Metal working – Method of mechanical manufacture – Electrical device making
Reexamination Certificate
2000-02-16
2004-02-24
Tugbang, A. Dexter (Department: 3729)
Metal working
Method of mechanical manufacture
Electrical device making
C029S843000, C029S852000, C029S832000, C228S180210, C174S034000, C174S260000, C361S800000, C361S816000, C361S818000
Reexamination Certificate
active
06694610
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an electronic component and a method of producing the same, and more particularly to an electronic component, such as a high-frequency composite module used in the communication field, having a structure in which a surface-mount part is accommodated in a case, and a method of producing the same.
2. Description of the Related Art
One method of producing an electronic component
60
having a structure in which surface-mount parts
64
are accommodated in a shield case
65
is illustrated in FIG.
9
. It is disclosed in, for example, Japanese Unexamined Patent Publication No. 10-13078.
According to this method, the electronic component
60
is producing by carrying out the following steps
1
to
6
.
Step
1
: As shown in
FIG. 10
, through holes
62
are formed in a sheet board
61
comprising a plurality of boards
51
for mounting parts thereon, and electrodes
63
for mounting shield cases
65
thereon are formed at side surfaces defining the through holes
62
.
Step
2
: Then, the surface-mount parts
64
are mounted onto the sheet board
61
, and soldered onto land electrodes (not shown) on the sheet board
61
.
Step
3
: After the soldering, the through holes
62
are filled with solder pastes
67
.
Step
4
: After the filling, pawls (engaging portions)
66
of a plurality of the shield cases
65
are inserted into their corresponding through holes
62
filled with the solder pastes
67
.
Step
5
: Next, the solder in the solder pastes
67
is melted in order to solder the shield cases
65
onto the sheet board
61
. As shown in
FIG. 9
, the pawls (engaging portions)
66
of each shield case
65
are joined and affixed to the sheet board
61
by soldering them onto the electrodes
63
(see
FIG. 10
) in the through holes
62
.
Step
6
: After affixing the pawls
66
, the sheet board
61
is cut along line A—A with, for example, a dicing machine, whereby individual electronic components
60
, one of which is shown in
FIG. 9
, are obtained.
Accordingly, in this conventional method, after soldering the surface-mount parts
64
onto the sheet board
61
(step
2
), the shield cases
65
are mounted onto the sheet board
61
in order to insert the pawls
66
into their corresponding through holes
62
filled with the solder pastes
67
(step
4
). Thereafter, the solder in the solder pastes
67
filling the through holes
62
is melted in order to solder the shield cases
65
onto the electrodes
63
in the sheet board
61
(step
5
). However, in this conventional method, two soldering steps, namely, the step of soldering the surface-mount parts
64
and the step of soldering the shield cases
65
are required. This restricts productivity.
In addition, in the above-described conventional method, the step of soldering the surface-mount parts
64
is generally carried out using a reflow soldering method. After soldering the surface-mount parts
64
by the reflow soldering method, the shield cases
65
are separately soldered by the same reflow soldering method. This means that the surface-mount parts
64
are put into a reflow oven twice. When the surface-mount parts
64
are put into the reflow oven twice, the properties of the surface-mount parts
64
may change because of the high temperature in the reflow oven. This results in the problem of reduced reliability of the products.
SUMMARY OF THE INVENTION
Accordingly, in order to overcome the above-described problems, it is an object of the present invention to provide an electronic component production method that allows electronic components having a structure in which surface-mount parts are accommodated in shield cases to be efficiently produced without causing changes in the properties thereof; and to provide highly reliably electronic components that are efficiently produced by this method.
To this end, according to one aspect of the present invention, there is provided an electronic component production method in which the electronic component has a structure in which a surface-mount part is accommodated in a shield case, the method comprising the steps of:
applying solder paste to a connection land electrode, to which the surface-mount part is to be electrically and mechanically connected, and a case-fixing electrode, to which an engaging portion of the shield case for accommodating the surface-mount part is to be electrically and mechanically joined and affixed, the connection land electrode and the case-fixing electrode being disposed on a printed board onto which the surface-mount part is to be mounted;
mounting the surface-mount part and the shield case onto predetermined locations of the printed board, the shield case being mounted so as to accommodate the surface-mount part therein; and
carrying out reflow soldering in order to solder at the same time the surface-mount part onto the connection land electrode and the engaging portion of the shield case onto the case-fixing electrode by putting the printed board on which the surface-mount part and the shield case are mounted into a reflow oven and melting the solder in the solder paste.
In this case, solder paste is applied to both the connection land electrode, to which the surface-mount part is to be electrically and mechanically connected, and case-fixing electrode, to which the engaging portion of the shield case is to be electrically and mechanically joined and affixed. Next, with the paste being applied, the surface-mount part is mounted onto a predetermined location of the printed board, and the shield case is mounted onto the printed board so that the surface-mount part is accommodated in the shield case. Then, the printed board is put into the reflow oven in order to solder the surface-mount part onto the connection land electrode and the engaging portion of the shield case onto the case-fixing electrode used for affixing the case thereto. Therefore, both the surface-mount part and the shield case can be mounted onto the printed board at the same time in one soldering step. Consequently, an electronic component can be efficiently produced without causing changes in the properties thereof. Since the step of melting solder can be finished only at one time and thermal stress to the surface-mount parts can be reduced, deterioration in property due to the thermal stress applied to the surface-mount parts mounted on the printed board can be prevented and the reliability can be improved.
The shield case is prevented from dropping and shielding performance can be improved in a case where stresses from other directions applied to the shield case, since the case-fixing electrode is disposed on the printed board for mounting the surface-mount parts, and the shield case is soldered to the case-fixing electrode.
Another aspect of the present invention provides the manufacturing method in which the solder-paste-applying method is carried out so that the solder paste is applied to the connection land electrode and the case-fixing electrode at the same time.
In the step of applying the solder paste, the solder paste is applied to the connection land electrode and the case-fixing electrode at the same time. In this case, since providing the solder with the printed board, for example, printing or applying can be finished in only one step during entire process, the number of manufacturing steps can be reduced, which leads to improvement of productivity and reduction in manufacturing cost.
Another aspect of the present invention provides the manufacturing method in which the solder-paste-applying method is carried out so that the solder paste is applied in separate stages of manufacturing to the connection land electrode and the case-fixing electrode.
In the step of applying the solder paste, the solder paste is separately applied to the connection land electrode and the case-fixing electrode. In this case, other steps of manufacturing process can be added between the step of applying the solder paste to one electrode and the step of applying the solder paste to the other electrode. This
Keating & Bennett LLP
Murata Manufacturing Co. Ltd.
Tugbang A. Dexter
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