Patent Publication Number: US-2022216586-A1

Title: Chip antenna and manufacturing method thereof

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit under 35 USC 119(a) of Korean Patent Application No. 10-2021-0000885 filed in the Korean Intellectual Property Office on Jan. 5, 2021, the entire disclosure of which is incorporated herein by reference for all purposes. 
     BACKGROUND 
     1. Field 
     The present disclosure relates to a chip antenna and a manufacturing method thereof. 
     2. Description of the Background 
     A 5G communication system is realized in higher frequency (mmWave) bandwidths, for example, the bandwidths of 10 GHz to 100 GHz so as to achieve higher data rates. To reduce a propagation loss of RF signals and increase a transmission distance, beamforming, large scale multiple-input multiple-output (MIMO), full dimensional multiple-input multiple-output, an array antenna, analog beamforming, and large scale antenna schemes are being discussed in the 5G communication system field. 
     The current mobile communication traffic in the world is predicted to increase by an annual average of 53%, and the core industry of the fourth industrial revolution, such as the Internet of things (IoT), autonomous vehicles, virtual reality (VR), robots, and big data require a huge volume of data, so the 5G communication appears necessary. 
     In the earlier stages of the 5G service, a specific hotspot-based service is expected to be gradually developed into a wide area service securing mobility without limits of places and areas. In particular, regarding the wide area service securing mobility, a base station increases the using number of macro cells and small cells, and a terminal requires high-power transmission and receiving for allowing middle and long distance transmission and receiving, so a large number of array antennae are expected to be used. 
     However, terminal down-sizing issues will continue, so reducing the size and increasing the antenna efficiency is needed. Therefore, chip antenna modules small enough to be installed in mobile communication terminals and appropriate for the GHz bandwidth are required. 
     The above information is presented as background information only to assist with an understanding of the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the disclosure. 
     SUMMARY 
     This Summary is provided to introduce a selection of concepts in simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter. 
     In one general aspect, a chip antenna includes a substrate having a concavo-convex pattern on a surface thereof, and a conductor pattern disposed on the surface of the substrate having the concavo-convex pattern, wherein a convex portion extending in one direction and a concave portion extending in one direction are alternately disposed in the concavo-convex pattern. 
     The concavo-convex pattern may have a wave shape. 
     A difference in height between the convex portion and the concave portion adjacent to the convex portion may be 3 μm to 10 μm. 
     A height deviation of the convex portion may be less than or equal to 1 μm. 
     A height deviation of the concave portion may be less than or equal to 1 μm. 
     A distance between the convex portion and the concave portion adjacent to the convex portion may be 100 μm to 460 μm. 
     A surface roughness (Ra) of the substrate with the concavo-convex pattern may be greater than 0.39 μm. 
     The concavo-convex pattern may have waviness with a width of 1000 μm to 5000 μm and a height of 2 μm to 9 μm. 
     The convex or concave portion of the concavo-convex pattern may extend in a direction parallel to one edge of the substrate. 
     The convex or concave portion of the concavo-convex pattern may extend in a direction diagonal to one edge of the substrate. 
     Both surfaces or a plurality of surfaces of the substrate may have the concavo-convex pattern. 
     Adhesion between the substrate and the conductor pattern may be greater than 76.5 kgf. 
     In another general aspect, a chip antenna includes a first substrate, a second substrate disposed to face the first substrate, a first conductor pattern disposed on one surface of the first substrate and configured to operate as a feeding patch, and a second conductor pattern disposed on the second substrate and configured to operate as a radiation patch, wherein the first substrate, the second substrate, or both have a concavo-convex pattern on at least one surface thereof, and wherein a convex portion extending in one direction and a concave portion extending in one direction are alternately disposed in the concavo-convex pattern. 
     The convex or concave portion of the concavo-convex pattern may extend in a direction parallel to one edge of the first or second substrate. 
     The convex or concave portion of the concavo-convex pattern may extend in a direction diagonal to one edge of the first or second substrate. 
     In another general aspect, a manufacturing method of a chip antenna includes forming a concavo-convex pattern on one side of a substrate, and forming a conductor pattern on one surface of the substrate on which the concavo-convex pattern is formed, wherein a convex portion extending in one direction and a concave portion extending in one direction are alternately disposed in the concavo-convex pattern. 
     In the forming of the concavo-convex pattern, the concavo-convex pattern may be formed by using a wire saw. 
     A wire diameter of the wire saw may be 0.20 mm or less. 
     The forming of the conductor pattern may include applying a composition for forming a conductor pattern on one surface of the substrate on which the concavo-convex pattern is formed and then sintering the composition for forming the conductor pattern. 
     The composition for forming the conductor pattern may be contracted while being sintered. 
     Other features and aspects will be apparent from the following detailed description, the drawings, and the claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates a perspective view of a chip antenna according to an embodiment of the present disclosure. 
         FIG. 2  illustrates a perspective view of a chip antenna according to another embodiment of the present disclosure. 
         FIG. 3  illustrates a side view of the chip antenna of  FIG. 2 . 
         FIG. 4  illustrates a cross-sectional view of the chip antenna taken along line IV-IV of  FIG. 2 . 
         FIG. 5  illustrates a perspective view of a chip antenna according to another embodiment of the present disclosure. 
         FIG. 6  illustrates a perspective view of a chip antenna according to another embodiment of the present disclosure. 
         FIG. 7  illustrates a side view of the chip antenna of  FIG. 6 . 
         FIG. 8  illustrates a cross-sectional view of the chip antenna taken along line VIII-VIII of  FIG. 6 . 
         FIG. 9  illustrates a partial exploded perspective view of a chip antenna according to another embodiment of the present disclosure. 
         FIG. 10  illustrates a partial exploded perspective view of a chip antenna according to another embodiment of the present disclosure. 
         FIG. 11  illustrates a perspective view of a chip antenna according to another embodiment of the present disclosure. 
         FIG. 12  illustrates a cross-sectional view of the chip antenna taken along line X-X of FIG. 
         FIG. 13  illustrates a manufacturing process diagram of a manufacturing method of a chip antenna according to another embodiment of the present disclosure. 
         FIG. 14  illustrates a graph of results of analyzing a surficial concavo-convex pattern of a substrate prepared in Preparation Example 1. 
         FIG. 15  illustrates a graph of results of analyzing a surficial concavo-convex pattern of a substrate prepared in Comparative Preparation Example 1. 
     
