JP2006156499A - Multiple-pattern substrate and glass ceramic board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem, wherein in a glass ceramic board having a ferrite layer formed inside the glass ceramic board and a coil embedded in the ferrite layer, moisture, etc. in the atmosphere infiltrates from the ferrite layer exposed on the side face and then the glass ceramic board absorbs the moisture, etc. <P>SOLUTION: The glass ceramic board comprises an insulation substrate 1 comprising a plurality of glass ceramic insulation layers 6 formed stacked of glass or a filler, the ferrite layer 2 of the same size as that of the glass ceramic insulation layers 6 which is formed in an inner layer of the glass substrate 1, and a conductor 3 for a coil embedded inside the ferrite layer 2. Dividing grooves 7 reach the ferrite layer 2. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a glass ceramic substrate having a ferrite layer in which a coil conductor is embedded in an insulating base made of a glass ceramic sintered body.

  Conventionally, a large number of electronic devices are incorporated in electronic devices such as mobile communication devices such as mobile phones. Such communication devices such as mobile phones have been rapidly reduced in size in recent years, and various electronic devices mounted thereon are required to be reduced in size and thickness. For example, an LC filter having a configuration in which a coil is built in a glass ceramic substrate is known. In the case of this LC filter, it has the advantage that it can be reduced in size and thickness by incorporating the coil of the chip component in the inside of the glass ceramic substrate. Among them, a coil having a large inductance exceeding 100 nH is relatively large as a chip component, and incorporating this in a glass ceramic substrate has an advantage that the effect of miniaturization and thinning is great.

  However, in a glass ceramic substrate with a built-in coil, the coil is formed in a non-magnetic glass ceramic substrate. Therefore, in order to incorporate a coil capable of obtaining a relatively large inductance of about 100 nH, the number of turns of the coil is increased. Therefore, it is necessary to secure a corresponding coil area, and it has been difficult to effectively reduce the size and thickness.

  Therefore, in recent years, a ferrite layer having ferromagnetism is formed inside a glass ceramic substrate, and the coil is embedded in this ferrite layer, so that a coil exceeding 100 nH can be built in without increasing the number of turns of the coil, thereby increasing the surface. Simplification of the mounting process and downsizing of the glass ceramic substrate have been attempted.

  On the other hand, such a glass-ceramic substrate has an extremely small size of several mm square, facilitates handling of the glass-ceramic substrate, and further efficiently manufactures the glass-ceramic substrate and the electronic device. In addition, it is manufactured in the form of a so-called multiple substrate, in which a plurality of wiring substrates are obtained simultaneously from a single large-area mother substrate.

  In such a multiple substrate, dividing grooves are formed vertically and horizontally on at least one main surface of a substantially flat mother board, and the mother board is divided into a plurality of wiring boards by dividing grooves. Individual wiring boards can be obtained by bending the mother board along the board.

In such a glass ceramic substrate, the ferrite layer and the glass ceramic insulating layer are simultaneously fired in order to firmly bond the ferrite layer and the glass ceramic insulating layer by diffusing the glass of the glass ceramic insulating layer into the ferrite layer. It is done.
JP-A-6-20839 JP-A-6-21264

  However, when the ferrite layer and the glass ceramic insulating layer of the glass ceramic substrate are co-fired, the ferrite layer is bound to the glass of the glass ceramic substrate and the ferrite layer is constrained and contracted by the glass of the glass ceramic substrate. The ferrite layer inside the glass ceramic substrate is hindered and roughened due to insufficient sintering, whereas the end of the ferrite layer exposed on the side surface of the glass ceramic substrate is insulated with glass ceramic insulation. Since there was no restraint by the layers, it was in a state of being fully sintered. The sintered state of this ferrite layer causes the following problems.

  That is, in the case of a plurality of glass ceramic substrates, since the glass ceramic mother substrate is fired and divided into individual pieces, the individual glass ceramic substrates are roughened due to insufficient sintering of the ferrite layer. Is exposed to the side surface, and moisture in the atmosphere enters from this portion, which causes a problem that water absorption occurs in the glass ceramic substrate. When water absorption occurs in the glass ceramic substrate, an electrical characteristic failure such as a short circuit of the wiring conductor formed in the inner layer of the glass ceramic substrate is induced, and the electrical reliability of the glass ceramic substrate is lowered.

On the other hand, in the conventional glass ceramic substrate in which a ferrite layer is formed inside the glass ceramic substrate as described above, and a coil is embedded in this ferrite layer, the inner ferrite layer can be formed only with a minute volume or low density, There is also a variation in coil inductance between glass ceramic substrates produced in the same manner, and there is a problem that it is difficult to stably obtain a glass ceramic substrate having sufficient coil characteristics using a ferrite layer. It was. For example, it was not possible to obtain a glass ceramic substrate having a sintered density of 5.0 g / cm ³ or higher at a firing temperature of 800 to 1000 ° C. and a ferrite layer having a permeability of 100 or higher in a frequency band of 1 KHz to 10 MHz. These disadvantages are due to the following reasons.

That is, in the conventional configuration, in order to fire a ferrite layer having a firing temperature exceeding 1000 ° C. at 800 ° C. to 1000 ° C. which is the firing temperature of the glass ceramic substrate, sintering of glass powder, SiO ₂ , Al ₂ O ₃ or the like. Auxiliary had to be added. In general, the magnetic properties of magnetic materials such as ferrite are expressed using magnetic permeability (μ) as an index. If the magnetic permeability is high, the inductance of the coil increases, but if there is a nonmagnetic portion in the magnetic material, the nonmagnetic portion The magnetic permeability decreases in proportion to the cube of the volume. Therefore, when glass powder or sintering aid, which is a non-magnetic material, is added to the ferrite layer, these form a non-magnetic region in the ferrite layer, reducing the ferrite density in the ferrite layer, and increasing the permeability. There was a problem that became low.

