Light emitting device package and method of manufacturing the same

A light emitting device package includes a base, a light emitting element, a mask, metal wires, an encapsulating layer and a cover layer. The base has a first surface bearing electrical structure thereon and an opposite second surface. The mask is arranged on the first surface to define a space receiving the light emitting element. Two openings are defined in the mask. The light emitting element has two pads exposed to an outside through the two openings respectively. The metal wires electrically connect the pads and the electrical structures. The encapsulating layer is filled in the space and two through holes in the base and encapsulates the light emitting element. The encapsulating layer is separated from the metal wires. The cover layer covers and protects the mask and the metal wires. A method of manufacturing the package is also provided.

BACKGROUND

1. Technical Field

The present disclosure relates generally to light emitting devices, and more particularly to a package of light emitting device and a method of manufacturing the package.

2. Description of Related Art

Light emitting diodes (LEDs) are solid state light emitting devices formed of semiconductors, which are more stable and reliable than other conventional light sources such as incandescent bulbs. Thus, LEDs are being widely used in various fields such as numeral/character displaying elements, signal lights, light sources for lighting and display devices. When in use, providing LEDs in packages can provide protection, color selection, focusing and the like for light emitted by the LEDs.

A typical LED package includes a base, an LED chip, and an encapsulating layer. The LED chip is electrically connected to electrical structures on the base via gold wires. The encapsulating layer encapsulates the LED chip. Generally, in the process of encapsulating, the encapsulating layer covers the LED chip by a technique of molding. However, the LED chip and gold wires are prone to damage during the process of molding. Thus, a reliability of the LED chip and electrical connection between the LED chip and the gold wires is impaired. The LED package has a risk of failing to work due to the damage to the LED chip or the electrical connection between the LED chip and the gold wires.

What is needed therefore is a light emitting device package and a method of packaging a light emitting device which can overcome the above mentioned limitations.

DETAILED DESCRIPTION

Referring toFIG. 10, a light emitting device package in accordance with an embodiment of the present disclosure is illustrated. The light emitting device package comprises a base10, a light emitting element20mounted on the base10, a mask30covering the light emitting element20, metal wires40electrically connecting to the light emitting element20and the base10, an encapsulating layer50encapsulating the light emitting element20, and a cover layer60covering the mask30and the metal wires40to protect them from damage or injury.

The base10has a first surface101and a second surface102opposite to the first surface101. Two or more through holes12are defined in the base10and extend through the first and second surfaces101,102. The through holes12function as passages to receive the encapsulating layer50. The number of the through holes12can be altered according to an actual requirement. The shape of each of the through holes12in a top view can be round, rectangular, etc. The through holes12can be positioned around the light emitting element20in a matrix, or in a circle. Electrical structures14are formed on the first surface101around the through holes12. The electrical structures14comprise at least two terminals141.

The light emitting element20is mounted on the first surface101of the base10, and surrounded by the through holes12. The light emitting element20can be a light emitting diode (LED), a laser diode and/or other semiconductor lighting devices which include one or more semiconductor layers, which may include silicon, silicon carbide, gallium nitride and/or other semiconductor materials. In the present embodiment, the light emitting element20is an LED. It is understood that, an ultraviolet, blue and/or green LED may be provided. The light emitting element20has two pads201with reverse polarities. In some embodiments, the pads201can form additional shoulders thereon to increase a height of the pads201for conveniently connecting to the metal wires40. The pads201are positioned at a top surface of the light emitting element20, that is, the light emitting element20is a horizontal structure LED. It is noted that the light emitting element20can be a vertical structure LED with the two pads201positioned on top and bottom surfaces thereof in an alternative embodiment.

Also referring toFIG. 3, the mask30is arranged on the first surface101of the base10and covers the light emitting element20. A space501is defined between the mask30and the first surface101. The space501is used for receiving the encapsulating layer50. The mask30is made of transparent or translucent material so that light generated by the light emitting element20can transmit through the mask30. The mask30defines two openings301therein. The openings301correspond to the pads201of the light emitting element20respectively for exposing the pads201outside of the mask30. It is understood that number of the openings301is identical to that of the pads201at the top surface of the light emitting element20, and if the light emitting element20is a vertical structure LED, the mask30defines a single opening301corresponding to the pad201at the top surface of the light emitting element20. The openings301can be designed to have such an exact size that only permits the extension of the pads201therethrough. Thus, when forming the encapsulating layer50, the liquid encapsulating material can be prevented from leaking out of the mask30via the openings301to the largest extent.

