JP4702021B2 - Ceramic substrate with conductor layer and method for producing the same - Google Patents

Description

  The present invention relates to a ceramic substrate with a conductor layer such as a low-temperature co-fired ceramic substrate on which a surface conductor for soldering or the like is formed, and a method for manufacturing the same.

Low temperature co-fired ceramics (LTCC) technology is widely used as a high frequency passive component built-in technology. Recently, application to antennas and various filters for wireless LAN, bluetooth, or ultra wide band (UWB) is expected.
FIG. 1 is a conceptual diagram of a cross section of a typical antenna for UWB, which is a kind of ceramic substrate with a conductor layer. An antenna (ceramic substrate with a conductor layer) 10 is an electric circuit in which a laminated body of ceramic layers 11 as a main body, an inner layer conductor 2 wired therein, and a vertical pattern necessary for multilayering are electrically formed. It has a via conductor 3 for bonding and a surface layer conductor 1 used for soldering with a power supply to the antenna and a substrate to be bonded.

The ceramic layer 11 is formed by firing a glass ceramic composition made of a ceramic green sheet (hereinafter sometimes simply referred to as a green sheet). As such a glass ceramic composition, for example, a composition comprising SiO ₂ —B ₂ O ₃ —Al ₂ O ₃ —RO (alkaline earth metal oxide) —ZnO glass powder and alumina powder is known ( Patent Document 1).

  The green sheets are laminated to form a green sheet laminate, and the conductor paste layer that is fired to become the surface layer conductor 1 is on the green sheet laminate surface, and the conductor paste layer that is fired to become the inner conductor 2 is between the green sheet layers. Conductive paste filling holes that are baked to become via conductors 3 are formed in the green sheets.

Such a ceramic substrate with a conductor layer is usually soldered and mounted on a general printed circuit board using a solder reflow furnace at the surface layer conductor portion. In this case, the surface layer conductor has sufficient solderability and Adhesive strength is required.
As a conductor paste suitable for forming such a surface layer conductor excellent in solderability and adhesive strength, a paste composed of a metal powder, a trace amount of manganese oxide powder, a trace amount of glass frit and an organic vehicle is known (Patent Document). 2).

JP 2005-126250 A Japanese Patent Laid-Open No. 5-48225

The surface conductor of the high-frequency passive component is required to have a specific resistance of 3.0 μΩ · cm or less. When the specific resistance is more than 3.0 μΩ · cm, the radiation efficiency is lowered in the case of an antenna, and in the case of a filter, the conductor loss of the transmission line in which the antenna is incorporated is increased and the transmission loss is reduced. This is because the problem of worsening occurs.
However, it has been difficult to make the surface conductor excellent in solderability and adhesive strength and low in specific resistance.

  For example, in the conductor paste described in Patent Document 2, glass powder (glass frit) is added to increase the adhesive strength, but a paste from which the glass powder is removed to increase the specific resistance of the conductor is prepared. The specific resistance of the conductor obtained by firing this was also more than 3.0 μΩ · cm.

That is, Example 1 described in Table 1 of Patent Document 2 (in parts by weight, silver powder: 95, palladium powder: 5, MnO ₂ powder: 1, glass frit: 1), Example 4 (in parts by weight) , Silver powder: 80, palladium powder: 20, MnO ₂ powder: 0.2, SnO ₂ powder: 1, glass frit: 1) Conductive paste 1 ′, 4 ′ corresponding to glass frit of 0) Silver powder (spherical powder with an average particle diameter of 1 μm), palladium powder (spherical powder with an average particle diameter of 0.5 μm), MnO ₂ powder (spherical powder with an average particle diameter of 1 μm) or SnO ₂ powder (with an average particle diameter of 1 μm) Spherical powder) and organic varnish (ethyl cellulose resin having a polymerization degree of 7 dissolved in α-terpineol so as to have a concentration of 20% by mass), kneaded in a porcelain mortar for 1 hour, and three It was produced by performing dispersion three times by a roll.

