Patent Publication Number: US-2015060932-A1

Title: Liquid-filled packaging structure of heating component

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This non-provisional application claims priority under 35 U.S.C. §119(a) on Patent Application No(s). 102131580 filed in Taiwan, R.O.C. on Sep. 2, 2013, the entire contents of which are hereby incorporated by reference. 
     BACKGROUND 
     1. Technical Field 
     The disclosure relates to a liquid-filled packaging structure of a heating component. 
     2. Related Art 
     Ultraviolet light sources (UV light source) are commonly used in different kinds of applications based on their wave bands. The use of mercury has been restricted according to the Restriction of Hazardous Substances Directive (RoHS) adopted by European Union, therefore, UV Light-Emitting Diode (UV LED) will replace the mercury lamp in the near future. However, the package of the UV LED has two main problems. One is that the low conversion efficiency of the UV LED die (namely, chip crystal) leads to produce too much heat, thus, an effective heat dissipation mechanism needs to be applied to the UV LED lamp, to improve the stabilization and the life span of the LED. For example, a substrate with high conduction efficiency, e.g., aluminum nitride substrate (the heat conduction coefficient is 200 to 240 W/m K), is applied for enhancing the heat dissipation to immediately protect the LED from concentrating the heat at one point, generating a hot spot. The other problem is that because the light emitting wave band of the UV LED is between 300 to 400 nanometers (nm), encapsulants or lenses made of epoxy or silicone for the package of LED, are illuminated by the UV (especially the UV LED emitting the light having short wavelength) over time, so as to hurt or damage the good condition of the UV LED or to be degenerated (become yellowed). Thus, the luminance and color temperature of the UV LED are reduced. 
     The conventional package manner of the UV LED is to package the LED die in a vacuum or an inert gas environment for protecting the electrodes on the surface of the LED Die. However, the disadvantage of such a manner is that the index of refraction of the light emitted from the LED die is so high that the efficiency becomes lowered. In addition, the packaging manner in the vacuum or the inert gas environment leads to higher costs and a lower life span. 
     SUMMARY 
     An embodiment of the disclosure provides a liquid-filled packaging structure of a heating component comprising a main body, at least one heating component and a channel. The main body includes an accommodating space, a first opening connecting with the accommodating space and a second opening connecting with the accommodating space. The heating component is disposed in the accommodating space. The two opposite ends of the channel connect with the first opening and the second opening, respectively, so as to form a circulation loop. The accommodating space and the channel are filled with a liquid. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present disclosure will become more fully understood from the detailed description given hereinbelow along with the accompanying drawings which are for illustration only, thus are not limitative of the present disclosure, and wherein: 
         FIG. 1A  is a cross-sectional view of a liquid-filled packaging structure of a heating component according to a first embodiment of the disclosure; 
         FIG. 1B  is a cross-sectional view along a line A-A in  FIG. 1A ; 
         FIG. 2  is a cross-sectional view of a liquid-filled packaging structure of a heating component according to a second embodiment of the disclosure; 
         FIG. 3  is a cross-sectional view of a liquid-filled packaging structure of a heating component according to a third embodiment of the disclosure; 
         FIG. 4  is a cross-sectional view of a liquid-filled packaging structure of a heating component according to a fourth embodiment of the disclosure; 
         FIG. 5  is a cross-sectional view of a liquid-filled packaging structure of a heating component according to a fifth embodiment of the disclosure; 
         FIG. 6  is a cross-sectional view of a liquid-filled packaging structure of a heating component according to a sixth embodiment of the disclosure; 
         FIG. 7  is a diagram illustrating the relationships between the temperature and the start time of a liquid-filled packaging structure of a heating component and an LED lamp without a circulation channel; and 
         FIG. 8  is a cross-sectional view of a liquid-filled packaging structure of a heating component according to a seventh embodiment of the disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     In the following detailed description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the disclosed embodiments. It will be apparent, however, that one or more embodiments may be practiced without these specific details. In other instances, well-known structures and devices are schematically shown in order to simplify the drawings. 
