JP4231316B2 - Manufacturing method of ceramic wiring board - Google Patents

Description

【００５１】
【表２】

【００５２】
表２の結果からも明らかなように、メタライズ配線層およびビア導体に接触する気孔径５μｍ以上の気孔の数がメタライズ配線層およびビア導体の各周囲長さ１００μｍあたり２個以下である配線基板は、いずれも絶縁抵抗が１０^６Ω以上で、低いシート抵抗を維持していた。
【００５３】
【発明の効果】
以上詳述した通り、本発明のセラミック配線基板の製造方法によれば、屈伏点が６００〜８００℃のガラス成分を２０質量％以上含有し、焼成後の閉気孔率が５〜２０％、比誘電率が６以下であるセラミック組成物からなるグリーンシートに形成された貫通孔内に、銅を主体とする金属成分１００質量部に対して、屈伏点が６００〜８００℃のガラス成分１〜１０質量部と、クオーツ，フォルステライトおよびウラストナイトのうちのいずれかのフィラー１〜１０質量部とを含有する導体ペーストを充填してビア導体を形成するとともに、前記グリーンシート表面に、銅を主体とする金属成分１００質量部に対して、屈伏点が６００〜８００℃のガラス成分１〜１０質量部と、クオーツ，フォルステライトおよびウラストナイトのうちのいずれかのフィラー１〜１０質量部とを含有する導体ペーストを印刷塗布して導体パターンを形成した後、前記導体パターンおよび前記ビア導体を形成したグリーンシートを複数積層し、８００〜１０５０℃の非酸化性雰囲気中で焼成することにより、絶縁層が高い閉気孔率を有しながらも、配線基板中の銅メタライズ配線層や銅ビア導体の周囲の、銅メタライズ配線層や銅ビア導体と接触した気孔径５μｍ以上の気孔の数を少なくすることで、マイグレーションの発生を抑制でき、従来法による異種絶縁材料のペーストを塗布乾燥するなどの手法に比較してテープの伸び縮みも防止でき、焼成後の収縮バラツキもなく、絶縁材料の閉気孔率導入による低誘電率化を最大限に生かした配線基板を提供することができる。
【図面の簡単な説明】
【図１】本発明のセラミック配線基板の概略断面図である。
【図２】本発明のセラミック配線基板の要部拡大断面図である。
【図３】従来のセラミック配線基板の要部拡大断面図である。
【符号の説明】
１、１１・・・高気孔率層
２・・・低気孔率層
３、１３・・・配線層
４、１４・・・ビアホール
５、１５・・・気孔[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a ceramic wiring board and a manufacturing method thereof.
[0002]
[Prior art]
Conventionally, a ceramic wiring substrate has a structure in which a metallized wiring layer is disposed on or inside an insulating substrate in which ceramic insulating layers are laminated in multiple layers. As a typical example, a package for housing a semiconductor element such as an LSI is used. Can be mentioned. As such a package, an insulating layer made of ceramics such as alumina has been widely used. Recently, a wiring substrate that is fired at a low temperature such as glass ceramics that can be fired simultaneously with copper metallization has been put into practical use. It is being done.
[0003]
In such a ceramic wiring board, since the transmission speed is inversely proportional to the square root of the dielectric constant, the dielectric constant of the insulating board has been reduced, and the dielectric constant of the insulating material is generally 5-8. In recent years, since the frequency of use has been increased, a substrate material having a lower dielectric constant has been demanded.
[0004]
In order to achieve such a low dielectric constant, improvements have been made to insulating substrate materials. As one method for reducing the dielectric constant of such an insulating substrate, as shown in FIG. It has been proposed to reduce the dielectric constant by introducing pores 12 having a dielectric constant of substantially 1, in other words, by making the insulating substrate 11 porous (for example, Patent Document 1, 2, 3). In Patent Documents 1 and 2, a ceramic paste containing no carbon powder is applied to both sides of a green sheet containing carbon powder for generating fine pores, a hole is formed by punching, and a conductive paste is embedded. Further, it is described that a conductor paste is printed, laminated, and fired simultaneously.
