Resin composition for laser processing

Abstract

A resin composition for laser processing which is able to enhance laser processability with maintaining a resist performance of a resin after ultraviolet laser processing, and which can be, for example, used as a resist in forming a circuit of a printed wiring board is provided. Disclosed is a resin composition for laser processing containing a resin and an ultraviolet absorber, wherein the resin is a thermoplastic resin having a carboxyl group and having a softening temperature of from 70 to 140 C., and a content of the ultraviolet absorber is from 1 to 30 parts by mass based on 100 parts by mass of the thermoplastic resin.

Claims

1. A resin composition for laser processing comprising a thermoplastic resin and an ultraviolet absorber, wherein the thermoplastic resin is a copolymer composed of (meth)acrylic acid and styrene and/or an alkyl (meth)acrylate, said thermoplastic resin further having a softening temperature of from 70 to 140 C. and having an acid value of from 100 to 300 mgKOH/g, and a content of the ultraviolet absorber is from 1 to 30 parts by mass based on 100 parts by mass of the thermoplastic resin.

2. The resin composition for laser processing according to claim 1, wherein the ultraviolet absorber has an absorption wavelength of from 200 to 380 nm.

3. The resin composition for laser processing according to claim 1, further comprising a plasticizer wherein a content of the plasticizer is from 1 to 30 parts by mass based on 100 parts by mass of the thermoplastic resin.

4. A resin film for laser processing, which is obtained by coating the resin composition for laser processing according to claim 1 on a support, followed by drying.

5. The resin composition for laser processing according to clam 2, further comprising a plasticizer wherein a content of the plasticizer is from 1to 30 parts by mass based on 100 parts by mass of the thermoplastic resin.

6. A resin film for laser processing, which is obtained by coating the resin composition for laser processing according to claim 2 on a support, followed by drying.

7. A resin film for laser processing, which is obtained by coating the resin composition for laser processing according to claim 3 on a support, followed by drying.

Description

EXAMPLES

(1) Although the present invention is more specifically described below by reference to the Examples, it should not be construed that the present invention is limited to the following Examples. It is to be noted that in the following, the term part means part by mass unless otherwise indicated.

Synthesis Examples

(2) (Thermoplastic Resin A-1)

(3) In a reaction apparatus equipped with a stirrer, a thermometer, a reflux condenser, a dropping device, and a nitrogen inlet tube, a nitrogen gas was enclosed, and thereafter, 120 parts of methyl isobutyl ketone, 30 parts of isopropyl alcohol, 27 parts of acrylic acid, 55 parts of styrene, 18 parts of 2-ethylhexyl acrylate, and 2,2-azobisisobutyronitrile (a trade name: V-60, manufactured by Wako Pure Chemical Industries, Ltd.) which is an azo-based polymerization initiator were charged. The contents were polymerized in a nitrogen gas stream with stirring at 80 C. for 12 hours, thereby obtaining a thermoplastic resin A-1. The obtained thermoplastic resin A-1 was found to have a weight average molecular weight (measured by GPC, hereinafter the same) of 30,000 and a softening temperature (measured by a flow tester, hereinafter the same) of 108 C.

(4) (Thermoplastic Resin A-2)

(5) In a reaction apparatus equipped with a stirrer, a thermometer, a reflux condenser, a dropping device, and a nitrogen inlet tube, a nitrogen gas was enclosed, and thereafter, 58 parts of methyl isobutyl ketone, 14 parts of isopropyl alcohol, 27 parts of acrylic acid, 55 parts of styrene, 18 parts of 2-ethylhexyl acrylate, and 2,2-azobisisobutyronitrile (a trade name: V-60, manufactured by Wako Pure Chemical Industries, Ltd.) which is an azo-based polymerization initiator were charged. The contents were polymerized in a nitrogen gas stream with stirring at 75 C. for 12 hours, thereby obtaining a thermoplastic resin A-2. The obtained thermoplastic resin A-2 was found to have a weight average molecular weight of 50,000 and a softening temperature of 104 C.

(6) (Thermoplastic Resin A-3)

(7) In a reaction apparatus equipped with a stirrer, a thermometer, a reflux condenser, a dropping device, and a nitrogen inlet tube, a nitrogen gas was enclosed, and thereafter, 120 parts of methyl isobutyl ketone, 30 parts of isopropyl alcohol, 27 parts of acrylic acid, 39 parts of styrene, 34 parts of 2-ethylhexyl acrylate, and 2,2-azobisisobutyronitrile (a trade name: V-60, manufactured by Wako Pure Chemical Industries, Ltd.) which is an azo-based polymerization initiator were charged. The contents were polymerized in a nitrogen gas stream with stirring at 80 C. for 12 hours, thereby obtaining a thermoplastic resin A-3. The obtained thermoplastic resin A-3 was found to have a weight average molecular weight of 30,000 and a softening temperature of 86 C.