    
    
     Throughout the drawings and the detailed description, the same reference numerals refer to the same elements. The drawings may not be to scale, and the relative sizes, proportions, and depictions of elements in the drawings may be exaggerated for clarity, illustration, and convenience. 
     DETAILED DESCRIPTION 
     Hereinafter, while example embodiments of the present disclosure will be described in detail with reference to the accompanying drawings, it is noted that examples are not limited to the same. 
     The following detailed description is provided to assist the reader in gaining a comprehensive understanding of the methods, apparatuses, and/or systems described herein. However, various changes, modifications, and equivalents of the methods, apparatuses, and/or systems described herein will be apparent after an understanding of this disclosure. For example, the sequences of operations described herein are merely examples, and are not limited to those set forth herein, but may be changed as will be apparent after an understanding of this disclosure, with the exception of operations necessarily occurring in a certain order. Also, descriptions of functions and constructions that would be well known in the art may be omitted for increased clarity and conciseness. 
     The features described herein may be embodied in different forms, and are not to be construed as being limited to the examples described herein. Rather, the examples described herein have been provided merely to illustrate some of the many possible ways of implementing the methods, apparatuses, and/or systems described herein that will be apparent after an understanding of this disclosure. 
     Herein, it is noted that use of the term “may” with respect to an example or embodiment, for example, as to what an example or embodiment may include or implement, means that at least one example or embodiment exists in which such a feature is included or implemented while all examples and embodiments are not limited thereto. 
     Throughout the specification, when an element, such as a layer, region, or substrate, is described as being “on,” “connected to,” or “coupled to” another element, it may be directly “on,” “connected to,” or “coupled to” the other element, or there may be one or more other elements intervening therebetween. In contrast, when an element is described as being “directly on,” “directly connected to,” or “directly coupled to” another element, there can be no other elements intervening therebetween. As used herein “portion” of an element may include the whole element or a part of the whole element less than the whole element. 
     As used herein, the term “and/or” includes any one and any combination of any two or more of the associated listed items; likewise, “at least one of” includes any one and any combination of any two or more of the associated listed items. 
     Although terms such as “first,” “second,” and “third” may be used herein to describe various members, components, regions, layers, or sections, these members, components, regions, layers, or sections are not to be limited by these terms. Rather, these terms are only used to distinguish one member, component, region, layer, or section from another member, component, region, layer, or section. Thus, a first member, component, region, layer, or section referred to in examples described herein may also be referred to as a second member, component, region, layer, or section without departing from the teachings of the examples. 
     The terminology used herein is for describing various examples only, and is not to be used to limit the disclosure. The articles “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms “comprises,” “includes,” and “has” specify the presence of stated features, numbers, operations, members, elements, and/or combinations thereof, but do not preclude the presence or addition of one or more other features, numbers, operations, members, elements, and/or combinations thereof. 
     Spatially relative terms such as “above,” “upper,” “below,” “lower,” and the like may be used herein for ease of description to describe one element&#39;s relationship to another element as illustrated in the figures. Such spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, an element described as being “above” or “upper” relative to another element will then be “below” or “lower” relative to the other element. Thus, the term “above” encompasses both the above and below orientations depending on the spatial orientation of the device. The device may also be oriented in other ways (for example, rotated 90 degrees or at other orientations), and the spatially relative terms used herein are to be interpreted accordingly. 
     Due to manufacturing techniques and/or tolerances, variations of the shapes illustrated in the drawings may occur. Thus, the examples described herein are not limited to the specific shapes illustrated in the drawings, but include changes in shape that occur during manufacturing. 
     The features of the examples described herein may be combined in various ways as will be apparent after an understanding of this disclosure. Further, although the examples described herein have a variety of configurations, other configurations are possible as will be apparent after an understanding of this disclosure. 
     One aspect of the present disclosure is to provide a chip antenna and a manufacturing method thereof that may improve close-contacting force or adhering force between a ceramic substrate and a metal conductor pattern. 
     A chip antenna module described in the present specification is operable in a radio frequency region, for example, it may be operated in a frequency bandwidth of equal to or greater than 3 GHz, and for example, it may be operated in the bandwidth of 20 GHz to 60 GHz. The chip antenna module may be installed in an electronic device for receiving or transmitting RF signals. For example, the chip antenna may be installed in a portable phone, a portable laptop, or a drone. 
       FIG. 1  illustrates a perspective view of a chip antenna according to an embodiment. 
     Referring to  FIG. 1 , a chip antenna  100  according to the present embodiment includes a substrate  110 , and a conductor pattern  120  disposed on one surface of the substrate  110 . 
     The substrate  110  may be made of a polymer or ceramic sintered body having a predetermined dielectric constant. For example, the substrate  110  may be made of a material having a relatively high dielectric constant, such as a ceramic-based material such as a low temperature co-fired ceramic (LTCC) or a glass-based material, and it may have a higher dielectric constant or stronger durability by further containing at least one of magnesium (Mg), silicon (Si), aluminum (Al), calcium (Ca), and titanium (Ti). 
     The substrate  110  has a concavo-convex pattern  1110  on one surface thereof. However, the present disclosure is not limited thereto, and the substrate  110  may have concavo-convex patterns  1110  on both surfaces or on a plurality of surfaces. 
     The concavo-convex pattern  1110  is formed by alternately disposing a convex portion  1111  extending in one direction and a concave portion  1112  extending in one direction. Accordingly, the concavo-convex pattern  1110  may have a wavy shape as a whole. 
