Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
1998-11-13
2003-08-26
Meier, Stephen D. (Department: 2853)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
C029S890100
Reexamination Certificate
active
06609783
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an ink jet recording head, a method for producing the same and a recording apparatus equipped therewith.
2. Related Background Art
The ink jet recording method, forming a record by generating small ink droplets and depositing such droplets onto a recording material such as paper, is featured by extremely low noise at the recording operation, ability of achieving high-speed recording and ability of recording on plain paper. Among such ink jet recording, particular attention is being paid to so-called bubble jet recording method utilizing an energy generating member for generating energy for ink discharge.
FIGS. 11A
,
11
B,
12
A and
12
B illustrate the representative film structure of a heater portion and an electric connection portion in the recording head for the above-mentioned bubble jet recording.
FIGS. 11A and 11B
show a heater board
100
of the bubble jet recording head, connected by wire bonding to a substrate (wiring substrate) for receiving an electrical signal from the printer. On an Si substrate
101
, there is formed a heat accumulation layer
102
, on which formed are a heat-generating element (electrical resistance layer)
103
for generating the ink discharging energy and a wiring (wiring electrode layer)
104
for supplying the heat-generating element with the electrical signal, with thin film forming technology. The heater board
100
is completed by forming thereon an insulation film
105
and a cavitation layer
106
. The electrical connection with the wiring substrate is achieved by bonding a wire
109
, with a wire bonding device, to a contact pad
111
provided in a contact hole (through hole)
107
which is opened in the protective layer.
FIGS. 12A and 12B
show another method of electrical connection in the bubble jet recording apparatus, in which an ink discharging element and a TAB tape are connected by the TAB method. On an Si substrate
101
, there is formed a heat accumulation layer
102
, on which formed are a heat-generating element
103
for generating the ink discharging energy and a wiring
104
for supplying the heat-generating element with the electrical signal, by thin film forming technology. On these layers, an insulation film
105
is formed, and a contact hole
107
is formed for electrically connecting the heat-generating wiring
104
with an electrical connection layer formed on top. Then a cavitation layer
106
and an electrical connection layer
110
are formed for example by sputtering, and an electrical connection pad
111
is formed by photolithographic method. The electrical connection is achieved by bonding the electrical connection pad
111
of the completed heater board
100
and a lead
112
of a TAB tape by a bonding device.
In case the electrical connection pad is positioned in a recessed part (through hole) as shown in
FIGS. 11A and 11B
, the pad area has to be made large in order that the bonding is not hindered by the surrounding layers (insulation layer etc.). However, the area of the electrical connection pad cannot be made large enough, because a large number of functional elements are positioned on the substrate of the ink jet recording head and also because the dimension of the recording head is made smaller in recent years. For this reason, there is adopted a method of forming a bump of a conductive material on the through hole, thereby forming the electrical connection pad higher than the surrounding insulation layer. In either of the electrical connecting methods mentioned above, the surface of the electrical connection pad is desirably not concave but provided with a sufficiently large flat area, in order to increase the adhesion strength of bonding. However, if the bump is formed on the pad portion for example by sputtering, the film of the bump follows the stepped surface shape of the through hole whereby the surface of the bump is recessed. On the other hand, in case the bump is formed by electroplating in the through hole, the electroplating has to be conducted after the through hole portion is covered with a conductive film of a high anticorrosive property such as TiW, in order to prevent that aluminum constituting the wiring electrode is dissolved in the electroplating operation. For this reason, the formed conductive film follows the stepped shape of the through hole also in this case, whereby the surface of the bump becomes recessed. Besides, in order to effect such electroplating operation, there has to be provided a current supplying wiring for electroplating, in a part of the wiring electrode or of the conductive film.
Also the surface of the electrical connection pad can be made flat by extending the wiring from the through hole to the end of the substrate as shown in
FIGS. 12A and 12B
, such configuration does not match the aforementioned tendency of compactization of the substrate.
In the recording head of the side shooter type, there can be adopted the TAB connection shown in
FIGS. 12A and 12B
, but such electrical connecting method based on TAB requires an additional gold layer by sputtering or evaporation on the electrical connection layer
110
on the substrate, in comparison with the conventional wire bonding method, thus leading to the following drawbacks of:
1) requiring additional apparatus for gold film formation and patterning;
2) requiring an additional mask for the additional patterning step; and
3) requiring a larger target for a large-sized wafer, with a significantly increased initial investment of the gold for such a target.
SUMMARY OF THE INVENTION
In consideration of the foregoing, an object of the present invention is to provide an ink jet recording head and a producing method therefor, enabling size reduction of the recording head and providing excellent reliability in the connection with the external wiring.
Another object of the present invention is to provide an ink jet recording head and a producing method therefor, based on an electrical connecting method capable of solving the above-mentioned drawbacks 1), 2) and 3) and applicable both to the edge shooter type and the side shooter type, with a high production yield, a high process throughput and a low cost.
The above-mentioned objects can be attained, according to the present invention, by an ink jet recording head provided with a heat-generating resistance layer for generating thermal energy used for ink discharge, and a wiring electrode layer electrically connected to the heat-generating resistance layer, also provided on a substrate with an electrothermal converting element, an insulating protective layer covering the electrothermal converting element, and an external electrical connection portion electrically connected to the electrothermal converting element and to be adhered to an external wiring for applying a voltage to the electrothermal converting element, wherein the external electrical connection portion is formed by a film grown by electroless plating from the wiring electrode layer through a through hole formed in the insulating protective layer. The above-mentioned ink jet recording head further includes the features that an anticavitation Ta layer is formed on the insulating protective layer, avoiding the position of the external electrical connection portion, that a photosensitive resin layer constituting walls of a liquid path is formed on the insulating protective layer, that the external wiring is constituted by a TAB tape, and that the substrate has a protruding portion between the external electrical connection portion and the end of the substrate.
According to the present invention, there is also provided a method for producing an ink jet recording head provided with a heat-generating resistance layer for generating thermal energy used for ink discharge, and a wiring electrode layer electrically connected to the heat-generating resistance layer, also provided on a substrate with an electrothermal converting element, an insulating protective layer covering the electrothermal converting element, and an exte
Kitani Masashi
Koyama Shuji
Kubota Masahiko
Mori Toshihiro
Ozaki Teruo
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Meier Stephen D.
Mouttet Blaise
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