inye Ingqiqo esisiseko yokugqobhoza

Ngomngxuma (VIA) yinxalenye ebalulekileyo ye I-PCB ye-Multilayer, 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.

PCB ngokusebenzisa ingqiqo esisiseko umngxuma kunye ngokusebenzisa umngxuma indlela intshayelelo

Ukusuka kumbono woyilo, umngxuma wokutyhutyha ubukhulu becala uqulunqwe ngamacandelo amabini, enye ingumgodi wokubhobhoza phakathi, kwaye enye yindawo yepadi ejikeleze umngxuma wokugaya. 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 ukunciphisa ubungakanani bomngxuma ngexesha elifanayo kuzisa ukunyuka kweendleko, kwaye ubungakanani bomngxuma abunakuncitshiswa ngaphandle komda, bunqunyelwe ngokubhobhoza (ukubhobhoza) kunye nokucoca (i-plating) kunye nezinye itekhnoloji: encinci umngxuma, ixesha elide elithathayo ukubhola, kulula ukuphambuka kwindawo ephakathi; Xa ubunzulu bomngxunya bungaphezulu kwamaxesha ama-6 ubukhulu bomngxunya, akunakwenzeka ukuba kuqinisekiswe ukufana kobhedu lodonga lomngxuma. Umzekelo, ukuba ubukhulu (ngobunzulu bomngxuma) bebhodi yePCB ene-6-layer eqhelekileyo yi-50Mil, ngoko ke ubuncinci bedayamitha yomngxuma abanokubonelela ngayo ngabavelisi be-PCB yi-8Mil. Ngophuhliso lwetekhnoloji yokomba i-laser, ubungakanani bokomba bunokuba buncinci kwaye buncinci. Ngokubanzi, ububanzi bomngxuma bungaphantsi okanye bulingana ne-6Mils, siyibiza ngokuba yi-micro hole. I-Microholes isoloko isetyenziswa kwi-HDI (isakhiwo soxinaniso oluphezulu lwe-Interconnect) uyilo. Ithekhnoloji ye-Microhole ivumela umngxuma ukuba ubethe ngqo kwi-pad (VIA-in-pad), ephucula kakhulu ukusebenza kwesekethe kwaye igcine indawo yocingo.

Umngxuma wokutyhutyha kumgca wothumelo yindawo yokuphumla yokungaqhubeki kwe-impedance, eya kubangela ukubonakaliswa kwesignali. Ngokubanzi, uthintelo olulinganayo lomngxuma wokutyhutyha malunga ne-12% ngaphantsi kunalowo wentambo yothumelo. Ngokomzekelo, ukunyanzeliswa komgca wothumelo we-50ohm kuya kuncipha nge-6 ohm xa idlula kumngxuma wokutyhutyha (okuthile kukwanxulumene nobukhulu bomngxuma wokutyhutyha kunye nobukhulu beplate, kodwa hayi ukuncipha ngokupheleleyo). Nangona kunjalo, ukubonakaliswa okubangelwa ukupheliswa kokuphazamiseka ngomngxuma ngokwenene kuncinci kakhulu, kwaye i-coefficient yayo yokubonisa kuphela : (44-50) / (44 + 50) = 0.06. Iingxaki ezibangelwa ngumngxuma zijolise ngakumbi kwimpembelelo ye-parasitic capacitance kunye ne-inductance.

