JP3199588B2 - 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 used in a package for housing a semiconductor element on which a semiconductor element is mounted, a hybrid integrated circuit device, and the like.
The present invention relates to a wiring board having a wiring conductor formed on the surface and / or inside of an insulating base made of a ceramic sintered body having at least one of mullite, cristobalite and forsterite as a main crystal phase.

[0002]

2. Description of the Related Art Conventionally, a wiring board, for example, a wiring board used for a semiconductor element housing package for housing a semiconductor element is made of an electrically insulating ceramic such as an aluminum oxide sintered body, and is substantially at the center of the upper surface thereof. An insulating base having a concave portion for accommodating a semiconductor element in a portion, and a high melting point metal powder such as tungsten (W), molybdenum (Mo), and manganese (Mn) derived from the periphery of the concave portion to the lower surface of the insulating base. And a wiring conductor.

[0003] Each electrode of the semiconductor element is electrically connected to a wiring conductor located around the concave portion via a bonding wire on the bottom surface of the concave portion of the insulating substrate. And the like are sealed via a sealing material made of glass, resin, brazing material, or the like so as to cover the concave portion of the insulating base, and the semiconductor element is hermetically housed in the concave portion of the insulating base as a final product. Semiconductor device.

A wiring board used for a package for housing a semiconductor element includes a part of a wiring conductor provided on an insulating base,
External lead terminals made of an iron-nickel-cobalt alloy, an iron-nickel alloy, or the like are attached via a brazing material such as silver brazing, and each electrode of the semiconductor element is connected by connecting the external lead terminals to an external electric circuit. Are electrically connected to an external electric circuit via wiring conductors, bonding wires and external lead terminals.

[0005] The wiring board is formed into a slurry by adding a suitable organic binder, a plasticizer, and a solvent to a raw material powder such as aluminum oxide (Al ₂ O ₃ ), silicon oxide, and magnesium oxide. A plurality of ceramic green sheets are obtained by employing a tape forming technique such as a doctor blade method or a calender roll method, which is well known in the art, and then an organic binder suitable for a high melting point metal powder such as W or Mo is applied to each of the ceramic green sheets. Plasticizer, metal paste obtained by adding and mixing solvent is printed and applied in a predetermined pattern,
Finally, the ceramic green sheets are stacked and pressed on top and bottom, and fired at a temperature of about 1600 ° C. in a reducing atmosphere.

[0006]

However, this conventional wiring board has the following drawbacks.

(1) Since W, Mo, and the like forming the wiring conductor have a high electric resistance, the voltage drop of an electric signal transmitted through the wiring conductor is large, which makes it difficult to miniaturize the wiring conductor. It has been difficult to increase the size and density of the device.

(2) The high-melting-point metal powders such as tungsten, molybdenum, etc. forming the Al ₂ O ₃ sintered body and the wiring conductor constituting the insulating substrate have a thermal expansion coefficient of 7.0 to 8 at room temperature to 800 ° C., respectively. 0.5 × 10 ^{−6 /} ° C., 4.5-6.0 ×
Since it is 10 ⁻⁶ / ° C., which is different from the above, when a ceramic green sheet formed by printing and applying a metal paste made of a high melting point metal powder such as tungsten or molybdenum in a predetermined pattern is baked to form a wiring board, the ceramic green sheet becomes Thermal stress is generated between the wiring conductor and the wiring conductor due to a difference in thermal expansion coefficient between the wiring conductors and remains in the wiring board. When an external force or a thermal shock is applied to the wiring board, the external force or the thermal shock is applied. The force becomes extremely large immediately after the residual stress, causing cracks in the insulating base to cause disconnection of the wiring conductor, and has the disadvantage that the wiring conductor is separated from the insulating base.

(3) A sintered body that can be fired at a lower temperature than alumina, for example, a glass ceramic sintered body fired at 1000 to 1600 ° C., or at least one of mullite, cristobalite and forsterite is used as a main crystal phase. An insulating substrate made of a ceramic sintered body has a coefficient of thermal expansion of 5
１２12 × 10 ⁻⁶ / ° C., so that it can be close to that of W and Mo. However, since the temperature at the time of integral sintering is low, high melting point metals such as W and Mo are not sintered and densified. , Mo, W, Mo
Therefore, a low-temperature sintering wiring conductor applicable to an insulating substrate fired at 1000 to 1600 ° C. has been demanded.

(4) The relative dielectric constant of Al ₂ O ₃ is as high as about 10, which causes a problem that the relative dielectric constant of the Al ₂ O ₃ -based sintered body increases and the signal propagation speed decreases. .

