JPH10167810A - Glass-ceramic sintered compact and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a glass-ceramic sintered compact suppressing the leaching of the glass phase and excellent in acid resistance in the case of contact with acidic chemicals such as a plating soln. SOLUTION: A mixture of borosilicate glass with a ceramic filler is compacted and fired in a mixed atmosphere contg. nitrogen and steam. By this firing, B2 O3 in the surface part is vaporized and the boron content of the surface of the resultant sintered compact is made lower than that in the central part. The peak height expressed as boron content in the surface part of the sintered compact measured by fluorescent X-ray analysis is especially <=90% of that in the central part. The borosilicate glass contains at least SiO2 , Al2 O3 , RO (R is at least one among Mg, Ca and Zn) and B2 O3 and is prepicitated a crystal phase at the time of firing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a glass ceramic sintered body useful as an insulating substrate for a wiring board such as a semiconductor storage package and a method for producing the same. It is about improvement.

[0002]

2. Description of the Related Art Conventionally, ceramic materials such as alumina have been used as wiring substrates for mounting semiconductor elements and the like, but recently, the dielectric constant and firing temperature are lower than those of alumina. Low resistance conductor, eg C
A glass ceramic sintered body has attracted attention as a substrate material which can be applied particularly to a demand for high integration of a circuit because it is excellent in that a wiring of u, Au, and Ag can be formed.

Conventionally, as a method of manufacturing a wiring board using a glass ceramic sintered body as an insulating substrate, for example, a green sheet made of a glass ceramic raw material composed of borosilicate glass or the like and a ceramic filler and an organic binder is punched. A through hole is formed, the through hole is filled with a conductive paste, and then the conductive paste is printed at a predetermined position on the sheet to form a conductive pattern. After aligning these sheets and laminating under pressure, the laminated body is heated to remove the binder and fire, thereby obtaining a glass ceramic multilayer wiring board.

As a conductor material of such a glass ceramic wiring board, Cu, Au, and Ag are used. Among them, Au lacks versatility in terms of cost, and is generally C
u or Ag is used. Ag conductors are advantageous in terms of cost because they can be fired in an air atmosphere and can be wire-bonded without plating the surface conductors. However, there is a problem in reliability due to migration and solder erosion.
Further, in order to improve these characteristics, Pd or the like is added to the conductor material to improve the properties. However, in this case, the conductor resistance is increased, and there is a problem particularly when used at high frequencies. On the other hand, a Cu conductor needs to be fired in a non-oxidizing atmosphere and plated with Ni or the like on the Cu conductor surface to prevent oxidation. However, there is an advantage that high reliability can be ensured.

[0005]

When Cu is used as a conductor material, a plating film is formed on the conductor on the surface in order to suppress the deterioration of wire bonding property and solder wettability due to oxidation of the conductor surface as described above. Need to be applied. In the plating step, a treatment liquid composed of an acidic solution such as hydrochloric acid is used, so that the glass ceramic material used as the substrate is required to have chemical resistance. However, in the conventional glass ceramic sintered body, when it comes into contact with such a treatment liquid, there are problems such as roughening of the surface of the sintered body and plating of the surface of the sintered body.

This is probably because the glass contained in the sintered body has poor acid resistance, and the glass phase is eluted by the acid treatment. As a glass having high acid resistance, a glass for physics and chemistry represented by Corning # 7740 glass is known. This glass has B ₂ to improve acid resistance.
The O ₃ amount has been optimized. When the amount of B ₂ O ₃ becomes excessive, B ₂ O ₃ reacts with water to form water-soluble H ₃ BO.
It is also known that they form ₃ , and the water resistance and the acid resistance decrease.

[0007] Borosilicate glass containing SiO ₂ and B ₂ O ₃ is most commonly used for the production of a glass-ceramic sintered body. In order to approximate, the sintering temperature of the sintered body is easily controlled to a low temperature of 900 to 1000 ° C., and the sintered body can be obtained at a low cost. In particular, recently, borosilicate glass that crystallizes at the time of firing to improve the strength of the sintered body is becoming mainstream.

When a sintered body is manufactured using such a borosilicate glass, a glass phase necessarily remains in the sintered body, and even in the case of crystallized glass, even if it is a small amount, A glass phase remains. The glass phase after the glass is crystallized is SiO ₂ , Al ₂ O ₃ , RO (R is Mg, C
a, Zn, etc.) and the composition of B ₂ O ₃ is often excessive. That is, in order to improve the acid resistance, it is considered necessary to reduce the amount of B ₂ O ₃ in the residual glass.

