How to convert between ppmw and ppmma?
Thread Content
I would like to ask how to convert between ppmw and ppmma?
ppmw is the concentration based on mass, where w stands for weight. PPMA is the concentration based on the number of atoms, with a referring to atoms. To convert the atomic density of trace impurities in high-purity silicon into a mass concentration (ppmw), the following formula can be used: Atomic density of impurity × atomic weight of the impurity element / (5e22×28) = Mass concentration of the impurity (ppmw). Here, 5e22 represents the number of silicon atoms per cubic centimeter of silicon, and 28 is the atomic weight of silicon