JP2004156047A - Substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a substrate having high strengths, suitable for use in a high-frequency range, suitably used in applications utilizing magnetic properties and suitable for applications requiring heat resistance. <P>SOLUTION: This substrate is obtained by impregnating a slurry ferrite paste into a glass cloth, drying the impregnated cloth to obtain a prepreg, heat-pressing the prepreg with a copper foil to obtain a substrate and forming a coat of a ferrite paste on the surface of the copper foil of the substrate, wherein the slurry ferrite paste is obtained by kneading a ferrite powder and an epoxy resin with a solvent. <P>COPYRIGHT: (C)2004,JPO

Description

  The present invention relates to a substrate used for an electronic component or a circuit board, and is particularly suitable for use in a high frequency region (100 MHz or more), and suitable for use utilizing magnetic characteristics or magnetic shield. About.

  Conventionally, as a substrate material used for an electronic component or a circuit board, there is a material obtained by kneading a molding material by kneading ferrite powder and subjecting the molded plate to a treatment such as plating.For example, a liquid crystal polymer and ferrite are used. Some use a composite ferrite substrate made of a composite ferrite molding material as a component. In addition, there is a copper-clad laminate using a prepreg made of a glass cloth-containing epoxy resin or a phenol resin containing no ferrite powder.

  However, it is difficult to form a thin and large shape in the case where the above formed plate is subjected to a treatment such as plating. Further, in the copper-clad laminate containing no ferrite powder described above, since no magnetic material is present, a ferrite material is applied or bulk ferrite is attached to elements, components, and circuits using magnetic characteristics. There is a need. Further, it has no magnetic shield effect by itself, and is not suitable for use for the purpose of magnetic shield.

  On the other hand, Japanese Patent Application Laid-Open (JP-A) No. 58-158813 discloses "a laminate for electric use in which a laminate base material is impregnated with a laminate resin containing a metal oxide having both magnetic properties and electrical insulation properties". It has been disclosed. However, what is shown in the examples is a combination of a phenolic resin and kraft paper, which is disadvantageous in strength required for thinning and heat resistance. Further, the proportion of ferrite powder is less than 50% by weight of the whole, so that the magnetic properties required as a magnetic material may not be sufficiently obtained.

  Japanese Unexamined Patent Publication No. Sho 59-176035 discloses a fiber composite material which is composed of fiber layers which are arranged one above the other and are connected and aligned with each other by a base material composed of a resin and a curing agent, and absorb electromagnetic waves. A fibrous composite material in which a filler that absorbs radio waves is contained in each layer from outside to inside with a change in concentration is disclosed. However, as shown in the example, the distribution of the packing material has a concentration gradient, and it takes much time to prepare the prepreg.

  Further, Japanese Patent Application Laid-Open No. 2-120040 discloses a copper-clad laminate formed by laminating a prepreg obtained by impregnating and drying a thermosetting resin on a glass fiber woven fabric and then forming a copper foil by applying heat and pressure. There is disclosed a radio wave absorbing copper-clad laminate in which a radio wave absorbing material is mixed and dispersed in a curable resin to absorb electromagnetic noise of a specific frequency. However, what is shown in the examples uses PZT powder and is not suitable for use utilizing magnetic properties or use for magnetic shielding.

  First, the object of the present invention is to provide a prepreg containing ferrite, which is suitable for use in a high frequency region (100 MHz or more), and which is suitable for use utilizing magnetic characteristics or use for magnetic shielding. Also, without using a non-magnetic layer or adhesive, bonding with copper foil, patterning or multi-layering is possible, thinner strength can be improved, and structure improvement such as thinning is possible. An object of the present invention is to provide a prepreg, and to provide a substrate that is easy to manufacture, has excellent heat resistance, has high strength, and has improved high-frequency characteristics using such a prepreg.

