Metal working – Method of mechanical manufacture – Fluid pattern dispersing device making – e.g. – ink jet
Reexamination Certificate
2001-09-27
2003-11-25
Tugbang, A. Dexter (Department: 3729)
Metal working
Method of mechanical manufacture
Fluid pattern dispersing device making, e.g., ink jet
C029S025350, C029SDIG001, C427S100000, C427S098300, C427S304000, C427S555000, C427S556000, C347S068000, C347S071000, C219S121690, C219S121200
Reexamination Certificate
active
06651335
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a processing method of resistless, maskless electroless, 3-dimensional plating of an ink-jet print head, and a production method thereof.
Electroless plating is depositing a continuous film of metal by controlling reduction and oxidation reaction which occurs between metallic salts and reducing agents in a plating bath. By electroless plating, a film of metal, alloy, compound, or composite can be formed onto an electrically non-conductive surface.
Eelectroless plating is capable of conducting metal deposition without electric power. But, before electroless plating, plating catalyst must be absorbed onto a substrate to initiate metal deposition. Otherwise, the electroless plating cannot start.
After starting, already deposited metal itself can work as a self catalyst for further plating.
An electroless plating can coat a metallic layer onto a non-conductive substrate which has previously been subjected to a suitable pre-processing, such as washing, etching and catalyst absorbing, and an uniform metallic film can be deposited on any substrates whatever shape they may have. Usual electroless plating metal is nickel, and can be deposited onto a various kind of substrates, including metal, plastic, ceramic, and other non-conductors. Because electroless plating is capable of depositing a metal layer onto any surface, regardless of their conductivity and even inside wall of a small hole, it is widely used in a electronic industry, for example, in a circuit patterning of a printed wiring board, contact point of a connector, a semiconductor device, a package of a ceramic-metal-integrated circuit, a connector shell made of aluminum, a lead frame, formation of an electrode of an ink-jet print head, etc.
In particular, regarding an ink-jet print head, it can be cited, a piezo type ink-jet print head which jets inks from an ink chamber by a piezo ceramic actuator, attached to an ink chamber, through the application of an electric signal to an electrode of a piezo ceramic. Further, there is another type of piezo ink-jet print head which is called share-mode print head.
The share mode print head have many minute ink channels inside a piezoelectric ceramic itself and metal is selectively deposited onto a partition wall between the channels as an electrode.
By applying an electric signal to electrodes between a wall, share-mode deformation of the partition wall occurs and compress the ink inside the channel and ejects a droplet from the channel.
Ink-jet print head have to eject a droplet from each channel independently. But electroless plating deposits a metal film onto a whole surface evenly, so either masking before plating or removing unnecessary metals after plating, is inevitable, to separate electrode and wiring, in each channel.
In a print head, we must build both electrode pattern to actuate piezo ceramic channel and wiring pattern to connect between electrode and control circuit, simultaneously by electroless plating. The Patterning technology is very important for an ink jet print head.
Usual patterning technology is as follows, coat of a photoresist is conducted onto a substrate and UV is irradiated through an appropriate mask. After developing a pattern image, metal is deposited, onto a portion which is not masked.
As for ink jet print head, head size is very small and has many minute ink channels, and also, 3-dimensional wiring is required. Recently, channel width is approaching less than 50 &mgr;m, and channel numbers are increasing over 500, and also, an electrode pattern must be built inside and a wiring pattern must be built outside of the channel, simultaneously by electroless plating. The usual patterning method using photoresist and mask is not adequate for ink jet print head due to its small size and a complex 3-dimensional structure.
Laser pattering is most suitable for ink jet print head. This is a resistless, maskless, 3-dimensional pattering.
Laser pattering technology of print head is described in the publications of Japanese Tokkaihei H8-300667 and H9-10976 and WO 00/29217. There is cited a method in which a pattering of an electrode and wiring is accomplished by evaporating a metal deposited in an unnecessary portion of a print head, by selective application of a high-energy laser beam.
As described in the patents, in the conventional technology, separation of an electrode and wiring is accomplished through evaporation of unnecessary metal film by a laser beam, but nickel is a very hard metal and has high melting temperature, therefore, high energy density laser beam is required, thus thermal shock and thermal distortion occur in the piezoelectric ceramic, the piezo-electrical properties is very sensitive to elevated temperature, and its performance is easily deteriorated by heat and also there is a possibility of damage in a print head.
Further, the high energy laser beam, requires a high-output and high-priced apparatus. Moreover, there is a possibility that the metallic film evaporated by high energy laser beam, have a tendency to redeposit around the surroundings, and may produce defects due to redeposited debris, in the final electrode and wiring, resulting in a short circuit.
SUMMARY OF THE INVENTION
This invention was performed in view of the above-mentioned actual situation, and its first object is to provide a processing method of a resistless, maskless and 3-dimensional electroless plating which is capable of forming a plating pattern having no defect at low cost without deteriorating both piezo-electrical and physical properties and further, without producing any damage in a head.
Its second object is to provide a new laser pattering method which evaporates plating catalyst, instead of plated metal. The former requires one-tenth energy of the latter, so undesirable heat shock, and debris formation can be minimized.
It can provide an ink-jet print head which has an electrode and wiring pattern, having no defect, at low cost without deteriorating both piezoelectric and physical properties and further, without producing any contamination due to debris in a head, and the method of manufacturing it.
Its third object is to provide a new UV pattering method which oxidize plating catalyst, instead of evaporation.
The former requires much lower energy, no undesirable heat shock, and no debris formation can be expected. It can provide an ink-jet print head which has an electrode and wiring pattern, having no defect, at low cost without deteriorating both piezoelectric and physical properties and further, without producing any damage in a head, and the method of manufacturing it.
For the purpose of solving the above-mentioned problems and accomplishing the objects, this invention was made to have any one of methods described in the following.
(Method 1): A processing method of electroless plating characterized in that a catalytic material for electroless plating is absorbed onto a surface of a piezo-electric ceramic, then a laser beam is selectively applied to this ceramic, finally, processing of electroless plating is applied to this ceramic, a metal layer is formed on the portion to which the laser beam has not been irradiated and a metal layer is not formed on the portion to which the laser beam has been irradiated.
To separate the electrode and wiring between channels, evaporating a catalyst, instead of metal, much lower laser power is needed, so much lower thermal damage and much lower debris can be expected. Because, the amount of catalytic material contained is only &mgr;g order palladium, but the amount of electrode material contained is mg order nickel.
According to the method 1, prior to electroless plating, the substrate with catalyst has already been selectively irradiated by laser beam, a plating pattern having no defect can be formed at a low cost without deteriorating the piezoelectric and physical properties and further, without producing any damage and contamination in a print head.
(Method 2): A processing method of electroless plating characterized in that a catalytic material is absorbed onto
Akanabe Yuichi
Kikugawa Shozo
Okuno Tetsuo
Yamada Minoru
Frishauf Holtz Goodman & Chick P.C.
Konica Corporation
Tugbang A. Dexter
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