Resistivity Of Solvent Extract (R.O.S.E.) Test

The R.O.S.E. Test, which stands for Resistivity Of Solvent Extract, is a widely used method in the electronics manufacturing industry to assess the ionic cleanliness of printed circuit boards (PCBs) and assemblies.

The test detects soluble ionic contaminants—such as sodium, chloride, bromide, and fluoride—that can remain on a PCB after manufacturing processes like soldering or etching. These ions can lead to corrosion, dendritic growth, and ultimately electrical failures if not properly removed. 

How It Works

  1. A test solution of  75% isopropyl alcohol (IPA)and 25% water is used to extract ionic residues from the surface of the PCB.
  2. The initial resistivityof the clean solvent is measured.
  3. The PCB is immersed in the solvent, which dissolves the ionic contaminants.
  4. The final resistivityof the solvent is measured.
  5. The difference in resistivity indicates the amount of ionic contamination, usually reported in micrograms of sodium chloride equivalent per square centimeter(µg NaCl/cm²) 
  6. For military testing purposes the PASS/FAIL limit is 37.0 µg/in2 (5.7 µg/cm2).
  7. The Bellcore telecommunications specification requires a PASS/FAIL level of 3.70 µg/cm2 (23.9 µg/in2).

 

Applications

  • Quality controlin PCB manufacturing
  • Process validationfor cleaning steps
  • Reliability assurancein high-stakes industries like aerospace, military, and medical devices

Limitations

  • The R.O.S.E. test only detects ions and is not a measure of other contaminants such as dirt, dust, oils or surfactants that have no ionic reactivity.

R.O.S.E. testing is the recognized industry standard for measuring and tracking ionic cleanliness in circuit boards and assemblies in order to prevent performance issues, especially within sensitive industries such as the military and medical fields.