JP2003101226A - Method for manufacturing multilayer wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a multilayer wiring board which has a wiring circuit layer made of a metal foil arranged at least therein, and in which an insulation fault between wiring circuit layers due to the invasion of a moisture does not occur in plating or in a high humidity atmosphere, by generating a gap at the periphery of the internal wiring circuit layer. SOLUTION: A method for manufacturing the multilayer wiring board comprises the steps of coating to form the wring circuit layer 13 made of the metal foil on the surface of a green sheet 11 containing a vitreous component or a mixture of the vitreous component and a ceramic filler component, coating a plasticizer together with an organic binder on the periphery of the layer 13 in a width of 30 μm or more to form a plasticizer-containing layer 14, then laminating the green sheets, and baking the laminate.

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 wiring board in which a wiring circuit layer made of metal foil is provided inside a ceramic insulating substrate such as glass ceramic.

[0002]

2. Description of the Related Art Ceramic wiring boards are generally manufactured by the following method. 1) A ceramic composition is kneaded with a resin component or a solvent, and a green sheet is formed by a doctor blade method. 2) The obtained green sheet is perforated, and the hole is filled with a conductor paste to form a via-hole conductor. 3) A conductor circuit layer is screen-printed on the surface of the green sheet to deposit a wiring circuit layer on the green sheet. 4) A plurality of these are aligned to remove the binder, and then fired.

Recently, in order to reduce wiring resistance, miniaturize wiring, and improve accuracy, attempts have been made to form a wiring circuit layer by a metal foil instead of a conductor paste. For example, Japanese Patent Laid-Open Nos. 11-224984 and 20
No. 00-200969, etc., a metal foil adhered on a resin film is etched to form a wiring circuit layer having a predetermined pattern, which is pressure-transferred onto a ceramic green sheet, and then a plurality of them are laminated, A method of firing to obtain a ceramic wiring board has been reported.

[0004]

However, in the method of using the metal foil for the wiring circuit layer, as shown in FIG.
When the wiring circuit layer 32 made of metal foil is formed in the insulating substrate 31, there is a problem that a gap 33 is likely to occur in the outer peripheral portion of the wiring circuit layer 32 on the laminated surface.

Usually, when a wiring paste is formed by depositing a conductor paste made of metal powder or the like on a ceramic green sheet containing an organic binder by a screen printing method or the like to form a wiring circuit layer, the green sheets are laminated and thermocompression bonded. By doing so, the wiring circuit layer composed of the green sheet and the conductor paste is deformed to form a laminated body with no gap therebetween, and the organic binder is easily removed.
Since the metal foil itself has extremely high rigidity and is dense, the metal foil hardly deforms due to the pressure during lamination or shrinks during firing, and does not pass decomposition gas during the organic binder. Therefore, gaps and voids are likely to occur around the metal foil.

To address this problem, it has been proposed to embed a wiring circuit layer made of a metal foil on the surface of the green sheet by applying pressure. However, a high pressure is applied to embed the wiring circuit layer on the surface of the green sheet. Alternatively, there is a problem that the properties of the green sheet are impaired because the green sheet needs to be soft, and the dimensional stability is lacking.

Further, the generation of the gap becomes smaller as the thickness of the wiring circuit layer made of the metal foil is made thinner, but it is necessary to make it very thin in order to completely prevent the formation of the gap. However, there is a problem that the electric resistance of the wiring circuit layer increases.

Further, since the wiring circuit layer made of a metal foil can form a fine wiring pattern by etching, the wiring circuit layers are very close to each other. However, the insulating layer sandwiched between the wiring circuit layers has the organic binder removed. However, there is a problem in that sintering defects are likely to occur and voids are easily generated.

Therefore, there is a problem that the plating liquid or water enters the above-mentioned gaps or voids around the wiring circuit layer in the plating process or in a high humidity atmosphere to deteriorate the insulation between the wiring circuit layers.

