JP5784153B2 - Alumina ceramics and ceramic wiring board and ceramic package using the same - Google Patents

Description

  The present invention relates to an alumina ceramic suitable for an insulating substrate requiring high strength, a ceramic wiring substrate and a ceramic package to which the alumina ceramic is applied.

  2. Description of the Related Art Conventionally, a ceramic wiring board has been widely used as a wiring board used for a package for storing electronic components such as a semiconductor element and a crystal resonator because it has relatively high mechanical strength and excellent airtightness.

  FIG. 2 shows an example of an exploded perspective view of a ceramic package for mounting electronic components. In a ceramic package for mounting an electronic component such as a crystal application product, for example, a conductor 102 is formed on the surface of a ceramic substrate 101 made of an alumina sintered body, and the electronic component mounted on the surface of the conductor 102 For example, a metal member 105 (here, a lid 105) for hermetically sealing (for example, a crystal application product) 109 is bonded via a bonding member 107 such as silver solder coated on the metallized layer 103. (For example, refer to Patent Document 1).

  The present applicant has previously proposed low-temperature fired alumina ceramics that can be fired simultaneously with a copper-based conductor as a substrate material applied to this type of ceramic package (for example, Patent Document 2 and Patent Document 2). 3).

  In recent years, mobile electronic devices such as mobile phones and IC cards have become widespread, but these electronic devices are increasingly required to be smaller, thinner, and higher performance. The electronic component 109 to be incorporated and the ceramic package for housing the electronic component 109 are also required to be further reduced in size and thickness.

When the ceramic package is reduced in size and thickness, the thickness t of the substrate bottom portion 101a constituting the ceramic substrate 101 located on the bottom surface of the ceramic package and the width w _{0 of the} substrate bank portion 101b serving as a portion to which the lid 105 is joined. Need to be narrowed.

However, the width _{w 0} of the thickness t and the substrate bank portion 101b of the substrate bottom portion 101a is, for example, when the extremely thin as 0.5mm or less, be applied to the substrate materials described above, joining the cover member 105 In doing so, there has been a problem that the substrate bottom 101a and the substrate bank 101b of the ceramic substrate 101 are deformed, which causes cracks in the ceramic substrate 101.

JP 2001-196485 A JP 2003-101238 A JP 2006-100364 A

  Accordingly, an object of the present invention is to provide an alumina ceramic having a high mechanical strength, a high-strength wiring board to which the ceramic ceramic is applied, and a ceramic package.

The alumina-based ceramic of the present invention contains aluminum oxide as a main component, contains 2.0 to 5.0% by mass of manganese in terms of Mn ₂ O ₃ and 3.0 to 7.5% by mass of silicon in terms of SiO ₂ , When the composition formulas of manganese and silicon are Mn ₂ O ₃ and SiO ₂ , respectively , the mass ratio represented by Mn ₂ O ₃ / (Mn ₂ O ₃ + SiO ₂ ) is 30 to 50%.
And further containing magnesium and molybdenum, wherein the magnesium is 0.3 to 0.7% by mass in terms of MgO, and the molybdenum is 0.3 to 0.7% by mass in terms of MoO, X-ray diffraction Rietbelt The proportion of the crystal phase mainly composed of aluminum oxide determined by analysis is 99.0 to 99.9 mass%, the average particle size of the crystal phase is 0.8 to 1.5 μm, and the unit 2. The area ratio of voids per area is 3. It is characterized by being 0 % or less.

  The ceramic wiring board of the present invention is a ceramic wiring board having a metallized layer on the surface of an insulating substrate, wherein the insulating substrate is made of the above-mentioned alumina ceramics.

  The ceramic package of the present invention is a ceramic package in which a metal member is bonded to the surface of an insulating substrate via a bonding member, and the insulating substrate is made of the above-mentioned alumina ceramics.

  According to the present invention, an alumina ceramic with high mechanical strength can be obtained. Further, by applying such alumina ceramics as a material for the insulating substrate, a high-strength ceramic wiring substrate and a ceramic package can be obtained.

It is a disassembled perspective view which shows one Embodiment of the ceramic package of this invention. It is a disassembled perspective view which shows one Embodiment of the conventional ceramic package.

