Abstract:
A light-emitting diode (LED) package including a rectangular carrier, an LED chip, and an encapsulant is provided. The rectangular carrier has an upper surface. The LED chip is mounted on the upper surface and is electrically connected to the rectangular carrier. The encapsulant has a curved convex surface and covers the entire upper surface and the LED chip. The encapsulant is doped with a phosphor material for converting at least parts of light emitted from the LED chip. The encapsulant doped with the phosphor material is visually neon orange when the LED chip does not emit the light.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims the priority benefits of Taiwan application serial no. 104110882, filed on Apr. 2, 2015, and Chinese application serial no. 201510433655.2, filed on Jul. 22, 2015. The entirety of each of the above-mentioned patent applications is hereby incorporated by reference herein and made a part of this specification. 
       FIELD OF THE DISCLOSURE 
       [0002]    The invention relates to a light-emitting device. In particular, the invention relates to a light-emitting diode (LED) package. 
       DESCRIPTION OF RELATED ART 
       [0003]    With progress in semiconductor technologies, a light-emitting diode (LED) now has advantages of high luminance and satisfactory color rendering property, low power consumption, compactness, low driving voltage, mercury free, etc.; therefore, the LED has been extensively applied in the fields of displays, vehicle illumination, and so on. For instance, in case of the vehicle illumination, the LED can be applied not only to headlight and tail light but to turn signals. The turn signals of vehicles are required to have colors (e.g., orange-yellow) other than white; hence, how to manufacture the LED with high power and stable color-displaying performance is one of the main concerns of researchers. 
       SUMMARY 
       [0004]    The invention is directed to a light-emitting diode (LED) package that includes an encapsulant whose height-to-width ratio is appropriate. 
         [0005]    In an embodiment of the invention, an LED package including a rectangular carrier, an LED chip, and an encapsulant is provided. The rectangular carrier has an upper surface. The LED chip is mounted on the upper surface and is electrically connected to the rectangular carrier. The encapsulant covers the upper surface and the LED chip. The encapsulant is doped with a phosphor material for converting a wavelength of at least parts of light emitted from the LED chip. The encapsulant has a curved convex surface and covers the entire upper surface. When the LED chip does not emit the light, the encapsulant doped with the phosphor material is visually neon orange. 
         [0006]    According to an embodiment of the invention, in a thickness direction of the encapsulant, a maximum height from the curved convex surface to the upper surface is H, a width of the encapsulant is W, and a ratio of H to W is within a range from 0.05 to 0.5. 
         [0007]    According to an embodiment of the invention, the rectangular carrier includes a rectangular circuit board, for instance. 
         [0008]    According to an embodiment of the invention, the LED chip is electrically connected to the rectangular carrier by flip-chip-bonding, for instance. 
         [0009]    According to an embodiment of the invention, a width of the encapsulant is equal to a length of one side of the rectangular carrier or equal to a length of a diagonal of the rectangular carrier. 
         [0010]    According to an embodiment of the invention, a distance between the curved convex surface and the upper surface gradually increases from an edge of the rectangular carrier to a center of the rectangular carrier. 
         [0011]    According to an embodiment of the invention, an included angle between the curved convex surface and the upper surface exists at an edge of the rectangular carrier and is an acute angle, and the acute angle is within a range from 5 degrees to 75 degrees. 
         [0012]    According to an embodiment of the invention, an edge of the encapsulant is aligned to an edge of the rectangular carrier. 
         [0013]    According to an embodiment of the invention, a peak wavelength (λ p ) of the light emitted from the light-emitting diode chip is between 435 nanometers and 475 nanometers, and a peak wavelength (λ p ) of light emitted by exciting the phosphor material is between 570 nanometers and 630 nanometers. 
         [0014]    According to an embodiment of the invention, the light emitted by the phosphor material accounts for more than 90% in the LED package. 
