Transcript Electro-Chemical Migration Idea Stage

Electro-Chemical Migration
Definition Stage
Project
Wallace Ables - Dell
HDP User Group Member Meeting
Host: Oracle
Santa Clara, CA.
Feb. 26. 2013
Presented by: Keith Howell
© HDP User Group International, Inc.
Problem Statement
• The current industry standard test
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protocols were originally developed to
identify highly ionic contaminant levels
(halides) after a cleaning process.
These test protocols are not completely
effective at identifying ECM and corrosion
exposures from no-clean flux residues.
© HDP User Group International, Inc.
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Background
1. Products assembled with no clean flux systems are
experiencing various forms of corrosion and Electro
Chemical Migration failures. These products and flux
systems have passed the current industry standard
cleanliness and corrosion resistance testing,
demonstrating that these test procedures are not
completely effective.
2. The failure mechanisms occur on products assembled for
all segments of the electronics industry.
3. The current industry standard testing does not take into
consideration various acceleration factors associated
with no clean flux and product design features.
© HDP User Group International, Inc
3
Project Goal
Identify the required enhancements to current
industry specifications, test methods, test boards
and coupon design to increase detection of ECM
and corrosion induced failures when no clean
flux systems are used.
Areas to investigate:
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Cleanliness testing
Corrosion resistance testing
ECM testing
Maximum acceptable residue levels
Influence of PCB manufacturing defects
Influence of PCBA design features
© HDP User Group International, Inc.
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Not in immediate scope
Some closely aligned aspects of this project will
be deferred to a follow-on project, or are already
being investigated by other project teams.
Therefore the following factors will not be in the
scope of this project:
1.
Conformal coating over no-clean fluxes. This may
allow ECM under the conformal coating.
2.
Solder mask test standards for ECM controls.
3.
ImAg creep corrosion (covered by multiple current
projects)
© HDP User Group International, Inc
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Project Objectives
1. Identify modification to current industry standard
specifications and test methods for cleanliness
testing, corrosion resistance testing, and ECM
testing to increase detection of failures when no
clean flux systems are used.
Primary areas of investigation:
a.
b.
c.
d.
e.
Characterize failures escaping current test methods
Test flux residue levels: SMT, Wave Solder, Rework
Test flux application methods: controls, acceptable
application levels, measurement methods and test
methods
Enhance test board and test coupon designs
Identify acceptable flux residue levels by product
class
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© HDP User Group International, Inc.
Project Objectives
2. Identify the influence of PCB manufacturing defects and
design properties on the development of ECM and
corrosion failures.
Primary areas of investigation:
a.
b.
c.
d.
e.
Exposed Cu from solder mask openings (pin holes,
undercut, damage, etc.)
Moisture and chemical absorption properties
Minimum cure level
Voltage bias on a trace
Minimum spacing between positive and negative
features to prevent ECM
© HDP User Group International, Inc.
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Proposed Execution Plan
How the project will answer the Goal and Objectives
Compile list of
current test
methods /
standards / test
vehicles
Compile list of
failure modes from
team members
Correlate
corrosion failures
to gaps in current
test methods
Perform DOE’s.
Collect and
evaluate test data
Develop DOE’s to
validate proposed
changes
Identify
modifications
required to current
test methods
Draft proposed
changes to test
methods /
standards / test
vehicles
Provided
proposed changes
and supporting
data to test
standard owners.
Write final report
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Current Project Activities
• Completed list of current test methods
• Completed identification of failure modes
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observed with no clean residues
Started gathering existing possible Test
Vehicles.
Have met with IPC sub-committees on
Coatings, Cleaning and Testing to discuss
our activity.
Established the basic project plan.
Started to Identify the flux variables to be
used in DOE.
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Industry Standard Test Methods to
consider
Test
Method
Method
Type
#
Method
Focus
Spec.