Embodiments of the present invention will be described below. Alumina ceramic of the present embodiment, an aluminum oxide as a main component, contains from 3.0 to 7.5% by mass of 2.0 to 5.0 wt% and silicon in terms of SiO ₂ and manganese _Mn 2 _{O 3} in terms of It is out.

  Further, in this alumina ceramic, the ratio of the crystal phase mainly composed of aluminum oxide obtained by the Rietveld analysis of X-ray diffraction is 99.0 to 99.9% by mass.

  Further, the alumina ceramic has an average particle size of a crystal phase mainly composed of aluminum oxide (hereinafter referred to as alumina crystal phase) of 0.8 to 1.5 μm, and a void area ratio per unit area. Is 3.1% or less.

  According to the alumina ceramics of the present embodiment, although containing a considerable amount of manganese and silicon in addition to the main component of aluminum oxide, the proportion of the alumina crystal phase as the main crystal phase is as high as 99% by mass or more, Since the average grain size of the crystal phase is small and the area ratio of voids is small, the material is excellent in mechanical properties, and an alumina ceramic having a three-point bending strength of 680 MPa or more can be realized.

Usually, when an auxiliary component such as manganese oxide is contained in aluminum oxide, a crystal phase derived from a composite oxide such as MnAl ₂ O ₄ is formed at the grain boundary of the alumina crystal phase of the alumina ceramic which is a porcelain. However, in the alumina ceramic of the present embodiment, the ratio of the identifiable crystal phase present at the grain boundary of the alumina crystal phase is 1% by mass or less, and the alumina crystal phase is amorphous derived from manganese oxide or silicon oxide. By making the sintered state through the interstitial phase, the progress of the transition between the crystal phases is suppressed compared to the case where there are other crystal phases having different crystal structures adjacent to the alumina crystal phase. The strength of the alumina ceramic which is a sintered body can be increased. Here, the alumina crystal phase is present in the porcelain in the form of grain-shaped crystal particles.

  On the other hand, when the ratio of the alumina crystal phase obtained by Rietveld analysis of X-ray diffraction is lower than 99.0% by mass, there are many crystal phases other than the alumina crystal phase in the alumina ceramics. Thus, this reduces the mechanical strength of the alumina ceramic.

  When the proportion of the alumina crystal phase obtained by Rietveld analysis of X-ray diffraction is higher than 99.9% by mass, the amount of sintering aid such as manganese oxide or silicon oxide is considerably small. The adhesive strength between the crystal phases decreases, and in this case also, the mechanical strength tends to decrease.

When the content of manganese contained in the alumina ceramic is less than 2.0% by mass in terms of Mn ₂ O ₃ conversion, or the content of silicon in terms of SiO ₂ is less than 3.0% by mass Since the amount of the component serving as the sintering aid is reduced, there are many portions where the sintering aid does not reach the grain boundary of the alumina crystal phase, and the alumina crystal phase itself is likely to grow. Even in this case, the mechanical strength is lowered.

When the content of manganese contained in the alumina ceramic is more than 5.0% by mass in terms of Mn ₂ O ₃ or the content of silicon in terms of SiO ₂ is more than 7.5% by mass, alumina In this case, the mechanical strength tends to decrease because the ratio of the alumina crystal phase, which is a high-strength material, in the ceramic material is reduced.

  Further, the mechanical strength of the alumina ceramic is also lowered when the average grain size of the alumina crystal phase is out of the range of 0.8 to 1.5 μm. Here, when the average particle diameter of the alumina crystal phase is smaller than 0.8 μm, the mechanical strength decreases because the alumina crystal phase is atomized and the specific surface area is increased, and therefore the alumina crystal phase is increased by the grain boundary of the alumina crystal phase. This is probably because there are parts where auxiliary agents such as manganese oxide and silicon oxide do not reach.

  The mechanical strength decreases when the average grain size of the alumina crystal phase is larger than 1.5 μm. The mechanical strength of ceramics tends to decrease as the size of the fracture source increases. This is considered to be because the size of the fracture source that is generated when a load is applied increases as the average particle size increases.

  In addition, when the void area ratio per unit area of the alumina ceramic is larger than 3.1%, the mechanical strength is lowered because the size of the fracture source is increased.

