JP4567328B2 - Manufacturing method of multilayer ceramic substrate - Google Patents

Description

  The present invention relates to a method for manufacturing a multilayer ceramic substrate. More specifically, the present invention relates to a method for manufacturing a multilayer ceramic substrate that is preferably manufactured using a firing method that suppresses sintering shrinkage.

  In recent years, in the electronic component field, high-efficiency manufacturing by taking a large number of pieces has been demanded, and it is desired to increase the size of a multilayer ceramic substrate during manufacturing. However, when a large ceramic substrate is manufactured using a normal firing method, it is difficult to grasp the firing shrinkage over the entire surface, and it is possible to sufficiently obtain the dimensional accuracy of the ceramic substrate and the alignment accuracy in the mounting process. difficult. On the other hand, a non-shrinkage firing method is known as a firing method capable of achieving high dimensional accuracy. That is, for example, Patent Document 1, Patent Document 2, and Patent Document 3 below. This non-shrinkage firing method has the advantage that the dimensional variation during firing can be made extremely small without substantially shrinking in the plane direction.

JP-A-4-243978 (Page 6, etc.) JP 2002-43757 A (Page 4 etc.) JP 2002-226259 A (Page 4 etc.)

  In the above-mentioned Patent Document 1, it is shown that the glass transition to the forced layer (shrinkage suppression layer referred to in the present specification) is suppressed to 50 μm or less, etc., but the glass is selected in consideration of the dielectric properties and the like. It is not easy and does not show what glass can be specifically selected. Furthermore, in the above-mentioned Patent Document 2, it is described that the viscosity of the glass before crystallization is set to a predetermined value, and that the crystallization start temperature is preferably in a predetermined range is described. . However, this is not an invention in view of the bondability and removability with the shrinkage suppression layer, but an invention that optimizes the bondability with the conductor layer. Further, Patent Document 3 similarly relates to a technique for preventing discoloration of ceramics, not considering the bondability and removability with the shrinkage suppression layer.

  The present invention has been made in view of the above, and even without containing Pb having a large environmental load, while maintaining dielectric properties suitable for a multilayer ceramic substrate, it is possible to effectively suppress shrinkage during production, and An object of the present invention is to provide a method for producing a multilayer ceramic substrate in which the removal of the shrinkage suppression layer is facilitated.

The present inventors have studied a method for producing a multilayer ceramic substrate by a non-shrinkage firing method. As a result, as disclosed in the above-mentioned patent publication 1, “to facilitate removal of the forced layer after firing, the glass of the ceramic part being fired substantially penetrates or interacts with the forced layer during processing. It must be fired simply to prevent the glass from moving into the forced layer, such as "Do not be" and "The glass composition should be that which prevents glass penetration into the forced layer". It was discovered that shrinkage may not be sufficiently suppressed. On the other hand, when the glass is excessively transferred to the shrinkage suppression layer, it is difficult to remove the glass as shown in the above-mentioned Patent Publication 1. However, the glass powder used for the multilayer ceramic substrate is an important material that greatly affects the dielectric properties of the multilayer ceramic substrate, and cannot be selected only with the suppression of shrinkage in mind. In addition, as disclosed, it is difficult to select a glass only from the viscosity and contact angle of the glass, and in practice, any glass can be selected to suppress shrinkage, and the removal of the shrinkage suppression layer should be performed without any problem. It was unclear whether it was possible. In particular, it is more difficult to achieve the above without containing a material having a large environmental load such as Pb which has been a problem in recent years.
As a result of repeated studies on the above problems, the present inventors have found that the above problems can be solved very effectively by keeping the melting characteristics of glass within a certain range without containing Pb, and the present invention has been completed. It was.

That is, the present invention is as follows.
( 1 ) A shrinkage suppression layer that is not sintered at the firing temperature of the laminate is disposed on the front and back surfaces of the laminate obtained by laminating an unfired sheet containing a ceramic filler and glass powder. Firing step of firing,
In the method for producing a multilayer ceramic substrate, comprising the removal step of removing the shrinkage suppression layer after performing the firing step,
The glass powder has a glass transition point of 580 to 700 ° C., a temperature difference between the glass transition point and the softening point is 140 ° C. or less, contains an alkali metal, and the content of the alkali metal is The total glass is 2.0% by mass or less in terms of oxide, and it is made of glass not containing Pb.
The shrinkage suppression layer does not contain glass powder, and contains alumina powder,
In the firing step, the laminate is fired without pressure, and the glass diffuses from the laminate to the shrinkage suppression layer ,
The glass further contains Si, Al, B, Ca, and Zn, and the content of B is 12 to 30% by mass with respect to the whole glass in terms of oxide. Manufacturing method.
(2) The said glass is a manufacturing method of the multilayer ceramic substrate as described in said (1) whose temperature difference of a glass transition point and a yield point is 25-45 degreeC.
( 3 ) The method for manufacturing a multilayer ceramic substrate according to any one of (1) and ( 2 ), wherein the multilayer ceramic substrate includes a conductor portion that is co-fired with the multilayer body.

