JP2003008225A - Multilayer wiring substrate and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a multilayer wiring substrate, in which failures of adhesion between a wiring circuit layer and an insulating layer are not generated and high planarity of the wiring substrate is kept after the pattern transfer, by preventing oozing of conductive paste for a via-hole conductor to the circumference of the via-hole conductor. SOLUTION: This multilayer wiring substrate comprises a plurality of insulation layers 1a-1c, each containing at least a thermosetting resin, wiring circuit layers 2 embedded in the surfaces of the insulation layers 1a-1c, and via-hole conductors 3 composed of a conductive component containing metal powder filled in through-holes arranged in the insulation layers 1a-1c to make connections between the wiring circuit layers 2, where a recess 4 having a depth of 0.2-0.5 times the thickness of the wiring circuit layers and a size of 0.7-1.6 times the diameter of the via-hole conductors 3 is provided at each part of the wiring circuit layers 2, that is connected to each via-hole conductor 3, on the side where the wiring circuit layers 2 are embedded in the insulation layers 1a-1c.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to, for example, a multilayer wiring board used for a wiring board and a package for housing a semiconductor element, and a method for manufacturing the same.

[0002]

2. Description of the Related Art In recent years, so-called printed boards, in which a wiring circuit layer is formed on the surface of an insulating substrate containing a thermosetting resin such as epoxy resin or phenol resin, have been applied to a circuit board or a package mounted with a semiconductor element. There is. In such a printed wiring board, as a method of forming a wiring circuit layer on the surface of the insulating layer, a method of forming a wiring circuit layer by adhering a copper foil to the surface of the insulating substrate and then etching the copper foil, or A method of transferring a copper foil formed on a wiring circuit to an insulating substrate, a method of forming a circuit on the surface of the insulating substrate by a metal plating method, and the like are used.

With the increase in the number of wiring layers, wiring circuit layers between different layers are electrically connected by via-hole conductors. This via-hole conductor is generally formed by forming a through hole at a predetermined location on the wiring board with a drill or the like and then plating the inner wall of the through hole.

However, in the above method, the processing chemicals involved in the chemical plating process are expensive, and the processing time is long, so that productivity and economic efficiency are difficult. Further, when a multilayer wiring board is manufactured, it is technically difficult to form the via-hole conductor between arbitrary layers in the multilayer structure, so that there is a problem that the density of the wiring circuit layer cannot be improved.

To cope with such a problem, recently, a low-viscosity conductor paste or the like in which copper powder, an organic binder such as a liquid epoxy resin, and a curing agent are mixed is used to fill the through hole. Japanese Patent No. 2603053, Japanese Patent No. 258
7596, JP-A-8-204342, JP-A-8-1
It is proposed in Japanese Patent Laid-Open No. 91184 and Japanese Patent Laid-Open No. 8-191184.

[0006]

However, since the via-hole conductor filled with the conductor paste containing the metal powder is electrically connected by the contact between the powders, the via-hole conductor is compared with the via-hole conductor by plating. There is a problem that the resistance of is high. To solve this problem, attempts have been made to increase the filling rate of the metal powder filling the through holes formed in the insulating layer. For example, after filling a through hole with a conductor paste, a via circuit conductor made of a metal foil is pressed against the via hole conductor to densify the via hole conductor.

However, as shown in FIG.
When the wiring circuit layer 33 is pressed against the via-hole conductor 32 formed in the above, in the upper part of the via-hole conductor 32,
The conductor paste 34 in the via-hole conductor 32 seeps into the gap between the insulating layer 31 and the wiring circuit layer 33, and the conductor paste 3
4 diffuses around the via-hole conductor 32, and as a result, the adhesion of the wiring circuit layer 33 to the insulating layer 31 is impaired. Therefore, for example, the wiring circuit layer 33
However, there is a problem that when the wiring circuit layer 33 is formed by transfer, a transfer failure of the wiring circuit layer 33 occurs or the resistance between the wiring circuit layer 33 and the via-hole conductor 32 changes in terms of durability.

