JP4845675B2 - Glass ceramic multilayer circuit board - Google Patents

Description

  TECHNICAL FIELD The present invention relates to a glass ceramic multilayer circuit board, and in particular, by firing a plurality of glass ceramic green sheets having different shrinkage curves (behaviors) in firing, firing in a plane direction of the glass ceramic green sheet. The present invention relates to a glass-ceramic multilayer circuit board with excellent dimensional accuracy in which the above is suppressed.

  Conventionally, in a multilayer circuit board used in the field of mobile communication, etc., Ag, Cu, Au, Pd, Pt or a mixture thereof having high conductivity is used as a conductor material, and the melting point of the conductor material is used as an insulating layer material. Glass ceramic multilayer circuit boards using glass ceramics that can be fired at a low temperature are widely used.

  In recent years, in a glass ceramic multilayer circuit board, it has become one of important techniques to improve the board dimensional accuracy. A glass ceramic multilayer circuit board shrinks in volume by about 40 to 50% by firing. At this time, the variation in the shrinkage rate (average of 15 to 20% in one direction) in the direction parallel to the main surface of the glass ceramic multilayer circuit board (average in one direction is about 15 to 20%) becomes the positional variation of the wiring layer, resulting in poor substrate dimensional accuracy.

  Here, the shrinkage rate is defined as a value obtained by dividing a value obtained by subtracting a dimension after firing from a dimension before firing by a dimension before firing.

  In addition, these glass ceramic multilayer circuit boards are very demanded for high density, small size and light weight, and in glass ceramic multilayer circuit boards mounted on portable information communication devices represented by mobile phones, The demand is particularly strong. Among the demands for miniaturization, the low profile must be dealt with by reducing the thickness of the insulating layers that make up the ceramic multilayer circuit board. The problem that it becomes easy to break occurs.

  Therefore, for the former problem, as a method for improving the substrate dimensional accuracy, two or more types of green sheets having different firing shrinkage start temperatures are stacked and fired to suppress shrinkage in the plane direction. A method of reducing the shrinkage in the planar direction by shrinking in the thickness direction has been proposed (see, for example, Patent Document 1).

  In Patent Document 1, an insulating layer having a lower firing shrinkage start temperature is disposed on the outermost layer of the multilayer circuit board, and the thickness of the outermost insulating layer is compared with the thickness of the insulating layer having a higher firing shrinkage start temperature. It is also described that the shrinkage in the planar direction can be further reduced by reducing the thickness by 50% or more.

Also, for the latter problem, it has been proposed to improve the substrate strength by increasing the proportion of the crystal phase in the glass ceramic material constituting the insulating layer (see, for example, Patent Document 2).
Japanese Patent Laid-Open No. 2004-200679 JP 2002-338341 A

  However, the insulating layer having the lower firing shrinkage start temperature is disposed on the outermost layer of the multilayer circuit board, and the thickness of the outermost insulating layer is 50% or more thinner than the thickness of the insulating layer having the higher firing shrinkage start temperature. In addition, when the ratio of the crystal phase of the outermost insulating layer is further increased, the rearrangement of the crystal phase in the insulating layer may not be sufficiently performed in the range where the thickness of the outermost insulating layer is 30 μm or less. As a result, voids penetrating the insulating layer after firing, or very large voids with a maximum opening diameter of 15 μm or more are generated. There was a problem of causing variation. Such a phenomenon occurs when the surface of the outermost insulating layer is exposed to the atmosphere, and the glass component evaporates from the surface or crystallization proceeds from the surface. This phenomenon occurs remarkably when the glass component is small.

  The present invention is proposed as a result of taking such circumstances into consideration, and the object is to provide a glass ceramic multilayer circuit having high dimensional accuracy and stable high substrate strength even when the thickness of the insulating layer is reduced. It is to provide a substrate.

