Ion Chromatography for PCB Failure Analysis
- โชว์สินค้าทั้งหมด
- No categories
September 1, 2026
Anion and Cation Analysis · Anion Test · IPC-TM-650 2.3.28 · Root Cause Investigation · Chloride and Ammonium Identification · Failure Evidence
ISO/IEC 17025 Accredited Testing Where Applicable | Anion and Cation Analysis | Chemical and Electronics Testing
A PCB assembly has been returned from the field with intermittent electrical failure. SEM examination shows corrosion on conductor surfaces. The failure mode suggests ionic contamination-driven electrochemical attack. The question that determines corrective action is not whether ionic contamination is present but which ionic species are responsible and where they came from.
Ion chromatography, commonly referred to as the anion test in electronics manufacturing, answers that question. It separates and quantifies individual ionic species in the extract from a PCB surface, providing species-level identification that points directly toward the contamination source and the process step that should be investigated. In PCB failure analysis, IC is not a routine quality check. It is a diagnostic tool.
The Role of IC in PCB Failure Investigation
Ion chromatography for PCB failure analysis differs from IC used in production quality monitoring in one important respect: the objective. In production monitoring, IC confirms that ionic contamination levels are within the specified cleanliness limit. In failure analysis, IC is used to understand what happened after a failure has already occurred.
When a PCB assembly fails in service and ionic contamination is suspected as a contributing factor, IC provides three things that other analytical techniques cannot.
Species identification. IC identifies which ionic species are present and in what quantities across three categories: anions including chloride, fluoride, bromide, sulfate, and phosphate; cations including ammonium, sodium, and potassium; and weak organic acids (WOA) including acetate, formate, and citrate, which are characteristic markers of no-clean flux residue activity. Without species identification, corrective action is guesswork.
Quantification at failure-relevant levels. Modern IC systems detect ionic species at concentrations of parts per billion in the extract solution, translating to nanograms per square centimetre on the board surface. These detection limits allow meaningful measurement even when contamination levels are low, as is often the case with field failures where the original contamination may have been borderline or where the board has experienced some self-remediation during service.
Evidence for the investigation record. A failure analysis report supported by IC data includes objective, quantitative evidence of contamination levels and species distribution. This supports decisions about corrective action, supplier responsibility, and process qualification in a way that qualitative observations cannot.
What the Key Ionic Species Indicate
The diagnostic value of IC in failure analysis comes from understanding what each ionic species indicates about its origin.
Ionic species Type Primary implication in PCB failure analysis Chloride Anion Flux activator residue, environmental chloride exposure, halogenated material contamination Fluoride Anion Specific flux formulations, etching process residues Bromide Anion Halogenated flux systems, flame retardant materials Nitrate Anion Environmental sources, cleaning chemistry Nitrite Anion Environmental sources, some process chemistry Phosphate Anion Some flux formulations, process chemical residues Sulfate Anion Environmental deposition, some flux chemistry, atmospheric contamination during storage Sodium, potassium Cation Handling contamination, process water, environmental sources Ammonium Cation No-clean flux amine activators, incompletely deactivated flux residue Calcium, magnesium Cation Process water, environmental contamination Lithium Cation Specific process chemistry, battery-related contamination Acetate, formate WOA No-clean flux activator decomposition products Citrate, malate, succinate WOA Flux chemistry residues, organic acid activators Methanesulfonate WOA Specific flux formulations Phthalate WOA Plasticiser migration, packaging contamination
Chloride is the most significant anion in PCB failure analysis. Even at low concentrations, it initiates pitting corrosion and supports dendritic growth between conductors under voltage bias. Elevated ammonium, organic amines, or WOA species such as acetate and formate indicate no-clean flux residue that has not been fully deactivated and retains corrosion-promoting properties despite a nominally clean process.
