JP3069476B2 - Multilayer printed wiring board and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer printed wiring board and a method for manufacturing the same, and more particularly, to a multilayer printed wiring board excellent in heat cycle resistance and a method for manufacturing the same.

[0002]

2. Description of the Related Art In recent years, multilayer printed wiring boards suitable for high-density wiring or high-speed arithmetic functions have recently been constructed by alternately building up conductive circuits and interlayer insulating layers, and providing internal and external circuits through via holes and the like. The build-up multilayer wiring board which connects and conducts is attracting attention. This build-up multilayer wiring board is mainly manufactured by an additive method.

In the additive method, an insulating material layer is formed by applying a resin insulating material for electroless plating on an insulating substrate such as glass epoxy, and then the surface of the insulating material layer is roughened. Forming a plating resist on the surface
Thereafter, a method of attaching a metal to be a conductor circuit by electroless plating.

According to such a method, since a conductor circuit is deposited on the roughened insulating material layer by plating or the like, the adhesion between the interlayer insulating material layer and the conductor circuit provided thereon is improved. Can be.

On the other hand, in the above method, as means for improving the adhesion between the conductor circuit and the interlayer insulating material layer provided thereon, conventionally, the surface of the conductor circuit is oxidized and reduced to roughen the surface. That is, a so-called blackening / reducing treatment is performed. When such a blackening / reducing treatment is performed, the surface of the conductor circuit is roughened, and the roughened surface serves as an anchor, thereby physically strengthening the connection between the interlayer insulating material layer and the conductor circuit. .

[0006]

However, the adhesion between the conductor circuit and the interlayer insulating material layer provided thereon is still insufficient even by using the above-described blackening / reducing treatment technique. Under severe environmental conditions, there is a problem that the printed wiring board lacks heat cycle resistance. For example, according to a test under conditions according to MIL-883 at −6 ° C. to 150 ° C., the heat cycle resistance of the printed wiring board is 30 cycles at the maximum number of cycles at which the interlayer insulating layer does not peel.
It was about 0 cycles.

An object of the present invention is to solve the above-mentioned problems of the prior art, and in particular, to provide a multilayer printed wiring board having excellent heat cycle resistance and a manufacturing technique therefor.

[0008]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies for realizing the above object, and as a result, have found that a roughened layer made of an electroless plating film of needle-like crystals is provided at the interface between a conductor circuit and an interlayer insulating material layer. It has been found that the above-mentioned object can be realized by providing, and the present invention has been reached.

That is, according to the present invention, a conductive circuit having a roughened layer on at least a part of the surface is provided on a substrate, and an interlayer insulating material layer is provided on the substrate including the conductive circuit. In the multilayer printed wiring board in which another conductive circuit is provided on the interlayer insulating material layer, the roughened layer is made of Cu, Ni and P, preferably 90 <Cu <100 m
ol%, 0 <Ni <10 mol%, and 0 <P <10 mol% comprising a layer containing a eutectic compound, wherein the roughened layer is a needle-shaped crystal. It is desirable that the film has a thickness of 5 μm or less. The method for manufacturing a multilayer printed wiring board includes forming a roughened layer on at least a part of the surface of a conductive circuit provided on a substrate, and then forming an interlayer insulating material layer on the substrate, In the method for manufacturing a multilayer printed wiring board in which a conductor circuit is provided on an interlayer insulating material layer, the substrate provided with the conductor circuit is immersed in an electroless plating bath containing at least a Cu compound, a Ni compound, and hypophosphite. Thereby forming a roughened layer containing a eutectic compound composed of Cu, Ni and P on at least a part of the surface of the conductor circuit, thereby producing a multilayer printed wiring board. Cu ion concentration, Ni ion concentration and hypophosphite ion concentration are 2.2 × 10 ^-2 to 4.1 ×, respectively.
10 ^-2 mol / l, 2.2 × 10 ^-3 to 4.1 × 10 ^-3 mol / l, 0.20
By applying electroless plating (eutectic plating) using a plating bath of 0.20.25 mol / l, 90 <Cu <100 mol%, 0 <Ni <10 mol% and 0 <P It is desirable to form a roughened layer containing a eutectic compound of <10 mol%, and the Cu compound, Ni compound and hypophosphite are copper sulfate, nickel sulfate and sodium hypophosphite, respectively. It is desirable. In the present invention, the substrate provided with the conductor circuit is:
A multilayer substrate may be used.

