CN100523051C - Soluble polyimide resin and preparation method thereof - Google Patents

Abstract

The present invention provides a polyimide resin. The resin is formed by polymerizing at least a dianhydride monomer represented by formula (I), wherein R is an oxygen atom or -O( _CH2 ) _nO- , and n is an integer of 0 to 2; and a diamine monomer _H2N -Ar- _NH2 (II) represented by formula (II) to form a polyamic acid resin, and then performing an imidization reaction. The polyimide resin of the present invention uses a specific dianhydride monomer and a diamine monomer to react, introduce a biphenyl structure into the main chain part of the polyimide resin, improve the water absorption and thermal expansion coefficient of the polyimide resin, make it soluble in an organic solvent, and take into account the heat resistance and dimensional stability of the polyimide resin. The polyimide resin of the present invention is soluble in an organic solvent, has high dimensional stability and excellent heat resistance.

Description

Soluble polyimide resin and its preparation method

technical field

The invention relates to a polyimide resin and its preparation method, in particular to a soluble polyimide resin and its preparation method.

Background technique

In recent years, due to the thinning and miniaturization requirements of electronic and communication equipment, the packaging volume of integrated circuits in the equipment is also developing towards miniaturization and thinning, and the wiring circuit boards used are also becoming more and more miniaturized. Among various wiring circuit boards, flexible printed circuit boards can greatly reduce the volume and weight of electronic components, and are a commonly used wiring circuit board.

Generally, the structure of the flexible printed circuit board includes an insulating substrate and a metal conductor layer. The insulating substrate and the metal conductor layer are bonded with an adhesive to form a circuit laminate. Copper foil is usually used as the material of the metal layer. Polyimide resin has heat resistance, chemical resistance, excellent mechanical properties and good electrical properties, and is a commonly used insulating substrate material. The adhesive used for bonding the metal layer to the insulating substrate is usually an epoxy resin or an acrylic resin adhesive. However, the heat resistance of these adhesives is not good, and they are easy to break during the subsequent resin thermosetting process, which reduces the dimensional stability of the flexible printed circuit board. To solve this problem, some people try to add rubber elastomers to the adhesive to avoid cracking. However, the thermal stability of the rubber elastomer is not good, and it will deteriorate in the high-temperature process, resulting in a decrease in the physical properties of the flexible circuit board.

The characteristics of the polyimide resin layer will also affect the quality of the laminate. When the polyimide resin contains more amide groups, the water absorption of the polyimide resin layer will be increased, and the amide groups will be decomposed into sub- amine and acid groups. The introduction of other functional groups into the main chain of the molecule can reduce the water absorption of the polyimide resin. However, the application of too many long-chain monomers will cause the elasticity of the polyimide resin layer to decrease, and the increase in the coefficient of linear expansion will lead to a large change in the size of the prepared laminate and a decrease in dimensional stability.

In addition, polyimide acid resin usually cannot be dissolved in organic solvents after the dehydration dead cycle, thus greatly reducing its applicability. Therefore, there is a need for a polyimide resin that can reduce water absorption and linear expansion coefficient, and has good heat resistance and processing characteristics.

Contents of the invention

In order to overcome the above-mentioned shortcoming of the prior art, the main purpose of the present invention is to provide a polyimide resin soluble in organic solvents.

Another object of the present invention is to provide a polyimide resin with high dimensional stability.

Still another object of the present invention is to provide a polyimide resin excellent in heat resistance.

In order to achieve the above and other purposes, the present invention provides a dianhydride monomer comprising at least formula (I)

In the formula, R is an oxygen atom or O(CH ₂ ) _n O, wherein n is an integer from 0 to 2;

And the diamine monomer represented by formula (II)

H ₂ N—Ar—NH ₂ (II)

In the formula, Ar is an aromatic group as shown below,

Use the above-mentioned specific dianhydride monomers to react with diamine monomers, introduce the biphenyl structure into the main chain of the polyimide resin, improve the structure of the polyimide resin, and make it soluble in organic solvents, while taking into account Heat resistance and dimensional stability of polyimide resin.

