JP3061282B2 - Ceramic multilayer circuit board and semiconductor module - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic multilayer circuit board, and more particularly to a ceramic multilayer circuit board suitable for a configuration of a functional module and a method of manufacturing the same.

2. Description of the Related Art Conventionally, there has been known a ceramic multilayer circuit board in which a conductive paste and an insulating paste are alternately formed on a green sheet by printing or the like and fired (Japanese Patent Publication No. 52-37588).
In addition, a ceramic multilayer circuit board formed by forming fine wiring on a green sheet using photolithographic technology, laminating and firing the fine wiring is disclosed in JP-B-63-37518, a dense alumina ceramic layer and a porous alumina ceramic layer. Japanese Patent Application Laid-Open No. 59-22398 discloses a ceramic multilayer circuit board in which a high-strength layer such as alumina is provided on the surface layer and a low dielectric constant layer such as mullite is provided on the inner layer. Is known from JP-A-60-14494. Also, in the field of organic multilayer circuit boards, multilayer circuit boards in which different kinds of organic sheets are laminated are known (Japanese Patent Laid-Open No. 61-220499).

[Problems to be Solved by the Invention] In recent years, high-density packaging has been required for large-scale computers in order to increase the operation speed, and in order to achieve this, high-density multilayer circuit boards have been put into practical use. .

In the ceramic multi-layer circuit board, a low dielectric constant of the substrate material is required to increase the speed of an electric signal, and a high strength is also required from the viewpoint of mounting reliability. However, it is difficult to make these two properties compatible with one kind of material.

As means for solving the above problems, for example, Japanese Patent Application Laid-Open No. 60-14 / 1985
As disclosed in Japanese Patent Publication No. 494, it is conceivable to form the outermost layer of the multilayer circuit board with a high strength material and the inner layer with a low dielectric constant material. However, such a configuration is effective for the pinning strength of a multilayer circuit board having connection pins, but the strength of the entire circuit board depends on the strength of the low-permittivity material of the inner layer that occupies most of the strength. You. In addition, there is a problem that cracks and peeling are likely to occur at the interface between the high-strength layer and the low-dielectric layer, and that the high-strength layer having a high dielectric constant affects the signal transmission speed.

Ceramics generally shrink with firing. In particular,
When dissimilar materials are stacked and fired, peeling and cracking are likely to occur between dissimilar materials due to differences in shrinkage characteristics.

In addition, a method of manufacturing a normal ceramic multilayer circuit board from a green sheet is advantageous in multilayering because after forming a wiring pattern on the sheet, inspecting the sheets one by one, and laminating them collectively, Good yield. However, when manufacturing a high-density multilayer circuit board on which fine wiring is formed, the thickness of the insulating layer must be reduced from the viewpoint of characteristic impedance, so that the green sheet must be thin. However, such a thin green sheet
There is a problem that it is difficult to handle because it is weak in strength and easily deformed.

On the other hand, the thin-film multilayer circuit board by the sequential lamination method in which the conductor layer (wiring) and the insulating layer are formed each time the firing is performed is advantageous in terms of miniaturization and high density of the wiring. Therefore, if a defect occurs in the middle of the process, there is a problem that the whole becomes defective and the production yield is poor. Also,
Since firing is performed for each layer, the number of steps is increased, and mass productivity is poor.

It is an object of the present invention to provide a ceramic multilayer circuit board that achieves both high strength and high signal propagation speed. Another object of the present invention is to provide a method for producing the ceramic multilayer circuit board with excellent mass productivity.

[Means for Solving the Problems] The gist of the present invention for achieving the above object is as follows.

(1) In a ceramic multilayer circuit board having a plurality of insulating layers made of a ceramic insulating material, conductors formed between the insulating layers, and via holes for electrically connecting the conductors of the respective layers, the insulating layer is high. The high-strength layer is composed of a higher-strength material than the low-k layer, and the low-k layer has a signal layer. A ceramic multilayer circuit board, wherein a power supply layer or a ground layer is provided between a dielectric layer and the high-strength layer.