[0010]

The roughened layer formed by the blackening reduction treatment is obtained by oxidizing the copper surface to form copper oxide. However, the strength of the copper oxide constituting the roughened layer is low, and therefore, the roughened layer is formed by thermal shock. It is easily broken and delaminated. In this regard, the roughened layer formed by the eutectic plating of the present invention constitutes the roughened layer.
The strength of the eutectic compound itself consisting of Cu, Ni and P is high,
In addition, the needle-like crystal has an excellent effect as an anchor, and the conductor circuit and the interlayer insulating material layer can be firmly adhered to each other. Therefore, delamination due to thermal shock hardly occurs and heat cycle resistance is improved. improves. Furthermore, since the copper oxide or copper is exposed to the surface, the roughened layer formed by the blackening reduction process is dissolved in the alkaline solution of the chemical copper plating bath, so that a so-called haloing phenomenon easily occurs.
The copper surface is oxidized. In this regard, since the roughened layer formed by the eutectic plating of the present invention is formed of a Cu-Ni-P eutectic compound having higher chemical resistance and oxidation resistance than Cu, the roughened layer is dissolved in a chemical copper plating bath. High adhesion can be secured without dripping or oxidation. As described above, the multilayer printed wiring board of the present invention is characterized in that the roughened layer made of the electroless plating film provided at the interface between the conductor circuit and the interlayer insulating material layer is a eutectic compound made of Cu, Ni and P. There is a feature.

Here, in the present invention, the above-mentioned eutectic compound is in a range shown by hatching in FIG. 1, that is, 90 <Cu <100 m
ol%, 0 <Ni <10 mol% and 0 <P <10 mol%. The reason is that if the Cu content is 90 mol% or less, the crystals of the deposited film become powdery, and if the Ni content is 10 mol% or more, the crystals of the deposited film become powdery and the conductivity deteriorates.
If the content is more than 10 mol%, the resistance value increases and it is difficult to form needle-like crystals. That is, in the above combination, the crystals of the deposited film have a needle-like structure and a structure having an excellent anchor effect.

In the present invention, the roughened layer is desirably a film having a thickness of 5 μm or less, particularly 0.5 μm.
The range from m to 2 μm is preferred. The reason is 0.5 μm
Below 5 μm, the anchor effect is low, while above 5 μm
This is because the surface roughness becomes too large, and the adhesion strength is rather reduced.

In the multilayer printed wiring board of the present invention, even if a conductor circuit on a substrate and another conductor circuit provided on an interlayer insulating material layer are electrically connected to each other through via holes or through holes. Good . If you want to connect in the bus Iahoru, connection
If there is a roughened layer in the area, the resistance value will be high, albeit slightly.
It becomes. However, the blackening reduction process described above
Copper oxide is not formed,
It is not edged and is advantageous compared to the blackening reduction process.
You. Note that the roughened layer at the connection point may be removed in advance or may be configured without the roughened layer .

In the present invention, the resin insulating material used as the interlayer insulating material layer is a hardened heat-resistant resin which is soluble in an acid or an oxidizing agent in a matrix made of a resin which is hardly soluble in an acid or an oxidizing agent. It is desirable that the powder be dispersed. The reason for this is that the interlayer insulating material layer obtained using the above resin insulating material can be easily provided with a roughened surface by an acid or an oxidizing agent, and the interlayer insulating material layer and a conductor provided thereon by electroless plating. This is because adhesion to a circuit can be improved. The heat-resistant resin powder for forming an anchor for forming such a roughened surface is, for example, a heat-resistant resin powder having an average particle diameter of 10 μm or less, and a heat-resistant resin powder having an average particle diameter of 2 μm or less is aggregated. Agglomerated particles having a size of 2 to 10 μm, a mixture of a heat-resistant resin powder having an average particle size of 2 to 10 μm and a heat-resistant resin powder having an average particle size of 2 μm or less, on the surface of the heat-resistant resin powder having an average particle size of 2 to 10 μm It is preferable to select pseudo particles obtained by adhering at least one of a heat-resistant resin powder having an average particle diameter of 2 μm or less and an inorganic powder having an average particle diameter of 2 μm or less. The shape and depth of the formed anchor are desirably adjusted so that the surface roughness is in the range of 1 to 20 μm using resin powders having different particle diameters. Strength is obtained. Further, it is desirable that the matrix resin constituting the resin insulating material has photosensitive characteristics. This is because a via hole can be easily formed by exposure and development by using a resin exhibiting photosensitive characteristics.