     The convex portion  1111  may be protruded upward in a thickness direction of the substrate  110 , that is, in a positive z-axis direction in  FIG. 1 , and the concave portion  1112  may be recessed downward in the thickness direction of the substrate  110 , that is, in a negative z-axis direction in  FIG. 1 . 
     The convex portion  1111  and the concave portion  1112  extend in one direction, for example, in a y-axis direction in  FIG. 1 . For example, the convex portion  1111  or the concave portion  1112  of the concavo-convex pattern  1110  may extend in a direction parallel to one edge of the substrate  110  or in a diagonal direction to one edge of the substrate  110 . A specific example of this will be described later. 
     A direction in which the convex portion  1111  extends and a direction in which the concave portion  1112  extends may be substantially parallel. However, the present disclosure is not limited thereto, and an angle formed by the direction in which the convex portion  1111  extends and the direction in which the concave portion  1112  extends may be less than ±90 degrees, less than or equal to ±60 degrees, less than or equal to ±30 degrees, less than or equal to ±20 degrees, or less than or equal to ±10 degrees. 
     The substrate  110  may include a plurality of convex portions  1111  and a plurality of concave portions  1112  that are alternately disposed. In this case, directions in which respective convex portions  1111  extend may be substantially parallel. However, the present disclosure is not limited thereto, and an angle formed by the direction in which one convex portion  1111  extends and the direction in which another convex portion  1111  extends may be less than ±90 degrees, less than or equal to ±60 degrees, less than or equal to ±30 degrees, less than or equal to ±20 degrees, or less than or equal to ±10 degrees. In addition, directions in which respective concave portions  1112  extend may be substantially parallel. However, the present disclosure is not limited thereto, and an angle formed by the direction in which one concave portion  1112  extends and the direction in which another concave portion  1112  extends may be less than ±90 degrees, less than or equal to ±60 degrees, less than or equal to ±30 degrees, less than or equal to ±20 degrees, or less than or equal to ±10 degrees. 
     The convex portion  1111  may be defined as a portion having a value of greater than a mean line on one cut surface, and the concave portion  1112  may be defined as a portion having a value of smaller than the mean line in one cut surface. 
     Here, the cut surface may be one cut surface that intersects all of the convex portions  1111  and the concave portions  1112  to be measured, and for example, may be one of xz cut surfaces in  FIG. 1 . The mean line is a straight line where a sum of squares of a deviation up to an unfiltered profile is minimum, and the unfiltered profile is referred to as a contour of the concavo-convex pattern on the cut surface. 
     As the convex portions  1111  and the concave portions  1112  of the concavo-convex pattern  1110  are alternately disposed, a height difference L 1  between the convex portion  1111  and the concave portion  1112  adjacent to the convex portion  1111  may be 3 μm (microns) to 10 μm, for example, 2 μm to 7 μm, or 4 μm to 5 μm. 
     The height difference L 1  between the convex portion  1111  and the concave portion  1112  may be obtained from a difference between a highest height of the convex portion  1111  and a lowest height of the concave portion  1112 , the highest height of the convex portion  1111  may be obtained from a largest value among distances between the unfiltered profile and the mean line that form the convex portion  1111  on one cut surface, and the lowest height of the concave portion  1112  may be obtained from a largest value among distances between the unfiltered profile and the mean line that form the concave portion  1112  on one cut surface. 
     When the height difference L 1  between the convex portion  1111  and the concave portion  1112  is less than 3 μm, adhesion may decrease due to a decrease in anchoring effect, and when it is greater than 10 μm, horizontality may be deteriorated. 
     The height deviation of the convex portion  1111  may be 1 μm or less, for example, 0 μm to 0.8 μm, or 0.2 μm to 0.5 μm. 
     The height deviation of the convex portion  1111  may be obtained from a difference between a highest height of the convex portion  1111  on one cut surface and a highest height of the convex portion  1111  in another cut surface. Here, the two cut surfaces may be two arbitrarily selected cut surfaces, and for example, the one cut surface may be a cut surface in which roughness of the convex portion  1111  is largest, and the other cut surface may be a cut surface in which roughness of the convex portion  1111  is smallest. 
     When the height deviation of the convex portion  1111  is greater than 1 μm, the horizontality of the substrate may be deteriorated. 
     The height deviation of the concave portion  1112  may be 1 μm or less, for example, 0 μm to 0.8 μm, or 0.2 μm to 0.5 μm. 
     The height deviation of the concave portion  1112  may be obtained from a difference between a lowest height of the concave portion  1112  on one cut surface and a lowest height of the concave portion  1112  in another cut surface. Here, the two cut surfaces may be arbitrarily selected as two cut surfaces, and for example, the one cut surface may be a cut surface in which roughness of the concave portion  1112  is largest, and the other cut surface may be a cut surface in which roughness of the concave portion  1112  is smallest. 
     When the height deviation of the concave portion  1112  is greater than 1 μm, the horizontality of the substrate may be deteriorated. 
     A distance L 2  between the convex portion  1111  and the concave portion  1112  adjacent to the convex portion  1111  may be 100 μm to 460 μm, for example, 120 μm to 450 μm, or 130 μm to 300 μm. The distance L 2  between the convex portion  1111  and the concave portion  1112  may be obtained from a distance between the highest height of the convex portion  1111  and the lowest height of the concave portion  1112  on one cut surface. When the distance L 2  between the convex portion  1111  and the concave portion  1112  is less than 100 μm, there may be difficulties in processing time and processing conditions, and when it is greater than 460 μm, the number of protrusions and depressions is small, so that the anchoring effect is small, and thus the adhesion may be deteriorated. 
     In the substrate provided with the concavo-convex pattern, a centerline surface roughness Ra may be greater than 0.39 μm, for example, 0.40 μm or more, 0.50 μm or more, 0.60 μm or more, 0.70 μm or more, or 0.77 μm or more, and may be 1.00 μm or less, for example, 0.90 μm or less, 0.80 μm or less, or 0.77 μm or less, and may be greater than 0.39 μm and 1.00 μm or less, for example, 0.50 μm to 0.90 μm, or 0.60 μm to 0.80 μm. 
     The centerline average roughness Ra may be calculated by Equation 1 below. 
     
