Ngenxa yobukhulu obuncinci kunye nobukhulu, akukho phantse imigangatho yebhodi yesekethe eprintiweyo ekhulayo yemarike ye-IoT enxibekayo. Ngaphambi kokuba le migangatho iphume, kwafuneka sithembele kulwazi kunye namava okuvelisa afundiweyo kuphuhliso lwenqanaba lebhodi kwaye sicinge malunga nendlela yokuyisebenzisa kwimingeni ekhethekileyo evelayo. Kukho iinkalo ezintathu ezifuna ingqalelo yethu ekhethekileyo. Zizo: izixhobo zomphezulu webhodi yesekethe, uyilo lweRF/microwave kunye neentambo zothumelo lweRF.

Izinto zePCB

"I-PCB" ngokubanzi iqulethe i-laminates, enokuthi yenziwe nge-fiber-reinforced epoxy (FR4), i-polyimide okanye i-Rogers imathiriyeli okanye ezinye izinto ze-laminate. Izinto zokugquma phakathi kweeleya ezahlukeneyo zibizwa ngokuba yi-prepreg.

izixhobo ezinxitywayo zifuna ukuthembeka okuphezulu, ngoko xa abaqulunqi be-PCB bejongene nokukhetha ukusebenzisa i-FR4 (eyona nto ibiza kakhulu i-PCB impahla yokuvelisa) okanye izinto eziphambili kunye nexabiso eliphezulu, oku kuya kuba yingxaki.

Ukuba izicelo zePCB ezinxitywayo zifuna isantya esiphezulu, izixhobo ezisebenza rhoqo, iFR4 isenokungabi lolona khetho lungcono. I-dielectric constant (Dk) ye-FR4 yi-4.5, i-dielectric constant of the more advanced Rogers 4003 series material is 3.55, kunye ne-dielectric constant of the brother series Rogers 4350 yi-3.66.

“I-dielectric constant ye-laminate ibhekiselele kumlinganiselo we-capacitance okanye amandla phakathi kweperi ye-conductor ezikufutshane ne-laminate kwi-capacitance okanye amandla phakathi kweperi ye-conductors kwi-vacuum. Kwiifrikhwensi eziphezulu, kungcono ukuba ube nelahleko encinci. Ngoko ke, i-Roger 4350 ene-dielectric constant ye-3.66 ifaneleka ngakumbi kwizicelo eziphezulu ze-frequency kune-FR4 ene-dielectric constant ye-4.5.

Phantsi kweemeko eziqhelekileyo, inani leeleya zePCB zezixhobo ezinxitywayo zisuka kwi-4 ukuya kwi-8 layers. Umgaqo wokwakha umaleko kukuba ukuba i-PCB ye-8-layer, kufuneka ikwazi ukubonelela ngomgangatho owaneleyo kunye neengqimba zamandla kunye nesandwich i-wiring layer. Ngale ndlela, umphumo we-ripple kwi-crosstalk unokugcinwa ubuncinci kwaye ukuphazamiseka kwe-electromagnetic (EMI) kunokuncitshiswa kakhulu.

Kwinqanaba loyilo loyilo lwebhodi yesekethe, isicwangciso soyilo ngokuqhelekileyo ukubeka umgangatho omkhulu womhlaba kufuphi nomgangatho wokusabalalisa amandla. Oku kunokwenza isiphumo esisezantsi kakhulu sokukrazula, kwaye ingxolo yenkqubo inokuncitshiswa phantse ibero. Oku kubaluleke ngakumbi kwisixokelelwano samaza kanomathotholo.

Xa kuthelekiswa nezinto eziphathekayo zikaRogers, i-FR4 ine-dissipation factor ephezulu (i-Df), ngokukodwa kwi-frequency ephezulu. Ukusebenza okuphezulu kwe-FR4 laminates, ixabiso le-Df li malunga ne-0.002, i-odolo yobukhulu obungcono kune-FR4 eqhelekileyo. Nangona kunjalo, istaki sikaRogers si-0.001 kuphela okanye ngaphantsi. Xa izinto ze-FR4 zisetyenziselwa izicelo eziphezulu ze-frequency, kuya kubakho umehluko omkhulu ekulahlekeni kokufaka. Ukulahleka kokufakwa kuchazwa njengokulahlekelwa kwamandla kwesignali ukusuka kwindawo A ukuya kwindawo B xa usebenzisa i-FR4, iRogers okanye ezinye izinto.

ukudala iingxaki

I-PCB enxibayo ifuna ulawulo olungqongqo lwe-impedance. Le nto ibalulekileyo kwizixhobo ezinxitywayo. Ukulinganisa i-impedance kunokuvelisa ukuhanjiswa komqondiso ococekileyo. Ngaphambili, ukunyamezela okusemgangathweni kweempawu zokuphatha iimpawu kwakuyi-± 10%. Esi salathisi ngokucacileyo asilungile ngokwaneleyo kwimijikelezo yanamhlanje ephezulu kunye nesantya esiphezulu. Imfuno yangoku yi-±7%, kwaye kwezinye iimeko nokuba yi-±5% okanye ngaphantsi. Le parameter kunye nezinye izinto eziguquguqukayo ziyakuchaphazela kakhulu ukwenziwa kwezi PCBs zinxitywayo ngolawulo olungqongqo lwe-impedance, ngaloo ndlela kuncitshiswa inani lamashishini anokuwenza.

