Solder joints are the most fragile parts in electronic package. The properties of joints made of lead-free material are harder and crisper than those of lead-contained material. They tend to break due to dynamic loading by absorbing the impact energy and result in malfunction. Thus, how to improve the reliability of contact joints made of lead-free material in dynamic loading has become an important topic for research.
This work is based on JEDEC Standard JESD22 - B111 ¡§Board Level Drop Test Method of Components for Handheld Electronic Products,¡¨ and JESD22 ¡V B110 ¡§Subassembly Mechanical Shock¡¨. The setup of drop test apparatuses was used to conduct dropping tests with the impact of acceleration 1500 G, in order to acquire the reliability of SnAgCu, SnCu, and SnAg alloy, which would be compared with 63Sn37Pb. The specimens would be red-dyed for an analysis under SEM to examine the distribution of the breakage.
The results were analyzed by Weibull distribution to predict Mean Time to Failure (MTTF), it is revealed that MTTF of solder joints made of Sn0.7Cu, Sn2.6Ag0.5Cu, and Sn3.0Ag0.5Cu (MTTF=355.32, 295.82, 289.54 cycles respectively) are longer than that made of 63Sn37Pb (MTTF=152.52 cycles). Notably, MTTF of alloy Sn0.7Cu is 2.3 times of solder joints of SnPb. Alloy Sn3.0Ag0.5Cu has the shortest MTTF among the three, which is also 1.89 times of alloy SnPb. That is to say, under impact of 1500G, solder joints made of Sn0.7Cu, Sn2.6Ag0.5Cu, and Sn3.0Ag0.5Cu possess greater resistance to shock than alloy 63Sn37Pb, which is in common by used at present.
In addition, the breakage of solder joints mainly generated on Intermetallic Compound (IMC) and around the four corners, distributed from the periphery to the central area. Especially, those on the corners receive greater stresses due to edge effect.
| Identifer | oai:union.ndltd.org:NSYSU/oai:NSYSU:etd-0707105-150303 |
| Date | 07 July 2005 |
| Creators | Chen, Chien-ming |
| Contributors | Ming-hwa R. Jen, Yi-shao Lai, Chi-hui Chien, Chorng-fuh Liu |
| 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-0707105-150303 |
| Rights | unrestricted, Copyright information available at source archive |
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