Owner
Spec Number
Bare
Board
Rev
Date
Title of Spec
1
ECM
Material
IPC
TM650, 2.6.14.1
Sep-00
Electrochemical Migration Resistance Test
2
SIR
Material
IPC
TM650 , 2.6.3.3B
Jun-04
Surface Insulation Resistance, Fluxes
3
SIR
Material
IPC
TM650 , 2.6.3.7
Surface Insulation Resistance,
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Other
Material
IPC
TM650, 2.6.15C
9
CLN
PCA
IPC
TM650,2.3.25C
11
CLN
PCA
IPC
TM650,2.3.38C
12
Other
PCA
IPC
TM650,2.3.39C
Corrosion, Flux
Detection and Measurement of Ionizable Surface
Contaminants by Resistivity of Solvent Extract (ROSE)
Surface Organic Contaminant Detection Test
Surface Organic Contaminant Detection Test (Infrared
Analytical Method)
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ECM
PCA
Bono
16
ECM
Material
HP
EL-EN861-00
Flux Electrochemical Migration Test Method
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19
CLN
CLN
PCA
PCA
IPC
Foresite C3
TM650,2.6.38
Bulk IC
Localized area IC
20
SIR
PCA
Foresite C3
Localized area Y pattern
26
CLN
Material
GR-78-CORE
27
Other
Material
GR-78-CORE
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Other
Other
Material
Material
GR-78-CORE
GR-78-CORE
Silver Chromate Paper IPC-TM 650 2.3.33
Copper Mirror Tests (Modified IPC / Bellcore Method) IPCTM 650 2.3.32
Copper Corrosion Test IPC-TM 650 2.6.15
Copper Corrosion Test JIS Z3197-1999 Test Method 8.4.1
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ECM
Material
GR-78-CORE
13.1.4
Bellcore Electromigration
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32
33
34
CLN
SIR
SIR
ECM
PCA
Material
Material
Material
IPC
IPC
JIS Z3197
JIS Z3197
TM650
IPC -9202
IPC ROSE Test
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No clean flux failure modes
Open
Trace
Corrosion
Failure
Corrosion Mechanism:
A form of crevice or pitting corrosion at the small solder mask opening and the
trace.
Failure mode dependencies:
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Openings or defects in solder mask
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Voltage bias
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Activity level, type, and quantity of flux residue
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Humidity levels
Potential areas to investigate with current test methods:
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Modify test coupon to detect crevice or pitting corrosion failure modes?
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Solder mask openings on test coupon (pitting corrosion)
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Flux trapped under low stand off connections (crevice corrosion)
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Measure flux residue levels (identify threshold of acceptable residual flux contaminants)
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Multiple voltages to traces or nets on the test coupon (identify voltage level sensitivity)
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Multiple humidity levels
© HDP User Group International, Inc.
11
No clean flux failure modes
+ 3V
GND
+ 3V
Surface
Corrosion
Failure
Non soldered OSP
Corrosion Mechanism:
Surface corrosion
Failure mode dependencies:
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Voltage bias
•
Activity level, type, and quantity of flux residue
•
Humidity levels
Potential areas to investigate with current test methods:
•
Measure flux residue levels (identify threshold of acceptable residual flux contaminants)
•
Multiple voltages to traces or nets on the test coupon (identify voltage level sensitivity)
•
Multiple test pad and hole sizes
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Multiple surface finishes
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Multiple humidity levels
© HDP User Group International, Inc.
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No clean flux failure modes
+ 3V
anode
GND
ECM
Corrosion
Failure
Corrosion Mechanism:
Electrochemical Migration – metal dendrite growth
Failure mode dependencies:
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Openings or defects in solder mask (exposed anode / + voltage)
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Voltage bias
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Activity level and quantity of flux residue
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Humidity levels
Potential areas to investigate with current test methods:
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Modify test coupon to provide exposed anode adjacent to ground features (already exists?)
•
Measure flux residue levels (identify threshold of acceptable residual flux contaminants)
•
Multiple voltages to traces or nets on the test coupon (identify voltage level sensitivity)
© HDP User Group International, Inc.
13
Proposed Execution Plan
1. Complete
list of current test methods/standards/test vehicle.
Complete
2. Compile list of failure modes from team members.
Complete
3. Correlate corrosion failures to gaps in current test methods.
4. Identify modifications required to current test methods.
5. Develop DOE’s to validate proposed changes.
6. Perform DOE’s, collect and evaluate data.
7. Draft proposed changes to test methods/standards/test vehicle.
8. Provide proposed changes and support data to test standards owner.
9. Write final report
Complete
In-Process
Not started
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Team Members –To Date
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Agilent
Alcatel-Lucent
Arlon
ASE
Celestica
Ciena
Cisco
Cobar
Dell
Emerson
Ericsson
Flextronics
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Fujitsu
H3C
Huawei
IBM
Intel
Isola
IST Group
Kyzen
Medtronic
Nihon-Superior
Oracle
Panasonic
© HDP User Group International, Inc.
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Phillips
Plexus
Rockwell
Suntak
Shengyi
TTM Tech
Ventec
Zestron
ZTE
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