JPH09135059A - Wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable the deformation s such as warp and wave on the surface of insulating base substance of a wiring board to be minimized by a method wherein a wiring conductor contains luthenium and molybdenum within a specific range as high melting point metallic compounds as well as alumina within a specific range in a glass component. SOLUTION: Within a wiring board 1, 30-70wt.% of luthenium and molybdenum as high melting point metallic components as well as a wiring conductor 3 containing 5-20wt.% of alumina to 100wt.% of high melting point metallic component are integrally formed on an insulating base substance 2 made of alumina sintered body. Through these procedures, in case of forming the wiring board 1, the deformation such as warp and wave due to the difference in the thermal expansion coefficients between the wiring conductor 3 and the insulating base substance 2 can be minimized, resultantly flattening the surface of the insulating base substance 2 after the integration by baking step thereby enabling the excellent dimensional precision to be given.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is suitable for a semiconductor element housing package in which a semiconductor element is housed and mounted, and a hybrid integrated circuit device in which various electronic components such as capacitors and resistors are mounted in addition to the semiconductor element. The present invention relates to a flexible wiring board.

[0002]

2. Description of the Related Art Conventionally, a wiring board used for a package for housing a semiconductor element, a hybrid integrated circuit device or the like generally uses an insulating base made of an electrically insulating ceramic sintered body such as an alumina sintered body. A plurality of wiring conductors made of a refractory metal such as tungsten (W), molybdenum (Mo), manganese (Mn), and the like, from the periphery to the lower surface of the concave portion provided at substantially the center of the substrate, or to the inside and the surface thereof. And a structure in which the wiring conductors are connected by through-hole conductors made of the same high melting point metal provided in the insulating base.

In the wiring board constructed as described above, for example, in a package for housing a semiconductor element, the semiconductor element is adhered and fixed to the bottom surface of the recess of the insulating substrate via an adhesive such as glass, resin, or brazing material. At the same time, each electrode of the semiconductor element is electrically connected to a wiring conductor located around the recess via a bonding wire, and a lid made of metal or ceramics is sealed in the same manner as the adhesive so as to close the recess. The semiconductor device as the final product is obtained by joining the semiconductor elements through the materials and hermetically housing the semiconductor element in the recess of the insulating base.

However, on a wiring board on which semiconductor elements such as ICs and LSIs, which have become higher in frequency and higher in density in recent years, are mounted, fine wiring patterns having a higher density than in the past are formed, and moreover, the semiconductor elements are made compact. In order to mount the semiconductor device on the wiring board, a flip chip connection method has been adopted in which the surface electrode of the semiconductor element is directly connected to the wiring electrode of the wiring board by solder bumps or the like. Is required.

In order to obtain a wiring board having high flatness as described above, various methods such as making the density of the laminate and the temperature distribution during firing uniform have been studied. Since the thermal expansion coefficients of the sintered body and the wiring conductor are essentially different, warpage and undulation occur on the wiring board due to shrinkage during the firing process, and high-quality wiring boards with good flatness and good yield can be obtained. There was a problem that it was difficult to obtain.

Therefore, in order to solve such a problem, a straightening method using a jig or pre-firing in a temperature range higher than the softening temperature of the inorganic material and lower than the firing temperature of the ceramic substrate is applied, and then a load is applied to the main body. A firing method and the like have been proposed (JP-A-4-31368, Japanese Patent Publication No. 25257/1990).
Reference).

[0007]

However, in the straightening method using the jig as described above, the ceramic sintered body which has been once fired is refired, while on the other hand, after the preliminary firing, a load is applied to the ceramic sintered body. Even if the firing method is used, the firing steps are also increased, which greatly increases the manufacturing cost and impairs the economical efficiency, and each time, a complicated step of uniformly applying a load with a jig or the like must be performed. Therefore, the workability becomes extremely poor.

Further, if some kind of weight or jig is used to apply a load, the surface condition of the weight or jig is transferred to the contact surface of the multilayer wiring board to form a dent or a scratch on the surface. There are various problems such as the possibility that the wiring pattern may be disconnected and the high-density wiring pattern may be broken or short-circuited.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and an object thereof is to minimize the deformation such as warping or waviness on the surface of an insulating substrate of a wiring board having a wiring conductor therein.
An object of the present invention is to provide a wiring board having good dimensional accuracy and excellent mass production effect.

[0010]

In the wiring board of the present invention, the wiring conductor integrally formed on the insulating base body made of the alumina sintered body contains ruthenium (Ru) whose refractory metal component is 30 to 70% by weight. 30 to 70% by weight of molybdenum (M
o) and 5 to 20 parts by weight of alumina (Al ₂ O ₃ ) is added to 100 parts by weight of the refractory metal in the glass component forming the wiring conductor together with the refractory metal.

