I’ve been taking place in a new project of a famous automotive supplier as
process engineer. Our department is responsible for the assembly processes. The
products must work reliably in extreme environmental conditions, therefore certain
components need special protection.
The solder bumps of BGA (Ball Grid Array) package provide mechanical fixing
and electrical contact with the PCB (printed circuit board). Electrically insulating glue is
dispensed under the package (with a so called underfill technology) in order to shield
the bumps from harmful effects and to enhance the strength of the fixing.
The automatic optical inspection (AOI) provides the only one in-line underfill
inspection opportunity. My task was to develop the inspection process, since the
installed AOI equipment frequently signs pseudo errors. The reason of this malfunction
is that the quality of the picture made by the optical head unit is not sufficient for
reliable image processing.
In this document I’ve presented several underfill technologies and their quality
inspection methods. I’ve described the optical inspection technologies and the
I’ve found out the problems of the current illumination system and developed an
efficient lighting for the glue inspection process. I have simulated lightings with several
wavelengths and made comparative measurements with Matlab Image Processing
Toolbox software. After the tests I’ve described the feasible solutions. I’ve selected the
best resolutions considering the measurement results and the company’s needs. At the
end I’ve evaluated the developed solution and aimed the attention to the bottlenecks as