When the amount of the conductor paste is increased in order to increase the density of the via-hole conductors 32, a bulge portion 35 is formed on the surface on the opposite side of the wiring circuit layer 33, and the flatness of the surface of the wiring circuit layer 33 is formed. In addition, there is a problem that the flatness of the wiring board is impaired.

The present invention prevents the conductor paste in the via-hole conductor from seeping out to the periphery of the via-hole conductor, does not cause poor adhesion of the wiring circuit layer to the insulating layer, and further flattens the wiring substrate after transfer. It is an object of the present invention to provide a multi-layer wiring board having a high degree and a manufacturing method thereof.

[0010]

According to the present invention, with respect to a via-hole conductor formed by filling a through-hole formed in an insulating layer with a conductor paste, a wiring circuit layer side connected to the via-hole conductor is formed. By providing a recess in the via hole conductor, it is possible to effectively prevent the conductor paste from leaching out of the via hole conductor, thereby preventing poor adhesion of the wiring circuit layer near the formation of the via hole conductor and connecting the wiring circuit layer and the via hole conductor. It was found that the reliability can be increased.

That is, the multilayer wiring board of the present invention has an insulating layer containing at least a thermosetting resin, a wiring circuit layer formed on the surface of the insulating layer, and the insulating layer for connecting the wiring circuit layers. In a multilayer wiring board having a through-hole provided with a via-hole conductor filled with a conductor component containing metal powder, a recess is provided in a portion of the wiring circuit layer connected to the via-hole conductor. It is a thing.

The depth of the recess is 0.2 to 0.5 of the thickness of the wiring circuit layer, and the size of the recess is 0.7 to 1.6 times the diameter of the via-hole conductor. It is desirable that the effect of suppressing the seepage of the conductor component due to the depression is exhibited.

According to the method for manufacturing a multilayer wiring board of the present invention, a step of forming a metal layer on the surface of the film base material by adhesion, processing the metal layer to form a wiring circuit layer, and the wiring circuit. A step of forming a depression in a predetermined portion of the layer, a step of forming a through hole in a semi-cured insulating layer containing at least a thermosetting resin, and filling a conductor component in the through hole to form a via-hole conductor; , The film base material on which the wiring circuit layer having the recess is formed is laminated so that the via-hole conductor of the insulating layer and the recess are aligned, and after thermocompression bonding, the film base material is peeled off to form the wiring circuit. The method is characterized by comprising a step of transferring and embedding a layer on the surface of an insulating layer and a step of laminating and integrating a plurality of insulating layers in which the wiring circuit layer is embedded.

As another manufacturing method, a step of adhesively forming a metal layer on the surface of the film base material, processing the metal layer to form a wiring circuit layer, and a depression at a predetermined position of the wiring circuit layer. A step of forming a first wiring circuit layer on the surface of a semi-cured first insulating layer containing at least a thermosetting resin, and a step of forming the first wiring circuit layer. A step of laminating a semi-cured second insulating layer containing at least an organic resin on the surface of the first insulating layer, forming a through hole in the second insulating layer, and filling the through hole with a conductor component; A step of forming a via-hole conductor, a film substrate on which the wiring circuit layer having the depression is formed, are laminated so that the depression and the via-hole conductor of the insulating layer are aligned, and after thermocompression bonding,
A step of transferring and embedding the wiring circuit layer on the surface of the insulating layer by peeling off the film base material.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION A schematic cross-sectional view of an example of a multilayer wiring board according to the present invention is shown below in FIG.

In the multilayer wiring board of the present invention, a laminated body of a plurality of insulating layers 1a-1c containing at least a thermosetting resin is used as an insulating substrate 1, and a metal foil is formed on the front surface, the back surface and the inside of the insulating substrate 1. The wiring circuit layer 2 is formed. Via-hole conductors 3 are formed in each insulating layer in order to connect the front and back surfaces of the insulating substrate 1 and the plurality of wiring circuit layers 2 provided inside. The via-hole conductor 3 is formed by filling the through-holes formed in the insulating layers 1a to 1c with a conductor component containing metal powder.