       
         
           
             
               
                 
                   
                     R 
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                     a 
                   
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                       L 
                     
                     × 
                     
                       
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                         0 
                         L 
                       
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                             f 
                             ⁡ 
                             
                               ( 
                               x 
                               ) 
                             
                           
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                         dx 
                       
                     
                   
                 
               
               
                 
                   ( 
                   
                     Equation 
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                     ⁢ 
                     1 
                   
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     In Equation 1, L is a length measured in a predetermined direction, and f (x) is a height based on a center line of the concavo-convex pattern at a predetermined position on a surface of the substrate  110 . 
     In other words, the center line average roughness Ra is a mean height from the centerline to the unfiltered profile, and the centerline (arithmetic mean line of profile) is parallel to the mean line and is a straight line at a position where upper and lower areas surrounded by the unfiltered profile become the same. 
     The concavo-convex pattern  1110  of the substrate  110  may have waviness. The waviness is a deviation from abnormal surfaces that are repeated at a greater interval and depth compared with roughness. In  FIG. 1 , the waviness is included between a first convex portion  1111   a  and a second convex portion  1111   b . That is, after the first convex portion  1111   a , the highest heights of the convex portions  1111  gradually decrease, and after the lowest point, the highest heights of the convex portions  1111  gradually increase, and then the highest point becomes at the second convex portion  1111   b , and then the highest heights of the convex portions  1111  again gradually decrease. 
     A width L 4  of the waviness may be 1000 μm to 5000 μm, for example, 1000 μm to 3000 μm, or 3000 μm to 5000 μm. The width L 4  of the waviness is a distance between the first convex portion  1111   a  and the second convex portion  1111   b . When the width L 4  of the waviness is less than 1000 μm, the horizontal degree may be deteriorated, and when it is greater than 5000 μm, there may be difficulties in processing conditions. 
     A height L 3  of the waviness may be 1 μm to 6 μm, for example, 1 μm to 3 μm, or 4 μm to 6 μm. The height L 3  of the waviness is a height difference between a first concave portion  1112   a , which has a lowest height within the width L 4  of the waviness and the second convex portion  1111   b . When the height L 3  of the waviness is less than 1 μm, processing conditions may be difficult, and when it is greater than 6 μm, the horizontal degree may be deteriorated. 
     The conductor pattern  120  may be made of a conductor made of Ag, Au, Cu, Al, Pt, Ti, Mo, Ni, W, or an alloy thereof. 
     The conductor pattern  120  may be formed of a flat plate-shaped metal having a certain area. For example, the conductor pattern  120  may be formed in a quadrangular shape. However, the conductor pattern  120  may be formed in various shapes such as a polygonal shape and a circular shape according to embodiments. 
     The adhesion between the substrate  110  and the conductor pattern  120  may be greater than 76.5 kgf, for example 100 kgf to 400 kgf, 202.4 kgf to 351.4 kgf, 207.6 kgf to 351.4 kgf, 212.4 kgf to 351.4 kgf, 221.0 kgf to 351.4 kgf, 228.5 kgf to 351.4 kgf, 231.9 kgf to 351.4 kgf, 240.9 kgf to 351.4 kgf, 250.7 kgf to 351.4 kgf, 254.9 kgf to 351.4 kgf, or 279.4 kgf to 351.4 kgf. 
     Since the substrate  110  has the concavo-convex pattern  1110  on one side thereof, a contact area between the substrate  110  and the conductor pattern  120  increases, so that the adhesion between the substrate  110  and the conductor pattern  120  may be improved. In addition, the conductor pattern  120  may be manufactured by applying a metal paste and then sintering it, and in this case, the metal paste may shrink when sintering the metal paste. Therefore, the concavo-convex pattern  1110  of the substrate  110  may enhance the anchoring effect when the metal paste shrinks, thereby improving the adhesion between them.  FIG. 2  illustrates a perspective view of a chip antenna according to another embodiment of the present disclosure,  FIG. 3  illustrates a side view of the chip antenna of  FIG. 2 , and  FIG. 4  illustrates a cross-sectional view of the chip antenna taken along line IV-IV of  FIG. 2 . 
     Referring to  FIG. 2 ,  FIG. 3 , and  FIG. 4 , the chip antenna  100  may include a first substrate  110   a , a second substrate  110   b , and a first conductor pattern  120   a , and may include at least one of a second conductor pattern  120   b  and a third conductor pattern  120   c.    
     The first substrate  110   a  and the second substrate  110   b  may be disposed to be spaced apart from each other. Accordingly, a space between the first substrate  110   a  and the second substrate  110   b  may be filled with air or a medium having a dielectric constant lower than the dielectric constant of the first substrate  110   a  and the second substrate  110   b.    
     The first substrate  110   a , the second substrate  110   b , or both may be provided with the concavo-convex pattern  1110  on at least one surface thereof. In  FIG. 2 , by allowing the direction in which the convex portion of the concavo-convex pattern  1110  extends to be a straight line, the concavo-convex pattern  1110  is simplified and shown.  FIG. 2  illustrates that the convex portion of the concavo-convex pattern  1110  extends in a direction parallel to one edge of the first substrate  110   a  and the second substrate  110   b , that is, the y-axis direction. 
     The first conductor pattern  120   a  is formed of a flat plate-shaped metal with a certain area. The first conductor pattern  120   a  is formed in a quadrangular shape. However, in some embodiments, it may be formed in various shapes such as a polygonal shape and a circular shape. The first conductor pattern  120   a  may be connected to a feeding via  131  to function and operate as a feed patch. 
