Ukukhetha kwe PCB itekhnoloji yokwaleka komphezulu we-SMT soldering kwi-SMT processing ikakhulu ixhomekeke kuhlobo lwamacandelo adityanisiweyo okugqibela, kwaye inkqubo yonyango lomphezulu iya kuchaphazela ukuveliswa, ukudibanisa kunye nokusetyenziswa kokugqibela kwe-PCB. Oku kulandelayo sazisa ngokufutshane isiseko sokhetho lwePCB solderability surface coating.

Xa ukhetha i-solderable surface coating ye-PCB kwi-patch processing, ukubunjwa kwe-alloy ekhethiweyo ye-solder kunye nokusetyenziswa kwemveliso kufuneka kuthathelwe ingqalelo.

1. Ukuqulunqwa kwe-alloy ye-Solder

Ukuhambelana kwe-PCB pad yokwambathisa kunye ne-solder alloy yeyona nto iphambili ekukhetheni i-PCB ethengisiweyo yokwaleka komhlaba (i-plating). Oku kuchaphazela ngokuthe ngqo ukuthengiswa kunye nokuthembeka koxhumo lwamalungu e-solder kumacala omabini e-pad. Ngokomzekelo, umgangatho womoya oshushu we-Sn-Pb kufuneka ukhethwe kwi-alloy ye-Sn-pb, kunye ne-hot air leveling ye-lead-free metal okanye i-lead-free solder alloy kufuneka ikhethwe kwi-alloy-free alloy.

2. Iimfuno zokuthembeka

Iimveliso ezineemfuno eziphezulu zokuthembeka kufuneka ziqale zikhethe umgangatho ofanayo womoya oshushu njenge-alloy ye-solder, eyona nto ikhethekileyo yokuhambelana. Ukongezelela, umgangatho ophezulu we-Ni-Au (ENIG) unokuqwalaselwa kwakhona, kuba amandla okudibanisa i-alloy interface ye-Ni3Sn4 phakathi kwe-Sn kunye ne-Ni yeyona nto izinzile. Ukuba i-ENIG isetyenzisiwe, i-Ni layer kufuneka ilawulwe ibe> 3 µm (5 ukuya ku-7 µm), kwaye umaleko we-Au kufuneka ube ngu-≤ 1 µm (0.05 ukuya ku-0.15 µm), kunye neemfuno zokuthengiswa kufuneka zibekwe phambili kumenzi.

3. Inkqubo yokuvelisa

Xa ukhetha PCB solderable umphezulu ukutyabeka (plating) umaleko, ukuhambelana PCB pad umaleko ukutyabeka kunye nenkqubo yokuvelisa kufuneka kwakhona kuqwalaselwe. Umgangatho womoya oshushu (HASL) une-weldability elungileyo, ingasetyenziselwa ukuwelda okuphindwe kabini, kwaye inokumelana ne-welding ezininzi. Nangona kunjalo, ekubeni umphezulu we-pad awukho flat ngokwaneleyo, ayifanelekanga kwi-pitch emxinwa. I-OSP kunye ne-tin yokuntywila (I-Sn) ifaneleke ngakumbi kwindibano yecala elinye kunye nenkqubo yokuthengisa ngexesha elinye.