Fab Insights: EVT in PCBA Product Development

The engineering validation test (EVT) stage determines whether your PCBA design meets your customer’s functional product requirements. This validation testing occurs after your project’s concept phase and after a product requirements document (PRD) has been completed.

EVT is the first of three key validation stages. There are two additional testing phases before the project gets released to manufacturing, gated by successful EVT completion:

Design Validation Testing (DVT) – This stage tests whether the full characterization of the product meets specifications across all manufacturing variances.

Production Validation Testing (PVT) – This stage works through the challenges of preparing for and transferring the project to manufacturing.

This is the first in our series on PCBA development stages. Look for our articles on DVT and PVT for a fuller design cycle picture. Now, let’s review what happens during the EVT stage, its importance, what challenges exist, and how to overcome them.

The EVT stage implements the design in its fit, form, and function. This proves your electronics product can function as intended. The first batch of prototypes is assembled and tested for basic functionality. The typical prototype quantities can range from a few to fifty.

This project phase may require design iterations if the functional operation does not meet specifications due to design shortcomings. In the case of required changes, the design must get updated for a new batch of prototypes. This can lead to an EVT2 stage.

If the EVT stage is successful, it is often used to better inform stakeholders of your production intent. This is often considered the most important milestone in the project as the customer acceptance process can only begin once they have the first project articles.

The first prototype build demonstrates the ability to manufacture the first production batch. This first assembly preparation pinpoints weak points within the process. Preparation will pay off at this stage if the proper steps are in place to mitigate risks.

During EVT, the bill of materials (BOM) gets procured for the first time. Assembly also happens for the first time. The PCBA is finally manufactured. All these processes have the potential for unexpected issues. Here are some potential areas of risk if the proper preparation is not considered:

• One or more components within the BOM may not be available for procurement.
• Although a component is available, the BOM package type may not match the footprint on the layout.
• A PCBA layout connection issue may prevent proper electrical operation.
• The solder screen for the PCBA assembly may have pad openings that are too large, too small, or may have erroneous features.
• The final yield outcome turns out unacceptably low
• Special custom surface-mount technology (SMT) instructions may not be completely communicated to the assembly floor for execution.

Mitigate challenges by making decisions early and working with a contract manufacturer (CM) such as MacroFab during project development. MacroFab works with a network of manufacturing partners that specialize in both small prototype build and large-scale manufacturing. The quoting process prepares for long-term success by identifying all project needs during the EVT stage. MacroFab’s digital platform addresses risks that are inherent in the EVT processes and beyond.

The challenges to completing the project don’t end with the EVT. Once the EVT stage meets requirements through additional design iterations, the project moves to the DVT stage. The DVT stage proves the design can hold up across variances. This is also the point where the performance is examined to understand where operational boundaries exist for the product.

By working with MacroFab as your CM partner, you can also tackle the next set of activities during DVT. You can learn more about DVT in the next article titled “Fab Insights: DVT in PCBA Product Development.”