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Preliminary measurements of soldering flux residues in AC environment.

Brewin, A; Zou, L; Dusek, M; Hunt, C (2005) Preliminary measurements of soldering flux residues in AC environment. NPL Report. DEPC-MPR 029

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Surface insulation resistance (SIR) techniques are currently used to measure the effects on long-term reliability of electronic assemblies of residues emanating from electronic production processes. This is achieved by monitoring leakage currents under a DC voltage in high temperature and humidity conditions.
This approach has been adopted from the simple expedient that tests run under DC conditions are simpler to implement than those under AC conditions. Historically, however, there has also been a concern that under AC conditions electro-chemical corrosion failures such as dendrite growth will not occur.
This exploratory work has studied the effects of flux residues on the impedance of interdigitated combs under the application of AC voltage. These effects are considered to be more relevant to digital and AC circuit designs currently in use in many applications. The effects of the presence of generic flux types (rosin, water-based, and glutaric acid) on SIR style interdigitated combs have been measured and compared, using the parameters of impedance (real and imaginary) and capacitance.
The study indicates that the use of impedance properties as a tool for differentiating the effects of flux and their potential effect on AC circuits is promising, and warrants further study. Suggestions for further work are included.

Item Type: Report/Guide (NPL Report)
NPL Report No.: DEPC-MPR 029
Keywords: impedance, PCB contamination
Subjects: Advanced Materials
Advanced Materials > Electronics Interconnection
Last Modified: 02 Feb 2018 13:16
URI: http://eprintspublications.npl.co.uk/id/eprint/3277

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