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PCBA production has a good quality control method.

October 12, 2020

1846

1. General requirements


1) First article inspection: According to the content specified in the quality inspection standard, self-inspection and special inspection:


2) Operate strictly in accordance with operating regulations and work instructions;


3) Set up quality control points in accordance with product process flow, and determine key parts, key processes, and key process parameters;


4) Regularly monitor the operating status of the equipment;


5) Implement the inspection system.


2. Solder paste printing


1) Equipment parameters, environment (temperature and humidity) setting records and verification.


2) Inspection of solder paste graphic accuracy and thickness:


a. Determine the key components and use the designated device to measure the thickness of the solder paste printed on the pad;


b. To monitor the printing situation of the entire board solder paste, the test points are selected at 5 points on the test surface of the printed board, including the upper and lower, left and right, and middle points. Generally, the thickness of the solder paste is required to be between -10% and +15% of the template thickness.


c. Solder paste application: retention time on the board and soldering quality.


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3. Welding


1) Manual welding: The quality of solder joints should meet the inspection standards and job level requirements.


2) Reflow soldering, wave soldering: one pass rate, quality PPM.


a. Measure the furnace temperature curve for new products, line change, shift change, solder and flux change, maintenance, upgrade, transformation, etc., to ensure that the equipment meets normal use;


b. Monitor the actual furnace temperature according to the specified period;


c. Check the equipment temperature control system on schedule.


Solder: Each batch should verify its practical welding effect and process compliance. Wave soldering should regularly check whether the content of harmful substances in its solder tank exceeds the standard.


Optical inspection


The type is non-contact non-destructive testing, which is divided into black and white and color to replace manual visual inspection.


☆The assembly line application is more flexible, and a variety of process positions are available;


☆Limit to the inspection of visible faults on the surface;


☆Fast speed and good consistency of inspection results;


☆High requirements for chromaticity and brightness consistency of PCB and components.


X optical inspection


The resolution suitable for board level circuits is about 5-20 microns.


The application of X-ray inspection technology in board-level circuit assembly only began to be used in the manufacture of board-level circuits in military electronic equipment in the early 1990s. New packaging devices such as PGA, BGA, and CSP on PCBA of electronic products are widely used.


X-ray detection of certain components (such as crystal oscillators) may be risky.


4. Component installation


1) Insertion:


Forming: Whether the lead length, shape, span, and identification meet the product and process requirements;


Plug-ins: the distribution of wrong parts, missing parts, reverse, damaged components, kneeling legs, and missing parts;


The process is reasonable.


2) Surface mount parts:


Statistics of wrong parts, missing parts, flying parts, reverse, reverse parts, and offset;


Loss rate; accuracy rate.


5. Inspection and testing


1) Detection:


False judgment rate: testing standard database, testing strategy;


Detection rate: The distribution of content that failed to be detected.


2) Inspection:


Missed detection rate;


Personnel qualification level.


Manual visual inspection


flexible;


Limited to surface inspection;


low efficiency;


Poor consistency


High labor intensity, easy to fatigue;


The fault coverage rate is only about 35%;


Mainly with the help of 5-40 times zoom lens for high-density, fine-pitch PCB inspection.