DocumentCode :
894456
Title :
Reliability of Pb-free preplated leadframe under atmosphere and accelerated aging test
Author :
Park, Jongwoo ; Kim, Young-Hee ; Wang, Seung-Woog ; Lee, Seung-Woo ; Jeon, Hyungoo
Author_Institution :
SYSTEM Large Scale Integration Div., Samsung Electron., Gyeonggi-Do, South Korea
Volume :
6
Issue :
1
fYear :
2006
fDate :
3/1/2006 12:00:00 AM
Firstpage :
33
Lastpage :
41
Abstract :
Atmospheric corrosion of Pb-free preplated leadframe (PPF) finish, which causes unacceptable appearance due to discoloration, has been meticulously investigated. The discoloration appears particularly on the shoulder, tip, and sidewall of the leadframe, where bare Cu is directly exposed to the given environments. Such Cu exposure is attributed to the forming and trimming process of the PPF. It is found that the geometrical feature of the ragged shear edge on the sidewall of the PPF is dependent on the condition of a cutting tool. There is a porous Ni layer on the Cu substrate. It is also found that the tarnish products consist of cuprous oxide (Cu2O) and cuprous sulfide (Cu2S). The depth profile reveals a thick Cu oxidation layer over cuprous sulfide, which implies that the integrity of a dual inline package assembled with the PPF is susceptible when exposed to a relatively higher humidity and sulfur-involved environments. To reproduce the atmospheric corrosion, a variety of laboratory aging tests that include the mixed flowing gas (MFG) test was used. Except the MFG test, the laboratory corrosion that yields Cu oxidation only is not identical to the atmospheric corrosion. As results, electronic devices assembled with the PPF must be sealed into a moisture-barrier bag to extend the shelf life during storage, if particularly they are exposed to relatively harsh circumstances, higher humidity in H2S atmosphere.
Keywords :
copper compounds; corrosion; electronics packaging; finishing; life testing; reliability; Cu2O; Cu2S; accelerated aging test; atmospheric corrosion; copper substrate; cupric oxide; cuprous oxide; cuprous sulfide; discoloration; dual inline package; forming process; laboratory aging tests; lead frame reliability; mixed flowing gas test; moisture-barrier bag; porous layer; preplated lead frame; tarnish products; trimming process; Accelerated aging; Assembly; Atmosphere; Corrosion; Cutting tools; Humidity; Laboratories; Lead; Oxidation; Testing; Accelerated aging test; Pb-free preplated leadframe (PPF); corrosion; cupric oxide; cuprous oxide; cuprous sulfide; mixed flow gas test; reliability; tarnish product;
fLanguage :
English
Journal_Title :
Device and Materials Reliability, IEEE Transactions on
Publisher :
ieee
ISSN :
1530-4388
Type :
jour
DOI :
10.1109/TDMR.2006.870341
Filename :
1618652
Link To Document :
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