DFN1006 New Wire Bonding Design And Implementation

The package mode of Quad Flat No-lead Package is abbreviated as QFN,which is an advanced package mode.If the appearance of QFN is rectangle,it called DFN.DFN1006 is one kind of DFN package,and its process is relatively simple,with a large market demand,the package size is the length of 10 mm and width of 6mm,so it is called DFN1006.Since DFN1006 was introduced into Chengdu Advanced Power Semiconductor com.LTD,the BSOB(bonding stich on ball,solder ball on line)had been used as the wire bonding method in DFN1006.The advantage of the BSOB includes reduced height of the bonding wire and thinning package thickness.BSOB is widely used in package of the DFN product within 0.35 mm thickness.However,the BSOB process needs an additional bump ball process,welding wire sequence is complex and its efficiency is low;furthermore,bump balls prevents cleaver from perfectly cutting off line at the end,affecting quality of the solder wire ends.Therefore,for DFN1006 over 0.5 mm thickness,BSOB mode is not a good choice.The BBOS is(bonding ball on stich)is better,which does not need to form a Bump the ball.It is compatible with 0.5 mm thickness packaging size,which is a perfect solution to improve the quality of the solder wire and greatly increase the production efficiency.The author deeply studied DFN semiconductor packaging process and basic knowledge,Fully understand the die attach process and epoxy banking,the two process are closely related with wire bonding,I found the residue of epoxy banking had a great impact for the wire bonding process,then study the compositions of epoxy,we found the composition of the residue and the removing method.Focusing on bonding materials,hardware equipment and software,the author analyzed the effect of material composition and material parameter on the BBOS process in DFN1006 product.aiming At various failure factors,engineering test is implemented.Electronic microscope is used to measure morphology of wire bonding.EDX is employed to observe crystallization of wire bonding.Based on lots of engineering test results,the optimized materials parameters,reasonable equipment parameters and process condition are obtained to realize mass production.