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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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Contents

1. Summary of the Project……………………………………………………….…………..3

2. Particulars of Team…………………………………………………………….………….4

3. Project Write-up………………………………………………………………….………...5

A Introduction ……………………………. ………………………………….………......5

B Project Selection and Definition…………..........………………………….…………8

C Analytical Techniques……………………………………………………….…………9

D Solution ......…………………………..………………………………………………..13

E Results Achieved………………………………………………………………………15

F Standardization………………………………………………………………….……..16

G Expandability……………………………………………………………….................17

H Conclusion………………………………………………………………………...…...17

Powering Our Brighter Future

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Summary of Project

Theme: To Eliminate Used Wire Cutting Process at Wafer Saw.

Problem: Within a year, the wire cutters had 2 fire incidents (near misses) inside the chute.

Causes: Sparks were created inside the machine. Some sparks ignited the dry dust trapped

inside the chute, which caused FIRE.

Solution: ELIMINATION is the most effective way to control the risk. With this in mind, the team

challenged the status quo by taking away the cutting process, and eliminating the

used wire cutter while still continuing with the wafer saw operations.

Abstract: In 2011, under the framework of Systematic Problem Solving (SPS) program

implemented by the company for the continuous improvement of its operations, we

took the opportunity to form an SPS team to undertake this project. By undertaking

this project; our objective is to eliminate the risk of fire and to gain productivity.

Successful implementation of this project can change the way our workers perform

the wafer saw process in a safer and more productive manner, thereby deriving

significant annual cost savings for the company.

Used Wire Cutter machine Fire inside the chute

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Team Particulars

The team was formed in 15 July 2011. We are a cross functional team and the members were

selected based on certain strength which would be critical to the success of our project. The

team was further supported by the process, equipment and production teams which provided

special assistance during the project.

Name Job Title Strength

Christopher Heng Manufacturing Engineer

Motivator and energetic in driving the team

to obtain the goals

Patrick Teo Process Engineer Good in wafer saw process knowledge

Heng Chai Kiong Senior Production Leader

Good in execution and implementation of projects

Manickavel Senior Maintenance Specialist

Support in technical aspect

Kevin Roy Production Leader Good in execution and implementation of projects

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Project Write-up

A) Introduction

1. Company Background

With increasing concerns over climate change, renewable energy sources proved to be a better

long term solution to power the economy and it is our mission at REC to provide it through

Photovoltaic solar. As a leading player in the photovoltaic industry, REC Singapore sought to

produce high-quality solar panels to meet the ever increasing demand for electricity from

renewable energy.

REC Wafer with 4 main process steps as shown below.

Ingot Block Wafer Saw

Wafer Line

REC aims to play a leading role and be a

key contributor in shaping the future of the

solar energy industry. We focus on

achieving operational excellence and

lower production costs to enhance solar

viability. We do this by continuing to

pursue ambitious technology development

programs and cost-reduction initiatives.

REC Singapore is an integrated solar

production facility comprising 3 business

units – Wafer, Cells and Modules. Wafer,

being the first in the value chain, plays a

critical role to ensure high-quality solar

panels through the production of good

quality wafers using multicrystalline

technology.

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1. Ingot – Raw silicon materials are transformed into solidified ingots through

crystallization process

2. Block – An Ingot is cut into blocks and inline quality inspection is performed on the block

3. Wafer saw – Blocks are sawn into thin slices of wafers via multi wire sawing process

4. Wafer line – The end products, which are the silicon wafers, are inspected, sorted &

packed

2. Project Background

Wafer slicing process:

1. Transform blocks into wafers through multi wire sawing machine

2. Multi wire sawing machine.

Our company has many wire sawing machines. The diagrams below show a multi wire

sawing machine and the different parts of the machine.

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Multi wire sawing machine.

3. Steel wire acts as a media to carry silicon carbide which performs the sawing of blocks

into wafer. Before the start of the process, steel wire is being fed onto wire roller guide from

supply spool. During the process, used steel wires are being collected by another spool, known

as return spool. The pair of supply and return spool provides & collects wire respectively for

every run. When the supply wires are depleted, replacement of return & supply spool takes

place.

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4. Return Spool

Empty supply spool is being discarded while Return spool will be recycled to collect used

wire in the next two process run. Return spool is recycled by cutting away used wire wound

around it by means of a Used Wire cutter machine.

B) Project Selection and Definition

1. Project Selection

In the REC’s Health, Safety and Environment (HSE) Policies, REC puts safety first and follows

the strategy that all accidents, injuries and occupational illness are preventable.

Within a year, the wire cutters had 2 fire incidents (near misses) inside the chute. This is due to

the creation of sparks inside the machine. Some sparks ignited the dry dust trapped inside the

chute, which caused FIRE.

Used wire is being cut away by a fiber disc

inside the wire cutter. Heat and sparks

occur inside the chamber. Risk of fire.

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ELIMINATION is the most effective way to control the risk. With this in mind, the team

challenged the status quo by taking away the cutting process, and eliminating the used wire

cutter while still continuing with the wafer saw operations.

Project Title: Eliminate Used Wire Cutting Process at Wafer Saw

C) Analytical Techniques

1 Improvement Idea:

Used wire cutting process can be eliminated if we use the empty supply spool to

collect the used wire instead of the return spool.

Upon collection, we can dispose away the supply spool and used wire together. With

that, the used wire cutting process is eliminated.

2. Project Flow

After forming a SPS team, we use DMAIC for our improvement project.

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3. Target Setting

1. To eliminate the used wire cutting process at wafer saw.

2. To recycle empty supply spool as a replacement for return spool to collect used wire and

subsequently dispose of the supply spool with the used wire.

3. To eliminate Fire Hazard at the Wire Cutters in the plant.

4. SMART Goals:

To achieve the above target by eliminating the used wire cutting process for all wafer saws

machine in REC Wafer by December 2011.

Measurable Targets (Safety & Saving Enhancement)

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5. Activities Schedule

Activities schedule was planned out based on SMART goals in order to manage our

project effectively.

6. Benefit Analysis

Benefits analysis was conducted using 4M and 1E method to identify all potential gains

from this project in order to determine the feasibility of project based on ROI (Return of

investment).

Benefit Analysis Table

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31

1 Plan without pulley

1.1 Testing of 1 run w/o pulley X

1.2 Submit PCRB for change plan approval X

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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Yiel

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re /

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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

recognized as the best project of that year.