JP2002076640A - Circuit board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a circuit board for securing the connection reliability between wiring conductors even if the diameter of an Ag-based via hole conductor is increased, restraining cracks and the projection of the via hole conductor from the surface of a substrate, and flattening the surface of the via hole conductor. SOLUTION: In the circuit board where the Ag-based inner wiring 3 and the via hole conductor 4 penetrating the thickness are arranged among a plurality of dielectric layers 1a-1e made of glass and ceramic constituents and at the dielectric layers 1a-1e, respectively, the via hole conductor 4 is made of an Ag-based conductor, β quartz with 5-8 pts.wt., and at least either of MoO3 and Ru2O where the total is 0.5-8.0 pts.wt. to Ag-based material 100 pts.wt.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circuit board formed by laminating a dielectric layer made of glass-ceramic serving as a glass component and a ceramic component, and to a via-hole conductor formed in the circuit board. .

[0002]

2. Description of the Related Art Conventionally, a firing temperature of 800 to 1050 has been used.
A circuit board using a material that can be fired at a relatively low temperature of ° C. has been widely proposed.

[0003] A circuit board includes a board on which a plurality of dielectric layers are laminated, internal wirings arranged between the dielectric layers of the laminate, and
It is composed of surface wirings arranged on the surface of the laminate, and via-hole conductors connecting predetermined internal wirings in the thickness direction of each dielectric layer and connecting predetermined internal wirings and surface wirings.

Incidentally, various electronic components such as an IC chip are mounted on the surface wiring arranged on the surface of the laminate.

[0005] In order to increase the conductivity of the above-mentioned internal wiring to increase the circuit speed, the internal wiring, the via-hole conductor, and the surface wiring are made of Ag alone or Ag-Pd, A
An Ag-based material made of an Ag alloy such as g-Pt is used. As the dielectric layer, a material that can be fired at a low temperature (800 to 1050 ° C.) based on the melting point of the Ag-based material described above is used. For example, a glass-ceramic material composed of a glass component and a ceramic component.

[0006] The above-mentioned internal wiring and via-hole conductor have a similar sintering behavior at least when fired integrally with the laminated substrate, and contain a large amount of glass components in order to match firing shrinkage. . If the sintering shrinkage between the substrate material and the via-hole conductor is not matched, the surface of the via-hole conductor on the substrate surface will protrude. As a result, wiring on the substrate surface cannot be formed. Impossible to implement.

In addition, in particular, connection between each internal wiring,
In the via-hole conductor connecting the internal wiring and the surface wiring, it is required to reduce the conductor resistance with the recent increase in the speed of circuit operation. In order to meet this demand, the diameter of the via hole conductor is physically increased (diameter of 8).
0 μm or more).

However, according to the conventional method, if the substrate and the via-hole conductor are simultaneously fired, the sintering shrinkage of the glass-ceramic material as the substrate material and the sintering shrinkage of the via-hole conductor cannot be matched. That is, the thermal stress due to the difference in thermal expansion coefficient increases during firing and cooling. For example, cracks occur around the via-hole conductor on the surface of the substrate, and conduction failure occurs.

Therefore, an internal wiring mainly composed of Ag is formed between a plurality of dielectric layers composed of a glass component and a ceramic component, and a via hole conductor mainly composed of an Ag-based material penetrating through the dielectric layer. And the via-hole conductor is based on 100 parts by weight of the Ag-based material.
A circuit board containing 2 to 5% by weight of β-quartz and 0.1 to 1% by weight of at least one of magnesium oxide, aluminum oxide, and calcium oxide has already been proposed.

According to this technique, the via-hole conductor is
It contains a predetermined amount of β-quartz and at least one oxide of magnesium oxide, aluminum oxide, and calcium oxide. β-quartz mainly reduces the thermal stress due to the difference in thermal expansion coefficient between the substrate material and the Ag-based via-hole conductor, and at least one oxide of magnesium oxide, aluminum oxide, and calcium oxide is burned. The sintering of the via-hole conductor is delayed until the sintering of the substrate material is started by being present between the Ag particles at the time of sintering, and the shrinkage stress due to sintering is reduced.

