JP3420424B2 - 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 base made of alumina ceramics, and the insulating base and the metallized wiring layer can be simultaneously fired to accommodate a semiconductor element. Suitable for semiconductor element storage packages and various circuit boards having circuit wiring conductors, and cellular phones, personal handyphone systems, high-frequency multilayer wiring boards for various satellite communications, etc. Especially, semiconductor elements can be compactly accommodated and mounted. The present invention relates to a wiring board having good flatness that enables various electronic components such as capacitors and resistors to be densely mounted in addition to semiconductor elements.

[0002]

2. Description of the Related Art Conventionally, alumina ceramics have been
A semiconductor element housing package that houses a semiconductor element because of its excellent properties such as electrical insulation and chemical stability, and a hybrid integrated circuit device that mounts various electronic components such as capacitors and resistors in addition to the semiconductor element It is often used as an insulating substrate for various wiring boards.

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

In order to form a metallized wiring layer on such an insulating substrate, a metallizing paste containing a high melting point metal such as W or Mo as a main component is formed into a predetermined pattern on the surface of the ceramic green sheet to be the insulating substrate by a screen printing method or the like. After coating, laminate appropriately and in a reducing atmosphere, 1450 to 1
A method in which a part of the liquid phase component of the alumina-based ceramic is diffused between the particles of the refractory metal by simultaneous firing at a temperature of 700 ° C. to adhere and bond the metallized wiring layer and the insulating substrate is generally adopted. .

In recent years, a wiring board on which semiconductor elements such as ICs and LSIs, which are becoming higher in frequency and higher in density, are mounted, which makes the semiconductor elements faster and radiates better, has a higher insulation resistance and a lower dielectric loss (tan δ). ), Etc. are required, and in addition, in order to mount the semiconductor element compactly, a flip chip connection method or the like is used in which each electrode of the semiconductor element is directly connected to the wiring electrode of the wiring board by a solder bump or the like. Is starting to appear.

Therefore, as the insulating substrate, alumina of higher purity is used, the sintering aid is reduced as much as possible, and a high degree of flatness is required for the wiring board adopting the flip chip connection method or the like. Therefore, various methods such as making the density of the laminate constituting the wiring board and the temperature distribution during firing uniform have been taken for that purpose.

However, as described above, high-purity alumina is used to reduce the sintering aid, and the wiring density is increased to increase the wiring density on the ceramic green sheet.
When forming a metallized wiring layer in which the liquid phase component added to the refractory metal is reduced because it is necessary to lower the wiring resistance in order to realize high-speed semiconductor devices, the absolute amount of the liquid phase component interposed between the alumina crystals is Since the amount is small, there is a problem that the metallized wiring layer has poor sinterability and becomes porous, making it difficult to firmly bond the metallized wiring layer to the insulating substrate.

Moreover, when the insulating substrate and the metallized wiring layer are fired at the same time, since the respective sintering starting points are different from each other, the wiring board is deformed such as warping or waviness due to the shrinkage deviation in the firing process. , For example, warpage causes deformation of 1.06 μm or more per 1 mm of the length of the wiring board surface,
It has been difficult to obtain a high-quality wiring board having good flatness with a good yield.

In order to solve such a problem, therefore, a metallized composition obtained by adding Al ₂ O ₃ --MnO--SiO ₂ type glass to the refractory metal is used for an alumina sintered body, or a jig is used. Various proposals have been made, such as a method of straightening by calcination or a method of pre-calcining at a temperature lower than the calcination temperature of the insulating substrate and then carrying out a main calcination by applying a load (Japanese Patent Laid-Open No. Hei 2).
-30688, Japanese Patent Publication No. 2-25277, and Japanese Patent Laid-Open No. 4-31368).

[0010]

However, when the metallized composition is printed and co-fired on a ceramic green sheet containing alumina as a main component and the addition amount of a sintering aid is reduced, the metallized wiring is not formed. Although the adhesive strength between the layer and the insulating substrate can be obtained, there remains a problem that deformations such as warpage and waviness caused by a difference in thermal contraction between the layers cannot be completely eliminated.

Further, although the method of straightening using a jig and the method of firing with a load reduce deformation such as warpage and waviness of the wiring board, the jig is complicated to handle and the cure is required. There is a problem in that the manufacturing cost is significantly increased due to the maintenance and management of the ingredients and the need for a plurality of steps.

[0012]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and an insulating substrate made of alumina ceramics and a metallized wiring layer can be simultaneously fired without the need for a firing jig or a plurality of firing steps. The cost is low, and deformation such as warpage and undulation can be effectively prevented. In particular, semiconductor elements such as multilayer wiring boards and packages for accommodating semiconductor elements can be compactly accommodated and mounted. An object of the present invention is to provide a wiring board on which various electronic components such as a body can be densely mounted.

