JP6885705B2 - Ceramic sintered body and wiring board using it, and mounting components, modules and electronic devices equipped with this wiring board. - Google Patents

Description

The present invention relates to a ceramic sintered body, a wiring board using the ceramic sintered body, and mounting components, modules, and electronic devices provided with the wiring board.

Conventionally, a ceramic wiring board has been used as a package for accommodating an electric element such as an LSI.

The wiring board that becomes the package protects the stored electric elements from external shocks, humidity, heat, gas, light rays, etc., and the connection terminals provided on the outer circumference correctly transmit signals and power to the outside. It is used for the purpose of things, etc.

In recent years, for example, in automobiles, various sensor elements have come to be used in electronic control systems due to demands such as safety and comfort.

In this case, depending on the sensor element, it is necessary to mount a plurality of sensor elements having different characteristics on one wiring board. Therefore, a wiring board having a large size is required.

Further, some sensor elements, such as an angular velocity sensor, need to have a characteristic that they are hard to resonate with external vibration. Therefore, a wiring board having high rigidity is required.

Further, for LSIs and the like, it is necessary to lower the relative permittivity of the insulating layer in order to increase the speed of the transmission signal.

A wiring board that meets these requirements is required to have characteristics such as a large coefficient of thermal expansion, high mechanical strength, and a low relative permittivity.

Examples of the insulating material for forming such a wiring board include alumina and glass ceramics as candidate materials (see, for example, Patent Documents 1 and 2).

Japanese Unexamined Patent Publication No. 10-158032. Japanese Unexamined Patent Publication No. 2000-188453

However, it is difficult for alumina and glass ceramics to exhibit the above-mentioned three characteristics in a well-balanced manner. That is, the problem with alumina is that it basically has a small coefficient of thermal expansion. On the other hand, glass ceramics can greatly change the above three characteristics depending on the composition of the glass phase and the amount of inorganic particles added as a filler. For example, the amount of the filler added can be changed to improve the coefficient of thermal expansion. If this is done, there is a problem that the mechanical strength is greatly reduced.

Therefore, the present invention presents a new ceramic sintered body having a large coefficient of thermal expansion, high mechanical strength, and a low relative permittivity, a wiring board using the same, and mounting components and modules provided with the wiring board. And to provide electronic devices.

Ceramic sintered body of the present invention, the crystalline phase of the false Terai bets is 45-58 wt%, the crystal phase of spinel is 9-28 wt%, the crystal phase of tetragonal zirconia contains 23-37 wt% cage, the remainder being silicon oxide der shall.

The wiring board of the present invention is a wiring board provided with wiring on the surface of the insulating layer, and the insulating layer is the above-mentioned ceramic sintered body.

The mounting component of the present invention is one in which at least one electronic component of a semiconductor element, a sensor element, and a passive component is arranged on the surface or inside of the wiring board.

The module of the present invention has the above-mentioned mounting components mounted on a motherboard.

The electronic device of the present invention is electrically connected to a housing, a power supply unit and a display unit provided so as to be exposed from the inside of the housing to the surface, and the power supply unit and the display unit, respectively, and the display unit. An electronic device having a control unit for functioning the above-mentioned module.

According to the present invention, a ceramic sintered body having a large coefficient of thermal expansion, high mechanical strength, and a low relative permittivity, a wiring board using the ceramic sintered body, and mounting components, modules, and electronics provided with the wiring board. You can get the equipment.

It is a perspective view which shows typically the wiring board of this embodiment. (A) is a perspective view schematically showing a mounted component of the present embodiment, and (b) is a sectional view taken along line XX of (a). It is a perspective view which shows typically the module of this embodiment. It is an exploded perspective view which shows typically the electronic device of this embodiment.

The ceramic sintered body of the present embodiment has forsterite as a main crystal phase, which contains a spinel crystal phase and a zirconia crystal phase. Since the ceramic sintered body has forsterite as the main crystal phase, it is possible to obtain a ceramic sintered body having a ^{coefficient of thermal expansion of 7.2 × 10-6 / K or more.} Since this contains a spinel crystal phase and a zirconia crystal phase as the by-crystal phase, one having high mechanical strength can be obtained.

