observed (Figure 5). This effect highlights the importance of active solvent concentration for effective cleaning.
Organic flux residues deposited onto the surface of flip chip assemblies during reflow soldering operations have been shown, in some cases, to affect the properties of underfill. Formation of metal salts is due to the active ingredients in the flux chemistry. White residues that form as a result of solder/flux interactions are difficult to completely remove. Increased active solvent concentration in cleaning fluids can greatly improve cleaning performance.
The active solvent concentration is an essential driver for cleaning. A proprietary fluorinated material has been identified that azeotropes with the active solvent at higher level. Visual inspection of test boards revealed that increased level of active solvent, solubility of the residue improves.
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MIKE BIXENMAN, chief technology officer, and KYLE DOYEL, president, may be contacted at Kyzen Corp., 430 Harding Industrial Dr., Nashville, TN 37211; 615/831-0800; e-mail: firstname.lastname@example.org and email@example.com.