Thank you for visiting nature. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser or turn off compatibility mode in Internet Explorer.
This novel technique produces well-controlled nanopatterns in any desired shape and in a variety of geometric dimensions, over large areas and with a high throughput.
Standard photolithography techniques produce various micropatterns but are limited to a feature size of approximately a micron 1. To overcome this limitation, conventional nanolithography techniques such as electron-beam lithography and focused ion-beam are commonly employed 2.
Often, the standard photolithography and nanolithography techniques are used together to create mixed-scale patterns. The most relevant alternatives for cracking-based patterning appear to partially or individually address the weaknesses and limitations 489 Therefore, a novel technique that can comprehensively and fully address all the weaknesses and overcome the crucial limitations is strongly required for the practical application of crack-based patterns.
Here we describe a cracking-assisted photolithography technique that utilizes a non-crystalized, monolithic and organic material for example, SU-8 photoresist for the first time and relies only on a standard photolithography process. This innovative technique can produce any desired nanopatterns on the surface of a micropatterned photoresist over large areas, with a high throughput, and with no need for any specific nanofabrication techniques and equipment.
Furthermore, the technique allows accurate control of the geometric dimensions of the nanopatterns, thereby resolving the limitations that previous cracking-based techniques were confronted by.
As an example of practical application, we demonstrate a nanofluidic device with 1, pairs of microchambers that are individually interconnected by a crack-assisted nanochannel; it appears to be impossible to produce the same nanofluidic device by using either the conventional or the unconventional fabrication techniques because of throughput and controllability limits, respectively.
Cracking-assisted photolithography for mixed-scale patterning and nanofluidic applications
However, the technique proposed in this work can produce such a complex nanofluidic device in a single batch process with high reproducibility by soft lithography and with positioning of both the microchannels and nanochannels on the same surface, which is essential for a broad range of nanofluidic applications.
Figure 1a shows a schematic diagram of the proposed nanofabrication process. For example, a sharp notch tends to concentrate stresses more effectively than a blunt one, and causes formation of cracks. In general, cracks are initiated when a stiff and thin elastic layer placed on a viscoelastic underlying layer is subjected to tensile stresses higher than its fracture strength 15 This delicate process produced a relatively stiff and elastic layer onto a viscoelastic layer with a cross-linking gradient along the direction normal to the substrate, namely a silicon wafer Fig.
Tensile stresses occur naturally in the elastic layer during the development process, causing the viscoelastic layer to swell Fig.
When the coarsely cross-linked viscoelastic layer absorbs the solvent molecules, it swells isotropically, and consequently, the thin elastic layer above is subjected to an isotropic tensile stress. Once cracking is initiated, it keeps propagating until it reaches a termination structure, whereupon the concentrated stresses are finally released. Thus, a nanoscale crack is successfully created between the initiating notch and the termination structure, as planned during the design stage.
Additional details are provided in Supplementary Note 1. Cracking is initiated and terminated at the previously designed micro-notch structures. The inset is an atomic force microscopy AFM image showing a propagating crack tip.Hoof cracks develop for many reasons. Some are superficial, some are serious, and either can be permanent. Environmental, genetic, nutritional, and conformational factors also play an important role in hoof health and strength.
There are many types of hoof imperfections that involve chipping, tearing, and cracking of the hoof wall. Typically a grass crack is a superficial flaw that starts from the ground and moves upward.
It is usually very thin and does not penetrate deep within the wall. These cracks can occur for many reasons, including ground condition changes specifically, from very wet to dry environmental conditionspoor nutrition malnourishment inhibits hoof growth and lack of exercise as exercise increases healthy blood flow to the hoof. These are very similar to grass cracks; however, they originate from the coronary band and extend downward.
Heel cracks can be very painful. Cracking in the heel region might also result from a shoe that is too long—excessive shoe length creates leverage that applies excessive force to the heel region. Heel cracks might also develop due to uneven heel loading. Bar cracks that appear in the bars the inward folds of the hoof wall, located on either side of the frog also can be painful and are usually caused by trauma e.
