JPH08288623A - Manufacture of printed wiring board and printed wiring board - Google Patents

Abstract

PURPOSE: To completely cover the whole bodies of conductors with a circuit protective resist at the time of forming a circuit protective resist pattern on a conductor circuit pattern by abundantly sticking the resist to the edge section of the conductor circuit pattern than the other part. CONSTITUTION: A circuit protecting resist pattern 103 is printed on a copper circuit pattern 102 by using a bubble jetting type ink jet printer charged with a circuit protective resist. The pattern 103 is printed in dots based on printing data prepared from the pre-prepared data of the pattern 103. The data of the pattern 103 are prepared so that the amount of the resist stuck to the edge section 104 of the pattern 102 can become about double that of the resist stuck to the other part of the pattern 102. Therefore, the part to be covered with the circuit protective resist can be covered completely with the resist including the edge section 104.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printed wiring board manufacturing method and a printed wiring board.

[0002]

2. Description of the Related Art Conventionally, as a method of manufacturing a printed circuit board, glass cloth impregnated with a resin such as epoxy resin or polyimide resin, or gold, silver, copper or platinum on a substrate such as ceramic or bakelite is used. After forming a resist pattern corresponding to the conductor circuit pattern on a substrate provided with a metal such as aluminum, the conductor circuit pattern is formed by a treatment such as etching or plating, and then the surface of the conductor circuit pattern for protection is formed. The method of forming a resist pattern has been taken. In the formation of the resist pattern, a liquid or a photosensitive resin commonly referred to as a dry film, which is formed in a predetermined thickness, is provided on a substrate and then exposed to ultraviolet light through a photomask corresponding to a desired conductor circuit pattern. After that, a pattern was formed by performing development processing or screen printing using a screen plate corresponding to a desired pattern.

Further, there is a method of forming a desired pattern by scanning a laser beam instead of photolithography using a mask. But,
This method does not require a photomask, but it does not solve the problems of environmental issues and material costs. Further, there is a problem that the device itself is very expensive.

As a method for solving these conventional problems,
A method has been proposed in which a resist pattern is directly drawn by an inkjet device. JP-A-56-660
In JP-A-89, JP-A-56-157089 and JP-A-58-50794, a resist pattern for etching a conductor is formed by an inkjet device. In Japanese Patent Publication No. 59-41320, the conductor layer and the insulating layer are formed by an inkjet device.

According to the method using the ink jet device, only the data created by CAD is converted for the ink jet device, and a mask or a screen printing plate is not required. Moreover, it is possible to easily deal with a part of the design change, no need to change jigs and tools, and the cost and delivery time can be reduced. It can be said that the resist pattern forming method using the ink jet device is particularly advantageous for small-quantity, high-mix production. In addition, this method is also effective against environmental problems because it is not necessary to develop the resist. In particular, the use of a drop-on-demand inkjet device that can discharge the resist only where it is needed has the advantage that the amount of resist used can be very small. In addition, as an apparatus, an expensive optical system required for a method of scanning a laser beam is unnecessary, and therefore, there is an advantage that it is inexpensive.

[0006]

However, when a circuit protection resist pattern is formed on a previously formed conductor circuit pattern, the circuit protection resist completely covers the conductor at the edge portion of the conductor circuit pattern. There was a problem of not doing. in this way,
If the portion of the conductor circuit pattern that should originally be covered is not covered, a short circuit will occur when the board is passed through the molten solder bath in order to electrically connect the electrical components to the printed wiring board in a later process, causing the failure. And also cause corrosion of the conductor.

An object of the present invention is to provide a novel printed wiring board manufacturing method and a printed wiring board which solve the problems associated with the conventional printed wiring board manufacturing method.

[0008]

In order to solve the above problems, a method for manufacturing a printed wiring board according to claim 1 of the present invention comprises:
In a method of manufacturing a printed wiring board, which comprises forming a conductor circuit pattern on a substrate and then covering at least a part of the conductor circuit pattern with a protective resist using an inkjet device, It is characterized in that the resist is deposited more than other portions.

Further, according to a second aspect of the present invention, in the method for producing a printed wiring board according to the first aspect, the thickness of the resist in the vicinity of the edge of the conductor circuit pattern is made thicker than the resist thickness on the conductor pattern. It is characterized by doing.