Further, it is effective that the cross section of the wiring circuit layer 2 in the multilayer wiring board of the present invention has an inverted trapezoidal shape as shown in FIG. 2 in terms of adhesion to the insulating layer 1 and embedding property. In particular, the formation angle θ in the inverted trapezoidal shape is 30 to 80 °
Is desirable. As described above, according to the multilayer wiring board of the present invention, each of the wiring circuit layers 2 includes the insulating layers 1a to 1a.
Since it is embedded in the surface of c, the stacking failure due to the thickness of the wiring circuit layer 2 itself does not occur, and the insulating layer 1
It is possible to realize excellent adhesion between a to 1c and very excellent flatness of the wiring board as a whole.

Further, according to the present invention, as shown in FIG. 2, a recess 4 is provided in a portion of the wiring circuit layer 2 which is connected to the via hole conductor 3 on the side buried in the insulating layers 1a to 1c. is important. By forming the depression 4, the connection reliability between the wiring circuit layer 2 and the via-hole conductor 3 is increased,
Further, it is possible to prevent the adhesion failure around the via-hole conductor 3 of the wiring circuit layer 2.

If the recess 4 is too shallow, the effect of forming the recess is small. On the contrary, if the recess 4 is too deep, the wiring circuit layer 2 is not formed.
There is a fear that the strength of the wiring / circuit layer may be reduced due to the decrease in the thickness. From this point of view, it is appropriate that the depth d of the depression is 0.2 to 0.5 times, especially 0.25 to 0.4 times the thickness t of the wiring circuit layer 2.

When the dimples d are less than 0.2 times the thickness t of the wiring circuit layer 2, the effect of forming the dimples 4 is not remarkable, and the conductor paste is scattered around the via-hole conductors and the wiring circuit layer 2 and the periphery of the via-hole conductors. Poor adhesion tends to occur at the part. Further, if the depth of the depression is deeper than 0.5, the via-hole conductor becomes difficult to be compressed sufficiently, so that the filling property of the via-hole conductor is deteriorated, the resistance of the via-hole conductor is increased, and the reliability is deteriorated. is there.

Further, the size W ₁ of the recess 4 is 0.7 to 1.6 times the diameter W ₂ of the via-hole conductor 3, and particularly 0.
It is suitable to be 9 to 1.2 times in order to exert the effect of the present invention.

Further, the insulating layers 1a to 1c of the wiring circuit layer 2 are provided.
The ten-point average roughness (Rz) of the interface in contact with
The roughening to m can improve the adhesion to the insulating layers 1a to 1c.

In the multilayer wiring board of the present invention, the insulating layers 1a to 1c are made of an insulating material containing at least a thermosetting resin, such as PPE (thermosetting polyphenylene ether resin) and BT resin ( (Bismaleide triazine), a polyimide resin, a fluororesin, a polyamino bismaleimide resin, and an epoxy resin, and it is particularly preferable that the material is a thermosetting resin that is liquid at room temperature.

As the insulating material, the strength of the insulating substrate can be increased by uniformly dispersing the filler component in the proportion of 20 to 80% by volume together with the thermosetting resin. Examples of the filler component include organic or inorganic powders or fibrous bodies.

As the inorganic filler, SiO ₂ ,
Al ₂ O ₃ , ZrO ₂ , TiO ₂ , AlN, SiC, BaT
iO ₃ , SrTiO ₃ , MgTiO ₃ , zeolite, Ca
Known materials such as TiO ₃ and aluminum borate can be used. Further, the shape thereof may be any shape such as a spherical shape or a needle shape. Further, as the fibrous body, there is a fibrous body such as glass, and a woven fabric, a non-woven fabric or the like having an arbitrary property may be used. Further, as the organic filler,
Examples include aramid fiber and cellulose fiber.