  The glass-ceramic multilayer circuit board of the present invention is a glass-ceramic multilayer circuit board comprising a plurality of insulating layers made of a glass-ceramic material and having different firing shrinkage start temperatures, and wiring, wherein the insulating board The outermost insulating layer having a thickness of 5 to 30 μm, a first insulating layer in contact with the outermost insulating layer, and a second insulating layer in contact with the first insulating layer, The firing shrinkage start temperature of the insulating layer is lower than the firing shrinkage start temperatures of the second insulating layer and the outermost insulating layer, and the ratio of the amorphous phase in the first insulating layer is the outermost insulating layer and the first insulating layer. And the thickness of the outermost insulating layer is smaller than the thickness of the second insulating layer.

  In the glass ceramic multilayer circuit board of the present invention, the maximum opening diameter of the voids opened on the surface of the outermost insulating layer is 10 μm or less, and the maximum opening diameter is 80% or less of the thickness of the outermost insulating layer. It is desirable that

  In the glass ceramic multilayer circuit board of the present invention, it is desirable that the glass ceramic material constituting the outermost insulating layer and the glass ceramic material constituting the second insulating layer are the same.

  In the glass ceramic multilayer circuit board of the present invention, it is desirable that the thickness of the second insulating layer is thicker than the thickness of the first insulating layer.

  The glass ceramic multilayer circuit board of the present invention has a difference in the firing shrinkage start temperature of the insulating layer made of the glass ceramic material, so that the firing shrinkage is started when the first insulating layer starts firing shrinkage. When the outermost insulating layer and the second insulating layer in contact with the first insulating layer are not contracted in the planar direction by the outermost insulating layer and the second insulating layer in contact with the first insulating layer, the outermost insulating layer and the second insulating layer in contact with the first insulating layer are contracted. Since the first insulating layer suppresses shrinkage in the planar direction of the outermost insulating layer and the second insulating layer, the shrinkage in the planar direction of the glass ceramic multilayer circuit board of the present invention is suppressed.

  Furthermore, by using a layer having a higher proportion of the amorphous phase than the first insulating layer as the outermost insulating layer, generation of large voids or scratches on the surface can be suppressed.

  In addition, by providing a first insulating layer having a higher proportion of crystalline phase than the outermost insulating layer adjacent to the inner side of the outermost insulating layer, the strength is high in the vicinity of the surface layer of the insulating substrate where stress is easily applied. Since the first insulating layer can be disposed, a high-strength insulating layer is disposed in the vicinity of the surface, so that the outermost insulating layer has a thickness of 5 to 5 in combination with the absence of large voids or scratches on the surface. Even when the thickness is reduced to 30 μm, the insulating substrate has high strength.

  In the glass ceramic multilayer circuit board of the present invention, the maximum opening diameter of the void opened on the surface of the outermost insulating layer is 10 μm or less, and the maximum opening diameter is 80% or less of the thickness of the outermost insulating layer. It is desirable. Thereby, the strength reduction and variation of the glass ceramic multilayer circuit board can be prevented, and the glass ceramic multilayer circuit board having high strength can be stably obtained.

  In the glass ceramic multilayer circuit board of the present invention, it is desirable that the glass ceramic material constituting the outermost insulating layer and the glass ceramic material constituting the second insulating layer are the same. The shrinkage in the planar direction due to firing of the outermost insulating layer and the second insulating layer is constrained by the first insulating layer that has already started sintering, and the outermost insulating layer and the second insulating layer are restrained. By using the same material for the layers, the warpage of the glass ceramic multilayer circuit board can be reduced by causing the outermost insulating layer and the second insulating layer to start shrinking at the same timing on both surfaces of the first insulating layer. it can.

  In the glass ceramic multilayer circuit board of the present invention, it is desirable that the thickness of the second insulating layer is thicker than the thickness of the first insulating layer.

Since the suppression of the shrinkage in the planar direction due to the firing of the first insulating layer is due to the unfired outermost insulating layer and the second insulating layer having a low rigidity, the volume fraction of the first insulating layer in the substrate By making the value smaller than that of the second insulating layer, the contraction in the planar direction of the first insulating layer can be more effectively suppressed by the second insulating layer.