As a result, even if the diameter of the via-hole conductor is increased in order to reduce the conductor resistance of the via-hole conductor, the difference in thermal expansion from the substrate is reduced, and the shrinkage behavior is approximated. As a result, the connection reliability between the wiring conductors is stabilized, and no crack is generated in the via-hole conductor and the opening thereof, and the protrusion of the via-hole conductor from the surface of the substrate is suppressed.

[0012]

Here, in order to improve the smoothness of the substrate, it is desired to make the surface of the via-hole conductor flat.

However, in the above-described circuit board, the connection reliability between the wiring conductors is stabilized, and the via-hole conductor and the opening thereof are not cracked, and the protrusion of the via-hole conductor from the surface of the board can be suppressed. Although it is possible, as shown in FIG.
When the diameter of the via-hole conductor is increased, there is a problem that the central portion is dented. In FIG. 3, reference numeral 1a denotes a dielectric layer on the surface side of the laminated substrate 1.

Although the shrinkage behavior of the via-hole conductor 40 is similar to that of the substrate material as a whole, the shrinkage speed is slightly different between the peripheral portion and the central portion. Is considered to be dented.

The present invention has been devised in view of the above-mentioned problems, and has as its object to ensure the connection reliability between wiring conductors even when the diameter of via-hole conductors is increased, and to prevent cracks. An object of the present invention is to provide a circuit board capable of suppressing occurrence, suppressing the amount of protrusion of a via-hole conductor from the surface of the substrate, and flattening the surface of the via-hole conductor.

[0016]

According to the present invention, there is provided a circuit board having an internal wiring mainly composed of Ag disposed between a plurality of dielectric layers comprising a glass component and a ceramic component. A via-hole conductor having Ag as a main component and having a thickness of 0.5 to 8.0 parts by weight of β-quartz based on 100 parts by weight of the Ag-based conductor material. And the total is 0.5 ~
It contains 8.0 parts by weight of at least one of MoO ₃ and Ru ₂ O.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a circuit board according to the present invention will be described with reference to the drawings. FIG. 1 is a sectional view of a circuit board according to the present invention. In FIG. 1, reference numeral 10 denotes a circuit board,
Is a laminated substrate, 21 is a first surface wiring formed on the surface of the laminated substrate 1, 22 is a second surface wiring, 3 is an internal wiring formed in the laminated substrate 1, and 4 is a wiring formed in the laminated substrate 1. The via hole conductor 5 is an IC chip component, and 6 is another electronic component. Note that the first surface wiring 21 and the second surface wiring 22 are generally referred to as surface wiring 2.

The laminated substrate 1 has dielectric layers 1a to 1e made of a glass-ceramic material and internal wirings for achieving a predetermined circuit network and generating a capacitance component between the dielectric layers 1a to 1e. 3 are arranged.

In the dielectric layers 1a to 1e, via-hole conductors 4 penetrating in the thickness direction of the layers are formed. Further, a surface wiring 2 is formed on the surface of the laminated substrate 1 on which the dielectric layers 1a to 1e are laminated.

The dielectric layers 1a to 1e are, for example, 850 to 1
It is made of a glass-ceramic material that can be fired at a relatively low temperature of around 050 ° C. Specific ceramic materials include insulating ceramic materials such as cristobalite, quartz, corundum (α-alumina), mullite, cordierite, dielectric ceramic materials such as BaTiO ₃ , Pb ₄ Fe ₂ Nb ₂ O ₁₂ , TiO ₂ , and Ni -Zn ferrite, M
n-Zn ferrite (ceramic in a broad sense)
And other magnetic ceramic materials. The average particle size is 1.0 to 6.0 μm, preferably 1.5 to 6.0 μm.
Use the one crushed to 4.0 μm. Further, two or more ceramic materials may be used in combination. In particular, the use of corundum is advantageous in terms of cost.

The frit of the glass component is calcined, mullite, anorthite,
Serdian, spinel, garnite, willemite, dolomite, petalite or a substituted derivative thereof or a crystal of a spinel structure may be precipitated, for example,
Glass frit containing B ₂ O ₃ , SiO ₂ , Al ₂ O ₃ , ZnO, and alkaline earth oxide can be used. Such a glass frit has a wide vitrification range and a yield point of 600
~ 800 ° C.