The above object is achieved by the present invention described below.
(1) A glass cloth is impregnated with a paste obtained by kneading a ferrite powder and an epoxy resin in a solvent to form a slurry, and drying and drying the prepreg and copper foil to form a substrate obtained by heating and pressing. A substrate on which a ferrite paste coating film obtained by kneading a ferrite powder and an epoxy resin in a solvent is formed on a copper foil on the surface.
(2) A glass cloth is impregnated with a paste obtained by kneading a ferrite powder and an epoxy resin in a solvent to form a slurry, and drying is performed. A substrate in which a ferrite paste coating film obtained by kneading a ferrite powder and an epoxy resin in a solvent is formed on a copper foil on the surface of the substrate.
(3) A prepreg obtained by impregnating a glass cloth with a slurry obtained by kneading a ferrite powder and an epoxy resin in a solvent and forming a slurry, and a substrate obtained by molding the prepreg by heating and pressing; A substrate obtained by stacking a plurality of the prepregs and molding by heating and pressing, a substrate obtained by shaping the prepreg and the copper foil by heating and pressing, and heating and pressing the copper foil by stacking a plurality of the prepregs. Using a board selected from the boards obtained by molding, and kneading ferrite powder and epoxy resin in a solvent on a copper foil on the surface of the multilayered board obtained by heating and pressing and molding. Substrate on which the ferrite paste coating film is formed.
(4) The substrate according to any one of (1) to (3), wherein the ferrite paste for forming a coating film contains 50 to 80% by weight of a ferrite powder and 45 to 10% by weight of an epoxy resin.
(5) The substrate according to any one of (1) to (4), wherein the ferrite powder of the prepreg has a particle size of 0.01 to 50 μm.
(6) The content of the above-mentioned (1) to (5), wherein the content of the ferrite powder represented by the weight ratio of the amount of the ferrite powder to the total amount of the ferrite powder, the epoxy resin and the glass cloth of the prepreg is 50 to 80% by weight. Any substrate.
(7) The substrate according to any one of (1) to (6), wherein a mixing ratio of the epoxy resin and the glass cloth of the prepreg is 4/1 to 1/1 by weight of epoxy resin / glass cloth.
(8) The substrate according to any one of (1) to (7), wherein the prepreg uses a glass cloth having a thickness of 20 to 60 μm.
(9) The substrate according to any one of (1) to (8), which is used in a high frequency region of 100 MHz or more.

  According to the present invention, a prepreg suitable for use in a high frequency region of 100 MHz or more and suitable for use utilizing magnetic properties can be obtained. Further, it is possible to bond with a copper foil, pattern, or form a multilayer without using a nonmagnetic layer or an adhesive. Further, the strength can be improved with a thin wall. Further, using such a prepreg, a substrate having excellent heat resistance, high strength, and improved high-frequency characteristics can be obtained.

Hereinafter, the present invention will be described in detail.
The prepreg of the present invention is obtained by impregnating a glass cloth with a paste obtained by kneading a ferrite powder and an epoxy resin into a solvent to form a slurry, and drying the paste. With such a configuration, it is suitable for use in a high frequency region (100 MHz or more, particularly 100 MHz or more and 10 GHz or less), and since the content of ferrite powder can be increased, it can be used in applications utilizing magnetic characteristics or a magnetic shield. It is a prepreg suitable for use for the purpose, and has high strength. When a substrate is formed using such a prepreg, adhesion and patterning with a copper foil can be realized without using a nonmagnetic layer or an adhesive, and multilayering can be realized. Such patterning and multi-layering can be performed in the same process as a normal substrate manufacturing process, so that cost reduction and workability can be improved. The substrate thus obtained has high strength and improved high frequency characteristics. Further, by using an epoxy resin, it is possible to provide heat resistance particularly required for a substrate or an electronic component, and it is possible to satisfy reflow resistance and solder heat resistance at 350 ° C. for 3 seconds at the maximum.

  Japanese Patent Application Laid-Open No. 58-158813 discloses a prepreg containing a metal oxide having both magnetic properties and electrical insulation properties. This is a combination with kraft paper, and unlike the present invention, there is no specific disclosure about the combination of epoxy resin and glass cloth.

  JP-A-59-176035 discloses a fiber composite material in which a radio wave absorbing material is contained in a prepreg layer with a concentration gradient, which is clearly different from the present invention having no concentration gradient. Things.

