Plasma display panel vacuum in-line sealing technology by using a bubble-reduced frit

Improper base vacuum level in any vacuum microelectronic device, such as a plasma display panel (PDP), will damage the overall performance of the device due to impurities such as $H2,$ $O2,$ CO, $CO2,$ and $N2.$ In conventional tubulation packaging technology, the obtainable base vacuum level before plasma gas filling will be very poor because of the pumping conductance limitation for such a large panel size with a small gap of 150 μm, especially due to the barrier ribs inside the PDP panel. The time required to reach any reasonable level will be too long. In this study, we performed the sealing of the two glass plates composing the PDP panel, a plasma gas filling into the panel and a hole-off (named instead of a conventional “tip-off”) process, all in a vacuum chamber, called as “vacuum in-line sealing.” Several factors related with the heating process of a frit glass were investigated. A prepared frit glass was successfully applied for the vacuum in-line sealing approach without suffering bubbles. We successfully have fabricated an operable PDP panel with a 2 in. diagonal size by using the fully vacuum in-line sealing technology for the first time in the world. The sealing temperature of the two plates was around 330 °C which corresponded to a temperature about 120 °C lower than that used in a conventional air environment. The base vacuum level inside the panel before gas filling was about $5×10−6 Torr$ at the time of sealing. The total elapsed time for the sealing processes was less than 6 h, including the gas fill and the hole-off processes.