Any genuine PCB manufacturer should conduct a DFM inspection before putting the circuit board into production to find potential quality problems. DFM inspection is very important to ensure high yield, but there are other points of attention in the inspection and testing process, including:

01. Electrical Test

This includes needle bed and needle flying test. Both are non-invasive tests and can be used to check for open circuits and short circuits on critical networks during the manufacturing process.

02. Manual or Automatic Optical Inspection

The circuit board should be checked automatically or manually after manufacturing. Some of the defects that can be identified through automatic inspection include trace size and spacing violations, missing or short-circuited pads, and incomplete or damaged drill holes.

03. BGA Inspection

Use X-ray imaging system to inspect BGA devices.

04. TDR Test

This test is used to measure the characteristics or differential impedance of the transmission line in the impedance control wiring. This can be done by placing the transmission line on a panel or board-side sample, and then comparing the expected impedance with the reference impedance.

05. Special Standard Manufacturing Requirements

If you are manufacturing in accordance with IPC Class 3 or Class 3/A, your circuit board must meet important reliability standards. The manufacturer should check these points before and during the manufacturing process to ensure compliance and reliability.

06. Any Circuit Board Function That Requires a Specific Process

Advanced high-speed/high-frequency design utilizes unique waveguide wiring functions, and these functions may require highly professional testing. You should provide detailed documentation to the manufacturer so that they can assist with testing.

These tests can be performed before or after final assembly and testing. Any manufacturing defects must be fed back to the design side, and must be recorded and reported. These manufacturing defects may be missed areas in the DFM inspection process, errors in manufacturing documentation, errors in package allocation, or simply miscalculated electrical parameter values on critical networks.

Whenever a specification is violated or a fault is discovered, it needs to be reported to the design team for correction. In the case of mass production, violation or failure reports need to be completed as early as possible (preferably in the early prototyping stage). Whether the defect is discovered through quality control in mass production or during the prototype design process, it needs to be reported to the design team for correction.