JP3171427B2 - Method of manufacturing thick film pattern conductor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a thick film pattern conductor which requires high reliability, high density and low resistance wiring. In particular, it manufactures components such as coils for ultra-small and high-performance flat motors and optical pickups, circuit boards including finely arranged parts of LSIs, and connection circuit components for high-definition display elements typified by liquid crystal displays. The present invention relates to a method for producing a thick film pattern conductor suitable for production.

[0002]

2. Description of the Related Art With the demand for higher performance, the number of pins of an LSI (Large Scale Integrated Circuit) and the like having higher performance is increasing, and the pitch of the pins is becoming narrower. In addition, as seen in liquid crystal displays, as the demand for higher definition has increased, the number of display scanning lines has increased, and at the same time the wiring intervals have become extremely narrow, making it difficult to mount ICs for controlling display. ing.

Under such technical trends, high-density and low-density components for connecting components having greatly different circuit wiring intervals, for example, ICs and LSIs having pins with narrow pitches to a motherboard (which has a large circuit wiring interval). There is a growing demand for resistance different pitch connection parts. Although there is a document defining such a part as “interposer”, (Nikkei Electronics 1995.16 (No. 626) 7
(Pages 9 to 86) In the present invention, this is referred to as a different pitch connection part.

[0004] A high-density and low-resistance thick-film pattern conductor has a small wiring pitch and at the same time a large cross-sectional area of the conductor.
That is, a high conductor height is required. For example, as described in the sixth Microelectronics Symposium, pages 43 to 46, when the CPU is operated at a high-speed operation clock frequency, the required performance of the different-pitch connection parts is determined by the attenuation of the signal pulse as the wiring resistance increases. There is a report that can be seen. Further, when the wiring resistance of the connection between the control IC for the high-definition liquid crystal display element and the liquid crystal substrate increases, S
It is said that the / N ratio is lowered and the image becomes unstable.

As a conventional method of manufacturing a thick film pattern conductor, a method capable of combining copper-clad substrate, photolithography and etching is known. Other methods of forming a thick film pattern conductor include, for example, Japanese Patent Application Laid-Open Nos. 52-137666 and 57-162489.
Japanese Patent Application Laid-Open No. 55-41729 discloses a method of filling a resist pattern with a thick film paste material, and a method of exposing and developing a mixture of a thick film paste and a positive resist. Japanese Patent Application Laid-Open No. Sho 59-198792 discloses a method for producing a thick film pattern conductor by repeating resist lamination / exposure on a conductive substrate, followed by development and electrolytic plating. Also, JP-A-56-946
No. 90 and JP-A-60-161605 disclose a method of forming a fine pattern circuit by anisotropic electrolytic plating by combining a conductive substrate and photolithography.

In addition, the present inventors disclosed a method for forming a high-density and low-resistance conductor pattern using a liquid photosensitive resin in Japanese Patent Application Laid-Open No. 6-283830 with respect to the technique of forming a fine pattern conductor.

[0007]

However, in the conventional thick film pattern conductor, it is extremely difficult to suppress the side etch phenomenon at the time of etching the copper foil. Reliability decreases. Further, as the height of the conductor increases, that is, as the thickness of the copper foil increases, this phenomenon becomes more remarkable. Therefore, the thickness of the copper foil of a commonly used copper-clad board is 18 to 35 μm.
However, the limit is a wiring density of about 20 lines / mm, that is, a wiring pitch of about 50 μm.

[0008] In the thick film pattern conductor obtained by another method of forming a thick film pattern conductor, pores are generated in the conductor when the paste is baked, and as a result, circuit characteristics are deteriorated due to an increase in conductor resistance. Occur. JP-A-59-198792
Although it is expected that a resist pattern having a relatively high aspect ratio can be obtained in the publication, the process is complicated, defects are introduced due to misalignment at the time of lamination / exposure, and a resist shape defect occurs, resulting in a short circuit in the circuit. There are many problems. Further, Japanese Patent Application Laid-Open Nos.
In the method of JP-A-161605, the conductor design is controlled by the plating start width, and since the cross-sectional shape of the conductor is spherical, the thickness cannot be increased with respect to the width of the conductor. A high-density, low-resistance patterned conductor cannot be manufactured. Further, JP-A-6-283830
In the case of forming a conductor pattern obtained in Japanese Unexamined Patent Publication (Kokai) No. H11 (1995) with a higher density and a lower resistance, a residue of the photosensitive resin may remain in an unexposed portion, and the conductor pattern may be partially disconnected. It was difficult to produce a stable product.

