Using DOE to improve COB bonbability
In recent years, the Chip-on-Board (COB) package technology has become popular in semiconductor industries. The COB technology, in which the dies are directly mounted onto a printed circuit board (PCB) with bonding wires connecting the die and leads. Besides solder bumps, wire bonding is still the most popular interconnect method. With the development of wire bonding technology in the COB package, we can realize advanced processes with good performance by new wire bonding equipment and more powerful software. However, there are still many challenges to be overcome in the bonding process. In this paper, we did experiments to optimize the bonding parameter using 1.0mil Au wire on COB and successfully found the optimal range of bonding parameters through DOE (Design Of Experiment). By the optimal solution, we further improved the bondability; the second bonding quality was also improved by using BSOB (Bond Stitch On Ball) bonding.
Dynamic response of a molded leaded package in wire bonding assembly process
In this paper, a 3-D finite element (FE) model was established to simulate the dynamic vibration in lead frame of molded leaded package (MLP during wire bonding process. The dynamic vibration response in the MLP will be examined. Four lead frame design options are investigated for their dynamic response during the wire bonding process. Two different wire bonding ultrasonic vibration directions are studied. Different wire bonding clamping methods are considered. Different polymer tape materials under lead frame are checked as well. Finally, the ball stitch on ball (BSOB) wire bonding and normal wire bonding process are compared. The FEA modeling results show that all of these factors have impacted on the neighbor leads' vibration response significantly. BSOB wire bonding method is a good method to reduce neighbor lead vibration for all four lead frame design options. This study helps to improve assembly yield in wire bonding process of a lead frame MLP.
Experimental Study on Acoustic Agglomeration of Fine Particles from Coal Combustion
The removal of fine particles in coal-fired fumes was experimentally studied based on acoustic agglomeration. An experiment facility was designed and set up. In this facility, a fluidized bed coal combustor was used as fume generator, and an Electrical Low Pressure Impact or (ELPI) was used to measure the fine particle concentration and size distribution in the fumes. The results show that under the effect of high intensity sound waves, there is good performance to remove fine particles in coal-fired fumes, which with a number mean diameter of 0.07μm. Especially, under the conditions of the frequency of 1 000Hz and the sound intensity of 161.5dB, the number concentration of 0.0233~9.314μm particles decreased by 85.2%, and their mass concentration decreased by 92.5%.