  Further, Japanese Patent Application Laid-Open No. Hei 2-10040 discloses a copper-clad laminate using a prepreg containing a radio wave absorbing material, but a concrete example shown in the examples uses PZT powder. Unlike the present invention, there is no specific disclosure about a prepreg in which ferrite powder is mixed and dispersed.

Further, the present invention will be described.
The material of the ferrite powder used in the present invention is a Mn-Mg-Zn-based, Ni-Zn-based, Mn-Zn-based or the like, and preferably a Mn-Mg-Zn-based or Ni-Zn-based.

  The particle size of the ferrite powder is preferably from 0.01 to 50 μm, and the average particle size is preferably from 1 to 20 μm. With such a particle size, the dispersibility of the ferrite powder is improved, and the effect of the present invention is improved. On the other hand, when the particle size of the ferrite powder is large, it becomes difficult to form a fine pattern during patterning. Further, it is practically difficult to make the particle size too small, and the limit is about 0.01 μm.

  The particle size of the ferrite powder is preferably uniform, and if necessary, the particle size may be uniformed by sieving or the like.

  The magnetic permeability μ of the ferrite powder is preferably from 10 to 10,000. Further, it is preferable that the bulk insulating property is higher because the insulating property when the substrate is formed is improved.

  The epoxy resin used in the present invention is a novolak-type epoxy resin such as a bisphenol-type epoxy resin, a phenol novolak-type epoxy resin (EPN), a cresol novolak-type epoxy resin (ECN), and a polyfunctional glycidylamine resin. Phenol novolak epoxy resin (EPN), cresol novolak epoxy resin (ECN), polyfunctional glycidylamine resin and the like are preferable, and phenol novolak epoxy resin (EPN) and cresol novolak epoxy resin (ECN) are particularly preferable.

  Such an epoxy resin is liquid (including semi-solid) or solid at ordinary temperature (temperature of about 25 ° C.), and has a number average molecular weight (Mn) of about 300 to 10,000. The viscosity of a liquid is about 1,000 to 100,000 cps at a temperature of about 25 ° C., and the softening point of a solid is about 40 to 120 ° C.

Next, phenol novolak type epoxy resin (EPN) and cresol novolak type epoxy resin (ECN) which are preferably used in the present invention will be described.
These epoxy resins have particularly good heat resistance. More specifically, as an electronic component, reflow at a maximum temperature of 250 ° C. is performed about three times (including pretreatment: with water absorption), and solder dip is performed at 260 ° C. for 10 seconds or 350 ° C. for 3 seconds. Need to be Further, it is necessary for the substrate to perform reflow at a maximum temperature of 250 ° C. about three times (pretreatment: including water absorption) or to perform solder dip at 260 ° C. for 120 seconds. Further, the heat resistance in a long-term reliability test is required to be 125 to 150 ° C. These epoxy resins can sufficiently satisfy these required properties. Actually, the decomposition inflection point of the phenol novolak type epoxy resin is 370 to 400 ° C.

  The chemical structures of phenol novolak epoxy resin (EPN) and cresol novolak epoxy resin (ECN) are as shown below.

  Phenol novolak type epoxy resin (EPN) is a semi-solid or solid resin at normal temperature, and has a number average molecular weight (Mn) of about 400 to 1200. The viscosity of the semi-solid material is about 3000 to 100000 cps at a temperature of about 25 to 55 ° C, and the softening point of the solid material is about 50 to 90 ° C.

  Such a phenol novolak type epoxy resin (EPN) is commercially available, and includes, for example, trade names DEN431, DEN438, XD-7818, XD-7855, and DER331 (both manufactured by Dow Chemical Company).

  On the other hand, cresol novolak type epoxy resin (ECN) is a solid resin having a number average molecular weight (Mn) of about 400 to 1200 and a softening point of about 60 to 120 ° C.

These cresol novolak epoxy resins (ECN) are commercially available, and include, for example, ECN-268, ECN-273, ECN-280, ECN-285, ECN-299 (all manufactured by Asahi Kasei).
The epoxy resin may be used alone or in combination of two or more.

  The glass cloth used in the present invention may be of various types depending on the purpose and application, and a commercially available product can be used as it is. Its thickness is preferably 20 to 60 μm.