[0005]
[Patent Document 1]
JP-A-12-185977 [0006]
[Patent Document 2]
Japanese Patent Laid-Open No. 2002-308678
[Patent Document 3]
Japanese Patent Publication No. 7-72092 [0008]
[Problems to be solved by the invention]
However, in the case of the structures of Patent Documents 1 and 2, as shown in FIG. 3, a portion where the metallized wiring layer 13 and the via conductors 14 and the pores 12 are in direct contact is generated, resulting in a high temperature and high humidity atmosphere. When exposed, migration occurs from the metallized wiring layer 13 and the via conductor 14 via the pores 12, resulting in a problem that the reliability of the circuit is lowered.
[0009]
With respect to such a problem, Patent Document 3 describes that a ceramic paste capable of forming a dense layer is applied to the front and back surfaces of a porous green sheet. According to this method, although the migration between the metallized wiring layers can be suppressed, the via conductor is in contact with many pores, so that there is a problem such as migration or a decrease in insulation resistance between the via conductors. there were.
[0010]
In addition, the method of Patent Document 3 is not only complicated in the process of separately applying the paste to the surface of the green sheet, but also due to the expansion and contraction of the tape caused by applying and drying a paste of a different material. There was a problem that variation in shrinkage occurred.
[0011]
Accordingly, an object of the present invention is to provide a ceramic wiring board with improved reliability of a metallized wiring layer or via conductor formed on a low dielectric constant insulating layer containing a large amount of pores, and a method for manufacturing the same.
[0012]
[Means for Solving the Problems]
In the case where the metallized wiring layer and via conductor are formed on the insulating layer containing a large amount of pores as described above, the present inventor has pores adjacent to the periphery of the metallized wiring layer and via conductor provided in the substrate. As a result, it was found that migration can be suppressed due to pores existing around the metallized wiring layer.
[0015]
That is, the method for producing a ceramic wiring board of the present invention contains 20% by mass or more of glass powder having a yield point of 600 to 800 ° C., a closed porosity after firing of 5 to 20%, and a relative dielectric constant of 6 or less. In a through-hole formed in a green sheet made of a ceramic composition, with respect to 100 parts by mass of a metal component mainly composed of copper, 1 to 10 parts by mass of a glass component having a yield point of 600 to 800 ° C., quartz, A via paste is formed by filling a conductor paste containing 1 to 10 parts by mass of any one of forsterite and wollastonite, and 100 masses of a metal component mainly composed of copper on the surface of the green sheet. 1 to 10 parts by mass of a glass component having a yield point of 600 to 800 ° C., and a filler of quartz, forsterite and wollastonite After forming a conductor pattern by printing and applying a conductor paste containing 10 parts by mass to 10 parts by mass, a plurality of green sheets on which the conductor pattern and the via conductor are formed are stacked, and in a non-oxidizing atmosphere at 800 to 1050 ° C. It is characterized by firing.
[0016]
It is desirable that the yield point of the glass component in the conductor paste for the conductor pattern and the yield point of the glass component in the conductor paste for the via conductor are not more than the yield point of the glass in the ceramic composition, It is desirable that the glass component in the conductor paste for the conductor pattern and the glass component in the conductor paste for the via conductor are made of the same glass composition as the glass component in the ceramic composition. As a result, the glass component penetrates into the pores near the metallized wiring layer, and the pores can be eliminated.
[0018]
Furthermore, the average particle size of the glass component in the conductor paste for the conductor pattern and the glass component in the conductor paste for the via conductor is less than the average particle size of the glass in the ceramic composition. Desirably, this can also promote the penetration of the glass into the pores. The average particle size is preferably 0.5 to 5 μm from the viewpoint of printability and glass penetration.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
The ceramic wiring board A of the present invention, for example, as shown in FIG. 1, is simultaneously with the insulating layers 1a to 1d between the insulating substrate 1 formed by laminating a plurality of insulating layers 1a to 1e and the insulating layers 1a to 1d. Copper metallized wiring layer 2 (hereinafter sometimes simply referred to as a metallized wiring layer) formed by firing and a copper via conductor formed through the insulating layers 1a to 1d and connecting the copper metallized wiring layer 2 3 (hereinafter sometimes simply referred to as via conductor).
