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ESD Protection Design for Gate Line Leed on TFT/LCD

IP.com Disclosure Number: IPCOM000014692D
Original Publication Date: 2000-Jan-01
Included in the Prior Art Database: 2003-Jun-20
Document File: 2 page(s) / 487K

Publishing Venue

IBM

Abstract

Disclosed herein is a ESD (electrostatic discharge) protection for gate line lead on TFT/LCD, where dummy metal line close to the last gate line and increasing plane metal area connected to the counter electrode (ITO) through transfer pad. For large size and thin glass TFT/LCD, electrostatic charge in process (TFT fabrication and cell fabrication) is easier to occur and causes breakdown to metal even through passivation layer. For TFT design, Cs (storage capacitor) line-connections and V com line connections are put on gate line edge side close to separated metal lead for TAB (tape automated bonding) connection. Usually transfer pad is designed on space between gate-metal lead separation. In case of this, the electrostatic discharge is easily occurred to closest gate-line lead from charged space for transfer pad area. By this ESD, the worm-bite shape appeared on the edge of gate-line lead, and causes line defect or line discontinuity for the worst case. To protect discharge damage to the actual gate line lead, two protection method are described, which are: minimizing electrostatic charge by transfer pad design and specially designed dummy-metal line lead to be discharged intentionally.

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ESD Protection Design for Gate Line Leed on TFT/LCD

    Disclosed herein is a ESD (electrostatic discharge) protection for gate line lead on TFT/LCD,
where dummy metal line close to the last gate line and increasing plane metal area connected to the
counter electrode (ITO) through transfer pad. For large size and thin glass TFT/LCD, electrostatic
charge in process (TFT fabrication and cell fabrication) is easier to occur and causes breakdown to
metal even through passivation layer. For TFT design, Cs (storage capacitor) line-connections and V
com line connections are put on gate line edge side close to separated metal lead for TAB (tape
automated bonding) connection. Usually transfer pad is designed on space between gate-metal lead
separation. In case of this, the electrostatic discharge is easily occurred to closest gate-line lead
from charged space for transfer pad area. By this ESD, the worm-bite shape appeared on the edge of
gate-line lead, and causes line defect or line discontinuity for the worst case. To protect
discharge damage to the actual gate line lead, two protection method are described, which are:
minimizing electrostatic charge by transfer pad design and specially designed dummy-metal line lead
to be discharged intentionally.

Figure shows TAB design to protect ESD failure, where includes dummy metal line (next to and covering
Cs lead line), and large plane-shape (home-base
shape in this case) common electrode (V com) pad.

The key point is double protection as:
1) intentional ESD occurrence to the restricted or expected position by dummy metal line,
2) minimization of electrostatic charge by larger common electrode (V com) or transfer pad area
The dummy metal is de...