Pure-spacesuited materials

Pure-spacesuited materials test and classification procedures around the industry with the structure of manufacturing plants for konta minationsempfindliche mikrosysteme to support, are needed purity-fair reason and structure materials. World-wide no material lists are available, so that with the selection of suitable materials to optical and scientifically not secured criteria one pays attention purely. With a standardized testing method for the evaluation of the pure space fitness of materials one works against to this circumstance. 1 introduction the claims of quality to all products constantly rise. A constantly growing number of industries and their products need therefore a purity-fair manufacturing. With the "pure manufacturing" it is necessary to control all product-relevant contamination factors.Particularly within ranges like the semiconductor industry, the foodstuffs industry or the pharmaceutical industry a particularly high value comes to the avoidance of individual contamination. Means of production, which are used into pure manufacturing, carry often substantial for the contamination of the "pure manufacturing" those procedures, which lead to the generation of particle emission procedures at means of production, can to friction and schwingungsvorgaenge be attributed. To emphasize is:: Friction procedures, which are caused by the relative motion of the means of production surfaces, possess the by far highest portion. For the generation of particles on technical surfaces of friction partners existed at present still no scientifically founded model conception, which permits it, the material selection for "pure manufacturing" already in the apron of meeting during the means of production development.In the area of the clearing-up of connections between technical characteristics of combinations of material and the generation of contamination, in particular those the airborne particles at means of production, no research work is to be in-grouped bekannt.Um the contamination behavior of basic materials or surface coatings, must a procedure for determining the pure space fitness by combinations of material be compiled. above all to the emission of airborne, mikroner and/or submikroner particles a special meaning is attached to 2 prioritization of the kinds of contamination apart from the electrostatic contamination behavior or the delivery of easily volatile organic materials. If the source of particle "humans" remains unconsidered, latter process has the largest influence on the pollution of the product (with approximately 30 % to 40 % portion of all, unwanted contamination arising in the pure area).A representatively accomplished inquiry with approximately 270 companies resulted in that the partikelfoermigen contamination takes the highest value regarding the research need:: Two thirds of all demands on the materials cover the particle poverty or particle liberty. Linked with the particle emission closely, the surface quality of assigned materials (fig. 1) stands. Particles emitted by means of production develop due to material oscillations or relative motions of at least two together rubbing materials. With these induced friction pairings of means of production components the surface systems of means of production take to crucial influence on the generation of particle. 3 contentwise objective 3,1 developing a test procedure around the individual emission behavior of different combinations of material to clear up, is developed a standardized test procedure.During the practical conversion a material test stand serves for the contamination-free under search of materials for the pure space employment. The development of a scientifically founded test procedure ensures - reproductibility, - the comparability, - security and - to interpretation of the results of measurement. 3.2 evaluation and classifying scheme for evaluating and classifying gewon the nenen measuring data must be compiled and used evaluation mechanisms. Here can be partly fallen back to guideline and standard works from the semiconductor and clean-room technology, already existing. The evaluation algorithms for the measuring data are to point clearly the suitability out of the different combinations of material for the employment within pure ranges. 3.3 optimizing combinations of material the proceeding divided into - actual condition analysis (first determination of the contamination condition), - the modification of the combination of material (optimization of the Tribosystems) and - verification analysis (determination of the contamination condition renewed) dividing permits a systematic advancement of the combinations of material to the purity-relevant requirements. With the regarding of the airborne individual contamination statements about the suitability of the combinations of material for existing air categories of purity can be met, since in the internationally recognized air purity standards only to this kind of contamination is referred. This circumstance increases the national and international acceptance of the test procedure and their results crucially. 4 process development nearly all movement procedures at production plants leads to friction procedures between two materials.The friction again is the most frequent cause for the particle emergence. In order to make this scientifically seizable, the particle emissions must be seized and evaluated instrumentation. First step here is identifying the Hauptemissionsquelle(n) at material construction units or components. In order if possible few foreign influences on the result of measurement of the detected sources of main mission to received, as much as possible sources of influence of noise are to be eliminated. That succeeds to the friction pairing place from the material construction unit at the best one with extracting and separating. For this the friction pairing place in a test stand on standardized, reproducible laboratory conditions must be placed behind (fig. 2).The procedure for the evaluation of the purity quality of the examined combinations of material is two statements liefern::• in which air categories of purity (following international sets of rules for the evaluation of the air purity) to know "separated" material mating is used, und• in what respect is the results of the investigations on laboratory conditions to material construction unit/components transferably. Material construction units and components are examined after the established proceeding of the VDI 2083 sheet 8 "pure space fitness by operational funds" on their pure space fitness. This proceeding is appropriate for the evaluation of complex construction units. With the attempt to examine individual combinations of material this procedure fails.Transfer the results to material construction units after the friction partners identified and into a Tribosystem in the laboratory test stand are transferred, extents of utilization are adapted to typical load conditions of the material construction units. Classification measurements and evaluations find after VDI 2083 sheet 8 (material construction unit) as well as the classification model for combinations of material with the load universe of three representative extents of utilization. In order to determine the transferability of the differently won classification results, a model must be developed. It can be provided however only in a second step, if the classification model were established before for the evaluation of the pure space fitness of combinations of material in test stands. All obtained measured values and statements are to be confirmed with suitable statistic procedures. 