JP5929052B2 - Multilayer coil parts - Google Patents

Description

  The present invention relates to a laminated coil component.

  As a conventional multilayer coil component, for example, one described in Patent Document 1 is known. In this laminated coil component, a coil conductor is formed on a glass ceramic sheet, the sheets are laminated, the coil conductors in each sheet are electrically connected, and the coil portion is placed inside by firing. The formed element body is formed. In addition, external electrode portions electrically connected to the end portions of the coil portions are formed on both end faces of the element body.

JP-A-11-297533

  Here, the multilayer coil component has a lower Q (quality factor) value than a wound coil wound with a wire due to reasons such as its structure and manufacturing method. However, with the recent demand for components that can cope with high frequencies in particular, high Q values are also required for laminated coil components. Conventional multilayer coil components have not been able to realize a high Q value until such a requirement is satisfied.

  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 order to increase the Q value of the coil, it is preferable to increase the smoothness of the surface of the coil conductor. The inventors of the present invention have found that it is effective to make the base ceramic amorphous so as to increase the smoothness of the surface of the coil conductor. When the element body is crystalline, the surface of the coil conductor in contact with the element body becomes uneven due to the influence of the unevenness on the surface of the element body, and the smoothness becomes low (see, for example, FIG. 3A). On the other hand, if the element body is amorphous, the surface of the coil conductor in contact with the element body becomes smooth due to the influence of the smooth surface of the element body, and the smoothness becomes high (see, for example, FIG. 3B). ).

  Here, when the softening point is lowered in order to make the element body amorphous, the inventors soften the entire element body, thereby rounding the shape of the element body (for example, FIG. 4B). (Refer to page 3), and found that the problem that the shape cannot be maintained. Therefore, as a result of intensive studies, the present inventors have found a suitable configuration of a laminated coil component.

  That is, a multilayer coil component according to the present invention includes an element body formed by laminating a plurality of insulator layers, and a coil portion formed inside the element body by a plurality of coil conductors. The body includes a coil part arrangement layer in which the coil part is arranged, and at least a pair of shape-retaining layers that sandwich the coil part arrangement layer and keep the shape of the coil part arrangement layer. Is made of a glass ceramic containing SrO, and the coil part arrangement layer is characterized in that the softening point of the coil part arrangement layer is lower than the softening point or melting point of the shape retaining layer.

  In the multilayer coil component according to the present invention, the element body has a coil part arrangement layer in which the coil part is arranged, and a shape retaining layer that sandwiches the coil part arrangement layer. Since the shape retaining layer is made of glass ceramic containing SrO, the softening point or melting point is increased. On the other hand, since the coil portion arrangement layer is amorphous, the softening point is set lower than the softening point or melting point of the shape retaining layer. Since the coil portion arrangement layer having such a low softening point is sandwiched between the shape-retaining layers, the shape is maintained without being rounded during firing. Here, when the material for increasing the softening point is diffused from the shape-retaining layer to the coil portion arrangement layer during firing, the softening point of the coil portion arrangement layer cannot be lowered and is amorphous. It can not be. However, since SrO has a characteristic of not diffusing, it is possible to prevent the softening point of the coil portion arrangement layer from increasing due to diffusion from the shape retaining layer during firing. Thereby, a coil part arrangement | positioning layer can be made amorphous reliably. By making the coil portion arrangement layer amorphous as described above, the smoothness of the surface of the coil conductor can be improved, and thereby the Q value of the multilayer coil component can be increased.

In the multilayer coil component according to the present invention, the coil portion arrangement layer preferably contains 86.7 to 92.5% by weight of SiO ₂ . As a result, the dielectric constant of the coil portion arrangement layer can be reduced.

In the multilayer coil component according to the present invention, the coil portion arrangement layer preferably contains 0.5 to 2.4% by weight of Al ₂ O ₃ . Thereby, crystal transition in the coil portion arrangement layer can be prevented.

  According to the present invention, the Q value of the multilayer coil component can be increased.

It is sectional drawing which shows the laminated coil component which concerns on embodiment of this invention. It is a schematic diagram which shows the relationship between the smoothness of the surface of a coil conductor, and surface resistance. It is a schematic diagram which shows the relationship between the state of an element body, and the smoothness of the surface of a coil conductor. It is a schematic diagram which shows the state of the element body at the time of baking with and without the shape retaining layer. It is an enlarged photograph which shows the mode of the coil conductor and element | base_body of the laminated | stacked coil conductor which concerns on an Example and a comparative example.

