Do You know the Basic Information of PCB Ionic Contamination Test?

Do You know the Basic Information of PCB Ionic Contamination Test?

A PCB ionic contamination test detects ionic residues that remain from the manufacturing and soldering process and is often a requirement to ensure ionic cleanliness prior to applying the conformal coating to printed circuit boards.

Do you know the basic information of PCB ionic contamination test? In this passage, please check and read the passage below for more professional knowledge.

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How to ionic contamination testing before conformal coating services?

We offer ionic contamination testing prior to our in-house conformal coating processes, but the ionic testing services are also available to customers who wish to test the quality of the products they’re receiving from contract manufacturers. We can usually deliver same-day or 1-day turns for ionic contaminant testing. This is a quick, inexpensive way for our customers to determine the level of cleanliness they’ve received before continuing their production processes.

Plasma Ruggedized Solutions’ ionic contamination testing and cleaning services can detect and remove any number of common contaminants created in the manufacture of PCBs and other components. These include:

·  Chloride

·  Fluoride

·  Potassium

·  Sodium

·  and many others

What are the common issues of PCB Ionic contamination testing?

A PCB can also have nonionic contamination, which involves nonionic residues. Nonionic residues don’t have conductive properties, so they can usually remain on the PCB after production and assembly. Therefore, most manufacturers focus on ionic contamination when examining a board’s cleanliness. The ionic residues that affect PCB components during production include:

·  Salts

·  Inorganic and organic acids

·  Ethanolamines

·  Perspiration

·  Flux activators

·  Plating chemistries

·  Ionic contamination has two common sources:

Lack of bare board cleanliness: Many ionic contaminants come from the board itself. The board fabrication process, as well as environmental exposure, can leave residues such as particulate residues, oils, salts and dust. Before adding components to a bare board, manufacturers must ensure no contaminants were left over from previous steps in the production process.

Use of aggressive chemistry: Copper etching liquid, water-soluble soldering chemistry and other kinds of aggressive chemistry can leave behind residues that change the board’s conductivity when not cleaned properly.

What are effects of ionic contamination in a PCB?

The occurrence of ionic contamination on PCB assembly can inhibit its performance. In the production house, bare boards can carry ionic contaminants in the form of left-over flux, etching chemical, and solder material. If these residues are left on the board, major issues, like Electrochemical Migration (ECM), corroded traces, parasitic leakages, and dendritic growth, can hamper the PCB’s life-cycle. Read 8 soldering tips to avoid possible ionic contamination issues.

Electrochemical migration (ECM): Electrochemical migration is caused by the electric field in which metal gets dissolved, resulting in ion formation between two copper features. If the electric field is applied, the metal dissolves at the Anode and gets deposited to the Cathode resulting in dendrite growth. Because dendrites grow from conductive ions, they can direct PCB currents differently from what is intended, leading to short circuits. Dendrites create alternative current paths that can affect the accuracy of current measurements in a PCB.

Corrosion: Usually, PCBs corrode due to their material. Ionic contamination can corrode the entire PCB in a much shorter time. When ionic residue comes in contact with moisture, the short-circuit risk increases. The corroding metal flakes off, overlooking the chemical properties needed for the PCB to operate correctly. Selecting apt PCB material and laminates help with ionic contamination issues.

Ionic contamination alone is not responsible for the above consequences; moisture and environmental exposure are also. That is why PCBs are baked to eliminate moisture before starting any new process. The ionic contamination level needs to be controlled during the manufacturing of circuit boards by adopting a process control tool. This tool ensures that the individual production process steps (e.g., surface-mount or through-hole) are performed in a controlled manner to achieve a manageable ionic contamination level.

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