What is contamination testing and why it is important?

What is contamination testing and why it is important

Why is PCB cleanliness important?

Circuit boards can suffer from a variety of problems if the surface is contaminated with electrically conducting materials. Combined with moisture, this results in a lowering of resistance between tracks and pads and can lead to corrosion of metals. Since the elimination of solvent-cleaned rosin assembly practices,the electronics industry has turned to alternative manufacturing processes such as aqueous cleaning,water-soluble and no clean processes over the past 15 years. The use of these alternate processes has resulted in a growing number of field failures due to electro-migration or corrosion issues. This poorer field performance has been directly tied to the changes in process residues (types, levels and reactive states). Our understanding of these changes has come from investigation of the failures, process improvements, process qualifications, validations and monitoring of these alternative manufacturing methods through ionic testing equipment.

How clean is clean?

The ionic contamination level is calculated from the ionic conductivity of the wash solution and the total board area. The result is an average value across the whole surface. The development of standards of cleanliness and standard test methods date back to the early 1970’s in the US, culminating in the publication of the original American MIL standards.It was from this work that the original pass/fail criteria of 10μg NaCl equivalence /inch or 1.56μ gNaCl /cm2 were first proposed. Cleanliness testing is now a routine procedure and manufacturers of both bare and populated boards are commonly asked to ensure their products meet contamination specifications based on this limit.

Dynamic vs.Static

Since the birth of ionic contamination testing ,there are has been some confusion over the so called dynamic or static testing methods. Both sides claim they could deliver more benefits than the other. To overcome these issues,the C8 contamination tester gives you the flexibility to adopt the best method,as both of them are cited by IPC standard.This is especially important for OEM manufacturers,their various customers may require different methods of analysis and this saves the purchasing of the two types of equipment

Related Suggestion