Next, a method for manufacturing a multilayer printed wiring board according to the present invention will be described. The production method of the present invention is characterized in that the substrate provided with the conductor circuit is immersed in a plating bath containing at least a Cu compound, a Ni compound and hypophosphite and subjected to electroless plating, whereby the surface of the conductor circuit is provided. Is characterized in that a roughened layer containing a eutectic compound composed of Cu, Ni and P is formed on at least a part of the layer. According to this, the crystal of the film deposited by the electroless plating is a eutectic compound composed of Cu, Ni and P having a needle-like crystal structure, and this needle-like crystal structure forms a conductor circuit and an interlayer insulating film provided thereon. It acts as an anchor effect for improving the adhesion to the material layer.

[0016] Here, the Cu ion concentration in an electroless plating bath, Ni ion concentration and hypophosphite ion concentration, ^{respectively, 2.2 × 10 -2 ~ 4.1 ×} 10 -2 mol / l, 2.2 × 10 - ^Three
Desirably, it is about 4.1 × 10 ⁻³ mol / l and 0.20 to 0.25 mol / l. The reason for this is that, within the above range, the crystalline structure of the deposited film has a needle-like structure, so that the anchor effect is excellent. In addition, a complexing agent, an additive, and the like may be appropriately added to the electroless plating bath in addition to the above compounds. Also,
Before performing the electroless plating, a catalyst nucleus such as Pd may be applied in advance.

The conditions of the above electroless plating are as follows.
80 ° C., deposition rate 1-1.5 μm / 10 min, bath ratio 0.5-1.
0 dm ² / l, bath pH is preferably 8 to 10, and plating time is preferably 5 to 20 minutes. This means that if you deviate from the above conditions,
This is because the deposited plating film does not become dense and the heat cycle resistance is significantly reduced.

In the method of the present invention, after the above-described process of forming a roughened layer on the surface of a conductive circuit on a substrate is completed, an interlayer insulating material layer is provided on the substrate including the conductive circuit, and a via hole Form a through hole for a concave portion or a through hole, and further form a plating resist on this interlayer insulating material layer as necessary, provide another conductive circuit by electroless plating, and obtain a multilayer printed wiring board . Here, when connecting the upper and lower conductor circuits by via holes,
The roughened layer at the connection point may be removed in advance, or the roughened layer may not be provided in the lower conductive circuit . Such a place
In case, prior to providing a roughened layer on the conductor circuit surface by electroless plating, it is a method to keep masking part component that will be connected by via holes. Note that the conductor circuits of the upper layer and the inner layer in the present invention can be provided according to a conventional method.
Hereinafter, examples will be described in detail.

[0019]

EXAMPLES (Example 1) A multilayer printed wiring board by a build-up method was obtained according to the following manufacturing steps (1) to (10). (1) After etching the copper-clad laminate to form the inner layer circuit 1, the substrate is acid degreased, soft-etched, substituted with a Pd catalyst on Cu, activated, and then subjected to the composition shown in Table 1. Plating in the electroless plating bath shown in Fig. 2 (a)
Thus, a roughened layer 2 of Ni-P-Cu eutectic having a thickness of 1 μm was obtained on the entire surface including the side surfaces of the conductor circuit (see FIG. 2A) . The composition of the roughened layer 2 was analyzed by EPMA (X-ray fluorescence analyzer),
Cu: 98 mol%, Ni: 1.5 mol%, P: 0.5 mol%.

[0020]

[Table 1]

(2) Cresol novolak type epoxy resin (manufactured by Yuka Shell, trade name: Epicoat 180S) Bisphenol A type epoxy resin (manufactured by Yuka Shell, trade name: E-1001) is added to 60 parts by weight of 50% acrylate. 40 parts by weight, diallyl terephthalate 15 parts by weight, 2-methyl-1- [4- (methylthio) phenyl] 2-morpholinopropanone-1
(Ciba Geigy, trade name: Irgacure-907) 4
10 parts by weight of an epoxy resin fine powder (manufactured by Toray) having a particle diameter of 5.5 μm and 25 parts by weight of an epoxy resin fine powder (manufactured by Toray) having a particle diameter of 0.5 μm were blended. Then, the mixture was stirred with a homodisper stirrer while adding an appropriate amount of butyl cellosolve to prepare a varnish of a resin insulating material.

(3) After applying the varnish on the inner layer circuit 1 using a roll coater, the applied varnish is heated to 100 ° C.
For 1 hour to form a photosensitive interlayer insulating material layer 3 having a thickness of 50 μm (see FIG. 2B).

