Semiconductor device manufacturing: process – Packaging or treatment of packaged semiconductor – Metallic housing or support
Reexamination Certificate
2001-08-29
2004-05-04
Potter, Roy (Department: 2822)
Semiconductor device manufacturing: process
Packaging or treatment of packaged semiconductor
Metallic housing or support
C438S124000
Reexamination Certificate
active
06730546
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of Invention
The present invention relates to a resin-molded electronic component, and to a method of producing such a resin-molded electronic component.
2. Description of Related Art
In recent years, great reductions in the size and thickness have been achieved for various small-sized information devices, such as an HDD (hard disk drive), a mobile computer, and an IC card, and also for various mobile communication devices, such as a portable telephone, a mobile telephone, and a paging system. Correspondingly, enhancements in performance have been achieved for various electronic components, such as a piezoelectric resonator and a piezoelectric oscillator for use in information devices or communication devices, wherein, in many cases, these electronic components are produced into forms suitable for automatic mounting.
For example, in the case of a piezoelectric resonator of such electronic components, a quartz resonator chip serving as a piezoelectric material in the form of a very thin plate is disposed in a package. Such a quartz resonator chip includes metal electrode films formed in particular patterns and disposed on two opposite surfaces of the quartz plate. If a driving voltage is applied between the two electrode films, the quartz resonator chip vibrates at a specific vibration frequency depending upon the thickness of the quartz resonator chip. The vibration is converted into an electrical signal and used, as a clock signal, in a device in which the quartz resonator is disposed.
In such piezoelectric resonators, if a package in which a piezoelectric resonator chip is housed has a special shape, or if electrode terminals which are to be connected to a mounting board are formed at locations different from those of other types of electronic components, it is impossible to automatically mount piezoelectric resonators. To avoid the above problem, it is known to produce a molded component such that a package is molded with resin and electrode terminals are formed using lead frames so that the resultant molded component has a form suitable for automatic mounting using an automatic mounting machine.
When a piezoelectric resonator is produced into a molded form according to the conventional technique, electrode terminals must be formed so as to adapt to the external shape of a resin-molded part.
More specifically, in the case where an electronic component is produced in a resin-molded form, terminals must be formed so as to extend outwardly from a resin-molded part at locations precisely corresponding to lands of a conductive pattern formed on a mounting board.
To this end, before performing molding, an electronic component is precisely positioned with respect to a lead frame for forming a terminal (terminal-forming lead frame), and then lead terminals of the electronic component are connected to the terminal-forming lead frame. Thereafter, the electronic component connected with the lead frame is placed in a mold, and a molding material is injected into the mold thereby performing molding.
However, in many cases, electronic components, such as a piezoelectric resonator, are very small in size, and thus it is difficult to precisely position lead terminals of electronic components with respect to the terminal-forming lead frames. If the positioning is not precise enough, a good connection between lead terminals and a lead frame is not achieved, and thus a resultant product has degraded performance.
Furthermore, if an electronic component is not placed at a correct position in a mold, a problem not only occurs in forming electrode terminals, but also a problem occurs that the electronic component is not properly covered with a molding material and the electronic component is partially exposed from a resin-molded part.
The conventional molded component has another problem as described below.
FIG. 39
illustrates one production step of a conventional molded component. In this production method, an electronic component to be molded, that is, a piezoelectric resonator chip housed in a cylindrical package
511
, is inserted between lead frames
513
and
514
disposed on a terminal-forming frame
521
and is properly positioned.
As shown in
FIG. 39
, the lead frame
513
formed on one end of the terminal-forming frame
521
, which will become an electrode terminal of the molded component, includes a part
513
a
extending substantially horizontally from the terminal-forming frame
521
, a rising-up part
513
b
formed integrally with the horizontal part
513
a
and extending substantially vertically from the inner end of the horizontal part
513
a
, and a lead terminal connection part
513
c
extending horizontally from the upper end of the rising-up part
513
b.
On the other hand, a lead frame
514
formed on the other end of the terminal-forming frame
521
includes a rising-up part
514
b
formed on the inner end of the lead frame
514
and an outwardly extending part
514
a
which is integrally formed with the rising-up part
514
b
and which is connected to the terminal-forming frame
521
. After completion of a resin-molding process, an end portion of the outwardly extending part
514
a
becomes a horizontal part extending horizontally from a resin-molded part and serving as a dummy terminal.
After inserting the packaged electronic component
511
between the lead frames
513
and
514
located on the two respective ends, the outer lead
512
b
of the package
511
and the connection part of the lead frame
513
are welded to each other, as shown in an enlarged fragmentary view of
FIG. 40
, by applying a voltage between an upper electrode
532
and a lower electrode
531
of an electrode block (not shown in FIG.
40
).
In the above process, the outer lead
512
b
is put on the lead frame
513
, and the lower electrode
531
is brought from below into contact with the lead frame
513
, and the upper electrode
532
is brought from above into contact with the outer lead
512
b
. Thereafter, the voltage is applied between the upper electrode
532
and the lower electrode
531
while pressing the lead frame
513
and the outer lead
512
b
between the upper electrode
532
and the lower electrode
531
.
However, because the lead terminal connection part
513
c
extends substantially vertically from the rising-up part
513
b
of the lead frame
513
, a gap
513
e
is created when the lower electrode
531
comes into contact with a corner
513
d
at which the lead frame
513
is bent. If such a gap
513
e
is created, an applied current cannot flow sufficiently, and thus welding is not well performed.
After completion of the welding described above, the package
511
is sandwiched between an upper mold
534
and a lower mold
533
and a molding material is injected so as to mold the package
511
by transfer molding, as shown in FIG.
41
. In this molding process, if horizontally extending parts of the lead frames
513
a
and
514
a
are slightly inclined upwardly in an inward direction, a gap
533
a
or
533
b
is created.
The creation of the gap
533
a
or
533
b
can cause a molding material to intrude into the gap
533
a
or
533
b
, and thus can cause a burr to be created on a surface serving as a mounting surface, which is to be contacted with a surface of a mounting board when being mounted, of the molded component. The burrs can result in an insufficient mounting strength when the molded component is mounted on the board, and thus can cause degradation of quality.
The conventional molded component has still another problem as described below.
FIG.
42
(A) illustrates a process of producing a resin-molded part
515
by molding a package
511
with resin using a terminal-forming frame
521
. A gate
535
for use in molding is formed near a dummy-terminal lead frame
514
.
The lead frame
514
is formed integrally with the terminal-forming frame
521
made of metal such as a copper-based alloy.
More specifically, the terminal-forming frame
521
has a space
521
a
in the form of a rectangular window, which is larger than the size of the e
LandOfFree
Molded component and method of producing the same does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Molded component and method of producing the same, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Molded component and method of producing the same will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3197200