JPH0999561A - Manufacture of a charge board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a charge plate by a usual method. SOLUTION: In the production of a charge plate, at first, a ceramic charge substrate having an end surface 12, an upper surface 14 and a rear surface 18 is prepared. Subsequently, conductive patterns are formed to the end surfaces of the ceramic substrate to form charge surfaces 16. Subsequently, conductive routes 22 are formed to the upper surface of the non-conductive charge substrate from the charge surfaces and charge drivers are provided on the upper surface of the ceramic substrate. Next, conductive patterns 24 are formed on the upper surface to provide the electric connection from the charge drivers to the charge plates. Finally, the upper surface having the patterns formed thereon is covered with a dielectric material.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to the field of binary continuous ink jet printers, and more particularly to a method of making a charge plate for an ink jet printer.

[0002]

2. Description of the Related Art In a continuous ink jet printer,
Conductive ink is supplied under pressure to the manifold region, from which the ink is distributed to a plurality of orifices arranged in a linear array. The ink is expelled as a filament from the orifice and breaks the filament to form a droplet stream. The individual droplets in the stream are selectively charged to form substantially two levels in the filament break region and the charged droplets are deflected from their normal trajectory. Deflected drops or undeflected drops can be captured and reused, while other drops adhere to the print medium.

In binary continuous ink jets, the droplets are charged by a charge plate, which has a plurality of charge electrodes located along its thin end face and a corresponding number of connecting leads located along the top face. Have.
The end surface of the charge plate provided with the charge electrode is located in the vicinity of the dividing point of the inkjet filament, and a current is applied to the lead to charge the droplet when the droplet is separated from the filament.

US Pat. No. 4,560,991 discloses one method of making a charge plate. In this patent, a charge plate is manufactured by electrically depositing charge electrodes and leads on a thin sheet of etchable material (eg, copper foil) to form a so-called "coupon". The coupon is bent by a jig at an angle of about 90 °. The leads are then adhered to a dielectric material (eg aluminum oxide) and the etchable substrate is then removed by chemical etching. A method of manufacturing such a charge plate is called a "lead transfer method", and it is necessary to form an electrode on an etchable substrate.

Another "lead transfer" type charge plate manufacturing method is described in US patent application Ser. No. 08 / 229,114, which also forms electrodes on an etchable substrate. There is a need. The electroformed coupon is then bent at an angle of about 90 ° and adhered to a dielectric material (eg, aluminum oxide), then the etchable substrate is removed by chemical etching.

[0006]

However, conventional charge plate manufacturing techniques have several drawbacks. For example, the manufacturing method is complicated because the number of manufacturing steps required to manufacture a usable charge plate is relatively large, and the manufacturing method is costly in connection with the large number of manufacturing steps. Also, the lead transfer method lacks accuracy. The reason is,
This is because the leads move slightly when the substrate is removed by etching. As the spatial distance between the jets decreases, the problems associated with connecting to external circuitry increase. For example, standard electronic connection technology can provide about 20 electrical connections per linear inch of connector. Oriental technology can make about 100 reliable connections per inch (about 25.4 mm). 1 for current inkjet printers
Hundreds of charge leads per inch (about 25.4 mm) are desired. Currently, this is done by "fanning out" the leads from the leading edge or end face of the charge plate to a larger connection area in the portion of the charge plate (away from the inkjet area).
For example, for a 1 inch wide print head with 300 jets per inch, at least 3 inches behind the charge plate.
It is necessary to provide a connector space of 6.2 mm). This causes the charge plate and printhead to be much larger than the desired small size. Another problem with current charge plate manufacturing technology is condensation that occurs on the charge plate during printhead operation. Since the charge plate operates in a 100% relative humidity environment, water tends to condense on the charge plate. To solve this problem, a heater as disclosed in U.S. Pat. No. 4,622,562 is used to maintain the charge plate at a temperature just above ambient temperature. In the current state of the art, such as disclosed in U.S. Pat. No. 4,560,991, the trap heater is an additional element located below the charge plate within the trap. Incorporating this additional element into the printhead adds to the cost and complexity of the printhead. Furthermore, since nickel is used as the electroformed electrode, during the operation of the print head in inkjet printing,
There is a strong possibility that the electroformed electrode will be lost electrochemically (due to corrosion). This tendency is especially pronounced in the bottom portion of the lead (particularly the portion furthest from the 90 ° bend) which tends to accumulate ink during inkjet printing.

