IE 545, Human Factors Engineering Failure Modes and Effects Analysis

2 Example for FMEA: Pre-Reflow Inspection Station (PRIS)

3 Overall SMT Process Solder dispense Pick & place

4 A Typical PCB

5 bView Display

IE Inspection Process ● Prepare and review documents ● Program reflow oven ● Inspect board – Check board match – Check component placement – Check component population – Check component rotation/direction ● Insert manual components

7 PRIS Process/Task Hierarchy (also called Hierarchical Task Analysis, HTA) A0: Assemble Electronics Components A1: Set Up Oven & Dispenser (Initial) A2: Program & Set Up SMT A3: Dispense Solder On Board A4: Place Component A5: Perform Pre-Reflow Inspection & Place Manual Components A51: Prepare & Review Documents A52: Program Reflow Oven A53: Inspect Board A531: Compare Board Match A5311: Study iView Diagram A5312: Study Individual Component / Group A532: Check Components (Loose, Misaligned, Skewed) A5321: Study iView for Check Components A5322: Assess Individual Component / Group (for Check Components) A5323: Adjust Parts (When needed) A533: Check Component Population (1st Board Only) A5331: Study iView Component Population A5332: Assess PCB Population A534: Check Component Orientation/Direction (1st Board Only) A5341: Study iView and OPIE A5342: Visually Assess Placement of the Component A54: Install Manual Components A6: Reflow

8 PRIS Process Hierarchy in HMSEM Workbook

9 Failure Modes and Effects Analysis (FMEA) ● Purpose – Systematically, prospectively, identify ways in which a process (system) can fail: Failure Modes. – Identify factors potentially contributing to failures. – Estimate risk of failure – Identify countermeasures – Develop requirements ● Method (using HMSEM workbook) – Select task on which to perform FMEA (IDEF0 modeling or HTA should have been completed on it) – Copy/Type process hierarchy into [Process Hierarchy] worksheet. – Perform FMEA in [FMEA worksheet]

10 PRIS FMEA in HMSEM Workbook

11 FMEA Fields ● A# – A-number from IDEF0 nodelist/process hierachy ● Activity / Process / Function – Name (auto look-up) ● Contributing Factors – Circumstances, conditions, events, factors,... anything that might make a failure mode more likely. ● Potential Failure Mode – A way in which the process/system can fail. ● Potential Effects of Failure Mode – Consequences of the failure. ● Severity – Numeric rating of the estimated severity of consequences, of the failure, e.g., 1. negligible 2. minor 3. moderate 4. major 5. catastrophic

12 FMEA Fields (2) ● Probability – Numeric rating of the estimated probability that the failure will occur, e.g., 1. Remote 2. Unlikely 3. Occasional 4. Common 5. Frequent

13 FMEA Fields (3) ● Nondetectability – Numeric rating of the difficulty of detecting the failure in time to prevent or mitigate its consequences, e.g., 1.Should the failure occur, there is a virtual certainty that the existing controls will detect it. 2.Very high 3.Should the failure occur there is a high probability that the existing controls will detect it. 4.Moderately high 5.Existing controls have difficulty detecting the failure 6.Low 7.Controls are weak. Detection could depend on a lucky catch. 8.Remote 9.Very remote 10.No controls for this failure mode exist ● RPN: Risk Priority Number – RPN = Probability x Severity x Nondetectability

14 FMEA Fields (4) ● Potential Remediations – Design strategies that could reduce the likelihood of the failure mode. ● Design Requirements – Abbreviated requirements statements for remediations. – Requirement numbers ([Requirements] worksheet).