Mechanical durability of flexible printed circuit boards containing thin coverlays fabricated with poly(Amide-imide-urethane)/epoxy interpenetrating networks

Jeongah Kim; Bo Young Kim; Seong Dae Park; Ji Hun Seo; Chan Jae Lee; Myong Jae Yoo; Youngmin Kim

doi:10.3390/mi12080943

Mechanical durability of flexible printed circuit boards containing thin coverlays fabricated with poly(Amide-imide-urethane)/epoxy interpenetrating networks

Jeongah Kim, Bo Young Kim, Seong Dae Park, Ji Hun Seo, Chan Jae Lee, Myong Jae Yoo, Youngmin Kim

Research output: Contribution to journal › Article › peer-review

6 Citations (Scopus)

Abstract

Because electronics are becoming flexible, the demand for techniques to manufacture thin flexible printed circuit boards (FPCBs) has increased. Conventional FPCBs are fabricated by attaching a coverlay film (41 μm) onto copper patterns/polyimide (PI) film to produce the structure of coverlay/Cu patterns/PI film. Given that the conventional coverlay consists of two layers of polyimide film and adhesive, its thickness must be reduced to generate thinner FPCBs. In this study, we fabricated 25-μm-thick poly(amide-imide-urethane)/epoxy interpenetrating networks (IPNs) to re-place the thick conventional coverlay. Poly(amide-imide-urethane) (PAIU) was synthesized by re-acting isocyanate-capped polyurethane with trimellitic anhydride and then mixed with epoxy resin to produce PAIU/epoxy IPNs after curing. Thanks to the soft segments of polyurethane, the elongation of PAIU/epoxy IPNs increased with increasing PAIU content and reached over 200%. After confirming the excellent thermal stability and chemical resistance of the PAIU/epoxy IPNs, we fabricated FPCBs by equipping them as coverlays. The mechanical durability of the FPCBs was evaluated through an MIT folding test, and the FPCB fabricated with PAIU/ep-2 was stable up to 164 folding cycles because of the balanced mechanical properties.

Original language	English
Article number	943
Journal	Micromachines
Volume	12
Issue number	8
DOIs	https://doi.org/10.3390/mi12080943
Publication status	Published - 2021 Aug

Bibliographical note

Funding Information:
Funding: This work was supported by the Ministry of Trade, Industry & Energy (MOTIE, Korea) [grant number 20006472, Development of design responsive inkjet/aero-soljet fusion printing technology to implement rigid flex PCB with high resolution line width 30 um space 40 um for 5G mobile communication devices].

Publisher Copyright:
© 2021 by the authors. Licensee MDPI, Basel, Switzerland.

Keywords

Coverlay
Flexible printed circuit boards
Interpenetrating network
MIT folding test
Poly(amide-imide-urethane)

ASJC Scopus subject areas

Control and Systems Engineering
Mechanical Engineering
Electrical and Electronic Engineering

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10.3390/mi12080943

Cite this

@article{46a003b70cb34e3486909223e136f831,

title = "Mechanical durability of flexible printed circuit boards containing thin coverlays fabricated with poly(Amide-imide-urethane)/epoxy interpenetrating networks",

abstract = "Because electronics are becoming flexible, the demand for techniques to manufacture thin flexible printed circuit boards (FPCBs) has increased. Conventional FPCBs are fabricated by attaching a coverlay film (41 μm) onto copper patterns/polyimide (PI) film to produce the structure of coverlay/Cu patterns/PI film. Given that the conventional coverlay consists of two layers of polyimide film and adhesive, its thickness must be reduced to generate thinner FPCBs. In this study, we fabricated 25-μm-thick poly(amide-imide-urethane)/epoxy interpenetrating networks (IPNs) to re-place the thick conventional coverlay. Poly(amide-imide-urethane) (PAIU) was synthesized by re-acting isocyanate-capped polyurethane with trimellitic anhydride and then mixed with epoxy resin to produce PAIU/epoxy IPNs after curing. Thanks to the soft segments of polyurethane, the elongation of PAIU/epoxy IPNs increased with increasing PAIU content and reached over 200%. After confirming the excellent thermal stability and chemical resistance of the PAIU/epoxy IPNs, we fabricated FPCBs by equipping them as coverlays. The mechanical durability of the FPCBs was evaluated through an MIT folding test, and the FPCB fabricated with PAIU/ep-2 was stable up to 164 folding cycles because of the balanced mechanical properties.",

