Copper-clad laminate

• US 6,924,024 B2
• Filed: 07/21/2003
• Issued: 08/02/2005
• Est. Priority Date: 07/19/2002
• Status: Expired due to Fees

• Current Assignee: UBE Industries Limited
• Original Assignee: UBE Industries Limited
• Inventors: Yamamoto, Nobuyuki, Narui, Kohji, Anno, Toshihiko
• Primary Examiner(s): Nakarani, D. S.
• Application Number:
  US10/622,471
• Publication Number:
  US 20040110015A1
• Time in Patent Office: 743 Days
• Field of Search: 156/308.2, 156/309.6, 428/141, 428/450, 428/451, 428/458, 428/473.5
• US Class Current: 428/141
• CPC Class Codes: B32B 15/08 of synthetic resin
• CPC Class Codes: H05K 1/0346 containing N
• CPC Class Codes: H05K 2201/0108 Transparent
• CPC Class Codes: H05K 2201/0129 Thermoplastic polymer, e.g. auto-adhesive layer; Shaping of thermoplastic polymer
• CPC Class Codes: H05K 2201/0154 Polyimide
• CPC Class Codes: H05K 2201/0355 Metal foils
• CPC Class Codes: H05K 3/022 Processes for manufacturing precursors of printed circuits, i.e. copper-clad substrates
• CPC Class Codes: H05K 3/389 by the use of a coupling agent, e.g. silane
• CPC Class Codes: Y10T 428/12438 Composite
• CPC Class Codes: Y10T 428/24355 Continuous and nonuniform or irregular surface on layer or component [e.g., roofing, etc.]
• CPC Class Codes: Y10T 428/31667 Next to addition polymer from unsaturated monomers, or aldehyde or ketone condensation product
• CPC Class Codes: Y10T 428/31681 Next to polyester, polyamide or polyimide [e.g., alkyd, glue, or nylon, etc.]
• CPC Class Codes: Y10T 428/31721 Of polyimide

Abstract

A copper-clad laminate is composed of a copper foil and an aromatic polyimide film placed thereon, in which the copper foil is bonded to the polyimide film at a bonding strength of ≧500 N/m and the polyimide film shows a light transmittance of ≧40% for a light of wavelength of 600 nm and a haze of ≧30% [the light transmittance and haze are values measured after the copper foil is removed by etching].

Claims

1. A copper-clad laminate comprising a copper foil having a surface roughness in terms of Rz of 1 μ

m or less and an aromatic polyimide film placed thereon, wherein the copper foil is bonded to the polyimide film at a bonding strength of 500 N/m or higher and the polyimide film shows a light transmittance of 40% or higher for a light of wavelength of 600 nm and a haze of 30% or higher, the light transmittance and haze being values measured after the copper foil is removed by etching.

2. The copper-clad laminate of claim 1, wherein the polyimide film has a thermoplastic surface at least on one side.

3. The copper-clad laminate of claim 2, wherein the polyimide film comprises a polyimide substrate film having no glass transition temperature at temperatures of lower than 340°

C. and at least one thermoplastic polyimide film placed on the polyimide substrate film, the thermoplastic polyimide film having a glass transition temperature in the range of 180 to 275°

C.

4. The copper-clad laminate of claim 1, which shows a bonding strength of 285 N/m or higher, the bonding strength being measured between the copper foil and the polyimide film after the laminate is kept at 150°

C. for 1,000 hours.

5. The copper-clad laminate of claim 1, which shows a bonding strength of 80% or higher of an initial bonding strength between the copper foil and the polyimide film, the former bonding strength being measured after the laminate is kept at 150°

C. for 1,000 hours.

6. The copper-clad laminate of claim 1, wherein the copper foil has an adhesive surface.

7. The copper-clad laminate of claim 6, wherein the adhesive surface is produced by placing a coupling agent on the copper foil.

8. The copper-clad laminate of claim 6, wherein the coupling agent is a silane-coupling agent.

9. The copper-clad laminate of claim 1, wherein the copper foil is in the form of a continuous film having a gloss of 360% or higher in a longitudinal direction thereof and a gloss of 310% or higher in a width direction thereof, the glosses being measured at an incident angle of 60°

.

10. A process for manufacturing a copper-clad laminate of claim 1, which comprises the steps of:

preparing a copper foil having a surface roughness in terms of Rz of 1 μ

m or less and an adhesive surface and an aromatic polyimide film comprising a polyimide substrate film having no glass transition temperature at temperatures of lower than 340°

C. and at least one thermoplastic polyimide film placed on the polyimide substrate film, the thermoplastic polyimide film having a glass transition temperature in the range of 200 to 275°

C.;

placing the thermoplastic polyimide film of the aromatic polyimide film on the adhesive surface of the copper foil; and

heating the thermoplastic polyimide film and the copper foil at a temperature of higher than the glass transition temperature of the thermoplastic polyimide film but not higher than 400°

C. under pressure.

11. The process of claim 10, wherein the step of heating the thermoplastic polyimide film and the copper foil is performed by means of a double belt press.

12. The process of claim 10, wherein the adhesive surface of the copper foil is produced by placing a coupling agent on the copper foil.

13. A copper-clad laminate comprising a copper layer and an aromatic polyimide film placed thereon, wherein the copper layer is bonded to the polyimide film at a bonding strength of 500 N/m or higher under the condition that the bonding strength after heating at 150°

C. for 1,000 hours is 285 N/m or higher, and the polyimide film shows a light transmittance of 40% or higher for a light of wavelength of 600 nm and a haze of 30% or higher, the light transmittance and haze being values measured after the copper layer is removed by etching.