In order to thin and reduce the weight of mobile devices, it is necessary to thin not only the semiconductor die, but also the packages. In response to demand for package thinning, resin grinding (using wheels) is often used in the low profiling of sealing resin. The workpieces (objects processed) in resin grinding are varied, such as single packages and strip substrates or wafers on which multiple packages are connected.
Recently, for the logic memory semiconductors installed in mobile devices including smartphones, the adoption of packages called wafer level packages (Fan-In Wafer Level Package and Fan-Out Wafer Level Package) is increasing. They are sealed as wafers and the sealing resin and mold resin are thinned by grinding to make them into individual packages through dicing (using blades). In the case of package laminated structures, both resin and silicon (die), or both resin and metal (electrodes) are ground concurrently in some cases.
When grinding resin, measures to prevent the grinding wheel loading are necessary. Loading, which occurs due to the resin adhering to the processing surface of the grinding wheel during processing, may cause grinding defects. Thus, it is necessary to select a grinding wheel which is unlikely to cause loading.
Resin is a material which easily warps. The thicker the resin is, the more the workpiece warps. If the workpiece before grinding is largely warped, automatic transfer of the workpiece and vacuum securing to the processing table cannot be performed. Thus, countermeasures are performed both on the transfer parts and processing table vacuum securing system in the grinder. This tends to reduce the warpage of the workpiece after grinding.
When grinding individual packages or strip substrates, in order to process multiple workpieces at a time, they are mounted and secured on a frame and processed concurrently.