Bond Ball Connection Flatness Study On Fine Bond Pad Pitch With 2.8um Aluminum Thickness

In this paper,an influence on bond ball connection flatness and aluminum splash on fine bond pad pitch with 2.8um aluminum thickness in assembly wire bonding process was discussed.The measurement and calculation method for bond ball connection flatness was defined and quantitative study could be realized.By using pro-bond technology for first bond bonding on K&S Iconn machine and custom design of experiment method,the optimized parameter and process window was come out and the sample passed confirmation run and reliability test.After pre-production with 100 K products,the accuracy and applicability of the research result was further confirmed.In the pre-study of experiment,through compare two kinds of pro-bond mode and run 8 groups design of experiment,observe that scrub–force-force mode is better for bond ball connection flatness and aluminum splash.The main factor is bonding USG and bonding force.In custom design of experiment,using custom design to design 15 groups design of experiment and proceeding predictive analysis to make sure the experiment groups is satisfied.Based on the data analysis,the optimized parameter and process window is bonding USG 70-80 m A,bond force24-28 g and bond time 5-11 ms.To verify the result,do confirmation run and corner study confirmation run.All the groups passed reliability test.After pre-production with 100 K products,the wire bonding performance of the product and lot assembly and test yield all meet mass-production requirement.The pre-production verification meet the expected result,then will phase into mass-production and monitor and analysis the bond ball connection flatness result.Meanwhile,fan out the research to other new device which used similar wafer technology and aluminum thickness,and further evaluate the application in production.