WO2011049357A2 - Polyamic acid solution, polyimide resin, and flexible copper clad laminate using same - Google Patents

Abstract

The present invention relates to a polyamic acid solution comprising: (a) an aromatic tetracarboxylic acid dianhydride comprising 3,3',4,4'-biphenyltetracarboxylic acid dianhydride (BPDA) and pyromellitic dianhydride (PMDA); (b) an aromatic diamine; and (c) a solvent, and a polyimide resin prepared by imidization of the polyamic acid solution. A flexible copper clad laminate with excellent flexibility can be prepared by using the polyimide resin.

Description

Polyamic Acid Solution, Polyimide Resin, and Flexible Copper Foil Laminate Using the Same

The present invention relates to a polyimide resin used for producing a flexible copper foil laminate and a polyamic acid solution for producing the polyimide resin.

Flexible Copper Clad Laminate (FCCL) is mainly used as a substrate for flexible printed circuit boards (FPCBs), and is also used for surface heating element electromagnetic wave shielding materials, flat cables, and packaging materials.

Such a flexible copper foil laminate consists of a polyimide layer and a copper foil layer, and can be classified into an adhesive type and a non-adhesive type depending on whether an adhesive layer exists between the polyimide layer and the copper foil layer.

That is, the adhesive flexible copper foil laminated plate is a polyimide layer and a copper foil layer adhered by using an adhesive made of an epoxy resin or an acrylic resin, and the non-adhesive flexible copper foil laminated plate is a polyimide bonded directly to the copper foil surface. In accordance with the trend of light and thin, small and thin electronic products, the development of the non-adhesive flexible copper foil laminate rather than the adhesive flexible copper foil laminate.

The non-adhesive flexible copper foil laminate is manufactured by applying a polyamic acid solution to the surface of copper foil, followed by heating to remove the solvent contained in the polyamic acid solution, and imidating the polyamic acid to form a polyimide layer on the copper foil surface. Here, the manufactured copper foil laminate has to be flat because it must pass through the slots of various facilities and undergo a post-process. Therefore, conventionally, by adding an inorganic filler such as talc, mica, montmorillonite, and the like, the difference in thermal expansion coefficient between the copper foil layer and the polyimide layer is reduced, thereby improving flatness (Curl) of the copper foil laminate.

However, as the flatness of the copper foil laminate is improved by adding an inorganic filler, the productivity of the copper foil laminate is improved, but when the copper foil laminate is repeatedly bent, the polyimide layer ruptures easily, resulting in a problem in that the copper foil laminate is inferior in flexibility.

The present invention is to solve the above problems, in the manufacture of a flexible copper foil laminated plate, a polyimide resin and the polyimide resin that can exhibit a good flatness when bonded to the copper foil layer and can be made to have excellent flexibility It is an object to provide a polyamic acid solution for the production.

The present invention (a) 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride (3,3', 4,4'-biphenyltetracarboxylic acid dianhydride, BPDA) and pyromellitic dianhydride ( aromatic tetracarboxylic acid dianhydride, including pyromellitic dianhydride (PMDA); (b) aromatic diamines; And (c) a polyamic acid solution comprising a solvent, and a polyimide resin prepared by imidating the polyamic acid solution.

In addition, the present invention is a copper foil layer; And it provides a flexible copper foil laminate comprising a polyimide resin layer formed by bonding the polyimide resin to one surface of the copper foil layer, and a printed circuit board comprising the same.

Hereinafter, the present invention will be described in detail.

<Polyamic acid solution>

The polyamic acid solution of the present invention is used to form a flexible copper foil laminate by forming a polyimide resin layer on the copper foil layer, and (a) 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride. Aromatic tetracarboxylic acid dianhydride, including (3,3 ', 4,4'-biphenyltetracarboxylic acid dianhydride (BPDA)) and pyromellitic dianhydride (PMDA), (b ) Aromatic diamine, (c) solvent.

When the polyimide resin layer is formed on the copper foil layer using the polyamic acid solution, even if an additive such as an inorganic filler is used, the difference between the copper foil layer and the coefficient of thermal expansion (CTE) is minimized, thereby achieving good curl. The flexible copper foil laminates produced while being shown may have excellent bendability.

In particular, (a) aromatic tetracarboxylic dianhydrides comprising 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride (BPDA) and pyromellitic dianhydride (PMDA) The flatness and the flexibility may vary depending on the mixing ratio of, 3 ', 4,4'-biphenyltetracarboxylic dianhydride (BPDA) and pyromellitic dianhydride (PMDA).