Folded or crooked bars tend to be weaker and more prone to cracking. Your horse can overload the toe when he moves, causing these cracks. Also, many horses with heel pain land toe first, causing extreme toe concussion—and, hence, cracking. Hoof Project Foundation head David Hood, PhD, DVM, is studying horses with a prominent crena, or notch, at the distal dorsal aspect the of the distal phalanx the lowest point on the top of the coffin boneto determine whether a weak or absent laminar attachment from the wall to the coffin bone in this area causes toe cracks.
Quarter cracks can be the most aggravating of all hoof cracks to manage. They are usually caused by uneven foot landing, usually due to conformation defects such as carpus valgus outward deviation of the lower limb stemming from the knee, seen as knock knees or varus outward deviation of of the lower limb stemming from the knee, seen as toeing in.
They can also result from many other factors such as neglect hooves can grow too long if not trimmed regularly, causing cracks and splitsimbalance when one side of the coronary band is higher than the othercoffin bone defects e.
Quarter cracks usually appear at the coronary band and grow toward the ground. These types of cracks might bleed or become infected, causing extreme pain. Your veterinarian might need to take radiographs X rays to determine the exact cause of the crack. Radiographs can reveal foreign objects in the hoof wall, coffin bone defects, or coffin bone remodeling that could weaken the wall and create cracks. Hoof abscesses can also cause cracks.
Break-Resistant Dinnerware: How We Tested
If your horse has an abscess and the infection drains from the coronary band, a small horizontal crack called a cleft might appear at the hairline. Usually, these small clefts will grow down the hoof wall with no problems as long as they are kept clean and reasonably dry.The present invention relates to photoimageable epoxy compositions useful as photoresists for applications requiring thick films. In particular, this invention relates to specific compositions useful for that purpose that include at least one solvent, at least one epoxidized bisphenol A formaldehyde novolak resin, at least one polyol reactive diluent and at least one photoacid generator.
Photoimageable coatings are currently used in a wide variety of semiconductor and micromachining applications, where photoimaging is accomplished by exposure to patterned radiation of a coating on a substrate, where the radiation induces a solubility change of the coating in a developer, such that the exposed or unexposed regions can be selectively developed away.Cracking on single-sided printed boards
The photoimageable coating photoresist may be either of the positive or negative type, where exposure to radiation increases or decreases the developer solubility, respectively.
Advanced packaging applications requiring solder bumps having a high aspect ratio defined as the height to width ratio of the imaged featureor applications involving the fabrication of micro electromechanical devices MEMS require photoresists which are capable of producing uniform spin-coated films and high aspect ratio images of greater than one hundred microns thickness. Conventional positive resists based on diazonaphthoquinone-novolak chemistry are not suitable for applications for which the thickness is required to be greater than about 50 microns.
This thickness limitation is caused by the relatively high optical absorption of the diazonaphthoquinone-type DNQ photoactive compound in the near-ultraviolet region of the optical spectrum nm which is typically used to expose the resist. Also, DNQ-type of photoresist possesses limited contrast, or differential solubility, of the exposed vs. Optical absorption necessarily reduces the radiation intensity as it traverses from the top to the bottom of the film, such that if the optical absorption is too high the bottom of the film will be underexposed relative to the top, causing a tapered or otherwise distorted profile of the developed image.
A negative, spin-coated, thick-film photoresist of the chemically amplified type, which has a very low optical absorbance at wavelengths in the nm range has been described in the literature N. LaBianca and J.
SPIE, vol. Suitable photoacid generators based on sulfonium salts are well-known and have been extensively discussed in the literature see for ex.
Crivello et al. The resulting photoresist formulation may be spin-coated onto a wide variety of substrates, pre-baked to evaporate solvent, leaving a solid photoresist coating of one hundred microns or greater thickness which may be photoimaged by exposure to near-ultraviolet radiation through a patterned photomask by contact, proximity, or projection exposure. Subsequent immersion in a developer solution dissolves away the unexposed regions, leaving behind a high resolution, three dimensional, negative image of the photomask.
