ASSOCIATION CONNECTING ELECTRONICS …

1 IPC-9261 AIn- process dpmo andEstimated yield for PCAsDeveloped by the dpmo and Assemblies, Attributes and VariablesIdentification Task Group (5-22g) of the Assembly and Joining ProcessesCommittee (5-20) of IPCU sers of this publication are encouraged to participate in thedevelopment of future :IPC3000 Lakeside Drive, Suite 309 SBannockburn, Illinois60015-1249 Tel 847 847 :IPC-9261 - March 2002 ASSOCIATION CONNECTINGELECTRONICS INDUSTRIES Table of .. and Definitions .. (Defects per Million Opportunities) .. (Defects per Unit) .. Step estimated yield .. Opportunities (oc).. Defect (dc) .. Opportunity (op) .. Defect (dp) .. Opportunity (ot).. Defect (dt).. Assembly Opportunity (oa).. Assembly Defect (da).. 22 APPLICABLE 23 CALCULATION OF IN- process of In- process Metrics -Assumptions .. Examples .. of Placement dpmo .. of Termination dpmo .. of Component dpmo .

2 Of Assembly dpmo .. 74 estimated 8 Appendix A:Defect 10 FiguresFigure 3-1 process Flow 3 Figure 4-1 estimated yield CalculationConceptual 8 TablesTable 3-1 Bill of 3 Table 3-2 dpmo Calculations for Placement Defect Category .. 4 Table 3-3 dpmo Calculations for Termination Defect Category .. 5 Table 3-4 dpmo Calculations for Component Defect Category .. 6 Table 3-5 dpmo Calculations for Assembly Defect Category .. 7 Table 4-1 estimated yield Example 1 .. 8 Table 4-2 estimated yield Example 2 .. 9 IPC-9261 AOctober 2006ivIn- process dpmo and estimated yield for PCAs1 ScopeThis document defines standard methodolo-gies for calculating defects per million opportunities( dpmo ) metrics related to electronic printed board assem-bly processes. It is intended for use in measuring in-processassembly steps rather than end product determination. Cal-culation of completed item dpmo is addressed in , a guide to defect categorization is providedthat when used with J-STD-001 and IPC-A-610 can serveas a base for summarizing and reporting in- process :This document does not dictate the number ofassemblies or data points needed to calculate dpmo PurposeThe purpose of this document is to defineconsistent methodologies for computation ofin-processDPMO metrics for any defect evaluation stage in theassembly objective anticipates the following conditions indefect reporting and analysis: To facilitate process improvement, defects discovered atany stated inspection or test point should be assigned totheir appropriate process step.

3 All defects shall be reported at the inspection point theyare found, even though one undetected previous defectmay have caused the subsequent defects. Regardless of how these defects are assigned, the defectmust be attributed to either a component, placement, ter-mination or assembly defect. The assumption is that each printed board assembly thatis inspected will be 100% inspected for all defects. The assumption of 100% inspection efficiency is should be exercised when comparing processesusing manual inspection to those using automated visioninspection. When using a sampling inspection plan, the number ofPCAsinspecteddetermines the opportunity count, notthe Terms and dpmo (Defects per Million Opportunities)DPMOis defined as the total number of defects divided by thetotal number of opportunities for a defect multiplied by1,000,000. It is not strictly equivalent to PPM as thedefinition of opportunities has special meaning whenconsidering electronic assembly DPU (Defects per Unit)DPU is defined as theaverage number of defects per process Step estimated YieldThe expected per-centage of assemblies with no defects for a particular pro-cess step or combined process steps, based on historicaldefect Component Opportunities (oc)The term compo-nent is defined as each device or piece of hardware thatmay be assembled onto a printed wire board (PWB).

4 Sol-der, glue dots, and other similar materials are not to beincluded in this dpmo calculation. The PWB is consideredto be one total opportunity count for each component is electronic component with multiple leads still counts asone. Processes, such as conformal coating and cleaningoperations, do not add component opportunity are captured in one assembly opportunity. The fin-ished PCA is not an Component Defect (dc)A component defect isdamage to a component exceeding the limits of the compo-nent specification, or those described in J-STD-001, and/ordamage that results in nonusability of that defects include both visible and nonvisibledefects (physical/electrical).Example:A component couldbe both dimensionally incorrect and have major surfaceflaws, however, this results in a defect count of Placement Opportunity (op)The term placement refers to the proper placement of components based on thebill of materials.

5 The PWB does not have a placementopportunity. The total opportunity count for each placedcomponent is Placement Defect (dp)A placement defect is anycomponent presence and/or positioning error that hasoccurred during an assembly operation that violates thedimensional criteria specified for that component in J-STD-001 or IPC-A-610. Example: Exceeding maximum side ortoe overhang. Even though a component may have morethan one placement defect, any one or combination of mul-tiple placement defects on any single component has amaximum defect count of one for that Termination Opportunity (ot)The term termina-tion is defined as any hole, land or other surface (such ascomponent to component attachment) to which a compo-nent is electrically terminated. It also includes any terminalonto which a wire is electrically 2006 IPC-9261A1