[0020]
In addition, as shown in the enlarged view of the main part of FIG. 2, the insulating layers 1 a to 1 d can reduce the dielectric constant of the insulating layers 1 a to 1 d by introducing a large amount of pores 4. Specifically, it is a copper metallized wiring having a closed porosity of 5% or more, particularly 10% or more, more preferably 15% or more, and a relative dielectric constant of 6 or less, particularly 5 or less, or even 4 or less. This is important in reducing the loss of the high-frequency signal transmitted through the layer 2. In order to maintain the strength of the substrate, the closed porosity is desirably 20% or less.
[0021]
The metallized wiring layer 2 is preferably formed of a low-resistance conductor material mainly composed of copper or silver in order to reduce transmission loss of high-frequency signals.
[0022]
Then, when the metallized wiring layer 2 made of such a low-resistance conductor material and the insulating layer are simultaneously fired, the insulating layer 1 is preferably a ceramic that can be fired at a low temperature of 800 to 1050 ° C.
[0023]
In this respect, the insulating layer is preferably made of a composite of a glass component and a ceramic filler component.
[0024]
As the glass component, a glass containing SiO ₂ , for example, a well-known glass component such as borosilicate glass, barium silicate glass, or alkali silicate glass, 20 to 80% by mass, and a ceramic filler component 20 to 80% by mass is preferably used. it can. The filler component contains at least one of Al ₂ O ₃ , SiO ₂ , alkali oxide, alkaline earth oxide, such as alumina, diopsite, cordierite, mullite, quartz, cristobalite, serdian, It is desirable to contain at least one selected from the group consisting of forsterite, alkali silicate, spinel, CaTiO ₃ , SrTiO ₃ , and BaTiO ₃ .
[0025]
In particular, glass and filler can be properly used depending on the purpose. For example, in order to increase the strength, the filler may be selected from the group consisting of Al ₂ O ₃ , diopsite, cordierite, mullite, and spinel. At least one selected is suitable, and quartz, cristobalite, serdian, forsterite, alkali silicate, etc. are suitable if high thermal expansion is desired.
[0026]
The metallized wiring layer 2 and the via conductor 3 in the present invention have a pore diameter of 5 μm or more in the insulating layer in contact with the periphery of the via conductor 3 and the metallized wiring layer 2 when the cross sections of the metallized wiring layer 2 and the via conductor 3 are observed. It is important that the number of pores is 2 or less, particularly 1 or less, and even 0 per 100 μm peripheral length of the metallized wiring layer and via conductor. That is, if the number of pores in contact around the metallized wiring layer 2 and the via conductor 3 is larger than the above, migration occurs through the contacted pores, and insulation reliability between metallized wiring layers and via conductors is generated. The nature will decline.
[0027]
In this way, even if the insulating layer 2 of the ceramic wiring board A has a high porosity by controlling the number of pores in contact around the metallized wiring layer 2 and the via conductor 3, the metallized wiring layer Further, the occurrence of migration between via conductors can be suppressed. In addition, since different types of insulating materials are not used as in the past, the occurrence of shrinkage variations, warpage, and peeling due to differences in shrinkage behavior between different types of materials is prevented, and the porosity of the insulating layer is maximized. A wiring board having a low dielectric constant can be obtained.
[0028]
In the above-described wiring board A in the present invention, the metallized wiring layer 2 and the via conductor 3 are both quartz and 1% by mass or more of metal (amorphous) and metal oxide filler (crystalline) in addition to copper. It is desirable to contain 1% by mass or more of any filler of forsterite and wollastonite.
[0029]
This is because glass is contained in the metallized wiring layer 2 and the via conductor 3 so that the glass can enter the pores in contact with the metallized wiring layer 2 and the via conductor 3 to fill the pores.
[0030]
Therefore, when the glass amount is less than 1% by mass, the glass component does not enter the pores near the metallized wiring layer, and the pores remain. As a result, the pores in contact around the metallized wiring layer 2 and the via conductor 3 It becomes difficult to reduce the number. The glass content is preferably 1.5% by mass or more, and more preferably 2% by mass or more. In order to maintain the low resistance of the metallized wiring layer 2 and the via conductor 3, the glass amount is desirably 10% by mass or less, particularly 5% by mass or less.
