ipc 3-11g mixed flowing gas (mfg) creep corrosion benchmarking test preliminary results feb 2013
TRANSCRIPT
IPC 3-11g Mixed Flowing Gas (MFG) Creep Corrosion Benchmarking Test
Preliminary Results Feb 2013
Objectives
• Replicate Alcatel-Lucent’s creep corrosion results– Will use exactly the same conditions, test
coupons and materials
• Improved MFG operating procedures
Test Vehicle
• FR4
• 4” x 5” x 0.063”
• 9 comb patterns – 7 on top, 2 on bottom– 5 comb patterns with perpendicular solder
mask strips
• 4 comb with PTHs – 2 with solder mask defined holes, 2 not
• Taiyo PSR4000 or equivalent solder mask
Surface Finish & Flux
• Surface finishes– True bare copper– SnPb HASL– OSP– iAg– ENIG
• ROL0 solder paste
• ORL0 & ROL0 wave fluxes
Test Matrix with # of Replicates
Wave flux
Surface FinishRO OR None
Bare Copper
3 3 3
SnPb HASL
3 3 3
OSP 3 3 3
iAg 3 3 3
ENIG 3 3 3
Before Testing…
• Handle by edges with nitrile gloves
• Check representative sample with IC as per IPC TM-650, Method 2.3.28
• Visually inspect & document
• Vacuum seal with no paper or desiccant
• Non-contaminating marking– Finish, flux, board #
Before Testing…
• Screen solder paste using 6 mil stencil
• Reflow once (record parameters)
• Uniform wave flux application with validated hole penetration (record parameters)
• Wave solder (record parameters)
• Coupons stored in clean aluminum foil, if required
Actual MFG Testing
• Clean chamber only if part of usual procedure (record parameters)
• Copper foil & ASTM B825-02 weighed (to nearest 0.01 mg) control samples
• Coupons & foils parallel to air flow in chamber
• Recorded, randomized placement• 40C, 70-75% RH• No bias• 20 days
Actual MFG Testing- Gas Concentrations
H2S SO2 NO2 Cl2
1700 ppb 200 ppb 200 ppb 20 ppb
Like EIA IIIA but with elevated H2S
Immediate Post Test Work
• Weigh control foils
• Record amount of creep corrosion on coupons
• Wrap in Al foil
• Send off foils & coupons for further analysis
Further Post Test Analytical Work
• EDX identification of corrosion products from each surface finish/flux combination
• Remove corrosion products & inspect surfaces of coupons and foils
• Weigh cleaned foils and calculate corrosion rate
• ASTM B825-02 corrosion rates to be determined coulometrically
Appendices to the Test Method
• A – Measurement Techniques for Determining the Amount of Wave Solder Flux Applied
• B – Visual Inspection Criteria for Creep Corrosion Evaluation• C – Worksheet for Reporting Board Inspection & Cleanliness
Testing Prior to Preconditioning• D – Worksheet for Reporting Preconditioning Results &
Parameters• E – Worksheet for Reporting Parameters from MFG Chambers• F – Worksheet for Reporting Measurements & Experimental
Results from MFG Tests• G – Worksheet for Reporting Results form ASTM B825-02
Coupons• H Procedure for Removing Corrosion Products
Test Sites
• CALCE• Battelle• Alcatel-Lucent (5d data only)• Univ. of Limerick (data not plotted yet)
Different Types of Corrosion Observed
Fiber assisted corrosion[Immersion Silver–day 5
Discoloration [Bare Copper –day 5]
Discoloration Creep[Immersion Silver–day 5]
Creep
White Patina[Bare Copper –day 10]
White Patina
Flaking[Immersion Silver–day 20]
Flaking
Green Patina[Bare Copper –day 5]
Green Patina
Board Type Day 5 Day 10 Day 15 Day 20
Cu
Cu-OR
Cu-RO
SnPb
SnPb-OR
SnPb-RO
OSP
