Dragon, Was recently responsible for No Clean Process/Material evaluation and implementation project. Shop was 100% Water soluble facility. Several Top Paste manufacturers were invited to participate. (3) were evaluated. All key variables were identified and measured in DOE. AIM NC 253 came out the winner. We had success with 14 mil. FP, 0603 resnets, .8 mm, 1200 I/O devices, CBGA, PBGA, column grid arrays, and micro's. Limited residues remaining, and less voiding characteristics. One key determination was the printing characteristics of the AIM. Having inline Cyber Sentries aided in measuring print conformance. Measuring relax and recovery times, clogging apertures, stencil life, etc. A 2% increase in yields was noted in ICT/FCT Test on the products/assemblies transferred to No Clean Process. Additional to the normal inspection/test gates we utilized a BGA Caltex Scope, and 3D X-ray (Tomosynthesis) to validate solder joint integrity, voiding, etc. Some of the bigger challenges occurred in Post and Touch up areas, and SRT BGA repair process. What kind of board finish is typical in your shop? If you'd like to know more of the specifics of eval., DOE outline, variables, and paste manufacturers give me a shout. Scott
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