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本帖最后由 doghog 于 2010-8-19 17:20 编辑 " D8 V" o! f, C4 @& f
. ]% K N* A/ R/ `真空镀膜技术及其应用
( ~5 J* H' L& HApplication of vacuum technology for coating techniques
$ g1 c$ U5 l- d! F0 {4 z8 `% i- |; eApplication of vacuum technology for coating techniques 1.1 Vacuum coating technique" p8 w! i: ^: W( S& f- ?3 u; x; \
Vacuum technology has been increasingly used in industrial production processes during the last two decades. Some of these processes and their typical working pressure ranges are shown in Fig. 7.1.
8 ~$ W* e8 s0 M' W# F7 NSince a discussion of all processes is beyond the scope of this brochure, this section will be restricted to a discussion of several examples of applications in the important field of coating technology.
4 K, k, y8 E# D" v9 GDeposition of thin films is used to change the surface properties of the base material, the substrate. For example, optical properties such as transmission or reflection of lenses and other glass products can be adjusted by applying suitable coating layer systems. Metal coatings on plastic web produce conductive coatings for film capacitors. Polymer layers on metals enhance the corrosion resistance of the substrate. Through the use of vacuum it is possible to create coatings with a high degree of uniform thickness ranging from several nanometers to more than 100 mm while still achieving very good reproducibility of the coating properties. Flat substrates, web and strip, as well as complex molded-plastic parts can be coated with virtually no restrictions as to the substrate material. For example, metals, alloys, glass, ceramics, plastics and paper can be coated. The variety of coating materials is also very large. In addition to metal and alloy coatings, layers may be produced from various chemical compounds or layers of different materials applied in sandwich form. A significant advantage of vacuum coating over other methods is that many special coating properties desired, such as structure, hardness, electrical conductivity or refractive index, are obtained merely by selecting a specific coating method and the process parameters for a certain coating material.
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1.2 Coating sources" q8 {3 A$ x: N: }0 v9 ]; f
In all vacuum coating methods layers are formed by deposition of material from the gas phase. The coating material may be formed by physical processes such as evaporation and sputtering, or by chemical reaction. Therefore, a distinction is made between physical and chemical vapor deposition:& w& ~. I5 j; M
·physical vapor deposition = PVD( H' }8 ~% y7 a: B, D1 ] h
·chemical vapor deposition = CVD.7 {+ [' e& _- @' f! j; k# I
1.2.1 Thermal evaporators (boats, wires etc.)
' {+ j( D; S, G$ G- M1 M% b, }+ mIn the evaporation process the material to be deposited is heated to a temperature high enough to reach a sufficiently high vapor pressure and the desired evaporation or condensation rate is set. The simplest sources used in evaporation consist of wire filaments, boats of sheet metal or electrically conductive ceramics that are heated by passing an electrical current through them (Fig. 7.2). However, there are restrictions regarding the type of material to be heated. In some cases it is not possible to achieve the necessary evaporator temperatures without significantly evaporating the source holder and thus contaminating the coating. Furthermore chemical reactions between the holder and the material to be evaporated can occur resulting in either a reduction of the lifetime of the evaporator or contamination of the coating.5 I+ e5 g( X9 g8 l) ?' e2 ^, w6 r+ _
1.2.2 Electron beam evaporators (electron guns)
& W/ f/ [ q$ }+ [; o- G+ P# JTo evaporate coating material using an electron beam gun, the material, which is kept in a water-cooled crucible, is bombarded by a focused electron beam and thereby heated. Since the crucible remains cold, in principle, contamination of the coating by crucible material is avoided and a high degree of coating purity is achieved. With the focused electron beam, very high temperatures of the material to be evaporated can be obtained and thus very high evaporation rates. Consequently, high-melting point compounds such as oxides can be evaporated in addition to metals and alloys. By changing the power of the electron beam the evaporation rate is easily and rapidly controlled.
