Kwinkqubo yoyilo lwePCB, ezinye iinjineli azifuni ukubeka ubhedu kuwo wonke umphezulu womaleko ongezantsi ukuze wonge ixesha.Ngaba oku kuchanekile?Ngaba iPCB kufuneka ifakwe ubhedu?
Okokuqala, kufuneka sicace: i-copper plating ephantsi inenzuzo kwaye iyimfuneko kwi-PCB, kodwa ukufakwa kobhedu kwibhodi yonke kufuneka kuhlangabezane neemeko ezithile.
Iingenelo zokubeka ubhedu olusezantsi
1. Ukususela kumbono we-EMC, yonke indawo yomgangatho ongezantsi ihlanganiswe ngobhedu, enika ukhuseleko olongezelelweyo lokukhusela kunye nokunciphisa ingxolo yesignali yangaphakathi kunye nesignali yangaphakathi.Ngelo xesha, ikwanalo ukhuseleko oluthile lokukhusela izixhobo eziphantsi kunye neempawu.
2. Ukusuka kwimbono yokutshatyalaliswa kobushushu, ngenxa yokwanda kwangoku kwi-PCB yebhodi yoxinaniso, i-chip ephambili ye-BGA nayo ifuna ukuqwalasela imiba yokutshatyalaliswa kobushushu ngakumbi nangaphezulu.Ibhodi yesekethe yonke isekelwe ngobhedu ukuphucula amandla okutshatyalaliswa kobushushu bePCB.
3. Ukusuka kwindawo yokujonga inkqubo, ibhodi yonke isekelwe ngobhedu ukwenza ibhodi yePCB isasazwe ngokulinganayo.PCB ukugoba kunye warping kufuneka kuphetshwe ngexesha PCB processing kunye nocinezelo.Kwangaxeshanye, uxinzelelo olubangelwa yi-PCB reflow soldering aluyi kubangelwa yifoyile yobhedu engalinganiyo.PCB warpage.
Isikhumbuzi: Kwiibhodi ezimbini zeebhodi, i-copper copper iyafuneka
Ngakolunye uhlangothi, ngenxa yokuba ibhodi enemigangatho emibini ayinayo i-plane epheleleyo yokubhekisela, umhlaba owenziweyo unokubonelela ngendlela yokubuya, kwaye unokusetyenziswa njengereferensi ye-coplanar ukufezekisa injongo yokulawula i-impedance.Ngokuqhelekileyo sinokubeka i-plane yomhlaba kwinqanaba elisezantsi, kwaye emva koko sibeke amacandelo aphambili kunye nemigca yamandla kunye nemigca yesignali kwinqanaba eliphezulu.Kwiisekethe eziphezulu ze-impedance, ii-analog circuits (i-analog-to-digital conversion circuits, switch-mode mode convertion circuits), i-copper plating ngumkhwa omhle.
Iimeko zokufakwa kobhedu phantsi
Nangona umaleko ongezantsi wobhedu uyilungele kakhulu iPCB, usafuna ukuhlangabezana neemeko ezithile:
1. Beka kangangoko kunokwenzeka ngexesha elifanayo, musa ukugubungela zonke kanye kanye, ugweme ulusu lobhedu ekuqhekekeni, kwaye ungeze ngemingxuma kwinqanaba lomhlaba wendawo yobhedu.
Isizathu: Umaleko wobhedu kuluhlu lwangaphezulu kufuneka uphulwe kwaye utshatyalaliswe ngamacandelo kunye nemigca yesiginali kumgangatho ongaphezulu.Ukuba i-foil yobhedu ayisekelwanga kakuhle (ingakumbi i-foil ebhityileyo kunye nede yobhedu yaphukile), iya kuba yi-eriyali kwaye ibangele iingxaki ze-EMI.
2. Qwalasela ibhalansi ye-thermal yeepakethe ezincinci, ngakumbi iipakethe ezincinci, ezinje nge-0402 0603, ukuphepha iziphumo ezinkulu.
Isizathu: Ukuba ibhodi yesiphaluka yonke i-copper-plated, ubhedu lwezikhonkwane zecandelo luya kudibaniswa ngokupheleleyo nobhedu, oluya kubangela ukuba ukushisa kuqhume ngokukhawuleza, okuya kubangela ubunzima bokuchithwa kunye nokusebenza kwakhona.
3. Ukubekwa phantsi kwayo yonke ibhodi yesekethe ye-PCB kukhethwa ukuba kuqhutywe ngokuqhubekayo.Umgama ukusuka kumhlaba ukuya kumqondiso kufuneka ulawulwe ukuze ugweme ukuyeka ukungabikho kwi-impedance yomzila wokuhambisa.
Isizathu: Iphepha lobhedu lisondele kakhulu emhlabeni liya kutshintsha i-impedance ye-microstrip transmission line, kunye neshidi lobhedu elingapheliyo liya kuba nefuthe elibi kwi-impedance discontinuity yomzila wothumelo.
4. Ezinye iimeko ezizodwa zixhomekeke kwimeko yesicelo.Uyilo lwePCB akufuneki lube luyilo olupheleleyo, kodwa kufuneka lulinganiswe kwaye ludityaniswe neethiyori ezahlukeneyo.
Isizathu: Ukongeza kwiimpawu ezibucayi ezifuna ukusekwa, ukuba kukho imigca yesignali yesantya esiphezulu kunye namacandelo, inani elikhulu lekhefu elincinci kunye nexesha elide lobhedu liya kuveliswa, kwaye iziteshi zocingo ziqinile.Kuyimfuneko ukuba ugweme imingxuma emininzi yobhedu phezu komhlaba ngokusemandleni ukudibanisa kumgangatho womhlaba.Umaleko womphezulu unokuzikhethela ngaphandle kobhedu.