However, in the case of using glass having a reduced amount of B ₂ O _3, the melting temperature during glass production is high, and the sintering temperature of a glass ceramic material in which glass is mixed with a filler is high, and metal such as Cu There was a problem that simultaneous baking with was impossible.

[0010] Accordingly, an object of the present invention is to provide a glass-ceramic sintered body excellent in acid resistance, which suppresses elution of a glass phase when contacted with an acidic chemical such as a plating solution, and a method for producing the same. It is assumed that.

[0011]

Means for Solving the Problems As a result of repeated studies to solve the above-mentioned problems, the present inventors have found that at least a sintered body of a glass-ceramic comprising a borosilicate glass and a ceramic filler. The oxidation resistance of the sintered body can be improved by reducing the amount of B on the surface, in other words, the amount of B ₂ O ₃ , and when the sintering step is performed in an atmosphere in which nitrogen and steam are mixed, B ₂ O ₃ is reduced. It has been found that they can be volatilized and the amount of B ₂ O ₃ on the surface can be reduced, leading to the present invention.

That is, the glass-ceramic sintered body of the present invention is obtained by molding and firing a mixture comprising a borosilicate glass and a ceramic filler, and the B content on the surface of the sintered body is reduced by firing. It is characterized in that it is less than the B content at an internal depth of 30 μm or more from the surface of the consolidated body. In particular, the peak intensity height of boron in the fluorescent X-ray analysis of the surface of the sintered body is 90% or less of the peak intensity height of boron at a depth of 30 μm from the surface of the sintered body. The glass is at least SiO
₂ , a glass containing Al ₂ O ₃ , RO (R: at least one of Mg, Ca, Zn) and B ₂ O ₃ and capable of depositing a crystal phase during firing. is there. Further, as a method for producing such a sintered body, after molding a mixture of borosilicate glass and a ceramic filler, firing in a mixed atmosphere containing nitrogen and water vapor,
It is characterized in that B ₂ O ₃ on the surface is volatilized.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The glass ceramic sintered body of the present invention is obtained by molding and firing a mixture of borosilicate glass (in other words, glass containing at least SiO ₂ and B ₂ O ₃ ) and a ceramic filler. However, the most significant feature is that the B content on the surface of the sintered body is smaller than the B content at an internal depth of 30 μm or more from the surface of the sintered body.

When a plating layer is formed on the surface of a conductor layer when a wiring board or the like is manufactured, the glass ceramic sintered body serving as an insulating substrate must be brought into contact with a treatment solution such as hydrochloric acid in the plating step. become. In the present invention, by reducing the amount of B on the surface of the sintered body in contact with these chemicals, in other words, by reducing B ₂ O ₃ , the oxidation resistance is improved, and the elution of glass is prevented even when contacted with an acidic solution. In addition, the acid resistance of the sintered body can be improved.

According to the sintered body of the present invention, the B (boron) content tends to gradually increase as the outermost surface is the least and the inside is at least 30 μm deep from the surface. The B content is lower than the B content at the position, and at the deeper position, the B content may be equal to or more than the 30 μm depth position, and the B content is the largest at the center of the sintered body. .

From this point of view, the B content in the sintered body of the present invention is determined by X-ray fluorescence analysis (K
The peak intensity height of B at α-line) is 90% of the peak intensity height of B at a depth of 30 μm from the surface of the sintered body.
%, Particularly preferably 85% or less. According to the above, since the acid resistance is determined only by the surface characteristics of the sintered body, the B content on the surface of the sintered body is reduced. When the B content is low, the portion having a B content of 1 to 50 μm from the surface exists. It is desirable that the B content does not substantially change up to the center of the sintered body at a depth of 50 μm or more from the surface of the sintered body.

The absolute value of the amount of B in the sintered body is at least B (boron), and the relative content between the surface and the inside of the sintered body satisfies the above relationship. If so, it is not particularly limited, and is included in a suitable borosilicate glass capable of satisfying various properties such as simultaneous sinterability and electrical properties in terms of sinterability with a metal conductor such as Cu. It is appropriately determined by the amount of B ₂ O _{3 and the} like.

In the present invention, as a method for reducing the amount of B only on the surface of the sintered body, when firing a molded body composed of a mixture of a borosilicate glass and a ceramic filler, an atmosphere containing nitrogen and water vapor is used. Bake. When fired in an atmosphere containing water vapor in this manner, B ₂ O ₃ in the glass reacts with the water vapor in the atmosphere to form H ₃ BO
_In order to form and scatter _{3, the} amount of B ₂ O _{3 on the} surface of the sintered body can be reduced.