& x, [: Y7 R$ ~6 T+ l ?! ?9 ^1.2.3 Cathode sputtering
], u: a% r& J. N' D/ EIn the cathode sputtering process, the target, a solid, is bombarded with high energy ions in a gas discharge (Fig. 7.3). The impinging ions transfer their momentum to the atoms in the target material, knocking them off. These displaced atoms – the sputtered particles – condense on the substrate facing the target. Compared to evaporated particles, sputtered particles have considerably higher kinetic energy. Therefore, the conditions for condensation and layer growth are very different in the two processes. Sputtered layers usually have higher adhesive strength and a denser coating structure than evaporated ones. Sputter cathodes are available in many different geometric shapes and sizes as well as electrical circuits configurations. What all sputter cathodes have in common is a large particle source area compared to evaporators and the capability to coat large substrates with a high degree of uniformity. In this type of process metals, alloys of any composition as well as oxides can be used as coating materials.
; F3 X- D+ R8 L# m3 Q& n1.2.4 Chemical vapor deposition
* T2 M8 v; t9 ^! \In contrast to PVD methods, where the substance to be deposited is either solid or liquid, in chemical vapor deposition the substance is already in the vapor phase when admitted to the vacuum system. To deposit it, the substance must be thermally excited, i.e. by means of appropriate high temperatures or with plasma. Generally, in this type of process, a large number of chemical reactions take place, some of which are taken advantage of to control the desired composition and properties of the coating. For example, using silicon-hydrogen monomers, soft Si-H polymer coatings, hard silicon coatings or – by addition of oxygen – quartz coatings can be created by controlling process parameters.$ K/ d7 ?' l7 l$ t! o' L
1.3 Vacuum coating technology/coating systems. f+ \8 ]' x5 @6 _
1.3.1 Coating of parts2 ]$ f) \1 |) v5 U. w
For molded-plastic parts, vacuum coating techniques are increasingly replacing conventional coating methods, such as electroplating. For example, using vacuum coating methods, automobile reflectors obtain a mirror-like surface, plastic articles in the furniture, decoration, clock and watch as well as electronics industry are metal-coated and optical effects are created on articles in the decoration industry.
' ~- m2 n0 n. f0 T1 y& `5 P4 i/ p2 V$ BFig. 7.4 shows a type of vacuum system in which large batches of molded-plastic parts can be coated simultaneously. The substrates are placed on a cage that rotates past the coating source, a sputter cathode in this example. In some applications, by using a glow discharge treatment, the substrates are cleaned and the surface is activated prior to the coating process. This enhances the adhesive strength and reproducibility of the coating properties. A corrosion protection coating can be applied after sputtering. In this case, a monomer vapor is admitted into the system and a high-frequency plasma discharge ignited. The monomer is actived in the plasma and deposits on the substrates as a polymer coating. In this type of system there may be plastic substrates with a surface area of several 10 m2 on the cage, causing a correspondingly high desorption gas flow. The vacuum system must be able to attain the required pressures reliably despite these high gas loads. In the example shown, the system is evacuated with a combination of a backing and Roots pump. A diffusion pump along with a cold surface forms the high vacuum pump system. The cold surfaces pump a large portion of the vapor and volatile substances emitted by the plastic parts while the diffusion pump basically removes the non-condensable gases as well as the noble gas required for the sputter process.
