JPH10265572A - Circuit board, suspension board with circuit and their production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a circuit board having an insulating layer comprising a polyimide resin on a metal foil board, small in the linear expansion coefficient of the polyimide resin, wherein the linear expansion coefficient is near to that of the metal foil board, and thereby not causing the generation of cracks in the resin layer, the peeling of the resin layer and further the generation of curvature, and to provide a circuit-having suspension board using the same. SOLUTION: This circuit board has an insulating layer comprising a polyimide resin on a metal foil board. Therein, the polyimide resin is a polyimide resin obtained by reacting (A) aromatic diamines comprising (a) p- phenylenediamine and (b) 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl with (B) 3,4,3',4'-biphenyltetracarboxylic dianhydride. The suspension board with a circuit is obtained by forming a prescribed circuit comprising a conductive layer on the circuit board by a patterning technique.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circuit board, a suspension board with a circuit, and a method for manufacturing the same, and more particularly, to a circuit board having an insulating layer made of a polyimide resin on a metal foil substrate, and such a circuit board. The present invention relates to a suspension board with circuit provided with a pattern circuit formed of a conductor layer thereon, and a method of manufacturing the same.

For example, in a magnetic disk device such as a hard disk device used as an external storage device of a computer or the like, in order to perform magnetic recording and reproduction, the magnetic disk and the magnetic head are moved relatively, and air generated by the magnetic disk is generated. It is necessary to elastically press the magnetic head against the magnetic disk against the flow, and to maintain a certain minute gap between the magnetic head and the magnetic disk. Thus, the suspension is a magnetic head supporting device that elastically presses the magnetic head against the magnetic disk against the airflow. The present invention is a circuit board that can be suitably used for manufacturing such a suspension board with a circuit,
The present invention relates to a suspension board with a pattern circuit formed by forming a circuit made of a conductor layer on such a circuit board by a patterning technique, and a method of manufacturing the same.

[0003]

2. Description of the Related Art In recent years, as a thin-film multilayer circuit board for high-density mounting of semiconductors and high-speed signal processing, a circuit board provided with an insulating layer made of a polyimide resin on a metal foil has been used. However, conventionally, generally, polyimide resin used as an insulating material has a higher linear thermal expansion coefficient than various metal foils, so that a circuit board may be cracked or a resin layer may be peeled off.
Also, warpage may occur.

[0004] On the other hand, a computer and a storage device as its peripheral device are required to be reduced in size and price while improving the capacity.
Hard disk drive technology is making significant strides. In magnetic heads, compared to the conventional metal-in-gap (MIG), recently, thin-film magnetic heads (TFH) in which the coil portion is thinned, and thin-film magnetic heads that are both readable and writable and have a remarkably large storage capacity. -The development of a magnetoresistive composite head (MR) is urgent.

However, according to the conventional technique of forming a required wiring by arranging a conductor on a suspension board, the conductor affects the elasticity of the suspension and causes a variation in the flying height. In some cases, contact with the magnetic disk may reduce the durability of the magnetic disk device.

Therefore, in recent years, a suspension in which an electric circuit is formed directly on a suspension board on which a head is mounted has been put to practical use. However, as described above, according to the conventional circuit board in which a polyimide resin is used as the insulating layer, the finally obtained suspension is also caused by the polyimide resin having a larger coefficient of linear thermal expansion than the metal foil base material. Then, insulation failure and warpage occur,
May cause poor performance. Furthermore, conventionally known polyimide resins are inferior in adhesiveness between polyimide resins.
There is also a problem that it is difficult to form a ray (coating layer).

[0007]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems in a conventional circuit board having an insulating layer made of a polyimide resin on a metal foil and a suspension board with a circuit using the same. The coefficient of linear thermal expansion is close to various metal foils,
It is an object of the present invention to provide a circuit board that does not cause cracking or peeling of the resin layer and does not warp, a suspension board with a circuit using the same, and a method of manufacturing the same.

[0008]

According to the present invention, there is provided a circuit board having an insulating layer made of a polyimide resin on a metal foil substrate, wherein the polyimide resin is (A) (a) p-phenylenediamine, And (b) an aromatic diamine consisting of 2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl, and (B) 3,4,3 ', 4'-biphenyltetracarboxylic dianhydride And a polyimide resin obtained by the reaction with

More specifically, the polyimide resin is
(A) an aromatic diamine consisting of (a) p-phenylenediamine and (b) 2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl; and (B) 3,4,3 ' A polyimide resin obtained by reacting a polyimide resin precursor obtained from 4,4'-biphenyltetracarboxylic dianhydride in the presence of a photosensitive agent.

In the method for producing a circuit board according to the present invention, a film made of a photosensitive polyimide resin precursor is formed on a metal foil substrate, exposed, heated after exposure, developed, heated and imidized by heating. Wherein the photosensitive polyimide resin precursor comprises (A) (a) p-phenylenediamine, and (b) 2,2'-bis (trifluoromethyl ) An aromatic diamine comprising -4,4'-diaminobiphenyl, and (B) 3,4,
It is characterized in that a photosensitive agent is blended with a polyamic acid obtained by reaction with 3 ', 4'-biphenyltetracarboxylic dianhydride.

According to this method, a coating made of a photosensitive polyimide resin precursor is exposed on a metal foil substrate in accordance with a predetermined pattern, heated after exposure, and developed to form a predetermined pattern made of the precursor. By forming it and finally heating it to a high temperature for imidization, a circuit board having an insulating layer made of a patterned polyimide resin can be obtained.

The suspension with circuit according to the present invention comprises:
Having an insulating layer made of a polyimide resin on a metal foil substrate,
In a suspension board with circuit having a pattern circuit comprising a conductor layer thereon, the polyimide resin is a polyimide resin obtained by the reaction between the aromatic diamine and tetracarboxylic dianhydride.

The method of manufacturing a suspension with a circuit according to the present invention is a method of manufacturing a suspension board with a circuit, comprising forming a pattern circuit made of a conductor layer on an insulating layer made of a polyimide resin of the circuit board. A resin precursor is obtained by mixing a photosensitive agent with a polyamic acid obtained by reacting the aromatic diamine with a tetracarboxylic dianhydride. That is,
In this method, a circuit board having an insulating layer made of a predetermined patterned polyimide resin is formed, and then a pattern circuit made of a conductor layer is formed on the insulating layer to obtain a suspension board with a circuit. Things.

