Glass substrate is a sheet glass which makes flat panel displays (FPD), such as liquid crystal televisions (LCD), plasma televisions (PDP), and  laptops displays. The ingredients differ from the sheet glass used for windowpanes. Ingredients also differ between liquid crystal and plasma displays.
As the production process for glass substrate, there is the floating method which takes out the melted glass horizontally the same way windowpanes are processed, and the fusion method which removes the glass in a downward perpendicular direction. Glass sheets made using these methods and cut according to customer specifications is referred to as the mother glass. After completing the surface polish and other treatments, the glass is packaged in to a box called Packer. The thickness of the glass substrate is normally 3mm or less, with the thinnest sheets being 0.5mm. Since the products become defective from dirt or cracks, portions which can be maintained are limited. For this reason, the difficulty of handling the glass substrate will increase with the size of glass.
Perpendicular packaging is most widely used method to box up glass substrates. Glass sizes up to G5 (shown below) packing was packaged by maintaining spaces between the glass substrates, but large glass beyond G6 is packaged by inserting a jointing paper between the substrates to prevent damage. This packaging method requires a large sized multi-jointed robot and exclusive unit to perform this operation in a packer device.
The device that removes the glass substrate from the box by the panel maker is called the un-packer.  The removed glass substrate is inserted to  a container called the cassette. The cassette is then supplied to a manufacturing line.  The equipment that picks up the glass substrate from the cassette and removes the processed glass substrate from the processing line is called loader/un-loader. The dual-arm type robot primarily applied to a loader/un-loader device which extracts and supplies the glass substrates is capable of performing continuously.

Mother Glass’s size for glass substrate manufacturing is becoming larger every year. The demand is driven from the growing number of and size of products ranging from calculators to laptops and more recently televisions that require single mother glass sheets.
The size of the mother glass is expressed in generations that represent  the general size measurements. Changes in general sizes are shown as follows. (In the case of the glass substrate used for TFT-LCD)