  For example, as shown in FIG. 1, a glass ceramic multilayer circuit board 1 of the present invention is made of a glass ceramic material, and includes an insulating substrate 9 made of a plurality of insulating layers 3, 5, 7 having different firing shrinkage start temperatures, and wiring 11. , 13, 13 is a glass ceramic multilayer circuit board 1, wherein the outermost insulating layer 3 is the outermost layer of the insulating substrate 9, and the first insulating layer 5 is disposed in contact with the inner side of the outermost insulating layer 3. An insulating substrate 9 formed by laminating a second insulating layer 7 in contact with the first insulating layer 5, a surface conductor 11 formed on the surface of the insulating substrate 9, and an internal conductor formed inside the insulating substrate 9 13 and via-hole conductor 15.

  In the glass ceramic multilayer circuit board 1 of the present invention, the firing shrinkage start temperature of the first insulating layer 5 is lower than the firing shrinkage start temperatures of the outermost insulating layer 3 and the second insulating layer 7, and the first insulating layer 5. The ratio of the amorphous phase is smaller than the ratio of the amorphous phase in the outermost insulating layer 3 and the second insulating layer 7, and the thickness of the outermost insulating layer 3 is thinner than the thickness of the first insulating layer 5, It is important that the thickness of the outermost insulating layer 3 is 5 to 30 μm.

  According to the present invention, by using a plurality of insulating layers having different firing shrinkage start temperatures, for example, when the first insulating layer 5 starts firing shrinkage, the first insulating layer 5 undergoes firing shrinkage. When the outermost insulating layer 3 and the second insulating layer 7 are restrained by the unstarted outermost insulating layer 3 and the second insulating layer 7 and the outermost insulating layer 3 and the second insulating layer 7 start firing shrinkage, the outermost insulating layer 3 and the second insulating layer 7 This insulating layer 7 is constrained by the first insulating layer 5 which has already started firing shrinkage, and as a result, shrinkage in the planar direction due to firing of the glass ceramic multilayer circuit board 1 is suppressed. In particular, when the outermost insulating layer 3 and the second insulating layer 7 start firing shrinkage, the firing shrinkage of the first insulating layer 5 is almost completed (98% or more of the final firing volume shrinkage). Can reduce the shrinkage in the planar direction by firing to 5% or less, further 2% or less, and particularly 1% or less.

  Note that the firing shrinkage start temperature here is defined as a temperature at which the target material is fired alone and contracted by 2% of the final fired volume shrinkage. The volume shrinkage is measured by TMA (thermomechanical analysis) by pressing the outermost insulating layer 3, the first insulating layer 5, and the second insulating layer 7 independently. At this time, each contracts isotropically, and volume contraction can be obtained by converting from linear contraction of TMA to volume contraction.

  Further, according to the present invention, the outermost insulating layer 3 having an amorphous phase more than the first insulating layer 5 and having a thickness of 5 to 30 μm is provided on the surface of the insulating substrate 9. By providing the outermost insulating layer 3 with a smooth surface and no large voids or opening holes on the surface of the first insulating layer 5 having higher strength, it becomes a source of destruction of the surface of the first insulating layer 5. The glass ceramic multilayer circuit board 1 has a structure in which the outermost insulating layer 3 covers the voids and the opening holes.

  Thus, the strength of the glass ceramic multilayer circuit board 1 can be increased.

  That is, the glass-ceramic multilayer circuit board 1 of the present invention can maintain strength and is excellent in dimensional accuracy even when it corresponds to a reduction in height.

  When the thickness of the outermost insulating layer 3 exceeds 30 μm, the strength of the outermost insulating layer 3 itself becomes dominant, and the strength of the insulating substrate 9 tends to decrease. On the other hand, when the thickness of the outermost insulating layer 3 is less than 5 μm, it becomes difficult to sufficiently cover the surface of the first insulating layer 5 and the variation in strength tends to increase. The thickness of the outermost insulating layer 3 is preferably 10 to 15 μm.

  Further, when the proportion of the crystalline phase of the outermost insulating layer 3 is increased, it becomes difficult to smooth the surface of the insulating substrate 9, and an opening hole is easily formed on the surface of the outermost insulating layer 3. The effect of providing the layer 3 is lost.