According to the method for producing a multilayer ceramic substrate of the present invention, the multilayer ceramic substrate having dielectric properties suitable for the multilayer ceramic substrate not containing Pb is effectively suppressed from firing shrinkage, and further, the shrinkage inhibiting layer after firing. Can be obtained by a method that makes it easy to remove. Moreover, simultaneous firing with a low-resistance conductor can be performed without any problem.
When the temperature difference between the glass transition point and the yield point of the glass is 25 to 45 ° C., the temperature and time at which the glass moves to the shrinkage suppression layer is optimized, and after firing while fully exhibiting the shrinkage suppression effect Removal of the shrinkage suppression layer is also facilitated.
Glass containing B, since the content of B is 12 to 30 wt%, can be more reliably Tg and Ts-Tg glass fall within the desired range, the melting characteristics of the glass to a suitable range Can keep. Moreover, low temperature firing to the extent that simultaneous firing with the low resistance conductor is possible is ensured, and warpage can be prevented. Furthermore, the chemical stability (chemical resistance) of the glass is sufficiently obtained.
Glass Si, Al, because it contains Ca and Zn, can be more reliably Tg and Ts-Tg glass fall within the desired range, it is possible to keep the melting characteristics of the glass to a suitable range. In addition, dielectric properties, thermal expansion properties, and mechanical properties can be obtained with a good balance.
Since the content of the alkali metal in the glass is not more than a predetermined amount, it is possible to prevent only the glass from being oversintered, and furthermore, the occurrence of migration can be effectively suppressed even when a low resistance conductor is used.
In the case of including a conductor portion that is co-fired with the multilayer body, the dimensional accuracy is high and excellent electrical reliability can be obtained.

The present invention will be described in detail below.
[1] Multilayer Ceramic Substrate The multilayer ceramic substrate manufactured by the manufacturing method of the present invention includes a glass ceramic mixing portion, and the glass phase has a glass transition point (hereinafter also simply referred to as “Tg”) of 580 to 700 ° C. The temperature difference (hereinafter also simply referred to as “Ts−Tg”) between the glass transition point and the softening point (hereinafter also simply referred to as “Ts-Tg”) is 140 ° C. or less, and the Pb content is oxidized. It consists of glass which is 0 mass% with respect to the whole glass in physical conversion.

(1) Glass Phase The above “glass phase” constitutes a glass ceramic mixing part and is a matrix with respect to the ceramic filler. The glass ceramic mixing part and the ceramic filler will be described later.
The glass constituting the glass phase has a Tg of 580 to 700 ° C. As Tg increases, the softening of the glass starts at a higher temperature and can be densified in a shorter time, so that the diffusion of the glass into the shrinkage suppression layer is suppressed. Further, as Tg is smaller, the softening of the glass starts at a lower temperature and promotes the diffusion of the glass into the shrinkage suppression layer. When Tg is in the range of 580 to 700 ° C. in this balance, the shrinkage suppression layer after firing can be easily removed while sufficiently exhibiting the shrinkage suppression effect. In addition, when Tg exceeds 670 ° C., it becomes difficult to control the timing of sintering when co-firing with a low-resistance conductor (Ag and Cu, etc.), and the resulting multilayer ceramic substrate is warped, The conductor part (conductor pattern or the like) may be peeled off from the substrate, which is not preferable. This Tg is preferably 600 to 680 ° C, and more preferably 620 to 660 ° C.

  Moreover, Ts-Tg is 140 degrees C or less. As Ts-Tg increases, the softening of the glass occurs more slowly and the diffusion of the glass into the shrinkage suppression layer is promoted. However, when Ts-Tg exceeds 140 ° C., the diffusion tends to be excessive. This is not preferable because it is difficult to remove the shrinkage suppression layer after firing. On the other hand, as Ts-Tg is smaller, the softening of the glass occurs more rapidly, and the glass can be densified in a shorter time, so that diffusion to the shrinkage suppression layer of the glass is suppressed. As described above, if there is a temperature difference exceeding this, diffusion does not become excessively small, and therefore a sufficient shrinkage suppressing effect can be obtained. That is, if Ts-Tg is 140 ° C. or lower, the shrinkage suppression layer after firing can be easily removed while sufficiently exhibiting the shrinkage suppression effect. This Ts-Tg is preferably 130 ° C. or lower, and more preferably 125 ° C. or lower.