Further, the wiring circuit layer 2 is formed of a metal suitable for forming wiring, for example, gold, silver,
A metal foil of a low resistance metal containing at least one of copper and aluminum is preferably used. The thickness of this metal foil is 1-3
5 μm is preferable, and 5 to 18 μm is preferable. The thickness of this metal foil, in other words, the thickness of the wiring circuit layer 2 is 1 μm.
If it is smaller, the resistivity of the wiring becomes higher, and if it is larger than 35 μm, it becomes impossible to form a fine wiring of 50 μm or less by etching. In addition, there is a problem that the deformation of the insulating substrate becomes large at the time of stacking, the amount of metal embedded in the insulating substrate increases, the strain of the insulating substrate becomes large, and the substrate is easily deformed after the resin is cured.

Further, as the conductor paste to be filled in the via hole, a metal powder forming the wiring circuit layer to which a resin component such as epoxy or cellulose is added and kneaded with a solvent such as butyl acetate is used. The conductor paste is dried after the solvent is filled into the via holes, but it is desirable that the conductor paste is solvent-free from the beginning. Further, in order to reduce the resistance of the via-hole conductor, the metal powder may contain a low melting point metal containing at least lead or tin.

Next, a method of manufacturing the multilayer wiring board of the present invention will be described with reference to FIG. (A) First, desired through holes 11 are formed in the insulating sheet 10 by a punching method or laser processing.

The insulating sheet 10 is produced by the following method, for example, when a composite material of a thermosetting resin and an inorganic filler is used as the insulating material. First, a kneader (kneader) is added to a suitable inorganic filler as described above, in which the liquid thermosetting resin described above is added together with a solvent so that the amount of the inorganic filler is 20 to 80% by volume.
And an insulating slurry are prepared by mixing by means such as a three-roll mill.

The insulating slurry is preferably a composite material of the above-mentioned organic resin and inorganic filler, toluene,
A fluid having a predetermined viscosity is obtained by adding a solvent such as butyl acetate, methyl ethyl ketone, methanol, methyl cellosolve acetate, isopropyl alcohol, methyl isobutyl ketone, and dimethylformamide. The viscosity of the slurry is preferably 100 to 3000 poise, although it depends on the sheet forming method.

Then, after the mixture is formed into a sheet by a sheet forming method such as a rolling method, an extrusion method, an injection method, a doctor blade method or the like, if desired, the temperature is slightly higher than a temperature sufficient to completely cure the thermosetting resin. The insulating sheet 10 can be manufactured by heating to a low temperature and semi-curing the thermosetting resin. (B) Then, the via hole conductor 12 is formed by filling the through hole 11 with a conductor paste containing a metal powder. The conductor paste filled in the through holes 11 is gold, silver,
A conductor paste prepared by mixing a metal powder containing at least one selected from copper, aluminum and the like with a binder and the like is preferably used. It is desirable to use a non-volatile binder that reacts with the insulating resin. Further, as a method of filling the conductor component, a normal pressure printing machine or the like can be used, but a vacuum printing machine can further increase the filling rate. (C) Next, the wiring circuit layer 14 made of metal foil is formed on both ends of the via-hole conductor 12 of the semi-cured insulating sheet 10. In the present invention, the wiring circuit layer 14 is formed by the transfer method.

According to this transfer method, first, one or more kinds selected from copper, gold, silver, aluminum and the like prepared on the surface of the film base material 13 made of resin or metal by a plating method or the like. Alloy thickness: 1-35 μm
After the mirror surface side of the metal foil is adhered and a resist layer is attached to the surface of the metal foil so as to form a mirror image pattern of a desired wiring pattern, the wiring circuit layer 14 having a mirror image of a predetermined wiring pattern is formed by etching and resist removal. To form. The wiring circuit layer 14 at this time preferably has an inverted trapezoidal cross section as shown in FIG. 2 as described above.
Such an inverted trapezoidal shape has a metal foil etching rate of 2 to 50 μm, for example, using ferric chloride, cupric chloride or the like.
It can be easily formed by setting m / min. (D) After that, a recess 15 is formed in the wiring circuit layer 14 formed on the surface of the film base material 13 at a position connected to the via-hole conductor 12 formed in the insulating sheet 10. The recess 15 is, for example, a microdrill,
Although it can be formed by laser light irradiation, etching treatment, etc., the accuracy of forming the depressions 15, fine workability,
Irradiation with laser light is desirable from the viewpoint of stoolability.