That is, as the amount of 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride (BPDA) constituting the aromatic tetracarboxylic dianhydride increases, the flexibility is improved, but the flatness may be deteriorated. If the amount of metician dianhydride (PMDA) is increased, the flatness may be excellent but the flexibility may be reduced.

Thus, aromatic tetracarboxylic dianhydrides have a 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride (BPDA) and pyromellitic dianhydride (PMDA) of 60 to 90: 40 to 40 Preference is given to using what is included in a mol% proportion of 10. When 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride (BPDA) and pyromellitic dianhydride (PMDA) are included in the range of this range, it forms in copper foil layer as well as flatness and flexibility. The peeling strength of the polyimide resin layer used can also be improved.

(b) Aromatic diamine is an imidization reaction with the aromatic tetracarboxylic dianhydride to form a polyimide resin, and the polyimide resin layer has a good flatness afterwards and is excellent in the flexible copper foil laminate produced. It is preferable to include p-phenylenediamine (p-PDA) and 4,4'-oxydianiline (4,4'-oxydianiline, ODA) to exhibit flexibility.

In this case, the flatness, flexibility and peel strength may also vary depending on the mixing ratio of p-phenylenediamine (p-PDA) and 4,4'-oxydianiline (ODA) constituting the aromatic diamine. Therefore, p-phenylenediamine (p-PDA) and 4,4'-oxydianiline (ODA) are 60 to 80 in order for the polyimide resin layer formed on the copper foil layer to exhibit good flatness, excellent flexibility, and peeling strength. 40 to 20 Preference is given to using aromatic diamines contained in the mol% ratio of the range.

That is, as the amount of 4,4'-oxydianiline (ODA) constituting the aromatic diamine increases, the flexibility is improved, but the flatness may be decreased. On the contrary, when the amount of p-phenylenediamine (p-PDA) increases, the flatness It is preferable that p-phenylenediamine (p-PDA) and 4,4'-oxydianiline (ODA) are included in the above ratio because it may be excellent but the flexibility is poor.

On the other hand, in addition to p-phenylenediamine (p-PDA) and 4,4'-oxydianiline (ODA), aromatic diamine is m-phenylenediamine (m-PDA) and 2,2-bis (4-4 [amino] Phenoxy] -phenyl) propane (BAPP), 2,2'-dimethyl-4,4'-diaminobiphenyl (m-TB-HG), 1,3-bis (4-aminophenoxy) benzene (TPE -R), 2,2-bis (4- [3-aminophenoxy] phenyl) sulfone (m-BAPS), 4,4'-diaminobenzanilide (DABA), 4,4'-bis (4 It may further comprise one or more selected from -aminophenoxy) biphenyl.

The polyamic acid solution of the present invention is prepared by reacting an aromatic tetracarboxylic acid dianhydride and an aromatic diamine with a polar aprotic solvent, wherein the ratio of the solvent (c) used Restrictive examples include N-methylpyrrolidinone (NMP), N, N-dimethylacetamide (DMAc), tetrahydrofuran (THF), N, N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), Cyclohexane, acetonitrile or a mixture of one or two or more thereof.

Here, the conditions for reacting the aromatic tetracarboxylic dianhydride and the aromatic diamine in the polar aprotic solvent are 2 to 24 hours at a temperature in the range of 0 to 90 ° C, preferably 5 to 50 ° C, under an inert atmosphere such as nitrogen gas. It is good to react to a degree.

The polyamic acid solution of the present invention described above, based on the total weight 100 of the polyamic acid solution, (a) 5 to 15 parts by weight of aromatic tetracarboxylic dianhydride; (b) 5 to 15 parts by weight of aromatic diamine; And (c) 70 to 90 parts by weight of the solvent. If the content range of the aromatic tetracarboxylic dianhydride, aromatic diamine and the solvent contained in the polyamic acid solution is less than the above range, the viscosity of the polyamic acid solution may be too low, on the contrary, if the above range is exceeded, the polyamic acid solution This is because the viscosity may be too high.

Such polyamic acid solutions of the present invention may have a viscosity in the range of about 3,000 to 50,000 cps, preferably about 15,000 to 40,000 cps. If the viscosity of the polyamic acid solution is less than 3,000 cps, it may be difficult to control the thickness when the polyamic acid solution is coated on the copper foil layer. If the polyamic acid solution exceeds 50,000 cps, the coating surface may become uneven when the polyamic acid solution is coated on the copper foil layer. It is preferable to have a viscosity in the range of.