(2) In the method of manufacturing a ceramic multilayer circuit board, a step of forming a ceramic green sheet for the high-strength layer; and forming a power supply layer or a ground layer on the ceramic green sheet for the high-strength layer using a conductive paste. Forming a conductive green layer, forming a ceramic green sheet for the low dielectric constant layer on the release-treated organic polymer film, and forming a signal using a conductive paste on the ceramic green sheet for the low dielectric constant layer. Forming a layer, positioning and laminating the ceramic green sheet for the low dielectric constant layer on the side on which the conductor layer of the ceramic green sheet for the high strength layer is formed, and peeling the polymer film; A process for forming a green sheet laminate by pressing and laminating a plurality of sets of laminated green sheets for the high strength layer and the low dielectric constant layer. , Preparation of the ceramic multilayer circuit board which comprises a step of performing a binder vent and firing the green sheet laminate.

Although it has been described that it is difficult to achieve both high strength of the substrate and high signal propagation speed with one type of ceramic insulating material, the present invention has solved the problem by adopting the above configuration. That is, most of the signal wiring is formed on a low dielectric constant layer, and a conductor layer serving as a power supply or a ground layer is formed at an interface between the high strength layer and the low dielectric constant layer.
By doing so, the signal propagation speed is hardly affected by the high-intensity layer. Therefore, the signal propagation speed is substantially determined by the relative dielectric constant of the low dielectric constant layer forming the signal wiring, and can be increased.

In addition, most of the mechanical stress applied to the multilayer circuit board is received by the high-strength layer formed of a material having a relatively high Young's modulus.

In addition, by alternately laminating one or more high-strength layers and two or more low-dielectric layers, a thermal stress based on a difference in firing shrinkage characteristic and a difference in thermal expansion coefficient between different materials is obtained. Since the stress is applied relatively uniformly to each layer, delamination, cracks, etc. are less likely to occur.

Furthermore, in the case of combining a high strength layer and a low dielectric constant layer having different firing shrinkage characteristics, even if the lower shrinkage start temperature starts shrinking, if the other has not reached the shrinkage start temperature,
Shrinkage in the surface direction is suppressed at the bonding interface between the two, and shrinkage of the substrate rather occurs in the thickness direction. Then, when the next higher shrinkage start temperature reaches the temperature at which shrinkage starts, the other sintered body also shrinks in the thickness direction, because the other shrinkage suppresses the shrinkage. As a result, the shrinkage of the entire multilayer circuit board in the plane direction can be reduced, and the variation in the firing shrinkage is small.

Further, according to the present invention, even if there is a potential difference between the conductive layers (power supply layer or ground layer) formed on both sides of the high-strength layer as described above, the high-strength layer has a relatively high dielectric constant. Therefore, there is an effect that voltage fluctuation is suppressed and reduced.

A problem such as delamination between the low dielectric layer and the high strength layer can be solved by selecting a material. For example, by using the same glass for both components and using a material having a different inorganic filler (hereinafter referred to as a filler), a multilayer circuit board having excellent interlayer adhesive strength can be obtained.

As the filler for the high-strength layer, for example, Al ₂ O ₃ , B
Materials with high Young's modulus, such as ₄ C and SiC, are preferred.

In addition, as glass powder, MgO is converted to oxide by 2
0~30mol%, 0.1~3mol% of CaO, 10 to 30 mol% of Al ₂ O _3,
B ₂ O ₃ to 35~45mol%, it is preferable that to prepare a SiO ₂ in the range of 0~30mol%.

As fillers for the low dielectric constant layer, for example, α quartz, Si
A low dielectric constant filler such as hollow microspheres of O ₂ or SiO ₂ is preferred.
The glass powder may have the same composition as the glass powder used for the high-strength layer. The glass good crystallized glass which precipitates a main crystalline of _{2Al 2 O 3 · B 2 O} 3 during sintering.

Further, as the low dielectric constant layer, a material in which the ceramic powder is adhered to the surface of an inorganic fiber base material such as ceramic paper, ceramic cloth or glass cloth can be used by firing. This is a material that is preferable for lowering the dielectric constant, since the entangled inorganic fibers prevent the ceramic powder from entering the inside, so that a material having a dense surface and containing pores is obtained.

The conductive paste filling the via holes has an average particle size of 5μ.
98 to 80% by weight of a powder of gold, copper, silver-palladium, silver-platinum or the like is mixed with 2 to 20% by weight of a glass powder of m, and a methacrylic acid-based binder and a solvent such as butyl carbitol acetate are added to the mixed powder. Mix the appropriate amount of
Adjust to an appropriate viscosity before use. In addition, the glass powder composition of the paste is 70 to 80 mol% of SiO ₂ in terms of oxide, and Al ₂ O ₃
Those containing 10 to 15 mol% of Cu ₂ O and 10 to 15 mol% of Cu ₂ O are preferable.

