Since the 1970s, ROSE testing was used to determine "clean enough." In 2015, the J-STD-001 committee assigned a team to develop the next generation of "cleanliness" requirements. Section 8 defines the key concepts that drove the need for developing new cleanliness requirements.
A qualified manufacturing process requires assemblers to qualify soldering and cleaning processes that result in acceptable levels of flux and other residues. This paper reported research on both test boards and instrumentation for use at the assembly site. The instrument and test board combinations are tools that process engineers and line personnel can use to develop objective evidence as it relates to the cleanliness of production hardware.
The purpose of this experiment was to assess the SIR resistance of storage conditions and compare levels of contamination on boards between two types of desiccants: Silica Beads and Super Absorbing Polymers. Two sets of desiccant conditions were stored in sealed containers at room temperature in a high-humidity area (75% RH, as in a room with an inline cleaner), and resistance measurements were taken daily on PCB electrodes within the sealed enclosure. Both desiccant types showed no visible dendrites at 5 volts after 90 days. The cleanliness assessment revealed significant differences in contamination levels on the boards between the two types of desiccants. Test methods, equipment, and results of the cleanliness assessment are in the attached report.
The basic premise of the test has to do with
- Are there residues that affect electrical performance?
- Are there residues that will cause corrosion?