A third aspect of the present invention is the method for producing a printed wiring board according to the first or second aspect, wherein the ink jet device is a bubble jet type ink jet device for ejecting a liquid by the energy of a heating element. Is characterized in that.

A fourth aspect of the present invention relates to a printed wiring board, wherein the printed wiring board has a conductor circuit pattern formed on a substrate and at least a part of the conductor circuit pattern is covered with a protective resist. In the printed wiring board, the protective resist covering at least a part of the conductor circuit pattern is composed of a set of resist droplets, and the protective resist at the edge portion of the conductor circuit pattern is formed in another part. It is characterized in that it is attached more.

The printed wiring board according to a fifth aspect of the present invention is the printed wiring board according to the fourth aspect, wherein the thickness of the resist near the edge of the conductor circuit pattern is thicker than the resist thickness on the conductor pattern. Is characterized by.

Any type of ink jet system can be used in the present invention, but preferably,
There is a bubble jet type ink jet in which the foaming component in the ink is foamed by the electrothermal conversion element and the ink is ejected as shown in JP-A-56-123869. More preferably, a bubble jet type inkjet of the type shown in FIG.

FIG. 2 (a) is a sectional view of a nozzle showing an example of an ink jet head preferably used in the present invention, and FIG. 2 (b) is a sectional view taken along the line XIII-XIII of FIG. (C) is the figure which looked at the AA cross section from the Y direction.

In FIG. 2, an electrothermal conversion element (hereinafter referred to as a heater) 205 is formed on a substrate 201 and an ejection liquid flow path 204 for accommodating an ejection liquid which is a first liquid ejected from an ink jet head. Foaming liquid flow path 20 for accommodating the bubble generating liquid which is the first region and the second liquid
6, a second region, the discharge liquid flow path 204, and the discharge port 2
No. 03 integrally molded with a grooved top plate 202, a first region including the discharge liquid flow path 204, and the foaming liquid flow path 2
Separation wall 20 for separating and separating the second region composed of 06
8 and.

A movable member 207 is formed on the separation wall 208. The movable member 207 has a free end on the side close to the ejection port 203 for ejecting the ejection liquid, and the ejection port 203
The distant side is the fulcrum, which is a so-called cantilever beam-shaped spring. 209 is a nozzle separation wall that separates each nozzle. In FIGS. 2B and 2C, the movable member 207 is formed at a position directly above the heater 205.

In the present ink jet recording head, the separating wall 208 and the nozzle separating wall 209 are integrally formed by electroforming of nickel, and by joining with the substrate 201, the foaming liquid flow passage 206 is formed. The grooved top plate 202 has the ejection port 203 formed by laser processing a molded product of polysulfone, for example.

Next, the principle of ejection using this head will be described with reference to FIG.

FIG. 3A shows an initial state or heater 20.
The case where 5 is OFF is shown. In this case, the movable member 207 formed on the separation wall 208 is not deformed and the discharge amount is zero.

The foaming liquid made of a solvent described below is supplied to the foaming liquid flow passage 206 which is the second region, and is supplied so as to cover at least the heater. The supply method is by supplying pressure by a circulation system and providing a suction port, but is not limited to circulation as long as it is supplied so as to cover the heater.

After the foaming liquid is supplied, the etching resist liquid as the discharge ink is supplied. The etching resist solution is supplied so as to completely fill the discharge port 203. After pressure supply, or by suction from the discharge port 203, the discharge port 203 is completely filled with the etching resist liquid.

FIG. 3B shows a state where the heater 205 is ON. The bubbling liquid filled in the second region formed by the bubbling liquid flow path 206 generates bubbles as the heater 205 heats and foams. The bubbling energy pushes up the movable member 207, deforms the free end of the movable member 207, and has a displacement amount of H only. The bubbles can enter the discharge liquid flow path 204, which is the first region, through the gap having the displacement amount H of the movable member, and discharge a V etching resist liquid amount.