[0013]

DISCLOSURE OF THE INVENTION The inventors of the present invention have found that an insulating substrate made of alumina ceramics has a high melting point of W or M.
In a metallized composition for forming a metallized wiring layer containing at least one of o as a main component, CaO-Al which forms a liquid phase with SiO _{2 in} alumina ceramics forming an insulating substrate in a temperature range of 1200 to 1600 ° C. ₂ O ₃ -SiO
It has been found that the above object can be achieved by containing a ₂ type compound.

That is, the wiring board of the present invention is made of alumina 90.
˜96 wt%, SiO ₂ , MgO, C as sintering aids
Alumina-based ceramics containing 4 to 10% by weight of aO
A refractory metal tungsten (W)
Metallic containing one or more of molybdenum (Mo) as a main component
A wiring board having a wiring layer
The metallization composition for forming the wiring layer is 1200-
Alumina ceramics that form an insulating substrate in the temperature range of 1600 ° C
Calcium that forms a liquid phase with silica (SiO ₂ ) in the mix
Shear (CaO) - alumina _(Al 2 _{O 3)} - silica (S
iO ₂₎ based compound containing 0.05 to 10.0 wt%
It is characterized by being formed.

Further, the wiring substrate of the present invention is CaO-Al.
₂ O ₃ -SiO ₂ type compounds CaO · Al ₂ O ₃ · 2S
It is more desirable is iO ₂ or _{2CaO · Al 2 O 3 · SiO} 2.

[0016]

According to the present invention, an insulating substrate made of alumina ceramics contains Si or Si contained in the alumina ceramics as a main component and contains at least one of refractory metals W and Mo.
Since the metallized wiring layer is formed by the metallized composition containing CaO—Al ₂ O ₃ —SiO ₂ -based compound that forms a liquid phase with O ₂ , the sintering aid component in the alumina ceramic is liquid. At the temperature at which the phase is formed, the CaO—Al ₂ O ₃ —SiO ₂ -based compound in the metallized composition also simultaneously forms a liquid phase, and the contraction of the alumina ceramics and the metallized composition is simultaneously started. Deformation of the insulating substrate such as warpage and waviness is extremely reduced, and S of the liquid phase component of the alumina ceramics is
The iO ₂ and the liquid phase components in the metallized composition react with each other to further increase the adhesive strength.

On the other hand, since the refractory metals Mo and W in the metallized composition are also densified, the wiring resistance of the metallized wiring layer is also reduced.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION The wiring board of the present invention will be described in detail below.

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

Conventionally, W has been generally used as a co-firing metallizing composition. However, in an insulating substrate having excellent high frequency characteristics, the metallizing composition has high sinterability and the metallized wiring layer is easily densified. Desirably, 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.

In addition, the metallized composition of the present invention is prepared by adding CaO-A to the refractory metal powder having an average particle diameter of 2 to 3 μm.
The content of the l ₂ O ₃ —SiO ₂ compound is 0.05 to 1
When the content is less than 0.05% by weight, the sintering of the refractory metal becomes insufficient, the resistance of the metallized wiring layer becomes large, and the loss becomes large. Since the electrical characteristics are deteriorated, it is not suitable for forming a wiring layer, and when the content exceeds 10.0% by weight, the grain growth of the refractory metal is excessively promoted, and the liquid phase component in the metallized composition is alumina ceramics. By being discharged to the side, the adhesiveness between the insulating substrate and the metallized wiring layer becomes insufficient and the adhesive strength decreases.

Therefore, from the viewpoint of ensuring low wiring resistance of the metallized wiring layer and sufficient adhesive strength, CaO
The content of the —Al ₂ O ₃ —SiO ₂ compound is 0.05
˜5.0 wt% is more desirable, and especially 0.1˜2.0 wt% is most desirable.

Next, the CaO--Al ₂ O ₃ --SiO ₂
The system compound is limited to a liquid phase formation temperature of 1200 to 1600 ° C. with SiO ₂ in the alumina-based ceramics forming the insulating substrate.
When the temperature is lower than 0 ° C, the sintering start temperature of the alumina ceramics is 1200 to 1300 ° C, and therefore CaO-
If the liquid phase component of the Al ₂ O ₃ —SiO ₂ compound diffuses to the alumina ceramics side, and if the liquid phase generation temperature exceeds 1600 ° C., the firing temperature of the alumina ceramics is 1450 to 1600 ° C. Therefore, the metallized composition is not densified, the resistance of the metallized wiring layer is increased and the loss is increased, and the electrical characteristics are deteriorated, and the adhesive strength with the insulating substrate is reduced. The effect of adding the —Al ₂ O ₃ —SiO ₂ compound disappears.