. `- s! a+ X# l2 w+ ~A completely different concept for the same process steps is shown in Fig. 7.5. The system consists of four separate stations made up of a drum rotating around the vertical axis with four substrate chambers and process stations mounted in the vacuum chamber. During rotation, a substrate chamber moves from the loading and unloading station to the pretreatment station, to the metallization station, to the protective coating station and then back to the initial position. Since each station has its own pumping system, all four processes can run simultaneously with entirely independent adjustable process parameters. The vacuum system comprises of turbo molecular pumps and backing pump sets consisting of Roots and rotary vane pumps.% K8 t/ O$ t9 K1 C# \
/ H4 R" Q6 f) a0 a$ u9 S1.3.2 Web coating
# ^ t+ S6 F5 P9 ]0 p2 X2 ` [8 BMetal-coated plastic webs and papers play an important role in food packaging. They preserve food longer according to storage and transport logistics requirements and give packaging an attractive appearance. Another important area of application of metal-coated web is the production of film capacitors for electrical and electronics applications. Metal-coating is carried out in vacuum web coating systems. Fig. 7.6 shows a typical scheme. The unit consists of two chambers, the winding chamber with the roll of web to be coated and the winding system, as well as the coating chamber, where the evaporators are located. The two chambers are sealed from each other, except for two slits through which the web runs. This makes it possible to pump high gas loads from the web roll using a relatively small pumping set. The pressure in the winding chamber may be more than a factor of 100 higher than the pressure simultaneously established in the coating chamber. The pump set for the winding chamber usually consists of a combination of Roots and rotary vane pumps.% n; I3 n% n4 k
With strongly degassing rolls of paper, it may be necessary to install a cold surface in the winding chamber to act as a water vapor pump. The rolls of the plastic web or paper typically have diameters between 400 and 1000 mm and a width of 400 to 3000 mm. A precise, electronically controlled winding system is required for winding and unwinding as well as web guidance." b" Y- X9 U4 g
During the coating process the web, at a speed of more than 10 m/s, passes a group of evaporators consisting of ceramic boats, from which aluminum is evaporated. To achieve the necessary Al-coating thickness at these high web speeds, very high evaporation rates are required. The evaporators must be run at temperatures in excess of 1400 °C. The thermal radiation of the evaporators, together with the heat of condensation of the growing layer, yields a considerable thermal load for the web. With the help of cooled rollers, the foil is cooled during and after coating so that it is not damaged during coating and has cooled down sufficiently prior to winding.
0 w7 P" I. [* XDuring the entire coating process the coating thickness is continuously monitored with an optical measuring system or by means of electrical resistance measurement devices. The measured values are compared with the coating thickness set points in the system and the evaporator power is thus automatically controlled.
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0 y' ]6 v8 {5 R8 f7 H1.3.3 Optical coatings
x% i, v& ]& Q- O: R) g6 uVacuum coatings have a broad range of applications in production of ophthalmic optics, lenses for cameras and other optical instruments as well as a wide variety of optical filters and special mirrors. To obtain the desired transmission or reflection properties, at least three, but sometimes up to 50 coatings are applied to the glass or plastic substrates. The coating properties, such as thickness and refractive index of the individual coatings, must be controlled very precisely and matched to each other. Most of these coatings are produced using electron beam evaporators in single-chamber units (Fig. 7.7). The evaporators are installed at the bottom of the chamber, usually with automatically operated crucibles, in which there are several different materials. The substrates are mounted on a rotating collect above the evaporators. Application of suitable shielding combined with relative movement between evaporators and substrates, results in a very high degree of coating uniformity. With the help of quartz coating thickness monitors (see Section 6) and direct measurement of the attained optical properties of the coating system during coating, the coating process is fully controlled automatically.
- Q! C9 d! ` m4 [, EOne of the key requirements of coatings is that they retain their properties under usual ambient conditions over long periods of time. This requires to produce the densest coatings possible, into which neither oxygen nor water can penetrate. Using glass lenses, this is achieved by keeping the substrates at temperatures up to 300 °C during coating by means of radiation heaters. However, plastic lenses, as those used in eyeglass optics, are not allowed to be heated above 80 °C. To obtain dense, stable coatings these substrates are bombarded with Ar ions from an ion source during coating. Through the ion bombardment the right amount of energy is applied to the growing layer so that the coated particles are arranged on the energetically most favorable lattice sites, without the substrate temperature reaching unacceptably high values. At the same time oxygen can be added to the argon. The resulting oxygen ions are very reactive and ensure that the oxygen is included in the growing layer as desired.
