Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Reexamination Certificate
1999-01-08
2001-03-06
Ball, Michael W. (Department: 1733)
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
C156S273100, C065S040000, C065S043000
Reexamination Certificate
active
06197139
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is directed to an electrostatic thermal bonding of glass substrates, and in particular to an improved electrostatic thermal bonding method capable of easily and solidly bonding a pair of glass substrates without using an adhesive or a high-temperature process.
2. Description of the Background Art
An electrostatic thermal bonding method was introduced in 1969, and then a silicon-glass bonding and a silicon-silicon bonding utilizing a glass thin film have been used in packaging of miniature devices. The thermal expansion coefficient of a glass used for the electrostatic thermal bonding is almost identical with that of a silicon, and materials containing metallic elements therein having a remarkable ionization tendency such as natrium and lithium are used for the glass to be bonded. For the silicon-glass bonding, when the silicon substrate and glass substrates are brought face to face with each other and heated to a predetermined temperature, and then the metal elements inside the glass substrates are ionized into the ionic condition having constant electric charges. Here, in the case that an external direct current voltage of a cathode is applied to the glass substrates, the ionized metal ions are moved into the cathode due to the electric field generated at both end portions of the silicon-glass interface and a space charge section is formed at the interface of the silicon-glass. A strong electrostatic force is generated due to the space charges. The silicon and the glass substrates are forced to be pulled toward each other by the electrostatic force, and thus a bonding of the silicon and the glass substrates is performed.
However, in the case of a flat-plate display device, the bonding of the two glass substrates is conventionally performed utilizing a method for bonding a pair of glass substrates by putting glass frit on a surface of one glass substrate, facing the pair of substrates to one another, and heating the glass substrates to a temperature of about 450 to 600° C. for melting the glass frit, whereby the pair of glass substrates are bonded
As mentioned above, the conventional electrostatic thermal bonding methods have been limited to a silicon-glass bonding and silicon-silicon bonding utilizing a glass thin film. That is, the conventional electrostatic thermal bonding methods have not been adopted for a glass—glass bonding related to a display device.
In the studies recently performed with regard to the packaging of flat-plate display devices, a glass—glass bonding using a glass frit is utilizing for bonding glass substrates. However, such a packaging, i.e., the conventional glass—glass bonding method has disadvantages in that the longevity of the device is reduced due to the high temperature bonding and the device is contaminated by gas generated during the melting of the glass frit, which results in inferior effect on the condition that a vacuum packaging should be performed.
SUMMARY OF THE INVENTION
It is therefore a primary object of the present invention to provide a method for bonding glass substrates in a solid condition by using a silicon-glass bonding mechanism which is a basic concept of the electrostatic thermal bonding, without using an adhesive or a high temperature process.
It is another object of the present invention to provide a vacuum packaging method by bonding glass substrates, which method is capable of achieving a excellent vacuum degree between the glass substrates by sequentially forming a metal thin film electrode and a silicon thin film on one glass substrate and applying a predetermined direct current voltage between the other glass substrate and the metal thin film.
In order to achieve the above-described objects, in accordance with the present invention, there is provided a thermal bonding method for bonding glass substrates by utilizing a silicon thin film comprising: forming a metal thin film electrode on a surface of one of two glass substrates; forming a silicon substrate on the metal thin film; bringing the silicon substrate into contact with the other glass substrate; and applying a direct current voltage in the range of 0 to 1000V between the metal thin film and the glass substrate on which the metal thin film is not formed under a temperature of between 100° C. and 500° C. In addition, it is preferable that the process for applying a predetermined direct current voltage between the metal thin film and the glass substrate is performed by connecting an anode of a direct current voltage source to the metal thin film formed on the one glass substrate, and connecting a cathode of the direct current voltage source to the other glass substrate.
REFERENCES:
patent: 4452624 (1984-06-01), Wohltjen et al.
patent: 5141148 (1992-08-01), Ichiyawa
patent: 5396042 (1995-03-01), Ishida et al.
patent: 5695590 (1997-12-01), Willcox et al.
Choi Woo-Beom
Ju Byeong-Kwon
Oh Myung-Hwan
Ball Michael W.
Haran John T.
Korea Institute of Science & Tech.
Ostrolenk Faber Gerb & Soffen, LLP
LandOfFree
Method for electrostatic thermal bonding of a pair of glass... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method for electrostatic thermal bonding of a pair of glass..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for electrostatic thermal bonding of a pair of glass... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2438249