Abstract:
An electronic device module comprises a carrier and first and second device regions. The first device region comprises a plurality of serially-connected devices deposited on the carrier, and the second device region is adjacent to the first device region and comprises a plurality of serially-connected devices. The voltage potential of the plurality of the serially-connected devices in the first device region is substantially the same as that of the plurality of the serially-connected devices in the second device region whereby damage due to short circuit of the adjacent plurality of serially-connected devices is avoided.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to an electronic device module, and more particularly to an electronic device module with short circuit protection. 
         [0003]    2. Description of the Related Art 
         [0004]    With the development of the semiconductor manufacturing technology, the scale of electronic devices is continuously being reduced. Therefore, traditional connecting methods, such as the pin-through-hole (THT) method for connecting electronic devices to electronic carriers, i.e., printed circuit boards (PCB), circuit boards, or substrates, cannot handle the highly integrated current circuit design. Depositing a THT device on an electronic carrier requires drilling a hole in the carrier and applying tin solder to fix the THT device on the bottom side of the carrier; therefore the devices of this type occupy space on both sides of the electronic carrier and require a larger welding spot at the connection. In addition, THT devices usually have larger volume and occupy more space on the electronic carrier, and so surface mounting technique (SMT) has largely replaced the THT technique in current assembly processes to meet the requirement of miniaturized structures of the market. 
         [0005]    In the case of using SMT devices, because their pins and the main body are soldered on the same side of the electronic carrier, additional drilled holes are not required. Meanwhile, the SMT technique can be utilized to connect electronic devices on both sides of the electronic carrier, and thus improves the usage rate of the space significantly. In addition, due to their smaller volume and more competitive price, the SMT devices have already become common in the market. 
         [0006]      FIG. 1A  shows a top view of a conventional electronic device module  10 . Referring to  FIG. 1A , the electronic device module  10  comprises a substrate  11  and two device regions  12  and  13 . Each device region  12  and  13  is configured to contain a group of serially-connected devices.  FIG. 1A  shows an example of the device region  12  comprising a plurality of pairs of solder pads  141 ,  142 ,  151 ,  152 ,  161 , and  162  deposited on the surface of the substrate  11 . Both terminals of an electronic device  14  are connected to the corresponding solder pads  141  and  142  via a solder paste. Subsequently, the terminals of the electronic device  14  are electrically connected to other circuit layers or signals of the substrate by a via adjacent to the solder pad or by a wire (not shown). 
         [0007]      FIG. 1B  shows a circuit diagram of the conventional electronic device module  10  according to one embodiment of the present invention. As shown in  FIG. 1B , the group of the serially-connected devices in the device region  12  comprises devices  14 ,  15 , and  16 , and the group of the serially-connected devices in the device region  13  comprises devices  17 ,  18 , and  19 . The groups of the serially-connected devices are respectively connected between a power source V DD  and ground. Referring to  FIG. 1B , the terminal  141  of the device  14  is electrically connected to the power source V DD , the terminal  162  of the device  16  is electrically connected to ground, the terminal  171  of the device  17  is electrically connected to the power source V DD , and the terminal  192  of the device  19  is electrically connected to ground. 
         [0008]    Due to the highly integrated characteristic of the devices, when the tin solder of the solder pad of the device exceeds a slight tolerance or has a solder extrusion phenomenon produced by diffusion, a short circuit will occur between the tin solders. Referring to  FIG. 1A , because the terminal  162  of the device  16  is electrically connected to ground and the terminal  171  of the device  17  is electrically connected to the power source V DD , and the terminals  162  and  171  are deposited at the boundary between the device regions  12  and  13 , when the tin solders at the boundary are short, the power source V DD  is connected to ground which produces a greatly increased short current. Such large short current may damage electronic products utilizing the electronic device module. On the basis of the above, there is a need to provide an electronic device module so as to improve the reliability and the production yield of the electronic products. 