[0014]

According to the present invention, in a circuit board having an insulating layer made of a polyimide resin on a metal foil substrate, the polyimide resin is (A) (a) p-phenylenediamine

[0015]

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And (b) 2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl

[0017]

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An aromatic diamine comprising: (B) 3,4,
3 ', 4'-biphenyltetracarboxylic dianhydride

[0019]

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Is a polyimide resin obtained by the reaction with

In the present invention, the metal foil substrate is not particularly limited, but is usually a stainless steel foil, a copper foil,
Aluminum foil, copper-beryllium foil, phosphor bronze foil, 42
An alloy foil or the like is used. Further, according to the present invention, a long object is preferably used for such a metal foil substrate. That is, an insulating layer made of a polyimide resin is provided on a long metal foil base material so as to repeat a predetermined pattern, and a required pattern circuit made of a conductor layer is formed on each of the patterned insulating layers, thus. Finally, by cutting the metal foil base material for each individual pattern circuit, a suspension board with individual circuits can be obtained.

Therefore, according to the present invention, the circuit board is preferably prepared by applying a solution of the photosensitive polyimide resin precursor onto a long metal foil substrate, usually a long stainless steel foil, and drying it. After forming the film, the film is exposed to ultraviolet light through a mask having a predetermined pattern, heated (heated after exposure), developed, and then heat-cured (polyimide of the polyamic acid). Thus, it can be obtained by forming a predetermined pattern made of a polyimide resin and using this as an insulating layer.

The above-mentioned photosensitive polyimide resin precursor is prepared by mixing the above-mentioned aromatic diamine and tetracarboxylic dianhydride in a substantially equimolar ratio with an appropriate organic solvent such as N, N-dimethylacetamide or N-methyl. A liquid composition in which polyamic acid (polyamic acid) is produced by reacting in 2-pyrrolidone or the like, and a photosensitive agent is added thereto.

According to the present invention, the proportion of p-phenylenediamine as the component (a) in the aromatic diamine is in the range of 50 to 70 mol%, preferably 55 to 65 mol%, and (b) ) The component 2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl has a proportion of 50-3.
0 mol%, preferably in the range of 45-35 mol%, and according to the present invention, such proportions of the two aromatic diamines can be combined with 3,3 ′, 4,4′-biphenyltetracarboxylic acid diamine. When used together with the anhydride, a polyimide resin having a low coefficient of linear thermal expansion can be obtained. The polyimide resin according to the present invention usually has a coefficient of linear thermal expansion of 10 to 20 ppm.
In the range.

In the present invention, the ratio (mol%) of the component (a) and the component (b) in the aromatic diamine is as follows:
The mole numbers of the component (a) and the component (b) are a and b, respectively.
Where (a / (a + b)) × 100 and (b / (a + b)) × 100, respectively.

Further, the polyimide resin according to the present invention has excellent adhesiveness between the polyimide resins. Therefore, in the production of a suspension board with circuit, when forming a cover lay, a product having excellent reliability can be obtained without delamination of the resin at a portion where the polyimide resin is bonded to each other. As the photosensitive agent, as described in detail in JP-A-6-75376,
General formula (I)

[0027]

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(Wherein X ¹ to X ⁴ each independently represent a hydrogen atom, a fluorine atom, a nitro group, a methoxy group, an amino group, a dialkylamino group, a cyano group or a fluoroalkyl group, and Y ¹ represents a cyano group or it indicates the formula -COR ^3, Y ² represents a cyano group or the general formula -COR ^4, wherein, R ³ and R ⁴ each independently represent an alkyl group or an alkoxy group having 1 to 4 carbon atoms, an anilino group, toluidino group, a benzyloxy group, an amino group or a dialkylamino group, R ^1, R ² and R ⁵ each independently represent a hydrogen atom or an alkyl group having 1 to 3 carbon atoms .R ¹ and R ^3,
R ² and R ⁴ can be a 5-membered ring, a 6-membered ring or a membered ring capable of forming a heterocyclic ring containing a keto group. )) Is used.

As specific examples, for example, 4-o-nitrophenyl-3,5-dimethoxycarbonyl-2,6-dimethyl-1,4-dihydropyridine (hereinafter referred to as nifedipine), 4-o-nitrophenyl- 3,5-dimethoxycarbonyl-2,6-dimethyl-1-methyl-4-hydropyridine (hereinafter referred to as N-methyl form), 4-o-nitrophenyl-3,5-diacetyl-1,4-dihydropyridine (Hereinafter, simply referred to as acetyl form). These may be used alone or as a mixture of two or more. If necessary, an appropriate amount of imidazole is used as a dissolution aid for the developer.

In the present invention, the dihydropyridine derivative is usually used in an amount of 0.05 to 0.5 based on 1 mol part of the total amount of the aromatic diamine and the aromatic tetracarboxylic dianhydride.
It is used in the molar part range. Imidazole is also used, if necessary, usually in an amount of 0.1 part by weight based on the total amount of 1 mol of the diamine containing the aromatic diamine and the aromatic tetracarboxylic dianhydride.
It is used in the range of 0.5 to 0.5 mole part.

Such a photosensitive polyimide resin precursor is coated with a solution on an appropriate substrate, dried, exposed to ultraviolet rays (irradiation with ultraviolet rays), and then heated (heat after exposure). ) To form a positive or negative latent image and develop it to obtain a positive or negative image, that is, a required pattern. Therefore, if this is finally heated to a high temperature to imidize the polyamic acid,
A pattern coating made of a polyimide resin can be obtained.

More specifically, the photosensitive polyimide resin precursor varies somewhat depending on the type of photosensitizer used, but when the temperature of the post-exposure bake is relatively low at around 140 ° C., the exposed portion is not developed. Dissolves in the developer to form a positive image, while when the temperature of the post-exposure heating is relatively high at about 170 ° C. or higher, the unexposed portion dissolves in the developer to form a negative image. Form.

