An increasing demand for smaller, more compact electronic devices has driven an increased effort to reduce the sizes of its internal components. The internal components include packaged devices. Thus, there is an increased effort to decrease the size of packaged devices. Packaged devices typically include an integrated circuit device coupled to a package substrate. The package substrate interconnects the integrated circuit device to a system board. To minimize the amount of space occupied by the packaged device, industry leaders have invested in ways to decrease the thickness of package substrates. Decreasing the thickness of package substrates, however, is not without issues.
As package substrates continue to decrease in thickness, the amount of mechanical instability, such as bending or curving, increases. Such mechanical instability is a significant contributor to fabrication issues after wafer singulation. For instance, bent or curved package substrates can affect throughput and yield if the package substrates cannot be attached properly onto a system board. As a result, methods have been implemented in the package assembly process to address these issues.
Substrate manufacturing processes are performed in a panel or subpanel of packages. In the last steps of substrate manufacturing, the panel is singulated to form individual package substrates. The package substrates are then attached to an integrated circuit, such as a semiconductor die, during the assembly process. The attachment can cause the package substrate to warp or curve due to different coefficient of thermal expansions for the integrated circuit and the package substrate. To address the issues related to bent or curved package substrates, each individual package substrate may be flattened by attaching a stiffener.
Current methods attach stiffeners to individual package substrates in the package assembly process. The stiffeners may be formed by any conventional process, such as a transfer molding process. In such methods, a mold is placed directly around a singulated package substrate. A mold compound, such as a filled epoxy material, is then injected into the mold. After the mold compound cures, the package is removed and the cured mold compound remains as a stiffener on the singulated package substrate. Performing the transfer molding process at a singulated level is costly and has high total processing time for large volumes of production.
Alternatively, the stiffeners may be incorporated by an attachment process. The attachment process adheres a pre-made stiffener to a singulated package substrate by an adhesive material. Attaching stiffeners to the singulated package substrates can be less costly than the transfer molding process, but can have low alignment accuracy and high total processing time for large volumes of production. Accordingly, conventional processes for stiffening package substrates are inefficient and time consuming.
Attaching stiffeners after singulation has plenty of additional shortcomings. For instance, attaching stiffeners after singulation increases the chances of having rotational misalignment and/or translational misalignment between the stiffeners and the package substrates. Misalignment can create overhang where the stiffener protrudes over an edge of the package substrate. To compensate for overhang, edges of the package substrates may be extended. Extending the edges of the package substrates may result in a detrimental increase in package size.