Kungani imigqa ezwelayo ku PCB imiphetho ethambekele ekuphazanyisweni kwe-ESD?

Ukusetha kabusha kohlelo kwenzeke lapho ibhentshi lokuhlola lihlolwa kusetshenziswa ukukhishwa koxhumana nabo be-ESD kwe-6KV esikhumulweni sokubeka phansi. Ngesikhathi sokuhlolwa, i-Y capacitor exhunywe ku-terminal yomhlabathi kanye nendawo yokusebenza yedijithali yangaphakathi inqanyuliwe, futhi umphumela wokuhlolwa awuthuthukisiwe kakhulu.

Ukuphazanyiswa kwe-ESD kufaka isekethe langaphakathi lomkhiqizo ngezindlela ezahlukahlukene. Ngemikhiqizo ehlolwe kuleli cala, iphuzu lokuhlola liyiphuzu lomhlabathi, iningi lamandla wokuphazanyiswa kwe-ESD azohamba asuke kulayini wokubeka phansi, okusho ukuthi, i-ESD yamanje ayigeleli ngqo kwisekethe yangaphakathi yomkhiqizo, kepha , ku-IEC61000-4-2 ejwayelekile yokuhlola imvelo ye-ESD kule mishini yetafula, ubude bomugqa wokumisa cishe ku-1m, Umugqa wokugcizelela uzokhiqiza ukukhuphuka komthofu okukhudlwana (kungasetshenziswa ukulinganisa u-1 u H / m), ukuphazamiseka kokukhishwa kwe-electrostatic kwenzeka (isibalo 1 switch K) lapho kuvaliwe, imvamisa ephezulu (engaphansi kwe-1 ns ekhuphuka ngokugeleza kwe-electrostatic yamanje ayenzi yenza imikhiqizo evivinywayo ihlangane ne-zero zero voltage (FIG. 1 G point voltage in K is not zero when closed). Le voltage engeyona eye-zero esigungwini somhlaba izophinde ingene ekujikelezeni kwangaphakathi komkhiqizo. Umdwebo 1 unikeze umdwebo wesikimu wokuphazanyiswa kwe-ESD ku-PCB engaphakathi komkhiqizo.

ISITHOMBE. Umdwebo wesikimu wokuphazanyiswa kwe-ESD okufaka i-PCB ngaphakathi komkhiqizo

Kungabonakala futhi kusuka ku-Figure 1 ukuthi i-CP1 (capacitance parasitic capacitance between discharge point and GND), Cp2 (capacitance parasitic between PCB board and reference grounding floor), indawo yokusebenza yebhodi le-PCB (GND) kanye nesibhamu sokukhipha i-electrostatic (kufaka phakathi ucingo lwe-grounding isibhamu sokukhipha i-electrostatic) ndawonye benza indlela yokuphazamiseka, futhi ukuphazamiseka kwamanje yi-ICM. Kule ndlela yokuphazanyiswa, ibhodi le-PCB liphakathi, futhi i-PCB ngokusobala iphazamisekile ngokukhishwa kwe-electrostatic ngalesi sikhathi. Uma kukhona ezinye izintambo kumkhiqizo, ukuphazamiseka kuzoba nzima kakhulu.

Ukuphazamiseka kuholele kanjani ekusethweni kabusha komkhiqizo ohloliwe? Ngemuva kokuhlolwa ngokucophelela kwe-PCB yomkhiqizo ohloliwe, kutholakale ukuthi umugqa wokulawula ukusetha kabusha we-CPU ku-PCB wabekwa onqenqemeni lwe-PCB nangaphandle kwendiza ye-GND, njengoba kukhonjisiwe ku-Figure 2.

Ukuchaza ukuthi kungani imigqa ephrintiwe onqenqemeni lwe-PCB isengozini yokuphazanyiswa, qala ngamandla we-parasitic phakathi kwemigqa ephrintiwe ku-PCB kanye ne-plate plate eyinkomba. Kukhona amandla we-parasitic phakathi komugqa ophrintiwe kanye nepuleti lokufaka ireferensi, elizophazamisa umugqa wesiginali ophrintiwe ebhodini le-PCB. Umdwebo wesikimu wevolumu yokuphazanyiswa kwemodi ejwayelekile ephazamisa ulayini ophrintiwe ku-PCB uboniswa ku-Figure 3.

Umdwebo 3 ukhombisa ukuthi lapho ukuphazamiseka kwemodi ejwayelekile (i-voltage evamile yokuphazanyiswa kwamandla okuhlobene nesitezi sokubhekisa phansi) ingena ku-GND, kuzongena i-voltage yokuphazamiseka phakathi komugqa ophrintiwe ebhodini le-PCB nase-GND. Le voltage yokuphazanyiswa ayihlobene kuphela ne-impedance phakathi komugqa ophrintiwe kanye ne-GND yebhodi le-PCB (Z ku-Figure 3) kodwa futhi naku-capacitance yama-parasitic phakathi komugqa ophrintiwe kanye ne-reference plate grounding ku-PCB.

Uma ucabanga ukuthi i-impedance Z phakathi komugqa ophrintiwe nebhodi le-PCB GND ayiguquki, lapho amandla we-parasitic phakathi komugqa ophrintiwe kanye nesitezi sokubeka phansi kukhulu, amandla okuphazamiseka e-Vi phakathi komugqa ophrintiwe nebhodi le-PCB GND likhulu. Le voltage iphezulu ngamandla asebenzayo ajwayelekile ku-PCB futhi izothinta ngqo isekethe esebenza ku-PCB.

ISITHOMBE. 2 Umdwebo wangempela wentambo ye-PCB engakhethi yomkhiqizo ohloliwe

ISITHOMBE. 3 Imodi ejwayelekile yokuphazamiseka kwamandla okuphazamiseka kwe-PCB ephrintiwe yomugqa wesikimu

Ngokusho kwefomula 1 yokubala amandla we-parasitic phakathi kolayini ophrintiwe kanye ne-reference plate grounding, amandla we-parasitic phakathi komugqa ophrintiwe kanye ne-reference plate grounding incike ebangeni phakathi komugqa ophrintiwe kanye ne-reference plate grounding (H ku-Formula 1) nendawo elingana nensimu kagesi eyakhiwe phakathi kwentambo ephrintiwe kanye nepuleti lokugxila okuyinkomba

Ngokusobala, ekwakhiweni kwesifunda kuleli cala, umugqa wesiginali wokusetha kabusha ku-PCB uhlelwe onqenqemeni lwebhodi le-PCB futhi uwele ngaphandle kwendiza ye-GND, ngakho-ke umugqa wesiginali wokusetha kabusha uzophazamiseka kakhulu, okuholele esimeni sokusetha kabusha uhlelo ngesikhathi se-ESD ukuhlolwa.