PCBA Tech - Inspection of PCB multilayer circuit board assembly

In order to complete the requirements of multi-layer PCB circuit board assembly detection, a variety of detection devices have been produced. Automatic Optical Detection (AOI. Systems are typically used for testing the front and inner layers of layers. After layering, X-ray systems monitor alignment accuracy and minor defects. Scanning laser systems provide methods for detecting the bonding pad layer before reflux. These systems, together with visual inspection techniques for production lines and integrity testing for components that automatically place components, help ensure final assembly and availability of welded plates Reliability.

Multilayer PCB circuit board assembly is prone to the following defects:

1. Component missing.

2. Component failure.

3. There is an installation error and misalignment in the components.

4. Component failure.

5. Poor tin exposure.

6. Tin bridge short circuit.

However, even if these efforts minimize defects, final testing of the assembly of multilayer PCB circuit boards is still required, which may be most important as it is the final unit for product and process evaluation.

Final detection of the assembly of multilayer PCB circuit boards may be done either by active means or by automated systems, often using both methods together. "Manual" means that an operator uses an optical instrument to pass a visual inspection board and make the correct judgment about the defect. Automated systems use computer-aided graphic analysis to identify defects. Many people also believe that automated systems contain all detection methods except manual light detection.

X-ray technology provides a method for evaluating solder thickness, distribution, internal voids, cracks, de-bonding, and the presence of solder balls. Ultrasound will detect holes, cracks, and untouched interfaces. Automatic optical testing evaluates external features such as bridging, tin melting, and shape. Laser detection provides a three-dimensional image of external features. Infrared detection detects internal weld failure by comparing the thermal signal of a weld with a known good one.

It is worth noting that these automatic detection technologies have found all the defects that cannot be found by the limited detection of the assembly of multilayer PCB circuit boards. Therefore, manual visual detection methods must be combined with automatic detection methods, especially for those small applications. The combination of X-ray detection and manual optical detection is the best method to detect defects in the assembly board.