Uyilo lwe i-PCB ephezulu yinkqubo enzima, kwaye izinto ezininzi zinokuchaphazela ngokuthe ngqo ukusebenza komsebenzi wesekethe ephezulu. Uyilo lwesekethe ephezulu kunye neengcingo zibaluleke kakhulu kuyilo lonke. Ezi ngcebiso zilishumi zilandelayo zoyilo lwe-PCB yesekethe ephezulu zicetyiswa ngakumbi:

1. Iintambo zebhodi ezininzi

Iisekethe eziphezulu ze-frequency zivame ukuba nokuhlanganiswa okuphezulu kunye nokuxinana kwee-wiring eziphezulu. Ukusetyenziswa kweebhodi ze-multi-layer akuyimfuneko kuphela kwi-wiring, kodwa kunye neendlela ezisebenzayo zokunciphisa ukuphazamiseka. Kwinqanaba le-PCB yoLuhlulo, ukhetho olufanelekileyo lwesayizi yebhodi eprintiweyo kunye nenani elithile leemaleko linokusebenzisa ngokupheleleyo umaleko ophakathi ukuseta ikhaka, ukuqonda ngcono isiseko esikufutshane, kunye nokunciphisa ngokufanelekileyo i-parasitic inductance kunye nokunciphisa umqondiso. ubude bokuhambisa, ngelixa ugcina ubuninzi Zonke ezi ndlela zinenzuzo ekuthembekeni kweesekethe eziphezulu ze-frequency, ezifana nokunciphisa i-amplitude ye-signal interference. Ezinye iinkcukacha zibonisa ukuba xa kusetyenziswa izinto ezifanayo, ingxolo yebhodi ene-four-layer i-20dB ephantsi kunaleyo yebhodi ephindwe kabini. Nangona kunjalo, kukwakho ingxaki. Okukhona liphezulu inani le-PCB enesiqingatha-amaleya, kokukhona intsonkothe ​​ngakumbi inkqubo yokwenziwa kwemveliso, kwaye kokukhona ixabiso leyunithi liphezulu. Oku kufuna ukuba sikhethe iibhodi zePCB ezinenani elifanelekileyo lomaleko xa sisenza uYilo lwePCB. Isicwangciso soyilo lwecandelo olufanelekileyo, kwaye usebenzise imithetho echanekileyo yocingo ukugqibezela uyilo.

2. Okukhona ilothe igoba kancinci phakathi kwezikhonkwane zezixhobo zombane ezinesantya esiphezulu, kokukhona kungcono

Intambo ekhokelayo ye-high-frequency circuit wiring ingcono ukuthabatha umgca ochanekileyo opheleleyo, omele uguqulwe. Inokuguqulwa ngumgca we-45-degree ephukileyo okanye i-arc ejikelezayo. Le mfuneko isetyenziselwa kuphela ukuphucula amandla okulungisa i-foil yobhedu kwiisekethe eziphantsi-frequency, ngelixa kwiisekethe eziphezulu, le mfuneko idibene. Enye imfuneko inokunciphisa ukukhutshwa kwangaphandle kunye nokudibanisa okufanayo kweempawu ze-high-frequency.

3. Imfutshane isikhokelo phakathi kwezikhonkwane zesixhobo sesekethe esiphezulu, kungcono

Ubunzulu bemitha yophawu bulingana nobude bomkhondo womgca wophawu. Okukhona umqondiso we-high-frequency ukhokelela, kokukhona kulula ukudibanisa kumacandelo akufutshane nawo. Ngoko ke, iwashi yesignali, i-crystal oscillator, idatha ye-DDR, imigca ye-LVDS, imigca ye-USB, imigca ye-HDMI kunye neminye imigca yesignali ye-high-frequency kufuneka ibe mfutshane kangangoko kunokwenzeka.

4. Okukhona umaleko okhokelayo utshintshana phakathi kwezikhonkwane zesixhobo sesekethe esinesantya esiphezulu, kokukhona kungcono.

Oko kubizwa ngokuba “kuncinci ukutshintshiselana kwe-inter-layer ye-lead, kungcono” kuthetha ukuba i-vias encinci (i-Via) esetyenziswe kwinkqubo yokudibanisa icandelo, ingcono. Ngokutsho kwecala, enye nge-via inokuzisa malunga ne-0.5pF i-capacitance esasazwayo, kwaye ukunciphisa inani le-vias kunokunyusa kakhulu isantya kunye nokunciphisa amathuba okuba neempazamo zedatha.