In this case, the B content is the smallest on the surface of the sintered body and gradually increases over the inside. At a depth of 30 μm or more, the borosilicate glass used in the present invention has a glass transition point of 600 ° C. or more, Particularly, a temperature of 650 ° C. or more is desirable. A typical glass composition is Si
O ₂ , Al ₂ O ₃ , RO (R is Mg, Ca and Zn
There is at least one) and alumino borosilicate glass containing B ₂ O ₃ as an essential component of, inter alia, SiO ₂ 35 to 55 wt%, Al ₂ O ₃ 10~3
5 wt%, RO10～30 wt%, it is desirable that the B ₂ O ₃ 5 to 15% by weight of the composition range. Other, Li ₂
Alkali metal oxides such as O, Na ₂ O, K ₂ O, ZrO
₂ , TiO ₂ and the like.

This glass has a high temperature at which the softening flow starts, and the firing shrinkage starting temperature of the material can be raised, so that the binder is easily removed in a non-oxidizing atmosphere, and the glass rapidly shrinks with respect to the temperature. B _{2 on} material surface only
It is possible to reduce the amount of O ₃ . What can crystallize the glass during firing is effective in increasing the bending strength of the material. In the case of crystallized glass, as described above, the crystal boundary of the crystal phase of the sintered body is reduced. High concentration of B
Since the glass is acid resistant likely to be generated is poor containing ₂ O _3, present invention since it is possible to suppress the generation of a high concentration of the content _of B ₂ O ₃ glass phase, is particularly effective.

On the other hand, when borosilicate glass having a low glass transition point such as # 7740 glass is used, the acid resistance can be improved by reducing the B content on the surface according to the present invention. The temperature at which firing shrinkage starts is low and it is difficult to perform sufficient debinding, the viscosity of the glass decreases slowly with temperature, and B ₂ O ₃ scatters before the material is densified, resulting in a porous material surface. It tends to be quality.

The ceramic filler mixed with the above glass can be selected according to the required material properties. Representative examples include alumina, silica, mullite, zirconia and the like.

More specifically, a mixture of 40 to 80% by volume of the above borosilicate glass and the above ceramic filler at a ratio of 20 to 60% by volume is mixed with an organic resin binder for molding and various molding aids. After the addition of the agent and the like, it is formed into an arbitrary shape by a desired forming means, for example, a die press, a cold isostatic press, injection molding, extrusion molding or the like. Examples of the method of forming the sheet include a doctor blade method, a calendar roll method, a rolling method, and the like.

Then, the molded body is heat-treated at 300 to 500 ° C. in an N ₂ or N ₂ + H ₂ O atmosphere to decompose and remove the organic resin binder in the molded body. 800-1 in an atmosphere containing
It can be manufactured by baking at a temperature of 000 ° C. for 0.1 to 2 hours. The steam pressure in the atmosphere during the firing is suitably 9 to 300 mmHg. In addition, 9mmHg
If it is lower than this, the effect of volatilizing B ₂ O _{3 on} the surface of the sintered body is not remarkable, and if it is higher than 300 mmHg, the metal is oxidized when co-fired with a metal such as Cu.

When a wiring board is manufactured using such a glass-ceramic sintered body, the above-mentioned glass powder and ceramic filler powder may be added to a molding organic material such as methacrylic acid resin which is excellent in thermal decomposability. A slurry is prepared by mixing a resin binder and a solvent, and a green sheet is formed by a doctor blade method or the like. Then, a paste containing a metal such as Cu, Au, or Ag is printed on the surface of the green sheet in the form of a wiring pattern, and in some cases, a through hole is formed in a predetermined portion of the green sheet, and the paste is filled. After that, the green sheets are aligned and press-laminated, and then the laminated body is 300 to 500
Heat treatment is performed in a nitrogen atmosphere containing water vapor at a temperature of .degree. C. to decompose and remove binders, plasticizers and solvents in the green sheets and metal paste.

Thereafter, the temperature is raised to 800 to 1000 ° C. in a nitrogen atmosphere containing water vapor as described above, and a small amount of carbon remaining in the substrate is reacted with water vapor to remove and densify the carbon. B _{2 on the} surface of the sintered body
O ₃ is stripped off. When crystalline glass is used, the glass is crystallized simultaneously with the densification. Further, the amount of B ₂ O _{3 on the} surface of the sintered body can be appropriately adjusted by the firing time and the like.

When a metal conductor, particularly a Cu conductor, of the glass ceramic wiring board is formed, the surface of the Cu conductor is plated. The type of plating film depends on the application, but Ni or Cu is plated on the base, and Au is
Should be plated.

