Glossary
| Terms | Explanations |
|---|---|
| AOI | It is stand for "Automated Optical Inspection". Automatic optical appearance inspection or inspection equipment for such purpose. In the SMT process, it is often expressed by distinguishing it from SPI, and it is mainly used for inspection of component placement condition and inspection of soldering state of the board after passing through the reflow oven. |
| IR | It is stand for "InfraRed". Refers to infrared rays. In 2D inspection process, the effects of silk and flux are reduced, and the height measurement accuracy is improved during 3D inspection. |
| N-point verification | SMT process involves a variety of processes before complete. This is a software function for identifying in which process the defect occurred by checking the specific component images and log data handled in each process. SMT-related equipment manufacturers have similar functions, but only image verification from inspection equipment is common. Yamaha's N-point verification allows comparison of each process of printing, placement, and inspection with the list of previous and next work history. |
| OCR | It is stand for "Optical Character Recognition". In the SMT process, it is used for applications such as recognizing characters printed on the top surface of components. |
| QA-Option | M2M function that identifies and feeds back to pick and place machine which the target component is placed when the AOI detects NG and displays the cycle stop and warning forcibly. In addition to preventing continuous occurrence of the same defect, confirmation of pick-up and placed position of the target components, confirmation of the components recognition status, etc. can be performed quickly and easily from the warning screen. It is possible to eliminate over-judgement by making a secondary judgement by a person using a remote judgement function, etc., and to feed back only when an actual defect occurs. |
| SPI | It is stand for "Solder Paste Inspection". Automatic solder printing inspection or inspection equipment for such inspection. Although it is a kind of AOI, but often expressed by distinguishing in the SMT process, in the process after printing and coating the solder, used for inspection of the state of the solder before component placement. |
| 2D inspection | An optical camera is used to capture and inspect an object two-dimensionally by imaging from the top surface of the object to be inspected. |
| 3D inspection | In 3D inspection for SMT, it is roughly classified into "Phase shifting method" to reproduce a three-dimensional shape mainly from differences in patterns made to the object by projecting moire fringes to the inspection object, and "Stereo camera method" to image the camera from different positions and reproduce a three-dimensional shape from the parallax image, and "Optical cutting method" to reproduce a three-dimensional shape by irradiating a line laser to the inspection object and measuring. Though there are advantages and disadvantages in each of them, the system using "phase shifting method" is becoming the mainstream in 3D inspection machine marketed at present. |
| Red Eye | A phenomenon in which solder does not spread over the entire land of the board during reflow process, leaving an exposed portion of copper foil on part of lands. In case of using lead-free solder, the occurrence rate of red eye tends to increase because of poor solder wettability. |
| Phase shift method | (Refer "3D Inspection") One of 3D modelling technique adopted by many inspection equipment manufacturers in recent years. It is adopted in both SPI and AOI. A method to 3D part shapes from the amount of deformation of fringes by projecting moire fringes and imaging them with cameras. |
| Wicking | A phenomenon in which solder is sucked up to base part of lead of lead components such as SOP, and the amount of solder at the joint become insufficient. Occurs due to improper temperature profile of reflow oven or plating condition of leads. |
| False alarm | In the SMT process, the AOI and SPI cannot correctly judge a non-defective product as NG or a defective product as OK. It is also called over-judgement to judge a non-defective product as NG. Caused by inadequate tuning of the data, changes in the lot of the inspected object, changes in the color of the parts, etc. |
| Tele-centric lens | A lens whose chief ray (or principal ray) is parallel to the lens optical axis. The feature is less distortion in the appearance of the object at the lens center point and the side part, and the magnification becomes constant regardless of the distance between the object and the camera to be imaged. It is ideal lens for equipment that performs image processing. |
| Coaxial lighting | The lighting that coaxially arranges the camera to be imaged and the lighting that irradiates the imaged object. This makes it possible to detect scratches and dirt and cracks of the planar portion of the components to be specularly reflected such as a semiconductor wafer or a mirror components. |
| Batch inspection | When the inspection machine is installed in-line in the SMT process, there is a case where the operation rate of the inspection machine alone is lowered due to the difference in cycle time in each process and the stoppage due to the setup. Inspection of finished boards shall be carried out collectively separate from SMT line (offline) in order to maintain a high operating rate for the inspection machine alone. |
| Solder ball | A condition in which solder balls adhere to unintentional part of board. A short circuit is caused by entering between electrodes such as leads of component. Occurs when there is an excessive amount of solder or inadequate parameter of reflow oven. |
| Optical cutting method | (Refer "3D inspection") One of 3D modelling technique, also known as the laser method. It is mainly adopted by AOI, and many manufacturers adopt it by irradiating a line laser from two directions, and it is imaged by a camera. A method of generating 3D images by converting the resulting deformation into height information and combining it with camera images. |
| Bridge | A phenomenon solder is connected like a bridge between leads of lead components or connector and occurs short circuit. It is likely to occur when the lead pitch is narrow and the amount of solder is excessive. |