       SUMMARY OF THE INVENTION 
       [0009]    An aspect of the present invention is to reduce damage to adjacent serially-connected devices due to a short circuit. 
         [0010]    According to one embodiment of the present invention, an electronic device module comprises a carrier and first and second device regions. The first device region comprises a plurality of serially-connected devices deposited on the carrier, and the second device region is adjacent to the first device region and comprises a plurality of serially-connected devices. The voltage potential of the plurality of the serially-connected devices in the first device region is substantially the same as that of the plurality of the serially-connected devices in the second device region whereby damage due to short circuit of the adjacent plurality of serially-connected devices is avoided. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    The invention will be described according to the appended drawings in which: 
           [0012]      FIG. 1A  shows a top view of a conventional electronic module; 
           [0013]      FIG. 1B  shows a circuit diagram of the conventional electronic module according to one embodiment of the present invention; 
           [0014]      FIG. 2A  shows a top view of an electronic module according to one embodiment of the present invention; 
           [0015]      FIG. 2B  shows a circuit diagram of the electronic module according to one embodiment of the present invention; and 
           [0016]      FIG. 2C  shows a light emitting module utilizing the aforementioned arrangement of the electronic devices. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0017]      FIG. 2A  shows a top view of an electronic device module  20  according to one embodiment of the present invention. Referring to  FIG. 2A , the electronic device module  20  comprises a carrier  21  and a plurality of device regions  22 ,  23 , and  24 , and the device regions  22 ,  23 , and  24  are deposited on the surface of the substrate  21 . Each of the device regions  22 ,  23 , and  24  has first and second terminals deposited respectively on the solder pad on the surface of the substrate  21 . The device regions  22 ,  23 , and  24  are configured to contain a group of serially-connected devices. 
         [0018]      FIG. 2B  shows a circuit diagram of the electronic device module  20  according to one embodiment of the present invention, wherein the group of the serially-connected devices in the device region  22  comprises devices  223  and  224 , the group of the serially-connected devices in the device region  23  comprises devices  233  and  234 , and the group of the serially-connected devices in the device region  24  comprises devices  243  and  244 . Each of the groups of the serially-connected devices  22 ,  23 , and  24  is respectively connected between a power source V DD  and ground. One terminal of the device  223  in the device region  22  is connected to the first terminal  221  of the device region  22 , that is, the power source, and one terminal of the device  224  is connected to the second terminal  222  of the device region  22 , that is, the ground. One terminal of the device  233  in the device region  23  is connected to the second terminal  232  of the device region  23 , that is, the ground, and one terminal of the device  234  is connected to the first terminal  231  of the device region  23 , that is, the power source. Also, one terminal of the device  243  in the device region  24  is connected to the first terminal  241  of the device region  24 , that is, the power source, and one terminal of the device  244  is connected to the second terminal  242  of the device region  24 , that is, the ground. 
         [0019]    Referring to  FIG. 2A , in this embodiment, the first terminal  221  is deposited in the device region  22  according to a direction of a first side of the substrate  21 , and the second terminal  222  is deposited in the device region  22  according to a direction of a second side of the substrate  21 . The second terminal  232  is deposited in the device region  23  according to the direction of the first side of the substrate  21 , and the first terminal  231  is deposited in the device region  23  according to the direction of the second side of the substrate  21 . Because the second terminal  222  is electrically connected to the ground, and the second terminal  232  is also electrically connected to the ground, such arrangement can prevent failure when a short circuit occurs between the second terminal  222  and the second terminal  232 . 
