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Transcript of corrosion and reliability characteristics of fluxes - michalkiewicz 2013 v2.pdf
Renee Michalkiewicz,General Manager
Trace Laboratories, Inc. – BaltimoreChairman, IPC J-STD-004 Flux
Specification Task Group
Renee Michalkiewicz,General Manager
Trace Laboratories, Inc. – BaltimoreChairman, IPC J-STD-004 Flux
Specification Task Group
1
Flux Corrosion and PCA Reliability OverviewFlux Corrosion and PCA Reliability Overview
Background
Soldering Flux Qualification Tests for Corrosion
Introduction to Turbini-modified Bono Test
Assembly Process Validation Testing
Product Failures Related to Flux-Induced Corrosion
Assembly Process Improvement
Background
Soldering Flux Qualification Tests for Corrosion
Introduction to Turbini-modified Bono Test
Assembly Process Validation Testing
Product Failures Related to Flux-Induced Corrosion
Assembly Process Improvement
Copyright 2013 TraceLaboratories. All rights reserved.
BackgroundBackground
Flux Corrosion by Definition Chemical Corrosion is a process in which a solid,
especially a metal, is eaten away and changed by achemical action
Electrolytic Corrosion is an electrochemical process inwhich one metal corrodes preferentially to another whenboth metals are in electrical contact in the presence of anelectrolyte
Electromigration Video:http://www.youtube.com/user/TraceLabs
Flux Corrosion by Definition Chemical Corrosion is a process in which a solid,
especially a metal, is eaten away and changed by achemical action
Electrolytic Corrosion is an electrochemical process inwhich one metal corrodes preferentially to another whenboth metals are in electrical contact in the presence of anelectrolyte
Electromigration Video:http://www.youtube.com/user/TraceLabs
Copyright 2013 TraceLaboratories. All rights reserved.
Copyright 2013 TraceLaboratories. All rights reserved.
BackgroundBackground
Fluxes for use in electronics have been qualifiedsince the 1950’s through MIL-F-14256, Flux,Soldering, Liquid, Paste Flux, Solder Paste andSolder-Paste Flux, (For Electronic/Electrical Use)General Specification for (1956 - 1995)Prior to Joint Standard (IPC J-STD-004), IPC-SF-818 was also in place (1988 - 1995)Flux residue activity has been measured since thebeginningFlux chemistry has changed but concernsregarding active flux residues have not
Fluxes for use in electronics have been qualifiedsince the 1950’s through MIL-F-14256, Flux,Soldering, Liquid, Paste Flux, Solder Paste andSolder-Paste Flux, (For Electronic/Electrical Use)General Specification for (1956 - 1995)Prior to Joint Standard (IPC J-STD-004), IPC-SF-818 was also in place (1988 - 1995)Flux residue activity has been measured since thebeginningFlux chemistry has changed but concernsregarding active flux residues have not
Copyright 2013 TraceLaboratories. All rights reserved.
BackgroundBackground
Concerns with active flux residue
Can cause degradation of copper circuit which could lead toan open circuit
Can lead to formation of dendrites which could lead to ashort circuit
Case studies are provided at the end of the presentation
Concerns with active flux residue
Can cause degradation of copper circuit which could lead toan open circuit
Can lead to formation of dendrites which could lead to ashort circuit
Case studies are provided at the end of the presentation
Copyright 2013 TraceLaboratories. All rights reserved.
Soldering Flux Qualification Tests for CorrosionSoldering Flux Qualification Tests for Corrosion
IPC J-STD-004, Requirements for Soldering Fluxes
Used to classify flux activity (1995 to present)
Product qualification, not assembly process validation
Four tests to evaluate corrosive properties of flux Copper Mirror Corrosion Surface Insulation Resistance (SIR) Electrochemical Migration (ECM)
IPC J-STD-004, Requirements for Soldering Fluxes
Used to classify flux activity (1995 to present)
Product qualification, not assembly process validation
Four tests to evaluate corrosive properties of flux Copper Mirror Corrosion Surface Insulation Resistance (SIR) Electrochemical Migration (ECM)
Copyright 2013 TraceLaboratories. All rights reserved.
