Patent Publication Number: US-2020287104-A1

Title: Package

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to China Application Serial Number 201910167401.9, filed Mar. 6, 2019, which is herein incorporated by reference in its entirety. 
     BACKGROUND 
     Field of Invention 
     The present invention relates to a package. 
     Description of Related Art 
     Light emitting diodes are devices that emit light when a forward current flows through a semiconductor P-N junction. The light emitting diodes may be made of III-V semiconductor materials, such as GaAs or GaN. Recently, due to the advances in the semiconductor epitaxial growth technique and the light emitting device processes, light emitting diodes with excellent converting efficiency have been developed. The light emitting diodes are widely used in various fields. However, due to the size of the conventional light emitting diodes, it is easy to be observed in display devices. Therefore, a new package is needed to address the problem mentioned above. 
     SUMMARY 
     The invention provides a package. The package includes a substrate and a plurality of light emitting chips. The substrate has a top surface. The light emitting chips are disposed on the top surface of the substrate. A sum of vertical projection areas of the light emitting chips on the top surface is less than 5% of an area of the top surface. 
     In accordance with an embodiment of the present invention, each of the light emitting chips is configured to emit a light with a wavelength different from each other. 
     In accordance with an embodiment of the present invention, the package further includes a wavelength conversion layer covering one of the light emitting chips solely. 
     In accordance with an embodiment of the present invention, the package further includes a driver chip disposed on the substrate and electrically connected with the light emitting chips. 
     In accordance with an embodiment of the present invention, each of the light emitting chips includes a pair of first electrical contacts, the substrate includes a plurality of pairs of second electrical contacts disposed on the top surface of the substrate, and each pair of the first electrical contacts are electrically connected with each pair of the second electrical contacts respectively. 
     In accordance with an embodiment of the present invention, the pair of the first electrical contacts of each light emitting chip are disposed at a same side of said each light emitting chip. 
     In accordance with an embodiment of the present invention, the pair of the first electrical contacts of each light emitting chip are disposed at opposite sides of said each light emitting chip. 
     The invention also provides a package. The package includes a substrate, a plurality of light emitting chips and a package layer. The substrate has a top surface and a bottom surface opposite to the top surface. The light emitting chips are disposed on the top surface of the substrate, and each of the light emitting chips has an upper surface. The package layer covers the top surface of the substrate and the upper surface of each of the light emitting chips. The package layer has a top surface. A ratio of a distance between the top surface of the substrate and the upper surface of each of the light emitting chips to a distance between the bottom surface of the substrate and the top surface of the package layer is less than 0.1. 
     In accordance with an embodiment of the present invention, a distance between the upper surface of each of the light emitting chips and the top surface of the package layer is greater than 5 times of a distance between the top surface of the substrate and the upper surface of each of the light emitting chips. 
     In accordance with an embodiment of the present invention, the package further includes a driver chip disposed on the substrate and electrically connected with the light emitting chips. 
     In accordance with an embodiment of the present invention, a distance between the top surface of the substrate and the upper surface of each of the light emitting chips is less than 10 μm. 
     The technical solution of the present invention may improve the user experience and reduce the probability of the light emitting chips being observed by users. In addition, the package herein may also increase the current density, such that the luminous efficiency of the light emitting chips is also increased. Besides, since the vertical projection area of the light emitting chips on the substrate is relatively small, the cost can be reduced and the contrast can be improved. The black area is also increased. 
     It is to be understood that both the foregoing general description and the following detailed description are by examples, and are intended to provide further explanation of the invention as claimed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention can be more fully understood by reading the following detailed description of the embodiment, with reference made to the accompanying drawings as follows: 
         FIG. 1  illustrates a top view of a package  100  according to an embodiment of the present invention; 
         FIG. 2  illustrates a cross-section view of the package  100  according to an embodiment of the present invention; 
         FIG. 3  illustrates a cross-section view of a package  100   a  according to an embodiment of the present invention; 
         FIG. 4  illustrates a cross-section view of an package  200  according to an embodiment of the present invention; and 
         FIG. 5  illustrates a cross-section view of a package  300  according to an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     The following disclosure provides many different embodiments, or examples, for implementing different features of the provided subject matter. Specific examples of components and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting. For example, the formation of a first feature over a second feature in the description that follows may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features are disposed between the first and second features, such that the first and second features are not in direct contact. 