(4) A black circle having a diameter of 100 μm and a photomask film in which a punched and cut portion is printed in black are brought into close contact with the wiring board subjected to the treatment in the step (3), and 500 mj / cm is applied by an ultrahigh pressure mercury lamp. Exposure at ² . This was subjected to ultrasonic development with a chlorocene solution to form an opening 4 serving as a via hole having a diameter of 100 μm on the wiring board.

(5) The wiring board is moved for about 30
Exposure at 0 mj / cm ² and further at 100 ° C. for 1 hour and 1 hour
Heat treatment was performed at 50 ° C. for 3 hours. Through these processes, the opening 4 having excellent dimensional accuracy equivalent to a photomask film can be obtained.
(See FIG. 2 (c)).

(6) The surface of the interlayer insulating material layer 3 was roughened by immersing the wiring board in chromic acid for 10 minutes. Further, after neutralization, washing with water and hot water was performed to remove chromic acid from the wiring board.

(7) The wiring board is immersed in a commercially available Pd—Sn colloid catalyst to allow the Pd—Sn colloid 5 to be adsorbed on the inner wall surface of the opening 4 and the surface of the roughened interlayer insulating material layer 3. ° C
For 30 minutes. (See FIG. 2 (d)).

(8) A dry film photoresist was laminated on the wiring board and exposed and developed to form a plating resist 6.

(9) The wiring board was immersed in a 37% aqueous formaldehyde solution as a reducing agent to activate Pd. The processing temperature at this time is 40 ° C., and the processing time is 5 minutes.

(10) Immediately immersing the wiring board in an electroless plating solution having the composition shown in Table 2 and maintaining it in that state for 15 hours, the thickness of the plating film was about 35 μm, and the L / S was 75 μm /
A multilayer printed wiring board having a conductor circuit 7 of 75 μm was obtained (see FIG. 2E).

[0030]

[Table 2]

(Embodiment 2) In this embodiment, the first embodiment will be described.
A multilayer printed wiring board was obtained by a build-up method using a different resin composition. (1) 50% acrylate 100 of phenol aralkyl type epoxy resin (Mitsui Toatsu Chemicals, trade name: XL-225 L)
15 parts by weight of diallyl terephthalate, 4 parts by weight of 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropanone-1 (manufactured by Ciba-Geigy, trade name Irgacure-907), and imidazole 4 parts by weight of a curing agent (trade name: 2PZ-CN, manufactured by Shikoku Chemicals) and 10 parts by weight of melamine resin fine powder having an average particle diameter of 5.0 μm (manufactured by Honen Corporation) were blended. Then, an appropriate amount of butyl carbitol was added to the mixture, and the mixture was stirred with a three-roller to obtain a varnish of a resin insulating material.

(2) After forming the inner layer circuit 1, a roughened layer 2 having a thickness of 1.5 μm is formed in the same electroless plating bath as in Example 1, and a gap coater is formed on the wiring board. After the above varnish was applied, the applied varnish was dried and cured at 80 ° C. for 1 hour to form a photosensitive interlayer insulating material layer 3 having a thickness of 70 μm.

(3) According to the steps (4) to (6) of the first embodiment, the opening 4 serving as a via hole and the surface of the interlayer insulating material layer 3 were roughened. Chromic acid was used for the surface roughening treatment of the interlayer insulating material layer 3.

(4) The wiring board was immersed in a commercially available Pd—Sn colloid catalyst, and the Pd—Sn colloid 5 was adsorbed on the inner wall surface of the opening 4 and the surface of the roughened interlayer insulating material layer 3.

(5) A dry film resist was laminated on the wiring board and exposed and developed to form a plating resist 6.

(6) The wiring board was immersed in a hydrofluoric acid-glucose aqueous solution to activate Pd again. The processing temperature at this time is 30 ° C., and the processing time is 10 minutes.

(7) The wiring board was immediately immersed in an electroless copper plating solution having the composition shown in Table 2 and kept in that state for 15 hours to obtain a plating film having a thickness of about 35 μm and L / S = 50 μm.
A conductor circuit of m / 50 μm was formed.

(8) Further, after the resist 6 is removed and the catalyst present under the resist 6 is removed, the steps (1) to (7) are repeated to build up a multi-layer print of three layers on one side shown in FIG. A wiring board was obtained.