     The second conductor pattern  120   b  and the third conductor pattern  120   c  are disposed to be spaced apart from the first conductor pattern  120   a  by a predetermined distance, and are formed of a flat plate-shaped metal having a certain area. The second conductor pattern  120   b  and the third conductor pattern  120   c  have the same area as or a different area from the first conductor pattern  120   a . For example, the second conductor pattern  120   b  and the third conductor pattern  120   c  may be formed to have a smaller area than the first conductor pattern  120   a  to be disposed on the first conductor pattern  120   a . For example, the second conductor pattern  120   b  and the third conductor pattern  120   c  may be formed to be 5% to 8% smaller than the first conductor pattern  120   a . For example, thicknesses of the first conductor pattern  120   a , the second conductor pattern  120   b , and the third conductor pattern  120 C may be 20 μm. 
     The second conductor pattern  120   b  and the third conductor pattern  120   c  are electromagnetically coupled to the first conductor pattern  120   a , so that they may function and operate as radiation patches. The second conductor pattern  120   b  and the third conductor pattern  120   c  further concentrate an RF signal in the z-axis direction corresponding to a mounting direction of the chip antenna  100  to improve a gain or bandwidth of the first conductor pattern  120   a . The chip antenna  100  may include at least one of the second conductor pattern  120   b  and the third conductor pattern  120   c  that function as a radiation patch. 
     Meanwhile, in some embodiments, a passivation layer formed in a form of a film along a surface of each of the first conductor pattern  120   a , the second conductor pattern  120   b , and the third conductor pattern  120   c  may be additionally formed on the first conductor pattern  120   a , the second conductor pattern  120   b , and the third conductor pattern  120   c . The passivation layer may be formed on the surface of each of the first conductor pattern  120   a , the second conductor pattern  120   b , and the third conductor pattern  120   c  through a plating process. The passivation layer may be formed by sequentially stacking a nickel (Ni) layer and a tin (Sn) layer, or sequentially stacking a zinc (Zn) layer and a tin (Sn) layer. The passivation layer is formed on each of the first conductor pattern  120   a , the second conductor pattern  120   b , and the third conductor pattern  120   c , so that oxidation of the first conductor pattern  120   a , the second conductor pattern  120   b , and the third conductor pattern  120   c  may be prevented. In addition, the passivation layer may be formed along surfaces of a feeding pad  130 , a feeding via  131 , a bonding pad  140 , and a spacer  150 , which will be described later. 
     As illustrated, the second substrate  110   b  may have a thickness less than that of the first substrate  110   a . A thickness of the first substrate  110   a  may correspond to 1 to 5 times, for example, 2 to 3 times, the thickness of the second substrate  110   b . For example, the thickness of the first substrate  110   a  may be 150 μm to 500 μm, the thickness of the second substrate  110   b  may be 100 μm to 200 μm, and the thickness of the second substrate  110   b  may be 50 μm to 200 μm. Unlike the above-described example, the second substrate  110   b  may have the same thickness as the first substrate  110   a.    
     The first conductor pattern  120   a  is provided on one surface of the first substrate  110   a , and the feeding pad  130  is provided on the other surface of the first substrate  110   a  opposite the one surface. At least one feeding pad  130  may be provided on the other surface of the first substrate  110   a . A thickness of the feeding pad  130  may be about 20 μm. 
     The feeding pad  130  provided on the other surface of the first substrate  110   a  is electrically connected to a feeding pad provided on one surface of a substrate. The feeding pad  130  may be electrically connected to the feeding via  131  penetrating the first substrate  110   a  in a thickness direction, and the feeding via  131  may provide a feeding signal to the first conductor pattern  120   a  provided on the one surface of the first substrate  110   a . At least one feeding via  131  may be provided. For example, two feeding vias  131  may be provided so as to correspond to two feeding pads  130 . One of the two feeding vias  131  corresponds to a feeding line for generating vertical polarization, and the other thereof corresponds to a feeding line for generating horizontal polarization. A diameter of the feeding via  131  may be about 150 μm. The bonding pad  140  is provided on the other surface of the first substrate  110   a . The bonding pad  140  allows the chip antenna  100  to be bonded to a chip antenna module substrate. A thickness of the bonding pad  140  may be about 20 μm. 
       FIG. 5  illustrates a perspective view of a chip antenna according to another embodiment. 
     Since the chip antenna according to the present embodiment is similar to the chip antenna described above, duplicate descriptions will be omitted, and differences will be mainly described. 
       FIG. 2  illustrates that the convex portion of the concavo-convex pattern  1110  extends in a direction parallel to one edge of the first substrate  110   a  and the second substrate  110   b , that is, the y-axis direction, while  FIG. 5  illustrates that the convex portion of the concavo-convex pattern  1110  extends diagonally to one edge of the first substrate  110   a  and the second substrate  110   b.    
       FIG. 6  illustrates a perspective view of a chip antenna according to another embodiment of the present disclosure,  FIG. 7  illustrates a side view of the chip antenna of  FIG. 6 , and  FIG. 8  illustrates a cross-sectional view of the chip antenna taken along line VIII-VIII of  FIG. 6 . 
     Since the chip antenna according to the present embodiment is similar to the chip antenna described above, duplicate descriptions will be omitted, and differences will be mainly described. 
       FIG. 2  illustrates that the first substrate  110   a  and the second substrate  110   b  of the chip antenna  100  are disposed to be separated from each other through the spacer  150 , while  FIG. 6  illustrates that the first substrate  110   a  and the second substrate  110   b  of the chip antenna  100  are mutually bonded through a bonding layer  155 . In  FIG. 6 , it may be understood that the bonding layer  155  is provided in a space formed by a gap between the first substrate  110   a  and the second substrate  110   b  of  FIG. 2 . 
     The bonding layer  155  may be formed to cover one surface of the first substrate  110   a  and the other surface of the second substrate  110   b , facing the one surface of the first substrate  110   a , to entirely bond the first substrate  110   a  and the second substrate  110   b . The bonding layer  155  may be formed of, for example, a polymer, and for example, the polymer may include a polymer sheet. A dielectric constant of the bonding layer  155  may be lower than that of the first substrate  110   a  and the second substrate  110   b . For example, the dielectric constant of the bonding layer  155  may be a dielectric constant at 28 GHz, and a thickness of the bonding layer  155  may be 50 μm to 200 μm. 
       FIG. 9  and  FIG. 10  illustrate partial exploded perspective views of a chip antenna according to another embodiment. 