The thickness of each of the dielectric layers 1a to 1e is, for example, about 100 to 300 μm.

The internal wiring 3 and the via-hole conductor 4 are made of Ag (Ag alone, Ag alloy such as Ag-Pd, Ag-Pt).
And the thickness of the internal wiring 3 is about 8 to 15 μm. The diameter of the via-hole conductor 4 can be set to an arbitrary value, but is set to 80 to 350 μm in order to increase the diameter and reduce the resistance.
In particular, the via-hole conductor 4 is made of an Ag-based material, β quartz, Mo
O ₃ , a crystal phase of cordierite, mullite, anorthite, serdian, spinel, garnite, willemite, dolomite, petalite or a substituted derivative thereof or a crystal phase having a spinel structure, for example, B ₂ O ₃ , SiO ₂ , A
Glass frit containing l ₂ O ₃ , ZnO, and alkaline earth oxide may be used.

The first surface wiring 21 is made of a conductive film mainly composed of Ag (Ag alone, Ag-Pd, Ag-Pt or other Ag alloy), and mainly has a predetermined circuit wiring on the surface of the laminated substrate 1. And also serves as a connection pad for the electronic component 6 to be joined via solder.
It becomes the terminal electrode of the thick film capacitor element. In particular, in connection with internal wiring 3, first surface wiring 21 is connected to via-hole conductor 4 exposed from dielectric layer 1a.

The second surface wiring 22 is made of a conductive film mainly composed of Au, and is mainly used as a connection pad (wire bonding pad) of the IC chip 5 connected by a bonding thin wire or a flip chip.

The electronic component 6 can be exemplified by a chip-shaped electronic component such as a multilayer ceramic capacitor or a chip resistor, other oscillating devices or transistors, and is connected to the first surface wiring 21 via solder.

The IC chip 5 is provided with a predetermined surface wiring (2
1, 22) and the like,
It is connected to the second surface wiring 22 via wire bonding using a l or Au bonding thin wire or via a pump member formed on the lower surface of the IC chip 5.

A method for manufacturing the above-described circuit board will be described.

First, the glass which becomes the dielectric layers 1a to 1e
A green sheet made of a ceramic material is formed. Specifically, the above-mentioned ceramic powder, the above-mentioned frit of the low-melting glass component, the organic binder, and a slurry obtained by homogeneously kneading the organic solvent are tape-formed to a predetermined thickness by a doctor blade method, and cut into a predetermined size. Create a sheet. The composition ratio of the ceramic material and the glass material is 10 to 60% by weight, preferably 30 to 50% by weight of the ceramic material in order to stably fire at a relatively low temperature of 850 to 1050 ° C. 90-40 material
%, Preferably 70 to 50% by weight.

The organic binder also needs to pay attention to the wettability with solids (ceramic powder, frit of low melting point glass component), and is thermally decomposable so that it can be burned off in a relatively low temperature and short firing step. Excellent ones are preferable, and ethylenically unsaturated compounds having a carboxyl group and an alcoholic hydroxyl group such as acrylic acid or methacrylic acid-based polymers are preferable.

As the solvent, an organic solvent or an aqueous solvent can be used. For example, in the case of an organic solvent,
For example, 2,4-trimethyl-1,3-pentanediol monoisoventate or the like is used. In the case of an aqueous solvent, the solvent must be water-soluble, and the monomer and the binder include a hydrophilic functional group such as carboxyl. A group has been added. The amount of addition is 2 to 300, preferably 5 to 100, when expressed in acid value. If the added amount is small, the solubility in water and the dispersibility of the powder of the fixed component deteriorate, and if the added amount is large, the thermal decomposability deteriorates. In consideration of the above, it is appropriately added within the above range.

Next, through holes of a predetermined diameter in which via-hole conductors 4 are formed through the thicknesses of the respective dielectric layers are formed in the green sheets to be the dielectric layers 1a to 1e by punching.

The through-hole has an opening diameter of 80 to 3 as required to reduce the conductor resistance of the via-hole conductor 4.
It is 50 μm.

