JP3301914B2 - Wiring board - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wiring board in which a metallized wiring layer is formed on an insulating substrate made of alumina ceramics, and simultaneously sintering the insulating substrate and the metallized wiring layer at a low firing temperature in a short time. Suitable for various circuit boards having semiconductor element housing packages and circuit wiring conductors in which semiconductor elements are housed and mounted, and cellular phones, personal handy phone systems, high-frequency multilayer wiring boards for various satellite communications, etc. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wiring board suitable for a hybrid integrated circuit device or the like in which a semiconductor element can be compactly accommodated and mounted and various electronic components such as a capacitor and a resistor are mounted in addition to the semiconductor element.

[0002]

2. Description of the Related Art Conventionally, alumina ceramics have been
Because of its excellent properties such as electrical insulation and chemical stability, a package for housing semiconductor elements, and a hybrid integrated circuit device equipped with various electronic components such as capacitors or resistors in addition to semiconductor elements. Are widely used as insulating bases for various wiring boards.

A metallized wiring layer as a conductor for forming an electric circuit is formed on the surface or inside of the insulating base. For example, in a package for housing a semiconductor element, a semiconductor is provided on the bottom of a concave portion provided on the insulating base. The device is bonded and fixed, each electrode of the semiconductor device is electrically connected to the metallized wiring layer via a bonding wire, and a lid is bonded so as to cover the recess, so that the semiconductor device is recessed in the insulating base. It has been housed in a hermetically sealed manner as a semiconductor component as a final product.

In order to form a metallized wiring layer on the insulating substrate, a ceramic green sheet serving as the insulating substrate is prepared by adding an organic binder and a solvent to a refractory metal such as W or Mo by screen printing or the like. After applying the metallized paste in a predetermined pattern, it is laminated appropriately,
By holding the insulating substrate and the metallized wiring layer simultaneously in a reducing atmosphere at a temperature of about 1600 ° C. for several hours, a part of the liquid phase component interposed between the crystals of the alumina ceramics is converted into high melting point metal particles. In general, a method in which a metallized wiring layer and an insulating substrate are adhered and bonded by being diffused therebetween is generally adopted.

In recent years, a wiring board on which a semiconductor element such as an IC or an LSI, which has been operated at a higher frequency and a higher density, has a higher speed and a better heat dissipation, has a higher insulation resistance and a lower dielectric loss (tan δ). ) And the like, and furthermore, in order to mount the semiconductor element compactly, a flip chip connection method of directly connecting each electrode of the semiconductor element to a wiring electrode of a wiring board by a solder bump or the like is adopted. It is becoming.

For this reason, it is necessary to use alumina having higher purity as the insulating base, reduce the sintering aid as much as possible, increase the wiring density and increase the density, and realize a high-speed semiconductor device. It has been desired to reduce the liquid phase component added to the high melting point metal to form the metallized wiring layer in order to lower the wiring resistance, and to increase the bonding strength between the insulating base and the metallized wiring layer.

However, when the sintering aid for the insulating substrate and the liquid phase component of the metallized wiring layer are reduced, the wiring resistance is reduced, but the bonding strength between the two is reduced. Has to be increased, resulting in an increase in the firing cost.

In order to solve such a problem, there has been proposed a metallized composition in which Al ₂ O ₃ and Nb ₂ O ₅ or a compound thereof are added to the refractory metal (Japanese Patent Publication No. Sho 57-78). No. 10076, JP-A-63-
No. 107879).

[0009]

However, although the metallized composition has a sufficient adhesive strength even at a firing temperature of 1600 ° C. or lower and 1300 ° C., the firing time still requires several hours or more, and the metallized composition is required. Calcination raw material powders must be used as a raw material. Under the recent circumstances in which the model change and the time to market have been further shortened, there has been a problem that the demands for shorter delivery time and lower cost of the wiring boards used for them are not necessarily satisfied.

[0010]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and does not require complicated manufacturing steps such as calcination and pulverization. The semiconductor element can be housed compactly without deformation such as warpage or undulation, and various electronic components such as capacitors and resistors can be densely mounted in addition to the semiconductor element. It is an object of the present invention to provide a low-cost wiring board with a short delivery time, which is suitable for a multi-layer wiring board and a package for storing semiconductor elements, which is suitable for a semiconductor device mounted product in recent years.

