JP6036007B2 - Multilayer coil parts - Google Patents

Description

  The present invention relates to a laminated coil component.

  Patent Document 1 includes a step of preparing a conductive paste containing conductive particles and thermally decomposable resin particles, and thermally contracting more than a ceramic material constituting the ceramic body, and using the conductive paste to produce a ceramic. A laminate type having a step of screen-printing a conductor pattern on a green sheet, a step of forming a laminate by laminating a plurality of ceramic green sheets printed with a conductor pattern, and a step of firing the laminate. A method for manufacturing a coil component is disclosed.

  If residual carbon remains in the conductive paste during the binder removal process, the residual carbon vaporizes and expands in the subsequent firing process, and the ceramic body and conductive particles formed by sintering the ceramic green sheet are formed by sintering. The interface with the formed inner conductor may be in a crimped state. However, when the conductive paste having the thermal decomposability is used, the resin particles are burned out or completely disappeared before the conductive particles are sintered. Therefore, the interface between the ceramic body and the internal conductor is suppressed from being brought into a crimped state. Accordingly, a gap is formed at the interface between the ceramic body and the internal conductor, and it is difficult for a minute stress to remain at the interface, so that electrical characteristics and reliability can be improved.

JP 2005-167108 A

  By the way, the multilayer coil component has a lower Q factor (quality factor) than a wire wound coil component wound with a wire due to reasons such as its structure and manufacturing method. However, in recent years, with the demand for components capable of handling particularly high frequencies, a high Q value is also required for multilayer coil components. Conventional multilayer coil components have not been able to achieve a high Q value that satisfies these requirements.

  The present invention has been made to solve such problems, and an object of the present invention is to provide a laminated coil component capable of obtaining a high Q value.

  In the case where a plurality of holes are present along the longitudinal direction in the coil conductor, the present inventors calculate the ratio of the area of the hole to the cross-sectional area of the coil conductor in a plane orthogonal to the longitudinal direction. It has been found that a high Q value can be obtained according to the porosity shown, and the present invention has been completed.

  That is, the multilayer coil component according to one aspect of the present invention includes an element body formed by laminating a plurality of insulator layers and a plurality of coil conductors electrically connected to the inside of the element body. A plurality of holes are arranged in the coil conductor along the longitudinal direction of the coil conductor, and the holes of the coil conductor with respect to the cross-sectional area of the coil conductor in a plane orthogonal to the longitudinal direction are present in the coil conductor. The average porosity, which is an average value from one end of the coil conductor to the other end, of the porosity indicating the area ratio is 15% or more.

  The reason why a high Q value is obtained according to the porosity is considered as follows. As the porosity increases, the total cross-sectional area of the holes and the coil conductor also increases, so that the size of the outer shape of the coil conductor increases. For this reason, the peripheral length of the coil conductor in a plane orthogonal to the longitudinal direction is increased. That is, the outline of the coil conductor changes depending on the presence or absence of holes and the size of the holes, and the outer shape of the coil conductor becomes larger as the holes are larger. When a high-frequency current flows through the conductor, the current flows only near the surface of the conductor due to the skin effect, so that the peripheral length increases, the cross-sectional area through which the current flows increases. Therefore, the resistance of the coil conductor is reduced. Since the Q value is inversely proportional to the magnitude of the resistance of the coil conductor, a high Q value is obtained as the resistance of the coil conductor is reduced. In particular, by setting the average porosity to 15% or more, it is possible to obtain a Q value equal to or higher than that of the wire-wound coil component even in the laminated coil component.

  According to the present invention, a high Q value can be obtained in a laminated coil component.