         [0015]    According to an embodiment of the invention, the light emitted from the LED chip and light emitted by exciting the phosphor material are mixed to obtain orange-yellow light. A CIE 1931 chromo coordinate (x,y) of the mixed light satisfies following conditions, for instance: 
         [0000]        y≦x 6−0.120;
 
         [0000]        y≧ 0.390; and 
         [0000]        y≧ 0.790−0.670 x.  
 
         [0016]    In an embodiment of the invention, an LED package including a rectangular carrier, an LED chip, and an encapsulant is provided. The rectangular carrier has an upper surface. The LED chip is mounted on the upper surface and is electrically connected to the rectangular carrier. The encapsulant covers the upper surface and the LED chip. The encapsulant is doped with a phosphor material for converting at least 90% of first light emitted from the LED chip into second light. A wavelength of the first light is shorter than a wavelength of the second light. The encapsulant covers the entire upper surface, and a dominant wavelength of light obtained by mixing the first light with the second light is between 585 nanometers and 595 nanometers. 
         [0017]    In an embodiment of the invention, an LED package including a rectangular carrier, an LED chip, and an encapsulant is provided. The rectangular carrier has an upper surface. The LED chip is mounted on the upper surface and is electrically connected to the rectangular carrier. The encapsulant covers the upper surface and the LED chip. The encapsulant is doped with a phosphor material for converting first light into second light, and the encapsulant covers the entire upper surface. A CIE 1931 chromo coordinate (x,y) of light generated by mixing the first light with the second light satisfies following conditions: 
         [0000]        y≦x− 0.120; 
         [0000]        y≧ 0.390; and 
         [0000]        y≧ 0.790−0.670 x.  
 
         [0018]    In view of the above, the encapsulant of the LED package provided herein has the curved convex surface and entirely covers the upper surface of the rectangular carrier. Said design allows the bonding area between the encapsulant and the rectangular carrier to be increased, thus enhancing the device reliability of the LED package. In an embodiment of the invention, the encapsulant is doped with the phosphor material which allows most of the first light emitted from the LED chip to be converted into the second light, so as to obtain the orange-yellow light. Thereby, the LED package can be better applied for the purpose of vehicle illumination. 
         [0019]    In order to make the aforementioned and other features and advantages of the disclosure more comprehensible, several embodiments accompanied with figures are described in detail below. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0020]    The accompanying drawings are included to provide a further understanding of the disclosure, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the disclosure and, together with the description, serve to explain the principles of the disclosure. 
           [0021]      FIG. 1  is a schematic cross-sectional view illustrating a light-emitting diode (LED) package according to an embodiment of the invention. 
           [0022]      FIG. 2  is a schematic three-dimensional view illustrating an LED package according to an embodiment of the invention. 
           [0023]      FIG. 3  illustrates a spectrum of an LED package according to an embodiment of the invention. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0024]      FIG. 1  is a schematic cross-sectional view illustrating a light-emitting diode (LED) package according to an embodiment of the invention.  FIG. 2  is a schematic three-dimensional view illustrating an LED package according to an embodiment of the invention.  FIG. 3  illustrates a spectrum of an LED package according to an embodiment of the invention. 
         [0025]    With reference to  FIG. 1  to  FIG. 3 , an LED package  100  provided herein includes a rectangular carrier  110 , an LED chip  120 , and an encapsulant  130 . The rectangular carrier  110  has an upper surface  110   a . The LED chip  120  is mounted on the upper surface  110   a  and is electrically connected to the rectangular carrier  110 . The encapsulant  130  covers the upper surface  110   a  of the rectangular carrier  110  and the LED chip  120 , so as to convert first light L 1  emitted from the LED chip into second light L 2 . Note that a wavelength of the first light L 1  is shorter than a wavelength of the second light L 2 . In the present embodiment, the entire upper surface  110   a  of the rectangular carrier  110  is covered by the encapsulant  130 . The encapsulant  130  has a curved convex surface  130   a . In a thickness direction T of the encapsulant  130 , a maximum height from the curved convex surface  130   a  to the upper surface  110   a  of the rectangular carrier  110  is H, a width of the encapsulant is W, and a ratio of H to W is within a range from 0.05 to 0.5. 
