and is exposed and developed via a phototool to form the via holes. Thereafter, the photosensitive insulating resin layer surface is subjected to circuit machining including plating to form a conductor wiring. At the time of developing, an aq. alkaline developer containing an organic solvent is used as a developer and an aq. soln. containing the organic solvent is used as a rinsing soln. after developing to manufacture the multilayer printed circuit board. As the developer, an aq. soln. containing diethylene glycol monobutyl ether and sodium borate is preferably used. Further as the rinsing soln., an aq. soln. containing diethylene glycol monobutyl ether is preferably used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a multilayer printed wiring board, and more particularly to a method for developing a photosensitive insulating resin layer and a rinsing liquid used in the method.

[0002]

2. Description of the Related Art In recent years, the miniaturization, weight reduction, and multifunctionality of electronic equipment have been further advanced, and with this, the integration of LSIs and chip components has been advanced, and the form has also been increased to multi-pin and miniaturized. And it is changing rapidly. For this reason, the multilayer wiring board has been required to further increase the wiring pattern density in order to increase the mounting density of electronic components. Conventional multilayer wiring boards are, for example, those that are laminated and integrated with a copper foil via a prepreg on an insulating substrate on which an inner layer circuit is formed, then drilled, connected between layers by through-hole plating and made conductive. Had been used. However, in the above-described multilayer wiring board, when the number of layers increases, the number of through holes for interlayer connection also increases, so that the area for forming the conductor wiring is limited, and the correspondence to high-density wiring is reduced. It was difficult. In order to solve these problems, the development of build-up multilayer wiring boards in which conductive circuits and insulating resin materials are alternately laminated, and conduction is carried out using via holes only in areas where interlayer connection is required, has been actively conducted. Came to be. In the build-up method multilayer wiring board, the dead space due to through holes is reduced, and via holes other than drills can be used to reduce the via holes themselves, resulting in a larger area that can be used for conductor wiring And the density can be increased. As a method of manufacturing such a build-up multilayer wiring board, the present inventors have proposed a method using a photosensitive insulating resin as disclosed in JP-A-6-148877. In this method, a via hole for interlayer connection is formed by a photo process, so that a minute via hole can be easily formed, which greatly contributes to an improvement in wiring density of a multilayer wiring board.

[0003]

In forming via holes for interlayer connection, the quality of via holes is very important in terms of ensuring connection reliability. In other words, if the via hole is scuffed (undercut, see FIG. 2A) or if the inner layer conductor and the bottom of the via hole are peeled off (see FIG. 2B), the scuffed or peeled portion is removed. Since copper plating does not sufficiently precipitate in the back, plating is not continuous at the bottom edge of the via hole, and a groove is formed. Such a via hole causes an initial conduction failure between layers and a connection failure in a thermal cycle. On the other hand, according to the method proposed by the present inventors, the connection reliability was not always sufficient because of the via hole shape. For this reason, there is a limit in characteristics in application to applications that require higher reliability than module substrates and the like, such as package applications. An object of the present invention is to provide a method of manufacturing a build-up multilayer wiring board which solves such problems, forms a high-quality via hole without scouring and peeling, and has excellent connection reliability between layers. .

[0004]

According to the present invention, a photosensitive insulating resin layer is provided on an inner conductor formed on an insulating substrate, exposed and developed through a photo tool, and a via hole is formed.
In the method for producing a multilayer wiring board in which conductor wiring is formed by performing circuit processing including plating on the surface of the photosensitive insulating resin layer, in the development, an aqueous alkaline developer containing an organic solvent is used as a developing solution. A method for producing a multilayer printed wiring board using an aqueous solution containing an organic solvent as a rinsing liquid. The aqueous alkaline developer containing an organic solvent is an aqueous solution containing diethylene glycol monobutyl ether and sodium borate, and the aqueous solution containing an organic solvent used as a rinse after development is an aqueous solution containing diethylene glycol monobutyl ether. This is a preferred method of manufacturing a multilayer printed wiring board. Further, the present invention is a method for producing a multilayer printed wiring board, wherein the concentration of diethylene glycol monobutyl ether contained in the rinsing liquid is preferably 0.1 to 90% by volume.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION In order to solve the above problems, the present inventors have conducted intensive studies on the formation of via holes. As a result, a rinsing (cleaning) step performed after contacting with a developing solution during development has been described. By using an aqueous solution containing diethylene glycol monobutyl ether instead of water, which is generally used as a rinsing liquid in the development of photosensitive materials, it was conceived that scouring and peeling of via holes could be suppressed, and the connection reliability between layers was excellent. A method for manufacturing a multilayer printed wiring board has been completed. In other words, it was found that scouring and peeling of via holes did not occur (1) during contact with the developing solution, and (2) occurrence occurred when the rinsing solution was water in the rinsing step after development. ,
As a result, an aqueous solution containing an organic solvent as a rinse liquid,
In particular, by using an aqueous solution containing diethylene glycol monobutyl ether, the coverage of plating is sufficient, forming high-quality via holes without scouring and peeling, and manufacturing multilayer printed wiring boards with high connection reliability in interlayer connection We were able to.

