Electro-Chemical Migration Definition Stage Project Wallace Ables - Dell HDP User Group Member...
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Transcript of Electro-Chemical Migration Definition Stage Project Wallace Ables - Dell HDP User Group Member...
Electro-Chemical Migration
Definition Stage Project Wallace Ables - Dell
HDP User Group Member MeetingHost: Oracle
Santa Clara, CA.
Feb. 26. 2013Presented by: Keith Howell
© HDP User Group International, Inc.
2
Problem Statement
• The current industry standard test 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.
3
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
4
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: 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.
Not in immediate scope
5
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
6
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. Characterize failures escaping current test methodsb. Test flux residue levels: SMT, Wave Solder, Reworkc. Test flux application methods: controls, acceptable
application levels, measurement methods and test methods
d. Enhance test board and test coupon designse. Identify acceptable flux residue levels by product
class
© HDP User Group International, Inc.
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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. Exposed Cu from solder mask openings (pin holes,
undercut, damage, etc.)b. Moisture and chemical absorption propertiesc. Minimum cure leveld. Voltage bias on a tracee. Minimum spacing between positive and negative
features to prevent ECM
© HDP User Group International, Inc.
8
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
Identify modifications
required to current test methods
Develop DOE’s to validate proposed
changes
Perform DOE’s. Collect and
evaluate test data
Draft proposed changes to test
methods / standards / test
vehicles
Provided proposed changes
and supporting data to test
standard owners.
Write final report
• Completed list of current test methods
• Completed identification of failure modes 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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Current Project Activities
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Test Method
#
Method Type
Method Focus
Spec. Owner
Spec NumberBare
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,
7 Other Material IPC TM650, 2.6.15C Corrosion, Flux
9 CLN PCA IPC TM650,2.3.25CDetection and Measurement of Ionizable Surface
Contaminants by Resistivity of Solvent Extract (ROSE)11 CLN PCA IPC TM650,2.3.38C Surface Organic Contaminant Detection Test
12 Other PCA IPC TM650,2.3.39CSurface Organic Contaminant Detection Test (Infrared
Analytical Method)15 ECM PCA Bono
16 ECM Material HP EL-EN861-00 Flux Electrochemical Migration Test Method
18 CLN PCA IPC TM650,2.6.38 Bulk IC19 CLN PCA Foresite C3 Localized area IC
20 SIR PCA Foresite C3 Localized area Y pattern
26 CLN Material GR-78-CORE Silver Chromate Paper IPC-TM 650 2.3.33
27 Other Material GR-78-CORECopper Mirror Tests (Modified IPC / Bellcore Method) IPC-
TM 650 2.3.3228 Other Material GR-78-CORE Copper Corrosion Test IPC-TM 650 2.6.1529 Other Material GR-78-CORE Copper Corrosion Test JIS Z3197-1999 Test Method 8.4.1
30 ECM Material GR-78-CORE 13.1.4 Bellcore Electromigration
31 CLN PCA IPC TM650 IPC ROSE Test 32 SIR Material IPC IPC -920233 SIR Material JIS Z319734 ECM Material JIS Z3197
Industry Standard Test Methods to consider
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No clean flux failure modes
Failure mode dependencies:• Openings or defects in solder mask• Voltage bias • Activity level, type, and quantity of flux residue• Humidity levels
© HDP User Group International, Inc.
Potential areas to investigate with current test methods:• Modify test coupon to detect crevice or pitting corrosion failure modes?
• Solder mask openings on test coupon (pitting corrosion)• Flux trapped under low stand off connections (crevice corrosion)
• 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 humidity levels
Corrosion Mechanism:A form of crevice or pitting corrosion at the small solder mask opening and the trace.
Open Trace Corrosion Failure
12
No clean flux failure modes
Failure mode dependencies:• Voltage bias • Activity level, type, and quantity of flux residue• Humidity levels
© HDP User Group International, Inc.
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• Multiple surface finishes• Multiple humidity levels
Corrosion Mechanism:Surface corrosion
+ 3V
GND
Non soldered OSP+ 3V
Surface Corrosion Failure
13
No clean flux failure modes
Failure mode dependencies:• Openings or defects in solder mask (exposed anode / + voltage)• Voltage bias • Activity level and quantity of flux residue• Humidity levels
© HDP User Group International, Inc.
Potential areas to investigate with current test methods:• 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)
Corrosion Mechanism:Electrochemical Migration – metal dendrite growth
+ 3Vanode
GND
ECMCorrosion Failure
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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
Proposed Execution Plan
CompleteIn-ProcessNot started
Team Members –To Date
15© HDP User Group International, Inc.
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• Fujitsu• H3C• Huawei• IBM• Intel• Isola• IST Group• Kyzen• Medtronic• Nihon-Superior• Oracle• Panasonic
• Phillips• Plexus • Rockwell • Suntak• Shengyi• TTM Tech• Ventec• Zestron• ZTE