Example 3 By repeating the steps (1) to (8) of Example 2 on both surfaces of the substrate, a six-layer build-up multilayer printed wiring board shown in FIG. 4 was obtained.

(Comparative Example 1) After subjecting a substrate surface on which an inner layer circuit was formed by etching to blackening reduction treatment, an interlayer insulating material layer was formed in the same manner as in Example 1, and further roughened and plated. As a result, a build-up multilayer printed wiring board was obtained.

(Comparative Example 2) A blackening reduction process is performed after the formation of the inner layer circuit, whereby an inner layer circuit—blackening reduction layer—insulating layer—inner circuit—blackening reduction layer—insulating layer—outer layer pattern is formed. Of a single-sided, three-layer build-up multilayer printed wiring board.

Comparative Example 3 A 6-layer build-up multilayer printed wiring board was obtained by forming the structure of Comparative Example 2 on both sides of the substrate on which the inner layer circuit was formed.

With respect to the build-up multilayer printed wiring board prepared as described above, at −65 ° C. × 15 minutes, normal temperature × 10
The heat cycle resistance was measured by a gas phase heat cycle test at 125 ° C for 15 minutes, and the presence or absence of insulation layer peeling after immersion in a solder bath at 260 ° C for 15 seconds was examined. Table 3 shows the results.

As is clear from the results shown in Table 3, it was confirmed that the multilayer printed wiring board according to the present invention had significantly improved heat cycle resistance as compared with the conventional wiring board.

[0045]

[Table 3]

[0046]

As described above, according to the present invention, a multilayer printed wiring board having excellent heat cycle resistance can be manufactured very easily.

[Brief description of the drawings]

FIG. 1 is a diagram showing the composition of a roughened layer deposited by Ni-P-Cu eutectic plating.

FIG. 2 is a manufacturing process diagram showing one embodiment of the present invention.

FIG. 3 is a diagram showing a multilayer printed wiring board obtained in Example 2.

FIG. 4 is a diagram showing a multilayer printed wiring board obtained in Example 3.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Inner layer circuit 2 Roughening layer (Ni-P-Cu eutectic plating) 3 Interlayer insulating material layer 4 Opening 5 Pd-Sn colloid 6 Plating resist 7 Conductor circuit

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H05K 3/46 H05K 3/38

Claims (7)

(57) [Claims] 1. A conductive circuit having a roughened layer on at least a part of a surface is provided on a substrate, and an interlayer insulating material layer is provided on a substrate including the conductive circuit.
In the multilayer printed wiring board in which another conductive circuit is provided on the interlayer insulating material layer, the roughened layer is constituted by a layer containing a eutectic compound composed of Cu, Ni and P. Multi-layer printed wiring board. 2. The roughening layer according to claim 1, wherein 90 <Cu <100 mol%, 0 <
2. A layer comprising a eutectic compound comprising Ni <10 mol% and 0 <P <10 mol%.
2. The multilayer printed wiring board according to item 1. 3. The multilayer printed wiring board according to claim 1, wherein the roughened layer is a coating of a needle crystal. 4. The multilayer printed wiring board according to claim 1, wherein the roughened layer is a coating having a thickness of 5 μm or less. 5. A roughened layer is formed on at least a part of the surface of a conductor circuit provided on a substrate, and then an interlayer insulating material layer is formed on the substrate, and then a conductor is formed on the interlayer insulating material layer. In the method for manufacturing a multilayer printed wiring board provided with a circuit, the substrate provided with the conductor circuit is formed by using at least a Cu compound, Ni
Forming a roughened layer containing a eutectic compound composed of Cu, Ni and P on at least a part of the conductor circuit surface by immersion in an electroless plating bath containing a compound and hypophosphite. A method for manufacturing a multilayer printed wiring board, comprising: 6. The bath has a Cu ion concentration, a Ni ion concentration and a hypophosphite ion concentration of 2.2 × 10 ⁻² to
4.1 × 10 ^-2 mol / l, 2.2 × 10 ^-3 to 4.1 × 10 ^-3 mol / l,
By performing electroless plating using a plating bath of 0.20 to 0.25 mol / l, at least a part of the surface of the conductor circuit has 90 <Cu <100 mol%, 0 <Ni <10 mol% and 0 <P
The method for producing a multilayer printed wiring board according to claim 5, wherein a roughened layer containing a eutectic compound of <10 mol% is formed. 7. The method according to claim 5, wherein the Cu compound, the Ni compound and the hypophosphite are copper sulfate, nickel sulfate and sodium hypophosphite, respectively.