JP2002290053A - Multilayer wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the increase in capacitance of a built-in capacitor due to simultaneous baking by adjusting the material composition of a high dielectric layer and low dielectric layer. SOLUTION: In a multilayer wiring board in which a conductive wiring layer 2 is arranged on the surface of the inside of a ceramic insulating substrate 1 which is a laminate of a high dielectric layer 1b and low dielectric layers 1a and 1c, the layer 1b contains CaTiO3 and the amount of Ca in the layers 1a and 1c is set at 20% or more of the total amount of Ca in the layer 1b. By the way, both layers 1a and 1c are preferably made of sintered bodies obtained by adding an inorganic filler to an SiO2 -BaO-CaO-Al2 O3 -B2 O3 based glass and sintering the resulting bodies.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer wiring board having a high dielectric constant layer and a low dielectric constant layer,
More specifically, the present invention relates to a multilayer wiring board that allows a high dielectric layer to function as a capacitor.

[0002]

2. Description of the Related Art Conventionally, a multilayer wiring board has a structure in which a conductor wiring layer is disposed on the surface or inside of an insulating substrate in which insulating layers are stacked in multiple layers. Package. As such a package, a package in which an insulating layer is made of a ceramic such as alumina has been widely used, but recently, a package in which a glass ceramic sintered body capable of being co-fired with copper metallization is used as an insulating substrate. Has been put to practical use.

On the other hand, with the rapid spread of portable information terminals such as mobile phones and notebook personal computers, there is a strong demand for miniaturization of built-in electronic components. As an example, a switching circuit and a power amplifier circuit of a mobile phone are configured by a plurality of resistors and capacitors, and conventionally, these elements are individually installed on an electric circuit board, so that miniaturization,
And reduction of manufacturing costs. For this reason, a multilayer wiring board has recently been proposed in which a capacitor is formed by arranging opposing electrodes above and below an insulating layer. At that time, it has been proposed to form a high-capacity capacitor by forming an insulating layer between the electrode layers with an insulating layer having a high dielectric constant.

[0004]

However, the multilayer wiring board with a built-in capacitor has not been put into practical use because the capacitance accuracy of the capacitor built in the multilayer wiring board is inferior to that of the mounted capacitor chip. Factors of the capacity variation of the built-in capacitor include a dimensional variation of the electrode layer, a thickness variation of the high dielectric constant layer, and a decrease in the dielectric constant of the high dielectric constant layer due to simultaneous firing with the low dielectric constant layer.
Among them, the dimensional variation of the electrodes is due to the printing accuracy of the electrode layer,
The effect of mechanical accuracy such as lamination accuracy is large, and the thickness variation of the high dielectric constant layer depends on the mechanical accuracy of green sheet molding. Since the decrease in the dielectric constant is caused by co-firing with the low dielectric constant layer, it is caused by the material composition and cannot be eliminated without controlling the material composition.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a multilayer wiring board capable of preventing a reduction in the capacity of a built-in capacitor due to simultaneous firing by adjusting the material composition of the high dielectric constant layer and the low dielectric constant layer. Is what you do.

[0006]

Means for Solving the Problems The present inventors have made various studies on the above-mentioned problems, and as a result, for example, a glass ceramic obtained by mixing, molding, and firing a glass component and an inorganic filler component. , When a high dielectric constant layer and a low dielectric constant layer are formed,
It has been found that the above object can be achieved by containing aTiO ₃ and Ca in the low dielectric constant layer at a predetermined ratio.

That is, the multilayer wiring board of the present invention is a multilayer wiring board having a conductor wiring layer disposed on or inside a ceramic insulating substrate having a high dielectric constant layer and a low dielectric constant layer laminated thereon. The dielectric layer contains CaTiO ₃ , the low dielectric layer also contains Ca, and the C contained in the low dielectric layer is
When the amount of a is not less than 20% of the total amount of Ca contained in the high dielectric constant layer, diffusion of the Ca component from the high dielectric constant layer to the low dielectric constant layer in simultaneous firing can be prevented, Variations in the composition of the rate layer can be suppressed.

