1. Technical Field
The present disclosure relates generally to a printed circuit board and a module with a surface mounting element using the printed circuit board, and more particularly to a back light module using the printed circuit board.
2. Description of Related Art
In recent years, light emitting diodes (LEDs) have been developed capable of emitting red, green, and blue light. Therefore, the LEDs have been increasingly used for various applications such as light sources of back light modules in displays or monitors.
A typical back light module includes a printed circuit board (PCB), an LED package mounted on the PCB, and a light guide plate located adjacent to the LED package. The light generated by the LED package can project into the light guide plate. Usually, the LED package includes two pins, and the PCB forms two corresponding pads thereon. The pins are soldered onto the pads by a surface mounting technology (SMT), to perform an electronic connection between the LED package and the PCB. However, different LED packages have different pins which are located at different positions. Therefore, when confronting different LED packages, multiple types of PCBs having different pads matching with the different pins of the LED packages are needed, which resulting in an increase of storage cost or even a risk of overstock.
What is needed therefore is a PCB and a back light module applying the PCB which has a good compatibility with different LED packages.
Many aspects of the present embodiments can be better understood with reference to the following drawings. The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the present embodiments. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views.
The module with a surface mounting element of the present disclosure is applied to a back light module as an example.
As shown in
In addition, a diffusion sheet (not shown) is adhered on the light guiding plate 24. The diffusion sheet can modulate the property of the light guiding plate 24. Different diffusion sheets are applied according to different light guiding plates 24. For example, a diffusion sheet with a thickness of about 100 μm can be applied to a polycarbonate light guiding plate 24 with a thickness of 20 mm, to increase optical uniformity of the light sources 21. The diffusion sheet can be directly located on the light guiding plate 24, or be adhered on the light guiding plate 24 via adhesive. The space between the diffusion sheet and the light guiding plate 24 is preferably 0-10 mm. The diffusion sheet is preferably made of, but not limited to, polyethylene terephthalate, as long as having a resistance to deformation or damage when confronting the heat generated by the light sources 21.
The light source 21 further comprises two electrodes 216, two wires 214 each connecting to the light emitting element 215 and a corresponding electrode 216, and a transparent encapsulant 213 secured in the groove 2111 and covering the light emitting element 215 and the wires 214. Each electrode 216 has a part embedded in the substrate 211, and another part exposed out of the substrate 211 to form the pin 212. The two pins 212 are located at two lateral sides of a front end of the substrate 211 respectively. Each pin 212 has a substantially L shape with an upper portion thereof adhered to the lateral side of the substrate 211 and a lower portion thereof adhered to a bottom of the substrate 211.
The resistance of the electrodes 216 is less than 300 μΩ-cm, and preferably less than 3 μΩ-cm, and the electrodes 216 can be made of copper, iron, or gold-plated/silver-plated aluminum.
The encapsulant 213 serves to support and protect the electrodes 216 and the light emitting element 215. The encapsulant 213 can be made of transparent organic or inorganic material such as silicone, epoxide resin, urea resin, or glass. In addition, other material such as thickening agents, light sensitive agents, barium titanium compounds, titanium oxides, aluminum oxides, silicon oxides, silicon dioxides, calcium bicarbonates, calcium carbonates can be added into the encapsulant 213. Further, a light emitting surface of the encapsulant 213 can be configured to be concave or convex mirrors to obtain a lens property.
The PCB 22 forms a plurality of soldering pads 23 thereon, and every two soldering pads 23 form a pad unit to match with the two pins 212 of a corresponding light source 21. Referring to
The PCB 22 is made of non-conductive material and the soldering pads 23 are made of conductive material such as copper. Referring to
Compared with the rectangular groove 2111 of the light source 21 in the first embodiment, the groove 2111a of the substrate 211a of the light source 21a in the second embodiment has an elliptic shape, for increasing a strength of sidewalls of the substrate 211a defining the groove 2111a.
Another difference between the light sources 21, 21a of the first and second embodiments is that, the pins 212 of the light source 21 of the first embodiment are located at two lateral sides of the front end of the substrate 211; however, the pins 212a of the light source 21a are located at two lateral sides of the rear end of the substrate 211a. When the light source 21a is to be soldered onto the PCB 22, a solder paste can be adhered to a rear half portion of the soldering pads 23 to bond with the pins 212a of the light source 21a and the soldering pads 23 of the PCB 22.
As described above, it is understood that the PCB 22 is capable of being used with different light sources 21(21a) without modification. That is, when confronting different light sources 21(21a), there is no need to prepare multiple types of PCBs, which reduces a storage cost.
It is noted that the extending direction of the second bars can be changed in alternative embodiments. Referring to
Furthermore, the second bar is not limited to perpendicular to the first bar.
It is believed that the present embodiments and their advantages will be understood from the foregoing description, and it will be apparent that various changes may be made thereto without departing from the spirit and scope of the disclosure or sacrificing all of its material advantages, the examples hereinbefore described merely being preferred or exemplary embodiments of the disclosure.
Number | Date | Country | Kind |
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98203881 | Mar 2009 | TW | national |