Soldering Flux Qualification Tests for CorrosionSoldering Flux Qualification Tests for Corrosion
Copper Mirror Test IPC-TM-650, Method 2.3.32 Flux is tested as-received Determines the removal effect the flux has on bright copper
mirror film deposited on glass slide
Copper Mirror Test IPC-TM-650, Method 2.3.32 Flux is tested as-received Determines the removal effect the flux has on bright copper
mirror film deposited on glass slide
Copyright 2013 TraceLaboratories. All rights reserved.
L M HNo Breakthrough Less Than 50% Breakthrough Greater Than 50% Breakthrough
Soldering Flux Qualification Tests for CorrosionSoldering Flux Qualification Tests for Corrosion
Corrosion Test IPC-TM-650, Method 2.6.15 Flux is tested after reflow Determines the corrosive properties of flux residues
following 10 days of 50°C / 95%RH A pellet of solder is melted in contact with the test flux on a
copper test panel
Corrosion Test IPC-TM-650, Method 2.6.15 Flux is tested after reflow Determines the corrosive properties of flux residues
following 10 days of 50°C / 95%RH A pellet of solder is melted in contact with the test flux on a
copper test panel
Copyright 2013 TraceLaboratories. All rights reserved.
No CorrosionNo Corrosion Minor CorrosionMinor Corrosion Major CorrosionMajor Corrosion
Soldering Flux Qualification Tests for CorrosionSoldering Flux Qualification Tests for Corrosion
Surface Insulation Resistance (SIR) IPC-TM-650, Method 2.6.3.7 Flux is tested after reflow Determines the corrosive properties of flux residues (as well
as leakage current development) under 40°C / 90%RHenvironment for 7 days
Surface Insulation Resistance (SIR) IPC-TM-650, Method 2.6.3.7 Flux is tested after reflow Determines the corrosive properties of flux residues (as well
as leakage current development) under 40°C / 90%RHenvironment for 7 days
Copyright 2013 TraceLaboratories. All rights reserved.
Soldering Flux Qualification Tests for CorrosionSoldering Flux Qualification Tests for Corrosion
Chemical corrosion and electrolytic corrosion are reasonsfor failure
Copyright 2013 TraceLaboratories. All rights reserved.
Soldering Flux Qualification Tests for CorrosionSoldering Flux Qualification Tests for Corrosion
Electrochemical Migration (ECM) IPC-TM-650, Method 2.6.14.1 Flux is tested after reflow Determines the corrosive properties of flux residues (as well
as IR degradation) under 65°C / 88.5%RH environment for21 days
Electrochemical Migration (ECM) IPC-TM-650, Method 2.6.14.1 Flux is tested after reflow Determines the corrosive properties of flux residues (as well
as IR degradation) under 65°C / 88.5%RH environment for21 days
Copyright 2013 TraceLaboratories. All rights reserved.
Soldering Flux Qualification Tests for CorrosionSoldering Flux Qualification Tests for Corrosion
Again, chemical corrosion and electrolytic corrosion arereasons for failure
Copyright 2013 TraceLaboratories. All rights reserved.
Introduction to TurbiniIntroduction to Turbini--modified Bono Testmodified Bono Test
Characterizing Corrosion Effects Recently modified to better quantify and characterize the
corrosive effects of WOA flux on copper circuits WOA solutions used were abietic, succinic, glutaric, adipic and malic
acids (Experiment did not use full flux chemistry) Study found 60°C / 93%RH for 10 days to be the best to
detect differences in the WOA’s
Characterizing Corrosion Effects Recently modified to better quantify and characterize the
corrosive effects of WOA flux on copper circuits WOA solutions used were abietic, succinic, glutaric, adipic and malic
acids (Experiment did not use full flux chemistry) Study found 60°C / 93%RH for 10 days to be the best to
detect differences in the WOA’s
Copyright 2013 TraceLaboratories. All rights reserved.
