Abstract:
A protective circuit board for a battery pack for controlling charge and discharge states of the battery pack includes an insulation layer and a first signal pattern disposed inside the insulation layer. The circuit can further include a second signal pattern disposed inside the insulation layer. The circuit can include a first dummy pattern spaced from a first side of the first signal pattern and a second dummy pattern spaced from a second side of the first signal pattern.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to and the benefit of Korean Patent Application No. 10-2004-0086896, filed with the Korean Intellectual Property Office on Oct. 28, 2004, the entire content of which is incorporated by reference. 
     BACKGROUND OF THE INVENTION 
     a. Technical Field 
     The present invention relates to a protective circuit board for a battery pack, and more particularly to a protective circuit board for a battery which minimizes the influence of external electromagnetic waves and static electricity. 
     b. Description of Related Art 
     In general, a protective circuit board for a battery pack controls charge and discharge states of the battery pack and interrupts the current of the battery pack when it is overcharged or over-discharged to protect the battery pack and the user. 
     The structure of a protective circuit board will now be described briefly with reference to  FIG. 1 . 
     As shown, a conventional protective circuit board includes an insulation layer  10 , at least one conductive first signal pattern  20  formed on a surface of the insulation layer  10  or on the opposite surface, at least one second signal pattern  30  formed on a surface of the insulation layer  10  or on the opposite surface, at least one conductive via  40  for electrically connecting the first and second signal patterns  20  and  30  to each other, and various electronic components  50 , such as semiconductor ICs, switches, and/or LEDs, mounted on the first or second signal pattern  20  or  30 . 
     Battery packs having a protective circuit board mounted thereon are frequently exposed to extreme conditions. For example, they are usually used at a place where severe electromagnetic waves occur or are exposed to naturally generated static electricity. Such electromagnetic waves or static electricity generally affect various electronic components on the protective circuit board. Particularly, noise or static electricity may act on the electronic components along first or second signal patterns formed on the surface of the protective circuit board. 
     The larger the length or area of the first or second signal patterns are, the more likely it is that electromagnetic waves or static electricity will flow towards the electronic components along the first or second signal patterns. As a result, conventional battery packs frequently malfunction as various electronic components fail to operate correctly under the influence of electromagnetic waves or static electricity. 
     In an attempt to minimize the influence of electromagnetic waves or static electricity, a case, which encloses the protective circuit board, may be subjected to secondary shielding treatment. Alternatively, silicone glue or tape may be attached thereto. However, such measures raise the overall manufacturing cost of battery packs and increase the weight. 
     SUMMARY OF THE INVENTION 
     Accordingly, a protective circuit board for a battery pack is provided with main signal patterns disposed inside an insulation layer to minimize the influence of external electromagnetic waves and static electricity. 
     A protective circuit board for a battery pack for controlling charge and discharge states of the battery pack includes an insulation layer and a first signal pattern disposed inside the insulation layer. In one embodiment, the circuit board further includes a second signal pattern disposed inside the insulation layer. 
     According to another aspect of the present invention, a protective circuit board includes an insulation layer, first and second dummy patterns disposed inside the insulation layer and spaced a predetermined distance from each other. A signal pattern may be formed between the first and second dummy patterns. 
     Since main signal patterns are positioned inside the insulation layer, external electromagnetic waves and static electricity are less likely to reach the signal patterns. Therefore, various electronic components mounted on the protective circuit board are not affected by any noise caused by electromagnetic waves and static electricity, and the protective circuit board may be less likely to malfunction. 
     In addition, the first and second dummy patterns, which are positioned above and below the signal pattern, respectively, absorb and remove electromagnetic waves and static electricity. As a result, the signal pattern, which is positioned between the dummy patterns, is less affected by noise. 
     A method of minimizing influence of electromagnetic waves and static electricity on signal patterns of a protective circuit board for a battery pack includes providing the protective circuit board with an insulation layer. The insulation layer has a first outer surface, a second outer surface, and a first insulation sublayer and a second insulation sublayer interposed between the first outer surface and the second outer surface. The method also includes disposing a first signal pattern at a first interface between the first insulation sublayer and the second insulation sublayer such that the first signal pattern is spaced from the first outer surface and the second outer surface. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic sectional view showing a conventional protective circuit board for a battery pack. 