  Further, the temperature of the yield point (hereinafter also simply referred to as “Mg”) is not particularly limited, but the temperature difference between Tg and Mg (hereinafter also simply referred to as “Mg-Tg”) is 25 to 45 ° C. (more preferably 28-42 ° C., more preferably 30-42 ° C.). By this Mg-Tg being in this range, the temperature and time for the glass to be further transferred to the shrinkage suppression layer are further optimized, and it is easy to remove the shrinkage suppression layer after firing while fully exhibiting the shrinkage suppression effect. Become.

The composition of this glass is usually aluminosilicate glass (including aluminoborosilicate glass). Therefore, this glass contains Si and Al.
Although Si is not content particularly limited, and oxides in the case where the entire glass is 100 mass% 15-60% by weight (SiO ₂₎ in terms of (more preferably 20 to 55 wt%, more preferably 25 to 50 mass %). In this range, the Tg and Ts-Tg of the glass can be kept within the above range particularly reliably, and the melting characteristics of the glass can be maintained in an appropriate range. Moreover, low temperature firing to the extent that simultaneous firing with the low resistance conductor is possible is ensured, and warpage can be prevented. Furthermore, range suitable for epsilon _r multilayer ceramic substrate (i.e., for example, epsilon _r is 6-10) may be accommodated in.
Note that the low-resistance conductor is a conductor having high conductivity but low melting point (for example, 1085 ° C. or lower) since silver, copper, gold, palladium, and the like are the main components. Furthermore, the temperature at which simultaneous firing is possible is usually 1050 ° C. or lower.

On the other hand, is not particularly limited content of Al, an oxide in the case where the entire glass is 100 mass% _(Al 2 _{O 3)} 6~30% by weight in terms of (more preferably 8 to 28 wt%, more preferably 10 to 26% by mass) is preferable. Within this range, the mechanical strength of the multilayer ceramic substrate can be sufficiently obtained, and the simultaneous firing with the low-resistance conductor can be reliably performed without the firing temperature becoming too high.
These Si and Al contents can be combined with each other. That is, for example, Si is preferably 15 to 60% by mass and Al is preferably 6 to 30% by mass, Si is preferably 20 to 55% by mass and Al is preferably 8 to 28% by mass, and Si is 25% by mass. It is particularly preferable that -50% by mass and Al is 10-26% by mass.

Further, this glass has a Pb oxide (PbO) conversion content of 0 to 1% by mass when the entire glass is 100% by mass. Since the melting point of the glass in the field of the present invention can be lowered by the inclusion of Pb, the sinterability and workability have been ensured by containing Pb conventionally. However, in recent years, due to the large environmental load, efforts have been made to obtain conventional characteristics without containing Pb. The present invention can obtain an excellent shrinkage suppression effect while maintaining dielectric properties without containing Pb, that is, the effect of the present invention can be obtained without positively containing Pb. Can do. The glass does not contain Pb (below the detection limit by fluorescent X-ray measurement).

B is contained as an element constituting the glass. B can change the melting characteristics of the glass depending on its content. The content of this B is 12 to 30 wt% of an oxide _(B 2 _{O 3)} in terms of when the entire glass is 100 mass%, more preferably 14 to 25 wt%, more preferably 16 to 22 It is preferable to set it as the mass%. If it is this range, Tg and Ts-Tg of glass can be more reliably accommodated in said range, and the melting characteristic of glass can be maintained in a suitable range. Moreover, low temperature firing to the extent that simultaneous firing with the low resistance conductor is possible is ensured, and warpage can be prevented. Furthermore, the chemical stability (chemical resistance) of the glass is sufficiently obtained, and, for example, erosion can be prevented when a plating process or the like is required at the time of manufacturing the wiring board.
The contents of B and the Si and Al can be combined with each other. That is, for example, it is preferable that Si is 15 to 60% by mass, Al is 6 to 30% by mass and B is 12 to 30% by mass, Si is 20 to 55% by mass, Al is 8 to 28% by mass and B is Is more preferably 14 to 25% by mass, particularly preferably Si is 25 to 50% by mass, Al is 10 to 26% by mass, and B is 16 to 22% by mass.

Further, the glass contains Ca and Zn in addition to B, Si and Al .
Although content of Ca is not specifically limited, When the whole glass is 100 mass%, it is 8-22 mass% (more preferably 10-20 mass%, still more preferably 12-17 mass%) in conversion of an oxide (CaO). ) Is preferable. In this range, Tg and Ts-Tg of glass can be more reliably contained in said range, and the melting characteristic of glass can be maintained in an appropriate range. Moreover, low temperature firing to the extent that simultaneous firing with the low resistance conductor is possible is ensured, and warpage can be prevented. Furthermore, the thermal expansion coefficient does not become too large (that is, the coefficient of thermal expansion when the temperature is increased from 25 ° C. to 400 ° C., for example, is 12 ppm / ° C. or less), and a multilayer ceramic substrate having high reliability is obtained. be able to.