Ukunyamezelwa kwe-dielectric rhoqo kwe-laminate eyenziwe ngezinto ze-Rogers UHF kugcinwa ngokubanzi kwi-±2%, kwaye ezinye iimveliso zinokufikelela kwi-±1%. Ngokwahlukileyo, ukunyamezela rhoqo kwe-dielectric ye-FR4 laminate iphezulu njenge-10%. Ngoko ke, thelekisa Ezi zixhobo zimbini zinokufunyanwa ukuba ilahleko yokufaka uRogers iphantsi kakhulu. Xa kuthelekiswa nezinto zemveli zeFR4, ilahleko yothumelo kunye nokufakwa kwelahleko yesitaki sikaRogers sisezantsi ngesiqingatha.

Kwiimeko ezininzi, iindleko zezona zibalulekileyo. Nangona kunjalo, uRogers unokubonelela ngelahleko ephantsi-isantya esiphezulu sokusebenza kwe-laminate kwindawo yexabiso elamkelekileyo. Ukusetyenziswa kwezorhwebo, uRogers unokwenziwa kwi-PCB exubileyo ene-epoxy-based FR4, ezinye iileya ezisebenzisa izinto zikaRogers, kunye nezinye iileya zisebenzisa iFR4.

Xa ukhetha isitaki sikaRogers, ukuphindaphinda yeyona nto iphambili yokuqwalaselwa. Xa i-frequency idlula i-500MHz, abaqulunqi be-PCB badla ngokukhetha izinto zeRogers, ngakumbi kwiisekethe ze-RF/microwave, kuba ezi zixhobo zinokubonelela ngokusebenza okuphezulu xa imikhondo ephezulu ilawulwa ngokungqongqo yi-impedance.

Xa kuthelekiswa nezinto ze-FR4, izinto zeRogers zinokubonelela ngelahleko ephantsi ye-dielectric, kwaye i-dielectric rhoqo izinzileyo kwi-wide frequency range. Ukongeza, izinto zeRogers zinokubonelela ngelahleko ephantsi yokufakwa kokusebenza okufunwa kukusebenza okuphezulu.

I-coefficient yokwandiswa kwe-thermal (CTE) ye-Rogers 4000 series materials inozinzo oluhle kakhulu lwe-dimensional. Oku kuthetha ukuba xa kuthelekiswa ne-FR4, xa i-PCB idlula kwimijikelezo ebandayo, eshushu kwaye ishushu kakhulu i-reflow soldering, ukwandiswa kwe-thermal kunye nokunciphisa ibhodi yesekethe kunokugcinwa kumda ozinzileyo phantsi kwe-frequency ephezulu kunye nemijikelezo yokushisa ephezulu.

Kwimeko ye-stacking edibeneyo, kulula ukusebenzisa iteknoloji yenkqubo yokuvelisa eqhelekileyo ukuxuba i-Rogers kunye ne-FR4 yokusebenza okuphezulu kunye, ngoko ke kulula ukufezekisa isivuno esiphezulu sokuvelisa. Isitaki sikaRogers asifuni nto ikhethekileyo ngenkqubo yokulungiselela.

I-FR4 eqhelekileyo ayinakufezekisa ukusebenza kombane okuthembeke kakhulu, kodwa ukusebenza okuphezulu kwe-FR4 izixhobo zineempawu zokuthembeka ezilungileyo, ezinje nge-Tg ephezulu, isexabiso eliphantsi ngokwentelekiso, kwaye inokusetyenziswa kuluhlu olubanzi lwezicelo, ukusuka kuyilo olulula lomsindo ukuya kwi-Complex microwave applications. .

Iingqwalasela zoyilo lwe-RF/Microwave

Itekhnoloji ephathekayo kunye neBluetooth zivule indlela yeRF/microwave applications kwizixhobo ezinxitywayo. Uluhlu lwamaxesha anamhlanje luya lusiba namandla ngakumbi. Kwiminyaka embalwa edlulileyo, i-frequency ephezulu kakhulu (VHF) yayichazwa njenge-2GHz ~ 3GHz. Kodwa ngoku sinokubona usetyenziso lwe-ultra-high frequency (UHF) ukusuka kwi-10GHz ukuya kwi-25GHz.

Ke ngoko, kwiPCB enokunxitywa, inxalenye yeRF ifuna ingqwalasela ethe kratya kwimiba yocingo, kwaye iimpawu kufuneka zohlulwe ngokwahlukeneyo, kunye neetrayisi ezivelisa iisignali ze-frequency ephezulu kufuneka zigcinwe kude emhlabeni. Ezinye izinto eziqwalaselwayo ziquka: ukubonelela ngesihluzo sokugqitha, ii-capacitors zokuqhawula ezaneleyo, ukumisa umhlaba, kunye nokuyila umgca wothumelo kunye nomgca wokubuyela ukuba uphantse ulingane.

