JPS6347775A - Permanent master with enduring latent image to be used in electrostatic transfer - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention generally relates to a method for high resolution electrostatic transfer of high density images to non-porous, non-absorbent, conductive image-receiving surfaces. In particular, the present invention relates to a method of forming a persistent latent image onto a permanent master using a photosensitive material such as a liquid photoresist or a dry film photoresist, and a method of transferring from the master. The permanent master of the present invention can be used repeatedly for the formation of high resolution and high density images on more image-receiving surfaces of printed circuit boards.

The formation of conductive wiring patterns on insulating substrates using dry film resists by photoimaging and other methods to produce printed circuit boards typically uses a five-step process. using tenting techniques or hole occlusion (ho
The five different steps are: laminating or coating a photosensitive dry film resist onto at least one conductive surface of an insulating substrate; The process involves releasing the wiring pattern on the dry film resist by using a photo tool, exposing the dry film resist to actinic radiation through the transparent area of the photo tool, and removing the unexposed part of the negative dry film resist. developing the circuit board; etching the conductive substrate from the circuit board in all non-imaging areas not under the desired conductive trace pattern still imaged in the dry film resist; From the unetched portion of the conductive substrate to the desired wiring No. 9
stripping or removing the dry film resist covering the turns. This five step method must be repeated to produce each circuit board.

During the exposure step of the standard dry film method, in order to produce straight sidewalls in the dry film resist, which is a result of the pattern of cross-linking of the polymers in the dry film,
Sufficient radiation exposure levels and exposure times are desired. These straight sidewalls must be perpendicular to the conductor surface. However, in practice, for example, in standard negative dry film photoresist printing and etching processes, either underexposure can occur, producing sidewall edges that undercut the desired resist pattern, or overexposure can occur. , the surface of the conductor increases, creating sidewall edges in the dry film photoresist and contributing to the width and legs of the dry film photoresist at the base of the resist.

These conditions cause the width of the final conductive pattern to vary from the desired width, exceeding the planned tolerances or ranges of line widths within the conductor surface.

The development step in this method ideally dissolves and removes the ungaged, and therefore uncross-bonded, areas of the negative dry film resist so that the width is equal to the pattern on the phototool and the conductor surface. P on the conductor surface
dry film photoresist, but in practice, underdevelopment or overdevelopment of the dry film photoresist occurs.

Underdevelopment results in build-up of resist residue within the sidewall zone or developed channel, which slopes toward the adjacent sidewalls, resulting in smaller interline spacing than the desired adjacent line spacing.

When overdevelopment occurs, the unexposed film resist edge is undercut and the spacing between adjacent lines is greater than desired. Additionally, there may be some rounding at the top of the resist surface sidewall edges.

The inability of the photo tool to accurately reproduce the entire thickness of the dry film resist affects the good line resolution and reproduction characteristics of the reproduced circuit pattern.

As circuit boards have become more complex and stacking of multiple boards has become common, a desire has arisen for higher density and better resolution circuit patterns. Resolution has been viewed as the ability to reliably reproduce the smallest line and adjacent line spacing that can be reliably conveyed by the five-step process.

The thinnest or smallest line that can be reproduced by development and the narrowness of the gap or spacing between adjacent lines of a circuit notation are approximately 1,010,7874 s 5 1 mil) line and spacing dimensions, or approximately 6.3 wire pairs per 1 u. Development led to a demanding printed circuit board industry with good line resolution and reproduction standards. These standards are used to define the desired density of circuit boards.

Attempts to apply the principles of electrography to the transfer of developed electrostatic latent images at high resolution and high density images from the electrostatically imaged surface of a photoconductor to an image receiving surface have been made difficult. I encountered it.

A major source of this difficulty arises from the fact that circuit boards are comprised of non-porous or non-absorbent substrates such as metals such as copper or plastics such as polyester films sold under the trade name Mylar. This non-porous, non-absorbing image-receiving surface prevents the transferred image from being completely distorted or collapsed, especially when using liquid toner.
d)

The problem of image transfer to an absorbent image-receiving surface, such as paper, was solved by xerographic technology by transferring the image formed by toner particles through a gap. The gap was an air gap or a combined air-liquid gap. However, attempts to transfer this gap transfer technique to non-porous substrates have resulted in image "squish" and the gap spacing and It turns out that the voltage has to be carefully controlled.

If the voltage and gap spacing, ie, the distance between the photoconductor or electrostatically imageable surface and the conductive image receiving surface, are not carefully controlled, electrical arcing will occur between the gaps.

This can cause pinholes in the transferred toner image by permanently damaging the electrostatically imageable surface.

This is of particular significance in printing and etching applications used in the manufacture of printed circuit boards.

Non-porous image-receiving substrates require that both the photoconductor or electrostatically imageable surface and the conductive image-receiving surface remain stationary at the point of transfer of the toner image in order to obtain a high-resolution transferred image. Understood. Additional problems arise when electrostatically transferring the developed latent image to a non-absorbing substrate such as copper. Because the metal or copper surface that forms the conductive image-receiving surface as well as the electrostatically imageable surface is not planar, electrostatic The spacing between the imageable surface and the conductive image receiving surface must be sufficient.

These problems are solved by the method of the present invention by providing a method for producing persistent latent images and permanent masters using photosensitive materials such as liquid or dry film renosts. A persistent latent image on a photosensitive material is produced by transferring an electrophotographically developed electrostatic latent image from the electrostatic imaging surface of a permanent master to a large number of printed circuit boards having the desired conductivity and nine turns. The image receiving surface is preferably, but not exclusively, a conductive, non-absorbent, non-porous image receiving surface of the mold used in manufacturing. A permanent master is one in which all non-crosslinked areas of the sensitive material have not been dissolved away to obtain the dielectric contrast necessary to effect image transfer.