  Although content of Zn is not specifically limited, When the whole glass is 100 mass%, it is 2-18 mass% (more preferably 3-16 mass%, still more preferably 4-14 mass%) in conversion of an oxide (ZnO). ) Is preferable. If it is this range, sufficient sinterability with a low-resistance conductor can be fully obtained, and it can sinter without producing a curvature. In addition, the chemical resistance of the multilayer ceramic substrate can be sufficiently obtained.

  The contents of these Ca and Zn and the above Si, Al, and B can be combined. That is, for example, Si is preferably 15 to 60% by mass, Al is 6 to 30% by mass, B is 12 to 30% by mass, Ca is 8 to 12% by mass, and Zn is preferably 2 to 18% by mass, Is more preferably 20 to 55 mass%, Al is 8 to 28 mass%, B is 14 to 25 mass%, Ca is 10 to 20 mass%, Zn is 3 to 16 mass%, and Si is 25 to 50 mass%. It is particularly preferable that 10% by mass, Al is 10 to 26% by mass, B is 16 to 22% by mass, Ca is 12 to 17% by mass, and Zn is 4 to 14% by mass.

Further, the content of alkali metals (particularly Li, Na and K) in this glass is such that the content in terms of oxides (Li ₂ O, Na ₂ O and K ₂ O, etc.) in terms of 100% by mass of the entire glass. 2.0% by mass or less (more preferably 1.8% by mass or less, and still more preferably 1.5% by mass or less). Within this range, the glass transition point becomes excessively low, and it is possible to reliably prevent oversintering of only the glass, and furthermore, the occurrence of migration can be effectively suppressed even when a low resistance conductor is used. .

(2) Ceramic filler The “ceramic filler” is dispersed and contained in the glass phase of the glass ceramic mixing part. The ceramic filler can adjust the dielectric characteristics, thermal expansion characteristics and mechanical characteristics of the multilayer ceramic substrate according to the type and content thereof. Examples of ceramic fillers include garnite, titania, alumina, titanates (magnesium titanate, calcium titanate, strontium titanate, barium titanate, etc.), aluminum nitride, mullite, zirconia, quartz, cordierite, forsterite. , Wollastonite, anorthite, enstatite, diopsite, akermanite, gelenite, spinel and the like. Among these, for example, in order to increase ε _r in a high frequency band (particularly in the GHz band) in dielectric characteristics, it is preferable to use garnite, titania, titanate, and alumina powders. In order to improve mechanical strength, each powder of garnite, titania, zirconia, and alumina is preferable. These may use only 1 type and may use 2 or more types together. By using two or more kinds, it is possible to improve all of dielectric characteristics, thermal expansion characteristics, mechanical strength, and the like.

The shape of the ceramic filler is not particularly limited, and can be various shapes such as a particulate shape, a scale shape, a fiber shape, and a whisker shape, but is usually a particulate shape. Furthermore, although the size is not particularly limited, it is usually preferably 1 to 10 μm (average particle diameter in the case of particle shape, average maximum length in other cases). Within this range, the structure of the multilayer ceramic substrate does not become excessively rough, and there is no difficulty in handling during production.
The ceramic filler is usually present in the multilayer ceramic substrate with the shape and size added as the ceramic filler during the production of the multilayer ceramic substrate. However, it also includes those added as glass powder or the like at the time of production and precipitated as crystalline components (anocite, spinel, garnite, etc.) by firing.

(3) Glass ceramic mixing part The multilayer ceramic substrate manufactured by the manufacturing method of this invention has a glass ceramic mixing part (11 in FIG. 1). The multilayer ceramic substrate (1 in FIG. 1) normally includes a conductor portion (12 in FIG. 1) in addition to the glass ceramic mixing portion, and the glass ceramic mixing portion can function as an insulating portion for the conductor portion.
The “glass ceramic mixing part” has a glass phase (111 in FIG. 1) and a ceramic filler (112 in FIG. 1). The ratio of the glass phase and the ceramic filler is not particularly limited. Usually, when the total of the glass phase and the ceramic filler is 100% by mass, the glass phase is 27 to 73% by mass (more preferably 25 to 70% by mass, More preferably, it is 40 to 60% by mass). If it is this range, it can fully densify and sufficient bending strength (for example, the 3 point | piece bending strength according to JISR1601 is 200 Mpa or more) can be obtained. Further, simultaneous sintering can be performed without causing problems such as warping with the low-resistance conductor, and further, reaction between the firing jig and glass due to glass melting during firing can be reliably prevented.

