JP2746550B2 - Polyamic acid and polyimide - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to polyamic acids and polyimides, and more particularly to materials having a low dielectric constant.

[0002]

2. Description of the Related Art The arithmetic processing speed of a large-scale computer has been steadily increasing due to an increase in the speed of elements and an increase in the density of a mounting system. In response to this, there is an increasing demand for lowering the dielectric constant of the insulating material used for the signal layer of the mounting board. The reason is that the lower the dielectric constant of the insulating film, the lower the signal propagation delay due to the relationship shown in the following equation (III), and as a result, the higher the processing speed can be expected.

Td = l√ε (III) Td: signal propagation delay time l: circuit constant ε: relative dielectric constant of insulating layer As a specific measure, ceramics conventionally used for the insulating layer (ε ≒ 10) Is being replaced with an organic material (ε = 2 to 6). As the material, attention is focused on a polyimide resin described in, for example, US Pat. No. 3,179,634, which has excellent heat resistance that can withstand a thin film process at the time of manufacturing a mounting substrate, and a post process such as chip connection and pin attachment. I have.

[0004] Among these, as a polyimide having a low relative dielectric constant, THERmid FA-7001 (Kanebo uenu SSC) has a value of ε = 2.95 (10 kHz, catalog value), which is the lowest among commercially available products. Have a value.

[0005]

However, even in the case of the above-mentioned polyimide resin, a resin having a lower relative dielectric constant has been demanded in accordance with an increase in the processing speed. In other words, as a material suitable for a substrate requiring high-speed signal processing, such as a thin-film multilayer substrate for a computer, or an insulating layer of an element, a material having a low dielectric constant and excellent heat resistance is required. .

SUMMARY OF THE INVENTION An object of the present invention is to provide a substrate and an insulating layer of an element which have a lower dielectric constant than conventional ones, have the same heat resistance as conventional ones, and require high-speed signal processing. And a method for manufacturing the same.

[0007]

The object of the present invention is to provide a polyamic acid comprising a repeating unit represented by the following general formula (I) or a polyimide comprising a repeating unit represented by the following general formula (II):

[0008]

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[0009]

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Ar ₁ is

[0011]

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Ar ₂ is at least one group selected from the group consisting of

[0013]

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This is attained by thermosetting a polyamic acid or polyimide, which is at least one group selected from the groups, to form a film.

This polyamic acid or polyimide is prepared by diamine and tetracarboxylic dianhydride in a polar solvent such as N, N-dimethylacetamide, N, N-dimethylformamide, N-methyl-2-pyrrolidone, diglyme, etc. May be produced by a polymerization reaction of

As the above diamine,

[0017]

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At least one selected from the above is used.

The tetracarboxylic dianhydride includes:

[0020]

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At least one selected from the above is used.

[0022]

Embodiments of the present invention will be described below in detail.

<Example 1> A 500 mL four-necked flask serving as a reaction vessel was equipped with a stirring rod with a blade, a cooling pipe, and a N ₂ gas introduction pipe, and then flowed dry N ₂ gas. When the inside of the flask was sufficiently replaced with N ₂ gas, 150 g of dehydrated and distilled N, N-dimethylacetamide was added, and 29.526 g of an aromatic diamine represented by the following formula (IV):
(69.6 mmol) and completely dissolved.

[0024]

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Thereafter, the flask is placed in a cold water bath, and an equimolar amount of tetracarboxylic dianhydride represented by the following formula (V) is added little by little so that the temperature of the reaction solution does not exceed 40 ° C .: At this time, the above tetracarboxylic dianhydride attached to the reaction vessel wall is added while washing with 50 g of N, N-dimethylacetamide.

[0026]

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After that, the mixture was stirred at room temperature for 6 hours, the temperature of the reaction solution was raised to 70 ° C. using an oil bath, and the mixture was stirred for 4 hours. Thus, a polyamic acid varnish was obtained.

This varnish had a solid content of 20 wt% and a viscosity of 1.1 Pa · s.

Next, the varnish was subjected to pressure filtration using a Teflon filter having a pore size of 2 μm to remove foreign substances, and as shown in FIG. Spin coated on top. Next, the substrate was imidized by heat treatment at 200 ° C. for 30 minutes and further at 350 ° C. for 30 minutes, and a polyimide film 3 having a thickness of 5 μm was formed.
Was formed.

Further, an upper Al electrode 4 having a thickness of 2 μm is formed on the polyimide film 3 by mask vapor deposition. A sample was prepared.

Using this sample, the capacitance of the polyimide film 3 was measured with an LCZ meter 4277A manufactured by Yokogawa Hewlett-Packard Co., Ltd., and the relative dielectric constant ε was obtained using the following equation (VI). The measurement frequency used was 10 kHz.

[0032] (C: capacitance, d: sample thickness, ε ₀ : vacuum dielectric constant,
(S: upper electrode area) At this time, ε is 2.6, which is smaller than that of the conventional polyimide.
It was a sufficiently low value.

Further, in the same manner as in the film for measuring ε, a polyimide film formed by thermosetting on a silicon wafer was used, and the glass transition temperature (Tg) and the thermal decomposition onset temperature (TG) were respectively set to ( DSC- manufactured by Vacuum Riko Co., Ltd.
It measured using 1500M and TGD-500RH. As a result, it was confirmed that Tg = 320 ° C. and TG = 440 ° C., which have high heat resistance.

<Example 2> By the same reaction as in Example 1, No. 2 in FIG. 1 to No. 6 and No. 3 in FIG. 7 ~
No. As shown in No. 8, a polyamic acid precursor → a polyimide film was produced. The evaluation of ε, Tg, and TG was performed in the same manner. As in Example 1, the ε was sufficiently lower than that of the conventional polyimide, and both Tg and TG showed high values.

<Comparative Example> Example 1 was performed using a polyamic acid varnish (trade name: PIQ, manufactured by Hitachi Chemical Co., Ltd.).
, Tg, TG
Was measured. ε = 3.4, Tg = 310 ° C., TG = 46
The temperature was 0 ° C. and the heat resistance was excellent, but ε was higher than that of the present invention.

[0036]

According to the present invention, since a polyimide resin having a low ε and a high heat resistance can be obtained, a substrate or a device which requires high-speed signal processing, such as a thin film multilayer substrate for a computer, is required. Use of this material for the layer has the effect of improving the signal processing speed.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing an outline of a cross-sectional shape of a sample for ε measurement formed in Example 1 of the present invention.

FIG. 2 is a chart showing a polyimide produced in Example 2.

FIG. 3 is a chart showing a polyimide produced in Example 2.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Glass substrate, 2 ... Lower Al electrode, 3 ... Polyimide film, 4 ... Upper Al electrode.

Claims (2)

(57) [Claims] 1. A polyamic acid comprising a repeating unit represented by the following general formula (I): Ar ₁ is Ar ₂ is a group represented by the following formula: A polyamic acid, which is any one of the above groups. 2. A polyimide comprising a repeating unit represented by the following general formula (II): Ar ₁ is Is any of the radicals, Ar ₂ is embedded image A polyimide, which is any one of the above groups.