A strip-shaped pattern having a length of 50 cm and a thickness of 10 μm is formed on an alumina substrate by screen printing using the conductive pastes 1 ′ and 4 ′, and it is 5 hours from room temperature to 550 ° C. and 0.5 hours from 550 ° C. to 875 ° C. Baked at 875 ° C. for 1.5 hours and then naturally cooled to room temperature.
The specific resistances of the fired bodies (conductors) of the conductor pastes 1 ′ and 4 ′ thus obtained were measured and found to be 3.8 μΩ · cm and 4.9 μΩ · cm, respectively.
From this, it can be seen that the specific resistance of the conductor obtained by firing the glass frit-containing conductor paste described in Patent Document 2 is more than 3.0 μΩ · cm.

  An object of this invention is to provide the ceramic substrate with a conductor layer in which the conductor layer which is excellent in solderability and adhesive strength, and has a small specific resistance is formed in the surface.

  The present invention was obtained by firing the surface of a ceramic green sheet laminate that was fired to form a ceramic laminate, containing glass powder and metal powder, and applied with a conductor paste that was fired to become a conductor layer. Provided is a ceramic wiring board having a conductor layer in which a conductor layer on a ceramic laminate is separated into a metal layer on the surface side and a glass layer on the interface side of the ceramic laminate. To do.

  Also, a method for producing a ceramic substrate with a conductor layer by applying a conductive paste containing glass powder and metal powder in a mass ratio of 3:97 to 25:75 on the surface of the ceramic green sheet laminate and firing it. In this case, the glass powder precipitates crystals when the firing is performed, and the softening point thereof provides a method for producing a ceramic substrate with a conductor layer that is 300 to 400 ° C. lower than the temperature for firing.

  Further, a method for producing a ceramic substrate with a conductor layer by applying a conductor paste containing glass powder and metal powder in a mass ratio of 3:97 to 25:75 on the surface of a ceramic green sheet laminate, and firing the paste. Provided is a method for producing a ceramic substrate with a conductor layer, in which crystals are precipitated when the glass powder is baked, and the softening point thereof is 500 to 600 ° C.

In order to obtain a surface layer conductor having excellent solderability and adhesive strength and low specific resistance, the present inventor tried changing the particle size of the silver powder, and using the same glass powder as the glass powder contained in the ceramic green sheet Various attempts were made such as adding copper oxide or vanadium oxide powder, which is known as an additive for improving strength, but the desired results could not be obtained.
However, the glass powder contained in the conductor paste has a low softening point and precipitates crystals before the ceramic green sheet laminate starts to sinter during firing, so that it has excellent solderability and adhesive strength and has a specific resistance. It has been found that a small surface conductor can be obtained.

  When the SEM-EPMA photograph of the cross section of the surface conductor portion was taken on the ceramic substrate with the conductor layer thus obtained, the surface conductor portion was separated into a metal layer on the surface of the surface conductor and a glass layer on the substrate side. And found the present invention.

  FIG. 2 is a conceptual sketch of an SEM-EPMA photograph of the cross-section of the surface conductor portion in the ceramic substrate with a conductor layer of Example 1 described later, focusing on the layer structure. It was not linear but uneven.

  The SEM-EPMA photograph was taken as follows. That is, the ceramic substrate with a conductor layer was cut and embedded in an acrylic resin, and then the fracture surface was mirror-polished to prepare a sample. Carbon vapor deposition was performed on the sample, and the surface was analyzed in a semi-quantitative mode using an electron beam microanalyzer (JXA-8900M) manufactured by JEOL Ltd. with an output of 15 KV-30 nA and an analysis probe diameter of 10 μm.

  FIG. 2A is a mapping of silver which is a metal component of the surface layer conductor. The presence of silver was confirmed only in the region having a thickness of about 10 μm on the surface side, and the concentration of silver was less than 0.1% by mass in about 99% of the other regions.

  FIG. 2B is a mapping of bismuth which is a component of glass existing in the surface layer conductor. The bismuth layer was present so as to be in contact with the silver layer having a thickness of about 10 μm on the surface side (FIG. 2A), and the presence of bismuth was not observed in the region corresponding to the silver layer. That is, the silver layer and the glass layer containing bismuth were in contact with each other in a separated state. The thickness of the bismuth layer, that is, the thickness of the glass layer was approximately 8 μm, and the concentration of bismuth was less than 0.1% by mass in about 98% of the region other than the bismuth layer.

