Chip electronic part

Details Chip electronic part Chip electronic part

1999-08-05

2001-02-27

Thomas, Tom (Department: 2811)

Semiconductor device manufacturing: process

Packaging or treatment of packaged semiconductor

Making plural separate devices

C257S531000, C336S150000, C336S195000, C336S200000, C438S106000, C438S381000, C205S204000, C205S205000, C029S602100, C029S607000

Reexamination Certificate

active

06194248

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to chip electronic parts used in chip inductors, chip coils, chip capacitors, etc. 2. Description of the Related Art
Conventionally, the rectangular chip coil shown in
FIG. 8
has been known in the art. This type of chip coil has the following structure: a coil pattern
2
and leading electrodes
3
are formed on a ceramic member
1
; an insulating protective layer
4
covers the entire face of the coil pattern
2
and portions of the leading electrodes
3
; external electrodes
5
electrically connected to the corresponding leading electrodes
3
are formed on the corresponding end faces of the ceramic member
1
. Each of the external electrodes
5
is composed of: a Cr undercoating layer
5
a
formed by dry plating such as sputtering; and a Ni plating layer
5
b
and a solder plating layer
5
c
, both produced by wet electrolytic plating.
According to the above conventional chip coil, when the undercoating layers
5
a
are formed on the corresponding end faces of the ceramic member
1
by dry plating, e. g. sputtering, a sputtering material inevitably extends to the upper and lower faces of the ceramic member
1
and the plating layers
5
b
and
5
c
are formed thereon by electrolytic plating. In this case, the length of the upper extension E
1
and that of the lower extension E
2
are the same in each of the external electrodes
5
. A certain length of the lower extension E
2
is required to solder the external electrodes
5
to a print substrate. Thus, the length of the upper extension E
1
is correspondingly increased to ensure a certain length of the lower extension E
2
.
However, an increase in the size of the upper extension E
1
leads to a decrease in the effective area for forming a conductor pattern on the ceramic member, which fact is a great problem because small-sized electronic parts are in demand nowadays. Further, the size of the upper extension E
1
alters according to the shape of the conductor pattern or the insulating protective layer, and the electrical characteristics thereby undesirably deteriorate or vary widely due to, e.g., inductive coupling between the pattern coil
2
and the upper extension E
1
of the external electrode
5
.
Conventional chip electronic parts are prepared as follows: A large-area ceramic base material is partitioned into portions by primary dividing grooves and secondary dividing grooves running in the transverse and longitudinal directions, respectively, and a conductor pattern and an insulating protective layer are formed in each portion according to a matrix pattern. After obtaining stick-shaped base material by primary-cutting the ceramic base material along the primary dividing grooves, the external electrodes are provided on the corresponding end faces, in which process a sputtering material of the undercoating layer enters into the secondary dividing grooves and plating layers are further formed thereon. As a result, the external electrodes are formed also in the secondary dividing grooves, and the electrical characteristics of the device thereby undesirably deteriorate or vary widely.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to provide a chip electronic part which can prevent external electrodes from greatly extending to the upper face of a ceramic member and/or largely entering into the secondary dividing grooves.
To solve the above object, a chip electronic part of the present invention is provided with at least one groove formed near an end face of an insulating protective layer so as to prevent the formation of an undercoating layer of the external electrode, which insulating protective layer is formed on the surface of the ceramic member to cover a conductor pattern.
The slope of the groove is not entirely covered with the undercoating layer by dry plating; thus the plating layer is not formed on the groove by dry plating. Following the dry plating step is a wet plating step, carried out on the undercoating layer to complete the plating layer. In other words, the extension of the external electrode is cut by the slope of the groove, thereby decreasing the length of the upper extension or the amount of the electrode entering into the secondary dividing grooves.


REFERENCES:
patent: 4434416 (1984-02-01), Schonberger
patent: 5071509 (1991-12-01), Kano et al.
patent: 5450263 (1995-09-01), Desaigoudar et al.
patent: 5699025 (1997-12-01), Kanoh et al.
patent: 5757076 (1998-05-01), Kambara
patent: 5764126 (1998-06-01), Kanetaka et al.
patent: 5900797 (1999-05-01), Dougauchi
patent: 6114938 (2000-09-01), Lida et al.

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