After forming a via hole in a thin green sheet, a ceramic multilayer circuit board forms a signal wiring or a conductor layer,
If these are laminated and fired at the same time, it seems that a circuit board can be formed with good yield. However, in practice, such thin green sheets have high strength due to their low strength and large pattern deformation due to green sheet elongation. Getting things is not easy.

Therefore, in the present invention, on a relatively thick green sheet,
A multilayer circuit board was obtained by laminating several layers of conductor layers or signal layers and inorganic thin film insulating layers having via holes formed alternately, and laminating and firing several sets.

The inorganic thin film insulating layer may be formed directly on a thick green sheet, or may be formed on another substrate by transfer onto a thick green sheet. In addition,
In forming the inorganic thin film insulating layer by a method of sequentially laminating on a thick green sheet, the number of laminating layers is about several layers. By doing so, the defect occurrence rate can be reduced to half or less as compared with the conventional system in which all layers are sequentially laminated.

[Operation] The ceramic multilayer circuit board of the present invention can increase the speed of signal propagation because most of the signal wiring is formed in the low dielectric layer, and the low dielectric layer and the high strength layer are formed. It is considered that the power layer or the ground layer provided between them has little electrical influence on the high-strength layer having a high dielectric constant.

In addition, the mechanical stress applied to the substrate is at least applied to the high-strength layers inserted every several layers, so that the substrate can have high strength.

Furthermore, the manufacturing yield of the ceramic multilayer circuit board of the present invention can be improved because a plurality of thin-film multilayer circuits formed on a relatively thick green sheet are laminated as a set. It is for producing by a method.

Embodiment An embodiment of the present invention will be specifically described below with reference to FIGS. 1 to 9.

Embodiment 1 FIG. 1 is a cross-sectional view showing an outline of a ceramic multilayer circuit board of the present invention, and FIG. 2 is a flowchart showing a manufacturing process of the ceramic multilayer circuit board of the present invention by a transfer method.

As a green sheet 13 for a high-strength layer of the ceramic multilayer circuit board in FIG. 2, 70% by weight of glass powder having an average particle size of 5 μm and 30% by weight of Al ₂ O ₃ powder having an average particle size of 1 μm are prepared. The glass powder contains MgO 22.8 mol% in terms of oxide, CaO
_{1.2mol%, Al 2 O 3 28mol} %, B 2 O 3 38.4mol%, SiO 2 9.6mol
%.

Next, 20 parts by weight of a methacrylic acid-based organic binder, 99 parts by weight of trichloroethylene, 26 parts by weight of tetrachloroethylene, 35 parts by weight of n-butyl alcohol, and 35 parts by weight of phthalic acid were added to 100 parts by weight of the mixture of the above glass powder and Al ₂ O ₃ powder. -N-
One part by weight of butyl was added and wet-mixed with a ball mill for 24 hours to prepare a slurry. The slurry was adjusted to an appropriate viscosity by degassing under reduced pressure.

Next, the slurry was applied on a silicone-coated polyester film to a thickness of 1.5 mm using a doctor blade, dried, and the polyester film was peeled off to produce a green sheet 13.

Next, the conductive paste to be filled in the via hole 3 in FIG. 1 is obtained by adding 90% copper powder to 10% by weight of glass powder having an average particle size of 5 μm.
% By weight, and 100 parts by weight of this mixed powder, 30 parts by weight of a methacrylic acid-based organic binder and 100 parts by weight of butyl carbitol acetate are mixed for 30 minutes by a triturator to adjust to an appropriate viscosity. did. The glass powder composition of the paste was converted to oxide, and SiO ₂ 75 mol%, Al ₂ O ₂ 1
It contains 2.5 mol% and 12.5 mol% of Cu ₂ O.

Next, the green sheet 13 has a diameter
A hole 12 having a diameter of 100 μm was formed, and the conductive paste 9 was buried to form the via hole 3 shown in FIG. Further, the viscosity of the conductive paste was adjusted, and a ground layer 9 'was formed on the green sheet by printing.