FIG. 1 is a cross-sectional view showing a laminated coil component according to this embodiment. FIG. 2 is a cross-sectional view showing a laminated coil component according to another example of the present embodiment. FIG. 3 is a schematic view showing the state of the element body during firing when the softening point of the coil portion arrangement layer is low and with or without the shape retaining layer. FIG. 4 is a schematic diagram showing the relationship between the state of the element body and the smoothness of the surface of the coil conductor. FIG. 5 is a photograph showing a cross section of the coil conductor of the laminated coil component. FIG. 6 is an enlarged sectional view showing a part of the conductor pattern. FIG. 7 is a diagram illustrating the relationship between the porosity and the magnitude of the deviation of the Q value from the wound coil component. FIG. 8 is a schematic diagram showing the relationship between the surface smoothness of the coil conductor and the surface resistance.

  Embodiments of the present invention will be described with reference to the drawings. However, the following embodiments are exemplifications for explaining the present invention and are not intended to limit the present invention to the following contents. In the description, the same reference numerals are used for the same elements or elements having the same function, and redundant description is omitted.

  As shown in FIGS. 1 and 2, the laminated coil component 1 includes an element body 2 formed by laminating a plurality of insulator layers and a plurality of coil conductors 4 and 5 inside the element body 2. A coil portion 3 to be formed and a pair of external electrodes 6 formed on both end faces of the element body 2 are provided.

  The element body 2 is a rectangular parallelepiped or cubic laminate made of a sintered body in which a plurality of ceramic green sheets are laminated. As shown in FIG. 2, the element body 2 includes a coil part arrangement layer 2A in which the coil part 3 is arranged, and a shape-retaining layer 2B provided as a pair so as to sandwich the coil part arrangement layer 2A. Alternatively, as shown in FIG. 1, the coil portion arrangement layer 2A may be provided without the shape retaining layer 2B.

The coil portion arrangement layer 2A is not particularly limited as long as the particle diameter of the coil conductor 4 can be within a predetermined range, but is preferably made of glass ceramics, for example. This is because the dielectric constant of the element body 2 is reduced and the Q value can be increased. The coil portion arrangement layer 2A is preferably made of amorphous ceramics. This is because the smoothness of the coil conductors 4 and 5 can be increased. The coil portion arrangement layer 2A preferably contains SiO ₂ . This is because the dielectric constant of the coil portion arrangement layer 2A can be reduced. The coil portion arrangement layer 2A preferably contains Al ₂ O ₃ . This is because the crystal transition in the coil portion arrangement layer 2A can be prevented. The coil portion arrangement layer 2A preferably contains K ₂ O in order to form the covering layer 7 that covers the coil conductors 4 and 5.

The coil portion arrangement layer 2A contains 35-60% by weight of a borosilicate glass component as a main component, 15-35% by weight of a quartz component, an amorphous silica component in the balance, and alumina as a subcomponent. The alumina content may be 0.5 to 2.5% by weight with respect to 100% by weight of the main component. In the coil portion arrangement layer 2A, after firing, SiO ₂ is 86.7 to 92.5 wt%, B ₂ O ₃ is 6.2 to 10.7 wt%, and K ₂ O is 0.7 to 1.2. % By weight and Al ₂ O ₃ may have a composition of 0.5 to 2.4% by weight. When the glass ceramic contains 86.7 to 92.5% by weight of SiO ₂ and 0.5 to 2.4% by weight of Al ₂ O ₃ , the surface smoothness of the coil conductors 4 and 5 is further increased. Can be improved. The coil portion arrangement layer 2A may contain 1.0 wt% or less of MgO and CaO. Coil unit arrangement layer 2A is, by containing SiO ₂ of 86.7 to 92.5 wt%, it is possible to reduce the dielectric constant of the coil portion disposed layer 2A. When the coil part arrangement layer 2A contains 0.5 to 2.4% by weight of Al ₂ O ₃ , crystal transition in the coil part arrangement layer 2A can be prevented. The coil portion arrangement layer 2A may contain 1.0 wt% or less of MgO and CaO.

