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54-439: In DRIE, the substrate is placed inside a reactor, and several gases are introduced. A plasma is struck in the gas mixture which breaks the gas molecules into ions. The ions are accelerated towards, and react with the surface of the material being etched, forming another gaseous element. This is known as the chemical part of the reactive ion etching. There is also a physical part, if ions have enough energy, they can knock atoms out of

108-406: A glass balance spring. This was much less affected by heat than steel, reducing the compensation required, and also didn't rust. Other trials with glass springs revealed that they were difficult and expensive to make, and they suffered from a widespread perception of fragility, which persisted until the time of fibreglass and fibre-optic materials. Hairsprings made of etched silicon were introduced in

162-431: A large number of branched or ring alkanes that have specific names, e.g., tert-butyl , bornyl , cyclohexyl , etc. There are several functional groups that contain an alkene such as vinyl group , allyl group , or acrylic group . Hydrocarbons may form charged structures: positively charged carbocations or negative carbanions . Carbocations are often named -um . Examples are tropylium and triphenylmethyl cations and

216-446: A large number of very small isotropic etch steps taking place only at the bottom of the etched pits. To etch through a 0.5 mm silicon wafer, for example, 100–1000 etch/deposit steps are needed. The two-phase process causes the sidewalls to undulate with an amplitude of about 100–500 nm . The cycle time can be adjusted: short cycles yield smoother walls, and long cycles yield a higher etch rate. Etching depth typically depends on

270-432: A mainspring, which provides a diminishing drive force as it unwinds. Another cause of varying driving force is friction, which varies as the lubricating oil ages. Early watchmakers empirically found approaches to make their balance springs isochronous. For example, Arnold in 1776 patented a helical (cylindrical) form of the balance spring, in which the ends of the spring were coiled inwards. In 1861 M. Phillips published

324-410: A rise to the second plane in about three spring section heights. The second method is done for aesthetic reasons and is much more difficult to perform. Due to the difficulty with forming an overcoil, modern watches often use a slightly less effective "dogleg", which uses a series of sharp bends (in plane) to place part of the outermost coil out of the way of the rest of the spring. The balance spring and

378-458: A semicircular toothed rack, which was adjusted by fitting a key to a cog and turning it. The modern regulator, a lever pivoted concentrically with the balance wheel, was patented by Joseph Bosley in 1755, but it didn't replace the Tompion regulator until the early 19th century. In order to adjust the rate, the balance spring usually has a regulator . The regulator is a moveable lever mounted on

432-527: A solution to it. Harrison, in the course of his development of the marine chronometer, solved the problem by a "compensation curb" – essentially a bimetallic thermometer which adjusted the effective length of the balance spring as a function of temperature. While this scheme worked well enough to allow Harrison to meet the standards set by the Longitude Act , it was not widely adopted. Around 1765, Pierre Le Roy (son of Julien Le Roy ) invented

486-411: A surface can be etched with a vertical-walled trench 30 times deeper than its width. This has allowed for silicon components to be substituted for some parts which are usually made of steel, such as the hairspring . Silicon is lighter and harder than steel, which carries benefits but makes the manufacturing process more challenging. Functional group In organic chemistry , a functional group

540-456: A theoretical treatment of the problem. He demonstrated that a balance spring whose center of gravity coincides with the axis of the balance wheel is isochronous. In general practice, the most common method of achieving isochronism is through the use of the Breguet overcoil, which places part of the outermost turn of the hairspring in a different plane from the rest of the spring. This allows

594-405: Is 2, 3, or 4), carbyne for methylidyne, and trityl for triphenylmethyl. Hairspring A balance spring , or hairspring , is a spring attached to the balance wheel in mechanical timepieces . It causes the balance wheel to oscillate with a resonant frequency when the timepiece is running, which controls the speed at which the wheels of the timepiece turn, thus the rate of movement of

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648-592: Is a substituent or moiety in a molecule that causes the molecule's characteristic chemical reactions . The same functional group will undergo the same or similar chemical reactions regardless of the rest of the molecule's composition. This enables systematic prediction of chemical reactions and behavior of chemical compounds and the design of chemical synthesis . The reactivity of a functional group can be modified by other functional groups nearby. Functional group interconversion can be used in retrosynthetic analysis to plan organic synthesis . A functional group