         [0026]    According to the present embodiment, the rectangular carrier  110  is a rectangular circuit board, for instance. For instance, the rectangular carrier  110  may be a ceramic circuit board, a metal core printed circuit board (MCPCB), a lead frame, or any other carrier that is suitable for carrying the LED chip  120 . The rectangular carrier  110  provided in the present embodiment includes a plurality of circuit layers (not shown), for instance, and the circuit layers are suitable for being electrically connected to the LED chip  120 . Besides, the LED chip  120  is electrically connected to the rectangular carrier  110  by flip-chip-bonding, for instance. Particularly, a conductive bump B may be formed on the LED chip  120  or on the rectangular carrier  110  according to the present embodiment, such that the LED chip  120  may be electrically connected to the rectangular carrier  110  via the conductive bump B. 
         [0027]    As shown in  FIG. 1 , in addition to the upper surface  110   a , the rectangular carrier  110  has a bottom surface  110   b  opposite to the upper surface  110   a , and the circuit layers in the rectangular carrier  110  can be distributed onto the upper surface  110   a , the bottom surface  110   b , and the inside of the rectangular carrier  110 . In most cases, the circuit layers on the upper surface  10   a  include a plurality of bonding pads BP electrically connected to the LED chip  120 , and the circuit layers on the bottom surface  110   b  include a plurality of outer contacts OT. The circuit layers (e.g., conductive vias) distributed into the rectangular carrier  110  can be applied to connect the bonding pads BP and the outer contacts OT. Thereby, the LED package  100  can be arranged on other circuit carriers through the outer contacts OT distributed onto the bottom surface  110   b  of the rectangular carrier  110 , such that the LED chip  120  can be electrically connected to other circuit carriers. For instance, the LED package  100  provided in the present embodiment can be a surface mount device (SMD), and the outer contacts OT can be directly fixed onto the circuit carriers via solder. 
         [0028]    As shown in  FIG. 1  and  FIG. 2 , the outer shape of the encapsulant  130  provided in the present embodiment is different from that of the lens portion of the conventional LED chip package. Specifically, although the encapsulant  130  has the curved convex surface  130   a , the outer profile of the curved convex surface  130   a  is the same as the outer profile of the rectangular carrier  110 ; that is, the edge of the encapsulant  130  is aligned to the edge of the rectangular carrier  110 . According to the present embodiment, the maximum width W max  of the encapsulant  130  is equal to a length of a diagonal of the rectangular carrier  110 , and the minimum width W min  of the encapsulant  130  is equal to a length of one side of the rectangular carrier  110 . For instance, the minimum width W min  of the encapsulant  130  is equal to a length of a short side of the rectangular carrier  110 . 
         [0029]    As shown in  FIG. 1 , a distance between the curved convex surface  130   a  and the upper surface  110   a  of the rectangular carrier  110  gradually increases from the edge of the rectangular carrier  110  to the center of the rectangular carrier  110 . Besides, an included angle between the curved convex surface  130   a  and the upper surface  110   a  exists at the edge of the rectangular carrier  110  and is an acute angle θ, and the acute angle θ is within a range from 5 degrees to 75 degrees, for instance. 