As the developer, an aqueous solution of an organic alkali such as tetramethylammonium hydroxide or the like or an aqueous solution of an inorganic alkali such as sodium hydroxide or potassium hydroxide is usually used. Usually, the alkali concentration is suitably in the range of 2 to 5% by weight. If necessary,
The alkaline aqueous solution includes methanol, ethanol, n
-Lower aliphatic alcohols such as propanol and isopropanol may be added. The amount of alcohol added is usually
It is 50% by weight or less. The development temperature is usually 25
A range of -50 ° C is appropriate.

According to the photosensitive polyimide resin precursor used in the present invention, when the temperature of the post-exposure baking is relatively low at around 140 ° C., the imino group at one position of the dihydropyridine derivative is present in the unexposed area. Forming a hydrogen bond between the hydrogen and the carboxyl group of the polyamic acid,
The hydrophilicity of the polyimide resin and the diffusion rate of the coating film to the developer are reduced, and as a result, the dissolution rate of the coating film in the developer is reduced. The dihydropyridine derivative is converted to a basic pyridine compound, which forms a weak salt structure with the polyamic acid, resulting in an increased hydrophilicity of the coating and an increased dissolution rate in the developer. As described above, since the dissolution rate of the exposed portion in the developer is higher than that of the unexposed portion, the coating after exposure, heating after exposure, and development gives a positive image.

On the other hand, according to the photosensitive polyimide resin precursor used in the present invention, the post-exposure heating temperature is about 170 ° C.
When the temperature is relatively high, the unexposed portion has a lower rate of dissolution of the coating film in the developer, as in the case where the temperature of the post-exposure heating is relatively low, around 140 ° C. ,
In the exposed part, the dihydropyridine derivative is changed into a basic pyridine compound by exposure, which promotes the polyimidization of the polyamic acid and reduces the dissolution rate of the film in the developer, and at the same time, the pyridine compound itself is also exposed. The post-heating changes the compound into a more insoluble cyclized compound and promotes the conversion of the polyamic acid into a polyimide. As a result, the solubility of the coating in the exposed portion in the developer is further reduced as compared with the unexposed portion. As described above, when the heating temperature after the exposure is a relatively high temperature of about 170 ° C. or more, since the dissolution rate of the exposed part in the developer is significantly smaller than that of the unexposed part, the exposure, the post-exposure heating and The coating after development gives a negative working image.

According to the present invention, a solution of the above-described photosensitive polyimide resin precursor is applied to a long metal foil base material, and dried by heating to form a precursor coating film. Exposure to a predetermined pattern by irradiating ultraviolet rays through, heating after exposure, and development, preferably, after forming a negative image having a predetermined pattern, heat-curing this, to cause an imidization reaction Thus, the circuit board according to the present invention can be obtained by forming an insulating layer made of a polyimide resin. As described above, in order to heat and polyimide the polyimide resin precursor, it is preferable to coat the coating under vacuum or under an inert gas atmosphere at 350 to 40.
It is preferable to heat to about 0 ° C. for several hours.

Thereafter, a predetermined circuit composed of a conductor layer having a predetermined pattern is formed on the insulating layer according to a conventional method, required terminals are formed, and then a long metal foil base material is formed. By chemically cutting into the shape of
The suspension board with circuit according to the present invention can be obtained.

According to the present invention, an amino group-containing bifunctional polysiloxane may be used, if necessary, as a part of the diamine component in order to improve the adhesion of the obtained polyimide resin to the substrate. . Specific examples of such an amino group-containing bifunctional polysiloxane include, for example, a compound represented by the general formula (II):

[0039]

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(Wherein, R ¹ represents an alkylene group having 1 to 18 carbon atoms, R ² represents an alkyl group having 1 to 18 carbon atoms, and n is an integer of 1 to 100). Can be mentioned. Such an amino group-containing bifunctional polysiloxane is used in an amount of 10 mol% or less of the diamine component.

In the present invention, the ratio (mol%) of the amino group-containing bifunctional polysiloxane is such that the mole numbers of the aromatic diamine (a) component and (b) component are a and b, respectively, When the number of moles of the bifunctional polysiloxane is c, it is defined as (c / (a + b + c)) × 100.

Particularly, in the present invention, in the general formula (I), R ¹ is preferably an alkylene group having 1 to 7 carbon atoms, and specific examples thereof include methylene, ethylene, propylene, butylene and hexylene. And the like. R ² has 1 to 1 carbon atoms
It is preferably an alkyl group of 7, and as a specific example,
For example, alkyl groups such as methyl, ethyl, propyl, butyl, hexyl and the like can be mentioned. N is preferably 1 to 40. Among them, bis (aminopropyl) tetramethyldisiloxane is preferably used as the amino-functional bifunctional polysiloxane.

Next, a suspension board with circuit according to the present invention is manufactured by forming a circuit board as described above and then forming a pattern circuit comprising a conductor layer on an insulating layer made of a polyimide resin in accordance with a conventional method of patterning technology. After the required terminals are formed, the stainless steel foil is finally cut out into a required shape including the insulating layer, whereby a suspension board with individual circuits can be obtained.

As described above, according to the present invention, a required processing is performed on a circuit board having an insulating layer made of a polyimide resin having a high elongation as described above to form a suspension board with a circuit. Even if it is severely bent, no crack occurs in the polyimide resin, and therefore, poor insulation does not occur. Moreover, according to the present invention, as described above, precise patterning can be performed with high sensitivity and high contrast, so that the suspension board with circuit can be reduced in capacity and size.

Hereinafter, a suspension board with circuit according to the present invention and its manufacture will be described in detail with reference to the drawings.

FIG. 1 is a perspective view showing an example of a suspension board with circuit 1 according to the present invention, and an insulating layer (not shown) made of a polyimide resin on a stainless steel foil substrate 2.
And a predetermined pattern circuit made of the copper conductor layer 3 is formed thereon as a thin film. At the tip, a gimbal 4 is formed integrally with the substrate by cutting into the substrate, and a slider (not shown) having a magnetic head thereon
Is fixed. Required terminals 5 and 6 are formed at the front and rear ends, respectively. However, FIG. 1 shows a state in which a coating layer (cover lay) for covering and protecting the surface of the substrate is peeled off.