  Here, the proportion of the crystal phase contained in the alumina ceramic is determined by performing X-ray diffraction on a powdered sample obtained by pulverizing the alumina ceramic, and Rietveld analysis on the obtained X-ray diffraction pattern. To determine the mass ratio of each crystal phase.

  The content of each component contained in the alumina ceramic is determined by atomic absorption analysis and ICP (Inductively Coupled Plasma) analysis. In this case, the obtained alumina ceramics are dissolved in an acidic solution, and the elements contained in the alumina ceramics are qualitatively analyzed by atomic absorption analysis, and then the standard solution is prepared by diluting the standard solution for each specified element. As described above, it is quantified by ICP emission spectroscopic analysis. The amount of oxygen is obtained based on the valence of each element shown in the periodic table.

  The average grain size of the alumina crystal phase is obtained by taking a photograph of 1000 to 5000 times using a scanning electron microscope on a polished surface obtained by polishing a cross section of a sample of an alumina ceramic, and then obtaining the photograph by the intercept method. .

  For the void area ratio, after the surface of the alumina ceramics is mirror-polished, the total area of voids (open pores) recognized within the predetermined area as the observation range is obtained by using an image analysis apparatus, and the predetermined void area is determined. Obtained as a percentage of the area.

  The mechanical strength is determined by a method based on JIS-R1601.

As described above, the alumina ceramic of the present embodiment has a mechanical structure because it has a crystal structure that suppresses generation of a crystal phase other than the alumina crystal phase even if it contains a considerable amount of additive components such as manganese and silicon. Although it is an excellent material, in this alumina ceramic, when the composition formulas of manganese and silicon are Mn ₂ O ₃ and SiO ₂ , respectively, it is expressed by Mn ₂ O ₃ / (Mn ₂ O ₃ + SiO ₂ ) The mass ratio is set to 30 to 50%, and magnesium and molybdenum are further included. The magnesium content is 0.3 to 0.7% by mass in terms of MgO, and the molybdenum content is 0.3 to 0 in terms of MoO. When the void ratio is 3.0% or less and the mechanical strength (3-point bending strength) of the alumina ceramic is 700 MPa or less. It can be.

  In addition, since the alumina ceramics of this configuration are adjusted to the composition of magnesium and molybdenum in addition to manganese and silicon, there is no color unevenness (including porcelain spots) and the appearance and design are beautiful ceramics. Can be.

  Further, when the metallized layer is formed on the surface of the alumina ceramic having this structure as an insulating substrate as will be described later, the metallized strength can be increased.

Furthermore, in this alumina ceramic, when the mass ratio represented by Mn ₂ O ₃ / (Mn ₂ O ₃ + SiO ₂ ) is 30 to 40%, the three-point bending strength can be increased to 710 MPa or more. In this case, the ratio of the crystal phase mainly composed of aluminum oxide contained in the alumina ceramic is preferably 99.2 to 99.9% by mass.

  As described above, since the alumina ceramic of the present embodiment is excellent in mechanical properties, it is suitable as an insulating substrate for various ceramic wiring boards and ceramic packages.

In this case, when a metallized layer is formed on the surface of an insulating substrate made of alumina ceramics, the metallized strength can be 43 N (kg · m / s ² ) or more, particularly 51 N (kg · m / s ² ) or more. This is because the amorphous phase of oxide containing manganese and silicon surrounding the alumina crystal phase has good wettability to the metallized layer (metal powder sintered body) side formed on the surface of the alumina ceramics. This is to penetrate.

  FIG. 1 is an exploded perspective view showing an embodiment of a ceramic package of the present invention.

  The ceramic package of the present embodiment has a metallized layer 3 arranged circumferentially on the surface of an insulating substrate 1 made of ceramic. On the upper surface of the metallized layer 3 arranged circumferentially, A joining member 7 for joining the metal member 5 such as a lid or a metal frame to the metallized layer 3 is provided.

  The insulating substrate 1 includes a plate-like substrate bottom portion 1a and a substrate bank portion 1b provided at the peripheral edge of the substrate bottom portion 1a, and the electronic component 9 is mounted on the surface of the substrate bottom portion 1a. A conductor 11 is formed.