5. Nika ingqalelo kwi-“crosstalk” eyaziswa ngumgca wesignali kwi-route parallel close

I-wiring ye-high-frequency circuit wiring kufuneka ihlawule ingqalelo kwi-“crosstalk” evezwe ngokusondeleyo kwi-parallel routing yemigca yesignali. I-Crosstalk ibhekisa kwinto yokudibanisa phakathi kwemigca yemiqondiso engadityaniswanga ngokuthe ngqo. Kuba imiqondiso ye-frequency ephezulu ihanjiswa ngendlela yamaza e-electromagnetic ecaleni komgca wothumelo, umgca wesiginali uya kusebenza njenge-eriyali, kwaye amandla ommandla we-electromagnetic aya kukhutshwa kumgca wothumelo. Imiqondiso yengxolo engafunekiyo yenziwa ngenxa yokudityaniswa kwemimandla ye-electromagnetic phakathi kwemiqondiso. Ebizwa ngokuba yi-crosstalk (Crosstalk). Iiparameters ze-PCB layer, izithuba zemigca yesignali, iimpawu zombane zesiphelo sokuqhuba kunye nesiphelo sokufumana, kunye nendlela yokuphelisa umgca wesignali zonke zinempembelelo ethile kwi-crosstalk. Ke ngoko, ukuze kuncitshiswe i-crosstalk yeempawu ze-frequency ephezulu, kufuneka wenze oku kulandelayo kangangoko kunokwenzeka xa ufaka iingcingo:

Ukuba indawo yocingo ivumela, ukufaka ucingo lomhlaba okanye inqwelomoya ephantsi phakathi kweengcingo ezimbini ezine-crosstalk enzulu inokudlala indima yodwa kunye nokunciphisa i-crosstalk. Xa kukho intsimi ye-electromagnetic eguquguqukayo yexesha kwindawo ejikeleze umgca wesignali, ukuba ukuhanjiswa okuhambelanayo akunakuthintelwa, indawo enkulu “yomhlaba” inokulungiswa kwelinye icala lomgca wesignali ehambelanayo ukunciphisa kakhulu ukuphazamiseka.

Ngaphantsi kwesizathu sokuba i-wiring space ivumela, ukwandisa isithuba phakathi kwemigca yesignali esondeleyo, ukunciphisa ubude obufanayo bemigca yesignali, kwaye uzame ukwenza umgca wewashi ulungelelanise umgca wesignali obalulekileyo endaweni ye-parallel. Ukuba i-wiring ehambelanayo kwinqanaba elifanayo liphantse lingenakuphepheka, kwiindawo ezimbini ezikufutshane, izikhokelo ze-wiring kufuneka zibe perpendicular omnye komnye.

Kwiisekethe zedijithali, imiqondiso yewotshi eqhelekileyo yimiqondiso enotshintsho olukhawulezayo, olune-crosstalk yangaphandle ephezulu. Ngoko ke, kuyilo, umgca wewashi kufuneka ujikelezwe ngumgca womhlaba kwaye ubethe imingxuma engaphezulu yomhlaba ukuze kuncitshiswe i-capacitance eyabiwayo, ngaloo ndlela ukunciphisa i-crosstalk. Kwiiwotshi zomqondiso we-high-frequency, zama ukusebenzisa i-low-voltage differential clock signals kwaye usonge imowudi yomhlaba, kwaye ubeke ingqalelo kwingqibelelo ye-package punching yomhlaba.

I-terminal yokufaka engasetyenziswanga akufuneki inqunyanyiswe, kodwa isekelwe phantsi okanye iqhagamshelwe kunikezelo lwamandla (unikezelo lwamandla lukwasekelwe kwi-loop ye-high-frequency signal loop), kuba umgca omisiweyo unokulingana ne-eriyali yokudlulisa, kwaye umhlaba unokunqanda. ukukhutshwa. Ukuziqhelanisa kubonise ukuba ukusebenzisa le ndlela yokuphelisa i-crosstalk ngamanye amaxesha kunokuvelisa iziphumo ezikhawulezayo.

6. Yongeza i-high-frequency decoupling capacitor kwi-pin yonikezelo lwamandla kwibhloko yesekethe edibeneyo

I-capacitor ye-high-frequency decoupling capacitor yongezwa kwi-pin yonikezelo lwamandla kwibhloko nganye yesiphaluka edibeneyo ekufutshane. Ukwandisa i-high-frequency decoupling capacitor ye-pin yonikezelo lwamandla inokucinezela ngokufanelekileyo ukuphazamiseka kwe-harmonics ye-high-frequency kwi-pin yonikezelo lwamandla.