ALS Testing analyses all three ionic categories under IPC-TM-650 2.3.28: anions (chloride, fluoride, bromide, nitrate, nitrite, phosphate, sulfate), cations (ammonium, sodium, potassium, calcium, magnesium, lithium), and weak organic acids or WOA (acetate, formate, citrate, malate, succinate, methanesulfonate, phthalate). A full species profile across all three categories provides the most complete picture of contamination source and corrosion risk. IC and SEM-EDX Together in Failure Investigation Ion chromatography and SEM-EDX analysis are complementary in PCB failure investigation. Each provides information the other cannot. SEM imaging characterises the morphology of corrosion damage at the failure site: the distribution of corrosion products, the pattern of dendritic growth, the condition of solder joint surfaces, and any visible residues or contamination. EDX analysis at specific points within the corrosion zone identifies the elemental composition, which can support or question the hypothesis generated by IC results. Detecting chlorine by EDX at a corrosion site is consistent with chloride-driven corrosion. Detecting sulfur is consistent with sulfate-related attack. What EDX cannot do is quantify the contamination level across the board surface or distinguish between the many possible ionic species that contain chlorine or sulfur. IC provides that quantification and speciation, working across the full board surface rather than at specific isolated points. A complete PCB failure investigation typically uses IC to characterise the overall ionic contamination profile and identify the dominant species, and SEM-EDX to characterise the specific failure site morphology and elemental composition. Together, they provide the evidence base needed for a defensible root cause conclusion. For a broader explanation of how SEM, EDX, and FTIR contribute to failure analysis, see our guide on scanning electron microscopy analysis for failure investigation. The Extraction Method Matters The reliability of IC results in failure analysis depends on how the extraction is performed. The method must be consistent, validated, and appropriate for the investigative objective, since errors or deviations at the extraction stage propagate directly into the analytical results and can obscure or misrepresent the actual contamination state of the board. Standard procedure. IPC-TM-650 2.3.28 defines the extraction method: the board is placed in a clean vessel with 75% isopropyl alcohol and 25% deionised water, extracted at 80°C for one hour under agitation, then filtered and injected into the IC system. This dissolves ionic species from the board surface including flux residues not fully soluble in water alone. Extract as received. For failure analysis, the extraction must be performed on the assembly without prior cleaning or alteration to preserve the contamination evidence in its original state. Area-specific extraction. Where the investigation requires spatial information, a controlled volume of extraction solvent applied to a defined surface area allows IC to map where contamination is most concentrated, which can be decisive in identifying the contamination source. Limitations of IC Results in Failure Investigation IC results are powerful evidence but require careful interpretation. Three limitations apply in most failure analysis contexts. IC does not identify the responsible process step or supplier. Species identification points toward contamination sources, for example chloride toward flux residue or environmental exposure, and ammonium toward no-clean flux deactivation failure. But identifying which specific process step, supplier, or handling event introduced the contamination requires interpreting IC data in the context of the full assembly process history, materials used, handling conditions, and failure pattern. IC reflects contamination at the time of testing, not necessarily at the time of failure. In boards returned from extended service, some ionic species may have been consumed by the corrosion reactions they initiated, reducing the measured concentration below the original level. Others may have been introduced by service environment exposure after the original failure mechanism was already underway. Interpreting IC results from aged field returns requires judgement about what the data represents and what may have changed since manufacture. A single IC result has limited diagnostic power without comparison data. A contamination level that looks elevated in isolation may be normal for the process, or it may indicate a process excursion if compared against qualification data. Results from non-failed assemblies from the same production lot, or from process qualification records, provide the reference point that makes species level differences meaningful and points toward the contamination source. Frequently Asked Questions When should IC be included in a PCB failure analysis investigation? IC should be included when ionic contamination is a plausible contributor to the failure mechanism, covering most cases of corrosion, leakage current, dendritic growth, or intermittent electrical behaviour associated with humidity exposure. It should also be included when the investigation needs to differentiate between flux residue contamination and environmental contamination, since anion test species profiles typically distinguish between these sources. Can IC analysis be performed on a board that has already been