Therefore, according to the present invention, in a multilayer wiring board in which a wiring circuit layer made of a metal foil is provided at least inside, a void is generated around the wiring circuit layer inside or a void due to defective removal of the organic binder. It is an object of the present invention to provide a method of manufacturing a multilayer wiring board in which insulation failure between wiring circuit layers does not occur due to plating treatment or ingress of moisture in a high humidity atmosphere due to the occurrence of the above.

[0011]

As a result of repeated studies on the above problems, the present invention provides a plasticizer around the same plane as a wiring circuit layer made of a metal foil disposed inside an insulating substrate. The present invention has been found out that the application can effectively suppress the generation of a gap around the wiring circuit layer, and has completed the present invention.

That is, in the method for manufacturing a multilayer wiring board of the present invention, a wiring circuit layer made of a metal foil is adhered and formed on the surface of a green sheet containing a predetermined ceramic component, and a plastic circuit is formed around the wiring circuit layer. After applying the agent, the green sheets are laminated and fired.

By applying the plasticizer together with the organic resin, the workability and application area can be easily controlled, and it is effective to apply the plasticizer with a width of 30 μm or more around the wiring circuit layer. Is.

The wiring circuit layer is made of Cu, Ag, A
1, at least 1 selected from Au, Ni, Pt, and Pd
It is desirable that it is made of a seed from the viewpoint of lowering the resistance, and it is desirable that its thickness is 30 μm or less in order to prevent peeling. In addition, the ceramic component in the green sheet,
By forming a glass component or a mixture of a glass component and a ceramic filler component, it can be formed by cofiring with the low resistance metal foil.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION A multilayer wiring board of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic sectional view showing an example of the multilayer wiring board of the present invention. According to the multilayer wiring board 1 of FIG. 1, the insulating substrate 2 is composed of a laminated body formed by laminating a plurality of ceramic insulating layers 2a to 2c, and between the insulating layers 2a to 2c and on the surface of the insulating substrate 2, A wiring circuit layer 3 made of a high-purity metal foil having a thickness of 30 μm or less, particularly 5 to 20 μm, is adhered and formed. Furthermore, via-hole conductors 4 having a diameter of 80 to 200 μm formed so as to penetrate in the thickness direction are formed in each of the ceramic insulating layers 2a to 2c, thereby connecting the wiring circuit layers 3 to achieve a predetermined circuit. A network for An electronic component 5 such as a semiconductor element is mounted and mounted on the surface of the wiring circuit layer 3.

In the present invention, the ceramic insulating layers 2a to 2c are used.
It is desirable that the insulating substrate 2 is made of glass ceramics obtained by firing a glass component or a mixture of a glass component and a ceramic filler component. It is desirable that the composition composed of 30 to 90% by weight of the filler component be fired. Such glass ceramics has a firing temperature of 800 to 1050.
Since it is as low as ℃, it is advantageous in that it can be fired at the same time as a low-resistance conductor described later. Moreover, since the dielectric constant is generally low, transmission loss of high-frequency signals can be reduced.

Here, as the glass component used,
At least SiO₂Including, Al₂O ₃, B₂O₃, Zn
O, PbO, alkaline earth metal oxides, alkali metal acids
Containing at least one of the following compounds:
For example, SiO₂-B₂O₃System, SiO₂-B₂O₃-Al₂
O₃System-MO system (M is Ca, Sr, Mg, Ba or
Or Zn), etc., borosilicate glass, alkali silicic acid
Glass, Ba-based glass, Pb-based glass, Bi-based glass, etc.
Is mentioned.

These glass components are amorphous glasses that remain amorphous even after firing, and lithium silicate, quartz, cristobalite, cordierite, mullite, anorthite, sergian and spinel by firing. , Glassite, willemite, dolomite, petalite, or any crystallized glass that precipitates at least one crystal of a derivative thereof.

As the ceramic filler component,
SiO ₂ , such as quartz and cristobalite, and Al
₂ O ₃ , ZrO ₂ , mullite, forsterite, enstatite, spinel, magnesia, calcium zirconate, strontium silicate, calcium titanate, barium titanate, etc. are preferably used.