702-478: Is a group of atoms in a molecule with distinctive chemical properties , regardless of the other atoms in the molecule. The atoms in a functional group are linked to each other and to the rest of the molecule by covalent bonds . For repeating units of polymers , functional groups attach to their nonpolar core of carbon atoms and thus add chemical character to carbon chains. Functional groups can also be charged , e.g. in carboxylate salts ( −COO ), which turns

756-420: Is an essential adjunct to the balance wheel, causing it to oscillate back and forth. The balance spring and balance wheel together form a harmonic oscillator , which oscillates with a precise period or "beat" resisting external disturbances and is responsible for timekeeping accuracy. The addition of the balance spring to the balance wheel around 1657 by Robert Hooke and Christiaan Huygens greatly increased

810-556: Is preferred over functional class nomenclature (marked as suffix in table) for sulfides, disulfides, sulfoxides and sulfones. Compounds that contain phosphorus exhibit unique chemistry due to the ability of phosphorus to form more bonds than nitrogen, its lighter analogue on the periodic table. Compounds containing boron exhibit unique chemistry due to their having partially filled octets and therefore acting as Lewis acids . methyllithium methylmagnesium chloride trimethylaluminium trimethylsilyl triflate Fluorine

864-429: Is proportional to the angular displacement. When this property is exactly satisfied, the balance spring is said to be isochronous , and the period of oscillation is independent of the amplitude of oscillation. This is an essential property for accurate timekeeping, because no mechanical drive train can provide absolutely constant driving force. This is particularly true in watches and portable clocks which are powered by

918-539: Is that the standard masks on substrates crack under the extreme cold, plus etch by-products have a tendency of depositing on the nearest cold surface, i.e. the substrate or electrode. The Bosch process, named after the German company Robert Bosch GmbH which patented the process, also known as pulsed or time-multiplexed etching, alternates repeatedly between two modes to achieve nearly vertical structures: Each phase lasts for several seconds. The passivation layer protects

972-538: Is the angular acceleration, d 2 θ / d t 2 {\displaystyle d^{2}\theta \,/dt^{2}} . The following differential equation for the motion of the wheel results from rearranging the above equation: d 2 θ d t 2 + κ I θ = 0 {\displaystyle {\frac {d^{2}\theta }{dt^{2}}}+{\frac {\kappa }{I}}\theta =0\,} The solution to this equation of motion for

1026-420: Is too electronegative to be bonded to magnesium; it becomes an ionic salt instead. These names are used to refer to the moieties themselves or to radical species, and also to form the names of halides and substituents in larger molecules. When the parent hydrocarbon is unsaturated, the suffix ("-yl", "-ylidene", or "-ylidyne") replaces "-ane" (e.g. "ethane" becomes "ethyl"); otherwise, the suffix replaces only

1080-402: The cyclopentadienyl anion. Haloalkanes are a class of molecule that is defined by a carbon– halogen bond. This bond can be relatively weak (in the case of an iodoalkane) or quite stable (as in the case of a fluoroalkane). In general, with the exception of fluorinated compounds, haloalkanes readily undergo nucleophilic substitution reactions or elimination reactions . The substitution on

1134-400: The hydroxyl functional group ( −OH ) and hydroxyls interact strongly with each other. Plus, when functional groups are more electronegative than atoms they attach to, the functional groups will become polar, and the otherwise nonpolar molecules containing these functional groups become polar and so become soluble in some aqueous environment. Combining the names of functional groups with

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1188-404: The accuracy of pocketwatches , from perhaps several hours per day to 10 minutes per day, making them useful timekeepers for the first time. The first balance springs had only a few turns. A few early watches had a Barrow regulator, which used a worm drive , but the first widely used regulator was invented by Thomas Tompion around 1680. In the Tompion regulator the curb pins were mounted on

