JP2002348172A - High frequency wire board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high frequency wire board with high thermal conductivity, having a low dielectric constant and dielectric loss at high frequency region, that can form a wire circuit layer out of low resistant metals such as Ag, Cu and Au. SOLUTION: In this high frequency wire board, wire circuit layers 2 that transmit high frequency signals are attached to and formed on the surface of or inside the dielectric board 1. As the dielectric board 1, a glass ceramic comprised of 30-95 wt.% glass component and 5-70 wt.% filler component that includes at least an aluminum nitride crystal particle having <=0.8 wt.% oxygen amount, <=1% porosity and >=2 μm mean particle size. The dielectric board 1 uses a glass ceramic having >=5 W/m.K thermal conductivity, <=8 dielectric constant at 15 GHz measured frequency and <=100×10<-4> dielectric loss, is used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is applied to a package for housing a semiconductor element, a multilayer wiring board and the like, and particularly relates to a high-frequency wiring board having high thermal conductivity and low dielectric loss.

[0002]

2. Description of the Related Art In recent years, with the era of advanced information technology, information and communication technology has been rapidly developed. Accordingly, the speed and size of semiconductor devices have been increasing. For this reason, the problem of signal delay in a package, a substrate, and the like is increasing with the speeding up of the semiconductor element. At the same time, the problem of thermal resistance in a package, a substrate, or the like due to an increase in the amount of heat generated due to an increase in the size of the semiconductor element is also increasing.

Conventionally, as a ceramic multilayer wiring board, an alumina wiring board in which a wiring circuit layer made of a refractory metal such as tungsten or molybdenum is formed on the surface or inside of an insulating layer made of an alumina-based sintered body is most widely used. are doing.

However, in the conventional alumina wiring board,
Tungsten (W) or molybdenum (M
A high melting point metal such as o) has a large conductor resistance, and the dielectric constant of alumina is as high as about 9, so that a large signal delay has been a problem. Therefore, it is required to use a low-resistance metal such as copper, silver, or gold as a conductor instead of a metal such as W or Mo, and to further lower the dielectric constant of the insulating layer.

[0005] Therefore, recently, by using glass or glass-ceramics, which is a composite material of glass and ceramic filler, as an insulating layer, 1000 or more is used.
Developed a glass-ceramic wiring board that can be fired at a low temperature of ℃ or lower, allows low-resistance metals such as copper, silver, and gold with low melting points to be used as conductors and has a dielectric constant lower than that of alumina Is being done.

For example, as disclosed in Japanese Patent Publication No. 4-12639, an insulating phase in which SiO ₂ filler is added to glass,
A wiring layer made of a low resistance metal such as copper, silver,
A multilayer wiring board co-fired at a temperature of ５０1050 ° C. or a zinc borosilicate glass to which a filler such as alumina, zirconia or mullite is added simultaneously with a low-resistance metal, as disclosed in Japanese Patent Application Laid-Open No. 60-240135. Fired products and the like have been proposed. In addition, JP-A-5-298919
Also proposes a glass ceramic material in which mullite or cordierite is precipitated as a crystalline phase.

[0007]

However, in the above-mentioned conventional glass ceramics, the thermal conductivity is as low as 2 W / m · K or less, and the heat dissipation is inferior to that of conventional alumina and the like. Met.

Therefore, as described in JP-A-63-307182, there has been proposed a wiring board using an insulating substrate made of glass ceramics using AlN which itself has excellent thermal conductivity as a filler.

However, glass ceramics using AlN as a filler have improved thermal conductivity as compared with conventional glass ceramics, but have a high relative dielectric constant of 12, and are required to have a low dielectric constant. Was unsuitable for Further, in a high-frequency wiring board that transmits a high-frequency signal having a frequency of 500 MHz or more, it is desired that the dielectric loss is small. However, a conventional glass ceramic containing AlN has a large dielectric loss of 20 × 10 ⁻³ or more. However, it is difficult to apply as a high-frequency wiring board.