FIG. 2 is a cross-sectional view taken along the line AA in FIG. 1 and has an insulating layer 7 made of a polyimide resin on the stainless steel foil substrate 2 and a chromium thin film 23 on the insulating layer 7. A predetermined pattern circuit composed of the copper conductor layer 3 is formed as a thin film. This conductor layer is protected by a coating made of a nickel thin film 28, and furthermore, a terminal 5
Are formed. The entire surface except the terminals is covered and protected by the covering layer 8.

FIG. 3 is a cross-sectional view taken along the line BB in FIG. 1, and has an insulating layer 7 made of a polyimide resin on the stainless steel foil base material 2, and a chromium thin film 23 on the insulating layer 7. A predetermined pattern circuit composed of the copper conductor layer 3 is formed as a thin film. This conductor layer is protected by a coating made of a nickel thin film 28 and further protected by a coating layer 8.

The long stainless steel foil substrate 2 usually has a thickness of 10 to 60 μm, preferably 15 to 30 μm and a width of 50 to 500 m from the viewpoint of vibration characteristics.
m, preferably in the range of 125 to 300 mm. However, it is not limited to these.

FIGS. 4 and 5 show steps of manufacturing a circuit board according to the present invention, and FIGS. 6 to 16 show steps of manufacturing a suspension with circuit according to the present invention.

First, as shown in FIG. 4, the photosensitive polyimide is coated on the entire surface of the stainless steel foil substrate 2 as described above so that the thickness of the obtained resin layer is 2 to 20 μm, preferably 5 to 10 μm. Apply the solution of the resin precursor and apply 60
~ 150 ° C, preferably heated at 80-120 ° C,
The coating 21 of the photosensitive polyimide resin precursor is formed.

Next, the coating of the photosensitive polyimide resin precursor is irradiated with ultraviolet rays through an appropriate mask to expose the coating to a predetermined pattern. Here, the integrated exposure light amount is 100
１０００1000 mJ / cm ² , preferably 200 to 700
mJ / cm ² , and the exposure wavelength is usually 300
-450 nm, preferably in the range of 350-420 nm. After this exposure, the coating is heated at a temperature of 80 to 200 ° C., preferably 120 to 180 ° C. for about 2 to 10 minutes (post-exposure heating), and then developed. In the present invention, it is preferable to obtain a negative image. After this,
The thus-obtained pattern coating of the polyimide resin precursor is heated to a high temperature to be polyimide, and thus,
As shown in FIG. 5, a patterned insulating layer 22 made of a polyimide resin is formed on a stainless steel foil substrate 2 to obtain a circuit board according to the present invention.

Next, as shown in FIG. 6, a stainless steel foil substrate 2 having a patterned polyimide insulating layer 22 is formed.
A chromium thin film 23 and a copper thin film 24 are successively formed on the entire surface by sputtering. The chromium thin film 23 is useful for bringing the copper thin film 24 into close contact with the insulating layer 22 made of polyimide. Here, the film thickness is 10
0-600 angstroms, copper thin film 500-200
A range of 0 Å is preferred. The surface resistance of the copper thin film thus obtained is usually 0.6Ω / □ or less.

Thereafter, as shown in FIG.
4 is subjected to electrolytic copper plating with a thickness of about 2 to 15 μm to form a conductor layer 25 made of copper. In FIG. 7, the chromium thin film is not shown.

Next, as shown in FIGS. 8 and 9, after exposure and development are performed by a patterning technique using a liquid photoresist 26 or a dry film laminate according to a conventional method, the copper conductor layer 25 in the non-pattern portion is formed.
Is removed by etching, and thus the predetermined conductor pattern 27 made of copper is formed on the insulating layer 22 made of the polyimide resin. Here, it is preferable to etch copper by alkali etching.

After the copper conductor layer in the non-pattern portion is removed by etching, the chromium thin film 23 is further removed by etching, and as shown in FIG. Is obtained. For the etching of the chromium thin film 23, for example, a potassium ferricyanide-based etchant or an etchant such as potassium permanganate or sodium metasilicate-based etchant is used.

After the unnecessary chromium thin film on the base material is removed in this manner, electroless nickel plating is performed.
As shown in FIG. 11, a hard nickel thin film 28 is formed on the surface of the copper conductor layer 27 and the surface of the stainless steel foil substrate 2 to cover and protect the surface of the copper conductor layer. Therefore, the thickness of the nickel plating may be such that the lower copper conductor layer is not exposed, and is generally in the range of 0.05 to 0.1 μm.

Thereafter, the conductor pattern 27 in the wiring portion is covered and protected by using the above-mentioned photosensitive polyimide resin precursor, and a terminal is formed in a required terminal portion, and the surface is similarly covered except for this. Protect and form a cover layer (cover lay). In FIG. 12 and subsequent figures, the left side of the substrate shows the formation of the wiring portion, and the right side shows the formation of the terminal portion.

That is, as shown in FIG.
The conductor pattern 27 is covered with a polyimide resin 29. In the terminal portion, the terminal portion is left by patterning and a lead portion 30 for forming the terminal by electrolytic plating.
Leaving, using the photosensitive polyimide resin precursor,
Perform the same coating, exposure, post-exposure heating, development and heat curing (imidization) as described above, and coat with polyimide resin,
The coating layer 31 is formed.

Next, as shown in FIG. 13, in the terminal portion, first, the electroless nickel plating thin film 28 (see FIG. 11) which protected the surface of the conductor pattern 27 was peeled off, and 2 is also removed. Thereafter, the stainless steel foil base material, the conductor pattern 27, and the polyimide resin coating layer 31 are coated with a resist by a method using a normal photoresist, leaving only the terminal portion, according to a conventional method. Nickel plating 32 and electrolytic gold plating 33
Are sequentially performed to form the terminals 34. Here, the thicknesses of the electrolytic nickel plating and the electrolytic gold plating are both 1
About 5 μm is appropriate. Thereafter, the resist is removed.

Next, as shown in FIG. 14, in the conductor pattern 27 on which the terminals 34 are formed, the lead portions 30 (see FIG. 12) used for the electrolytic plating are removed by chemical etching. The removal of copper and chromium from the lead portion may be performed by the same method as described above. In this manner, after the lead portion is removed, in order to cut out the stainless steel foil base material 2 into a required shape by chemical etching, exposure and development are performed using a photoresist 35 or a dry film laminate according to a conventional method. As shown in FIG. 15, after a required pattern is formed on the stainless steel foil substrate 2, the stainless steel foil substrate is cut out into a required shape by etching.
Here, as an etching solution, for example, ferric chloride,
An aqueous solution of cupric chloride or the like is used.

