Process Terms

When discussing a process and its performance the terminology used refers to key words that have distinct and important meanings and are defined in ISO 9001. Use of such specific terms provide a framework on discussing and comparing processes. The terms are: Characterisation, Validation, Verification, and Qualification. These definitions are given here as they apply to building electronic assemblies.

Characterisation

Characterisation is the application of a test where the data is not assessed against a standard, but the results are analysed on the principle of a comparison, or against some arbitrary metric. The test method may or not be covered by a standard.

Characterisation
Validation
Validation

Validation of objective evidence testing is an assessment that the specification captures the requirements. That data meeting the specification are evidence that the product is reliable.

Verification

Confirmation, through the provision of objective evidence, that specified requirements have been fulfilled.

Verification
Qualification
Qualification

Qualification is an act or process to assure something complies with some condition, standard, or specific requirements. For example in the SIR test if the resistance is above the 10⁸Ω then the test has qualified the result to IPC-J-STD-001.

Summary

A characterisation study using SIR will use a reproducible method that maybe from a standard, the results are typically compared with other tests, or to library values. Validation is where which test to be used is decided, for example this could be IEC 61189-5-502 or IPC-TM-650 Method 2.6.3.7, or IPC 9202. In the validation the test methods will be reviewed according to the parameters and compared to the requirements. Using an agreed test schedule and comparing those results to a specification is a verification. The SIR test can be used to verify that the material set meet the requirements for objective evidence, for example the procedure in J Std 001 has been meet. A verification study may also meet the requirements where the resistance values are better than 10⁸Ω, and this would be a qualification.
 

SIR can be used to qualify the materials and processes used in a product. In fact a SIR test is an essential part of any qualification. But a SIR test cannot qualify a product, and this is because SIR patterns cannot be incorporated into a product, and SIR cannot be used on a product as manufactured. SIR Process Qualification will involve testing dummy components on a representative example of the intended end-product. The IPC B52 test vehicle employ’s dummy components that represent “worst case” for process residue entrapment and thereby better determine whether the chosen material set is electrochemically compatible. Following a successful SIR qualification on a IPC B52, a final IC analysis may be performed on the product as a final check. This will provide confidence that the product itself does not exhibit undesirable anomalies that may lead to ECM. Finally for the purposes of Process Control the PICT test is performed on these first products to form a reference value for this product, for which any future manufactured product of this design can be compared.