* b7 f: F& U# |; W% K, dThe vacuum system of such a coating unit usually consists of a backing pump set comprising a rotary vane pump and Roots pump as well as a high vacuum pumping system. Depending on the requirements, diffusion pumps, cryo pumps or turbo molecular pumps are used here, in most cases in connection with large refrigerator-cooled cold surfaces. The pumps must be installed and protected by shielding in a way that no coating material can enter the pumps and the heaters in the system do not thermally overload them. Since shielding always reduces the effective pumping speed, the system manufacturer must find a suitable compromise between shielding effect and reduction of pumping speed.. a* K$ l F! L2 A' u
1.3.4 Glass coating, o! R w$ l5 m3 d- c. I3 ^
Coated glass plays a major role in a number of applications: window panes in moderate and cold climate zones are provided with heat-reflecting coating systems to lower heating costs; in countries with high intensity solar radiation, solar protection coatings are used that reduce air conditioning costs; coated car windows reduce the heating-up of the interior and mirrors are used both in the furniture and the automobile industry. Most of these coatings are produced in large in-line vacuum systems. Fig. 7.8 shows a typical system. The individual glass panes are transported into a entrance chamber at atmospheric pressure. After the entrance valve is closed, the chamber is evacuated with a fore pump set. As soon as the pressure is low enough, the valve to the evacuated transfer chamber can be opened. The glass pane is moved into the transfer chamber and from there at constant speed to the process chambers, where coating is carried out by means of sputter cathodes. On the exit side there is, in analogy to the entrance side, a transfer chamber in which the pane is parked until it can be transferred out through the exit chamber.
) t% h% B% a! {) {" c0 C" m" s' uMost of the coatings consist of a stack of alternative layers of metal and oxide. Since the metal layers may not be contaminated with oxygen, the individual process stations have to be vacuum-isolated from each other and from the transfer stations. Utilization of valves for separating process chambers is unsatisfactory because it increases plant dimensions. To avoid frequent and undesirable starting