What causes printed circuit boards to fail? Ionic contamination ranks high on the list, accounting for an estimated 25% of failures.
Contaminants can be introduced in virtually any step of the manufacturing process. Some examples include inorganic or organic acids from product components such as flux, sodium and chloride from poor handling, and potassium and sulfates from an incomplete cleaning process.
With so many possible contaminants and points of entry, how do we know which substances and processes to blame? Ionic testing holds the answer.
Ionic Testing for Printed Circuit Boards
Two methods are commonly used to identify contaminants on printed circuit boards — the Resistivity of Solvent Extract (ROSE) test and Ion Chromatography (IC) testing.
The ROSE Test
This quick-and-easy test is often used in production environments to gauge the overall cleanliness of manufactured products. During testing, a sample is extracted using a solution of isopropyl alcohol and ultrapure, deionized water. This sample is then run through a dynamic ionic testing unit that measures the sample’s resistance, using a conductivity bridge and a liquid conductivity cell.
The ROSE test identifies total ionic contamination but doesn’t identify the specific ions present. So, it can’t help you identify the reason for a high conductivity or low resistance reading. In other words, you’ll know you have a problem but not necessarily what’s causing it.
Ion Chromatography Testing
Like the ROSE test, IC testing uses a sample extracted using a solution of isopropyl alcohol and ultrapure, deionized water, but the process and output are different.
IC testing uses a high-performance liquid chromatography system to identify positively and negatively charged ions.. The amount of ionic contamination can then be related back to the surface area extracted to determine the amount of ionic contamination per surface area. The data from IC testing can be compared to known requirements for establishing process control or failure analysis.
ROSE Test vs. Ion Chromatography For Printed Circuit Boards
So, how do you choose between the ROSE and IC tests to identify contaminants on printed circuit boards? It depends on your needs. While the ROSE test is faster, IC provides more data. The ROSE test is excellent for providing bulk analysis of ions in a production line environment, but to uncover the clues that will allow you to fix production issues, you’ll need more detailed data.
IC testing provides specific data about contaminants affecting product performance, including the specific ionic species and their concentrations. While your results with IC testing won’t be quite as immediate as ROSE testing, you won’t have to wait long. You can get results within two business days with Innovatech’s expedited service.
Chromatogram of Contaminated Circuit Boards
This chromatogram from a contaminated circuit board provides qualitative and quantitative information about the contaminant’s composition and source. Results show elevated levels of both ionic species and weak organic acids compared to baseline. This data provides the manufacturer with clues to identify possible process improvements.
Are Contaminants Affecting Your Product’s Performance?
IC testing is an extremely versatile tool to help identify the presence and concentration of contaminants. Numerous industries use IC testing for quality control and to ensure product performance. Its vast applications include:
- Validating the cleaning process in critical environment manufacturing settings
- Identifying residuals that could impact the safety of medical devices
- Testing for environmental additives
There’s no single test that’s perfect for all testing situations. But, if ion chromatography isn’t a good choice for your project, we’ll help identify materials analysis techniques to quickly and accurately provide the information you need.
Contact us to get started.