Patent Application
20160146436
This invention relates to an LED module, more particularly to an LED module including an LED unit, a flexible printed circuit board and a glue layer.
One type of conventional printed circuit board is composed of a flexible polymer film and an etched copper foil. This type of conventional printed circuit board provides good adhesion with electronic components, but is relatively expensive. Another type of conventional printed circuit board is composed of a flexible polymer film and a metal coil (e.g., silver coil or copper coil) printed on the flexible polymer film. This type of conventional printed circuit board is relatively low in cost, but offers inferior adhesion with electronic components.
Referring to
After repeated flexing of the flexible substrate 81, an interface between each of the banding pads 821 and the respective one of the conducting wirings 82 may break.
Therefore, an object of the present invention is to provide an LED module and an LED unit that can alleviate at least one of the drawbacks associated with the abovementioned prior arts.
According to a first aspect of the present invention, there is provided an LED module that includes a flexible printed circuit board, an LED unit disposed on the flexible printed circuit board, and a glue layer. The flexible printed circuit board includes a flexible substrate and two bonding pads disposed on the flexible substrate. The LED unit includes an insulating casing having a bottom surface that has a periphery region, an LED chip encapsulated in the insulating casing, and two conducting elements. Each of the conducting elements has a main portion disposed adjacent to the periphery region on the bottom surface of the insulating casing, is electrically connected to the LED chip, and is spaced apart from a periphery of the bottom surface of the insulating casing by the periphery region. The glue layer includes two first glue portions and two second glue portions. Each of the first glue portions is disposed between and electrically interconnects a respective one of the bonding pads of the flexible printed board and the main portion of a respective one of the connecting elements of the LED unit. The second glue portions are disposed on the periphery region of the bottom surface of the insulating casing to interconnect the LED unit and the flexible printed circuit board.
According to a second aspect of the present invention, there is provided an LED unit for being disposed on a flexible printed circuit board. The LED unit includes an insulating casing, an LED chip encapsulated in the insulating casing and two conducting elements. The insulating casing has a bottom surface that has a periphery region. Each of the conducting elements has a main portion that is disposed adjacent to the periphery region on the bottom surface of the insulating casing. Each of the conducting elements is electrically connected to the LED chip, and is spaced apart from a periphery of the bottom surface of the insulating casing by the periphery region.
Other features and advantages of the present invention will become apparent in the following detailed description of the embodiments with reference to the accompanying drawings, of which:
Before the present invention is described in greater detail with reference to the accompanying embodiments, it should be noted herein that like elements are denoted by the same reference numerals throughout the disclosure.
Referring to
The flexible printed circuit board 2 includes a flexible substrate 21, two bonding pads 22 separately disposed on the flexible substrate 21, and a pair of conducting wirings 23. Each of the conducting wirings 23 extends from and is electrically connected to a corresponding one of the bonding pads 22. The flexible substrate 21 may be made from polyethylene terephthalate (PET). The bonding pads 22 may be made from silver. Alternatively, the flexible substrate 21 may be made from polyimide (PI), and bonding pads 22 may be made from copper or other conductive materials.
The LED unit 1 is disposed on the flexible printed circuit board 2 and includes an insulating casing 11 having a bottom surface that has a periphery region, an LED chip 12 encapsulated in the insulating casing 11, and two spaced apart conducting elements 13 formed on the bottom surface of the insulating casing 11 and exposing the periphery region.
The bottom surface of the insulating casing 11 has a periphery 15. In the first embodiment, the periphery 15 has a rectangular shape and has two opposing long sides and two opposing short sides.
Each of the conducting elements 13 has a main portion 130 that is disposed adjacent to the periphery region on the bottom surface of the insulating casing 11, that is spaced apart from the periphery 15 by the periphery region, and that is electrically connected to the LED chip 12. The periphery region between the main portion 130 of each of the conducting elements 13 and the periphery 15 has a minimum width (d) not less than 0.5 mm. To be more specific, in this embodiment, the periphery region between the main portion 130 of each of the conducting elements 13 and a corresponding one of the short sides of the periphery 15 has a minimum width (d) not less than 0.5 mm (see
The glue layer 3 includes two first glue portions 31 and two second glue portions 32. Each of the first glue portions 31 is disposed between and electrically interconnects a respective one of the bonding pads 22 of the flexible printed circuit board 2 and the main portion 130 of a respective one of the connecting elements 13 of the LED unit 1. The second glue portions 32 are disposed on the peripheral region of the bottom surface of the insulating casing 11 to interconnect the LED unit 1 and the flexible printed circuit board 2 for enhancing bonding strength therebetween. In this embodiment, each of the second glue portions 32 covers a corresponding one of the conducting wirings 23 located under the peripheral region and is spaced apart from a respective one of the first glue portions. It should be noted that the second glue portions 32 may extend to a lateral surface (perpendicularly extending from the periphery 15 of the bottom surface) of the insulating casing 11 for further enhancing bonding strength between the LED unit 1 and the flexible printed circuit board 2. The first glue portions 31 are conductive adhesives made from, e.g., tin or silver. The second glue portions 32 may be conductive or non-conductive adhesives.
The lateral surface of the insulating casing 11 includes a lateral lighting portion 10 that permits light emitted from the LED chip 12 to exit from the insulating casing 11 toward a light guide film (not shown). The light transmitted in the light guide film could emit toward a keyboard apparatus (not shown) so as to provide a lighting keyboard apparatus. It is worth mentioning that since the arrangement of the LED unit 1 with the lateral lighting portion 10, the light guide film and the keyboard apparatus is well known to a skilled artisan and can vary based on practical requirements, detailed descriptions thereof are omitted herein for the sake of brevity.
To sum up, by virtue of the second glue portions 32 that are respectively located between the periphery of the insulating casing 11 and the first glue portions 31, bonding strength between the LED unit 1 and the flexible printed circuit board 2 could be enhanced and the problem of breakage at an interface between the bonding pad and the conducting wiring likely to occur in the prior art could be alleviated.
While the present invention has been described in connection with what are considered the most practical embodiments, it is understood that this invention is not limited to the disclosed embodiments but is intended to cover various arrangements included within the spirit and scope of the broadest interpretation so as to encompass all such modifications and equivalent arrangements.