This ceramic package is obtained by applying the high-strength alumina ceramic of the present embodiment to the substrate bottom 1a and the substrate bank 1b, which are insulating substrates. In order to reduce the size of the ceramic package, the substrate bottom 1a even by reducing the width w ₀ of the thickness t and the substrate bank portion 1b of the can suppress the deformation of the substrate bottom 1a and the substrate bank portion 1b which occurs when bonding the metal member 5 is the lid, the occurrence of cracks Can be prevented. Further, according to such a ceramic package, it is possible to reduce the strain generated at the interface between the insulating substrate 1 and the metallized layer 3 even if a reliability test such as a temperature cycle test is performed, and a highly reliable ceramic package. Can be obtained. In this case, the thin ceramic package has an average thickness of the substrate bottom portion 1a of 0.05 to 0.3 mm, particularly 0.05 to 0.2 mm, and an average thickness of the substrate bank portion 1b of 0.15 mm or less. It is suitable for.

  The material for forming the metallized layer 3 may be a metal material having a melting point higher than that of the material used for the bonding member 7. Molybdenum, tungsten, or an alloy thereof is used in view of enabling simultaneous firing with the ceramic substrate 1. The main component is good. In this case, copper or silver may be combined with molybdenum or tungsten according to the composition of the insulating substrate 1 and the sintering temperature.

  The ceramic component included in the metallized layer 3 is a ceramic material having a high melting point that does not melt in the temperature range where the metal material of the metallized layer 3 is sintered and remains in the metallized layer 3 after sintering. Is desirable. In this case, for example, oxides of alumina, zirconia, magnesia, and rare earth elements are suitable, but the main component of the insulating substrate 1 is that the strength of the metallized layer 3 mainly composed of molybdenum, tungsten, or the like can be increased. Aluminum oxide (alumina) is preferred. It is desirable that the conductor 11 has the same composition.

  The bonding member 7 is preferably a material that melts at a relatively low temperature (here, 900 ° C. or less) when heated and has a low viscosity and easily diffuses into the metallized layer 3. For example, silver brazing (Ag—Cu And materials containing a low melting point metal such as wood metal.

  As the metal member 5, a metal material such as Kovar, 4-2 alloy, Alsic (ALSiC) and the like, a composite of ceramics with a metal material, or a ceramic material can be applied.

  Next, an alumina ceramic according to the present embodiment, a ceramic wiring substrate to which the alumina ceramic is applied, and a method for manufacturing a ceramic package will be described.

First, after adding an organic binder to a ceramic powder in which a predetermined amount of aluminum oxide powder (hereinafter referred to as alumina powder), manganese oxide powder (Mn ₂ O ₃ powder) and silicon oxide powder (SiO ₂ powder) is mixed, For example, a plate-shaped raw molded body is formed by a known molding method such as a press method, a doctor blade method, a rolling method, or an injection method. In this case, if the ratio of Mn ₂ O ₃ powder and SiO ₂ powder is 30 to 50% in terms of Mn ₂ O ₃ / (Mn ₂ O ₃ + SiO ₂ ) ratio (mass ratio), it is included in the obtained alumina ceramics. The proportion of the crystal phase other than the alumina crystal phase can be further reduced.

The average particle size of the alumina powder, Mn ₂ O ₃ powder, and SiO ₂ powder used here is preferably in the range of 0.3 to 1.0 μm, whereby the alumina crystal phase in the alumina ceramics after firing In addition, the average particle diameter of the crystal grains can be 0.8 to 1.5 μm, and precipitation of crystal phases other than the alumina crystal phase can be suppressed at the grain boundaries of the alumina crystal phase.

  Next, after forming a conductor pattern on the surface of the green molded body as necessary, it is fired at a temperature of 1300 to 1600 ° C. in a reducing atmosphere, for example.

  When the ceramic package having the configuration shown in FIG. 1 is manufactured, first, a green sheet is produced as a raw molded body to be the substrate bottom 1a, and then a conductor pattern is formed on the surface thereof.

  The green molded body to be the substrate bank portion 1b is prepared by subjecting the green sheet to hole processing and then partially forming a conductor pattern on the surface around the hole of the green sheet. At this time, a sheet that has only been subjected to drilling is prepared as necessary.