Therefore, there is a need for an improved method of making a charge plate that overcomes the problems of the prior art.

Accordingly, it is an object of the present invention to provide a charge plate having a driver chip which reduces the size of the interconnect. Another object of the invention is to provide a charge plate that can be manufactured by conventional methods such as patterning with thick and thin films. Yet another object of the present invention is to provide a method of manufacturing a charge plate that overcomes the drawbacks of similar prior art manufacturing methods by separately patterning the top and end faces of the charge plate. Another object of the invention is to use thick film circuit technology to form connections for standard connectors on the trailing edge of the charge plate to provide the circuitry required for electrical isolation of the driver chip. That is. Another object of the present invention is to integrate a resistive charge plate heater with the bottom surface of the charge plate. Yet another object of the present invention is to further increase the flexibility in manufacturing.

[0009]

The above-mentioned requirements can be met by providing an integrated manufacturing method of a charge plate and an electronic driver according to the present invention.
In this method, the charge plate can be manufactured by conventional methods (eg, patterning thin and thick films), and the driver electronics can be integrated with the charge plate by charge plate manufacturing techniques. Previous attempts at using such conventional methods have failed for several reasons. First, there was no electronic driver chip available that could withstand the high pressures required for inkjet printing. Second, it was not possible to use the method of manufacturing the circuit required for the charge plate with the required spatial resolution. Finally, it was not possible to use the technique necessary to form the charge leads extending across the 90 ° angle, as it was not possible to create a pattern on the end face. The lead transfer method can be used to produce chipped charge plates, but this method has limitations.

In the present invention, in the manufacturing method, the pattern formation on the upper surface and the pattern formation on the end surface are separately performed,
By allowing more flexibility in manufacturing, the drawbacks mentioned above can be overcome. A clever combination of new technologies allows the fabrication of circuitry on the back side of the plate so that the electronic chip driving the charge leads can be mounted on the charge plate. This allows input to the charge plate via one electronic "bus" (bus) so that many charge leads can be driven with few electrical connections to external circuitry. The new technology also allows the integration of a heater for the charge plate on the underside of the charge plate. Furthermore, the loss of material available for manufacturing with this new technology due to corrosion is small.

According to one aspect of the present invention, in a method of manufacturing a charge plate for an ink jet printer, the charge plate can be manufactured using a conventional method. First, a ceramic charge plate substrate having an end surface, an upper surface and a lower surface is prepared. A conductive pattern is then created (by conventional printing techniques) on the edge of the substrate to form the charge surface. By creating a pattern on the top surface of the charge plate substrate, a conductive path from the charge surface to the top surface of the ceramic charge plate substrate is completed and a wrap
nd) Form a circuit. A pattern is formed on a circuit portion on the upper surface where the electronic driver chip is present. In this case, the pattern is composed of a number of small rectangular conductive areas (called "pads") surrounding the driver chip. The pads provide a point for making electrical connections from the charge plate to the driver chips using any suitable known technique, such as the known techniques described above, for example, gold wire ball bonding, flip chip attachment, micro attachment. Ball grid array mounting, including ball grid array mounting, and common wire bonding techniques such as tape automated bonding. The connection from the pad to the charge surface and the rear surface of the chip is performed in a pattern forming process on the upper surface. This patterning can be accomplished by any suitable method, such as the thick film method. A pattern can be created on the top surface of the charge plate to electrically connect the top surface to the end face for charging and deflection of the droplets.
When the conductive path to the top surface of the ceramic charge plate substrate (from the charge surface) is complete, the next step (the second set of steps) is performed to form an area on the back surface of the charge plate for the bilayer circuit. . For example, it is necessary to make an electrical ground below the electrical trace (sweep line) that sends the power and logic signals to the driver chip. The charge plate is provided with holes so that thick film circuit technology can be used to form a resistive charge plate heater on the lower surface of the charge plate.