In any of these methods, a low-resistance, high-density thick-film pattern conductor having a conductor wiring pitch of 50 μm or less and a conductor aspect ratio of 1.0 or more is difficult to manufacture at good productivity and at low cost. Further, a thick film pattern conductor having a conductor wiring pitch of 20 μm or less and a conductor aspect ratio of 1.5 or more has not been substantially obtained. Therefore, the present invention provides a high-density, low-resistance pattern conductor by forming a circuit with a high aspect ratio conductor and a small conductor-to-conductor distance. It is an object of the present invention to provide a method for manufacturing a manufactured product.

[0010]

Means for Solving the Problems The present inventors have applied a liquid photosensitive resin to the surface of a conductive substrate, exposed it through a photomask, and removed an unexposed portion of the liquid photosensitive resin by development. Forming a resin pattern, performing electroplating on the portion from which the liquid photosensitive resin has been removed to form a conductor pattern, transferring the formed conductor pattern onto an insulating substrate, and then removing the conductive substrate. Process
In a method of manufacturing a thick film pattern conductor including a portion having a minimum wiring pitch of 50 μm or less and an aspect ratio of the conductor of 1.0 or more, the surface diffuse reflectance of the liquid photosensitive resin of the conductive substrate in a photosensitive wavelength region To 20% or less can solve the problem, and have accomplished the present invention. In the present invention, the term “minimum wiring pitch” is generally defined as a circuit wiring board having various wiring pitches on the same substrate, but having the smallest wiring pitch.

A specific method for obtaining a thick film pattern conductor is as follows: (1) a step of controlling the surface diffuse reflectance of the conductive substrate to 20% or less; and (2) coating a liquid photosensitive resin on the surface of the conductive substrate. (3) exposing and developing a photosensitive resin through a predetermined photomask to form a resin pattern; (4) forming a pattern conductor by electrolytic plating on a portion where the liquid photosensitive resin has been removed. Step (5) of transferring the formed pattern conductor onto an insulating substrate, and then removing the conductive substrate.

The conductive substrate used in the present invention is not particularly limited, but a substrate made of aluminum, copper, zinc or the like is preferably used. It is essential that the surface diffuse reflectance of the conductive substrate used in the present invention is 20% or less. In the case of 20% or less, the liquid photosensitive resin photo-curing of the light shielding portion of the photomask due to the reflection of light on the substrate surface is suppressed, and the resin residue can be extremely reduced. The occurrence of plating adhesion failure and the like during formation is extremely small, and stable production can be performed. Basically, the smaller the surface diffuse reflectance, the better.

The surface diffuse reflectance of the substrate defined here is:
This is the diffuse reflectance of the liquid photosensitive resin used in the photosensitive wavelength range. When the surface diffuse reflectance of the substrate exceeds 20%,
Since the diffuse reflection of the incident light on the substrate surface increases, the bottom of the unexposed portion of the resin pattern (the portion close to the substrate surface) is hardened, and as a result, fogging occurs in the pattern or residues remain. Therefore, a resin pattern for obtaining a high-density patterned conductor having a wiring density of 50 μm or less and an aspect ratio of the conductor of 1.0 or more cannot be obtained.

The value of the surface diffuse reflectance can be measured using a spectrophotometer having an integrating sphere with the surface diffuse reflectance of a barium sulfate standard white plate as a control (100%). As a method for treating the surface of the conductive substrate, a physical surface polishing means has been conventionally used. However, the surface diffuse reflectance of the substrate obtained by this method is as large as about 40%, and a desired resin pattern cannot be obtained. Was.

