ISSN:
0954-0911
Source:
Emerald Fulltext Archive Database 1994-2005
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
The reliability and corrosivity of two VOC - free, no-cleanfluxes (C and D) were assessed using traditional test method such as copper mirror and copper corrosiontests. Modified surface insulation resistance (SIR) tests using coupons fluxed with various methods wereperformed in 50°C/90%RH environmental conditions. Printed circuit boards and assemblies were fluxedand exposed to a 50°C/90%RH chamber to assess long-term reliability. To evaluate the corrosion ratesof copper and solder sheets in as- received liquid fluxes, electrochemical polarisation measurements wereemployed. These showed that the corrosion rate of copper in flux D is 100 times higher than that in fluxC. These quantitative data agreed with the qualitative copper mirror test results, i,e, flux C passed andflux D failed the test. However, both flux residues were found to corrode copper traces underneath thesolder mask and copper pads on the PCB after three weeks in a 50°C/90% RH environment chamber. Large amounts of blue/green corrosion products were observed on the bare copper SIR coupons within seven days when using either flux; and SIR values were below the required 108 ohms. Based on the test results, neither flux was qualified for no-clean processes because of the issues withcorrosion. The corrosiveness of the VOC- free, no- clean flux residue is believed to be due to theactivator packages used.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1108/09540919610777555
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