[0012]

DETAILED DESCRIPTION OF THE INVENTION Referring to the drawings, FIG. 1 shows a charge plate substrate 10 that can be assembled as a charge plate assembly. Preferably, the charge plate substrate 10 is constructed of ceramic and made of 96% aluminum oxide having a coefficient of thermal expansion of 8.2 x ^10-6 / ° C. The end surface 12 of the base body is substantially perpendicular to the upper surface 14.
Preferably, the end surface 12 is flat so as to provide optimal charge of the droplets.

Referring to FIG. 2, first, the end face 12 of the ceramic substrate 10 of FIG. 1 is patterned to form a charge surface or charge surface 16. In the preferred embodiment of the present invention, the end face 12 has a height of about 0.015.
Inches (about 0.38 mm). End face 12 is lower face 18
Is also substantially vertical. A chamfer 20 spaces the end surface 12 and the lower surface 18 through a surface at an angle of about 45 ° and provides a path for the deflected drops towards the trap.

In a preferred embodiment of the invention,
During patterning of the edges, a small amount of ink can spread over the top surface to improve the electrical connection. The charging surface 16 is formed by passing thick film conductive ink through openings in the screen (silk screen printing) and / or thin metal foil (stencil printing) using standard methods in thick film processing technology. ,It is formed. Silk-screen printing has the advantage of allowing the formation of unusual patterns, and stencil printing has improved printing lines and without the use of wire mesh, which can cause problems when extruding ink at high resolution. It has the advantage of providing line space. A gold thick film paste such as the commercially available DuPont 6715 (trade number) gold thick film paste is preferred over nickel. The reason is that gold is more chemically inert than nickel.

Referring to FIG. 3, following the formation of the charge surface 16, the conductive path from the charge surface to the top surface 14 is completed to form a wrap around conductive path 22. In a preferred embodiment of the invention, the conductive pathways can extend across the end face during wrap formation. This causes an overlap of the end face and the wrap, ensuring a good electrical connection around the end face.

The wrap 22 is formed by a thick film paste or printing technique such as printing, drying and firing. Therefore, the present invention employs a thick film process to obtain the electrical connection between the top surface 14 and the charging surface 16. The electrical connection from the top surface 14 to the end surface 12 is made using an electrical connection wrap method that connects the charge surface 16 of the end surface 12 to the top surface wrap 22. this is,
Done by direct metal-to-metal diffusion during the firing step (after the substrate printing and drying steps, but before the top surface patterning step).

In FIG. 4, to form the charge plate,
Shown is a top surface pattern 24 of a substrate created after printing, drying, firing and metal-to-metal diffusion. The top surface pattern of the substrate can be made using any material, such as the Fodel photoimageable material as described in "Proceedings of the 1993 International Symposium on Microelectronics". Fodel's technology is an extension of the thick film paste technology, with the inorganic components, metal powders, glass powders, metal oxides and refractory powders used to make thick film dielectrics and conductors, and printed wiring. It was developed by combining organic components, polymers, photoinitiators, monomers and stabilizers used to make photoresist films in the board field. This combination produces a photoimageable ceramic material that combines the well-known reliability of ceramic materials with the ease of processing in conventional equipment using mild aqueous chemistry currently used in the printed wiring board field. Obtainable.

The Vodel method, like the component materials, is a combination of the conventional thick film method and the printed wiring board method. As is known to those skilled in the art, conventional thick or thin film methods and conventional printed wiring board methods can be used separately or, where appropriate, for patterning the charge plates of the present invention. It can also be used in combination. The Vodel method is described by way of example only and is not a limitation of the present invention.

In the Foldel method, a photoactive paste, such as the commercially available Foldel paste, is first applied to the desired substrate by blank screen printing. The paste is flattened at room temperature and then dried, for example at a temperature of 80 ° C. After drying, the paste is exposed to UV light (having a typical maximum wavelength of about 360 nm) through a suitable photomask to form a latent image. Following exposure, the latent image on the material is developed using, for example, a 1% aqueous Na ₂ CO ₃ solution, eg, in a transportable spray processor. The developed paste is then fired by the normal thick film method.

After forming the upper surface pattern shown in FIG. 4, the upper surface is covered with a material having a high breakdown voltage and no pinhole.
The preferred material is a dielectric material that sinters against the patterned top surface to form a good dielectric coating. Dielectric coating is available on the market DuPont 5
It can be any suitable dielectric, such as 704 (product number) dielectric.