  The mixing ratio of the epoxy resin, the glass cloth, and the ferrite powder in the present invention preferably satisfies the following relationship when represented by the ratio of the total amount of the epoxy resin and the glass cloth to the ferrite powder.

(Epoxy resin + glass cloth): ferrite powder = 100: 100-400
That is, the content of the ferrite powder is preferably 50 to 80% by weight. By setting the content of such ferrite powder, the effect of the present invention is improved. On the other hand, when the content of the ferrite powder is large, it is difficult to form a slurry and apply the slurry, and it is difficult to prepare a prepreg. On the other hand, when the content of the ferrite powder is small, the magnetic properties are deteriorated.

  The mixing ratio of the epoxy resin and the glass cloth is preferably 4/1 to 1/1 in weight ratio of epoxy resin / glass cloth. With such a mixing ratio, the effects of the present invention are improved. On the other hand, when this ratio is reduced and the amount of epoxy resin is reduced, the adhesion to the copper foil is reduced, and a problem occurs in the smoothness of the substrate. Conversely, when this ratio increases and the amount of epoxy resin increases, it becomes difficult to select a glass cloth that can be used, and it is difficult to secure strength with a thin wall.

  In the present invention, the prepreg is obtained by impregnating and drying a paste containing a ferrite powder and an epoxy resin having a predetermined compounding ratio, kneaded in a solvent, and slurried. The solvent used in this case is a volatile solvent such as methyl ethyl ketone (MEK), and is used for the purpose of adjusting the viscosity of the paste to facilitate coating. The kneading may be performed by a known method using a ball mill or the like. By impregnating the paste into the glass cloth, the gap having a diameter of about several μm in the glass cloth is filled. The thickness of the coating film is preferably, for example, about 40 μm when using a 20 μm thick glass cloth in the prepreg, and preferably about 1 to 3 times the thickness of the glass cloth. With such a thickness, the smoothness and adhesiveness of the prepreg are improved.

  The total thickness of the prepreg of the present invention is preferably about 60 to 140 μm when a glass cloth having a thickness of 20 μm is used.

The prepreg of the present invention forms a substrate by applying heat and pressure to mold. In this case, only one prepreg may be used, or a plurality of prepregs may be used in an overlapping manner depending on the intended thickness. The molding may be performed according to a known method, and the heating and pressing conditions may be a temperature of 100 to 200 ° C. and a pressure of 10 to 80 kgf / cm ² , and the molding may be performed under such conditions for about 30 to 120 minutes. preferable. The molding can be performed in a plurality of stages under different conditions.

  The substrate (organic composite material) as a molding material thus obtained is excellent in high-frequency characteristics of magnetic permeability and dielectric constant. In addition, it has excellent insulation properties that can be endured as an insulating material. Furthermore, when a substrate with a copper foil is used as described later, the adhesive strength with the copper foil is large. Also, it has excellent heat resistance such as solder heat resistance.

The prepreg of the present invention can form a substrate with a copper foil by laminating on a copper foil and molding by heating and pressing. In this case, the thickness of the copper foil is about 12 to 35 μm.
Examples of such a substrate with a copper foil include a double-sided patterned substrate and a multilayer substrate.

  1 and 2 show process diagrams of an example of forming a double-sided patterned substrate. As shown in FIGS. 1 and 2, a prepreg 1 having a predetermined thickness and a copper (Cu) foil 2 having a predetermined thickness are stacked, and are heated and molded under pressure (step A). Next, through holes are formed by drilling (step B). Copper (Cu) plating is applied to the formed through holes to form a plating film 4 (step C). Further, the copper foil 2 on both sides is patterned to form a conductor pattern 21 (step D). Thereafter, as shown in FIG. 1, plating for connecting external terminals and the like is performed (step E). In this case, plating is performed by a method of further plating Pd after Ni plating, a method of further plating Au after Ni plating (plating is electrolytic or electroless plating), or a method using a solder leveler.