In the present invention, ruthenium (Ru) and molybdenum (M) are used as the refractory metal components of the wiring conductor.
o) together with alumina (Al ₂ O ₃ ) as a glass component forming the wiring conductor within a predetermined range, the content of the refractory metal component is 30% by weight of ruthenium (Ru). Less than 7 molybdenum (Mo)
Over 0% by weight, or conversely ruthenium (Ru)
Is more than 70% by weight and molybdenum (Mo) is less than 30% by weight, the thermal expansion coefficients of the wiring conductor and the insulating substrate are largely different, and as a result, the insulating substrate is warped or undulated, resulting in flatness. Also, it becomes difficult to obtain a wiring board having excellent dimensional accuracy.

Therefore, the content of the refractory metal component is
30 to 70 wt% of ruthenium (Ru) and 30 to 70 wt% of molybdenum (Mo) are specified, and 40 to 60 wt% of ruthenium (Ru) and molybdenum (M
O) is preferably 40 to 60% by weight.

Further, in the present invention, when the wiring conductor composed of the refractory metal and the glass component contains ruthenium (Ru) and molybdenum (Mo) within the predetermined range as the refractory metal amount, Alumina (Al
_When the content of ₂ O ₃ ) is less than 5 parts by weight with respect to 100 parts by weight of the refractory metal, the adhesion between the insulating substrate and the wiring conductor is deteriorated, and when it exceeds 20 parts by weight, the electric resistance is increased. It becomes large and cannot be applied as a wiring conductor.

Therefore, in the wiring conductor, the refractory metal component is 30 to 70% by weight of ruthenium (Ru) and 30 to 70% by weight of molybdenum (Mo), and 100 parts by weight of the refractory metal component. The content of alumina (Al ₂ O ₃ ) in the glass component is specified to be 5 to 20 parts by weight. Particularly, the refractory metal component is 40 to 60 wt% of ruthenium (Ru) and 40 to 6 of molybdenum (Mo).
It is more preferable that the content of 0% by weight, and 10 to 15 parts by weight of alumina (Al ₂ O ₃ ) per 100 parts by weight of the refractory metal component.

As the glass component, calcia (CaO), magnesia (MgO) or the like can be appropriately contained.

[0016]

According to the wiring board of the present invention, the refractory metal component of the wiring conductor is 30 to 70% by weight of ruthenium (Ru) and 30 to 70% by weight of molybdenum (Mo), and Since 5 to 20 parts by weight of alumina (Al ₂ O ₃ ) was added to 100 parts by weight of the refractory metal, the coefficient of thermal expansion of the wiring conductor was 6.0 × 10 5.
^-6 / ° C to 7.5 x 10 ^-6 / ° C, which can be approximated to the coefficient of thermal expansion of the alumina-based sintered body that constitutes the insulating substrate, which allows insulation from the wiring conductor when the wiring board is manufactured. Deformation such as warpage and undulation due to the difference in thermal expansion coefficient between the base and the base becomes extremely small, and as a result, the surface of the insulating base after firing and integration becomes flat, and excellent dimensional accuracy can be obtained. The wiring conductor can be firmly attached to the insulating substrate, and therefore, even if an external force or thermal shock is applied to the wiring substrate, the wiring conductor is not likely to peel off from the insulating substrate.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a wiring board of the present invention will be described in detail with reference to the drawings. FIG. 1 is a sectional view of an essential part showing an embodiment in which a wiring board of the present invention is applied to a multilayer wiring board for flip chip mounting.

In the figure, reference numeral 1 denotes an insulating substrate 2 and a wiring conductor 3
Are integrally formed, and the wiring conductors 3 are electrically connected to each other through the through-hole conductors 4 provided in the insulating base 2, and the flip chip 6 of the semiconductor element is mounted on the central portion of the upper surface of the insulating base 2. This is a wiring board in which a metallized pad is formed as a wiring electrode for, and the flip chip 6 is directly bonded and fixed via the solder bump 5.

In the wiring conductor 3, a high melting point metal raw material powder made of ruthenium (Ru) and molybdenum (Mo) powder is mixed with raw material powders of glass components such as silica containing alumina, magnesia, and calcia, and the mixed powder is obtained. An electrically conductive paste prepared by adding a known organic binder, a plasticizer, and a solvent to, for example, alumina (Al ₂ O ₃ ), silica (SiO ₂ ), magnesia (MgO), calcia (Ca
Various binders are added to the raw material powder such as O) to prepare a slurry, and the slurry is printed and applied by a screen printing method to a predetermined wiring pattern on a ceramic green sheet formed by a known forming method such as a doctor blade method. After about 16
It is formed by firing at a temperature of 00 ° C.

On the other hand, an external lead terminal 7 made of Fe-Ni-Co alloy or the like is joined to the wiring electrode led out to the lower surface of the insulating substrate 2 through a brazing material such as silver brazing, and the external lead is formed. By connecting the terminal 7 to an external electric circuit,
The flip chip 6 is connected to the external electric circuit via the solder bumps 5, the wiring conductors 3, the through-hole conductors 4, and the external lead terminals 7, respectively. The final product is a semiconductor device by hermetically containing it on the upper surface.