Therefore, the liquid phase formation temperature is 13 from the above viewpoint.
00 to 1600 ° C. is desirable, especially 1300 to 15
Most preferred is 00 ° C.

As described above, the amount of CaO--Al ₂ O ₃ --SiO ₂ -based compound contained in the metallized composition and the temperature range for forming a liquid phase with SiO ₂ in the alumina-based ceramic of the insulating substrate are specified. By this, the matching of the heat shrinkage between the insulating substrate and the metallized wiring layer is improved, deformation of the wiring board such as warpage and waviness due to the shrinkage difference in the firing process is prevented, and the shrinkage difference occurs. Unnecessary stress is also relaxed, and as a result, the metallized wiring layer can be firmly adhered to the insulating substrate.

As an insulating substrate for which the metallized composition applied to the wiring board of the present invention can be preferably used, alumina is used.
90 to 96% by weight of SiO ₂ , Mg as a sintering aid
Alumina cerami containing 4 to 10% by weight of O and CaO
X is used.

Further, when the purity of the inorganic component, especially 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.

Moreover, the metallized composition is made of aluminum.
When manufacturing a wiring board using an alumina-based ceramic having an aluminum content of 90 to 96% by weight as an insulating base, the alumina-based sintered body and the metallized wiring layer can be formed by simultaneous firing, so that the multilayer wiring of the wiring board is formed. Can be realized.

Next, a method for manufacturing a wiring board using the above metallized composition and using alumina ceramics as an insulating substrate will be described. First, the Al ₂ O ₃ raw material powder was converted into Si.
O _2, MgO, to which was added and mixed sintering aid such as CaO, the mud was prepared by adding a mixture of solvents, etc., which a doctor blade method, calender roll method, rolling method, etc.,
Alternatively, the mixed powder is press-molded into a sheet having an appropriate thickness to produce a green sheet.

On the other hand, the above-mentioned Ca
O-Al ₂ O ₃ -SiO ₂ compound-containing powder mixed metallized composition, a known binder such as acrylic resin, ethyl cellulose, nitrocellulose, a known plasticizer such as dibutyl phthalate, other defoaming agent, A metallizing paste is prepared by appropriately adding and mixing a surfactant and the like together with a solvent.

Then, the metallizing paste is printed on the surface of the green sheet in the form of a wiring pattern by a screen printing method, a gravure printing method or the like, at the same time a through hole is formed in the green sheet, and the metallizing paste is also formed in the through hole. After filling with, a plurality of green sheets are laminated and integrated.

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

The metallized wiring layer exposed on the surface of the wiring board and the surface of the wiring layer on which the metal fittings are mounted are improved in corrosion resistance and wettability with brazing material and solder to improve the bonding strength. Nickel (N
i), a metal such as gold (Au) having good electrical conductivity and excellent corrosion resistance, by means of electrolytic plating, electroless plating or the like.
It may be formed with a thickness of μm.

[0034]

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

First, W and Mo powders having an average particle size of 1 to 5 μm, and CaO—Al ₂ O ₃ —Si having various compositions are used.
O ₂ type compounds were weighed in the ratios shown in Tables 1 to 3, and a known organic binder and organic solvent were added thereto and kneaded by a kneader to prepare a paste-like metallizing sample.

On the other hand, as an alumina-based compact for an insulating substrate, Al ₂ O _{3 of} 90 to 96% by weight, SiO ₂ , Mg
A sintering aid composed of O, CaO, etc. is added in a total amount of 4 to 10% by weight, and an organic binder, a plasticizer and a solvent are added thereto to prepare a slurry, and the slurry is thickened by the above-mentioned known tape forming method. A ceramic green sheet for an insulating substrate having a size of about 500 μm was formed.

As a sample for metallization, C contained
_{aO-Al 2 O 3 11CaO ·} 4Al 2 O 3 · 15 is a liquid phase generating temperature of -SiO ₂ based compound is less than 1200 ° C.
SiO ₂ and C whose liquid phase formation temperature exceeds 1600 ° C.
A comparative example was prepared by adding aO.Al ₂ O ₃ .99SiO ₂ .

Further, the liquid phase generation temperature of the CaO-Al ₂ O ₃ -SiO ₂ based compound, the raw material mixed powder CaO-Al ₂
The liquid phase formation temperature was specified by visually inspecting the formation of the liquid phase by firing at various temperatures assumed from the O ₃ —SiO ₂ ternary phase diagram and also by inspecting with a scanning electron microscope.