  For example, as in the invention described in Patent Document 2, in the case where an insulating layer having a large crystalline phase is disposed as the outermost layer, the effect is not sufficiently exhibited unless the insulating layer is thickened. This is because the outermost layer is in contact with the atmosphere, so that the glass component is easily crystallized, and when it is thin, densification is hindered.

  On the other hand, according to the present invention, the thickness of the outermost insulating layer 3 can be further reduced as compared with the invention described in Patent Document 1, and the strength can be maintained even in a region of 5 to 30 μm or less.

  Here, the ratio of the amorphous phase is defined by (“mass of insulating layer” − “total of mass of all crystal layers”) / “mass of insulating layer” in each insulating layer. The ratio of the mass of the amorphous phase contained in each insulating layer is represented. The mass of the crystalline phase in the insulating layer is calculated by Rietveld analysis. By using ZnO, Si, CaF, etc. as an internal standard sample, the measurement accuracy can be improved, but an error of about ± 3% by mass including.

  The total crystal phase includes all crystal phases such as those existing as fillers in the raw material powder stage, those crystallized and precipitated from glass during firing, and those produced by the reaction between glass and filler.

  In addition, the insulating layer having the same composition as the first insulating layer 5 and the insulating layer having the same composition as the second insulating layer 7 are alternately arranged in the present invention to control the thickness of the glass ceramic multilayer circuit board 1. It goes without saying.

  Further, it is desirable that the maximum opening diameter of the voids opened on the front and back surfaces of the glass ceramic multilayer circuit board 1 is 10 μm or less and the maximum opening diameter is 80% or less of the thickness of the outermost insulating layer 3. Thereby, the strength reduction and variation of the glass ceramic multilayer circuit board 1 can be remarkably reduced, and the glass ceramic multilayer circuit board 1 having high strength stably can be obtained. More preferably, the maximum opening diameter is 7 μm or less, the maximum opening diameter is 75% or less of the thickness of the outermost insulating layer 3, particularly the maximum opening diameter is 5 μm or less, and the maximum opening diameter is the outermost insulating layer 3. It is desirable that it is 70% or less of the thickness.

  Further, it is desirable that the glass ceramic material constituting the outermost insulating layer 3 and the glass ceramic material constituting the second insulating layer 7 are the same. Since the shrinkage in the plane direction due to the firing of the outermost insulating layer 3 and the second insulating layer 7 is both restrained by the first insulating layer 5 which has already started sintering, the outermost insulating layer 3 And the second insulating layer 7 are made of the same material, and the shrinkage of the outermost insulating layer 3 and the second insulating layer 7 is started at the same timing on both surfaces of the first insulating layer 5, thereby forming a glass ceramic multilayer circuit. The warpage of the substrate can be reduced.

  In addition, when insulating layers with different compositions are stacked and fired simultaneously, mutual diffusion occurs between the two, and complex sintering behavior is likely to occur. However, by reducing the types of insulating layers used, Items to be considered can be reduced.

  In the insulating substrate 9, the thickness of the first insulating layer 5 is preferably thinner than the thickness of the second insulating layer 7. Since the suppression of the shrinkage in the planar direction due to the firing of the first insulating layer 5 is due to the outermost insulating layer 3 and the outermost second insulating layer 7 in the unfired state having a low rigidity, the first insulating layer 5 By reducing the volume fraction of the substrate, that is, by reducing the thickness of the first insulating layer 5 and reducing the absolute amount of shrinkage, the shrinkage in the planar direction of the outermost insulating layer 3 is more effectively suppressed. can do. Specifically, when the thickness of the first insulating layer 5 is 60% or less, particularly 50% or less of the thickness of the second insulating layer 7, the above effect can be easily obtained.

  The outermost insulating layer 3, the first insulating layer, and the second insulating layer 7 are desirably made of a glass ceramic material containing a glass phase and a crystal phase, and are within the scope of the present invention. The types, combinations, composition ratios, and the like of the constituent components and the glass phase and the crystal phase can be arbitrarily selected, whereby the outermost insulating layer 3, the first insulating layer 5 and the second insulating layer 7 can be selected. It is possible to control characteristics such as mechanical characteristics, electrical characteristics, and thermal characteristics.

  Details of the glass ceramic material will be described below.

