Ion Chromatography

for PCB and

PCA Contamination

Presented By:Foresite Inc.

Objectives

• Theory of Operation

• Basic Plumbing

• Critical Parameters to Monitor

• Columns, Materials, and Reagents

• Lab Equipment

• Making Eluents

• Making Controls and Standards

• Equipment Start-Up

• Making Programs and Schedules In Chromeleon

• Executing Batch Files in Chromeleon

• Calibrating the Chromatograph– Running Standards and Controls

– Checking for Linearity

– Optimizing Graphs

• Daily Start-up Schedules

• Daily Logs

• Sample Extractions (Standard K-Pak TSE)

• C3 Sample Extraction

Introduction to Ion Chromatography

• Characterizes and Quantifies specific residue species present on sample

• IPC condoned test method – TM-650.2.3.28– Foresite was instrumental in developing this testing

methodology

• Two extraction methods:– Standard bath, total board extraction

– Localized C3 spot extraction

What is Ion Chromatography?

• Qualifies and Quantifies specific process residues byseparating ionic and organic compounds suspended in aliquid solution.

• Separation is achieved through a finely balanced system of aliquid phase element and a charged resin column.

• Each different species travels through the column (Time ofFlight) at different rates, dependant upon the specie’s massand charge.

• Species exit the column separately and their conductivity ismeasured by a conductivity meter.

Theory of Operation

Conductivity {µS}

Time

Basic Plumbing Flow

• 1 Eluent (Mobile Phase – Carries Sample)

• 2 Pump (Moves Eluent and Sample)

• 3 Pulse Dampener (Removes pump oscillation)

• 4 Sample Valve (Injects sample into Eluent stream)

• 5 Guard Column (Filter and 20% Separation)

• 6 Analytical Column (Performs Separation)

• 7 Suppressor (Removes Counter Species)

• 8 Conductivity Cell (Measures Designated Species)

Basic Plumbing Hardware

Eluent inlet

“From Stock or E.G.”

Suppressor

“Removes Counter Ions”

Pulse Dampener

“Reduces Pump Noise”

Column Oven

“Heats Columns”

Pumps

“2-Stage”

Conductivity Cell

“Measures sample conductivity”

Sample Valve

“To Inject Sample”

Check Valve

“Prevents Back-flow”Flow Schematic

Sample Port

“For Manual Injection”

Column Selection (Why AS-22)

AG-22 & AS-22

• Carb / Bi-Carb Eluent is easy to make and control

• Column set is fairly Mature

• Water Dips do not interfere with eluent peaks

• SO4 Time of Flight is about 8-9 Min

• WOA Time of Flight is 15.5 min (Run time)

• WOA & SO4 do not Co-Elute!

• Can Resolve Formate and Acetate without using a separate Tetra

Borate Deca-Hydrate Eluent run.

• Down side - Column is NOT Alcohol Compatible >10%

Isocratic vs. Gradient

Isocratic Run

• Steady-State Eluent

• Baseline is fixed

• Elution times are fixed

• Easier to Calibrate

Gradient Run

• Can change Eluent Real time

• Baseline shifts with eluent

• Elution Times not as fixed

• More difficult to Calibrate

Typical Anions Many Manufacturers Are Concerned

With Today on Electronic Hardware

Dionex DX-120 system with a AS4A-SC 4mm Column

WOAPO4

2

NO3BrNO2

Cl

Typical Anions manufacturers are concerned

with in today’s on electronic manufacturing

Dionex ICS-2000 system with a AS-22 4mm Column Set

Typical Cations manufacturers are concerned

with in today’s on electronic manufacturing

Dionex DX-120 system with a CS12A 4 mm Column Set

Critical Perimeters to Monitor

• Back Pressure PSI

• Baseline Conductivity µS

• Elution Times Min

• Peak Separation Touch Baseline?

• Peak Profiles Bell Curve

• Control ppm Values <5% Inaccuracy

• Column / System Leakage Leak Check

• Controls and Eluent Age Refrigerate @ 40F!