1242-417: The accuracy of portable timepieces, transforming early pocketwatches from expensive novelties to useful timekeepers. Improvements to the balance spring are responsible for further large increases in accuracy since that time. Modern balance springs are made of special low temperature coefficient alloys like nivarox to reduce the effects of temperature changes on the rate, and carefully shaped to minimize

1296-1137: The application: DRIE is distinguished from RIE from its etch depth. Practical etch depths for RIE (as used in IC manufacturing) would be limited to around 10 μm at a rate up to 1 μm/min, while DRIE can etch features much greater, up to 600 μm or more with rates up to 20 μm/min or more in some applications. DRIE of glass requires high plasma power, which makes it difficult to find suitable mask materials for truly deep etching. Polysilicon and nickel are used for 10–50 μm etched depths. In DRIE of polymers, Bosch process with alternating steps of SF 6 etching and C 4 F 8 passivation take place. Metal masks can be used, however they are expensive to use since several additional photo and deposition steps are always required. Metal masks are not necessary however on various substrates (Si [up to 800 μm], InP [up to 40 μm] or glass [up to 12 μm]) if using chemically amplified negative resists. Gallium ion implantation can be used as etch mask in cryo-DRIE. Combined nanofabrication process of focused ion beam and cryo-DRIE

1350-420: The balance cock or bridge, pivoted coaxially with the balance. A narrow slot is formed on one end of the regulator by two downward projecting pins, called curb pins, or by a curb pin and a pin with a heavier section called a boot. The end of the outer turn of the balance spring is fixed in a stud which is secured to the balance cock. The outer turn of the spring then passes through the regulator slot. The portion of

1404-439: The balance is simple harmonic motion ; i.e., a sinusoidal motion of constant period: θ ( t ) = A cos ⁡ ( κ I t ) + B sin ⁡ ( κ I t ) {\displaystyle \theta (t)=A\cos \left({\sqrt {\frac {\kappa }{I}}}t\right)+B\sin \left({\sqrt {\frac {\kappa }{I}}}t\right)\,} Thus,

1458-422: The balance spring. The compensating balance design of Thomas Earnshaw , which consists simply of a balance wheel with bimetallic rim, became the standard solution for temperature compensation. While the compensating balance was effective as a way to compensate for the effect of temperature on the balance spring, it could not provide a complete solution. The basic design suffers from "middle temperature error": if

1512-569: The balance wheel (which is usually referred to as simply the balance ) form a harmonic oscillator . The balance spring provides a restoring torque that limits and reverses the motion of the balance so it oscillates back and forth. Its resonant period makes it resistant to changes from perturbing forces, which is what makes it a good timekeeping device. The stiffness of the spring, its spring coefficient, κ {\displaystyle \kappa \,} in N·m/radian^2, along with

1566-560: The balance wheel's moment of inertia , I {\displaystyle I\,} in kg·m , determines the wheel's oscillation period T {\displaystyle T\,} . The equations of motion for the balance are derived from the angular form of Hooke's law and the angular form of Newton's second law: τ = − κ θ = I α   . {\displaystyle \tau =-\kappa \theta =I\alpha \,\ .} α {\displaystyle \alpha \,}

1620-558: The carbon, the acidity of an adjacent proton, the solvent conditions, etc. all can influence the outcome of the reactivity. Compounds that contain C-O bonds each possess differing reactivity based upon the location and hybridization of the C-O bond, owing to the electron-withdrawing effect of sp-hybridized oxygen (carbonyl groups) and the donating effects of sp -hybridized oxygen (alcohol groups). [REDACTED] Compounds that contain nitrogen in this category may contain C-O bonds, such as in

1674-428: The case of amides . (acetimidamide) alkyl nitrate alkyl nitrite [REDACTED] [REDACTED] [REDACTED] 4-pyridyl (pyridin-4-yl) 3-pyridyl (pyridin-3-yl) 2-pyridyl (pyridin-2-yl) Compounds that contain sulfur exhibit unique chemistry due to sulfur's ability to form more bonds than oxygen, its lighter analogue on the periodic table. Substitutive nomenclature (marked as prefix in table)

