JP4703212B2 - Wiring board and manufacturing method thereof - Google Patents

Description

  The present invention relates to a wiring board and a manufacturing method thereof, and more particularly to a wiring board that can be suitably used for a multilayer wiring board using a high-frequency signal, a package for housing semiconductor elements, a hybrid integrated circuit device, and the like, and a manufacturing method thereof.

  In recent years, low resistance is required for semiconductor element storage packages that mount semiconductor elements such as ICs and LSIs, which are becoming increasingly highly integrated, and wiring boards that are applied to hybrid integrated circuit devices on which various electronic components are mounted. Since a low-resistance metal such as copper can be used as a wiring conductor, a glass ceramic wiring board has attracted attention.

  Glass ceramics are generally obtained by combining glass and filler. Among them, crystals having desired characteristics are precipitated by using crystallized glass for the glass, and glass having various characteristics. There is a possibility of obtaining ceramics, and in recent years, intensive research has been conducted. The crystallized glass referred to in the present invention refers to glass that is in a glass state before firing and crystallizes after firing.

  In addition to reducing the resistance of conductors, a reduction in loss is strongly demanded in order to fully exploit the characteristics of electronic components. Glass ceramics that have a lower dielectric constant than alumina ceramic materials have a low loss, but in order to further reduce the loss, improvement of the wiring conductor is required. That is, when the electrical signal passing through the substrate becomes high frequency, it concentrates near the interface between the conductor and the insulator due to the skin effect, so the conductivity at the conductor interface affects the loss, but to suppress this decrease in conductivity. Is required to have a smooth interface between the conductor and the insulator.

  By the way, the conventional glass-ceramic wiring board has a structure in which a wiring conductor layer is disposed on the through-hole portion or the surface of the ceramic insulating substrate. In such a glass ceramic wiring board, as a specific method for forming a wiring conductor layer mainly composed of copper, silver, gold, etc. on the through-hole portion and / or the surface, a glass ceramic raw material powder, a solvent is added to the organic binder. The slurry prepared by addition is formed into a sheet by the doctor blade method, etc., and through holes are punched into the obtained green sheet, and the through holes are filled with a conductive paste mainly composed of copper, silver, gold, etc. Through-hole conductors are formed, and at the same time, a conductor paste mainly composed of copper, silver, gold, etc. is printed on the green sheet in the form of a wiring pattern by screen printing, etc., and through-hole conductors and wiring patterns are formed. A plurality of green sheets were stacked under pressure and fired at 800 to 1000 ° C. (for example, patent document) Reference).

  However, in the glass ceramic described in Patent Document 1, the roughness of the interface increases when the filler is present at the interface with the wiring pattern, and the roughness of the interface increases when crystals are precipitated from the glass at the interface. There is a problem that the high-frequency conduction distance is substantially increased, that is, the wiring pattern is substantially increased in size, and the loss is increased.

Therefore, for the purpose of reducing the roughness of the glass ceramic substrate surface, a method of forming a smooth layer that is sintered at a temperature lower than the sintering temperature of the glass ceramic material on both sides of the glass ceramic laminate has been proposed. ing. Since the smoothing layer suppresses the firing shrinkage of the glass ceramic laminate, the unevenness of the substrate surface, which is caused by locally different firing shrinkage behavior, is improved. Further, since the smooth layer contains a glass component in a weight ratio larger than the weight ratio of the glass component in the glass ceramic material, when a conductor is formed on the smooth layer, the conductor and the insulator (smooth layer) The roughness of the interface is improved (see, for example, Patent Document 2).
Japanese Patent Laid-Open No. 1-112605 JP 2002-246746 A

  However, the technique described in Patent Document 2 has the advantage that the surface of the substrate can be smoothed, and when the conductor is formed on the smooth layer, the roughness of the interface with the conductor is improved. There was a problem that the body interface could not be sufficiently smoothed.

  Accordingly, an object of the present invention is to provide a wiring board having a high conductivity near a conductor interface in a high frequency band and a low loss, and a method for manufacturing the same.

