NanoPrint Technologies uses proprietary printing technology, processes, and expertise to achieve the highest quality and consistency for printing high resolution lines and thin layers at high speeds. Printed Electronics (PE) require a very high level of control in the printing process to provide high yield results. Many companies that design PE components will have a prototype printer, most likely an ink jet printer that they can use to test designs. When it comes time for volume production, most will turn to companies like ours to meet their cost, capacity, and quality requirements.
As current applications transition to PE and new applications emerge, there will be an increasing demand for printing facilities that are able to meet the requirements of PE. While PE is revolutionary in what it will do for products that we all use, the technology used to print electronics will continue to be an evolution and merging of traditional printing technologies. Product and application developers will look to printers for design and production consulting just as the traditional electronics market looks to semiconductor fabrication (fab) houses today.
Offset printing
Offset Lithography Printing Process
Offset printing is a widely used printing technique where the inked image is transferred (or "offset") from a plate to a rubber blanket, then to the printing surface. When used in combination with the lithographic process, which is based on the repulsion of oil and water, the offset technique employs a flat (planographic) image carrier on which the image to be printed obtains ink from ink rollers, while the non-printing area attracts a film of water, keeping the non-printing areas ink-free.
Offset printing advantages
Advantages of offset printing compared to other printing methods include:
- Consistent high image quality. Offset printing produces sharper and cleaner images and type than letterpress printing because the rubber blanket conforms to the texture of the printing surface.
- Quick and easy production of printing plates.
- Longer printing plate life than on direct litho presses because there is no direct contact between the plate and the printing surface.
Photo offset
The most common kind of offset printing is derived from the photo offset process, which involves using light-sensitive chemicals and photographic techniques to transfer images and type from original materials to printing plates.
In current use, original materials may be actual photographic prints and typeset text. However, it's more common -- with the prevalence of computers and digital images -- that the source material exists only as data in a digital publishing system.
Web offset
Offset litho printing on to a web (reel) of paper. Commonly used for printing of newspapers and magazines.
Sheet-fed litho
Offset litho printing on to single sheets of paper or board. Commonly used for printing of short run magazines, brochures, letter headings, general commercial (jobbing) printing.
Present day
Offset printing is the most common form of high volume commercial printing, due to advantages in quality and efficiency in high volume jobs. While modern digital presses (Indigo Digital Press, for example) are getting closer to the cost/benefit of offset for high quality work, they have not yet been able to compete with the sheer volume of product that an offset press can produce. Furthermore, many modern offset presses are using computer to plate systems as opposed to the older computer to film workflows, which further increases their quality.
In the last two decades flexography has become the dominant form of printing in packaging due to lower quality expectations and the significantly lower costs in comparison to other forms of printing.
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Diagram of rotogravure process Gravure may also refer to Gravure idol.
Rotogravure (gravure for short) is a type of intaglio printing process, in that it involves engraving the image onto an image carrier. In gravure printing, the image is engraved onto a copper cylinder because, like offset and flexography, it uses a rotary printing press. The vast majority of gravure presses print on reels of paper, rather than sheets of paper. (Sheetfed gravure is a small, specialty market.) Rotary gravure presses are the fastest and widest presses in operation, printing everything from narrow labels to 12-feet-wide rolls of vinyl flooring. Additional operations may be in-line with a gravure press, such as saddle stitching facilities for magazine/brochure work.
In 1932 a George Gallup "Survey of Reader Interest in Various Sections of Sunday Newspapers to Determine the Relative Value of Rotogravure as an Advertising Medium" found that rotogravures were the most widely read sections of the paper and that advertisements there were three times more likely to be seen by readers than in any other section. The rotogravure process is still used for commercial printing of magazines, postcards, and corrugated (cardboard) product packaging.
In the latter quarter of the 19th centure, the method of image photo transfer onto carbon tissue covered with light-sensitive gelatin was discovered and was the beginning of rotogravure.
Three methods of photoengraving have been used for engraving of gravure cylinders, where the cell open size or the depth of cells can be uniform or variable:
Gravure cylinders nowadays are typically engraved digitally by a diamond tipped or laser etching machine. On the gravure cylinder, the engraved image is composed of small recessed cells (or 'dots') that act as tiny wells. Their depth and size control the amount of ink that gets transferred to the substrate (paper or other material, such as plastic or foil) via a process of pressure, osmosis, and electrostatic pull. (A patented process called "Electrostatic Assist" is sometimes used to enhance ink transfer.)