One object of the present invention is to provide a method for achieving contactless, high resolution electrostatic transfer of a developed high density electrostatic latent image directly from a permanent master to a non-porous, non-absorbing substrate.

Another object of the present invention is to obtain a high density electrostatic latent image on an electrostatically imageable surface by the use of a dry film lenost that serves as a permanent and reusable master.

Another object of the present invention is to be able to utilize electrostatic transfer methods for permanent masters as electrostatically imageable surfaces.

Yet another object of the present invention is to use a manufacturing press for making multiple copies of a desired resist pattern on a conductive substrate to produce conductive circuit trace patterns on printed circuit boards. An object of the present invention is to provide a permanent master and a method for manufacturing the permanent master.

One feature of the present invention is that the photosensitive material of the permanent master is charged after the entire latent image is formed and that the reusable permanent master has lines and spacing of about 0.02794 inches (i, 1 mil), i.e., 1 mil. It has the ability to resolve equal individual objects of 18 line pairs per m.

Another feature of the invention is that the conductive backing material or substrate supporting the permanent master is electrically grounded during electrostatic transfer and that the conductive image receiving surface is electrically isolated from ground.

Yet another feature of the invention is the use of conductivity differences in dry film photoresist between imaged and non-imaged areas on a master to form a persistent electrostatic latent image.

Another feature of the invention is that the persistent latent image is electrostatically charged, developed and transferred through a liquid filled gap to a conductive image receiving surface.

Another feature of the invention is that the gap distance or spacing between the electrostatically imageable surface and the conductive image receiving surface is about 1
0762 (about 3 mils) to about (L508. (about 20 mils)
and that said distance is maintained by the use of two spacer means between the surfaces that are electrically isolated from ground.

Yet another feature of the present invention for permanent masters used as electrostatically imageable surfaces is that the electrostatic latent image on the electrostatically imageable surface is persistent and unique for each circuit board code. It is reusable as a master for producing large quantities of printed circuit boards without the need to expose dry film or liquid photoresist.

Yet another feature of the invention is that only the top surface of the dry film photoresist image on the master is used to form a developed image prior to transfer to a conductive image receiving surface.

Yet another feature of the invention is that transfer of the developed electrostatic image to the conductive image receiving surface is accomplished by direct application of a voltage to the conductive image receiving surface rather than by corona charging.

One advantage of the method of the present invention is that high resolution transfer of toner particles forming a developed latent image onto a conductive image receiving surface is obtained without image distortion.

Another advantage of the present invention is that there is no damage or scratching of the electrostatically imageable surface, the permanent master, during the transfer process so that the surface can be continuously reused.

Yet another advantage of the present invention is that high resolution transfer is obtained because there is no contact between the developed toner particles on the electrostatic imaging surface, the permanent master, and the conductive image receiving surface.

Yet another advantage of the present invention is that the power required to perform electrostatic transfer is reduced due to the use of directly applied voltage rather than corona charging which causes air ionization.

Yet another advantage of the present invention is that the repeated exposure and development steps required for dry film or liquid photoresist for each circuit board are eliminated, resulting in a faster and less expensive method of manufacturing printed circuit boards. That's true.

These and other objects, features, and advantages of the use of a permanent master and the use of electrically It is obtained by a method of producing a toner image on an isolated non-absorbing conductive surface. The electrostatically imageable surface is first charged to develop the charged toner particles into the latent image areas on the photosensitive material of the master and transfer to the conductive image-receiving surface.

Objects, features, and advantages of the present invention will become apparent from the following detailed description of the invention, particularly when considered in conjunction with the accompanying drawings.

FIG. 1 illustrates a standard five step process conventionally used in the manufacture of printed circuit boards. Each single circuit board manufactured requires the application by pressure and heat of a dry film to a conductive substrate, typically copper, which is laminated to a non-conductive substrate such as fiberglass epoxy. Apply a mask onto the dry film so that the desired 74 turns can be generated by selective radiation from a light source or other actinic radiation source. Development is accomplished by removing the uncrosslinked dry film, leaving only the crosslinked dry film with the desired pattern. The conductive copper substrate is removed from between the crosslinked dry film regions by etching with an acid etchant. Finally, the dry film is peeled away from the remaining conductive steel substrate to fully expose the desired circuitry. This method is commonly known as the printing and etching method.

However, in the method of the present invention, a permanent master is fabricated by the use of a photosensitive material or coating, such as a dry film or liquid photorenost on a conductive substrate. No dry film or liquid photoresist is then used to form the desired conductive pattern from the permanent master onto the product circuit board.

A permanent master is used as an electrostatically imageable surface as shown in FIG.

The conductive backing has a photosensitive material, such as a dry film or liquid photoresist, applied to at least one side thereof. The resistivity of this photosensitive material changes due to crosslinking of polymers in the material upon exposure to actinic radiation. "Write the desired number or turn by irradiating actinic rays through a mask or by using a digital laser pen."
A permanent image is formed on the photosensitive material. Both methods create electrostatic contrast, or a difference in resistivity between imaged and non-imaged areas on the photosensitive material. The electrostatically imageable surface is isolated from ground and charged with a corona charging device to form a charged latent image.

