Abstract
The influence of thermal aging on joint strength and fracture surface of PbSn and AuSn solders in laser module packages has been studied experimentally and numerically. Al2O3-Solder-Substrate assembled samples were aged at 150oC for one, four, nine, sixteen, twenty-five, thirty-six, and forty-nine days. It was found that the joint strength decreased as the aging time increased. This joint strength decrease is due to the increase of void and crack formations in solder joints. There is a correlation between the intermetallic compound (IMC) growth and the joint strength for PbSn and AuSn solders under aging test. The fracture surface of PbSn specimen is gradually changed from the ductile dominated morphology of as-soldered status to the brittle dominated morphology. The section view indicates Kirkendall voids appeared around the interface of bulk solder and IMC layers after 49 days of aging. However, AuSn specimen still shows a ductile dominated morphology and no Kirkendall voids observed even after 49 days of aging. Through 49 days of aging, the shear force drops of 2£gm Au-coated PbSn and AuSn specimens are 9.48kg and 7.65kg, respectively; the shear force drops of 10£gm Au-coated PbSn and AuSn specimens are 9.42kg and 5.88kg,respectively. A finite-element method (FEM) analysis was performed on the calculation of joint strength variation of PbSn and AuSn solders in thermal aging tests. Simulation results were in good agreement with the experimental measurements that the solder joint strength decreased as the aging time increased.
Another study is based on the well-known result of thermal induced fiber alignment shifts of fiber-solder-ferrule (FSF) joints in laser diode package. It indicates fiber alignment shift under temperature cycling tests can be reduced significantly if the fiber can be located closer to the center of the ferrule. An approach to make an FSF with the minimum eccentric offset is studied, an in-house design machine set is used for this purpose, which includes a hot plate, a fiber fix stage, an image capture camera, and a PC with offset analysis program. A preliminary target is set to achieve a maximum 20£gm offset FSF. It was believed that a less than 0.5£gm fiber shift could be measured after 500 temperature cycles. After the practical experiment trial, FSF with around 10 and 12£gm offset is available. However, the continuous improvement is necessary for process stability.
| Identifer | oai:union.ndltd.org:NSYSU/oai:NSYSU:etd-0620102-194049 |
| Date | 20 June 2002 |
| Creators | Chang, Chia-Ming |
| Contributors | Way-Seen Wang, Maw-Tyan Sheen, Jao-Hwa Kuang, Wood Hi Cheng, Ci-Ling Pan |
| 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-0620102-194049 |
| Rights | not_available, Copyright information available at source archive |
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