Ngomngxuma (VIA) yinxalenye ebalulekileyo ye multilayer PCB, kunye neendleko zokumba imingxunya zihlala zibalelwa kwi-30% ukuya kwi-40% yeendleko zokwenza ibhodi ye-PCB. Ukubeka ngokulula, yonke imingxunya kwiPCB ibizwa ngokuba ngumngxuma wokupasa. Ngokomsebenzi, umngxunya unokwahlulwa ube ziindidi ezimbini: enye isetyenziselwa unxibelelwano lombane phakathi kweendlela; Enye isetyenziselwa ukulungiswa kwesixhobo okanye ukubeka indawo.

Ngokwenkqubo, le mingxunya igqobhoziweyo yahlulwe yangamacandelo amathathu, oko kukuthi, iimfama ziyadlula, kungcwatywa ngokugqitha. Imingxunya engaboniyo ibekwe kwindawo ephezulu nasezantsi kwibhodi yesekethe eprintiweyo kwaye inobunzulu obuthile bokuqhagamshela isekethe yomphezulu kwisekethe yangaphakathi engezantsi. Ubunzulu bemingxunya ngokuqhelekileyo abudluli kumyinge othile (ukuvula). Imingxunya engcwatyelweyo yimingxunya yoqhagamshelo kumaleko angaphakathi ebhodini yesekethe eprintiweyo engafikeleli kumphezulu webhodi yesekethe eprintiweyo. Ezi ndidi zimbini zemingxunya zibekwe kumaleko angaphakathi ebhodi yesekethe, egqityiweyo yinkqubo yokubumba engaphakathi ngaphambi kokufakwa, kwaye uninzi lwangaphakathi lunokugqunywa ngexesha lokwakheka komngxunya. Uhlobo lwesithathu, olubizwa ngokuba yimingxunya, luhamba kuyo yonke ibhodi yesekethe kwaye inokusetyenziselwa unxibelelwano lwangaphakathi okanye njengokufaka nokufumana imingxunya yezinto. Ngenxa yokuba umngxuma kulula ukuwuphumeza kwinkqubo, iindleko ziphantsi, ngenxa yoko uninzi lweebhodi zesekethe eziprintiweyo ziyayisebenzisa, endaweni yokuba zisebenzise ezinye iintlobo ezimbini zomngxunya. Oku kulandelayo ngemingxunya, ngaphandle kwengcaciso ekhethekileyo, kuya kuqwalaselwa njengemingxunya.

Wazi ntoni malunga umngxuma uyilo PCB

Ukusuka kwindawo yokuyila, umngxunya ojikelezwe ikakhulu unamalungu amabini, omnye ngumngxunya wokugrobo embindini kunye nomnye yindawo yedatha ejikeleze umngxunya wokugrumba, njengoko kubonisiwe kumfanekiso ongezantsi. Ubungakanani bala macandelo mabini buchaza ubungakanani bomngxunya ogqobhoziweyo. Ngokucacileyo, kuyilo lwesantya esiphezulu, i-PCB exineneyo, umyili uhlala efuna ukuba umngxunya ube mncinci ngangokunokwenzeka, le sampulu inokushiya indawo yokubamba, ukongeza, umngxunya omncinci, amandla ayo okusasaza amancinci, ngakumbi ilungele isantya sokujikeleza. Kodwa ubukhulu bomngxunya buyancipha kwangaxeshanye buzisa ukwanda kweendleko, kwaye ubukhulu bomngxuma abunakuncitshiswa ngaphandle komda, bunqunyelwe ngokugrumba (ukubhola) kunye nesingxobo (ukutyabeka) kunye nenye itekhnoloji: encinci umngxunya, ixesha elide ukuthatha ukubhola, kulula ngakumbi ukuphambuka embindini; Xa ubunzulu bomngxunya bungaphezulu kwamaxesha ama-6 ubukhulu bomngxunya, akunakwenzeka ukuba kuqinisekiswe ukufana kobhedu lodonga lomngxuma. Umzekelo, ubukhulu obuqhelekileyo obuqhelekileyo (ngokujula komngxunya) webhodi ye-PCB engama-6 imalunga ne-50Mil, ke ubuncinci bokubhola ubukhulu obunokubonelelwa ngabavelisi be-PCB kunokufikelela kwi-8Mil kuphela. Ukuqina komngxunya womngxunya ngokwawo ukhona emhlabeni, ukuba ubukhulu bomngxunya wokuzahlula bungu-D2, ubukhulu bephedi yomngxunya yi-D1, ubukhulu bebhodi ye-PCB yi-T, kunye ne-dielectric engapheliyo ye-substrate yi-ε, amandla e-parasitic embobo umalunga ne: C = 1.41εTD1 / (D2-D1)

Iziphumo eziphambili ze-parasitic capacitance kwisekethe kukwandisa ixesha lokunyuka komqondiso kunye nokunciphisa isantya sesekethe. Umzekelo, kwibhodi ye-PCB enobunzima be-50Mil, ukuba ubukhulu bangaphakathi bomngxunya yi-10Mil, ububanzi bephedi yi-20Mil, kunye nomgama phakathi kwephedi kunye nomgangatho wobhedu yi-32Mil, sinokuqikelela amandla e-parasitic capacitance womngxunya ngokusebenzisa le fomyula ingentla: C = 1.41 × 4.4 × 0.050 × 0.020 / (0.032-0.020) = 0.517pF, ukungafani kwexesha lokunyuka okubangelwa yile nxalenye ye-capacitance yile: T10-90 = 2.2C (Z0 / 2) = 2.2 × 0.517x (55 / 2) = 31.28ps. Ukusuka kula maxabiso, kuyacaca ukuba nangona amandla e-parasitic capacitance ukusuka kumngxunya omnye kulibaziseko lokunyuka akucaci, abayili kufuneka balumke ukuba kusetyenziswe imingxunya emininzi kulungelelwaniso lolwaleko.