  The present invention is based on the novel knowledge that when a glass material contains a filler or a crystal phase and they are present in the vicinity of the interface, unevenness is generated at the interface and the smoothness of the interface is lowered. The smoothness of the interface between the ceramic insulating layer and the wiring conductor is improved by providing an intermediate layer made of glass that does not substantially contain a crystal phase at the interface with the wiring conductor.

That is, the wiring board according to the present invention is a wiring board comprising a wiring conductor made of glass ceramic fired at 800 to 1000 ° C., and having a wiring conductor formed on the surface of a ceramic insulating board containing a crystal phase and simultaneously fired with the ceramic insulating board. An intermediate layer made of glass having a softening point of 600 to 900 ° C. and containing substantially no crystal phase is provided between the ceramic insulating substrate and the wiring conductor.

Further, another wiring board of the present invention, made of a glass ceramic fired at 800 to 1000 ° C., comprising a surface and internal wiring conductor of the ceramic insulating base plate and the ceramic insulating layer is stacked containing a crystal phase wiring A softening point is 600 to 900 ° C. between at least one ceramic insulating layer provided inside the ceramic insulating substrate and a wiring conductor formed on the surface of the ceramic insulating layer. An intermediate layer made of glass substantially free of a crystal phase is provided.

It is preferable that the interface roughness R _max between the wiring conductor and the intermediate layer is 3 μm or less.

  The intermediate layer preferably has a thickness of 10 μm or less.

  It is preferable that the wiring conductor is formed by printing a conductive paste on a green sheet, and the average particle size of the metal powder contained in the conductive paste is 5 μm or less.

  It is preferable to flow an electromagnetic wave of 100 MHz or more through the wiring conductor.

Moreover, the manufacturing method of the wiring board of this invention apply | coats the glass paste containing the glass powder which does not precipitate a crystal | crystallization substantially at the time of baking whose softening point is 600-900 degreeC on the green sheet which comprises glass powder. After forming the non-crystallized glass layer, the conductor paste is printed on the non-crystallized glass layer to form a wiring pattern, and further, the non-crystallized glass layer is formed on the conductor pattern. It is characterized by co- firing at 800 to 1000 ° C.

  In the present invention, the cause of unevenness occurring at the interface of the wiring conductor is due to the crystal phase contained in the ceramic insulating substrate or ceramic insulating layer in contact with the wiring conductor, and by providing an intermediate layer, the interface of the wiring conductor is smoothed. It is based on the knowledge that it can be made.

  That is, the ceramic substrate in contact with the wiring conductor contains a crystal phase. For example, glass ceramics is composed of glass and crystallized glass, glass and ceramic filler, glass, crystallized glass and ceramic filler, crystallized glass, crystallized glass and ceramic filler, etc. A crystal phase is included in the bonded body, and glass ceramics include a crystal phase.

  When a conductive paste containing a low-resistance metal such as Cu, Ag, or Au is printed on a green sheet containing such glass ceramics and co-fired, the fluidity of the low-resistance metal softened during firing On the other hand, since crystal phases such as fillers and precipitated crystals have low fluidity, the interface is determined by the arrangement of crystal phases, and large irregularities are generated.

According to the present invention, an amorphous intermediate layer is formed between a ceramic insulating substrate including a crystal phase , which is made of glass ceramics fired at 800 to 1000 ° C., and a wiring conductor simultaneously fired with the ceramic insulating substrate. When the wiring substrate is made of a ceramic insulating substrate in which a plurality of ceramic insulating layers including a crystal phase are laminated, the softening point is 600 to 600 between the wiring conductor through which a high frequency passes and the adjacent ceramic insulating layer. By providing an amorphous intermediate layer made of glass that is substantially free of crystalline phase at 900 ° C., the interface of the wiring conductor is smoothed, and the conductivity near the conductor interface in the high frequency band is high, and the low loss It is possible to realize a simple wiring board and a manufacturing method thereof.