For the reason described above, the depth of the recess 15 is 0.2 to 0.5 of the thickness of the wiring circuit layer 14.
Double, especially 0.25 to 0.4 times, and also the depression 1
The size (diameter) of 5 is 0.7 to the diameter of the via-hole conductor.
It is desirable to form so as to be 1.6 times, especially 0.9 to 1.2 times.

Further, it is desirable that the wiring circuit layer 14 formed on the surface of the film substrate 13 is roughened so that the ten-point average roughness (Rz) is 2 μm or more, and particularly 3 μm or more. .

As the film substrate 13, polyethylene terephthalate, polyethylene naphthalate, polyimide, polyphenylene sulfide, vinyl chloride,
Resin such as polypropylene, metal such as stainless steel,
Known ones can be used. Film thickness is 10-10
0 μm is suitable, and preferably 25 to 50 μm. This is because if the thickness of the film is less than 10 μm, the conductor wiring formed by deformation or bending of the film is likely to cause disconnection, and if the thickness is more than 100 μm, the flexibility of the film is lost and peeling of the sheet becomes difficult. . Further, as the adhesive for adhering the metal foil to the surface of the film substrate 13, known adhesives such as acrylic, rubber, silicon and epoxy can be used. (E) Next, the film base material 13 having the wiring circuit layer 14 having the depression 15 produced as described above is laminated on the surface of the insulating sheet 10 on which the via-hole conductor 12 is formed. At that time, the via-hole conductor 12 and the recess 15 are aligned and stacked so as to be aligned with each other. (F) And 10-500 kg / c of the laminate
After heating under pressure at m ² of 60 to 0.20 ° C. and peeling off the film base material 13, a wiring sheet in which the wiring circuit layer 14 is embedded in the surface of the insulating sheet 10 can be produced.

At this time, the via-hole conductor 12 is normally pressed by the wiring circuit layer 14 so that the conductor paste leaches and spreads to the peripheral portion of the via-hole conductor 12, but it is formed on the wiring circuit layer 14 according to the present invention. The hollow 15 can suppress the seeping and spreading. Further, since the pressure at the time of transfer is applied toward the center of the via-hole conductor 12, the densification of the via-hole conductor 12 can be improved.

When forming this wiring sheet,
When the film base material 13 having the wiring circuit layers 14 formed on both surfaces of the insulating sheet 10 is laminated and pressure-bonded, a wiring sheet having the wiring circuit layers 14 formed on both surfaces can be formed. (G) After the wiring sheet a produced as described above is laminated and integrated with the wiring sheets b and c produced in the same manner, these are brought to a temperature at which the thermosetting resin in the insulating sheet is completely cured. By heating, the multilayer wiring board of the present invention can be manufactured.

Another method of manufacturing the multilayer wiring board of the present invention will be described with reference to the process chart of FIG. (A) First, an insulating sheet 21 containing an uncured or semi-cured thermosetting resin is prepared as a first insulating layer, and a wiring circuit layer 22 is formed on the surface of the insulating sheet 21.
When forming the wiring circuit layer 22, it is desirable to use a transfer method. Specifically, after adhering a metal foil to the surface of an appropriate film base in advance, a mirror image pattern of the wiring circuit layer 22 is formed by a well-known photoresist method or the like, and this is applied to the first insulating sheet 21. After laminating and pressure bonding, the wiring circuit layer 22 is transferred to the surface of the insulating sheet 21 by peeling off the film base material, and the wiring circuit layer 22 is embedded in the surface of the insulating sheet 21 as shown in FIG. 4A. You can (B) Next, the uncured or semi-cured insulating sheet 23 is laminated on the surface of the first insulating sheet 21 on which the first wiring circuit layer 22 is formed. (C) Thereafter, a through hole reaching the first wiring circuit layer 22 is formed in the insulating sheet 23, and a conductor component is filled in the through hole to form the via hole conductor 24.
In order to form the through hole, it is desirable to form the through hole by any one of laser light selected from the group consisting of CO ₂ , YAG, and excimer laser. This is because a fine through hole can be formed as compared with a commonly used micro drill.