[0031]
Further, when the amount of the metal oxide filler is less than 1% by mass, the sintering of the copper powder starts during the debinding, and pores due to defective debonding are likely to remain in the sintered body. It becomes difficult to reduce the number of pores in contact around the via conductor 3. The amount of the metal oxide filler is preferably 1.5% by mass or more, particularly 2% by mass or more. In order to maintain the low resistance of the metallized wiring layer 2 and the via conductor 3, the amount of the metal oxide filler is preferably 10% by mass or less, particularly 5% by mass or less.
[0032]
Moreover, it is desirable that the glass powder in the conductor paste is made of the same glass composition as the glass powder in the ceramic composition. As a result, the glass component easily enters the pores in the vicinity of the metallized wiring layer, and the pores can be effectively eliminated.
[0033]
Furthermore, it is desirable that the yield point of the glass powder in the conductor paste and the glass powder in the ceramic composition is equal to or less than the yield point of the glass forming the insulating layer, whereby the glass penetrates into the pores. Can be promoted. From the viewpoint of debinding and glass penetration, the yield point is preferably 600 to 800 ° C.
[0034]
Furthermore, the average particle size of the glass in the conductor paste is more preferably equal to or less than the average particle size of the glass forming the insulating layer, and this also promotes the penetration of the glass into the pores. I can do it. The average particle size is preferably 0.5 to 5 μm from the viewpoint of printability and glass penetration. When the thickness is less than 0.5 μm, the glass components are aggregated, the glass enters the pores sparsely, and the pores are likely to remain. Moreover, the printability of a conductor paste can be improved by setting it as 5 micrometers or less.
[0035]
Next, the manufacturing method of the ceramic wiring board of this invention is demonstrated. First, a glass ceramic composition is prepared with the glass and ceramic filler as described above. Such a glass-ceramic composition can produce a ceramic having a closed porosity of 5 to 10% by controlling the firing conditions by itself, but increases the closed porosity for further lowering the dielectric constant. In order to form stably, an additive (carbon, BN, resin, etc.) that is scattered during firing is added to such a glass ceramic composition, or a foaming source that generates gas in the glass (for example, hydration) Pores can also be generated. Using these techniques, the closed porosity is controlled to about 5 to 20% after firing.
[0036]
Next, after adding an appropriate organic resin binder to the above glass ceramic composition, any desired molding means such as injection molding, extrusion molding, doctor blade method, calender roll method, etc. may be used. Mold into green sheets.
[0037]
The obtained green sheet is subjected to through-hole processing with an NC puncher or mold, filled with a conductive paste made of a desired metal material to form a via hole, and further, a screen printing method or a gravure printing method with a desired pattern using the conductive paste. It forms by well-known methods, such as.
[0038]
At this time, as a conductor paste to be used, glass is 1 part by mass or more and 10 parts by mass or less and oxide filler is 1 part by mass or more and 10 parts by mass or less with respect to 100 parts by mass of low resistance metal powder mainly composed of copper. In addition to this, a kneaded mixture of resin and solvent is used. The low-resistance metal powder is preferably spherical from the viewpoint of printability, and more preferably having an average particle diameter of 1 to 5 μm.
[0039]
The glass blended in the conductor paste has a yield point below the yield point of the glass in the glass ceramic composition from the viewpoint of allowing the glass to penetrate into the pores around the metallized wiring layer and via conductor, the ceramic composition It consists of the same glass composition as the glass powder in the product, the average particle size of the glass powder is equal to or less than the average particle size of the glass powder in the ceramic composition, and the yield point of the glass powder is 600 It is desirable to satisfy at least one or more selected from the group of ˜800 ° C. and an average particle size of the glass powder of 0.5 to 5 μm.
[0040]
In addition, about the metallized wiring layer and the via-hole conductor, a paste having exactly the same composition may be used, or a composition in which the composition ratio is appropriately changed may be used.
