Page 1 Facilitator: Jen Tan Leader : Christopher Heng Members : Patrick Teo, Heng Chai Kiong Manickavel, Kevin Roy Department: REC Wafer Team Name: Wafer SAW Formation: 15 July 2011 Workplace Safety & Health Innovation Award 2013 Project Title: Eliminate Used Wire Cutting Process at Wafer Saw
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Eliminating Used Wire Cutting Process at Wafer Saw
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Page 1
Facilitator: Jen Tan Leader : Christopher Heng Members : Patrick Teo, Heng Chai Kiong Manickavel, Kevin Roy
Department: REC Wafer Team Name: Wafer SAW Formation: 15 July 2011
Workplace Safety & Health Innovation Award
2013
Project Title: Eliminate Used Wire Cutting Process at Wafer
Saw
Page 2
Contents
1. Summary of the Project……………………………………………………….…………..3
2. Particulars of Team…………………………………………………………….………….4
1.3 Test DG0 1 saw for 1 week(saw F105) X X X X X X X X
1.4 Generate DG1 report for PCRB review X X X X X X
1.5 Review result of DG0 and issue encounter X
2
Test DG1 (Bekaert spool) on 5 saw for 2
week(saw F1#08 to F1#12) D X X X X X X X X X X X
2.1 Generate DG1 report for PCRB review X X
2.2 Review result of DG1 and issue encounter X
2.3
Test DG2 on 50% Bekaert wire saw for volume for
1 month in F2 factory X X X X X X X X X X X X X X X X X X
3
Test DG0 1 saw for 1 week(saw F105)Hyosung
spool X X X X X X
3.1 Generate DG1 report for Team review X X
3.2
Review result of DG1 and issue encounter by
Team X
3.3
Test DG2 on 5 saw Hyosung wire saw for volume
for 1 month in F1 factory X X X X X X X X X X X X X X X X X X X X X X X
4 Test DG0 1 saw for 1 week(saw F105)JFS D D D D D D
4.1
Test DG2 on 5 JFS wire saw for volume for 1
month in F1 factory D D D D D X X X X X X X X X
5 Generate DG2 report for PCRB review
5.1 Review result of DG2 and issue encounter
6 Preparation of shot lock bolt for 1st 32 saw X X X X
6.1 Preparation of shot lock bolt for next 32 saw X X X X X X
6.2 Preparation of WI for new change
6.3 Preparation of ER report, ECN and CCB approval
7 Full Implementation in WST 1&2
Project Schedule September October
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7. Potential Benefit Gain
Possible benefits identified from the above Benefit Analysis diagram were consolidated.
The team reviewed and decided to proceed to evaluate the technicality of project
implementation.
Benefits Table
8. Project Evaluation (Constraints)
Spool Elongation
Different wire spool supplier, different design
• There may be deviation on the spool structure among different spool suppliers.
• Tests need to be conducted on different types of spool to evaluate the feasibility of the
replacement.
Concerns:
Compared with the conventional used wire return spool, the used supply spool drum is made of different materials. It is expected to have a higher elongation rate, which may cause difficulties in its removal from the machine once the expansion is greater than control specification. There may be a RISK of Deformation and injury to operators.
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D) Solution.
1. Feasibility test on spool expansion.
The Decision Gate (DG) 0 is to test the feasibility of the project and to understand the
success rate.
• Spool was set with the wire with tension being optimized.
• First run was carried out with the used wire wound round half of the spool. The spool
expanded a little.
• Continued with 2nd run to complete the wire take up without any interruption. The spool
expanded with no risk.
• No difficulties were encountered in the removal of the spool even with the
expansion.
2. Solution Implementation and Test Results
The DG1 test is a 10 saw run test per spool type. This is to understand the influence in
yield performance during the test and make changes when necessary.
Below is the test result for DG1.The result shows not negative impact to yield.
3. Test on different suppliers
The DG2 test is a half factory volume test for 1 to 2 weeks. This test is to monitor the
stability of change that will not impact the yield loss before large volume test is carried
out.
The table below shows the result of 3 different spool suppliers. The yield was better than
the standard run.
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A Supplier Spool Test Results
B Supplier Spool Test Results
C Supplier Spool Test Results
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5. Final Project Implementation
After all the above tests were done to confirm that there was no impact to safety and
production process quality, we made changes by substituting the Return Spool with
Empty Supply Spool.
By doing so, we do not need to recycle the Return Spool. Therefore we can
Eliminate the used wire cutting process.
E) Results Achieved
1. Safety Enhancement: After implementing the project, fire occurrence at wire cutter
was reduced to zero. All cutter machines were no longer in use.
2. Cycle time reduction: After implementing the project, the change over time for
spool was shortened by 15 minutes.
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3. Cost Saving: After implementing the project, we achieved a cost saving of more
than one million dollars per year.
F) Standardization
1. Sustainability
To ensure sustainability, yield performance of ‘A’ wafer (best grade wafer) was
monitored closely after implementation of project. Results showed that ‘A’ wafer yield
remained stable in Factory WST1 where the project was piloted.
Upon gain verification by Finance and project results review and approval by line
manager, the project is confirmed to be implemented across the whole production.
2. Documentation
The following documents were updated accordingly:
Documents to Review & Update Responsible Status
1. Operations SOP/WI
Christopher Heng, Heng CK Completed
2. Maintenance SOP/WI
Manickavel, Patrick Teo Completed, no change required
3. Drawings
Patrick Teo Completed
4. Maintenance List/Plan
Patrick Teo, Hisham Completed
5. ICCM Library
Patrick Teo Completed
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0.0
0.5
1.0
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Wk 44 Wk 45 Wk 46 Wk 47 Wk 48 Wk 49 Wk 50 Wk 51
Yiel
d/ %
Failu
re /
%
Date
WST1Yyield Performance
Saw mark TTV LATF A-wafer Singulated
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Operation WI Updated and Maintenance List/Plan Updated
Training was conducted to the relevant personnel (Production, Engineering) on the new
process of recycling supply spool to replace the return spool to collect used wire.
Competency matrixes of trained employees were updated accordingly.
Competency Matrix Updated
G) Expandability
Relevant personnel of our affiliated company who had the same wafer saw process
methods came to Singapore to learn from us. They implemented the same procedure at
their plants.
H) Conclusion
In the subject of risk control, “elimination” is the highest challenge the company has
ever implemented. This project started from an idea, and success was made possible by
passion, determination and patience. We took 6 months to finish the project, which was