After this etching treatment, if the substrate is washed with pure water and dried, the suspension board with circuit 1 according to the present invention can be obtained as shown in FIG. That is, the suspension board with circuit has an insulating layer 22 made of a polyimide resin on the stainless steel foil substrate 2,
A conductive pattern 27 made of a thin film of a conductive layer, that is, a pattern circuit is provided thereon, and the entire surface except for the terminals 34 is covered and protected by a coating layer 31 made of a polyimide resin.

[0063]

As described above, the circuit board according to the present invention comprises a metal foil substrate and a predetermined ratio of two kinds of aromatic diamines and 3,4,3 ', 4'-biphenyltetracarboxylic acid. Having a polyimide resin layer obtained by reaction with dianhydride as an insulating layer, and since this polyimide resin has a linear thermal expansion coefficient close to the metal foil, the resin layer does not crack or does not peel off. Further, no warping occurs. Therefore, also in the suspension board with circuit according to the present invention, the resin layer does not crack, the resin layer does not peel off, and the warpage does not occur.

[0064]

EXAMPLES The present invention will be described below with reference to examples.
The present invention is not limited by these examples.

Example 1 0.386 kg (3.57 mol) of p-phenylenediamine and
0.832 kg (2.60 mol) of 2,2′-bis (trifluoromethyl) -4,4′-diaminobiphenyl and 0.081 kg (0.31 kg) of bis (aminopropyl) tetramethyldisiloxane
3 mol) (total 6.5 mol of diamine component) and 3,4,3 ', 4'-
1.912 kg (6.5 mol) of biphenyltetracarboxylic dianhydride (diphthalic dianhydride) was dissolved in 19.72 kg of dimethylacetamide and stirred at room temperature for 72 hours. Thereafter, the temperature was raised to 75 ° C., and when the viscosity reached 5,000 centipoise, the heating was stopped, and the mixture was left to cool to room temperature and cooled. Then, 0.9633 kg of Nifedipine (2.7
8 mol), 0.6422 kg (2.04 mol) of the acetyl form and 0.161 kg (2.36 mol) of imidazole were added,
A solution of a photosensitive polyimide resin precursor was prepared.

A 25 μm thick stainless steel (SUS30
4) The solution of the photosensitive polyimide resin precursor was applied on a foil by a continuous coater for a long time, and then heated and dried at 120 ° C. for 2 minutes to form a film of the photosensitive polyimide resin precursor. Then, through a mask, the exposure amount is 700 mJ / cm.
^After irradiating with ultraviolet light at ^{2 and} heating at 160 ° C. for 3 minutes, development processing was carried out to form a negative image, and further 0.01 Torr.
r, heated to 400 ° C. under vacuum to form an insulating layer (thickness: 6 μm) made of a patterned polyimide resin,
A circuit board was obtained.

The thermal expansion coefficient of the polyimide resin film was 16.5 ppm. In the case of general SUS304 stainless steel foil, the coefficient of linear thermal expansion was 17 ppm. Here, the coefficient of linear thermal expansion is 2 mm in width, 6 μm in thickness, and 3 in length.
A 0 mm sample was measured by a TMA method (thermal mechanical analysis method) at a heating rate of 10 ° C./min and a load of 5 g.

Next, chromium and copper were deposited on the insulating layer made of polyimide of such a circuit board by continuous sputtering at 500 Å and 1000 Å, respectively.
A thin film was formed with a thickness of Å. The surface resistance of the copper thin film was 0.3 to 0.4Ω / □. Next, after attaching a light adhesive sheet as a plating mask to the back surface of the stainless steel base material, copper sulfate electrolytic plating was performed on the entire surface of the copper thin film to form a 10 μm-thick copper-plated conductor layer.

Thereafter, a commercially available dry film laminate was laminated on the conductor layer at 110 ° C. in accordance with a conventional method, and then this was exposed at an exposure amount of 80 mJ / cm ² and developed to remove the copper conductor layer in the non-pattern portion. The conductor layer was patterned by alkali etching so as to leave the lead portion of the electrolytic plating together with the wiring portion and the terminal portion, and then the resist was removed. Next, the thus treated stainless steel foil was immersed in a mixed aqueous solution of potassium ferricyanide and sodium hydroxide at 25 ° C. to remove the unnecessary chromium thin film.

Thereafter, the stainless substrate was subjected to ordinary electroless plating to form a nickel thin film having a thickness of about 0.5 μm on the entire surface of the stainless steel foil including the conductor layer and the insulating layer.
Next, as described above, a required coating layer was formed on the wiring portion and the terminal portion of the conductor layer on the stainless steel foil using the photosensitive polyimide resin precursor in the same manner as described above. Next, the substrate was immersed in a nitric acid-based release agent at room temperature to remove the electroless plating thin film on the terminal portion and the stainless steel foil.

After that, according to a conventional method, except for the above-mentioned terminal portions, coating with a normal photoresist was performed, and then the above-mentioned terminal portions were sequentially subjected to electrolytic nickel plating and electrolytic gold plating.
Each terminal was formed by forming a plating layer having a thickness of 1 μm. Thereafter, the resist was stripped. Subsequent to this plating, copper alkaline etching and chromium etching were performed in the same manner as described above to remove the lead portion used for plating from the conductor layer.

After the plating lead portion is removed from the conductor layer in this manner, exposure and development are performed using a photoresist or a dry film laminate in accordance with a conventional method in order to cut out the stainless steel foil substrate into a required shape. Go,
After the required pattern was formed on the stainless steel foil, the stainless steel foil substrate was immersed in a ferric chloride etching solution at 45 ° C., and cut into a required shape. This was sufficiently washed with pure water and then dried to obtain individually cut out suspension boards with circuits.

According to the suspension board with circuit obtained in this manner, the polyimide resin has a small coefficient of linear thermal expansion, and furthermore has excellent adhesiveness between the polyimide resins. No delamination occurs between the substrate and the substrate, and the reliability is high. Further, since there is no warpage, there is no occurrence of poor performance or the like.