Here, the main crystal phase refers to the crystal phase having the highest content in the ceramic sintered body, and as described above, in the ceramic sintered body in which the three crystal phases coexist, it is contained in an amount of 40% by mass or more. Say what you have. The subcrystal phase has a lower content than the main crystal phase.

The ceramic sintered body of the present embodiment exhibits high thermal expansion and high strength because the crystal phase of the spinel is an equiaxed crystal system similar to that of diamond, and therefore the mechanical strength is high even by itself, and the main crystal. This is because the difference in melting point between the phase and the forsterite is within 200 ° C., so that both crystal phases are easily sintered.

Further, the crystal phase of zirconia originally shows a tendency that the crystal structure is transformed from, for example, a tetragonal system to a monoclinic system when a mechanical pressure is applied to the crystal. Therefore, when pressure is applied to the crystal, the stress is easily dispersed, which has the property of increasing toughness. In this ceramic sintered body, a zirconia crystal phase exhibiting the above-mentioned properties is interposed between the forsterite and spinel crystal phases, so that a ceramic sintered body having high mechanical strength can be obtained. As a result, this ceramic sintered body has a thermal expansion coefficient of 7.2 × ^10-6 / K or more and a mechanical strength of 288 MPa or more, so that a ceramic sintered body having high thermal expansion and high strength characteristics can be obtained. Can be done.

Further, this ceramic sintered body has a characteristic that the relative permittivity is 11 or less and the chemical resistance is excellent.

When the ratio of each crystal phase is specified for the ceramic sintered body of the present embodiment, the coefficient of thermal expansion and the mechanical strength are further higher, and the relative permittivity is lower.

For example, in the X-ray diffraction pattern, the total of the peak intensities of the main crystal phase of forsterite, which is the sum of the five from the one with the largest peak intensity, is IF, and for the crystal phase of spinel, the five from the one with the largest peak intensity are combined. When the total peak intensity is IS, when the IS / IF ratio is 0.35 to 0.55, the coefficient of thermal expansion is 7.3 × ^10-6 / K or more, and the mechanical intensity is 303 MPa or more. , A ceramic sintered body having a relative dielectric constant of 9.8 or less can be obtained.

In this case, the chemical formula of the compound when identifying each crystal phase from the X-ray diffraction pattern is that forsterite is Mg ₂ SiO ₄ , spinel is _{Mg Al 2} O ₄ , and zirconia is ZrO ₂ , but cations are analyzed. The ratio of oxygen to oxygen may vary slightly as long as the original structure of each crystal phase does not change.

Further, in this ceramic sintered body, the crystal phase of zirconia is preferably tetragonal. When the crystal phase of zirconia is tetragonal, the toughness is increased because stress is easily dispersed when a mechanical load is applied to the ceramic sintered body. As a result, the mechanical strength can be further increased. Specifically, when the crystal phase of zirconia contained in the ceramic sintered body is tetragonal, the coefficient of thermal expansion is 7.3 × 10 in the range where the IS / IF ratio is 0.37 to 0.55. ^{A ceramic sintered body having a mechanical strength of -6} / K or more and a mechanical strength of 308 MPa or more can be obtained.

Further, the IS / IF ratio is preferably 0.40 to 0.50. When the IS / IF ratio is 0.40 to 0.50, the mechanical strength is 308 MPa or more, the coefficient of thermal expansion is 8.0 × ^10-6 / K or more, and the relative permittivity is 9.7 or less. A sintered body can be obtained.

