Nondestructive measurement of bond line thickness and die tilt in the die attach for semiconductor packaging

The present investigation describes about the development of a cost effective measurement technique for automatic determination of bond-line thickness and die tilt in die attach for semiconductor packaging process. Bond line thickness (BLT) and die tilt in the die attach were measured using an optical non contact scanning probe system. The probe system was consisted of a line laser diode as the light source and a high resolution charge couple device (CCD) camera to acquire the image of the laser line. Software was developed considering least square polynomials to acquire the objects space coordinate from the image coordinate in CCD. A transparent grid with regularly spaced nodal points was used to construct the space mapping function. This measurement system can accurately determine the BLT by scanning it at high speed with laser line and detecting the image by CCD. The BLT and die tilt of a die attached chip of substrate height 800 μm and cross section 15 mm × 15 mm were measured to be approximately 76.3 μm and 0.007°, respectively.