On the other hand, a polyester film 10
The signal layer 5 having a thickness of 15 μm and a width of 50 μm was printed and wired on the conductive paste whose viscosity was readjusted above, and a slurry 11 for a low dielectric constant layer was printed thereon. The slurry was composed of 60% by weight of glass powder having an average particle size of 5 μm and an average particle size of 1 μm.
It was prepared in the same manner as the above-mentioned high-strength layer, using a mixture containing 40% by weight of a ₂ μm SiO ₂ powder. The composition of the glass powder used was the same as that of the glass powder used for the high-strength layer. The glass is a crystallized glass which precipitates crystals of _{2Al 2 O 3 · B 2 O} 3 during sintering.

After drying the slurry 11, use a laser to set the diameter
A hole 12 having a diameter of 100 μm was formed, and the Cu-based conductor paste 9 was embedded by a printing method.

Next, the low dielectric layer formed on the polyester film 10 was positioned on the green sheet 13 for the high-strength layer, pressed and laminated, and the polyester film 10 was peeled off.

Next, a layer having only a via hole or a signal layer 5 was similarly transferred and laminated thereon in the same manner to form a low dielectric constant layer 7 composed of three layers. Further, a ground 9 'was printed on the laminate with the above-mentioned Cu-based conductor paste.

Five sets of the laminate composed of one high-strength layer and three low-dielectric-constant layers thus obtained were laminated and pressed by hot pressing. Crimping conditions are a temperature of 100 ° C. and a pressure of 50 kgf / mm ² .

The laminate thus produced was heated from room temperature at a rate of 100 ° C./h to remove the binder, and fired at 980 ° C. for 1 hour to obtain a fired product. The firing atmosphere was nitrogen containing 30% by volume of water vapor.

The ceramic multilayer circuit board thus manufactured has a high-strength layer thickness of 350 μm and a low-inductance layer thickness of 80 μm, and cracks and peels around conductor layers (signal layer, power layer, ground layer) and via holes. Was not recognized.

Further, as shown in FIG. 1, a pin 8 is attached to the fired product,
The LSI chip 1 was mounted with the solder 2. No crack or the like was observed around the pin 8. No warping or deformation of the substrate was observed.

The flexural strength of the ceramic multilayer circuit board is 15 kgf / mm ² , and the signal propagation speed is the same as the speed of 1.5 × 10 ⁸ m / sec when propagating through a material having a relative dielectric constant of 4. It is possible to obtain a ceramic multi-layer circuit board compatible with increasing the propagation speed.

Further, the formation of a thin insulating layer, which was difficult to laminate as a green sheet, could be performed relatively easily by the above-described method. In this embodiment, since the insulating layer can be formed thin, the inductance is small and the rate of occurrence of electric noise is smaller than that of the conventional one.

[Example 2] In the same manner as in Example 1, a green sheet 13 for a high-strength layer was produced from the ceramics shown in Table 3 using the glasses shown in Tables 1 and 2.

Next, holes were made in the same manner as in Example 1, the conductive paste shown in Table 3 was filled, and a conductive layer was formed by printing.

Further, a slurry of ceramics for a low dielectric constant layer shown in Table 3 was prepared, a thin film was formed on a polyester film in the same manner as in Example 1, and this was transferred and laminated. The laminate was fired to obtain a ceramic multilayer circuit board.

No cracks or peeling were observed around the conductor layers and via holes of the obtained ceramic multilayer circuit board, and no warping or deformation of the substrate was observed. In addition, the installed LSI
No defective electrical connection between the chip, the ceramic multilayer circuit board, and the pins 8 occurred. The thickness of the low dielectric constant layer of the ceramic multilayer circuit board is 60 μm, and the wiring width is 20 μm.

Example 3 FIG. 3 is a cross-sectional view showing an outline of a ceramic multilayer circuit board in which fibers are combined with a high-strength layer.

In terms of oxide, 78% by weight of SiO _2, 14.5% by weight of B ₂ O ₃ , ₂ % by weight of alkaline earth metal oxide (MgO), 3% by weight of alkali metal oxide (K ₂ O), Al ₂ O ₃ 70% by weight of borosilicate glass powder with an average particle size of 5 μm containing 1.5% by weight and 1% by weight of impurities
And 30% by weight of SiO ₂ having an average particle diameter of 1 μm, and a slurry was prepared in the same manner as in Example 1.