     Please refer to  FIG. 1A , which is a cross-sectional view of a liquid-filled packaging structure of a heating component according to a first embodiment of the disclosure. The liquid-filled packaging structure of a heating component  1  in this embodiment comprises a main body  9 , at least one heating component  30 , a heat dissipation component  60  and a channel  50 . The main body  9  includes an accommodating space  15 , a first opening  16  connecting with the accommodating space  15  and a second opening  18  connecting with the accommodating space  15 . In this embodiment, the main body  9  includes a frame  10  and a cover  20 . The frame  10  includes a substrate  12  having a first surface  121  and a second surface  123  that are opposite to each other. The first surface  121  forms one of walls of the accommodating space  15 . The cover  20  covers the frame  10  so as to form the accommodating space  15  together. The accommodating space  15  and the channel  50  are filled with a liquid  40 . In this embodiment, the first opening  16  and second opening  18  are formed on the frame  10 , but are not limitative for the disclosure. In other embodiments, the first opening  16  and the second opening  18  are both formed on the cover  20  or formed on the frame  10  and cover  20 , respectively. 
     In this embodiment, the heating component  30  is disposed on the first surface  121  of the substrate  12 . The heating component  30  further comprises electronic components including dies, circuit boards, transmission wires and so forth, but are not limitative of the disclosure. The electronic components, for example, are resistors, capacitors, diodes, transistors, integrated circuits, fuel cells or solar cells. The circuit boards, for example, are ceramic substrates or printed circuit boards (PCB). In this embodiment, three LED dies are taken as the heating components  30  for example and are not limitative of the disclosure. In other embodiments, the number of the heating components  30  may be more than or less than three. 
     The channel  50  is connected to the first opening  16  and the second opening  18  of the frame  10 . The cover  20  covers the frame  10  so as to form the accommodating space  15  together. The accommodating space  15  and the channel  50  are both filled with the liquid  40 . 
     The heat dissipation component  60  is disposed on the second surface  123  of the frame  10 . The above-mentioned “being disposed on the second surface  123 ” is defined as the heat dissipation component  60  is attached to the second surface  123  of the frame  10  or the heat dissipation component  60  is located on the same side of the frame  10  as the second surface  123  and separated with the second surface  123  by a distance. In this embodiment, the heat dissipation component  60  is attached to the second surface  123  of the frame  10 , but this configuration is not limited to the disclosure. 
     The heat dissipation component  60  is a heat sink having a plurality of fins or is a thermoelectric component (TEC). The cover  20  is made of transparent material, e.g., inorganic material including silicone, glass, quartz glass and so forth. The liquid  40  is a material with low polarity, which is selected from a group consisting of silicone oil, mineral oil, and organic ester and a combination thereof. In addition the viscosity of the liquid  40  is between 0.1 to 10 5  centipoises (cP). However, the above-mentioned materials are only for exemplary, and are not limitative of the disclosure. In this embodiment, the heat dissipation component  60  is a heat sink comprising a base  62  and a plurality of fins  64 . The base  62  is connected to the second surface  123  of the substrate  12  of the frame  10 , and the channel  50  extends through the base  62 . 
     Please refer to  FIGS. 1A and 1B  together, and  FIG. 1B  is a cross-sectional view along a line A-A in  FIG. 1A . In this embodiment, the heating components  30  are a plurality of LED dies. When light generated by the heating component  30  emits out of the cover  20  through the liquid  40 , heat generated by the heating components  30  transfers to the base  62  of the heat dissipation component  60  through an effective heat dissipation area  35 . Then, the heat is dissipated through the fin  64 , reducing the whole temperature of the liquid-filled packaging structure of the heating component  1 . In this disclosure, the effective heat dissipation area  35  is defined as an area of the base  62  on which the heat source of the heating component  30  projects. For example, the heat generated by the heating component  30  is spread from the thermal contact area, where the first surface  121  of the substrate  12  is in thermal contact with the heating component  30 , towards the second surface  123  of the substrate  12 . The following describes an exemplary embodiment that the angle of the thermal spread of the heating component  30  is forty-five degrees. The effective heat dissipation area  35  (as shown in  FIG. 1B ) is an area that the bottom area of the heating component  30 , in thermal contact with the first surface  121 , projects and expands along forty-five degrees to the base  62 , but the angle of the thermal spread of the heating component  30  is not limitative of the disclosure. 