The wiring circuit layer 3 is made of a metal foil made of high-purity metal of 99.5% by weight or more, and particularly Cu, Ag,
It is possible to use at least one selected from the group consisting of Al, Au, Ni, Pt and Pd. Further, it is desirable that the via-hole conductor 4 be filled with a conductor having the same component as that of the wiring circuit layer 3.

Further, in the multilayer wiring board of the present invention, the wiring circuit layer 3 on the surface has various electronic parts 5 such as IC chips.
Is used as a pad for mounting the wiring, as a shield conductor film, and as a terminal electrode for connecting to an external circuit, and various electronic components 5 are bonded to the wiring circuit layer 3 via solder or a conductive adhesive. It Although not shown,
If necessary, a thick film resistor film such as tantalum silicide or molybdenum silicide, a wiring protective film, or the like may be further formed on the surface of the wiring board.

Further, by applying this plasticizer with a width of 30 μm or more, particularly 50 μm or more around the wiring circuit layer 3a, it is possible to effectively prevent the formation of gaps.

According to the present invention, a method for manufacturing the above wiring board will be described with reference to FIG. First, a crystallized glass component or an amorphous glass component as described above is mixed with the ceramic filler component to prepare a ceramic composition, and an organic binder or the like is added to the mixture, and then a doctor blade method or a rolling method. Then, the green sheet 11 having a thickness of about 50 to 500 μm is formed by forming into a sheet by a pressing method or the like (FIG. 2A).

Then, the diameter of the green sheet 11 is reduced to 80 by laser, microdrill, punching or the like.
A through hole having a thickness of up to 200 μm is formed, and a conductor paste is filled in the through hole to form a via hole conductor 12 (FIG. 2).
(B)). In the conductor paste, in addition to metal components such as Cu and Ag, an organic binder such as an acrylic resin and an organic solvent such as toluene, isopropyl alcohol, acetone, and terpineol are homogeneously mixed and formed.
The organic binder is based on 100 parts by weight of the metal component,
0.5 to 15.0 parts by weight, and the organic solvent is preferably mixed in a ratio of 5 to 100 parts by weight with respect to 100 parts by weight of the solid component and the organic binder. A slight amount of glass component or the like may be added to this conductor paste.

Next, a wiring circuit layer 13 made of a high-purity metal conductor, especially a metal foil is formed on the surface of the green sheet 11 (FIG. 2 (c)). For the wiring circuit layer 13 made of such a metal foil, a method of forming a desired circuit by a known photo-etching method or the like after the metal foil is bonded to the surface of the green sheet 11 is known. However, since the green sheet is altered by the etching solution, the transfer method is used in the present invention.

As a method of forming the wiring circuit layer 13 by the transfer method, first, a high-purity metal conductor, particularly a metal foil, is bonded onto a transfer film made of a polymer material or the like, and then a resist is formed on the surface of the metal conductor by a circuit. After depositing in a pattern, the wiring circuit layer 1 is subjected to etching treatment and resist removal.
3 is formed.

Then, after the transfer film having the mirror image wiring circuit layer 13 is aligned with the surface of the green sheet 11 having the via-hole conductor 12 and laminated and pressure-bonded,
By peeling off the transfer film, the wiring circuit layer 13 can be formed on the surface of the green sheet 11. At this time, in order to enhance the transferability of the wiring circuit layer 13 made of a metal foil, the surface roughness Rz of the side of the wiring circuit layer 13 made of a metal foil that comes into contact with the green sheet 11 is set to 3 to 6 μm, and thus the wiring is formed. The adhesion of the circuit layer 13 to the green sheet 11 can be improved.

Next, a plasticizer is applied to at least the periphery of the wiring circuit layer 13 on the surface of the green sheet 11 on which the wiring circuit layer 13 is formed. When the plasticizer penetrates into the green sheet 11, the part softens or dissolves,
Plastic deformation becomes easy. For this reason, in the laminating process described later, plastic deformation is performed so as to match the shape of the wiring circuit layer 3 by applying pressure when laminating a plurality of green sheets, so that it is possible to prevent the generation of a gap between layers.

