We will explain the outline, applications, principles, etc. of the board inspection equipment.
What is a board inspection device?
A board inspection device is a device that inspects defects in the manufacturing process of surface-mounted electronic boards. There are many visual inspection devices , but there are also solder printing inspection devices, 3D-CT inspection devices and X-ray inspection devices that can obtain information on the inside of the solder . In addition, some manufacturers classify dimensional inspection equipment as one of the board inspections.
It is used after the reflow after the final soldering in the surface mounting process of the electronic board, and it is confirmed whether the solder is properly welded.
Usage of board inspection equipment
Board inspection equipment is used to inspect most surface-mounted electronic boards. Until now, a certain number of electronic boards have sampled and inspected by humans, but by using a board inspection device, 100% inspection has become possible. There are various appearance items such as missing items, misalignment, and unsoldered items inspected.
In addition, the dimension inspection device inspects the dimensions of electronic boards such as headlamp LED boards, millimeter-wave radar boards, CMOS sensor boards, and IGBT power modules.
Principle of board inspection equipment
Board visual inspection equipment includes electronic board inspection equipment and solder printing inspection equipment. In both cases, the defect judged from the image taken by the high-performance camera and the set threshold value. The solder printing inspection equipment detects solder paste misalignment and defects.
In the 3D visual inspection method that does not use X-rays, multiple images of the target electronic board work at different angles using a high-performance camera. And height information obtained by combining them detect abnormalities.
Recently, 3D-CT inspection devices using X-rays have appeared. The 3D-CT inspection device can scan each layer to build a 3D image. It inspects not only the inside of a single layer but also the inside of a multi-layer board. It checks the layer misalignment and drilling of the printed circuit board. And it inspects products probablely inspected only by appearance, such as bottom electrode parts, laminated parts, and insertion parts. Therefore, the introduction examples are spreading. There are also devices inspected in a complex way by using a combination of X-rays, visible light, infrared rays, etc.
AOI is an automated optical inspection device.
For 2D type AOI, the inspection method using the line scan method using a line sensor camera adopted.
In the line scan method, the entire board is imaged while switching the lighting at high speed, enabling high-speed inspection.
You can also use UV lighting to inspect for uncoated or scattered coatings, and to automatically detect defects such as surplus parts and dust in unexpected boards.
The 3D type AOI can detect the quantitative height information of the parts in the board and recognize the parts position.
By visualizing in 3D, it is possible to inspect the inclination and floating of parts, which was difficult with the 2D type, and it is possible to improve the accuracy of solder paste inspection.
Foreign matter inspection
There is a device that inspects foreign matter on the board.
If foreign matter gets into the product, various problems will occur.
If conductive foreign matter mixed in semiconductor products, it may cause the product to deteriorate in function.
Also, if you paint the sheet metal, it will cause a defect in appearance.
In order to prevent defects, foreign matter inspection can perform before processing the board and before final shipment to prevent defects.
Some board inspection equipment uses a hybrid method of phase shift method and color highlight method.
With the hybrid method, it is possible to acquire the 3D shape of the solder and parts.
The acquired data used to visualize the solder bonding status and mounting status.
In many cases, we use standard inspections for non-defective products, which minimizes the risk of overlooking defects.
This makes it possible to exclude empty land solder from inspection in advance.