Next, as shown in FIG. 3, the slurry was applied to both sides of a sheet having a thickness of about 100 μm in which Al ₂ O ₃ long fibers 18 were knitted in a cross shape to a thickness of about 50 μm. Next, 100
A via hole 3 was formed by piercing a hole having a diameter of μm and burying a conductive paste, and a conductive layer (power supply layer or ground layer) 4 was printed on both sides to form a high-strength layer 6. The conductor paste used was prepared by mixing a conductor powder composed of 1% by weight of Pt and 99% by weight of Ag, an acrylic binder, and butyl carbitol acetate to adjust the viscosity to an appropriate value.

On the other hand, for the green sheet of the low dielectric constant layer 7, a slurry was prepared in the same manner as in Example 1 by using a mixed powder containing 60% by weight of borosilicate glass and 40% by weight of SiO ₂ glass as a ceramic raw material. It was applied to a thickness of 700 μm on a silicone-coated polyester film using a blade and dried to produce a 230 μm thick green sheet.

100μmφ for the three green sheets for low dielectric constant layer
And a via hole 3 was filled with the Pt-Ag paste, and a signal layer 5 was printed. The wiring width is 130 μm. The green sheet was transferred and laminated on the green sheet for the high-strength layer while being positioned.

Next, for one layer of the high-strength layer sheet containing the fibers, five sets of laminates each including three layers of the low-dielectric-constant layer sheet containing no fibers printed with the signal layer or the conductor layer are laminated, Pressing was performed in the same manner as in Example 1 to produce a laminate.

The above-mentioned laminate was heated from the room temperature in the atmosphere at a rate of 100 ° C./h and fired at 900 ° C. for 1 hour to obtain a fired product. Pins and LSI chips were attached to the fired product to obtain a ceramic multilayer circuit board.

No crack or peeling was observed around the conductor layer 4 and the via hole 3 of the multilayer circuit board. Also, no warping or deformation of the substrate was observed.

In the ceramic multilayer circuit board of this embodiment, since the fiber suppresses the firing shrinkage in the surface direction, the firing shrinkage in the surface direction is about 1%, and a ceramic multilayer circuit board with high dimensional accuracy can be obtained. Also, Al ₂ O ₃ fiber improves the strength of the ceramic multilayer circuit board, its bending strength is 15 kgf / mm ² , and the signal propagation speed is the same as when propagating in a material having a relative dielectric constant of 4. 1.5 × 10 ⁸ m / sec.

Example 4 As a green sheet for a high-strength layer, in terms of oxides
MgO 25 mol%, Al ₂ O ₃ 15 mol%, B ₂ O ₃ 40 mol%, SiO ₂ 20 mol%
70% by weight of glass powder having a basic composition of 5 μm in average particle size
And 30% by weight of Al ₂ O ₃ powder having an average particle size of 1 μm,
A slurry was prepared in the same manner as in Example 1. The slurry was applied on a silicone-coated polyester film to a thickness of 1 mm using a doctor blade and dried to produce a green sheet.

As shown in FIG. 7, a hole 12 having a diameter of 100 μm was drilled in the green sheet 13 by machining, and the hole was filled with the Cu-based conductor paste 9 used in Example 1. Further, a conductor layer was printed with the Cu-based conductor paste 9 in the same manner as in Example 1.

Next, as a low dielectric constant layer green sheet, SiO ₂ glass short fibers were randomly arranged, and the slurry 11 was applied to both sides of a 50 μm-thick ceramic paper 16 in the form of a cloth in an amount of 20 μm. The slurry 11 was prepared in the same manner as in Example 1 by mixing 60% by weight of glass powder having an average particle diameter of 5 μm and 40% by weight of SiO ₂ glass powder having an average particle diameter of 1 μm. The glass powder having an average particle size of 5 μm used here is the same MgO—Al ₂ O ₃ —B ₂ O ₃ —SiO ₂ glass used in the high-strength layer. A hole 12 having a thickness of 100 μm was formed in the low dielectric constant layer sheet to which the slurry 11 was applied, and the Cu paste 9 used in Example 1 was filled.

Next, a slurry 11 was prepared using a photosensitive resin and a ceramic raw material.
Is prepared, coated on a polyester film 10 to a thickness of 20 μm, further irradiating ultraviolet rays with a wiring pattern mask, and developing a solvent-containing slurry containing a photosensitive resin with a solvent to remove the wiring pattern. After the formation, a mask was applied to the pattern other than the pattern, Cu was deposited, and electroless Cu plating was applied to the wiring pattern to form a Cu wiring having a thickness of 20 μm and a width of 40 μm. Two sheets are prepared and the signal layer 5 in the X direction and the signal layer 5 in the Y direction
And

A signal layer in the X direction and a signal layer in the Y direction were transferred and laminated on both sides of the sheet 16 containing the fibers for the low dielectric constant layer to which the slurry 11 was applied.

