Active solid-state devices (e.g. – transistors – solid-state diode – Responsive to non-electrical signal – Electromagnetic or particle radiation
Patent
1995-02-10
1997-02-25
Saadat, Mahshid D.
Active solid-state devices (e.g., transistors, solid-state diode
Responsive to non-electrical signal
Electromagnetic or particle radiation
257432, 349110, H01L 310203
Patent
active
056061943
DESCRIPTION:
BRIEF SUMMARY
The subject of the present invention is a device for encapsulating and passivating circuits, and especially flat-screen integrated control circuits.
A liquid-crystal flat screen consists of a certain number of electro-optical cells/transducers consisting of electrodes framing a liquid crystal, the optical properties of which are modified depending on the value of the field to which it is subjected and which are controlled by a switching device. Each of these elementary cells thus constituted is called a pixel.
The addressing of these pixels is performed by means of rows (selection lines) and of columns (data lines) driven by peripheral addressing circuits (also called drivers).
The electrodes, the switching devices, the rows and the columns are deposited and etched on the same substrate plate; they constitute the active matrix of the screen. Advantageously, the peripheral control circuits may themselves also be integrated onto the substrate plate including the active matrix. The problem of passivating and protecting them is then posed.
In fact, these devices are fragile and their reliability is achieved by effective protection against all types of attack which may modify their electrical behaviour. These attacks may be mechanical, due to impacts or scratches, chemical when, for example, the screen is cleaned with an organic solvent or an alcohol, or electrical when, for example, a polar water, alcohol or liquid crystal molecule introduces a stray capacitance into the circuit. Light is another type of attack which can modify the operation of a circuit by photoconductivity.
In a general way, the passivation of integrated circuits is achieved by a dual layer consisting of silicon nitride (SiN) isolating the active layers, and of a metal or of an opaque organic polymer of the polyimide type which protects them from the light and, in the case of active matrices of flat screens, calibrates the cavity in which the liquid crystal is placed. In this latter case, the support plate including the active matrix and the backing plate constituting the backing electrode are bonded to one another by means of a sealing bead generally of epoxy which also makes it possible to keep the liquid crystal within the cells. This type of device is described in detail in the patent application EP 0444621 from Casio.
The present invention makes it possible to optimize the passivation and the protection of electronic circuits produced on a substrate, by virtue of a judicious use of this sealing bead, and is particularly well adapted to that of the addressing circuits integrated on glass for active-matrix flat screens.
The present invention relates to a device for encapsulating and passivating electronic circuits produced on a substrate plate including a sealing bead, characterized in that this bead is used to passivate and protect these electronic circuits.
The present invention also relates to a device for encapsulating and passivating electronic circuits produced on a support plate on which an active matrix is also produced controlling electro-optical cells and including an opaque layer blocking the photoconductivity of the components of the active matrix performing the function of spacer and possibly that of "black matrix", which is characterized in that this layer is used for encapsulating and passivating the said electronic circuits.
This type of encapsulation and of passivation makes it possible to minimize the surface lost at the periphery of the active part of the screen without complicating the fabrication process in order to do so.
The present invention will be better understood and additional advantages will appear in the description which will follow, illustrated by the following Figures:
FIG. 1 represents a sectional view of a liquid-crystal screen according to a first embodiment of the invention,
FIG. 2 represents a sectional view of a liquid-crystal screen according to a second embodiment of the invention,
FIG. 3 represents a plan view of a liquid-crystal screen equipped with a particular device of the second embodiment,
REFERENCES:
patent: 5132830 (1992-07-01), Fukutani et al.
patent: 5185653 (1993-02-01), Switky et al.
patent: 5299041 (1994-03-01), Morin et al.
patent: 5539552 (1996-07-01), Desai et al.
Lebrun Hugues
Mulatier Laurence
Clark S. V.
Saadat Mahshid D.
Thomson-LCD
LandOfFree
Device for encapsulating and passivating a circuit for flat scre does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Device for encapsulating and passivating a circuit for flat scre, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Device for encapsulating and passivating a circuit for flat scre will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1976020