A rotogravure printing press has one printing unit for each color, typically CMYK or cyan, magenta, yellow and key (printing terminology for black). The number of units vary depending on what colors are required to produce the final image. There are five basic components in each color unit: an engraved cylinder (whose circumference can change according to the layout of the job), an ink fountain, a doctor blade, an impression roller, and a dryer. While the press is in operation, the engraved cylinder is partially immersed in the ink fountain, filling the recessed cells. As the cylinder rotates, it draws ink out of the fountain with it. Acting as a squeegee, the doctor blade scrapes the cylinder before it makes contact with the paper, removing ink from the non-printing (non-recessed) areas. Next, the paper gets sandwiched between the impression roller and the gravure cylinder. This is where the ink gets transferred from the recessed cells to the paper. The purpose of the impression roller is to apply force, pressing the paper onto the gravure cylinder, ensuring even and maximum coverage of the ink. Then the paper goes through a dryer because it must be completely dry before going through the next color unit and absorbing another coat of ink.
Because gravure is capable of transferring more ink to the paper than other printing processes, gravure is noted for its remarkable density range (light to shadow) and hence is a process of choice for fine art and photography reproduction, though not typically as clean an image as that of sheet fed litho or web offset litho. Gravure is widely used for long-run magazine printing in excess of 1 million copies. Gravure's major quality shortcoming is that all images, including type and "solids," are actually printed as dots, and the screen pattern of these dots is readily visible to the naked eye. Examples of gravure work in the United States are typically long-run magazines, mail order catalogs, consumer packaging, and Sunday newspaper ad inserts.
Other application area of gravure printing is in the flexible packaging sector. A wide range of substrates such as Polyethylene, Polypropylene, Polyester, BOPP etc.. can be printed in the gravure press.
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Inkjet printers are a type of computer printer that operates by propelling tiny droplets of liquid ink onto paper. They are the most common type of computer printer for the general consumer due to their low cost, high quality of output, capability of printing in vivid color, and ease of use.
The emerging Ink jet material deposition market uses ink jet technologies, typically piezoelectric ink jet, to deposit materials on substrates.
In general
In the personal and small business computer market, inkjet printers currently predominate. Inkjets are usually inexpensive, quiet, and reasonably fast; and many models can produce high-quality output. Like most modern technologies, the present-day inkjet has built on the progress made by many earlier versions. Among many contributors, Epson, Hewlett-Packard and Canon can claim a substantial share of credit for the development of the modern inkjet. In the worldwide consumer market, four manufacturers account for the majority of inkjet printer sales: Canon, Hewlett-Packard, Epson, and Lexmark.
Ink jet printers use one of three main technologies: thermal, piezoelectric, and continuous.
Advantages
Compared to earlier consumer-oriented printers, inkjets have a number of advantages. They are quieter in operation than impact dot matrix or daisywheel printers. They can print finer, smoother details through higher printhead resolution, and many inkjets with photorealistic-quality color printing are widely available.
In comparison to more expensive technologies like thermal wax, dye sublimations, and laser printers, inkjets have the advantage of practically no warm up time and lower cost per page (except when compared to laser printers).
Present-day inkjet printers use stochastic or FM screening, which gives better-quality results than low-cost laser printers when printing photographic images. Some inkjet printers print dots of more than one size, so that the screening is not purely "FM".
For some inkjet printers, monochrome ink sets are available either from the printer manufacturer or third-party suppliers. These allow the inkjet printer to compete with the silver-based photographic papers traditionally used in black-and-white photography, and provide the same range of tones – neutral, "warm" or "cold". When switching between full-color and monochrome ink sets, it is necessary to flush out the old ink from the print head with a special cleaning cartridge.
As opposed to most other types of printers, inkjet cartridges can be refilled. Most cartridges can be easily refilled by drilling a hole in and filling the tank portion of the cartridge. This method is more cost effective as opposed to buying a new cartridge each time one runs dry.
