Adhesive composition for flexible printed-wiring board (FPC), and heat-curable resin film, prepreg and FPC substrate containing same

Patent metadata

Field	Value
Publication number	US-12421435-B2
Application number	US-202217696172-A
Country	US
Kind code	B2
Filing date	Mar 16, 2022
Priority date	Mar 25, 2021
Publication date	Sep 23, 2025
Grant date	Sep 23, 2025

Abstract

Provided is an adhesive composition for a flexible printed-wiring board (FPC) that has low dielectric properties, a high adhesion strength to low-dielectric resin films (LCP or MPI) and a copper foil, and an excellent moisture resistance and reflow resistance. This adhesive composition contains:
(A) 100 parts by mass of a maleimide compound having at least two maleimide groups in one molecule, having a number average molecular weight of greater than 4,000, and having at least one divalent organic group selected from a dimer acid skeleton, a linear alkylene group having not less than 6 carbon atoms, and a linear alkenylene group having not less than 6 carbon atoms; (B) 0.1 to 15 parts by mass of an epoxy resin having at least two epoxy groups in one molecule; and (C) 0.1 to 5 parts by mass of a diaminotriazine ring-containing imidazole.

First claim

The invention claimed is:

1. An adhesive composition for a flexible printed-wiring board (FPC: Flexible Printed Circuits), comprising:
(A) 100 parts by mass of a maleimide compound having at least two maleimide groups in one molecule, having a number average molecular weight of greater than 4,000, and having at least one divalent organic group selected from a dimer acid skeleton, a linear alkylene group having not less than 6 carbon atoms, and a linear alkenylene group having not less than 6 carbon atoms, the maleimide compound being represented by the following general formula (1),

wherein A independently represents a tetravalent organic group having an aromatic ring or aliphatic ring represented by any one of the following structures:

wherein bonds in the above structural formulae that are yet unbonded to substituent groups are to be bonded to carbonyl carbons forming maleimide structures in the formula (1),
B represents an alkylene group that has 6 to 18 carbon atoms and an aliphatic ring represented by any one of the following structures:

wherein bonds in the above structural formulae that are yet unbonded to substituent groups are to be bonded to nitrogen atoms forming maleimide structures in the formula (1),
Q independently represents a linear alkylene or linear alkenylene group having 6 to 20 carbon atoms,
R independently represents a linear or branched alkyl group having 6 to 12 carbon atoms,
n represents a number of 2 to 70, m represents a number greater than 0 to 70;
(B) 0.1 to 15 parts by mass of an epoxy resin having at least two epoxy groups in one molecule; and
(C) 0.1 to 5 parts by mass of a diaminotriazine ring-containing imidazole.

2. The adhesive composition for FPC according to claim 1 , further comprising:
(D) an inorganic filler.

3. The adhesive composition for FPC according to claim 2 , wherein the inorganic filler is such an inorganic filler that has been treated with a silane coupling agent having organic groups capable of reacting with the component (A).

4. A cured film obtained by heating the adhesive composition for FPC according to claim 1 , wherein if the composition is heated at 180° C. for two hours, a dielectric tangent measured at 10 GHz under 25° C. is not larger than 0.0040.

5. A heat-curable resin film comprising the adhesive composition for FPC according to claim 1 .

6. A prepreg comprising a semi-cured product of the adhesive composition for FPC according to claim 1 .

7. An FPC substrate comprising a cured product of the adhesive composition for FPC according to claim 1 .

8. The adhesive composition for FPC according to claim 1 , wherein a total content of components (A), (B), and (C) is 41 to 100% by mass to a total mass of the composition.

9. The adhesive composition for FPC according to claim 1 , wherein a content of component (A) is 39 to 99% by mass to a total mass of the composition.

10. A cured film obtained by heating the adhesive composition for FPC according to claim 1 , wherein the cured film has a dielectric tangent measured at 10 GHz under 25° C. is not larger than 0.0040.

11. The adhesive composition for FPC according to claim 1 , wherein the epoxy resin (B) comprises at least one epoxy resin selected from a bisphenol A type epoxy resin, a bisphenol F type epoxy resin, a biphenyl aralkyl type epoxy resin, a glycidylamine type epoxy resin, a dicyclopentadiene type epoxy resin, and an isocyanuric skeleton type epoxy resin.

12. The adhesive composition for FPC according to claim 1 , wherein the diaminotriazine ring-containing imidazole (C) comprises at least one compound selected from 2,4-diamino-6-[2′-methylimidazolyl-(1′)]-ethyl-s-triazine, 2,4-diamino-6-[2′-undecylimidazolyl-(1′)]-ethyl-s-triazine, 2,4-diamino-6-[2′-ethyl-4′ methylimidazolyl-(1′)]-ethyl-s-triazine, and 2,4-diamino-6-[2′-methylimidazolyl-(1′)]-ethyl-s-triazineisocyanuric acid adduct.

13. The adhesive composition for FPC according to claim 1 , wherein the maleimide compound (A) is a member selected from the group consisting of:

14. The adhesive composition for FPC according to claim 13 , wherein the maleimide compound (A) is at least two members selected from the maleimide compounds A represented by the formulas (A-2) and (A-3).

Assignees

• Shinetsu Chemical Co

Inventors

• Tsuura Atsushi
• Tsutsumi Yoshihiro
• Iguchi Hiroyuki
• Kudo Yuki
• Iwasaki Masayuki
• Sasahara Rina

Classifications

• C08K3/36

  Silica · CPC title

• C09J2203/326

  for bonding electronic components such as wafers, chips or semiconductors · CPC title

• H05K1/0373

  containing additives, e.g. fillers (H05K1/036 takes precedence) · CPC title

• C08K9/06

  with silicon-containing compounds · CPC title

• C09J2301/304

  the adhesive being heat-activatable, i.e. not tacky at temperatures inferior to 30°C · CPC title