The bubble jet type ink jet head used in the present invention preferably has 1 to 10 ⁴ nozzles, a resolution of 200 to 4000 dpi in the main and sub-scanning directions, and a driving frequency of 1 to 20 kHz. Here, the number of nozzles and the resolution may be achieved by one head, or may be achieved by combining multiple heads. The bubble-jet type inkjet head shown in FIGS. 2 and 3 is particularly preferable because the substrate can be formed by the photolithography method used in semiconductor manufacturing, and thus has the advantage of easily increasing the number of nozzles and increasing the density. .

Next, as the foaming liquid used in the present invention, a mixed liquid of water and the following solvent is used. Ethylene glycol, diethylene glycol, triethylene glycol, tripropylene glycol, glycerin, 1,
2,4-butanetriol, 1,2,6-hexanetriol, 1,2,5-pentanetriol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, dimethylsulfoxide, dye Acetone alcohol, glycerin monoallyl ether, propylene glycol, butylene glycol, polyethylene glycol 300, thiodiglycol, N-methyl-2-pyrrolidone, 2-pyrrolidone, γ-butyrolactone, 1,3-
Dimethyl-2-imidazolidinone, sulfolane, trimethylolpropane, neopentyl glycol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monoisopropyl ether, ethylene glycol monoallyl ether,
Diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, triethylene glycol monomethyl ether, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, β-dihydroxyethyl urea, urea, acetonylacetone, pentaerythritol, 1,4-cyclohexanediol, hexylene Glycol, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, ethylene glycol monoisobutyl ether, ethylene glycol monophenyl ether, diethylene glycol diethyl ether, diethylene glycol monobutyl ether, diethylene glycol monoisobutyl ether, triethylene glycol monobutyl ether, tri Tylene glycol dimethyl ether, triethylene glycol diethyl ether, tetraethylene glycol diethyl ether, tetraethylene glycol dimethyl ether, tetraethylene glycol diethyl ether, propylene glycol monobutyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monopropyl ether, dipropylene glycol monobutyl ether , Tripropylene glycol monomethyl ether, glycerin monoacetate, glycerin diacetate, glycerin triacetate, ethylene glycol monomethyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monomethyl ether acetate, cyclohexanol, 1,2-cis Clohexanediol, 1-butanol, 3-methyl-1,5-pentanediol, 3-hexene-2,5-diol, 2,3
-Butanediol, 1,5-pentanediol, 2,4
-Pentanediol, 2,5-hexanediol, ethanol, n-propanol, 2-propanol, 1-methoxy-2-propanol, furfuryl alcohol, tetrahydrofuryl alcohol and the like can be used. Also,
As a non-aqueous solvent, n-hexane, n-heptane, n-
Octane, toluene, xylene, methylene dichloride, ethyl ether, dioxane, dichlorohexane, methyl acetate, ethyl acetate can also be used. Also, a mixture of these can be used.

[0025]

According to the present invention, when the circuit protection resist pattern is formed on the conductor circuit pattern, the edge portion of the conductor circuit pattern adheres more than other portions of the circuit protection resist, and therefore the conductor to be covered. Can be almost completely covered. Therefore, the manufacturing yield of the printed circuit board can be kept high, and the manufacturing cost can be reduced. In addition, a highly reliable printed wiring board can be provided. As described above, a large amount of the circuit protection resist can be adhered only to the edge portion of the conductor pattern because the pattern formation by the inkjet device can control the data in dot units, and the resist film is formed on the entire surface of the substrate. This is because the resist is not removed by patterning afterwards, but the resist is printed in dot units to form a pattern.

[0026]

EXAMPLES The present invention will be specifically described below based on examples.

(Embodiment 1) An etching resist having the following composition having 128 nozzles, a resolution of 600 dpi in the main scanning direction and a sub-scanning direction, and a driving frequency of 4 KH
It was loaded in a bubble jet type inkjet printer (inkjet device) of z.

Etching resist: acrylic resin (acrylic resin / methyl methacrylate 1/9 copolymer, weight average molecular weight: 15000) 10 parts monoethanolamine 1 part water 89 parts C.I. I. Direct Blue 86 0.1 part This printer was used to print an etching pattern on a copper clad laminate for printed wiring boards (commercial one-sided copper foil thickness 35 μm, substrate thickness 1.2 mm) which was brush-polished. As the wiring pattern, print data was created from the previously created wiring pattern data and dot printing was performed. The printed wiring pattern had a wiring width of about 150 μm and a pad diameter of 1.0 mm. After printing, the substrate was heated and dried at 85 ° C. for 15 minutes to remove the solvent component. After cooling the substrate, etching treatment was performed with a ferric chloride-based etching solution. The treatment was performed at 50 ° C. for 4 minutes by a spray method. After processing, washing with water and measuring the wiring width,
The width of the copper wiring is 125 μm on average, and the diameter of the pad is 0.9.
It was 4 mm.