  Here, the electrical conductivity in the vicinity of the conductor interface in the high frequency band is affected by the specific resistance value of the wiring conductor and the shape of the interface between the wiring conductor and the ceramic insulating layer, but the shape of the interface is particularly important. This is because when the frequency of the electromagnetic wave flowing through the conductor increases, the current density flowing through the interface between the conductor and the ceramic insulating layer increases due to the skin effect. If the unevenness at the interface between the conductor and the ceramic insulation layer is large, the distance of charge movement will be longer than when the surface is smooth, and the charge will concentrate at the tip of the unevenness, resulting in a slow movement of charge. Decreases.

Therefore, an intermediate layer made of glass substantially free of crystal phase having a softening point of 600 to 900 ° C. is provided between the ceramic insulating substrate made of glass ceramic fired at 800 to 1000 ° C. and the wiring conductor. As a result, the glass softens and flows at a firing temperature of 800 to 1000 ° C., the intermediate layer absorbs irregularities on the surface of the ceramic insulating substrate, and the interface between the intermediate layer and the wiring conductor becomes smooth. can do. In addition, when the wiring board is made of a ceramic insulating substrate in which a plurality of ceramic insulating layers are laminated, the glass substantially does not contain a crystal phase at the interface between the ceramic insulating layer and the wiring conductor constituting the ceramic insulating substrate. By providing the intermediate layer, the interface of the wiring conductor can be similarly smoothed. Thereby, the electrical conductivity of the conductor interface can be improved.

  The wiring board of the present invention is a wiring board having a wiring conductor on the surface of a ceramic insulating substrate containing a crystal phase. In addition, the wiring board includes a wiring conductor on the surface and inside of a ceramic insulating board in which ceramic insulating layers containing crystal phases are laminated. In the following, the latter will be taken as an example, and a case where glass ceramics is used as the ceramic insulating layer will be described.

  Glass ceramics are featured because they can be fired at a low temperature with a wiring conductor made of a low-resistance metal such as Cu, and various characteristics can be obtained by combining glass and ceramic filler. This is because it can be suitably applied to a wiring board that can be used in a multilayer wiring board, a package for housing semiconductor elements, and a hybrid integrated circuit device.

  FIG. 1 is a partial cross-sectional view showing the structure of the wiring board of the present invention.

  According to FIG. 1A, the wiring board A of the present invention is composed of seven ceramic insulating layers 1a to 1g, and a surface conductor 2a is formed on the surface of the wiring board A. An internal conductor 2b is formed between the ceramic insulating layers 1a to 1g. In addition, via conductors 4 are formed in the ceramic insulating layers 1a to 1g in the thickness direction to connect the internal conductors 2b and to connect the surface conductor 2a and the internal conductor 2b.

According to the present invention, a crystal phase is substantially formed at the interface between the ceramic insulating layers 1a to 1g and the wiring conductor 2 composed of the surface conductor 2a and the internal conductor 2b formed on the surfaces of the ceramic insulating layers 1a to 1g. It is important to have an intermediate layer 3 made of glass that does not contain.

  For example, as shown in FIG. 1B, it is important that the intermediate layer 3 is provided at the interface between the internal wiring 2b and the ceramic insulating layer 1f and at the interface between the internal wiring 2b and the ceramic insulating layer 1g. It is.

As described above, the interface between the wiring conductor 2 and the ceramic insulating layer (1f, 1g) made of glass ceramic fired at 800 to 1000 ° C. does not substantially contain a crystalline phase having a softening point of 600 to 900 ° C. By providing the intermediate layer 3 made of glass, the glass softens and flows at the firing temperature, and the intermediate layer 3 absorbs the unevenness of the ceramic insulating substrate 1 , so that the interface between the wiring conductor 2 and the ceramic insulating substrate 1 is made smooth. Can do. Thereby, the electrical conductivity of the conductor interface can be improved.

  That is, since it contains crystallized glass and a filler, the interface 5a between the intermediate layer 3 and the ceramic insulating layers 1f and 1g has large irregularities, but the intermediate layer 3 is made of glass that does not contain a crystal phase. The smoothness of the interface 5b between the layer 3 and the internal wiring 2b is improved as compared with the interface 5a.

