Ukukhetha kwe PCB ubuchwepheshe bokumboza indawo engaphezulu ye-SMT soldering ekucubunguleni kwe-SMT ikakhulukazi kuncike ohlotsheni lwezingxenye zokugcina ezihlanganisiwe, futhi inqubo yokwelashwa okungaphezulu izothinta ukukhiqizwa, ukuhlanganisa kanye nokusetshenziswa kokugcina kwe-PCB. Okulandelayo kwethula kafushane isisekelo sokukhetha se-PCB solderability surface coating.

Lapho ukhetha i-solderable surface coating ye-PCB ekucubungulweni kwe-patch, ukwakheka kwe-alloy ekhethiwe ekhethiwe kanye nokusetshenziswa komkhiqizo kufanele kucatshangelwe.

1. Ukwakheka kwe-alloy ye-solder

Ukuhambisana kwe-PCB pad coating kanye ne-solder alloy kuyisici esiyinhloko ekukhetheni i-PCB solderable surface coating (plating). Lokhu kuthinta ngokuqondile ukuthengiselana nokuthembeka kokuxhumeka kwamalungu e-solder ezinhlangothini zombili zephedi. Isibonelo, ukulinganisa komoya oshisayo we-Sn-Pb kufanele kukhethelwe ingxubevange ye-Sn-pb, futhi ukulinganisa komoya oshisayo wensimbi engenamthofu noma ingxube ye-solder engenamthofu kufanele kukhethwe ingxubevange engenamthofu.

2. Izidingo zokwethembeka

Imikhiqizo enezidingo ezithembeke kakhulu kufanele iqale ikhethe izinga elifanayo lomoya oshisayo njenge-solder alloy, okuyisinqumo esingcono kakhulu sokuhambisana. Ngaphezu kwalokho, izinga eliphezulu le-Ni-Au (ENIG) lingabuye licatshangelwe, ngoba amandla okuxhumeka kwe-alloy interface Ni3Sn4 phakathi kwe-Sn ne-Ni yiwona ozinzile kakhulu. Uma i-ENIG isetshenziswa, isendlalelo se-Ni kumele silawulwe sibe> 3 µm (5 kuya ku-7 µm), futhi isendlalelo se-Au kumele sibe ngu-≤ 1 µm (0.05 kuya ku-0.15 µm), futhi izidingo zokuthengiswa kufanele zibekwe phambili kumkhiqizi.

3. Inqubo yokukhiqiza

Lapho ukhetha isendlalelo se-PCB solderable surface coating (plating), ukuhambisana kwe-PCB pad coating layer kanye nenqubo yokukhiqiza nakho kufanele kubhekwe. I-Hot air leveling (HASL) inokushisela okuhle, ingasetshenziselwa ukushisela kabusha okunezinhlangothi ezimbili, futhi ingamelana nokushisela okuningi. Kodwa-ke, njengoba ingaphezulu lephedi lingasicaba ngokwanele, alifanelekile iphimbo elincane. I-OSP kanye ne-immersion tin (I-Sn) ifaneleka kakhulu ukuhlanganisa okunohlangothi olulodwa kanye nenqubo yesikhathi esisodwa yokudambisa.