Isihluzo se-Bypass sinokucinezela impembelelo ye-ripple yomxholo wengxolo kunye ne-crosstalk. I-Decoupling capacitors kufuneka ibekwe kufutshane nezikhonkwane zesixhobo eziphethe imiqondiso yamandla.

Imigca yokuhanjiswa kwesantya esiphezulu kunye neesekethe zomqondiso zifuna umaleko womhlaba ukuba ubekwe phakathi kweempawu zomaleko wamandla ukugudisa i-jitter eyenziwe yimiqondiso yengxolo. Kwizantya zesignali eziphezulu, ukungahambelani okuncinci kwe-impedance kuya kubangela ukuhanjiswa okungalinganiyo kunye nokwamkelwa kwemiqondiso, okukhokelela ekugqwetheni. Ke ngoko, ingqwalasela eyodwa kufuneka ihlawulwe kwingxaki ehambelana ne-impedance ehambelana nesiginali yerediyo, kuba isignali yefrikhwensi yerediyo inesantya esiphezulu kunye nokunyamezela okukhethekileyo.

Iintambo zothumelo lweRF zifuna uthintelo olulawulwayo ukuze kudluliswe iisignali zeRF ukusuka kwi-IC substrate ethile ukuya kwiPCB. Ezi ntambo zothumelo zingaphunyezwa kumaleko angaphandle, umaleko ongaphezulu, kunye nomgangatho ongezantsi, okanye unokuyilwa kwinqanaba eliphakathi.

Iindlela ezisetyenziswa ngexesha loyilo lwe-PCB RF ngumgca we-microstrip, umgca womgca odadayo, i-coplanar waveguide okanye ukumisa umhlaba. Umgca we-microstrip uqukethe ubude obusisigxina betsimbi okanye umkhondo kunye nendiza yomhlaba wonke okanye inxalenye yendiza yomhlaba ngokuthe ngqo phantsi kwayo. I-impedance yeempawu kwisakhiwo somgca we-microstrip ngokubanzi ukusuka kwi-50Ω ukuya kwi-75Ω.

Umgca wentambo odadayo yenye indlela yocingo kunye nokuthomalalisa ingxolo. Lo mgca uqukethe i-wiring-width-width wiring kwi-layer yangaphakathi kunye ne-plane enkulu yomhlaba ngaphezulu nangaphantsi komqhubi weziko. Inqwelomoya ephantsi ifakwe phakathi kwenqwelomoya yamandla, ngoko inokubonelela ngesiphumo esisebenzayo somhlaba. Le yeyona ndlela ikhethwayo yokunxiba iingcingo zomqondiso we-PCB RF.

I-Coplanar waveguide inokubonelela ngokuzimela ngcono kufutshane nesekethe ye-RF kunye nesekethe ekufuneka ihanjiswe kufutshane. Esi siphakathi siqulathe i-conductor esembindini kunye neenqwelomoya eziphantsi macala omabini okanye ngaphantsi. Eyona ndlela ingcono yokusasaza iisiginali zerediyo kukunqumamisa imigca yemigca okanye i-coplanar waveguides. Ezi ndlela zimbini zinokubonelela ngokuzimela okungcono phakathi komqondiso kunye ne-RF traces.

Kucetyiswa ukuba kusetyenziswe into ebizwa ngokuba "ngocingo" kumacala omabini e-coplanar waveguide. Le ndlela inokubonelela ngomqolo we-vias yomhlaba kwiplani nganye yomhlaba yesinyithi yomqhubi weziko. Umkhondo ophambili ohamba phakathi uneecingo kwicala ngalinye, ngaloo ndlela unikezela indlela emfutshane yokubuyela kumhlaba ongezantsi. Le ndlela inokunciphisa inqanaba lengxolo elinxulunyaniswa nesiphumo somsindo omkhulu wophawu lweRF. I-dielectric constant ye-4.5 ihlala ifana ne-FR4 impahla ye-prepreg, ngelixa i-dielectric constant ye-prepreg-ukusuka kwi-microstrip, i-stripline okanye i-offset stripline-malunga ne-3.8 ukuya kwi-3.9.

Kwezinye izixhobo ezisebenzisa inqwelomoya ephantsi, i-vias eyimfama ingasetyenziselwa ukuphucula ukusebenza kwe-decoupling ye-capacitor yamandla kunye nokubonelela ngendlela ye-shunt ukusuka kwisixhobo ukuya emhlabeni. Indlela ye-shunt eya emhlabeni inokunciphisa ubude be-via. Oku kunokufezekisa iinjongo ezimbini: awugcini nje ukudala i-shunt okanye umhlaba, kodwa unciphisa umgama wokuhanjiswa kwezixhobo ezineendawo ezincinci, eyona nto ibalulekileyo yoyilo lweRF.