In addition, as shown in FIG. 1, the wiring board A of the present invention forms a ceramic insulating substrate 1 made of a laminate by laminating a plurality of ceramic insulating layers 1a to 1g , and the internal wiring 2b and the ceramic insulating layers 1a to 1g. even when the glass layer 3 is provided between the 1g, also the glass layer 3 may be provided on the surface wiring 2a and the ceramic insulating layer 1a~1g Tonokai surface.

  In particular, in recent wiring boards, a transmission line that requires low loss is often provided inside the ceramic insulating substrate 1 made of a laminate, and therefore the intermediate layer 3 is provided inside the ceramic insulating substrate 1. This is preferable because a wiring board with lower loss can be realized.

The maximum roughness R _max of the interface 5b between the wiring conductor 2 and the intermediate layer 3 is preferably 3 μm or less, particularly 2.5 μm or less, more preferably 2 μm or less in order to further reduce signal loss. Here, the maximum roughness R _max of the interface 5b between the wiring conductor 2 and the intermediate layer 3 is calculated by observing a cross section of the wiring board A with an SEM and measuring a length of 100 μm with respect to the length direction of the wiring. did. Specifically, an average line is drawn at the interface between the wiring conductor 2 and the intermediate layer 3, and the distance between the line parallel to the average line passing through the highest peak at the interface and the line parallel to the average line passing through the lowest valley bottom at the interface _{Was defined} as R _max .

  Further, when the intermediate layer 3 is formed only directly below the wiring conductor 2, the intermediate layer 3 is effectively suppressed at the end portion of the wiring conductor layer 6 in order to effectively suppress the occurrence of poor stacking between the ceramic insulating layers 1 f and 1 g. The thickness of is desirably thin. In addition, since glass generally has a high value of dielectric loss tangent, it is desirable that the thickness of the intermediate layer 3 be thinner in view of reducing loss. Specifically, the thickness of the intermediate layer 3 is preferably 10 μm or less, particularly 9 μm or less, and more preferably 8 μm or less.

Moreover, it is preferable that the softening point of the glass of the intermediate | middle layer 3 is 600-900 degreeC, especially 620-880 degreeC, Furthermore, it is preferable that it is 650-870 degreeC. That is, in order for the intermediate layer 3 to absorb the irregularities formed at the interface between the ceramic insulating layers 1a to 1g and the wiring conductor 2 and to smooth the interface between the wiring conductor 2 and the intermediate layer 3, the glass ceramic is fired. It is necessary to give the glass of the intermediate layer 3 appropriate fluidity at a temperature. Specifically, although the softening point of the glass used for the intermediate layer 3 depends on the type of glass ceramic used, Is preferably 600 to 900 ° C.

Examples of the glass powder used for the intermediate layer 3 include borosilicate glass, zinc borosilicate glass, and SiO ₂ —Al ₂ O ₃ —BaO—CaO—B ₂ O ₃ glass. These glasses are used because they have excellent wettability with the metal powder when co-fired with the metal powder, and in particular, borosilicate glass, especially SiO ₂ —Al ₂ O ₃ —BaO—CaO—B _2. It is preferable to use O ₃ glass.

  Moreover, it is preferable that the particle size of the metal powder contained in the conductor paste forming the wiring conductor 2 is small. When the particle size of the metal powder is large, the space between the metal particles in the paste becomes large, and this space greatly affects the unevenness caused by the conductor after firing. Specifically, it is desirable that the particle size of the metal powder used for the conductor paste is small.

  That is, the wiring conductor 2 is preferably formed by printing on a green sheet a conductor paste containing a metal powder having an average particle size of 5 μm or less, particularly 4 μm or less, and further 3 μm or less.

  Further, it is preferable to flow an electromagnetic wave of 100 MHz or more, particularly 500 MHz or more, and further 1 GHz or more to the wiring conductor 2. The reason why the interface between the wiring conductor 2 and the ceramic insulating layers 1a to 1g affects the signal loss is that the skin effect occurs when the electromagnetic waves flowing through the wiring conductor 2 become high frequency. Therefore, in order to sufficiently bring out the effect of providing the intermediate layer 3 between the wiring conductor 2 and the ceramic insulating layers 1a to 1g, it is preferable that the frequency of the electromagnetic wave flowing through the wiring conductor 2 is high.