  FIG. 3 and FIG. 4 are process diagrams of a multilayer substrate forming example, and show an example in which four layers are stacked. As shown in FIG. 3 and FIG. 4, a prepreg 1 having a predetermined thickness and a copper (Cu) foil 2 having a predetermined thickness are stacked and molded by applying pressure and heating (step a). Next, the copper foils 2 on both sides are patterned to form conductor patterns 21 (step b). A prepreg 1 and a copper foil 2 each having a predetermined thickness are further laminated on both sides of the double-sided patterned substrate thus obtained, and are simultaneously molded by applying pressure and heat (step c). Next, through holes are formed by drilling (step d). Copper (Cu) plating is applied to the formed through holes to form a plating film 4 (step e). Further, the copper foils 2 on both sides are patterned to form conductor patterns 21 (step f). Thereafter, as shown in FIG. 3, plating for connection to external terminals is performed (step g). In this case, plating is performed by a method of further plating Pd after Ni plating, a method of further plating Au after Ni plating (plating is electrolytic or electroless plating), or a method using a solder leveler.

The above-mentioned heating and pressing molding conditions are preferably performed at a temperature of 100 to 200 ° C. and a pressure of 10 to 80 kgf / cm ² for 30 to 120 minutes.

  In the present invention, not limited to the above example, various substrates can be formed. For example, it is also possible to use a substrate as a molding material or a substrate with a copper foil and a prepreg, and use the prepreg as an adhesive layer to form a multilayer. Further, in a mode of bonding a substrate as a prepreg or a molding material and a copper foil, a substrate obtained by patterning a ferrite paste obtained by kneading the above-described ferrite powder, an epoxy resin, and a high-boiling solvent such as butyl carbitol acetate. May be formed by screen printing or the like, whereby the characteristics can be improved. The content of ferrite powder in such a ferrite paste is preferably 50 to 80% by weight, 45 to 10% by weight of epoxy resin, and 5 to 10% by weight of solvent. The thickness of the coating film is preferably 30 to 150 μm on the molded substrate.

Hereinafter, specific examples of the present invention will be shown, and the present invention will be described in more detail.
Example 1
550 parts by weight of Mn-Mg-Zn-based ferrite (μ320) powder having an average particle size of 3 μm is added to a MEK liquid (varnish) containing 100 parts by weight of a phenol novolak type epoxy resin, and kneaded by a ball mill to form a slurry paste. Obtained.

  This paste was impregnated into a glass cloth having a thickness of 20 μm and dried at 110 ° C. for 60 minutes to obtain a prepreg. This is designated as prepreg No. 11. The thickness of the paste coating film in such prepreg No. 11 is 40 μm in dry thickness. The mixing ratio of ferrite powder, glass cloth and epoxy resin is 66 wt%, 12 wt% and 22 wt%.

Pre-preg No. 11 was subjected to primary molding under the conditions of a temperature of 110 ° C., a pressure of 10 kgf / cm ² and a time of 30 minutes, and further subjected to secondary molding at a temperature of 180 ° C., a pressure of 40 kgf / cm ² and a time of 30 minutes. . This is designated as molding material No. 11.

  A prepreg No. 12 was obtained in the same manner as in the molding material No. 11, except that the ferrite was changed to a Mn-Zn-based ferrite (μ1800), whereby a molding material No. 2 was obtained.

  The physical properties or characteristics of such molding materials No. 11 and 12 were examined. Table 1 shows the results. Among them, solder heat resistance and copper foil peel strength were evaluated as follows.

Solder heat resistance JIS C 5012 [Testing method for printed wiring board] Evaluation was made in accordance with 10.4.1 solder float method. However, the dipping time was 3 minutes. Evaluation was performed at 260 ° C. (260 ° C. × 3 minutes).

Copper foil peel strength JIS C 5012 [Testing method for printed wiring board] 8.1 Evaluated based on peeling strength of conductor.

  Table 1 shows that the molding material using the prepreg of the present invention is suitable as a substrate material. Note that the Mn-Mg-Zn-based material is a more preferable material because it has higher insulating properties than the Mn-Zn-based material.