and stopping of the glass panes, the process chambers are vacuum-separated through so-called “slit locks”, i.e. constantly open slits combined with an intermediate chamber with its own vacuum pump. The gaps in the slits are kept as small as technically possible to minimize clearance and therefore conductance as the glass panes are transported through them. The pumping speed at the intermediate chamber is kept as high as possible in order to achieve a considerably lower pressure in the intermediate chamber as in the process chambers. This lower pressure greatly reduces the gas flow from a process chamber via the intermediate chamber to the adjacent process chamber. For very stringent separation requirements it may be necessary to place several intermediate chambers between two process chambers., q, k; m3 L: D+ p: u
The glass coating process requires high gas flows for the sputter processes as well as low hydrocarbon concentration. The only vacuum pump which satisfies these requirements as well as high pumping speed stability over time is turbo-molecular pumps which are used almost exclusively.
* C6 ]8 v6 Q" k: sWhile the transfer and process chambers are constantly evacuated, the entrance and exit chambers must be periodically vented and then evacuated again. Due to the large volumes of these chambers and the short cycle times, a high pumping speed is required. It is provided by combinations of rotary vane pumps and Roots pumps. For particularly short cycle times gas cooled Roots pumps are also used.
5 q1 X6 j( H- C$ L; b6 iAll major functions of a plant, such as glass transport, control of the sputter processes and pump control, are carried out fully automatically. This is the only way to ensure high productivity along with high product quality.+ m. |: Q& _& e9 x8 y/ }( R
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0 V0 U8 g7 O; E4 C+ t1.1真空镀膜技术
( j# K- S& H/ s6 Z0 j7 z2 i在过去的20年,真空技术已越来越多的应用于工业生产过程。图1.1是一些典型的生产过程和它们的工作压力范围。; h5 n( T& G' F& {9 P$ j
j6 x4 f# M) ?: P& }由于对所有生产过程的讨论超出了本书的范围,本书将着重介绍几个在镀膜技术在一些重要领域应用的例子。) i- e) V, ^+ D8 l& n ^$ [
薄膜沉积是用来改变基材表面性质,底物。举例来说,如传输或镜头及其他玻璃制品反射光学性能,可以采用适当的调整涂层系统。塑料网金属涂层薄膜电容器生产导电涂料。对金属层增强聚合物基体的耐蚀性。通过真空用它可以创建一个统一的,从几纳米到100毫米以上,同时还实现了非常良好的涂层性能的高度重复性涂层厚度。平面基板,网络及带,以及复杂的注塑塑料零件,可几乎没有限制的基体材料涂层。例如,金属,合金,玻璃,陶瓷,塑料和纸张都可涂。涂层材料的品种也非常大,除了金属和合金涂层,也可以是不同的化学化合物或三明治的形式应用在不同的材料。真空镀膜和其它方法相比的显著优势在于,许多特殊的涂层需要,如结构,硬度,电导率或折射率等参数,从而选择一个特定的涂层方法和某一特定涂层材料的工艺参数。