  Next, the manufacturing method of the wiring board of this invention is demonstrated. A method for manufacturing the wiring substrate of FIG. 1 will be described as an example.

  The wiring board as shown in FIG. 1 is formed by applying a glass paste containing glass powder that does not substantially precipitate crystals upon firing onto a green sheet having glass powder to form an amorphous glass layer. It is important that the paste is printed on the non-crystallized glass layer to form a wiring pattern, and further the non-crystallized glass layer is formed on the conductor pattern and then fired.

  Specifically, first, a green sheet containing a crystal phase is produced after firing. In order to produce such a green sheet, crystallized glass powder alone, or glass powder and ceramic filler powder, crystallized glass powder and glass powder, crystallized glass powder and ceramic filler powder, crystallized glass as raw material powder Combinations of powder, glass powder, ceramic filler powder, and the like are possible.

The glass powder contains at least SiO ₂ and contains at least one of Al ₂ O ₃ , B ₂ O ₃ , ZnO, PbO, alkaline earth metal oxide, and alkali metal oxide. For example, borosilicate glass such as SiO ₂ —B ₂ O ₃ system, SiO ₂ —B ₂ O ₃ —Al ₂ O ₃ system—MO system (where M represents Ca, Sr, Mg, Ba or Zn) , Alkali silicate glass, Ba glass, Pb glass, Bi glass, and the like.

  These glasses are amorphous glass even when fired, and lithium silicate, quartz, cristobalite, cordierite, mullite, anosite, serdian, spinel, garnite, willemite, dolomite by firing. In this case, one that precipitates at least one kind of crystal of petalite, diopside or a substituted derivative thereof is used.

  Of these, cordierite-based crystallized glass is preferable from the viewpoint of increasing strength, and cordierite-based crystallized glass is preferable from the viewpoint of low dielectric constant and low thermal expansion.

As the ceramic filler powder, SiO ₂ such as quartz and cristobalite, Al ₂ O ₃ , ZrO ₂ , cordierite, mullite, forsterite, enstatite, spinel, magnesia and the like are preferably used. Among these, alumina is preferable in terms of high strength and low cost.

  A predetermined amount of the above raw material powder is weighed, and a slurry is prepared by adding an organic binder, an organic solvent, and a plasticizer if necessary. Then, a sheet shape is formed by a known forming method such as a doctor blade method, a rolling method, or a pressing method. A green sheet forming a ceramic wiring board having a thickness of 50 to 500 μm is formed.

Next, a glass paste for forming the intermediate layer is prepared. Glass powder is prepared as a raw material powder. It is important that the glass powder does not substantially precipitate crystals during firing, and specific examples include borosilicate glass, zinc borosilicate glass, and lead borosilicate glass. In particular, SiO ₂ —Al ₂ O ₃ —BaO—CaO—B ₂ O ₃ -based glass is preferable in that it is excellent in co-firing with metal powder at 800 to 1100 ° C.

  Here, substantially not precipitating crystals means that crystals are not precipitated during firing and are still in a glass state after firing.

  Moreover, it is preferable that the softening point of the glass powder contained in a glass paste is 600-900 degreeC, especially 620-880 degreeC, Furthermore, it is preferable that it is 650-870 degreeC.

  When the temperature is set, it is possible to suppress substrate warpage and undulation caused by a difference in sintering timing between the conductor and the insulating layer. This substrate warpage or undulation occurs when glass diffuses into the conductor, the diffused glass accelerates the sintering of the conductor, and the difference in sintering timing between the conductor and the insulator increases. By setting the softening point to the above temperature, it is possible to suppress glass diffusion from a low temperature, and thus it is possible to suppress substrate warpage and swell. Further, when the softening point of the glass is set to the above temperature, the glass can sufficiently reduce the viscosity in order to absorb the unevenness of the insulating layer, so that it becomes easier to achieve smoothing.

  The glass paste is prepared by adding the above glass powder, an organic binder, an organic solvent, and a dispersant as required. The viscosity of the paste is preferably 100 to 1000 poise, particularly 150 to 800 poise, more preferably 200 to 600 poise, from the viewpoint of paste printability, paste leveling property, and thin paste application.

