Integrated solution for high speed data filtering using package-in-package approach

In addressing emerging high speed interface such as USB 2.0, IEEE1394, LVDS and DVI in electronic devices, discrete solution of using choke and ESD diodes is a common practice in the PCB assembly in eliminating the common mode noise and providing ESD protection to the electronice device [1]. However, this brings up the cost and cycle time as PCB manufacturers have to purchase several components and mount them separately on the PCB. Consequently, a larger PCB footprint is required. In this paper, we introduced the first-to-market integrated common mode filter with ESD protection using package-in-package technology in DFN platform. This is an integrated solution that offers cost savings and space reduction in responds to the needs of portable digital devices which are increasingly smaller and thinner. The attachment of passive component in a DFN package adds complexity to the existing assembly process. The use of lead free solder paste and its selection were discussed in this paper. Solder printing on lead frame was employed for the component placement due to its high process throughput compared to the conventional dispensing method. This paper also elaborated on the stencil design and solder printing characterization. It included the modification in lead frame design to enhance the product quality. The effect of solder reflow was also addressed in the paper. The final product was assembled with the newly established process flow and passed MSL 1 @ 260°C reliability test. The integrated package passed the reliablity stress tests and validated the concept of package-in-package in DFN platform.