Halogen-Free Epoxy Resin Composition, Prepreg, Laminate and Printed Circuit Board Containing the Same

Abstract

The present invention relates to a halogen-free epoxy resin composition, a prepreg, a laminate and a printed circuit board containing the same. The halogen-free epoxy resin composition comprises an epoxy resin and a curing agent. Taking the total equivalent amount of the epoxy groups in the epoxy resin as 1, the active groups in the curing agent which react with the epoxy groups have an equivalent amount of 0.5-0.95. By controlling the equivalent ratio of the epoxy groups in the epoxy resin to the active groups in the curing agent to be 0.5-0.95, the present invention ensures the Df value stability of prepregs under different curing temperature conditions while maintaining a low dielectric constant and a low dielectric loss. The prepregs and laminates prepared from the resin composition have comprehensive performances, such as low dielectric constant, low dielectric loss, excellent flame retardancy, heat resistance, cohesiveness, low water absorption and moisture resistance, and are suitable for use in halogen-free multilayer circuit boards.

Claims

1. A halogen-free epoxy resin composition comprising an epoxy resin and a curing agent, wherein taking the total equivalent amount of the epoxy groups in the epoxy resin as 1, the active groups in the curing agent which react with the epoxy groups have an equivalent amount of 0.5-0.95.

2. The halogen-free epoxy resin composition claimed in claim 1, wherein taking the total equivalent amount of the epoxy groups in the epoxy resin as 1, the active groups in the curing agent which react with the epoxy groups have an equivalent amount of 0.7-0.85.

3. The halogen-free epoxy resin composition claimed in claim 1, wherein the curing agent is styrene-maleic anhydride and benzoxazine resin.

4. The halogen-free epoxy resin composition claimed in claim 3, wherein taking the total equivalent amount of the epoxy groups in the epoxy resin as 1, the benzoxazine resin has an equivalent amount of 0.3-0.55, and the styrene-maleic anhydride has an equivalent amount of 0.2-0.4.

5. The halogen-free epoxy resin composition claimed in claim 3, wherein taking the total equivalent amount of the epoxy groups in the epoxy resin as 1, the benzoxazine resin has an equivalent amount of 0.4-0.5, and the styrene-maleic anhydride has an equivalent amount of 0.3-0.35.

6. The halogen-free epoxy resin composition claimed in claim 1, wherein the epoxy resin is any one selected from the group consisting of bisphenol A epoxy resin, bisphenol F epoxy resin, biphenyl epoxy resin, alkyl novolac epoxy resin, dicyclopentadiene epoxy resin, bisphenol A novolac epoxy resin, o-cresol novolac epoxy resin, phenol novolac epoxy resin, tetrafunctional epoxy resin, isocyanate-modified epoxy resin, naphthalene epoxy resin and phosphorus-containing epoxy resin, or a mixture of at least two selected therefrom. ##STR00003## ##STR00004##

7. The halogen-free epoxy resin composition claimed in claim 3, wherein the benzoxazine resin is any one selected from the benzoxazine resins having the following structures, or a combination of at least two selected therefrom: ##STR00005## wherein R.sub.2 and R.sub.3 are mono- or poly-substituted, and are each independently selected from the group consisting of hydrogen, methyl, allyl and formyl group; R.sub.1 is any one selected from the group consisting of —CH.sub.2—, —O—, —C(CH.sub.3).sub.2—, —SO.sub.2—, —C(CF.sub.3).sub.2—, —CH.sub.2CH.sub.2— and dicyclopentadiene, or a combination of at least two selected therefrom; R.sub.4 and R.sub.5 are each independently selected from the group consisting of allyl, unsubstituted or substituted phenyl, unsubstituted or substituted alkyl having 1-8 carbon atoms and cycloalkyl having 1-8 carbon atoms, or a combination of at least two selected therefrom.

8. The halogen-free epoxy resin composition claimed in claim 3, wherein the styrene-maleic anhydride has a structural formula of: ##STR00006## wherein x:n=0.8-19:1.

9. The halogen-free epoxy resin composition claimed in claim 3, wherein the styrene-maleic anhydride has a number average molecular weight of 1000-50000.

10. The halogen-free epoxy resin composition claimed in claim 1, wherein the halogen-free epoxy resin composition comprises one or more selected from the group consisting of polyphenyl ether resin, cyanate ester resin, bismaleimide, active ester, styrene resin, butadiene resin, phenoxy resin, rubber resin, nuclear shell resin, polyamide and polyimide.

11. The halogen-free epoxy resin composition claimed in claim 1, wherein the halogen-free epoxy resin composition further comprises a halogen-free flame retardant.