  Moreover, a conductor paste is produced. A metal powder is prepared as a raw material powder. Examples of the metal powder include metals such as Cu, Ag, Au, Pd, and Pt, and alloys thereof. Of these, Cu is preferable in terms of low resistance and low cost, and Ag, Au, Pd, and Pt are preferable in that it can be fired in the atmosphere.

  The average particle size of the metal powder contained in the conductor paste is preferably 5 μm or less, particularly 4 μm or less, and more preferably 3 μm or less. By reducing the average particle size of the metal powder to 5 μm or less, particularly 4 μm or less, and further 3 μm or less, the roughness of the interface between the non-crystallized glass layer and the conductor pattern can be further reduced. , More effectively suppress penetration into the pores of the conductor pattern, and more effectively prevent the glass from flowing into the large void formed at the interface and increasing the interface roughness. Can do.

  And the non-crystallized glass layer is apply | coated to the surface of a green sheet using coating methods, such as a screen printing method, with the said glass paste. The thickness of the non-crystallized glass layer can be adjusted to 10 μm or less, particularly 9 μm or less, and more preferably 8 μm or less after firing. Is desirable because it makes the glass layer high.

  However, since the loss due to the conductor is more dominant than the loss due to the insulator in the microwave region, the influence of the dielectric loss tangent of the glass layer is small when the substrate of the present invention is used in the microwave. However, when it is used in a higher frequency region such as a millimeter wave band, the influence is increased, and therefore it is desirable to make the glass layer thinner because the loss due to the glass layer is reduced. At this time, the non-crystallized glass layer can be printed in the same pattern as a wiring conductor to be formed later, or can be printed on the entire green sheet.

  Furthermore, a conductor pattern layer that becomes a wiring conductor after firing is formed on the surface of the glass layer by screen printing or the like. That is, the conductor paste is screen-printed on the surface of the non-crystallized glass layer on the green sheet to form a wiring pattern.

  Note that via holes can be formed in the green sheet as desired, and via conductors can be filled into the via holes. The via hole and the via conductor can be produced either before or after the non-crystallized glass layer is formed.

  According to the present invention, thus forming a glass layer between a green sheet and a conductor pattern, and a green sheet or a laminate thereof formed with such an amorphous glass layer and a wiring pattern. It is important to form a wiring conductor through an intermediate layer on the surface of the ceramic insulating substrate by firing.

  In the process of firing the green sheet to produce a ceramic insulating substrate, the green sheet is softened and fluidized in a liquid phase of glass, and thereby sintered by rearranging the filler. At this time, irregularities are generated in the vicinity of the interface with the intermediate layer so as to follow the shape of the filler, and crystallized glass is precipitated as crystals, and large irregularities are generated in the vicinity of the interface with the intermediate layer. On the other hand, since the non-crystallized glass layer exists as an intermediate layer, the non-crystallized glass contained in the intermediate layer softens and flows, and the intermediate layer becomes a boundary where the interface with the wiring pattern is aligned with the formation surface of the glass paste, Furthermore, since the boundary becomes a smooth interface due to surface tension, large irregularities on the surface of the ceramic insulating substrate can be absorbed.

  Further, the wiring pattern has little influence on the interface smoothness, but further interface smoothness can be obtained by reducing the particle size of the metal powder in the conductor paste. That is, the particle size of the metal powder in the conductor paste is preferably 5 μm or less, particularly 4 μm or less, and more preferably 3 μm or less.

  Thus, since the intermediate layer is made of non-crystallized glass that does not contain crystallized glass, there is no precipitation of crystals that increase the unevenness of the interface, and the interface between the wiring conductor and the intermediate layer can be made smooth.

  Prior to firing, the organic sheet in the insulating substrate can be decomposed and removed by subjecting the green sheet or laminate thereof to heat treatment at 100 to 800 ° C., particularly 400 to 750 ° C., if desired. Further, it is preferable that the firing is performed at 800 to 1000 ° C., particularly 850 to 950 ° C., from the viewpoint of sufficient sintering and prevention of oversintering. At this time, when Cu is used as the metal in the conductor, firing is preferably performed in a nitrogen atmosphere from the viewpoint of preventing oxidation of Cu.