Lab Equipment “The Basics”

• Ion Chromatograph

• Glass Ware (Misc)

• Lab Scale (.0001g Resolution)

• Pipettes (Fixed Volume)

• Reagents (HPLC Grade)

• Mixing Vessels

• KaPak Bags (assorted sizes)

• Clean Aluminum Foil

• Verified Clean PVC Gloves

• Syringes (Verified Clean)

• Heated Water Bath

• D.I. Water Source

• Glass Ware (Volumetric Class A)

• Calibrated Weights

• Pipette Tips

• Weighing Boats

• Storage / Delivery Vessels

• Thermal Bag Sealer

• Lint Free Lab Wipes

• Chemical Gloves

• Syringe Filters

• Line Timer

Equipment “Large Scale Lab Water System”

Reverse

Osmosis

Pre FilterIon Polish

Final

U.V.

Incoming

U.V.

Resistance

Meter

Mid Filter

“Small Scale Reagent Lab Water System”

Bench Top System

- Low output volume

+ High Quality Water

+ Minimal Investment

+ Small Foot Print

+ Low Maintenance

+ Feed in good water get out Very

Good Water!

Feeding a 18.2 house loop in will generate Ultra-Pure for I.C.

Making Carb / Bi-Carb Eluent

• Baseline conductivity is very important (16µS-18µS)

• Eluent Baseline conductivity will greatly effect peak times!

• Each Column Set is Different and will need it’s own mix!

• Make Larger Eluent Volumes to Reduce Mixing Error!

• Only use Reagent Grade Materials or (HPLC Grade)

16 liters of Eluent

• Sodium Bi-Carbonate 1.8816g

• Sodium Carbonate 7.2920g

4 liters of Eluent

• Divide by 4

Good Water for I.C.!

Good I.C. water has

minimal background Ionics

Water was polished with a

Millipore A10 fed from 18.2

megΩΩΩΩ House D.I.. @ low

TOC

Sample was shot from a

cleaned Boro-silicate vial

on a Dionex AS-50

autosampler

Calibration of I.C.

Calibration and Chromeleon Training

will be performed in the Lab

I.C. Calibration Basics

Species

LinearityAmount

Table

Good Linearity is in the

99.9 to 99.7 R2 Range

Daily Start-Up!

First!, Is the Calibration still Valid?

First Run of the Day:

• Cation Control (Dionex)

• Anion Control (Dionex)

• Level 3 Cation Standard (4ppm)

• Level 3 SO4 / WOA Acid Standard (4ppm)

• Water Blank / Syringe Blank

• Bag Blank (1hr in Water Bath)

• Anion & Cation Controls Every 10 Samples!

Documentation (Controls)

Standards should be

traceable to NIST or NBS

Documentation (Calibration)

Standards should be

traceable to NIST or NBS

Controls should have

unique documentation

codes

Pipettes should be verified

before use.

Event Log (Your System’s Diary)

Document activity on

your system to predict

system and column

failures

Extraction Protocols

• TSE (Total Standard Extraction) IPC-TM- 650 Standard 2.3.28

– Uses 75% IPA 25% D.I. (Unique volume for each PCA size)

– Heated Water Bath

– Dilution factor is calculated by Dividing Volume into Surface area.

– For Populated Boards add 10%

• Localized Extraction by C3 & Test per IPC-TM- 650 Standard 2.3.28

– Uses D.I. Water (Steam)

– Dilution factor for I.C. is based on Cell Aperture (.1sq”)

– Dilution factor is (2.2mL / .1sq” = 22)

– For Populated Boards add 10% (2.2mL / .11sq” = 20)

(Volume of Solution / Total Board Area)

TSE (Total Standard Extraction) IPC 2.3.28

Heated Water Bath with Window

Extraction Fluid Dispensing

Dispenser

75% IPA

25% D.I. Water

Dispenser must be

repeatable and

able to be

calibrated!

TSE (Total Standard Extraction - FLOAT)

Extraction solution is added to a Kapak bag to cover the board Surface.

Platform

Kapak Bag

PCA

TSE (Total Standard Extraction) FLOAT

Bath MeniscusBag Meniscus

Total Solvent Extraction VS. Localized

• TSE

– Good for bare boards

– Bad if the solder mask is not cured! It will foul the column

– Not as good on populated boards. They can give anomalous reading

due to assembly package contributions. The organics dissolve can foul

the Anion columns. Column clean-up is time consuming!!!!!

