diplomsko delo
Gal Gros (Author), David Nedeljković (Mentor)

Abstract

Elektrostatična razelektritev (ang. electrostatic discharge (ESD)) je eden glavnih razlogov za uničenje in posledično izmet elektronskih vezij med njihovo izdelavo ali vgradnjo v druge naprave. Najbolj občutljivi elementi na razelektritve so tranzistorji z oksidno plastjo, pri katerih tok ESD naredi prevodno pot skozi oksid. Namen dela je izbrati ustrezno zaščito in opremo za proizvodno linijo, na kateri se že narejena elektronska vezja vgrajujejo v ohišje motorja. Ustreznost zaščite ter opreme je nato potrebno preveriti z meritvami upornosti in dovzetnosti za naelektritev. Upravičenost zaščite je potrebno dokazati z dovolj hitro povrnitvijo investicije v zaščitno opremo. Do električne razelektritve pride med dvema površinama, med katerima je dovolj visoka napetost oziroma jakost elektrostatičnega polja. Bližje kot sta si površini, manjši naboj je potreben za razelektritev. Razdalja in količina naboja, pri katerih pride do razelektritve, sta odvisni še od medija med površinama, ki je v proizvodnem prostoru največkrat zrak. Razelektritve v proizvodnji so v nehomogenem polju, ker je zrak nehomogena snov, in potekajo prek strimerjev ter liderjev. Približek razelektritve za testiranje vzdržljivosti komponent pa lahko dosežemo z RLC vezjem, katerega parametri so določeni po standardu za modele človeka, stroja in naelektrene naprave. Območje, kjer je uvedena zaščita in lahko rokujemo z elektronskimi vezji imenujemo prostor oziroma območje zaščiteno pred elektrostatičnimi razelektritvami (ang. ESD protected area (EPA)). Vsa oprema v tem prostoru vključno s človekom mora biti ozemljena. Med opremo sodijo tla, delovne površine, stroji, ročna orodja, embalaža in pisarniški material, namenjen organizaciji dela. Večina opreme je ozemljena z vodnikom, ki je povezan z ozemljitvijo stavbe. Predmeti, ki jih ne moremo ozemljiti z vodnikom, so iz prevodnega materiala in se ozemljijo preko prevodne delovne površine, ki je ozemljena z vodnikom. Vsa oprema in EPA morajo biti ustrezno označeni z opozorilnimi tablami ali oznakami na opremi. Osnovna ESD oznaka je rumena roka v črnem trikotniku pod kupolo na rumeni podlagi. Poleg ozemljitve se zaščitimo tudi z ionizatorji, ki pihajo pozitivno in negativno naelektrene delce zraka na površino, ki jo želimo razelektriti. Poznamo ionizatorje, ki izkoriščajo pojav korone, na izmenični tok, pulzirajoč ali konstanten enosmerni tok. Druga vrsta ionizatorjev izkorišča radioaktivni razpad elementa, ki seva alfa delce, ki ionizirajo delce zraka. Zaščitno opremo je potrebno redno preverjati, če je še primerna za uporabo. Meritve se opravljajo v mesečnih, polletnih ali letnih intervalih. Preveriti moramo vsak element zaščite. Merimo upornost tal, delovne površine, embalaže, halje in ozemljitvenih povezav. Kjer lahko, izmerimo tako površinsko kot volumsko upornost. Pri tleh izmerimo še naelektritev osebe med hojo. Pri meritvi ionizatorjev preverimo hitrost sposobnosti razelektritve naelektrene površine in enakomernost proizvajanja pozitivnih in negativnih ionov. Meritve so pokazale da je zaščitna oprema linije ustrezna. Sredstva investicije v zaščitno opremo se povrnejo v zelo kratkem času; na danem primeru proizvodne linije v 31 delovnih dneh.

Keywords

elektrostatika;elektrostatične razelektritve;zaščita pred elektrostatičnimi razelektritvami;ionizatorji;upornost;visokošolski strokovni študij;Aplikativna elektrotehnika;diplomske naloge;

Data

Language: Slovenian
Year of publishing:
Typology: 2.11 - Undergraduate Thesis
Organization: UL FE - Faculty of Electrical Engineering
Publisher: [G. Gros]
UDC: 621.3(043.2)(0.034.2)
COBISS: 206497027 Link will open in a new window
Views: 50
Downloads: 21
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Other data

Secondary language: English
Secondary title: Protection of the production line against electrostatic discharges
Secondary abstract: Electrostatic discharge (ESD) is one of the main reasons for the destruction and subsequent rejection of electronic circuits during their manufacture or installation in other devices. The most susceptible elements to damage are oxide layer transistors, where the ESD current makes a conductive path through the oxide. The purpose of this work is to choose the appropriate protection and equipment for the production line, on which the electronic circuits are installed in the motor housing. Adequacy of protection and equipment must then be checked by measuring resistance and susceptibility to electrification. However, the justification for protection must be proven with a sufficiently quick recovery of the investment in protective equipment. Electrostatic discharge occurs between two surfaces between which there is a sufficiently high voltage or strength of the electrostatic field. The closer the two surfaces are, the less charge is required for discharge. The distance and amount of charge at which discharge occurs also depend on the material between the surfaces. In the production area this material is air. Discharges in the production area are in an inhomogeneous field, because air is an inhomogeneous substance. Discharge path is defined through streamers and leaders. An approximation of the discharge for testing the durability of components can easily be achieved with an RLC circuit, the parameters of which are determined according to the standard for models of human body, machine and charged device. The area, where protection is introduced and where we can handle electronic circuits, is called ESD protected area (EPA). All equipment in this room, including the persons, must be grounded. The equipment includes floors, work surfaces, machines, hand tools, packaging and office material intended for the organization of work. Most equipment is grounded with a conductor connected to the building's grounding point. Objects that cannot be grounded with a conductor are made of conductive material and are grounded via a conductive work surface which is grounded with a conductor. All equipment and EPA must be properly marked with warning signs or markings on the equipment. The basic ESD symbol is a yellow hand in a black triangle under a dome on a yellow background. In addition to grounding, we can also protect electronic circuits with ionizers that blow positively and negatively charged air particles onto the protected surface. Ionizers use the phenomenon of corona and can work on alternating current, pulsating or constant direct current. Another type of ionizer utilizes the radioactive decay of an element that emits alpha particles that ionize air particles. Protective equipment must be regularly checked to see if it is still suitable for use. Measurements are performed at monthly, on half-year or annual intervals. Every element of ESD protection must be checked. We measure the resistance to the ground, work surface, packaging, garments and grounding connections. Where possible, both surface and volume resistivity must be measured. For flooring, we also measure charging of a person while walking. iv When measuring ionizers, we check the speed of discharging a charged surface and the uniformity of the production of positive and negative ions. The measurements showed that chosen protection is acceptable. Investments in protective equipment are returned in short period of time. On this production line the investment is returned in 31 working days.
Secondary keywords: Electrostatics;Electrostatic discharge;Protection against electrostatic discharges;Ionizer;Resistance;
Type (COBISS): Bachelor thesis/paper
Study programme: 1000315
Thesis comment: Univ. v Ljubljani, Fak. za elektrotehniko
Pages: 1 spletni vir (1 datoteka PDF (X, 30 str.))
ID: 24910899