  The glass ceramic mixing portion may have a uniform composition (all the glass ceramic mixing portions have the same composition) or a non-uniform composition (a portion having a different composition in the glass ceramic mixing portion) in the multilayer ceramic substrate. ). In the case of non-uniform composition, for example, by using a plurality of unfired sheets having different blending ratios of glass powder and ceramic filler at the time of manufacture, glass ceramic mixing parts having different glass phase and ceramic filler content ratios And the like. Moreover, the case where it has the glass ceramic mixing part from which the kind etc. of a ceramic filler differs by using the some unbaking sheet | seat from which the kind etc. of the ceramic filler used at the time of manufacture differs is mentioned.

Glass-ceramic mixed portion constituting a multilayer ceramic substrate manufactured by the manufacturing method of the present invention, 1～15GHz (especially 3-10 GHz) 4.5 to 13 The epsilon _r in (further 5 to 10, especially 6 to 10 ). Further, Q · f at 1 to 15 GHz (particularly 3 to 10 GHz) can be set to 650 to 1200 GHz (more preferably 850 to 1200 GHz, particularly 850 to 1100 GHz). Furthermore, τ _f when the temperature is raised from 25 ° C. to 80 ° C. can be set to −120 to −50 ppm / ° C. (further −90 to −50 ppm / ° C., particularly −80 to −60 ppm / ° C.). The dielectric loss at 1 to 15 GHz (especially 3 to 10 GHz) is 70 × 10 ⁻⁴ or less (more preferably 60 × 10 ⁻⁴ or less, particularly 50 × 10 ⁻⁴ or less, usually 20 × 10 ⁻⁴ or more). Can do. Furthermore, the thermal expansion coefficient when the temperature is raised from 25 ° C. to 400 ° C. can be 5 to 12 ppm / ° C.

(4) Structure of Other Parts and Multilayer Ceramic Substrate The multilayer ceramic substrate manufactured by the manufacturing method of the present invention can include a co-fired conductor portion in addition to the glass ceramic mixing portion. The “conductor portion” is a portion having conductivity (usually 3 μΩ · cm or less at normal temperature). Although the material which comprises this conductor part is not specifically limited, Silver, copper, gold | metal | money, palladium, etc. are mentioned. These may use only 1 type and may use 2 or more types together. Further, the shape and thickness thereof are not particularly limited. As this conductor part, the conductor etc. which connect a conductor pattern and the conductor patterns of a different interlayer are mentioned, for example. Examples of the conductor pattern include normal conduction wiring, resistance wiring, inductance wiring, and bonding pads. Examples of conductors that connect conductor patterns between different layers include through-hole conductors and via conductors.

Moreover, the multilayer ceramic substrate manufactured by the manufacturing method of this invention can be equipped with another part other than a glass ceramic mixing part and a conductor part. Examples of other parts include electronic components. The kind of electronic component is not particularly limited, and various electronic components can be provided. Examples of the electronic component include various active components and passive components. The location of these electronic components is not particularly limited. For example, the electronic components may be placed in a through hole provided in the multilayer ceramic substrate, or in a cavity formed in the multilayer ceramic substrate. It may be arranged on the surface of the multilayer ceramic substrate.
Furthermore, the shape of the multilayer ceramic substrate produced by the production method of the present invention is not particularly limited, and may be, for example, a flat plate shape or a non-flat plate shape. The non-flat shape is, for example, a case having a cavity (concave portion).

The multilayer ceramic substrate produced by the production method of the present invention is sintered at the firing temperature of the laminate on the front and back surfaces of the laminate obtained by laminating unfired sheets containing ceramic filler and glass powder. Each of the shrinkage-suppressing layers not provided is provided, and the laminate including the shrinkage-suppressing layer is fired, and then manufactured by a method of removing the shrinkage-suppressing layer. Furthermore, when manufacturing by this method, baking is performed under no pressure. These methods will be described in detail in the production method of the present invention below.

[2] Manufacturing Method of Multilayer Ceramic Substrate The manufacturing method of the present invention involves sintering at the firing temperature of the laminate on the front and back surfaces of the laminate obtained by laminating an unfired sheet containing a ceramic filler and glass powder. A firing step of disposing a non-shrinkage suppression layer and firing the laminate;
In the method for manufacturing a multilayer ceramic substrate, comprising a removal step of removing the shrinkage suppression layer after performing the firing step,
The glass powder has a glass transition point of 580 to 700 ° C., a temperature difference between the glass transition point and the softening point is 140 ° C. or less, contains an alkali metal, and the content of the alkali metal is an oxide. The total glass is 2.0% by mass or less in terms of conversion, and the glass does not contain Pb.
The shrinkage suppression layer does not contain glass powder and contains alumina powder,
In the firing step, the laminate is fired without pressure, and the glass diffuses from the laminate to the shrinkage suppression layer .
The glass further contains Si, Al, B, Ca and Zn, and the content of B is 12 to 30% by mass with respect to the whole glass in terms of oxide .