As is known to those skilled in the art, thick film technology is a method of making patterned circuits used in the electronics industry. A pattern is created on the substrate by the silk screen method, which is then dried and fired. The process begins with a suitable substrate capable of withstanding the temperatures required for ink sintering or firing, such as a substrate made of 96% aluminum oxide. Then, a thick film ink is applied on the substrate by a silk screen method. Of course, different inks can be used for different applications. For example, certain conductive inks can be used to form conductive gold paths. A conductive ink containing palladium and gold can be used as a soldering point. Resistive inks can be used to form resistive elements and resistive heaters for electronic circuits. Non-conductive or dielectric inks can be printed to form a protective coating on previously formed circuitry or on a barrier between two circuit layers. These inks contain three main components: a binder component (referred to as the frit), a print vehicle and a functional component. After the ink is applied to the substrate by the silk screen method, the substrate is placed in a drying oven and heated at a temperature of, for example, about 150 ° C. to evaporate all the solvents.
In the next step, the printed and dried substrate is fired. The substrate is subjected to a specific temperature treatment to heat the substrate to a temperature (for example, 500 ° C.) at which all organic substances are burned out, and the temperature is maintained. The substrate is then heated to a temperature at which firing actually occurs (eg, 850 ° C). At a temperature of 850 ° C., the functional component sinters into a layer of functional material. Similarly, the frit sinters and partially diffuses into the substrate, providing a means of adhering the functional component to the substrate. Finally, reduce the temperature. Additional layers may be placed on top and similar treatments applied.

Referring to FIG. 5, the ceramic substrate layer 26
The end face print layer 2 such as gold thick film
Use 8 to print. Then, the wrap layer 30 is applied. The wrap layer can be any suitable material such as a thick gold film. The thin line circuit layer 32 is formed using the Foder method. This layer provides a connection path between the charge driver chip 34 and the charge electrode on the end print layer 28. Next, a ground plane circuit 36 is provided to form an electrical ground path between the connector 38 and the driver chip 34. These two separate layers are then coated with a dielectric layer 40 and the layer 40 is sintered on top of the pattern surface to create a good electrically insulating coating. The control circuit layer 42 provides a path between the connector 38 and the driver chip 34 for power signals, control signals and data signals.

FIG. 6 is a block diagram showing the functional relationships between the various layers on the charge plate and the connection to supporting electronics remote from the charge plate. In FIG. 6, the power line 44, the control line 46, and the data line 48 are
The power source 50, the print controller 52, and the print data generator 54 are connected to each other via the connector 38.

Referring to FIG. 5, a second dielectric coating 56 is provided to protect the control circuitry and provide a second coating on the thin line circuitry 32. It is important that the dielectric coating has no voids in the area of thin line circuits. In the presence of voids, the conductive ink used in ink jet printing creates a conductive path between two adjacent traces, creating a short circuit and damaging the device.

Referring to FIGS. 5 and 6, the driver chip 3
4 is a silicon device that accepts logic level data in series, then latches these signals and outputs that data in parallel at a higher voltage potential. Logic levels are typically 0 and 12 volts (DC). The output voltage can range from 60 to 180 volts (DC). The input channels of driver chip 34 are connected to ground plane circuit 36 and control circuit 42 by any suitable means such as gold wire ball bonding. The output channel of the driver chip 34 is connected to the thin line circuit 32 by any suitable means such as gold wire ball bonding. Epoxy or other suitable material is used to cover the chip and wire bonds to protect the chip and wire bonds from the ambient environment.

Referring to FIGS. 5 and 6, the connector 38 is attached by standard surface mount soldering techniques. The solderable metal layer provides pads for soldering the connector, and the small holes formed in the back surface form conductive vias from the top surface to the bottom surface. This provides an electrical path from the top surface to the bottom surface of the charge plate and the heater for the resistive charge plate. Resistance layer 58 and heater circuit layer 60
The resistive charge plate heater constructed as follows is integrally formed on the lower surface using thick film technology. The heater circuit layer 60 is applied using a solderable ink and provides a conductive path between the bias and the heater layer (resistive layer) 58. The resistive ink is then used to form the heater layer 5
Give 8. The shape and thickness of this layer determine the desired resistance.

