1. The PBGA ndi anasonkhana mumakina a SMT, ndi ndondomeko dehumidification si ikuchitika pamaso kuwotcherera, chifukwa mu kuwonongeka kwa PBGA pa kuwotcherera.
Ma mafomu opangira ma SMD: ma CD osalowa mpweya, kuphatikiza ma pulasitiki okulunga mphika ndi utomoni wa epoxy, ma toni a silikoni (owonetsedwa ndi mpweya wozungulira, zinthu zopumira za polima).Maphukusi onse apulasitiki amatenga chinyezi ndipo samasindikizidwa kwathunthu.
Pamene MSD ikakhala pamalo okwerareflow uvunikutentha chilengedwe, chifukwa kulowerera kwa mkati MSD chinyezi kuti asamasanduke nthunzi kutulutsa kuthamanga kokwanira, kupanga ma CD bokosi pulasitiki kuchokera chip kapena pini pa wosanjikiza ndi kuchititsa kulumikiza tchipisi kuwonongeka ndi mkati mng'alu, zikavuta kwambiri, mng'alu umafikira pamwamba MSD. , ngakhale kuyambitsa kuphulika kwa MSD ndi kuphulika, komwe kumadziwika kuti "popcorn" phenomenon.
Pambuyo pa kukhudzana ndi mpweya kwa nthawi yaitali, chinyezi mu mlengalenga zimafalikira mu permeable chigawo ma CD zinthu.
Kumayambiriro kwa reflow soldering, kutentha kukakhala kopitilira 100 ℃, chinyezi chapamwamba cha zigawozo chimawonjezeka pang'onopang'ono, ndipo madzi amasonkhanitsidwa pang'onopang'ono kupita kumalo omangira.
Panthawi yowotcherera pamwamba, SMD imawululidwa ndi kutentha kopitilira 200 ℃.Panthawi yotentha kwambiri, kuphatikizika kwa zinthu monga kuwonjezereka kwa chinyezi m'zigawo, kusagwirizana kwazinthu, ndi kuwonongeka kwa mawonekedwe azinthu kungayambitse kusweka kwa mapaketi kapena delamination pamakina ofunikira amkati.
2. Pamene kuwotcherera kutsogolera-free zigawo zikuluzikulu monga PBGA, chodabwitsa cha MSD "popcorn" kupanga adzakhala pafupipafupi ndi kwambiri chifukwa cha kuwonjezeka kuwotcherera kutentha, ndipo ngakhale kutsogolera kupanga sangakhale yachibadwa.
Nthawi yotumiza: Aug-12-2021