The present invention also provides a method for producing polyimide resin, the method at least comprises the dianhydride monomer shown in formula (I) and the diamine monomer shown in formula (II), under the condition that solvent exists A polymerization reaction is performed to form a polyamic acid resin, followed by an imidization reaction to form a polyimide resin. The polyimide resin of the present invention is soluble and can be dissolved in an organic solvent to prepare a varnish, which can be used as an adhesive for preparing laminates and IC packaging.

In summary, compared with the prior art, the polyimide resin of the present invention is soluble in organic solvents, has high dimensional stability and excellent heat resistance.

Detailed ways

Embodiments of the present invention are described below through specific examples.

The polyimide resin of the present invention is to comprise at least the dianhydride monomer shown in formula (I)

In the formula, R is an oxygen atom or O(CH ₂ ) _n O, n is an integer from 0 to 2, and n is preferably an integer from 0 or 2;

And the diamine monomer represented by formula (II)

H ₂ N—Ar—NH ₂ (II)

In the formula, Ar is an aromatic group as shown below,

The polyimide resin of the present invention is formed by polymerizing the dianhydride monomer of formula (I) and other monomers, and the ester functional group is introduced into the polyimide resin by the dianhydride monomer of formula (I) , can increase the solubility of the polyimide resin of the present invention in organic solvents. Furthermore, the biphenyl functional group containing the liquid crystal structure is also introduced into the polyimide resin by the dianhydride monomer of formula (I), which can reduce the water absorption of the polyimide, and can adjust the polyimide The coefficient of thermal expansion of the resin. Increasing the solubility of polyimide resin can increase its applicability, and reducing water absorption can improve the processing stability and dimensional stability of polyimide resin. The closer the coefficient of thermal expansion of polyimide resin is to that of metal layers such as copper foil, the easier it is to make wiring boards without curling and deformation during high-temperature processing to reduce dimensional stability.

Embodiments of the present invention use dianhydride monomers in addition to dianhydride monomers represented by formula (I), and may also contain other dianhydride monomers, examples of which include, but are not limited to, 3,3',4,4'- Benzophenonetetracarboxylic dianhydride (BTDA), 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA), 4,4'-oxydiphthalic anhydride (ODPA) anhydride monomer. In examples, R of the dianhydride shown in formula (I) can be an oxygen atom or O(CH ₂ ) _n O, when R is an oxygen atom, the dianhydride of formula (I) is called PBTDA; when n is 2. When R is OCH ₂ CH ₂ O, the dianhydride of formula (I) is called BHEBPDA.

The preparation of PBTDA can be obtained by existing methods, for example, Japanese Patent No. 43-5911 uses benzene and toluene as solvents, and is prepared by reacting anhydrous chlorides with glycols; The product is obtained by transesterifying anhydrous acid compound trimellitic anhydride (TMA, Trimelltic Anhydride) with diesters in a solvent-like solvent. The PBTDA preparation method is shown in Reaction Formula 1.

Reaction 1

The preparation of BHEBPDA can be obtained by existing methods, such as using BHEBP and TMA to carry out transesterification reaction, and this method is disclosed in Japanese patent application JP10-330306.

The synthesis method of BHEBPDA is shown in Reaction Formula 2.

Reaction 2

Wherein, based on the total amount of dianhydride monomers, the content of dianhydride monomers represented by formula (I) is preferably 5 to 20 mole %; the 3,3',4,4'-diphenylmethyl The content of the ketone tetracarboxylic dianhydride (BTDA) monomer is preferably 60 to 80 mole %; the content of the 3,3',4,4'-biphenyltetracarboxylic dianhydride monomer (BPDA), Preferably, it is 10 to 20 mole %; the content of 4,4'-oxydiphthalic anhydride monomer (ODPA) is preferably 5 to 15 mole %.