Kuyilo lweesekethe zedijithali ezihamba ngesantya esiphezulu, ukumiliselwa kwe-parasitic ye-infasiti yokungena emngxunyeni kuhlala kukhulu kunefuthe lobuchule be-parasitic capacitance. Uluhlu lwayo lwe-parasitic inductance luya kulwenza buthathaka igalelo lokudlula kwamandla kunye nokunciphisa ukusebenza kokucoca kwenkqubo yamandla yonke. Sinokubala ngokulula ukunganyanzeleki kwe-parasitic yomngxunya wokugqobhoza ngokusebenzisa le fomyula ilandelayo: L = 5.08h [ln (4h / d) +1] apho L ibhekisa ekungeneni ngemingxunya, h ubude bokudlula- umngxuma, kunye no-D bububanzi bomngxuma ophakathi. Ingabonakala kwi-equation ukuba ububanzi bomngxunya bunefuthe elincinci ekuqhubekeni, ngelixa ubude bomngxunya bunefuthe elikhulu ekuqhubekeni. Usasebenzisa lo mzekelo ungasentla, ukukhutshwa emngxunyeni kungabalwa njengo-L = 5.08 × 0.050 [ln (4 × 0.050 / 0.010) +1] = 1.015nh. Ukuba ixesha lokunyuka komqondiso li-1ns, ke ubungakanani be-impedance efanayo: XL = πL / T10-90 = 3.19 ω. Esi sithintelo asinakuhoywa kubukho bevolthi ephezulu yangoku. Ngokukodwa, i-bypass capacitor kufuneka idlule kwimingxunya emibini ukuze idibanise umaleko wokubonelela ekubunjweni, ngaloo ndlela iphinda-phindwe kabini ukunganyangeki kwemingxunya.

Ngolu hlalutyo lungentla lweempawu zokuphazamiseka emngxunyeni, sinokubona ukuba kuyilo olukhawulezayo lwePCB, umngxunya obonakala ulula uhlala uzisa iziphumo ezibi kuyilo lwesekethe. Ukwenzela ukunciphisa iziphumo ezibi zomngxunya, singenza kangangoko kuyilo: 1. Ukusuka kwimiba emibini yexabiso kunye nomgangatho womqondiso, khetha ubungakanani obufanelekileyo bomngxunya. Umzekelo, iileyile ezi-6 ukuya kwezi-10 zemodyuli yeMemori ye-MEMORY, kungcono ukhethe i-10 / 20mil (ukubhola / iphedi) ngomngxunya, kwibhodi encinci yesayizi ephezulu, unokuzama ukusebenzisa i-8 / 18mil nge umngxuma. Ngobuchwephesha bangoku, kunganzima ukusebenzisa imingxunya emincinci. Ukunikezelwa kwamandla okanye ucingo lomhlaba ngemingxuma kunokuqwalaselwa ukusebenzisa ubungakanani obukhulu ukunciphisa impedance.

2. Iifomula ezimbini ekuxoxwe ngazo ngasentla zibonisa ukuba ukusetyenziswa kweebhodi zePCB ezincinci kunceda ukunciphisa iiparameter ezimbini zemingxunya ngemingxunya.

3. iintambo zombane kwibhodi ye-PCB akufuneki zitshintshe umaleko kangangoko kunokwenzeka, oko kukuthi, zama ukungasebenzisi imingxunya engeyomfuneko.

4. Izikhonkwane zonikezelo lwamandla kunye nomhlaba kufuneka kugrunjwe kufutshane. Ngokufutshane ukukhokela phakathi kwezikhonkwane kunye nemingxunya, kungcono, kuba ziya kukhokelela ekwandeni kokunyanzelwa. Kwangelo xesha, amandla kunye nomhlaba okhokelayo kufuneka ubemkhulu kangangoko ukunciphisa impedance.

5. Beka imingxunya yokubeka umhlaba kufutshane nemingxunya yotshintsho lomaleko womqondiso ukuze unikeze iluphu ekufuphi kumqondiso. Unokubeka imingxunya emininzi eyongezelelweyo kwi-PCB. Ewe kunjalo, kufuneka ubhetyebhetye kuyilo lwakho. Imodeli yokufaka umngxuma oxutyushwe ngasentla yimeko apho kukho iipads kulwahlulo ngalunye. Ngamanye amaxesha, sinokunciphisa okanye sisuse iipads kwezinye iindlela. Ngokukodwa kwimeko yokuxinana komngxunya kukhulu kakhulu, kunokukhokelela ekwenziweni kwe-groove yesekethe enqamlekileyo kumaleko wobhedu, ukusombulula ingxaki enjalo ukongeza ekususeni indawo yomngxunya, sinokujonga umngxunya Uluhlu lobhedu ukunciphisa ubungakanani bephedi.