  By such a manufacturing method, the interface between the wiring conductor through which the high-frequency signal flows and the ceramic insulating substrate can be smoothed, and a low-loss wiring substrate having high conductivity near the conductor interface in the high-frequency band can be obtained. .

  The wiring board for conductivity evaluation shown in FIG. 2 was prepared. The wiring board of FIG. 2 is formed by laminating ceramic insulating layers 8a and 8b having a thickness of 200 μm to form a ceramic insulating substrate 8, and a conductor layer 9 having a diameter of 40 mm is embedded between the layers. At this time, sample no. Nos. 2 to 23 are provided with an intermediate layer made of glass substantially not containing a crystal phase at the interface between the ceramic insulating layers 8a and 8b and the conductor layer 9, and sample Nos. In 1, this intermediate layer was not formed. The procedure for manufacturing the substrate of FIG. 2 is described below.

First, the green sheet which comprises a ceramic insulating layer was produced. A raw material powder is prepared, and a crystallized glass powder having a composition of 50% by mass of SiO ₂ , 18.5% by mass of MgO, 26% by mass of CaO, and 5.5% by mass of Al ₂ O ₃ is 60% by mass. Then, 40% by mass of Al ₂ O ₃ as a ceramic filler component was weighed to prepare a glass ceramic composition.

  Using the slurry prepared by adding acrylic resin as a binder to the glass ceramic composition, dibutyl phthalate as a plasticizer, and toluene and isopropyl alcohol as a solvent, the glass ceramic composition was molded by a doctor blade method. A 250 μm green sheet was prepared.

  Next, an intermediate layer was produced. That is, an acrylic resin as an organic binder and a mixed solution of terpineol and dibutyl phthalate (80:20 by weight) as a solvent were added to a glass powder having a softening point shown in Table 1, and kneaded. A glass paste was prepared.

  Furthermore, a conductor paste was produced. That is, conductive powder having the average particle size shown in Table 1, that is, Cu powder, Ag powder having an average particle size of 2 μm, and Cu—Ag alloy powder having an average particle size of 2 μm (Cu: Ag ratio is 90:10). A conductive paste sample was prepared by adding and kneading each metal powder with an acrylic resin as an organic binder and a mixed solution of terpineol and dibutyl phthalate (80:20 by mass) as a solvent. .

  Subsequently, a circular glass layer having a diameter of 65 mm was formed on the surface of the green sheet by printing the previously obtained glass paste. The thickness of the glass layer at this time was 5 to 15 μm. Next, the produced conductor paste was printed on the produced glass layer to form a circular wiring pattern having a diameter of 60 mm and a thickness of 20 μm. Further, a glass paste was printed on the glass layer so as to cover the wiring pattern, a glass layer was formed, and the wiring pattern was embedded in the glass layer.

  On the green sheet in which the wiring pattern thus obtained is embedded in the glass layer, another green sheet (hereinafter simply referred to as a green sheet alone) having no glass layer or wiring pattern formed on the surface is laminated. Thus, a laminate was produced. At this time, an adhesive was uniformly applied between the green sheets, and pressure lamination was performed under the conditions of 45 ° C. and 4 MPa.

  Sample No. As a comparative example, No. 1 was prepared by forming a pattern directly on a green sheet without providing an intermediate layer, and laminating a single green sheet on the green sheet to produce a laminate.

Subsequently, these laminates are placed on an Al ₂ O ₃ base plate and subjected to heat treatment at 720 ° C. in a nitrogen atmosphere in order to decompose and remove organic components such as an organic binder, and then in a nitrogen atmosphere. And calcination at 900 ° C. for 1 hour.

Two obtained wiring boards for electrical conductivity evaluation were prepared, and the electrical conductivity at the interface between the conductor and the insulator was measured using a cylindrical resonator method. The conductivity is standardized by copper conductivity of 5.8 × 10 ⁷ / Ω · m. For the details of the measurement method, the method disclosed in JP-A-12-46756 was used.