Disadvantages
Inkjet printers may have a number of disadvantages:
- The print heads may clog when ink dries up in them during a prolonged period of disuse
- The ink is often very expensive (for a typical OEM cartridge priced at $15, containing 5 ml of ink, the ink effectively costs $3000 per liter)
- Many "intelligent" ink cartridges contain a microchip that communicates the estimated ink level to the printer; this may cause the printer to display an error message, or incorrectly inform the user that the ink cartridge is empty. In some cases, these messages can be ignored, but many inkjet printers will refuse to print with a cartridge that declares itself empty, in order to prevent consumers from refilling cartridges.
- The color gamut of inkjet printers is limited
- The capacity of ink cartridges is limited; a typical black ink cartridge will print 100-300 pages of text, while a toner cartridge for a laser printer may last 2,500-10,000 pages.
- The lifetime of inkjet prints is limited; they may eventually fade and the color balance may change
- Some inkjets use multiple-ink cartridges which combine C, M and Y ink tanks; these must be replaced as a unit when only one color runs outs.
- For best results, inkjet printers require more expensive paper than laser printers.
- Double-sided printing is not usually practical with inkjet printers.
- Because the ink used in most inkjets is water-soluble, care must be taken with inkjet-printed documents to avoid even the smallest drop of water, which can cause severe "blurring" or "running." Similarly, water-based highlighter markers can blur inkjet-printed documents.
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Screenprinting, silkscreening, or serigraphy is a printmaking technique that creates a sharp-edged image using a stencil. A screenprint or serigraph is an image created using this technique.
It began as an industrial technology, and was adopted by American graphic artists in the early 1900s. It is currently popular both in fine arts and in commercial printing, where it is commonly used to print images on T-shirts, hats, CDs, DVDs, ceramics, glass, polyethylene, polypropylene, paper, metals, and wood.
Graphic screenprinting is widely used today to create many mass or large batch produced graphics, such as posters or display stands. Full color prints can be created by printing in CMYK (cyan, magenta, yellow and black). Screenprinting is often preferred over other processes such as dye sublimation or inkjet printing because of its low cost and ability to print on many types of media.
Printing technique
A screen is made of a piece of porous, finely woven fabric (originally silk, but typically made of polyester since the 1940s) stretched over an aluminum frame. Areas of the screen are blocked off with a non-permeable material to form a stencil, which is a positive of the image to be printed; that is, the open spaces are where the ink will appear.
The screen is placed atop a substrate such as paper or fabric. Ink is placed on top of the screen, and a fill bar is used to fill the mesh openings with ink. The operator begins with the fill bar at the rear of the screen and behind a reservoir of ink. The operator lifts the screen to prevent contact with the substrate and then using a slight amount of downward force pulls the fill bar to the front of the screen . This affectively fills the mesh openings with ink and moves the ink reservoir to the front of the screen. the operator then uses a squeegee (rubber blade) to move the mesh down to the substrate and pushes the squeegee to the rear of the screen. The ink that is in the mesh opening is transferred by capillary action to the substrate in a controlled and prescribed amount, i.e. the wet ink deposit is equal to the thickness of the stencil. As the squeegee moves toward the rear of the screen the tension of the mesh pulls the mesh up away from the substrate leaving the ink upon the substrate surface.
Textile items are printed in multi-color designs using a wet on wet technique, while graphic items are allowed to dry between colors that are then printed with another screen and often in a different color. The screen can be re-used after cleaning.
While the public thinks of garments in conjunction with screen printing, the technique is used on tens of thousands of items, decals, clock and watch faces, and many more products.
Versatility
Screenprinting is more versatile than traditional printing techniques. The surface does not have to be printed under pressure, unlike etching or lithography, and it does not have to be planar. Screenprinting inks can be used to work with a variety of materials, such as textiles, ceramics, metal, wood, paper, glass, and plastic. As a result, screen printing is used in many different industries, from clothing to product labels to circuit board printing.
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Letterpress printing is a term for printing text with movable type, in which the raised surface of the type is inked and then pressed against a smooth substance to obtain an image in reverse. In addition to the direct impression of inked movable type onto paper or another receptive surface, the term letterpress can also refer to the direct impression of inked media such as zinc "cuts" (plates) or linoleum blocks onto a receptive surface.
History
Early Chinese woodblock printing used characters or images carved in relief from before 750AD, and this form of printing was widespread throughout Eurasia as a means of printing patterns on textiles. Printing of images, first on cloth, then from about 1400 on paper was practised in Europe. In the 1400s, Johann Gutenberg (among others) is credited with the invention of movable type printing from individually-cast, reusable letters set together in a forme (frame). This had previously been invented in Asia, but the two inventions were probably not connected. He also invented a wooden printing-press where the type surface was inked and paper laid carefully on top by hand, then slid under a padded surface and pressure applied from above by a large threaded screw. Later metal presses used a knuckle and lever arrangement instead of the screw, but the principle was the same.