[0011]

Means for Solving the Problems The present inventors have proposed that an insulating base made of alumina ceramics is made of a high melting point metal such as W or M.
As a metallized composition for forming a metallized wiring layer containing at least one of O as a main component, 0.5 to 10.0% by weight of Al ₂ O ₃ and 0.1 to 3.0% by weight of Nb
₂ O _5, and generates the Al ₂ O ₃ and liquid phases in the metallization composition in the temperature range of 1200 to 1600 ° C. Al ₂
It has been found that the object can be achieved by containing 0.01 to 10.0% by weight of a compound composed of two or more of O ₃ , SiO ₂ , MgO and CaO.

That is, the wiring board of the present invention comprises at least one of the refractory metals W and Mo, and comprises, in addition to Al ₂ O ₃ and Nb ₂ O ₅ forming a metallized composition, the Al ₂ O ₃ And 1
Al ₂ that forms a liquid phase in the temperature range of 200 to 1600 ° C.
It has a metallized wiring layer formed of a metallized composition containing 0.01 to 10.0% by weight of a compound composed of two or more of O ₃ , SiO ₂ , MgO and CaO. is there.

Further, in the wiring board of the present invention, it is more preferable that the compound is cordierite or anorthite.

[0014]

According to the present invention, W refractory metal in an insulating substrate made of alumina ceramics, as a main component one or more kinds of Mo, in addition to Al ₂ O ₃ and Nb ₂ O _5, the Al ₂ O ₃
A which forms a liquid phase in a temperature range of 1200 to 1600 ° C.
Since the metallized wiring layer was formed with a metallized composition containing a compound composed of two or more of l ₂ O ₃ , SiO ₂ , MgO and CaO, Al ₂ O ₃ in the metallized composition and The compound simultaneously forms a liquid phase,
The surface of the W or Mo particles of the high melting point metal is covered with the liquid phase to promote the rearrangement of the particles, further promote sintering, and enable short-time firing at a low temperature.

At the same time, the shrinkage of the alumina ceramic and the metallized composition is simultaneously started,
Deformation such as warpage or undulation of the insulating substrate is extremely small,
The alumina ceramics and the liquid phase components in the metallized composition react with each other to increase the adhesive strength.

On the other hand, since Mo and W of the high melting point metal in the metallized composition also become denser, the wiring resistance of the metallized wiring layer also decreases.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a wiring board according to the present invention will be described in detail.

As the refractory metal in the metallized composition of the present invention, either W or Mo may be used, or both may be mixed.

Conventionally, W has been generally used as a metallizing composition for co-firing. However, in the case of an insulating substrate having excellent high-frequency characteristics, the metallizing composition has high sinterability and the metallized wiring layer is easily densified. From that point, Mo has a lower melting point and higher sinterability than W,
It has excellent characteristics as a metallized wiring layer of an insulating substrate made of alumina ceramics having excellent high frequency characteristics.

Further, the metallized composition of the present invention is characterized in that the refractory metal powder having an average particle size of 2 to 3 μm is added to Al ₂ O ₃
And Nb ₂ O ₅ , the Al ₂ O ₃ and 1200 to 160
Al ₂ O ₃ , Si which forms a liquid phase in a temperature range of 0 ° C.
A compound comprising at least two of O ₂ , MgO and CaO, wherein the content of Al ₂ O ₃ is 0.5% by weight.
If it is less than 1600 ° C., a liquid phase will not be formed with the compound at a low temperature of 1600 ° C. or less. If it exceeds 10.0% by weight, the surface of the metallized wiring layer will be covered with a ceramic layer mainly composed of Al ₂ O _3. A uniform plating film cannot be formed by the plating process in the process, the bonding strength between the plating coating layer and the metallized wiring layer decreases, and the wiring resistance increases.

Therefore, the content of Al ₂ O ₃ is 0.5
1.0 to 3.0% by weight in terms of adhesion strength and wiring resistance between the insulating base and the metallized wiring layer, and between the metallized wiring layer and the plating coating layer. It is.

Next, the Nb ₂ O ₅ is a component for improving the wettability between the high melting point metal and the glass component. When the content is less than 0.1% by weight, the high melting point metal and the glass component are used. The wettability with the component is only partially improved, and the bonding strength to the insulating substrate is reduced. When the content exceeds 3.0% by weight, the adhesion between the insulating substrate and the metallized wiring layer is hindered, and the high melting point metal is prevented. In addition, since Nb ₂ O ₅ is excessively present around the glass component, the bonding strength is deteriorated and the wiring resistance is increased.