The electrostatically imageable surface is then made of at least a portion of a non-polar insulating solvent that acts as a liquid carrier for toner particles that are charged oppositely to that of the electrostatically imageable surface. Develop by applying a liquid by surface adsorption. This application can be done by flooding or dipping or spraying the electrostatically imageable surface. Charged toner particles are directed to the latent image areas of the electrostatically imageable surface to develop the latent image.

When so developed, an image is formed on the electrostatically imageable surface that follows the pattern of the persistent latent image on the permanent master. The image thus developed is ready to be transferred to an electrically isolated conductive image-receiving surface to produce a circuit board with the desired conductive wiring pattern.

A conductive image-receiving surface is first coated with a liquid consisting at least in part of a non-polar insulating solvent.

This solvent is the same or equivalent to the solvent applied to the electrostatically imageable surface and can be applied by a sponzo, squeegee, rubber roller or other means capable of applying a continuous film.

The solvent preferably has a high resistivity and a low viscosity to allow the charged toner particles to migrate or flow through the solvent from the charged electrostatic latent image area on the electrostatically imageable surface to the conductive image-receiving surface. and should have. Solvents are generally Isopar (from Ekun Corporation, respectively)
l5opar ) G and iso/4- (l5op
ar) 09~C11'' sold under the product name H.
! or 09-Cl2O branched chain aliphatic hydrocarbon mixture or equivalent thereof. The electrical resistivity is preferably on the order of at least about 1090.2 and the dielectric constant is preferably less than about 3V2. The use of non-polar insulating solvents with these properties can improve the stability of toner particles. It helps to ensure that the turnkey does not disappear.

Approximately 200 to approximately 12LON+) No.9 suitable (I C
After applying a voltage to the conductive image-receiving surface to establish an electric field between the electrostatically imageable surface and the conductive image-receiving surface, both surfaces are brought close enough together to form two non-polar insulating solvent layers. to produce a completely liquid transfer medium. a first liquid surface of the first layer of non-polar insulating solvent on the electrostatically imageable surface and a second liquid surface of the second layer of non-polar insulating solvent on the conductive image-receiving surface are joined together; to fill the gap between both surfaces. The voltage required to establish the electric field between the electrostatic imageable surface and the conductive image-receiving surface can range from about 200 delts to about 3500 delts, but preferably about 200 delts.
0 to about 1500 Gault, optimally as described above. The ability to transfer high resolution images is a function of multiple factors: toner, liquid carrier, gap spacing, and applied voltage. Generally, in order to perform high-quality, high-resolution image transfer, the larger the gap distance, the higher the voltage required.

Uniform spacing between the gaps is maintained by the use of spacer strips or gap spacers, seen in FIG. 2, which are electrically isolated from ground.

The developed image is transferred from the electrostatically imageable surface through the gap into the liquid medium to the conductive surface and into the imaging area of the same turn of the phototool where the transferred toner particles reside. and a non-imaging area in which no toner particles are present.

Transfer of the developed image through the liquid-filled gap occurs at the transfer point by keeping a first plane through the electrostatic imageable surface parallel to a second plane through the conductive image-receiving surface. There should be no relative movement between the electrostatic imageable surface and the conductive image receiving surface at the point of transfer;
The transfer point may be a stationary point of transfer or a rolling point. The electrostatically imageable surface that transfers the developed image through the gap to a flat, stationary or moving conductive image-receiving surface includes a P ram or web;
Alternatively, a stationary flat surface can be used. The moving conductive image receiving surface may be a rolling P-ram or web or other suitable means. The electrostatically imageable surface and the conductive image-receiving surface must be held in place at the point of transfer, such as by a vacuum, or alternatively both surfaces must be moved magnetically or electrostatically across the gap. This is accomplished by holding it in place.

This gap between the electrostatically imageable surface and the conductive image receiving surface is preferably at least about 3 mils to about 0.25411111 by the use of spacer strips of desired thickness. 10 mils). Gap approximately 0.0762Yam (approximately 3 mils)
By keeping it larger, any inconsistencies or irregularities within the surfaces are sufficiently isolated to prevent contact between the surfaces and to prevent scuffs or scratches on the master or electrostatically imageable surface. Prevent it from happening.

Spacer strips or gap spacers are sold under the trade name Metal-like Conductive Material or MYLAR. / IJ ester film or a non-conductive material such as cellophane. The spacer strip must be electrically isolated from ground and must be of uniform thickness. The uniform thickness ensures that uniform gap spacing between the electrostatic imageable surface and the conductive image receiving surface is obtained.

Spacers) The IJ tube should preferably be placed outside the image area.

A non-polar insulating layer is formed by applying a first layer and a second layer of a non-polar insulating solvent to the electrostatically imageable surface and the conductive image-receiving surface in sufficient thickness to fill the gap between the two. A first liquid surface and a second layer of the first and second layers of solvent.
The liquid surfaces are joined together to form a continuous liquid transfer medium at the point of transfer of charged toner particles between the electrostatically imageable surface and the conductive image receiving surface. There are surface tension forces that charged toner particles must overcome by traveling through a continuous liquid transfer medium that can impede toner particle movement from an electrostatically imageable surface to a conductive image-receiving surface. do not. Charged toner particles are directed by an electric field applied at the transfer point through a liquid transfer medium created by the joining of two non-polar insulating solvent layers at the transfer point.

