Pb-FREE ALLOY ALTERNATIVES: RELIABILITY INVESTIGATIONAuthors: H.-J. Albrecht, P. Frühauf, and K. Wilke
Company: Siemens AG
Date Published: 10/4/2009 Conference: SMTA International
Assembly and reliability data of high Ag content alloys and low Ag content alloys will be presented and discussed in relation to the acceptance criteria for different applica-tions. The acceptability of any alloy may vary from prod-ucts and is dependent on the basic alloy data especially the long time behavior under test and / or field conditions. The influence of the assembly parameter will be discussed after visual inspection, X-ray and microsectioning at the initial state.
The test conditions used in the test procedure were tem-perature cycling with different parameters in terms of deltaT and hold and ramping times: 0/+80°C -20°C/+90°C (30'/10"/30'), -40°C/+125°C (30'/10"/30'), -40°C/+150°C (30'/10"/30'), 0°C/+80°C (30'/10"/30'),-40°C/+125°C (20´/10´´/15´/10´´), -40°C/+125°C (10'/20'/10'/20') , -40°C/+150°C (10'/20'/10'/20'), field simulation 0°C/+80°C (0'/60'/0'/360‘). Data are available for more than 2000 cycles.
A ranking list for reliable alloys will be presented for critical discussion and further requirements. Fatigue prop-erties analyzed were shear and pull data, recrystallization, crack initiation and growth, electrical continuity. Based on the fatigue behavior the damage mechanism for differ-ent solders was analyzed and compared to characterize the possibility of the definition of the acceleration factor between alloys and / or TCT conditions. Acceptance crite-ria for lead-free solders will be discussed in relation to the modification of alloys and test conditions. A critical re-view is formulated for possibilities to transform test to field conditions and further demands to generate lifetime results.
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