Example 2
In the same manner as in Example 1, prepregs using Mn—Mg—Zn-based ferrite (μ320) and Ni—Zn-based ferrite (μ100) as ferrites were obtained, and molding materials were obtained therefrom. These are referred to as molding materials Nos. 21 to 23, and the corresponding prepregs are referred to as prepreg Nos. 21 to 23. However, the compounding ratios in the molding materials Nos. 21 to 23 are as follows.

Molding material No. 21: Mn-Mg-Zn ferrite powder 66wt%
Glass cloth 12wt%
Epoxy resin 22wt%
Molding material No. 22: Ni-Zn ferrite powder 66wt%
Glass cloth 12wt%
Epoxy resin 22wt%
Molding material No. 23: Ni-Zn ferrite powder 80 wt%
Glass cloth 10wt%
Epoxy resin 10wt%

For these molding materials Nos. 21 to 23, the frequency characteristics of the complex relative magnetic permeability μ ′ and μ ″ and the frequency characteristics of the complex dielectric constants ε′r and ε ″ r were examined.
The results are shown in FIGS.
5 and 6, it can be seen that the high-frequency characteristics of μ ′ and μ ″ are excellent. That is, μ ′ remains even at several hundred MHz, and the frequency at which μ ″ takes the maximum value is 1 to 2 GHz. 7 and 8 show that the high frequency characteristics of ε′r and ε ″ r are excellent. That is, ε′r and ε ″ r are flat in the measurement frequency range.

Example 3
Using prepreg No. 11 containing the Mn-Mg-Zn-based ferrite powder prepared in Example 1, Cu foils were stacked on both surfaces and pressed and heated to mold. The molding conditions at this time were: primary molding at 110 ° C. and a pressure of 10 kgf / cm ² for 30 minutes, and secondary molding at 180 ° C. and a pressure of 40 kgf / cm ² for 30 minutes. Next, through-hold rrilling was performed, through-hole plating was performed with Cu, and patterning was performed on both surfaces to form a spiral coil pattern as shown in FIGS. 9 and 10. FIG. 9 is a pattern diagram on the front side of the substrate, and FIG. 10 is a pattern diagram on the back side. The numerical values in the figure represent dimensions (mm). Further, Ni plating was applied to a thickness of 2 μm, and further, Au flash plating was performed to complete the device. In this case, the thickness of Cu was 30 μm, and the overall thickness of the substrate was 0.5 mm. This is designated as substrate element No. 31.

  Using the element No. 31 prepared above, a ferrite paste containing 80 wt% of Mn-Mg-Zn-based ferrite powder (μ320, average particle size 3 μm) was screen-printed on both surfaces, and thermoset at 180 ° C. for 30 minutes. did.

  The ferrite paste contains Mn-Mg-Zn ferrite powder (μ320, average particle size 3 μm), 10 wt% of epoxy resin, and 10 wt% of butyl carbitol acetate, and is obtained by kneading them.

  The thickness of this coating film was 100 μm in the completed substrate element, and the total thickness of the element was 0.70 mm. This is designated as substrate element No. 32.

Further, using a commonly used glass epoxy substrate (FR-4, with double-sided copper foil) containing no ferrite, a substrate element was completed in the same process as substrate element No. 31 after the drilling step. The element thickness was 0.5 mm.
This is designated as substrate element No. 33.

  With respect to these substrate elements Nos. 31 to 33, the frequency characteristics of inductance (L) and impedance (Z) were examined. The results are shown in FIGS. 13 and 14 show frequency characteristics of resistance (R) as a real part of impedance (Z) and reactance (X) as an imaginary part.

  From FIG. 11, in the region of 10 MHz, the element No. 31 which is a ferrite substrate is about 1.6 times as large as the element No. 33 which is a normal ferrite-free substrate, and the element No. 32 of a ferrite substrate + ferrite resist is 2 times. It can be seen that the inductance value is improved by about 0.6 times. 12 to 14 that the impedance value increases in the same tendency as the inductance value. This is due to the structure of a closed magnetic circuit formed by a magnetic material.

  Further, the inductance component remains up to the region of 1 GHz or more, because the frequency characteristics of the magnetic permeability and the dielectric constant described above are excellent.

  Further, the resistance component (R) rises sharply at 100 MHz or more, which depends on the frequency characteristic of μ ″.