(8) (Thermoplastic Resin A-4)

(9) In a reaction apparatus equipped with a stirrer, a thermometer, a reflux condenser, a dropping device, and a nitrogen inlet tube, a nitrogen gas was enclosed, and thereafter, 120 parts of methyl isobutyl ketone, 30 parts of isopropyl alcohol, 33 parts of acrylic acid, 67 parts of styrene, and 2,2-azobisisobutyronitrile (a trade name: V-60, manufactured by Wako Pure Chemical Industries, Ltd.) which is an azo-based polymerization initiator were charged. The contents were polymerized in a nitrogen gas stream with stirring at 75 C. for 12 hours, thereby obtaining a thermoplastic resin A-4. The obtained thermoplastic resin A-4 was found to have a weight average molecular weight of 40,000 and a softening temperature of 101 C.

(10) (Thermoplastic Resin A-5)

(11) In a reaction apparatus equipped with a stirrer, a thermometer, a reflux condenser, a dropping device, and a nitrogen inlet tube, a nitrogen gas was enclosed, and thereafter, 120 parts of methyl isobutyl ketone, 30 parts of isopropyl alcohol, 27 parts of acrylic acid, 39 parts of styrene, 34 parts of butyl acrylate, and 2,2-azobisisobutyronitrile (a trade name: V-60, manufactured by Wako Pure Chemical Industries, Ltd.) which is an azo-based polymerization initiator were charged. The contents were polymerized in a nitrogen gas stream with stirring at 80 C. for 12 hours, thereby obtaining a thermoplastic resin A-5. The obtained thermoplastic resin A-5 was found to have a weight average molecular weight of 30,000 and a softening temperature of 86 C.

(12) (Thermoplastic Resin A-6)

(13) In a reaction apparatus equipped with a stirrer, a thermometer, a reflux condenser, a dropping device, and a nitrogen inlet tube, a nitrogen gas was enclosed, and thereafter, 120 parts of methyl isobutyl ketone, 30 parts of isopropyl alcohol, 32 parts of methacrylic acid, 39 parts of styrene, 29 parts of butyl methacrylate, and 2,2-azobisisobutyronitrile (a trade name: V-60, manufactured by Wako Pure Chemical Industries, Ltd.) which is an azo-based polymerization initiator were charged. The contents were polymerized in a nitrogen gas stream with stirring at 80 C. for 12 hours, thereby obtaining a thermoplastic resin A-6. The obtained thermoplastic resin A-6 was found to have a weight average molecular weight of 30,000 and a softening temperature of 118 C.

Examples and Comparative Examples

(14) The above-described thermoplastic resin A-1, A-2, A-3, A-4, A-5 or A-6, 2-(2H-benzotriazol-2-yl)-6-dodecyl-4-methylphenol (a trade name: TINUVIN 571, manufactured by BASF, maximum absorption wavelength: 344 nm) as an ultraviolet absorber B, and trixylenyl phosphate (a trade name: TXP, manufactured by Daihachi Chemical Industry Co., Ltd.) as a plasticizer C-1, bis(2-ethylhexyl) phthalate (a trade name: DOP, manufactured by Daihachi Chemical Industry Co., Ltd.) as a plasticizer C-2, bis(2-ethylhexyl) adipate (a trade name: DOA, manufactured by Daihachi Chemical Industry Co., Ltd.) as a plasticizer C-3, or tris(2-ethylhexyl) trimellitate (a trade name: TOTM, manufactured by Daihachi Chemical Industry Co., Ltd.) as a plasticizer C-4 were blended, respectively in a composition shown in Table 1, thereby preparing resin compositions for laser processing of the Examples and Comparative Examples. The obtained resin compositions for laser processing were measured and evaluated in the following manners. The evaluation results are shown in Table 1.

(15) <Softening Temperature>

(16) The softening temperature was measured by using a flow tester, manufactured by Shimadzu Corporation.

(17) <Laser Processability>

(18) The above-obtained resin composition for laser processing (resist composition) was coated on a surface of an epoxy-based insulating resin base material having a thickness of 100 m, thereby forming a coating having a film thickness after drying of 5 m. Then, the insulating resin base material having a coating formed thereon was subjected to groove formation processing with a substantially rectangular cross section having a width of 20 m and a depth of 30 m by means of laser processing, and an exposed state of the surface of the insulating resin base material and a state of the circuit groove were observed by an SEM (scanning electron microscope) and evaluated according to the following criteria. It is to be noted that a UV-YAG laser was used for the laser processing.

(19) A: Exposure of the insulating resin base material is not observed, and a residue of the resist resin does not exist in the circuit groove.

(20) B: Exposure of the insulating resin base material is observed, or a residue of the resist resin exists in the circuit groove.