Next, a conductor to be a via-hole conductor 4 is formed in the through hole formed in the green sheet by printing and filling an Ag-based conductive paste, and a conductor film to be each internal wiring 3 is formed on the green sheet. Is printed and a drying process is performed. At the same time, a conductor film to be the first surface wiring 21 and the second surface wiring 22 is printed on the green sheet positioned on the outermost surface, and a drying process is performed.

Here, the Ag-based conductive paste of the internal wiring includes Ag-based (Ag alone, Ag-Pd, Ag-Pt or other Ag alloy) powder, borosilicate-based low melting point glass frit, organic binder such as ethyl cellulose, or the like. What mixed the solvent homogeneously is used.

The conductive paste for the via hole is A
0.5 to 8.0 parts by weight of β quartz and 0.5 to 8.0 parts by weight based on 100 parts by weight of g-based (Ag alone, Ag alloy such as Ag-Pd, Ag-Pt) powder MoO which is a part
₃ , a homogeneous mixture of at least one of Ru ₂ O, an organic binder such as ethyl cellulose, and a solvent is used.

Here, β-quartz has a characteristic of a low coefficient of thermal expansion, has an effect of making the coefficient of thermal expansion of the via-hole conductive film close to the coefficient of thermal expansion of the substrate material, and can reduce the thermal stress during firing and cooling. Therefore, the diameter of the via-hole conductor 4 can be increased, and the conductor resistance can be reduced.

As shown in FIG. 2, MoO ₃ and Ru ₂ O can make the surface of the via-hole conductor 4 flat.

That is, as in the prior art, in a combination of β-quartz and at least one oxide of aluminum oxide, magnesium oxide and calcium oxide, it is added as an organic metal or a fine powder having a specific surface area of 100 cm ³ / g or more.
Although they are effectively arranged between Ag particles and function to delay the sintering of Ag, there is a limit in making the shrinkage behavior of the via-hole conductor close to that of the dielectric layer.

On the other hand, in the present invention, since the MoO ₃ or Ru ₂ O in the via-hole conductor 4 itself promotes the sintering of the high-temperature region Ag, the shrinkage behavior of the via-hole conductor 4 is changed to the shrinkage behavior of the laminated substrate 1. Because it can be approached effectively. Note that MoO ₃ and Ru ₂ O may be added alone or as a mixture.

The conductive paste on which the first surface wiring 21 is formed is obtained by homogeneously mixing Ag-based (Ag alone, Ag alloy such as Ag-Pd) powder, Pt powder, an inorganic binder, an organic binder, and a solvent. Things are used.

The conductive paste on which the second surface wiring 22 is formed is made of Au (Au alone, Au-Pd, Au-Pt).
A homogeneous mixture of an Au alloy powder, an inorganic binder, an organic binder, and a solvent is used. The first and second surface wirings 21 and 22 have V ₂ as a solid component.
When the O ₅ powder is added 0.2 to 1.0 parts by weight for each metal component, the desired adhesion strength between the laminated surface of the substrate 1 is improved.

The conductor which becomes the via-hole conductor 4 as described above,
Dielectric layers 1b-1 on which a conductor film to be internal wiring 3 is formed
e, green sheet, and first surface wiring 21, A
A green sheet to be a dielectric layer 1a on which an Au-based conductor film serving as a g-based conductor film and a second surface wiring 22 is formed,
The dielectric layers 1a to 1e of the laminated substrate 1 are laminated and integrated according to the lamination order.

Next, the unfired laminated substrate is fired in an oxidizing, neutral atmosphere or air atmosphere. The firing process is
It consists of a binder removal process and a sintering process.

The binder removal process involves burning off organic components contained in the green sheets serving as the dielectric layers 1a to 1e, the conductor film serving as the internal wiring 3, the conductor serving as the via hole conductor 4, and the conductor film serving as the surface wirings 21 and 22. This is performed, for example, in a temperature range of 600 ° C. or less.

