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No Clean

Eliud Rivera


No Clean | 12 June, 2001

We are trying to quilify a No-Cclean solder paste and we would like to know what kind of criterias or measurments are use to qualify the amount residues? Can we use an omega meter for that? What equipment measures SIR?

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No Clean | 12 June, 2001

The criterion you use will depend on the test method you select. For minimum requirements, look at J-STD-001C, Para 8, "Cleanliness Requirements". I figure that you�d measure the residues on a lot of your current product, measure the res on a lot of your product using NC, and be happy if the res from your NC is lower than your older flux.

Ionic residues are detectable by:

* Resistivity of Solvent Extract (ROSE) testing (Omega meter, Ionograph, etc.). [Eurolanders call this Solvent Extract Conductivity (SEC).] Using your Omega meter is identical to washing your boards in a IPA / DI water solution. That�s a sure fire way to turn your solder connections to a milky white color. Anyone desiring to use an ionic contamination tester should read EMPF [] report RR000013, "An In-Depth Look at Ionic Cleanliness Testing.

* Ion chromotagraphy. This test measures specific ionic residues that can cause failure. It does nothing to check for non-ionic residues that can cause problems. Generally, only large shops can maintain the equipment. IPC [] lists reputable test labs. Dionex [] is the premier supplier. And if you have to ask the cost, you cannot afford it.

* Surface Insulation Resistance. This test actually has a correlation with field failures. [No failures relating to residue, if resistivity is above a certain level. Guaranteed failures, if its below a certain level.] The level depends upon environment, panel design and circuit design [voltage, current, impedance, spacing, indoors vs. under the hood...]. This test should be done on test coupons in an environmental test lab. IPC [] lists reputable test labs. It is rarely done as a process control, since the test takes a week, and is not usually done on production panels. - Concoat [] makes a very good machine. [I believe that Multicore distributes it in the US. Elsewhere, dunno.] - Alpha Metals makes a SIRometer. - ASR Instruments is another reputable supplier.

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