     Further, spatially relative terms, such as “beneath,” “below,” “lower,” “above,” “upper” and the like, may be used herein for ease of description to describe one element or feature&#39;s relationship to another element(s) or feature(s) as illustrated in the figures. The 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. The apparatus may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein may likewise be interpreted accordingly. 
       FIG. 1  illustrates a top view of a package  100  according to an embodiment of the present invention.  FIG. 2  illustrates a cross-section view along a line AA′ of the package  100 . Referring to  FIG. 1 , the package  100  includes a substrate  110  and a plurality of light emitting chips  120 . In some examples, the substrate  110  may be a rectangle in the top view, such as a square. In certain examples, the substrate  110  has a side length ranging from 250 μm to 1200 μm, such as 250 μm, 500 μm, 750 μm, 1000 μm or 1200 μm. 
     The light emitting chips  120  are disposed on a top surface  111  of the substrate  110 . The sum of vertical projection areas of light emitting chips  120  on the top surface  111  is less than 5% of an area of the top surface  111  in the top view. Further, in the present invention, the area of each light emitting chip  120  is decreased such that the sum of the vertical projection areas of the light emitting chips  120  on the top surface  111  is less than 5% of the area of the top surface  111 . If the sum of vertical projection areas of the light emitting chips  120  on the top surface  111  is greater than 5% of the area of the top surface  111 , the light emitting chips  120  may be easily observed by users, thus affecting the user experience. In other words, the technical solution of the present invention may improve the user experience and reduce the probability of the light emitting chips  120  being observed by users. In addition, the maximum luminous efficiency of the light emitting chips  120 , such as light emitting diode, is achieved only in a specific current density range. However, in general, the current density is less than the above-mentioned range, and the light emitting chips can not achieve the maximum luminous efficiency. The light emitting chips  120  with small area, which may also increase the current density, is used in the present invention such that the current density falls into the range mentioned above. The luminous efficiency of the light emitting chips  120  is therefore increased. 
     In some examples, the package  100  further includes a driver chip  140  disposed on the substrate  110  and electrically connected with each of the light emitting chips  120 . The driver chip  140  is configured to control the light emitting chips  120  such that the brightness of the light emitting chips  120  is controllable. 
     In some examples, the light emitting chips  120  may be light emitting diodes (LED). In further examples, the light emitting chips  120  may be micro LEDs. In certain examples, the light emitting chips  120  emit lights having different wavelengths. For example, each light emitting chip  120  may emit primary color light, such as red light, green light or blue light. Hence, the light emitting chip  120  may be an element of a display device to display a desired color. In addition, in some examples, multiple light emitting chips  120  may constitute a pixel unit of the display device. 
     Please refer to  FIG. 2 , each light emitting chip  120  includes a pair of first electrical contacts  122 ,  124 , and the substrate  110  includes a pair of second electrical contacts  112 ,  114 . In some embodiments, the substrate  110  includes a plurality of pairs of second electrical contacts  112 ,  114 . The first electrical contacts  122 ,  124  are respectively connected with the second electrical contacts  112 ,  114 . In certain embodiments, each pair of the first electrical contacts  122 ,  124  are respectively connected with each pair of the second electrical contacts  112 ,  114 . In some examples, the second electrical contacts  112 ,  114  are disposed on the top surface  111  of the substrate  110 . Therefore, the second electrical contacts  112 ,  114  are in direct contact with the first electrical contacts  122 ,  124 , respectively. 
     In another embodiment, the package  100  further includes a package layer  160 . The package layer  160  covers the top surface  111  of the substrate  110  and an upper surface  121  of each light emitting chip  120 . In some examples, a ratio of a distance X1 between the top surface  111  of the substrate  110  and the upper surface  121  of each light emitting chip  120  to a distance X2 between a bottom surface  113  of the substrate  110  and a top surface  165  of the package layer  160  is less than 0.1 (X1/X2&lt;0.1). 
     In some examples, the package layer  160  includes a first insulating layer  161  and a second insulating layer  162 . The first electrical contacts  122  of the light emitting chips  120  are surrounded and covered by the first insulating layer  161 . The second insulating layer  162  is disposed on the first insulating layer  161  and covers the light emitting chips  120 . The first insulating layer  161  may be used as an insulator between adjacent ones of the first electrical contacts  122 ,  124 . The package layer  160  having a two-layer structure may better bond the light emitting chips  120  to the substrate  110 . In detail, the first insulating layer  161  may completely fill the gap between the first electrical contacts  122 ,  124 , and the second insulating layer  162  may completely cover the first insulating layer  161  and the light emitting chips  120 . 