         FIG. 2  is a schematic sectional view showing a protective circuit board for a battery pack according to an embodiment of the present invention. 
         FIG. 3  is a schematic sectional view showing a protective circuit board for a battery pack according to another embodiment of the present invention. 
         FIG. 4  is a block diagram showing a protective circuit board for a battery pack. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, examples of embodiments of the present invention will be described with reference to the accompanying drawings. In the following description and drawings, the same reference numerals are used to designate the same or similar components, and repetition of the description on the same or similar components will be omitted. 
     As shown in  FIG. 2 , a protective circuit board  100  for a battery pack according to one embodiment of the present invention includes at least one insulation layer  110 , at least one first signal pattern  120  disposed inside insulation layer  110 , at least one second signal pattern  130  disposed inside the insulation layer  110 , a first signal pad  140  formed on a surface of the insulation layer  110  while being electrically connected to the first signal pattern  120 , and a second signal pad  150  formed on a surface of the insulation layer  110  while being electrically connected to the second signal pattern  130 . 
     The insulation layer  110  in  FIG. 2  has first, second, third, and fourth sublayers  111 ,  112 ,  113 , and  114  successively laminated on top of each other. The number of layers of the insulation layer  110  is not limited to that shown in  FIG. 2  and may vary as desired. The insulation layer  110  may be made of an epoxy-based thermosetting resin or an equivalent thereof, but the material is not limited to that herein. 
     The first signal pattern  120  is disposed inside the insulation layer  110  without being exposed to the exterior thereof. Therefore, electromagnetic waves or static electricity cannot directly affect the first signal pattern  120 , although they may affect the surface of the insulation layer  110 . This means that the first signal pattern  120  does not generate any noise due to electromagnetic waves or static electricity. Although the first signal pattern  120  is shown in the drawing to be formed on an interface between the first and second layers  111  and  112  of the insulation layer  110 , the position is not limited to that in the present invention. For example, the first signal pattern  120  may be formed on an interface between the first and second layers  111  and  112  of the insulation layer  110 , on an interface between the second and third sublayers  112  and  113 , or on an interface between the third and fourth sublayers  113  and  114 . In other words, the position of the first signal pattern  120  is not limited in any manner, as long as it is not exposed to the surface of the insulation layer  110 . The first signal pattern  120  may be made of conventional copper or an equivalent thereof, but the material is not limited to that embodiment. 
     The second signal pattern  130  is disposed inside the insulation layer  110  without being exposed to the exterior thereof, while being spaced a predetermined distance from the first signal pattern  120 . As in the case of the first signal pattern  120 , therefore, electromagnetic waves or static electricity cannot directly affect the second signal pattern  130 , although they may affect the surface of the insulation layer  110 . This means that the second signal pattern  130  does not generate any noise due to electromagnetic waves or static electricity. 
     Although the second signal pattern  130  is shown in the drawing to be formed on an interface between the second and third layers  112  and  113  of the insulation layer  110 , the position is not limited thereto. For example, the second signal pattern  130  may be formed on an interface between the first and second layers  111  and  112  of the insulation layer  110 , on an interface between the second and third sublayers  112  and  113 , or on an interface between the third and fourth sublayers  113  and  114 . In other words, the position of the second signal pattern  130  is not limited in any manner, as long as it is not exposed to the surface of the insulation layer  110 . 
     The first and second signal patterns  120  and  130  may be positioned on different planes, the positional relationship is not limited to that shown in the drawing. Particularly, the first and second signal patterns  120  and  130  may be positioned on the same plane. The first and second signal patterns  120  and  130  may be connected to each other by means of a conductive via  139  extending through the insulation layer  110 . The conductive via  139  may be made of conventional copper or an equivalent thereof, but the material is not limited to that herein. As will be easily understood by those skilled in the art, various input or output signals can be transmitted via the first or second signal pattern  120  or  130 . 