[0011]

SUMMARY OF THE INVENTION The present invention has been devised in view of the above-mentioned drawbacks. It is possible to simultaneously sinter an insulating substrate and a wiring conductor at 1000 to 1600 ° C., and to prevent the wiring conductor from peeling or breaking the wiring conductor. It is an object of the present invention to provide a wiring board which does not cause any cracks in the insulating base and can make the wiring conductor finer.

[0012]

[Means for Solving the Problems] The wiring board of the present invention comprises:
A wiring substrate having a wiring conductor formed on the surface and / or inside of an insulating substrate, wherein the insulating substrate is made of a ceramic sintered body having at least one of mullite, cristobalite, and forsterite as a main crystal phase. The conductor is composed of 70 to 95% by weight of W and / or Mo,
It is characterized by being formed with 30% by weight of Cu.

The wiring conductor is made of W and / or Mo.
And 100 parts by weight of the main component consisting of Cu and Cu, it is desirable to add and contain 30 parts by weight or less of the constituent components of the insulating base. Al ₂ O ₃ , S
ceramic fillers such as iO ₂ , mullite, cordierite, and forsterite; alkaline earth metal oxides such as CaO and MgO; or hydroxides, salts, and Ta thereof
_There are oxides, compounds, and the like of elements of Group 5a of the periodic table such as ₂ O ₅ and Nb ₂ O ₅ .

[0014]

According to the wiring board of the present invention, the wiring conductor is composed of 70 to 95% by weight of W and / or Mo and 5 to 30% of Cu.
%, The thermal expansion coefficient of the wiring conductor can be approximated to the thermal expansion coefficient of a sintered body having at least one of mullite, cristobalite and forsterite as a main crystal phase at room temperature to 800 ° C. When a wiring board is manufactured by the method, no thermal stress is generated between the wiring conductor and the insulating substrate due to a difference in thermal expansion coefficient between the wiring conductor and the insulating substrate, and this hardly remains inside the wiring board. As a result, Even if an external force or a thermal shock force is applied to the wiring board, no crack is generated in the insulating base, and it is possible to effectively prevent the wiring conductor from being disconnected or the like, and at the same time, connect the wiring conductor to the insulating base. Can be firmly attached.

Further, according to the wiring board of the present invention, the wiring conductor is formed of 70 to 95% by weight of W and / or Mo and 5 to 30% by weight of Cu. Lower than the wiring conductor consisting of
As a result, the wiring conductor can be miniaturized without deteriorating the propagation strength of the electric signal transmitted through the wiring conductor, and the miniaturization and high density of the wiring board can be achieved.

Further, by using a sintered body having mullite and / or cristobalite as a main crystal phase and a sintered body having forsterite as a main crystal phase as an insulating base material, the relative dielectric constant can be suppressed low. Further, by using a wiring material composed of W and / or Mo and Cu, it is possible to fire at a lower temperature than alumina (1000 to 1).
(600 ° C., especially 1100 ° C. to 1500 ° C.) It is possible to co-fire with the insulating substrate.

Further, according to the wiring board of the present invention, the wiring conductor contains 30 parts by weight or less of the constituent components of the insulating base (100 parts by weight) with respect to 100 parts by weight of the main component comprising W and / or Mo and Cu. (Excluding) The addition allows the wiring conductor to be more firmly attached to the insulating base, so that even when an external force or a thermal shock force is applied to the wiring substrate, the wiring conductor does not peel off from the insulating base at all. Becomes For example, when a sintered body having mullite and / or cristobalite as a main crystal phase is used as an insulating substrate, the above effects can be obtained by adding alumina, mullite, silica, or the like to the wiring conductor.

In the wiring conductor, W and / or M
As long as the composition of o is 70 to 95% by weight and Cu is 5 to 30% by weight, components other than the components of the base such as alumina, mullite and silica, for example, rare earth oxides and compounds such as Y ₂ O ₃ Oxides, hydroxides, carbonates, salts of nitrates and the like of alkaline earth metals such as Mg, Ca, Sr and Ba;
Oxidation of halides such as chlorides, borides, oxides such as Cr and Mn, hydroxides, salts, halides such as chlorides, nitrides, carbides, borides, boron, zinc and alkali metals It may contain other components such as materials.
Boron, zinc, oxides of alkali metals and the like are effective in lowering the firing temperature.

[0019]

Embodiment 1 Next, the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 shows an embodiment of a wiring board according to the present invention.
Is a wiring conductor formed in the insulating base 1. The wiring substrate A is formed by forming the wiring conductor 2 in the insulating base 1.

The insulating substrate 1 is provided with a concave portion 1a for forming a space for accommodating the semiconductor element 3 in the center of the upper surface thereof, and the semiconductor element 3 is made of glass,
It is bonded and fixed via an adhesive such as resin or brazing material.

