Abstract:
The purpose of the present invention is to provide a component in which inductors and capacitors necessary for a low-pass filter and the like can be mounted at high density, and to in turn reduce the size of an electronic control unit in which the component is installed. The electronic control unit is characterized in that: the electronic control unit is provided with a laminated capacitor having built-in circuit patterns and dielectric bodies; the circuit patterns comprise a laminated plurality of coil effect generation patterns and inter-layer connection patterns for series connection of the plurality of coil effect generation patterns; and at least some of the plurality of coil effect generation patterns are used as electrodes for the laminated capacitor.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to an electronic control unit for controlling an in-vehicle device or a capacitor mounted in the electronic control unit. 
       BACKGROUND ART 
       [0002]    Conventionally, in order to control a car, many electronic control units are incorporated in the car. As described in PTL 1, since a mechanical driving device such as an engine and a transmission, and a battery are incorporated in the limited vehicle space, the space available for the electronic control unit is limited. In order to reduce the size of the electronic control unit, the volume of components and structural members of the electronic circuit have to be reduced. When the electronic circuit is miniaturized, it is difficult to keep ground stability as the density of the plated circuit increases, and there is concern about measures against noise, and measures to suppress noise is also required. 
         [0003]    Generally known measures against noise are to provide a low-pass filter and a small coil for constituting the filter. Examples of the small coil include a coil element as in PTL 2, in which four patterns of layers are prepared, laminated, and connected with each other through via holes to generate and laminate a coil loop, and as in PTL 3, an inductance element incorporating a coil winding and a capacitor. 
       CITATION LIST 
     Patent Literature 
       [0004]    PTL 1: JP 2011-192599 A 
         [0005]    PTL 2: WO 2011/155240 A 
         [0006]    PTL 3: JP 2006-54207 A 
       SUMMARY OF INVENTION 
     Technical Problem 
       [0007]    In the method of PTL 2, when a low-pass filter is mounted, four patterns of layers are required to form the coil loop. Accordingly, mounting of the filter involves an increase in mounting area. On the other hand, in the coil of PTL 3, since the capacitor necessary for the low-pass filter is formed in a pattern different from that of the coil winding, there is a concern about the increasing mounting area when a large number of capacitors are formed together with inductance elements. 
         [0008]    The present invention is made in view of the above problems, and an object of the present invention is to provide a component which allows an inductance element and a capacitor necessary for a low-pass filter or the like to be mounted with high density. Its object is further to miniaturize the electronic control unit in which the component is mounted. 
       Solution to Problem 
       [0009]    In order to solve the present invention, an electronic control unit according to the present invention includes a laminated capacitor incorporating a circuit pattern and a dielectric body, the circuit pattern including: a plurality of coil effect generation patterns that are laminated; and an inter-layer connection pattern being configured such that the plurality of coil effect generation patterns are connected to each other in series, wherein at least part of the plurality of coil effect generation patterns serves as an electrode of the laminated capacitor. 
       Effects of Invention 
       [0010]    According to the present invention, the application of a coil pattern in a laminated capacitor inside which a plurality of electrodes are laminated allows the coil pattern and the capacitor pattern required for forming the low-pass filter to be mounted in one component with high density, and the miniaturization of the electronic control unit can be further accomplished. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0011]      FIG. 1  is an explanatory view of a basic structure of a conventional electronic control unit. 
           [0012]      FIG. 2  is an explanatory view of a manufacturing process of a laminated ceramic capacitor. 
           [0013]      FIG. 3  is a cross-sectional view of the laminated ceramic capacitor. 
           [0014]      FIG. 4  is an explanatory view of a printing pattern of the present invention. 
           [0015]      FIG. 5  is a view illustrating hole positions in a perforation process. 
           [0016]      FIG. 6  is an explanatory view of electrode paste movement. 
           [0017]      FIG. 7  is an explanatory view of paste movement. 
           [0018]      FIG. 8  is an explanatory view of misalignment of a spiral pattern. 
           [0019]      FIG. 9  is an explanatory view of misalignment of a solid pattern. 
           [0020]      FIG. 10  is a view showing a method of increasing and decreasing a coil capacity and a capacitor capacitance. 
           [0021]      FIG. 11  is an application example of the present invention. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0022]    Hereinafter, an embodiment in which a coil pattern is incorporated in a laminated capacitor used for an electronic control unit for controlling an in-vehicle device will be described with reference to drawings. 
