SMT007 Magazine


Issue link:

Contents of this Issue


Page 15 of 123

16 SMT Magazine • July 2016 equipment manufacturers (OEMs). These appli- cations used rosin-based wave soldering fluxes, such as RMAs, and cleaned with now presently banned fluorocarbon solvents. Many of these applications have subsequently implemented water soluble soldering processes. Several au- tomotive and consumer electronic OEMs still use this standard, to qualifying assemblies built with no-clean materials using mixed SMT and PTH assembly technologies. IPC-TM-650 Method 2.3.25 contains stan- dard test methods for extracting contaminants from circuit boards using heated isopropanol (IPA) / water mixtures. Test method 2.3.25 is commonly referred to as the ROSE (resistivity of solvent extract) test. Previous work 1,2 has shown poor correlation between the presence of extractable, corrosive weak organic acids and results from IPC-TM-650 2.3.25 test results, par- tially due to the lack of solubility of materials found in no-clean fluxes, and the higher SIR values imparted by rosins and resins in modern no-clean soldering materials. This study will compare the results from testing two solder pastes using the IPC-J-STD- by K. Tellefsen, et al.* ALPHA ASSEMBLY SOLUTIONS Controlled humidity and temperature con- trolled surface insulation resistance (SIR) mea- surements of flux covered test vehicles, subject to a direct current (DC) bias voltage, are recog- nized by a number of global standards organi- zations as the preferred method to determine if no-clean solder paste and wave soldering flux residues are suitable for reliable electronic as- semblies. The Association Connecting Electron- ics Industries (IPC), Japanese Industry Standard (JIS), Deutsches Institut fur Normung (DIN) and International Electrical Commission (IEC) all have industry reviewed standards using similar variations of this measurement. Ionic contamination testing is recognized by the IPC as a standard for evaluating the clean- liness of assemblies that have been subjected to a cleaning process. IPC J-STD001F calls for a cleanliness level of <1.56 µg/cm² NaCl equiva- lent after the cleaning processes. Historically, this threshold originated from the cleanliness specifications of military and aerospace original FEATU RE

Articles in this issue

Archives of this issue

view archives of SMT007 Magazine - SMT-July2016