Low Dk/Df solder resistant composition use for printed circuit board

Abstract

A low dielectric constant (Dk) and dissipation factor (Df) of solder resistant mask composition comprising (A) a photopolymerizable prepolymer of formula (1); (B) a photopolymerizable vinyl monomer; (C) an epoxy compound; (D) a photopolymerization initiator; (E) an inorganic filler; (F) a catalyst; and (G) an organic solvent. The low dielectric constant (Dk) and dissipation factor (Df) of solder resistant mask composition has excellent photo and thermocurability, and high developability resolution with an alkaline aqueous solution, wherein the dielectric constant is below 3.20 (1 GHz), and the dissipation factor is less than 0.015 (1 GHz); ##STR00001## ##STR00002##

Claims

1. A low dielectric constant (Dk)/dissipation factor (Df) solder resistant composition, comprising following components: A) a photopolymerizable prepolymer of formula (1), which is 20 to 70 weight %, wherein the photopolymerizable prepolymer of formula (1) is prepared by reacting (a) an epoxy resin with (b) a mono carboxylic acid including a vinyl group, then reacting with (c) a saturated or unsaturated anhydride; wherein the epoxy resin is (a1) dicyclo pentadiene-phenol novolac multifunctional epoxy, or (a2) polyphenyl ether modified multifunctional epoxy resin or a combination thereof; B) a photopolymerizable vinyl monomer which is 5 to 20 weight % and used as thinner; C) an epoxy compound which is 5 to 30 weight %, the epoxy compound includes (C1) dicyclo pentadiene-phenol novolac multifunctional epoxy resin or polyphenyl ether modified epoxy resin or a combination thereof, and (C2) tetra methyl biphenol epoxy resin; D) a photopolymerization initiator which is 2 to 10 weight %; E) an inorganic filler which is 10 to 50 weight %; F) a catalyst or accelerant which is 0 to 2.0 weight %; G) an organic solvent which is 10 to 40 weight %; ##STR00006## wherein the low dielectric constant (Dk)/dissipation factor (Df) solder resistant composition has the dielectric constant Dk less than 3.20 (1 GHz) and the dissipation factor Df less than 0.015 (1 GHz).

2. The composition as claimed in claim 1, wherein the photopolymerizable prepolymer of formula (1) of the component A is 30-60 weight %.

3. The composition as claimed in claim 1, wherein the (c) saturated anhydride of the components (A) is selected from the group consisting of succinic anhydride, maleic anhydride, hexahydrophthalic anhydride, cis-4-methyl-1,2,3,6-tetrahydrophthalic anhydride, and 2,3,6-tetrahydro-3-phthalic anhydride.

4. The composition as claimed in claim 1, wherein the amount of the component (B) photopolymerizable vinyl monomer is 5 to 15 weight % and the component (B) is selected from the group consisting of 2-hydroxyethyl acrylate, 2-hydroxybutyl acrylate, alkyl amine acrylic acid compound, multifunctional acrylate of propylene oxide, acrylate of allyl glycidyl ether, and multifunctional acrylate of dipentaerythritol.

5. The composition as claimed in claim 1, wherein the amount of the component (C) epoxy resin compound is 10 to 25 weight %, and the epoxy resin compound is selected from (C1) dicyclo pentadiene-phenol novolac multifunctional epoxy resin or polyphenyl ether modified epoxy resin or a combination of the above-mentioned two epoxy resins; and (C2) tetramethyl biphenol epoxy resin.

6. The composition as claimed in claim 1, wherein the amount of the component (D) photopolymerization initiator is 2 to 8 weight %, and the photopolymerization initiator is selected from the group consisting of benzoin methyl ether, benzoin, isopropyl ether, 2,2-dimethyl-2-phenyl acetophenone, 1,1-dichloroacetophenone, 1-hydroxy cyclohexyl phenyl ketone, 2-methyl-1-[4-(methylthio) phenyl]-2-morpholinylacet-1-one, N,N-dimethyl amino acetophenone, benzophenone dimethyl acetal, diphenylketone, methyl diphenylketone, 4,4-dichlorobenzophenone, 4,4-diethylamino phenyl ketone, Michler's ketone, and 4-phenylmethylacyldiphenyl phosphorus oxide.

7. The composition as claimed in claim 1, wherein the amount of the component (E) inorganic filler is 15 to 35 weight %, and the inorganic filler is selected from the group consisting of talcum powder, magnesium carbonate, calcium carbonate, alumina and powder of silicon dioxide.

