Flexible board
First Claim
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1. A method of forming a flexible board, comprising:
- forming a first polyimide precursor film over a metal foil, the first polyimide precursor film having a content of residual volatile fractions within the range of 20 to 30 wt %;
forming a second polyimide precursor film over the first polyimide precursor film, the second polyimide precursor film having a content of residual volatile fractions within the range of 30 to 50 wt %;
forming a third polyimide precursor film over the second polyimide precursor film, the third polyimide precursor film having a content of residual volatile fractions within the range of 30 to 50 wt %; and
heat treating the first polyimide precursor film, the second polyimide precursor film and the third polyimide precursor film at a temperature of 210°
C. to 250°
C. to set the content of residual volatile fractions of the first polyimide precursor film, the second polyimide precursor film and the third polyimide precursor film at 7 to 10 wt % and to bring the imidation ratio of the first polyimide precursor film, the second polyimide precursor film and the third polyimide precursor film to 50% or lower, to form a corresponding first polyimide-based layer, second polyimide-based layer and third polyimide-based layer, wherein said flexible board satisfies the equation
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Abstract
A flexible board comprises metal foil 1 and provided thereon a laminated polyimide-based resin layer 2 of a three-layer structure comprising a first polyimide-based resin layer 2a, a second polyimide-based resin layer 2b, and a third polyimide-based resin layer 2c, wherein the following equation is satisfied.
where k1 is the coefficient of linear thermal expansion of the first polyimide-based resin layer 2a on the side of the metal foil 1, k2 is the coefficient of linear thermal expansion of the second polyimide-based resin layer 2b, and k3 is the coefficient of linear thermal expansion of the third polyimide-based resin layer 2c.
30 Citations
5 Claims
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1. A method of forming a flexible board, comprising:
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forming a first polyimide precursor film over a metal foil, the first polyimide precursor film having a content of residual volatile fractions within the range of 20 to 30 wt %;
forming a second polyimide precursor film over the first polyimide precursor film, the second polyimide precursor film having a content of residual volatile fractions within the range of 30 to 50 wt %;
forming a third polyimide precursor film over the second polyimide precursor film, the third polyimide precursor film having a content of residual volatile fractions within the range of 30 to 50 wt %; and
heat treating the first polyimide precursor film, the second polyimide precursor film and the third polyimide precursor film at a temperature of 210°
C. to 250°
C. to set the content of residual volatile fractions of the first polyimide precursor film, the second polyimide precursor film and the third polyimide precursor film at 7 to 10 wt % and to bring the imidation ratio of the first polyimide precursor film, the second polyimide precursor film and the third polyimide precursor film to 50% or lower, to form a corresponding first polyimide-based layer, second polyimide-based layer and third polyimide-based layer,wherein said flexible board satisfies the equation - View Dependent Claims (2, 3, 4, 5)
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Current AssigneeSony Chemicals Corp. (Dexerials Corporation)
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Original AssigneeSony Chemicals Corp. (Dexerials Corporation)
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InventorsTakahashi, Satoshi, Namiki, Hidetsugu
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Primary Examiner(s)NAKARANI, DHIRAJLAL S
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Application NumberUS09/456,440Time in Patent Office797 DaysField of Search428/209, 428/213, 428/458, 428/473.5, 428/901, 427/96, 427/409US Class Current427/409CPC Class CodesH05K 1/0346 containing NH05K 1/036 Multilayers with layers of ...H05K 2201/0154 PolyimideH05K 2201/068 wherein the coefficient of ...Y10T 428/31681 Next to polyester, polyamid...Y10T 428/31721 Of polyimide