         [0020]    In addition, in this embodiment, the first terminal  241  is deposited in the device region  24  according to the direction of the first side of the substrate  21 , and the second terminal  242  is deposited in the device region  24  according to the direction of the second side of the substrate  21 . That is, each of the plurality of the serially-connected devices in the device regions  22 ,  23 , and  24  has the same voltage polarity arrangement, i.e., (+, −, +, −, . . . +, −). The direction of the voltage polarity arrangement of the serially-connected devices  223  and  224  in the device region  22  is opposite to that of the serially-connected devices  233  and  234  in the device region  23 , and the direction of the voltage polarity arrangement of the serially-connected devices  243  and  244  in the device region  24  is the same as that of the serially-connected devices  223  and  224  in the device region  22 . Because the first terminal  231  in the device region  23  is electrically connected to the power source, and the first terminal  241  in the device region  24  is also electrically connected to the power source, such arrangement can prevent failure when a short circuit occurs between the first terminal  231  and the first terminal  241 . In addition, after the serially-connected devices are deposited in the device regions  22 ,  23 , and  24 , an encapsulating material is applied to cover the serially-connected devices to protect the devices from pollution, humidity and other environmental impurities. 
         [0021]    According to one embodiment of the present invention, the serially-connected devices comprise passive devices, such as a resistor, an inductor, or a capacitor. In another embodiment, the serially-connected devices can comprise a plurality of light emitting diodes (LEDs).  FIG. 2C  shows a light emitting module  30  utilizing the aforementioned arrangement of the electronic devices. The light emitting module  30  comprises a light emitting unit  31  and a driving device  32 , both deposited on a carrier (not shown). Light emitting rows  33  and  34  are composed of a plurality of LEDs connected in series, and the light emitting unit  31  is composed of a plurality of light emitting rows connected in parallel. Each light emitting row  33  and  34  is connected to a constant voltage V in  and light emitting signals of the light emitting rows  33  and  34  are controlled by the driving device  32 . The driving device comprises a plurality of output terminals OUT 1 -OUT N  connected to the light emitting rows, a voltage source terminal V DD , a ground terminal GND, a control terminal R ext , and an enable terminal EN. 
         [0022]    Referring to  FIG. 2C , a first terminal  331  of the light emitting row  33  is connected to the constant voltage V in  and a second terminal  332  is connected to the output terminal OUT 1 . In similar arrangement, a first terminal  341  of the light emitting row  34  is connected to the constant voltage V in  and a second terminal  342  is connected to the output terminal OUT 2 . The arrangement of the light emitting rows  33  and  34  according to one embodiment of the present invention is illustrated below. The first terminal  331  of the light emitting row  33  and the second terminal  342  of the light emitting row  34  are deposited according to the direction of the first side of the carrier, and the second terminal  332  of the light emitting row  33  and the first terminal  341  of the light emitting row  34  are deposited according to the direction of the second side of the carrier. In this arrangement, because the voltage potentials of the output terminal OUT 1  and OUT 2  are substantially the same, the light emitting module  30  will not fail when the second terminal  332  of the light emitting row  33  shorts to the second terminal  342  of the light emitting row  34 . 
         [0023]    The arrangement of the light emitting rows  33  and  34  according to another embodiment of the present invention is illustrated below. The second terminal  332  of the light emitting row  33  and the first terminal  341  of the light emitting row  34  are deposited according to the direction of the first side of the carrier, and the first terminal  331  of the light emitting row  33  and the second terminal  342  of the light emitting row  34  are deposited according to the direction of the second side of the carrier. In this arrangement, because the voltage potentials of the first terminal  331  of the light emitting row  33  and the first terminal  341  of the light emitting row  34  are the same, the light emitting module  30  will not fail when the first terminal  331  shorts to the first terminal  341 . 
         [0024]    The term “electrically connected” in the content refers to a method in which solder pads are connected by a via through different layers of a carrier, or solder pads are connected by a wire on the same side of the carrier. The term “deposited” as used above refers to a method in which the electronic devices and the carrier are connected by surface mount, flip-chip, bump, or wire bonding. 
         [0025]    The above-described embodiments of the present invention are intended to be illustrative only. Numerous alternative embodiments may be devised by those skilled in the art without departing from the scope of the following claims.