How to choose PCBA detection method

Professional PCBA processing plants are very strict in the detection of products after they are made. There are many PCBA detection methods, and each detection technology has its own advantages and disadvantages, so it is a very flexible decision to choose the appropriate detection scheme. Choosing the right combination testing scheme is a comprehensive consideration of many factors such as time - market, time - output and time - profit, etc. Different testing technology schemes are required in different production cycles of products.

PCBA production can be roughly divided into three cycles: new product prototype manufacturing, trial production, and mass production, and the testing process scheme for these three cycles should be formulated separately.

1. New product prototype manufacturing
The testing of new product prototypes is generally planned in combination with process parameter adjustment, timeliness, economy and reliability.

(1) Solder paste coating inspection (SPI) : Use 2D/3D solder paste detector (3D solder paste detector is preferred) to detect all or key solder paste coating points (such as fine pitch and ultra-fine pitch devices), and extract and record solder paste parameter values. In the prototyping phase, it is allowed to use visual inspection instead of SPI inspection equipment when the time is short.
(2) Flying needle detection (FP) : the prototype product production quantity is limited, the time requirement is tight, and the flying needle type online detector does not need to make needle bed, fixture, save the work and time of this link, can directly accept the PCB design data from the CAD system to automatically generate the corresponding detection program, the most suitable for assembly and welding inspection work.
(3) Function testing (FT) : function testing is mainly to verify the product design indicators and debug, can find the failure of components, electrical principle design rationality and other problems.
For the prototype production of BGA and flip-chip packaged devices, the solder joints or key solder joints of this type of device should be detected by X-ray detector before flying needle inspection under the condition of ability, so as to ensure the internal quality of solder joints.

2. Trial production
The main purpose of pilot production is to verify the stability of process parameters, and the test of prototype production is fully applicable to the pilot production stage.

3. Mass production
Batch production can be divided into three categories: large, medium and small, and there is no exact regulation in the concept of quantity.

(1) Mass production

① Mass production is the most economical production mode. After completing all the preparation conditions for assembly production, more advanced automatic testing equipment should be used to replace manual testing, so as to ensure that the quality of product assembly is strictly monitored, improve the efficiency of production line and testing, and increase the return on investment. Without the production of products similar to BGA and flip-chip packaging device assembly, AOI can replace X-ray inspection to reduce production and inspection costs.

② For the assembly of product process requirements of solder paste printing quality strict control, should also be set in front of the X-ray automatic detection of 3D solder paste coating detector, each PCB solder paste printing situation to check, to ensure the consistency of the printing effect of the screen printer, to ensure that the printing process parameters can be adjusted at any time according to the situation.

(2) Medium and small batch production
The roduction cycle of products in medium and small batch production is shortened. From the perspective of reliability, credibility, quality and economy, the detection scheme is considered for general component assembly products and special package device assembly products respectively. Usually, products containing special package devices should be preferred to adopt higher level detection methods, such as AXI, etc. The two types of devices are classified as follows:

① General component assembly products: the most complex devices are fine pitch, ultra-fine pitch QFP (four-side pin flat package device), etc.
② Special package device assembly products: including BGA, Flip-chip (flip chip) and other surface can not see the solder joint or the average solder joint density is very high, there is no detection circuit.