  The “unfired sheet” contains at least a ceramic filler and glass powder, and constitutes a laminate. Moreover, it will baked and will comprise the above-mentioned glass ceramic mixing part. The ratio of the ceramic filler and glass in the said glass ceramic mixing part can be applied as it is for the ratio of the ceramic filler and glass powder contained in the unfired sheet. In general, the ceramic filler formed by precipitation of glass is not contained in the glass ceramic mixing part or is contained in a very small amount even if contained.

The above-mentioned “ceramic filler” can be directly applied to the ceramic filler in the multilayer ceramic substrate, except that it does not contain a ceramic filler deposited from glass by firing.
The “glass powder” is a powder that is fired to become a glass phase of a multilayer ceramic substrate. The glass constituting the glass powder is usually the same as the glass constituting the glass phase, and the glass constituting the glass phase can be applied as it is. Moreover, the shape of the glass particle which comprises this glass powder is not specifically limited, It can be set as the same shape as the said ceramic filler. Moreover, although the magnitude | size of a glass particle is not specifically limited, Usually, it is preferable to set it as 1-7 micrometers (average particle diameter in the case of a particle shape, average maximum length in other cases). If it is this range, the spreading | diffusion to the shrinkage | contraction suppression layer of glass will be favorable, baking property will be good, and the difficulty on handling will not be accompanied at the time of manufacture.
This green sheet can contain things other than a ceramic filler and glass powder. Others include binders and solvents.

  The “laminate” is a laminate in which at least two unfired sheets are laminated. This laminated body may be provided with other parts besides the unfired sheet. Examples of the other parts include an unfired conductor pattern (can be disposed between unfired sheets) and an unfired conductor paste (can be disposed in a through-hole formed in the unfired sheet) to be a conductor portion. Furthermore, an electronic component or the like can be provided in a through hole or a cavity formed in the laminate.

The “shrinkage suppression layer” is a layer that is not sintered at the firing temperature of the laminate. The laminated body which becomes a multilayer ceramic substrate is provided with this shrinkage suppression layer on the front and back surfaces thereof, whereby shrinkage due to firing (particularly firing shrinkage in the xy direction) is suppressed. In addition, the fact that the laminate is not sintered at the firing temperature usually means that the shrinkage suppression layer contains ceramic powder, but the ceramic powders constituting the shrinkage inhibition layer do not cause adhesion due to firing. In particular, it is preferable that adhesion due to firing with the ceramic filler contained in the laminate does not occur. Furthermore, this shrinkage | contraction suppression layer may be provided for every 1 layer on the front and back of a laminated body, and may each be equipped with 2 or more layers. When two or more layers are provided, the shrinkage suppression layers provided on one surface side of the laminate may have the same composition or different compositions. The shrinkage suppression layer contains alumina powder as a ceramic powder.
Moreover, this shrinkage | contraction suppression layer does not contain glass powder. Firing shrinkage is suppressed, and removal of the shrinkage inhibiting layer after firing is facilitated.

The “baking step” is a step of firing the laminate including the shrinkage suppression layers on the front and back surfaces that are not sintered at the firing temperature of the laminate. Firing is heating at a firing temperature at which the laminate is sintered. The firing temperature in this firing is usually a low temperature of 1050 ° C. or lower (preferably 950 ° C. or lower, more preferably 900 ° C. or lower, usually 800 ° C. or higher). The firing time is usually 10 hours or shorter (preferably 5 hours or shorter, more preferably 2 hours or shorter, usually 0.5 hours or longer). These firing temperatures and firing times are preferably selected as appropriate depending on the ceramic filler used, glass powder, and other materials provided during firing. Furthermore, the firing temperature is preferably 300 ° C. or more (more preferably 200 ° C. or more) lower than the sintering temperature of the shrinkage suppression layer.
Moreover, this baking is performed without pressure. The non-pressurization means that no pressure is applied to the firing atmosphere, and no layer other than its own weight other than the shrinkage suppression layer is further laminated on the laminate. That is, the laminate that becomes the multilayer ceramic substrate is fired without receiving pressure other than the weight of the shrinkage suppression layer.

  The “removal step” is a step of removing the shrinkage suppression layer after performing the firing step. This removal may be performed by any method. For example, a method using thermal shock and a method of scraping with a tool may be used. Among these methods, as a method using thermal shock, for example, a fired body (multilayer ceramic substrate with a shrinkage suppression layer) that has undergone a firing process is held at a temperature in the range of 25 to 100 ° C., and then 10 ° C. above the held temperature. A method of removing the residual stress at the time of sintering by exposing to a low cooling medium (such as water) and instantaneously using the thermal shock due to this temperature difference is mentioned. On the other hand, as a method of scraping with a tool, for example, a method of spraying and removing liquid (water, etc.) and / or powder (alumina powder, etc.) with a spray gun, etc., and a hard spatula and brush, etc. A method of scraping with use is mentioned.