  Next, in order to evaluate the board warpage, a wiring board for warpage evaluation was produced. That is, a glass paste and a conductor paste having a fired shape of 10 mm × 10 mm were sequentially printed on the entire surface of the green sheet. Using the obtained green sheet as the uppermost layer, four green sheets alone were laminated and pressure-bonded so that a wiring pattern was formed on the surface.

  The warpage was measured using a surface roughness meter on a ceramic substrate on which a conductor pattern of 10 mm × 10 mm was formed.

  Moreover, the presence or absence of a stacking failure was determined by observing the cross-sectional structure of the substrate with an SEM. At that time, those having no stacking faults at the pattern end portions are indicated as “◯”, and those having the pattern are indicated as “×” in Table 1.

Rmax is broken by applying a load in the thickness direction to the wiring board for conductivity evaluation, polished until the fracture surface becomes a mirror surface, and the cross section is observed at a magnification of 2000 using an SEM, It calculated by _Rmax calculation method.

The results are shown in Table 1.

  Sample No. of the present invention. In Nos. 2 to 23, the conductivity was 75% or more and the warpage was 120 μm or less. In particular, in a sample in which the particle size of the metal powder was 5 μm or less and the softening point of the intermediate layer glass was 600 to 900 ° C., the conductivity was 85% or more and the warp was 100 μm or less.

  On the other hand, a sample No. outside the scope of the present invention in which no intermediate layer was provided. 1, the conductivity was as low as 70%.

The structure of the wiring board of this invention is shown, (a) is a fragmentary sectional view, (b) is a fragmentary sectional view near an electrode. The electrical conductivity measurement sample produced in the Example is shown, (a) is a top view and (b) is a cross-sectional view.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Ceramic insulation board 1a-1g ... Ceramic insulation layer 2 ... Wiring conductor 2a ... Surface conductor 2b ... Internal conductor 3 ... Intermediate layer 4 ... Via conductor 5a ... The interface 5b between the ceramic insulating substrate and the intermediate layer ... The interface between the intermediate layer and the wiring conductor 6 ... The wiring conductor layer including the intermediate layer
8 ... Ceramic insulating substrate 8a , 8b ... Ceramic insulating layer 9 ... Wiring conductor (conductor layer)

Claims (7)

A wiring board comprising a wiring conductor made of glass ceramics fired at 800 to 1000 ° C. and having a crystal phase and a ceramic conductor that is fired simultaneously with the ceramic insulating board, the ceramic insulating board; A wiring board comprising an intermediate layer made of glass having a softening point of 600 to 900 ° C. and containing substantially no crystal phase, between the wiring conductors. Consisting fired glass ceramic at 800 to 1000 ° C., the surface and the ceramic insulating base plate and the ceramic insulating layer is stacked containing a crystal phase, the wiring comprising the ceramic insulating substrate and cofired comprising wiring conductors a substrate, said ceramic insulating layer at least one layer of which is provided in the interior of the ceramic insulating substrate, between the surface to form a wiring conductor of the ceramic insulating layer, softening point at 600 to 900 ° C. wiring board, characterized by comprising an intermediate layer made from a certain substantially glass containing no crystalline phase. The circuit board according to claim 1 or 2 interface roughness R _max of the wiring conductor and the intermediate layer is equal to or is 3μm or less. The thickness of the said intermediate | middle layer is 10 micrometers or less, The wiring board in any one of Claims 1-3 characterized by the above-mentioned. Said wiring conductor is formed by printing a conductive paste on the green sheet, to any one of claims 1 to 4, wherein the average particle size of the metal powder contained in the conductor paste is 5μm or less The wiring board described. Wiring board according to any one of claims 1 to 5, characterized in that flow electromagnetic waves than 100MHz in the wiring conductor. After forming a non-crystallized glass layer by applying a glass paste containing glass powder that has a softening point of 600 to 900 ° C. and that does not substantially precipitate crystals during firing, on a green sheet having glass powder, A conductive paste is printed on the non-crystallized glass layer to form a wiring pattern, a non-crystallized glass layer is further formed on the conductive pattern, and then co- fired at 800 to 1000 ° C. A method of manufacturing a wiring board.

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