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1728-433: The compensation balance, which became the standard approach for temperature compensation in watches and chronometers. In this approach, the shape of the balance is altered, or adjusting weights are moved on the spokes or rim of the balance, by a temperature-sensitive mechanism. This changes the moment of inertia of the balance wheel, and the change is adjusted such that it compensates for the change in modulus of elasticity of

1782-422: The compensation is adjusted to be exact at extremes of temperature, then it will be slightly off at temperatures between those extremes. Various "auxiliary compensation" mechanisms were designed to avoid this, but they all suffer from being complex and hard to adjust. Around 1900, a fundamentally different solution was created by Charles Édouard Guillaume , inventor of elinvar . This is a nickel-steel alloy with

1836-501: The effect of changes in drive force as the mainspring runs down. Before the 1980s, balance wheels and balance springs were used in virtually every portable timekeeping device, but in recent decades electronic quartz timekeeping technology has replaced mechanical clockwork, and the major remaining use of balance springs is in mechanical watches. There is some dispute as to whether it was invented around 1660 by British physicist Robert Hooke or Dutch scientist Christiaan Huygens , with

1890-410: The entire substrate from further chemical attack and prevents further etching. However, during the etching phase, the directional ions that bombard the substrate attack the passivation layer at the bottom of the trench (but not along the sides). They collide with it and sputter it off, exposing the substrate to the chemical etchant. These etch/deposit steps are repeated many times over resulting in

1944-415: The extremities of the balance's arc and bring it to a gentle halt before throwing it back. The watch is accelerated by shortening the arc. This is not a balance spring regulator, being used in the earliest watches before the balance spring was invented. There is also a Barrow regulator, but this is really the earlier of the two principal methods of giving the mainspring "set-up tension"; that required to keep

1998-541: The final "-e" (e.g. " ethyne " becomes " ethynyl "). When used to refer to moieties, multiple single bonds differ from a single multiple bond. For example, a methylene bridge (methanediyl) has two single bonds, whereas a methylidene group (methylidene) has one double bond. Suffixes can be combined, as in methylidyne (triple bond) vs. methylylidene (single bond and double bond) vs. methanetriyl (three double bonds). There are some retained names, such as methylene for methanediyl, 1,x- phenylene for phenyl-1,x-diyl (where x

2052-475: The fusée chain in tension but not enough to actually drive the Watch. Verge watches can be regulated by adjusting the set-up tension, but if any of the previously described regulators is present then this is not usually done. A number of materials have been used for balance springs. Early on, steel was used, but without any hardening or tempering process applied; as a result, these springs would gradually weaken and

2106-418: The gamma-amine in gamma-aminobutyric acid is on the third carbon of the carbon chain attached to the carboxylic acid group. IUPAC conventions call for numeric labeling of the position, e.g. 4-aminobutanoic acid. In traditional names various qualifiers are used to label isomers , for example, isopropanol (IUPAC name: propan-2-ol) is an isomer of n-propanol (propan-1-ol). The term moiety has some overlap with

2160-473: The hairspring coil to expand and contract more evenly and symmetrically as the balance wheel rotates. Two types of overcoils are found – the gradual overcoil and the Z-Bend. The gradual overcoil is obtained by imposing two gradual twists to the hairspring, forming the rise to the second plane over half the circumference. The Z-bend does this by imposing two kinks of complementary 45 degree angles, accomplishing

2214-417: The hands. A regulator lever is often fitted, which can be used to alter the free length of the spring and thereby adjust the rate of the timepiece. The balance spring is a fine spiral or helical torsion spring used in mechanical watches , alarm clocks , kitchen timers , marine chronometers , and other timekeeping mechanisms to control the rate of oscillation of the balance wheel. The balance spring

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2268-427: The late 20th century and are not susceptible to magnetisation. The modulus of elasticity of materials is dependent on temperature. For most materials, this temperature coefficient is large enough that variations in temperature significantly affect the timekeeping of a balance wheel and balance spring. The earliest makers of watches with balance springs, such as Hooke and Huygens, observed this effect without finding

2322-431: The likelihood being that Hooke first had the idea, but Huygens built the first functioning watch that used a balance spring. Before that time, balance wheels or foliots without springs were used in clocks and watches, but they were very sensitive to fluctuations in the driving force, causing the timepiece to slow down as the mainspring unwound. The introduction of the balance spring effected an enormous increase in

