How to Troubleshoot Your Testing Processes

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There are a multitude of electronic circuit assembly manufacturers, high-volume/low-product mix to low-volume/high-product mix. Only you will know where you are in that definition.

Either way, the removal of the discredited ROSE test using an accept/reject criteria of 1.56 µg/cm2 is causing mayhem in the industry. Today, the non-negotiable requirement is to produce objective evidence.

Once the production process (material set) has been characterised, the user needs to have a fast, reliable, and repeatable test that will identify any ionically detectable changes in the final assembled product. Note: Such tested assemblies need to be assessed as suitable for shipment.

The new Process Ionic Contamination Test (PICT) [1] does precisely that.

  • Fast: Less than 15 minutes
  • Sensitive: At the same level as ion chromatography, but without the spectrum
  • Repeatable: Proven acceptability to Six Sigma levels

The SIR “process characterisation of a material set” is best defined in a new Test Method: IEC 61189-5-502 published earlier in 2021.

Where Can SIR Be Used?
SIR can be used for process validation, process verification, and process or material characterisation.

SIR testing is usually done by process material manufacturers to qualify their material to meet certain standards requirements such as solder flux, coatings, resists, and more, in isolation to all other materials.

In the case of a process “material set” characterisation, we are using a representative example of the intended end-product, fully assembled. The examination is to determine electrochemical compatibility between solder mask/resist, solder flux, paste or wire, underfills, adhesives, staking compounds cleaning processes, conformal coatings, etc.

To read this entire article, which appeared in the July 2021 issue of SMT007 Magazine, click here.


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