The answer is really a 2 part solution to this request. First, Lead frames need to be free from all surface organics – organic compounds and or residues - this can be reviewed with a scanning electron microscope and or high powered scope.
The object is to validate there is no residues present on the surface. Some companies use a SEM / EDX to quantify the carbon and oxygen present and if it is high then a Fourier Transform Infrared Spectrometer (FTIR)is used to determine the organic spectrum present to determine the type of organic present.
This is a good analytical tool to use to verify surface contamination. The second part is also using a SEM / EDX to determine the quality of the gold that is plated and this is used to determine the organic levels plated into the gold .
All gold baths have organic chemistries and brighteners in its gold solution. This test is used to verify the bath is kept in balance and there are not elevated levels of organics plated in to the gold plating.
The next answer addresses the need to plasma etch the lead frames before wirebonding to insure that all organics are gone and that the gold plated surface is prepped for wirebonding. Plasma etching is a great process step (CLEANING) before wirebonding to insure the lead frames are cleaned properly before wirebonding. Plasma removes the organics and oxides present on the surface and preps the gold surface.
We can also provide plasma etch advise if this is of interest.