Or coil part arrangement | positioning layer 2A contains 35 to 75 weight% of borosilicate glass components as a main component, contains 5 to 40 weight% of quartz components, and contains 5 to 60 weight% of zinc silicate components. Good. Borosilicate glass has SiO ₂ = 70 to 90% by weight, B ₂ O ₃ = 10 to 30% by weight as main components, and K ₂ O, Na ₂ O, BaO, SrO, Al ₂ O ₃ and CaO as subcomponents. You may contain 5 weight% or less of at least 1 sort (s) or more in total. The coil portion arrangement layer 2A has SiO ₂ = 53.7 to 89.5% by weight, B ₂ O ₃ = 3.5 to 22.5% by weight, ZnO = 3.0 to 35.8% by weight after firing. , K ₂ O, Na ₂ O, BaO, SrO, Al ₂ O ₃ and CaO may have a total composition of 3.8% by weight or less.

  As shown in FIG. 2, when the element body 2 has a shape retaining layer 2B, the element body 2 preferably has the following structure. That is, the shape-retaining layer 2B is formed so as to cover the entire end face 2a and end face 2b facing each other in the stacking direction among the end faces of the coil portion arrangement layer 2A. The shape retaining layer 2B has a function of maintaining the shape of the coil portion arrangement layer 2A during sintering. The thickness of the coil portion arrangement layer 2A in the stacking direction is, for example, 0.1 mm or more, and the thickness of the shape retaining layer 2B in the stacking direction is 5 μm or more.

The shape retention layer 2B may contain 50 to 70% by weight of a glass component and 30 to 50% by weight of an alumina component as main components. Hokatachiso 2B is after sintering, SiO ₂ is 23 to 42 _wt%, B 2 _{O 3} is 0.25 to 3.5 wt%, _Al 2 _{O 3} is from 34.2 to 58.8 wt%, alkali The earth metal oxide has a composition of 12.5 to 31.5% by weight, and is 60% by weight or more in the alkaline earth metal oxide (that is, 7.5 to 31.5% by weight of the entire shape retaining layer 2B). ) May be SrO.

  When the element body 2 is configured as shown in FIG. 2, the softening point of the coil portion arrangement layer 2A may be set lower than the softening point or melting point of the shape retaining layer 2B. Specifically, the softening point of the coil portion arrangement layer 2A may be 800 to 1050 ° C, and the softening point or melting point of the shape retaining layer 2B may be 1200 ° C or higher. The coil part arrangement layer 2A can be made amorphous by lowering the softening point of the coil part arrangement layer 2A. By increasing the softening point or melting point of the shape retention layer 2B, the shape can be maintained so that the coil portion arrangement layer 2A having a low softening point does not deform during firing.

Since the softening point cannot be lowered if SrO is contained, it is preferable that SrO is not contained in the coil portion arrangement layer 2A. Here, since SrO hardly diffuses, it is suppressed that SrO of the shape retaining layer 2B diffuses into the coil portion arrangement layer 2A during firing. If SrO is not contained in the coil portion arrangement layer 2A, the content ratio of SiO ₂ showing a low dielectric constant can be relatively increased in the coil portion arrangement layer 2A, and thereby the dielectric constant can be lowered. . Therefore, the Q (quality factor) value of the coil can be increased. On the other hand, since the shape retention layer 2B contains SrO, the content of SiO ₂ is smaller than that of the coil portion arrangement layer 2A, so that the dielectric constant of the shape retention layer 2B is increased. However, the shape retaining layer 2B does not include the coil conductors 4 and 5, and does not affect the Q value of the coil. Coil unit arrangement layer 2A is less high intensity content of SiO _2, Hokatachiso 2B is a high strength low content of SiO _2. That is, the shape retaining layer 2B can also function as a reinforcing layer of the coil portion arranging layer 2A after firing.