Accordingly, the present invention provides a high-frequency wiring board having high thermal conductivity, low relative permittivity and dielectric loss in a high-frequency region, and capable of being co-fired with a low-resistance metal such as silver, copper, or gold. The purpose is to provide.

[0011]

Means for Solving the Problems As a result of diligent studies on the above-mentioned problems, the present inventors have found that the glass ceramic contains at least aluminum nitride crystal particles as a filler component and the oxygen content in the aluminum nitride crystal particles is reduced to 0%. By controlling the content to be not more than 0.8% by weight, low resistance metals such as silver, copper and gold, low melting point metals, among which silver can be co-fired, high heat conductivity, and low dielectric loss even in a high frequency region. The present inventors have found that glass ceramics can be provided with good yield, and have reached the present invention.

That is, a high-frequency wiring board according to the present invention has a wiring circuit layer for transmitting a high-frequency signal adhered to the surface or inside of a dielectric substrate, wherein the dielectric substrate is made of a glass component. And a glass ceramic having an open porosity of 1% or less comprising a filler component and containing at least aluminum nitride crystal particles as the filler component, wherein the oxygen content in the aluminum nitride crystal particles is 0.8% by weight or less. It is characterized by having.

More specifically, 30% of the glass component is used.
In order to control the sinterability and electrical characteristics at low temperatures, it is desirable that the filler component be contained at a ratio of 5 to 70% by weight and that the aluminum nitride crystal particles have an average particle size of 2 μm or more. There is a feature. Thereby, the thermal conductivity is 5 W / m · K or more and the measurement frequency is 15 G
The dielectric constant around 8 Hz is 8 or less, and the dielectric loss is 100
× is characterized in that it has a ^10-4 following characteristics.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An example of a high-frequency wiring board according to the present invention will be described with reference to FIG. According to the high-frequency wiring board of FIG. 1, a wiring circuit layer 2 capable of transmitting a high-frequency signal is formed on the surface or inside of the dielectric substrate 1. The wiring circuit layer 2 includes, for example, a microstrip line, a coplanar line, a strip line, a coplanar line with ground, and the like. For example, in the case of a microstrip line, the wiring circuit layer 2 includes a ground layer 2a and a center conductor 2b. In addition, via-hole conductors 3 and the like are provided inside the dielectric substrate 1 as necessary. A high-frequency element 4 and the like are mounted on the surface of the wiring board.

According to the present invention, the dielectric substrate has a low dielectric loss in a high frequency region in order to reduce the signal transmission loss while effectively dissipating heat generated from the high frequency element 4 mounted on the surface. It is necessary to be formed by the dielectric substrate of the above.

According to the present invention, the dielectric substrate 1 is formed of a glass ceramic comprising a mixture of a glass component and a filler component, and at least aluminum nitride (hereinafter referred to as AlN) crystal particles as the filler component. It contains.

According to the present invention, the amount of oxygen in the AlN crystal particles dispersed in the ceramic is 0.8
It is important that it is less than or equal to weight percent. This gives A
The thermal conductivity of the glass ceramic can be improved by improving the thermal conductivity of the 1N crystal particles themselves. Further, according to the present invention, by including such AlN crystal particles containing low oxygen, it is possible to lower the dielectric constant of a glass ceramic in a high frequency region and to reduce the dielectric loss. The oxygen content of the aluminum nitride particles is desirably 0.5% by weight or less.

That is, when the amount of oxygen in the AlN crystal particles in the glass ceramics exceeds 0.8% by weight, the thermal conductivity tends to decrease and the dielectric constant tends to increase, and the dielectric loss in a high frequency region also increases. Will increase. This AlN
The amount of oxygen in the crystal particles can be easily measured by an Auger electron microscope based on Examples described later.

According to the present invention, it is desirable that the AlN crystal particles exist as particles having an average particle diameter of 2 μm or more, particularly 4 μm or more. This is because thermal conductivity and dielectric loss tend to decrease as the average particle size increases, and strength tends to increase. However, when the particles are too large, the smoothness of the ceramic surface is reduced, and destruction starting from coarse particles is likely to occur, and the strength is reduced. Therefore, the average particle size is 30 μm or less, particularly 15 μm or less.
μm or less, more preferably 10 μm or less.