As the glass phase, at least SiO ₂ is contained, and further tetravalent metal oxides such as CeO ₂ , ZrO ₂ , TiO ₂ , SnO ₂ , Al ₂ O ₃ , B ₂ O ₃ , Y ₂ O ₃ , La ₂ O. ₃ such trivalent metal oxides or alkaline earth oxides (hereinafter MO), ZnO, 2-valent metal oxides, such as PbO, alkali metal oxides (hereinafter _M 2 O) 1-valent metal oxides, such as, more It is preferable to include at least one of transition metal oxides and the like.

In order to reduce the proportion of the amorphous phase in the insulating layer, it is necessary to control the glass powder to a composition that facilitates crystallization, or to select a combination in which a crystal layer is likely to be formed by the reaction between the glass powder and the ceramic powder. . For example, the composition in the glass should be a composition close to the stoichiometric composition of the precipitated crystal phase, contain a nucleating agent such as ZrO ₂ or TiO _2, or select a ceramic powder that easily reacts with the glass. , Etc.

Examples of the glass used include borosilicate systems such as SiO ₂ —B ₂ O ₃ glass, SiO ₂ —B ₂ O ₃ —MO glass, and SiO ₂ —B ₂ O ₃ —Al ₂ O ₃ —MO glass. Examples thereof include glass and Bi-based glass. These glass phases may be so-called residual glass phases in which the composition of the glass in the glass ceramic material is changed with the crystallization during firing from the unfired powder state.

  Crystal phases contained in the outermost insulating layer 3, the first insulating layer 5 or the second insulating layer 7 include alumina, zirconia, quartz, cristobalite, cordierite, mullite, spinel, garnite, enstatite, forsterite. And anorthite, slausonite, serdian, diopside, montericite, akermanite, willemite, silicon nitride, aluminum nitride, silicon carbide, boron carbide, solid solutions thereof, substituted derivatives, and the like.

  Of these crystal phases, it is preferable to employ alumina, zirconia, forsterite, enstatite, spinel, anorthite, slusonite, and serdian, particularly alumina, zirconia, and serdian are preferred in terms of improving the bending strength. . In terms of improving acid resistance, alumina, zirconia, forsterite, enstatite, spinel, anorthite, slausonite, serdian, cordierite are preferable, and alumina and zirconia are particularly preferable.

  Furthermore, forsterite, enstatite, quartz, cristobalite, and cordierite are preferred in order to lower the dielectric constant and reduce transmission loss of high-frequency signals. In order to improve thermal conductivity, alumina, silicon nitride, aluminum nitride, and silicon carbide are preferable, and aluminum nitride is particularly preferable.

  Further, by setting the glass ceramic material to the above composition, low-temperature sintering at 1000 ° C. or less is possible, and as the surface conductor 11, the internal conductor 13 formed inside the insulating substrate 9, and the via-hole conductor 15, Cu , Ag and the like can be formed using a low-resistance conductor, and high-speed signal transmission is possible.

  Next, a method for producing the glass ceramic multilayer circuit board 1 of the present invention will be described.

  First, glass powder A for constituting outermost insulating layer 3, glass powder B for constituting first insulating layer 5, and glass powder C for constituting second insulating layer 7 as raw material powders. And ceramic powder as required.

The glass powders A, B, and C contain at least SiO ₂ , and further tetravalent metal oxides such as CeO ₂ , ZrO ₂ , TiO ₂ , SnO ₂ , Al ₂ O ₃ , B ₂ O ₃ , Y ₂ O. ₃ , trivalent metal oxides such as La ₂ O ₃ , alkaline earth oxides, divalent metal oxides such as ZnO and PbO, monovalent metal oxides such as alkali metal oxides, further transition metal oxides, Of these, those containing at least one kind are preferably used. At this time, the firing shrinkage starting temperature of the first insulating layer 5 is lower than the firing shrinkage starting temperatures of the outermost insulating layer 3 and the second insulating layer 7, and the ratio of the amorphous phase in the first insulating layer 5 is It is necessary to adjust the glass ceramic material for constituting each insulating layer so as to be smaller than the ratio of the amorphous phase in the outermost insulating layer 3 and the second insulating layer 7.