As a result of intensive studies, the present inventors have used a substrate controlled to a substrate surface diffuse reflectance of 20% or less, which is obtained by chemical surface treatment alone or by combining conventional physical polishing and chemical surface treatment. As a result, it has been found that a desired resin pattern can be obtained. Although the specific substrate surface treatment method varies depending on the substrate, for example, in the case of an aluminum substrate, an aluminum substrate such as an MBV method, an EW method, an arosin method, a zinc phosphate method, a potassium permanganate method, an iron chloride method, and a zincate treatment method. A surface treatment method can be suitably used. In the case of a copper substrate, a blackening process or the like can be used. Table 4 shows specific surface treatment conditions used in the present invention.

The actinic light source used in the exposure and development steps is preferably a parallel light source. In the case of a parallel light source, a resin pattern having a rectangular resist pattern shape and a higher aspect ratio can be obtained. The liquid photosensitive resin used in the present invention is not particularly limited, but is disclosed in JP-A-6-283.
No. 830 can be suitably used. Specifically, the concentration of the ethylenically unsaturated bond is 10 ⁻² to
2 × 10 ^-4 mol / g and molecular weight of 500 to 1000
It is a liquid photosensitive resin composition comprising a prepolymer or oligomer having an ethylenically unsaturated bond of 00 and an ethylenically unsaturated compound monomer.

The composition ratio of these components is such that 1 to 200 parts by weight of the monomer is added to 100 parts by weight of the total of the prepolymer or oligomer. Preferably, the monomer is 10 to 100 parts by weight, more preferably 30 to 70 parts by weight.
Parts by weight. If necessary, a photopolymerization initiator and a thermal polymerization inhibitor may be added. 005-5.0
It is selected from the range of parts by weight.

In the present invention, the concentration of ethylenically unsaturated bonds in the prepolymer or oligomer is 10 ^-2 to 2 × 1.
0 ^-4 mol / g is preferred. If the ethylenically unsaturated bond concentration exceeds 10 ^-2 mol / g, the mechanical strength and elongation of the cured resin after exposure are reduced, cracks occur, and less than 2 × 10 ^-4 mol / g. In this case, since the photocrosslinking is not sufficiently performed, a remarkable decrease in resolution is caused.

The molecular weight is preferably from 500 to 100,000, more preferably from 500 to 50,000.
It is. If the molecular weight is less than 500, the flowability of the liquid photosensitive resin is too high to form a thick resin pattern, and if it exceeds 100000, the developability after exposure is significantly reduced, and high resolution Photosensitive resin cannot be obtained. Examples of the oligomer or prepolymer used in the present invention include unsaturated polyesters, unsaturated polyurethanes, oligoester acrylates or oligoester methacrylates, unsaturated polyamides, unsaturated polyimides, unsaturated polyethers, and unsaturated polyethers. Examples thereof include saturated polyacrylates or unsaturated polymethacrylates, various modified products and mixtures thereof, and various rubber compounds having a carbon-carbon double bond. Among these, unsaturated polyesters or unsaturated polyurethanes are preferable examples of obtaining an image having a large ratio of the height to the width of the image (aspect ratio).

Examples of the unsaturated polyesters include unsaturated dibasic acids such as maleic acid, fumaric acid and itaconic acid or anhydrides thereof and ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, glycerin, trimethylolpropane. Polyester reacted with polyhydric alcohol such as pentaerythritol, 1,4-polybutadiene having terminal hydroxyl group, hydrogenated or non-hydrogenated 1,2-polybutadiene, butadiene-styrene copolymer, butadiene-acrylonitrile copolymer Succinic acid, a part of the acid component,
Adipic acid, phthalic acid, isophthalic acid, phthalic anhydride,
Examples thereof include polyesters substituted with a saturated polybasic acid such as trimellitic acid, and polyesters modified with a drying oil fatty acid or a semi-dry oil fatty acid.

Examples of the unsaturated polyurethanes include the above-mentioned polyhydric alcohols and polyester polyols,
Polyols such as polyether polyols, 1,4-polybutadiene having a terminal hydroxyl group, hydrogenated or non-hydrogenated 1,2-polybutadiene, butadiene-styrene copolymer, butadiene-acrylonitrile copolymer, and tolylene diisocyanate , Diphenylmethane, 4, 4 '
-Compounds in which unsaturated groups are introduced by utilizing the reactivity of terminal isocyanate groups or hydroxyl groups of polyurethanes derived from polyisocyanates such as diisocyanate and hexamethylene diisocyanate. That is, an unsaturated group is introduced by reacting a compound having active hydrogen such as a hydroxyl group, a carboxyl group, or an amino group with an isocyanate, or an unsaturated group is introduced by a reaction between a carboxyl group and a hydroxyl group, or And the like in which unsaturated polyesters of the above are linked by polyisocyanates.