(21) <Rising Rate of Resist Resin Coating>

(22) A film thickness (m) of the resist resin coating was measured before and after the laser processing, respectively, and a rising rate was determined according to the following equation.
Rising rate=(Film thickness of resist resin after laser processing)/(Film thickness of resist resin before laser processing)
<Resistance to Plating Chemicals>

(23) The above-described insulating resin base material having a groove formed thereon was dipped in a cleaner conditioner (surfactant solution, a trade name: C/N3320, manufactured by Rohm and Haas Electronic Materials LLC, pH: lower than 1) and then washed with water. Subsequently, a soft etching treatment with a sodium persulfate-sulfuric acid-based soft etching agent (pH: lower than 1) was carried out. Subsequently, a pre-dipping treatment with PD404 (manufactured by Shipley Far East Ltd., pH: lower than 1) was carried out. Subsequently, by dipping in an acidic Pd-Sn colloid solution containing stannous chloride and palladium chloride (a trade name: CAT44, manufactured by Shipley Far East Ltd., pH: 1), palladium serving as a nucleus of electroless copper plating was adsorbed in a state of the tin-palladium colloid on the insulating resin base material. Subsequently, by dipping in an accelerator chemical liquid (a trade name: ACC19E, manufactured by Shipley Far East Ltd., pH: lower than 1), a palladium nucleus was generated. Thereafter, the surface of the insulating resin base material was observed through visual inspection, and a state of the resist resin was evaluated according to the following criteria.

(24) A: Neither separation nor cracking of the resist resin was generated.

(25) B: Separation or cracking of the resist resin was generated.

(26) <Alkali Developability>

(27) The insulating resin base material having a palladium nucleus generated therein was subjected to resist separation by spraying a 3% sodium hydroxide aqueous solution at 30 C., and a state of the separation was evaluated according to the following criteria.

(28) A: A residue of the resist resin does not exist on the insulating resin base material.

(29) B: A residue of the resist resin exists on the insulating resin base material.

(30) <Plating Formability>

(31) The insulating resin base material from which the resist had been separated was subjected to an electroless copper plating treatment by dipping in an electroless plating solution (a trade name: CM328A, CM328L, CM328C, manufactured by Shipley Far East Ltd.), thereby precipitating an electroless copper-plated film having a film thickness of from 3 to 5 m. Thereafter, the surface of the insulating resin base material was observed, and a formation state of the plated film was evaluated according to the following criteria.

(32) A: A plated film was formed in only a cutting-processed portion.

(33) B: A plated film was also formed in other portions than a cutting-processed portion, or a plated film was not formed in a cutting-processed portion.

(34) TABLE-US-00001 TABLE 1 Ultraviolet Thermoplastic resin absorber Plasticizer A-1 A-2 A-3 A-4 A-5 A-6 B C-1 C-2 C-3 C-4 Example 1 100 1 Example 2 100 5 Example 3 100 10 Example 4 100 30 Example 5 100 10 10 Example 6 100 10 10 Example 7 100 10 10 Example 8 100 10 20 Example 9 100 10 20 Example 10 100 10 20 Example 11 100 10 20 Example 12 100 10 20 Example 13 100 10 20 Example 14 100 10 20 Comparative 100 Example 1 Comparative 100 0.1 Example 2 Comparative 100 30 Example 3 Comparative 100 Example 4 Comparative 100 30 Example 5 Softening Rising temperature rate Resistance of of to compotition Laser resist plating Alkali Plating ( C.) processablitiy resin chemicals developability formability Example 1 107 A 1.5 A A A Example 2 102 A 1.2 A A A Example 3 94 A 1.2 A A A Example 4 81 A 1.0 A A A Example 5 83 A 1.3 A A A Example 6 65 A 1.3 A A A Example 7 65 A 1.3 A A A Example 8 72 A 1.3 A A A Example 9 69 A 1.4 A A A Example 10 69 A 1.3 A A A Example 11 80 A 1.4 A A A Example 12 70 A 1.3 A A A Example 13 63 A 1.3 A A A Example 14 85 A 1.4 A A A Comparative 108 B 2.1 A B B Example 1 Comparative 106 B 1.8 A B B Example 2 Comparative 73 B 2.0 A B B Example 3 Comparative 104 B 2.3 A B B Example 4 Comparative 69 B 2.2 A B B Example 5

(35) As is noted from the results shown in Table 1, it could be confirmed that in the resin composition for laser processing of the present invention, by adding an ultraviolet absorber to a thermoplastic resin having a softening temperature of from 70 C. to 140 C., it is possible to conspicuously enhance laser processability with maintaining a resist performance after laser processing.

INDUSTRIAL APPLICABILITY

(36) Since the resin composition of the present invention is able to enhance laser processability of the resin with maintaining a resist performance, it is useful as a resist to be used at the time of forming a circuit of a printed wiring board using a laser.