The high dielectric constant layer and the low dielectric constant layer are formed of Si
It is desirable to use a sintered body obtained by adding an inorganic filler to an O ₂ —BaO—CaO—Al ₂ O ₃ —B ₂ O ₃ -based glass and firing it. By providing the pair of electrode layers, the high dielectric constant layer can function as a capacitor, and a desired capacitance can be obtained.

In order to simultaneously sinter the high dielectric layer and the low dielectric layer, it is necessary to match both thermal expansion coefficients.
More specifically, it is necessary to reduce the difference in the coefficient of thermal expansion, and the glass ceramic can easily control the coefficient of thermal expansion. That is, as the inorganic filler of the low dielectric constant layer, for example, quartz having a high coefficient of thermal expansion and forsterite having a low coefficient of thermal expansion are used, and the coefficient of thermal expansion is adjusted to that of the high dielectric constant layer by adjusting the ratio. Is possible. This not only enables simultaneous firing of the low-k layer and the high-k layer, but also suppresses the generation of thermal stress due to the difference in thermal expansion even when a thermal cycle is applied during use. , High long-term reliability is obtained.

According to the present invention, by using a high dielectric constant layer having an arbitrary dielectric constant and a low dielectric constant layer which can be fired simultaneously with the high dielectric constant layer, a capacitor having a capacitance as designed is built in. It becomes possible to create a multilayer wiring board.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. 1, a multilayer wiring board according to the present invention comprises a ceramic insulating substrate 1 having ceramic insulating layers 1a, 1b and 1c laminated in multiple layers on the surface and / or inside thereof. 2, at least one of the ceramic insulating layers 1b is a high dielectric constant layer made of a ceramic sintered body having a high dielectric constant, and the insulating layers 1a and 1c are formed by low dielectric constant layers. Cu above and below the rate layer 1b
By forming the electrode layers 3 and 3 made of a conductor such as, for example, and connecting with the conductor wiring layer 2 on the substrate surface via the through-hole conductors 4 and 4, etc., a predetermined capacitance between the wiring layers 2 and 2 is obtained. Can be taken out.

In the multilayer wiring board of the present invention, each of the high dielectric constant layer 1b and the low dielectric constant layers 1a and 1c is formed of a sintered body obtained by molding and firing a mixture of a glass component and an inorganic filler component. This is desirable from the viewpoint of easy control of characteristics such as sinterability, dielectric constant, and coefficient of thermal expansion of the high dielectric constant layer and the low dielectric constant layer.

As the glass component, SiO ₂ —BaO—
It is preferable to use a glass composed of CaO—Al ₂ O ₃ —B ₂ O ₃ , containing 5% by weight or more of CaO, an amorphous glass,
Or oxide-based crystal containing Ca after firing, specifically _{CaO · 2SiO 2, CaAl 2 Si} 2 O 8, CaB 2 S
Crystallized glass that precipitates a crystal phase such as i ₂ O ₈ is employed. In particular, as a glass composition, SiO ₂
60 wt%, 2-18 wt% of CaO, Al ₂ O ₃ 4~1
0 wt%, BaO20~27 wt%, B ₂ O ₃ 11~15
% By weight, and more desirably the Zr compound
By containing 0.1 to 30% by weight in terms of rO ₂ , chemical resistance can be improved.

Further, the sag point of the above glass is 400-400.
The temperature is desirably 800 ° C, particularly 400 to 700 ° C. This is because when molding a mixture consisting of glass and an inorganic filler, a molding binder such as an organic resin is added. This binder is efficiently removed, and the metallization, which is fired simultaneously with the insulating substrate, and matching of firing conditions. Required to achieve a yield point of 400
If the temperature is lower than 0 ° C, the glass starts sintering at a low temperature.
This is because simultaneous firing with metallization at 0 ° C. cannot be performed, and densification of the molded article starts at a low temperature, so that the binder cannot be decomposed and volatilized, and the binder component remains, resulting in affecting the properties. On the other hand, if the yield point is higher than 800 ° C., sintering becomes difficult unless the amount of glass is increased,
The use of relatively expensive glass increases, which hinders cost reduction.