[0039]

[Table 1]

[0040]

[Table 2]

[0041]

[Table 3]

The thus-obtained metallizing sample was printed on one entire outer surface of the ceramic green sheet or on a predetermined wiring pattern by a screen printing method, and a plurality of these layers were laminated and pressure-bonded to each other, and then the laminated body was formed. Is cut into a rectangular shape with a length of 50 mm and a width of 20 mm, and this is cut in a reducing atmosphere consisting of a mixed gas of nitrogen and hydrogen for 1,500
Simultaneous firing was performed at a temperature of ˜1600 ° C. to produce a wiring board for evaluation in which an insulating substrate surface made of an alumina-based sintered body and a metallized wiring layer having a thickness of about 20 μm were formed on the surface of the insulating substrate.

Using the thus-obtained wiring board for evaluation, the central portion of the surface of the wiring board, about 20 mm square, was touched diagonally with a contact type surface roughness meter equipped with diamond needles to form a warped shape. Measured and warped per unit length (μm
/ Mm) was calculated and the maximum value was evaluated as flatness.

Next, the electric resistance value of the metallized wiring layer of the wiring board was measured with an electric resistance measuring device by the 4-terminal method, and the specific resistance value was calculated from the shape dimension of the metallized wiring layer to evaluate the wiring resistance. .

The surface of the metallized wiring layer of the wiring board is coated with Ni, and an iron-nickel lead pin is bonded on the Ni coating layer with silver solder at a temperature of 800 to 900 ° C. Was pulled at a pulling speed of 10 mm / min, and the load when the lead pin was peeled off was evaluated as the metallization strength.

[0046]

[Table 4]

[0047]

[Table 5]

[0048]

[Table 6]

As is clear from the results of Tables 4 to 6,
Comparative sample numbers 25, 51, 52, 71, 72, 7
In Nos. 9 and 80, the warp was 1.06 μm / mm or more, and the metallization strength was as low as 4.4 kgf or less.
In 6, the warp is 1.05 μm / mm, which is slightly small, but
The metallization strength is as weak as 4.2 kgf.

Further, sample numbers 1 and 1 in which the content of the CaO--Al ₂ O ₃ --SiO ₂ compound is less than the lower limit of the present invention.
3, 27, 39, 53, 60 and the sample numbers 12, 38, 59, 66 exceeding the upper limit have a warp of 1.06 μ.
The metallization strength was 4.8 kgf or less at m / mm or more, and in the sample numbers 20 and 46 exceeding the upper limit, the warpage was 1.
The metallization strength is 4.4 kgf or less, which is slightly insufficient, although it is slightly small at 05 μm / mm.

On the other hand, it can be seen that all the samples of the present invention are 1.05 μm / mm or less and have a metallizing strength of 4.9 kgf or more, which are in close contact with each other.

[0052]

As described in detail above, the wiring board of the present invention contains, as a main component, one or more of refractory metals W and Mo.
In the temperature range of 200 to 1600 ° C., the CaO—Al ₂ O ₃ —SiO ₂ -based compound that forms a liquid phase with SiO ₂ contained in the alumina-based ceramics that forms the insulating base is 0.0
Since it has a metallized wiring layer formed of a metallized composition containing 5 to 10.0% by weight, it does not require a firing jig or a plurality of firing steps, and has an insulating base made of alumina ceramics and a low electric resistance. A metallized wiring layer with high airtightness can be co-fired at a low manufacturing cost, and deformation such as warpage and undulation can be effectively prevented, and a semiconductor element storage package, various circuit boards, and high frequency It is possible to obtain a highly reliable wiring board such as a multi-layer wiring board for use in which a semiconductor element can be accommodated and mounted compactly, and various electronic components such as a capacitor and a resistor can be densely mounted in addition to the semiconductor element.

Claims (2)

(57) [Claims] 1. A sintering aid in 90 to 96% by weight of alumina.
Then, add SiO ₂ , MgO, and CaO in an amount of 4 to 10% by weight.
A wiring board having a metallized wiring layer containing at least one of refractory metals such as tungsten (W) and molybdenum (Mo) as a main component on an insulating substrate made of alumina ceramics for forming the metallized wiring layer. The metallized composition of (1) has a silica (SiO 2) content in an alumina ceramic forming an insulating substrate in the temperature range of 1200 to 1600 ° C.
₂₎ and to produce a liquid phase calcia (CaO) - alumina _(Al 2 _{O 3)} - silica (SiO ₂₎ compound 0.0
A wiring board comprising 5 to 10.0% by weight. 2. The calcia (CaO) -alumina (Al
_{The 2} O ₃ ) -silica (SiO ₂ ) based compound is anorthite (CaO.Al ₂ O ₃ .2SiO ₂ ) or grenite (2CaO.Al ₂ O ₃ .SiO ₂ ). Wiring board.