In addition, the polyamic acid solution of the present invention may contain a small amount of additives such as plasticizers, antioxidants, flame retardants, dispersants, viscosity regulators, leveling agents and the like within the range that does not significantly impair the object and effect of the present invention if necessary. .

<Polyimide resin>

In the present invention, the polyamic acid solution may be imidized to prepare a polyimide resin in the form of a random copolymer or a block copolymer. In this case, the prepared polyimide resin is a polymer material containing an imide ring, and is excellent in heat resistance, chemical resistance, abrasion resistance, and electrical properties, as well as excellent in flexibility. Therefore, when the flexible copper foil laminate is manufactured by attaching the polyimide resin to one surface of the copper foil layer, the flexible copper foil laminate may have excellent bendability.

On the other hand, in preparing the polyimide resin by imidating the polyamic acid solution of the present invention, the reaction temperature is preferably about 250 to 400 ° C, and the reaction time is about 5 to 60 minutes.

<Flexible Copper Foil Laminates>

The flexible copper foil laminated board of this invention contains the polyimide resin layer to which the polyimide resin demonstrated above was adhere | attached on the copper foil layer and one surface of the copper foil layer. Specifically, the flexible copper foil laminate of the present invention may be prepared by applying the polyamic acid solution described above to one surface of the copper foil layer and then imidizing to form a polyimide resin layer.

As the copper foil layer, a rolled copper foil or an electrolytic copper foil may be used in consideration of economical efficiency and productivity, and the thickness is not particularly limited, but is preferably 8 to 35 μm, preferably 9 to 18 μm.

In this case, the present invention describes a flexible copper foil laminate comprising a copper foil layer, but imidates the polyamic acid solution described in the present invention on a metal foil layer (eg, tin, gold, silver, etc.) that exhibits conductivity and ductility in addition to the copper foil layer. By forming a polyimide resin layer can be produced a flexible metal foil laminate, this will also fall within the scope of the present invention.

On the other hand, the thickness of the polyimide resin layer adhered to one surface of the copper foil layer is not particularly limited, but is preferably 2 to 60 µm, preferably 3 to 30 µm. Such a polyimide resin layer exhibits a thermal expansion coefficient (CTE) in the range of 10 to 30 ppm / ° C., so that the difference between the copper foil layer and the thermal expansion coefficient is small, so that the polyimide resin layer may exhibit good flatness upon adhesion to the copper foil layer.

In addition, this invention can provide the printed circuit board provided with said flexible copper foil laminated board. Specific examples of the printed circuit board may be a multilayer flexible printed circuit board or a rigid flexible printed circuit board. Since the printed circuit board continuously exhibits excellent performances such as heat resistance, chemical resistance, insulation resistance, and bendability due to the polyimide resin layer in the flexible copper foil laminate, it can contribute to high functionalization and long life of various electronic devices. have.

Hereinafter, the present invention will be described in more detail with reference to Examples. However, the following examples are only preferred examples of the present invention, and the present invention is not limited to the following examples.

Example 1

1-1. Preparation of Polyamic Acid Solution

166 ml of N-methylpyrrolidone (NMP) was added to a four-necked reaction vessel equipped with a thermometer, agitator, nitrogen inlet, and powder dispensing funnel, and stirred. To this solution was added 7.10 g (0.0657 mol) of p-phenylenediamine (p-PDA) and 3.37 g (0.0168 mol) of 4,4'-oxydianiline (ODA), which was stirred at 25 ° C to completely dissolve. To this solution was slowly added 21.74 g (0.0739 mol) of 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride (BPDA) and pyromellitic dianhydride (PMDA) 1.79 g (0.0082 mol). It superposed | polymerized with addition and stirring for 10 hours, and obtained the polymic acid solution of 27,000 cps of viscosity.

1-2. Flexible Copper Clad Laminate Manufacturing

The polyamic acid solution prepared above was coated on the surface of an electrolytic copper foil (EDI-12 of Iljin Material) having a thickness of 12 μm by using a casting method. At this time, the coated thickness was adjusted so that the final polyimide resin layer after the curing process is 20㎛ thickness. The coated polyamic acid solution was then dried for about 20 minutes at several temperatures below 200 ° C. through several steps. Next, the temperature was raised to 400 degreeC, the imidation reaction was advanced, and the flexible copper foil laminated board with a polyimide layer was produced.

[Examples 2 to 5]

After adjusting the content of BPDA, PMDA, p-PDA, ODA as shown in Table 1 below to prepare a polyamic acid solution in the same manner as the polyamic acid solution of Example 1 manufacturing process of the flexible copper foil laminate of Example 1 In the same manner as in the flexible copper foil laminate of Examples 2 to 5 were prepared.

