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.