The metal wires40electrically connect the pads201of the light emitting element20and the electrical structures14. The metal wires40are positioned outside of the mask30. Each metal wire40connects one of the pads201with one end thereof, and one of the terminals141with an opposite end thereof. The number of the metal wires40can be two or more in this embodiment. It is noted that if the light emitting element20is a vertical structure LED, the number of the metal wires40can be one which connects to the pad201at the top surface of the light emitting element20, and the pad201at the bottom surface of the light emitting element20can connect a corresponding electrical structure14directly.

In some embodiments, a sealing layer70can be optionally formed on the mask30to seal the joints of the pads201and the metal wires40. The sealing layer70can increase a joining strength of the metal wires40and the pads201. The sealing layer70positioned at the openings301can also function as a leak proof structure to prevent the liquid encapsulating material from leaking from the openings301when forming the encapsulating layer50. As shown inFIG. 6, the sealing layer70can be divided into multiple ones separated from each other. Each sealing layer70seals a corresponding opening301. The sealing layer70can be silicone, epoxy or the mixture of the two. The sealing layer70can also contain phosphors therein.

The encapsulating layer50is filled in the space501between the first surface101of the base10and the mask30, and encapsulates the light emitting element20. The encapsulating layer50also seals the through holes12of the base12. The encapsulating layer50contains phosphors therein. The phosphors may be YAG phosphors, silicon oxynitride phosphors, or nitride phosphors, etc. The phosphors in the encapsulating layer50can be excited by the light from the light emitting element20to emit light with a wave length different from that of the light generated by the light emitting element20. The two lights with different wave lengths combining together can obtain a light with a desired color such as white.

The cover layer60is arranged on the first surface101of the base10and shields the mask30and the metal wires40. The cover layer60is made of transparent or translucent material through which light is able to penetrate. The cover layer60may comprise inorganic material such as silica (SiO2) or titanium dioxide (TiO2).

The light emitting device package provided by the present disclosure is characterized in that the encapsulating layer50is not in contact with the metal wires40. Thus, the damage to the joints of the metal wires40and the light emitting element20during the encapsulating process in the conventional light emitting device package is eliminated in the light emitting device package provided by the present disclosure. In addition, the mask30can be designed to have such a height that the encapsulating layer50only covers lateral sides of the light emitting element20, whereby a damage to the light emitting element20during the encapsulating process can be at least partly decreased.

Referring toFIG. 11, a light emitting device package in accordance with an alternative embodiment can further comprise extended layers142extending from the electrical structures14. The extended layers142each connect one of the terminals141and extend from the first surface101to the second surface102of the base10. The extended layers142are configured to facilitate subsequent usage or installation of the light emitting device package.

Referring toFIG. 12, multiple holes143can be defined in the extended layer142corresponding to the through holes12of the base10respectively. After forming the encapsulating layer50, the holes143are sealed by soldering material80.

Referring toFIG. 13, a light emitting device package in accordance with an alternative embodiment, in comparison with the embodiment ofFIG. 10, can further comprise another sealing layer90formed on the second surface102of the base10. The another sealing layer90seals the through holes12of the base10to protect the encapsulating layer50.

Referring toFIG. 9, a light emitting device package in accordance with an alternative embodiment, in comparison with the embodiment ofFIG. 10, is different in that the encapsulating material50in the through holes12ofFIG. 10is replaced by heat conductive material15ofFIG. 9. The heat conductive material15can be metal, ceramics or other material having a good heat conductivity. The heat conductive material15not only increase a heat dissipating efficiency of the base10but also protect the encapsulating layer50from contamination. The encapsulating material50in this embodiment is only filled in the space501.

It is understood that features described in the above different embodiments can be combined or altered without departing from the spirit of the disclosure. For example, the heat conductive material15can be covered by the extended layer142or the another sealing layer90.

A method of manufacturing a light emitting device package provided by the present disclosure now will be described in detail hereinafter with reference to FIGS.1-10.