Table 1

[Comparative Examples 1 to 6]

After adjusting the content of BPDA, PMDA, p-PDA, ODA and additives (Talc) as shown in Table 2 below to prepare a polyamic acid solution in the same manner as the polyamic acid solution of Example 1, the ductility of Example 1 In the same manner as the manufacturing process of the copper foil laminate, the flexible copper foil laminates of Comparative Examples 1 to 6 were prepared.

TABLE 2

	Comparative Example 1	Comparative Example 2	Comparative Example 3	Comparative Example 4	Comparative Example 5	Comparative Example 6
BPDA	23.72g	23.72g	23.72g	-	20.62 g	12.73 g
	0.0806mol	0.0806mol	0.0806mol		0.0701 mol	0.0433mol
PMDA	-	-	-	21.45 g	1.70 g	9.44 g
				0.0983mol	0.0078mol	0.0433mol
p-PDA	6.97 g	6.97 g	6.97 g	8.51 g	4.63 g	6.55 g
	0.0645mol	0.0645mol	0.0645mol	0.0787mol	0.0428mol	0.0606mol
ODA	3.31 g	3.31 g	3.31 g	4.04g	7.05 g	5.28g
	0.0165mol	0.0165mol	0.0165mol	0.0202mol	0.0352mol	0.0264mol
Talc	0.00%	0.00%	6.80 g	0.00%	0.00%	0.00%
			20.0%
NMP	166	166	166	166	166	166
Solid content	17.00%	17.00%	19.73%	17.00%	17.00%	17.00%
Copper foil	the year before	Rolling	the year before	the year before	the year before	the year before

[Test Example] Evaluation of Characteristics of Flexible Copper Clad Laminates

In order to evaluate the properties of the flexible copper foil laminates prepared in Examples 1 to 5 and Comparative Examples 1 to 6, the experiment was conducted by the following measuring method, and the results are shown in Table 3.

Copper Foil Peel Strength

In accordance with IPC-TM-650 No. 2, 4, 9, a circuit having a pattern width of 1 mm was formed on the manufactured flexible copper foil laminate, and then the copper foil layer was formed at 90 degrees with respect to the surface of the laminate under a temperature of 25 ° C. The minimum value of the force required for peeling at a rate of 50 mm / min was measured and expressed as copper foil peel strength.

2. Lead bath heat resistance

The flexible copper foil laminated sheet manufactured according to IPC-TM-650 No.2.4.13 was floated in 300 degreeC and 90 sec solder tank, and the appearance condition was confirmed.

3. Number of sliding bends (MIT)

A cover test (PI Film 12 μm, adhesive 25 μm) was bonded to the surface on which the circuit of the manufactured flexible copper foil laminate was formed to prepare a bending test specimen. After mounting the fabricated specimen in the MIT bending test apparatus, the number of times until the mounted specimen was disconnected was measured at a speed of 175 rpm with a jig with a radius of curvature of 0.38 R while being initially pulled with a force of 0.5 Kgf.

4. Slide durable

After forming a circuit having a pattern width of 0.1 mm on the manufactured flexible copper foil laminate, a coverlay (PI Film 12 μm, adhesive 25 μm) was bonded to the surface on which the circuit was formed to prepare a slide durability test specimen. The fabricated specimen was mounted on a jig with a radius of curvature of 0.65R, and the number of times until the resistance value of the mounted specimen was out of the 10% range was measured at a speed of 60 rpm.

5. Curling: Curling of the product

After cutting the flexible copper foil laminate produced 100X100mm after measuring the corner peak at the bottom is bad if more than 25mm, 15-25mm range is usually 15mm or less is good.

TABLE 3

	Copper Peel Strength (kgf / cm)	Lead bath heat resistance	Sliding bends (MIT)	Slide durability	Flatness (Curl)
Example 1	0.95	No change	9,000 times	200,000 times	usually
Example 2	1.10	No change	9,500	260,000 times	usually
Example 3	1.15	No change	9,000 times	230,000 times	good
Example 4	1.05	No change	7,500 times	190,000 times	good
Example 5	1.05	No change	7,000 times	160,000 times	good
Comparative Example 1	0.90	No change	9,500	230,000 times	Bad
Comparative Example 2	0.70	No change	12,000 times	340,000 times	Bad
Comparative Example 3	1.30	No change	6,500	100,000 times	good
Comparative Example 4	0.70	No change	4,000 times	90,000 times	good
Comparative Example 5	1.20	No change	10,500 times	210,000 times	Bad
Comparative Example 6	0.80	No change	6,000 times	120,000 times	good

Looking at Table 3, Examples 1 to 5 of the present invention can be confirmed that the flatness is better than Comparative Examples 1 to 6, but the number of sliding bends is about 9000 or more times (in the past, 7,000 or more times was excellent) excellent flexibility. there was. In particular, Example 3, in which the content of 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride (BPDA) and pyromellitic dianhydride (PMDA) is properly adjusted, has good flatness and high sliding. It can be seen that the number of bending.