Hereinafter, the features of the present invention will be described in accordance with the process sequence shown in FIG. First, an insulating substrate on which a first circuit is formed is prepared (FIG. 1- (a)). The insulating substrate is not particularly limited, and may be a glass cloth-epoxy resin, paper-
Insulating substrates such as phenolic resin, paper-epoxy resin, glass cloth / glass paper-epoxy resin, etc. used for ordinary wiring boards can be used. Further, as a method of forming the first circuit of the present invention, a subtractive method in which an unnecessary portion of the copper foil is removed by etching using a copper-clad laminate in which a copper foil and the insulating substrate are bonded, An ordinary method of manufacturing a wiring board, such as an additive method of forming a circuit by electroless plating in a necessary place, can be used. Next, a photosensitive insulating resin layer is formed on the circuit surface on which the first circuit has been formed (FIG. 1- (b)). As the resin composition, a photosensitive resin or a resin combining photosensitivity and thermosetting can be used, and a composition containing a copolymer or a monomer having a functional group that can be cross-linked by light or Any composition can be used as long as it is a composition in which a heat-crosslinkable functional group and a thermal initiator are mixed in addition to light. The first group that can be used as other resin components is an alicyclic epoxy resin such as an epoxy resin, a brominated epoxy resin, a rubber-modified epoxy resin, a rubber-dispersed epoxy resin, or a bisphenol A-based epoxy resin and these epoxy resins. And acid-modified products thereof. In particular, when photo-curing is performed by irradiating light, modified products of these epoxy resins and unsaturated acids are preferable. Examples of the unsaturated acid include maleic anhydride, tetrahydrophthalic anhydride, itaconic anhydride, acrylic acid, methacrylic acid and the like. These can be obtained by reacting the unsaturated carboxylic acid with the epoxy group of the epoxy resin in an equivalent amount or a mixing ratio of the equivalent or less. In addition, a thermosetting material such as a melamine resin or a cyanate ester resin, or a combination of the thermosetting material and a phenol resin is one of the preferable application examples. In addition, the use of a flexibility-imparting material is also a suitable combination, and examples thereof include butadiene acrylonitrile rubber, natural rubber, acrylic rubber, SBR, carboxylic acid-modified butadiene acrylonitrile rubber, carboxylic acid-modified acrylic rubber, cross-linked NBR particles, Carboxylic acid-modified crosslinked NBR particles and the like.

[0007] By adding such various resin components, it becomes possible to impart various properties to the cured product while maintaining basic properties such as photocurability and thermosetting properties. For example, a combination with an epoxy resin or a phenol resin can provide a cured product with good electrical insulation.
When a rubber component is blended, the cured product is given tough properties, and the surface of the cured product can be easily roughened by surface treatment with an oxidizing chemical. The curable composition may also contain commonly used additives (polymerization stabilizer, leveling agent, pigment, dye, etc.). There is no problem in adding a filler. As the filler, silica, fused silica, talc, alumina, hydrated alumina, barium sulfate, calcium hydroxide, aerosil, inorganic fine particles such as calcium carbonate, powdered epoxy resin, organic fine particles such as powdered polyimide particles, powdered Teflon particles And the like. These fillers may be subjected to a coupling treatment in advance. These dispersions can be achieved by a known kneading method such as a kneader, a ball mill, a bead mill, and a three-roll mill. As a method for forming the insulating resin layer, a method in which a liquid resin is applied by a method such as roll coating, curtain coating, or dip coating, or a method in which a film is formed into a film and laminated by lamination can be used.