The high functionality and branching result in efficient crosslinking under the influence of strong acid catalysts, while the high transparency allows uniform irradiation through thick films, making the resist capable of forming images with aspect ratio of greater than at film thicknesses of greater than microns. Newton, Mass. However, no polyol reactive diluents were disclosed.
No polyol reactive diluents were disclosed. Curtain coating, roll coating, and wound wire rod coating were used. The hydroxyl-containing additive is reported to increase flexibility and decrease shrinkage for coatings of up to microns thickness.Effective date : Photoresist is quickly removed from a wafer using a process liquid including water, ozone and a photoresist penetrating additive, such as ammonium hydroxide. The penetrating additive creates cracks in the photoresist layer.
The process liquid moves through the cracks and etches away the underlying adhesion layer. The photoresist layer is then released from the wafer. Pieces or particles of the photoresist are lifted off of the workpiece and carried away in a flow of the liquid.
This Application is a Continuation-in-Part of U. Patent Application No. Patent Application Nos. This Application is also a Continuation-in-Part of U. Each of the applications listed above is incorporated herein by reference.
Semiconductor devices are the basic building blocks of most electronic products. They are widely used in an ever expanding array of products. Semiconductor devices are generally manufactured on a microscopic scale on semiconductor material wafers, or other substrates, via photoithography.
This process involves multiple etching, metal or chemical deposition, and chemical treatment steps. In a typical lithography procedure for manufactureing a microelectronic device, a layer of conductive metal several nanometers thick is deposited onto the substrate. A layer of photoresist is applied on top of the metal layer. Photoresist is typically a liquid chemical that hardens when exposed to UV light. The photoresist is selectively hardened by illuminating it at specific locations with UV light passing through a patterned mask.
The photoresist not exposed to UV light is not hardened and is etched away along with the metal under it in a susequent chemical process step. Additional plating and etching steps may follow. The hardened photoresist is eventually etched away in a later process step.
This leaves a metal layer on the substrate in the same pattern as the mask although on a microscopic scale. In addition to manufacturing microelectronic and semiconductor devices, photoresist is also used in generally similar ways in biomedical engineering, holographic, and nano-technology devices.
Novalak resin types of photoresist also referred to as nm photoresists have been used for many years. These types of photoresist after hardening via ultraviolet light with a nm wavelength were conventionally removed using large quantities of etching chemicals, such as acids, in multiple step immersion processes. While successful in removing the hardened photoresist, these immersion processes were time consuming, expensive, subject to variable results, and generated large amounts of chemical waste.
In a technological breakthrough made several years ago, the present inventor developed a vastly improved technique for removing photoresist. The Hydrozone process has since met with widespread commercial success, public acclaim, and has been frequently emulated by others.
The Hydrozone process is also the subject of several pioneering patents, including U. The Hydrozone process is extremely effective in removing nm photoresists.
The molecular structure of these types of photoresists typically has double bonds. It is generally believed that these double bonds serve as primary attack sites for the ozone to initiate bond cleavage and the breakdown of the photoresist polymer chain. In recent years, newer photoresists, known as nm photoresists, have become more common in the semiconductor and related industries, to better meet the manufacturing needs of making ever smaller devices.
These nm photoresists use a different base resin, typically called methacrylate or polymethacrylate resin, which does not have a double bond structure. Unlike the nm photoresists, the nm photoresists are not easily removed using the water and ozone processes.Get Directions.
Bubbles caused from a loss of adhesion and lifting of the paint film from the underlying surface. Thin, long, and relatively straight cracks that form in the paint film, usually in the direction of the plywood grain. Thin, long, relatively straight cracks running in a singular direction on a previously stained wood surface. This item has been successfully added to your list.
Epoxy photoresist composition with improved cracking resistance
Your Sherwin-Williams Update Location. Click the link below and get directions to your closest Sherwin-Williams store. Choose Color with Confidence. View Color Selection Tools. It's Free and Simple! Store Locator. Find Your Sherwin-Williams. Peeling, Cracking Failure of coating to properly adhere to surface.