In FIG. 2B, the region below the bismuth layer is the substrate body itself, that is, the one obtained by firing the ceramic green sheet laminate (ceramic laminate) itself.
The bismuth layer is a portion where glass derived from the conductive paste is soaked in the portion that has become the substrate body if there is no conductive paste that becomes a surface conductor after being baked. is there.

  In the present invention, the surface conductor or conductor layer present on the surface of the ceramic substrate with a conductor layer includes an altered portion of the substrate main body (recognized in the SEM-EPMA photograph), and the metal layer in the conductor layer (in the example of FIG. 2) If the silver layer is separated from the glass layer, it means that mixing of the glass into the metal layer is not observed in the SEM-EPMA photograph.

In the present invention, since no glass is present on the surface of the conductor layer as shown in FIG. 2A, the solderability, that is, the solder wettability is excellent.
Further, as shown in FIG. 2 (b), there is an altered portion containing glass derived from the conductive paste between the metal layer and the substrate body, and this altered portion provides an adhesive strength between the conductor layer or the metal layer and the substrate body. Get higher.
Further, as shown in FIGS. 2A and 2B, since the glass does not exist in the metal layer, the specific resistance of the conductor layer is reduced.

It becomes possible to increase the radiation efficiency of an antenna for UWB or to reduce the transmission loss of a transmission line incorporating a high frequency filter.
In addition, there are effects such as high mounting strength on general printed circuit boards, bonding and soldering without plating, and soldering using lead-free solder that is inferior in wettability compared to lead-containing solder. is there.

A ceramic substrate with a conductor layer (hereinafter simply referred to as a substrate with a conductor layer) of the present invention will be described with reference to FIG. Note that the present invention is not limited to FIG.
The main part of the substrate with a conductor layer of the present invention is a ceramic laminate in which a plurality of ceramic layers 11 are laminated, and an inner layer conductor 2 and a via conductor 3 that usually become part of the wiring exist inside the ceramic laminate. To do.
A conductor layer (surface conductor) 1 is formed on the surface of the ceramic laminate, and the conductor layer 1 is usually formed so as to be connected to the inner layer conductor 2 or the via conductor 3.

The conductor layer formed on the surface of the ceramic laminate will be described with reference to FIG. 3 which is a conceptual diagram of the cross section, taking as an example the case where it is formed on the ceramic layer 11.
A layer presenting a boundary with the ceramic layer 11 when viewed with a cross-sectional SEM-EPMA photograph is a conductor layer.
When viewed in the same manner, the conductor layer itself has a boundary inside thereof, and the layer present on the surface side of the conductor layer from the boundary is the metal layer 1a. The layer present on the interface side with the layer 11 is the glass layer 1b.

Metal is present in the metal layer 1a, and glass is present in the glass layer 1b.
It is preferable that glass is not substantially present in the metal layer 1a. That is, it is preferable that the area ratio of the portion where the glass exists in the cross section of the metal layer is 3% or less.
It is preferable that the glass layer 1b is substantially free of metal that is a constituent component of the metal layer 1a, that is, a metal powder contained in a conductor paste that is fired to become a conductor layer. That is, it is preferable that the area ratio of the portion where the metal of the metal powder exists in the cross section of the glass layer is 2% or less.

  As for the area ratio of the portion where the glass exists in the cross section of the metal layer 1a and the area ratio of the portion where the metal exists in the cross section of the glass layer 1b, the detection limit is the SEM-EPMA photograph of the cross section of the conductor layer over a length of 100 μm. It is obtained by photographing under the condition of 0.1% by mass.

The metal powder is a powder of one or more metals selected from the group consisting of silver, gold and a silver-palladium alloy, or one or more metals selected from the group consisting of silver, gold and a silver-palladium alloy. It is preferable to be a mixed powder of the above powder and palladium powder.
The specific resistance of the metal layer is preferably 3 μΩ · cm or less. If it exceeds 3 μΩ · cm, it will be difficult to use for high frequency passive components.
The conductor layer preferably does not contain lead.

