Pressure sensitive adhesive composition and sheet having layer thereof

• US 5,955,512 A
• Filed: 04/24/1997
• Issued: 09/21/1999
• Est. Priority Date: 04/26/1996
• Status: Expired due to Term

• Current Assignee: Lintec Corporation
• Original Assignee: Lintec Corporation
• Inventors: Mineura, Yoshihisa, Numazawa, Hideki
• Primary Examiner(s): GORR, RACHEL F
• Application Number:
  US08/847,560
• Time in Patent Office: 880 Days
• Field of Search: 522/95, 522/96, 522/117, 428/343, 428/345, 428/355 EN, 428/355 N, 528/75
• US Class Current: 522/95
• CPC Class Codes: C08G 2170/40 Compositions for pressure-sensitive adhesives
• CPC Class Codes: C08L 33/00 Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides or nitriles thereof; Compositions of derivatives of such polymers
• CPC Class Codes: C09J 175/16 having terminal carbon-to-carbon unsaturated bonds
• CPC Class Codes: Y10T 428/28 Web or sheet containing structurally defined element or component and having an adhesive outermost layer
• CPC Class Codes: Y10T 428/2809 including irradiated or wave energy treated component
• CPC Class Codes: Y10T 428/2878 including addition polymer from unsaturated monomer
• CPC Class Codes: Y10T 428/2896 including nitrogen containing condensation polymer [e.g., polyurethane, polyisocyanate, etc.]

Abstract

A pressure sensitive adhesive composition is disclosed which comprises an acrylic copolymer (A), an energy beam polymerizable urethane acrylate oligomer (B) and an energy beam polymerizable compound having one acryloyl group or methacryloyl group in each molecule thereof (C). This composition is preferred to further contain a plasticizer (D), a crosslinking agent (E) and/or a photopolymerization initiator (F) according to necessity. The pressure sensitive adhesive composition has satisfactory pressure sensitive adherence and initial adhesion before the irradiation with energy beam and the adhesive strength thereof is sharply reduced with maintaining the rubber elasticity after the irradiation with energy beam. Further, the pressure sensitive adhesive composition ensures excellent chip alignability in the expanding step subsequent to dicing. The pressure sensitive adhesive composition provides a pressure sensitive adhesive sheet, especially, a wafer processing pressure sensitive adhesive sheet or a surface protective pressure sensitive adhesive sheet.

Claims

1. A pressure sensitive adhesive composition, comprising:

an acrylic copolymer (A) having a molecular weight of at least 200,000;

an energy beam polymerizable urethane acrylate oligomer (B); and

an energy beam polymerizable compound having one acryloyl group or methacryloyl group in each molecule thereof (C), wherein the composition is tacky before an energy beam irradiation and the composition becomes non-tacky after the energy beam irradiation.

2. The pressure sensitive adhesive composition as claimed in claim 1, which further comprises a plasticizer (D).

3. The pressure sensitive adhesive composition as claimed in claim 1, which further comprises a crosslinking agent (E).

4. The pressure sensitive adhesive composition as claimed in claim 1, which further comprises a photopolymerization initiator (F).

11. The pressure sensitive adhesive composition as claimed in claim 2, which further comprises a crosslinking agent (E).

12. The pressure sensitive adhesive composition as claimed in claim 2, which further comprises a photopolymerization initiator (F).

13. The pressure sensitive adhesive composition as claimed in claim 3, which further comprises a photopolymerization initiator (F).

14. The pressure sensitive adhesive composition of claim 1, wherein the composition has an adhesive strength to a specular surface of semiconductor wafer ranging from 100 to 2000 g/25 mm before the energy beam irradiation, and wherein the adhesive strength is controllable, such that an adhesive strength after the energy beam irradiation is about 1 to 50% of said adhesive strength before the energy beam irradiation.

5. A pressure sensitive adhesive sheet, comprising:

a substrate and, formed thereon, a pressure sensitive adhesive layer having a pressure sensitive adhesive composition, comprising;

an acrylic copolymer (A) having a molecular weight of at least 200,000;

an energy beam polymerizable urethane acrylate oligomer (B); and

an energy polymerizable compound having one acryloyl group or methacryloyl group in each molecule thereof (C), wherein the pressure sensitive layer is tacky before an energy beam irradiation and the composition becomes non-tacky after the energy beam irradiation.

6. A pressure sensitive adhesive sheet according to claim 5 in which the pressure sensitive adhesive composition further comprises a plasticizer (D).

7. A pressure sensitive adhesive sheet according to claim 5 in which the pressure sensitive adhesive composition further comprises a crosslinking agent (E).

8. A pressure sensitive adhesive sheet according to claim 5 in which the pressure sensitive adhesive composition further comprises a photopolymerization initiator (F).

9. A pressure sensitive adhesive sheet according to claim 5 in which the pressure sensitive adhesive composition further comprises a plasticizer (D) and a crosslinking agent (E).

10. A pressure sensitive adhesive sheet according to claim 5 in which the pressure sensitive adhesive composition further comprises a plasticizer (D), a crosslinking agent (E) and a photopolymerization initiator (F).

15. The pressure sensitive adhesive sheet as claimed in claim 5, wherein the adhesive layer has an adhesive strength to a specular surface of semiconductor wafer ranging from 100 to 2000 g/25 mm before the energy beam irradiation, and wherein the adhesive strength is controllable such that an adhesive strength after the energy beam irradiation is about 1 to 50% of said adhesive strength before the energy beam irradiation.