  Here, as shown in FIG. 3A, if the element body is crystalline, the surface of the coil conductor in contact with the element body may be uneven due to the influence of the unevenness on the surface of the element body. On the other hand, as shown in FIG. 3B, it is more preferable that the element body is amorphous because the surface of the coil conductor in contact therewith becomes smooth due to the influence of the smooth surface of the element body. That is, the element body is more preferably amorphous. When the element body 2 has the configuration shown in FIG. 2, the element body 2 is not completely amorphous, and the crystalline substance is reduced to the extent that the alumina component is contained in a small amount (0.5 to 2.4 wt%). Although the portion is included, the amount is extremely small, so that a smooth surface as shown in FIG.

  When the softening point is lowered in order to make the element body amorphous, the shape of the element body is rounded by softening the entire element body as shown in FIG. 4B, and the shape cannot be maintained. There is a case. However, when the structure having the shape retaining layer 2B as shown in FIG. 2 is adopted as the element body 2, it is preferable because the shape of the element body 2 can be maintained as shown in FIG. When the structure of FIG. 2 is adopted as the element body 2, even if the softening point is set lower than the shape-retaining layer 2B in order to make the coil portion arrangement layer 2A amorphous, the coil portion having a low softening point. Since the arrangement layer 2A is sandwiched between the shape-retaining layers 2B, the shape is maintained without being rounded during firing. If the shape retaining layer 2B is not provided but can be made amorphous, the configuration shown in FIG. 1 may be used. The element body is not limited to being amorphous, and may be crystalline as long as a desired coil conductor particle size can be obtained.

  The coil part 3 has a coil conductor 4 related to the winding part and a coil conductor 5 related to the lead part connected to the external electrode 6. For example, the coil conductors 4 and 5 are made of a conductor paste mainly composed of silver, copper, or nickel. In the case where the element body 2 has the configuration shown in FIG. 2, the coil part 3 is arranged only inside the coil part arrangement layer 2A and is not arranged in the shape retaining layer 2B. None of the coil conductors 4 and 5 of the coil part 3 is in contact with the shape retaining layer 2B. Both end portions of the coil portion 3 in the stacking direction are separated from the shape retaining layer 2B, and the ceramic of the coil portion arrangement layer 2A is disposed between the coil portion 3 and the shape retaining layer 2B. The coil conductor 4 related to the winding portion is configured by forming a conductor pattern of a predetermined winding with a conductor paste on the ceramic green sheet forming the coil portion arrangement layer 2A. The conductor patterns of each layer are electrically connected in the stacking direction by through-hole conductors. The coil conductor 5 related to the lead-out portion is configured by a conductor pattern that pulls the end of the winding pattern to the external electrode 6. The coil pattern of the winding part, the number of windings, the drawing position of the drawing part, etc. are not particularly limited.

  Around the coil conductors 4 and 5 of the coil portion 3, a K (potassium) coating layer 7 is formed to cover the coil conductors 4 and 5. The covering layer 7 is formed by allowing potassium to be collected around the coil conductors 4 and 5 during firing by adding potassium to the ceramic green sheet before firing forming the coil portion arrangement layer 2A.

  The particle size after firing of the coil conductors 4 and 5 is preferably 10 μm to 22 μm, and more preferably 11 μm to 18 μm. By setting the particle diameter of the coil conductors 4 and 5 to 22 μm or less, it is possible to suppress the occurrence of disconnection or pull-in of the lead-out portion due to melting of the metal (for example, silver) constituting the coil conductors 4 and 5.

  In order to reduce the surface resistance, it is preferable to reduce the surface roughness of the coil conductors 4 and 5. By setting the particle diameter of the coil conductors 4 and 5 to 10 μm or more, the surface roughness can be reduced and the Q value can be increased at a high frequency. FIG. 5 shows an example of a SIM (Scanning Ion Microscopy) image of the cross section of the coil conductor when the surface roughness is 1%, 5%, 8% and 18%. In this embodiment, the height of the unevenness and the width of the unevenness of the coil conductor are measured for the boundary portion between the coil conductor and the element body in the conductor cross section, and the percentage of the height of the unevenness with respect to the width of the unevenness is obtained. More than 100 irregularities were sampled and statistically processed, and the average value of the percentage was defined as the surface roughness.