  These board elements Nos. 31 and 32 clear the solder heat resistance of 350 seconds at the maximum required for chip components for 3 seconds.

  For this reason, when compared to a normal ferrite-free substrate, the substrate of the present invention can improve the inductance and impedance up to high frequencies due to the closed magnetic circuit effect and the excellent high-frequency characteristics of the material, and further has a resistance component. It has been found that the material can be used as a high-frequency chip component or substrate utilizing the excellent high-frequency magnetic loss characteristics of the material, which appears in the high-frequency region.

FIG. 4 is a process chart showing an example of forming a double-sided pattern substrate of the present invention. FIG. 4 is a process chart showing an example of forming a double-sided pattern substrate of the present invention. It is a flowchart showing the example of formation of the multilayer board of the present invention. It is a flowchart showing the example of formation of the multilayer board of the present invention. It is a graph which shows the frequency characteristic of μ 'of the substrate (molding material) of the present invention. 4 is a graph showing μ ″ frequency characteristics of the substrate (molding material) of the present invention. 5 is a graph showing frequency characteristics of ε′r of the substrate (molding material) of the present invention. 4 is a graph showing frequency characteristics of ε ″ r of the substrate (molding material) of the present invention. It is the schematic which shows the conductor pattern on the front side of the board | substrate element of this invention. It is the schematic which shows the conductor pattern on the back side of the board element of this invention. 6 is a graph illustrating frequency characteristics of inductance of a substrate element. 6 is a graph illustrating frequency characteristics of impedance of a substrate element. It is a graph which shows the frequency characteristic of the real part of the impedance of a board | substrate element. It is a graph which shows the frequency characteristic of the imaginary part of the impedance of a board | substrate element.

Explanation of reference numerals

DESCRIPTION OF SYMBOLS 1 Prepreg 2 Cu foil 3 Through hole 4 Cu plating film 21 Conductor pattern

Claims (9)

A glass cloth is impregnated with a paste obtained by kneading a ferrite powder and an epoxy resin in a solvent to form a slurry, and drying is performed. A substrate on which a ferrite paste coating film obtained by kneading a ferrite powder and an epoxy resin in a solvent is formed on a foil. A glass cloth is impregnated with a paste obtained by kneading a slurry by kneading a ferrite powder and an epoxy resin with a solvent, drying and drying a plurality of prepregs, heating and pressing a copper foil and forming a substrate obtained by pressing. A substrate on which a ferrite paste coating film obtained by kneading a ferrite powder and an epoxy resin in a solvent is formed on a copper foil on the surface. A glass cloth is impregnated with a paste obtained by kneading a slurry by kneading a ferrite powder and an epoxy resin in a solvent, and drying the prepreg obtained. A substrate obtained by heating and pressing and molding a plurality of sheets, a substrate obtained by heating and pressing the prepreg and the copper foil, and a substrate obtained by stacking a plurality of the prepregs and heating and pressing the copper foil and forming A ferrite obtained by kneading ferrite powder and epoxy resin in a solvent on a copper foil on the surface of a multi-layer substrate obtained by heating and pressing and molding using a substrate selected from the obtained substrates. Substrate on which the paste coating is formed. 4. The substrate according to claim 1, wherein said ferrite paste for forming a coating film contains 50 to 80% by weight of ferrite powder and 45 to 10% by weight of epoxy resin. 5. The substrate according to claim 1, wherein the particle size of the ferrite powder of the prepreg is 0.01 to 50 [mu] m. The substrate according to any one of claims 1 to 5, wherein a content of the ferrite powder represented by a weight ratio of an amount of the ferrite powder to a total amount of the ferrite powder, the epoxy resin, and the glass cloth of the prepreg is 50 to 80 wt%. The substrate according to any one of claims 1 to 6, wherein a mixing ratio of the epoxy resin and the glass cloth of the prepreg is 4/1 to 1/1 in weight ratio of epoxy resin / glass cloth. 8. The substrate according to claim 1, wherein said prepreg uses a glass cloth having a thickness of 20 to 60 [mu] m. 9. The substrate according to claim 1, which is used in a high frequency range of 100 MHz or more.