5 conceiving a material test stand 5.1 friction procedures the friction between two bodies can be realized in principle by the three following procedures (fig. 3 and picture 4) with the "spherical washer test" is pressed a ball against the front surface of a disk. The contact point is punctiform, the ball is fix with the "disk disk test" a swivelling stored disk laterally to the drive disk is advanced and unreels on this. The contact point is linienfoermig, both surfaces is curved at the contact point. With the "role disk test" a role (for example high-grade steel or PA6-Rolle) is pressed on the face of a disk, which is provided with the coating which can be examined. The procedure is used for the investigation of linings or coatings, on which in the material case a role runs off. The "role disk test" is used for example of the examination of a pure space floor mat, on which roll-claimant cars run off. 5.2 attempt principle the "spherical washer test" frequently into literature and practice is used there, are present for this extensive data records for correlation with the generation of particle. A further advantage of the test is in the fact that a punctiform contact point between the materials is present. Since thus a high standardizableness exists, the "spherical washer procedure" is consulted for the following views. Rotates a test disk with the frequency f under a ball of the diameter D, which is pressed with the normal force FN with a radius r on the disk. At the contact point of ball and disk it comes to a material removal, which is accompanied by a particle emission. It is formed a wear trace.The characteristics both the wear trace and the contact point can be consulted in dependence of the detectable load sizes at material components (pressing surface, laufstrecke, multiple load of stages) for the evaluation and fine differentiation. 5.3 identifying the relevant parameters with a "spherical washer test" represents the inspection pieces involved (ball, disk) a wear system. It can be described by a parameter set. For the attempts accomplished here the relevant parameters of the wear system do not result following DIN 50320 (old) as in fig. 5 gezeigt.In the literature are present data, whose article the individual emission of friction pairings or the linkage of tribologischen sizes with an observed particle emission is. In DIN 50324 (old) an interlaboratory test is described, in which by means of the "spherical washer test" high-grade steel mating is examined.The inputs used there served the preliminary tests as starting point for Vorversuche.In the dependence of the examined characteristics (particle emission, tribologische sizes) of the normal force were examined and the temporal development during a longer period seized. the conception of a test stand shows 5.4 shifting of the test stand concept fig. 6 after the "spherical washer test", with which the requirements at the pure space and purity fitness of the test stand must be kept. 5.5 integrating the particle investigations with the determination of the Tribo characteristics of parallel to the investigation of the particle emission is determined tribologische characteristics. For the confrontation of the results as reference basis the particle emission is used. From the measured values of the individual particle channels (0.2 µm; 0,3 µm; 0,5 µm and 5.0 µm) the size of "particle volume" can be derived.The tribologischen characteristics are referred individually and in compound form (when derived sizes such as trace volumes) to this size. Thus the connection of the tribologischen characteristics and the particle emission values can be judged. 6 classification model for combinations of material a crucial goal is it to observe and characterize the development of the particle emission during the tribologischen load. The used optical particle counters supply the particle measured values in differential representation, that means as counting events per gate time or measuring volume interval. In preliminary tests a very unsteady behavior of the measured value development resulted in the case of the diagram of the particle measured values over the number of revolutions, so that the measured values in this form were unsuitable as basis for a characterisation (fig. 7).While the first revolution of the test ball on the test disk, the ball on a so far unaffected laufstrecke runs off, so that a small particle emission takes place. During the subsequent revolution the ball on a laufstrecke already loaded runs off, so that increased particle emissions are the result. This effect continues with the subsequent revolutions in each case and explains the observed unstable behavior of the emission values over the total time. This circumstances lead to the fact that the condition for an evaluation with the student t and Poisson statistics - as this demands the VDI 2083 sheet 8 - is no more fulfilled be-generally a tendentious rise of the measured values with the number of revolutions to observe (see fig. 7). If now all generated particles up to a discrete number of revolutions are added, this corresponds integrals to a representation of the particle measured values.The resulting curves show a constant process (fig. 8) in this representation. With the help of integrals the representation graphs can be produced, those as basis for the characterisation of the particle emission serve to the explanation of the observed increase of the emission values over the time are assumed during the first revolution of the combination of material particles are already produced as abrasives. While the combination of material (together with the before produced particles) causes still faster further particles for the subsequent revolution, so that an avalanche effect takes place. Mathematically one tries to represent the avalanche-like rise of the particle emission with an exponential beginning:: After an approximation of the particle emission graphs by means of nonlinear involution, cumulated, the curves can be mathematically accurately further regarded.The parameters A and b and/or the pair (a/b) of the regression curves represent a yardstick for the emission rate and thus the pure space fitness of the regarded Werkstoffpaarung.Da the number of generated particles directly with the number of revolutions, only however in subordinated measure with the applied time are connected, as new control variable in place of the gate time the number of the revolutions are consulted. After converting the limit values of the maximally permissible particle numbers for the individual air categories of purity according to DIN EN ISO 14644-1 in dependence of the numbers of revolutions, an air category of purity diagram adapted to the problem (fig. 9) results. During illustration of the summed particle values by means of regression curves these always cut the border straight lines of the air categories of purity.In order to reduce on the one hand the pair (a/b) of the regression curves to an individual parameter, and the moreover one a clear statement about the pure space fitness of the regarded combination of material too received, is necessary the definition on a firm number of revolutions. Since in the represented example the examined combination of material during the reference revolution of N = 500 between the limit value straight lines of the air categories of purity ISO Class 5 and ISO Class 6 lie, this combination of material can be used secured in pure areas of the ISO Class 6.7 advantages of the classification procedure in the following one are combined the advantages of the classification model into the evaluation of the pure space fitness of arbitrary combinations of material:: 8 view in the further research becomes above all the reciprocal effect relationship between classification results at material construction units - how these were classified according to the VDI 2083 sheet 8 - and on combinations of material in laboratory test stands "separated" compiled.