     Besides, in some examples, a distance X3 between the upper surface  121  of each of the light emitting chips  120  and the top surface  165  of the package layer  160  is greater than 5 times of the distance X1 between the top surface  111  of the substrate  110  and the upper surface  121  of each of the light emitting chips  120 . In some examples, the distance X1 between the top surface  111  of the substrate  110  and the upper surface  121  of each of the light emitting chips  120  is less than 10 μm, such as 8 μm, 7 μm, 6 μm or 5 μm. 
     The light emitting chips  120  disposed on the substrate  110  herein have a specific thickness. As a result, the total thickness and the size of the package are decreased so as to decrease the cost. Besides, the present invention may also be applied to miniaturized display devices. 
     As mentioned above, the light emitting chips  120  may emit lights with different wavelengths. Thus, in some examples, the light emitting chips  120  may be different light emitting diodes, such as a red light emitting diode, a green light emitting diode and a blue light emitting diode. 
     In addition, please refer to  FIG. 3 , which illustrates a cross-section view of a package  100   a  according to an embodiment of the present invention. The package  100   a  further includes a wavelength conversion layer  130  covering at least one of the light emitting chips  120 . In some embodiments, the wavelength conversion layer  130  covers one of the light emitting chips  120  solely. The light emitting chips  120  are the same-typed light emitting diodes, therefore emit lights with the same wavelength. Since the lights emitted from the light emitting chips  120  pass through the different wavelength conversion layers  130 , the lights become different colors (different wavelengths). In some examples, the different wavelength conversion layers  130  respectively cover the light emitting chips  120 . 
     The present invention also provides a package  200 . Please refer to  FIG. 4 , which illustrates a cross-section view of a package  200  according to an embodiment of the present invention. Different from the package  100 , the first electrical contacts  122 ,  124  of the light emitting chip  120  of the package  200  are disposed on the upper surface  121  of the light emitting chip  120 . In some examples, the package  200  includes a conductive layer  150  extending from the first electrical contacts  122 ,  124  to the second electrical contacts  112 ,  114  of the substrate  110 . Further, the conductive layer  150  extends along a sidewall  123  of the light emitting chip  120 , and each of the light emitting chips  120  is electrically connected with the substrate  110  through the conductive layer  150 . 
     Please refer to  FIG. 5 , which illustrates a cross-section view of a package  300  according to an embodiment of the present invention. Different from the package  100  and the package  200 , first electrical contacts  322 ,  324  of a light emitting chip  320  of the package  300  are disposed at the opposite sides of the light emitting chip  320 . In detail, the first electrical contact  322  is disposed on a bottom surface  323  of the light emitting chip  320 , and the first electrical contact  324  is disposed on an upper surface  321  of the light emitting chip  320 . Hence, in the present example, the first electrical contact  322  of light emitting chip  320  is in direct contact with the second electrical contact  112  of the substrate  110 , and the first electrical contact  324  is electrically connected with the second electrical contact  114  through the conductive layer  350 . 
     Therefore, in some examples of the present invention, such as the examples illustrated in  FIGS. 2-4 , the first electrical contacts  122 , 124  of the light emitting chip  120  are disposed at the same side of the light emitting chip  120 . In other examples, such as the example illustrated in  FIG. 5 , the first electrical contacts  322 ,  324  of the light emitting chip  320  may be disposed at the opposite sides of the light emitting chip  320 . The aforementioned examples are merely exemplary and are not intended to be limited. Any suitable packages can be used, depending on demands. 
     The technical solution of the present invention may improve the user experience and reduce the probability of the light emitting chips being observed by users. In addition, the package herein may also increase the current density, such that the luminous efficiency of the light emitting chips is also increased. Besides, since the vertical projection area on the substrate of the light emitting chip is relatively small, the cost can be reduced and the contrast can be improved. The black area is also increased. 
     Although the present invention has been described in considerable detail with reference to certain embodiments thereof, other embodiments are possible. Therefore, the spirit and scope of the appended claims should not be limited to the description of the embodiments contained herein. It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the present invention without departing from the scope or spirit of the invention. In view of the foregoing, it is intended that the present invention cover modifications and variations of this invention provided they fall within the scope of the following claims.