With the advent of industrial mechanisation, the inking was carried out by rollers which would pass over the face of the type and move out of the way onto a separate ink-bed where they would pick up a fresh film of ink for the following sheet. Meanwhile a sheet of paper was slid against a hinged platen (see image) which was then rapidly pressed onto the type and swung back again to have the sheet removed and the next sheet inserted (during which operation the now freshly-inked rollers would run over the type again). In a fully-automated 20th century press, the paper was fed and removed by vacuum sucker grips.
Industrial-scale use in the 20th century
Rotary presses were used for high-speed work. In the oscillating press, the forme slid under a drum around which each sheet of paper got wrapped for the impression, sliding back under the inking rollers while the paper was removed and a new sheet inserted. In a newspaper press, a papier-mâché mixture (flong) was used to make a mould of the entire forme of type, then dried and bent, and a curved metal plate cast against it. The plates were clipped to a rotating drum, and could thus print against a continuous reel of paper at the enormously high speeds required for overnight newspaper production.
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A flexographic printing plate.
Flexography (also called surface printing), often abbreviated to flexographic, is a method of printing most commonly used for packaging.
A flexo print is achieved by creating a mirrored master of the required image as a 3D relief in a rubber or polymer material. A measured amount of ink is deposited upon the surface of the printing plate (or printing cylinder) using an anilox roll. The print surface then rotates, contacting the print material which transfers the ink.
Flexo is so named because it was originally used as a method of printing onto corrugated cardboard, which has a very uneven surface. It is required that the printing plate surface maintain contact with the cardboard, which it does by being flexible. Also, unprinted high points on the cardboard must not get printed by ink remnants not on the plate surface, which is achieved by ensuring a sufficient depth for the non-print areas of the plate.
Originally flexo printing was very low quality. In the last 3 decades great advances have been made, including improvements to the plate material and the method of plate creation—usually photographic exposure followed by chemical etch, though also by direct laser engraving. Laser-etched anilox rolls also play a part in the improvement of print quality. Full colour picture printing now occurs, and some of the finer presses available today in combination with a skilled operator allow quality that rivals the lithographic process. One ongoing improvement has been the increasing ability to reproduce highlight tonal values, thereby providing a workaround for the very high dot gain associated with flexo print.
Flexo has an advantage over lithography in that it can use a wider range of inks and is good at printing on a variety of different materials. Flexo inks, like those used in gravure and unlike those used in lithography generally have low viscosity. This enables faster drying and, as a result, faster production; that means low cost. Printing press speeds of 450 meters per minute are regular with modern technology high end printers, like Windmoeller und Hollscher or Schiavi type. The main printing process worldwide for flexible packaging are rotogravure, for very large runs, and flexo for large and medium runs.
Typical products printed using flexography include brown corrugated boxes, flexible packaging including retail and shopping bags, food and hygiene bags and sacks, flexible plastics, self adhesive labels, and wallpaper. A number of newspapers now eschew the more common offset lithography process in favour of flexo.
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Lithography stone and mirror-image print of a map of Munich.
Invented by Bavarian author Aloys Senefelder in 1796,[1][2] lithography is a method for printing on a smooth surface. It can be used to print text or artwork onto paper or another suitable material. It can also refer to photolithography, a microfabrication technique used to make integrated circuits and microelectromechanical systems.
Printing
The principle
Lithography press for printing maps in Munich.
Lithography is a printing process that uses chemical processes to create an image. For instance, the positive part of an image would be a hydrophobic chemical, while the negative image would be water. Thus, when the plate is introduced to a compatible ink and water mixture, the ink will adhere to the positive image and the water will clean the negative image. This allows for a relatively flat print plate which allows for much longer runs than the older physical methods of imaging (e.g., embossing or engraving).