  On the other hand, when the ferrite layer and the glass ceramic insulating layer are fired simultaneously, the thermal expansion coefficient of the ferrite layer and the thermal expansion coefficient of the glass ceramic insulating layer are greatly different. There is also a problem that the magnetic permeability of the ferrite layer is lowered and it is difficult to obtain a desired magnetic permeability.

  In addition, if the thickness of the ferrite layer is increased in order to obtain sufficient inductance, the fired ferrite layer is easily peeled off due to the stress generated due to the difference in thermal expansion coefficient between the glass ceramic substrate and the ferrite layer. There was also a problem.

  The present invention has been made in view of the above-described problems, and an object thereof is to provide a multi-chip substrate and a glass ceramic substrate that are excellent in productivity and reliability.

  The multi-cavity substrate of the present invention is a multi-cavity substrate in which a dividing groove is provided along the boundary between adjacent substrate regions on the main surface of a mother substrate in which rectangular substrate regions are arranged in a matrix. The mother board is formed by adhering a glass ceramic insulating layer on both main surfaces of a ferrite layer in which a coil conductor is embedded, and is formed to a depth at which the dividing groove reaches the ferrite layer. It is characterized by being.

  The glass ceramic substrate of the present invention is a glass ceramic substrate in which a glass ceramic insulating layer is deposited on both main surfaces of a ferrite layer in which a coil conductor is embedded, and the void ratio of the ferrite layer is an outer peripheral region. It is characterized by being higher in the central area than

Further, in the glass ceramic substrate of the present invention, the ferrite layer contains Fe ₂ O ₃ in an amount of 63 to 73% by mass, CuO in an amount of 5 to 10% by mass, NiO in an amount of 5 to 12% by mass, and ZnO in an amount of 10 to 23% by mass. It is characterized by doing.

  Furthermore, in the glass ceramic substrate of the present invention, the glass ceramic insulating layer and the ferrite layer contain the same component ferrite as the glass and the ferrite layer, and the thermal expansion coefficient of the glass ceramic insulating layer and the ferrite It is characterized by being bonded via an intervening layer having a thermal expansion coefficient between the layers.

  Furthermore, in the glass ceramic substrate of the present invention, the glass ceramic insulating layer and the ferrite layer are made of at least one metal selected from the group consisting of Cu, Ag, Au, Pt, Ag—Pd alloy, and Ag—Pt alloy, and glass. It joins through the intervening layer which consists of a sintered metal containing this.

  Furthermore, in the glass ceramic substrate of the present invention, the glass ceramic insulating layer and the ferrite layer are joined via an intervening layer, and the intervening layer contains the same ferrite as the glass and the ferrite layer. An insulating layer having a thermal expansion coefficient between the thermal expansion coefficient of the glass ceramic insulating layer and the thermal expansion coefficient of the ferrite layer, a Cu, Ag, Au, Pt, Ag-Pd alloy, and an Ag-Pt alloy. It is characterized by being formed by laminating a sintered metal layer containing at least one kind of metal and glass.

  Furthermore, in the glass ceramic substrate of the present invention, the glass ceramic insulating layer and the ferrite layer are bonded via an intervening layer, and the intervening layer contains the same ferrite as the glass and the ferrite layer. An insulating layer having a thermal expansion coefficient between the thermal expansion coefficient of the glass ceramic insulating layer and the thermal expansion coefficient of the ferrite layer, a Cu, Ag, Au, Pt, Ag-Pd alloy, and an Ag-Pt alloy. It is characterized by being formed by juxtaposing a sintered metal layer containing at least one kind of metal and glass.

  According to the multi-cavity substrate of the present invention, since the dividing groove reaches the ferrite layer, the glass-ceramic insulating layer and the ferrite layer are blocked from being bonded by the glass at the dividing groove portion. The layer can be sufficiently sintered without being constrained by the glass ceramic insulating layer. Therefore, even after the glass ceramic mother substrate is divided into individual pieces along the dividing groove, the outer peripheral area of each glass ceramic substrate is sufficiently sintered. It is possible to prevent moisture and the like from entering.

  Further, according to the glass ceramic substrate of the present invention, the ferrite layer has a higher void ratio in the central region than in the outer peripheral region, and the magnetic permeability in the central region of the ferrite layer is lower than in the outer peripheral region. As a result, the leakage magnetic flux from the central portion of the substrate is reduced, so that the influence on the mounted components such as the IC to be mounted can be reduced.

Furthermore, according to the glass-ceramic substrate of the present invention, the ferrite layer, the _Fe 2 _{O 3 63~73} wt%, a CuO 5 to 10 wt%, 5-12 wt% of NiO, the ZnO 10 to 23 wt% Therefore, it is possible to form a ferrite layer having the same size as the glass ceramic insulating layer by using NiCuZn ferrite in which CuZn ferrite that can be sintered at a low temperature is combined with NiZn ferrite having excellent high frequency band characteristics. . As a result, the ferrite layer can be fired simultaneously with the glass ceramic substrate without adding a glass powder or a sintering aid such as SiO ₂ or Al ₂ O ₃ , and high permeability can be obtained in a high frequency band. In addition, a glass-ceramic substrate with a built-in coil having high inductance can be obtained.

