Uma isignali yefrikhwensi ephezulu/microwave radio frequency ifakwa ku PCB isifunda, ukulahlekelwa okubangelwa i-circuit ngokwayo kanye ne-circuit material nakanjani kuzokhiqiza inani elithile lokushisa. Ukulahlekelwa okukhulu, amandla adlula ezintweni ze-PCB aphezulu, kanye nokushisa okukhiqizwa kakhulu. Lapho izinga lokushisa lokusebenza lesifunda lidlula inani elilinganiselwe, isifunda singabangela izinkinga ezithile. Isibonelo, ipharamitha yokusebenza ejwayelekile ye-MOT, eyaziwa kakhulu kuma-PCB, izinga lokushisa eliphakeme lokusebenza. Uma izinga lokushisa lokusebenza lidlula i-MOT, ukusebenza nokuthembeka kwesekethe ye-PCB kuzosongelwa. Ngenhlanganisela yemodeli kazibuthe kagesi kanye nezilinganiso zokuhlola, ukuqonda izici ezishisayo zama-RF microwave PCB kungasiza ukugwema ukuwohloka kokusebenza kwesekethe kanye nokuwohloka kokwethembeka okubangelwa amazinga okushisa aphezulu.

Ukuqonda ukuthi kwenzeka kanjani ukulahlekelwa kokufaka ezintweni zesekethe kusiza ukuchaza kangcono izici ezibalulekile ezihlobene nokusebenza okushisayo kwamasekhethi e-PCB anemvamisa ephezulu. Lesi sihloko sizothatha isekethe yomugqa wokudlulisa we-microstrip njengesibonelo sokuxoxa ngokuhwebelana okuhlobene nokusebenza okushisayo kwesekhethi. Kumjikelezo we-microstrip onesakhiwo se-PCB esinezinhlangothi ezimbili, ukulahlekelwa kufaka phakathi ukulahlekelwa kwe-dielectric, ukulahlekelwa kwe-conductor, ukulahlekelwa kwemisebe, nokulahlekelwa kokuvuza. Umehluko phakathi kwezingxenye ezihlukene zokulahlekelwa mkhulu. Ngaphandle kokumbalwa, ukulahleka kokuvuza kwamasekhethi e-PCB anemvamisa ephezulu ngokuvamile kuphansi kakhulu. Kulesi sihloko, njengoba inani lokulahlekelwa kokuvuza liphansi kakhulu, lizozitshwa okwamanje.

Ukulahleka kwemisebe

Ukulahleka kwemisebe kuncike kumapharamitha amaningi wesekethe njengemvamisa yokusebenza, ukujiya kwe-substrate yesifunda, i-PCB dielectric constant (isihlobo se-dielectric constant noma εr) nohlelo lokuklama. Mayelana nezinhlelo zokuklama, ukulahleka kwemisebe kuvame ukuvela ekuguqukeni okungalungile kwe-impedance kusekethe noma umehluko wokudluliswa kwamagagasi kagesi kusekethe. Indawo yokuguqula i-circuit impedance ngokuvamile ihlanganisa indawo yokuphakelayo yesignali, indawo yokuvimbela isinyathelo, i-stub kanye nenethiwekhi efanayo. Idizayini yesifunda enengqondo ingathola ukuguqulwa kwe-impedance okushelelayo, ngaleyo ndlela kunciphise ukulahleka kwemisebe yesekethe. Vele, kufanele kuqashelwe ukuthi kukhona ithuba lokungafani kwe-impedance okuholela ekulahlekelweni kwemisebe kunoma iyiphi i-interface yesekethe. Ngokombono wokuvama kokusebenza, ngokuvamile ukuphakama kwemvamisa, kukhulu ukulahlekelwa kwemisebe yesekethe.