  Next, the green sheet with the conductor pattern formed on the surface around the hole is laminated on the surface on which the conductor pattern of the green sheet, which will be the substrate bottom 1a, is formed and adhered to form a ceramic package for the shape shown in FIG. Form the body.

  As the paste for the conductor pattern, it is possible to use metal materials having various compositions in accordance with the sintering temperature of the ceramic powder. For example, a ceramic powder containing 80% by mass or more of alumina powder in a raw molded body In the case of using, it is preferable to use a metal material having a high melting point such as molybdenum or tungsten.

  In addition, a nickel plating film is formed on the surface of the metallized layer 3 of the obtained ceramic package, and a metal such as a lid or a metal frame is formed on the surface of the metallized layer 3 on which the nickel plating film is formed via a bonding member 7. The member 5 is joined.

  The ceramic package having the metal member 5 manufactured in this way has high mechanical strength of the insulating substrate 1 and high bonding strength between the metallized layer 3 and the metal member 5 through the bonding member 7, and appearance. There is no defect, and when the lid is bonded to the insulating substrate 1, it can be made highly airtight.

Next, experimental examples conducted for confirming the effects of the present invention will be described.

First, alumina powder, Mn ₂ O ₃ powder, SiO ₂ powder, MgO powder, and MoO ₃ powder having an average particle diameter of 0.5 μm were prepared as raw material powders for producing alumina ceramics.

  Next, after mixing these raw material powders in the proportions shown in Table 1, an acrylic binder is used as a molding organic resin (binder), and toluene is used as a solvent to prepare a slurry. Thereafter, a doctor blade method is used. A green sheet having a predetermined thickness was prepared.

  The obtained green sheet was laminated to a predetermined thickness, and a conductor pattern mainly composed of the metal shown in Table 1 was printed as needed, and fired at the temperature shown in Table 1. As the firing atmosphere, a nitrogen-hydrogen mixed atmosphere with a dew point of + 25 ° C. was used.

  Next, the following evaluation was performed on the obtained alumina ceramics.

  The ratio of each crystal phase was determined by Rietveld analysis after pulverizing the obtained alumina ceramics, identifying the main crystal phase by X-ray diffraction.

  The average grain size of the alumina crystal phase is determined by taking an approximately 3000-fold photograph using a scanning electron microscope on the polished surface obtained by polishing the cross section of the sample of the alumina ceramics, and then using this photograph by the intercept method. Asked.

For the void area ratio, the surface of the alumina ceramics is mirror-polished with an abrasive, and then the total area of voids (open pores) recognized within a predetermined area is obtained using an image analyzer (LUZEX-FS manufactured by Nireco). It was determined as a ratio to a predetermined area. At this time, the microscope magnification was about 100 times, and the measurement area was 9.0 × 10 ⁴ μm ² .

  The mechanical strength was obtained by preparing a beam-like sample having a thickness of 3 mm, a width of 4 mm, and a length of 40 mm, measuring it as a three-point bending strength at room temperature based on JIS R1601, and calculating from an average value of 35 pieces.

  The metallized strength is obtained by forming a conductor pattern on a green sheet so as to have a size of 2 mm × 20 mm after firing, firing by the same method as described above, applying Ni plating, and eutectic Ag-Cu brazing material. A lead pin made of Fe—Ni—Co was used to bond, and the load when peeled off by pulling vertically at a speed of 20 mm / min was evaluated as the metallization strength.

  In addition, after forming a plating film of electroless nickel (Ni) and gold (Au) on the metallized layer formed on the surface of the alumina ceramic, the appearance was observed at about 40 times using a stereomicroscope. The presence or absence of uneven color on the surface of the ceramic material (stains due to coloring of additive components) was evaluated. Moreover, the presence or absence of plating adhesion was also evaluated, and a sample in which color unevenness or plating adhesion was observed was judged as defective (x). In Table 1, “◯” indicates that there is no appearance defect.