Next, a layer having the cavity 15 was produced. The method of manufacturing the cavity is to apply the same slurry 11 as that applied to both sides of the fiber on a metal plate, make holes in predetermined positions with an electron beam, and fill the holes with the above-mentioned Cu conductor paste by printing. Via hole 3 was formed.

As shown in FIG. 5, a high frequency voltage is applied by sandwiching a green sheet 11 'for a low dielectric constant layer between an electrode 14 having a projection in the same pattern as the signal layer turn and a pair of conductors 14'. Applied. A cavity 15 is formed in the green sheet by the discharge by the high frequency voltage. The shape of the cavity 15 is a shape suitable for speeding up a signal.

Next, as shown in FIG. 7, the layer 16, X
The sheet 21 in which the above-mentioned voids were formed was transferred and laminated on both sides of the layer including the layer including the signal layer 5 in the Y direction.
Further, the conductor layer 4 was printed on the laminate. Then, this laminate and the green sheet 13 of the high-strength layer prepared above were
A total of five sets were stacked.

The binder was removed from the laminate in the same manner as in Example 1, and 980 was removed.
C. for one hour to obtain a fired product having a cavity 15 in contact with the signal layer 4. FIG.

The cavity 15 may be formed by irradiating the green sheet with a laser. In addition, a so-called photolithography technique is used in which a photosensitive resin is used as a ceramic binder, a wiring pattern is masked, ultraviolet rays are irradiated, and a pattern is formed by utilizing the difference in solubility of the photosensitive resin in a solvent. Can be used to form a cavity.

Further, when the slurry is applied to the fibrous sheet, the ceramic powder in the slurry hardly penetrates into the inside of the fiber, so that a sheet having a dense sheet surface and many pores inside the sheet is obtained.

By providing a fiber layer containing many cavities and pores around the signal layer, the capacitance per unit length of the signal layer can be reduced, and the signal propagation speed can be increased.

In addition, in the ceramic multilayer circuit board of this example shown in FIG. 6, no crack, peeling or the like was observed around the conductor layer 4 and the via hole 3. Furthermore, pins were attached to the fired product, and an LSI chip was mounted by CCB bonding. No cracks or the like were observed around the pinned portion, and no warping or deformation of the substrate was observed.

The bending strength of the ceramic multilayer circuit board of the present embodiment is 10 kgf /
mm ² and the signal propagation speed is 1.9 × 10 ⁸ m / sec.

Example 5 As shown in FIG. 4, as a green sheet for a high-strength layer, 75% by weight of SiO ₂ , 18% by weight of B ₂ O ₃ , and MgO ₂ were converted into oxides.
% By weight, 3% by weight of Li ₂ O + K ₂ O, ₂ % by weight of Al ₂ O _3, 50% by weight of glass powder having an average particle size of 5 μm, and 50% by weight of Al ₂ O ₃ powder having an average particle size of 1 μm. And a slurry was prepared in the same manner as in Example 1.

Next, a green sheet was produced in the same manner as in Example 4. The Pt-Ag paste used in Example 3 was filled in the green sheet by making a 100 μm φ hole. Further, the conductor layer 4 was formed by printing with the conductor paste.

Next, as the low dielectric constant layer green sheet, 40% by weight of the above-mentioned borosilicate glass powder 60% by weight and SiO ₂ hollow microspheres 28 having an average particle diameter of 20 μm and having pores therein were mixed at 40% by weight. A slurry is prepared on a silicone-coated polyester film using a
It was applied to a thickness of m and dried to prepare five green sheets having a thickness of 100 μm. A hole having a diameter of 100 μm was made in the green sheet, and the Pt-Ag paste was filled therein, thereby producing a low dielectric constant layer 7.

Next, two sheets of the low dielectric constant layer green sheet were used for an X-direction signal layer having a wiring width of 100 μm, and the other two sheets were used for a wiring width of 100 μm.
m for the Y-direction signal layer, and the remaining one was printed with the conductor layer 4 using the conductor paste.

The green sheet 21 containing the SiO ₂ hollow microspheres and the green sheet for the high-strength layer were set as one set, and five sets were laminated.