Therefore, the content of Nb ₂ O ₅ is 0.1 to
From the viewpoint that the wettability between the high-melting point metal and the glass component becomes more uniform, it is specified to be 3.0 to 2.0% by weight.
0% by weight is more desirable.

On the other hand, Al ₂ O ₃ in the metallized composition and Al which forms a liquid phase in a temperature range of 1200 to 1600 ° C.
_If the content of the compound consisting of two or more of ₂ O ₃ , SiO ₂ , MgO and CaO is less than 0.01% by weight, the amount of liquid phase interposed between the high melting point metal particles is insufficient.
The sintering of the high melting point metal particles is hindered, so that the bonding strength with the insulating base is reduced and the wiring resistance is increased.

If the content exceeds 10.0% by weight, the surface of the metallized wiring layer is covered with a glass component.
The bonding strength between the plating coating layer and the metallized wiring layer is reduced, and the wiring resistance is increased, which does not satisfy the requirements as a wiring board.

Therefore, the content of the compound is 0.01
-10.0% by weight, from the viewpoint of sintering of the high melting point metal and plating coverage on the surface of the metallized wiring layer.
More preferably, the content is from 0.5 to 2.0% by weight.

The above Al ₂ O ₃ , SiO ₂ , Mg
O, a compound of two or more of CaO, Al ₂ O
Compounds having a liquid phase formation temperature of less than 1200 ° C with ₃ have a sintering start temperature of alumina ceramics of 1200 to 130.
Since the temperature is 0 ° C., the liquid phase component of the compound diffuses to the alumina ceramics side. On the other hand, if the liquid phase generation temperature exceeds 1600 ° C., the firing cost increases, which is undesirable. Since the sintering temperature of the ceramic is 1450 to 1600 ° C., the metallized composition is not densified, the resistance of the metallized wiring layer is increased, and the loss is increased. The strength is reduced, and the effect of adding the compound is lost.

Therefore, the liquid phase formation temperature range is 1200
１1600 ° C., especially 1200-1400
C is most preferred.

Compounds satisfying the above-mentioned conditions include mullite (3Al ₂ O ₃ .2SiO ₂ ), spinel (MgO.Al ₂ O ₃ ), and gehlenite (2CaO.A).
l ₂ O ₃ · SiO ₂ ), Rankinite (3CaO · 2S)
iO ₂ ), protoenstatite (MgO.Si)
O ₂ ), cordierite (2MgO.2Al ₂ O ₃ .5)
SiO ₂ ), anorthite (CaO.Al ₂ O ₃ .2S)
iO ₂₎ and forsterite (2MgO · SiO _2), and the like, Al ₂ in the temperature range of 1200 to 1400 ° C.
As the compound that forms a liquid phase with O ₃ , cordierite (2MgO.2Al ₂ O ₃ .5SiO ₂ ) and anorthite (CaO.Al ₂ O ₃ .2SiO ₂ ) are most suitable.

If the particle size of the compound is larger than the particle size of the high melting point metal, the compound will not be uniformly dispersed among the particles of the high melting point metal. As a result, the wettability of the high melting point metal will be insufficient. Since the penetration of the glass component between the high melting point metal particles becomes partial, the adhesive strength between the insulating base and the metallized wiring layer is deteriorated, and the wiring resistance tends to increase.
The particle size of the compound is desirably equal to or smaller than the particle size of the high melting point metal.

Further, by specifying the amount of the compound contained in the metallized composition and the temperature range in which a liquid phase is formed with Al ₂ O ₃ in the metallized composition, the heat shrinkage between the insulating substrate and the metallized wiring layer is determined. Of the wiring board is prevented from being deformed due to a difference in shrinkage during the firing process, and unnecessary stress generated due to the difference in shrinkage is also reduced. As a result, the metallized wiring The layer can be firmly adhered to the insulating substrate.

In addition, as an insulating base which can suitably use the metallized composition applied to the wiring board of the present invention, when this wiring board is used as a substrate for a high frequency band of 1 to 100 GHz,
The dielectric loss tangent (tan δ) in the 1 to 10 GHz band is 1
Since it is necessary to obtain a value in the vicinity of × 10 ^-3 or less, it is more preferable to use a high-purity alumina sintered body.

Further, when the purity of the inorganic component, particularly Al ₂ O _{3 in} the metallized composition is made 99.9% or more, the Al
₂ interface O ₃ and the insulating substrate of the Al ₂ O ₃ is formed by sintering, further contributes to the tightness becomes what enables high intensity purity.