The insulating substrate 1 is made of a ceramic containing mullite as a main crystal phase, cristobalite as a main crystal phase, a mixture of mullite and cristobalite crystal phases as a main crystal phase, or a forsterite crystal phase as a main crystal phase. It is composed of a sintered body. This insulating base 1
For example, mullite, Al ₂ O ₃ , SiO ₂ , MgO, C
A raw material powder such as aO is mixed with an appropriate organic binder, a plasticizer, and a solvent to form a slurry, and the slurry is formed into a ceramic green sheet by employing a conventionally known doctor blade method, calendar roll method, or the like. After that, the ceramic green sheet is manufactured by subjecting the ceramic green sheet to appropriate punching, laminating a plurality of the sheets, and firing at a temperature of about 1500 ° C.

In the insulating base 1, a wiring conductor 2 is provided.
Are formed integrally, and each electrode of the semiconductor element 3 is connected to a bonding wire 4 around the concave portion 1a of the wiring conductor 2.
An external lead terminal 5 connected to an external electric circuit is electrically connected to a wiring conductor led out on the lower surface of the insulating base 1.

The wiring conductor 2 formed in the insulating base 1 is
70 to 95% by weight of W and / or Mo and 5% of Cu
The wiring conductor 2 is connected to an external lead terminal 5 connected to an external electric circuit by a semiconductor element 3.
Has the function of electrically conducting the respective electrodes.

W and / or Mo is 70 to 95% by weight
And a wiring conductor 2 composed of 5 to 30% by weight of Cu, a metal paste obtained by adding an appropriate organic binder, a plasticizer, and a solvent to a predetermined amount of powder of W, Mo, Cu, etc. The ceramic green sheet is printed and applied in a predetermined pattern in advance by a well-known screen printing method or the like, and is integrally formed at a predetermined position by simultaneous firing with the insulating substrate 1.

In this case, W and / or Mo are set to 70 to
The wiring conductor 2 composed of 95% by weight and 5 to 30% by weight of Cu is a sintered body having mullite and / or cristobalite constituting the insulating base 1 as a main crystal phase or a main crystal phase of forsterite. Since the thermal expansion coefficient is close to the thermal expansion coefficient of the sintered body, no thermal stress is generated between the wiring conductor 2 and the insulating base 1 due to the difference in thermal expansion coefficient between the wiring conductor 2 and the insulating base 1. Hardly remains on the wiring substrate A. As a result, even if an external force or a thermal shock force is applied to the wiring board A, cracks occur in the insulating base 1 and the wiring conductor 2 does not break, etc. The conductor 2 does not peel off from the insulating base 1.

The wiring conductor 2 having the above-described structure has a lower sheet resistance value than the conventional wiring conductor made of W, Mo, or the like. , The voltage drop of an electric signal transmitted through the wiring board A can be made small, the wiring conductor 2 can be miniaturized at the same time, and the size and density of the wiring board A can be reduced.

The wiring conductor 2 made of 70 to 95% by weight of W and / or Mo and 5 to 30% by weight of Cu
Although the melting point of copper is 1085 ° C., which is lower than the temperature at which ceramic green sheets are fired (1500 ° C.), since the copper is confined between high melting point tungsten and molybdenum powders, As a result, the wiring conductor 2 made of W and / or Mo and Cu is integrally formed on the insulating base 1 obtained by firing the ceramic green sheet without scattering the melting point to the outside during firing. Will be.

The wiring conductor 2 is made of W and / or Mo.
Exceeds 95% by weight and copper is less than 5% by weight,
The electric resistance of the wiring conductor 2 increases, the propagation speed of the electric signal transmitted through the wiring conductor 2 decreases, it becomes difficult to miniaturize the wiring, and W and / or Mo become less than 70% by weight and Cu Exceeds 30% by weight, the coefficient of thermal expansion greatly differs from the coefficient of thermal expansion of the insulating base 1, making it difficult to firmly and integrally attach the wiring conductor 2 to the insulating base 1. In particular, the wiring conductor 2 in the present invention is desirably composed of 80 to 90% by weight of W and 10 to 20% by weight of Cu.

Further, the wiring conductor 2 contains 70 to 95% by weight of W and / or Mo and 5 to 30% by weight of Cu.
From 100 parts by weight of the main component, Al ₂ O ₃ , Si
When the above-mentioned constituent components of the insulating substrate such as O ₂ and mullite are contained in an amount of 30 parts by weight or less (not including 0), the wiring conductor 2 can be more firmly and integrally attached to the insulating substrate 1.