  Furthermore, according to the glass ceramic substrate of the present invention, the glass ceramic insulating layer and the ferrite layer are joined via an intervening layer, and the intervening layer is formed by containing the same component ferrite as the glass and the ferrite layer. And an insulating layer having a thermal expansion coefficient between the thermal expansion coefficient of the glass ceramic insulating layer and the thermal expansion coefficient of the ferrite layer, Cu, Ag, Au, Pt, Ag—Pd alloy, and Ag—Pt alloy By forming the sintered metal layer containing at least one kind of metal and glass, the stress caused by the difference in thermal expansion between the ferrite layer and the glass ceramic insulating layer can be expressed as the thermal expansion coefficient of the glass ceramic insulating layer and the ferrite. It can be relaxed with an insulating layer having a thermal expansion coefficient that is intermediate between the thermal expansion coefficients of the layers. A write layer and the glass ceramic insulating layer can be firmly bonded.

  Furthermore, according to the glass ceramic substrate of the present invention, the glass ceramic insulating layer and the ferrite layer are joined via the intervening layer, and the intervening layer is bonded to the Cu, Ag, Au, Pt, Ag—Pd alloy, and Ag—. By forming the sintered metal layer containing at least one kind of metal of Pt alloy and glass, the stress caused by the difference in thermal expansion coefficient between the ferrite layer and the glass ceramic insulating layer is suppressed. Can be relaxed by plastic deformation, and a decrease in magnetic permeability due to magnetostriction can be suppressed, and the ferrite layer and the glass ceramic insulating layer can be firmly bonded.

  Still further, according to the glass ceramic substrate of the present invention, the intervening layer contains the same components as the glass and ferrite layer and has a thermal expansion coefficient between the thermal expansion coefficient of the glass ceramic insulating layer and the thermal expansion coefficient of the ferrite layer. And a sintered metal layer containing at least one metal of Cu, Ag, Au, Pt, Ag—Pd alloy and Ag—Pt alloy and glass is laminated and formed. Since the action of the insulating layer and the action of the sintered metal layer work synergistically, the stress caused by the difference in thermal expansion between the ferrite layer and the glass ceramic insulating layer can be more effectively relaxed. As a result, a decrease in magnetic permeability due to magnetostriction can be further effectively suppressed, and the bonding between the ferrite layer and the glass ceramic insulating layer can be further strongly bonded.

  Furthermore, according to the glass ceramic substrate of the present invention, the intervening layer contains the same components as the glass and ferrite layer, and the thermal expansion coefficient between the thermal expansion coefficient of the glass ceramic insulating layer and the thermal expansion coefficient of the ferrite layer. And a sintered metal layer containing glass and at least one of Cu, Ag, Au, Pt, Ag—Pd alloy, and Ag—Pt alloy. Thus, the action of the insulating layer and the action of the sintered metal layer work in the same plane, so that the stress caused by the difference in thermal expansion between the ferrite layer and the glass ceramic insulating layer can be more effectively alleviated. it can. As a result, a decrease in magnetic permeability due to magnetostriction can be further effectively suppressed, and the bonding between the ferrite layer and the glass ceramic insulating layer can be further strongly bonded.

  The present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 is a cross-sectional view showing an example of an embodiment of a multiple substrate according to the present invention, wherein 1 is an insulating base composed of a plurality of glass ceramic insulating layers 6, 2 is a ferrite layer, and 3 is a wiring including a coil conductor. Conductor, 4 is an insulating layer, 5 is a sintered metal layer, 6 is a glass ceramic insulating layer, and 7 is a dividing groove.

  The insulating substrate 1 of the multiple substrate shown in the figure is configured by laminating a plurality of glass ceramic insulating layers 6, and the ferrite layer 2 in which the wiring conductor 3 is embedded is formed of the insulating layer 4, the sintered layer 4. It is formed through the bonded metal layer 5.

  The insulating substrate 1 is made of a glass ceramic green sheet to be a glass ceramic insulating layer 6 and a ferrite green sheet to be a ferrite layer 2, and a conductive paste to be a wiring conductor 3 and an insulating layer to the glass ceramic green sheet and the ferrite green sheet. After the insulating paste to be 4 and the metal paste to be the sintered metal layer 5 are printed, a plurality of these glass ceramic green sheets and ferrite green sheets are laminated, and 800 to 1000 ° C. in air or in a humidified nitrogen atmosphere. It is made by firing at a temperature of

  The glass ceramic insulating layer 6 is obtained by first mixing glass powder and filler powder (ceramic powder), and further mixing an organic binder, plasticizer, organic solvent, etc. to obtain a slurry, from which a doctor blade method, a rolling method, a calender roll method, etc. Thus, a glass ceramic green sheet to be the glass ceramic insulating layer 6 is manufactured, and the ferrite layer 2 is sandwiched between a plurality of glass ceramic green sheets.

Examples of the glass powder include SiO ₂ —B ₂ O ₃ , SiO ₂ —B ₂ O ₃ —Al ₂ O ₃ , SiO ₂ —B ₂ O ₃ —Al ₂ O ₃ —MO (where M is Ca , Sr, Mg, Ba or Zn), SiO ₂ —Al ₂ O ₃ —M ¹ O—M ² O system (wherein M ¹ and M ² are the same or different, Ca, Sr, Mg, Ba or Zn) _{shown), SiO 2 -B 2 O 3} -Al 2 O 3 -M 1 O-M 2 O system (where, ^{M 1} and ^{M 2} are the same as _{above), SiO 2 -B 2 O 3} -M ³ ₂ O system (where M ³ represents Li, Na or K), SiO ₂ —B ₂ O ₃ —Al ₂ O ₃ —M ³ ₂ O system (where M ³ is the same as above), Pb glass or Bi glass can be used.

Examples of the filler powder include Al ₂ O ₃ , SiO ₂ , a composite oxide of ZrO ₂ and an alkaline earth metal oxide, a composite oxide of TiO ₂ and an alkaline earth metal oxide, and Al ₂ O. A composite oxide (for example, spinel, mullite, cordierite) containing at least one selected from ₃ and SiO ₂ can be used.