According to the present invention, in order to achieve high thermal conductivity,
5% by weight or more of AlN crystal particles as a filler,
Desirably, the content is 0% by weight or more, more preferably 20% by weight or more.

Further, the glass ceramic may contain other ceramic fillers as fillers other than AlN crystal particles. Other fillers include Al
₂ O ₃ , SiO ₂ (quartz, cristobalite, tridymite), 3Al ₂ O ₃ · ₂ SiO ₂ , MgSiO ₃ , Mg
_{2 SiO 4, CaMgSi 2 O 6} , Mg 2 Al 4 Si 5 O 18,
ZnAl ₂ O ₄ , MgAl ₂ O ₄ , CaAl ₂ Si ₂ O ₈ , S
rAl ₂ Si ₂ O ₈ , BaAl ₂ Si ₂ O ₈ , Ca ₂ MgSi
O ₇ , Sr ₂ MgSiO ₇ , Ba ₂ MgSiO ₇ , ZnO,
CaSiO ₃ , SrSiO ₃ , BaSiO ₃ , Si ₃ N ₄ ,
At least one selected from the group consisting of SiC;
It is contained within a range that does not impair the effect of the dispersion of the 1N crystal particles, and is suitably contained in a proportion of not more than 30% by weight.

The glass component in the glass ceramic of the present invention includes silica glass, borosilicate glass, aluminosilicate glass, Pb-based glass, Bi-based glass, alkali-based glass, alkaline-earth-based glass, aluminoborosilicate glass and the like. And, particularly, 1000
Aluminosilicate glass, to realize sintering at a temperature of less than ℃ and to simultaneously sinter with a low-resistance metal such as Cu or Ag.
At least one selected from the group consisting of aluminoborosilicate glass, alkali glass and alkaline earth glass is desirable.

Further, the glass component is an amorphous glass,
Any of crystallized glass may be used.
Is desirably a crystallized glass. Deposited from glass
The crystal phase that can be emitted is SiO 2_Two(Quartz), MgAl_Two
O_Four(Spinel), ZnAl_TwoO _Four(Garnite), Ca
(Mg, Al) (Si, Al)_TwoO₆(Diopsai
C), CaMgSi_TwoO₇(Akermanite), Sr_TwoM
gSi_TwoO₇(Sr-Akermanite), CaMgSiO
_Four(Monticerite), Ca_ThreeMgSi_TwoO₈(Merirai
G), Mg_TwoSiO_Four(Enstatite), MgSiO_Three
(Enstatite), 3Al_TwoO_Three・ 2SiO_Two(Murai
G), Mg_TwoAl_FourSi_FiveO₁₈(Cordierite), (S
r, Ca) Al_TwoSi_TwoO₈(Slausonite), CaA
l_TwoSi_TwoO₈(Anorthite), BaAl_TwoSi_TwoO₈(S
Luzian), (Ca, Sr) SiO_Three, SrSiO_ThreeFlock of
At least one member selected from the group consisting of:

Further, the glass ceramic in the present invention needs to have an open porosity of 1% or less. This is necessary to reduce the dielectric loss, and the open porosity is 1
%, Moisture is adsorbed in the open pores, and dielectric loss in a high-frequency region increases. In particular, the open porosity is desirably 0.5% or less, particularly preferably 0.2% or less.

In the present invention, the glass ceramic has a high thermal conductivity of 5 W / m · K or more, particularly 8 W / m · K or more, and has a relative dielectric constant of 8 or less at a measuring frequency of 1 GHz, particularly 7.5 or less, more preferably 7 or less, and a dielectric loss of 60 × 10 ⁻⁴ or less, particularly 50
It has excellent properties of not more than × 10 ^-4 , and more preferably not more than 30 × 10 ^-4 .