through SEM examination? In most cases yes, provided the SEM examination was performed without sputter coating the board surface, and provided the board has not been cleaned or altered during the SEM investigation. Discuss the planned analytical sequence with the laboratory before any step that might affect the surface chemistry of the board. What information should I provide when submitting a failed PCB for IC analysis? The most useful information includes the assembly process description (flux type, cleaning or no-clean process), service history including environment and duration, visual or functional observations from the failure, the OEM cleanliness specification if one applies, and whether comparison samples from the same production lot are available. For no-clean assemblies, note whether WOA analysis is required alongside standard anion and cation testing, as WOA species are particularly relevant to no-clean flux residue characterisation. How does IC for failure analysis differ from routine production anion testing? The analytical method is the same. The difference is in the objective and interpretation. Production anion testing confirms ionic contamination is within the specified limit. Failure analysis IC characterises the contamination profile of a failed assembly and generates hypotheses about the source and mechanism of failure, interpreted against the full failure evidence rather than a pass or fail threshold alone. Next Steps See our full Chemical and Electronics Testing services including IC for PCB failure analysis See our Failure Analysis services including SEM-EDX for corrosion and contamination investigation Read our guide on PCB cleanliness testing and ion chromatography for production quality control context Contact our team to discuss a PCB failure analysis investigation ISO/IEC 17025 Accredited Testing Where Applicable | Anion and Cation Analysis for PCB Failure Investigation | Electronics Testing Support
Read moreIonic species Type Primary implication in PCB failure analysis Chloride Anion Flux activator residue, environmental chloride exposure, halogenated material contamination Fluoride Anion Specific flux formulations, etching process residues Bromide Anion Halogenated flux systems, flame retardant materials Nitrate Anion Environmental sources, cleaning chemistry Nitrite Anion Environmental sources, some process chemistry Phosphate Anion Some flux formulations, process chemical residues Sulfate Anion Environmental deposition, some flux chemistry, atmospheric contamination during storage Sodium, potassium Cation Handling contamination, process water, environmental sources Ammonium Cation No-clean flux amine activators, incompletely deactivated flux residue Calcium, magnesium Cation Process water, environmental contamination Lithium Cation Specific process chemistry, battery-related contamination Acetate, formate WOA No-clean flux activator decomposition products Citrate, malate, succinate WOA Flux chemistry residues, organic acid activators Methanesulfonate WOA Specific flux formulations Phthalate WOA Plasticiser migration, packaging contamination
Chloride is the most significant anion in PCB failure analysis. Even at low concentrations, it initiates pitting corrosion and supports dendritic growth between conductors under voltage bias. Elevated ammonium, organic amines, or WOA species such as acetate and formate indicate no-clean flux residue that has not been fully deactivated and retains corrosion-promoting properties despite a nominally clean process.
ALS Testing analyses all three ionic categories under IPC-TM-650 2.3.28: anions (chloride, fluoride, bromide, nitrate, nitrite, phosphate, sulfate), cations (ammonium, sodium, potassium, calcium, magnesium, lithium), and weak organic acids or WOA (acetate, formate, citrate, malate, succinate, methanesulfonate, phthalate). A full species profile across all three categories provides the most complete picture of contamination source and corrosion risk. IC and SEM-EDX Together in Failure Investigation Ion chromatography and SEM-EDX analysis are complementary in PCB failure investigation. Each provides information the other cannot. SEM imaging characterises the morphology of corrosion damage at the failure site: the distribution of corrosion products, the pattern of dendritic growth, the condition of solder joint surfaces, and any visible residues or contamination. EDX analysis at specific points within the corrosion zone identifies the elemental composition, which can support or question the hypothesis generated by IC results. Detecting chlorine by EDX at a corrosion site is consistent with chloride-driven corrosion. Detecting sulfur is consistent with sulfate-related attack. What EDX cannot do is quantify the contamination level across the board surface or distinguish between the many possible ionic species that contain chlorine or sulfur. IC provides that quantification and speciation, working across the full board surface rather than at specific isolated points. A complete PCB failure investigation typically uses IC to characterise the overall ionic contamination profile and identify the dominant species, and SEM-EDX to characterise the specific failure site morphology and elemental composition. Together, they provide the evidence base needed for a defensible root cause conclusion. For a broader explanation of how SEM, EDX, and FTIR contribute to failure analysis, see our guide on scanning electron microscopy analysis for