  The wiring conductor 3 is formed on the surface and inside of the insulating substrate 1 and inside the ferrite layer 2, and is prepared by kneading a suitable organic binder and solvent into metal powder such as Cu, Ag, Au, and Ag alloy. The conductive paste is applied to the glass ceramic green sheet surface and the ferrite green sheet surface by a screen printing method, a gravure printing method, or the like, and fired simultaneously with the glass ceramic green sheet and the ferrite green sheet.

  The insulating layer 4 as an intervening layer is formed between the ferrite layer 2 covering the upper and lower surfaces of the wiring conductor 3 and the glass ceramic insulating layer 6, and the ferrite powder contained in the glass powder and the ferrite layer 2 An insulating paste prepared by kneading an appropriate organic binder and solvent is blended so that the thermal expansion coefficient is between the thermal expansion coefficient of the glass ceramic insulating layer 6 and the thermal expansion coefficient of the ferrite layer 2. It is formed by applying at a position where the ferrite layer 2 on the glass ceramic green sheet is placed by a printing method, a gravure printing method or the like, and firing at the same time as the glass ceramic green sheet.

In addition, the ferrite powder of the insulating layer 4 is the same as the ferrite powder of the ferrite layer 2. As a sintered body, Fe ₂ O ₃ is 63 to 73 mass%, CuO is 5 to 10 mass%, and NiO is 5 to 12 mass. %, Ferrite containing 10 to 23% by mass of ZnO as a main component can be used.

The glass powder of the insulating layer 4 may be the same as the glass ceramic of the glass ceramic insulating layer 6, for example, _SiO 2 _-B 2 _{O 3 based, SiO 2 -B 2 O 3 -Al} 2 O 3 System, SiO ₂ —B ₂ O ₃ —Al ₂ O ₃ —MO system (where M represents Ca, Sr, Mg, Ba or Zn), SiO ₂ —Al ₂ O ₃ —M ¹ O—M ² O System (provided that M ¹ and M ² are the same or different and represent Ca, Sr, Mg, Ba or Zn), SiO ₂ —B ₂ O ₃ —Al ₂ O ₃ —M ¹ O—M ² O system (provided that , M ¹ and M ² are the same as described above), SiO ₂ —B ₂ O ₃ —M ³ ₂ O system (where M ³ represents Li, Na or K), SiO ₂ —B ₂ O ₃ — Al ₂ O ₃ -M ³ ₂ O system (where M ³ is the same as above) Pb glass, Bi glass, etc. can be used.

  The sintered metal layer 5 as an intervening layer is formed between the ferrite layer 2 covering the upper and lower surfaces of the wiring conductor 3 and the glass ceramic insulating layer 6, and includes Cu, Ag, Au, Pt, Ag—Pd alloy and A metal paste prepared by blending a glass powder with a metal powder of at least one metal of an Ag-Pt alloy and kneading an appropriate organic binder and solvent is obtained by a conventionally known screen printing method or gravure printing method. It is formed by applying the ferrite layer 2 on the glass ceramic green sheet at a position where it is placed and firing it at the same time as the glass ceramic green sheet.

The glass powder contained in the sintered metal layer 5 may be the same as the glass ceramic of the glass ceramic insulating layer 6, for example, _SiO 2 _-B 2 _{O 3 based,} SiO 2 _-B 2 _{O 3} - Al ₂ O ₃ system, SiO ₂ —B ₂ O ₃ —Al ₂ O ₃ —MO system (where M represents Ca, Sr, Mg, Ba or Zn), SiO ₂ —Al ₂ O ₃ —M ¹ O -M ² O system (where, ^{M 1} and ^{M 2} indicate Ca, Sr, Mg, Ba, or Zn same or _{different), SiO 2 -B 2 O 3} -Al 2 O 3 -M 1 O-M 2 O system (provided that M ¹ and M ² are the same as above), SiO ₂ —B ₂ O ₃ —M ³ ₂ O system (provided that M ³ represents Li, Na or K), SiO ₂ —B ₂ O ₃ —Al ₂ O ₃ —M ³ ₂ O system (where M ³ is Pb glass, Bi glass and the like can be used.

  The sintered metal layer 5 may have the same composition as the wiring conductor 3, and a part of the wiring conductor 3 may be used as the sintered metal layer 5.

  When the insulating layer 4 is formed by combining the insulating layer 4 and the sintered metal layer 5, they are arranged side by side in the same layer (interlayer) between the glass ceramic insulating layer 6 and the ferrite layer 2 as shown in FIG. There are a configuration in which the glass ceramic insulating layer 6 and the ferrite layer 2 are laminated and a configuration in which these configurations are combined. In each of these configurations, the insulating paste and the metal paste produced by the above method are separately applied to the position where the ferrite layer 2 on the glass ceramic green sheet is formed by a conventionally known screen printing method or gravure printing method. And is fired simultaneously with the glass ceramic green sheet.

  When the intervening layer combining the insulating layer 4 and the sintered metal layer 5 is arranged side by side in the same layer between the glass ceramic insulating layer 6 and the ferrite layer 2, between the glass ceramic insulating layer 6 and the ferrite layer 2, The wiring conductor 3 can be formed using the insulating layer 4 that is an insulator and the sintered metal layer 5 that is a conductor. When the intervening layer formed by laminating the insulating layer 4 and the sintered metal layer 5 is formed between the glass ceramic insulating layer 6 and the ferrite layer 2, the stress relaxation effect of the insulating layer 4 and the sintered metal layer 5 is more effective. It gets even higher. Further, an intervening layer obtained by combining a configuration in which the insulating layer 4 and the sintered metal layer 5 are arranged in the same layer and a configuration in which the insulating layer 4 and the sintered metal layer 5 are laminated is combined with the glass ceramic insulating layer 6. When formed between the ferrite layers 2, the effects of the two configurations can be obtained together.

