Why do I need to provide OE?

Is your end-product required or expected to be reliable?
Will anyone get hurt if your product fails?
Will your insurance policy cover you in the event of a product failure?
Do you operate under ISO 9001 or other formal accreditation?

If you answer Yes to any of these, then you need to Qualify your manufacturing process.

So what does that mean?

OE is needed to validate the quality of a product, and this can only be achieved by the production of data that characterises the product, and these data are the basis of objective evidence. Experimental data from a recognised test method provides the confirmation that the materials and process used in the manufacture meet the requirements of a standard, or contract. By using a standard test method and meeting the requirements of J Std 001, there is a globally recognised framework by which OE can be produced.

What is the need for it?

The need for producing OE is to establish a qualification of a manufacturing process. This approach encompasses different types of assembly, which may entail different cleaning requirements. Testing therefore needs to produce objective evidence that indicates whether any of the chemical species remaining on the assembly will affect its electronic reliability where it is subject to problematic temperature and humidity conditions. A manufacturing process cannot be qualified through chemical analysis alone, and must be determined by testing using temperature/humidity/voltage-bias techniques. By applying a bias you discover the propensity of ionic residues to be mobilised and their potential to cause ECM. This is SIR.

Testing for the ionic residues

As mentioned above SIR testing can be used to discover the effect of residues in supporting ECM that leads to failure. An alternative approach using Ion chromatography (IC) is also referenced in J Std 001. IC is a chemical test, and identifies soluble chemical species from the circuit assembly. This chemical information from IC can be related to the product functionality through the use of previous studies and library values. There is no pass/fail criteria for IC data in J Std 001. However, IC can be related to electromigration of ionic species that cause harmful effects, and it can be used as a route to creating objective evidence to qualify a process. But this is only possible where previous characterisation work by SIR or field data have developed the ideal library values for the specific product. In summary OE data are principally generated using SIR testing, but can be in combination with ion chromatography testing or other functional testing as agreed between user and supplier.

Ionic Testing
The Purpose
The Purpose

The purpose of objective evidence is to demonstrate that residual chemical species do not adversely affect the reliability of the assembly. Producing OE characterises the materials and processes used in the  manufacture of a product. Any substantial change in the process will require re-qualification. Typical major changes could include flux, solder, cleaning agent, solder mask type, solderable finish, change of PCB supplier, etc. The need for OE also be required to qualify process changes. These changes can include for example a modification of the reflow profile, cleaning parameters, and material changes.

Your auditor will investigate your manufacturing process.

The data that is produced by the OE process will be defined in these terms:

Process Verification and Qualification are particularly important because these statements describe your compliance with the OE targets.