Interpretation of Shanghai Electronic Products PCB circuit board pollution complaints v. Survey results

As described in the article, we divide the direction of tracing this issue into two parts. The first route is to send SEMs / EDS and FTIR analysis to labs that send contaminants on non-performing products to third-party fair institutions , But the result of SEM / EDS can only tell us that it is organic matter, and the elements that are produced are C (carbon) and O (oxygen); therefore, FTIR needs to be further performed but the result of FTIR Only in the database than the existing graphics, if the database is not stored in the material than not, so you need to get the actual material in doubt to do FTIR comparison, but also to confirm the pollutants.

The second route is to check all possible sources of contamination of the factory, ranging from PCB loading, inspection, SMT racks on PCBs, SMT entire lines (especially reflow furnaces), hand soldering parts, ICT circuit testing , FVT function tests, repairs, assembly lines, and even the possibility that the electrostatic guns will not spit out the oil, and then carefully examine each possible source, the entire plant is almost doubled over.

It is also due to coincidence that preliminary laboratory tests showed that the contaminants contained IPA or glycol ether detergent components but none of the other components were detectable. Shanghai's electronic product processing was somewhat in line with the use of solvents and detergents at the factory Different, so I found all the relevant personnel to discuss the possible reasons, and suddenly someone said there will be operators mistakenly use solder flux (flux) to use as a cleaner? This is quite possible, so the factory all the flux and detergent sent to do FTIR analysis of the ingredients, and asked the factory quality control engineer secretly observed record of each production line operators how to wipe the PCB circuit board buttons gold fingers, And the emulation uses flux to act as an IPA cleaner to clean the PCB.

The result of FTIR is very encouraging. Another group of contaminants that could not be detected was a flux, but the laboratory concluded that the contaminants should be a mixture of cleaner and flux reconciled in a certain ratio. This also shows why the operator can not at the time judge liquid wipe PCB circuit board is not a cleaning agent but live flux, or flux with a yellowish color, and gas and IPA cleaner, a little production line experienced operators Should be able to easily determine the difference between the two.