The ferrite layer 2 is formed together with the wiring conductor 3 on the inner layer of the insulating base 1 so as to cover the upper and lower surfaces of the wiring conductor 3. To allow the firing at a low temperature, and to obtain a sufficiently high magnetic permeability in a high frequency band, a ferrite layer _2, Fe 2 O 3 63~73 wt%, CuO5～10 wt%, NiO5～12 wt%, ZnO10 It is important to form the film containing ˜23 mass%.

Fe ₂ O ₃ is a basic component of ferrite. If the main component of the ferrite is a solid solution having an inverted spinel structure represented as X—Fe ₂ O ₄ (X is Cu, Ni, Zn, etc.), 63 to 73 Must constitute mass%. When the content of Fe ₂ O ₃ is less than 63% by mass, sufficient magnetic permeability cannot be obtained, and when the content of Fe ₂ O ₃ exceeds 73% by mass, the mechanical strength decreases due to a decrease in sintered density. There is a risk of inviting.

CuO must constitute 5 to 10% by mass of the main component of ferrite. This is because CuO greatly contributes to lowering the sintering temperature, and CuO uses the effect of promoting sintering by forming a liquid layer at a low temperature, so that the firing temperature of glass ceramics is not impaired without damaging the magnetic properties. It is for baking at 800-1000 degreeC which is. When the content of CuO is less than 5% by mass of the main component of ferrite, the sintering density becomes insufficient and the mechanical strength becomes insufficient when firing is performed in the low temperature range targeted by the present invention. If the content exceeds 10% by mass of the main component of ferrite, the proportion of CuFe ₂ O _{4 having} low magnetic properties increases, so that the magnetic properties may be impaired.

NiO is contained in order to ensure the magnetic permeability of the ferrite in the high frequency range. NiFe ₂ O ₄ does not cause the attenuation of the magnetic permeability due to resonance up to the high frequency range and can maintain the magnetic permeability in the high frequency range at a relatively high value. However, since the initial permeability is low, When the content is less than 5% by mass, the magnetic permeability in a high frequency region of 10 MHz or more is reduced, and when the content of NiO exceeds 12% by mass, the ratio of NiFe ₂ O ₄ increases, so that the initial permeability is increased. descend. Therefore, it is important to set the content of the main component of ferrite to 5 to 12% by mass.

  ZnO is an important element for improving the permeability of ferrite, and if it is less than 10% by mass of the main component of ferrite, it causes a problem of insufficient magnetic properties. Deteriorate.

  The ferrite layer 2 is formed by first mixing a ferrite powder with an appropriate organic binder, plasticizer, organic solvent, etc. to obtain a slurry, and then producing a ferrite green sheet by a doctor blade method, a rolling method, a calender roll method, or the like. . Next, the ferrite green sheet is cut into the same shape as the glass ceramic green sheet in plan view so as to cover the predetermined wiring conductor 3, and the wiring conductor 3 is interposed in the glass ceramic green sheet laminate. The conductor pattern is arranged and laminated so as to cover the upper and lower surfaces of the wiring conductor 3.

  At this time, in order to effectively increase the inductance of the coil conductor, it is preferable to completely cover the upper and lower surfaces of the wiring conductor 3 with the ferrite layer 2. Therefore, in order to form such a wiring conductor 3 and a ferrite layer 2, a ferrite green sheet to be the lower ferrite layer 2 on the surface of a predetermined glass ceramic green sheet, a pattern of a conductor paste to be the wiring conductor 3, Each layer may be arranged and laminated in the order of the ferrite green sheet to be the upper ferrite layer 2.

  As the ferrite powder used to form the ferrite green sheet to be the ferrite layer 2, calcined ferrite powder is used, and the average particle size thereof is uniform in the range of 0.1 μm to 0.9 μm, for example. It is preferable to use grains having a nearly spherical shape. Here, when the average particle diameter of the ferrite powder is smaller than 0.1 μm, it becomes difficult to uniformly disperse the ferrite powder in the production of the ferrite green sheet. When the average particle diameter of the ferrite powder exceeds 0.9 μm, The sintering temperature is increased, which has an undesirable effect on productivity. In addition, if the particle size is uniform and close to a sphere, a uniform sintered state can be obtained. However, when ferrite powder has a small particle size, the growth of crystal grains is reduced only in that portion. The magnetic permeability of the ferrite layer 2 obtained after sintering becomes difficult to stabilize.

  Then, the dividing groove 7 is formed in the dividing portion of the insulating base 1 to a depth reaching the ferrite layer. This is because if the dividing groove 7 does not reach the ferrite layer 2, the ferrite layer 2 is constrained by the glass ceramic insulating layer 6 by bonding the glass ceramic insulating layer 6 and the ferrite layer 2 even in the dividing groove portion. This is because the shrinkage is hindered and the ferrite layer 2 is not sufficiently sintered and roughened.

  There is no restriction | limiting in particular as a shape of the front-end | tip of the division groove | channel 7, For example, it forms in the cross-sectional V shape and the cross-sectional U shape. The V-shaped groove is desirable when the insulating substrate 1 is divided into individual pieces, and stress is concentrated in the divided grooves, so that the V-shaped groove is easy to break. Since the U-shaped groove has a wider width for blocking the bonding between the glass ceramic insulating base 6 and the ferrite layer 2, the ferrite layer 2 is sintered without being constrained by the glass ceramic insulating layer 6 in a wide region. Thus, it is more effective to prevent moisture in the atmosphere from entering from the ferrite layer 2 exposed on the side surface of the substrate.