Next, a circuit protection resist having the following composition was added:
It was loaded in the same bubble jet type inkjet printer as described above.

Resist for circuit protection: ・ NK-ester A-TMPT-3EO (acrylic monomer: manufactured by Shin-Nakamura Chemical Co., Ltd.) 10 parts ・ IRGACURE 651 (photopolymerization initiator: manufactured by Ciba-Geigy Co., Ltd.) 0.3 part -Isopropyl alcohol 60 parts-Water 9.7 parts-N-Cylpyrrolidone 20 parts Using this printer, a circuit protection resist pattern was printed on the previously formed copper circuit pattern. As for the circuit protection resist pattern, print data was created from the data of the circuit protection resist pattern created in advance as in the above, and dot printing was performed. In this pattern data, the data was created so that the resist on the edge of the copper circuit pattern was almost twice as large as the resist on the copper circuit pattern. The substrate after printing was heated and dried at 80 ° C. for 20 minutes to remove the solvent component. Next, the resist was cured by exposing it to ultraviolet rays of 5 J / cm ² with an ultra-high pressure mercury lamp.

In a visual inspection, the edge of the copper circuit pattern to be covered with the protective resist was completely covered. Further, in order to evaluate the coverage of the copper circuit pattern, the printed wiring board obtained above was dipped in a molten Sn—Pd eutectic solder bath and pulled up.
No solder was attached to the portion where the circuit protection resist pattern was formed.

(Example 2) A circuit protection resist pattern was printed on the substrate having the copper circuit pattern formed in Example 1 by using the ink jet head having the structure shown in FIGS. 2 and 3.

The following are used as the first liquid, that is, the circuit protection resist, and the second liquid, that is, the foaming liquid.

Resist for circuit protection: ・ Adeka Resin EP-4100 (bisphenol A type epoxy resin: Asahi Denka Kogyo Co., Ltd.) 20 parts ・ Denacol EX-314 (Polyepoxy compound: Nakase Kasei Co., Ltd.) 10 parts ・ 2-Ethyl -4-Methyl-imidazole (epoxy curing agent) 3 parts ・ Dichloropropylene glycol monomethyl ether 50 parts ・ Isopropyl alcohol 10 parts ・ N-methyl propylene alcohol 10 parts Effervescent liquid: ・ Difluoroethylene glycol monomethyl ether 80 parts ・ Isopropyl alcohol This printer was used to print a circuit protection resist pattern on the copper circuit pattern formed above. As for the circuit protection resist pattern, print data was created from the data of the circuit protection resist pattern created in advance as in the above, and dot printing was performed. In this pattern data, the data was created so that the resist on the edge of the copper circuit pattern was almost twice as large as the resist on the copper circuit pattern. The printed substrate was heated and dried in an oven at 60 ° C. for 20 minutes to remove the solvent component. Next, the resist was cured by heating in an oven at 150 ° C. for 1 hour.

In visual inspection, the edge of the copper circuit pattern to be covered with the protective resist was completely covered. In addition, in order to evaluate the coverage of the copper circuit pattern, the printed wiring board obtained above was dipped in a molten Sn-Pd eutectic solder bath and pulled up. No solder was attached to the portion where the circuit protection resist pattern was formed.

(Comparative Example 1) A printed wiring board was prepared in the same manner as in Example 1. However, regarding the data of the resist pattern for circuit protection, the edge portion of the copper circuit pattern was not made thick, but the thickness was made to be the same as that on the copper circuit pattern.

The printed substrate was at 80 ° C. as in Example 1.
The solvent was removed by heating and drying in an oven for 20 minutes.
Next, the resist was cured by exposing it to ultraviolet rays of 5 J / cm ² with an ultra-high pressure mercury lamp.

