Newly developed ultralow CTE materials for thinner PKG applications

The higher density packaging technologies have been required to reduce the area of substrate for smaller portable handheld products and devices such as smart phones and tablet PCs. So, the three-dimensional packaging is becoming to be a key technology to minimize the total size of products and devices. However, the thinner construction of PoP (package on package) may cause the poor connection reliability because of the warpage of the substrate at the soldering process. So, the reduction of the warpage of the substrate by the ultralow CTE (coefficient of thermal expansion) materials may be the key to overcome. Recently, we have developed two types of ultralow CTE materials to meet with the requirement applying our new resin systems and a filler treatment technology. The developed materials show the ultralow CTE(X) of 2.8-3.3 ppm/^OC which is close to that of the glass fabric. The resulted warpage using the material is much lower than that of the conventional low CTE material. We are also developing a technology for the further lowering of CTE for future applications.