JPH07176855A - Manufacture of printed circuit board, printed circuit board, and equipment - Google Patents

Abstract

PURPOSE:To provide a method for manufacturing printed circuit board using a solder resist having an excellent plating resistance. V CONSTITUTION:A method for manufacturing printed circuit board which includes a process for heating a solder resist in an atmosphere where the oxygen concentration is maintained at <=15% (in volume) after a process for forming the solder resist in a pattern on a circuit board. In addition, a printed circuit board and equipment are also provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a printed circuit board, a printed circuit board and a device using the same.

[0002]

2. Description of the Related Art Conventionally, in the manufacture of printed circuit boards,
Solder resists are widely used as permanent protective coatings for printed circuit boards. This solder resist has been used for the purpose of preventing solder bridges during soldering, preventing corrosion of conductors during use, and maintaining electrical insulation, but recently, it has been used for printed circuit board terminals and surface mount type components. For the purpose of improving the connection reliability of the connection pad and the like, plating of gold or the like is often performed after forming the solder resist, and the solder resist is also required to have a performance as a plating resist. However, there is a problem in that the plating solution penetrates into the interface between the resist and copper during plating and the resist peels off, resulting in wiring failure. On the other hand, an adhesion promoter has been developed as a means for improving the adhesion between a plating resist and a base metal such as copper, and indazole or its derivative (JP-A-53-702),
Phthalazone or its derivative (JP-A-55-65202), tetrazole or its derivative (JP-A-5-12)
5726), lophine or a derivative thereof (Japanese Patent Laid-Open No. Sho 5 (1999) -58242).
It has been proposed to add a heterocyclic nitrogen compound such as JP-A-125727) to the resist composition, but it was insufficient to have sufficient resistance to plating (hereinafter referred to as plating resistance). .

[0003]

The present invention has solved the above-mentioned problems of the conventional techniques. The present invention relates to a method for manufacturing a printed circuit board using a solder resist having excellent plating resistance, a printed circuit board, and a device using the printed circuit board.

[0004]

According to the present invention, after a step of forming a solder resist in a pattern on a circuit board, a step of heating in an atmosphere having an oxygen concentration (volume ratio) of 15% or less is performed. And a method for manufacturing a printed circuit board.

The present invention will be described in detail below. The printed circuit board of the present invention can be manufactured, for example, as follows. After applying the resist on the circuit board,
Actinic rays are radiated in a pattern through a negative or positive pattern called artwork, and the pattern is developed with a developing solution to form a pattern-shaped solder resist having an opening at a terminal connection portion. Further, in order to sufficiently cure the resist, it is heated after being irradiated with an actinic ray. The printed circuit board can be obtained by plating the circuit board provided with the sufficiently hardened solder resist thus obtained.

As the above-mentioned circuit board in the present invention, a known one can be used. For example, after applying a resist on a copper-clad laminate, a negative or positive pattern called an artwork corresponding to a desired circuit pattern is used. It can be obtained by irradiating actinic rays in a pattern, developing with a developing solution, heating and drying to form a resist pattern corresponding to the circuit pattern, then etching with an etching solution to remove unnecessary copper, and then peeling the resist. (Called the subtractive method).

There is no particular limitation on the resist used for producing the circuit board and the resist used as the solder resist used for obtaining the printed circuit board, and known ones can be used. For example, an organic solvent should be used. No
Dry film type resist applied by laminating method, liquid resist applied by dip coating method, roll coating method, curtain coating method, screen printing method, etc., electrodeposition resist applied by electrodeposition coating method,
Examples thereof include toner type resists applied by the Thurtrack method. When a liquid resist is used, as a method of volatilizing the solvent contained in the resist, it is common to heat and dry in a dryer. In that case, the oxygen concentration (volume ratio) of the heating atmosphere is 15% or less. (Preferably 1
0% or less, more preferably 5% or less) and the temperature is 70%.
-250 ° C, preferably 1 to 120 at 80 to 200 ° C
Minutes, more preferably 5 to 90 minutes.

When the actinic ray is applied in a pattern, as the actinic ray, for example, a carbon arc lamp, an ultrahigh pressure mercury lamp, a high pressure mercury lamp, a xenon lamp or the like that effectively radiates ultraviolet rays is used. The developing method includes a dry developing method such as a peeling method, a wet developing method such as a dipping method, a paddle method, a spray method, and a high pressure spray method, and the high pressure spray method is preferable. In addition, as a developer used in wet development, one that is safe and stable and has good operability is used. For example, in a general solvent-developable resist, 1,1,1-trichloroethane or the like is used in alkali development. A dilute solution of sodium carbonate or the like is used for the type resist.

In the manufacture of circuit boards and printed circuit boards,
Depending on each method used, one or more heating steps are included, but after the step of forming the solder resist in a pattern, the oxygen concentration of the heating atmosphere is increased in the heating step to sufficiently cure the resist. (Volume ratio) is 15% or less (preferably 10% or less, more preferably 5% or less)
Is required from the viewpoint of plating resistance, adhesion, etc. The heating temperature is preferably 70 to 250 ° C, more preferably 80 to 200 ° C. The heating time is preferably 1 to 120 minutes, more preferably 5 to 90 minutes. If the heating temperature and time are out of this range, the plating resistance, adhesion, etc. tend to be poor.

When the step of forming the solder resist in a pattern on the circuit board is to perform wet development after pattern exposure, the oxygen concentration (volume ratio) after development is 15% or less (preferably 10%). Or less, more preferably 5
% Or less), it is preferable to dry by heating in an atmosphere of plating resistance and adhesion. This heating temperature is 50 ~
The temperature is preferably in the range of 200 ° C., and the heating time is 1 to
It is preferably 60 minutes.