Hereinafter, the present invention will be described specifically by Experiment (Experiment 1-9,11-12,1 5 -17 are examples. Experimental Example 10,13, 14, is a reference example).
[1] Production of Multilayer Ceramic Substrate (1) Preparation of Glass Powder Mixed powder is obtained by mixing at a ratio shown in Table 1 of SiO ₂ powder, B ₂ O ₃ powder, Al ₂ O ₃ powder, CaO powder and ZnO powder. It was. The obtained mixed powder was heated and melted, and then poured into water and crushed by rapid cooling to obtain a glass frit. The obtained glass frit was further pulverized by a ball mill to obtain glass powder having an average particle diameter of 3 μm. The melting characteristics (Tg, Ts, and Mg) of each glass powder were measured, and the results are shown in Table 2. The measurement was performed using a differential thermal analyzer (manufactured by Rigaku Corporation, type “THERMFLEX”).

(2) Production of Unsintered Sheet On the other hand, alumina powder (average particle size 3 μm, specific surface area 1.0 m ² / g) was prepared as a ceramic filler. The glass powder and the alumina powder obtained above were weighed so that the volume ratio was 1: 1, and then mixed. Furthermore, a binder (acrylic binder) and a plasticizer (di-2-ethylhexyl phthalate) and a solvent (methyl ethyl ketone) necessary for molding were added and further mixed to obtain a slurry. The obtained slurry was formed into a sheet having a length and width of 200 mm and a thickness of 0.15 mm by a doctor blade method to obtain an unfired sheet.

(3) Production of Shrinkage Suppression Layer The alumina powder used in (2) above was prepared, and a slurry was obtained in the same manner as (2) above. The obtained slurry was formed into a sheet shape of 200 mm in length and width and 0.30 mm in thickness by a doctor blade method to obtain a shrinkage suppression layer.

(4) Formation of Laminate and Lamination of Shrinkage Suppression Layer Four laminates of unfired sheets obtained in (2) above were laminated to obtain a laminate. Furthermore, the shrinkage | contraction suppression layer obtained by said (3) was laminated | stacked on the front and back of this laminated body, and the laminated body provided with a shrinkage | contraction suppression layer on the front and back was obtained.

(5) Firing step The laminate including the shrinkage suppression layer obtained up to the above (4) was placed in a firing furnace and fired at a firing temperature shown in Table 1 without pressure.

(6) removing step after a above (5), after holding a temperature 25 ° C. over 30 minutes, removed to experimental examples 1 to the shrinkage inhibiting layer by applying heat shock by immersion in cold water 10 ° C. 17 and Comparative Examples 1 to 7 were obtained.

[2] Evaluation of multilayer ceramic substrate (1) Measurement of shrinkage rate and variation in shrinkage rate The shrinkage rate of the multilayer ceramic substrate obtained by the above [1] was measured and shown in Table 3. Further, this variation in shrinkage (3σ) was calculated and shown in Table 3.
(2) Measurement of peelability Table 3 shows the ease of removal in the removal steps [1] and (6) described above, evaluated in the following three stages.
“◎”: When the area where the shrinkage suppression layer was removed is 99% or more of the front and back surfaces of the laminate.
“◯”: When the area where the shrinkage suppression layer can be removed is 90% or more and less than 99% of the front and back surfaces of the laminate.
“Δ”: The area where the shrinkage suppression layer can be removed is 50% or more and less than 90% of the front and back surfaces of the laminate.
"X" ... The area which could remove the shrinkage | contraction suppression layer is less than 50% of a laminated body front and back.

(3) Measurement of dielectric characteristics A part of the multilayer ceramic substrate obtained in [1] above is cut out and polished into a plate-like body having a length of 50 mm, a width of 50 mm, and a thickness of 0.635 mm. Obtained porcelain. The dielectric properties using a measuring porcelain, in accordance with JIS R 1627, the resonance frequency in TE011 mode was measured epsilon _r and the Q value as 3～12GHz. The results are shown in Table 3. The Q value was expressed as a product (Q · f) with the resonance frequency (f).

(4) Measurement of thermal expansion characteristics A part of the multilayer ceramic substrate obtained in [1] above is cut out and polished into a columnar body having a length of 3 mm, a width of 3 mm, and a height of 1.6 mm, and each thermal expansion characteristic is measured. A porcelain was obtained. Using this ceramic for measuring thermal expansion characteristics, the coefficient of thermal expansion when the temperature was raised from 25 ° C. to 400 ° C. was measured using a differential expansion thermomechanical analyzer (manufactured by Rigaku Corporation, model “TMA8140C”). . The results are also shown in Table 3.