- m6 M6 O% Z" R8 A1.2涂层来源' u( u, L/ j0 Y* t2 d3 O
在所有的真空镀膜方法中,层是由物质的气相沉积形成的。该涂层材料可由物理过程形成,如蒸发,溅射,或通过化学反应。因此,可以分为物理和化学气相沉积:
" a4 }6 S1 h" U- v+ M; a物理气相沉积=PVD& h6 m( ~& M7 g3 q1 i8 s7 G, w0 X5 Z
化学气相沉积=CVD
, ], r8 Y$ w, Z. h1.2.1热蒸发器(金属板、导线等)
' x7 v' v* \$ H1 P, Q9 g+ x: \在蒸发过程中,材料加热到足够高的温度,达到足够高的蒸汽压力和期望的蒸发或冷凝率。用最简单的蒸发来源包括线丝,金属板或导电陶瓷,电流通过它们从而起到加热的作用(图1.2)。但是,有些类型的材料在加热时是有限制的。在某些情况下是不可能达到蒸发所需的温度,从而污染涂层。蒸发器和涂层材料之间的化学反应会减少蒸发器的寿命或污染涂层。
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% h: q4 ^. I4 i/ M* J+ W) {( \) W4 \1.2.2电子束蒸发器(电子枪)& ^! Z- P$ e2 Y0 s) Z
蒸发镀膜材料使用电子束枪将电子束聚焦不断轰炸放在水冷坩埚里的材料,不断加热。由于坩埚处于低温,原则上由坩埚涂层产生的污染是可以避免的,高纯度的涂层是可以获得的。随着电子束聚焦,材料是在非常高的温度下蒸发,从而可以得到很高的蒸发率。因此,高熔点化合物如氧化物,除了金属和合金,都可以蒸发。通过改变电子束功率,蒸发速度很容易和迅速控制的。
0 o. f" x$ }% r1.2.3阴极溅射( q$ X- U, m3 i+ `
在阴极溅射过程中,由一种气体放电产生高能量离子,轰击目标固体(图1.3)。冲击离子转移动量到目标物质的原子,敲击走原子。这些敲走的原子—溅射粒子—在目标基板凝结。相对于蒸发颗粒,溅射粒子有相当高的动能。因此,冷凝层生长的条件是完全不同的两个过程。溅射层通常比蒸发涂层具有较高的粘接强度和涂层结构密度。溅射阴极可以有许多不同的几何形状和尺寸以及配置电路。阴极溅射和蒸发器的共同点是大颗粒物源,和蒸发相比,阴极溅射涂层具有高度的统一性。在这个过程中金属,合金以及任何组成的氧化物型可作为涂层材料。
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1.2.4化学气相沉积6 C; P' `2 r" B" ~( l" A
与物理气相沉积的方法相反,物质在固体或液体的化学蒸汽中,沉积物在气相时已经进入了真空系统。进入的物质必须是热激发,即通过适当的高温等离子体或手段。一般来说,在这种过程,有大量发生化学反应,其中有些是采取了控制所需的组成及涂层性能。例如,利用硅氢单体,软Si- H的聚合物涂层,硬硅涂层,石英涂层(除了有氧),可通过控制工艺参数创建。
7 T5 [- t, l& c; w( t ]; Y6 j1.3真空镀膜技术/涂层系统
/ L: [" H6 K6 c: k% u6 t1.3.1涂层设备
, j# K5 e j" p- Z) f. s4 N+ Z, ]模塑塑料件,真空镀膜技术被越来越多地取代传统的涂层,如电镀方法。例如,使用真空镀膜的方法,汽车反光取得镜子一样的表面,在家具,装饰,时钟塑胶制品和手表以及电子行业的金属涂层和光的文章中创建装饰行业的影响。
* R; X8 W h3 k4 H图1.4为一个真空系统,其中模塑塑料件为大批量,涂层是同类类型。在基板上的笼子里旋转涂层源放在过去,在这个例子中是一个溅射阴极。在某些应用中,通过使用一个辉光放电处理,在涂层过程之前清洗基板和涂层表面。这提高了粘接强度和涂层性能的重复性。阿防腐涂料可应用于溅射后。在这种情况下,单体蒸汽进入到系统中,高频等离子体放电点燃。这提高了粘接强度和涂层性能的重复性。防腐涂料可应用于溅射后。在这种情况下,单体蒸汽进入到系统中,高频等离子体放电点燃。真空系统必须能够可靠地达到所需的压力,尽管这些高瓦斯负载。在所示的例子中,该系统是由罗茨泵组合起来的。扩散泵冷的表面形成高真空泵系统。一个冷的表面的蒸气泵和塑料零件的挥发性有机物排放很大一部分,而扩散泵,基本上消除了非凝性气体,以及惰性气体对溅射过程的所需。7 N+ h# p, B. e$ `
同一过程中的一个步骤,是完全不同的概念,如图1.5所示,该系统包括了4个分开的部分,组成一个圆筒绕垂直轴旋转,在真空室安装了4个独立的腔室。在旋转过程中,从进料和卸料,到预处理部分,到镀金部分,到涂层保护部分,然后回到初始位置。由于每个站都有自己的抽气系统,所有四个流程可以完全独立运行,同时调整工艺参数。该套系统包括真空罗茨泵和旋转叶片组成的涡轮分子泵和支持泵。
3 Q3 K5 Y6 S0 d/ k% F; F1.3.2卷绕镀膜 F& _0 C+ |; _+ O, H9 n
金属涂层塑料网和包装纸在食品包装中发挥着重要作用。再根据保存食物储存和运输物流的要求,给一个有吸引力的包装外观。另一种金属涂层网的重要领域是薄膜电容器的电气和电子应用产品。金属涂层在真空卷绕镀膜系统中生成。图1.6显示了一个典型的流程。该装置由两个腔室组成,抽气室和卷绕室,蒸发装置在涂层室。两个腔室相互密封,除了两个狭缝。这使得通过一个相对较小的抽气泵组获得较大的抽气量称为可能。在弯曲的抽气室中的压力可能比涂层室的压力大100倍,抽气室的泵通常是由罗茨泵和旋转叶片泵组合而成。! S( _) X9 h' p: e4 {1 z- J" ]! B