     The liquid-filled packaging structure of the heating component  1  in this embodiment applies not only the thermal conduction between the heat dissipation component  60  and the substrate  12  but also the thermosyphon by the liquid  40 . Specifically, the liquid  40 , in thermal contact with the heating component  30 , is configured for flowing through the channel  50 . After performing heat exchange with the heat source (the heating components  30 ), the liquid  40  flows into the channel  50  and the heat of the liquid  40  is removed to the heat dissipation component  60  through the channel  50 . Then, the liquid  40  flows back to the heating component  30  to form a circulation loop for heat dissipation. Therefore, the heat dissipation efficiency of the liquid-filled packaging structure of the heating component  1  is enhanced by the circulation loop. 
     In this embodiment, when the liquid  40  is heated, the volume of the liquid  40  expands and its density lowers. Accordingly, the buoyancy of the heated liquid  40  is greater than that of the liquid  40  at lower temperature, so the heated liquid  40  flows upwards (towards the cover  20 ), generating the thermal convection of the liquid  40 . Because the liquid  40  is filled within an enclosed chamber formed by the channel  50  and the accommodating space  15 , in this enclose chamber, once the liquid  40  at high temperature flows, it drives the adjacent liquid  40  at low temperature fills the empty space left by the liquid  40  at high temperature, which enhances the circulation of the liquid  40  around the channel  50  and the accommodating space  15 . The liquid  40  at high temperature flows into the channel  50  through the first opening  16 . Because the channel  50  is disposed inside and extends through the base  62  of the heat dissipation component  60 , the heat of the liquid  40  at high temperature inside the channel  50  is dissipated by the fins  64  of the heat dissipation component  60  so as to lower the temperature of the liquid  40 . Then, the liquid  40  at a low temperature flows back to the accommodating space  15  through the second opening  18 . Therefore, the liquid  40  may circulate around the liquid-filled packaging structure of the heating component  1  to remove the heat generated by the heating components  30 . 
     In order to improve the heat dissipation efficiency of the liquid-filled packaging structure of the heating component  1 , the channel  50  is designed to be serpentine shape that the channel comprises a plurality of U shapes connected with each other with respect to the cross-sectional area line A-A in  FIG. 1A , for increasing the thermal contact area between the liquid  40  and the heat dissipation component  60 . In this embodiment, the U shapes of the channel and the effective heat dissipation area  35  on the base  62  are separated with each other (i.e., the U shapes of the channel do not intersect with the effective heat dissipation area  35  on the base  62 ), for enhancing the use of the space of the base  62  as well as the efficacy of the heat dissipation component  60 . In this disclosure, the heat dissipation component  60  has no impact on the area of the base  62  except the effective heat dissipation area  35 , so the area of heat dissipation component  60  where the channel  50  flows through does not affect the heat transfer between the substrate  12  and the base  62 . In other embodiments, in order to enhance the circulation efficiency of the liquid  40 , the widths of the plurality of U shapes gradually decrease from the first opening  16  towards the second opening. Thus, the flow resistance of the accommodating space  15  at the second opening  18  end is increased, allowing the liquid  40  at a high temperature to flow towards the first opening  16  end of the accommodating space  15 . 
     Please refer to  FIG. 2 , which is a cross-sectional view of a liquid-filled packaging structure of the heating component according to a second embodiment of the disclosure. In this embodiment, the difference between the liquid-filled packaging structure of the heating component  2  and the liquid-filled packaging structure of the heating component  1  in  FIG. 1A  is that the first opening  16  and the second opening  18  of the liquid-filled packaging structure of the heating component  2  have different heights. In this embodiment, the first opening  16  and the first surface  121  are separated by a first height H1, the second opening  18  and the first surface  121  are separated by a second height H2, and the first height H1 is greater than the second height H2. That is to say, adjusting the height of the opening makes the flow resistance of the first opening  16  end less than that of the second opening  18  end, so the liquid  40  at high temperature inside the accommodating space  15  tends to flow towards the first opening  16 , which improves the circulation efficiency of the liquid  40 . 
     Please refer to  FIG. 3 , which is a cross-sectional view of a liquid-filled packaging structure of the heating component according to a third embodiment of the disclosure. In this embodiment, the difference between the liquid-filled packaging structure of the heating component  3  and the liquid-filled packaging structure of the heating component  1  in  FIG. 1A  is that the first opening  16  and the second opening  18  of liquid-filled packaging structure of the heating component  3  have different cross-sectional areas. In this embodiment, the first cross-sectional area A1 of the first opening  16  is greater than the second cross-sectional area A2 of the second opening  18 . That is to say, adjusting the cross-sectional areas of the openings makes the flow resistance of the first opening  16  end less than that of the second opening  18  end, so the liquid  40  at a high temperature inside the accommodating space  15  tends to flow towards the first opening  16 , improving the circulation efficiency of the liquid  40 . 