     Since the chip antenna according to the present embodiments is similar to the chip antenna described above, duplicate descriptions will be omitted, and differences will be mainly described. 
     In the embodiment shown in  FIG. 6 , the bonding layer  155  is formed to cover the entire surface of the first substrate  110   a  to entirely bond the first substrate  110   a  and the second substrate  110   b , while in the embodiments shown in  FIG. 9  and  FIG. 10 , the bonding layer  155  may have a cavity  156  to surround the first conductor pattern  120   a , and the cavity  156  may provide a dielectric medium (for example, air) that is lower than the dielectric constant of the bonding layer  155 , so that a bandwidth and gain may be further improved compared with a size of the chip antenna  100 . 
     Since a dimension or shape of the cavity  156  may affect a resonance frequency or performance of the chip antenna  100 , the chip antenna  100  has a structure that reduces a phenomenon that the dimension or shape of the cavity  156  deviates from a designed dimension or shape during the manufacturing process, so that more stable performance thereof may be realized. 
     In addition, since the bonding layer  155  may have a shorter width as the cavity  156  is provided, the bonding layer  155  may have relatively weak structural stability compared with a case in which the cavity  156  is not provided. Therefore, the chip antenna  100  has a structure that reduces factors that physically affect the bonding layer  155  during the manufacturing process, so that more stable performance may be realized. 
     Accordingly, as in the embodiment shown in  FIG. 10 , the bonding layer  155  may have a ventilation channel  157  between the cavity  156  and an outer surface of the bonding layer  155 . 
     For example, in the manufacturing process of the chip antenna  100 , when the first substrate  110   a  and the second substrate  110   b  are bonded by the bonding layer  155 , the chip antenna  100  may be subjected to stress that causes a volume change of the cavity  156 , and this stress may distort the dimension or shape of the cavity  156  or cause cracks in the first and second substrates  110   a  and  110   b.    
     The ventilation channel  157  provides an air movement path of the cavity  156  when the chip antenna  100  is subjected to the stress that causes the volume change of the cavity  156 , thereby reducing the influence of the stress on the chip antenna  100 . 
     Accordingly, the chip antenna  100  may reduce a phenomenon in which the dimension or shape of the cavity  156  deviates from the designed dimension or shape during the manufacturing process, or factors that physically affect the bonding layer  155 , so that the performance (bandwidth and gain versus size) that is improved based on the cavity  156  may be more stably obtained. 
     For example, the bonding layer  155  may include a polymer having higher adhesion than the dielectric material of the first substrate  110   a  and the second substrate  110   b . Since the adhesive polymer may have a fluid characteristic compared with a ceramic structure, although the dimension or shape of the cavity  156  may have an instability factor, since the chip antenna  100  includes the ventilation channel  157 , the cavity  156  of the bonding layer  155  including the adhesive polymer having the fluid characteristic may be stably provided. 
     For example, one outer side surface of the bonding layer  155 , one side surface of the first substrate  110   a , and one side surface of the second substrate  110   b  may form one plane. That is, the chip antenna  100  may have a shape in which the side surfaces of the structure are cut in a structure in which the bonding layer  155  is adhered to the first substrate  110   a  and the second substrate  110   b.    
     Accordingly, the ventilation channel  157  may be more stably formed, and the air movement path of the cavity  156  may be more stably provided. In addition, when a plurality of chip antennas  100  are manufactured together, the ventilation channel  157  may also serve as an air movement path between respective cavities  156  of the plurality of chip antennas  100 . 
     For example, a width of the ventilation channel  157  may be shorter than a length of a structure surrounding the cavity  156  in the bonding layer  155 , and may be shorter than a width thereof. Accordingly, since leakage of an RF signal in the horizontal direction may be further suppressed, the gain of the chip antenna  100  may be further improved. 
     For example, the ventilation channel  157  is configured in plural, and the plurality of ventilation channels  157  may be positioned to overlap each other in a ventilation direction (for example, the x-axis direction and/or y-axis direction) of the plurality of ventilation channels  157 . 
     Accordingly, air movement efficiency with respect to the width of the plurality of ventilation channels  157  may be further improved, so that the chip antenna  100  may stably obtain a high gain. In addition, the overlapping structure of the plurality of ventilation channels  157  may be more efficiently formed when a plurality of chip antennas  100  are manufactured together. 
       FIG. 11  illustrates a perspective view of a chip antenna according to another embodiment, and  FIG. 12  illustrates a cross-sectional view of the chip antenna taken along line X-X of  FIG. 11 . 
     Since the chip antenna according to the present embodiment is similar to the chip antenna described above, duplicate descriptions will be omitted, and differences will be mainly described. 
     In  FIG. 2 , the first substrate  110   a  and the second substrate  110   b  of the chip antenna  100  are disposed to be separated from each other through the spacer  150 , while in  FIG. 11 , the first substrate  110   a  and the second substrate  110   b  of the chip antenna  100  may be mutually bonded with the first conductor pattern  120   a  therebetween. 
     Specifically, the first conductor pattern  120   a  is provided on one surface of the first substrate  110   a , and the second conductor pattern  120   b  is provided on one surface of the second substrate  110   b . The first conductor pattern  120   a  provided on one surface of the first substrate  110   a  may be bonded to the other surface of the second substrate  110   b  opposite the one surface of the second substrate  110   b . Accordingly, the first conductor pattern  120   a  may be interposed between the first substrate  110   a  and the second substrate  110   b.    
       FIG. 13  illustrates a manufacturing process diagram of a manufacturing method of a chip antenna according to another embodiment. 
     Referring to  FIG. 13 , the manufacturing method of the chip antenna  100  includes forming the concavo-convex pattern  1110  on one surface of the substrate  110  ( 51 ), and forming the conductor pattern  120  on one surface of the substrate  110  on which the concavo-convex pattern  1110  is formed (S 2  and S 3 ). 
     First, the concavo-convex pattern  1110  is formed on one surface of the substrate  110  ( 51 ). 