12. The halogen-free epoxy resin composition claimed in claim 11, wherein the halogen-free flame retardant is any one selected from the group consisting of phosphorus-containing novolac, phosphorus-nitrogen based compound, ammonium polyphosphate, tri(2-carboxyethyl)phosphine, tri(isopropylchloro)-phosphate, trimethyl phosphate, dimethyl-methyl phosphate, resorcinol bis-xylyl phosphate, melamine polyphosphate, melamine cyanurate and tri-hydroxyethyl isocyanurate, or a combination of at least two selected therefrom.

13. The halogen-free epoxy resin composition claimed in claim 12, wherein the phosphorus-containing novolac is any one selected from the group consisting of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide-modified novolac resin, 10-(2,5-dihydroxylphenyl)9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide-modified novolac resin, 10-(2,9-dihydroxylnaphthyl)-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide-modified novolac resin, or a mixture of at least two selected therefrom.

14. The halogen-free epoxy resin composition claimed in claim 11, wherein the halogen-free flame retardant comprises a phosphorus-containing novolac and a phosphorus-nitrogen based compound, wherein the phosphorus-containing novolac is in a weight of ⅙-⅔ of the weight of the epoxy resin, and the phosphorus-nitrogen based compound is in a weight of ⅙-⅚ of the weight of the epoxy resin.

15. The halogen-free epoxy resin composition claimed in claim 1, wherein the halogen-free epoxy resin composition further comprises a filler.

16. The halogen-free epoxy resin composition claimed in claim 15, wherein the filler is an organic and/or inorganic filler.

17. The halogen-free epoxy resin composition claimed in claim 16, wherein the inorganic filler is any one selected from the group consisting of aluminum hydroxide, alumina, magnesium hydroxide, magnesium oxide, aluminum oxide, silica, calcium carbonate, aluminum nitride, boron nitride, silicon carbide, titanium dioxide, zinc oxide, zirconium oxide, mica, boehmite, calcined talc, talcum powder, silicon nitride and calcined kaolin, or a mixture of at least two selected therefrom; the organic filler is any one selected from the group consisting of polytetrafluoroethylene powder, polyphenylene sulfide and polyether sulfone powder, or a mixture of at least two selected therefrom.

18. The halogen-free epoxy resin composition claimed in claim 15, wherein the filler has a particle size of from 0.01 to 50 μm.

19. The halogen-free epoxy resin composition claimed in claim 1, wherein the halogen-free epoxy resin composition further comprises a curing accelerator which is selected from imidazole accelerators.

20. The halogen-free epoxy resin composition claimed in claim 19, wherein the curing accelerator is any one selected from the group consisting of 2-methyl imidazole, undecyl imidazole, 2-ethyl-4-methyl imidazole, 2-phenyl imidazole and 1-cyanoethyl-substituted imidazole, or a combination of at least two selected therefrom.

21. A prepreg comprising a reinforcing material and the halogen-free epoxy resin composition in claim 1 attached thereon after impregnation and drying.

22. A laminate, comprising at least one prepreg claimed in claim 21.

23. A printed circuit board, comprising at least one prepreg claimed in claim 21.

Description

EMBODIMENTS

[0057] The technical solution of the present invention is further stated by the following specific embodiments.

[0058] As for the resin composition for use in prepregs and laminates of the present invention, the peeling strength, glass transition temperature, flame retardancy, dip soldering resistance limit after two hours of PCT, water absorption and dielectric constant of substrates cured at 200° C. for 120 minutes were tested, and the dielectric loss performance was tested at different curing temperatures. The following examples provide further description.

[0059] Epoxy resin, benzoxazine, styrene-maleic anhydride, halogen-free flame retardant, filler and other auxiliaries were fed into a container, stirred and homogeneously mixed to make a glue. A solvent was used to adjust the solid content of the solution to 60%-70% to obtain a glue solution, i.e., the resin composition glue solution of the present invention. A glass fabric having 2116 electronic grade was impregnated with the glue, baked with an oven to prepare the prepreg. Six sheets of 2116 prepregs were covered by both sides with electrolytic copper foils having a thickness of 35 μm, vacuum-laminated by a thermocompressor, cured at 190° C., 200° C. and 210° C. for 120 minutes to obtain a copper-clad plate.

[0060] The components in the examples and comparison examples are stated as follows.

