<p>This research was conducted to develop and qualify a vacuum GaAs semiconductor monolithic microwave integrated circuit die attach process. Research was done to understand the causes and effects of voiding levels on device performance and reliability. Simultaneous investigation was done to qualify vacuum-attach as a successful methodology by which minimal voiding levels were achieved.
After an initial vacuum-attach trial was completed to verify the methodology, internal accept/reject criteria were developed to qualify die attach interfaces. A dual phase attachment methodology was created to minimize tolerance stacking resulting in more consistent component placement. MATLAB image processing code was developed to quantify the voiding levels against the accept/reject criteria. Statistical methodologies were employed to troubleshoot root causes for special cause variation of initial attachment failures. A design of experiment was conducted testing three factors each at two levels (process gas [Gas A, Gas B], leaking chamber [yes, no], and carrier supplier [Supplier A, Supplier B]). The DOE identified process gas and its interaction with the carrier supplier to be significant. Further investigation of the carriers identified plating contamination, resulting in the process gas the primary factor of interest. A secondary experiment focusing on process gas identified no statistical difference between Gas A? and Gas B (Gas A? indicating a high purity form of Gas A). With this information, Gas A? was selected as the process gas. A total of 56 attachment interfaces were then produced yielding 0.7485% voiding, on average, following a Weibull distribution (?= 1.04171, ? = 0.75967) with zero rejections. The process?s consistency of minimal voiding levels were deemed a success and the process was released to production.
|05 January 2017
|Blanden, Zachary F.
|State University of New York at Binghamton
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