         [0023]      FIG. 1  shows a basic structure of a conventional electronic control unit (ECU)  102 . The electronic control unit includes a main body case  110 , a connector  101  for connecting with an external device, and a printed circuit board  104 . Electronic parts such as an IC  103 , capacitors  107 , and resistors  105  are mounted on the printed circuit board  104 . The packaging area of the board differs depending on the specification of the electronic control unit. In the present embodiment, for the sake of simplicity, description is made with reference to  FIG. 1 . In the electronic control unit  102 , the printed circuit board  104  includes a large number of capacitors  107  in order to prevent or reduce various noises received from external devices and external harnesses. 
         [0024]    Although the conventional configuration and capacitors of the conventional electronic control unit  102  have been described above, in general, laminated ceramic capacitors with compactness and large capacitance are employed in order to reduce the volume of the electronic control unit  102 . Next, a method of manufacturing the laminated ceramic capacitor will be described with reference to  FIG. 2 . 
         [0025]    The first process for the laminated ceramic capacitor is sheet formation  201 . A dielectric material sheet made of a slurry dielectric material composed of barium titanate or the like (ceramic material), and having a thickness of about 1 μm, for example, is produced. 
         [0026]    The second process is electrode printing  202 . In thick film printing technology, for example an electrode made of nickel paste is printed on the dielectric material sheet. While the number of repetition of the first process and the second process varies depending on the capacitance of the capacitor, hereinafter description will be made assuming that the number of repetition is 600. 
         [0027]    In the press process  203  as the third process, 600 layers of the sheets produced by the first process and the second process, which have been repeated 600 times, are laminated in the same direction and pressed in the lamination direction to produce a laminated ceramic with a large area. 
         [0028]    In cutting  204  as the fourth process, the cutting is made along the printed electrode pattern so as to produce small sized laminated ceramic capacitors. 
         [0029]    The fifth process is firing  205 . In the sixth process, terminal electrode paste coating  206  is applied, and the capacitor is completed as a component. 
         [0030]      FIG. 3  is a cross-sectional view of the laminated ceramic capacitor. In order to increase the capacitance of the capacitor, the electrodes made of each layer are alternately laminated, and dielectric sheets  303  are sandwiched between the layers. The internal electrodes each having a positive terminal  301  or a negative terminal  302  are alternately laminated and connected to the respective external electrodes. In  FIG. 3 , the electrode area of the capacitor can be increased as the number of layers is increased in a limited volume, and thus the capacitance can be increased. 
         [0031]    The present invention utilizes the characteristics of the laminated ceramic capacitor, and a perforation process is added to the manufacturing process of the laminated ceramic capacitor, and a spiral pattern is employed for the laminated ceramic capacitor. Accordingly, it is possible to secure a capacitor capacitance and a coil capacity, thereby accomplishing a laminated capacitor which can performs characteristics of a low-pass filter. 
         [0032]      FIGS. 4 and 5  illustrate a printing pattern of the laminated capacitor of the present invention and a fabrication process of the printing pattern. 
         [0033]    In order to generate capacitors one by one, the conventional electrode has a simple pattern, like the electrode indicated by the electrode printing  202 , which is the second process of  FIG. 2 , wherein the printing pattern is alternately printed on the dielectric sheet A layer and on the dielectric sheet B layer (one dielectric sheet is for terminal and the other dielectric sheet is for ground). 
         [0034]    In the process of the electrode printing  202  of  FIG. 2 , according to the present invention, a spiral pattern  406  is printed on the dielectric sheet A layer  402  as shown in FIG.  4 . On the dielectric sheet B layer  403 , a pattern for coil series connection  404  and a solid pattern for ground  405  for connecting multiple layers of the spiral pattern in series are printed. These ways forms a coil in the laminated capacitor. 
         [0035]    A perforation process is added before the electrode printing process so that each spiral pattern  406 , which will constitute a coil layer, is connected in series wherein layers of the spiral pattern sandwich the dielectric sheet B layer  403 . As shown in  FIG. 5 , a hole  503  is opened in the dielectric sheet A layer  402  so that the pattern for coil series connection  404  of the dielectric sheet B layers can be mutually connected. Further, in order to connect the solid pattern for ground provided on a plurality of layers in parallel to each other, a through hole for ground  504  is opened. In order to make the outlet of the spiral pattern leading to the outside of the laminated capacitor, where the plurality of layers of the spiral pattern are connected in series to each other, a hole  502  passing through the last layer of the 600 layers is opened. After the additional perforation process, the spiral pattern  406  is printed on the dielectric sheet A layer  402 , and the pattern for coil series connection  404  and the solid pattern for ground  405  are printed on the dielectric sheet B layer  403 . 
