Flexible backplane and methods for its manufacture
View Patent ↗The present invention is directed to a flexible backplane for direct drive display devices and methods for its manufacture. The flexible backplane has many advantages. Because there is no need for a polyimide layer and only one layer of metal foil is used, the backplanes may be manufactured at a relatively low cost.
1. A backplane for a direct drive display device, which comprises:
(i) a plastic film substrate, one side of said substrate comprises an active area and an inactive area, wherein said active area comprises at least one segment electrode and said inactive area comprises at least one connecting terminal, and the other side of said substrate comprises at least a wire; and
(ii) conductive via holes through which said segment electrode and said connecting terminal are individually connected to said wire,
wherein said active area, not said inactive area, is covered by a layer of display cells, and only the connecting terminal is directly linked to a driving mechanism, and gaps between said segment electrodes and crevices of the via holes are covered by a protective layer formed from a composition comprising a polar oligomeric or polymeric material having a glass transition temperature below about 100° C. and the resulting layer has an average crosslinking density of below about 1 crosslink point per 80 molecular weight.
2. The backplane of claim 1 wherein said segment electrode and said connecting terminal are formed from a metal foil.
3. The backplane of claim 1 wherein said connecting terminal is the type of a high density pitch.
4. The backplane of claim 2 wherein said metal foil is a copper foil.
5. The backplane of claim 1 wherein a barrier layer is disposed on the side of said plastic film substrate comprising the wire.
6. The backplane of claim 5 wherein said barrier layer is formed from a thermosetting adhesive, UV curable adhesive or pressure sensitive adhesive.
7. A method for manufacturing a backplane of claim 2 , which method comprises:
a) depositing the metal foil on one side of the plastic film substrate;
b) forming the segment electrode and the connecting terminal on said metal foil;
c) applying the composition to reach the gaps and crevices and curing the composition to form the protective layer;
d) forming the wire on the side of said plastic film substrate opposite from the metal foil;
e) forming said conductive via holes; and
f) connecting said segment electrode and said connecting terminal individually to said wire through said conductive via holes.
8. The method of claim 7 further comprising connecting said connecting terminal to a driving mechanism.
9. The method of claim 7 wherein said wire is formed by printing of a conductive paste.
10. The method of claim 7 wherein said segment electrode and said connecting terminal are formed by photolithography of said metal foil.
11. A direct drive display device, comprising
a) a common electrode,
b) the backplane of claim 1 ; and
c) the layer of display cells sandwiched between the common electrode and the backplane.