         [0030]    The encapsulant  130  provided in the present embodiment is silicone doped with a phosphor material  132 , for instance, and a dopant concentration of the phosphor material  132  is within a range from 50% to 60%, for instance. The external quantum efficiency of the encapsulant  130  is within a range from 61% to 63%, for instance. A peak wavelength (λ p ) of the first light L 1  emitted from the LED chip  120  is between 435 nanometers and 475 nanometers, for instance. Besides, second light L 2  is generated after the first light L 1  excites the phosphor material  132 , and a peak wavelength (λ p ) of the second light L 2  emitted by exciting the phosphor material  132  is between 570 nanometers and 630 nanometers, for instance. Here, the peak wavelength (λ p ) of the first light L 1  emitted from the LED chip  120  is defined as a corresponding wavelength of the first light L 1  with the maximum intensity according to the spectrum of the first light L 1 , and the peak wavelength (λ p ) of the second light L 2  emitted from the phosphor material  132  is defined as a corresponding wavelength of the second light L 2  with the maximum intensity according to the spectrum of the second light L 2 . That is, the LED chip  120  may be a blue LED chip, and the phosphor material  132  is capable of being excited by blue light and emitting orange-yellow light. Besides, the first light L 1  emitted from the LED chip  120  is mostly (e.g., at least 90%) converted into the second light L 2 ; therefore, the second light L 2  emitted by exciting the phosphor material  132  accounts for more than 90% in the LED package  100 , and the first light L 1  emitted from the LED chip  120  accounts for less than 10%, as shown by the spectrum in  FIG. 3 , for instance. In the present embodiment, the phosphor material  132  is Ca x Eu y (Si,Al) 12 (O,N) 16 , for instance, wherein x is within a range from 0 to 2.5, and y is within a range from 0.01 to 0.2. Preferably, x is 1.67, and y is 0.08, for instance; additionally, the peak wavelength (λ p ) of the second light L 2  emitted by exciting the phosphor material  132  is between 599 nanometers and 610 nanometers, for instance. 
         [0031]    In the present embodiment, a dominant wavelength (λ d ) of the light obtained by mixing the first light L 1  (emitted from the LED chip  120 ) with the second light L 2  (emitted by exciting the phosphor material  132 ) is between 585 nanometers and 595 nanometers, for instance. Here, after the first light L 1  and the second light L 2  are mixed, the dominant wavelength (λ d ) of the mixed light can be calculated according to the chromo coordinate of the mixed light and the chromo coordinate of a reference illuminant (e.g., an equal-energy white light point W E ). The way to calculate the dominant wavelength (λ d ) is elaborated below. 
         [0032]    Here, the equal-energy white light point W E  with the chromo coordinate (0.3333, 0.3333) in the CIE 1931 chromaticity diagram serves as a reference illuminant. Given that the point S represents the light generated by mixing the first light L 1  with the second light L 2  and has the chromo coordinate (x,y), the point W E  and the point S are connected and extended to be intersected with the spectrum locus at a point λ d . The corresponding wavelength of the point λ d  (with the chromo coordinate (x d ,y d )) on the spectrum locus is the dominant wavelength (λ d ). 
         [0033]    According to the present embodiment, the first light L 1  emitted from the LED chip  120  and the second light L 2  emitted by exciting the phosphor material  132  in the encapsulant  130  are mixed to obtain orange-yellow light. The CIE 1931 chromo coordinate (x,y) of the mixed orange-yellow light satisfies following conditions, for instance: 
         [0000]        y≦x− 0.120; 
         [0000]        y≧ 0.390; and 
         [0000]        y≧ 0.790−0.670 x.  
 
         [0034]    To sum up, the encapsulant of the LED package provided herein has the curved convex surface and entirely covers the upper surface of the rectangular carrier. Said design allows the bonding area between the encapsulant and the rectangular carrier to be increased, thus enhancing the device reliability of the LED package. Moreover, according to the embodiments provided above, the encapsulant is doped with the phosphor material which allows most of the first light emitted from the LED chip to be converted into the second light. The first light is mixed with the second light to obtain the orange-yellow light. Thereby, the LED package can be better applied for the purpose of vehicle illumination. 
         [0035]    It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the disclosed embodiments without departing from the scope or spirit of the disclosure. In view of the foregoing, it is intended that the disclosure cover modifications and variations of this disclosure provided they fall within the scope of the following claims and their equivalents.