On 7 Sep 1995, Smith, Joshua wrote: > > We have observed corrosion caused by ionic impurities in adhesives we are > using for an application. We have looked at total content (burn off) and > extractable ionics (90 deg C, 40 hrs). > 1)What standards/ procedures are accepted for measuring Ionic impurities : > On or in flex circuits? > on/in PCBs? > in adhesives for PCBs? > In adhesives for chip attach? > > 2)What are acceptable levels of contamination in each of these applications? > > 3)We have been told that 200 ppm is acceptable for PCB applications while IC > people require 20ppm. Is this true? > > 4) What are the primary ions that cause trouble. Cl, Br, F others? > > Josh Smith > Information, Imaging and Electronics Sector Research Laboratory > 3M co > 612-736-1101 > > > > Josh, Most companies go by MIL SPEC 883D Method 5011.2 "Evaluation and Procedures For Polymeric Adhesives." The maximum level of contamination for Na+, K+, and F- are 50 ppm. The level for Cl- is much higher at 300 ppm. However, most companies prefer levels below 20 ppm for all four ions. Tom Cinque Alphametals (201) 434-6778 x2259 [log in to unmask]