Next, the insulating resin layer is exposed through a photo tool to form a via hole connected to the first circuit (FIG. 1- (c)). Exposure is performed using the same method as that for forming a normal wiring board resist. Next, via holes for connecting to the first circuit are formed in the insulating resin layer by a method of etching the unexposed portions with a developing solution (FIG. 1).
-(D)). As the developer, an aqueous alkaline developer containing an organic solvent is used. Examples of the organic solvent used in the developer include glycol derivatives such as ethylene glycol, propylene glycol, trimethylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, pinacol, and the like. Examples include dimers, trimers, multimers, and lower alkyl substituents such as methyl, ethyl, propyl, and butyl groups. Specific examples include diethylene glycol, ethylene glycol monoethyl ether, diethylene glycol monoethyl ether, triethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, and the like.
Also, diacetone alcohol, acetone, ethyl acetate,
2-methoxyethanol, 2-ethoxyethanol, ethyl alcohol, methyl alcohol, isopropyl alcohol, butyl alcohol and the like are used. These are 2
It may contain more than one kind of organic solvent. In particular, diethylene glycol monobutyl ether is effective for that purpose. The concentration of the organic solvent is 1 to 50% by volume. Preferably, it is 5 to 35% by volume. Examples of the alkali substance used in the developer include alkali metal hydroxides, carbonates, phosphates, borates and the like. Examples include sodium hydroxide, potassium hydroxide, ammonium hydroxide, sodium carbonate, potassium carbonate, trisodium phosphate, sodium borate, sodium metasilicate and the like. As a combination of an aqueous alkaline developer containing an organic solvent, it is preferable to use an aqueous solution containing diethylene glycol monobutyl ether and sodium borate. The concentration of diethylene glycol monobutyl ether is preferably 5 to 30% by volume, and the concentration of sodium borate is preferably 5 to 30 g / l.

Next, the insulating resin layer after the development is rinsed. As the rinsing liquid, an aqueous solution containing an organic solvent is used. As the organic solvent, the organic solvent described for the developer can be used. It is particularly preferable to use an aqueous solution containing diethylene glycol monobutyl ether.
The concentration of diethylene glycol monobutyl ether was 0.1.
It is preferably from 1 to 90% by volume, particularly preferably about 1 to 20% by volume. The rinsing process is not particularly limited, whether it is dipping or spraying. If it is less than 0.1% by volume, the effect is poor. If it exceeds 90% by volume, there is no difference in effect, and a large amount of energy is required for waste liquid treatment.

Next, after treating the insulating resin layer with an oxidizing roughening solution, copper plating is deposited on the insulating resin layer to form a second circuit and to connect via holes to each other (FIG. 1).
(E)). In this case, a method in which the insulating resin layer is cured with ultraviolet light or ultraviolet light and heat and then immersed in an oxidizing roughening liquid may be used. As the oxidizing roughening solution, a roughening solution of chromium / sulfuric acid, a roughening solution of alkali permanganate, a roughening solution of sodium fluoride / chromium / sulfuric acid, a roughening solution of borofluoric acid, or the like can be used. Further, as a method of forming the second circuit, a catalyst for electroless plating is applied to the surface of the roughened insulating resin layer to deposit electroless plated copper on the entire surface, and if necessary, the circuit conductor is formed by electrolytic plating. To the required thickness, by etching and removing unnecessary parts,
Using an insulating resin layer containing a plating catalyst, a method of forming a plating resist and forming a circuit by electroless plating only at a necessary portion, and roughening an insulating resin layer not containing a plating catalyst and plating after applying a plating catalyst A method in which a resist is formed and a circuit is formed by electroless plating only at a necessary portion can be used.

When the present invention is to be multi-layered, the above method (FIG. 1- (b) -FIG. 1- (e)) is repeated to form a multi-layer (step: FIG. 1- (f) -FIG. 1-). (H)). On this occasion,
Preferably, before forming an insulating layer supporting the next circuit layer, the surface of the underlying circuit layer conductor is roughened to form irregularities, or the surface of the circuit layer conductor is used as in a conventional multilayer wiring board. Can be oxidized to form irregularities, or the irregularities formed by oxidation can be reduced using an alkaline reducing agent such as sodium borohydride or dimethylamine borane to increase the adhesion between layers.