The ethylenically unsaturated monomers include:
Known types of compounds can be used. For example, acrylic acid,
As an unsaturated carboxylic acid such as methacrylic acid or an ester thereof, for example, linear alkyl, cycloalkyl, alkyl halide, alkoxylalkyl, hydroxyalkyl, aminoalkyl, tetrahydrofurfuryl,
Acrylates and methacrylates having allyl, glycidyl, benzyl, phenoxy, etc. groups, alkylene glycol, polyoxyalkylene glycol mono- or diacrylates and methacrylates, trimethylolpropane triacrylate and methacrylate, and pentaerythritol tri- Or tetraacrylate and methacrylate.

Further, as acrylamide, methacrylamide or derivatives thereof, for example, acrylamide and methacrylamide N-substituted or N, N'-substituted with alkyl or hydroxyalkyl, N, N'-alkylenebisacrylamide and methacrylamide, etc. Is raised. The monomer can be detected by liquid chromatography or gas chromatography.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to embodiments. The present invention is not limited by the embodiments.

[0025]

Example 1 Toyo Aluminum Co., Ltd., thickness 100 μm
m aluminum substrate was subjected to surface treatment at 30 ° C. for 80 seconds using AZ401 zincate treatment solution manufactured by Uemura Kogyo Co., Ltd. As a result of measuring the surface diffuse reflectance at 365 nm of the obtained aluminum substrate with an MPS-2000 spectrophotometer manufactured by Shimadzu Corporation, it was found to be 19%. Next, propylene glycol, diethylene glycol and adipic acid, isophthalic acid, and fumaric acid are each in a molar ratio of 0.12 / 0.38 / 0.24 / 0.12 / 0.
Unsaturated polyester resin 1 obtained by condensation at a ratio of 14
In 00 parts, diethylene glycol dimethacrylate 12
Parts, tetraethylene glycol dimethacrylate 30
Parts, 2-hydroxyethyl methacrylate 12 parts, diacetone acrylamide 6 parts, benzoin isobutyl ether 2 parts, 4-tert-butyl catechol 0.03
And stirred and mixed well to obtain a liquid photosensitive resin.

The prepared liquid photosensitive resin was applied to the above-treated aluminum substrate using an SR-B apparatus manufactured by Asahi Kasei Corporation. At this time, each sample was adjusted with a spacer so that the thickness of the resist layer was as shown in Table 1. Mask exposure and development (1% sodium borate solution, 40 ° C., discharge pressure 0.1 kg / cm ² ) are performed using a predetermined glass mask and a parallel light source manufactured by Oak Co., Ltd. A resin pattern having a height of 10 μm or more was formed.

Using a copper pyrophosphate plating solution manufactured by Harshaw Murata Co., a plated copper film is deposited on the obtained resist pattern under the conditions of a current density of the cathode of 3 A / dm ² until the conductor height shown in Table 1 is reached. Then, a patterned conductor was formed.
An adhesive (Cemedine EP008,
EP170) is screen-printed, transferred and bonded on a glass epoxy insulating substrate, and then the aluminum substrate is
The film was removed by etching with hydrochloric acid to obtain a thick film pattern conductor.

The obtained substrate was cut into a 2 cm square, cured with an epoxy resin, mirror-polished on a cross section with a polisher, observed for a pattern shape, and measured for a resistance value per unit length. The results are shown in Table 1. As is clear from the results in Table 1, the thick film pattern conductor obtained in the present invention is:
In each case, it is found that high-density wiring with a minimum wiring pitch of 50 μm or less is possible, and the resistance value per cm is extremely small. Further, using a sample of sample No. 2, a pulse generator (Tektronix TM50)
In 2A), a signal was generated, and the attenuation of the signal after passing through the sample was observed. The resistance of the wiring was low, and the attenuation of the signal was low, and the signal could be transmitted.