As a method of applying a plasticizer around the wiring circuit layer 13, a plasticizer is mixed with an organic binder to prepare a viscosity-adjusted paste, which is then printed by a screen printing method or an offset printing method. It is preferable to apply the plasticizer-containing layer 14 to the wiring circuit layer 13 around the circuit layer 13 with a predetermined width to form the plasticizer-containing layer 14 because workability and application of the plasticizer to unnecessary portions can be prevented. In particular, the screen printing method is effective for obtaining a sufficient coating amount.

As the type of the organic binder mixed with the plasticizer, for example, methacrylate, acrylate, α-methylstyrene, carbonate or the like, which has good thermal decomposability, is preferably used, and this organic binder is based on 100 parts by mass of the plasticizer. , 2 to 20 parts by mass is suitable.

The amount of the plasticizer applied is preferably 5 g / m ² or more, but if the amount of plasticizer is too large, the green sheet becomes too soft and the shape retention becomes poor.
Since the green sheet may be cracked, it is preferably 50 g / m ² or less.

The plasticizer is applied to a region having a width of 30 μm or more around the wiring circuit layer 13 to cause plastic deformation of the green sheet to cause the wiring circuit layer 13 to undergo plastic deformation.
It is possible to prevent the formation of gaps around the.

The above plasticizer is used for the green sheet 1.
Although it is applied around the wiring circuit layer 13 formed on the surface of No. 1, according to the present invention, the present invention is not limited to this. It may be applied to the periphery of the circuit layer forming portion, or may be applied to a portion of another green sheet (not shown) laminated on the wiring circuit layer 13 that faces the periphery of the wiring circuit layer 13. May be.

In addition to the above plasticizer and organic binder, it is possible to add glass and / or filler, which are the ceramic components in the green sheet, to the plasticizer-containing layer 14.

The formation of the plasticizer-containing layer 14 is not always necessary for the green sheets located on the outermost surface and the lowermost surface of the wiring board, because the phenomenon such as delamination does not occur.

Next, a plurality of green sheets produced in the same manner as above are laminated and pressure-bonded to form a laminated body 15 (FIG. 2 (e)). For stacking green sheets, a method of applying heat and pressure to the stacked green sheets to perform thermocompression bonding, a method of applying an adhesive consisting of an organic binder, plasticizer, solvent, etc. between the sheets and performing thermocompression bonding, etc. are adopted. It is possible.

Thereafter, the laminated body 15 is fired. When the wiring circuit layer 13 made of a metal foil is provided, the metal foil itself is a very dense body and does not shrink by firing like a green sheet. Strain may occur between the insulating layer and the insulating layer, and warpage or cracks may occur. Therefore, upon firing, it is desirable to perform firing while suppressing firing shrinkage in the plane direction.

As a method for firing while suppressing shrinkage in the plane direction, for example, 1)
Firing is performed while applying a pressure of 0 to 30 MPa. 2) As shown in FIG. 3f, the non-sinterable ceramic sheet 16 made of alumina or the like that does not shrink by firing at the firing temperature is laminated 1 above.
A method of adhering to the front surface or the front and back surfaces of No. 5 and firing is mentioned. 2) is more advantageous in that no pressurizing means is required.

The hard-to-sinter ceramic sheet 16 in the method 2) is formed into a sheet-like slurry by adding an organic binder, a plasticizer, a solvent and the like to a ceramic component containing a hard-to-sinter ceramic material as a main component. Obtained. The non-sinterable ceramic material is specifically composed of a ceramic composition that does not densify at a temperature of 1100 ° C. or lower, and specifically, Al ₂ O ₃ , SiO ₂ , MgO, Zr.
Powders of at least one of O ₂ , BN and TiO ₂ or a compound thereof (forsterite, enstatite, etc.) can be mentioned. Further, as the organic binder, the plasticizer and the solvent, the same materials as those used for the glass ceramic green sheet can be used. Further, by adding 0.5 to 15% by volume of a glass component in the hardly-sinterable ceramic sheet, the adhesion with the green sheet is increased, the effect of suppressing shrinkage is increased, and the surface of the green sheet is increased. It has an advantage that the generation of voids due to the diffusion of the glass component can be suppressed.