As schematically illustrated in FIG. 2, charged toner particles having a predetermined charge are removed as individual particles or collective particles from cross-linked imaging areas of opposite charge with a photosensitive material on an electrostatically imageable surface. Transfer to a conductive image-receiving surface. A conductive image receiving surface is laminated onto an insulating dielectric layer such as fiberglass epoxy. The applied transfer electric field moves the toner particles through a liquid transfer medium of a non-polar insulating solvent and deposits them onto a conductive image-receiving surface, creating imaged areas where toner particles are present and non-imaged areas where toner particles are absent. to generate.

A photosensitive material, such as a photoresist film or a liquid photoresist, on an electrostatically imageable surface acts as a master electrostatic image plate and, depending on the photoresist used, will most likely remain static for a period of time. Because the resistivity difference between the imaged and non-imaged areas on the electrically imageable surface remains relatively constant, a large number of copies can be made with electrostatic transfer techniques. For repeated operations, excess non-polar insulating solvent and excess toner particles on the electrostatically imageable surface must be removed. Residual charge on the electrostatically imageable areas must be discharged, such as by charging the surface of the photosensitive material with an alternating current corona.

After producing a cross-linked imaged region of increased resistivity by exposure to actinic radiation and a non-imaged or background region that remains unexposed to actinic radiation and of low resistivity, a comparison is made. By utilizing the ability of the photosensitive material to maintain resistivity differences for long periods of time, the desired electrostatic latent image/master turn remains in the photosensitive material. Photosensitive materials such as photoresists are typically cross-linked to create a more dielectric sized area that is larger than the background or unexposed areas, depending on the processing speed of image transfer. It must be made of a polymer K to form an imaged area of higher electrical resistivity than that required. Faster processing speeds require larger resistivity differences.

For fine line image transfer, the resistivity of the photosensitive material can range from 1017 to 1011 ohms, depending on the material. The electrical resistivity of the background or non-imaging area should typically be 1010 Ω·tan. For comparison, the resistivities of various materials are known, including some that are traditionally considered insulating materials. Mylar (M71ar) polyester film for electronics is approximately 10,170 mm, aluminum oxide ceramic is approximately 10,160 mm, and α-grade mica is 1013 to 1
017Ω・100, unexposed Dynachem
The AX dry film is approximately 10130 d, with various grades of Union Carpai P Bakelite (Union C
The arbide'5Bakelite) copolymer plastic has a resistivity of about 107 to 1016 ohms. Dune Stone (Dupon the s R15to
n) 3615)' Lie film has a resistivity of approximately 10100.

The imaged area produced by exposure of the photosensitive material to actinic radiation will retain a high voltage charge when charged with a D, C, charging corona, if the conductive backing is electrically grounded. This is the region of increasing resistivity. The non-imaged or background areas, which have low electrical resistivity, quickly release or leak charge through the grounded conductive backing. Charged toner particles suspended in a non-polar insulating solvent are oppositely charged to these latent image forming areas, so that the charged toner particles are attracted to the latent image forming areas.

This allows the transfer of these charged toner particles from the electrostatic imageable surface across the liquid gap to the conductive image receiving surface as described above.

Once a toner image is formed by the toner particles in the imaging area on the conductive image-receiving surface, the toner particles are fused to the conductive image-receiving surface by heating, as schematically illustrated in FIG.

Heat is applied by the use of an open or by blowing hot air through an air slot to reach a temperature at which the binder or polymer that forms the toner particles becomes solvated in the liquid and entrained within the transferred image. Heat it for a certain amount of time. For example, the fusion may be performed at a temperature of about 100°C or higher, about 1
It can be carried out at a temperature of 80° C. or less for about 15 to about 20 seconds.

Thereafter, the non-imaging areas are etched to produce the desired conductive traces in the unetched conductive image-receiving surface coated with toner particles. The etching process utilizes a solution that does not remove conductive material from areas of the conductive image-receiving surface that are protected by toner particles, but that attacks and removes conductive material from areas that are not protected by toner particles. The particular type of etchant used will depend in part on the conductive material being etched and the type of cyst used, so acid and very mild alkaline etchants can be used.

For example, if the conductive image-receiving surface is copper, it is preferred to use an etching agent containing acidic cupric chloride.

The final step in the electrostatic transfer method for making copies is a peeling step. During this step, the toner particles are suitably removed or stripped from the imaged areas, such as by washing with methylene chloride or acetone or an aqueous alkaline solution or other suitable solution.

Examples are shown next to demonstrate the obtained results, but the scope of the present invention is not limited by the description of these Examples. Examples describe how a permanent master with a persistent conductive latent image on an electrostatic imageable surface can be obtained and how gap spacing and voltage levels can be adjusted to achieve successful electrostatic image transfer. This is to show that change is possible. Embodiments also describe a method of using a photoconductor, or permanent master, as an electrostatically imageable surface and a method of using a photoconductor or permanent master as an electrostatically imageable surface and applying a P-lime to each conductive image-receiving surface prior to transfer of a developed latent image from the electrostatically imageable surface. It is also shown how successful electrostatic image transfer can be achieved without the need to apply film or liquid resist.

Example 1 A liquid toner was prepared for use by compounding the following ingredients in the indicated amounts in a high speed dispersion device.

Ingredients Quantity <ti> Required ingredients
(ISOPAR) H1248,6 Solvent - Carrier Rosin Ester Allied (Allied) AC307,8 Chain Polyethylene Polyethylene 6A Suspension Phthalocyanine Green 2292 Colorant -
Pigment alkali pull () 158.4
Colorant - Pigment These ingredients are 71.1 to 104.5
While maintaining a temperature of ℃ (i60~220?) 80
Mixed for 10 minutes at a speed of 00 rpm.

