1. Field of the Invention
The present invention relates to a battery pack having metal tabs arranged at both ends of a protection circuit board and a case having apertures arranged at a location that corresponds to the metal tabs, and a method of fabricating the same.
2. Description of the Related Art
Recently, various compact handheld electronic/electrical devices, such as cellular phones, notebook computers, camcorders, and so on, have been widely developed and produced. The handheld electronic/electrical devices include a battery pack installed therein to operate the same without a separate power source. The battery pack can be classified into a nickel-cadmium (Ni—Cd) battery, a nickel-metal hydride (Ni—MH) battery, and a lithium (Li) battery. The battery pack using a secondary (i.e., rechargeable) battery is generally used in consideration of economic efficiency.
Among the types of batteries, the Li secondary battery is widely used for the handheld electronic/electrical devices due to an operating voltage three times higher and a higher energy density per unit weight than the Ni—Cd battery and the Ni—MH battery. The Li secondary battery can be classified into a Li ion battery using a liquid electrolyte and a Li polymer battery using a polymer electrolyte depending on the kind of electrolytes, or can be classified into a cylindrical, rectangular or pouch type depending on a manufactured shape thereof.
In general, the battery pack using the Li secondary battery includes a bare cell and a protection circuit assembly. The bare cell includes a can having an upper opening and accommodating an electrode assembly that includes a positive electrode plate and a negative electrode plate which respectively have electrode tabs connected to current collectors coated with active materials, and a separator arranged between the positive electrode plate and the negative electrode plate, and a cap assembly for sealing the upper opening of the can. The protection circuit assembly is electrically connected to the bare cell to prevent overcharge or over-discharge of the bare cell. The protection circuit assembly includes a protection circuit board for controlling voltage and current when the bare cell is charged or discharged, and an upper case for protecting the protection circuit board from external impact.
Specifically, the secondary battery includes a bare cell having a can for accommodating an electrode assembly and a cap assembly, and a protection circuit board coupled to the bare cell to adjust voltage or current upon charge or discharge. The cap assembly includes a cap plate for covering an opening into which the electrode assembly is inserted into the can, an electrode terminal insulated from the cap plate via a gasket, and a lead plate for electrically contacting the bare cell with the protection circuit board. In addition, a current circuit breaker, (e.g., a positive temperature coefficient (PTC)), is also coupled to the cap plate and insulated with double-sided tape.
However, when using the PTC, space and expense are required for forming an electrical terminal of the PTC for forming a contact between the PTC and the electrode terminal and between the PTC and the electrical terminal of the protection circuit board. Further, the lead plate connected to the bare cell, the electrical terminal of the PTC, and the electrical terminal of the protection circuit board have a substantially an L-shape for electrical connection with the protection circuit board. The L-shaped terminals are fixed to the bare cell or the protection circuit board at their horizontal parts. Since vertical parts of the L-shaped terminals are welded to each other with corresponding parts overlapping each other, the vertical parts of the L-shaped terminal can increase the entire length of the secondary battery. That is, as described above, it can be difficult to provide both a small size and a large capacity secondary battery due to the space required to form the electrical terminal of the PTC, the vertical parts of the L-shaped terminal, and so on. In addition, in order to insulate the entire PTC, including the electrical terminal, from the cap plate, double-sided insulating tape or the like needs to be adhered to the cap plate, thereby increasing material and process costs.