  A plurality of holes H (see FIG. 6) are arranged in the coil conductors 4 and 5 along the longitudinal direction thereof. These holes H exist only inside the coil conductors 4 and 5 and do not communicate with the surfaces of the coil conductors 4 and 5. In the coil conductors 4 and 5, there may be very few holes (not shown) communicating with the surfaces of the coil conductors 4 and 5. Only the hole H which exists only inside and does not communicate with the surfaces of the coil conductors 4 and 5 is referred to. The surfaces of the coil conductors 4 and 5 are in close contact with the element body 2 (coil portion arrangement layer 2A).

In the present embodiment, the area of the hole H (as the coil conductors 4, 5) with respect to the cross-sectional area of the coil conductors 4, 5 in the plane perpendicular to the longitudinal direction The average porosity, which is an average value from one end of the coil conductors 4 and 5 to the other end, of the porosity indicating the ratio of the area of the area where there is no substance is 15% or more. FIG. 7 and Table 1 show the relationship between the porosity and the magnitude of the deviation of the Q value from the wound coil component. The magnitude of the deviation when the average porosity is 3.63% is -10.5%, and the magnitude of the deviation when the average porosity is 6.26% is -6.81%. Yes, the magnitude of the deviation when the average porosity is 7.26% is -4.51%, and the magnitude of the deviation when the average porosity is 15.3% is 0.76%. When the average porosity is 17.8%, the magnitude of the deviation is 2.31%. As shown in FIG. 7, when the average porosity is 15% or more, the multilayer coil component 1 can also obtain a Q value equal to or higher than that of the wire-wound coil component. An average porosity of 17% or more is more preferable because a Q value that is even higher than that of the wire-wound coil component can be obtained.

  The circumferential length of the coil conductors 4 and 5 in a plane orthogonal to the longitudinal direction can be set to about 60 μm to 80 μm when the multilayer coil component 1 has a 0402 shape, and when the multilayer coil component 1 has a 0603 shape. It can be set to about 70 μm to 90 μm, and can be set to about 190 μm to 240 μm when the laminated coil component 1 has a 1005 shape. The height (aspect ratio) with respect to the width of the coil conductors 4 and 5 on a plane orthogonal to the longitudinal direction can be set to about 0.3 to 1.0.

  The pair of external electrodes 6 are formed so as to cover both end faces facing each other in the direction orthogonal to the stacking direction, among the end faces of the element body 2. Each external electrode 6 may be formed so as to cover the entire both end surfaces, and a part may wrap around from the both end surfaces to the other four surfaces. Each external electrode 6 is formed by screen-printing or using a printing and dipping method, for example, a conductor paste containing silver, copper, or nickel as a main component.

  Next, a method for manufacturing the multilayer coil component 1 having the above-described configuration will be described.

  First, a ceramic green sheet for forming the coil portion arrangement layer 2A is prepared. Each ceramic green sheet is prepared by adjusting a ceramic paste so as to have the above-described composition and molding the sheet by a doctor blade method or the like. In the case of the configuration as shown in FIG. 2, a ceramic green sheet for forming the shape retaining layer 2B is also prepared.

  A conductive paste for forming the coil conductors 4 and 5 is prepared. The conductive paste contains a conductor powder mainly composed of silver, nickel or copper having a predetermined particle size characteristic. Specifically, conductor powder having an average particle size of 1 μm to 3 μm and a standard deviation of 0.7 μm to 1.0 μm is used. In addition, classification may be performed to obtain a conductor powder having such particle size characteristics.

  Subsequently, a through hole is formed by laser processing or the like at a predetermined position of each ceramic green sheet serving as the coil portion arrangement layer 2A, that is, a position where a through hole electrode is to be formed. Next, each conductor pattern is formed on each ceramic green sheet to be the coil portion arrangement layer 2A. Each conductor pattern and each through-hole electrode are formed by a screen printing method using a conductive paste containing silver or nickel. Next, binder removal is performed by heat-treating the conductive paste at a predetermined temperature (for example, about 100 to 150 °) for a predetermined time (for example, about 1 to 2 hours). At this time, a part of the binder remains as residual carbon in the conductive paste.

