Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Reexamination Certificate
2000-08-30
2003-03-04
Yao, Sam Chuan (Department: 1733)
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
C156S273900, C156S274800, C156S275500, C156S275700, C156S312000
Reexamination Certificate
active
06527903
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a substrate bonding method, a bonded product, an ink jet head, and an image forming apparatus. More particularly, the present invention is concerned with a substrate bonding method, a bonded product, an ink jet head, and an image forming apparatus, which are to be used in fabricating functional devices by various micromachining techniques.
2. Description of the Prior Art
According to a substrate bonding method so far adopted generally, an adhesive is used for bonding. However, as to functional devices fabricated using various micromachining techniques, there is a conspicuous tendency to microsizing and, in bonding using an adhesive, an inappropriate thickness of the adhesive and protrusion thereof give rise to a serious problem.
For example, as an ink jet head fabricating method, there has been proposed the use of two substrates bonded together, typical of which is disclosed in Japanese Published Unexamined Patent Application No. Sho 61-230954. However, as ink flowing grooves formed in bonding surfaces become higher in density and smaller in size, the application of an adhesive used in bonding becomes difficult. As a remedial measure there is proposed in Japanese Published Unexamined Patent Application No. Sho 63-34152 a technique in which an adhesive is applied thin and selectively.
Recently, however, there has been an increasing tendency to a smaller dot size with a view to attaining a high image quality in an ink jet head, and the size of a nozzle as an ink jet orifice is also becoming very small to meet the tendency to smaller dots. Such a reduction of the nozzle size is giving rise to the following several problems also in the method proposed in Japanese Published Unexamined Patent Application No. Sho 63-34152.
(1) The groove size in bonded surfaces is becoming extremely small with the recent tendency to a smaller nozzle size, and even a slight protrusion of an adhesive results in the nozzle and ink flowing grooves being filled up with the adhesive.
FIG. 9
shows ink jet head nozzle portions. The nozzle shown in
FIG. 9A
is a conventional 400 DPI equivalent nozzle having an ink droplet generating width of about 20 &mgr;m, and with this size, there is no fear of the nozzle being filled up with an adhesive
70
even by protrusion of the adhesive. But in case of such a reduced-size nozzle of about 5 &mgr;m in width as in
FIG. 9B
, which is equivalent to 1600 DPI and which generates ink droplets, the entire nozzle opening is filled up with protruded adhesive
70
and cannot eject ink.
(2) If the adhesive coating is made thin for preventing the foregoing protrusion of the adhesive into the ink flowing paths, there will occur defective sealing between ink flowing paths due to adhesive deficiency in a poor adhesion area which is attributable to the presence of fine convexes and concaves in bonding substrate surfaces or substrate warping, with consequent occurrence of an inconvenience such that a pressure developed for the ejection of ink in a certain ink flowing path escapes to an ink flowing path adjacent thereto. Therefore, for the purpose of improving the flatness of bonding substrate, surfaces there is adopted, for example, a planarizing process (Japanese Unexamined Patent Application No. Hei 11-245426) using CMP (Chemical Mechanical Polish). In bonding substrates of a large area, however, due to warping of wafers or the presence of particles, a substrate-to-substrate gap (bonding gap) of about 1.0 &mgr;m or less occurs in the foregoing defective adhesion area.
(3) As a result of having used the ink jet nozzle for a long period of time, a thin adhesive film which has been transferred to a protruded portion of the adhesive or to an unbonded portion comes off and may cause clogging of the nozzle.
FIG. 10A
shows an ink flowing path structure in the ink jet head and
FIG. 10B
is a sectional view taken on line X—X in FIG.
10
A. In the case where a thin adhesive film is transferred to a convex portion formed on an ink flowing path substrate
40
and the substrate
40
and a device substrate
26
are bonded together, there occurs a state in which the adhesive is transferred but bonding is not made at rear wall portions of individual flow paths
44
corresponding to bypaths.
In an effort to solve the abovementioned problems, various techniques have been proposed which do not use any adhesive, such as eutectic bonding and room temperature interface bonding. In eutectic bonding, however, it is necessary to form a thin Au film, resulting in an increase of the manufacturing cost. In room temperature interface bonding, it is necessary to perform a special interface treatment using an ultra-high vacuum or an ion beam, thus requiring the use of special equipment.
Further, in anodic bonding, it is necessary to apply a voltage as high as several hundred volts, with consequent danger of transistors, etc. being destroyed in case of a substrate having an electronic circuit.
As a bonding method which is carried out through a resin layer, there is known a thermocompression bonding, but it is necessary to apply a high pressure (4.9×10
5
to 9.8×10
5
Pa), thus requiring the use of special equipment. In addition, there arises a problem in point of reliability of a circuit-mounted board because of application of a high pressure. In forming fine patterns, there arises the same problem as in the use of an adhesive in point of thickness and protrusion of a resin layer.
SUMMARY OF THE INVENTION
The present invention has been accomplished for solving the abovementioned problems and provides a substrate bonding method, a bonded product obtained by using the substrate bonding method, an ink jet head, and an image forming apparatus, capable of implementing a satisfactory bonded state at low cost.
For solving the foregoing problems, in the substrate bonding method according to the present invention, a resin material is sandwiched between plural substrates and voltage is applied across the plural substrates to bond the substrate together. In the present invention, a plus side of a resin material which has been dipole-polarized by the application of voltage across plural substrates and a substrate on a minus electrode side attract each other by an electrostatic attraction, while a minus side of the resin material and a substrate on a plus electrode side attract each other by an electrostatic attraction, with the result that the resin material gets in fine concaves and convexes on the substrate interface, thus creating an anchor effect, whereby the substrates are bonded together through the resin material. Further, it is presumed that minus ions migrate from the resin material to the substrate side and undergoes a chemical reaction with the material of the substrate, with consequent chemical bonding reinforcing the substrate bonding. Thus, the substrate bonding does not require the use of any adhesive, nor is it necessary to use any equipment for implementing high temperature and high pressure conditions. Consequently, a satisfactory bonding free of adhesive protrusion can be attained at low cost.
It is preferable that the applied voltage be 350V or lower and be 50V or so. With such a level of voltage, the resin material is shifted moderately and a satisfactory bonding is obtained; in addition, since such a high voltage of several hundred volts as in the anodic bonding is not applied, it is not necessary to use any special equipment and bonding can be done at low cost.
By applying pressure to the plural substrates at the time of the voltage application there can be attained a better bonded state.
It is preferable that the plural substrates be held at a temperature of 200° C. or higher at the time of the voltage application.
It is preferable that a maximum temperature of the plural substrates at the time of the voltage application be a heat-resisting temperature of the resin material or lower and a glass transition point temperature of the resin material or higher. If the substrate temperature is the glass
Funatsu Norikuni
Iwamori Toshimichi
Kataoka Masaki
Murata Michiaki
Tanaka Kumiko
Fuji 'Xerox Co., Ltd.
Yao Sam Chuan
LandOfFree
Substrate bonding method, bonded product, ink jet head, and... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Substrate bonding method, bonded product, ink jet head, and..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Substrate bonding method, bonded product, ink jet head, and... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3036795