Electricity: battery or capacitor charging or discharging – Battery or cell discharging – With charging
Reexamination Certificate
1999-03-24
2001-02-06
Tso, Edward H. (Department: 2838)
Electricity: battery or capacitor charging or discharging
Battery or cell discharging
With charging
C320S136000, C257S791000
Reexamination Certificate
active
06184658
ABSTRACT:
BACKGROUND OF INVENTION
1. Field of the Invention
This invention relates to a battery pack incorporating a lithium ion battery, and more particularly to a battery pack in which a circuit board protecting the battery is improved.
2. Related Art
A rechargeable battery pack used for a portable telephone set or the like is a lithium ion battery which is incorporated in an insulating package. The battery pack includes a protective circuit which prevents the over-discharge or over-charge of the battery. A plurality of circuit parts are built on a circuit board having a printed wiring pattern. A battery pack whose miniaturization is advanced, the space for the circuit board is limited. Therefore, a circuit board whose both sides are used is employed; that is, parts are built on both sides of one circuit board.
FIGS.
3
(A) and
3
(B) are a plan view and a side view of a conventional protective circuit COB (chip on board) type circuit board, respectively. In those figures, reference numeral
10
designates a circuit board whose both sides are used formounting parts (hereinafter referred to as “a circuit board”, when applicable);
11
, a first part mounting on the front surface side;
12
, a second part mounting surface on the rear surface side. Reference numeral
22
designates a circuit part mounted on a second part mounting surface
12
. On both part mounting surfaces, the wiring patterns are not shown. Reference numeral
13
designates through-holes which connect the two front and rear wiring patterns.
Some of the circuit parts are resin-sealed for water proof. Those parts are, in general, transistors and ICs (semiconductor integrated circuit devices). In the case FIG.
3
(A), the parts
23
and
24
are to be resin-sealed; that is, those parts are covered with resin
30
after being mounted. The parts of this kind; that is, the transistors and ICs
23
and
24
are molded in their packages, and mounted on the circuit board
10
by soldering.
In the case of a battery pack used for a portable telephone set, there is a strong demand for reduction in weight. One method of reducing the weight of the protective circuit shown in FIGS.
3
(A) and
3
(B) is to use a bare chip of a transistor or IC. In the case of use of the bare chip, partial sealing of the parts with the resin
30
is insufficient in water proof. Especially, in the case where the circuit board
10
whose both surfaces are used for mounting parts is employed, the resin sealing (
30
) of one surface is low in reliability. On the other hand, in the conventional battery pack, the protective circuit board is laid out in the spaces or gaps left in the pack, so that the layout of the wires is in disorder, and it is impossible to coat the whole circuit board
10
with the resin
30
. Those are the problems to be solved by the invention.
SUMMARY OF INVENTION
The foregoing object of the invention has been achieved by the provision of a battery pack incorporating a lithium ion battery, which, according to the invention, comprises:
a circuit board of the type that parts are mounted on a single surface thereof, on the part-mounting surface of which a plurality of circuit parts forming a protective circuit for preventing the over-charge and over-discharge of the battery; and
resin which seals the whole part-mounting surface of the circuit board after the circuit parts have been mounted thereon,
transistors and ICs employed as the circuit parts being a bare chips.
It is preferable that, in the battery pack, external connecting terminals of the protective circuit are formed on the surface opposite to the part-mounting surface of the circuit board, and the protective circuit is connected through through-holes to the external connecting terminals.
REFERENCES:
patent: 5083189 (1992-01-01), Sawaya
patent: 5264656 (1993-11-01), Itakura et al.
patent: 5793118 (1998-08-01), Nakajima
Higashijima Yasuhisa
Mori Masaki
McGuireWoods LLP
Mitsumi Electric Co. Ltd.
Tso Edward H.
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