Next, the method for producing a substrate with a conductor layer of the present invention (the production method of the present invention) is described.
The manufacturing method of this invention is suitable as a method of manufacturing the board | substrate with a conductor layer of this invention.
The conductor paste is usually composed of a first glass powder, a metal powder and an organic varnish, but may contain other powders as necessary.
When the mass ratio of the first glass powder and the metal powder is smaller than 3:97, the adhesive strength is lowered. Typically, it is 5:95 or more. If it is larger than 25:75, glass tends to be present on the surface of the conductor layer obtained by firing the conductor paste, and the solderability of the conductor layer is reduced or the specific resistance is increased. Typically it is 23:77 or less.

The first glass powder must deposit crystals upon firing. Otherwise, the glass flow during firing becomes excessive and glass tends to exist on the surface of the conductor layer.
The temperature (Tc) at which the first glass powder precipitates crystals is preferably 150 to 250 ° C. lower than the temperature (Tb) at which the firing is performed. If Tc is lower than Tb in a range of less than 150 ° C., the time during which the glass can flow during firing is shortened, and the glass is unlikely to exist at the interface with the ceramic layer, which may reduce the adhesive strength. More preferably, Tc is 180 ° C. lower than Tb. If Tc is lower than Tb by more than 250 ° C., the glass flow during firing becomes excessive, and there is a possibility that the glass tends to exist on the surface of the conductor layer. More preferably, Tc is lower than Tb in the range of 220 ° C. or lower.
Typically, Tc is 620 to 720 ° C and Tb is 850 to 900 ° C.

The softening point (Ts) of the first glass powder must be 260 to 370 ° C. lower than Tb. If Ts is lower than Tb in a range of less than 260 ° C., the time during which the glass can flow during firing is shortened, and the glass is unlikely to exist at the interface with the ceramic layer, which may reduce the adhesive strength. More preferably, Ts is lower by 300 ° C. or more than Tb.
Ts is typically 500-600 ° C.

The first glass powder is expressed in terms of mol% based on the following oxides: SiO ₂ 40-50%, B ₂ O ₃ 10-16%, ZnO 15-21%, Li ₂ O + Na ₂ O + K ₂ O 10-16% , Bi ₂ O ₃ 2-8%, TiO ₂ 1-6%, CeO ₂ 0-3% .
In this exemplary glass, in terms of mol%, B ₂ O ₃ is 10 to 15%, Li ₂ O is 4 to 8%, Na ₂ O is 5 to 9%, K ₂ O is 0 to 2%, Bi ₂ O ₃ Is typically 3-7% and TiO ₂ is 2-5%.

This glass consists essentially of the above components, may contain other components within a range not impairing the object of the present invention, in which case the total content of such components 10 mol% or less It is preferable that it is 5 mol% or less. For example, K ₂ O being 0 to 2% means that K ₂ O is not essential but may be contained up to 2%.

  The metal powder is preferably a powder of one or more metals selected from the group consisting of silver, gold, and a silver-palladium alloy.

The mass percentage display content ratio of the organic varnish in the conductor paste is preferably 3 to 20%. If it is less than 3%, the coating film strength before firing may be insufficient, or the paste viscosity may be increased and the printability may be reduced. If it exceeds 20%, the conductor layer has more voids and the specific resistance becomes larger, or the paste viscosity becomes too small and the printability may be lowered.
The conductor paste preferably does not contain lead.

The ceramic green sheet laminate is a laminate of green sheets.
Green sheets are made by methods well known in the LTCC technology. That is, a glass ceramic composition containing ceramic powder such as the second glass powder and alumina powder as an essential component, a resin such as polyvinyl butyral and acrylic resin, a solvent such as toluene, xylene, and butanol, and further phthalate as necessary. A plasticizer and a dispersant such as dibutyl acid, dioctyl phthalate, triethylene glycol, and polyethylene glycol are added and mixed to obtain a slurry. Next, the slurry is formed into a sheet shape by a doctor blade method or the like on a film of polyethylene terephthalate (PET) or the like. The sheet formed into a sheet is dried to remove the solvent to obtain a green sheet.