     The concavo-convex pattern  1110  may be formed so that the convex portion  1111  extending in one direction and the concave portion  1112  extending in one direction are alternately disposed. The concavo-convex pattern  1110  may be formed by using, for example, a wire saw. As an example, the wire saw may use a wire with adsorbed diamonds. 
     Specifically, when, while passing through a wire that is reciprocated between a pair of drums, the substrate  110  is cut by the wire, and the convex portion  1111  and the concave portion  1112  extending in the direction in which the wire is reciprocated are formed, so that the concavo-convex pattern  1110  in which the convex portions  1111  and the concave portions  1112  are alternately disposed in the direction in which the substrate  110  passes through the wire may be formed. 
     In this case, the shape of the concavo-convex pattern  1110 , and the height difference and distance between the convex portion  1111  and the concave portion  1112  may be adjusted by using the diameter and reciprocating speed of the wire, the passing speed of the substrate  110 , or the tension of the wire. In addition, the waviness may be formed by eccentricity or vibration of the wire saw. 
     As an example, the diameter of the wire may be 0.20 mm or less, for example 0.18 mm or less, 0.17 mm or less, 0.16 mm or less, 0.15 mm or less, 0.14 mm or less, 0.13 mm or less, 0.12 mm or less, 0.11 mm or less, 0.10 mm or less, 0.09 mm or less, 0.08 mm or less, or may be 0.08 mm to 0.20 mm. 
     Next, a composition  121  for forming the conductor pattern is applied on the surface of the substrate  110  on which the concavo-convex pattern  1110  is formed (S 2 ). 
     The composition  121  for forming the conductor pattern may be, for example, a metal paste, and the metal may be Ag, Au, Cu, Al, Pt, Ti, Mo, Ni, W, or an alloy thereof. By using the metal paste, the conductor pattern  120  may be directly formed into the designed shape without a separate etching process. 
     The method of applying the composition  121  for forming the conductor pattern on the one surface of the substrate  110  on which the concavo-convex pattern  1110  is formed is not particularly limited in the present disclosure, and for example, a spin coating, bar coating, spray coating, slit coating, screen printing, inkjet printing, nozzle printing, spraying, or doctor blade coating method may be used. 
     Finally, the composition  121  for forming the conductor pattern is sintered to form the conductor pattern  120  (S 3 ). 
     A sintering temperature of the composition  121  for forming the conductor pattern may be 500° C. to 1000° C., and a sintering time thereof may be 1 minute to 10 hours. 
     When the sintering temperature of the composition  121  for forming the conductor pattern is less than 500° C., or when the sintering time thereof is less than 1 minute, the composition may be unsintered so that the adhesion may be deteriorated, and when the sintering temperature thereof is greater than 1000° C., or when the sintering time thereof is greater than 10 hours, the composition may be over-sintered, so that an electrode peeling phenomenon may occur. 
     In this case, the composition  121  for forming the conductor pattern may shrink by about 13 vol % to 20 vol % in direction Ds while being sintered. The concavo-convex pattern  1110  of the substrate  110  enhances the anchoring effect Da when the composition  121  for forming the conductor pattern is contracted, thereby improving the bonding strength between the substrate  110  and the conductor pattern  120 . 
     Hereinafter, specific embodiments of the present disclosure are described. However, the following described examples are only for illustrating the disclosure more specifically, and thus the scope of the disclosure should not be limited by these examples. 
     Preparation Example: Preparation of Chip Antenna 
     Preparation Example 1 
     A ceramic sintered substrate (with a size of 5 mm in width and 5 mm in length and a thickness of 50 mm) including a Mg 2 SiO 4  phase, a MgAl 2 O 4  phase, and a CaTiO 3  phase was cut by using a wire saw with a diameter of 0.08 mm under a condition of Ra 5 μm to form a concavo-convex pattern on one surface thereof. 
     A metal paste containing Ag, Pd, glass frit, and an inorganic solvent was prepared, and the metal paste was applied on the one surface of the substrate on which the concavo-convex pattern was formed, and then the metal paste was sintered to prepare a chip antenna. In this case, the metal paste is contracted by about 18 vol %. 
     Preparation Example 2 to Preparation Example 12 
     A chip antenna was prepared in the same manner as in Preparation Example 1, except that the substrate of Preparation Example 1 was cut by using wire saws having diameters of 0.09 mm, 0.11 mm, 0.10 mm, 0.12 mm, 0.13 mm, 0.14 mm, 0.15 mm, 0.16 mm, 0.17 mm, 0.18 mm, and 0.20 mm, respectively. 
     Comparative Preparation Example 1 
     A chip antenna was prepared in the same manner as in Preparation Example 1, except that a substrate was cut under the condition of a roughness Ra of 0.5 μm by lapping without using a wire saw. 
     Experimental Example 1: Analysis of Concavo-Convex Pattern of Substrate 
     The surfaces of the substrate prepared in Preparation Example 1 and the substrate prepared in Comparative Preparation Example 1 were analyzed under conditions of 10 to 30 times magnification by using a 3D measuring laser microscope (Manufacturer: OLYMPUS, product name: OLS4000) using reflection of a laser beam, and the results are shown in  FIG. 14  and  FIG. 15 , respectively. 
     Referring to  FIG. 14  and  FIG. 15 , it can be confirmed that in the case of the substrate prepared in Preparation Example 1, the concavo-convex pattern in which the convex portion extending in one direction and the concave portion extending in one direction were alternately disposed was formed (Ra=0.77 μm, Rz=4.3 μm), while in the case of the substrate prepared in Comparative Preparation Example 1, a random surface roughness was obtained (Ra=0.39 μm, Rz=4.2 μm). 
     Experimental Example 2: Measurement of Adhesion of Substrate 
     The height difference between the convex portion and the concave portion adjacent to the convex portion, and the distance between the convex portion and the concave portion adjacent to the convex portion of the substrate prepared in Preparation Examples 1 to 12, and the substrate prepared in Comparative Preparation Example 1 were measured, and the results are summarized in Table 1. 
     In this case, the height difference between the convex portion and the concave portion adjacent to the convex portion, and the distance between the convex portion and the concave portion adjacent to the convex portion, were measured by a non-contact method under the condition of 30 times magnification by using a 3D laser microscope using a laser beam. 
     In addition, the adhesion between the substrate and the conductor pattern of the chip antenna prepared in Preparation Examples 1 to 12 and Comparative Preparation Example 1 was measured by a contact method under the condition of a speed of 500 μm/s and 5 kgf of a load cell by using a 30 μm-thick gauge pin of Dage4000plus (Manufacturer: NORDSON), and the results are also summarized in Table 1. 
     