The chemical process
Lithography works because of the repulsion of oil and water. The image is drawn on the surface of the print plate with an oil-based medium (hydrophobic). The range of oil-based mediums is endless, but the dexterity of the image relies on the lipid content of the material being used--its ability to withstand water and acid. Following the placement of the image is the application of an acid emulsified with gum arabic. The function of this emulsion is to create a salt layer directly around the image area. The salt layer seeps into the pores of the stone, completely enveloping the original image. This process is called etching. Using lithographic turpentine, the printer then removes the greasy drawing material, leaving only the salt layer; it is this salt layer which holds the skeleton of the image's original form. When printing, the stone or plate is kept wet with water. Naturally the water is attracted to the layer of salt created by the acid wash. Ink that bears a high lipid content is then rolled over the surface. The water repels the grease in the ink and the only place for it to go is the cavity left by the original drawing material. When the cavity is sufficiently full, the stone and paper are run through a press which applies even pressure over the surface, transferring the ink to the paper and off the stone.
The modern process
Modern high-volume lithography is used to produce posters, maps, books, newspapers, and packaging —just about any smooth, mass-produced item with print on it.
In this form of lithography, which depends on photographic processes, flexible aluminum or plastic printing plates are used in place of stone tablets. Modern printing plates have a brushed or roughened texture and are covered with a photosensitive emulsion. A photographic negative of the desired image is placed in contact with the emulsion and the plate is exposed to light. After development, the emulsion shows a reverse of the negative image, which is thus a duplicate of the original (positive) image. The image on the plate emulsion can also be created through direct laser imaging in a CTP (Computer-To-Plate) device called a platesetter. The positive image is the emulsion that remains after imaging. For many years, chemicals have been used to remove the non-image emulsion, but now plates are available that do not require chemical processing.
The plate is affixed to a drum on a printing press. Rollers apply water, which covers the blank portions of the plate but is repelled by the emulsion of the image area. Ink, applied by other rollers, is repelled by the water and only adheres to the emulsion of the image area--such as the type and photographs on a newspaper page.
If this image were directly transferred to paper, it would create a positive image, but the paper would become too wet. Instead, the plate rolls against a drum covered with a rubber blanket, which squeezes away the water and picks up the ink. The paper rolls across the blanket drum and the image is transferred to the paper. Because the image is first transferred, or offset to the rubber drum, this reproduction method is known as offset lithography or offset printing.
Many innovations and technical refinements have been made in printing processes and presses over the years, including the development of presses with multiple units (each containing one printing plate) that can print multi-color images in one pass on both sides of the sheet, and presses that accommodate continuous rolls (webs) of paper, known as web presses. Another innovation was the continuous dampening system first introduced by Dahlgren. This increased control over the water flow to the plate and allowed for better ink and water balance. Current dampening systems include a "delta effect" which slows the roller in contact with the plate, thus creating a sweeping movement over the ink image to clean impurities known as "hickies".
The advent of desktop publishing made it possible for type and images to be manipulated easily on personal computers for eventual printing on desktop or commercial presses. The development of digital imagesetters enabled print shops to produce negatives for platemaking directly from digital input, skipping the intermediate step of photographing an actual page layout. The development of the digital platesetter in the late twentieth century eliminated film negatives altogether by exposing printing plates directly from digital input, a process known as computer to plate printing.
Microlithography and nanolithography
Microlithography and nanolithography refer specifically to lithographic patterning methods capable of structuring material on a fine scale. Typically features smaller than 10 micrometers are considered microlithographic, and features smaller than 100 nanometers are considered nanolithographic. Photolithography is one of these methods, often applied to semiconductor manufacturing of microchips. Photolithography is also commonly used in fabricating MEMS devices. Photolithography generally uses a pre-fabricated photomask or reticle as a master from which the final pattern is derived.
Although photolithographic technology is the most commercially advanced form of nanolithography, other techniques are also used. Some, for example electron beam lithography, are capable of much higher patterning resolution (sometime as small as a few nanometers). Electron beam lithography is also commercially important, primarily for its use in the manufacture of photomasks. Electron beam lithography as it is usually practiced is a form of maskless lithography, in that no mask is required to generate the final pattern. Instead the final pattern is created directly from a digital representation on a computer, by controlling an electron beam as it scans across a resist-coated substrate.
In addition to these commercially well-established techniques, a large number of promising microlithographic and nanolithographic technologies exist or are emerging, including nanoimprint lithography, interference lithography, X-ray lithography, extreme ultraviolet lithography, and scanning probe lithography. Some of these emerging techniques have been used successfully in small-scale commercial and important research applications.
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