In addition to the diamine monomer of formula (II), the polyimide resin of the present invention may also include one or more other diamine monomers, examples of which include, but are not limited to, 2,2'-bis-[4 -(4-aminophenoxy)phenyl]propane (BAPP), 4,4'-bis-(4-aminophenoxy)biphenyl (BAPB), bis[4-(4-aminophenyl Oxygen)phenyl]sulfone (BAPS), 3,3'-bisaminodiphenylsulfone (DDS, 3,3'-Diaminodiphenylsulfone) and 1,4-bis(4-aminophenoxy)benzene ( APB, 1,4-Bis(4-aminoPhenoxy)benzene).

In the polyimide resin of the present invention, the ratio of the dianhydride monomer to the diamine monomer is preferably between 0.75 and 1.25, more preferably between 0.9 and 1.1, in terms of moles. In the polyimide resin of the present invention, diamine and dianhydride monomers are respectively dissolved in an aprotic solvent, and polymerized to form a polyamic acid resin. Examples of the aprotic solvent include, but are not limited to, N-methyl-2-pyrrolidone (NMP), dimethylacetamide (DMAC), dimethylformamide (DMF), and mixtures thereof. When forming the polyamic acid resin, the diamine can be dissolved in the above-mentioned solvent first, and then the dianhydride can be added in batches for reaction. An organic solvent may also be added to the above-mentioned aprotic solvent, and examples of the organic solvent include, but are not limited to, benzene, toluene, hexane, cyclohexanol, and mixtures thereof. The amount of the organic solvent is based on the principle of preventing the polyamic acid resin from precipitating.

The temperature range of the reaction between the dianhydride and diamine is preferably from 0 to 100°C, and more preferably from 0 to 80°C. Preferably, the polyamic acid resin solution comprises 5 to 50% of the solid component; more preferably, the solid component accounts for 10 to 30% of the solution.

When making polyimide resin, the above-mentioned polyamic acid resin is added to triethylamine and acetic anhydride to carry out chemical cyclization reaction at low temperature to form polyimide resin, or to add an entrainer such as toluene or xylene , and then raise the temperature to carry out reflux dehydration and cyclization to become a polyimide resin, and then add methanol to precipitate the reaction product into a powder.

When the polyimide resin of the present invention is used to make a flexible circuit board, the thickness of the polyimide resin layer is usually 5 to 100 microns. The metal layer can be copper foil, aluminum foil, nickel foil, alloy foil or iron foil; wherein, the copper foil can be electrolytic copper foil or rolled copper foil, and its thickness is usually 12 to 70 microns. The production method can first coat the polyamic acid resin on the roughened surface of the above metal layer, and the coating method can use a die coater (die coater), lip coater (lip coater) or roll coater (roll coater) to coat cloth. After the coating is completed, put it in an oven to remove the solvent by heating in stages, so that the solvent content is below 20%. The baking temperature is generally 110 to 180°C, preferably 120 to 170°C. The baking speed is usually 0.5 to 10 m/min, preferably 1 to 7 m/min.

Then curing at a high temperature, or adding tertiary amines or acetic anhydride to cure at a lower temperature, imidates the polyamic acid resin into a polyimide resin. Ripening can be achieved by heating in an oven in a continuous or batch manner. The post curing temperature is 200 to 400°C, preferably 250 to 350°C. The chemical aging temperature for adding tertiary amines or acetic anhydride is 200 to 300°C. Nitrogen or a non-reactive gas environment can be used in the oven to protect the metal layer from oxidation during oven heating.

The polyimide resin powder of the present invention can be dissolved in aprotic polar organic solvents such as NMP, DMAC or DMF to prepare a varnish (varnish), which is coated on a polyimide substrate (such as Kapton, Apical or Upilex and other commercially available products) and used as an adhesive. The solid content of the polyimide resin in the varnish is 5 to 50%, preferably 10 to 30%. The polyimide substrate coated with varnish is baked in an oven to remove the solvent, and then laminated with metals such as copper foil to form a flexible circuit board, such as a double-layer wiring board. The polyimide resin of the present invention has good heat resistance and high bonding strength, which can improve the shortcomings of existing adhesives such as epoxy resin adhesives or acrylic resin adhesives, which have poor heat resistance, and avoid resin Adhesives deteriorate at high temperatures, resulting in reduced quality of wiring boards.