In the glass ceramic of the present invention, the total amount of the glass component is 30 to 95% by weight, preferably 32.
5 to 85% by weight, more preferably 35 to 80% by weight,
The ceramic filler component containing AlN is preferably present at a ratio of 5 to 70% by weight, preferably 15 to 67.5% by weight, more preferably 20 to 65% by weight. It is most suitable for improving characteristics. (Manufacturing method) Next, a method of manufacturing the glass ceramic according to the present invention will be described. First, as a starting material, a glass powder and a ceramic filler powder are mixed at a predetermined ratio. 30 to 95% by weight of glass powder, especially 3
2.5-85% by weight, optimally 35-75% by weight, A
5 to 5% by weight of ceramic filler containing 1N or more
70% by weight, especially 15-67.5% by weight, optimally 25%
Mix at a rate of ~ 65% by weight.

The composition of the glass and the filler is limited to the above range because the glass powder is less than 30% by weight or the ceramic filler is more than 70% by weight.
When the composition is fired at a low temperature of 000 ° C. or less, the composition has a relative density of 9
This is because it is difficult to densify the glass to 5% or more, and if the amount of the glass exceeds 95% by weight or the amount of AlN is less than 5% by weight, the effect of improving the thermal conductivity of the porcelain becomes insufficient.

The glass has a glass transition point of 8
When the temperature is not higher than 00 ° C., particularly not higher than 750 ° C., and most preferably not higher than 700 ° C., the densification in firing at not higher than 1000 ° C. can be promoted.

The glass used in the present invention contains SiO ₂ and B ₂ O ₃ as essential components. Specifically, 15 to 70% by weight of SiO ₂ and B ₂ O ₃
Is contained at a ratio of 0.5 to 30% by weight, and MgO, CaO, SrO, BaO, Z
At least one selected from the group consisting of nO and Al ₂ O ₃ may be contained. However, it is necessary to suppress the reactivity between the glass and the non-oxide ceramic filler. In order to suppress the reactivity, it is necessary to appropriately control the composition of the glass, the firing temperature, the firing atmosphere, and the like.
In particular, in the glass composition, the total content of Pb, Bi, Cu and the alkali metal element is 0.5% by weight or less,
In particular, it is desirably 0.3% by weight or less, and more desirably 0.1% by weight or less. This is because the above specific component is AlN
This is because it is a component that promotes the reaction with, and if these are present in excess of the above ratio, the reaction will occur.

Further, as the glass to be used, the thermal conductivity and the strength can be improved by crystallizing the glass alone or when firing a composition containing a filler. The crystal phase precipitated by crystallization of glass is
As described above. In order to enhance the sinterability, it is desirable that the average particle size of the glass powder is 2 μm or less, particularly 1.8 μm or less.

On the other hand, it is important that the AlN powder added as a filler has an oxygen content of 0.8% by weight or less, particularly 0.5% by weight or less, and more preferably 0.3% by weight or less.
That is, when the oxygen content of the AlN powder is more than 0.8% by weight, it becomes impossible to achieve a thermal conductivity of 5 W / m · K or more, a low dielectric constant and a low dielectric loss of the glass ceramics by firing at 1000 ° C. or less. That's why. Further, by setting the average particle size of the AlN powder to 2 μm or more, the thermal conductivity of the ceramic can be improved.

In order to produce such an AlN powder having a large average particle size uniformly and at low cost, it is desirable that the aluminum nitride powder is produced by a direct nitriding method. Further, in order to reduce the oxygen content in the AlN powder, a nitriding treatment for manufacturing the AlN raw material is required to be performed by 20%.
Treated at a high temperature of 00 ° C or higher, or
By adding a sintering aid such as ₂ O ₃ and performing calcination in a non-oxidizing atmosphere, the amount of oxygen in the AlN raw material can be reduced.

Further, Fe in aluminum nitride powder,
Si, C, Cu, Mn, Mg, Zn, Ni, Cr, Ti
It is desirable that the total amount of impurities other than Al be 0.1% by weight or less, particularly 0.02% by weight or less in order to achieve high thermal conductivity.