[0021]

EXAMPLES When evaluating the wiring board of the present invention, first,
As an insulating substrate made of an alumina sintered body, for example, Al
_A slurry is prepared by adding and mixing an appropriate organic binder, a plasticizer, and a solvent to raw material powders such as ₂ O ₃ , SiO ₂ , MgO, and CaO, and the slurry is tape-formed by the well-known doctor blade method or calendar roll method. Depending on technology, thickness is about 300 μm
After the above ceramic green sheet was molded, the ceramic green sheet was punched in advance at predetermined positions to form through holes.

Next, a high melting point metal powder of ruthenium (Ru) and molybdenum (Mo) having an average particle diameter of 0.5 to 10 μm and alumina having an average particle diameter of 0.5 to 5.0 μm contained in the glass component. (Al ₂ O ₃ ) powder was mixed in the ratio shown in Table 1, and a known organic binder was added and mixed to prepare a conductive paste.

Using the conductive paste thus obtained, a wiring pattern for evaluation is printed and applied to the above-mentioned ceramic green sheet by a screen printing method, the through hole is filled, and five sheets of this are stacked, and then hydrogen ( H ₂ ) and nitrogen (N ₂ ) in a reducing atmosphere consisting of a mixed gas, or in a neutral atmosphere such as argon (Ar) gas at a temperature of about 1600 ° C. and integrated by 50 mm in length.
A sample for evaluation having a width of 60 mm and a thickness of 1.25 mm was prepared.

Using the evaluation sample, a probe having a tip radius of curvature of 5 μm was scanned on the diagonal line of the sample surface with a surface roughness meter, and the maximum displacement was measured to determine the warpage.

The flatness is 20 m at the center of the sample for evaluation.
The inside of the m corner is divided into 4 vertically and horizontally, and the total of each intersection is 1
The height of each position at 6 points was measured using a laser measuring machine with a spot diameter of 10 μm, and the difference between the maximum value and the minimum value was evaluated.

Further, the adhesion between the wiring conductor and the insulating substrate is determined by forming a 2 mm × 20 mm pad having a thickness of 20 μm on the surface of the insulating substrate, coating the surface of the pad with nickel and gold plating, and then silver-copper solder. A metal frame made of an Fe-Ni-Co alloy was joined via the above, and the load when the metal frame was peeled off by applying tension to the metal frame was evaluated as the metallization strength.

As a wiring conductor, tungsten (W) 1
An evaluation sample made of the same material as described above was used as a comparative example.

[0028]

[Table 1]

As is apparent from the table, the sample No. 1 of the comparative example and the sample Nos. 2 and 8 out of the claims of the present invention have a warp of 9
0 μm or more, the flatness is as large as 35 μm or more, and Sample Nos. 9, 17, and 25 which are also outside the scope of the claims of the present invention have low metallization strength of 4.1 Kgf, and Sample Nos. In contrast to the occurrence of disconnection, the present invention has a warp of 68 μm or less and a flatness of 30 μm.
It can be seen that the metallization strength is less than m and the metallization strength is more than 5.0 kgf.

The present invention is not limited to the above-mentioned embodiments, but various modifications can be made without departing from the gist of the present invention.

[0031]

According to the wiring board of the present invention, the wiring conductor made of the high melting point metal and glass provided on the insulating base made of the alumina sintered body has a high melting point metal component of 30 to 70.
% Of ruthenium (Ru) and 30 to 70% by weight of molybdenum (Mo), and alumina (Al ₂ O ₃ ) based on 100 parts by weight of the refractory metal in the glass component.
Since 5 to 20 parts by weight is contained, deformation of the surface of the insulating substrate such as warpage and waviness is extremely small, dimensional accuracy is good, the wiring conductor is firmly attached to the insulating substrate, and the mass production effect is also very excellent. As a result, a high-density fine wiring pattern can be formed with high precision, and a semiconductor element can be compactly mounted, which is extremely useful for various control devices, information communication devices, and other applications.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of essential parts showing an embodiment in which a wiring board according to the present invention is applied to a multilayer wiring board for flip chip mounting.

[Explanation of reference numerals] 1 wiring board 2 insulating base 3 wiring conductor

Claims (1)

[Claims] 1. A wiring board in which a wiring conductor made of a refractory metal and glass is integrally formed on an insulating base made of an alumina sintered body, the wiring conductor being 30 to 70% by weight as a refractory metal component. Ruthenium (Ru) and 30 to 7
A wiring board containing 0% by weight of molybdenum (Mo) and 5 to 20 parts by weight of alumina (Al ₂ O ₃ ) in 100 parts by weight of the refractory metal component in the glass component.