Next, in the same manner as in Example 1, after the binder was removed from the laminate, it was fired in the air at 950 ° C. for 1 hour to obtain a fired product.

By forming the low dielectric constant layer 7 including many pores around the signal layer 5 of the obtained multilayer circuit board, the capacitance per unit length of the signal layer 5 can be reduced,
The signal propagation speed could be increased. No crack, peeling, or the like was observed around the conductor layer 4 and the via hole 3.

In addition, the pin 8 and the LSI chip 1 were installed.
No cracks or the like were found around the pinned portion, and no warping or deformation of the substrate was found.

The bending strength of the ceramic multilayer circuit board of the present embodiment is 10 kgf /
mm ² and the signal propagation speed is 1.6 × 10 ⁸ .

Example 6 A slurry was prepared in the same manner as in Example 1, except that a raw material powder having a mixing ratio of 99% by weight of Al ₂ O ₃ powder having an average particle diameter of 0.1 μm and 1% by weight of MgO powder was used. Next, the above-mentioned slurry was applied to both sides of a 400 μm thick sheet in which the Al ₂ O ₃ long fibers 18 were knitted in a cross shape at a thickness of 200 μm, and after drying, a hole of 200 μm was made. Fill and place in nitrogen with hydrogen and steam
Firing at 00 ° C. for one hour produced the Al ₂ O ₃ plate 19 shown in FIG.

By combining the fibers 18 in this manner, the occurrence of warpage can be prevented even with a sintered body having a relatively large area.

Next, after both surfaces of the Al ₂ O ₃ plate 19 were polished, the laminated body containing the fibers of Examples 3 and 4 and the Al ₂ O ₃ plate were aligned and pressure-bonded. Firing under the same conditions, Al ₂ O ₃
A ceramic multilayer circuit board in which the board 19 and the glass ceramic were integrated was manufactured.

After electroless plating of Ni and Au on the W portion, pins 8 for inputting and outputting electric signals were soldered. Since the laminate containing fibers has a small firing shrinkage in the plane direction, it can be integrally fired with the Al ₂ O ₃ sintered body. In addition, pinning can be performed on an Al ₂ O ₃ plate having high strength, and pinning with high reliability can be performed.

Embodiment 7 FIG. 9 shows an outline of a semiconductor module using the multilayer circuit board of the present invention.

With the ceramic multilayer circuit board produced in the above embodiment
For connection to LSI chip 1, use polyimide 29 as insulating material and C
A copper-polyimide thin-film multilayer wiring 23 having u as the conductor layer 5 was formed, and the LSI chip 1 was mounted thereon via a carrier substrate 27. An AlN cap 22 is attached to the carrier substrate 27,
The cooling bellows 20 was mounted via cooling fins. In addition, it can be connected to the power supply circuit board 30 via the pins 8.

The semiconductor module has an excellent signal propagation speed and high strength characteristics that can withstand a severe heat cycle.

[Effects of the Invention] According to the present invention, since the conductor layer is formed at the interface between the low dielectric constant layer and the high strength layer, the low dielectric constant layer and the high strength layer are electrically separated from each other. The signal layer formed on the dielectric layer is less affected by the high-strength layer, so that a ceramic multilayer circuit board having a high signal propagation speed can be obtained.

Further, since the high-strength layer receives an external force applied to the ceramic multilayer circuit board, a ceramic multilayer circuit board having high strength can be obtained.

Further, a multilayer circuit board having a large number of laminations can be manufactured with high yield.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a ceramic multilayer circuit board of the present invention,
FIG. 2 is a flow chart of the manufacturing process of the ceramic multilayer circuit board of the present invention, FIG. _Two
FIG. 5 is a schematic view of a method of forming a cavity in a green sheet by a high-frequency current, and FIG. 6 is a ceramic multilayer circuit in which a cavity is formed in a low dielectric constant layer. FIG. 7 is a flow chart of a manufacturing process of the ceramic multilayer circuit board of FIG. 6, FIG. 8 is a schematic sectional view of a ceramic multilayer circuit board with a reinforcing plate, FIG.
The figure is a schematic sectional view of a semiconductor module using the ceramic multilayer circuit board of the present invention. 1 ... LSI chip, 2 ... solder, 3 ... via hole,
4 ... conductor layer, 5 ... signal layer, 6 ... high strength layer, 7 ...
Low dielectric constant layer, 8 Pin, 9 Conductor paste, 10
Polyester film, 11 Slurry, 11 ', 21 ... Green sheet for low dielectric constant layer, 12 ... Hole, 13 ... Green sheet for high strength layer, 14, 14' ... Electrode, 15 ... Cavity, 16
... ceramic paper, 17 ... high frequency power supply, 18 ... fiber, 19 ... reinforcing plate, 20 ... cooling bellows, 22 ... AlN
Cap, 23 ...... copper polyimide thin film multi-layer wiring, 24 ...... copper conductor, 25 ...... printed circuit board, 26 ...... coolant channel 27 ...... carrier substrate, 28 ...... SiO ₂ hollow microspheres, 29 ...... polyimide,
30 ... Power supply circuit board.