  As a method for adjusting the firing shrinkage start temperature of the outermost insulating layer 3, the first insulating layer 5, and the second insulating layer 7, the outermost insulating layer 3, the first insulating layer 5, and the second insulating layer 7 are used. It is effective to change the particle size and glass transition point of the glass powder contained in the glass ceramic materials A, B, and C for forming the glass. In general, the smaller the particle size of the glass powder and the lower the glass transition point, the lower the firing shrinkage start temperature. In particular, changing the glass transition point has a great influence on the firing shrinkage start temperature.

  In producing the glass ceramic green sheet, first, glass powder, ceramic powder, an organic binder, an organic solvent, and a plasticizer as necessary are used for the outermost insulating layer 3, the first insulating layer 5 and the second insulating layer 7. Mix and slurry. Using this slurry, a thin layer is formed by a doctor blade method or the like, and cut into predetermined dimensions to produce glass ceramic green sheets A, B, and C. At this time, the thickness of the glass ceramic green sheet A can be formed thinner than the thickness of the glass ceramic green sheet B in order to make the outermost insulating layer 3 after firing thinner than the thickness of the first insulating layer 5. is important.

  In some cases, the glass ceramic green sheet C for forming the first insulating layer 5 and the second insulating layer 7 is pressure-bonded, or after the glass ceramic green sheet B is formed, the glass ceramic green sheet C is directly applied to the surface thereof. (The order of B and C may be switched) to form a glass ceramic green sheet composite, and this composite can be put into subsequent steps as a layer unit. The green sheet for forming the outermost insulating layer 3 is formed by pressing the glass ceramic green sheet A on the glass ceramic green sheet B side in the composite, or on the glass ceramic green sheet B side in the composite. The glass ceramic green sheet A may be directly formed on the surface to form a glass ceramic green sheet composite for the outermost layer.

  Next, through holes are formed in the glass ceramic green sheet by punching or the like. The through-hole is filled with a conductor paste that becomes a via-hole conductor. As the conductor paste, an organic binder, an organic solvent, and additives as required are added to either Ag powder or Cu powder and kneaded with three rolls or the like. For the filling, a screen printing method is used by using a metal mask or an emulsion mesh screen mask perforated at a position corresponding to the through conductor forming position. Furthermore, the surface conductor layer and the inner conductor layer are deposited by screen printing using a conductor paste.

  For the internal conductor and the surface layer conductor, the same metal powder as the main component of the via-hole conductor can be used as the main component. Both conductors are not particularly limited in terms of the presence and amount of the organic vehicle, organic solvent, glass powder and the like added to the metal powder as a conductor paste, and can be appropriately adjusted and added.

  Each glass ceramic green sheet or glass ceramic green sheet composite thus obtained is laminated according to a predetermined lamination order to form a laminated molded body, and then fired.

  In firing, the temperature is raised, and after reaching the shrinkage start temperature of the first insulating layer 5, the temperature is gradually raised, or the shrinkage start temperature, or the shrinkage start temperature or higher and the outermost insulating layer 3 and the second insulation layer The temperature in the furnace is temporarily maintained at a temperature lower than the shrinkage start temperature of the insulating layer 7, and the first insulating layer 5 is maintained until the firing shrinkage of 98% or more of the final firing volume shrinkage proceeds. At this time, the first insulating layer 5 is shrunk in the thickness direction while being shrunk in the plane direction by the outermost insulating layer 3 and the second insulating layer 7 that are not fired and shrunk at that temperature. Thereafter, after the first insulating layer 5 contracts by 90% or more of the final firing volume shrinkage, the temperature is raised to the shrinkage start temperature of the outermost insulating layer 3 and the second insulating layer 7 and fired. By this firing, the outermost insulating layer 3 and the second insulating layer 7 are fired and shrunk in the thickness direction while firing shrinkage in the plane direction is suppressed by the first insulating layer 5 whose sintering is almost completed. As a result, it is possible to manufacture a substrate with high dimensional accuracy in which the outermost insulating layer 3, the first insulating layer 5, and the second insulating layer 7 are all prevented from firing shrinkage in the planar direction and are fired shrinkage in the thickness direction. .