  The method for forming the dividing groove 7 is not particularly limited as long as it is a method capable of forming the groove in the glass ceramic green sheet laminate. For example, a method of forming the dividing groove by press molding, a method of forming the dividing groove by a rotary blade, or the like. Should be used.

  Further, in the glass ceramic substrate described above, the void ratio of the ferrite layer 2 is higher in the central area than in the outer peripheral area, the void ratio in the outer peripheral area is 0 to 5%, and the void ratio in the central area is in the range of 5 to 15%. It is preferable to set to. This is because if the void ratio exceeds 5% in the outer peripheral area, moisture in the atmosphere may enter from this portion and water absorption may occur in the glass ceramic substrate, and the void ratio is less than 5% in the central area. In this case, the difference in the void ratio between the central area and the outer peripheral area is reduced, so that the difference in magnetic permeability is also reduced. As a result, the effect of suppressing the leakage magnetic flux is reduced. If the void ratio in the central area exceeds 15%, the mechanical strength of the substrate itself may be insufficient. Therefore, the void ratio in the central area is preferably set to 15% or less.

  The void ratio is measured by mirror-polishing the insulating substrate 1 using a surface grinder, and taking a photograph of the cross section of the ferrite layer 2 at a magnification of 1000 to 5000 using a scanning electron microscope or the like. It can be obtained by binarizing into ferrite and void by treatment and measuring the area ratio.

  And in the manufacturing method of the glass ceramic substrate of this form, first, the ferrite layer 2 and the wiring conductor 3 are laminated | stacked with several sheets of a glass ceramic green sheet in the above-mentioned way, and a glass ceramic green sheet laminated body is produced. Next, the dividing grooves 7 are formed on the glass ceramic green sheet laminate in the manner described above. And after removing an organic component from this glass ceramic green sheet laminated body, it bakes. The organic component is removed by heating the glass ceramic green sheet laminate in a temperature range of 100 to 800 ° C. while applying a load to the glass ceramic green sheet laminate to decompose and volatilize the organic component. Moreover, although a calcination temperature changes with glass ceramic compositions, it is in the range of about 800-1000 degreeC normally. Firing is usually performed in the air, but when Cu is used as the conductor material of the wiring conductor 3, organic components are removed in a humidified nitrogen atmosphere at 100 to 700 ° C., and then the firing is performed in a nitrogen atmosphere.

  Further, at the time of removing the organic component and at the time of firing, in order to prevent the glass ceramic green sheet laminate from warping, it is preferable to apply a load by placing a weight on the upper surface thereof. The load due to such weight is suitably about 50 Pa to 1 MPa. When the load is less than 50 Pa, the action of suppressing the warp of the glass ceramic green sheet laminate is not sufficient. In addition, when the load exceeds 1 MPa, the “weight” to be used increases, so that it cannot enter the firing furnace, or even if it enters the firing furnace, the “weight” is large and the heat capacity is insufficient and the firing is performed. There is a risk of problems such as being unable to do so.

  Such “weight” includes a heat-resistant porous material that does not deform or melt during firing of the glass-ceramic substrate, resulting in non-uniform loads or hindering volatilization of decomposed organic components. A quality one is suitable. Specifically, a refractory material such as ceramics or a high melting point metal can be used. Further, a porous “weight” may be placed on the upper surface of the glass ceramic green sheet laminate, and a non-porous “weight” may be placed thereon.

  In Example 1, a test piece provided with a dividing groove reaching the ferrite layer 2 as shown in FIG. 2 was prepared and divided into solid pieces, and then the water absorption rate was measured. In FIG. 2, the same parts as in FIG. 1 are denoted by the same reference numerals, 1 is an insulating substrate, 2 is a ferrite layer, 3 is a wiring conductor, 6 is a glass ceramic insulating layer, and 7 is a dividing groove. . The water absorption is measured by first measuring the weight of the solid piece, then immersing the solid piece in water, leaving it in a vacuum for 1 hour, measuring the weight of the subsequent solid piece, and calculating the weight difference before and after immersion in water. The percentage difference is obtained by dividing the weight difference by the initial solid piece weight. When the water absorption is 0.1% or more, it is indicated by x, and when it is less than 0.1%, it is indicated by ◯.

  The test piece was produced as follows.

First, as a glass ceramic component, SiO ₂ —Al ₂ O ₃ —MgO—B ₂ O ₃ —ZnO-based glass powder 60% by weight, CaZrO ₃ powder 20% by weight, SrTiO ₃ powder 17% by weight, and Al ₂ O ₃ powder 3 Using 100% by weight of this glass ceramic component, 12 parts by weight of an acrylic resin as an organic binder, 6 parts by weight of a phthalic plasticizer, and 30 parts by weight of toluene as a solvent are added. The mixture was made into a slurry, and a glass ceramic green sheet having a thickness of 300 μm was formed using the obtained slurry by employing a conventionally known doctor blade method.

Next, as a ferrite green sheet, first, 1000 g of each of the raw materials having the composition ratio shown in Material No. 1 in Table 2 was weighed, and 24 mm in a 7000 cm ³ ball mill using 4000 cm ³ pure water and zirconia grinding balls. After time preparation, the raw material powder was separated and dried, and calcined at 730 ° C. in a zirconia crucible. To this, 10% by weight of a butyral resin and 45% by weight of a high molecular weight alcohol as a diluent were added and mixed by a ball mill method to obtain a slurry. Using this slurry, a ferrite green sheet having a thickness of 100 μm was formed by a doctor blade method.

  The conductor paste for forming the wiring conductor 3 uses Ag powder having an average particle diameter of 2.5 to 3.5 μm, adds a predetermined amount of ethyl cellulose resin and terpineol, and has an appropriate viscosity by three rolls. Made by mixing.

