Setup Surface Inspection for Visual Defect & Particle
After understanding the visual and contamination defect, now we need to setup a surface visual defect
inspection system in order to detect the surface defect and particulate contamination. There are many type of surface inspection methods, system and equipments available in the market which field engineer could select. In this article, we are going to discuss several type of surface defect inspection system which field engineer could adopt with regard to the surface defect.
The surface inspection system is implemented after the surface cleaning process in order to judge the cleaning result. Field engineer should base on the surface defect selecting proper inspection tools.
Manual Surface Visual Defect Inspection
Visual Defect / Contamination Inspection System
Human eyes inspection would be favourable to any gross visual defect; this could be mechanically damage surface defect or contamination / particle / stain. 20/20 visual inspection is the basic visual defect inspection setup condition for visual surface inspection. During this inspection process, field engineer should take extra care for light illumination or brightness as well as the light source direction.
With some of the defect contamination size, magnification glass will be used to assist the visual defect inspectionsystem. The inspection surface will but under 7-10X magnification glass for surface visual defect inspection.
Optical Defect / Contamination Inspection System
Microscope is one good for the defect size goes into micron size. 100-500X magnification is the common magnification range in most of the surface defect. For certain surface defect, the microscope requires to comes with a Nomaski function or Nomaski microscopy. With this differential interference contrast, micron size defect is more easily detected.
Interferon meter is good for surface morphology change which unable to detect under visual or microscopy inspection. Because the surface is in gradually change mode, interferon meter will be the
most suitable tool for this type of surface defect.
Contact / Non-contact CMM machine.
CMM machine is the common tool for surface visual defect inspection in PCB industry and tooling surface inspection. CMM machine also having the capability for dimension measurement, it also widely use for dimension measurement.
Automate Optical Defect / Contamination Surface Inspection System
Laser always used for micron size surface defect inspection. Perhaps Automate Optical Inspection (AOI) normally use at the precision cleaning process, because of the small defect size, only this type of AOI machine is able to carry out the job. By selecting difference wave length, laser lighting has becomes the best equipment for small surface defect. The machine manufacturer installs the laser in the mechanism and automates the surface defect inspection by scanning through the entire surface.
There are many Automation Optical Inspection system in the market, make sure select the appropriate equipment with considering the laser wave length, laser light strength decay period.
Contact / Non-contact CMM machine.
For most of the CMM machine, it has incorporated with simple program whereby the machine will automate the inspection process.
Above are the few common surface visual defect inspection systems available in the market. Field engineer should select the suitable equipment for setting up the inspection process.
DST has many years working experience on applying various surface visual defect inspection system for examining the surface cleanliness. Feel free to contact DST Technology if you need any advice for setting up surface visual defect inspection system for examine the substance surface cleanliness.
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