Although the second glass powder is a powder of glass containing _{SiO 2,} Al ₂ O 3, ZnO and the alkaline earth metal oxide in total 70 mol% or more, as good components also contain other _{B 2} Examples include O ₃ and Bi ₂ O ₃ . In addition, it is preferable that PbO does not contain.

As a second glass powder, as represented by mol% based on the following _{oxides, SiO 2 25~50%, B 2} O 3 0~25%, Al 2 O 3 3~12%, 1~22% ZnO, MgO + CaO + BaO A glass powder consisting essentially of 18-55% is exemplified. This exemplary glass consists essentially of the above components, but may contain other components as long as the object of the present invention is not impaired, in which case the total content of such components is 10 mol% or less. More preferably, it is 5 mol% or less.

A green sheet laminate was produced as follows.
First, raw materials were prepared and mixed so as to have a composition represented by mol% in the columns of SiO ₂ to SnO ₂ in Table 1, and the mixed raw materials were melted, and the obtained molten glass was poured out and cooled. . The cooled glass was pulverized to obtain powders of glasses AD. This powder was flaky and had an average particle size of 1 μm.

Next, glass ceramic compositions GC-A to GC-D containing the glass and ceramic powders in Table 2 at the ratios indicated by mass percentage in each column of glass amount and ceramic amount were prepared.
Sumiko Random AA2 manufactured by Sumitomo Chemical Co., Ltd. was used as the alumina powder.
The barium titanate powder was produced as follows. That is, 88 g of BaCO ₃ powder (barium carbonate BW-KT manufactured by Sakai Chemical Industry Co., Ltd.) and 130 g of TiO ₂ powder (HT0210 manufactured by Toho Titanium Co., Ltd.) were mixed in a ball mill using water as a solvent, and kept at 1150 ° C. for 2 hours after drying. . Thereafter, it was pulverized for 60 hours by a ball mill to obtain a powder having an average particle size of 1 μm.

For each of the glass ceramic compositions GC-A to D, an organic material containing toluene, xylene, isopropyl alcohol, and 2-butyl alcohol in a mass ratio of 4: 2: 2: 1 in 100 parts by mass of the glass ceramic composition. 70 parts by mass of solvent, 5 parts by mass of dioctyl phthalate, 0.3 parts by mass of a dispersant (BYK180 manufactured by BYK Japan) and 10 parts by mass of polyvinyl butyral were added and stirred to obtain a smooth slurry. . This slurry was applied onto a PET film by a doctor blade method and dried to obtain green sheets GS-A to D having a thickness of 200 μm.
For each of the green sheets GS-A to D, 6 sheets each having a size of 40 mm × 100 mm were laminated, heated to 80 ° C., and integrated by applying a pressure of 80 MPa to produce green sheet laminates A to D. .

On the other hand, glass powder 1 (mole%, SiO ₂ 44.65%, B ₂ O ₃ 13.13%, ZnO 18.44%, Li ₂ O 6.58%, Na ₂ O 7 as a conductive paste glass powder. 0.06%, K ₂ O 0.71%, Bi ₂ O ₃ 5.28%, TiO ₂ 3.15%, CeO ₂ 1.0%), glass powder 2 (mol%, SiO ₂ 51.9%) Al ₂ O ₃ 13.2%, ZnO 10.5%, MgO 24.4%) and glass powder 3 (SiO ₂ —B ₂ O ₃ —PbO glass powder ASF-1340 manufactured by Asahi Glass Co., Ltd.) were prepared.
Glass powders 1, 2, and 3 were all in the form of flakes having an average particle diameter of 1 μm.

Ts and Tc of glass powders 1, 2, and 3 were measured as follows. The results are shown in Table 3. In addition, about the glass powder 3, crystal precipitation was not recognized in the range up to 850 degreeC.
Ts, Tc: Measurement by differential thermal analysis, heat absorption when 30 mg of glass powder is filled in a platinum container using DTA-50 manufactured by Shimadzu Corporation and the temperature is raised to 900 ° C. at a speed of 10 ° C. per minute. From the curve, the temperature at the bottom of the second endothermic part was read for Ts, and the temperature at which heat generation was highest for Tc.