  The composition of the prepared sample was determined by atomic absorption analysis and ICP analysis. In this case, the obtained alumina ceramics are dissolved in an acidic solution, and the elements contained in the alumina ceramics are qualitatively analyzed by atomic absorption analysis, and then the standard solution is prepared by diluting the standard solution for each specified element. As quantified by ICP emission spectroscopic analysis. The amount of oxygen was determined based on the valence of each element shown in the periodic table. All the compositions of the samples corresponded to the preparation compositions shown in Table 1.

As is apparent from the results shown in Table 1, the aluminum oxide as a main component, 3.0 to 7.5 wt% of manganese _Mn 2 _{O 3} and 2.0 to 5.0 wt% and silicon in terms of SiO ₂ in terms In addition, the ratio of the crystal phase mainly composed of aluminum oxide determined by Rietveld analysis of X-ray diffraction is 99.0 to 99.9% by mass, and the average grain size of the alumina crystal phase is 0.8 to 1 Sample No. 5 having a void area ratio of 3.1% or less per unit area. 1-4, 6-8, 10-17, 19 and 20 all had a three-point bending strength of 680 MPa or more.

Further, when the composition formulas of manganese and silicon are Mn ₂ O ₃ and SiO ₂ , respectively, the mass ratio represented by Mn ₂ O ₃ / (Mn ₂ O ₃ + SiO ₂ ) is 30 to 50%, and In addition, magnesium and molybdenum are contained, magnesium is 0.3 to 0.7% by mass in terms of MgO, molybdenum is 0.3 to 0.7% by mass in terms of MoO, and the void fraction is 3.0% or less. Sample No. In 1, 3, 4, 7, 8, 11, 12, 15, 16, 19 and 20, all three-point bending strengths were 705 MPa or more. In addition, these samples all had a metallization strength of 51 N or more, and had a good appearance without color unevenness or plating adhesion on the surface of the sample.

In particular, the sample in which the proportion of the alumina crystal phase is 99.2 to 99.9% by mass and the mass ratio represented by Mn ₂ O ₃ / (Mn ₂ O ₃ + SiO ₂ ) is 30 to 40%. No. In 1, 3, 4, 7, 11, 12, 15, 16, 19, and 20, all three-point bending strengths were 710 MPa or more.

  In contrast, sample no. In 5, 9, 18, 21 to 24, the three-point bending strengths were all lower than 680 MPa.

DESCRIPTION OF SYMBOLS 1,101 ..... Insulation board | substrate 1a, 101a ..... Board | substrate bottom part 1b, 101b ....... Board | substrate bank part 3, 103 ...・ ・ ・ ・ ・ Metalized layer 5, 105 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Metal member (lid)
7, 107 ..... Joining member 9, 109 ..... Electronic parts 11, 102 ..... Conductor

Claims (4)

Mainly composed of aluminum oxide, containing 2.0 to 5.0% by mass of manganese in terms of Mn ₂ O ₃ and 3.0 to 7.5% by mass of silicon in terms of SiO ₂ , the composition formula of manganese and silicon the when the _Mn 2 _{O 3} and SiO _{2, respectively,} the mass ratio expressed by _{Mn 2 O 3 / (Mn 2} O 3 + SiO 2) is 30 to 50% further comprises magnesium and molybdenum, the Magnesium is 0.3 to 0.7% by mass in terms of MgO, and molybdenum is 0.3 to 0.7% by mass in terms of MoO. The main component is the aluminum oxide obtained by Rietveld analysis of X-ray diffraction. The ratio of the crystal phase is 99.0 to 99.9% by mass, the average particle size of the crystal phase is 0.8 to 1.5 μm, and the void area ratio per unit area There 3. Alumina ceramics characterized by being 0 % or less. The ratio of the crystal phase mainly composed of aluminum oxide is 99.2 to 99.9 mass%, and the mass ratio represented by Mn ₂ O ₃ / (Mn ₂ O ₃ + SiO ₂ ) is 30 to 40. alumina ceramics according to claim 1, characterized in that the%. A ceramic wiring substrate having a metallized layer on a surface of an insulating substrate, wherein the insulating substrate is made of the alumina ceramics according to claim 1 or 2 . A ceramic package in which a metal member is bonded to the surface of an insulating substrate via a bonding member, wherein the insulating substrate is made of the alumina ceramics according to claim 1 or 2. .