I-parasitic capacitance kunye ne-inductance ngokusebenzisa umngxuma

I-parasitic stray capacitance ikhona kumngxuma ngokwawo. Ukuba ububanzi bendawo yokumelana ne-welding yomngxuma kwi-laying layer yi-D2, ububanzi be-welding pad yi-D1, ubukhulu bebhodi ye-PCB yi-T, kwaye i-dielectric constant ye-substrate ngu-ε, i-parasitic capacitance umngxuma 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 obuyi-50Mil, ukuba i-diameter ye-pad-hole pad yi-20Mil (i-diameter ye-borehole yi-10Mils) kunye nobubanzi bebhloko ye-solder yi-40Mil, sinokuqikelela amandla e-parasitic umngxuma ophumela kwifomula engentla: C = 1.41 × 4.4 × 0.050 × 0.020/ (0.040-0.020) = 0.31pF utshintsho lwexesha lokunyuka olubangelwa yi-capacitance luba ngolu hlobo lulandelayo: T10-90 = 2.2c (Z0/2) = 2.2 × 0.31x (50/2) = 17.05ps Ukusuka kula maxabiso, kunokubonwa ukuba nangona umphumo wokunyuka kokulibaziseka kunye nokucotha okubangelwa yi-parasitic capacitance ye-single through- umngxuma awucacanga ncam, ukuba umngxuma wokutyhutyha usetyenziselwa ukutshintshela phakathi kweeleya amaxesha amaninzi, imingxunya emininzi iya kusetyenziswa. Lumka kuyilo lwakho. Kuyilo olusebenzayo, amandla e-parasitic capacitance anokuncitshiswa ngokwandisa umgama phakathi komngxunya kunye nendawo yokubeka ubhedu (i-anti-pad) okanye ngokunciphisa ububanzi bephedi. Kwi-design ye-high-speed ye-digital circuit, i-parasitic inductance of the through-hole iyingozi ngakumbi kune-capacitance ye-parasitic. Uluhlu lwayo lwe-parasitic inductance luya kulwenza buthathaka igalelo lokudlula kwamandla kunye nokunciphisa ukusebenza kokucoca kwenkqubo yamandla yonke. Singabala ngokulula i-parasitic inductance of the through-hole approximation sisebenzisa le fomula yeempirical ilandelayo: L=5.08h [ln (4h/d) +1]

Apho u-L ebhekiselele kwi-inductance yomngxuma, H bubude bomngxuma, kwaye u-D bububanzi bomngxuma osembindini. Ingabonakala kwi-equation ukuba ububanzi bomngxunya bunefuthe elincinci ekuqhubekeni, ngelixa ubude bomngxunya bunefuthe elikhulu ekuqhubekeni. Usasebenzisa lo mzekelo ungasentla, ukukhutshwa emngxunyeni kungabalwa ngolu hlobo:

L = 5.08 × 0.050 [ln (4 × 0.050 / 0.010) +1] = 1.015nh Ukuba ixesha lokunyuka kwesignali liyi-1ns, ngoko ubungakanani obulinganayo be-impedance bu: 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.

Isithathu, indlela yokusebenzisa umngxunya

Ngolu hlalutyo lungentla lweempawu zeparasitic kwimingxuma ephumela kwimingxuma, siyabona ukuba kuyilo lwePCB olunesantya esiphezulu, imingxunya ebonakala ilula idla ngokuzisa iziphumo ezibi kuyilo lwesekethe. Ukuze kuncitshiswe imiphumo emibi yempembelelo yeparasitic yomngxuma, sinokuzama ukwenza ngolu hlobo lulandelayo kuyilo:

1. Ukujonga ixabiso kunye nomgangatho womqondiso, kukhethwe ubungakanani bomngxunya ofanelekileyo. Ukuba kuyimfuneko, cinga ukusebenzisa ubukhulu obahlukeneyo bemingxuma. Ngokomzekelo, kumandla ombane okanye iintambo zomhlaba, cinga ukusebenzisa ubukhulu obukhulu ukunciphisa i-impedance, kunye ne-wiring yesignali, sebenzisa imingxuma emincinci. Ngokuqinisekileyo, njengoko ubungakanani bomngxuma buyancipha, iindleko ezihambelanayo ziya kunyuka.

2. Ezi fomula zimbini zixoxwe ngasentla zibonisa ukuba ukusetyenziswa kweebhodi zePCB ezibhityileyo kunceda ekunciphiseni iiparamitha ezimbini zeparasitic zokugqobhoza.

3. Ukufakelwa kweentambo zombane kwibhodi yePCB akufuneki kutshintshe iileya kangangoko kunokwenzeka, oko kukuthi, musa ukusebenzisa imingxunya engeyomfuneko kangangoko.

4. Izikhonkwane zonikezelo lwamandla kunye nomhlaba kufuneka ziqhutywe kumngxuma osondeleyo, kwaye ukukhokela phakathi komngxuma kunye nezikhonkwane kufuneka kube mfutshane ngokusemandleni. Imingxunya emininzi inokuqwalaselwa ngokuhambelanayo ukuze kuncitshiswe i-inductance efanayo.

5. Eminye imingxunya yomhlaba ibekwe kufutshane nemingxunya yokubeka umqondiso ukwenzela ukubonelela ngomtya osondeleyo wesiginali. 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.

6. Kuba iibhodi ngesantya esiphezulu PCB kunye ezixineneyo, micro – imingxunya ingaqwalaselwa.