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8D Report Case Study
This 8D report summarizes an issue where a die was bonded incorrectly inside a package. The root cause was determined to be the tight tolerance between the die size and leadframe pad size, which could cause misalignment during bonding. Corrective actions included retraining operators, using a bonder with higher accuracy, and requesting a new leadframe design with larger pads to eliminate the issue. The team's work in containing the problem, analyzing the root cause, and implementing preventative solutions was commended.
8D Report Case Study
- 1. 8D Report CaseStudy Presenter Name: Atul Rastogi Date: 3rd October, 2012
- 2. Agenda / Contents TeamIdentification Problem Description Containment Root Cause Corrective Actions and Verification Prevent Reoccurrence Summary (Congratulate the Team) Questions
- 3. • Customer SalesRep logged in issue in the Excel tracking sheet and notified me of the issue • Determined assembly/test location of the unit in question and issued transmittal to the customer to ship the units to the responsible facility • Communicated and discussed issue with appropriate QRA team, specifically the team lead, in China Returned Unit Team Identification
- 4. • Identified theproblem with the returned unit • ATE testing revealed a short • X-ray revealed that the die inside the package was not in the correct position • Deprocessing of the returned unit verified that the die inside was bonded incorrectly Decap of Returned Unit X-ray of Returned Unit Problem Description
- 5. • Identified affectedlot from product marking and shipping records • Requested material from affected lot to be put on hold at the customer location and in-house inventories • Asked customer to return all unused material for disposition • Issued 3D Report (preliminary version of the 8D Report) Containment
- 6. 5Y Analysis Root Cause5Y Analysis
- 7. • Expanded 5Yanalysis to dig deeper into the issue Ishikawa Fishbone Diagram Root Cause – Ishikawa Fishbone Diagram
- 8. • Man • Suboptimalalignment of first die bond was not detected during self- inspection • Subsequent die bonds are based on the first die bond • Material • Compared die size with leadframe pad size and discovered tolerance could be tight for the bonders • Machine • Reviewed bonder accuracy specs • TOSOK – ±75µm • STC400 – ±50µm • Reviewed calibration records • Verified bonder accuracy was with spec limits using 300 samples • V/M inspection could not differentiate between die edge pad edge • Process • Production test duration was very short • Extended stress could cause die to expand due to thermal expansion Decap of Returned Unit Root Cause Analysis
- 9. • Actions taken,verified, and documented immediately after root cause analysis • Man • Operators were notified of the issue and were re-trained to take time to verify self-inspection • Remarks were added to the bonding diagram highlighting the tight tolerance • Shift supervisor verified that the preceding actions were implemented and documented • Machine • Bonder STC500 with an accuracy of ±35µm is to be used going forward • Remarks were added to the bonding diagram to specifically use the STC500 • Shift supervisor verified that the preceding actions were implemented and documented • Implemented corrective actions on other devices with similar die/leadframe pad size ratios Corrective Actions
- 10. • Material –Requested leadframe change • New pad size is ~2x (978µm vs. 1800µm) • Eliminates die shift due to bonder inaccuracy • All 3 bonders can be used b bonder so capacity is not an issue • Received agreement from SQ manager from customer’s manufacturing site • Process Change Notification was issued and approved Prevent Reoccurrence
- 11. • Verified customerissue • After initial assessment, highlighted and added visibility to the tight die/leadframe pad tolerance • Provided additional training to operators • Reminders were incorporated in the bonding diagrams • Requested change in leadframe increasing the pad size by 2x, virtually eliminating the issue • Closed the issue with the China team and the CSR, thanking them for their support and moved on to the next issue • During this process, the customer was kept abreast of our findings Summary (Congratulate the Team)
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