Here, a method for producing the ceramic sintered body of the present embodiment will be described. Forsterite powder, zirconia powder, and alumina powder are used as raw material powders for producing this ceramic sintered body. In this case, even if the spinel powder is not used, the added alumina powder reacts with the forsterite powder to form a spinel crystal phase adjacent to the forsterite crystal phase. This is called Mg-Al spinel. On the other hand, the zirconia powder remains as a crystal phase in the same composition ratio even after firing, and has a crystal structure coexisting with the forsterite crystal phase and the spinel crystal phase. In this way, a ceramic sintered body containing forsterite as the main crystal phase and containing the spinel crystal phase and the zirconia crystal phase can be obtained.

The composition of each crystal phase of forsterite, spinel, and zirconia constituting this ceramic sintered body is such that the crystal phase of zirconia is 23 to 37% by mass and that of forsterite is based on the compounding composition of Examples described later. The crystal phase is 45 to 58% by mass, the crystal phase of spinel is 9 to 28% by mass, and the balance is silicon oxide separated from forsterite. Silicon oxide exists as a crystalline phase or an amorphous phase at the grain boundaries of each of these forsterite, spinel and zirconia crystal phases. As a result, the crystal phases of forsterite, spinel and zirconia are firmly bonded to each other. As a result, a ceramic sintered body having a large coefficient of thermal expansion and high mechanical strength can be obtained.

FIG. 1 is a perspective view schematically showing a wiring board of the present embodiment. The wiring board A of the present embodiment has a basic structure in which a pad 2 and a wiring 3 provided so as to be connected to the pad 2 are provided on the surface 1a of the insulating layer 1, and the insulating layer 1 is fired with the above-mentioned ceramic. It is the one to which the union is applied. In this case, since the ceramic sintered body to be the insulating layer 1 has a high coefficient of thermal expansion and high mechanical strength, it is possible to obtain a wiring board A having high thermal expansion and high strength.

As the pads 2 and wiring 3 constituting the wiring substrate A, any low melting point metal such as copper and silver or high melting point metals such as tungsten and molybdenum can be applied, but the insulating layer 1 and the pad 2 A metal material obtained by compounding or alloying these is used from the viewpoint of optimizing the sinterability when the wiring 3 and the wiring 3 are fired at the same time and making the pad 2 and the wiring 3 dense to bring out high conductivity. Is good. In the wiring board A shown in FIG. 1, the wiring 3 is provided on the surface of the insulating layer 1, but the wiring 3 is not limited to this, and has a structure in which the wiring 3 is arranged inside the insulating layer 1 via a via conductor. Is also good.

2A is a perspective view schematically showing a mounted component of the present embodiment, and FIG. 2B is a sectional view taken along line XX of FIG. 2A. In the mounting component B of the present embodiment, at least one electronic component 5 of a semiconductor element, a sensor element, and a passive component is arranged on the surface 1a of the wiring board A. In this case, the electronic component 5 is connected to the wiring 3 provided on the surface 1a of the insulating layer 1 constituting the wiring board A via the connection terminal 6. In this case, as the connection terminal 6, a solder ball is suitable from the viewpoint that the wiring length of the connection terminal 6 can be shortened. In the mounting component B, the electronic component 5 may be arranged not only on the surface 1a of the insulating layer 1 constituting the wiring board A but also inside the insulating layer 1.

FIG. 3 is a perspective view schematically showing the module of the present embodiment. The module C of the present embodiment has the above-mentioned mounting component B mounted on the motherboard 7. In this case, the mounting component B is connected to the motherboard 7 via a predetermined connecting member. As the connecting member, solder balls, pins, sockets and the like are used.

As the motherboard 7, a circuit board in which an organic resin is used as an insulating material and a copper foil is formed as a wiring member on the surface thereof is suitable. The motherboard 7 using an organic resin as an insulating material has a coefficient of thermal expansion of ^{about 15 to 30 × 10-6} / K. Even when a motherboard 7 having such a large coefficient of thermal expansion is applied, a module C having high mounting reliability can be obtained. This is because the mounting component B to be mounted on the surface is formed by the wiring board A having the above-mentioned ceramic sintered body as the insulating layer 1, so that it is compared with the wiring board to which alumina or glass ceramics are applied as the insulating layer 1. Since both the thermal expansion coefficient and the mechanical strength are high, the connecting member connecting the wiring board A and the motherboard is less likely to crack, and the module C with high mounting reliability can be obtained.