OSP-OR
OSP-RO
ImAg
ImAg-OR
ImAg-RO
ENIG
ENIG-OR
ENIG-RO
CALCE
3 out of 3
1 out of 32 out of 3
Discoloration
BattelleALU
Board Type Day 5 Day 10 Day 15 Day 20
Cu
Cu-OR
Cu-RO
SnPb
SnPb-OR
SnPb-RO
OSP
OSP-OR
OSP-RO
ImAg
ImAg-OR
ImAg-RO
ENIG
ENIG-OR
ENIG-RO
3 out of 3
1 out of 32 out of 3
CALCE
Creep
ALU Battelle
Board Type Day 5 Day 10 Day 15 Day 20
Cu
Cu-OR
Cu-RO
SnPb
SnPb-OR
SnPb-RO
OSP
OSP-OR
OSP-RO
ImAg
ImAg-OR
ImAg-RO
ENIG
ENIG-OR
ENIG-RO
3 out of 3
1 out of 32 out of 3
CALCE
Greening
ALU (none) Battelle (none)
Board Type Day 5 Day 10 Day 15 Day 20
Cu
Cu-OR
Cu-RO
SnPb
SnPb-OR
SnPb-RO
OSP
OSP-OR
OSP-RO
ImAg
ImAg-OR
ImAg-RO
ENIG
ENIG-OR
ENIG-RO
3 out of 3
1 out of 32 out of 3
CALCE
Flaking
BattelleALU (none)
Board Type Day 5 Day 10 Day 15 Day 20
Cu
Cu-OR
Cu-RO
SnPb
SnPb-OR
SnPb-RO
OSP
OSP-OR
OSP-RO
ImAg
ImAg-OR
ImAg-RO
ENIG
ENIG-OR
ENIG-RO
3 out of 3
1 out of 32 out of 3
White
CALCE ALU (none) Battelle
SUMMARY DATA FOR EACH CHAMBER
ResultsBoard Type Day 5 Day 10 Day 15 Day 20
Cu
Cu-OR
Cu-RO
SnPb
SnPb-OR
SnPb-RO
OSP
OSP-OR
OSP-RO
ImAg
ImAg-OR
ImAg-RO
ENIG
ENIG-OR
ENIG-RO
Discoloration Creep WhiteFlakingGreen
3 out of 3
1 out of 32 out of 3
Creep Corrosion Results - CALCE
Board Type Day 5 Day 10 Day 15 Day 20
Cu
Cu-OR
Cu-RO
SnPb
SnPb-OR
SnPb-RO
OSP
OSP-OR
OSP-RO
ImAg
ImAg-OR
ImAg-RO
ENIG
ENIG-OR
ENIG-RO
Results Discoloration Creep WhiteFlakingGreenCreep Corrosion Results - Battelle
ResultsBoard Type Day 5 Day 10 Day 15 Day 20
Cu
Cu-OR
Cu-RO
SnPb
SnPb-OR
SnPb-RO
OSP
OSP-OR
OSP-RO
ImAg
ImAg-OR
ImAg-RO
ENIG
ENIG-OR
ENIG-RO
Discoloration Creep WhiteFlakingGreen
3 out of 3
1 out of 32 out of 3
ALCATEL LUCENT RESULTS
BACKUP
Creep Corrosion ClassificationPTH Creep
No Creep Pre-CreepBuild up of corrosion product to edge
of solder mask
Minor CreepCorrosion onto solder mask
Severe CreepCorrosion forms film
Creep Corrosion ClassificationCreep on traces
No Creep Minor Creep .Major Creep
Minor – Corrosion product from trace on solder mask
Major – Corrosion product from trace forms a film
Type Day 5 Day 10 Day 15 Day 20
Cu
Cu-OR
Cu-RO
SnPb
SnPb-OR
SnPb-RO
OSP
OSP-OR
OSP-RO
ImAg
ImAg-OR
ImAg-RO
ENIG
ENIG-OR
ENIG-RO
Pre-Creep Minor SeverePTH: Minor SevereTrace:
3 out of 3
1 out of 32 out of 3
Creep Corrosion Results - CALCE
Type Day 5 Day 10 Day 15 Day 20
Cu
Cu-OR
Cu-RO
SnPb
SnPb-OR
SnPb-RO
OSP
OSP-OR
OSP-RO
ImAg
ImAg-OR
ImAg-RO
ENIG
ENIG-OR
ENIG-RO
Pre-Creep Minor SeverePTH: MinorSever
eTrace:
3 out of 3
1 out of 32 out of 3
ALCATEL LUCENT RESULTS
Type Day 5 Day 10 Day 15 Day 20
Cu
Cu-OR
Cu-RO
SnPb
SnPb-OR
SnPb-RO
OSP
OSP-OR
OSP-RO
ImAg
ImAg-OR
ImAg-RO
ENIG
ENIG-OR
ENIG-RO
Pre-Creep Minor SeverePTH: MinorSever
eTrace:
3 out of 3
1 out of 32 out of 3
Creep Corrosion Results - Battelle
Steps for corrosion classification1) Identify features of interest and features that will be used to
differentiate between different corrosion phenomena
2) Identify levels of corrosion and features that will be used to determine severity
3) Examine samples, taking sample images when different corrosion phenomena occur or corrosion severity increases
4) Combine results for all samples in a single graphic
The following charts provide images of corrosion type and/or classification, an overview chart, and supporting documentation.Slides 3-6 cover overall corrosion. Slides 7-18 cover creep corrosion.