     Please refer to  FIG. 4 , which is a cross-sectional view of a liquid-filled packaging structure of the heating component according to a fourth embodiment of the disclosure. In this embodiment, the difference between the liquid-filled packaging structure of the heating component  4  and the liquid-filled packaging structure of the heating component  1  in  FIG. 1A  is that the heating component  30  of the liquid-filled packaging structure of the heating component  4  is disposed toward the ground, i.e., the liquid-filled packaging structure of the heating component  4  system is upside down with respect to the configuration of the liquid-filled packaging structure of the heating component  1 . Moreover, the configuration of the channel  50 ′ is different from the channel  50  of the liquid-filled packaging structure of the heating component  1  in  FIG. 1A . In this embodiment, the lengths of the two ends of the channel  50 ′ are not equal to each other. Specifically, the length L, which the channel  50 ′ projects in the horizontal direction in  FIG. 4 , is equally divided by the middle line B-B, so the channel  50 ′ is divided into a first-opening- 16 -end section (on the left side of the middle line B-B) and a second-opening- 18 -end section (on the right side of the middle line B-B). The channel length of the first-opening- 16 -end section is greater than that of the second-opening- 18 -end, i.e., the path length of the liquid  40  flows through the first opening  16  end is greater than that of the second opening  18 . The configuration of the channel  50 ′ differentiates the channel lengths of the first opening  16  end and the second opening  18  end, so as to differentiate the flow resistances of the first opening  16  end and that of the second opening  18  end, driving the liquid  40  in the channel  50 ′ to flow towards the second opening  18  end as well as driving the liquid  40  at high temperature in the accommodating space  15  to flow towards the first opening  16 . Therefore, the circulation efficiency of the liquid  40  is improved. 
     According to the above-mentioned embodiments in  FIGS. 2 to 4 , The configuration of the channel  50  is asymmetrical that the shape of the first opening  16  end of the channel  50  is different from that of the second opening  18  end of the channel  50  (or  50 ′), which differentiates the flow resistances of the channel of the first opening  16  and that of the second opening  18 , thereby driving the liquid  40  in the channel  50  (or  50 ′) to flow towards the end of the opening with less flow resistance. The above-mentioned asymmetrical manners of the channel  50  (or  50 ′) comprise asymmetrical lengths, asymmetrical inner diameters of the channel and asymmetrical horizontal heights. However, people skilled in the art may apply other asymmetrical manners to achieve the same purpose, and are not limitative of the above-mentioned asymmetrical manners. 
     Please refer to  FIG. 5 , which is a cross-sectional view of a liquid-filled packaging structure of the heating component according to a fifth embodiment of the disclosure. In this embodiment, the difference between the liquid-filled packaging structure of the heating component  5  and the liquid-filled packaging structure of the heating component  1  in  FIG. 1A  is that the heat dissipation component  60  is disposed on the same side of the frame  10  as the second surface  123 , but the base  62  and the substrate  12  of the frame  10  are not directly connected with each other, i.e., the base  62  and the second surface  123  of the substrate  12  are separated by a distance. In addition, the liquid-filled packaging structure of the heating component  5  further comprises a pump  70  disposed inside the channel  50 . The pump  70  is configured for driving the liquid  40  in the channel  50  to flow towards the second opening  18  end, enhancing the circulation efficiency of the liquid  40 . 
     Please refer to  FIG. 6 , which is a cross-sectional view of a liquid-filled packaging structure of the heating component according to a sixth embodiment of the disclosure. The difference between the liquid-filled packaging structure of the heating component  6  and the liquid-filled packaging structure of the heating component  1  in  FIG. 1A  is that after extending through the base  62 , the channel  50 ″ extends through to the outside of the heat dissipation component  60 . Because the channel  50 ″ extends through to the outside of the heat dissipation component  60 , the heat dissipation efficiency of the liquid-filled packaging structure of the heating component  6  is improved. 