Example 2 0.386 kg (3.57 mol) of p-phenylenediamine and
0.832 kg (2.60 mol) of 2,2′-bis (trifluoromethyl) -4,4′-diaminobiphenyl and 0.081 kg (0.31 kg) of bis (aminopropyl) tetramethyldisiloxane
3 mol) (total 6.5 mol of diamine component) and 3,4,3 ', 4'-
1.912 kg (6.5 mol) of biphenyltetracarboxylic dianhydride (diphthalic dianhydride) was added to N-methyl-2-
The compound was dissolved in 19.72 kg of pyrrolidone and stirred at room temperature for 72 hours. Thereafter, the temperature was raised to 75 ° C., and when the viscosity reached 5,000 centipoise, the heating was stopped, and the mixture was left to cool to room temperature and cooled. Then add 0.9633 kg of nifedipine
(2.78 mol), 0.6422 kg (2.04 mol) of the acetyl form and 0.161 kg (2.36 mol) of imidazole were added to prepare a solution of a photosensitive polyimide resin precursor.

A 25 μm thick stainless steel (SUS30
4) The solution of the photosensitive polyimide resin precursor was applied on a foil by a continuous coater for a long time, and then heated and dried at 120 ° C. for 2 minutes to form a film of the photosensitive polyimide resin precursor. Then, through a mask, the exposure amount is 700 mJ / cm.
^After irradiating with ultraviolet light at ^{2 and} heating at 160 ° C. for 3 minutes, development processing was carried out to form a negative image, and further 0.01 Torr.
r, heated to 400 ° C. under vacuum to form an insulating layer (thickness: 6 μm) made of a patterned polyimide resin,
A circuit board was obtained. The thermal expansion coefficient of the polyimide resin film measured in the same manner as in Example 1 was 16.5 ppm.

Next, using this circuit board, the first embodiment
By the same procedure as described above, a suspension board with circuit was obtained. In this suspension board with circuit, since the polyimide resin has a small coefficient of linear thermal expansion and also has excellent adhesiveness between polyimide resins, cracks occur in the resin layer and delamination between the substrate and the base material. , And high reliability, and no warping occurs.

Example 3 0.421 kg (3.90 mol) of p-phenylenediamine and
0.832 kg (2.60 mol) of 2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl (total 6.5 mol of diamine components) and 3,4,3 ', 4'-biphenyltetra 1.912 kg (6.5) of carboxylic dianhydride (diphthalic dianhydride)
Mol) was dissolved in 19.72 kg of N-methyl-2-pyrrolidone and stirred at room temperature for 72 hours. Thereafter, the temperature was raised to 75 ° C., and when the viscosity reached 5,000 centipoise, the heating was stopped, and the mixture was left to cool to room temperature and cooled. Next, 0.9633 kg (2.78 mol) of nifedipine and an acetyl form
0.6422 kg (2.04 mol) and 0.16 of imidazole
1 kg (2.36 mol) was added to prepare a solution of a photosensitive polyimide resin precursor.

A 25 μm thick stainless steel (SUS30
4) The solution of the photosensitive polyimide resin precursor was applied on a foil by a continuous coater for a long time, and then heated and dried at 120 ° C. for 2 minutes to form a film of the photosensitive polyimide resin precursor. Then, through a mask, the exposure amount is 700 mJ / cm.
^After irradiating with ultraviolet light at ^{2 and} heating at 160 ° C. for 3 minutes, development processing was carried out to form a negative image, and further 0.01 Torr.
r, heated to 400 ° C. under vacuum to form an insulating layer (thickness: 6 μm) made of a patterned polyimide resin,
A circuit board was obtained. The thermal expansion coefficient of the polyimide resin film measured in the same manner as in Example 1 was 16.0 ppm.

Next, using this circuit board, the first embodiment
By the same procedure as described above, a suspension board with circuit was obtained. In this suspension board with circuit, since the polyimide resin has a small coefficient of linear thermal expansion and also has excellent adhesiveness between polyimide resins, cracks occur in the resin layer and delamination between the substrate and the base material. , And high reliability, and no warping occurs.

Example 4 0.421 kg (3.90 mol) of p-phenylenediamine and
0.624 kg (1.95 mol) of 2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl and 0.161 kg (0.66 kg) of bis (aminopropyl) tetramethyldisiloxane
5 mol) (total 6.5 mol of diamine component) and 3,4,3 ', 4'-
1.912 kg (6.5 mol) of biphenyltetracarboxylic dianhydride (diphthalic dianhydride) was dissolved in 19.72 kg of dimethylacetamide and stirred at room temperature for 72 hours. Thereafter, the temperature was raised to 75 ° C., and when the viscosity reached 5,000 centipoise, the heating was stopped, and the mixture was left to cool to room temperature and cooled. Then, 0.9633 kg of Nifedipine (2.7
8 mol), 0.6422 kg (2.04 mol) of the acetyl form and 0.161 kg (2.36 mol) of imidazole were added,
A solution of a photosensitive polyimide resin precursor was prepared.

A 25 μm thick stainless steel (SUS30
4) The solution of the photosensitive polyimide resin precursor was applied on a foil by a continuous coater for a long time, and then heated and dried at 120 ° C. for 2 minutes to form a film of the photosensitive polyimide resin precursor. Then, through a mask, the exposure amount is 700 mJ / cm.
^After irradiating with ultraviolet light at ^{2 and} heating at 160 ° C. for 3 minutes, development processing was carried out to form a negative image, and further 0.01 Torr.
r, heated to 400 ° C. under vacuum to form an insulating layer (thickness: 6 μm) made of a patterned polyimide resin,
A circuit board was obtained. The thermal expansion coefficient of the polyimide resin film measured in the same manner as in Example 1 was 17.5 ppm.

Next, using this circuit board, Example 1
By the same procedure as described above, a suspension board with circuit was obtained. In this suspension board with circuit, since the polyimide resin has a small coefficient of linear thermal expansion and also has excellent adhesiveness between polyimide resins, cracks occur in the resin layer and delamination between the substrate and the base material. , And high reliability, and no warping occurs.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an example of a suspension board with circuit according to the present invention.