  First, a conductor paste layer was applied to each pattern shape on a glass ceramic green sheet and a ferrite green sheet and dried. Then, two glass ceramic green sheets were superposed, and four ferrite green sheets were superposed on the glass ceramic green sheet. Further, two glass ceramic green sheets were superposed on the ferrite green sheet and pressed at a temperature of 55 ° C. and a pressure of 20 MPa to obtain a glass ceramic laminate.

  And the obtained glass-ceramic laminated body was cut | disconnected to the test piece of 80 mm size, and also the division groove | channel 7 which reaches a ferrite layer by a 10-mm space | interval was provided in the test piece.

  The obtained test piece was placed on an alumina ceramic setter, and a weight of the same component as that of the alumina ceramic setter was placed thereon and heated at 500 ° C. for 2 hours in the atmosphere while applying a load of about 0.5 MPa. After removing the organic components, the mixture was baked in the atmosphere at 900 ° C. for 2 hours.

  Table 1 shows the results of measuring the water absorption rate of the glass ceramic substrate of Example 1 thus obtained.

Comparative Example 1

A test piece for evaluation of Comparative Example 1 was produced in the same manner as in Example 1 except that the depth of the dividing groove 7 of Example 1 was set to 300 μm that did not reach the ferrite layer 2. Table 1 shows the results of measuring the water absorption rate of the obtained glass ceramic substrate.

  According to Table 1, in Example 1 where the depth of the dividing groove 7 reaches the ferrite layer 2, the water absorption is less than 0.1%, whereas the depth of the dividing groove 7 is up to the ferrite layer 2. In Comparative Example 1 which did not reach, the water absorption was 0.1% or more. This is because the split groove 7 reaches the ferrite layer 2 to block the bond between the ferrite layer 2 and the glass ceramic insulating layer 6.

  In Example 2, a test piece for evaluation of a ring shape having an outer diameter of 16 mm and an inner diameter of 8 mm as shown in FIG. 3 was prepared, and the magnetic permeability was measured. In FIG. 3, the same parts as those in FIG. 1 are denoted by the same reference numerals, 2 is a ferrite layer, and 6 is a glass ceramic insulating layer. The permeability was measured by an high frequency current voltage method using an impedance analyzer (product name “HP-4291A”; manufactured by Hewlett Packard).

  The test piece was produced as follows.

First, as a glass ceramic component, SiO ₂ —Al ₂ O ₃ —MgO—B ₂ O ₃ —ZnO-based glass powder 60% by weight, CaZrO ₃ powder 20% by weight, SrTiO ₃ powder 17% by weight, and Al ₂ O ₃ powder 3 Using 100% by weight of this glass ceramic component, 12 parts by weight of an acrylic resin as an organic binder, 6 parts by weight of a phthalic plasticizer, and 30 parts by weight of toluene as a solvent are added. The mixture was made into a slurry, and a glass ceramic green sheet having a thickness of 300 μm was formed using the obtained slurry by employing a conventionally known doctor blade method.

  Next, as a ferrite green sheet, calcined powder was prepared in the same manner as in Example 1 with the composition ratio shown in Table 2. To this, 10% by weight of a butyral resin and 45% by weight of a high molecular weight alcohol as a diluent were added and mixed by a ball mill method to obtain a slurry. Using this slurry, a ferrite green sheet having a thickness of 100 μm was formed by a doctor blade method.

  Then, a predetermined number of glass ceramic green sheets were superposed, and a predetermined number of ferrite green sheets were superposed on the glass ceramic green sheet. Further, a predetermined number of glass ceramic green sheets were superposed on the ferrite green sheet and pressure bonded at a temperature of 55 ° C. and a pressure of 20 MPa to obtain a glass ceramic laminate.

  The obtained glass-ceramic laminate is placed on an alumina ceramic setter, and a weight of the same component as the alumina ceramic setter is placed thereon, and a load of about 0.5 MPa is applied at 500 ° C. in the atmosphere for 2 hours. After removing the organic component by heating, it was baked at 900 ° C. for 2 hours in the air.

In the obtained glass ceramic substrate, although the ferrite layer 2 was formed on the entire inner layer, no warping or deformation was observed. The results of measuring the magnetic permeability of the glass ceramic substrate of Example 2 are shown in Table 2.

According to Table 2, those having the composition of the main component within the range defined by the present invention are excellent in the sintered density and magnetic permeability, and are the target ferrite characteristics. The sintered density is 5 g / cm ^3. As described above, it has a permeability of 100 or more at 1.0 MHz and 10.0 MHz.

  A test piece for evaluation with a ring shape having an outer diameter of 16 mm and an inner diameter of 8 mm was prepared by interposing the insulating layer 4 between the ferrite layer and the glass ceramic insulating layer of Example 2, and the magnetic permeability was measured.

The insulating paste for forming the insulating layer 4 is the same as the glass powder contained in the glass ceramic, and is contained in the ferrite green sheet, 30 mass% of SiO ₂ —Al ₂ O ₃ —MgO—B ₂ O ₃ —ZnO-based glass powder. 70% by mass of ferrite powder composed of ZnFe ₂ O ₄ , CuFe ₂ O ₄ , FeFe ₂ O ₄ , and NiFe ₂ O ₄ having the same average particle size as that of the calcined ferrite powder is 0.5 to 0.7 μm. A predetermined amount of ethylcellulose-based resin and terpineol were added and mixed to prepare an appropriate viscosity with three rolls.

  First, a predetermined number of glass ceramic green sheets were overlapped, and an insulating paste layer was applied over the entire surface and dried. Thereafter, a ferrite green sheet was superposed on the dried insulating paste layer, and further, the insulating paste layer was applied over the entire surface and dried. Thereafter, a predetermined number of glass ceramic green sheets were superposed on the dried insulating paste layer and pressure-bonded at a temperature of 55 ° C. and a pressure of 20 MPa to obtain a glass ceramic laminate.