The firing temperature is 100 to 850 ° C., especially 400 to 850 ° C.
After heat treatment in a nitrogen atmosphere at 750 ° C. to decompose and remove organic components in the green sheet and the via-hole conductor paste, firing is performed in a nitrogen atmosphere at 800 to 1100 ° C.
When an Ag conductor is used for the wiring circuit layer, the firing atmosphere can be performed in the air.

After that, the multilayer ceramic substrate 17 can be manufactured by appropriately removing the hardly-sinterable ceramic sheet 16 by ultrasonic cleaning, polishing, water jet, chemical blast, sand blast, wet blast, or the like.

The multilayer wiring board 17 thus obtained
Since the shrinkage during firing is suppressed only in the thickness direction by the pressure or the hardly-sinterable ceramic sheet, the shrinkage in the plane direction can be suppressed to 0.5% or less, and the glass ceramic green sheet Since the binding sheet is uniformly and surely bonded to the entire surface by the binding sheet, it is possible to prevent the binding sheet from being warped or deformed due to partial peeling or the like.

[0043]

EXAMPLES SiO ₂ : 37% by weight, Al ₂ O ₃ : 27% by weight, CaO: 11% by weight, ZnO: 12% by weight, B
₂ O ₃ : A glass ceramic raw material composed of 73% by weight of a crystallized glass A powder (softening point 850 ° C.) having a composition of 13% by weight and an average particle size of 3 μm, and 27% by weight of silica having an average particle size of 2 μm as a ceramic filler. 11 parts by weight of isobutyl methacrylate resin as an organic binder and 5 parts by weight of dibutyl phthalate as a plasticizer were added to 100 parts by weight of powder as an organic binder, and toluene was mixed as an organic solvent for 36 hours by a ball mill to prepare a slurry. did. The obtained slurry is 0.2m thick by the doctor blade method.
m green sheet A was formed.

Next, a copper foil having a thickness of 0.02 mm formed on the PET film was formed by photoetching as shown in FIG.
Three parallel wiring parts 21 having a length of 30 mm shown in FIG.
A wiring circuit layer 23 including the measurement terminals 22 was manufactured. The wiring width of each of the three parallel wiring portions 21 is 1 mm,
The intervals were each 1 mm. The printed circuit layer 23 formed on this PET film is heat-pressed onto the green sheet A,
The PET film was peeled off and the wiring circuit layer was transferred onto the surface of the green sheet A.

On the other hand, with respect to 100 parts by mass of various plasticizers shown in Table 1, 10 parts by mass of an organic binder made of isobutyl methacrylate resin was added and mixed to give a viscosity of 8
A Pa · S paste was prepared.

Then, the paste containing the plasticizer having a maximum width of 2 mm was applied around the wiring circuit layer 23 on the surface of the green sheet A.

Further, a green sheet B having a thickness of 0.2 mm is prepared in the same manner as described above, and the measurement terminals 22 of the wiring circuit layer 23 of the green sheet A of the green sheet B are manufactured.
A through hole was formed in a portion opposite to, and a copper paste was filled in the through hole to form a via hole conductor 25. Further, a wiring circuit layer was transferred and formed on the surface of the green sheet B in the same manner as above.

Then, the green sheet B is laminated on the green sheet A on which the wiring circuit layer 23 and the ceramic layer 24 are formed, and thermocompression bonding is performed at 80 ° C. and 10 MPa to embed the wiring portion 22 inside the substrate. And measuring terminal 2
2 was connected to the measurement electrode 26 on the surface via the via-hole conductor 25 to obtain a laminated body 27.

After that, in order to decompose and remove the organic components (binder, plasticizer, etc.) in the laminate 27, heat treatment is performed at 750 ° C. for 3 hours in a nitrogen atmosphere containing water vapor to reduce the residual carbon amount to 300 ppm or less. 930 after reducing
Firing was carried out at 1 ° C. for 1 hour to produce a wiring board having the wiring circuit layer 23.