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Satoru Ogihara 4026 Kuji-cho, Hitachi City, Ibaraki Prefecture Within Hitachi Research Laboratory, Hitachi, Ltd. (56) References JP-A-60-132393 (JP, A) 136294 (JP, A) JP-A-61-22939 (JP, A) JP-A-2-83255 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H05K 3/46

Claims (7)

(57) [Claims] 1. A ceramic multilayer circuit board having a plurality of insulating layers made of a ceramic insulating material, a conductor formed between each insulating layer, and a via hole for electrically connecting the conductor of each layer. Consists of a laminate of two types of insulating layers, a high-strength layer and a low-permittivity layer. The high-strength layer is composed of a higher-strength material than the low-permittivity layer. The low-permittivity layer includes a signal layer, and a power supply layer or a ground layer is provided between the low-permittivity layer and the high-strength layer. Ceramic multilayer circuit board. 2. A ceramic multilayer circuit board having a plurality of insulating layers made of a ceramic insulating material, a conductor formed between the insulating layers, and a via hole electrically connecting the conductors of each layer. Comprises a plurality of laminates of two types of insulating layers, a high-strength layer and a low-permittivity layer, wherein the high-strength layer of the laminate is made of a higher-strength material than the low-permittivity layer; Is formed in an inner layer portion, a power supply layer or a ground layer is provided on both surfaces thereof, and the low dielectric constant layer is provided via the power supply layer or the ground layer, and the low dielectric constant layer is A ceramic multilayer circuit board having a signal layer. 3. A ceramic multilayer circuit board having a plurality of insulating layers made of a ceramic insulating material, a conductor formed between the insulating layers, and a via hole for electrically connecting the conductors of each layer. Consists of a multi-layered structure including two or more repetitions of a laminated structure composed of two types of insulating layers, a high-strength layer and two or more low-permittivity layers, and a signal layer is formed between the low-permittivity layers. A power layer or a ground layer is provided on a side of the low dielectric layer where the signal layer is not formed, and the high-strength layer is provided across the power layer or the ground layer. A ceramic multilayer circuit board comprising a material having a higher strength than a low dielectric constant layer. 4. A cavity is provided along a signal layer provided in the low dielectric constant layer and on a side of the low dielectric constant layer close to the power supply layer or the ground layer and adjacent to the signal layer. The ceramic multilayer circuit board according to any one of claims 1 to 3, wherein: 5. The ceramic material constituting the high-strength layer and the low-dielectric-constant layer has the same glass component.
_{4. The method according to claim} 1, wherein at least one of Al ₂ O ₃ , B ₄ C, and SiC, and the latter inorganic filler contains at least one of α-quartz, SiO ₂ , and SiO ₂ hollow microspheres. Item 10. A ceramic multilayer circuit board according to any one of the above items. 6. The ceramic multilayer circuit board according to claim 1, wherein a signal propagation speed of said signal layer is 1.2 × 10 ⁸ m / sec or more. 7. A semiconductor module in which a semiconductor element is mounted on a multilayer circuit board via a carrier substrate and the multilayer circuit board and the semiconductor element are electrically connected by the carrier substrate, wherein the multilayer circuit board is made of a ceramic insulating material. A plurality of insulating layers are laminated, conductors are formed between the insulating layers, and there are via holes for electrically connecting the conductors of the respective layers. The insulating layers are of two types: a high strength layer and a low dielectric constant layer. The high-strength layer is composed of a higher-strength material than the low-dielectric-constant layer, and at least one high-dielectric-constant layer sandwiched between the low-dielectric-constant layers is provided in the inner layer of the laminate. A semiconductor module comprising: a signal layer in the low dielectric constant layer; and a power supply layer or a ground layer provided between the low dielectric constant layer and the high strength layer.