Further, the metallized composition can form an alumina sintered body and a metallized wiring layer by simultaneous sintering when manufacturing a wiring board using high-purity alumina ceramics as an insulating base. It becomes easy to make the substrate a multilayer wiring.

Next, a method of manufacturing a wiring board using the above metallized composition and using alumina ceramics as an insulating substrate will be described. First, Si _{2 was} added to the Al ₂ O ₃ raw material powder.
A slurry is prepared by adding and mixing a solvent and the like to a mixture obtained by adding and mixing a sintering aid such as O ₂ , MgO, and CaO, and the slurry is prepared by a doctor blade method, a calendar roll method, a rolling method, or the like.
Alternatively, the mixed powder is press-molded into a sheet having an appropriate thickness to produce a green sheet.

On the other hand, as a main component a high melting point metal, Al ₂ O
₃ and Nb ₂ O ₅ , and Al ₂ O ₃ , SiO ₂ , MgO,
A mixed powder of a metallized composition containing a compound composed of two or more kinds of CaO is mixed with a known binder such as an acrylic resin, ethyl cellulose and nitrocellulose, and a known plasticizer such as dibutyl phthalate, if necessary. A metallizing paste is prepared by appropriately adding and mixing a foaming agent, a surfactant and the like with a solvent.

The metallized paste is printed in a wiring pattern on the surface of the green sheet by a screen printing method, a gravure printing method, or the like, and a through hole is formed in the green sheet. After filling, a plurality of green sheets are laminated and integrated.

The laminate thus obtained is placed in a reducing atmosphere, preferably in a humidified nitrogen-hydrogen mixed atmosphere, for 145 minutes.
By firing at a temperature of 0 to 1600 ° C. and simultaneously firing the green sheet and the metallized paste, a multilayer wiring board can be manufactured.

The metallized wiring layer exposed on the surface of the wiring substrate and the surface of the wiring layer to which the connection fitting is attached are provided with an improved corrosion resistance or an improved wettability with a brazing material or solder to improve the bonding strength. Nickel (N
i) a metal having good conductivity and excellent corrosion resistance, such as gold (Au), having a thickness of 0.1 to 10 by means such as electrolytic plating and electroless plating;
It may be formed with a thickness of μm.

[0040]

EXAMPLES Hereinafter, the metallized composition of the present invention and a wiring board using the same will be described in detail with reference to examples.

First, W and Mo powders having an average particle diameter of 1 to 3 μm, Al ₂ O ₃ and N
b ₂ O ₅ , Al ₂ O ₃ , SiO ₂ , MgO, CaO
Are weighed at the ratios shown in Tables 1 to 3 respectively, and a known organic binder and an organic solvent are added thereto, and the mixture is kneaded with a kneader for 10 hours to form a paste-like metallization. A sample was prepared.

On the other hand, as alumina molded body for insulating substrate, the Al ₂ O ₃ 92 wt%, SiO _2, MgO, Ca
A sintering aid composed of O or the like is added in a total amount of 8% by weight, and an organic binder, a plasticizer, and a solvent are added thereto to prepare a slurry. The slurry is formed to a thickness of about 30 by the known tape forming method.
A 0 μm ceramic green sheet for an insulating substrate was formed.

As the metallized composition, the above Al ₂
Comparative examples were those containing no compound composed of two or more of O ₃ , SiO ₂ , MgO and CaO, and those containing periklase (MgO) having a liquid phase formation temperature exceeding 1600 ° C.

The above Al ₂ O ₃ , SiO ₂ , Mg
The liquid phase formation temperature of the compound composed of two or more of O and CaO is determined by firing a mixed powder of the compound and the Al ₂ O ₃ raw material powder at various temperatures assumed from the respective phase diagrams. The formation was visually inspected and also checked with a scanning electron microscope to confirm the liquid phase formation temperature.

[0045]

[Table 1]

[0046]

[Table 2]

[0047]

[Table 3]

The thus obtained metallizing sample was printed on one outer surface of the ceramic green sheet cut into a rectangular shape by a screen printing method with a rectangular shape having a length of 3 mm and a width of 24 mm and a resistance measurement pattern.
In a reducing atmosphere consisting of a mixed gas of nitrogen and hydrogen,
Simultaneous firing at a temperature of 1600 ° C. yielded a wiring board for evaluation in which a metallized wiring layer having a thickness of about 20 μm was formed on the surface of an insulating substrate made of an alumina sintered body.