  The obtained glass-ceramic laminate was placed on an alumina ceramic setter, and a weight of the same component as the alumina ceramic setter was placed thereon, and a load of about 0.5 MPa was applied at 500 ° C. in the atmosphere for 2 hours. After removing the organic component by heating, it was baked at 900 ° C. for 2 hours in the air.

  Table 3 shows the results of measuring the magnetic permeability of the glass ceramic substrate of Example 3 thus obtained.

Instead of the insulating layer 4 of Example 3, 80% by mass of Ag powder (average particle size 1.0 μm) and 20% by mass of SiO ₂ —Al ₂ O ₃ —MgO—B ₂ O ₃ —ZnO-based glass powder were used. A test piece for evaluation of Example 4 was produced in the same manner as Example 3 except that the sintered metal layer 5 was formed. The results of measuring the magnetic permeability of the obtained glass ceramic substrate are shown in Table 3 together with the results of Example 3.

In addition to the insulating layer 4 of Example 3, 80% by mass of Ag powder (average particle size 1.0 μm) and 20% by mass of SiO ₂ —Al ₂ O ₃ —MgO—B ₂ O ₃ —ZnO-based glass powder were used. A test piece for evaluation of Example 4 was produced in the same manner as Example 3 except that the sintered metal layer 5 was formed. The results of measuring the magnetic permeability of the obtained glass ceramic substrate are shown in Table 3 together with the results of Examples 3 and 4.

According to Table 3, the ferrite formed in the ferrite substrate had a sintered density of 5 g / cm ³ or more, which is the target characteristic, and a magnetic permeability of 100 or more at 1.0 MHz and 10.0 MHz.

  Further, the magnetic permeability of Examples 3 to 5 in which the insulating layer 4 and / or the sintered metal layer 5 were interposed between the ferrite layer and the glass ceramic insulating layer was higher than the magnetic permeability of Example 2. This is presumably because the magnetostriction acting on the ferrite layer 2 is reduced by relaxing the stress acting between the ferrite layer and the glass ceramic layer by the insulating layer 4 and / or the sintered metal layer 5.

  The present invention is not limited to the above-described embodiments and examples, and various modifications can be made without departing from the scope of the present invention. For example, although Ag is used for the wiring conductor 3 in the above-described embodiment, Cu, Au, Ag—Pd alloy, or the like may be used for the wiring conductor 3.

It is sectional drawing which shows an example of embodiment of the multi-cavity board | substrate of this invention. 1 is a cross-sectional view of a test piece according to the present invention used in Example 1. FIG. It is sectional drawing of the test piece concerning this invention used in Example 2. FIG.

Explanation of symbols

1: Insulating substrate 2: Ferrite layer 3: Wiring conductor 4: Insulating layer 5: Sintered metal layer 6: Glass ceramic insulating layer 7: Dividing groove

Claims (7)

A plurality of substrates obtained by providing a dividing groove along a boundary between adjacent substrate regions on a main surface of a mother substrate in which rectangular substrate regions are arranged in a matrix,
The mother board is formed by depositing a glass ceramic insulating layer on both main surfaces of a ferrite layer in which a coil conductor is embedded, and the dividing groove is formed to a depth that reaches the ferrite layer. A multi-layer substrate characterized by that. A glass ceramic substrate in which a glass ceramic insulating layer is deposited on both main surfaces of a ferrite layer in which a coil conductor is embedded, and the void ratio of the ferrite layer is higher in the central region than in the outer peripheral region. Glass ceramic substrate. The ferrite layer contains Fe ₂ O ₃ in an amount of 63 to 73% by mass, CuO in an amount of 5 to 10% by mass, NiO in an amount of 5 to 12% by mass, and ZnO in an amount of 10 to 23% by mass. The glass ceramic substrate as described. The glass ceramic insulating layer and the ferrite layer contain the same component ferrite as the glass and the ferrite layer, and the thermal expansion coefficient between the thermal expansion coefficient of the glass ceramic insulating layer and the thermal expansion coefficient of the ferrite layer The glass ceramic substrate according to claim 2 or 3, wherein the glass ceramic substrate is bonded via an intervening layer having a coefficient. The glass ceramic insulating layer and the ferrite layer include an intervening layer made of a sintered metal containing at least one metal of Cu, Ag, Au, Pt, an Ag—Pd alloy, and an Ag—Pt alloy and glass. The glass-ceramic substrate according to claim 2 or 3, wherein the glass-ceramic substrate is bonded via a via. The glass ceramic insulating layer and the ferrite layer are joined via an intervening layer, and the intervening layer contains ferrite having the same component as the glass and the ferrite layer, and the thermal expansion coefficient of the glass ceramic insulating layer And an insulating layer having a thermal expansion coefficient between that of the ferrite layer and at least one metal selected from the group consisting of Cu, Ag, Au, Pt, Ag—Pd alloy and Ag—Pt alloy, and glass. The glass ceramic substrate according to claim 2 or 3, wherein the glass ceramic substrate is formed by laminating a sintered metal layer containing bismuth. The glass ceramic insulating layer and the ferrite layer are joined via an intervening layer, and the intervening layer contains ferrite having the same component as the glass and the ferrite layer, and the thermal expansion coefficient of the glass ceramic insulating layer And an insulating layer having a thermal expansion coefficient between that of the ferrite layer and at least one metal selected from the group consisting of Cu, Ag, Au, Pt, Ag—Pd alloy and Ag—Pt alloy, and glass. The glass ceramic substrate according to claim 2, wherein the glass ceramic substrate is formed by juxtaposing a sintered metal layer containing bismuth.

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