(A) Epoxy resin
(A-1) NC-3000-H (Trade name from Japan Chemical)
(A-2) HP-7200H (Trade name from Dainippon Ink)
(B) Benzoxazine resin
(B-1) D-125 (Trade name from Sichuan East wood Technology Group Co., Ltd)
(B-2) LZ8280 (Trade name from Huntsman Advanced Materials)
(C) Styrene-maleic anhydride oligomer: SMA-EF40 (Trade name from Sartomer)
(D-1) Dicyandiamide: DICY (Trade name from Ningxia Darong)

(D-2) Polyester: EXB-9460

[0061] (E) Phosphorus-containing novolac resin
(E-1) XZ92741 (Trade name from DOW)
(E-2) LC-950 (Trade name from SHIN-A)
(F) Phosphorus-nitrogen based compounds: SPB-100 (Trade name from Otsuka Chemical Corporation)
(G) Filler: molten silica

TABLE-US-00001 TABLE 1 Glue ingredients Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Example 9 Epoxy A-1 60 60 60 60 30 60 60 60 resin A-2 60 30 Total 1 1 1 1 1 1 1 1 1 equivalent amount Curing B-1 15 23 28 23 20 25 23 agent B-2 23 28 C 10 16 20 16 20 15 14 18 Total 0.5 0.78 0.95 0.78 0.85 0.85 0.7 0.85 0.78 equivalent amount Flame E-1 18 18 retardant E-2 40 10 F 30 10 50 30 Filler G 50 50 100

TABLE-US-00002 TABLE 2 Glue Com. Com. Com. Com. Com. Com. Com. Com. ingredients Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Epoxy A-1 60 60 30 30 resin A-2 60 60 60 30 60 60 Total 1 1 1 1 1 1 1 1 equivalent amount Curing B-1 10 40 agent B-2 23 23 28 28 23 23 C 16 16 5 40 15 15 20 20 Total 0.51 1.1 0.55 1.25 0.85 0.85 0.85 0.85 equivalent amount Flame D-1 18 18 retardant D-2 40 40 5 50 40 40 E 30 30 10 10 50 50 5 60 Filler F 50 50 50 50 100 100 50 50

TABLE-US-00003 TABLE 3 Example Example Example Example Example Example Example Example Example Testing items 1 2 3 4 5 6 7 8 9 Tg(DSC) 178 184 188 182 182 180 180 186 182 (° C.) Peeling strength 1.32 1.32 1.25 1.35 1.28 1.30 1.33 1.33 1.32 (N/mm) Combustibility V-1 V-1 V-1 V-0 V-0 V-0 V-1 V-1 V-0 PCT(min) >5 >5 >5 >5 >5 >5 >5 >5 >5 PCT water 0.32 0.32 0.35 0.33 0.36 0.33 0.32 0.32 0.32 absorption % Processability Good Good Good Good Good Good Good Good Good Dielectric constant 3.9 3.9 3.9 3.9 3.9 3.9 3.9 3.9 3.9 (1 GHz) Dielectric 190° C./ 0.007 0.0063 0.0063 0.0063 0.0067 0.0065 0.0065 0.0063 0.0063 loss 120 min (1 GHz) 200° C./ 0.007 0.0063 0.0063 0.0063 0.0067 0.0065 0.0065 0.0063 0.0063 120 min 210° C. 0.007 0.0063 0.0063 0.0063 0.0067 0.0065 0.0065 0.0063 0.0063 120 min

TABLE-US-00004 TABLE 4 Com. Com. Com. Com. Com. Com. Com. Com. Example Example Example Example Example Example Example Example Testing items 1 2 3 4 5 6 7 8 Tg(DSC) 170 190 171 188 182 175 184 170 (° C.) Peeling strength 1.30 1.35 1.30 1.02 1.30 1.30 1.30 1.30 (N/mm) Combustibility V-0 V-0 V-0 V-1 V-1 V-0 V-1 V-0 PCT(min) >5 >5 >5 >5 >5 4 >5 4 PCT water 0.35 0.36 0.36 0.40 0.32 0.41 0.36 0.36 absorption % Processability Good Poor Poor Good Good Good Good Poor Dielectric constant 4.0 3.9 4.0 3.9 3.9 3.9 3.9 3.9 (1 GHz) Dielectric 190° C./ 0.0075 0.0063 0.008 0.006 0.0065 0.0068 0.0067 0.0067 loss 120 min (1 GHz) 200° C./ 0.0075 0.0072 0.008 0.0068 0.0065 0.0068 0.0067 0.0067 120 min 210° C./ 0.0075 0.0080 0.008 0.0078 0.00654 0.0068 0.0067 0.0067 120 min

[0062] According to Tables 1-4:

[0063] According to Example 1 and Examples 2, 7, 8, it can be seen that the formulae optimized with curing agents has a lower Df value and a higher Tg. According to Examples 2, 7, 8 and Example 3, it can be seen that, although the formulae optimized with curing agents has a lower Tg, it has a higher peeling strength and a lower water absorption. That is to say, it can be seen according to Examples 1-3, 7 and 8 that the formulae optimized with curing agents has better comprehensive performances.

