Issue link: https://iconnect007.uberflip.com/i/1379105
26 SMT007 MAGAZINE I JUNE 2021 As explained in the new IPC WP019B, the requirement is to use SIR. is technique mea- sures changes to insulation resistance by exam- ining a representative example of the intended end-product from an electro-chemical stand- point. • It determines whether the product will be electro-chemically reliable • It is not able to determine what is presently causing a problem If a problem is encountered, then other ana- lytical methods are required such as ion chro- matography and FTIR. ese methods mea- sure the amount of ionic residues on the test sample. • It is not able to predict if the end-product will be electro-chemically reliable • Nor is either of them able to detect non-ionic material that is most commonly present in modern process materials As can be seen, there is no one-size-fits-all answer. Regarding inspection, techniques such as 3D inspection microscopy and scanning electron microscopy are proving to be valuable inspec- tion tools. However, care must be taken when conducting these levels of inspection as it is all too common to scare yourself at what you can now see for the first time. New component technology, oen incorpo- rating bottom terminations (BTCs), are offer- ing a challenge to those who clean, given that the component stand-off is so tight. It is not only the issue of ensuring penetration of the cleaning media to the underneath of the com- ponent, but the escape of the resulting "por- ridge." SIR is the most effective tool to measure the actual performance of the desired clean- ing process, and is why GEN3 is collaborating with Zestron to help the industry move into this new territory. New international standards have already been published to help industry address the issue: Figure 1: Types of objective evidence.