PCBA Tech - Appearance inspection and reliability of PCBA manufacturing

The techniques and methods for failure analysis of PCBA manufacturing technology mainly include: appearance inspection, metallographic section analysis, optical microscope analysis technology, infrared microscope analysis technology,

Acoustic microscope analysis technology, scanning electron microscope technology, electron beam testing technology, X-ray analysis technology, dyeing and penetration testing technology, etc. In failure analysis applications,

It is necessary to comprehensively use one or more of these technologies according to the type, phenomenon and mechanism of the failure problem to complete the failure analysis. Here is a focus on PCBA manufacturing plus

Principles, methods and applicable conditions of analysis techniques often used in process failure analysis.

SMT processing and PCBA manufacturing failure analysis

Visual inspection is mainly to analyze and inspect appearance defects. The purpose of visual inspection is to record the physical dimensions, materials, design, structure and markings of PCBs, components and solder joints.

Confirm the appearance of damage and detect abnormalities and defects such as pollution. These problems are evidence of errors, overloads and operating errors caused by process manufacturing or application. This information is likely to be related to the failure.

Visual inspection is usually used for visual inspection, and 1.5 to 10 times magnifying glass or optical microscope can also be used. One of the functions of the visual inspection is to verify the PCB, components and

The consistency of solder joints with standards and specifications; the second function of visual inspection is to look for problems that may lead to failure. For example, if there is a crack on the shell or the glass insulator, it may be

The entry of external ambient gas into the components causes electrical performance changes or corrosion. If there are foreign objects between the outer leads, the foreign objects may cause a short circuit between the leads. Mechanical damage on the PCB surface may cause the PVB trace to break and cause an open circuit.

Since failure analysis may involve destructive analysis work such as slicing and de-encapsulation, the object of visual inspection no longer exists. Therefore, detailed records should be made during visual inspection, and it is best to take some pictures. As a preliminary inspection, you may lose valuable information if you handle the test piece casually before checking the appearance. As part of this visual inspection procedure, firstly, all its information marks should be recorded, that is, the manufacturer name, specification, model, batch, date code and other information of the PCB manufacturer and component manufacturer should be recorded in detail. When carrying out reliability design, clear control requirements for production, storage, storage, and transportation should be put forward in the process documents, and the suspicious parts must be further checked with measuring instruments that can obtain information. The stereo microscope has a high degree of microscopic observation and a simple low magnification, the magnification between the two (approximately several times to 150 times). The high-magnification metallurgical microscope can be used not only for bright field observation, but also for dark field observation and differential interference observation. The magnification can be from tens of times to about 1500 times. In addition, if it is necessary to make the viewing scene deep, there is a scanning electron microscope, which has a magnification of several tens to hundreds of thousands of times and a resolving power from several mm to about 15 nm. It is an indispensable device for observing specimens with fine structures. All important information is recorded by the microscope and its photographic accessories

Failure analysis is an important part of the reliability of the chip processing technology. To carry out the failure analysis of the chip processing technology, certain testing and analysis equipment must be equipped.

All kinds of analysis equipment have their performance characteristics, application range and sensitivity. According to the needs and requirements of failure analysis, various analysis techniques and analysis methods need to be comprehensively adopted.

To determine the location of the failure, the extent of the failure, the cause and mechanism of the failure, etc. Therefore, failure analysis is related to many professional knowledge analysis theories, and also related to various

Various analysis devices and analysis experience also play an important role in failure analysis. Failure analysis of the patch processing technology Investigation and analysis of the failure of the dunk process, failure

Identification of modes, description of failure characteristics, assumptions and determination of failure modes, as well as proposing corrective measures and preventing the occurrence of new failures, etc.

The failure analysis of the patch processing technology is to perform post-mortem failure phenomena related to the assembly process, such as solder joints, vias, and wiring, which are judged to be failed according to the performance failure criterion.

The purpose of inspection and analysis is to discover and determine the cause and mechanism of failure related to the assembly process, so as to feed back to the design, manufacture and user to prevent the failure from recurring.

To achieve the ultimate goal of improving the process reliability of electronic products.

The effects of PCBA manufacturing process failure analysis are as follows:

Through failure analysis, theories and methods for improving hardware design, process design and reliable application are obtained.

Through failure analysis, the physical phenomenon that caused the failure is found, and the reliability prediction model is obtained.

Provide theoretical basis and practical analysis methods for reliability test (accelerated life test and screening test) conditions.

When dealing with PCBA manufacturing process problems encountered in the process, determine whether it is a batch problem, and provide a basis for whether batch recall and scrapping are required.