7. Ukwahlula ucingo oluphantsi lwe-high-frequency digital signal kunye ne-analog signal ground wire

Xa ucingo olusemhlabeni lwe-analog, ucingo olusemhlabeni lwedijithali, njl.njl. luqhagamshelwe kucingo olusemhlabeni lukawonke-wonke, sebenzisa amaso amazibuthe aminxekayo aphezulu-frequency ukudibanisa okanye ukwahlula ngokuthe ngqo kwaye ukhethe indawo efanelekileyo yoqhagamshelo lwenqaku elinye. Amandla omhlaba wocingo oluphantsi lwesignali yedijithali ye-high-frequency ayihambelani ngokubanzi. Kuhlala kukho umahluko othile wombane phakathi kwezi zimbini ngokuthe ngqo. Ngaphezu koko, ucingo oluphantsi lwesignali yedijithali ye-high-frequency ihlala iqulethe amacandelo atyebileyo kakhulu e-harmonic yesiginali ye-frequency ephezulu. Xa i-digital signal ye-ground wire kunye ne-analog signal ground wire idibaniswe ngokuthe ngqo, i-harmonics ye-high-frequency signal iya kuphazamisa umqondiso we-analog ngokusebenzisa ukudibanisa ucingo lomhlaba. Ngoko ke, phantsi kweemeko eziqhelekileyo, ucingo olusezantsi lwe-high-frequency digital signal kunye nocingo oluphantsi lwesignali ye-analog kufuneka lube lodwa, kwaye indlela yokudibanisa i-single-point ingasetyenziselwa kwindawo efanelekileyo, okanye indlela ephezulu-yaphezulu. Uqhagamshelo lwe-frequency choke magnetic bead lungasetyenziswa.

8. Gwema iilophu ezenziwe ngocingo

Zonke iintlobo zeempawu zophawu oluphezulu akufunekanga zenze i-loop kangangoko kunokwenzeka. Ukuba ayinakuphepheka, indawo ye-loop kufuneka ibe yincinci kangangoko.

9. Kufuneka iqinisekise ukuhambelana kophawu lokuthintela

Kwinkqubo yokuhanjiswa kwesignali, xa i-impedance ingahambelani, isignali iya kubonakalisa kwisiteshi sokuhambisa, kwaye ukubonakalisa kuya kubangela ukuba isignali edibeneyo yenze i-overshoot, ebangela ukuba umqondiso uguquguquke kufuphi nomda we-logic.

Indlela esisiseko yokuphelisa ukubonakaliswa kukuhambelana kakuhle nokuphazamiseka kwesiginali yothumelo. Ekubeni mkhulu umehluko phakathi kokuphazamiseka komthwalo kunye nokuphazamiseka kweempawu zomgca wokuhambisa, ukubonakalisa okukhulu, ngoko ke ukuxhatshazwa kweempawu zomgca wokuhambisa umqondiso kufuneka zenziwe zilingane nomthwalo womthwalo kangangoko kunokwenzeka. Kwangaxeshanye, nceda uqaphele ukuba umgca wothumelo kwi-PCB awunakuba notshintsho okanye iikona ngesiquphe, kwaye uzame ukugcina i-impedance yendawo nganye yomzila wothumelo ngokuqhubekayo, ngaphandle koko kuya kubakho ukubonakaliswa phakathi kwamacandelo ahlukeneyo omgca wothumelo. Oku kufuna ukuba ngexesha le-PCB enesantya esiphezulu, le migaqo yocingo ilandelayo kufuneka igcinwe:

Imithetho yocingo lwe-USB. Ifuna indlela yokwahluka komqondiso we-USB, ububanzi bomgca yi-10mil, isithuba somgca yi-6mil, kunye nomgca osezantsi kunye nesithuba somgca wesignali yi-6mil.

Imithetho yocingo lweHDMI. I-HDMI yokuhlukanisa umzila wesignali iyadingeka, ububanzi bomgca yi-10mil, ukuchithwa komgca ngu-6mil, kunye nesithuba phakathi kweeseti ezimbini ze-HDMI izibini ezihlukeneyo zesignali zidlula i-20mil.

Imithetho yokufaka iintambo ze-LVDS. Ifuna i-LVDS indlela yokwahlukana komqondiso, ububanzi bomgca yi-7mil, isithuba somgca yi-6mil, injongo kukulawula ukunyanzeliswa kwesignali ye-HDMI kwi-100 + -15% ohm.

Imithetho yocingo lweDDR. Iimpawu ze-DDR1 zifuna ukuba iimpawu zingadluli kwimingxunya kangangoko kunokwenzeka, imigca yesignali inobubanzi obulinganayo, kwaye imigca ihlukaniswe ngokulinganayo. Umkhondo kufuneka uhlangabezane nomgaqo we-2W ukunciphisa i-crosstalk phakathi kweempawu. Kwizixhobo ezikhawulezayo ze-DDR2 nangaphezulu, idatha ye-frequency ephezulu nayo iyafuneka. Imigca ilingana ngobude ukuze kuqinisekiswe ukuhambelana kwe-impedance yesignali.

10. Qinisekisa ukuthembeka kosulelo

Gcina ingqibelelo yokuhanjiswa kwesignali kwaye uthintele “i-bounce phenomenon yomhlaba” ebangelwa ukuhlukana komhlaba.