The polyimide resin of the present invention can also be used for encapsulation of electronic mechanisms or electronic components, for example, it can be used for shielding protective films of integrated circuit (IC) components or light emitting diode (LED) components. The polyimide resin of the present invention can also be blended with a photosensitive group-containing compound to form a photosensitive polyimide resin used in the manufacture of integrated circuits (IC). In addition, the polyimide resin of the present invention can be made into a film or prepared into a varnish for making a high heat-resistant cover film, such as a cover film for a flexible board. The polyimide resin of the present invention can also be blended with a high dielectric constant material such as barium titanate to make a thin film, as an internal built-in electronic component such as a capacitor.

Raw material description

BTDA: 3,3',4,4'-Benzophenone tetracarboxylic dianhydride

BPDA: 3,3',4,4'-Biphenyltetracarboxylic dianhydride

ODPA: 4,4'-oxydiphthalic anhydride

TPE-R: 1,3-bis(4-aminophenoxy)benzene

BAPP: 2,2'-bis-[4-(4-aminophenoxy)phenyl]propane

BAPS: bis[4-(4-aminophenoxy)phenyl]sulfone

APB: 1,4-bis(4-aminophenoxy)benzene

BAPB: 4,4'-bis-(4-aminophenoxy)biphenyl

NMP: N-methyl-2-pyrrolidone

DMAC: Dimethylacetamide

DMF: Dimethylformamide

Physical property test method

(1) Water absorption: according to IPCTM-6502.6.2

(2) Handa heat resistance test: according to IPCTM-6502.4.13

(3) Peel Strength: according to IPCTM-6502.4.9

(4) Tg: Temperature glass transition temperature (Tg) measured by thermomechanical analysis

Example 1

Put 24.6 grams of APP (0.06 mol) and 160 grams of NMP into a four-neck reactor with a stirrer and a nitrogen conduit for dissolution. The nitrogen flow rate is 20cc/min. After stirring evenly and dissolving, maintain 15°C.

Take four flasks with stirring bars respectively, put 2.94 g of BPDA (0.01 mol) and 10 g of NMP into the first flask and stir to dissolve them. 1.34 grams of PBTDA (0.0025 moles) and 10 grams of NMP were placed in the second flask and stirred to dissolve. The solutions in the first and second flasks were added into the reaction kettle, nitrogen gas was continuously introduced, and the reaction was carried out with stirring for 1 hour.

Put 3.1 g of ODPA (0.01 mol) and 10 g of NMP into the third flask, stir to dissolve them. The solution in the flask was added to the reaction kettle, nitrogen gas was continuously introduced, and the reaction was carried out with stirring for 1 hour.

Put 12.08 grams of BTDA (0.0375 moles) and 50 grams of NMP into the fourth flask, stir to dissolve. Next, the solution in the fourth flask was added into the reaction kettle four times every 30 minutes, nitrogen gas was continuously introduced, and the reaction was carried out at 15° C. for 4 hours to generate polyamic acid resin.

Stop introducing nitrogen, and the reaction kettle is equipped with Dean stack to remove water. Take 35 grams of toluene into the reaction kettle, raise the temperature to 185° C. to carry out dead cycle dehydration reaction, so that the polyamic acid resin becomes polyimide resin. The water was continuously taken out by reflux of toluene until it was confirmed that no water was taken out, and then the temperature was lowered to room temperature. Then add methanol to precipitate the polyimide resin, filter the precipitate, wash the precipitate twice with methanol, and dry in an oven to obtain polyimide resin powder.

0.5 g of polyimide resin was dissolved in 15 g of N-methyl-2-pyrrolidone, and the intrinsic viscosity (IV) measured at 25° C. by a viscometer was 1.16 dl/g.

Example 2 to Example 10

Repeat the step of Example 1, and the molar amount of each component is as shown in Table 1.

Comparative Example 1 and Comparative Example 2

Repeat the step of Example 1, and the molar amount of each component is as shown in Table 1.