The present invention relates to a method for producing a build-up multi-layer wiring board using a photosensitive material as an insulating layer, which can be formed without causing scuffing or peeling at the bottom of a via hole for interlayer connection. A multilayer printed wiring board having excellent connection reliability can be provided. Hereinafter, the present invention will be described specifically with reference to Examples.

[0013]

【Example】

(Example 1) (1) An insulating resin having the following composition was applied on a polyethylene terephthalate film (thickness: 50 μm) subjected to a release treatment, and dried at 80 ° C. for 10 minutes to form a film having a thickness of 60 μm. .・ 30 parts by weight of 2,2′-bis (4,4′-N-maleimidylphenoxyphenyl) fluorocarbon (BBMI, manufactured by Hitachi Chemical Co., Ltd.) 45 parts by weight of acid-modified ethoxy resin synthesized by reacting phthalic acid at 150 ° C. for 10 hours in a nitrogen atmosphere. 20 parts by weight-1,3-Phase (9,9-acrylicino) heptane 5 parts by weight-Aluminum hydroxide 10 parts by weight-Dolphin Cure 651 (trade name, manufactured by Chihwa Ikki Co.) 5 parts by weight (2) 18 µm A glass cloth based epoxy resin copper-clad laminate MCL-E-67 (trade name, manufactured by Hitachi Chemical Co., Ltd.) with thick copper foil attached to both sides There was subjected to circuit patterned into a desired shape by etching processing. (3) After the etching, the surface of the conductor pattern was subjected to an oxidation treatment and a reduction treatment in order to roughen the copper. (4) The film of (1) was laminated on the circuit forming surface of the substrate to form an insulating resin layer. HLM- for laminator
Using V530 (trade name, manufactured by Hitachi AC Co., Ltd.), the test was performed under the following conditions.・ Laminating atmosphere: under reduced pressure (760 torr) ・ Air gauge pressure: 3 Kg / cm ²・ Laminating speed: 0.5 m / min ・ Roll temperature: 110 ° C. (5) A photo tool having a shielding portion formed in a portion to be a via hole After irradiating 300 mJ / cm ² of ultraviolet light, the polyethylene terephthalate film on the film surface was peeled off, and the unexposed portion was developed and rinsed. As a developing solution, an aqueous alkaline developing solution containing an organic solvent was used, and diethylene glycol monobutyl ether was used as an organic solvent to 10% by volume. 15 g of sodium tetraborate (decahydrate) as an alkaline substance
/ L, and developed at 40 ° C for 4 minutes at a spray pressure of 1.0 kg / cm ² . As an aqueous solution containing an organic solvent as a rinse solution after development, a via hole is formed by rinsing with an aqueous solution containing 10% by volume of diethylene glycol monobutyl ether at 25 ° C. for 4 minutes at a spray pressure of 1.0 kg / cm ^2. did. (6) The substrate after development and rinsing was irradiated with ultraviolet light of ² J / cm ² and then heat-treated at 150 ° C. for 1 hour to perform post-curing. (7) To chemically roughen the insulating layer, use KM as a roughening solution.
_{n0 4: 60g / l, NaOH} : to prepare an aqueous solution containing 40 g / l, was immersed warmed to 50 ° C. for 10 minutes. Thereafter, a neutralization treatment was performed by immersion in an aqueous solution of 30 g / l of SnCl _{2 and} 300 ml / l of HCl at room temperature for 5 minutes. (8) After the roughening treatment, in order to form a conductor circuit on the surface of the insulating layer, first, a plating pretreatment including the HS-202B (trade name, manufactured by Hitachi Chemical Co., Ltd.) catalyst for electroless copper plating is performed. Immersed in electroless copper plating CUST-201 (trade name, manufactured by Hitachi Chemical Co., Ltd.) at room temperature for 15 minutes, and further electroplated in a copper sulfate plating bath to form a 20 μm thick layer on the surface of the insulating layer.
Was formed. (9) Next, in order to remove unnecessary portions of the plated conductor, an etching resist was formed, and etching was performed using a hydrochloric acid / iron chloride etchant to produce a circuit pattern.

