Interfacialreactionsandeleciromigrationinlead-freesoiderjoints with copper and au-nisurfacefinished coppersubsiratfs
Loading...
Date
2009-11
Authors
Ngoc Binh, Duong
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
Properties of lead free solder alloys (Sn-9Zn, Sn-8Zn-3Bi and Sn-3Ag-
0.5Cu) on Au-Ni surface finished copper and copper substrates were investigated.
Results obtained showed good wetting of all three solder alloys on Au-Ni surface
finished substrate at appropriate temperatures. Contact angle measurement and
wetting force results reaffirmed that good wetting of solder alloys on substrate was
achieved. Microstructural analysis of the interface between solder alloys and Au-Ni
surface finished copper substrate revealed that the Au layer on the substrate had
dissolved completely into solder alloys after 20 seconds. A layer of Au-Zn
intermetallic compound (IMC) was formed at the solder substrate interface, i.e.
Au5Zn3 in Sn-9Zn and AuZn3 in Sn-8Zn-3Bi. With Sn-3Ag-0.5Cu, AuS114 IMCs were
found distributed in the solder alloy and a layer of (Ni,Cu)6Sns IMC was formed at the
solder-substrate interface. Electromigration has thickened the IMC layer at the
interface of solder joint, which is Cu5Zn8 IMC in Sn-9Zn and Sn-8Zn-3Bi joints
whilst it is CU6Sn5 in the Sn-3Ag-0.5Cu joint. The thickening process occured at
different rates, faster IMC thickening was observed on the anode of a specimen than
on the cathode. Also, the Cu5Zn8 layer which is formed in the Sn-9Zn and Sn-8Zn-3Bi
solder joints were found to grow faster than the CU6Sn5 layer in the Sn-3Ag-0.5Cu
joint. Electric current was found to have an effect on the growth of CU6Sn5 in Sn-3Ag-
0.5Cu, with elongated Cu6Sn5 phase being formed along with the current direction.
Description
Keywords
Deleciromigrationinlead-freesoiderjoints , Au-nisurfacefinished coppersubsiratfs