The conductor component filled in the through hole is
At least one selected from gold, silver, copper, aluminum, etc.
A conductor paste prepared by mixing a metal powder containing at least one kind and a binder is preferably used. It is desirable to use a non-volatile binder that reacts with the insulating resin. Further, as a method of filling the conductor component, a normal pressure printing machine or the like can be used, but a vacuum printing machine can further increase the filling rate. (D) On the other hand, according to the same method as described in (a) above, a metal foil is adhered to the surface of a suitable film substrate 26, and then a mirror image of the wiring circuit layer 27 is formed by a known photoresist method. Form a pattern. Then, in the wiring circuit layer 27 formed on the surface of the film base material 26, a recess 28 is formed at a position connected to the via-hole conductor 24 formed in the insulating sheet 23. This hollow 28
Can be formed by, for example, a microdrill, laser light irradiation, etching treatment, or the like.
Irradiation with a laser beam is desirable from the viewpoints of the precision of forming No. 8, fine processability, and stoolability.

For this reason, the depth of the recess 28 is 0.2 to 0.5 of the thickness of the wiring circuit layer 27.
Double, especially 0.25 to 0.4 times, and the recess 2
The size (diameter) of 8 is 0.8 mm of the diameter of the via-hole conductor 24.
It is desirable to form it so that it is 7 to 1.6 times, and particularly 0.9 to 1.2 times. Further, in order to form the recess 28 having a thickness of 0.2 or more in the wiring circuit layer made of this metal foil, the laser condition is 0.1 to ² mJ / cm ² , and 1 to 3 Shot.
Just irradiate.

The wiring circuit layer 27 formed on the surface of the film substrate 26 is preferably roughened so that the ten-point average roughness (Rz) is 2 μm or more, particularly 3 μm or more. . (E) Next, the film base material 26 having the wiring circuit layer 27 having the depression 28 manufactured as described above is laminated on the surface of the insulating sheet 26 on which the via-hole conductor 24 is formed. At that time, the via-hole conductor 24 and the recess 28 are aligned and stacked so as to be aligned with each other. (F) And 10-500 kg / c of the laminate
The wiring circuit layer 27 can be embedded in the surface of the insulating sheet 23 by peeling off the film base material 26 after heating under pressure at m ² of 60 to 0.20 ° C. and is formed on the surface of the insulating sheet 21. It is possible to form a laminated body in which the wiring circuit layer 22 and the wiring circuit layer 27 formed on the surface of the insulating sheet 23 are electrically connected by the via hole conductor 24. (G) Further, in the case of aiming for a multilayer structure, the above (b) to
By repeating the step (f), an arbitrary number of layers can be formed.

The multilayered insulating sheet as described above can be completely cured by performing heat treatment after each step (f), but in order to simplify the steps, It is desirable to finally carry out a hardening treatment collectively on the multi-layered one.

In the above description of the second manufacturing method, the first insulating sheet 21 having the wiring circuit layer 22 is
Although the wiring circuit layer 22 is formed by the transfer method, the insulating sheet 21 is formed by etching a commercially available glass fiber impregnated with resin, that is, a so-called prepreg having a metal foil bonded to the surface thereof. The metal foil may be processed into a circuit pattern by a method.