[0028]

Examples: SiO ₂ : 44% by weight, Al ₂ O ₃ : 28% by weight, MgO: 11% by weight, ZnO: 8% by weight, B ₂ O
₃ : Based on a glass ceramic raw material powder composed of 61% by weight of crystalline glass powder having a composition of 9% by weight, 21% by weight of calcium zirconate powder, 16% by weight of strontium titanate powder, and 2% by weight of alumina powder. A slurry was prepared by adding isobutyl methacrylate resin as an organic binder in an amount of 12% by weight in terms of solid content and dibutyl phthalate as a plasticizer in an amount of 6% by weight, and using a ball mill for 40 hours with toluene and ethyl acetate as solvents to prepare a slurry.

The obtained slurry was formed into a green sheet having a thickness of 0.4 mm by a doctor blade method. A molded body obtained by pressing and laminating three such sheets, and C on the sheet
A molded body formed by pressing and laminating three sheets with the u paste printed thereon as the uppermost layer.

In order to decompose and remove organic components (binders, plasticizers, etc.) in the molded product, heat treatment is performed at 750 ° C. for 1 hour in a nitrogen atmosphere containing 55 mmHg of steam. Change to 1 and 900
℃ 1 hour firing, glass ceramic substrate and C
A wiring board provided with u wiring was obtained.

The obtained substrate was placed in 6N hydrochloric acid at room temperature for 1 hour.
The weight loss after immersion for 5 minutes was measured. Further, the amount of B on the surface of the sintered body was analyzed by fluorescent X-ray analysis using Kα radiation. Regarding the amount of B, when the surface of the sintered body was ground by 30 μm and the peak intensity I ₁ of B (boron) by fluorescent X-ray analysis of the surface was set to 100, the B amount by fluorescent X-ray analysis on the surface of the sintered body The ratio (I ₂ × 100 / I ₁ ) of the peak intensity I ₂ of (boron) was calculated. The specific gravity was measured by the Archimedes method. Further, the appearance of the Cu wiring after firing was observed for the wiring substrate. The results are shown in Table 1.
It was shown to.

[0032]

[Table 1]

As is evident from the results in Table 1, by adding steam to the atmosphere during firing, the B
It can be seen that the amount is reduced (the amount of B ₂ O _{3 in the} center of the sintered body is about 5.5% by weight), and as a result, the acid resistance is improved. Further, in this glass ceramic material, the specific gravity of the material did not change by changing the atmosphere during firing.
However, when the amount of water vapor was 360 mmHg, the Cu conductor was significantly oxidized.

Example 2 Glasses A (glass transition point: 710 ° C.) and B shown in Table 2
(Glass transition point: 520 ° C.) The same evaluation as in Example 1 was performed on a composition in which 50% by weight of each and alumina: 50% by weight of a filler were mixed. Table 3 shows the results.

[0035]

[Table 2]

[0036]

[Table 3]

From the results shown in Table 3, all the samples baked in an atmosphere containing water vapor and having a reduced B content on the surface exhibited superior oxidation resistance as compared with the samples not reduced in the B content. . However, when borosilicate glass B having a low glass transition point is used, the specific gravity is reduced by firing in an atmosphere containing a mixture of water vapor, and as a result of cross-sectional observation, it is confirmed that the substrate surface is porous. confirmed.

[0038]

As described above in detail, according to the glass ceramic sintered body of the present invention, the acid resistance of the sintered body can be greatly improved by reducing the amount of B ₂ O _{3 on the} surface. Accordingly, in the production of a wiring board or the like, even when the glass substrate comes into contact with a plating solution or the like, elution of the glass phase can be prevented, and the yield during manufacturing can be improved.

Claims (4)

[Claims] 1. A glass-ceramic sintered body obtained by molding and firing a mixture comprising borosilicate glass and a ceramic filler, wherein the surface of the sintered body has a boron content of 30 μm or more from the surface of the sintered body. A glass ceramic sintered body characterized in that the content is less than the boron content at the inner depth of the glass ceramic. 2. The peak intensity of boron in the surface of the sintered body in a fluorescent X-ray analysis is not more than 90% of the peak intensity of boron at a depth of 30 μm from the surface of the sintered body. Glass ceramic sintered body. 3. The method according to claim 1, wherein the borosilicate glass is at least Si.
_{2. The} glass according to claim 1, wherein the glass contains O ₂ , Al ₂ O ₃ , RO (at least one of R, Mg, Ca, and Zn) and B ₂ O ₃ and can precipitate a crystal phase during firing. Ceramic sintered body. 4. A glass ceramic sintering method comprising molding a mixture comprising a borosilicate glass and a ceramic filler, followed by firing in a mixed atmosphere containing nitrogen and water vapor to volatilize B ₂ O ₃ on the surface. How to make the body.