X-ray(AXI) Technology

[Saki’s Planar Computed Tomography]


Saki’s Planar Computed Tomography (pCT) is a very unique technology to reconstruct plane object. It captures multiple diagonal transmission images from various directions by micro focus X-ray tube and reconstructs horizontal sectional images by computer tomography. In case of Saki’s scanning method, the detector moves parallel with the planar object against X-ray source. Without rotational axis, each diagonal image does not rotate around such axis and machine can always obtain diagonal images from any direction with the same magnification. Therefore, Saki’s pCT is capable of generating high quality sectional images and also keeping good separation in Z direction.


[High Accuracy Gantry]

Planner CT image processing is based on FOV (Field of view). Saki’s 3D-AXI machines automatically create continuous images without joints and 3D data. It allows a user to generate and manage inspection data in the same way with line scanning technology without requiring a user to intentionally execute a special operation for FOV joints even with the area of large ICs and connectors. Granite base plate gantry is the core of realizing this method. The sample stage and the detector stage are mounted on both sides of the granite to maintain straightness, flatness and parallelism to a high level. Each axis is driven directly by a linear motor in order to realize a high definition performance of positioning control and good repeatability in high speed.




[Tube Box Concept]

Saki 3D-AXI machines always irradiate the X-ray during automatic inspection to keep stability. There is a tube box with lead shielding inside the machine and X-ray source is mounted in it. The tube box has a tube shutter for shielding purpose and conveyor shutters both at entrance for carrying in and exit for taking out substrates. When loading and unloading substrates in automatic operation mode, the tube shutter is closed and the conveyor shutters are open. During scanning process, the tube shutter is open and the conveyor shutters are closed. By doing this, X-ray intensity should be kept stable and X-ray source ramp-up time is not necessary. Consequently, this contributes to stabilize operation environment of X-ray source and support a longer life of X-ray source.



[Zinc Filter]

Big amount of X-ray dose may cause damage to not only human body but also to high density electronic devices. There are several physical factors damaging to devices and the most influential factor is photoelectric effect. It will be dominant in soft X-ray wave range such as below a couple of 10kV energy areas. Zinc absorbs such soft X-ray effectively and at the same time passes high energy X-ray that is less damaging to electrical devices yet necessary for machines to perform CT analysis. Saki’s AXI machines are equipped with Zinc filter to absorb approximately 94% of X-ray dose and keep possible damage on electronic devices to the minimum.



[High Speed Planar CT Reconstruction Engine]

Saki’s AXI machines incorporate multiple cores of CPUs and GPUs in order to realize high speed planar CT reconstruction operation. Parallel processing of CPUs and GPUs have been highly optimized in order to shorten operation time to meet inline operation requirements.



[Stability of X-ray source]

Saki’s high definition X-ray inspection machines use open-type X-ray source, which separates a target from X-ray tube in an insulating way and directly measures electron beams reaching to target. By doing so, X-ray intensity from X-ray tube can be directly controlled. This approach can stabilize micro focus X-ray images of high definition for automatic inspection in line.



[Head in pillow inspection]

Detecting poor wetting of solder is an essential function required with AOI machines. Head in pillow defect occurring with BGA solder joints is the most difficult inspection item. Saki’s X-ray inspection machines perform 3D-pCT operation in real time while in operation and can detect any head in pillow defect in 3D.