Table 1

Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Example 9 Example 10 Comparative example 1 Comparative example 2 BPDA 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.040 BTDA 0.075 0.07 0.065 0.060 0.075 0.07 0.07 0.07 0.07 0.07 0.08 0.050 ODPA 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 PBTDA 0.005 0.01 0.015 0.02 0.01 0.01 0.01 0.01 BHEBPDA 0.005 0.01 BAPP 0.1 0.1 0.1 0.1 0.1 0.1 0.1 BAPB 0.1 BAPS 0.1 BAPS-M 0.1 TPE-R 0.1 APB 0.1 Intrinsic viscosity (dl/g) 1.16 0.97 1.25 1.31 0.92 0.85 0.93 1.22 0.95 0.83 0.92 1.13

The polyimide resin powders obtained in Examples 1 to 10 and Comparative Examples 1 and 2 were dissolved in a solvent, and the results are listed in Table 2.

Table 2

Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Example 9 Example 10 Comparative example 1 Comparative example 2 NMP + + + + + + + + + + + * DMAC + + + + + + + + + + * * DMF + + + + + + + + + + — —

"+" means dissolved; "—" means insoluble; "*" means dissolved after heating

Dissolve the polyimide resin powder obtained in the above-mentioned Examples 1 to 10 and Comparative Example 1 and Comparative Example 2 in NMP, prepare a varnish with a solid content of 15%, and coat it on a polyimide resin with a thickness of 25 microns. On the imide film (trade name Apical), the coating thickness was 6 micrometers. The solvent was dried and removed in an oven under the conditions of heating at 150° C. for 5 minutes and at 180° C. for 15 minutes. After the drying is completed, the polyimide film coated with polyimide resin and the blank copper foil are pressed together at 280°C to 400°C using a high-temperature press machine. 200kg/cm ² , preferably 40-150kg/cm ² . The polyimide resin double-sided copper foil wiring board was obtained, and the peel strength of the copper foil was tested by IPCTM-650. The results are listed in Table 3.

table 3

Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Example 9 Example 10 Comparative example 1 Comparative example 2 Tg(°C) 234 243 247 235 234 226 235 225 228 238 236 247 Peel strength (kgf/cm) 1.1 1.1 1.3 1.2 1.4 1.3 1.2 1.4 1.7 1.4 0.8 0.7 Heat resistance test (288℃10sec) pass pass pass pass pass pass pass pass pass pass pass pass

As can be seen from Table 3, the double-sided copper foil wiring board made by the polyimide resin of the present invention has a better peel strength (greater than 1.0kg/cm), thus it can be known that the polyimide resin of the present invention is The manufactured flexible circuit board has better characteristics than existing ones.

Claims (18)

1. the polyimide resin with solubility is characterized in that, this resin is by comprising 3,3 ', 4,4 '-benzophenone tetracarboxylic dianhydride; 3,3 ', 4,4 '-biphenyl tetracarboxylic dianhydride monomer; 4,4 '-oxygen, two benzene dianhydrides; And the dianhydride monomer shown in the formula (I)

Wherein, R be Sauerstoffatom or-O (CH ₂) _nO-, n are 0 to 2 integer; And the diamine monomer shown in the formula (II)

H ₂N—Ar—NH ₂ (II)

In the formula, Ar is expression

Carrying out polyreaction and form polyamic acid resin, then carry out imidization and form, and the content of the dianhydride monomer shown in the formula (I), is 5 to 20 moles of % in the total amount of dianhydride monomer; 3,3 ', 4, the monomeric content of 4 '-benzophenone tetracarboxylic dianhydride is 60 to 80 moles of % in the total amount of dianhydride monomer; 3,3 ', 4, the monomeric content of 4 '-biphenyl tetracarboxylic dianhydride is 10 to 20 moles of % and 4 in the total amount of dianhydride monomer, and the content of 4 '-oxygen hexichol dianhydride monomer is 5 to 15 moles of % in the total amount of dianhydride monomer.

2. polyimide resin as claimed in claim 1 is characterized in that, n is 0 or 2 integer.