The wiring conductor 2 functions to connect the semiconductor element 3 housed in the concave portion 1a of the insulating base 1 to an external electric circuit, and connects the external lead terminal 5 to the external electric circuit to thereby form the wiring conductor 2 in the concave portion 1a. The housed semiconductor element 3 is electrically connected to an external electric circuit via the wiring conductor 2, the bonding wire 4 and the external lead terminal 5.

The external lead terminal 5 is made of a metal such as an iron-nickel-cobalt alloy or an iron-nickel alloy. It is formed in a predetermined shape by employing a metal working method.

Thus, according to the above-described semiconductor element housing package, the semiconductor element 3 is bonded and fixed to the bottom surface of the concave portion 1a of the insulating base 1 via an adhesive such as glass, resin, brazing material or the like. Each electrode is electrically connected to the wiring conductor 2 via a bonding wire 4, and then a cover 6 is formed on the upper surface of the insulating base 1 from glass, resin, brazing material, or the like so as to cover the recess 1 a of the insulating conductor 1. The semiconductor device 3 is joined via the sealing material and the semiconductor element 3 is hermetically accommodated in the concave portion 1a of the insulating base 1 to obtain a semiconductor device as a final product.

It should be noted that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the gist of the present invention. Although the description has been given of the case where the substrate is applied to a semiconductor element housing package for housing a semiconductor element, this may be applied to a wiring substrate used in a hybrid integrated circuit device.

The present inventors conducted experiments to confirm the effects of the present invention. First, W and / or Mo and Cu powder are mixed at the ratios shown in Table 1, and a known amount of a known binder, solvent, plasticizer, defoamer, dispersant, etc. is added and mixed to form a paste. The length of 30 minutes was applied to the surface of the sintered body.
It was applied with a thickness of 3 mm and a thickness of 20 μm, baked at the temperature shown in Table 1, and the metallized metal layer was adhered and bonded to the sintered body, and the sheet resistance was measured.

[0035]

[Table 1]

From Table 1, it can be seen that Samples 1 to 5 of the present invention were used.
Has a coefficient of thermal expansion of 5 to 7.3 × 10 ⁻⁶ / ° C. and a sheet resistance of 8.6 to 9.1 mΩ / SQ, and the wiring conductor used in the present invention includes mullite, cristobalite, It can be seen that the thermal expansion coefficient of the ceramic sintered body having at least one of forsterite as a main crystal phase substantially coincides with the coefficient of thermal expansion.

The wiring board of the present invention is shown in FIGS.
It can be applied to a substrate as shown in FIG. Reference numeral 9 in FIGS. 2 and 3 denotes a heat spreader.

[0038]

According to the wiring board of the present invention, the wiring conductor is composed of 70 to 95% by weight of W and / or Mo, Cu
From 5 to 30% by weight, the coefficient of thermal expansion of the wiring conductor is approximated to the coefficient of thermal expansion of a ceramic sintered body containing at least one of mullite, cristobalite and forsterite as a main crystal phase constituting an insulating base. This prevents the occurrence of thermal stress due to the difference in the coefficient of thermal expansion when the wiring board is manufactured, and this hardly remains inside the wiring board, and as a result, the external force is applied to the wiring board. Even when a thermal shock force is applied, no cracks are generated in the insulating base, and no disconnection or the like occurs in the wiring conductor, and at the same time, the wiring conductor can be firmly attached to the insulating base.

Further, according to the wiring board of the present invention, the electric resistance of the wiring conductor can be made lower than that of the conventional product, and as a result, the wiring conductor can be miniaturized without deteriorating the propagation speed of the electric signal transmitted through the wiring conductor. It is possible to achieve the miniaturization and high density of the wiring board.

Further, by using a sintered body containing mullite and / or cristobalite as a main crystal phase as an insulating base material, the relative dielectric constant can be suppressed low.
Further, by using an electrode material made of W and / or Mo and Cu, an electrode material that is optimal for an insulating substrate that can be fired at a lower temperature than alumina can be provided.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment in which a wiring board of the present invention is applied to a package for housing a semiconductor element.

FIG. 2 is a sectional view showing another embodiment in which the wiring board of the present invention is applied to a package for housing a semiconductor element.

FIG. 3 is a sectional view showing still another embodiment in which the wiring board of the present invention is applied to a package for housing a semiconductor element.

[Description of Signs] 1 ... Insulating base 2 ... Wiring conductor 3 ... Semiconductor element A ... Wiring board

Claims (1)

(57) [Claims] 1. A wiring substrate comprising a wiring conductor formed on a surface and / or inside of an insulating substrate, wherein the insulating substrate has at least one of mullite, cristobalite and forsterite as a main crystal phase. A wiring substrate comprising 70 to 95% by weight of W and / or Mo and 5 to 30% by weight of Cu.