8. The composition as claimed in claim 1, wherein the amount of the component (F) catalyst or accelerant is 0.1 to 1.0 weight %, and the catalyst or accelerant is selected from the group consisting of imidazoles, quaternary ammonium compounds, quaternary phosphates, and dimethyl imidazole, diphenylimidazole, and bis(hydroxymethyl) diphenylimidazole.

9. The composition as claimed in claim 1, wherein the amount of the component (G) organic solvent is 10 to 30 weight %, and the organic solvent is selected from the group consisting of propylene carbonate, butoxyethanol, butoxyethyl acetate, methylbenzene, dimethylbenzene, butyl carbitol acetate, cyclohexanone, propylene glycol monomethyl ether, dipropylene glycol diethyl ether, and methyl carbitol acetate.

Description

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

(1) The preferable specific embodiment shall be clarified further in order to understand the invention more clearly, and explanations shall be detailed according to following embodiments.

Synthesis Example 1: Photopolymerizable Prepolymer (Oligomer)-A1

(2) Add 390 g solvent KA to 1000 g dicyclo pentadiene-phenol novolac multifunctional epoxy resin (produced by Nan Ya Plastics Corporation, with trademark NPPN-272H and equivalent of epoxy EEW of 272 g/eq); add 4.5 g triphenyl phosphine and 1.0 g hydroquinone HQ after heating the mixture to 100 C., stir and dissolve the mixture and drop 265 g acrylic acid AA to the above-mentioned solution to carry out reaction, wherein the reaction time during dropping shall be 90 min; the temperature during dropping shall be at 95 C.; implement ripening reaction for 12 h by heating the mixture to 120 C. after dropping; add 380 g tetrahydrophthalic anhydride THPA and 390 g solvent I-150 when the acid value of analysis is less than 1 mgKOH/g and implement reaction 5 h when the temperature is at 110 C.; then add 55 g solvent KA and 55 g I-150 to dilute until the solid content is 65% to obtain the photopolymerizable prepolymer (oligomer) A1 with acid value of analysis of 60 mgKOH/g and weight average molecular weight Mw of 1839.

Synthesis Example 2: Photopolymerizable Prepolymer (Oligomer)-A2

(3) Add 378 g solvent KA to 1000 g polyphenyl ether modified benzaldehyde novolac multifunctional epoxy resin (produced by Nan Ya Plastics Corporation, with trademark NPPN-433P and EEW of 316 g/eq); add 4.0 g triphenyl phosphine and 1.0 g hydroquinone HQ after heating the mixture to 100 C., stir and dissolve the mixture and drop 227 g acrylic acid AA to the above-mentioned solution to carry out reaction, wherein the time of dropping shall be 90 min; the temperature during dropping shall be at 95 C.; implement ripening reaction for 12 h after dropping and reaction for 5 h after adding 327 g tetrahydrophthalic anhydride THPA and 378 g solvent I-150 when the temperature is at 110 C.; then add 41 g solvent KA and 41 g I-150 to dilute until the solid content is 65% to obtain the photopolymerizable prepolymer (oligomer) A2 with acid value of analysis of 77 mgKOH/g and weight average molecular weight Mw of 1872.

Synthesis Example 3: Photopolymerizable Prepolymer (Oligomer)-A3

(4) Add 405 g solvent KA to 1000 g phenol-benzaldehyde novolac multifunctional epoxy resin (produced by Nan Ya Plastics Corporation, with trademark NPPN-433 and EEW of 230 g/eq); add 5.4 g triphenyl phosphine and 1.0 g hydroquinone HQ after heating the mixture to 100 C., stir and dissolve the mixture and drop 312 g acrylic acid AA to the above-mentioned solution to carry out reaction, wherein the reaction time of dropping shall be 90 min; the temperature during dropping shall be at 95 C.; implement ripening reaction for 12 h by heating the mixture to 120 C. after dropping; carry out reaction for 5 h after adding 450 g tetrahydrophthalic anhydride THPA and 405 g solvent I-150 when the temperature is at 110 C.; then add 71 g solvent KA and 71 g I-150 to dilute until the solid content is 65% to obtain the photopolymerizable prepolymer (oligomer) A3 with acid value of analysis of 59 mgKOH/g and weight average molecular weight Mw of 2267.

Comparison Example: Photopolymerizable Prepolymer (Oligomer)-A4

(5) Add 392 g solvent KA to 1000 g o-cresol phenolic multifunctional epoxy resin (produced by Nan Ya Plastics Corporation, with trademark NPPN-704 and EEW of 210 g/eq); add 6.0 g triphenyl phosphine and 1.2 g hydroquinone HQ after heating the mixture to 100 C., stir and dissolve the mixture and drop 342 g acrylic acid AA to the above-mentioned solution to carry out reaction, wherein the time of dropping shall be 90 min: the temperature during dropping shall be at 95 C.; implement ripening reaction for 12 h after dropping and reaction for 4 h after adding 384 g tetrahydrophthalic anhydride THPA and 392 g solvent I-150 when the temperature is at 110 C.; then add 128 g solvent KA and 128 g I-150 to dilute until the solid content is 62.5% to obtain the photopolymerizable prepolymer (oligomer) A4 with acid value of analysis of 51 mgKOH/g and weight average molecular weight Mw of 6000.

