Test Engineer - Early Project Involvement From Design Phase

Early Project Involvement From Design Phase

Ideally, a test engineer's involvement with a product begins with the very early stages of the design phase. Depending on the culture of the firm, the early stages could refer to Product Requirements Document (PRD) and Marketing Requirements Document (MRD)—some of the earliest work done during a new product introduction (NPI).

By working with or as part of the NPI group, a test engineer ensures that a product is designed for both testability and manufacturability. In other words, to make sure that the product can be readily tested and built.

The following are some general rules to ensure testability and manufacturability of a product:

• Making sure the product has correct label specs and placement that would make it possible for the unit to be traceable and programmable. Implementing good label specs results in having correct information programmed correctly into the unit under test (UUT) (sometimes called DUT or device under test). To make this possible, the test engineers enforce those labels location and are all readable and scannable, thus eliminating the need for a manual typing of information into the unit. Automatic placing of identification codes into the part during test and making them available for verification at later processing steps can help minimize these types of errors. Manual typing can introduce problems related to inaccurate information being programmed due to human errors. Also, without the test engineers input during PRD design phase, the hardware engineer in charge of designing of the silk-screen for the PCB may put those labels below some attachable board which will then later renders the labels useless (i.e. in a motherboard/daughterboard design and also a board that has a pluggable module, a label would be visible on the main board by itself but would be obstructed by the other boards that needs to be integrated). This information are often indicated in both PRD and MRD.
• Making sure that all components required to test and debug the UUT, which includes the console/serial port, are all accessible from the early part of the manufacturing process up to the last part which is often the final quality audit/assurance (FQA) process. This also includes making sure those components are available even after the units are returned by the customers for troubleshooting or repair. By following this guidelines, the team will eliminate unnecessary opening of the UUT just to access those components which may result in introducing errors into the unit (i.e. knocking off some capacitors or resistors when opening/sliding out the cover, dropping the tool inside the PCBA after opening, forgetting some other cables to reconnect before closing the unit for manufacturing process flow continuation, etc.).
• Making sure that all components needed to test the unit are added into the cost matrix of the final product. This components may include the UART/RS232 chips for talking to the UUT, ethernet ports for upgrading the firmware, JTAG connectors, etc.
• Defining what manufacturing test process is needed based from the product definition.
• Verifying that the currently available test equipment is adequate for testing the proposed design. If new equipment is needed, budgetary concerns have been addressed and sufficient lead time exists for new equipment installation and verification. Also, new test equipment may require training for test equipment operators and supervisors.

By following the general rules above, test engineers minimize future surprises (like adding extra components, re-layout of the boards, etc.) which drives up costs and development delays of the final product.