Lauryl methacrylate 104.1 and methyl methacrylate 44, both commercially available from Rohm and Haas.
．． Vazo 64 from 7 F and Duin Co.
Azobisisobutonitrile sold as 3. O
606 g of amphiphilic graft copolymer system was prepared by mixing I.

Amphiphilic copolymer stabilizer 108.2II was then prepared according to the method described below. 1 with stirrer, thermometer and reflux condenser! Petroleum ether (boiling point 90-120°C) 40011 is placed in a reaction flask and heated to a moderate reflux rate at normal pressure. Lauryl methacrylate 19411.
A solution of glycidyl methacrylate 6.011, hendiyl peroxide yeast (>60 Mfk% in dioctyl phthalate) is made and placed in a 250 m/ drop funnel attached to a reflux condenser. Add dropwise into the refluxing solvent at such a rate that it takes 3 hours to add. After the final addition of monomer, after refluxing for 40 minutes at pressure, add 0.5.9 of lauryl dimethylamine and add another hour at normal pressure. Continue refluxing. Next, add 0.11 g of hyrquinone and 5.0 g of methacrylic acid, and continue refluxing under nitrogen atmosphere until about 52% of the glycidyl groups are esterified (about 16 hours). The product obtained is a slightly viscous pale yellow liquid.

Exxon's Isopar (I 5OPAR) H34
5,8I to the amphiphilic copolymer stabilizer of 108.211 and the above amounts of lauryl methacrylate, methyl methacrylate, azobisisobutonitrile to form 606Ii.
An amphiphilic graft copolymer system is obtained.

This solution was heated at about 70°C for about 4 to about 20 hours under a nitrogen atmosphere.
Polymerization was carried out by heating at i58'F)K.

Addition of Isopar 60611 (ISOPA) to the above solution
Add R)H and bring the temperature to about 71.1-82.3°C (i60
Mixing continued for 10 minutes at 8000 RPM while holding the temperature at 8000 RPM (~180 below).

Finally, the isopar (ISOPAR) H of 3578.9
was added, the mixing speed was reduced to 1000-200 ORPM, and mixing continued for 30 minutes. During this final step, the temperature of the mixture was maintained at 48.8-60°C (i20-140?).

A liquid toner concentrate was then prepared by mixing the following in a Seiden attritor type mill.

Carnauba wax 58.3 ISOPAR H694,5 solvent-carrier These components were mixed at 30 ORPM at a temperature of 23.9°C.
(75'F) for 3 hours to form a toner concentrate.

This toner concentrate was further diluted to about 1 to about 2 parts solids to form a working solution for use in electrostatic imaging.

After corona charging a +1 Mium photoconductor (typical of the NP method type) coated with a MYLAR polyester film layer, a circuit trace was recorded on a Canon model 1824 copier with approximately 0
．． A charged latent image was formed by exposure at a temperature of 75 to about 2.70. This charged latent image was developed by applying liquid toner to the electrostatically imageable surface, a coated sulfided metal photoconductor.

The electrostatically imageable surface of this photoconductor is mounted on an internal aluminum substrate P ram. rRemove the ram from the copier. The high voltage power source has its ground lead connected inside the P ram and its positive lead connected to the copper surface of the conductive image receiving surface. A cellophane spacer (IJ tube, or gap spacer) was used between the drum and the conductive surface. A conductive surface was coated with a liquid containing a non-polar insulating solvent. The electrostatically imageable surface of the drum was coated during the development process. 1000 volts D, C, @ current was applied and the gap was set at α254 m (i0 mils).

A sulfide force Pmium r ram is manually rolled across the spacer strip to create a point of transfer of the latent image from the electrostatic imageable surface to the copper conductive image receiving surface. The image transfer was successful, resulting in an image with excellent resolution and good density.

Example 2 The sulfurizing power (%) Mium photoconductor P ram of Example 1 was washed and dried. The same liquid was used in the same equipment as in Example 1, and the same photoconductor latent image was obtained. The drum was wetted with liquid transfer medium and the process of Example 1 was repeated. A liquid transfer medium was applied to a conductive image receiving surface. A voltage of 500 volts was applied, and the same gap spacing as in Example 1 was set. Although the image transfer was successful, the amount of transferred toner particles forming the transferred image was less than in Example 1 and was very bright over the entire image area. The applied voltage appeared to be insufficient to transfer most toner particles across the 0.254 m (io mil) gap.

Example 3 The same steps and liquid transfer medium used in Example 2 were repeated. The conductive image receiving surface was wetted with the liquid transfer medium by application to the conductive image receiving surface with a squeegee. Spacer strips were set at 0.0762 m (3 mil) to obtain a uniform 0.0762 m (3 mil) separation between both surfaces, and a voltage of 1000 volts was used.

Although clear high-resolution images were obtained with good density,
Some boiler areas appeared in the billions. The image was uniform and clear.

Example 4 Using the same process and liquid transfer medium as Example 3, but with a 0.07
The gap spacer for forming the 62 m gap was 3 m thick. 200pol) D, C, an electric field was created by applying a current. A very clear, high-resolution image was transferred from the electrostatic imageable surface to the conductive image-receiving surface, exhibiting image density with good reflectivity. However, No. 4
The density of the T r area and line trace was somewhat lower than that obtained in Example 3, as not all of the toner particles were clearly transferred.

