PCBA Quality Process Audit - Reflow oven

1. Work Instructions
1.1Is there a revision controlled Operator Work Instruction which contains set-up information for the specific product being reflowed? (Score 0 if any unsigned/undated handwritten instructions or any handwritten instructions more than 48 hrs old)
1.2Are Work Instructions readily available to the operator and are they followed at Reflow?
1.3Is the conveyor speed set point specified on the Work Instruction and is it the same as that specified in the program?
1.4Are the temperature set points specified on the Work Instruction and are they the same as those specified in the program?
1.5Do Work instructions indicate if pallets or other tooling are required?
1.6When center rail support is required, do Work instructions indicate this requirement and is the location specified?
1.7Is the machine Program Name specified on the Work Instruction or set-up sheets?
2. Machine Capability
2.1Is the Reflow technology in use suitable for the product being built? Must be full forced Convection with sufficient zone count.
2.2Are air flow controllers or a centralized control system used to balance exhaust flow rates for each individual exhaust drop?
2.3Are exhaust flow rate ranges specified and monitored on a regular basis to insure compliance?
2.4Is the machine Program Name revision controlled to show traceability of program changes?
2.5Is the machine Program Name traceable to the PWB and PCBA part number?
2.6Is access to the machine program password protected with restricted access?
2.7Do program changes to critical parameters during machine control remain unsaved unless approved by a technician/engineer?
3. Temperature Profile
3.1Is there available a Temperature Profile for the product currently being built?
3.2Is the Temperature Profile assessable and readily available to operators / technicians as and when required?
3.3Were the Temperature Set Points and Conveyor Speed logged for that Thermal Profile when it was conducted?
3.4Do the Temperature Set Points & Conveyor Speed written on the Thermal Profile correspond to the current Program settings?
3.5Is there available an Engineering based specification to detail the acceptable process window for Temperature Profiles?
3.6Was the Engineering based spec. derived from the Paste & Component manufacturer’s recommendations but controlled to a narrower window?
3.7Does the product Temperature Profile fall within the Engineering based specification for the process window?
3.8Does the product Temperature Profile fall within the Engineering based specification for glass transition temperature requirements?
3.9Can any excursions outside of the process window be justified and supported with hard evidence and logical analysis?
3.10Does the product Temperature Profile meet the reflow requirements for the SMT components according to the component manufactures?
3.11Are the boards used to establish the initial Thermal Profile kept as engineering samples?
3.12Is there evidence that a once off comparison study been conducted for a loaded versus an unloaded oven?
3.13Have at least five thermocouples been used at various points on the board to establish the Thermal Profile? Note*
3.14Is there a documented and systematic approach used to identify the most appropriate locations to attach the thermocouples?
3.15Can it be demonstrated that a BOM review was conducted to verify that the chosen profile is appropriate for all specific component conditions?
3.16Is there evidence that each thermocouple ball was bonded to a board joint using Hi Temp. Solder or Conductive Epoxy?
3.17Is there the capability to detect a temperature zone failure and to trigger an alarm automatically if this occurs?
3.18Has a Calibration Profile been established in order to detect machine long term performance degradation?
3.19Is there a documented frequency for running a Calibration Profile and was it established based upon historical performance data?
3.20Is there evidence to demonstrate that Calibration Profiles are conducted and that records are up-to-date?
3.21Is the practice of comparing the current Calibration Profile to the Standardized Calibration Profile used to identify changes?
3.22Is the current Calibration Overlay/Profile used to determine if a variation in the ovens thermal characteristics has occurred?
3.23Is the current Calibration Overlay/Profile used to determine if a variation in conveyor speed has occurred?
3.24Is there evidence to demonstrate that action was taken when the Calibration Profile was different to the Standard?
3.25Is a standardized tool, like an OvenRider, used with a standardized profile to conduct a Calibration Profile?
4. Manual Inspection (NA allowed, for questions in this section if AOI is deployed)
4.1Are outputted boards at least sample inspected pre reflow for placement, missing components, and solder defects?
4.2Are Workmanship Standards defined for placement and soldering, and are they accessible and used to determine board acceptability?
4.3Are Inspection Templates available and used to identify missing & unpopulated components and component polarity post reflow?
4.4Are Inspection Templates or Visual Aids used to identify ICT not tested components post reflow?
4.5Are Templates readily accessible for verification purposes?
4.6Are Inspection Templates revision controlled and traceable to the current product ECO level?
4.7Is there a point and click software tool post reflow which is linked to CAD or program data to facilitate component identification for rework?
4.8Is there a documented requirement to conduct at least sampling X-ray inspection for BGA devices, and is there evidence that it is practiced?
5. Automatic Inspection (NA allowed, for the cells indicated)
5.1Are AOI/AXI complementary methods, which include solder joint inspection, used for all reflowed parts?
5.2Is the AOI coverage % calculated based on the board OFE for a given side vs the total # of joints/components inspected?
5.3Are the components/joints not covered by AOI documented and known and targeted for visual inspection?
5.4Is there evidence that the AOI coverage is verified periodically by using ICT and manual inspection feedback data?
5.5Can it be demonstrated that the machine calls are reviewed by the operator to determine if real or false?
5.6Can it be demonstrated that the operator been fully trained and certified to interpolate the AOI images presented?
5.7Does the ICT pareto of defects suggest that AOI is being 100% deployed and is being effective?
5.8Can it be demonstrated that AOI detectable ICT failures are feed back to AOI to improve program and operator effectiveness?
5.9Are rejected boards automatically stopped on the line post operator false call validation?
5.10Are changes to AOI coverage made based only on performance feedback?
6. Process Control
6.1Is there evidence that the SPC used to monitor output post reflow, is effective at identifying & correcting process performance issues?
6.2Is the processes DPMO and the products DPU monitored in real time? (‘real-time’=now)
6.3Is OFE data readily available and calculated in accordance to documented procedures?
6.4Is AOI data used to calculate SMT’s DPMO? Score 0 if AOI deployed and not done.
6.5Are ICT debug results used to re-calculate SMT DPMO as a true measure of SMT DPMO?
6.6Is the data collected meaningful and can it be demonstrated that it is used to make process control decisions?