  The glass-ceramic multilayer circuit board 1 produced in this way is excellent in dimensional accuracy in which the firing shrinkage in the planar direction is suppressed by integrally firing insulating layers having different shrinkage curves (behaviors) in firing. Since the glass ceramic multilayer circuit board 1 and the glass fluidity during firing of the insulating layer formed in the outermost layer can be kept high, the substrate thickness is reduced, that is, even when the insulating layer is reduced in thickness, The glass-ceramic multilayer circuit board 1 that stably exhibits high substrate strength that does not generate specific voids can be manufactured.

  First, a glass powder having an average particle size of 2.0 μm having the composition shown in Table 1 is prepared, weighed and mixed with a ceramic powder having a particle size of 2.0 μm according to Table 2, and an organic binder made of an acrylic resin is added to this mixture. After preparing a slurry by adding a plasticizer and an organic solvent, a thickness after firing when the outermost insulating layer, the first insulating layer, and the second insulating layer are integrally fired by the doctor blade method using this slurry. Is formed into a sheet shape as shown in Table 2, and the glass ceramic green sheet A that becomes the outermost insulating layer after firing, the glass ceramic green sheet B that becomes the first insulating layer after firing, the second after firing A glass ceramic green sheet C to be an insulating layer was produced.

  Note that the glass ceramic green sheets B and C were also used for the insulating layer that is not the first insulating layer and the insulating layer that is not the second insulating layer.

  Next, one glass ceramic green sheet B and one glass ceramic green sheet C were thermocompression bonded to produce composite green sheets D2 to D6. Further, one glass ceramic green sheet A, one glass ceramic green sheet B, and one glass ceramic green sheet C were heat-pressed so that the laminated state would be ABC, to produce a composite green sheet D1. Further, one glass ceramic green sheet A, two glass ceramic green sheets B, and one glass ceramic green sheet C were heat-pressed so that the laminated state would be BCBA, to produce a composite green sheet D7.

  Next, β quartz, ethyl cellulose as an organic binder, and 2-2-4-trimethyl-3-3-pentadiol monoisobutyrate as an organic solvent are added to Ag powder, and after stirring these, Ag powder and organic The paste was mixed with a three-roll mill until binder aggregates disappeared, and a paste for via-hole conductors and a conductor paste for wiring patterns were prepared.

  Next, a through hole serving as a via hole was formed in the glass ceramic green sheet composites D1 to D7 with a laser, and the through hole was filled with the conductive paste. Further, a conductive paste serving as a wiring pattern was formed on one main surface of each of the glass ceramic green sheet composites D1 to D6 and further on both main surfaces of D7 by screen printing.

Then, after aligning glass ceramic green sheet composites D1-D7 so that a lamination | stacking form might be ABCBCBCBCBCBCBCBA, it laminated | stacked and the laminated body 1 (not shown) was produced.

  This was treated to remove the binder at 400 ° C. in the atmosphere, and further fired at 910 ° C. in the atmosphere to produce a glass ceramic multilayer circuit board.

  1000 similar glass ceramic multilayer circuit boards were produced per sample.

  In addition, for each sample, an insulating substrate having the same layer configuration and the same glass ceramic material constituting each insulating layer and having no wiring pattern and via hole was produced.

  In a glass ceramic multilayer circuit board, for all 1000 substrates, the length between predetermined points before firing and after firing is measured, and the distance between points before firing is divided by the distance between points after firing. The shrinkage of the ceramic multilayer circuit board in the direction was calculated. The difference between the maximum shrinkage rate and the minimum shrinkage rate of 1000 substrates was evaluated as shrinkage variation.

  In addition, another 5 substrates are selected at random, voids opened on the front and back surfaces of the insulating layer are observed with an SEM, and a pixel having a pixel density equal to or higher than a predetermined threshold is defined as a void pixel using an image analyzer. The maximum opening diameter was calculated. The SEM observation area was 3 mm × 3 mm per substrate 1 surface, and this was repeated for the front and back surfaces and 5 substrates, and the largest of these was evaluated as the maximum aperture diameter. The results are shown in Table 3.