Example 5 The same steps and liquid transfer medium used in Example 2 were used, but the liquid was applied to a squeegee. The gap spacer has a thickness of 0 to form a gap of 0.0254 mm (i mil) between the electrostatic imageable surface and the conductive image receiving surface.
．． It was 0254 m (i mil). 1000pol) D
, C, was applied to form an electric field. The transferred image had good image density, but there were many hollow spots due to the arc. Apparently due to the close proximity of both surfaces and the resulting squishing of the toner particles,
There was some image distortion. Image distortion could be reduced using a system such as a vacuum hold-down system that could hold the receiving substrate rigidly flat. Most of the transferred images were not distorted.

Example 6 Scratch brushed full bar tempered aluminum foil (cDA alloy 1145-R18) 1
0.16c! A conductive substrate of nX 12.7m (4"X S//) was chosen as the conductive substrate for use in the production of the electrostatically imageable surface of the permanent master.

Cleaning or degreasing aluminum substrates.

I checked to see if it was necessary. If necessary, cleaning the substrate with methyl chloride, methylene chloride or trichloroethylene promotes good adhesion of the photoresist to the cleaned surface during the subsequent lamination step. No cleaning was necessary in this example. Dupont Liston (Du Pont Liston)
PontRiston) 215) Lie film photoresist was laminated onto the substrate as a photosensitive material. The lamination is
Western Magnum (We) manufactured by Dynachem of Tustin, California.
sternMagnum) model #XRL-360 laminator. The lamination temperature is approximately 104.4℃ (2
The roll temperature was 20 mm and a speed of 7 minutes over 6 feet. This aluminum foil/Rlston 215 laminate is approximately 0,001 inches thick on P-ly film photoresist. Lieterentele 7 tallate (hereinafter referred to as ``PET'')
A protective top layer of film was applied.

This laminate was exposed to actinic radiation through a negative photo tool using an Optic Beam 5050 exposure device manufactured by Ozotic Radiation. This exposure was carried out after the laminate had been cooled to room temperature after the lamination process. The exposure level was approximately 250 millijoules. The photo tool is Microcopy Te5t Targe.
t) T-10 resolution test chart with par groups varying from 1.0 cycles or line pair/m to 18 cycles or line pair/w, sold by Applied Image Inc. of Lochinister, New York. has been done.

After the master thus produced was stabilized for about 30 minutes to complete photocrosslinking, the protective layer of PET film was peeled off from the dry film photoresist. The aluminum foil below the electrostatically imageable surface was then grounded and the surface was corona charged so that the imaged areas received a positive charge. After a suitable time delay of up to 7 seconds to discharge the background areas, the charged latent image was developed electrophotographically by applying the liquid toner of Example 1 to the electrostatically imageable surface.

Next, the electrostatically imageable surface is
) Excess toner particles were removed by washing with H solvent carrier. At this point, the permanent master is ready for transfer of the developed image from the master to a conductive image receiving surface.

Example 7 Copper ICL1 6cmX 12.7cTn (4'X
5") An electrically conductive substrate was attached. The conductive surface of this laminate was verified to be clean and that no degreasing was required. If necessary, the substrate was cleaned with methyl chloride, methylene chloride or trichloroethylene. can be cleaned to promote good adhesion of the photoresist to the clean surface during subsequent lamination steps. In this example, no cleaning was necessary.
A Western Magnum machine operated at a speed of 7 minutes and a roll temperature of about 104.4°C (220?)
Magnum) model XRL-360 was used to apply Dupont R15t onto the surface.
on) 3615 dry film photoresist was laminated. Approximately 0.00254 m (0.001 m) thick on dry film photoresist of Steel/Liston 3615 laminate
We have established a top protection policy for in).

After the laminate was allowed to cool to room temperature for 10-15 minutes, the P-lye film was exposed to an active radiation head against a negative photo tool in two steps. 7 Darts (ADDA) manufactured by Parkley Technical Co., Ltd. of Tsupp Side, New York.
LUX Model 1421-40 equipment performs pre-fogging for approximately 5 seconds over approximately 25 m.
I went with J's energy level. The second step of this exposure process involved exposing the negative phototool and electrostatically imageable surface to an energy level of about 475 millijoules or an exposure time of about 55 seconds. The negative photo tool is the Microcopy Test Target (Microcopy Te5t Ta), available from Applyr Image Inc. of Rochester, New York.
rget) T-10 resolution test chart.

The group of pads on the photo tool varied from 1.0 cycle or line pair/1 m to 18 line pairs/■.

The exposed electrostatically imageable surface was then cooled to room temperature for about 30 minutes, thereby completing crosslinking within the dry film. The protective layer of the PET film was peeled off. The copper substrate was grounded and the electrostatically imageable surface was corona charged such that the imaged areas received a positive charge. After a short delay of about 1 second or more to discharge the background area,
The charged permanent image was then electrophotographically developed with the liquid toner of Example 1. From this developed permanent 1 star,
Iso/4- (Isop) without drying the toner
ar) Excess toner particles were washed away with H solvent carrier. At this point, the developed permanent image on the electrostatic master is ready for transfer to a conductive image receiving surface.

The electrostatic master thus produced was laid flat on a generally flat work surface. 2 pieces of 3 (03) mil thick MYLAR fl? A Lyester baser strip was placed along a pair of parallel opposing edges of the master, outside the developed image area.

Kapton (Kap) with thickness 0.0254+wa (i mil)
ton) polyimide)% laminated to the insulating layer 14.17
．． A flexible conductive image-receiving surface of 9 ('A oz.) copper foil was wrapped with wrapping tape, and each end was wrapped with a diameter of 3.81 cln (I
V2in) (7) Fixed to the drum. By immersing this cylinder, the image receiving surface is made isopar (Is
opar) H solvent carrier layer. Alternatively, the image receiving surface could be coated by pouring the liquid onto the image receiving surface.

