Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Reexamination Certificate
2000-11-02
2003-03-04
Mayes, Curtis (Department: 1734)
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
C156S314000, C156S329000, C156S330000, C156S356000, C156S538000, C156S578000, C029S739000, C029S740000
Reexamination Certificate
active
06527905
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a method for mounting an electronic component by means of arranging and sealing of the electronic component on an object such as a circuit board to which the component is mounted and, an apparatus and a dispenser used in the method.
BACKGROUND ART
A technique called as COB (CHIP ON BOARD) has attracted attention in recent years, as a way of mounting electronic components on a circuit board, in which electronic components are mounted onto electrodes on a circuit board in a state of the electronic components faced downward. The COB technique will be described with reference to the drawings.
FIG. 10A
is a flow chart of the conventional COB method. Based on this figure, the description is made. Referring first to
FIG. 10B
, according to the conventional COB method, an electronic component b is first arranged and bonded to a circuit board d. Electrode parts c as shown in
FIG. 10B
are provided on the circuit board d for the electric connection to the electronic component b. The circuit board d is held at a stage a in FIG.
10
B. Meanwhile, electrode parts of the electronic component b have bumps e to be bonded with the electrode parts c of the circuit board d. Each bump e is coated with a silver paste or the like for the bonding. The electronic component b is transferred while being sucked by a nozzle f, and positioned at an arrangement position on the board d. After the electronic component b is arranged on the board d, the silver paste is fused by heat thereby to bond the electronic component. Thereafter, a sealant is applied in the periphery of the electronic component b as indicated in FIG.
10
C. The sealant i is applied by a dispenser h along a higher position side of the electronic component b after the circuit board d is held slantwise with the use of, for instance, an inclination stage g shown in FIG.
10
C. In this manner, the applied sealant i is allowed to flow to a lower portion of the electronic component b along the inclination of the circuit board d. The sealant i is set with heat to complete the bonding. Reference symbol j in
FIG. 10C
indicates a positioning base for positioning the circuit board d.
The conventional method as above finds difficulty in flowing sealant i to the lower portion of the electronic component b, because a gap between a lower face of the electronic component b and the circuit board d is as narrow as several tens &mgr;m, and moreover the sealant i is highly viscous. A feed time for the flow of sealant i is consequently apt to be lengthy, in other words, production time is lengthened thereby lowering production efficiency. Besides, the sealant i fed to the gap tends to be insufficient in feed amount, resulting in the formation of air bubbles which are to be enclosed. When the air bubbles are present between the component b and the circuit board d, and the periphery of the electronic component b is sealed to tightly close the gap between them, an expansion/shrinkage of the air in the bubbles will occur due to change of the surrounding temperature. A pressure increase or decrease due to the expansion/shrinkage of air bubbles sometimes invites breaks of the electronic component b or the humidity in the air bubbles causes corrosion of the electrode or the like, thus leading to mounting faults.
The present invention is devised to solve the aforementioned issues, and has for its object to provide a method for mounting an electronic component by applying a sealant beforehand at an arrangement position of the component on an object where the electronic component is to be mounted thereby to positively apply the sealant under the electronic component, so that the electronic component can be sealed quickly and sufficiently with the occurence of breaks, corrosion or the like mounting failures being reduced, thereby improving production efficiency, and an apparatus and a dispenser used in the method.
SUMMARY OF INVENTION
In order to accomplish the above-described objective, a method for mounting an electronic component according to a first aspect of the present invention comprises:
a first application process of applying a sealant to a position of an object to which an electronic component is to be mounted where the electronic component is to be arranged, in a manner to avoid an electrode part of the object;
a bond process of arranging and bonding the electronic component at the arrangement position; and
a second application process of applying a sealant at least partly to periphery of the electronic component after bonded onto the object.
According to a second aspect of the present invention, in the first aspect, at least the first application process among the first and second application processes uses a writing method.
According to a third aspect of the present invention, in the first aspect, the first application process uses a screen print method.
According to a fourth aspect of the present invention, in any one of the first-third aspects, different sealants are used in the first and second application processes.
According to a fifth aspect of the present invention, in the fourth aspect, the sealant in the first application process has heat cycle function and moisture resistance and resists being mingled with air bubbles, while the sealant in the second application process smoothly fits to a bump of an electrode part of the electronic component, and has good fluidity and low surface tension.
According to a sixth aspect of the present invention, in any one of the first-fifth aspects, the sealant in the first application process is multifunctional epoxy, while the sealant in the second application process is one selected from silicone, flame retardant epoxy and acrylic resin.
According to a seventh aspect of the present invention, an apparatus for mounting an electronic component is provided, which comprises:
a holding device for holding an object to which the electronic component is to be mounted;
a first applying device for applying a sealant to an arrangement position of the object held by the holding device where the electronic component is to be arranged, in a manner to avoid an electrode part of the object;
a bonding device for arranging and bonding the electronic component at the arrangement position of the object; and
a second applying device for applying a sealant at least partly to periphery of the electronic component after bonded on the object.
According to an eighth aspect of the present invention, in the seventh aspect, at least the first applying device among the first and second applying devices is a writing device.
According to a ninth aspect of the present invention, in the seventh aspect, the first applying device is a screen printing device.
According to a 10th aspect of the present invention, in any one of the seventh-ninth aspects, different sealants are used in the first and second applying devices.
According to an 11th aspect of the present invention, in the 10th aspect, the sealant used by the first applying device has heat cycle function and moisture resistance and resists being mingled with air bubbles, while the sealant used by the second applying device smoothly fits to a bump of an electrode part of the electronic component, and has good fluidity and low surface tension.
According to a 12th aspect of the present invention, in any one of the seventh-11th aspects, multifunctional epoxy is used as the sealant used by the first applying device, while one selected from silicone, flame retardant epoxy, and acrylic resin is used as the sealant used by the second applying device.
According to a 13th aspect of the present invention, in any one of the seventh-12th aspects, the first applying device has a dispenser equipped with a plurality of discharge openings for the sealant, and control devices for controlling discharge amounts of the sealant from the corresponding discharge openings individually.
A dispenser according to a 14th aspect of the present invention is used in the mounting apparatus in any one of the seventh-13th aspects, which has a plurality of discharge openings
Enchi Kohei
Imanishi Makoto
Kabeshita Akira
Shida Satoshi
Mayes Curtis
Wenderoth , Lind & Ponack, L.L.P.
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