Ionic contamination is one of the most critical and overlooked reliability threats in electronic assemblies. In this article, we explain what it is, how it affects the long-term performance of your devices, how to detect it in the lab, and what measures can be implemented to reduce its impact.
What is Ionic Contamination?
In electronics manufacturing, ionic contamination refers to the presence of water-soluble ionic residues on a printed circuit board assembly (PCBA). These residues typically stem from:
- Incomplete removal of soldering fluxes
- Residues from human handling (sodium, potassium, chloride)
- Inadequate cleaning or rinsing procedures
- Cross-contamination from packaging, tools, or environment
These contaminants consist of mobile ions such as Na⁺, Cl⁻, K⁺, SO₄²⁻, which can dissolve in moisture. When moisture is present — especially in humid environments — these ions can migrate across the board’s surface, leading to electrochemical degradation.
Ionic contamination is particularly dangerous because it may not affect immediate functionality, but can cause latent or long-term failures, which are harder to detect and more costly to resolve in field applications.
Why is Ionic Contamination a problem?
The presence of ionic residues can severely compromise the reliability and safety of electronic assemblies. The most common failure mechanisms include:
- Latent or intermittent failures: Failures that appear only after the product is deployed and exposed to environmental stress (temperature, humidity). These are especially critical in industrial, medical or automotive applications.
- Galvanic corrosion: Electrochemical reactions are triggered between dissimilar metals, accelerated by moisture and ions. This leads to progressive damage of solder joints and conductive traces.
- Formation of dendrites and electrical shorts: Under bias, ions migrate and form conductive dendritic structures between pads or traces, resulting in intermittent or permanent short circuits.
- Reduction of Surface Insulation Resistance (SIR): The insulating capability between adjacent conductors decreases, increasing leakage currents and signal degradation.
How can Ionic Contamination be detected?
Since ionic contamination is invisible to the naked eye, it requires specialized testing and laboratory equipment. At NUFESA LABS, we use industry-standard methods for precise detection and quantification:
C3
The C3 test (Cubic Crystal Counter) is a test primarily used to detect and quantify ionic contamination on small surfaces of printed circuit boards (PCBs) and electronic components. This test focuses on measuring ionic residues present on the circuit substrate.
ROSE Test (Resistivity of Solvent Extract – IPC-TM-650, Method 2.3.25)
The ROSE test (Resistivity of Solvent Extract) is a test used to measure the ionic contamination present on the surfaces of printed circuit boards (PCBs) and electronic assemblies.
This test is used to verify the cleanliness of the boards after the soldering or assembly process, with the aim of identifying any ionic residues that could affect the reliability of the product.
Ion Chromatography (IC)
The IC test (Ion Chromatography) is a technique used to detect and quantify the presence of contaminant ions on the surfaces of PCBAs. This test is especially useful for identifying specific ions, such as chlorides, sulfates, nitrates, among others, and help us to determine the origin of the contamination.
Both methods are non-destructive and can be applied to whole boards or specific sections for failure analysis or process validation.
How can it be prevented?
Preventing ionic contamination involves both process optimization and contamination control protocols. We recommend:
- Validating cleaning processes with regular ROSE and IC tests.
- Reviewing flux usage: no-clean fluxes should be used only when fully compatible with reliability requirements.
- Avoiding manual handling without gloves.
- Monitoring humidity control in assembly and storage areas.
- Auditing materials and packaging for potential contamination risks.
- Implementing periodic lab assessments as part of quality control strategy.
According to our experience, contamination risks can often be reduced dramatically with small changes in process or material selection — but only if detected early.
Ionic contamination is silent but deadly. It doesn’t leave visible marks, and its effects often appear after the product is in use — when the cost of failure is highest.
At NUFESA LABS, we support electronics manufacturers and engineering teams with:
- Precise ionic residue quantification
- Validation of cleaning processes and flux compatibility
- Root cause analysis of latent or intermittent failures
- Tailored contamination control protocols
Need to evaluate the ionic cleanliness of your assemblies? Contact our lab team to schedule an analysis.