The glass ceramic of the present invention is prepared into a predetermined molded body using the mixed powder weighed and mixed with the above composition, and the molded body is fired in an oxidizing atmosphere or an inert atmosphere at 800 to 1000 ° C. However, it can be manufactured by densification until the open porosity becomes 1% or less.

Further, according to the present invention, as shown in FIG. 1, it is possible to obtain a wiring board having the above-mentioned glass ceramic as a dielectric substrate 1 and a wiring circuit layer 2 for high frequency on the surface or inside thereof. A suitable organic binder and a solvent are mixed with the mixed powder to prepare a slurry, which is formed into a sheet by a tape forming method such as press molding, extrusion molding, or a doctor blade method, to produce a green sheet.

After a through hole is formed in the green sheet as required, a metal paste containing Cu or Ag as a main component is filled in the through hole, and a conductive paste is formed on the surface of the green sheet in a predetermined circuit pattern. To form a high-frequency wiring circuit layer by printing and coating by screen printing method, gravure printing method, etc., applying a metal foil, patterning by etching, attaching a patterned metal foil, etc. .

If desired, a plurality of green sheets on which the wiring circuit layers are formed are laminated, for example, from 40 to 12
Heat and pressure bonding at 0 ° C. and 5 to 40 MPa, and in an oxidizing atmosphere or a weakly oxidizing atmosphere, 1000 ° C. or less, particularly 800 to
1000 ° C, 0.2 to 10 at 800 to 970 ° C
The wiring substrate can be manufactured by baking for 0.5 to 2 hours, particularly for 0.5 to 2 hours.

Then, on the surface of the wiring board,
A high-frequency element and the like are mounted and connected to a high-frequency wiring circuit layer so that high-frequency signals can be transmitted. The connection may be made by directly mounting on the wiring circuit layer and connecting by soldering or the like, or a resin of Ag-epoxy, Ag-glass, Au-Si or the like, a thickness of 50 μm made of at least one kind of metal or ceramic. A method in which the high-frequency element is fixed to the surface of the insulating substrate with a certain amount of adhesive and the wiring circuit layer and the high-frequency element are connected by wire bonding, TAB tape, or the like is applicable.

[0039]

EXAMPLES Glass powders having the composition and characteristics shown in Table 1 were prepared. In addition, as a ceramic filler, an AlN powder prepared by a reduction nitriding method or a direct nitriding method having the characteristics shown in Table 2 is prepared.
A calcination treatment was performed. When performing the calcining process, A
The treatment was performed after appropriately adding 0.5% by weight of Y ₂ O ₃ to the 1N powder. Incidentally, the average particle size was measured the d ₅₀ value by the micro track method. As for the amount of oxygen in the powder, a simultaneous oxygen and nitrogen analyzer (EMGA-650F) was used.
The oxygen content was measured using A).

The above glass powder and AlN powder were mixed in the combinations shown in Table 3 in the ratios shown in Table 3, and an acrylic organic binder, a plasticizer, and toluene were added to the mixture to prepare a slurry. To prepare a green sheet having a thickness of 300 μm by a doctor blade method.

Then, this green sheet is added to 10 to 15
The sheets are laminated and thermocompression-bonded at a temperature of 50 ° C. while applying a pressure of 10 MPa.
950 ° C in dry nitrogen
For 1 hour. During firing, the rate of temperature rise,
The cooling rate was 300 ° C./h.

The open porosity of the obtained glass ceramic was measured by the Archimedes method, and the oxygen content of aluminum nitride crystal particles in an arbitrary cross section of the glass ceramic was measured by an Auger electron microscope. In the measurement, the amount of oxygen was measured in the depth direction at the same time as the ceramic surface was sputtered. Also,
X-ray diffraction measurement was performed to identify a crystal phase detected in the ceramic.