In the sintering process, the glass component of the green sheet that becomes the dielectric layers 1a to 1e is crystallized and simultaneously dispersed uniformly at the grain boundaries of the ceramic powder to give a certain strength to the laminated substrate. An Ag-based material or an Au material, which is a metal powder of a conductive material of the conductor film serving as the wiring 3, the conductor serving as the via-hole conductor 4, and the conductor film serving as the surface wirings 21 and 22, is subjected to grain growth to reduce the resistance, Layers 1a to 1e
Is to be integrated. This is a peak temperature of 850
It is carried out until it reaches に 1050 ° C.

In this step, the laminated substrate 1 in which the internal wiring 3 and the via-hole conductor 4 are formed and the surface wirings 21 and 22 are formed on the surface is achieved.

Thereafter, if necessary, the first surface wiring 2
A thick-film resistance element connected to 1 and an insulating protective film of a predetermined shape are formed, and various electronic components 6 are joined and mounted with solder or the like. Further, the IC chip 5 is mounted on the predetermined wiring conductor film, and the second surface wiring 22 is subjected to wire bonding bonding using Al or Au bonding fine wires or flip chip connection using solder bumps.

Thus, the circuit board shown in FIG. 1 can be achieved.

In the above description, the surface of the laminated substrate 1
Although the first surface wiring 21 and the second surface wiring 22 are formed, for example, the second surface wiring 22 may be omitted.

Here, via-hole conductors 4 formed in dielectric layer 1a connecting predetermined internal wirings 3 and surface wirings 21 are formed.
Is formed of an Ag-based material, but the first surface wiring 2
1 is made of an Ag-based material similarly to the via-hole conductor 4, so that stable connection is achieved.

[0052]

The present inventors changed the shape of the via-hole conductor from 50 to 400 μm in diameter, and at the same time, as an Ag-based conductive paste, with respect to 100 parts by weight of the Ag-based material, β quartz, MoO ₃ , Ru. ₂ O and further an oxide (calcium oxide, magnesium oxide, or aluminum oxide) were added, and the amount ratio was examined.

In Sample Nos. 1 to 15, the diameter of the via hole conductor was 350 μm, and in Sample Nos. 16 to 17, the diameter of the via hole conductor was 80 and 400 μm.

In Sample Nos. 1 to 5, Ru ₂ O was added in an amount of 4 parts by weight, and β-quartz was changed to 0 to 9 parts by weight with respect to the solid component.

Sample No. 6 was made of β quartz (average powder particle size 7 μm).
m) 4.0 parts by weight of oxide, MoO ₃ , Ru ₂ O
Was not added.

In sample numbers 7 to 9, 4.0 parts by weight of β-quartz was added to the solid component, and MoO ₃ was changed to 0.5 to 9.0 parts by weight based on the solid component. .

In sample numbers 10 to 12, 4.0 parts by weight of β-quartz was added to the solid component, and Ru ₂ O was changed to 0.5 to 9.0 parts by weight based on the solid component. Was.

In Sample Nos. 13 to 15, β-quartz was added to the solid component in an amount of 4.0 wt%, and magnesium oxide, aluminum oxide, and calcium oxide (average powder particle diameter of less than 1 μm) were added as oxides to the solid component. On the other hand, 1.0wt
% Was added.

Table 1 shows the results. In the judgment of good or bad, the conductor resistance of the via-hole conductor was less than 1 mΩ, the one where no crack was generated in the substrate part around the via-hole conductor was “good”, and the protrusion amount of the substrate in the part where the via-hole conductor was formed was less than 10 μm. Is "good". The via hole shape is “C” when the amount of protrusion of the via hole portion 40 is 10 μm or more, “B” when only the peripheral portion of the via hole conductor 40 in FIG.
As shown in FIG. 2, the case where the surface of the via-hole conductor became flat was defined as “A”. Further, as a criterion for the comprehensive judgment, a conductor having at least one of the above-mentioned conductor resistance, crack, and protrusion amount is “crossed”, and the conductor resistance, crack, and protrusion amount are all good, but the via hole shape is B. Certain ones were indicated by "triangles", and those having the above-mentioned conductor resistance, cracks and protrusion amounts were all good, and the via hole shape was A were indicated by "circles".