As described above, according to the present invention, the contact area between the via-hole conductor and the wiring circuit layer is increased by coupling the via-hole conductor and the wiring circuit layer by the recess formed on the wiring circuit layer side. Since the via-hole conductor is bonded to the wiring circuit layer like an anchor, the bondability between the via-hole conductor and the wiring circuit layer is enhanced, and the connection resistance increases even when a heat cycle is applied. High reliability can be obtained without causing In addition, since the conductor paste does not seep around the via-hole conductor, the wiring circuit layer has high adhesion to the insulating layer, and as a result, the connection reliability between the wiring circuit layer and the via-hole conductor can be improved. it can.

[0045]

EXAMPLE An adhesive made of an acrylic resin is applied to the surface of a resin film made of polyethylene terephthalate (PET) so as to have an adhesive force, and the surface roughness of the thickness is 0.8 μm.
m copper foil was adhered to one surface. Then, a wiring circuit layer having a mirror image pattern of a desired circuit was formed on the copper foil by resist and etching. Then, a recess having a size as shown in Table 1 was formed by a CO ₂ laser in the connection portion of the wiring circuit layer with the via-hole conductor.

On the other hand, as the insulating slurry, thermosetting polyphenylene ether was mixed as the organic resin, and spherical silica was mixed as the inorganic filler in a volume ratio of 60:40. Toluene was added and mixed by heating at 80 ° C. to obtain the viscosity. 10
A 0 poise slurry was prepared.

An insulating sheet was prepared by molding the insulating slurry into a thickness of about 100 μm by the doctor blade method, and a through hole having a diameter of 100 μm on the incident side was formed by a CO ₂ laser. Then, a copper paste containing Cu—Ag alloy powder having an average particle size of 5 μm was filled in the through hole.

Then, the two PET films having the wiring circuit layer having the dents formed thereon are aligned and laminated from both sides of the insulating sheet, and are laminated by a vacuum laminating machine at 0.50 ° C. for 3 days.
After pressing with a pressure of 0 kg / cm ² for 2 minutes, the PET film was peeled off to transfer the wiring circuit layer to both surfaces of the insulating sheet.

Then, after laminating a plurality of insulating sheets having wiring circuit layers formed as described above, 200
The insulating sheet was completely cured by heating at 5 ° C. for 5 hours to produce a wiring board having a multilayer structure.

With respect to the obtained multilayer wiring board, the initial resistance value and the resistance value after being left for 1000 hours in a high temperature atmosphere of 0.20 ° C. were measured, and the resistance change rate (%) (= (left Post resistance value-initial resistance value) / initial resistance value) x 100) was calculated and shown in Table 1.

Further, the cross section of the portion including the connection portion between the via-hole conductor and the wiring circuit layer was observed with a scanning electron microscope, and the maximum immersion of the conductor paste from the end portion of the connection portion of the via-hole conductor with the wiring circuit layer was observed. The projecting width was measured and is shown in Table 1.

Further, the flatness of the surface of the wiring circuit layer in the vicinity of the formation of the via-hole conductor in the wiring board was measured using a stylus type surface roughness meter, and is shown in Table 1.

[0053]

[Table 1]

As shown in Table 1, when the depression was not formed, the conductor paste was observed to seep around the via-hole conductor, and as a result, the resistivity was high. . When the dent is 0.2 or more, the resistance change rate is small, and when the dent is 0.5 or more, a gap is formed between the conductor paste and the metal layer and the connection is rather deteriorated, resulting in an increase in resistance and disconnection (open). It was

On the other hand, by forming the depression, the leaching width is 30 μm or less, the resistance change rate is 20% or less,
It showed good characteristics with a flatness of 10 μm or less. In particular, by setting the depth of the depression to be 0.2 to 0.5 times the thickness of the wiring circuit layer and the size to be 0.7 to 1.6 times the diameter of the via-hole conductor, the leaching width is 25 μm or less, Resistance change rate 10%
Hereinafter, even better characteristics with a flatness of 7 μm or less were shown.

[0056]

As described above in detail, according to the present invention, the conductor paste in the via-hole conductor is suppressed from seeping out to the periphery of the via-hole conductor at the connection portion between the via-hole conductor and the wiring circuit layer. It is possible to suppress the occurrence of defective transfer of the wiring circuit layer in the vicinity of the via-hole conductor, improve the connection reliability, and manufacture a multilayer wiring board having high flatness.

