This paragraph is intended to emphasize that each type of requirement contained in the standard which is applicable to LOxx flux, also applies to ORxx flux.
Such documentation shall be approved by the procuring NASA Center prior to use (Requirement). When the supplier intends to use processes, materials, or parts not covered by this publication, the supplier shall document the details of fabrication and inspection, including acceptance and rejection criteria, and shall provide appropriate test data (Requirement). 3 require the following for approving use of non-standard flux:Ĥ.1.3 Nonstandard Processes, Materials, or Parts.
Precleaning bare printed circuit boards is also recommended to further reduce sources of stray halide contamination. Ion Chromatography is the recommended method for this quality monitor (see IPC J-STD-001 for the test method). It is important to baseline and monitor the cleaning process’ effectiveness for removing weak organic acids as well as for removing halides. However, unactivated and remnant weak organic acids, and the water that it readily retains, will also contribute to leakage paths, salt deposits, and corrosion, if stray halides (introduced during handling, rework, packaging) come in contact with the cleaned assembly. Remnant halides are an important player in the development of unwanted leakage paths and corrosion on finished printed wiring assemblies. 3 for LOxx fluxes) will not detect the presence of weak organic acids however they will detect remnant halides. Cleanliness methods which use conductivity measurements of cleaning fluid (such as those defined in NASA-STD-8739.2 and.
Several ORxx fluxes examined to date have very low, to imperceptible, amounts of remnant weak organic acids and halides after normal printed wiring assembly cleaning. Water soluble flux is effective via a combination of weak organic acids and halides. In all cases voiding should be baselined for the process to be used and controlled through statistical process control methods or 100% end-of-line inspection (X-ray screening).ī. successful performance over mission application conditions and lifetime). Where voiding is normally above 10%, vibration and thermal cycling life testing should be performed to establish that the typical voiding amount will result in sufficiently reliable joints (i.e. Voiding in excess of 10% of the joint area (as viewed by X-ray) should be avoided via process control and monitoring with X-ray. Some suppliers’ use of ORxx flux has resulted in consistent voiding in the solder joints. Note: Qualification tests used by a supplier for establishing a flux’s successful use in a manufacturing line may not be equivalent to the qualification tests NASA seeks which demonstrate successful performance over mission application conditions and lifetime.Įxamination of suppliers’ assemblies built with ORxx flux has found two defects which must be addressed for this material:Ī. ORxx flux may be present in liquid form, in solder paste, or in cored wire solder. Suppliers wishing to use ORxx flux (reference IPC J-STD-004) in NASA mission hardware must meet the requirements for non-standard flux as defined in the NASA Workmanship Standards NASA-STD-8739.2 or NASA-STD-8739.3. Though some suppliers may have long-standing experience with these fluxes and have “qualified” them for their own use, these materials continue to be considered non-standard for use in NASA mission hardware. This trend is nearly twenty years old and is beginning to affect hardware supplied to NASA for its missions. Links To Required Workmanship Standards |Ī move toward eco-friendly industrial systems worldwide has resulted in an increased use of water soluble and no-clean fluxes in the commercial sector.
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