[0060]

[Table 1]

First, the via-hole conductor is made of an Ag-based material 10
When 0 part by weight contains at least one of 4 parts by weight of β quartz and 0.5 to 8 parts by weight of MoO _{3 or} Ru ₂ O (sample numbers _{2 to} 4, 7 to 8, 10 ~ 11,16
17), the conductor resistance, cracks, and protrusion amounts are all good, and the surface of the via-hole conductor becomes flat.

On the other hand, 4 wt% β quartz, 1 wt%
Containing at least one of magnesium oxide, aluminum oxide and calcium oxide (sample numbers 13 to
15) Although the conductor resistance, cracks, and protrusion amounts are all good, the peripheral portion of the via hole shape rises.

When β-quartz is not contained (sample No. 1), the coefficient of thermal expansion cannot be matched to the coefficient of thermal expansion of the laminated substrate, and cracks occur during sintering and cooling.

When β-quartz exceeds 8 parts by weight and is excessively contained (sample No. 5), the conductor resistance increases and exceeds, for example, 1 mΩ.

Further, when MoO ₃ , Ru ₂ O, and oxide are not contained (sample No. 6), since the shrinkage matching between the via hole conductor and the laminated substrate cannot be obtained, the surface of the via hole conductor is formed on the substrate surface. Will protrude by about 20 μm.

When MoO ₃ and Ru ₂ O are excessively contained (Sample Nos. 9 and 12), M
oO ₃ and Ru ₂ O become excessive, and the conductor resistance exceeds 1 mΩ.

Further, as shown in Sample Nos. 16 and 17, the diameter of the via-hole conductor becomes a via-hole conductor having stable characteristics even at 80 to 400 μm. At 50 μm,
Although cracks and protrusions of via hole conductors are not seen,
Physical conductor resistance increases.

In the above experiment, Ag-based powder was used.
Ag alone was used, but A-Pp or Ag-Pt
It was confirmed that a similar effect was obtained even when an Ag-based material containing g as a main component was used.

From the above experiments, it was found that the conductor resistance, crack,
In consideration of the amount of protrusion, the via-hole conductor is 0.5 to 8 parts by weight of β-quartz and 0.5 to 8 parts by weight of MoO ₃ or Ru ₂ O with respect to 100 parts by weight of the Ag-based conductor material. Is important.

[0070]

As described above, according to the present invention, the via-hole conductor is made of an Ag-based material, 0.5 to 8 parts by weight of β quartz, MoO ₃ having a total of 0.5 to 8.0 parts by weight, It is formed using a conductive paste to which at least one of Ru ₂ O is added. This makes it easy to increase the diameter of the via-hole conductor to lower the conductor resistance value, and furthermore, since the shrinkage matching with the substrate is good, the circuit has excellent substrate smoothness and surface smoothness of the via-hole conductor. It becomes a substrate.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a circuit board according to the present invention.

FIG. 2 is an enlarged view of a via-hole conductor of the circuit board of the present invention.

FIG. 3 is an enlarged view of a via-hole conductor of a conventional circuit board.

[Explanation of symbols]

 10. Circuit board 1. Multilayer board 1a-1e .. Dielectric layer 2. Surface wiring 3. Internal wiring 4. Via-hole conductor

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01L 23/14 H01L 23/12 C H05K 1/09 N // H01B 1/16 23/14 CMF term (Reference) 4E351 AA07 AA13 BB01 BB24 BB26 BB31 CC12 CC31 DD05 DD31 DD32 DD58 EE02 EE03 GG02 GG06 5E346 AA12 AA13 AA15 AA38 AA43 BB01 CC18 CC39 DD02 DD34 EE24 FF18 GG02 GG06 GG09 H301 H33 DA11

Claims (1)

[Claims] An internal wiring having Ag as a main component is disposed between a plurality of dielectric layers composed of a glass component and a ceramic component, and the dielectric layer penetrates through its thickness.
Wherein the via hole conductor is 0.5 to 8.0 parts by weight of β-quartz with respect to 100 parts by weight of the Ag-based conductor material, and the total is 0.
Circuit board, characterized by containing a MoO _3, at least one of Ru ₂ O is from 5 to 8.0 parts by weight.