On the other hand, as the inorganic filler component to be mixed with the above-mentioned glass component, first, when a high dielectric constant layer is formed, sinterability with the glass component is good, and 1M
It is desirable that the relative dielectric constant at Hz is 13 or more, particularly 20 or more.

The filler used is not limited to this, but may be BaTiO ₃ (ε = 13000), C
aTiO ₃ (ε = 180), La ₂ Ti ₂ O ₇ (ε = 4
5), SrTiO ₃ (ε = 300), TiO ₂ (ε = 8)
0) and ZrO ₂ (ε = 30).

The above SiO ₂ —BaO—CaO—Al ₂ O
_The sinterability with the _3- B ₂ O ₃ glass is CaTiO ₃ , La ₂
At least one selected from the group consisting of Ti ₂ O ₇ and ZrO ₂ ;
In particular, it is desirable to include at least CaTiO ₃ .

The above glass component and filler component are:
Glass component: 30 to 70% by weight, filler component: 30
It is prepared at a ratio of ７０70% by weight. This is because when the glass component is less than 30% by weight and the filler component is more than 70% by weight, it is difficult to obtain a good dense body in a temperature range where co-firing with copper is possible, and the glass component is less than 70% by volume. If the content of the filler component is less than 30% by volume, it is difficult to increase the dielectric constant of the sintered body.

When the composition of glass and filler is adjusted in order to obtain the electrical characteristics of the high dielectric constant layer, the coefficient of thermal expansion of the obtained glass ceramic is inevitably determined. For this reason, in order to form a capacitor using such a high-permittivity glass ceramic as an inner layer, it is desirable to match the thermal expansion coefficient of the low-permittivity layer with that of the high-permittivity layer.

This is because the difference in the coefficient of thermal expansion of each layer is 1 × 10
If it is higher than ⁻⁶ / ° C., destruction occurs in a layer or between layers in the firing step, and the difference in thermal expansion coefficient of each layer is 0.5 to
In the case of 1 × 10 ⁻⁶ / ° C., simultaneous firing is possible,
Since cracks tend to occur locally in the layer or between layers, the difference in thermal expansion is desirably 0.5 × 10 ⁻⁶ / ° C. or less.

As the filler component in the low dielectric constant layer, quartz and / or forsterite is used, and by adjusting the component ratio of these fillers, it is possible to easily match the thermal expansion coefficient with the high dielectric constant layer. it can.

The above allows simultaneous firing of the high dielectric constant layer and the low dielectric constant layer. However, when the electrode layers are formed above and below the high dielectric constant layer using CaTiO ₃ as a filler to form a built-in capacitor, There is a tendency that the capacitance of the capacitor is lower than the design value.

As a result of various studies on this tendency,
This is because the composition of the high dielectric constant layer changes due to the diffusion of Ca of CaTiO ₃ in the high dielectric constant layer to the low dielectric constant layer side. It is very remarkable at 15% or less of the total amount of Ca in the medium, and in order to further prevent the diffusion, the amount of Ca in the low dielectric constant layer is set to 20% or more, particularly 30%, of the total amount of Ca in the high dielectric constant layer. % Is important.

As described above, in the high dielectric constant layer and the low dielectric constant layer,
To control the amount of Ca, use CaTiO _ThreeQuantity, and SiO_Two
-BaO-CaO-Al_TwoO_Three-B_TwoO_ThreeGlass content and
It is necessary to adjust the amount of CaO in the glass and glass.

In the method of manufacturing the multilayer wiring board of the present invention, first, for both the high dielectric constant layer and the low dielectric constant layer, an appropriate solvent for the mixture of the glass component and the filler component prepared at a predetermined ratio, and an organic solvent. After adding the resin binder,
A ceramic green sheet is formed by a conventionally known doctor blade method, lip coater method or the like. Next, as a conductor wiring layer, a metal paste obtained by adding and mixing an appropriate metal powder with an organic binder, a solvent, and a plasticizer is printed and applied in a predetermined pattern on the green sheet by a known screen printing method. In some cases, the green sheet is appropriately punched to form a through hole, and the hole is filled with a metallizing paste. After the above processing, the high-permittivity layer green sheet and the low-permittivity layer green sheet are laminated, and the green sheet laminate and metallization are simultaneously fired to obtain a multilayer wiring board with a built-in capacitor.