  Hereinafter, a preferred embodiment of a multilayer coil component according to the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a cross-sectional view showing a laminated coil component according to an embodiment of the present invention. As shown in FIG. 1, the laminated coil component 1 includes an element body 2 formed by laminating a plurality of insulator layers, and a coil formed inside the element body 2 by a plurality of coil conductors 4 and 5. The part 3 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. 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. The coil portion arrangement layer 2A and the shape retaining layer 2B are made of glass ceramics (the specific composition will be described later). At least coil part arrangement layer 2A consists of amorphous ceramics. The shape retaining layer 2B has a function of maintaining the shape of the coil portion arrangement layer 2A during sintering. 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 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 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 content of alumina is 0.5 to 2.5% by weight with respect to 100% by weight of the main component. And a coil portion disposed layer 2A is after sintering, SiO ₂ is from 86.7 to 92.5 _wt%, B 2 _{O 3} is 6.2 to 10.7 wt%, _{K 2} O is 0.7 to 1 .2 wt%, Al ₂ O ₃ has a composition of 0.5 to 2.4 wt%. 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. The coil unit arrangement layer 2A is, by containing _Al 2 _{O 3} of 0.5 to 2.4 wt%, it is possible to prevent the crystal transition of the coil portion disposed layer 2A. In addition, you may contain 1.0 weight% or less of MgO and CaO.

The shape retaining layer 2B contains 50 to 70% by weight of a glass component and 30 to 50% by weight of an alumina component as main components. And the shape retention layer 2B is 23 to 42% by weight of SiO ₂ , 0.25 to 3.5% by weight of B ₂ O _{3 and} 34.2 to 58.8% by weight of Al ₂ O ₃ after firing. The alkaline earth metal oxide has a composition of 12.5 to 31.5% by weight, and 60% by weight or more in the alkaline earth metal oxide (that is, 7.5 to 31.5% of the entire shape retaining layer 2B). % By weight) is SrO.

  The softening point of the coil portion arrangement layer 2A is 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 is 800 to 1050 ° C., and the softening point or melting point of the shape retaining layer 2B is 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, the coil portion arrangement layer 2A does not contain SrO. 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. In addition, since the coil portion arrangement layer 2A does not contain SrO, relatively low dielectric constant SiO ₂ can be increased, 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 retaining layer 2B contains SrO, the content of SiO ₂ is less than that of the coil portion arrangement layer 2A, and the dielectric constant is increased. 5 is not included and does not affect the Q value of the coil. The 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.

  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. The coil conductors 4 and 5 are formed of a conductor paste containing, for example, one of silver, copper, and nickel as a main component. The coil part 3 is arrange | positioned only inside the coil part arrangement | positioning layer 2A, and is not arrange | positioned in the shape-retaining layer 2B. Further, none of the coil conductors 4 and 5 of the coil portion 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 connected in the stacking direction by through-hole conductors. Further, the coil conductor 5 relating to the lead-out portion is configured by a conductor pattern that pulls the end of the winding pattern to the external electrode 6. In addition, the coil pattern of the winding part, the number of windings, the drawing position of the drawing part, etc. are not particularly limited.

  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, for example, by screen-printing a conductor paste containing silver, copper, or nickel as a main component, or by using a dip method.

  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 and a ceramic green sheet for forming the shape retaining layer 2B are 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.

  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. Here, each conductor pattern and each through-hole electrode are formed by screen printing using a conductive paste containing silver or nickel.

  Subsequently, each ceramic green sheet is laminated. At this time, the ceramic green sheet to be the coil portion arrangement layer 2A is stacked on the ceramic green sheet to be the shape retaining layer 2B, and the ceramic green sheet to be the shape retaining layer 2B is 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 fired at a predetermined temperature (for example, about 800 to 1150 ° C.) to form the element body 2. The firing temperature set at this time 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.

  Next, the operation and effect of the multilayer coil component 1 according to this embodiment will be described.

  In order to increase the quality factor (Q) value of the coil, it is preferable to increase the smoothness of the surface of the coil conductor. The higher the frequency, the shallower the skin depth. In the case of a high frequency, the smoothness of the surface of the coil conductor affects the Q value. For example, as shown in FIG. 2B, 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. 2A, the surface resistance of the coil conductor is lowered, and the Q value of the coil can be increased.

  In order to increase the smoothness of the surface of the coil conductor, it is effective to make the ceramic of the element body amorphous. As shown in FIG. 3A, when the element body is crystalline, the unevenness of the surface of the coil conductor in contact therewith increases due to the influence of the unevenness of the surface of the element body, and the smoothness becomes low. On the other hand, as shown in FIG. 3B, when the element body is amorphous, the surface of the coil conductor in contact with the element body becomes smooth due to the influence of the smooth surface of the element body, and the smoothness increases. .

  Here, when reducing the softening point in order to make the element body amorphous, the inventors round the shape of the element body by softening the entire element body as shown in FIG. As a result, it was found that the shape could not be maintained. Therefore, as a result of intensive studies, the present inventors have found the configuration of the multilayer coil component 1 according to the present embodiment.