随着强烈脱气的纸卷,它可能需要安装在一个冷的表面,抽气室充当水汽泵。塑料网或纸辊筒通常有400至1000毫米,宽直径400至3000毫米。精确的电子控制系统所必需的绕组线圈和平仓,以及网络的指导。9 t( D/ [+ N2 q5 G" m! l, y
在涂层过程中,在超过10m/s的速度传递由导电陶瓷组成的蒸发器,从中铝被蒸发。为了实现这样高速度的必要铝涂层厚度,蒸发率有非常高的要求。该蒸发器必须运行在1400℃以上的温度。该蒸发器的热辐射,随着涂层增长凝聚的热,产生了相当大的热负荷。在冷却辊的帮助下,涂层冷却期间和之后,以便涂层不会损坏,并在曲折前已充分冷却。
- P; a8 P% Q8 Q8 E在整个过程中,涂层厚度涂层不断用光学测量系统或电阻测量装置进行监测。所测的数值与涂层厚度在系统中设置比较点,因此蒸发器功率自动控制。! F( r" i! P' i. `7 u' i
1.3.3光学薄膜4 M8 q. K$ }) ^. k; e
真空涂层有在眼科光学生产应用范围广泛,相机和其他光学仪器镜头以及光学过滤器和各种特殊的镜子。为了获得所需的传输或反射特性,至少有三个,但有时高达50个涂层适用于玻璃或塑料基板。该涂层性能,如厚度和折射率,个别涂层必须非常精确地控制,并能满足对方。这些涂层大部分是利用单电子束蒸发室产生(图1.7)。该蒸发器安装在室底部通常与坩埚自动操作,其中有几种不同的材料。基板安装在一个旋转蒸发器收集上面。应用合适的方法,屏蔽蒸发器和基板,在相对运动情况下产生均匀性非常高的涂层。在涂层厚度的石英监视器的监视下(见第6节),涂层系统实现光学特性直接测量,涂层过程是完全自动进行控制。
; l& z, d; [1 R5 v) F7 l- S对涂层的关键要求之一是,在一般环境先涂层的性能可以保持很长一段时间。这就要求生产最密集的涂层,不能让氧气或水渗透。使用玻璃镜片,这是通过保持在涂层过程中温度高达300℃的辐射加热。不过,塑料镜片,光学眼镜,不得在高于80℃的条件下加热。为了获得致密,稳定的涂层这些基板轰击氩离子从离子源在涂层。通过离子轰击的能量应用到越来越多的包覆层,使粒子安排在最有利的格点,但无衬底的温度不能超过限制的温度。同时可以增加氧气到氩气中。由此产生的氧离子是非常被动的,而且保证氧气在增加的涂层中是需要的。 Y0 p6 `; E; `: `4 T* E& v: P
这种涂层机组真空系统通常是由水泵机组的支持,包括一个旋转叶片泵,罗茨泵,以及一个高真空抽水系统。根据不同的要求,扩散泵,低温泵或涡轮分子泵用在这里是在大多数情况下,在大冰箱冷却冷表面连接。该泵必须安装并在一个没有涂层材料可进入泵和系统中的加热器不热超载屏蔽保护。由于屏蔽泵始终有效降低了速度,系统制造商必须协调屏蔽效果及抽水减速之间的矛盾。
0 H3 [8 g4 n+ R* R9 C1.3.4玻璃涂层# @) ~* Y. i& q* O6 g6 x
镀膜玻璃在实际中有很多重要的应用:在寒冷气候和温和气候地带玻璃窗与热反射膜保暖系统,以降低成本提供;在高强度的国家太阳辐射,太阳防护涂层可以减少使用空调费用;涂层车窗减少内部和镜子升温,用于家具和汽车这两个行业。这些涂层大多分布在大型在线真空系统。图1.8显示了一个典型的系统。单独玻璃板运到一个大气压的压力室入口处。经过入口阀门关闭,经过入口阀门关闭,腔室是一个疏散水泵机组。当压力足够低,对疏散转移腔阀可以打开。玻璃面板是迁入室和转移的速度在不断从那里向腔室的过程,在涂层是由手段进行溅射阴极。出口处和进口处相似,到门口边,一个传输室中的窗玻璃停转,直到它可以通过出口室出来。; e! K& U4 a, d
& I* n5 L$ ]) G* u! Z图1.8 三腔室玻璃面板镀膜系统,年产量3,600,000m2/年 该涂料大部分组成一叠替代金属的氧化物层。由于金属层可能被氧污染,个别工作部位,必须从彼此的转运站真空隔离。阀门的有效利用分离腔室并不理想,因为它增加了尺寸。为了避免频繁和启动和停止玻璃板,腔室的过程是通过所谓的真空分离的“缝锁”,即与它自己的真空泵中间不断开缝与合并。在狭缝的差距不断的在技术上以尽量减少通关,因此作为玻璃板导正通过他们的小运。在中间腔抽水速度尽可能高,以实现该腔室在这个过程中间腔压力大大降低。这个较低的压力大大减少通过中间腔室,以毗邻的过程,从一室气体流动的过程。对于非常严格分离的规定可能有必要将两个腔室中间放几个中间级腔室。* j+ P8 r7 v' Z+ c; o4 J) {
玻璃涂层工艺要求高的溅射气体流动过程以及碳氢化合物的浓度低。唯一的真空泵,满足这些要求,以及高抽速稳定一段时间是涡轮分子泵。% v) a2 [' K% q) f. [" A* w( N& m' b0 ^
虽然转移和过程腔室不断疏散,出入口腔室必须定期通风,然后再撤离。由于这些腔室的大批量和短周期,高抽速是必需的。它是由旋转叶片泵和罗茨泵组合。对于特别是短周期冷却罗茨泵还使用天然气。
" K( T8 }2 Q& T所有系统的主要功能,如玻璃的运输,溅射工艺和泵的控制,进行了充分自动控制,这是唯一的途径,以确保产品的高品质以及高效率。 |
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