However, Comparative Examples 1 and 2 using only 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride (BPDA) had a high number of sliding bends, indicating good flexibility but poor flatness. Comparative Example 4 using only metician dianhydride (PMDA) was good in flatness, but it was confirmed that the flexibility is less because the number of sliding bends.

In addition, Comparative Example 5 in which the contents of 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride (BPDA) and 4,4'-oxydianiline (ODA) are relatively out of the scope of the present invention. Has a high number of sliding bends, good flexibility but poor flatness, on the contrary, Comparative Example 6 in which the content of pyromellitic dianhydride (PMDA) and p-phenylenediamine (p-PDA) is outside the scope of the present invention. The flatness was good, but the number of sliding bends was low, and the flexibility was confirmed to be inferior.

In addition, Comparative Example 3 containing an inorganic filler had good flatness, but it was confirmed that the flexibility was inferior due to the small number of sliding bends.

The polyamic acid solution according to the present invention is an aromatic tetracarboxylic with a controlled content of 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride (BPDA) and pyromellitic dianhydride (PMDA). Since dianhydride is used, it is possible to prepare a polyimide resin having excellent heat resistance, chemical resistance, and electrical properties as well as flexibility.

In addition, the polyimide resin described above has a small difference in coefficient of thermal expansion with copper foil, and thus, when the flexible copper foil laminate is manufactured using the polyimide resin, the flatness (Curl) is good, so that the productivity of the flexible copper foil laminate may be improved, and the flexibility may be improved. Since the excellent polyimide resin is used, the flexibility of the flexible copper foil laminate produced can also be excellent.

Claims (9)

1. (a) 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride (3,3', 4,4'-biphenyltetracarboxylic acid dianhydride (BPDA) and pyromellitic dianhydride, Aromatic tetracarboxylic acid dianhydride including PMDA);

   (b) aromatic diamines; And

   (c) A polyamic acid solution comprising an organic solvent.
2. The method of claim 1,

   The aromatic terracarboxylic dianhydride (a) is 60 to 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride (BPDA) and pyromellitic dianhydride (PMDA). 90: polyamic acid solution, characterized in that it comprises in a mol% ratio of 40 to 10 range.
3. The method of claim 1,

   The aromatic diamine (b) is a polyamic acid solution comprising p-phenylenediamine (p-PDA) and 4,4'-oxydianiline (4,4'-oxydianiline, ODA) .
4. The method of claim 3,

   The aromatic diamine (b) is a polya comprising p-phenylenediamine (p-PDA) and 4,4'-oxydianiline (ODA) in a mol% ratio ranging from 60 to 80:40 to 20. Mic acid solution.
5. The method of claim 3,

   The aromatic diamine (b) is m-phenylenediamine (m-PDA), 2,2-bis (4-4 [aminophenoxy] -phenyl) propane (BAPP), 2,2'-dimethyl-4,4 '-Diaminobiphenyl (m-TB-HG), 1,3-bis (4-aminophenoxy) benzene (TPE-R), 2,2-bis (4- [3-aminophenoxy] phenyl) Polya further comprising at least one selected from sulfone (m-BAPS), 4,4'-diaminobenzanilide (DABA), 4,4'-bis (4-aminophenoxy) biphenyl Mic acid solution.
6. The method of claim 1,

   Based on the total weight of the polyamic acid solution 100,

   (a) 5 to 15 parts by weight of aromatic tetracarboxylic acid dianhydride;

   (b) 5 to 15 parts by weight of aromatic diamine; And

   (c) a polyamic acid solution comprising 70 to 90 parts by weight of the solvent.
7. The polyimide resin manufactured by imidating the polyamic-acid solution in any one of Claims 1-6.
8. Copper foil layer; And

   The flexible copper foil laminated board containing the polyimide resin layer which the polyimide resin of Claim 7 adhere | attached on one surface of the said copper foil layer.
9. The printed circuit board containing the flexible copper foil laminated board of Claim 8.