Compliant substrates for thin-film transistor backplanes

S. Wagner, Helena Gleskova, E.Y. Ma, Z. Suo

Research output: Chapter in Book/Report/Conference proceedingConference contribution book

2 Citations (Scopus)

Abstract

The emergence of wearable electronics is leading away from glass substrates for the display backplane, to plastic and metal. At the same time the substrate thickness is reduced to make displays lighter. These two trends cooperate toward the development of compliant substrates, which are designed to offload mechanical stress from the active circuit onto the substrate (and encapsulation). Compliant substrates make the circuit particularly rugged against rolling and bending. Design principles for compliant substrates include: (a) Moving the circuit plane as close as possible to the neutral plane of the structure, and (b) Using substrate and encapsulation materials with low stiffness. Design principle (a) is demonstrated on thin-film transistors made on thin steel foil. Such transistors function well after the foils are rolled to small radii of curvature. Principle (b) of compliant substrates is demonstrated with bending experiments of a-Si:H TFTs made on thin substrates of polyimide foil. TFTs on 25-mu m thick polyimide foil may be bent to radii of curvature as low as 0.5 mm without failing. The reduction in bending radius, from R similar to 2 mm on same-thickness steel foil, agrees with the theoretical prediction that changing from a stiff to a compliant substrate reduces the bending strain in the device plane by a factor of up to 5.
LanguageEnglish
Title of host publicationFlat panel display technology and display meterology
EditorsB. Gnade, E. F. Kelley
Place of PublicationBellingham, WA
Pages32-39
Number of pages7
DOIs
Publication statusPublished - 1999
EventConference on Flat Panel Display Technology and Display Metrology - San Jose, California, United States
Duration: 27 Jan 199929 Jan 1999

Publication series

NameProceedings of the Society of Photo-Optical Insturmentation Engineers (SPIE)
PublisherSPIE
Volume3636
ISSN (Print)0277-786X

Conference

ConferenceConference on Flat Panel Display Technology and Display Metrology
CountryUnited States
CitySan Jose, California
Period27/01/9929/01/99

Fingerprint

transistors
thin films
foils
polyimides
radii
curvature
steels
stiffness
plastics
trends
glass
predictions
electronics
metals

Keywords

  • plasma enhanced chemical vapor deposition
  • thin-film transistor
  • steel substrate
  • plastic substrate
  • mechanical stress
  • hydrogenated amorphous silicon

Cite this

Wagner, S., Gleskova, H., Ma, E. Y., & Suo, Z. (1999). Compliant substrates for thin-film transistor backplanes. In B. Gnade, & E. F. Kelley (Eds.), Flat panel display technology and display meterology (pp. 32-39). (Proceedings of the Society of Photo-Optical Insturmentation Engineers (SPIE); Vol. 3636). Bellingham, WA. https://doi.org/10.1117/12.344653
Wagner, S. ; Gleskova, Helena ; Ma, E.Y. ; Suo, Z. / Compliant substrates for thin-film transistor backplanes. Flat panel display technology and display meterology . editor / B. Gnade ; E. F. Kelley. Bellingham, WA, 1999. pp. 32-39 (Proceedings of the Society of Photo-Optical Insturmentation Engineers (SPIE)).
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Wagner, S, Gleskova, H, Ma, EY & Suo, Z 1999, Compliant substrates for thin-film transistor backplanes. in B Gnade & EF Kelley (eds), Flat panel display technology and display meterology . Proceedings of the Society of Photo-Optical Insturmentation Engineers (SPIE), vol. 3636, Bellingham, WA, pp. 32-39, Conference on Flat Panel Display Technology and Display Metrology, San Jose, California, United States, 27/01/99. https://doi.org/10.1117/12.344653

Compliant substrates for thin-film transistor backplanes. / Wagner, S.; Gleskova, Helena; Ma, E.Y.; Suo, Z.

Flat panel display technology and display meterology . ed. / B. Gnade; E. F. Kelley. Bellingham, WA, 1999. p. 32-39 (Proceedings of the Society of Photo-Optical Insturmentation Engineers (SPIE); Vol. 3636).

Research output: Chapter in Book/Report/Conference proceedingConference contribution book

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AU - Gleskova, Helena

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AU - Suo, Z.

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N2 - The emergence of wearable electronics is leading away from glass substrates for the display backplane, to plastic and metal. At the same time the substrate thickness is reduced to make displays lighter. These two trends cooperate toward the development of compliant substrates, which are designed to offload mechanical stress from the active circuit onto the substrate (and encapsulation). Compliant substrates make the circuit particularly rugged against rolling and bending. Design principles for compliant substrates include: (a) Moving the circuit plane as close as possible to the neutral plane of the structure, and (b) Using substrate and encapsulation materials with low stiffness. Design principle (a) is demonstrated on thin-film transistors made on thin steel foil. Such transistors function well after the foils are rolled to small radii of curvature. Principle (b) of compliant substrates is demonstrated with bending experiments of a-Si:H TFTs made on thin substrates of polyimide foil. TFTs on 25-mu m thick polyimide foil may be bent to radii of curvature as low as 0.5 mm without failing. The reduction in bending radius, from R similar to 2 mm on same-thickness steel foil, agrees with the theoretical prediction that changing from a stiff to a compliant substrate reduces the bending strain in the device plane by a factor of up to 5.

AB - The emergence of wearable electronics is leading away from glass substrates for the display backplane, to plastic and metal. At the same time the substrate thickness is reduced to make displays lighter. These two trends cooperate toward the development of compliant substrates, which are designed to offload mechanical stress from the active circuit onto the substrate (and encapsulation). Compliant substrates make the circuit particularly rugged against rolling and bending. Design principles for compliant substrates include: (a) Moving the circuit plane as close as possible to the neutral plane of the structure, and (b) Using substrate and encapsulation materials with low stiffness. Design principle (a) is demonstrated on thin-film transistors made on thin steel foil. Such transistors function well after the foils are rolled to small radii of curvature. Principle (b) of compliant substrates is demonstrated with bending experiments of a-Si:H TFTs made on thin substrates of polyimide foil. TFTs on 25-mu m thick polyimide foil may be bent to radii of curvature as low as 0.5 mm without failing. The reduction in bending radius, from R similar to 2 mm on same-thickness steel foil, agrees with the theoretical prediction that changing from a stiff to a compliant substrate reduces the bending strain in the device plane by a factor of up to 5.

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Wagner S, Gleskova H, Ma EY, Suo Z. Compliant substrates for thin-film transistor backplanes. In Gnade B, Kelley EF, editors, Flat panel display technology and display meterology . Bellingham, WA. 1999. p. 32-39. (Proceedings of the Society of Photo-Optical Insturmentation Engineers (SPIE)). https://doi.org/10.1117/12.344653