     The first signal pad  140  occupies a minimum area on the surface of the first sublayer  111  of the insulation layer  110 . For example, the first signal pad  140  may have a length corresponding to 0.1-10% of that of the first signal pattern  120 . If the length of the first signal pad  140  is smaller than 0.1% of that of the first signal pattern  120 , various electronic components  160  must be mounted in a narrow area. This makes the mounting process difficult. If the length of the first signal pad  140  is larger than 10% of that of the first signal pattern  120 , electromagnetic waves and static electricity are increasingly likely to affect the first signal pad  140 , which has been problematic in the prior art. The first signal pad  140  may be made of conventional copper or an equivalent thereof; but the material is not limited thereto. The first signal pad  140  may be connected to the first signal pattern  120  by means of a conductive via  125 . In the drawing, the conductive via  125  extends through the first sublayer  111  of the insulation layer  110  and connects the first signal pad  140  to the first signal pattern  120 . The conductive via  125  may be made of conventional copper or an equivalent thereof, but the material is not limited thereto. 
     The second signal pad  150  occupies a minimum area on the surface of the fourth sublayer  114  of the insulation layer  110 . For example, the second signal pad  150  may have a length corresponding to 0.1-10% of that of the second signal pattern  130 . If the length of the second signal pad  150  is smaller than 0.1% of that of the second signal pattern  130 , various electronic components (not shown in the drawing) must be mounted in a narrow area. This makes the mounting process difficult. If the length of the second signal pad  150  is larger than 10% of that of the second signal pattern  130 , electromagnetic waves and static electricity are increasingly likely to affect the second signal pad  150 , which has been problematic in the prior art. The second signal pad  150  may be made of conventional copper or an equivalent thereof, but the material is not limited thereto. The second signal pad  150  may be connected to the second signal pattern  130  by means of a conductive via  135 . In the drawing, the conductive via  135  extends though the fourth sublayer  114  of the insulation layer  110  and connects the second signal pad  150  to the second signal pattern  130 . The conductive via  135  may be made of conventional copper or an equivalent thereof, but the material is not limited thereto. 
     As the first and second signal patterns  120  and  130  are positioned inside the insulation layer  110 , they do not generate either noise or high voltage due to electromagnetic waves or static electricity, which may be transmitted to the surface of the insulation layer  110 . 
     As shown in  FIG. 3 , a protective circuit board  200  for a battery pack according to another embodiment of the present invention includes at least one insulation layer  210 ; at least one signal pattern  220  disposed inside the insulation layer  220 ; first and second dummy patterns  230  and  240  spaced a predetermined distance from the signal pattern  220  in the upward and downward directions, respectively; first and second signal pads  250  and  260  formed on a surface of the insulation layer  210  while being electrically connected to the signal pattern  220 ; and first and second dummy pads  270  and  280  formed on a surface of the insulation layer  210  while being electrically connected to the first and second dummy patterns  230  and  240 , respectively. Descriptions of similar components as in the protective circuit board  100  discussed above in relation to  FIG. 2  will be omitted, and differences will now be described. 
     The insulation layer  210  may be a thermosetting resin including first, second, third, and fourth sublayers  211 ,  212 ,  213 , and  214  successively laminated, as in the case of the protective circuit board  100  according to the above-mentioned embodiment. 
     The signal pattern  220  is positioned on an interface between the second and third layers  212  and  213  of the insulation layer  210 . The signal pattern  220  may be made of conventional copper or an equivalent thereof, but the material is not limited thereto. 
