Electricity: electrical systems and devices – Electrostatic capacitors – Fixed capacitor
Reexamination Certificate
1999-04-16
2001-11-20
Bowers, Charles (Department: 2813)
Electricity: electrical systems and devices
Electrostatic capacitors
Fixed capacitor
C361S437000, C361S437000
Reexamination Certificate
active
06320739
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an electronic part constituted by sealing a chip device in a cavity of a resin container and a manufacturing method therefor.
In recent years, size reduction and improvement in the performance of a variety of electronic apparatuses, such as portable telephones and personal computers, have proceeded. Therefore, size reduction, improvement in the reliability, cost reduction and so forth of the electronic part are required to be flexibly adaptable to dense mounting, such as chip-on-board mounting with which a multiplicity of bare chip devices (bare chips) are directly mounted on a printed circuit board.
In addition to the conventional resistors, capacitors, coils and semiconductor devices, the electronic parts for use in the electronic apparatus have been varied which include, for example, electro-optic devices and surface-acoustic-wave devices, which incorporate mechanically weak materials, such as the ferroelectric piezoelectric single-crystal substrates. In the foregoing circumstance in which the electronic parts have been varied, optimum mounting must be performed to protect the surface of the electronic part while considering adaptation to common use and standardization. Since the materials for use in the electronic parts have been varied recently, the conventional rough method of directly covering the surface of a passive device or a transistor, with a silicon resin or an epoxy resin cannot realize satisfactory reliability because resistance against thermal stress and mechanical impact is unsatisfactory.
Therefore, the electronic parts including the electro-optical devices or the surface-acoustic-wave devices which use mechanically weak materials, have been mounted by a method of, for example, forming a cavity in a resin container and mounting a chip in the cavity.
FIGS. 6A and 6B
are perspective views showing the structure of a conventional electronic part which is a surface-acoustic-wave device taken as an example. Initially, a chip device
32
is mounted on a resin board
31
. Then, an adhesive agent is applied to the peripheral portion of the upper surface of the resin board
31
or an adhesive sheet layer is interposed. Then, a frame
33
is overlaid around the chip device
32
such that accurate locating is performed. Then, while pressure is being applied, a first heating and bonding process is performed to bond the frame
33
to the resin board
31
(see FIG.
6
A). Then, while close attention is being paid to prevent discharge of the adhesive agent from the top end of the frame
33
and omission from the application of the adhesive agent, an adhesive agent or the like is applied to the upper surface of the frame
33
, the cover
34
is mounted on the frame
33
, and then a second heating and bonding process is performed such that pressure is again applied (see FIG.
6
B). As described above, the bonding process is performed such that the application of the pressure and heat are performed two times. Then, a resin container
30
having a cavity
35
in which the chip device
32
is accommodated is formed. Thus, the electronic part has been manufactured.
The reason why the flat resin boards are superimposed to form a multilayer structure similar to a sandwich is that the manufacturing cost must be reduced. Examples of the foregoing structure have been disclosed also in Japanese Patent Laid-Open No. 2-179018. With the conventional technique, the chip device
32
is mounted on the resinboard
31
, and then the frame
33
is bonded. Another example is structured such that the frame
33
is bonded to the upper surface of the resin board
31
to form a recess on which the chip device
32
is mounted.
However, the above-mentioned conventional technique is required to accurately locate the bonding positions whenever the resin board is overlaid. When the size of the electronic part is furthermore reduced, the relative positions among the boards and the positions of the adhesive agents and the adhesive layers must accurately be located whenever the board is overlaid. Thus, there arises a problem in that satisfactory productivity cannot be realized and the operation cost cannot be reduced.
In general, plastic deformation of the resin board easily occurs when the resin board is heated or pressed. When the adhesive process for heating the resin board while applying pressure to the resin board is performed repeatedly, the amounts of deformation is accumulated excessively to perform accurate locating. What is worse, the sealing characteristic deteriorates, leak easily takes place and the reliability deteriorates. When the process for bonding the resin boards to each other is performed by using a prepreg or an adhesive resin, the bonded prepreg or the adhesive resin is softened or deformed if the pressure and heat are applied afterwards. Therefore, there arises a problem in that the resin components seep and the resin container is deformed and distorted. Another problem arises in that a portion of the resin component is gasified and the inside portion of the resin container is filled with the gas. In this case, the gasified resin adheres to the surface of the chip device. Thus, the chip device is contaminated.
SUMMARY OF THE INVENTION
An object of the present invention is to provide an electronic part which is capable of solving the above-mentioned problems, which permits size and cost reduction to easily be performed and which improves the reliability and a manufacturing method therefor.
To achieve the above-mentioned object, an electronic part according to the present invention in which a chip device having bump electrodes is sealed in a cavity of a resin container, wherein the resin container includes: a mounting board having a conductor pattern formed on at least either surface of a resin member for the purpose of bump-mounting the chip device; an intermediate board constituted by a frame-shape resin member, which is overlaid on the mounting board, which has a window for forming an inner wall apart from the chip device for predetermined distances and which is made of a frame-shape resin member; a cover board constituted by a resin member overlaid on the intermediate board to cover the window; a first adhesive layer which is interposed between overlaid portions of the mounting board and the intermediate board; and a second adhesive layer which is interposed between overlaid portion of the intermediate board and the cover board, wherein the first and second adhesive layers between which the intermediate board is interposed are heated and pressed at a time in a direction of the thickness of each of the mounting board and the cover board; and the mounting board, the intermediate board and the cover board are brought into intimate contact with one another so as to seal and form the cavity defined by the inner wall of the window.
According to the present invention, the mounting board and the cover board are located and applied with pressure and heat from outside only one time. Thus, the first adhesive layer and the second adhesive layer bond the mounting board, the intermediate board and the cover board by one-time adhesive process so as to seal and form the cavity in the resin container.
According to the present invention, there is provided a method of manufacturing an electronic part incorporating a chip device which is provided with bump electrodes and which is sealed in a cavity of a resin container, the method of manufacturing an electronic part comprising: a first step for bump-mounting the chip device on a conductor pattern of a mounting board provided with the conductor pattern for at least either surface of a resin member; a second step for overlaying an intermediate board which incorporates a frame-shape resin member having a window formed apart from the chip device for predetermined distances on the mounting board such that the first adhesive layer is interposed; a third step for overlaying a cover board constituted by a resin member for covering the window on the intermediate board such that a second adhesive la
Gotoh Masashi
Kanazawa Jitsuo
Yamamoto Syuichiro
Bowers Charles
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Schillinger Laura M
TDK Corporation
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