Using the wiring board for evaluation thus obtained, the outer surface of the metallized wiring layer of the wiring board is coated with Ni, and an iron-nickel-based lead pin is formed on the Ni coating layer.
After joining with a silver brazing at a temperature of 800 to 900 ° C., the lead pin was pulled at a pulling speed of 10 mm / min, and the load when the lead pin was peeled was evaluated as the metallized strength.

Next, the electric resistance at both ends of the metallized wiring layer of the resistance measuring pattern formed on the wiring substrate is measured by an electric resistance measuring device by a four-terminal method, and the shape and dimensions of the metallized wiring layer are measured by a measuring microscope. At the same time, the width and thickness were measured with a contact-type surface roughness meter equipped with a diamond needle, the specific resistance was calculated, and the wiring resistance was evaluated.

Further, the center of the surface of the wiring board is stapled in a diagonal direction with the contact type surface roughness meter to measure the warp shape, and the warp per unit length (μm / mm) is calculated. The maximum value was evaluated as flatness.

[0052]

[Table 4]

[0053]

[Table 5]

[0054]

[Table 6]

As is apparent from the above results, Al ₂ O
_In Sample Nos. 16, 63 and 89 of Comparative Examples which do not contain a compound that forms a liquid phase with ₃ , the baking time is as long as 120 minutes, and the temperature at which the liquid phase is formed is 1600.
In the sample numbers 49, 76, and 102 of the comparative examples exceeding ℃,
Although the baking time is short, the metallization strength is 4.2 kgf
And the wiring resistance is as high as 3.4 × 10 ⁻⁵ Ωcm or more, and the flatness is 1.10 μm per unit length (mm).
m and extremely bad.

Also, sample numbers 1, 8, 9, 15, 25, 26, 31, 3 outside the claims of the present invention other than the comparative examples.
2, 37, 42, 50, 56, 57, 62, 68, 7
In 3, 77, 82, 83, 88, 94, and 99, the metallization strength is 5 kgf or less, and the wiring resistance is 3.0.
× 10 ⁻⁵ Ωcm or more, and flatness is 1.05 μm
/ Mm or more, or not satisfying all the characteristics.

On the other hand, all of the samples of the present invention can be fired in a short time, and the metallization strength, wiring resistance,
It can be seen that all of the flatness are satisfactory.

[0058]

As described in detail above, the wiring board of the present invention contains one or more of high melting point metals W and Mo as main components,
0.5 to 10.0% by weight of Al ₂ O ₃ and 0.1 to 3.0%
Al ₂ O ₃ to generate the Al ₂ O ₃ and a liquid phase at a temperature range of weight% of Nb ₂ O _5, and 1200 to 1600 ° C., S
Since it has a metallized wiring layer formed of a metallized composition containing 0.01 to 10.0% by weight of a compound composed of two or more of iO ₂ , MgO and CaO, it becomes complicated such as calcination and pulverization. It does not require a complicated manufacturing process, can simultaneously sinter an insulating substrate made of alumina ceramics and a metallized wiring layer having low electrical resistance and high airtightness at a low temperature and in a short time, has low manufacturing costs, and has warpage and undulation. The semiconductor element can be compactly accommodated and mounted, such as a package for semiconductor element storage, various circuit boards, a multilayer wiring board for high frequency, etc., and various electronic components such as capacitors and resistors can be densely packed. It is possible to provide a low-cost, highly reliable wiring board with a short delivery time that can respond to the recent situation of products equipped with semiconductor devices that can be mounted on That.

Claims (2)

(57) [Claims] 1. An insulating substrate made of alumina ceramics is coated on a high melting point metal such as tungsten (W) and molybdenum (M).
o) a wiring board on which a metallized wiring layer containing at least one of the main components is formed, wherein the metallized composition for forming the metallized wiring layer is 0.5 to 10.0% by weight of alumina (Al ₂ O). ₃₎ 0.1 to 3.0 wt% of niobium oxide (Nb ₂ O _5), and the alumina in a temperature range of 1200 to 1600 ° C. (Al ₂ O ₃₎ and alumina to produce a liquid phase (Al ₂ O ₃ ) A wiring board comprising 0.01 to 10.0% by weight of a compound composed of two or more of silica (SiO ₂ ), magnesia (MgO) and calcia (CaO). 2. The wiring board according to claim 1, wherein said compound is cordierite or anorthite.