[Brief description of drawings]

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

FIG. 2 is an enlarged cross-sectional view of a main part of a multilayer wiring board according to the present invention.

FIG. 3 is a schematic cross-sectional view for explaining an example of the method for manufacturing a multilayer wiring board according to the present invention.

FIG. 4 is a schematic cross-sectional view for explaining another example of the method for manufacturing a multilayer wiring board of the present invention.

FIG. 5 is an enlarged cross-sectional view of a connection portion between a wiring circuit layer and a via-hole conductor in a conventional multilayer wiring board.

[Explanation of symbols]

1 Insulation board 1a-1c insulating layer 2 wiring circuit layers 3 Via hole conductor 4 depressions

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 5E343 AA02 AA17 AA18 AA19 BB02                       BB23 BB24 BB25 BB28 BB67                       DD56 EE32 EE33 EE37 ER18                       ER52 GG20                 5E346 AA15 AA32 AA43 CC02 CC09                       CC10 CC14 CC32 CC34 CC38                       CC39 CC55 CC58 DD12 DD32                       DD44 EE04 FF18 GG15 GG22                       GG23 GG27 GG28 HH07 HH21

Claims (7)

[Claims] 1. An insulating layer containing at least a thermosetting resin,
A multilayer including a wiring circuit layer buried in the surface of the insulating layer and a via hole conductor obtained by filling a through hole provided in the insulating layer for connecting the wiring circuit layers with a conductor component containing a metal powder. In the wiring board, a recess is provided in a portion connected to the via-hole conductor on a side of the wiring circuit layer which is embedded in the insulating layer, and a multi-layer wiring board. 2. The depth of the recess is 0.2 of the thickness of the wiring circuit layer.
The multilayer wiring board according to claim 1, wherein: 3. The multilayer wiring board according to claim 1, wherein the size of the recess is 0.7 to 1.6 times the diameter of the via-hole conductor. 4. A step of adhesively forming a metal layer on the surface of a film base material, processing the metal layer to form a wiring circuit layer,
A step of forming a recess at a predetermined position of the wiring circuit layer, and forming a through hole in a semi-cured insulating layer containing at least a thermosetting resin, and filling a conductor component in the through hole to form a via hole conductor. And the film substrate on which the wiring circuit layer having the recess is formed, are laminated so that the via hole conductor of the insulating layer and the recess are aligned, and after thermocompression bonding,
A step of transferring and embedding the wiring circuit layer on the surface of the insulating layer by peeling off the film base material, and a step of laminating and integrating a plurality of insulating layers having the wiring circuit layer embedded therein. A method for manufacturing a characteristic multilayer wiring board. 5. A step of adhesively forming a metal layer on the surface of a film base material, processing the metal layer to form a wiring circuit layer,
A step of forming a depression at a predetermined location of the wiring circuit layer; a step of depositing and forming a first wiring circuit layer on a surface of the first insulating layer in a semi-cured state containing at least a thermosetting resin; Stacking a semi-cured second insulating layer containing at least an organic resin on the surface of the first insulating layer on which the first wiring circuit layer is formed; forming a through hole in the second insulating layer; A step of filling a through hole with a conductor component to form a via-hole conductor, and a film substrate on which the wiring circuit layer having the depression is formed are laminated so that the depression and the via-hole conductor of the insulating layer are aligned and heated. After the pressure bonding, the step of transferring and embedding the wiring circuit layer on the surface of the insulating layer by peeling off the film base material is included. 6. The depth of the depression is 0.2 to the thickness of the metal layer.
It is 0.5, Claim 4 or Claim 5 characterized by the above-mentioned.
A method for manufacturing the multilayer wiring board described. 7. The manufacture of a multilayer wiring board according to claim 4, wherein the size of the recess is 0.7 to 1.6 times the diameter of the via-hole conductor. Method.