With the development of smaller and higher density surface mount packages like Quad Flat No-lead (QFN) and Ball Grid Array (BGA), solder joints¡¦ strength of the electronic components has a greater impact on the reliability of an end product. Also, the decrease in size of consumer products such as cellular phones, PDAs and MP3 players, has increased the frequency of accidental drops resulting in solder joint cracks and eventually malfunction of the products. With legislation put in place by government and industrial bodies, electronics companies are driven to eliminate the uses of lead in their products. It thus leads to the concern of reliability of lead-free solders as interconnects. The present work aims at studying the effects of drop impact on the strength of solder joint of lead free solder (Sn4Ag0.5Cu) and BGA substrate metal finish electrolytic Ni and Au.
In this study, the effects of internal stresses in BGA Ni layer and Pre-treatment Micro-Etching processing on the strength of Sn/Ag/Cu solder joint are investigated. The drop test and peel off test are adopted in testing the strength according to the standard of JEDEC.
The drop test results have shown that the compressive internal stresses in the Ni layer have worse effects on the joint strength than tensile internal stresses can affect. The failure modes are analyzed and can be concluded that all failures occur at the interface of IMC and the surface of Ni layer on BGA substrate.
The drop test results have shown also that the strength of the solder joint with the lower concentration of SPS in pre-treatment micro-etching is stronger and all the failures occur at the interface of IMC and the surface of PCB Cu Pad. Comparing with the effect of internal stress in Ni layer, SPS concentration in pre-treatment micro-etching to affect the solder joint strength is more significant.
| Identifer | oai:union.ndltd.org:NSYSU/oai:NSYSU:etd-0120107-093809 |
| Date | 20 January 2007 |
| Creators | Tseng, Chi-Chao |
| Contributors | Ting-Nung Shiau, Jung-Hung Sun, Chi-Hui Chien |
| Publisher | NSYSU |
| Source Sets | NSYSU Electronic Thesis and Dissertation Archive |
| Language | Cholon |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0120107-093809 |
| Rights | not_available, Copyright information available at source archive |
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