A conductor paste using glass powder 1, 2 or 3 was screen printed on the surface of the green sheet laminate A, B, C or D to produce a pattern as shown in FIG.
The left pattern in FIG. 4 is a specific resistance measurement pattern, the three large squares on the upper right side are solder wetting measurement patterns, and the twelve small squares on the lower right side are adhesive strength measurement patterns.

  Next, the green sheet laminate having such a pattern formed on the surface is placed in a box-type electric furnace, heated from room temperature to 550 ° C. for 5 hours, from 550 ° C. to 875 ° C. in 30 minutes, and at 875 ° C. The board | substrate with a conductor layer which performed the baking hold | maintained for 1 hour 30 minutes and has a conductor layer as shown in FIG. 4 on the surface was obtained.

Examples 1 to 7 in Tables 4 and 5 are examples of the production method of the present invention, Examples 8 to 11 are comparative examples, and Example 1 is an example of the substrate with a conductor layer of the present invention as described above. is there.
In Examples 8 and 9, the mass ratio of the glass powder of the conductive paste to the silver powder is outside the range of 3:97 to 5:75. In Example 10, the Ts of the glass powder of the conductive paste is 245 ° C. above the firing temperature, that is, 875 ° C. In Example 11, the glass powder of the conductor paste does not precipitate crystals upon firing.

  In Tables 4 and 5, the glass column shows the glass powder used in the conductor paste, the glass amount, silver powder amount, and varnish amount columns show the percentage content of each component of the conductor paste. In the column, the mass ratio of the glass powder and the silver powder is shown, and in the column of the laminate, the name of the green sheet laminate used is shown.

A silver powder having an average particle diameter of 3 μm was used as the silver powder.
As the organic varnish, an ethyl cellulose resin having a polymerization degree of 7 dissolved in α-terpineol so as to have a concentration of 20% by mass was used.
The conductive paste was prepared by mixing glass powder, silver powder and organic varnish in the ratios shown in Tables 4 and 5 and then kneading them in a porcelain mortar for 1 hour and further dispersing them three times with three rolls.

For the conductive layer-attached substrate of Examples 1-11, the specific resistance (unit: [mu] [Omega] · cm), the solder wettability (unit:%), the adhesive strength (unit:. Kg Weight / 2 mm ² Note, 1 kg weight / ^{2 mm} 2 = 2 .5 MPa) was measured as follows. The results are shown in Tables 4 and 5.
Specific Resistance: The electrical resistance R was measured for the specific resistance measurement pattern using a digital multimeter manufactured by Advantest Corporation. Furthermore, the cross section of the board | substrate with a conductor layer was observed with the scanning electron microscope, and the cross-sectional area S of the metal layer was calculated | required. R × S ÷ L was calculated using R, S and the length L of the conductive filament of the pattern, and this was defined as the specific resistance. The specific resistance is preferably 3 μΩ · cm or less.

  Solder wettability: After being immersed in a solder bath (3% Ag / 96.5% Sn / 0.5% Cu) maintained at 240 ° C. for 5 seconds and then cooled, the solder adheres to the conductor layer pattern area. The ratio of the area of the part was calculated and displayed. Solder wettability is an index of solderability and is preferably 100%.

Adhesive strength: After applying 3 μm of electroless Ni plating on the pattern for measuring adhesive strength of 2 mm square, and further applying 0.5 μm of electroless Au plating, 0.6 mm diameter Sn-plated copper wire is made L-shaped, The horizontal portion was soldered and measured by pulling at a rate of 20 mm / min with a tensile tester. The tensile force when the pattern was peeled was defined as the adhesive strength. The adhesive strength is preferably 2.0 kg weight (5.0 MPa) or more.
In Examples 9 and 10, soldering could not be performed and the adhesive strength could not be measured.

  It can be used as a passive component for high frequencies.

The conceptual diagram of the cross section of the ceramic substrate with a conductor layer. The SEM-EPMA photograph of the cross section of the surface layer conductor (conductor layer) portion of the ceramic substrate with a conductor layer conceptually sketched focusing on the layer structure. The conceptual diagram of the cross section in case the conductor layer is formed on the ceramic layer. The conceptual diagram of a conductor layer pattern.