Soldering Process ValidationSoldering Process Validation TestingTesting
SIR testing per IPC-9202 / IPC-9203 Different from product qualification Tests all chemistries on standardly designed test vehicle
(IPC-B-52) Can use commercially available test boards or you could
have your board manufacturer / CM site produce Need to use “dummy” non-active components
SIR testing per IPC-9202 / IPC-9203 Different from product qualification Tests all chemistries on standardly designed test vehicle
(IPC-B-52) Can use commercially available test boards or you could
have your board manufacturer / CM site produce Need to use “dummy” non-active components
Copyright 2013 TraceLaboratories. All rights reserved.
AssemblyAssembly Process ValidationProcess Validation TestingTesting
SIR test patterns are placed below the components The assemblies are run through an SIR environment as
mentioned in previous slides Adverse reactions between the assembly process
chemistries are assessed through electrical monitoring andvisual examination for evidence of corrosion
Allows for assessment of new assembly process prior tobuilding actual product
Drawback: Board is a test board so it cannot exactlysimulate all assembly challenges
SIR test patterns are placed below the components The assemblies are run through an SIR environment as
mentioned in previous slides Adverse reactions between the assembly process
chemistries are assessed through electrical monitoring andvisual examination for evidence of corrosion
Allows for assessment of new assembly process prior tobuilding actual product
Drawback: Board is a test board so it cannot exactlysimulate all assembly challenges
Copyright 2013 TraceLaboratories. All rights reserved.
Example Case Study #1Example Case Study #1
Major auto supplier experiencing intermittentfailures in electronic system Root cause failure analysis led to investigation of materials
used in assembly process; dendritic growth was suspecteddue to black carbonized debris found between isolatedcircuits
Major auto supplier experiencing intermittentfailures in electronic system Root cause failure analysis led to investigation of materials
used in assembly process; dendritic growth was suspecteddue to black carbonized debris found between isolatedcircuits
Copyright 2013 TraceLaboratories. All rights reserved.
Example Case Study #1Example Case Study #1
When the flux supplier was questioned, it was revealed thatthe flux raw materials had not been tested in 15 years
Testing of the flux showed a moderate activity level per J-STD-004 – the material was being sold as a no-clean
J-STD-004 requires retesting if source of raw materialchanges, but no one is currently policing suppliers
When the flux supplier was questioned, it was revealed thatthe flux raw materials had not been tested in 15 years
Testing of the flux showed a moderate activity level per J-STD-004 – the material was being sold as a no-clean
J-STD-004 requires retesting if source of raw materialchanges, but no one is currently policing suppliers
Copyright 2013 TraceLaboratories. All rights reserved.
“Qualified” Soldering Fluxes“Qualified” Soldering Fluxes
J-STD-004 Qualified Fluxes
Fluxes often qualified once and never tested again
Over the years, source of raw materials change
Activity of flux changes
In my experience, happens more often in companies that donot participate in IPC and have less of an understanding ofthe specification requirements.
J-STD-004 Qualified Fluxes
Fluxes often qualified once and never tested again
Over the years, source of raw materials change
Activity of flux changes
In my experience, happens more often in companies that donot participate in IPC and have less of an understanding ofthe specification requirements.
Copyright 2013 TraceLaboratories. All rights reserved.
Example Case Study #1Example Case Study #1
How to improve your assembly reliability
Use reputable flux suppliers
Periodically request most recent qualification and lotscreening test results; ask date of testing; illicit help fromsomeone who understands flux testing results; do not rely ontechnical datasheets; this information is often many years old
IPC has initiated a pilot program to begin a QPL for fluxmaterials under Randy Cherry, IPC Director of ValidationServices; once this is available, IPC will be policing suppliers
How to improve your assembly reliability
Use reputable flux suppliers
Periodically request most recent qualification and lotscreening test results; ask date of testing; illicit help fromsomeone who understands flux testing results; do not rely ontechnical datasheets; this information is often many years old
IPC has initiated a pilot program to begin a QPL for fluxmaterials under Randy Cherry, IPC Director of ValidationServices; once this is available, IPC will be policing suppliers
Copyright 2013 TraceLaboratories. All rights reserved.