Examples 14

(6) The low Dk/Df photopolymerizable prepolymer (oligomer) of the invention can be substituted into the formula of the solder resistant composition with components detailed in Table 1, and the photoresist ink composition can be acquired after grinding comprehensively by using SAMBON roller grinding machine. The printed circuit board of 20-30 m thickness can be acquired after coating the photoresist ink composition acquired by the method onto the copper printed circuit board having patterns by using the printing method in presence of screen. The membrane can be adhered to the coating by using the negative coating having photoresist patterns closely after drying for 30 min by using the hot air drier at 80 C., and irradiated by ultraviolet light with dosage of 25 mW/square centimeter by using the ultraviolet exposure device (of HMW-680GW type produced by ORC Company). Then the part not exposed can be dissolved and eliminated by developing for 60 s in presence of spraying pressure of 2.0 kg/square centimetre of 1% aqueous solution of sodium carbonate. Of course, the aqueous solutions of weak base of other types can also be used. Finally, the membrane hardened completely can be acquired after baking 0.5-1 h at 100-200 C. in order to increase the heat resistant performance.

Comparison Example 1

(7) The comparison example involves that substitution of the common photopolymerizable prepolymer (oligomer) into the formula of the solder resistant composition, and the formula is detailed in the Table 1.

(8) TABLE-US-00001 TABLE 1 Constitution form of formulas of embodiments and comparison example Comparison Component Project Embodiment 1 Embodiment 2 Embodiment 3 Embodiment 4 example 1 Photopolymerizable prepolymer 44.8 44.8 (oligomer) (synthesis case 1-A1) Photopolymerizable prepolymer 44.8 (oligomer) (synthesis case 2-A2) Photopolymerizable prepolymer 44.8 (oligomer) (synthesis case 3-A3) Photopolymerizable prepolymer 44.8 (oligomer) (synthesis case-A4) DPHA 5.0 5.0 5.0 5.0 5.0 (dipentaerythritolpentaacrylate), acrylic monomer dicyclo pentadiene-phenol 6.2 6.2 novolac multifunctional epoxy resin (produced by Nan Ya Plastics Corporation, NPPN-272H) PPE polyphenyl ether modified 6.2 benzaldehyde novolac multifunctional epoxy resin (produced by Nan Ya Plastics Corporation, NPPN-433P) Phenol-benzaldehyde novolac 6.2 multifunction epoxy resin (produced by Nan Ya Plastics Corporation, NPPN-433) Tetramethyl diphenol epoxy 7.2 7.2 7.2 7.2 7.2 resin Active ester resin 7.5 7.5 7.5 Photoinitiator 5.6 5.6 5.6 5.6 5.6 Filler 24.3 18.6 18.6 18.6 32.3 Accelerant 0.2 0.2 0.2 0.2 0.2 Solvent 4.9 4.9 4.9 4.9 4.9 Total 100 100 100 100 100 Developability (developing time: 90~120 s) Pencil hardness (H) 5 5 5 5 7 Adhesion 100/100 100/100 100/100 100/100 100/100 Heat resistance to solder spray 3 times, 3 times, 3 times, 3 times, 3 times, of taphole (270 C.) pass pass pass pass pass Soldering resistance of plug-in 3 times, 3 times, 3 times, 3 times, 3 times, (260 C.) pass pass pass pass pass Dielectric constant Dk(1 GHz) 3.05 3.00 2.90 3.05 3.6 Dissipation factor Df(1 GHz) 0.011 0.010 0.010 0.011 0.025

(9) Test of weight average molecular weight (Mw) Dissolve the sample in the THF to prepare the solution with concentration of 0.5-2.0%; implement injection and analysis by using gel chromatograph, and set up correction curve chart of weight average molecular weight Mw/Mn by using the polystyrene standard.

(10) Developability

(11) Brush and grind (linear speed: 2M/min; acid leach: 3% sulfuric acid; and drying: 90 C.) the test board clearly and coat the ink on the circuit board by using the screen of 36T; bake the circuit board 40 min in the drier at 75 C.; take out the circuit board from the drier and cool it to room temperature naturally.