       
         
           
               
               
               
               
               
               
             
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                   
                   
                 Height difference 
                   
                   
               
               
                   
                   
                 Distance between 
                 between convex 
               
               
                   
                 Wire 
                 convex portion 
                 portion and 
                   
                 Adhesion 
               
               
                   
                 diameter 
                 and concave 
                 concave portion 
                 Adhesion 
                 increase 
               
               
                   
                 (mm) 
                 portion (μm) 
                 (μm) 
                 (kgf) 
                 rate (%) 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
            
               
                 Preparation 
                 0.08 
                 145 
                 3 
                 351.4 
                 459 
               
               
                 Example 1 
               
               
                 Preparation 
                 0.09 
                 225 
                 4 
                 279.4 
                 365 
               
               
                 Example 2 
               
               
                 Preparation 
                 0.10 
                 250 
                 4 
                 240.9 
                 315 
               
               
                 Example 3 
               
               
                 Preparation 
                 0.11 
                 275 
                 4 
                 212.4 
                 278 
               
               
                 Example 4 
               
               
                 Preparation 
                 0.12 
                 300 
                 5 
                 254.9 
                 333 
               
               
                 Example 5 
               
               
                 Preparation 
                 0.13 
                 325 
                 5 
                 228.5 
                 299 
               
               
                 Example 6 
               
               
                 Preparation 
                 0.14 
                 350 
                 5 
                 207.6 
                 271 
               
               
                 Example 7 
               
               
                 Preparation 
                 0.15 
                 375 
                 6 
                 240.9 
                 315 
               
               
                 Example 8 
               
               
                 Preparation 
                 0.16 
                 400 
                 6 
                 221.0 
                 289 
               
               
                 Example 9 
               
               
                 Preparation 
                 0.17 
                 425 
                 7 
                 250.7 
                 328 
               
               
                 Example 10 
               
               
                 Preparation 
                 0.18 
                 450 
                 7 
                 231.9 
                 303 
               
               
                 Example 11 
               
               
                 Preparation 
                 0.20 
                 500 
                 7 
                 202.4 
                 265 
               
               
                 Example 12 
               
               
                 Comparative 
                 — 
                 — 
                  4 1)   
                 76.5 
                 100 
               
               
                 Preparation 
               
               
                 Example 1 
               
               
                   
               
               
                   1) In the case of Comparative Preparation Example 1, the difference in height between the convex portion and the concave portion was measured to have a 10-point average roughness (Rz). 
               
            
           
         
       
     
     Referring to Table 1, it can be confirmed that since the chip antennas prepared in Preparation Example 1 to Preparation Example 12 included the concavo-convex pattern formed on the substrate surface, the adhesion between the substrate and the conductor pattern was excellent compared with the chip antenna prepared in Comparative Preparation Example 1. 
     According to the chip antenna and the manufacturing method thereof as described in the embodiments herein, it is possible to improve close-contacting force or adhering force between a ceramic substrate and a metal conductor pattern by increasing a surface area of the ceramic substrate, and to improve bonding force between them by reinforcing an anchoring effect by a shrinkage behavior during sintering of the metal conductor pattern. 
     While specific example embodiments have been shown and described above, it will be apparent after an understanding of this disclosure that various changes in form and details may be made in these examples without departing from the spirit and scope of the claims and their equivalents. The examples described herein are to be considered in a descriptive sense only, and not for purposes of limitation. Descriptions of features or aspects in each example are to be considered as being applicable to similar features or aspects in other examples. Suitable results may be achieved if the described techniques are performed in a different order, and/or if components in a described system, architecture, device, or circuit are combined in a different manner, and/or replaced or supplemented by other components or their equivalents. Therefore, the scope of the disclosure is defined not by the detailed description, but by the claims and their equivalents, and all variations within the scope of the claims and their equivalents are to be construed as being included in the disclosure.