– IPA is not compatible with all column sets

– Is IPC Standard

• Localized

– Good for bare boards or populated boards

– Can check via locations vs. solder mask areas for etch residuals

– Will not foul the columns

Localized Extraction with C3

C3 Process Monitoring Tool

• Purposes of C3:

– Monitoring tool for production floor

• Focus on sensitive area of concern (0.1 in2)

• Performs electrical test and gives immediate ‘clean’ or ‘dirty’ reading

based on Foresite recommended limits for ionic contamination

– Localized extraction method for Ion Chromatography

• Extracts sample from localized testing area using deionized steam

• Samples can be shipped to a lab for Ion Chromatography analysis

Choosing Sensitive Areas to Test with C3

•Sensitive areas of circuitry

that are prone to failure

•High impedance devices

•Low standoff components

that could trap residues

Capacitor Investigation – How Clean is this Spot?

Background

-- 0805 Chip Capacitors on the battery circuit were causing the 3 volt battery to drain in less than 2 weeks on a new hand held Glucose tester prior to this new product launch. A high humidity screen was developed to separate the good units from the bad until a root cause and corrective action plan could be developed.

– It was originally thought that the capacitors were cracked, but this turned out not to be true, and standard cleanliness testing showed that this No Clean assembly process was clean and not the problem. Until we tested the failing units in just the area of the capacitor. This showed a high level of sulfate residue on the capacitor. This sulfate was not present in high quantities on the units that passed the screening test.

- 0805 Capacitors on Assemblies

Ion Chromatography C3

all values are ug/in2 Cl Br SO4 WOA Test Time

0805 Cap Good Boards

1370-122-04 Catalyst Board #1-C3 Site #4 1.11 0.07 0.13 11.62 Pass 3.00

1370-122-10 Catalyst Board #2-C3 Site #4 2.25 0.04 0.24 7.36 Pass 1.39

1370-122-16 Catalyst Board #3-C3 Site #4 1.54 0.10 0.16 5.92 Pass 1.48

1370-122-22 Catalyst Board #4-C3 Site #4 1.06 0.08 0.17 4.36 Pass 2.54

1370-122-28 Catalyst Board #5-C3 Site #4 2.04 0.18 0.21 6.52 Pass 1.69

0805 Cap Suspect Boards

1370-122-34 Catalyst Board #1 C3 Site #4 2.36 0.83 20.36 7.57 Failure 0.46

1370-122-40 Catalyst Board #2 C3 Site #4 2.15 0.53 28.26 10.14 Failure 0.15

1370-122-46 Catalyst Board #3 C3 Site #4 2.28 0.54 24.12 10.95 Failure 0.27

1370-122-52 Catalyst Board #4 C3 Site #4 3.06 0.34 29.36 7.41 Failure 0.33

1370-122-58 Catalyst Board #5 C3 Site #4 2.03 0.15 27.15 5.65 Failure 0.24

Standard Extraction Results

Ion Chromatography C3

all values are ug/in2 Cl Br SO4 WOA Test Time

Total Board Good Boards

1370-122-06 Catalyst Board #1 Total Board 0.99 0.28 0.00 7.95 N/A N/A

1370-122-12 Catalyst Board #2 Total Board 0.70 0.72 0.00 5.78 N/A N/A

1370-122-18 Catalyst Board #3 Total Board 0.51 0.87 0.00 6.48 N/A N/A

1370-122-24 Catalyst Board #4 Total Board 0.68 1.58 0.00 7.93 N/A N/A

1370-122-30 Catalyst Board #5 Total Board 0.55 0.59 0.00 6.69 N/A N/A

Total Board Suspect Boards

1370-122-36 Catalyst Board #1 Total Board 0.93 0.32 0.00 4.93 N/A N/A

1370-122-42 Catalyst Board #2 Total Board 1.05 1.97 0.00 4.41 N/A N/A

1370-122-48 Catalyst Board #3 Total Board 0.83 1.13 0.00 11.92 N/A N/A

1370-122-54 Catalyst Board #4 Total Board 1.18 0.46 0.00 3.38 N/A N/A

1370-122-60 Catalyst Board #5 Total Board 0.99 0.38 0.00 4.05 N/A N/A

Capacitor Investigation – How Clean is this Spot?

Conclusions

– The Capacitors were failing approximately 3-5% of the screening test. We found that the post plating rinses after the Barrel plating process using MSA (methane sulfonic acid) as the primary plating chemistry was not neutralized or uniformly rinsed

– The plating residue left on the capacitor surface created an invisible conductive pathway causing the failure of the off circuit due to this moisture absorbing conductive residue when sitting on the shelf in the box waiting for shipment.