Metal fusion bonding – Process – With clamping or holding
Reexamination Certificate
2002-01-17
2003-12-23
Dunn, Tom (Department: 1725)
Metal fusion bonding
Process
With clamping or holding
C228S047100, C228S044300
Reexamination Certificate
active
06666371
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a sealing system for sealing a package on which an electronic device element is mounted, and a cap, and a sealing method therefor, and more particularly to a sealing system for sealing a package and a cap while securing them with a multi-clip, and a sealing method therefor.
2. Description of the Related Art
Recently in the electronic equipment field, electronic devices where such electronic device elements as an SAW (Surface Acoustic Wave) filter and a semiconductor chip are mounted on a box-shaped package, and the opening of the package is sealed by a cap, are manufactured to meet the demand for downsizing and decreasing price.
FIG. 13A
is a cross-sectional view of such an electronic device
60
. As
FIG. 13A
shows, an electronic device element
80
is mounted on a box-shaped package
81
, and the electronic device
60
is configured by sealing the opening of the package
81
with the cap
82
with solder.
FIG. 13B
is a diagram depicting a conventional sealing method. As
FIG. 13B
shows, the cap
82
with solder is superimposed on the package
81
on which the electronic device element
80
is mounted in the chamber
85
, and heater electrodes
83
and
84
(surface temperature, about 500° C.) are contacted from the top and the bottom in a space filled with nitrogen gas, and the solder is melted by this heat for sealing. In this case, solder composed of gold-tin (Au-Sn) alloy, which eutectic point is 340° C., is used, for example.
Another sealing method is a sealing method by seam welding. In this method, a cap
82
is covered on a package
81
where a seal ring is attached, electric current is supplied to the contact face between the package
81
and the cap
82
by a roller electrode, and the cap
82
is sealed by welding.
However, with the conventional sealing method using the heater electrodes
83
and
84
, the temperature of the package
81
rapidly rises, and the package
81
may crack due to heat shock, which drops the reliability of the electronic device
60
. Also the set temperature of the heater electrodes
83
and
84
is high, which wears out the heater electrodes
83
and
84
considerably, and maintenance for this makes it difficult to improve productivity.
In the case of the conventional sealing method using the heater electrodes
83
and
84
, it is also difficult to select an appropriate temperature profile for melting the solder, and therefore, the change of the eutectic point due to a subtle change of the gold-tin (Au-Sn) alloy solder components cannot be appropriately responded.
In the case of the sealing method by seam welding, on the other hand, strain at four corners of an electronic device is large when this method is applied to a small-sized electronic device
60
, which may drop the air tightness quality of the electronic device
60
.
SUMMARY OF THE INVENTION
With the foregoing in view, it is an object of the present invention to provide a sealing system and sealing method therefor which implement an optimum temperature profile for solder melting, and which can improve productivity.
To achieve the above object, one aspect of the present invention comprises a sealing machine for superimposing a pre-soldered cap onto the opening of a package on which an electronic device element is mounted, a multi-clip for receiving and holding a plurality of sets of the packages and caps superimposed by the sealing machine in batch, and a sealing furnace for heating the plurality of sets of the packages and caps held in batch by the multi-clip, and generating a plurality of electronic devices in batch by melting the previously applied solder and sealing the plurality of sets of the packages and caps.
According to the present invention, the plurality of sets of the packages and caps which are held in batch by the multi-clip are heated and sealed, so the sealing efficiency of the packages and caps can be improved.
Also an optimum temperature profile for melting the solder can be used in the sealing furnace, so the thermal stress on a package can be decreased, and the air tightness quality of the electronic device can be improved.
In the above-mentioned invention, it is preferable that the sealing machine further comprises a package supply block for storing a plurality of the packages, a cap supply block for storing a plurality of the caps, a cap loading stage for superimposing the caps supplied from the cap supply block onto the openings of the packages supplied from the package supply block, and a clip transporting block for transporting the plurality of sets of the packages and caps held in batch by the multi-clip to the sealing furnace.
Also preferably, the sealing machine further comprises a rotary table on which a plurality of the cap loading stages are set, and in each of the cap loading stages, the packages are supplied at a first rotational position of the rotary table, the caps are supplied at a second rotational position of the rotary table, and the plurality of sets of the superimposed packages and caps are supplied to the clip transporting block at a third rotational position of the rotary table.
Also preferably, the sealing system further comprises a clip tray on which a plurality of the multi-clips can be aligned, and the clip transporting block aligns the multi-clips holding the plurality of sets of packages and caps on the clip tray, and transports the multi-clips to the sealing furnace.
Also preferably, the clip tray has a plurality of protrusions for aligning the multi-clips, and the multi-clips have set holes where the protrusions are to be inserted.
According to the present invention, the multi-clips can be accurately aligned on the clip tray by inserting the protrusions formed on the clip tray into the set holes formed on the multi-clips, so the temperature conditions in the sealing furnace can be made uniform, and the air tightness quality of an electronic device can be improved.
To achieve the above object, another aspect of the present invention is a clip for holding superimposed packages and caps in a sealing system, comprising a receiver that can contact with a plurality of sets of the superimposed packages and caps on a same plane, a shaft secured to the receiver, a plurality of pressers which can rotate around this shaft, and an elastic body which applies an independent rotational driving force to the plurality of pressers, wherein the receiver and the plurality of pressers can hold the plurality of sets of the superimposed packages and caps independently by the independent rotational driving force.
According to the present invention, the plurality of sets of the packages and caps held by the multi-clip can be heated and sealed in batch, so the sealing efficiency of the packages and caps can be improved.
In the above invention, it is preferable that stoppers which are attached to the pressers for restricting the rotational angle of the pressers, are included in the present invention.
According to the present invention, the tips of the pressers do not become lower than a specific height even if the multi-clip is not holding the packages and caps, so a collision of the tips of the pressers with the laser imprinting stage can be prevented even if the multi-clip approaches the laser imprinting stage without holding the packages and caps, and the rubbing of the tips of the pressers against the surface of the cap loading stage can be prevented even if the multi-clip moves away from the cap loading stage without holding the packages and caps.
In the above invention, it is preferable that the pressers are made of a thin plate with a rib structure.
According to the present invention, the strength of the multi-clip can be maintained and warping or deformation can be prevented by the rib structure, so the plate thickness of the multi-clip can be decreased, and the heat capacity of the multi-clip can be decreased so as to drop heat loss in the sealing furnace.
REFERENCES:
patent: 4558812 (1985-12-01), Bailey et al.
patent: 4602417 (1986-07-01), Mesch et al.
p
Ikeda Yuji
Nakazawa Tetsuji
Takahashi Katsuhiko
Cooke Colleen P.
Dunn Tom
Fujitsu Media Devices Limited
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