  Subsequently, each ceramic green sheet is laminated. In the case of the configuration as shown in FIG. 2, the ceramic green sheets to be the coil portion arrangement layer 2A are stacked on the ceramic green sheets to be the shape retaining layer 2B, and the ceramic green sheets to be the shape retaining layer 2B are stacked thereon. The shape-retaining layer 2B formed on the bottom and the top may be formed by a single ceramic green sheet or a plurality of ceramic green sheets. Next, pressure is applied in the stacking direction to pressure-bond each ceramic green sheet.

  Subsequently, the laminated body is baked, for example, at 900 to 940 ° C. for 10 to 60 minutes to form the element body 2. The firing condition is adjusted by setting the target particle size of the coil conductor to 10 μm to 22 μm. At this time, the residual carbon remaining in the conductive paste is gasified and expands, but the metal powder contained in the conductive paste is sintered first, and the gas tends to stay in the coil conductors 4 and 5. Since the ceramic green sheet used as the coil portion arrangement layer 2A is a glass-based material, the coil portion arrangement layer 2A is also easily deformed as the gas expands. Thus, the gas remaining in the coil conductors 4 and 5 forms relatively large holes H in the coil conductors 4 and 5, and the average porosity of the coil conductors 4 and 5 is 15% or more. In the case of the configuration as shown in FIG. 2, the set firing temperature is set to be equal to or higher than the softening point of the coil portion arrangement layer 2A and lower than the softening point or melting point of the shape retaining layer 2B. At this time, the shape retention layer 2B maintains the shape of the coil portion arrangement layer 2A.

  Subsequently, the external electrode 6 is formed on the element body 2. Thereby, the laminated coil component 1 is formed. The external electrode 6 is applied with an electrode paste mainly composed of silver, nickel or copper on both end faces in the longitudinal direction of the element body 2 and baked at a predetermined temperature (for example, about 600 to 700 ° C.). It is formed by applying electroplating. For this electroplating, Cu, Ni, Sn, or the like can be used.

  The reason why a high Q value is obtained according to the porosity in the multilayer coil component according to the present embodiment as described above is considered as follows. As the porosity increases, the total cross-sectional area of the holes H and the coil conductors 4 and 5 increases, so that the outer dimensions of the coil conductors 4 and 5 increase. Therefore, the peripheral length of the coil conductors 4 and 5 in a plane orthogonal to the longitudinal direction is increased. That is, the contours of the coil conductors 4 and 5 change depending on the presence or absence of the hole H and the size of the hole H, and the outer shape of the coil conductors 4 and 5 increases as the hole H increases. When a high-frequency current flows through the conductor, the current flows only near the surface of the conductor due to the skin effect, so that the peripheral length increases, the cross-sectional area through which the current flows increases. Accordingly, the resistance of the coil conductors 4 and 5 is reduced. Since the Q value is inversely proportional to the resistance of the coil conductors 4 and 5, a high Q value can be obtained as the resistance of the coil conductors 4 and 5 decreases. In particular, by setting the average porosity to 15% or more, even in the laminated coil component 1 that can be manufactured at a lower cost than the wound coil component, a Q value equal to or higher than that of the wound coil component can be obtained.