Imingcele yezinto zesekethe ezihlobene nokulahlekelwa kwemisebe ngokuyinhloko i-dielectric constant kanye nogqinsi lwempahla ye-PCB. Ukuqina kwe-substrate yesifunda, amathuba amakhulu okubangela ukulahleka kwemisebe; lapho i-εr yezinto ze-PCB ephansi, ukulahleka okukhulu kwemisebe yesekethe. Ukulinganisa izici ezibonakalayo, ukusetshenziswa kwama-substrate wesifunda esincane kungasetshenziswa njengendlela yokuqeda ukulahlekelwa kwemisebe okubangelwa izinto eziphansi zesekethe ze-εr. Umthelela wokujiya kwe-substrate yesekethe kanye no-εr ekulahlekeni kwemisebe yesekethe kungenxa yokuthi kuwumsebenzi oncike emazingeni. Uma ubukhulu be-substrate yesifunda bungadluli ku-20mil futhi imvamisa yokusebenza ingaphansi kuka-20GHz, ukulahlekelwa kwemisebe yesekethe kuphansi kakhulu. Njengoba iningi lamamodeli wesekethe namaza okulinganisa kulesi sihloko angaphansi kuka-20GHz, ingxoxo kulesi sihloko izoziba umthelela wokulahleka kwemisebe ekushisiseni kwesekethe.

Ngemva kokuziba ukulahlekelwa kwemisebe engaphansi kuka-20GHz, ukulahlekelwa kokufaka kwesekethe yomugqa wokudlulisa we-microstrip ikakhulukazi kufaka izingxenye ezimbili: ukulahlekelwa kwe-dielectric nokulahlekelwa kwe-conductor. Ingxenye yalokhu okubili ngokuyinhloko incike ebukhulu be-substrate yesifunda. Kuma-substrates azacile, ukulahleka kwe-conductor kuyisici esiyinhloko. Ngenxa yezizathu eziningi, ngokuvamile kunzima ukubikezela ngokunembile ukulahleka komqhubi. Isibonelo, ubulukhuni obungaphezulu be-conductor bunomthelela omkhulu ezicini zokudlulisela zamagagasi kagesi. Ubukhulu obungaphezulu be-foil yethusi ngeke buguqule nje kuphela i-electromagnetic wave propagation constant yesekethe ye-microstrip, kodwa futhi kwandise ukulahleka komqhubi wesekethe. Ngenxa yomphumela wesikhumba, umthelela we-foil yethusi ekulahlekeni kwe-conductor nakho kuncike emazingeni. Umfanekiso 1 uqhathanisa ukulahleka kokufakwa kwamasekethe olayini wokudlulisa we-microstrip angu-50 ohm ngokusekelwe kogqinsi obuhlukene be-PCB, okuyi-6.6 mils kanye ne-10 mils, ngokulandelana.

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Umfanekiso 1. Ukuqhathaniswa kwamasekhethi kalayini wokudlulisa we-microstrip angu-50 ohm ngokusekelwe ezintweni ze-PCB ezinobukhulu obuhlukahlukene.

Imiphumela elinganisiwe neyalingiswa

Ijika elikuMdwebo 1 liqukethe imiphumela elinganisiwe nemiphumela yokulingisa. Imiphumela yokulingisa itholakala ngokusebenzisa isofthiwe yokubala ye-MWI-2010 ye-microwave impedance ye-Rogers Corporation. Isofthiwe ye-MWI-2010 icaphuna izibalo zokuhlaziya emaphepheni akudala emkhakheni we-microstrip line modelling. Idatha yokuhlola kuMfanekiso 1 itholwa ngendlela yokulinganisa ubude obuhlukile yokuhlaziya inethiwekhi ye-vector. Kungabonakala ku-Fig. 1 ukuthi imiphumela yokulingisa yejika eliphelele lokulahlekelwa ngokuyisisekelo ihambisana nemiphumela elinganisiwe. Kungabonakala emfanekisweni ukuthi ukulahlekelwa komqhubi wesifunda esincane (ijika elingakwesokunxele lihambisana nobukhulu obungu-6.6 mil) luyingxenye eyinhloko yokulahlekelwa okuphelele kokufaka. Njengoba ukushuba kwesekethe kukhula (ugqinsi oluhambisana nejika elingakwesokudla lingu-10mil), ukulahleka kwe-dielectric nokulahlekelwa kwekhondatha kuvame ukusondela, futhi kokubili ndawonye kwakha ukulahlekelwa okuphelele kokufakwa.