Example Case Study #2Example Case Study #2
Implantable medical device experiencing failuresduring in-circuit test Audit of facility showed tight control on automated assembly
process including cleanliness testing during each shift ofproduction
Review of hand soldering installation of battery revealed useof “H” level flux with no cleaning or cleanliness testingfollowing soldering
Additionally, there was no control on the volume of flux usedin this step and excessive unreacted flux was found acrossthe entire circuit surface
Implantable medical device experiencing failuresduring in-circuit test Audit of facility showed tight control on automated assembly
process including cleanliness testing during each shift ofproduction
Review of hand soldering installation of battery revealed useof “H” level flux with no cleaning or cleanliness testingfollowing soldering
Additionally, there was no control on the volume of flux usedin this step and excessive unreacted flux was found acrossthe entire circuit surface
Copyright 2013 TraceLaboratories. All rights reserved.
Example Case Study #2Example Case Study #2
Temperature / Humidity testing was run on actual product torecreate the failure
Photos below show dendritic growth on actual assembly With tighter control added to battery soldering, the failures
were eliminated
Temperature / Humidity testing was run on actual product torecreate the failure
Photos below show dendritic growth on actual assembly With tighter control added to battery soldering, the failures
were eliminated
Copyright 2013 TraceLaboratories. All rights reserved.
Example CaseExample Case Study #2Study #2
How to improve your assembly reliability
Be sure to have controls on all stages of the solderingprocess
Verify assembly process through process validation studies
How to improve your assembly reliability
Be sure to have controls on all stages of the solderingprocess
Verify assembly process through process validation studies
Copyright 2013 TraceLaboratories. All rights reserved.
Example Case Study #3Example Case Study #3
Company that makes security systems experiencedfield failure returns of a camera correction board Excessive flux residue was observed around the BGA that
was determined to be the failure location
Company that makes security systems experiencedfield failure returns of a camera correction board Excessive flux residue was observed around the BGA that
was determined to be the failure location
Copyright 2013 TraceLaboratories. All rights reserved.
Example Case Study #3Example Case Study #3
Non-destructive X-ray analysis showed dendritic growthbranching from several solder balls to adjacent isolatedcircuits
Copyright 2013 TraceLaboratories. All rights reserved.
Example Case Study #3Example Case Study #3
The BGA component was removed for additional evaluationof dendrites bridging conductors and copper corrosion
Copyright 2013 TraceLaboratories. All rights reserved.
Example Case Study #3Example Case Study #3
FTIR analysis of flux showed match to specific water washtacky rework flux
Statement from technical datasheet reads:
“Meets IPC ANSI-J-STD-006 requirements for ORL0, WaterSoluble”
Does anyone know what is incorrect with this statement?
Additionally, DSC ΔTg analysis suggested that PCB wasnot fully cured; this could exacerbate issue by trappingresidues
FTIR analysis of flux showed match to specific water washtacky rework flux
Statement from technical datasheet reads:
“Meets IPC ANSI-J-STD-006 requirements for ORL0, WaterSoluble”
Does anyone know what is incorrect with this statement?
Additionally, DSC ΔTg analysis suggested that PCB wasnot fully cured; this could exacerbate issue by trappingresidues
Copyright 2013 TraceLaboratories. All rights reserved.
Example Case Study #3Example Case Study #3
How to improve your assembly reliability
Control process steps that are not part of normal process –i.e. rework
Rework flux must see full heat to be fully activated
Look for “red flags” on product datasheets that flux supplierdoes not have understanding of product specifications
Verify assembly process through process validation studies
How to improve your assembly reliability
Control process steps that are not part of normal process –i.e. rework
Rework flux must see full heat to be fully activated
Look for “red flags” on product datasheets that flux supplierdoes not have understanding of product specifications
Verify assembly process through process validation studies
Copyright 2013 TraceLaboratories. All rights reserved.
Example Case Study #4Example Case Study #4
Military OEM had Field Failure Return;Circuit on Assembly Measuring Open; Neededto determine Root Cause Microsection was taken in area of open circuit Missing copper in tented via led to conclusion that flux and
cleaning solutions had been trapped within via
Military OEM had Field Failure Return;Circuit on Assembly Measuring Open; Neededto determine Root Cause Microsection was taken in area of open circuit Missing copper in tented via led to conclusion that flux and
cleaning solutions had been trapped within via
Copyright 2013 TraceLaboratories. All rights reserved.
