unlocking the mystery of circuit board failures a case study presented by: alaa arif edtc 560...
TRANSCRIPT
Unlocking the Mystery of Circuit Board Failures A Case StudyPresented By:
Alaa Arif
EDTC 560
January 15, 2007
Terms & Definitions
Board: Printed Circuit Board (PCB).
ESD: Electro-Static Discharge.
It is the release of a build up of charge, similar to the
shock some people experience when touching a metal
surface or another person.
Terms & Definitions
FPY: First Pass Yield.
The percentage of boards that pass the test during the
first trial.
NDF: No Defect Found failure.
Failure without any apparent cause.
Problem Statement
Boards Failures:
For the first time in the company’s history, a
newly released product failed to reach FPY goals.
Quantity of boards failures exceeded all
expectations.
Analysis
Analysis revealed that 2 types of failures
are mainly responsible for the low FPY:
0
5
10
15
20
25
30
35
40
August, 06 October, 06 November, 06
ESDNDF
ESD Failures
NDF Failures
Analysis - ESD
ESD Failures:Caused by unsafe
ESD practices.
ESD could
damage sensitive
components on
the PCB.
Increased over the
first 3 months.
0
5
10
15
20
25
30
35
40
August, 06 October, 06 November, 06
ESDNDFVF
Analysis - ESD
ESD Failures:Caused by unsafe
ESD practices.
ESD could
damage sensitive
components on
the PCB.
Increased over the
first 3 months.
0
5
10
15
20
25
30
35
40
August, 06 October, 06 November, 06
ESDNDFVF
Analysis - ESD
ESD Failures:Caused by unsafe
ESD practices.
ESD could
damage sensitive
components on
the PCB.
Increased over the
first 3 months.
0
5
10
15
20
25
30
35
40
August, 06 October, 06 November, 06
ESDNDFVF
Analysis - NDF NDF Failures:
Caused by
operator
error.
Malfunction
of test
equipment.
Decreased
over the first
3 months.
0
5
10
15
20
25
30
35
40
August, 06 October, 06 November, 06
ESDNDFVF
Analysis - NDF NDF Failures:
Caused by
operator
error.
Malfunction
of test
equipment.
Decreased
over the first
3 months.
0
5
10
15
20
25
30
35
40
August, 06 October, 06 November, 06
ESDNDFVF
Analysis - NDF NDF Failures:
Caused by
operator
error.
Malfunction
of test
equipment.
Decreased
over the first
3 months.
0
5
10
15
20
25
30
35
40
August, 06 October, 06 November, 06
ESDNDFVF
Solution - ESD
Addressing ESD Failures at each level:
Work station.
Operators.
Solution - ESD
Work Station:
Properly ground the
work station.
Coat floor with
ESD-safe material.
Cover workbench
with ESD-safe mat.
Solution - ESD
Operator:
Wears ESD-safe
smock.
Uses ESD-safe wrist
strap.
Cover shoes with
ESD-safe heel straps.
Solution - NDF
Addressing NDF at each level:
Test Equipment.
Operator.
Procedures.
Solution - NDF
Test Equipment:
Train maintenance
technicians.
Increase frequency of
preventive
maintenance.
Provide ample quantity
of spare parts.
Solution - NDF
Operator:
Share with operators the test
results.
Explain the consequences of the
excessive amount of boards
failures.
Train and re-train operators.
0
5
10
15
20
25
30
35
40
August, 06 October, 06 November, 06
ESDNDFVF
Solution - NDF
Procedures:
Document test procedure.
Add illustrations to test procedures.
Make test documents easily accessible.
Results
December test data showed improvement:
0
5
10
15
20
25
30
35
40
Aug. 06 Oct. 06 Nov. 06 Dec. 06
ESDNDF
Trend line
End of the Presentation!