(12) Developing Condition:

(13) Concentration of developing solution: 1.00.2% Na.sub.2CO.sub.3 aqueous solution.

(14) Spray pressure: 2.50.5 Kg/cm2

(15) Developing temperature: at 3033 C.

(16) : Complete developing

(17) : The trace part cannot be developed.

(18) : One part cannot be developed completely.

(19) x: Cannot develop completely.

(20) Adhesion

(21) The hardening mould shall have the part of lattice according to the test method specified by JIS D 0202. Moreover, the peeling condition can be evaluated with eyes after peeling test by using Sailuofan adhesive tape.

(22) : 100/100, that is, no peeling occurs to 100 parts.

(23) : 100/100, the minority of the part is peeled.

(24) : 50/10090/100, that is, parts 50-90 in 100 are kept without peeling.

(25) x: 0/10050/100, that is, parts 0-50 in 100 are kept without peeling.

(26) Pencil Hardness

(27) Grind the tip (into right angle) of the 2B9H pencil produced by Mitsubishi after manufacturing the test slide by using the method of adhesion and scratch the test slide with angle of 45 degrees until the coating is scratched.

(28) Heat Resistance to Solder Spray of Taphole

(29) Brush and grind (linear speed: 2M/min; acid leach: 3% sulfuric acid; and drying: 90 C.) the test board clearly and coat the ink on the test board by using the screen of 36T, wherein the wet coating shall be 36-42 m; each hole of the taphole part shall be full of ink and pre-baked 40 min at 75 C.; implement hardening with UV exposure energy of 500 mJ/cm2 and hardening by means of segmented baking 30 min at 85 C., 30 min at 120 C. and 60 min at 15 C.; coat the soldering flux (known) on the circuit board hardened, spray tin for 10 s each time at 270 C. until peel occurs (next test can be implemented when the board is cooled each test); and stop the test if no peeling occurs after three times of tests.

(30) Wave Soldering Resistance of Plug-in

(31) Brush and grind (linear speed: 2M/min; acid leach: 3% sulfuric acid; and drying: 90 C.) the test board clearly and coat the ink on the test board by using the screen of 36T, wherein the wet coating shall be 36-42 m; hardening the circuit board by using the hardening method mentioned in heat resistance to solder spray of tap hole; test the circuit board after hardening by using the wave welder under the conditions that the pre-heating section is at 250 C., the temperature of tin is at 260 C., the linear speed is at 1.3M/min, the soldering flux is KESTER 984, and the acid value of the soldering flux is 1725 mgKOH/g until peeling occurs (next test can be implemented when the board is cooled each test); and stop the test if no peeling occurs after three times of tests.

(32) Test of Dielectric Constant (Dk):

(33) The test method comprises: harden the coating with thickness of 100 um by using the 5 cm5 cm square ink, clamp the test plate into the dielectric constant tester and acquire the average value after measuring the data of three points.

(34) Test of Dissipation Factor (Df):

(35) The test method comprises: harden the coating with thickness of 100 um by using the 5 cm5 cm square ink, clamp the test plate into the dielectric constant tester and acquire the average value after measuring the data of three points.

(36) The embodiments 1-4 and the comparison example in the above-mentioned form show that the photopolymerizable prepolymer (oligomer) can be by reacting the dicyclo pentadiene-phenol novolac multifunctional epoxy resin with the acrylic acid and reacting with the methyl tetradrophthalic anhydride in the embodiment 1; the photopolymerizable prepolymer (oligomer) can be by reacting the dicyclo pentadiene-phenol novolac multifunctional epoxy resin with the acrylic acid and reacting with the methyl tetradrophthalic anhydride, and the active ester resin is added to the photopolymerizable prepolymer (oligomer) in the embodiment 2; the photopolymerizable prepolymer (oligomer) can be by reacting the polyphenyl ether modified multifunctional epoxy resin with the acrylic acid and reacting with the methyl tetradrophthalic anhydride, and the active ester resin is added to the photopolymerizable prepolymer (oligomer) in the embodiment 3; the photopolymerizable prepolymer (oligomer) can be by reacting the phenol-benzaldehyde novolac multifunction epoxy resin with the acrylic acid and reacting with the methyl tetradrophthalic anhydride; the photopolymerizable prepolymer (oligomer) synthesized in the above-mentioned embodiments 1-4 are substituted into the solder resist ink produced according to the formula and compared with the comparison example, wherein the dielectric constant can be reduced between 3.2 from 3.6, and the dissipation factor can be reduced below 0.015 from 0.025; and the solder resist ink is applicable for printed circuit board for high-frequency high-speed signal transmission.

SYMBOL DESCRIPTION

(37) None