C.HillmanC.Hillman
Example Case Study #4Example Case Study #4
How to improve your assembly reliability
Do not tent via on one side of board
Make sure vias are completely tented; no solder mask voids
How to improve your assembly reliability
Do not tent via on one side of board
Make sure vias are completely tented; no solder mask voids
Copyright 2013 TraceLaboratories. All rights reserved.
Summary of RecommendationsSummary of Recommendations
Use reputable flux suppliers Periodically request most recent qualification and lot
screening test results Be sure to have controls on all stages of the soldering
process Verify assembly process through process validation studies Control process steps that are not part of normal process –
i.e. rework Rework flux must see full heat to be fully activated Look for “red flags” on product datasheets that flux supplier
does not have understanding of product specifications Do not tent via on one side of board Make sure vias are completely tented; no solder mask voids
Use reputable flux suppliers Periodically request most recent qualification and lot
screening test results Be sure to have controls on all stages of the soldering
process Verify assembly process through process validation studies Control process steps that are not part of normal process –
i.e. rework Rework flux must see full heat to be fully activated Look for “red flags” on product datasheets that flux supplier
does not have understanding of product specifications Do not tent via on one side of board Make sure vias are completely tented; no solder mask voids
Copyright 2013 TraceLaboratories. All rights reserved.
ACKNOWLEDGEMENTACKNOWLEDGEMENT
Thanks go out to the following Trace managersand test engineers for providing case studyinformation, photographs and video:Keith SellersMichael AllisonDaniel PhillipsDaniel Olsen
Thanks go out to the following Trace managersand test engineers for providing case studyinformation, photographs and video:Keith SellersMichael AllisonDaniel PhillipsDaniel Olsen
Copyright 2013 TraceLaboratories. All rights reserved.
REFERENCE ACKNOWLEDGEMENTREFERENCE ACKNOWLEDGEMENT
MIL-F-14256, Flux, Soldering, Liquid, PasteFlux, Solder Paste and Solder-Paste Flux, (ForElectronic/Electrical Use) General Specificationfor (1956)
IPC-SF-818, General Requirement for ElectronicSoldering Fluxes
IPC J-STD-004B, Requirements for SolderingFluxes (2008)
Zhou, et al. - Characterizing Corrosion Effects ofWeak Organic Acids Using a Modified Bono Test(2013)
MIL-F-14256, Flux, Soldering, Liquid, PasteFlux, Solder Paste and Solder-Paste Flux, (ForElectronic/Electrical Use) General Specificationfor (1956)
IPC-SF-818, General Requirement for ElectronicSoldering Fluxes
IPC J-STD-004B, Requirements for SolderingFluxes (2008)
Zhou, et al. - Characterizing Corrosion Effects ofWeak Organic Acids Using a Modified Bono Test(2013)
Copyright 2013 TraceLaboratories. All rights reserved.
REFERENCE ACKNOWLEDGEMENTREFERENCE ACKNOWLEDGEMENT
IPC-9202, Material and ProcessCharacterization / Qualification (2011)
IPC-9203, Users Guide to IPC-9202 and theIPC-B-52 Standard Test Vehicle (2012)
C. Hillman, Improved Methodologies forIdentifying Root-Cause of Printed Board Failures(2005)
IPC-9202, Material and ProcessCharacterization / Qualification (2011)
IPC-9203, Users Guide to IPC-9202 and theIPC-B-52 Standard Test Vehicle (2012)
C. Hillman, Improved Methodologies forIdentifying Root-Cause of Printed Board Failures(2005)
Copyright 2013 TraceLaboratories. All rights reserved.
Renee Michalkiewicz410-229-4360
Renee Michalkiewicz410-229-4360
Copyright 2013 Trace Laboratories. All rightsreserved.
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Live Video of Dendritic GrowthLive Video of Dendritic Growth
Copyright 2013 TraceLaboratories. All rights reserved.