Electricity: measuring and testing – Measuring – testing – or sensing electricity – per se – With rotor
Reexamination Certificate
2002-08-09
2004-11-02
Tang, Minh (Department: 2829)
Electricity: measuring and testing
Measuring, testing, or sensing electricity, per se
With rotor
C324S754090
Reexamination Certificate
active
06812692
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to inspection terminals for inspecting electronic chip components, and inspection methods and inspection apparatuses using the same, and more particularly, the present invention relates to an inspection terminal for inspecting an electronic chip component by bringing the inspection terminal into contact with, for example, an external electrode of the electronic chip component, and an inspection method and an inspection apparatus for inspecting the electronic chip component using the same.
2. Description of the Related Art
FIG. 9
is an illustration of an example inspection apparatus for inspecting an electronic chip component using a known inspection terminal, disclosed in Japanese Unexamined Patent Application Publication No. 10-19949. An inspection apparatus
1
includes a turntable
2
acting as a carrier unit for carrying electronic chip components
5
. The turntable
2
has a plurality of depressions arranged around the periphery thereof, each defining a storing portion
3
which stores one electronic chip component
5
. The electronic chip component
5
is carried around the circumference of the turntable
2
by rotating the turntable
2
.
Along the carrying path of the turntable
2
, the inspection apparatus
1
has an inserter unit
6
for inserting the electronic chip component
5
into the storing portion
3
, an inspection unit
7
for measuring a characteristic of the component
5
, and a sorter unit
8
for sorting the component
5
based on the measured characteristics of the component
5
. The turntable
2
carries the electronic chip components
5
stored in the storing portions
3
from the inserter unit
6
to the inspection unit
7
. As shown in
FIGS. 10A and 10B
, at the inspection unit
7
, an inspection terminal
9
is brought into contact with a side surface of an external electrode
5
a
of the electronic chip component
5
.
The inspection terminal
9
is cylindrical and has a linear edge portion
9
a
at the end thereof. The edge portion
9
a
has an acute angle, generally about 80 degrees. The linear portion of the edge portion
9
a
is brought into contact with the external electrode
5
a
in the widthwise direction of the external electrode
5
a
, that is, so as to be substantially parallel to the longitudinal direction of the entire electronic chip component
5
, as shown in
FIGS. 10A and 10B
. The inspection terminal
9
is connected to the inspection apparatus
1
and serves as a measuring terminal for measuring a characteristic of the electronic chip component
5
. For example, when the electronic chip component
5
is a chip-type capacitor, the capacitance, the insulating resistance, and so forth thereof are measured.
The external electrode
5
a
of the electronic chip component
5
has a multilayer structure. First, the electronic chip component
5
has an electrode, made from a metal such as Ag or Cu, baked at the end of a substrate thereof. The electronic chip component
5
also has a Ni-plated layer formed thereon for preventing electrode leaching causing the electrode to elute into a solder member during soldering, and further has a Sn-plated layer formed on the Ni-plated layer for improving solderability.
The Sn-plated layer is likely to be oxidized and accordingly has an oxide film formed on the surface thereof, sometimes causing inaccurate measurement of the characteristic. This problem however can be solved by providing the inspection terminal
9
with the edge portion
9
a
. That is, the edge portion
9
a
breaks the oxide film on the surface of the external electrode
5
a
and cuts into the external electrode
5
a
, leading to accurate measurement of the characteristic. Even when the inspection terminal
9
has dirt accumulated on the surface thereof, the dirt is removed since the surface of the inspection terminal
9
a
rubs against the external electrode
5
a
when the inspection terminal
9
cuts into the external electrode
5
a
. Accordingly, an incorrect measurement caused by the dirt can be prevented, since the inspection terminal
9
has little dirt on the surface of the edge portion
9
a
which has cut into the external electrode
5
a.
In addition, even when the electronic chip component
5
moves inside the storing portion
3
, the inspection terminal
9
can be reliably brought into contact with the external electrode
5
a
by bringing the linear portion of the edge portion
9
a
into contact with the external electrode
5
a
so as to be substantially parallel to the widthwise direction of the external electrode
5
a
. In other words, since the edge portion
9
a
of the inspection terminal
9
has a linear shape, at least one portion of the edge portion
9
a
comes into contact with the external electrode
5
a
even when the electronic chip component
5
moves in the widthwise direction of the external electrode
5
a
, i.e., in the longitudinal direction of the entire electronic chip component
5
. Furthermore, since the entire external electrode
5
a
is not totally out of contact with the inspection terminal
9
even when the electronic chip component
5
moves in the longitudinal direction of the external electrode
5
a
, i.e., in the widthwise direction of the entire electronic chip component
5
, the inspection terminal
9
can be brought into contact with the external electrode
5
a.
However, the edge portion of the above-described inspection terminal sometimes passes through the Sn-plated layer and reaches the Ni-plated layer since the edge portion has an acute angle. If an inner electrode layer such as the Ni-plated layer is exposed to the outside as described above, the solderability may deteriorate because of a chemical reaction of the exposed inner electrode layer when the electronic chip component is soldered onto a circuit board, thereby causing a risk of poor mounting.
Also, the external electrode of the electronic chip component is rounded off in the widthwise direction thereof as shown in
FIG. 10A
because of its short width. As a result, the length of the contact area between the external electrode and the inspection terminal is short, and thus, the pressing force per unit length caused by the inspection terminal increases, thereby leading to a large cut-in depth of the edge portion and consequently causing the inner electrode layer to be easily exposed to the outside.
SUMMARY OF THE INVENTION
In order to overcome the problems described above, preferred embodiments of the present invention provide an inspection terminal for inspecting an electronic chip component by accurately measuring the characteristic of the component without exposing an inner electrode layer constituting an external electrode of the component to the outside, and an inspection method using such an inspection terminal.
Also, preferred embodiments of the present invention provide an inspection apparatus which allows the inspection terminal to come into reliable contact with the external electrode of the electronic chip component by using the above-described inspection terminal and inspection method.
According to a preferred embodiment of the present invention, an inspection terminal, which contacts an external electrode of an electronic chip component for measuring a characteristic of the electronic chip component, includes a liner edge portion disposed at the end of the terminal, wherein the edge portion has an obtuse angle.
In such an inspection terminal, the edge portion has an angle preferably greater than about 90° and equal to or smaller than about 120°.
According to another preferred embodiment of the present invention, an inspection method for inspecting an electronic chip component includes the steps of preparing the inspection terminal according to the preferred embodiment described above, bringing the linear edge portion into contact with an external electrode of the electronic chip component so as to be substantially parallel to the longitudinal direction of the external electrode, and inspecting the electronic chip component in this cont
Keating & Bennett LLP
Kobert Russell M.
Murata Manufacturing Co. LTD
Tang Minh
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