ISSN:
1662-9752
Quelle:
Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
Thema:
Maschinenbau
Notizen:
The reliability of QFP (Quad flat package) solder joint using Sn-8Zn-3Bi solder pasteunder the thermal shock test was investigated. Considering the environmental restriction such asROHS, the QFP Cu LF (Lead-frame) was coated with lead-free materials (Sn, Sn-3Bi). To analyzethe reliability under thermal shock treatment, the samples were placed in the thermal shock chamber(248K/423K, Dwell time: 30min). During the thermal shock test, the solder joint cross-sectionswere observed every 500 cycles. No crack initiation and propagation was observed through all typeof plated Cu LF. The measured pull strength slightly decreased, as the number of cycles increased.After 1000 cycles, the pull strength of Sn and SnBi plated Cu LF reduced by 30% and 20%,respectively, compared with that of initial condition. Observing the fracture surface morphology byFE-SEM, the fracture mode changed and the IMC fractured area on the both fracture surface wasincreased. The IMC was identified as γ-Cu5Zn8 by chemical composition analysis using EDS. Thereduced pull strength was affected by IMC fracture and fracture mode change. However, the pullstrength does not decrease steeply but gradually. Consequently, the Sn-8Zn-3Bi solder joint showsthe reliable solder joint strength, fracture mechanism, and compatibility with lead-free plated Cu LFduring the thermal shock temperature of 248K to 423K
Materialart:
Digitale Medien
URL:
http://www.tib-hannover.de/fulltexts/2011/0528/02/18/transtech_doi~10.4028%252Fwww.scientific.net%252FMSF.580-582.247.pdf
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