Advanced Packaging Papers
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Fluid Flow Studies for Removing Flux Residue Under Flip Chip Die
by Mike Bixenman – Published November 2007
Abstract: Faster processing speeds drive the demand for advance packages that improve response and performance. Area array packages are moving to larger die size with increased number of solder bumps under the die. Many Class II and III circuit assemblies, that integrate advanced packages on their board designs, remove flux residue after the soldering operation. As the I/O and die size increase, the ability to penetrate, flow, and dissolve flux residue under the die becomes increasingly difficult. Several studies over the past four years have led to improved cleaning fluid and mechanical process innovations. The purpose of this research is to study fluid flow options for improving penetration and removal of the flux residue under the die using inline aqueous cleaning equipment. The paper will report video DOE results from fluid flow studies designed to clean under flip chip die.
Cleaning Wafer Level Packages
by Mike Bixenman – Published September 2009
Abstract: The feature size of integrated circuit packages is constantly shrinking, while simultaneously increasing the number of transistors incorporated into each device. Feature size reduction opens the market to faster and smaller devices. Cleaning these devices has become highly complex due to low standoff heights. Many industry standard cleaning processes do not remove flux residue trapped under low clearance components. Flux residue bridges conductors, and in some cases, heat during soldering and in use operation causes spherical solders patterns to electrochemically migrate. For many of these devices, wear out related failure is less critical in determining product reliability over the devices useful lifetime. This research reports the critical upstream factors when designing an integrated circuit packaging cleaning process.