[0041]
Next, the ceramic green sheets coated with the conductive paste and filled with the conductive paste as described above are laminated in a desired layer configuration and integrated to obtain a green sheet laminate for a ceramic substrate.
[0042]
Next, in firing the green sheet laminate, first, the binder component blended for molding is removed. The removal of the binder can be performed in a nitrogen atmosphere containing water vapor at 100 to 700 ° C. At this time, the shrinkage start temperature of the molded body is preferably about 700 to 850 ° C., and if the shrinkage start temperature is lower than this, it becomes difficult to remove the binder. It is necessary to control the yield point as described above.
[0043]
Firing is performed in a non-oxidizing atmosphere such as humidified nitrogen at 850 to 950 ° C. Thus, the glass ceramic composition is sintered to produce a sintered body having an open porosity of 2% or less and a closed porosity of 5 to 20%. At the same time, in the pores in contact with the metallized wiring layer and via conductor, the glass component in the metalized wiring layer and via conductor elutes and fills the pores. As a result, the pores in contact with the metalized wiring layer and via conductor The number can be reduced.
[0044]
The ceramic wiring board of the present invention includes a BGA (ball grid array), a CSP (chip scale package), and an LCC (leadless chip) in which electrical elements such as semiconductor elements and LED elements are housed in an upper surface of the wiring board or inside a cavity. The present invention can be applied to electrical element storage packages such as carriers) and various multilayer substrates. In particular, the present invention is particularly suitably used for high-frequency applications using microwaves or millimeter waves having a signal frequency of 1 GHz or more, particularly 5 GHz or more, and further 30 GHz or more.
[0045]
【Example】
As a glass ceramic composition for forming an insulating substrate having a high porosity, an average composition composed of SiO ₂ / BaO / B ₂ O ₃ / CaO / Al ₂ O ₃ = 44/23/14/12/7 in terms of mass ratio Glass blade A having a particle diameter of 3.5 μm and 50 vol% quartz having an average particle diameter of 3 μm and a slurry obtained by adding 12% acrylic resin, 4% plasticizer and appropriate toluene to form a slurry. A green sheet having a thickness of 100 μm was formed. Thereafter, through-hole processing with a diameter of 50 μm was performed on this green sheet by NC punching.
[0046]
On the other hand, with respect to 100 parts by mass of spherical copper powder having an average particle size of 3 μm, the composition shown in Table 1 is used. Then, an acrylic resin and terpineol were added to prepare a conductor paste, which was filled in the through hole by screen printing, and printed on a circuit pattern on the surface of the green sheet to form a metallized wiring layer. A plurality of ceramic green sheets produced in the same manner were laminated and pressure-bonded, and after a binder removal treatment at 700 ° C. for 1 hour, firing was performed in a humidified nitrogen atmosphere at 900 ° C. for 1 hour.
[0047]
Further, a green sheet was laminated without forming the metallized wiring layer and the via conductor and fired in the same manner as described above. The open porosity and closed porosity of the produced sintered body were measured. The measurement was performed by the Archimedes method.
[0048]
About the produced glass ceramic wiring board, the cross section is observed, and the vicinity of the interface between the via conductor exposed in the cross section and the insulating layer of the metallized wiring layer is observed, and each peripheral length of the metallized wiring layer and the via conductor is 100 μm. In the interface length, the number of pores in contact with the metallized wiring layer and the via conductor was observed. For each sample, 10 portions of 100 μm were measured, and the average is shown in Table 1.
[0049]
In addition, a migration test was performed as follows. A 40 × 40 μm solid layer was printed on a green sheet having a thickness of 50 μm after firing, and two of these layers were stacked and subjected to a high-temperature, high-humidity bias test at 85 ° C., 85%, 5.5 V, and 1000 hours later The change in insulation resistance was measured. The judgment was 10 ⁶ Ω or more as good. Furthermore, the sheet resistance of the metallized wiring layer was measured.
[0050]
[Table 1]

[0051]
[Table 2]

[0052]
As is clear from the results in Table 2, the number of pores having a pore diameter of 5 μm or more in contact with the metallized wiring layer and via conductor is 2 or less per 100 μm perimeter length of the metalized wiring layer and via conductor. In either case, the insulation resistance was 10 ⁶ Ω or more and the low sheet resistance was maintained.
