Ion Chromatography for PCB and PCA Contamination. Presented By: Foresite Inc.

Transcription

1 Ion Chromatography for PCB and PCA Contamination Presented By: Foresite Inc.

2 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

3 Introduction to Ion Chromatography Characterizes and Quantifies specific residue species present on sample IPC condoned test method TM Foresite was instrumental in developing this testing methodology Two extraction methods: Standard bath, total board extraction Localized C3 spot extraction

4 What is Ion Chromatography? Qualifies and Quantifies specific process residues by separating ionic and organic compounds suspended in a liquid solution. Separation is achieved through a finely balanced system of a liquid phase element and a charged resin column. Each different species travels through the column (Time of Flight) at different rates, dependant upon the specie s mass and charge. Species exit the column separately and their conductivity is measured by a conductivity meter.

5 Theory of Operation Conductivity {µs} Time

6 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)

7 Basic Plumbing Hardware Eluent inlet From Stock or E.G. Conductivity Cell Measures sample conductivity Pulse Dampener Reduces Pump Noise Sample Valve To Inject Sample Check Valve Prevents Back-flow Suppressor Removes Counter Ions Column Oven Heats Columns Sample Port For Manual Injection Pumps 2-Stage Flow Schematic

8 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 & SO 4 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%

9 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

10 Typical Anions Many Manufacturers Are Concerned With Today on Electronic Hardware Dionex DX-120 system with a AS4A-SC 4mm Column Cl NO 2 Br NO 3 PO 4 2 WOA

11 Typical Anions manufacturers are concerned with in today s on electronic manufacturing Dionex ICS-2000 system with a AS-22 4mm Column Set

12 Typical Cations manufacturers are concerned with in today s on electronic manufacturing Dionex DX-120 system with a CS12A 4 mm Column Set

13 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 40F!

14 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

15 Equipment Large Scale Lab Water System Incoming U.V. Reverse Osmosis Resistance Meter Final U.V. Pre Filter Ion Polish Mid Filter

16 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.

17 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 g Sodium Carbonate g Divide by 4 4 liters of Eluent

18 Good Water for I.C.! Good I.C. water has minimal background Ionics Water was polished with a Millipore A10 fed from 18.2 megω House low TOC Sample was shot from a cleaned Boro-silicate vial on a Dionex AS-50 autosampler

19 Calibration of I.C. Calibration and Chromeleon Training will be performed in the Lab

20 I.C. Calibration Basics Amount Table Species Good Linearity is in the 99.9 to 99.7 R 2 Range Linearity

21 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 SO 4 / WOA Acid Standard (4ppm) Water Blank / Syringe Blank Bag Blank (1hr in Water Bath) Anion & Cation Controls Every 10 Samples!

22 Documentation (Controls) Standards should be traceable to NIST or NBS

23 Documentation (Calibration) Standards should be traceable to NIST or NBS Controls should have unique documentation codes Pipettes should be verified before use.

24 Event Log (Your System s Diary) Document activity on your system to predict system and column failures

25 Extraction Protocols TSE (Total Standard Extraction) IPC-TM- 650 Standard 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% (Volume of Solution / Total Board Area) Localized Extraction by C3 & Test per IPC-TM- 650 Standard 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)

26 TSE (Total Standard Extraction) IPC Heated Water Bath with Window

27 Extraction Fluid Dispensing Dispenser Dispenser must be repeatable and able to be calibrated! 75% IPA 25% D.I. Water

28 TSE (Total Standard Extraction - FLOAT) Extraction solution is added to a Kapak bag to cover the board Surface. Kapak Bag PCA Platform

29 TSE (Total Standard Extraction) FLOAT Bag Meniscus Bath Meniscus

30 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

31 Localized Extraction with C3

32 C3 Process Monitoring Tool Purposes of C3: Monitoring tool for production floor Focus on sensitive area of concern (0.1 in 2 ) 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

33 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

34 Capacitor Investigation How Clean is this Spot? Background 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.

35 Capacitors on Assemblies Ion Chromatography C3 all values are ug/in2 Cl Br SO4 WOA Test Time 0805 Cap Good Boards Catalyst Board #1-C3 Site # Pass Catalyst Board #2-C3 Site # Pass Catalyst Board #3-C3 Site # Pass Catalyst Board #4-C3 Site # Pass Catalyst Board #5-C3 Site # Pass Cap Suspect Boards Catalyst Board #1 C3 Site # Failure Catalyst Board #2 C3 Site # Failure Catalyst Board #3 C3 Site # Failure Catalyst Board #4 C3 Site # Failure Catalyst Board #5 C3 Site # Failure 0.24

36 Standard Extraction Results Ion Chromatography C3 all values are ug/in2 Cl Br SO4 WOA Test Time Total Board Good Boards Catalyst Board #1 Total Board N/A N/A Catalyst Board #2 Total Board N/A N/A Catalyst Board #3 Total Board N/A N/A Catalyst Board #4 Total Board N/A N/A Catalyst Board #5 Total Board N/A N/A Total Board Suspect Boards Catalyst Board #1 Total Board N/A N/A Catalyst Board #2 Total Board N/A N/A Catalyst Board #3 Total Board N/A N/A Catalyst Board #4 Total Board N/A N/A Catalyst Board #5 Total Board N/A N/A

37 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.