[0064] According to a comparison of Example 2 and Examples 4 and 9, it can be seen that, although Tg is slightly reduced after the addition of phosphorus-containing novolac and phosphorus-nitrogen based compounds, it can be ensured that the flame retardancy can achieve V-0, and there is no other effect on other performances. In addition, the addition of fillers has little effect on the substrate performance.

[0065] According to Example 4 and Comparison Examples 1-2, it can be seen that, when benzoxazine is in an equivalent amount less than 0.3, the Tg thereof is lower, and the dielectric performances are worse; when benzoxazine is in an equivalent amount high than 0.55, the processability thereof is worse, and Df is unstable and increases along with the increase of the curing temperature, although it has a higher Tg.

[0066] According to Example 5 and Comparison Examples 3-4, it can be seen that, when styrene-maleic anhydride is in an equivalent amount less than 0.2, Tg is insufficient, and the dielectric loss performance is worse, which will affect the processability of the substrate; when the equivalent amount is higher than 0.4, the flame retardancy is insufficient although Tg can increase; the water absorption increases; the Df is unstable and will increase along with the increase of the curing temperature.

[0067] According to Example 6 and Comparison Examples 5-6, it can be seen that, when phosphorus-containing novolac is in an amount less than ⅙ of the weight of the epoxy resin, the flame retardancy cannot achieve the V-0 level; when phosphorus-containing novolac is in an amount higher than ⅔ of the weight of the epoxy resin, such amount can ensure the flame retardancy, but increase the water absorption of the substrate and decrease the Tg, and will affect the PCT performance of the substrate.

[0068] According to Example 5 and Comparison Examples 7-8, it can be seen that, when the phosphorus-nitrogen based compound is in an amount less than ⅙ of the weight of the epoxy resin, the flame retardancy cannot achieve the V-0 level; when the phosphorus-nitrogen based compound is in an amount higher than ⅚ of the weight of the epoxy resin, such amount can ensure the flame retardancy, but decrease the Tg, and will affect the PCT performance and processability of the substrate.

Comparison Example 9

[0069] Comparison Example 9 is Example 4 disclosed in CN 101684191B.

Comparison Example 10

[0070] Comparison Example 10 is Example 1 disclosed in CN103131131A.

Comparison Example 11

[0071] Comparison Example 11 is Example 2 disclosed in CN 103881302A.

TABLE-US-00005 TABLE 5 Glue Example Com. Com. Com. ingredients 10 Example 9 Example 10 Example 11 Epoxy A-1 60 35 35 resin A-2 25 25 Total 1 1 1 1 equivalent amount Curing B-1 115 30 agent B-2 42 C 42 6 18 D-1 0.9 D-2 12 Total 0.8 2.9 0.93 1.42 equivalent amount Flame E-1 44 24 retardant E-2 F 21 Filler G 21 31

TABLE-US-00006 TABLE 6 Com. Com. Com. Example Example Testing items Example 10 Example 9 10 11 Tg(DSC) 175 167 170 (° C.) Peeling strength 1.27 1.38 1.32 (N/mm) Combustibility V-1 V-0 V-0 PCT(min) >5 3 >5 PCT water absorption % 0.32 0.40 0.34 Processability Good Good Good Dielectric constant (1 GHz) 4.0 3.9 3.9 Dielectric loss 190° C./120 min 0.006 0.009 0.006 (1 GHz) 200° C./120 min 0.0068 0.009 0.0065 210° C./120 min 0.0072 0.009 0.0072

[0072] According to Examples 1-9, it can be seen that the laminates prepared from the halogen-free resin composition of the present invention have better dielectric performances, and the dielectric loss value will not change along with the increase of the curing temperature, and can achieve the V-0 standard in the flame retardancy test UL-94. Thus, while ensuring the halogen-free flame retardancy, the laminates also have comprehensive performances, such as low dielectric constant, low dielectric loss, excellent heat resistance, cohesiveness and moisture resistance, and are suitable for use in halogen-free high multi-layer circuit boards. The prepregs and laminates prepared from the resin composition of the present invention have comprehensive performances, such as low dielectric constant, low dielectric loss, excellent flame retardancy, heat resistance, cohesiveness and moisture resistance, overcome the shortcomings of the current halogen-free laminates, such as insufficient heat resistance and worse moisture resistance, and are suitable for use in halogen-free high multi-layer circuit boards.

[0073] The present invention discloses the detailed process via the aforesaid examples. However, the present invention is not limited by the aforesaid detailed process. That is to say, it does not mean that the present invention cannot be carried out unless the aforesaid detailed process is used. Those skilled in the art shall know that any improvement, equivalent replacement of various raw materials of the present invention, addition of auxiliary ingredients, selection of specific modes and the like all fall within the protection scope and disclosure of the present invention.