Further, with respect to the wiring circuit layer on the surface of this wiring board, a Ni plating layer having a thickness of 3 μm and a thickness of 2 μm
m Au plating layer was deposited by electroless plating. (Evaluation) Next, a lead wire was attached to the measurement electrode 26 of the wiring board, a temperature / humidity cycle bias test was performed, and the electrical resistance between the two measurement electrodes 26 was measured to evaluate the insulation property. The temperature / humidity cycle bias test is performed at a temperature of 5 ° C. and a humidity of 4 with a voltage of 5 V applied between the two measurement electrodes 26.
It was repeatedly exposed to an atmosphere of 0%, a temperature of 85 ° C., and a humidity of 95% for 2 hours each. The temperature / humidity cycle bias test is performed up to 1000 cycles, the electrical resistance between the measuring electrodes 26 is measured, and the one having a resistance value of 1 MΩ or more is judged as a good product (◯), and the one having a resistance value of less than 1 MΩ is defective. It was judged as (x) and the results are shown in Table 1.

Further, the peripheral portion of the wiring circuit layer in the wiring board manufactured as described above was observed by a scanning electron microscope photograph, and the number of voids in the peripheral portion of the wiring circuit layer made of metal foil was measured. The number of voids is 10 μm x 1
The average of the number of voids in three observation areas of 00 μm was obtained. The results are shown in Table 1.

[0052]

[Table 1]

According to the results shown in Table 1, in the conventional wiring board (Sample No. 1) in which the plasticizer was not applied, a gap was found around the wiring circuit layer, and the plating liquid or the moisture was found in the gap. Has invaded, which confirmed poor insulation at an early stage.

On the other hand, in the case of the product of the present invention in which the plasticizer was applied to the periphery of the wiring circuit layer, Sample No. Compared with 1, the generation of gaps and voids between the wiring circuit layers is suppressed,
The occurrence of insulation failure between wiring circuit layers was improved.

[0055]

As described above in detail, according to the method for manufacturing a multilayer wiring board of the present invention, the insulation between adjacent wiring circuit layers is generated due to the formation of gaps or the delamination in the periphery of the wiring circuit layer made of a metal foil. Can be effectively prevented from being damaged by the penetration of water due to the plating treatment or being kept in a high humidity atmosphere, and a highly reliable wiring board can be obtained.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing an example of a multilayer wiring board of the present invention.

FIG. 2 is a manufacturing process diagram in the method of manufacturing a multilayer wiring board according to the present invention.

FIG. 3 is a pattern diagram of a wiring circuit for evaluation.

FIG. 4 is a schematic cross-sectional view of a conventional multilayer wiring board.

[Explanation of symbols]

1 Multilayer wiring board 2 insulating substrate 2a-2d insulating layer 3 wiring circuit layer 4 Via hole conductor 5 Semiconductor element 6 Ceramic layer

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yasuhide Minmin             Kyocera Co., Ltd. 1-4 Yamashita Town, Kokubun City, Kagoshima Prefecture             Shikisha Research Institute F-term (reference) 5E346 AA12 AA15 AA60 CC31 CC32                       CC34 CC37 CC38 CC39 DD12                       DD23 GG09 GG17 HH11

Claims (6)

[Claims] 1. A green sheet containing a predetermined ceramic component, a wiring circuit layer made of a metal foil is formed on the surface of the green sheet, and a plasticizer is applied to the periphery of the wiring circuit layer. A method for manufacturing a multilayer wiring board, comprising laminating and firing. 2. The method of manufacturing a multilayer wiring board according to claim 1, wherein the plasticizer is mixed with an organic binder and applied. 3. The plasticizer is applied around the wiring circuit layer in an amount of 3 times.
The method for manufacturing a multilayer wiring board according to claim 1 or 2, wherein the width is 0 μm or more. 4. The method for manufacturing a multilayer wiring board according to claim 1, wherein the wiring circuit layer has a thickness of 30 μm or less. 5. The wiring circuit layer comprises Cu, Ag, Al, A
5. The method for manufacturing a multilayer wiring board according to claim 1, comprising at least one selected from u, Ni, Pt, and Pd. 6. The multilayer wiring board according to claim 1, wherein the ceramic component in the green sheet is a glass component or a mixture of a glass component and a ceramic filler component. Production method.