[0029]

Example 2 Toyo Aluminum Co., Ltd., thickness 100 μm
m was subjected to various surface treatments shown in Table 2, and the substrate surface diffuse reflectance was measured in the same manner as in Example 1. Next, using a liquid photosensitive resin prepared in the same manner as in Example 1, an exposure / developing apparatus, a pitch of 25 μm and a width of 1
A resin pattern having a thickness of 0 μm and a height of 30 μm was prepared, and a copper conductor having a thickness of 30 μm was deposited using a copper pyrophosphate plating solution manufactured by Harshaw Murata Co., Ltd. under the conditions of a current density of 3 A / dm ^{2 for} the cathode to form a pattern conductor. Formed.

[0030] An adhesive (Cemedine EP008, EP170) was screen-printed on the surface of the obtained substrate, transferred and bonded on a glass substrate, and then the aluminum substrate was 10%
The film was removed by etching with hydrochloric acid to obtain a thick film pattern conductor.
Table 3 shows actual measured values and resistance values of the obtained conductors. In Table 3, sample no. 5 and 6 are implementation exceptions of the present invention. It can be seen that when the surface diffuse reflectance of the aluminum substrate is 20% or more, high-density wiring with a minimum wiring pitch of 50 μm or less is extremely difficult. The plating conductor is not partially deposited due to the fogging phenomenon at the time of exposure and development, and disconnection easily occurs.

On the other hand, the sample No. 7, 8, 9 and 10, the minimum wiring pitch 50
High-density wiring of μm or less was possible.

[0032]

Example 3 Toyo Aluminum Co., Ltd., thickness 100 μm
The current density of the cathode is 3 A / dm ² using a copper plating solution of copper pyrophosphate manufactured by Harshaw Murata Co., Ltd.
Under these conditions, a plated copper film of about 6 μm was formed. This substrate was used in Example 2, Sample No. Buffle polishing was performed under the conditions of 1, and a surface blackening treatment was performed at 85 ° C. for 1 minute using Electrobright 499 manufactured by Ebara Densan Co., Ltd. The surface diffuse reflectance of the obtained copper substrate was 3%.

This substrate was coated with a liquid photosensitive resin in the same manner as in Example 2, exposed, developed, and plated to obtain a patterned conductor. The obtained substrate and a polyimide substrate with an adhesive manufactured by DuPont were thermocompression-bonded, the aluminum substrate was removed by etching with 10% hydrochloric acid, and then the copper foil portion was removed by etching with a 25% ferric chloride solution. As a result of measuring the cross-sectional shape and resistance of the pattern conductor, the minimum wiring pitch was 15 μm, and the conductor width was 7 μm.
and a thick-film pattern conductor used as a different-pitch connection part having a conductor height of 22 μm was produced.

[0034]

[Table 1]

[0035]

[Table 2]

[0036]

[Table 3]

[0037]

[Table 4]

[0038]

According to the present invention, since the surface diffuse reflectance of the conductive substrate is set to 20% or less, a thick film pattern conductor having no disconnection, a high density of 50 μm or less in pitch and a low resistance can be obtained. It can be manufactured stably.

Claims (2)

(57) [Claims] A step of applying a liquid photosensitive resin on a surface of a conductive substrate, exposing the liquid photosensitive resin through a photomask, and removing an unexposed portion of the liquid photosensitive resin by development to form a resin pattern; Forming a conductive pattern by performing electrolytic plating on the portion where the photosensitive resin has been removed, transferring the formed conductive pattern onto an insulating substrate, and then removing the conductive substrate, and has a minimum wiring pitch of 50 μm. In a method for producing a thick film pattern conductor having the following portion and having an aspect ratio of the conductor of 1.0 or more, the surface diffuse reflectance of the liquid photosensitive resin of the conductive substrate in a photosensitive wavelength region is 20% or less. A method for manufacturing a thick film pattern conductor. 2. A liquid photosensitive resin having an ethylenically unsaturated bond concentration of 10 ⁻² to 2 × 10 ⁻⁴ mol / g and a molecular weight of 5
2. A prepolymer and / or oligomer having an ethylenically unsaturated bond of from 100 to 100,000 and an ethylenically unsaturated compound monomer.
3. The method for producing a thick film pattern conductor according to claim 1.