(Comparative Example 1) In Example 1, the rinsing liquid used for the rinsing treatment was changed to water. Otherwise, the procedure was the same.

Table 1 shows the characteristics of the multilayer printed wiring board manufactured as described above. The test was performed as follows. Via hole scouring rate: Exposure, development, and rinsing treatments were performed through a photo tool in which a 150 μm and 125 μm diameter shielding portion was formed in a portion to be a via hole.
Observation was made at 0 places, and the number of scouring and peeling was counted.
The number of through holes observed in the denominator was the number of scouring and peeling out of the through holes observed in the numerator. Hot oil test: The circuit patterns obtained in Examples and Comparative Examples were immersed in 260 ° C. oil for 20 seconds, and immersed in a water-solvent mixture at room temperature for 20 seconds as one cycle. After 100 cycles, the circuit pattern having a change rate of the conduction resistance of less than 10% was evaluated as “OK”, and the circuit pattern having the change rate of the conduction resistance of 10% or more was evaluated as “NG”.

[0016]

[Table 1] Item Example 1 Comparative example 1 Wire hole diameter (phototool value) 150 μm 125 μm 150 μm 125 μm Wire hole generation rate 0/100 0/100 8/100 12/100 (number of holes observed / number of observation holes) hot oil test 20 cycles OK OK OK OK 40 cycles OK OK OK NG 100 cycles OK OK NG NG

In Example 1 and Comparative Example 1, the difference was due to the difference in the rinsing solution with the same developing solution. However, if scouring or peeling occurred in the via hole, the hot oil test was a measure of the connection reliability of the via hole. The number of test cycles at By treating with a rinsing solution containing diethylene glycol monobutyl ether as an organic solvent as in Example 1, scouring and peeling in via holes are eliminated, and connection reliability lines are improved.

[0018]

As described above, according to the present invention,
It is possible to stably form a via hole without scouring and peeling, and to provide a method of manufacturing a multilayer printed wiring board by a build-up method excellent in connection reliability between layers.

[Brief description of the drawings]

FIGS. 1A to 1H are cross-sectional views illustrating a method for manufacturing a multilayer printed wiring board according to the present invention.

FIG. 2 is a schematic sectional view of a via hole for explaining a problem to be solved by the invention. (A) is a schematic diagram for explaining scuffing, and (b) is a schematic diagram for explaining scuffing.

[Explanation of symbols]

 1. 1. Insulating substrate 2. First circuit First insulating layer 4. Photo tool 5. UV rays 6. Via hole 61. Via hole 7. Roughened surface 71. Roughened surface 8. Second circuit 9. Second insulating layer 10. Third circuit

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masaki Morita 1500 Oji Ogawa, Shimodate City, Ibaraki Pref.Hitachi Chemical Industry Co., Ltd. Inside Shimodate Research Institute (72) Inventor Tetsuro Irino 1500 Ogawa Oaza, Shimodate City, Ibaraki Prefecture Inside the Shimodate Plant of Hitachi Chemical Co., Ltd.

Claims (4)

[Claims] 1. A circuit including a photosensitive insulating resin layer provided on an inner conductor formed on an insulating substrate, exposure and development through a photo tool to form a via hole, and plating on the surface of the photosensitive insulating resin layer. In the method for producing a multilayer wiring board in which conductor wiring is formed by performing processing, in the development, an aqueous alkaline developer containing an organic solvent is used as a developer, and an aqueous solution containing an organic solvent is used as a rinse after development. A method for manufacturing a multilayer printed wiring board, comprising: 2. The method for producing a multilayer printed wiring board according to claim 1, wherein the aqueous alkaline developer containing an organic solvent is an aqueous solution containing diethylene glycol monobutyl ether and sodium borate. 3. The method for producing a multilayer printed wiring board according to claim 1, wherein the aqueous solution containing an organic solvent of the rinsing liquid is an aqueous solution containing diethylene glycol monobutyl ether. 4. The method for producing a multilayer printed wiring board according to claim 3, wherein the concentration of diethylene glycol monobutyl ether contained in the rinsing liquid is 0.1 to 90% by volume.