Explanation of symbols

1: Surface layer conductor (conductor layer)
DESCRIPTION OF SYMBOLS 1a: Metal layer 1b: Glass layer 2: Inner layer conductor 3: Via conductor 10: Ceramic substrate with a conductor layer 11: Ceramic layer

Claims (12)

On the surface of the ceramic green sheet laminate that is fired to become a ceramic laminate,
A ceramic substrate obtained by firing a conductive paste that contains a glass powder and a metal powder and is fired to form a conductor layer,
The conductor layer on the ceramic laminate is separated into a metal layer present on its surface side and a glass layer on which crystals present on the interface side with the ceramic laminate are deposited ,
The glass powder is expressed in mol% based on the following oxides:
SiO ₂ 40~50%,
B ₂ O ₃ 10-16%,
ZnO 15-21%,
Li ₂ O + Na ₂ O + K ₂ O 10-16%,
Bi ₂ O ₃ 2-8%,
TiO ₂ 1-6%,
CeO ₂ 0-3%,
Essentially consists of
A ceramic substrate with a conductor layer, wherein the conductor layer does not contain lead .   2. The ceramic substrate with a conductor layer according to claim 1, wherein the area ratio of the portion where the glass exists in the cross section of the metal layer is 3% or less.   The ceramic substrate with a conductor layer according to claim 1 or 2, wherein an area ratio of a portion of the metal powder in the glass layer cross section where the metal exists is 2% or less.   The metal powder is a powder of one or more metals selected from the group consisting of silver, gold and a silver-palladium alloy, or one or more metals selected from the group consisting of silver, gold and a silver-palladium alloy. 4. The ceramic substrate with a conductor layer according to claim 1, wherein the ceramic substrate is a mixed powder of powder and palladium powder.   5. The ceramic substrate with a conductor layer according to claim 1, wherein the specific resistance of the metal layer is 3 μΩ · cm or less. A conductor paste containing the first glass powder and the metal powder in a mass ratio of 3:97 to 25:75,
It is a method for producing a ceramic substrate with a conductor layer by applying to the surface of a ceramic green sheet laminate containing a second glass powder and firing.
The first glass powder is a glass powder that is 260 to 370 ° C. lower than the temperature at which the crystals are precipitated and the softening point is fired when the firing is performed,
In mol% display based on the following oxides:
SiO ₂ 40~50%,
B ₂ O ₃ 10-16%,
ZnO 15-21%,
Li ₂ O + Na ₂ O + K ₂ O 10-16%,
Bi ₂ O ₃ 2-8%,
TiO ₂ 1-6%,
CeO ₂ 0-3%,
Essentially consists of
The conductive paste is a glass powder containing no lead,
A method for producing a ceramic substrate with a conductor layer, wherein the second glass powder is a glass powder containing SiO ₂ , Al ₂ O ₃ , ZnO and an alkaline earth metal oxide in a total amount of 70 mol% or more. The method for producing a ceramic substrate with a conductor layer according to claim 6 , wherein the softening point of the first glass powder is 500 to 600 ° C. The method for producing a ceramic substrate with a conductor layer according to claim 6 or 7 , wherein a temperature at which the first glass powder precipitates crystals is 150 to 250 ° C lower than a temperature at which the firing is performed. The method for producing a ceramic substrate with a conductor layer according to claim 6, 7 or 8 , wherein the temperature at which the first glass powder precipitates crystals is 620 to 720 ° C. The method for producing a ceramic substrate with a conductor layer according to any one of claims 6 to 9 , wherein the firing temperature is 850 to 900 ° C. Represented by mol% of the second glass powder following _{oxides, SiO 2 25~50%, B 2} O 3 0~25%, Al 2 O 3 3~12%, ZnO 1~22%, MgO + CaO + BaO 18~ The method for producing a ceramic substrate with a conductor layer according to any one of claims 6 to 10 , essentially consisting of 55%. The metal powder is a powder of one or more metals selected from the group consisting of silver, gold and a silver-palladium alloy, or one or more metals selected from the group consisting of silver, gold and a silver-palladium alloy. The method for producing a ceramic substrate with a conductor layer according to any one of claims 6 to 11 , which is a mixed powder of powder and palladium powder.

Images