  By the way, in order to lengthen the perimeter of the coil conductors 4 and 5, it is also conceivable to apply a thick conductor paste on the ceramic green sheet. However, when the conductive paste is applied thickly on the ceramic green sheet, when a plurality of ceramic green sheets to which the conductive paste is applied are stacked and pressed, the step between adjacent ceramic green sheets becomes large, There is a risk of poor crimping. By applying the conductive paste thickly on the ceramic green sheet, the amount of the conductive paste to be used increases and the cost increases. However, in the present embodiment, since the laminated coil component 1 is manufactured so that the average porosity of the coil conductors 4 and 5 is high, the coil conductor 4 is not applied on the ceramic green sheet without thickly applying a conductor paste. , 5 can be made longer. For this reason, in the multilayer coil component 1 according to the present embodiment, it is difficult to cause a crimping failure between the ceramic green sheets, and the manufacturing cost can be suppressed.

  In order to increase the Q value of the coil, it is also preferable to increase the smoothness of the surface of the coil conductor. As mentioned above, when high-frequency current flows through the conductor, current flows only near the surface of the conductor due to the skin effect (because the higher the frequency, the lower the skin depth). This is because the smoothness of the surface of the coil conductor affects the Q value. For example, as shown in FIG. 8B, when the surface of the coil conductor has low smoothness and unevenness is formed, the surface resistance of the coil conductor increases and the Q value of the coil decreases. On the other hand, if the smoothness of the surface of the coil conductor is high as shown in FIG. 8A, the surface resistance of the coil conductor is lowered, and the Q value of the coil can be increased. Therefore, in this embodiment, the surface roughness of the coil conductors 4 and 5 is reduced by setting the particle diameter of the fired coil conductors 4 and 5 to 10 μm or more.

Here, the relationship between the skin depth d and the frequency f is shown in Equation (1). In Equation (1), ρ is the resistivity of the conductor, σ is the conductivity (σ = 1 / ρ), ω is the angular velocity of the current (ω = 2πf), μ is the permeability of the conductor, and π is the circumference. .

  When the conductor is silver, according to Equation (1), the skin depth d = 6.44 μm when the frequency f = 0.1 GHz, and the skin depth d = 2. When the frequency f = 1.0 GHz, the skin depth d = 2.04 μm, and when the frequency f = 3.0 GHz, the skin depth d = 1.18 μm. Therefore, when the coil conductors 4 and 5 are mainly composed of silver, in a high frequency region of 1 GHz or more, there is a hole H in a range closer to the center than 2.04 μm from the surface of the coil conductors 4 and 5. Preferably it is.

  In the present embodiment, in the multilayer coil component 1, a potassium coating layer 7 that covers the coil conductors 4 and 5 is formed. When potassium is present around the coil conductors 4 and 5, the softening point of the element body 2 around the coil conductors 4 and 5 can be lowered, and the element body 2 in the area softens and becomes smooth during firing. It becomes easy. Accordingly, the surfaces of the coil conductors 4 and 5 in contact therewith can also be smoothed. Further, by covering and protecting the coil conductors 4 and 5 with the potassium coating layer 7, it is possible to prevent cracks from occurring near the boundary between the coil conductors 4 and 5 and the glass ceramics.

  As mentioned above, although embodiment of this invention was described in detail, this invention is not limited to above-described embodiment. In the above-described embodiment, the laminated coil component having one coil portion is illustrated, but for example, it may have a plurality of coil portions in an array.

  DESCRIPTION OF SYMBOLS 1 ... Multilayer coil component, 2 ... Element body, 2A ... Coil part arrangement | positioning layer, 2B ... Shape retention layer, 3 ... Coil part, 4,5 ... Coil conductor, 6 ... External conductor.

Claims (2)

A non-magnetic element body formed by laminating a plurality of insulator layers;
A coil portion formed inside the element body by electrically connecting a plurality of coil conductors,
The surface of the coil conductor is in close contact with the element body,
In the coil conductor, there are a plurality of holes arranged along the longitudinal direction thereof,
An average porosity, which is an average value from one end of the coil conductor to the other end, of a porosity indicating a ratio of a hole area to a cross-sectional area of the coil conductor in a plane orthogonal to the longitudinal direction is 15 % Is a laminated coil component.   The multilayer coil component according to claim 1, wherein the element body is a glass ceramic.