         [0036]    In this way, in the present invention, since the spiral pattern  406  on the plurality of layers are electrically connected in series to each other, the solid pattern for ground  405  on the plurality of layers are electrically connected in parallel to each other, and the spiral pattern  406  and the solid pattern for ground  405  are laminated, the spiral pattern  406  forms one electrode of the capacitor in a range where the spiral pattern  406  overlaps the solid pattern for ground  405  in the stacking direction. The solid pattern for ground  405  serves as an electrode on the ground side of the capacitor and creates the effect of the capacitor. As a result, the spiral pattern  406  can serve as both a pattern for creating the effect of the coil and a pattern for creating the effect of the capacitor, and it is possible to mount with high density the coil and capacitor necessary for the low-pass filter. 
         [0037]    Further, utilizing the pressurization characteristics of the press process  203 , the adhesive electrode paste may be connected to the lower layer via a previously opened hole as shown by  601  in the drawing. By taking advantage of these characteristics, it is possible to accomplish the characteristics of coil series connection by connecting a plurality of spiral patterns in series. 
         [0038]    Further, utilizing the characteristic that the tensile strength of the electrode paste is limited, a narrow pattern  701  shown in  FIG. 7  is provided between the hole  501  and the hole  505 . When the pattern  701  is pressed, the electrode paste is pressed, the electrode paste is moved to the lower layer through the hole, and the narrow pattern is disconnected, the hole  501  and the hole  505  can form a path such that the disconnected narrow pattern is insulated to each other. 
         [0039]    Further, the solid pattern for ground  405  is not necessarily a solid pattern, and may be a pattern of spiral patterns having the same shape as the spiral pattern  406  so as to overlap the spiral pattern  406 . However, when the two spiral patterns are misaligned as shown in  FIG. 8 , a deviation occurs for the capacitor capacitance, because the capacitance of the capacitor depends on the area in which the stacked electrodes overlaps. 
         [0040]    Therefore, it is desirable to employ a solid pattern or a thicker pattern than the spiral pattern  406  as shown in  FIG. 9  for the ground layer, which is the dielectric sheet B layer. In the case where the dielectric sheet A layer  402  uses the same shaped spiral pattern as the dielectric sheet B layer  403 , there is an advantage that the mask for electrode printing can be formed in one type. However, if the misalignment as indicated in  FIG. 8  occurs, the area which can serve as capacitor capacitance is limited to an area indicated by  801 . In the case of a solid pattern, the area indicated by  901  in  FIG. 9  serves as the capacitor capacitance. 
         [0041]    The additional process (perforation) and pattern design described as mentioned above allows the laminated capacitor which has the built-in coil pattern to be formed. 
         [0042]    Furthermore, since the coil capacity is determined by the density and the series number of the spiral line, and the capacitor capacitance is determined by the area of the electrode area and the interlayer distance, the number of turns of the spiral pattern  406  per dielectric sheet A layer  402 , and the number of series connections of the coil composed of the dielectric sheet A layer  402  and the dielectric sheet B layer  403  makes it possible to change the capacity of the coil as shown in  FIG. 10 . 
         [0043]    By adjusting the thickness (area) of the pattern of the spiral pattern  406  and the number of parallel connections, the capacitance of the capacitor can also be adjusted. In addition, it is possible to adjust the capacitance of the capacitor by providing a dielectric sheet that does not print the electrode between the spiral pattern  406  and the pattern for ground to adjust the distance between the electrodes. 
         [0044]    The number of series connections of the spiral pattern  406  and the number of parallel connections of the solid pattern for ground  405  can be appropriately adjusted not only by adjusting the number of laminated dielectric sheets themselves but also by providing a pattern without the electrode printed and the like. 
         [0045]    Utilizing the mechanism of the capacitor with a built-in coil pattern, other circuit patterns can be incorporated in the capacitor as shown in  FIG. 11 . This can reduce a work load of the wiring on the board. 
         [0046]    In addition, as shown in  FIG. 11 , a plurality of LC circuits may be provided in one laminated capacitor package wherein the LC circuit is required for each terminal of IC. For example, for each of the plurality of LC circuits, the number of windings, the area and the number of connections of the spiral pattern  406 , the number of dielectric sheets which do not print the electrode, and the number of parallel connections of the solid pattern for ground  405  may be individually varied. In this manner, a plurality of coils and capacitors having different inductances and different capacitor capacitances can be formed in one laminated capacitor package and connected to terminals of the IC and the like. As a result, input output circuits of the IC and the like can be mounted with high density. 
       REFERENCE SIGNS LIST 
       [0000]    
       
           102  electronic control unit 
           107  capacitor 
           406  spiral pattern 
           405  solid pattern for ground 
           404  pattern for coil series connection