The top patterned thin line circuit layer 32 provides a conductive path between the wrap pattern and the output of the driver chip. This layer has pads used for wire bonding operations. Ground plane circuit layer 36 provides a conductive path for ground signals between the driver chip and the surface mount connector. The patterned top surface is covered with a dielectric layer 40, which sinters with the patterned top surface to form a good dielectric coating.
The control circuit layer 42 provides a conductive path between the connector and the driver chip prior to applying the second layer. Charge driver elements, shown as layer 34 and surface mount connector 38, provide the connection between the controller and the data source.
The resistive charge plate heater including the resistance layer 58 and the heater circuit layer 60 is integrally formed on the lower surface of the charge plate indicated by reference numeral 62 in FIG.

In accordance with the present invention, the separate patterning of the top and end faces allows the use of different materials.
Greater flexibility in manufacturing. As known to those skilled in the art, changing the material of the charging surface also changes the electrical properties. In the present invention, different materials can be used to obtain the desired overall electrical and electrochemical properties.

[0029]

INDUSTRIAL APPLICABILITY AND EFFECTS The present invention is useful in the field of ink jet printing and provides the advantage that the charging surface can be directly formed. This makes it easier to manufacture the charge plate. After forming the wrap, etchable thick film method, traditional thin film method,
Hydridization method for thick and thin films,
Also, various techniques such as photoimageable thick film techniques can be used to create the top surface patterning of the charge plate. Providing a driver chip has the advantage of reducing the size of the interconnect.

Although the present invention has been described with reference to the preferred embodiments of the invention, it goes without saying that various modifications and variations can be made without departing from the gist of the present invention.

[Brief description of drawings]

FIG. 1 is a perspective view of a charge plate base.

FIG. 2 is a perspective view of a ceramic substrate having an end surface patterned according to the present invention.

3 is a perspective view showing wrap conductive paths associated with the patterned end face of FIG. 2. FIG.

FIG. 4 is a perspective view showing a state in which a pattern is formed on the upper surface.

FIG. 5 is an exploded perspective view of various layers of the charge plate according to the present invention.

FIG. 6 is a block diagram showing power, ground, control and data signal interfaces to a charge plate.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 charge plate base 12 end surface 14 upper surface 16 charge surface 18 lower surface 20 chamfer 22 lap 24 upper surface pattern 34 charge driver

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Brian G. Morris 45419-1269, Dayton, Monterey Avenue, Ohio, USA 116 (72) Inventor Peter N Tank 45459-5147, Centerville, Ohio, USA Stanley Mill Drive 7860

Claims (10)

[Claims] 1. A method of manufacturing a charge plate for an ink jet print head, comprising: (a) preparing a ceramic charge plate substrate having an end face, an upper surface and a lower surface; and (b) an end face of the ceramic charge plate substrate. A predetermined conductive pattern is formed on the end surface of the ceramic charge plate substrate so as to form a charge surface on the ceramic charge plate substrate; (c) From the charge surface to the upper surface of the ceramic charge plate substrate to form the charge plate. (D) a step of providing a charge driver on the upper surface of the charge plate; and (e) an upper surface of the charge plate to enable electrical connection from the charge driver to the charge plate. And (e) coating the conductive pattern formed upper surface with a dielectric material. A method of manufacturing a charge plate, comprising: 2. The method of manufacturing a charge plate according to claim 1, further comprising the step of completing a conductive path from the upper surface to the lower surface via a conductive bias. 3. The method of manufacturing a charge plate according to claim 1, further comprising the step of forming a pattern on the lower surface to form a resistive trap heater. 4. The method of claim 1 including the step of providing a connector for control signals. 5. The method of claim 4 including the step of providing a conductive path from the charge driver to the connector. 6. The method of claim 1 including the step of providing an electrical connection from the charge plate to the charge driver by wire ball bonding made of gold. 7. The ceramic charge plate substrate is 96%
2. The method of manufacturing a charge plate according to claim 1, wherein the aluminum oxide is included. 8. The method of manufacturing a charge plate of claim 1 including the step of forming electrodes on an etchable substrate associated with the ceramic charge plate substrate. 9. The method of manufacturing a charge plate according to claim 1, further comprising the step of providing a chamfer for separating the end surface and the lower surface. 10. The method of manufacturing a charge plate according to claim 9, wherein the chamfered portion is formed of a non-conductive surface.