In firing the above-mentioned molded body, first,
The binder component blended for molding is removed. The binder is removed in an air atmosphere at about 700 ° C., but when, for example, Cu is used as the conductor for the wiring layer, the removal is performed in a nitrogen atmosphere containing water vapor at 100 to 750 ° C. At this time, the shrinkage start temperature of the molded body is 700 to
It is desirable to be about 850 ° C., and if the shrinkage onset temperature is lower than this, it is difficult to remove the binder. Becomes

The calcination is performed in an oxidizing atmosphere or a non-oxidizing atmosphere at 850 to 1050 ° C., whereby the relative density is increased to 90% or more. The firing temperature at this time is 8
If it is lower than 50 ° C., it cannot be densified, and
If it exceeds 300, the metallized layer will be melted by simultaneous firing with the conductor wiring layer. The glass-ceramic sintered body of the present invention has 8
Since it can be fired at a firing temperature of 50 to 1050 ° C., C
Simultaneous firing with a low-resistance metal such as u is possible. Where C
In the case of simultaneous firing using u as a wiring conductor, firing is performed in a non-oxidizing atmosphere.

[0028]

EXAMPLE 1 An evaluation example of a high dielectric constant material will be described. As glass powder,
SiO_Two: 43.9% by weight-BaO: 23.2% by weight-
CaO: 12.3% by weight-Al_TwoO_Three: 7% by weight-B
_TwoO_ThreeGlass and filler consisting of 13.6% by weight
As CaTiO _Three, La_TwoTi_TwoO₇, ZrO_TwoTable 1
Weigh and mix at the ratio shown in
After pulverizing and mixing using acrylic binder, plastic
Add materials and mix by weight to make a slurry,
A green sheet with a thickness of 300 μm is created by the blade method.
Made.

Five sheets of the obtained green sheet are brought into close contact with each other,
After preparing a sample of 50 mm x 50 mm and removing the binder in a nitrogen atmosphere containing water vapor at 700 ° C,
The firing was performed at 910 ° C. in a nitrogen atmosphere. Table 1 shows the Ca content in terms of CaO in the obtained sintered body, the relative dielectric constant at 3.2 GHz, and the coefficient of thermal expansion at 40 to 400 ° C.

[0030]

[Table 1]

Example 2 An evaluation example of a low dielectric constant material will be described. The composition of the glass powder is the same as that of the high dielectric constant material, SiO ₂ -BaO-CaO-A.
Although it is l ₂ O ₃ -B ₂ O ₃ system, by replacing CaO and BaO, the amount of Ca in the glass is set to the ratio shown in Table 2 in terms of CaO, and quartz and forsterite, and ZrO ₂ are used as fillers. Samples were weighed and prepared at the ratio shown in 2, and samples were prepared and evaluated in the same manner as for the high dielectric constant material. Ca amount in terms of CaO in the obtained sintered body alone, relative dielectric constant at 3.2 GHz, and 40 to
Table 2 also shows the thermal expansion coefficient at 400 ° C.

[0032]

[Table 2]

The results show that the thermal expansion in the range of 40 to 400
The coefficients are 8.8 to 9 × 10 ^-6/ ° C,
The difference between the coefficients of thermal expansion of all high dielectric materials shown in Table 1 is
0.5 × 10^-6/ ° C or lower, simultaneous in any combination
Baking is possible. Example 3 A high dielectric constant material shown in Table 1 and a low dielectric constant material shown in Table 2 were used.
PCB with built-in capacitor of capacitance 30pF
Is shown in Table 3.

Further, in this embodiment, a configuration was designed in which the capacitance was 30 pF by adjusting the electrode dimensions and the high dielectric constant layer thickness using the high dielectric constant materials shown in Table 1.

As a method of manufacturing a capacitor incorporated in a wiring board, first, a slurry is prepared for both the high dielectric constant layer and the low dielectric constant layer in the same manner as in Example 1, and a green sheet is formed. In addition, the thickness of the green sheet for the high dielectric constant layer has a predetermined value shown in Table 3 after firing,
The thickness for the low dielectric constant layer was 120 μm.

