'Improvements in Adhesion using New Cu Treatment Method for Substrates'

摘要

This report will discuss the differences between the current jet scrub (mechanical) and newly used chemical etch processes in the substrate manufacturing process to etch Copper. This newly proposed process is expected to increase package moisture performance by creating a rougher surface finish resulting in interlocking of the soldermask to the copper. The differences between the two processes will be covered in detail. The report will discuss moisture results obtained comparing the two processes with existing package materials in a BGA. The mold compound, non-conductive die attach and jet scrub substrate has achieved moisture sensitivity level one at 220 deg C reflow in some cases of optimized substrate design. The performance of the process is benchmarked using four substrate suppliers used in the industry. The package moisture performance improvements are critical to passing higher reflow temperature requirements such as 240 and 260 deg C for no Pb solutions for environmentally sensitive products in the wireless and palm pilot communications market. Also, included is a discussion of how the chemical etch performs based on other assembly quality measures such as wire ball shear, wire pull, solder ball adhesion and solder joint reliability. This new process is not expected to impact cost or cycle time and is seen as an improvement in overall product quality and reliability. However, due to varying experience with moisture performance of the BGA especially in cases of large die to package ratios, it is hopeful that the process will allow for more consistent results on the package.