Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
2000-11-09
2002-09-17
Vo, Anh T. N. (Department: 2861)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
Reexamination Certificate
active
06450617
ABSTRACT:
This application is based on Japanese Patent Application No. 11-321372 (1999) filed Nov. 11, 1999, the content of which is incorporated hereinto by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an ink jet print head that prints on a print medium by ejecting from nozzles a printing liquid (hereinafter referred to as an ink) in the form of flying droplets onto the print medium to make them adhere to the print medium, and an ink jet printing apparatus using such ink jet print head.
2. Description of the Related Art
An ink jet print head has been known in which a silicon substrate is placed on an aluminum support member bonded with a printed circuit board and is electrically connected through wire bonding to the printed circuit board and in which a connecting portion for a printer body is disposed on the same side of the silicon substrate where electrothermal transducers are arranged, or on the back side of the silicon substrate.
In more concrete terms, because the printed circuit board cannot be bent, the connecting portion for the printer can only be provided on the same side of the silicon substrate where the electrothermal transducers are arranged or on a side opposite to where the electrothermal transducers are arranged.
In another ink jet print head, such as disclosed in U.S. Pat. No. 4,635,073 or 4,827,294, the silicon substrate with electrothermal transducers for ejecting ink is enclosed by a wiring member on a tape-like insulating film (hereinafter referred to as a TAB film).
Normally, in the case of semiconductor devices using the TAB film or of an ink jet print head, the four sides of a chip is surrounded by the TAB film.
In a further print head, such as disclosed in Japanese Patent Application Publication No. 5-169662 (1993), a flexible printed circuit substrate (FPC) attached with a glass epoxy substrate on the back is used, and the silicon substrate and the bonding portion of the flexible printed circuit substrate are bonded on a support member of an aluminum (Al) plate and are electrically connected together by wire-bonding. The flexible printed circuit substrate is bent so that the surface for electrical connection to the printer can be disposed on the back side of the support member with respect to the side where the electrothermal transducers are provided.
In this conventional construction, however, when a flexible substrate is used to provide an electrical connection surface for the printer body which is at an angle to the side of the silicon substrate where the electrothermal transducers are provided, the wire bonding requires fixedly holding the silicon substrate and the flexible printed circuit substrate opposed to each other on the same member. Hence, a holding member must be used. Further, it is also necessary in a last step to secure to the holding member the flexible printed circuit substrate's electrical connection surface for the printer body. This step must be carried out separately from the step of securing the silicon substrate and the flexible printed circuit substrate opposite the silicon substrate. This will increase the cost. When, for example, two heads are arranged parallelly, with one head used for ejecting a black ink and the other for ejecting color inks, the above steps need to be performed for each of the two heads, increasing the cost. Further, in the ink jet print head using the above-described TAB film, the construction in which the silicon substrate is enclosed by the TAB film on four sides becomes a hindrance when the ink is ejected by using the electrothermal transducers.
To solve these problems the inventors of this invention proposed an ink jet print head in which three of the four sides of a rectangular silicon substrate incorporating electrothermal transducers and a drive circuit for driving the electrothermal transducers are surrounded by the TAB film; in which the electrothermal transducers are arranged along the side that does not face the TAB film so that a plurality of silicon substrates can be joined to the top plate formed integral with the nozzles; and in which the connecting portion for the printer body can be arranged at an angle to the ink ejection direction.
Further, in another proposed ink jet print head, two chips of silicon substrate using the above proposal are joined to the integrally formed top plate, with one chip filled with ink and the other with a preprocessing liquid.
In the ink jet print head in which the two chips of silicon substrate proposed by the inventors are joined to the integrally formed top plate, with one chip using the ink and the other using the preprocessing liquid, because the number of electrodes formed in one chip is as small as 30, metal bulges formed on the electrodes of the silicon substrate (hereinafter referred to bumps) use stud bumps that are formed mechanically. In the case of the stud bumps, gold (Au) bumps
210
are provided on the aluminum electrodes
240
on the silicon substrate
100
; the silicon substrate
100
is covered with a protective film
255
of silicon nitride (SiN) to cover the remaining part of the aluminum electrodes
240
; and the leads
130
are connected at their free end to the bumps
210
of gold (Au), as shown in FIG.
2
. In this construction, however, not all area of the aluminum electrodes
240
on the silicon substrate
100
cannot be covered completely with the gold (Au) metal or protective film
255
, with the underlying aluminum electrodes
240
partially exposed.
In this case, because the ink is alkaline and must be neutralized, the preprocessing liquid is known to be acid. When the electrode areas on the silicon substrate are applied with an electric field by chlorine ions (Cl
−
) present in the preprocessing liquid, it has been found that the aluminum electrodes exposed at the periphery of the metal bulges (hereinafter referred to as stud bumps) mechanically formed on the electrodes on the silicon substrate are corroded.
To prevent corrosion due to the preprocessing liquid, the following electrode construction is proposed. That is, the construction that prevents corrosion of electrodes even in the presence of the preprocessing liquid has a layer of titanium-tungsten (TiW) deposited by sputtering, which is normally used as a barrier metal, and also bumps formed of gold (Au) by plating in order to prevent corrosion of aluminum (Al) electrodes that are used for electric connection with external circuits. Because the titanium-tungsten (TiW) is not corroded by the acidic preprocessing liquid or chlorine ions (Cl
−
) present in the preprocessing liquid, the titanium-tungsten (TiW) is made to overlap the silicon nitride (SiN), a protective film surrounding the electrodes, to completely cover the aluminum (Al) electrodes, thereby preventing the preprocessing liquid from corroding the electric wiring. Further, putting drawn-out wires of tantalum (Ta) under the titanium-tungsten (TiW) layer can obviate the need for contact holes in the protective film, which have conventionally been formed in the protective film before depositing tantalum (Ta) and processing it by patterning to draw out the uppermost tantalum (Ta) wires outside the chip. This in turn can reduce the number of processes by one and provide the silicon substrate less expensively and therefore an ink jet print head at lower cost.
A method has been proposed for detecting the presence or absence of ink by checking a capacitance component between the tantalum (Ta), a cavitation resistant film, as one electrode and another electrode arranged outside the print head. In an ink jet print head having a plurality of liquid chambers on one and the same silicon substrate, for example, the tantalum (Ta) electrode is divided into the same number of pieces as the liquid chambers, which are then drawn out of the silicon substrate to make it possible to detect when the ink in the common liquid chamber has run out.
The aluminum (Al) electrodes on the silicon substrate for the preprocessing liquid are formed in a corrosion-resistant structure i
Kitani Masashi
Ozaki Teruo
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Vo Anh T. N.
LandOfFree
Ink jet print head and ink jet printing apparatus using the... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Ink jet print head and ink jet printing apparatus using the..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Ink jet print head and ink jet printing apparatus using the... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2912885