     The liquid-filled packaging structure of the heating component  6  according to this embodiment of the disclosure is to encapsulate the heating component in the accommodating space  15  filled with the liquid  40 , such that the heating component  30  (e.g., the LED die) is in direct contact with the liquid  40 , and the light emitted by the heating component  30  is refracted when passing through the liquid  40 . Thus, adjusting the index of the refraction of the liquid based on what kind of the heating component  30  (e.g., the LED die) the liquid-filled packaging structure of the heating component applies may enhance the efficiency of light extraction of the LED lamp. For example, the liquid  40  is silicone oil, and the heating component, which emits blue ray having the wavelength of 465 nm, is encapsulated by the liquid of silicone oil. After the heating component  30  operates to emit light for a continuous 72 hours by the power of 3.3 voltage and 350 milliamps and 28 degrees Celsius of room temperature, the total radiation flux is increased from 330.83 milliwatts to 369.38 milliwatts, which increases by 11.65 percent. 
     Please refer to  FIG. 7 , which is a diagram illustrating the relationships between the temperature and the start time of the liquid-filled packaging structure of the heating components  1 - 6  (the heating components  30  are LED dies for example) and an LED lamp without a circulation channel. It is found in  FIG. 7  that the increase rate of the temperature of the LED lamp without the circulation channel is faster than that of the liquid-filled packaging structure of the heating components provided by this disclosure. The difference of the temperature between them is ten degrees Celsius after the LED operates for thirty minutes. Thus,  FIG. 7  shows the efficacy of heat dissipation of the channel provided by this disclosure. 
     Please refer to  FIG. 8 , which is a cross-sectional view of a liquid-filled packaging structure of a heating component according to a seventh embodiment of the disclosure. The difference between the liquid-filled packaging structure of the heating component  7  and the liquid-filled packaging structure of the heating component  1  in  FIG. 1A  is that the liquid-filled packaging structure of the heating component  7  further comprises a metal printed circuit board (MCPCB)  13  disposed between the heating component  30  and the substrate  12 , and the heating component  30  is electrically connected to the metal printed circuit board  13 . 
     The liquid-filled packaging structure of the heating component (the heating components  30  are LED dies for example) according to the embodiments of the disclosure, the liquid is packaged to be in direct contact with the heating component (i.e., the heating component is immersed in the liquid), and the asymmetrical configuration of the channel or the drive of the pump allows the liquid to circulate around the liquid-filled packaging structure of the heating component, improving the thermal management, the light extraction, as well as maintaining the condition of encapsulant of the heating component and stabilization of the packaging structure (i.e., the heating component), which are described as follows: 
     (1) Thermal management: the heat is removed form the heat source to the outside by the liquid through the channel. After being cooled down, the liquid circulates to flow back to the heating component having a higher temperature than the channel by the configuration of the channel that the contact area between the liquid at a higher temperature and the cold end (ambient environment) is greatly increased. Thus, the path of the thermal spread is increased, and it controls the rising temperature of the heating component. 
     (2) Light extraction: the index of refraction of the liquid matches with the heating components. Compared with the package manner of the UV LED module in the inert gases or vacuum environment, the liquid package manner provided in this disclosure may greatly increase its efficiency of light extraction by 10 percent. 
     (3) Maintain the condition of encapsulant: adjusting the flow velocity of the liquid may control the light absorbing flux per certain time of the liquid. The liquid-filled packaging structure of the heating component may prevent the encapsulant or other packaging material of the heating component (e.g., LED) from being degenerated or yellowed according to the pyrolysis kinetics, or may defer the degeneration or yellowing of the encapsulants. Moreover, the liquid-filled packaging structure of the heating component may further comprise a door located on the frame or the channel for replacing the liquid. Therefore, when the liquid-filled packaging structure of the heating component operates for a long time, the liquid may be tainted or blemished, so the used liquid may be replaced through the door to maintain the life span and performance of the LED lamp. 
     (4) The stabilization of the packaging structure: the packaging structure (i.e., the heating component) is totally immersed in the liquid of the accommodating space, each unit of the packaging structure is borne by an equaled stress in the liquid. During the heat exchange process, this equaled stress may prevent the packaging structure from fracturing from the thermal stress, such as, thermal creep at the interface between two substances and the fatigue of the material. Thus the liquid may protect the packaging structure.