FIG. 4 is an exploded perspective view schematically showing the electronic device of the present embodiment. Examples of the electronic device D include mobile phones, smartphones and tablets. The electronic device D of the present embodiment has a configuration in which the above-mentioned module C is built in the housings 11a and 11b assembled from above and below. In this case, the electronic device D controls a display unit 13 provided so as to be exposed on the surface of the housing 11a, a power supply unit 15 installed in one housing 11b, and the display unit 13 and the power supply unit 15. It has a control unit 17 installed in the housing 11b for the purpose of doing so. As a result, the electronic device D can withstand long-term use based on the high mounting reliability of the module C.

Hereinafter, the ceramic sintered body according to the present embodiment was specifically produced, and then a wiring board to which the ceramic sintered body was applied was produced.

First, as a mixed powder for preparing a green sheet, forsterite powder having an average particle size of 4 μm, alumina powder having an average particle size of 3 μm, and yttria-stabilized zirconia powder having an average particle size of 0.3 μm were prepared. A slurry was prepared by adding in the ratio shown in 1. An acrylic binder and toluene were used to prepare the slurry.

Next, using the prepared slurry, a green sheet having a thickness of 120 μm was prepared by the doctor blade method.

A plurality of the obtained green sheets were stacked and pressure-laminated so as to have a predetermined thickness. After that, a molded product was prepared by cutting into a predetermined size so as to be a sample for characteristic evaluation.

Next, the produced molded product was fired under predetermined conditions to prepare a ceramic sintered body as a sample for characteristic evaluation. In this case, the maximum temperature for firing was set to 1350 ° C., the dew point temperature was set to 19 ° C., and firing was performed in a nitrogen-hydrogen mixed atmosphere with a holding time at the maximum temperature of 1 hour.

Next, the characteristics of the prepared ceramic sintered body sample were evaluated. The relative density was obtained by dividing the bulk density obtained by the Archimedes method by the theoretical density. In this case, the theoretical density was set to a value based on the ratio of each crystal phase of forsterite, spinel and zirconia contained in the ceramic sintered body. The proportions of each crystal phase of forsterite, spinel and zirconia were measured using the Rietveld method. In this case, as the theoretical density of each crystal phase, forsterite 3.0 g / cm ^3, spinels 3.6 g / cm ³ and zirconia was used, respectively a value of 6.0 g / cm ^3.

In addition, the crystal phase contained in the ceramic sintered body was identified by using an X-ray diffraction method, and then the ratio of spinel to forsterite was determined from the peak intensity ratio. In the X-ray diffraction pattern, the total of the peak intensities of the five from the largest peak intensities of the main crystal phase of forsterite is IF, and for the crystal phase of spinel, the peak intensities of the five from the one with the largest peak intensities are combined. The IS / IF ratio was calculated by using the total of IS as IS.

Further, the produced ceramic sintered body was processed, and the three-point bending strength was measured based on JIS R1601.

Further, the ceramic sintered body was processed into a size of 10 mm in diameter, and the relative permittivity was measured at a frequency of 1 MHz.

In addition, the ceramic sintered body was processed, and the coefficient of linear thermal expansion was measured using a thermomechanical analyzer (TMA).

Moreover, the chemical resistance of the ceramic sintered body was evaluated by the following method. In the chemical resistance test, the weight loss rate of the sample piece between before and after the pretreatment and posttreatment steps excluding the plating film forming step was determined. The conditions for pretreatment and posttreatment are surface treatment using an etching solution containing sulfuric acid and ammonium persulfate, etching treatment using an ammonium fluoride solution, washing with water, and so on.
Alkaline degreasing and acid treatment. The results are shown in Table 1.

In addition, sample No. Using the green sheet of No. 5, a wiring board having the configuration shown in FIG. 1 was produced. As a conductor material for forming the wiring, a material containing 50% by volume of copper and tungsten was applied.