A potential of approximately 800 volts was created to create an electric field across a gap of approximately Q, 3 mils.

The conductive image-receiving surface of the copper foil was positively charged with respect to the master electrically conductive copper substrate for use with negatively charged toner particles.

3,81 cm to which a conductive image-receiving surface is fixed (
i) Diameter - rotated on spacer strips on both ends of the ram master. Toner particles were transferred from the master to the conductive image-receiving surface as the roller passed over the master at each discrete transfer point.

The conductive image-receiving surface is then exposed to an air blower for up to about 30 seconds to dry the non-imaging areas that constitute the background areas. While the non-imaged areas must be dry, the imaged areas remain wet to prevent the polymers within the toner particles from solvating into the solvent carrier and flying out of the imaged areas ((
Must be. An air knife can also be used to dry the non-imaged areas.

The transferred image on the conductive image receiving surface is then fused by placing it in the open for about 30 seconds.

The open temperature before opening was about 180°C.

Fusing is accomplished by a temperature gradient that effectively occurs because when the aperture is opened and the conductive image receiving surface is admitted therein, the temperature within the aperture decreases as a result. After closing the open door again, gradually increase the open temperature to 180℃
Gradually increase the temperature to the level.

While preferred methods incorporating the principles of the invention have been illustrated and described, the invention is not limited to the particular illustrations and methods so presented, and in fact may be useful in practicing the broader aspects of the invention. It is to be understood that widely different means and methods may be used.

For example, to effect transfer, an electric field established between an electrostatic imageable surface and a conductive image-receiving surface directs charged toner particles across a liquid medium such that the charge on the toner particles causes It can be applied with either positive or negative polarity. Negatively charged toner particles will be attracted to the positively charged image receiving surface and will be repelled by the negative counter charge of the electrostatically imageable surface. When using positively charged toner particles, the toner particles will be attracted to the negatively charged conductive image-receiving surface and will therefore be repelled by the positive countercharge of the electrostatically imageable surface. .

Similarly, in developing an electrostatically imageable master surface,
Alternative methods can be used. Negatively charged toner particles will be attracted to a positively charged latent image, or conversely, positively charged toner particles will be attracted to a negatively charged latent image. , in the case of reversal development in which the background areas are exposed, the desired image areas on the electrostatically imageable surface are uncharged and the surrounding non-image areas are charged to the same charge as the toner particles. Toner particles will be repelled from the non-image area onto the desired area. Also, mineral spirits are equally good as non-polar insulating solvents, as long as they have high resistivity and low viscosity.

Gap spacing can equally well be used with a quepu wafer array that maintains the desired distance between the electrostatic imageable surface and the conductive image-receiving surface.

Electric fields can be established in several ways.

For example, in conductive surfaces such as copper laminates, or in the case of dielectric materials such as mylar polyester lined with a conductive surface, the electric field is created by direct charging. When using a dielectric receiving surface such as a Mylar polyester film, a conventional corona charging or roller charging front or back band-1 can be used.

Electrostatically imageable surfaces can be photoconductor or selenium photoconductor surfaces such as mylar polyester films or polystyrene or monosulfide surfaces with monoethylene overcoatings, or carbazole and carbazole derivatives, polypynylcarnozole, anthracene, etc. It can be any suitable organic photoconductor such as. If the electrostatically imageable surface uses a persistent latent image as a permanent master, the surface may be zinc oxide or an organic photoconductor developed with toner fused onto the master, or a dry film or liquid photoresist. can be.

The type of photosensitive material applied to the conductive backing to produce the permanent master can vary as long as it is permanently imageable and has the correct resistivity characteristics. For example, when using P-life film resist, the film can be an aqueous paste, a semi-aqueous paste, or a solvent paste. A photoconductive insulator film of zinc oxide dispersed in a resin binder can also be used.

The methods described herein are discussed with respect to manufacturing printed circuit boards. However, electrostatic image transfer from a permanent master
It goes without saying that it is equally well accepted for use in label manufacturing, high speed document production and photochemical machining or milling. The permanent master of the present invention can be used with liquid or dry toners. Dry toners can be applied by magnetic brushes or particle cascades or particle bed systems to the photosensitive materials used in the production of permanent masters.

The appended claims are intended to cover all obvious changes in details, materials and arrangement of parts that occur to those skilled in the art from reading this specification.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a prior art print and etch printed circuit board manufacturing process, and FIG. 2 is a schematic illustration of a prior art print and etch printed circuit board manufacturing process, and FIG. 1 is a schematic diagram of the method of the present invention using a permanent master that can be reused to generate multiple copies of a desired conductive trace epi-on; FIG. Patent applicant: 2 people other than Olin No.1nt Specialty Products, Inc.