Patterned cracking in the paint film resembling the scales of an alligator. Adhesion Blocking. Undesirable adhesion between two painted surfaces or between paint and weather stripping. The splitting of a dry paint film through at least one coat. Caulk Failure. Caulk - Paint Cracking or Crawling. Paint lifting from the underlying surface in the form of flakes.During these challenging times, we guarantee we will work tirelessly to support you. We will continue to give you accurate and timely information throughout the crisis, and we will deliver on our mission — to help everyone in the world learn how to do anything — no matter what.
Thank you to our community and to all of our readers who are working to aid others in this time of crisis, and to all of those who are making personal sacrifices for the good of their communities. We will get through this together. Neck cracking, much like chronic knuckle cracking, is a relatively common habit among Americans.
Although there is no definitive proof that cracking cavitating the spinal joints of your own neck is dangerous or likely to cause significant damage, common sense dictates that doing it numerous times per day is not beneficial either. For some people, constantly trying to crack their neck has turned into a compulsive tic, which may have negative social implications. With some willpower and basic understanding of what activities may be creating issues in your neck, learning to stop cracking it is possible.
Stretching is a good exercise to loosen and relax the neck to reduce your neck cracking habits. To stop cracking your neck, start by gently stretching your neck muscles times a day, since stretching can reduce some of the tension and discomfort that makes you want to crack your neck. Additionally, move your neck up and down, side to side, and in circles to loosen your joints.
You should also avoid sleeping on your stomach, which can cause your head and neck to twist in uncomfortable ways.
Instead, try sleeping on your side with your knees slightly bent and your arms below the level of your head and hips. For information from our Medical co-author about how to get help from a chiropractor or osteopath, read on!
Did this summary help you?
Article Edit. Learn why people trust wikiHow. Co-authored by Chris M. Matsko, MD Updated: October 24, This article was co-authored by Chris M.
Matsko, MD. Matsko is a retired Physician based in Pittsburgh, Pennsylvania. He received his M. There are 10 references cited in this article, which can be found at the bottom of the page.
Troubleshooting Your Environment. Getting Your Neck Treated. Tips and Warnings.The new, must-have addition to any hostess' arsenal is break-resistant dinnerware. It's less expensive and more durable than traditional porcelain pieces, so you won't have to take out a small loan every time a guest accidentally drops a stack of soup bowls.
And unlike paper plates, these sturdy pieces are reusable, which dramatically cuts down on waste. To help you avoid buying dishes that are prone to chipping, scratching, breaking, or staining, the Good Housekeeping Research Institute GHRI tested 29 lines of break-resistant dinnerware. To determine which break-resistant dinnerware is best for you, consider the following:. Material: Most break-resistant dinnerware is made from melamine a type of plasticbut Corelle dinnerware is made from tempered glass, which also offers the advantage of being chip- and scratch-resistant, as well as microwave safe.
Melamine isn't microwave safe, but plates made from melamine are generally lighter in weight and less likely to break if dropped on a very hard surface like slate or brick. Weight: Heavy plates may feel like they're high quality, but they're actually no more durable than their lightweight counterparts.
In fact, in our tests, heavier plates were even more likely to break when dropped. When shopping, choose a weight that you feel comfortable carrying. Decide What You Need: It may be tempting to buy a full set, but you might be getting more than you really need. While large sets of dinnerware tend to offer a better value per piece, you should decide in advance whether you really need matching bowls or salad plates.
Breakage: Remember that the dinnerware is break-resistant, not unbreakable. Over time it's likely that at least one piece will break. If you fall in love with a certain pattern, consider buying extra pieces.
Designs change seasonally, and you may not be able to get a replacement next summer. Product Reviews. Type keyword s to search. Today's Top Stories. Best Skincare Products of How to Clean Germy Toys. Advertisement - Continue Reading Below. More From Break-Resistant Dinnerware.