As shown in Table 1, Sample No. 1 was prepared from a ceramic sintered body in which forsterite was used as the main crystal phase, and the crystal phase of spinel and the crystal phase of zirconia were contained therein. In 1 to 13, the three-point bending strength was 288 MPa or more, the coefficient of thermal expansion was 7.2 × 10 ^-6 / K or more, and the relative permittivity was 10.2 or less. In addition, the weight change rate in the chemical resistance test was 0.14% or less.

Among these, Sample No. 1 in which the ratio (IS / IF ratio) of the peak intensity IS of the spinel crystal phase to the peak intensity IF of the X-ray diffraction pattern for the main crystal phase of forsterite is 0.35 to 0.55. In 2 to 8 and 10 to 13, the coefficient of thermal expansion was 7.3 × 10 ^-6 / K or more, the mechanical strength was 303 MPa or more, and the relative permittivity was 9.8 or less.

Further, among the samples in which the crystal phase of zirconia constituting the ceramic sintered body is a tetragonal system, the samples having an IS / IF ratio of 0.40 to 0.50 (Sample Nos. 3 to 7, 10 and 11). ), The mechanical strength was 308 MPa or more, the coefficient of thermal expansion was 8.0 × 10 ^-6 / K or more, and the relative permittivity was 9.7 or less.

On the other hand, in the sample (Sample Nos. 14 to 16) containing no one of the crystal phases of forsterite, spinel and zirconia in the ceramic sintered body, the three-point bending strength is 288 MPa or more and thermal expansion The coefficient ^{does not satisfy any of the characteristics of 7.2 × 10-6} / K or more and the relative permittivity of 10.2 or less.

Sample No. Even in the wiring board produced by using the ceramic sintered body of No. 5 as an insulating layer, each characteristic of the insulating layer is the sample No. It was equivalent to 5.

A ... Wiring board B ... Mounting component C ... Module D ... Electronic equipment 1 ... Insulation layer 1a・ ・ ・ ・ ・ ・ Surface 2 (of the insulating layer) ・ ・ ・ ・ ・ ・ ・ Pad 3 ・ ・ ・ ・ ・ ・ ・ ・ ・ Wiring 5 ・ ・ ・ ・ ・ ・ ・ ・ Electronic parts 6 ・ ・ ・ ・ ・ ・ ・ ・ Connection terminal 7 ・ ・ ・ ・ ・ ・ Motherboards 11a, 11b ・ Housing 13 ・ ・ ・ ・ ・ ・ Display unit 15 ・ ・ ・ ・ ・ ・ Power supply unit 17 ・ ・ ・ ・ ・ ・ Control unit

Claims (7)

False Terai bets crystalline phase 45-58% by weight, scan crystal phase of spinel is 9-28 wt%, the crystal phase of tetragonal zirconia contains 23-37 wt%, Ru balance silicon oxide der A ceramic sintered body characterized by that. In X-ray diffraction pattern, IF the total peak intensity of the combined five from the largest peak intensity of binding phase of the forsterite, the crystal phase of the spinel, the combined five from the direction of the peak intensity greater The ceramic sintered body according to claim 1, wherein the IS / IF ratio is 0.35 to 0.55, where IS is the total peak intensity. The ceramic sintered body according to claim 2, wherein the IS / IF ratio is 0.40 to 0.50. A wiring board having wiring on the surface of the insulating layer, wherein the insulating layer is the ceramic sintered body according to any one of claims 1 to 3. A mounting component characterized in that at least one electronic component among a semiconductor element, a sensor element, and a passive component is arranged on the surface or inside of the wiring board according to claim 4. A module characterized in that the mounting component according to claim 5 is mounted on a motherboard. A housing, a power supply unit and a display unit provided so as to be exposed from the inside of the housing to the surface, and a control unit electrically connected to the power supply unit and the display unit to function the display unit. An electronic device having the module according to claim 6 , wherein the control unit has the module.

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