In visual inspection, there was a portion to be covered with the protective resist for the copper circuit pattern, and there was an uncoated portion at the edge portion. In addition, Example 1
Similarly to, in order to evaluate the coverage of the copper circuit pattern, the printed wiring board obtained above was immersed in a molten Sn-Pd eutectic solder bath and pulled up. Even in the portion covered with the circuit protection resist pattern, there was a place where solder adhesion was observed. As a result of analysis, it was found that this occurred because the edge portion of the copper circuit pattern was not completely covered with the circuit protection resist.

Comparative Example 2 A printed wiring board was prepared in the same manner as in Example 2. However, regarding the data of the resist pattern for circuit protection, the edge portion of the circuit pattern is not made thick, but the entire thickness is made the same.

The substrate after printing is 60
The solvent was removed by heating and drying in an oven at ℃ for 20 minutes. Next, the resist was cured by heating in an oven at 150 ° C. for 1 hour.

In a visual inspection by visual inspection, there was a portion to be covered with the protective resist for the copper circuit pattern, and there was an uncoated portion at the edge portion. In addition, Example 1
Similarly to, in order to evaluate the coverage of the copper circuit pattern, the printed wiring board obtained above was immersed in a molten Sn-Pd eutectic solder bath and pulled up. In some areas where the circuit protection resist pattern was formed, solder adhesion was observed. This was found to be because the edge portion of the copper circuit pattern was not completely covered with the circuit protection resist, as in Comparative Example 1.

When the cross sections of the copper circuit pattern portions of the printed wiring boards prepared in the examples and comparative examples were observed,
In the embodiment, as shown in FIG. 1, a resist pattern 103 for circuit protection is thicker on the edge portion 104 of the copper circuit pattern 102 formed on the copper-clad laminated substrate 101 than on the center of the copper circuit pattern 102. Had been formed.

[0043]

According to the present invention, a highly reliable printed wiring board can be manufactured with a high yield. Further, since the pattern is formed by using an inkjet, a photomask and a screen printing plate are not required, and the cost and the delivery time are not required. Further, it is possible to easily deal with a partial change in design. Also, the process is short and not complicated. In particular, it is easy to handle low-volume, high-mix production. It is also environmentally friendly.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a copper circuit pattern portion of a printed wiring board manufactured according to the present invention.

FIG. 2A is a cross-sectional view of a nozzle showing an example of an inkjet head, and FIG. 2B is a cross-sectional view taken along line AA of FIG.
The top view seen from the direction, (c) is a cross section taken along the line A-A in (a).
It is the rear view seen from the direction.

3 (a) and 3 (b) are cross-sectional views for explaining the ejection principle of the inkjet recording head used in the present invention.

[Explanation of symbols]

 101 Copper-clad laminated substrate 102 Copper circuit pattern 103 Circuit protection resist pattern 104 Edge of copper circuit pattern 201 Substrate 202 Groove top plate 203 Discharge port 204 Discharge liquid flow path 205 Electrothermal conversion element 206 Foaming liquid flow path 207 Movable Member 208 Separation wall 209 Nozzle separation wall

Claims (5)

[Claims] 1. A method for manufacturing a printed wiring board, which comprises forming a conductor circuit pattern on a substrate, and then covering at least a part of the conductor circuit pattern with a protective resist by using an inkjet device. A method for manufacturing a printed wiring board, characterized in that a protective resist on a part is attached more than other parts. 2. The method for manufacturing a printed wiring board according to claim 1, wherein the thickness of the resist near the edge of the conductor circuit pattern is made thicker than the resist thickness on the conductor pattern. 3. The method for manufacturing a printed wiring board according to claim 1, wherein the ink jet device is a bubble jet type ink jet device that ejects a liquid by energy of a heating element. 4. A conductor circuit pattern is formed on a substrate,
In a printed wiring board in which at least a part of the conductor circuit pattern is covered with a protective resist, the protective resist covering at least a part of the conductor circuit pattern is composed of a set of resist droplets, A printed wiring board, characterized in that the protective resist at the edge portion of the conductor circuit pattern is attached more than at other portions. 5. The printed wiring board according to claim 4, wherein the thickness of the resist near the edge of the conductor circuit pattern is thicker than the resist thickness on the conductor pattern.