Next, through holes are formed in predetermined positions of the two green sheets for a low dielectric constant layer, and metallized paste is filled. Next, a metallized paste having a predetermined area serving as an electrode of a capacitor is printed on the green sheet for a low dielectric constant layer that has been subjected to such processing, and an adhesion liquid is applied to the same surface.

Next, the high-permittivity layer green sheet is sandwiched so that the electrode printed surfaces of the two processed low-permittivity layer green sheets are in contact with the high-permittivity layer green sheet. To wear.

Incidentally, the overlapping area of both electrodes is shown in Table 3 after firing.
Is designed to have the electrode dimensions of The obtained molded body is 12 mm × 12 mm at a position where the overlapping portion of the electrodes is at the center.
And fired.

The calcination was carried out at 700 ° C. in a nitrogen atmosphere containing water vapor, followed by debinding in a nitrogen atmosphere at 910 ° C.

Lead wires were joined to the through-hole conductors connected to the electrode layers on the upper and lower surfaces of the obtained wiring board with a built-in capacitor, and the capacitance of the built-in capacitor was measured. Also, by cutting the same sample and conducting EPMA analysis of the cross section,
Ratio of Ca amount (c2) contained in low dielectric constant layer to Ca amount (c1) contained in high dielectric constant layer (= c2 × 100
/ C1 (%)) is shown in Table 3 as a Ca content ratio.

The evaluation criteria are as follows: when the deviation of the actually measured value is 3% or less of the design value with respect to the design value of the built-in capacitor of 30 pF; Table 3 shows the case where the value is larger than the above.

[0042]

[Table 3]

As a result, the ratio of the amount of Ca contained in the low dielectric constant layer to the total amount of Ca contained in the high dielectric constant layer is independent of the dielectric constant and thickness of the high dielectric layer and the electrode dimensions of the built-in capacitor. By setting it to 20% or more, it is possible to suppress the deviation of the capacitor capacitance from the design value to 3% or less.

[0044]

As described in detail above, according to the present invention, by adjusting the amount of Ca contained in the high dielectric constant layer and the low dielectric constant layer, the high dielectric constant layer, the low dielectric constant layer, and the conductor wiring are adjusted. Even if the layers are fired simultaneously, a reduction in the capacity of the built-in capacitor due to the diffusion of Ca can be suppressed, and a capacitor having a deviation from the designed value within 3% can be obtained. Also,
Since a highly accurate capacitor can be formed in the wiring board, it is possible to reduce the size of an external electric circuit board such as a printed board on which the wiring board is mounted, and to reduce the cost of mounting the capacitor.

[0045]

[Brief description of the drawings]

FIG. 1 is a schematic sectional view for explaining one embodiment of a multilayer wiring board of the present invention.

[0046]

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Insulating board 1a, 1b, 1c Insulating layer 2 Conductor wiring layer 3 Electrode layer 4 Through-hole conductor

Continuation of the front page F term (reference) 5E346 AA13 AA43 BB20 CC17 CC18 CC21 CC32 DD13 DD45 EE27 EE29 FF18 HH22 HH31

Claims (4)

[Claims] 1. A multilayer wiring board having a conductor wiring layer disposed on or in a surface of a ceramic insulating substrate on which a high dielectric layer and a low dielectric layer are laminated.
A multilayer wiring board containing TiO ₃ , wherein the low dielectric layer contains 20% or more of the total Ca in the high dielectric layer. 2. The method according to claim 1, wherein the high dielectric constant layer and the low dielectric constant layer are formed of Si.
O ₂ to _{-BaO-CaO-Al 2 O 3} -B 2 O 3 based glass, a multilayer wiring according to claim 1, characterized by comprising a sintered body obtained by firing the addition of an inorganic filler substrate. 3. The low dielectric constant layer as an inorganic filler,
3. The multilayer wiring board according to claim 2, comprising at least quartz and / or forsterite. 4. The multilayer wiring board according to claim 1, wherein a pair of electrode layers are provided above and below said high dielectric constant layer.