Referring toFIGS. 1 and 2, a base10is provided. The base10has a first surface101and a second surface102opposite to the first surface101. The base10has at least two through holes12extending through the first and second surfaces101,102. The first surface101has electrical structures14formed thereon. The electrical structures14comprise at least two terminals141. A light emitting element20, for example, an LED chip, is provided and mounted on the first surface101of the base10. A bottom surface of the light emitting element20is attached to the first surface101. The light emitting element20has two pads201with reverse polarities at a top surface thereof. It is understood that the through holes12can be defined in the base10before or after that the light emitting element20is mounted on the base10.

Referring toFIG. 3, a mask30is brought to cover the first surface101of the base10. A space501is defined between the mask30and the first surface101. The light emitting element20is received in the space501. All of the through holes12of the base10are communicated with the space501. The mask30is made of material with good light penetration and the light generated by the light emitting element20can penetrate through the mask30with little loss. Two openings301are defined in the mask30corresponding to the pads201of the light emitting element20respectively. The pads201are exposed to an outside of the mask30through the openings301. The openings301are so dimensioned and configured that gaps between the mask20and the pads201are as small as possible, to thereby prevent liquid encapsulating material from leaking out of the mask30from the openings301when forming the encapsulating layer50as disclosed herebelow.

Referring toFIG. 4, it shows a step of electrically connecting the pads201of the light emitting element20and the terminals141of the electrical structures14with metal wires40. The metal wires40are positioned outside of the mask30. Each of the metal wires40has one end connected to one of the pads201and an opposite end connected to one of the terminals141.

Referring toFIG. 5, a sealing layer70is positioned on the mask30and covers the joints of the pads201and the metal wires40. The sealing layer70is made of material with good light penetration. The sealing layer70functions not only increasing a joining strength of the pads201and the metal wires40, but also preventing liquid encapsulating material from leaking from the openings301. The sealing layer70can also be designed to only cover at the openings301to reduce its coverage whereby shading of the light from the light emitting element20caused by the sealing70can be reduced, as shown inFIG. 6.

Referring toFIG. 7, liquid encapsulating material51is injected in the space501from one of the through holes12of the base10, and air in the space501can be exhausted from another through hole12as shown by the arrows. The liquid encapsulating material51encapsulates the light emitting element20and forms the encapsulating layer50after solidification. Also referring toFIG. 8, the base10can be positioned upside down during the encapsulating. Thus, the amount of the liquid encapsulating material51can be well controlled to only fill in the space501with the through holes12unoccupied.

Referring toFIG. 9, in one embodiment, heat conductive material15can fill in the through holes12after forming the encapsulating layer50. The heat conductive material15can be metal, ceramics, etc.

ReferringFIG. 10again, a cover layer60is provided on the first surface101of the base10and covers the mask30and the metal wires40. The cover layer60protects the metal wires40and the mask30from damage. The cover layer60is made of transparent or translucent material, and comprises inorganic material such as SiO2, TiO2, etc. The cover layer60can be formed to have an inverted U-shaped configuration defining a space receiving the metal wires40and the mask30therein, whereby the cover layer60does not contact and is separated from the metal wires40and the mask30.

Since the encapsulating layer50only encapsulates the light emitting element20and is separated from the metal wires40, the joints of the light emitting element20and the metal wires40are prevented from being impacted by the encapsulating material51during the encapsulating process, whereby a reliability of the light emitting device package is increased.

Referring toFIG. 11again, the electrical structures14can extend from the first surface101to the second surface102to form an extended layer142, after forming the encapsulating layer50. The extended layer142covers the through holes12to protect the encapsulating layer50from contamination. Also referring toFIG. 12again, the extended layer142can be formed with the electrical structures14before the encapsulating process. For this, when subsequently defining the through holes12in the base10, holes143are also defined in the extended layer142. After forming the encapsulating layer50, the holes143are sealed by soldering material80.

Referring toFIG. 13again, another sealing layer90can be formed on the second surface102of the base10to replace the extended layer142. The another sealing layer90can be made of silicone, epoxy, or the mixture of the two.

Further, if the light emitting element20is a vertical structure LED, the mask30defines only one opening301corresponding to the pad201at the top surface of the light emitting element20. The pad201at the bottom surface of the light emitting element20can be directly connected to one of the terminals141of the electrical structures14. Other packaging steps for the vertical structure LED are similar to those of the previous embodiments; thus, a detailed description is omitted.