     The first and second dummy patterns  230  and  240  are spaced at a predetermined distance from the signal pattern  220  in the upward and downward directions, respectively. For example, the first dummy pattern  230  is positioned on an interface between the first and second sublayers  211  and  212  of the insulation layer  210 , and the second dummy pattern  240  is positioned on an interface between the third and fourth sublayers  213  and  214  of the insulation layer  210 . The signal pattern  220 , which is positioned between the first and second dummy patterns  230  and  240 , is located on an interface between the second and third sublayers  212  and  213  of the insulation layer  210 . The first and second dummy patterns  230  and  240 , in this embodiment, have a length corresponding to 50-150% of that of the signal pattern  220 . If the length of the first and second dummy patterns  230  and  240  is smaller than 50% of that of the signal pattern  220 , external electromagnetic waves and static electricity are likely to reach the signal pattern  220 . If the length of the first or second dummy patterns  230  and  240  is larger than 150% of that of the signal pattern  220 , it is difficult to form another pattern and conductive via. The first and second dummy patterns  230  and  240  may be made of conventional copper or an equivalent thereof, but the material is not limited thereto. Even when electromagnetic waves and static electricity reach inside the insulation layer  210 , the first and second dummy patterns  230  and  240  absorb and remove it so that the signal pattern  220  positioned between the first and second dummy patterns  230  and  240  is not affected in any manner. As a result, electric components  290 , which are electrically connected to the signal pattern  220 , are not affected by any noise caused by electromagnetic waves and static electricity. 
     The first and second signal pads  250  and  260  are positioned on a surface of the insulation layer  210  while being connected to the signal pattern  220 . Particularly, the first signal pad  250  is formed on a surface of the first sublayer  211  of the insulation layer  210  and is connected to the signal pattern  220  by means of a conductive via  222 . The first signal pad  250  may have an electronic component  290  mounted thereon, such as an active device or a passive device. The second signal pad  260  is formed on a surface of the fourth sublayer  214  of the insulation layer  210  and is connected to the signal pattern  220  by means of a conductive via  224 . Although not shown in the drawing, the second signal pad  260  may have an electronic component mounted thereon. 
     The first and second signal pads  250  and  260 , in this embodiment, have a length corresponding to about 0.1-10% of that of the signal pattern  220 . If the length of the first and second signal pads  250  and  260  is smaller than 0.1% of that of the signal pattern  220 , various electronic components must be mounted in a too narrow area. This makes the mounting process difficult. If the length of the first and second signal pads  250  and  260  is larger than 10% of that of the signal pattern  220 , electromagnetic waves and static electricity are increasingly likely to affect the signal pattern  220 , which has been problematic in the prior art. 
     The first and second dummy pads  270  and  280  are positioned on a surface of the insulation layer  210  while being connected to the first and second dummy patterns  230  and  240 , respectively. Particularly, the first dummy pad  270  is positioned on a surface of the first sublayer  211  of the insulation layer  210  while being electrically connected to the first dummy pattern  230  by means of a conductive via  235 . The second dummy pad  280  is positioned on a surface of the fourth sublayer  214  of the insulation layer  210  while being electrically connected to the second dummy pattern  240  by means of a conductive via  245 . A positive or negative (or ground) voltage may be applied to the first dummy pad  270  and a voltage having the opposite polarity to that of the first dummy pad  270  (or ground) may be applied to the second dummy pad  280 . 
     As shown in  FIG. 4 , a battery pack  500  includes the protective circuit board  100  or  200 , and at least one battery cell  300 . The protective circuit board  100  or  200  may be electrically coupled to the battery cell  300 . Namely, the signal pad of the protective circuit board  100  or  200  may be coupled to terminals of the battery cell  300 . The battery cell  300  may be a lithium ion battery, a lithium polymer battery, or an equivalent thereof, but the material is not limited to that herein. Also, the battery cell  300  may be a square-type battery, a cylindrical battery, or an equivalent thereof, according to the appearance, but the appearance is not limited to that herein. 
     As mentioned above, the protective circuit board for a battery pack according to the this embodiment is advantageous in that, since the first and second signal patterns are positioned inside the insulation layer, external electromagnetic waves and static electricity hardly reach the first and second signal patterns. Therefore, various electronic components mounted on the protective circuit board are not affected by any noise caused by electromagnetic waves and static electricity, and the protective circuit board is prevented form malfunctioning. 
     In addition, the first and second dummy patterns, which are positioned above and below the signal pattern, respectively, absorb and remove electromagnetic waves and static electricity. As a result, the signal pattern, which is positioned between the dummy patterns, is not affected by any noise. 
     Although examples of embodiments of the present invention have been described for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims and equivalents thereof.