Further, the glass ceramics were made 50 m in diameter.
m, a thickness of 1 mm, and using a network analyzer and a synthesized sweeper in the vicinity of 1 GHz in the TE ₀₁₁ mode and 13 to 1 by the cavity resonator method.
The resonance characteristics were measured at a resonance frequency of 8 GHz (around 15 GHz), and the dielectric constant and the dielectric loss were calculated. Further, the glass ceramic was processed into a diameter of 10 mm and a thickness of 1 mm, and the thermal conductivity was measured by a laser flash method. The results are shown in Table 1.

[0044]

[Table 1]

[0045]

[Table 2]

[0046]

[Table 3]

According to the results of Tables 1 to 3, the amount of oxygen in the AlN raw material powder and the AlN crystal particles in the ceramics has an effect on not only the thermal conductivity but also the relative dielectric constant and the dielectric loss. As the amount of oxygen increased, the thermal conductivity decreased, the dielectric constant increased, and the dielectric loss also tended to increase.However, based on the present invention, the AlN raw material powder and the AlN crystal particles in the ceramics had a tendency to increase. By setting the oxygen content to 0.8% by weight or less, the thermal conductivity is 5 W / m · K or more, the relative dielectric constant is 8 or less, and the dielectric loss (15 GHz) is 100%.
× 10 ⁻⁴ or less. In particular, the dielectric loss (15%) can be achieved by controlling the oxygen content to 0.5% by weight or less.
GHz) of 60 × 10 ⁻⁴ or less.

However, the average particle size of the AlN powder was smaller than 2 μm, and the average particle size of the AlN crystal particles in the glass ceramic was smaller than 2 μm. 1 or AlN content of 9
0% by weight of Sample No. In No. 11, sintering was not possible, and it was difficult to densify the glass ceramic to an open porosity of 1% or less, and water absorption caused deterioration in insulation and increased dielectric loss.

[0049]

As described above in detail, according to the glass ceramics of the present invention, the oxygen content in the AlN crystal particles dispersed as a filler in the glass ceramics is 0.8%.
By setting the content by weight or less, it is possible to produce a glass ceramic having a low dielectric constant and a low dielectric loss while having a high thermal conductivity, and is provided with a wiring circuit layer containing Cu or Ag as a main component, particularly for a high frequency. It can be suitably used as an insulating substrate of a wiring board.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view for explaining an example of a high-frequency wiring board according to the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 dielectric substrate 2 wiring circuit layer 2 a ground layer 2 b center conductor 3 via hole conductor 4 high frequency element

 ──────────────────────────────────────────────────続 き Continued on front page F-term (reference) 4G001 BA01 BA02 BA03 BA04 BA05 BA06 BA07 BA36 BA71 BA73 BB01 BB02 BB03 BB04 BB05 BB06 BB07 BB36 BB71 BB73 BC13 BC17 BC22 BC53 BD23 BE22 BE26 BE32 BE33 4G030 AA07 AA10 AA37 AA51 BA12 CA04 CA08 GA14 GA15 GA17 GA20 GA25 5E346 AA12 AA15 AA38 AA43 BB02 BB03 BB04 CC18 CC32 CC39 DD02 DD34 EE24 FF18 GG03 HH06 HH17

Claims (4)

[Claims] 1. A high-frequency wiring board having a wiring circuit layer for transmitting a high-frequency signal adhered to a surface or inside of a dielectric substrate, wherein the dielectric substrate comprises a glass component and a filler component. A high frequency component comprising a glass ceramic having a porosity of 1% or less, containing at least aluminum nitride crystal particles as the filler component, and having an oxygen content of 0.8% by weight or less in the aluminum nitride crystal particles. Wiring board. 2. The high-frequency wiring board according to claim 1, wherein the glass component contains 30 to 95% by weight and the filler component 5 to 70% by weight. 3. The high-frequency wiring board according to claim 1, wherein the aluminum nitride crystal particles have an average particle size of 2 μm or more. 4. The method according to claim 1, wherein the thermal conductivity is 5 W / m · K or more, the relative dielectric constant is about 8 or less, and the dielectric loss is about 100 × 10 ⁻⁴ or less near a measurement frequency of 15 GHz. 4. The high-frequency wiring board according to any one of 3.