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Title: Failure modes & effects analysis (FMEA) of flip chip devices attached to printed wiring boards (PWB)
Author: Kennedy, M
Abstract: Assembly techniques using flip chip devices on PWB and ceramic have been available for several years. When Medtronic Micro-Rel decided to introduce this technology or change some of the design, component, or process parameters, Failure Modes and Effects Analysis (FMEA) proved to be a useful tool to identify any potential design and process related failure modes. Additional purposes of an FMEA are: to determine the effects of the failure modes. to determine the root cause of the failure modes. to prioritize actions by using a ranking system for the failure mode effects in terms of probability of occurrence of the failure mode, severity of the effect of the failure mode, and probability of detection of the failure mode through manufacturing. to identify, implement, and document corrective actions to address failure modes with rankings that are considered unacceptable. Although an FMEA may seem extremely time consuming or overwhelming the purpose of this paper is to address this large chore by dividing the process into smaller pieces for manageability. Additionally, this report will address a preliminary FMEA performed early in the evaluation stage of flip chip devices on PWB. Many of the initial inputs were based on available literature and findings from other companies. Many of the evaluations and designed experiments (DOE) performed were driven by the initial FMEA rankings. During the development 'stage, six DOEs were recorded and performed addressing various issues related to flip chip attachment. Areas reviewed included solder screening, reflow profiles of the flip chip dice, and underfill dispense parameters. The outputs from these DOEs allowed the engineers to perform less experiments and to get more from their evaluations. (Confirmation builds were used once all of the parameters were established.) Although many of the concerns found in literature searches were applicable, some items (such as underfill voiding) were found not to be as crucial a concern in this particular design. The FMEA was then reevaluated after all evaluations and qualification builds were performed. These findings were used to drive design rules and process parameters.
Source: TWENTY THIRD IEEE/CPMT INTERNATIONAL ELECTRONICS MANUFACTURING TECHNOLOGY SYMPOSIUM
Publication Year: 1998
Volume:
Issue nr:
Pages: 232 - 239
Science Code: Engineering, Manufacturing; Engineering, Electrical & Electronic
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