FIG. 2 is a sectional view taken along line AA in FIG.

FIG. 3 is a sectional view taken along line BB in FIG.

FIG.

FIG.

FIG.

FIG.

FIG.

FIG.

FIG.

FIG.

FIG.

FIG.

FIG.

FIG. 15 and

FIG. 16 is a fragmentary cross-sectional view showing a manufacturing step of the suspension board with circuit according to the present invention;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Suspension board with a circuit, 2 ... Stainless steel foil base, 3 ... Conductor layer, 4 ... Gimbal, 5 and 6 ... Terminal, 7 ...
Insulating layer, 8: coating layer, 21: coating of photosensitive polyimide resin precursor, 22: insulating layer of polyimide resin, 23: chromium thin film, 24: copper thin film, 25: conductor layer,
26 ... photoresist, 27 ... conductor pattern, 28 ... nickel thin film, 29 ... polyimide resin, 30 ... lead part,
31: polyimide resin coating layer, 33: electrolytic gold plating thin film, 34: terminal, 35: photoresist.

Claims (22)

[Claims] 1. A circuit board having an insulating layer made of a polyimide resin on a metal foil substrate, wherein the polyimide resin comprises (A) (a) p-phenylenediamine, and (b) 2,2'-bis (tri A polyimide resin obtained by reacting an aromatic diamine consisting of (fluoromethyl) -4,4'-diaminobiphenyl with (B) 3,4,3 ', 4'-biphenyltetracarboxylic dianhydride A featured circuit board. 2. A circuit board having an insulating layer made of a polyimide resin on a metal foil substrate, wherein the polyimide resin comprises (A) (a) p-phenylenediamine and (b) 2,2'-bis (tri The presence of a photosensitizer is obtained by mixing an aromatic diamine consisting of (fluoromethyl) -4,4'-diaminobiphenyl and a polyimide resin precursor obtained from (B) 3,4,3 ', 4'-biphenyltetracarboxylic dianhydride A circuit board characterized by being a polyimide resin obtained by reacting below. 3. A method according to claim 1, wherein the photosensitive agent has the general formula (I): (Wherein a hydrogen atom from X ¹ X ⁴ are each independently a fluorine atom, a nitro group, a methoxy group, an amino group, a dialkylamino group, a cyano group or a fluorinated alkyl group, Y ¹
Represents a cyano group or a general formula —COR ³ , Y ² represents a cyano group or a general formula —COR ⁴ , wherein R ³ and R ⁴
Each independently represent an alkyl group or an alkoxy group having 1 to 4 carbon atoms, an anilino group, a toluidino group, a benzyloxy group, an amino group or a dialkylamino group, R ¹ is,
R ² and R ⁵ each independently represent a hydrogen atom or a carbon atom
3 represents an alkyl group. R ¹ and R ³ , R ² and R ⁴ can be a 5-membered ring, a 6-membered ring or a heterocyclic-forming member ring containing a keto group. The circuit board according to claim 2, wherein 4. A photosensitizer comprising 4-o-nitrophenyl-3,5-
Dimethoxycarbonyl-2,6-dimethyl-1,4-dihydropyridine, 4-o-nitrophenyl-3,5-diacetyl-1,4-dihydropyridine and 4-o-nitrophenyl-3,5-dimethoxycarbonyl-2, 6-dimethyl-1
The circuit board according to claim 2, which is at least one dihydropyridine derivative selected from -methyl-4-hydropyridine. 5. The circuit board according to claim 1, wherein the component (a) is 50 to 70 mol% and the component (b) is 50 to 30 mol% in the aromatic diamine (A). . 6. A compound of the general formula (II) (Wherein, R ¹ represents an alkylene group having 1 to 18 carbon atoms, R ² represents an alkyl group having 1 to 18 carbon atoms, and n is an integer of 1 to 100). 6. The circuit board according to claim 1, wherein the polysiloxane is used in an amount of 10 mol% or less of the total diamine component comprising the aromatic diamine and the amino group-containing bifunctional polysiloxane. 7. A film made of a photosensitive polyimide resin precursor is formed on a metal foil substrate, exposed, heated after exposure, developed, and then heated and imidized to form a polyimide resin. In the method for producing a circuit board having an insulating layer, the photosensitive polyimide resin precursor may be (A) (a) p
-Phenylenediamine, and (b) an aromatic diamine consisting of 2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl; and (B) 3,4,3 ', 4'-biphenyltetracarboxylic acid A method for producing a circuit board, comprising mixing a photosensitive agent with a polyamic acid obtained by a reaction with an acid dianhydride. 8. The photosensitizer of the formula (I) (Wherein a hydrogen atom from X ¹ X ⁴ are each independently a fluorine atom, a nitro group, a methoxy group, an amino group, a dialkylamino group, a cyano group or a fluorinated alkyl group, Y ¹
Represents a cyano group or a general formula —COR ³ , Y ² represents a cyano group or a general formula —COR ⁴ , wherein R ³ and R ⁴
Each independently represent an alkyl group or an alkoxy group having 1 to 4 carbon atoms, an anilino group, a toluidino group, a benzyloxy group, an amino group or a dialkylamino group, R ¹ is,
R ² and R ⁵ each independently represent a hydrogen atom or a carbon atom
3 represents an alkyl group. R ¹ and R ³ , R ² and R ⁴ can be a 5-membered ring, a 6-membered ring or a heterocyclic-forming member ring containing a keto group. The method for manufacturing a circuit board according to claim 7, wherein 9. A photosensitizer comprising 4-o-nitrophenyl-3,5-
Dimethoxycarbonyl-2,6-dimethyl-1,4-dihydropyridine, 4-o-nitrophenyl-3,5-diacetyl-1,4-dihydropyridine and 4-o-nitrophenyl-3,5-dimethoxycarbonyl-2, 6-dimethyl-1
The method for producing a circuit board according to claim 7, wherein the method is at least one kind of dihydropyridine derivative selected from -methyl-4-hydropyridine. 10. The aromatic diamine (A) comprises 50 to 70 mol% of the component (a) and 50 to 30 mol% of the component (b).