keywords = "Coverlay, Flexible printed circuit boards, Interpenetrating network, MIT folding test, Poly(amide-imide-urethane)",

author = "Jeongah Kim and Kim, {Bo Young} and Park, {Seong Dae} and Seo, {Ji Hun} and Lee, {Chan Jae} and Yoo, {Myong Jae} and Youngmin Kim",

note = "Funding Information: Funding: This work was supported by the Ministry of Trade, Industry & Energy (MOTIE, Korea) [grant number 20006472, Development of design responsive inkjet/aero-soljet fusion printing technology to implement rigid flex PCB with high resolution line width 30 um space 40 um for 5G mobile communication devices]. Publisher Copyright: {\textcopyright} 2021 by the authors. Licensee MDPI, Basel, Switzerland.",

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volume = "12",

journal = "Micromachines",

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AU - Seo, Ji Hun

AU - Lee, Chan Jae

AU - Yoo, Myong Jae

AU - Kim, Youngmin

N1 - Funding Information: Funding: This work was supported by the Ministry of Trade, Industry & Energy (MOTIE, Korea) [grant number 20006472, Development of design responsive inkjet/aero-soljet fusion printing technology to implement rigid flex PCB with high resolution line width 30 um space 40 um for 5G mobile communication devices]. Publisher Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland.

PY - 2021/8

Y1 - 2021/8

N2 - Because electronics are becoming flexible, the demand for techniques to manufacture thin flexible printed circuit boards (FPCBs) has increased. Conventional FPCBs are fabricated by attaching a coverlay film (41 μm) onto copper patterns/polyimide (PI) film to produce the structure of coverlay/Cu patterns/PI film. Given that the conventional coverlay consists of two layers of polyimide film and adhesive, its thickness must be reduced to generate thinner FPCBs. In this study, we fabricated 25-μm-thick poly(amide-imide-urethane)/epoxy interpenetrating networks (IPNs) to re-place the thick conventional coverlay. Poly(amide-imide-urethane) (PAIU) was synthesized by re-acting isocyanate-capped polyurethane with trimellitic anhydride and then mixed with epoxy resin to produce PAIU/epoxy IPNs after curing. Thanks to the soft segments of polyurethane, the elongation of PAIU/epoxy IPNs increased with increasing PAIU content and reached over 200%. After confirming the excellent thermal stability and chemical resistance of the PAIU/epoxy IPNs, we fabricated FPCBs by equipping them as coverlays. The mechanical durability of the FPCBs was evaluated through an MIT folding test, and the FPCB fabricated with PAIU/ep-2 was stable up to 164 folding cycles because of the balanced mechanical properties.

AB - Because electronics are becoming flexible, the demand for techniques to manufacture thin flexible printed circuit boards (FPCBs) has increased. Conventional FPCBs are fabricated by attaching a coverlay film (41 μm) onto copper patterns/polyimide (PI) film to produce the structure of coverlay/Cu patterns/PI film. Given that the conventional coverlay consists of two layers of polyimide film and adhesive, its thickness must be reduced to generate thinner FPCBs. In this study, we fabricated 25-μm-thick poly(amide-imide-urethane)/epoxy interpenetrating networks (IPNs) to re-place the thick conventional coverlay. Poly(amide-imide-urethane) (PAIU) was synthesized by re-acting isocyanate-capped polyurethane with trimellitic anhydride and then mixed with epoxy resin to produce PAIU/epoxy IPNs after curing. Thanks to the soft segments of polyurethane, the elongation of PAIU/epoxy IPNs increased with increasing PAIU content and reached over 200%. After confirming the excellent thermal stability and chemical resistance of the PAIU/epoxy IPNs, we fabricated FPCBs by equipping them as coverlays. The mechanical durability of the FPCBs was evaluated through an MIT folding test, and the FPCB fabricated with PAIU/ep-2 was stable up to 164 folding cycles because of the balanced mechanical properties.

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ER -

Mechanical durability of flexible printed circuit boards containing thin coverlays fabricated with poly(Amide-imide-urethane)/epoxy interpenetrating networks

Abstract

Bibliographical note

Keywords

ASJC Scopus subject areas

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