PCB manual inspection
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PCB Manual Inspection

In the PCBA board manufacturing process, in order to ensure the quality of the assembly, both the manufacturer and the customer will require the production staff to conduct detailed PCB testing. In a large number of testing programs, some require customers to bear part of the testing costs, while others are provided free of charge by the manufacturer. As a Chinese PCBA manufacturer who advocates product quality, FS Technology provides free PCB manual testing for the entire assembly process.

Manual Visual Inspection or MVI is a technique used to find the different faults existing in the boards through the use of magnifying glass or the naked eye. The quality of this process depends on the expertise of the person who performs this process and so results can be varied according to operator concentration. Since this is a time-consuming inspection process, many manufacturers ignore it, but FS Technology believes that it is necessary and can be used to confirm the complete connection pattern with or without solder, missing solder, or unsoldered. FS Technology uses a magnifying glass and professional inspectors to ensure whether the PCB/PCBA board meets the requirements of the required project.

pcb inspection manual

Manual visual inspection is at those stages in turnkey PCBA?

Turnkey PCBA service refers to a full set of PCB services from manufacturing to IC programming to assembly. No matter which PCBA service you order, FS Technology will perform PCBA manual inspection according to strict requirements. During this inspection technique, the configuration of the circuit board is compared with the design layout of the board to make sure all features are fulfilled. With that, some other faults are detected during MVI based on the type of board and components connected to the board. Therefore, it is best to add MVI technology to every PCBA service process. Listed below is a manual visual inspection checklist during PCB fabrication and PCB assembly.

  • During the PCB manufacturing process, MVI ensures accurate board thickness as well as surface roughness and warpage.
  • Visually check whether the size of the electrical connector and PCB components meets the board specifications.
  • The structure and clearness of the conductive pattern were checked and also monitoring of burrs, voids, and soldering bridging done.
  • There is surface quality monitored after that to check the presence of pits, scratches, pinholes, dents, etc.
  • It is confirmed that all vias are existing in the accurate locations. It ensures that there are not incorrectly positioned and their diameter is according to design requirements.
  • There is the inspection of pad plating is done to find its roughness, firmness, and brightness.
  • Observe whether the components of the first assembled PCB are consistent with the BOM list; confirm that the components are placed in the center of the solder paste; the most important thing is to visually inspect the positive and negative extremely sensitive components.
  • Evaluation of conformal coating quality on prototype PCBA boards.

Advantages of MVI PCB Assembly Inspection

  • The visual inspection of PCB assembly is the main part component to ensure the quality of the resultant product. Visual inspection technique with a combination of the AOI method provides the required information to remove the faults existing in the board.
  • MVI offered some good features than other inspection techniques since it is easy to perform and has free.
  • There are no certain types of instruments needed to perform this method just for magnification some optic instruments are needed. 
  • This process takes less time to complete so can be used for each step involved in PCB fabrication and assembly.
  • There is just a need for an expert person to perform this test that will enhance the chance of accuracy. With that operators also have clear design features of the board to make sure that every inspection is done accurately.

Limitations of MVI Assembly Assays

  • TheYou can not inspect the faults of components that are not in your line of sight. 
  • Some hidden solder joints can not be inspected through this technique.
  • This technique will not be effective to detect the faults of complicated boards since they have small components that are configured in a complex way not easy to access.

How to carry out manual visual inspection of PCB?

To perform the manual visual inspection of the PCB board the inspection person gets the overview of the board through the naked eyemagnifying glass or microscope. First of all inspection person make a comparison between the board and design requirements or design files. Through this step, we can confirm whether the board is according to design requirements or not.

After checking the commonly existing faults on board. The faults existing on the board are based on the type of board, the components connected, and the manufacturing phase of the board.  In a simple way when solder paste is applied and components are connected on board, so inspection is performed to check the solder paste contamination. Through inspection, we will check components on the boards are connected properly and not any component missing. There are some points monitored through PCB assembly visual inspection.

  • Coating quality
  • Pad plating quality
  • Assembly dimensions
  • Quality of board surface
  • Conductive pattern clarity is checked.

PCBA Inspection during DFM Process

It is part of the board production step of NPI or new product introduction numerous electronics manufacturers outsource the creation of PCB design to turnkey PCBA manufacturers. At starting of prototype PCB assembly, manufacturer make the same replica of the board design drawing, that is according to users’ features. Here it is confirmed that the design is according to the objective and fit for the main purpose. The prototype was inspected using a microscope to find any existing faults.

After the approval of the refined model of the prototype and confirmation of fault absence, a larger number of PCBAs was created. EVT and DVT tests were performed. PCBA failure analysis and cosmetic check of the board done to fulfill that board is according to customer specification.

At last PVT or production validation test is performed. This is the final build phase before small batch PCB assembly moves to wholesale assembly. Throughout DFM process visual inspection is done through the use of a microscope and picture recording to make sure the client’s requirements. Continuous visual inspection saves many potential design errors and helps to make a less expensive manufacturing process. It also helps to make modifications in design if needed to get the good results.

Manual inspection before mass PCB assembly

The main objective of the inspection is to detect faults and solve them as soon as possible. To make sure there is a need to follow a special inspection plan. Nowadays small size boards with complicated structures are created to handle sophisticated designs of products.  It indicates that there is a need of a details inspection and has to perform an inspection at each manufacturing step of the board. Visual inspection is a significant option to inspect the PCB board.

It should be noted that there are different methods used for the quality control process, so a visual inspection can also be used with other methods.

Summarize

This test ensures the accurate position of components, correct connection, and soldering material used for the PCB board.  Manual visual inspection of PCBA board is an inspection technique that is done by an expert person having details knowledge of PCB and its related parameters to easily find the faults existing in the board. Through this method, operators make sure the board configuration is according to requirements. After that inspector finds the faults existing in the board. Faults exist on the board depending on the board type, the component connected to the board, and the manufacturing process of the board.

The main facts observed during the manual visual inspection are the quality of coating, pad plating quality, board dimensions, surface quality ad pattern of conductive paths. Through this technique, we can discuss almost every aspect of the PCBA.

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