2376-576: The material to be etched without chemical reaction. There are two main technologies for high-rate DRIE: cryogenic and Bosch, although the Bosch process is the only recognised production technique. Both Bosch and cryogenic processes can fabricate 90° (truly vertical) walls, but often the walls are slightly tapered, e.g. 88° ("reentrant") or 92° ("retrograde"). Another mechanism is sidewall passivation: SiO x F y functional groups (which originate from sulphur hexafluoride and oxygen etch gases) condense on

2430-449: The molecule into a polyatomic ion or a complex ion . Functional groups binding to a central atom in a coordination complex are called ligands . Complexation and solvation are also caused by specific interactions of functional groups. In the common rule of thumb "like dissolves like", it is the shared or mutually well-interacting functional groups which give rise to solubility . For example, sugar dissolves in water because both share

2484-409: The motion of the spring, causing inaccuracy, so precision timepieces like marine chronometers and some high end watches are free sprung , meaning they don't have a regulator. Instead, their rate is adjusted by timing screws on the balance wheel. There are two principal types of balance spring regulator: There is also a hog's hair or pig's bristle regulator, in which stiff fibres are positioned at

2538-456: The names of the parent alkanes generates what is termed a systematic nomenclature for naming organic compounds . In traditional nomenclature, the first carbon atom after the carbon that attaches to the functional group is called the alpha carbon ; the second, beta carbon, the third, gamma carbon, etc. If there is another functional group at a carbon, it may be named with the Greek letter, e.g.,

2592-404: The property that the modulus of elasticity is essentially unaffected by temperature. A watch fitted with an elinvar balance spring requires either no temperature compensation at all, or very little. This simplifies the mechanism, and it also means that middle temperature error is eliminated as well, or at a minimum is drastically reduced. A balance spring obeys Hooke's Law : the restoring torque

2646-464: The sidewalls, and protect them from lateral etching. As a combination of these processes, deep vertical structures can be made. In cryogenic-DRIE, the wafer is chilled to −110 °C (163 K ). The low temperature slows down the chemical reaction that produces isotropic etching. However, ions continue to bombard upward-facing surfaces and etch them away. This process produces trenches with highly vertical sidewalls. The primary issues with cryo-DRIE

2700-427: The spring between the stud and the slot is held stationary, so the position of the slot controls the free length of the spring. Moving the regulator slides the slot along the outer turn of the spring, changing its effective length. Moving the slot away from the stud shortens the spring, making it stiffer, increasing the balance's oscillation rate, and making the timepiece gain time. The regulator interferes slightly with

2754-407: The symbols R and R' usually denote an attached hydrogen, or a hydrocarbon side chain of any length, but may sometimes refer to any group of atoms. Hydrocarbons are a class of molecule that is defined by functional groups called hydrocarbyls that contain only carbon and hydrogen, but vary in the number and order of double bonds. Each one differs in type (and scope) of reactivity. There are also

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2808-406: The term "functional group". However, a moiety is an entire "half" of a molecule, which can be not only a single functional group, but also a larger unit consisting of multiple functional groups. For example, an "aryl moiety" may be any group containing an aromatic ring , regardless of how many functional groups the said aryl has. The following is a list of common functional groups. In the formulas,

2862-523: The watch would start losing time. Some watchmakers, for example John Arnold , used gold, which avoids the problem of corrosion but retains the problem of gradual weakening. Hardened and tempered steel was first used by John Harrison and subsequently remained the material of choice until the 20th century. In 1833, E. J. Dent (maker of the Great Clock of the Houses of Parliament ) experimented with

2916-430: Was first reported by N Chekurov et al in their article "The fabrication of silicon nanostructures by local gallium implantation and cryogenic deep reactive ion etching". DRIE has enabled the use of silicon mechanical components in high-end wristwatches. According to an engineer at Cartier , “There is no limit to geometric shapes with DRIE,”. With DRIE it is possible to obtain an aspect ratio of 30 or more, meaning that

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