failure investigation. The Extraction Method Matters The reliability of IC results in failure analysis depends on how the extraction is performed. The method must be consistent, validated, and appropriate for the investigative objective, since errors or deviations at the extraction stage propagate directly into the analytical results and can obscure or misrepresent the actual contamination state of the board. Standard procedure. IPC-TM-650 2.3.28 defines the extraction method: the board is placed in a clean vessel with 75% isopropyl alcohol and 25% deionised water, extracted at 80°C for one hour under agitation, then filtered and injected into the IC system. This dissolves ionic species from the board surface including flux residues not fully soluble in water alone. Extract as received. For failure analysis, the extraction must be performed on the assembly without prior cleaning or alteration to preserve the contamination evidence in its original state. Area-specific extraction. Where the investigation requires spatial information, a controlled volume of extraction solvent applied to a defined surface area allows IC to map where contamination is most concentrated, which can be decisive in identifying the contamination source. Limitations of IC Results in Failure Investigation IC results are powerful evidence but require careful interpretation. Three limitations apply in most failure analysis contexts. IC does not identify the responsible process step or supplier. Species identification points toward contamination sources, for example chloride toward flux residue or environmental exposure, and ammonium toward no-clean flux deactivation failure. But identifying which specific process step, supplier, or handling event introduced the contamination requires interpreting IC data in the context of the full assembly process history, materials used, handling conditions, and failure pattern. IC reflects contamination at the time of testing, not necessarily at the time of failure. In boards returned from extended service, some ionic species may have been consumed by the corrosion reactions they initiated, reducing the measured concentration below the original level. Others may have been introduced by service environment exposure after the original failure mechanism was already underway. Interpreting IC results from aged field returns requires judgement about what the data represents and what may have changed since manufacture. A single IC result has limited diagnostic power without comparison data. A contamination level that looks elevated in isolation may be normal for the process, or it may indicate a process excursion if compared against qualification data. Results from non-failed assemblies from the same production lot, or from process qualification records, provide the reference point that makes species level differences meaningful and points toward the contamination source. Frequently Asked Questions When should IC be included in a PCB failure analysis investigation? IC should be included when ionic contamination is a plausible contributor to the failure mechanism, covering most cases of corrosion, leakage current, dendritic growth, or intermittent electrical behaviour associated with humidity exposure. It should also be included when the investigation needs to differentiate between flux residue contamination and environmental contamination, since anion test species profiles typically distinguish between these sources. Can IC analysis be performed on a board that has already been through SEM examination? In most cases yes, provided the SEM examination was performed without sputter coating the board surface, and provided the board has not been cleaned or altered during the SEM investigation. Discuss the planned analytical sequence with the laboratory before any step that might affect the surface chemistry of the board. What information should I provide when submitting a failed PCB for IC analysis? The most useful information includes the assembly process description (flux type, cleaning or no-clean process), service history including environment and duration, visual or functional observations from the failure, the OEM cleanliness specification if one applies, and whether comparison samples from the same production lot are available. For no-clean assemblies, note whether WOA analysis is required alongside standard anion and cation testing, as WOA species are particularly relevant to no-clean flux residue characterisation. How does IC for failure analysis differ from routine production anion testing? The analytical method is the same. The difference is in the objective and interpretation. Production anion testing confirms ionic contamination is within the specified limit. Failure analysis IC characterises the contamination profile of a failed assembly and generates hypotheses about the source and mechanism of failure, interpreted against the full failure evidence rather than a pass or fail threshold alone. Next Steps See our full Chemical and Electronics Testing services including IC for PCB failure analysis See our Failure Analysis services including SEM-EDX for corrosion and contamination investigation Read our guide on PCB cleanliness testing and ion chromatography for production quality control context Contact our team to discuss a PCB failure analysis investigation ISO/IEC 17025 Accredited Testing Where Applicable | Anion and Cation Analysis for PCB Failure Investigation | Electronics Testing Support