[3] used as the glass powder and experimental examples of the glass powder obtained in blending the above with the ceramic filler [1] (1) 4, 5 types shown in Table 4 the volume ratio of the glass powder and the alumina powder Except for the above, the laminate was fired in the same manner as in [1] above (the firing temperature is the temperature shown in Table 4). The relative density based on the theoretical density calculated from the specific gravity, specific surface area, and mixing ratio of each particle of glass and ceramic filler of each obtained multilayer ceramic substrate was measured and shown in Table 4.

[4] than the effect Table 1-3 Experiment examples, Comparative Examples 1-7, it can be seen that it is difficult to remove the shrinkage suppression layer at an area ratio of 50% or more in both a simple method. It can also be seen that the variation in firing shrinkage is relatively large.
In contrast, even content of 0 to 1 mass% of Pb, as shown in experimental examples 1 to 17 (especially if containing no Pb), a Tg of from 580 to 700 ° C. and Ts-Tg Is 140 ° C. or lower (105 to 140 ° C.), while maintaining practical dielectric properties, the firing shrinkage rate is suppressed to 0.28 or lower and the variation is suppressed to 0.19 or lower, making the shrinkage suppression layer extremely simple. It can be seen that it can be removed with an area ratio of 50% or more by this method. Furthermore, as shown in experimental examples 1 to 14, so long as the Mg-Tg in addition to the conditions of the Tg and Ts-Tg is 25 to 45 ° C., while maintaining practical dielectric properties, firing shrinkage It can be seen that the rate is suppressed to 0.28 or less and the variation is controlled to 0.13 or less, and the shrinkage suppression layer can be removed at an area ratio of 90% or more by a very simple method. In particular, as shown in Experimental Examples 4 and 7, Tg is 630 through 640 ° C., Ts-Tg is 110 to 120 ° C., if Mg-Tg is 40 ° C., the .epsilon.r 7.1-7. is 6, Q · f 880~1000GHz, the tau _f while exhibiting excellent dielectric properties and -75 to-70 ppm / ° C., the firing shrinkage is suppressed to 0.28 or less and the variation 0.06, It can be seen that the shrinkage suppression layer can be removed at an area ratio of 99% or more by a very simple method.

  Moreover, it can be seen from Table 4 that by changing the mass ratio of the glass powder and the ceramic filler, a difference occurs in the density of the obtained multilayer ceramic substrate even if the firing temperature is the same. From this result, it is understood that the relative density exceeds 99% at least when the volume ratio of the glass powder is 30 to 70% by mass. In particular, when the mass ratio of the glass powder is 50% by mass, it can be seen that the relative density is sufficiently densified as 99.8%.

  The present invention is widely used in the field of electronic components. For example, the present invention relates to packages such as a package (C4 package or the like) having electrode pads for flip-chip connection of semiconductor elements, a package such as CSP (Chip Size Package), MCP (Multi Chip Package), and the like. It is used for a module such as MCM-C (Multi Chip Module-Ceramic) including a resistor, a capacitor and / or an inductor.

It is sectional drawing which shows typically the multilayer ceramic substrate manufactured by the manufacturing method of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1; Multilayer ceramic substrate, 11; Glass ceramic mixing part, 111; Glass phase, 112; Ceramic filler, 12; Conductor part.

Claims (3)

A shrinkage suppression layer that is not sintered at the firing temperature of the laminate is disposed on the front and back surfaces of the laminate obtained by laminating an unfired sheet containing a ceramic filler and glass powder, and the laminate is fired. A firing step;
In the method for producing a multilayer ceramic substrate, comprising the removal step of removing the shrinkage suppression layer after performing the firing step,
The glass powder has a glass transition point of 580 to 700 ° C., a temperature difference between the glass transition point and the softening point is 140 ° C. or less, contains an alkali metal, and the content of the alkali metal is The total glass is 2.0% by mass or less in terms of oxide, and it is made of glass not containing Pb.
The shrinkage suppression layer does not contain glass powder, and contains alumina powder,
In the firing step, the laminate is fired without pressure, and the glass diffuses from the laminate to the shrinkage suppression layer ,
The glass further contains Si, Al, B, Ca, and Zn, and the content of B is 12 to 30% by mass with respect to the whole glass in terms of oxide. Manufacturing method.   The method for producing a multilayer ceramic substrate according to claim 1, wherein the glass has a temperature difference between a glass transition point and a yield point of 25 to 45 ° C. The said multilayer ceramic substrate is a manufacturing method of the multilayer ceramic substrate of Claim 1 or 2 provided with the conductor part co-fired with the said laminated body.

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