The method for manufacturing a circuit board according to any one of claims 7 to 9, wherein 11. A compound of the general formula (II) (Wherein, R ¹ represents an alkylene group having 1 to 18 carbon atoms, R ² represents an alkyl group having 1 to 18 carbon atoms, and n is an integer of 1 to 100). 11. The method for producing a circuit board according to claim 7, wherein the polysiloxane is used in an amount of 10 mol% or less of the total diamine component comprising the aromatic diamine and the amino group-containing bifunctional polysiloxane. 12. A suspension board with a circuit having an insulating layer made of a polyimide resin on a metal foil base material and a pattern circuit made of a conductor layer thereon, wherein the polyimide resin is (A) (a) p- Phenylenediamine, and
(b) an aromatic diamine comprising 2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl; and (B) 3,4,
A suspension board with a circuit, which is a polyimide resin obtained by a reaction with 3 ', 4'-biphenyltetracarboxylic dianhydride. 13. A suspension board with a circuit having an insulating layer made of a polyimide resin on a metal foil base material and a pattern circuit made of a conductor layer thereon, wherein the polyimide resin is (A) (a) p- Phenylenediamine, and
(b) an aromatic diamine comprising 2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl; and (B) 3,4,
A suspension board with a circuit, characterized by being a polyimide resin obtained by reacting a polyimide resin precursor obtained from 3 ', 4'-biphenyltetracarboxylic dianhydride in the presence of a photosensitive agent. 14. A photosensitive agent represented by the general formula (I): (Wherein a hydrogen atom from X ¹ X ⁴ are each independently a fluorine atom, a nitro group, a methoxy group, an amino group, a dialkylamino group, a cyano group or a fluorinated alkyl group, Y ¹
Represents a cyano group or a general formula —COR ³ , Y ² represents a cyano group or a general formula —COR ⁴ , wherein R ³ and R ⁴
Each independently represent an alkyl group or an alkoxy group having 1 to 4 carbon atoms, an anilino group, a toluidino group, a benzyloxy group, an amino group or a dialkylamino group, R ¹ is,
R ² and R ⁵ each independently represent a hydrogen atom or a carbon atom
3 represents an alkyl group. R ¹ and R ³ , R ² and R ⁴ can be a 5-membered ring, a 6-membered ring or a heterocyclic-forming member ring containing a keto group. 14. The suspension board with circuit according to claim 13, which is represented by the following formula: 15. A photosensitizer comprising 4-o-nitrophenyl-3,5.
-Dimethoxycarbonyl-2,6-dimethyl-1,4-dihydropyridine, 4-o-nitrophenyl-3,5-diacetyl-1,4-dihydropyridine and 4-o-nitrophenyl-3,5-dimethoxycarbonyl-2 , 6-dimethyl-
The suspension board with circuit according to claim 13, which is at least one kind of dihydropyridine derivative selected from 1-methyl-4-hydropyridine. 16. The aromatic diamine (A) comprises 50 to 70 mol% of the component (a) and 50 to 30 mol% of the component (b).
The suspension board with circuit according to any one of claims 12 to 15, wherein 17. A compound of the general formula (II) (Wherein, R ¹ represents an alkylene group having 1 to 18 carbon atoms, R ² represents an alkyl group having 1 to 18 carbon atoms, and n is an integer of 1 to 100). 17. The suspension board with circuit according to claim 12, wherein the polysiloxane is used in an amount of 10 mol% or less of the total diamine component comprising the aromatic diamine and the amino group-containing bifunctional polysiloxane. 18. A film comprising a photosensitive polyimide resin precursor is formed on a metal foil substrate, exposed, heated after exposure,
Developing, after this, it is heated and imidized to form a circuit board having an insulating layer made of a polyimide resin, and then a suspension board with circuit for forming a pattern circuit made of a conductor layer on the insulating layer. In the production method, the photosensitive polyimide resin precursor may be (A) (a) p-
Phenylenediamine, (b) an aromatic diamine consisting of 2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl, and (B) 3,4,3 ', 4'-biphenyltetracarboxylic acid A method for producing a suspension board with circuit, characterized in that a photosensitive agent is blended with a polyamic acid obtained by a reaction with a dianhydride. (19) a photosensitive agent represented by the general formula (I): (Wherein a hydrogen atom from X ¹ X ⁴ are each independently a fluorine atom, a nitro group, a methoxy group, an amino group, a dialkylamino group, a cyano group or a fluorinated alkyl group, Y ¹
Represents a cyano group or a general formula —COR ³ , Y ² represents a cyano group or a general formula —COR ⁴ , wherein R ³ and R ⁴
Each independently represent an alkyl group or an alkoxy group having 1 to 4 carbon atoms, an anilino group, a toluidino group, a benzyloxy group, an amino group or a dialkylamino group, R ¹ is,
R ² and R ⁵ each independently represent a hydrogen atom or a carbon atom
3 represents an alkyl group. R ¹ and R ³ , R ² and R ⁴ can be a 5-membered ring, a 6-membered ring or a heterocyclic-forming member ring containing a keto group. 19. The method of manufacturing a suspension board with circuit according to claim 18, wherein 20. A photosensitizer comprising 4-o-nitrophenyl-3,5.
-Dimethoxycarbonyl-2,6-dimethyl-1,4-dihydropyridine, 4-o-nitrophenyl-3,5-diacetyl-1,4-dihydropyridine and 4-o-nitrophenyl-3,5-dimethoxycarbonyl-2 , 6-dimethyl-
The method for producing a suspension board with a circuit according to claim 18, wherein the method is at least one kind of dihydropyridine derivative selected from 1-methyl-4-hydropyridine. 21. In the aromatic diamine (A), the component (a) is 50 to 70 mol%, and the component (b) is 50 to 30 mol%.
21. The method for manufacturing a suspension board with circuit according to claim 18, wherein 22. A compound of the general formula (II) (Wherein, R ¹ represents an alkylene group having 1 to 18 carbon atoms, R ² represents an alkyl group having 1 to 18 carbon atoms, and n is an integer of 1 to 100). 22. The production of the suspension board with circuit according to claim 18, wherein the polysiloxane is used in an amount of 10 mol% or less of the total diamine component comprising the aromatic diamine and the amino group-containing bifunctional polysiloxane. Method.