Moreover, the glass-ceramic material A, the glass-ceramic material B, and the glass-ceramic material C were respectively added with wax, and pressed at 1 × 10 ³ MPa to form a cylindrical green compact having a diameter of 10 mm and a height of 8 mm. The shrinkage start temperature of each material was evaluated by TMA (thermomechanical analysis) in the temperature range of room temperature to 1000 ° C. for this green compact. At this time, the temperature was set to 10 ° C./min in an air atmosphere. The results are shown in Table 2.

  Further, a plurality of glass ceramic green sheet sheets A, B and C are laminated so that the thickness after firing is the same as that of an insulating substrate having no wiring pattern and via holes, and subjected to binder removal treatment at 400 ° C. in the atmosphere. Then, it was baked at 910 ° C. in the atmosphere to produce a single material insulating substrate.

Next, 30 insulating substrates each having no wiring pattern and via holes and a single material insulating substrate were cut into a shape of width 4.0 mm × length 30 mm without being processed in the thickness direction. For the cut sample, the load cell descending speed of 5 mm / min. The 3-point bending strength was measured under the condition of a span of 20 mm. The Weibull coefficient was calculated from the obtained bending strength data. The results are shown in Table 3.

  As shown in Table 3, Sample No. which is the glass ceramic multilayer circuit board of the present invention. In 1 to 5, 9, 10, 19, and 20, the shrinkage rate was as small as 1.38% or less, the shrinkage variation was 0.1% or less, and the end protrusion height was 3 μm or less. Further, there was almost no difference between the bending strength of the insulating substrate and the bending strength of the first insulating layer alone, and the Weibull coefficient was 13 or more. From the above, it was found that the glass-ceramic multilayer circuit board of the present invention has high dimensional accuracy and stably has high substrate strength.

  On the other hand, the sample No. outside the range of the present invention in which the thickness of the outermost insulating layer is not in the range of 5 to 30 μm. 6, 7, 8 and the outermost insulating layer having an amorphous ratio smaller than that of the first insulating layer. In Nos. 6 to 8 and 11 to 18, the bending strength of the insulating substrate was significantly lower than that of the first insulating layer, or the shrinkage rate and shrinkage variation in the planar direction were large.

  In addition, sample No. outside the scope of the present invention. In Nos. 15 and 18, the decrease in the bending strength of the insulating substrate is small, but the thickness of the outermost insulating layer is large and it is difficult to reduce the height.

It is sectional drawing explaining the glass ceramic multilayer circuit board of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Glass ceramic multilayer circuit board 3 ... Outermost insulating layer 5 ... 1st insulating layer 7 ... 2nd insulating layer 9 ... Insulating substrate 11, 13 ... Wiring layer

Claims (4)

A glass ceramic multilayer circuit board made of a glass ceramic material, comprising an insulating substrate comprising a plurality of insulating layers having different firing shrinkage start temperatures, and wiring, wherein the insulating substrate is an outermost layer having a surface layer thickness of 5 to 30 μm An insulating layer; a first insulating layer in contact with the outermost insulating layer; and a second insulating layer in contact with the first insulating layer, wherein a firing shrinkage start temperature of the first insulating layer is the first insulating layer. 2 is lower than the firing shrinkage start temperature of the outer insulating layer and the outermost insulating layer, and the ratio of the amorphous phase in the first insulating layer is the amorphous phase in the outermost insulating layer and the second insulating layer. A glass-ceramic multilayer circuit board, wherein the thickness is smaller than the ratio, and the thickness of the outermost insulating layer is thinner than the thickness of the second insulating layer. The maximum opening diameter of the void opened on the surface of the outermost insulating layer is 10 μm or less, and the maximum opening diameter is 80% or less of the thickness of the outermost insulating layer. Glass ceramic multilayer circuit board. 3. The glass ceramic multilayer circuit board according to claim 1, wherein the glass ceramic material constituting the outermost insulating layer and the glass ceramic material constituting the second insulating layer are the same. 4. The glass ceramic multilayer circuit board according to claim 1, wherein a thickness of the second insulating layer is larger than a thickness of the first insulating layer. 5.

Images