Imodeli yokulingisa ku-Figure 1 kanye nemingcele yezinto zesekethe ezisetshenziswa kusekethe yangempela yilezi: i-dielectric constant 3.66, i-loss factor 0.0037, kanye ne-copper conductor surface roughness 2.8 um RMS. Lapho ukuqina kwe-surface ye-foil yethusi ngaphansi kwezinto ezifanayo zesifunda kuncishisiwe, ukulahlekelwa komqhubi we-6.6 mil kanye ne-10 mil circuits ku-Figure 1 kuzoncishiswa kakhulu; Nokho, umphumela awubonakali kumjikelezo we-20 mil. Umfanekiso wesi-2 ubonisa imiphumela yokuhlolwa kwezinto ezimbili zesekethe ezinobunzima obuhlukile, okuyi-Rogers RO4350B™ impahla yesekethe evamile enobunzima obuphezulu kanye nesekhethi ye-Rogers RO4350B LoPro™ enobunzima obuphansi.

Umfanekiso wesi-2 ubonisa izinzuzo zokusebenzisa i-substrate ye-foil yethusi ebushelelezi ukucubungula amasekethe amancane. Kuma-substrates amancane, ukusetshenziswa kwe-foil yethusi ebushelelezi kunganciphisa kakhulu ukulahlekelwa kokufaka. Ku-substrate engu-6.6mil, ukulahlekelwa kokufaka kuncishiswe ngo-0.3 dB ku-20GHz ngenxa yokusetshenziswa kwe-foil yethusi ebushelelezi; i-substrate engu-10mil yehliswe ngo-0.22 dB ku-20GHz; kanye ne-substrate engu-20mil, ukulahlekelwa kokufaka kwehliswa kuphela ngo-0.11 dB.

Njengoba kuboniswe kuMfanekiso 1 no-Figure 2, i-substrate yesifunda ibe mncane kakhulu, iphakamisa ukulahlekelwa kokufaka kwesifunda. Lokhu kusho ukuthi uma isekethe inikezwa inani elithile lamandla e-RF microwave, okuzoba mncane kwesekhethi kuzokhiqiza ukushisa okwengeziwe. Uma kulinganiswa ngokuningiliziwe udaba lokushisisa kwesekethi, ngakolunye uhlangothi, isekethi encane ikhiqiza ukushisa okwengeziwe kunomjikelezo owugqinsi kumazinga aphezulu wamandla, kodwa ngakolunye uhlangothi, isekethe encane ingathola ukugeleza kokushisa okusebenzayo kakhulu kusinki wokushisa. Gcina izinga lokushisa liphansi kakhulu.

Ukuze uxazulule inkinga yokushisa yesifunda, isifunda esincane esifanelekile kufanele sibe nezici ezilandelayo: isici esiphansi sokulahlekelwa kwezinto zesifunda, ithusi elibushelelezi elibushelelezi eliphansi, i-εr ephansi kanye ne-conductivity ephezulu yokushisa. Uma kuqhathaniswa nempahla yesifunda ye-high εr, ububanzi bomqhubi we-impedance efanayo etholakala ngaphansi kwesimo se-εr ephansi ingaba mkhulu, okuzuzisa ukunciphisa ukulahlekelwa komqhubi wesifunda. Ngokombono wokuchithwa kokushisa kwesifunda, nakuba ama-substrates amaningi e-PCB aphakeme kakhulu ane-conductivity ephansi kakhulu ye-thermal ehlobene nama-conductor, ukuqhutshwa kokushisa kwezinto zokujikeleza kuseyipharamitha ebaluleke kakhulu.

Izingxoxo eziningi mayelana ne-thermal conductivity ye-circuit substrates ziye zachazwa ezihlokweni zangaphambili, futhi lesi sihloko sizocaphuna eminye imiphumela nolwazi oluvela ezihlokweni zangaphambili. Isibonelo, i-equation elandelayo kanye nomfanekiso wesi-3 kuyasiza ukuqonda izici ezihlobene nokusebenza okushisayo kwezinto zokujikeleza ze-PCB. Esilinganisweni, k i-thermal conductivity (W/m/K), A indawo, TH izinga lokushisa lomthombo wokushisa, i-TC izinga lokushisa lomthombo obandayo, futhi L ibanga phakathi komthombo wokushisa kanye umthombo obandayo.