3. polyimide resin as claimed in claim 1 is characterized in that, the ratio of this dianhydride monomer and diamine monomer is between 0.75 to 1.25 in mole number.

4. polyimide resin as claimed in claim 2 is characterized in that, the ratio of this dianhydride monomer and diamine monomer is between 0.9 to 1.1 in mole number.

5. a resinous varnish is characterized in that, this resinous varnish comprises polyimide resin as claimed in claim 1 and solvent, and varnish makes through reconciling into.

6. resinous varnish as claimed in claim 5 is characterized in that, this varnish is the resin tackiness agent.

7. resinous varnish as claimed in claim 5 is characterized in that, this solvent is to be selected from N-N-methyl-2-2-pyrrolidone N-, N,N-DIMETHYLACETAMIDE or dimethyl formamide to constitute a kind of in the group.

8. resinous varnish as claimed in claim 5 is characterized in that, the solid of this polyimide resin in this varnish is 5 to 50%.

9. resinous varnish as claimed in claim 5 is characterized in that, the solid of this polyimide resin in this varnish is 10 to 30%.

10. a method of using resinous varnish as claimed in claim 5 to prepare flexible circuit board is characterized in that this method comprises the following steps:

Polyimide resin varnish is coated on the tinsel; And

Add the heat abstraction solvent.

11. method as claimed in claim 10 is characterized in that, this method also comprises the following steps:

Do not fit the one side of tinsel with pressuring method another tinsel of fitting at polyimide resin varnish; And

Heat hardening resin combination under nitrogen is made the double-surface flexible circuit card of tinsel-resin-tinsel.

12., it is characterized in that this tinsel is that Copper Foil, aluminium foil, nickel foil or Alloy Foil constitute a kind of in the group as claim 10 or 11 described methods.

13. a method of making polyimide resin as claimed in claim 1 is characterized in that this method comprises the following steps:

(a) use dissolution with solvents to comprise 3 respectively, 3 ', 4,4 '-benzophenone tetracarboxylic dianhydride; 3,3 ', 4,4 '-biphenyl tetracarboxylic dianhydride monomer; 4,4 '-oxygen, two benzene dianhydrides; And the dianhydride monomer shown in the formula (I)

In the formula, R be Sauerstoffatom or-O (CH ₂) _nO-, n are 0 to 2 integer;

And the diamine monomer shown in the formula (II)

H ₂N—Ar—NH ₂ (II)

In the formula, Ar is expression

, and the content of the dianhydride monomer shown in the formula (I) is 5 to 20 moles of % in the total amount of dianhydride monomer; 3,3 ', 4, the monomeric content of 4 '-benzophenone tetracarboxylic dianhydride is 60 to 80 moles of % in the total amount of dianhydride monomer; 3,3 ', 4, the monomeric content of 4 '-biphenyl tetracarboxylic dianhydride is 10 to 20 moles of % and 4 in the total amount of dianhydride monomer, and the content of 4 '-oxygen hexichol dianhydride monomer is 5 to 15 moles of % in the total amount of dianhydride monomer;

(b) will add in the dissolved diamine monomer through the dissolved dianhydride monomer in batches, carry out polyreaction and form polyamic acid resin; And

Carry out imidization and form polyimide resin.

14. method as claimed in claim 13 is characterized in that, the ratio of this dianhydride monomer and diamine monomer is between 0.75 to 1.25 in mole number.

15. method as claimed in claim 14 is characterized in that, the ratio of this dianhydride monomer and diamine monomer is between 0.9 to 1.1 in mole number.

16. method as claimed in claim 13 is characterized in that, this solvent is to constitute a kind of in the group by N-N-methyl-2-2-pyrrolidone N-, N,N-DIMETHYLACETAMIDE or dimethyl formamide.

17. method as claimed in claim 13 is characterized in that, also comprises the step of adding organic solvent in this step (b), this organic solvent is the group that is made of benzene, toluene, hexane and hexalin.

18. method as claimed in claim 13 is characterized in that, the temperature of this step (b) is 0 to 100 ℃.