  That is, in the multilayer coil component 1 according to the present embodiment, 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 that sandwiches the coil part arrangement layer 2A. Have. Since the shape retaining layer 2B is made of glass ceramic containing SrO, the softening point is increased. On the other hand, since the coil portion arrangement layer 2A is amorphous, the softening point is set lower than the softening point or melting point of the shape-retaining layer 2B. Since the coil portion arrangement layer 2A having the softening point lowered in this manner is sandwiched between the shape-retaining layers 2B, the shape is maintained without being rounded during firing. Here, when the material for increasing the softening point is, for example, MgO or CaO, which diffuses from the shape retaining layer 2B to the coil portion arrangement layer 2A during firing, the coil portion arrangement layer 2A is softened. The point cannot be lowered and cannot be made amorphous. However, since SrO has a characteristic of not diffusing, it is possible to prevent the softening point of the coil portion arranging layer 2A from increasing due to diffusion from the shape retaining layer 2B during firing. Thereby, coil part arrangement | positioning layer 2A can be reliably made amorphous. By making the coil portion arrangement layer 2A amorphous as described above, the surface smoothness of the coil conductors 4 and 5 can be improved, and the Q value of the multilayer coil component 1 can be increased.

  In this embodiment, the element body is not completely non-poisonous but contains a small amount of alumina component (0.5 to 2.4% by weight). Therefore, a smooth surface as shown in FIG. As described above, the term “amorphous” as used herein corresponds to a part containing a crystalline substance in a small amount.

  FIG. 5A is an enlarged photograph showing the state of the coil conductor and the element body of the multilayer coil component according to the comparative example, and FIG. 5B is the coil conductor and element of the multilayer coil component according to the example. It is an enlarged photograph showing the state of the body.

In the multilayer coil component according to the comparative example, the element body is crystalline. As shown in FIG. 5 (a), in the comparative example, the smoothness of the coil conductor is lowered because the element body is crystalline. The laminated coil component according to the comparative example is manufactured by the following materials and manufacturing conditions. That is, the coil portion arrangement layer of the multilayer coil component according to the comparative example contains 70% by weight of the glass component and 30% by weight of the alumina component as the main components. And, after firing, a coil portion disposed layer of the multilayer coil component according to the comparative _example, B 2 _{O 3} 1.5 wt%, the MgO 2.1 wt%, the _Al 2 _{O 3} 37 wt%, SiO ₂ 32 wt%, the CaO 4 wt%, SrO 22% by weight, containing BaO 0.21 wt%. The laminated coil component according to the comparative example does not have a shape retaining layer. Further, Ag is adopted as the material of the coil conductor. The firing temperature is set to 900 ° C.

On the other hand, the multilayer coil component according to the example has an amorphous body. As shown in FIG.5 (b), in the Example, the smoothness of a coil conductor is high because an element | base_body becomes amorphous. This makes it possible to achieve a high Q value. In addition, the laminated coil component which concerns on an Example is manufactured by the following materials and manufacturing conditions. That is, the coil portion arrangement layer of the multilayer coil component according to the example has 60% by weight of the borosilicate glass component, 20% by weight of the quartz component, 20% by weight of the amorphous silica component, and 1.% of the alumina component as the main components. Contains 5% by weight. After firing, the multilayer coil component according to the _embodiment, B 2 _{O 3} 10.2 wt%, the _Al 2 _{O 3} 1.2 wt%, a SiO ₂ 87.5 wt%, the _{K 2} O 1 .Contains 1% by weight. The shape-retaining layer of the multilayer coil component according to the example contains 70% by weight of a glass component and 30% by weight of an alumina component as main components. After firing, the shape-retaining layer of the multilayer coil component according to the example is 1.5% by weight of B ₂ O ₃ , 2.1% by weight of MgO, 37% by weight of Al ₂ O ₃ , and 32% of SiO ₂ . It contains 4% by weight of CaO, 4% by weight of CaO, 22% by weight of SrO, and 0.21% by weight of BaO. Further, Ag is adopted as the material of the coil conductor. The firing temperature is set to 900 ° C.

  The present invention is not limited to the embodiment described above.

  For example, in the above-described embodiment, the laminated coil component having one coil part is illustrated, but for example, it may have a plurality of coil parts 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 (1)

An element body formed by laminating a plurality of insulator layers;
A coil portion formed inside the element body by a plurality of coil conductors,
The prime field is
A coil part arrangement layer in which the coil part is arranged;
A shape retaining layer that is provided at least in a pair so as to sandwich the coil portion arrangement layer, and maintains the shape of the coil portion arrangement layer,
The shape-retaining layer contains an alkaline earth metal oxide and is 60% by weight or more in the alkaline earth metal oxide and 7.5 to 31.5% by weight of the entire shape-retaining layer. Made of glass ceramic containing
The coil part arrangement layer contains 86.7 to 92.5% by weight of SiO ₂ and 0.5 to 2.4% by weight of Al ₂ O ₃ ,
A laminated coil component, wherein a softening point of the coil portion arrangement layer is lower than a softening point or a melting point of the shape retaining layer.