Claims (1)

[Claims] 1) The following steps: (a) coating a conductive substrate with a photosensitive material whose resistivity changes upon exposure to a source of actinic radiation, thereby being electrostatically imageable; (b) exposing the photosensitive material to actinic radiation using a phototool to form a persistent latent image on the photosensitive material to form non-imaging areas of low electrical resistivity and electrical (c) a non-image area and a latent image having an electrostatic contrast corresponding to the non-image forming area with low electric resistivity and the latent image area with high electric resistivity; A method for making a permanent master having a persistent latent image for use in repeated electrostatic image transfer to an image-receiving surface, the method comprising charging an electrostatically imageable surface to form a region. 2) The method according to claim 1, further comprising the use of a dry film photoresist as the photosensitive material. 3) The method according to claim 1, further comprising using a liquid photoresist as the photosensitive material. 4) The method of claim 1 further comprising providing the flexible dielectric material with a conductive substrate. 5) A method according to claim 1, further comprising providing the rigid inducing material with an electrically conductive substrate. 6) The following steps: (a) coating a conductive material with a photosensitive material whose resistivity changes upon exposure to an actinic radiation source; (b) coating a conductive material with a photosensitive material whose resistivity changes upon exposure to an actinic radiation source; (c) forming a persistent latent image thereon, forming electrostatically contrasting non-imageable areas and latent image areas, thereby forming an electrostatically imageable surface; (d) applying charged toner particles to the electrostatically imageable surface, the charged toner particles being electrostatically imageable; developing the electrostatic latent image by forming a developed latent image directed towards the latent image area of the surface; (e) forming an electric field between the electrostatically imageable surface and the image receiving surface; (f) placing the image-receiving surface adjacent the electrostatically imageable surface; and (g) transferring the developed latent image from the electrostatically imageable surface to the image-receiving surface at a transfer point. (h) fusing the transferred toner particle image to the image receiving surface; A method of forming a toner pattern on top. 7) further steps of: (a) etching the non-imaging areas of the conductive surface to remove the image-receiving surface from the non-imaging areas of the image-receiving surface; and (b) removing toner particles from the image-forming areas of the image-receiving surface. 7. The method of claim 6, comprising removing. 8) The method of claim 6 further comprising applying a liquid containing an at least partially non-polar insulating solvent to the image-receiving surface. 9) The method of claim 6 further comprising maintaining a gap between the image receiving surface and the electrostatically imageable surface during transfer at the transfer point. 10) A method according to claim 6, further comprising the use of a conductive laminate provided with an image-receiving surface. 11) The method of claim 10, further comprising using a conductive image-receiving surface as the image-receiving surface. 12) The method of claim 8, further comprising suspending the charged toner particles in the liquid. 13) The method of claim 12, further comprising using a liquid containing an at least partially non-polar insulating solvent as the liquid in which the charged toner particles are suspended. 14) The following steps: (a) coating a conductive substrate with a photosensitive material whose resistivity changes upon exposure to an actinic radiation source; (b) coating a conductive substrate with a photosensitive material whose resistivity changes upon exposure to an actinic radiation source; (c) forming a persistent latent image thereon to form electrostatically contrasting non-imageable areas and latent image areas, thereby forming an electrostatically imageable surface; charging a latent image area on the electrostatically imageable surface; (d) charging the electrostatically imageable surface suspended in a liquid comprising an at least partially non-polar insulating solvent; developing the electrostatic latent image area by applying toner particles to form a first liquid layer having a first liquid surface, the charged toner particles forming a latent image on the electrostatically imageable surface; (e) applying a liquid comprising an at least partially non-polar insulating solvent to the image-receiving surface to form a second liquid layer having a second liquid surface; (f) forming an electric field between the electrostatically imageable surface and the image-receiving surface; and (g) connecting the image-receiving surface to the electrostatically imageable surface such that a gap is maintained between the two. (h) transferring the developed latent image from the imageable surface to the image-receiving surface electrostatically through a liquid at a transfer point to form a transferred toner particle image in the non-imaged areas and the imaged areas; (i) maintaining a gap between the electrostatically imageable surface and the image-receiving surface during transfer at the transfer point; and (j) fusing the transferred toner particle image to the image-receiving surface. , (k) etching the non-imaging areas of the conductive surface to remove the image-receiving surface from the non-imaging areas of the image-receiving surface, and (l) removing toner particles from the image-forming areas of the image-receiving surface. A method of forming a toner pattern on a spatially isolated image-receiving surface. 15) The method of claim 14, further comprising using a conductive image-receiving surface as the image-receiving surface. 16) The method of claim 15, further comprising maintaining the gap by contacting the first liquid surface with the second liquid surface to form a liquid transfer medium across the gap. 17) further comprising maintaining a gap between about 3 to about 20 mils between the electrostatically imageable surface and the conductive surface during transfer at the transfer point; The method according to claim 16. 18) A method according to claim 15, further comprising the use of a conductive laminate provided with a conductive image-receiving surface. 19) (a) a conductive substrate; and (b) a photosensitive material applied to the conductive substrate that forms a persistent electrostatic latent image after change in electrical resistivity upon exposure to actinic radiation; further comprising a photosensitive material thereon, thereby having a non-image forming area of low electrical resistivity and a latent image area of high electrical resistivity; and (c) a photosensitive material and a conductive substrate. a charged electrostatically imageable surface formed with an electrostatically contrasting non-image area corresponding to a non-image area of low resistivity and a latent image area of high resistivity; A permanent master for use in repeated electrostatic image transfer to an image-receiving surface, comprising a charged electrostatically imageable surface that also has a latent image area and a latent image area. 20) The permanent master according to claim 19, wherein the latent image area further has charging polarity. 21) The permanent master of claim 20, wherein the latent image area further comprises charged toner particles of opposite polarity to that of the latent image area. 22) A permanent master according to claim 19, wherein the non-imaging areas further have a charged polarity. 23) The permanent master of claim 22, wherein the latent image area further comprises charged toner particles of the same polarity as the non-image forming area. 24) A permanent master according to claim 19, wherein the photosensitive material is selected from the group consisting of dry film photoresists or liquid photoresists.