[0053]
【The invention's effect】
As described in detail above, according to the method for manufacturing a ceramic wiring board of the present invention, the glass component having a yield point of 600 to 800 ° C. is contained in an amount of 20% by mass or more, and the closed porosity after firing is 5 to 20%. In a through hole formed in a green sheet made of a ceramic composition having a dielectric constant of 6 or less, a glass component 1 to 10 having a yield point of 600 to 800 ° C. with respect to 100 parts by mass of a metal component mainly composed of copper. Filled with a conductor paste containing 1 part by mass of filler and 1-10 parts by mass of any one of quartz, forsterite and wollastonite to form a via conductor, and the green sheet surface is mainly composed of copper 1 to 10 parts by mass of a glass component having a yield point of 600 to 800 ° C., and any one of quartz, forsterite and wollastonite with respect to 100 parts by mass of the metal component A conductor paste containing 1 to 10 parts by weight of the filler is printed and applied to form a conductor pattern, and then a plurality of green sheets on which the conductor pattern and the via conductor are formed are stacked, and non-oxidized at 800 to 1050 ° C. By firing in an oxidizing atmosphere, the insulating layer has a high closed porosity, but the air in contact with the copper metallized wiring layer and copper via conductor around the copper metallized wiring layer and copper via conductor in the wiring board By reducing the number of pores with a pore size of 5 μm or more, the occurrence of migration can be suppressed, and tape expansion and contraction can be prevented as compared with a method of applying and drying a paste of a different insulating material by a conventional method. There is no shrinkage variation, and a wiring board that makes the best use of the low dielectric constant by introducing the closed porosity of the insulating material can be provided.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view of a ceramic wiring board according to the present invention.
FIG. 2 is an enlarged cross-sectional view of a main part of a ceramic wiring board according to the present invention.
FIG. 3 is an enlarged cross-sectional view of a main part of a conventional ceramic wiring board.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1, 11 ... High-porosity layer 2 ... Low-porosity layer 3, 13 ... Wiring layer 4, 14 ... Via hole 5, 15 ... Pore

Claims (5)

  A penetration formed in a green sheet made of a ceramic composition containing a glass component having a yield point of 600 to 800 ° C. of 20% by mass or more, a closed porosity after firing of 5 to 20%, and a relative dielectric constant of 6 or less. In a hole, with respect to 100 parts by mass of a metal component mainly composed of copper, 1 to 10 parts by mass of a glass component having a yield point of 600 to 800 ° C., and a filler of any one of quartz, forsterite and wollastonite A via conductor is formed by filling a conductor paste containing 1 to 10 parts by mass, and the yield point is 600 to 800 ° C. with respect to 100 parts by mass of a metal component mainly composed of copper on the green sheet surface. A conductor paste containing 1 to 10 parts by weight of a glass component and 1 to 10 parts by weight of any one of quartz, forsterite and wollastonite is printed and applied. After forming the conductor pattern, the conductor pattern and a green sheet to form the via conductor and stacked method of the ceramic wiring board and firing in a non-oxidizing atmosphere at 800 to 1050 ° C.. The yield point of the glass component in the conductor paste for the conductor pattern and the yield point of the glass component in the conductor paste for the via conductor are less than or equal to the yield point of the glass in the ceramic composition. A method for producing a ceramic wiring board according to 1 . The glass component in the conductive paste for the glass component and the via conductors in a conductor paste for the conductor pattern, claim, characterized in that it consists of the same glass composition and glass components of the ceramic compositions in one or A method for manufacturing a ceramic wiring board according to claim 2 . The average particle size of the glass component in the conductor paste for the conductor pattern and the glass component in the conductor paste for the via conductor is equal to or less than the average particle size of the glass component in the ceramic composition. The manufacturing method of the ceramic wiring board in any one of Claims 1 thru | or 3 . Any of claims 1 to 4, wherein an average particle diameter of the glass component in the conductive paste for the glass component and the via conductors in a conductor paste for the conductor pattern is 0.5~5μm The manufacturing method of the ceramic wiring board as described in 2.

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