With the development of society more and more electronic products, each electronic product is controlled by a PCB, so PCBA production and processing is important to do a good job in quality control, is the quality assurance. The following is an introduction to PCBA production how to do a good job of quality control.
PCBA production and processing how to do a good job of quality control
1, general requirements
1) First inspection: according to the quality inspection standard content, self-inspection, special inspection:.
2) Strictly in accordance with the operating procedures, work instructions for operation;
3) Set quality control points in accordance with the product process, to determine the key parts, key processes, key process parameters;
4) Regularly monitor the operating status of equipment;
5)Execute inspection system.
2、Solder paste printing
1) Equipment parameters, environment (temperature and humidity) setting records and verification.
2) Solder paste graphics accuracy, thickness check.
- Determine the key components of concern, the use of designated devices to determine the thickness of solder paste printing on its pads;
- Monitoring of the whole board solder paste printing, test points selected in the printed board test surface of the upper and lower, left and right and the middle and other 5 points, the general requirements of the solder paste thickness range between -10% to +15% of the thickness of the template.
- Application of solder paste: the retention time on the board, the quality of welding.
1) manual welding: the quality of the solder joint should meet the inspection standards and job level requirements.
2) Reflow soldering, wave soldering: once through rate, quality PPM.
- New products, change of line, shift, change of solder and flux, repair, upgrade, transformation and other circumstances actual measurement of the furnace temperature curve to ensure that the equipment to meet normal use;
- Monitor the actual furnace temperature according to the specified cycle;
- Periodically check the equipment temperature control system.
Solder: Each batch should be verified for its practical welding effect and process compliance. Wave soldering should be periodically tested for excessive harmful substances in its solder tank.
Type of non-contact nondestructive testing, divided into black and white, color two, used to replace the manual visual inspection.
☆ Group line application is more flexible, a variety of process locations are available;
☆Limited to surface visible fault inspection;
☆Fast and consistent inspection effect;
☆High requirements for consistency of color and brightness of PCB and components.
Applicable to board-level circuits with a resolution of about 5-20 microns.
The application of X-ray inspection technology in the assembly of board-level circuits began to be applied only in the early 1990s in the manufacture of board-level circuits for military electronic equipment. New package devices such as PGA, BGA, CSP, etc. on PCBA of electronic products are widely used.
X-ray inspection of certain components (such as crystal oscillators, etc.) may be risky.
Forming: whether the lead length, shape, span, and logo meet the product and process requirements;
Insertion: the distribution of wrong parts, missing parts, reverse, component damage, kneeling legs, lost parts;
The reasonable degree of work process.
2) Tabulated parts.
Statistics of wrong parts, missing parts, flying parts, reversal, reverse parts, offset;
Rate of lost parts; Accuracy rate.
5、Inspection and testing
Misjudgment rate: detection standard database, test strategy ;
Detection rate: failure to detect the distribution of content.
Missed detection rate ;
Personnel qualification level.
Manual visual inspection
Limited to surface inspection;
High labor intensity, easily fatigued;
Fault coverage rate is only about 35%;
High density and fine pitch PCB inspection mainly with the help of about 5-40 times magnification.