Even in heating steps other than the above two heating steps, it is preferable that the oxygen concentration (volume ratio) of the heating atmosphere is 15% or less.

The heating means is not particularly limited, but usually a heating device such as a hot air dryer or an electric furnace can be used. In the natural state, the oxygen concentration in the heating device is about 21% (volume ratio), which is equivalent to the oxygen concentration in the atmosphere. As a means for adjusting the oxygen concentration (volume ratio) to 15% or less, the inside of the heating device is replaced with an inert gas such as nitrogen or argon,
A vacuum pump may be used, and the oxygen concentration thereof is preferably as low as possible. The oxygen concentration can be easily measured with an oxygen concentration meter,
As a commercially available oxygen concentration meter, a digital oxygen concentration meter XPO
-318E (manufactured by New Cosmos Electric Co., Ltd.) and the like.

The method of plating is not particularly limited, and known methods such as an electrolytic plating method, an electroless plating method, and a combination of these methods can be used. Usually, a plating bath is used. There is no particular limitation on the type of plating bath, and various plating baths can be used. For example, pyrophosphorus copper plating bath, copper sulfate plating bath, solder plating bath,
A nickel plating bath, a palladium plating bath, a gold plating bath, etc. may be mentioned.

[0014]

EXAMPLES The present invention will be described in detail below with reference to examples. In the following, the oxygen concentration was measured by using a digital oxygen concentration meter XPO-318E (manufactured by New Cosmos Electric Co., Ltd.) and installing a sensor at the exhaust port of a box dryer as a heating device.

Example 1 Alkali development type dry film solder resist SR-
2300G (manufactured by Hitachi Chemical Co., Ltd.) with a photosensitive layer thickness of 90μ
m is sanded with # 800 sandpaper, washed with water, drained with a stream of air, preheated atmosphere is replaced with nitrogen, and the oxygen concentration (volume ratio) is about 3% in a box dryer at 100 ° C. for 10 minutes. A circuit board having a circuit thickness of 65 μm (prepared by the subtractive method) that was preheated was laminated using a vacuum laminator HLM-V570 (manufactured by Hitachi Capacitor) under the following laminating conditions. Substrate preheating roller temperature: 100 ° C Heat shoe temperature: 90 ° C Laminating pressure (cylinder pressure): 5kgf / cm ² Pressure in vacuum chamber: 10mmHg Laminating speed: 0.8m / min

Then, using a negative film on the substrate thus obtained, a pattern exposure of 100 mJ / cm ² was performed with a 3 kW high pressure mercury lamp (HMW-201B, manufactured by Oak Manufacturing Co., Ltd.), and then on the dry film. The polyethylene terephthalate film was removed, and an unexposed portion was removed by spraying a 1 wt% sodium carbonate aqueous solution at 30 ° C. for 100 seconds to open the terminal connection portion of the component. Then, after washing the substrate with water for 1 minute, in order to remove the water contained in the resist, the heating atmosphere was replaced with nitrogen and the oxygen concentration was adjusted to about 3% (volume ratio) with a box dryer at 90 ° C. It was dried by heating for 10 minutes.

Next, in order to sufficiently cure the formed solder resist, a high pressure mercury lamp (manufactured by Toshiba Denshi Co., Ltd.) was used at 2 J /
cm ² was exposed, and then while heating the atmosphere was replaced with nitrogen, heating was carried out at 150 ° C. for 60 minutes in a box dryer having an oxygen concentration (volume ratio) of about 3%.

Next, in order to perform plating, degreasing and washing with water were carried out for 1 minute, and the plate was immersed in a 250 g / liter ammonium persulfate aqueous solution for 2 minutes. Further, after washing with water for 1 minute, it was immersed in a 10% by weight sulfuric acid aqueous solution for 1 minute, and washed again with water for 1 minute. Next, nickel plating bath (nickel sulfate 350g / liter, nickel chloride 45g / liter, boric acid 4
5 g / liter, Nical pc-3 (product name manufactured by Meltex) 30 ml / liter and nickel cream NAW-4
(Meltex brand name) 0.1 ml / liter),
Nickel plating was performed at 50 ° C. and 3 A / dm ² for 10 minutes. Immediately after completion of nickel plating, wash with water and then gold strike (Assid strike, trade name of Kojundo Chemical Co., Ltd.)
Was carried out at 40 ° C. and 5 A / dm ² for 10 seconds. Immediately after completion of the gold strike plating, the plate was washed with water, and then gold plating (Temperex 401, trade name of Nippon Electroplating Engineering Co., Ltd.) was performed at 30 ° C. and 1 A / dm ² for 10 minutes. After completion of gold plating, the plate was washed with water and left to dry at room temperature to obtain a printed circuit board.

Example 2 Alkali developable liquid solder resist BSR-4000
Z25 (manufactured by Taiyo Ink Co., Ltd.) was applied on a circuit board having a circuit thickness of 50 μm (prepared by the subtractive method) with a bar coater, and the oxygen concentration (volume ratio) was adjusted to about 2% while displacing the heating atmosphere with argon gas. The film was dried and heated at 80 ° C. for 20 minutes in a box dryer to form a photosensitive layer having a thickness of 40 μm (20 μm on the circuit).

Then, using a negative film on the substrate thus obtained, a pattern exposure of 250 mJ / cm ² was performed with a 3 kW high pressure mercury lamp (HMW-680, manufactured by Oak Manufacturing Co., Ltd.), and the exposure was carried out at 30 ° C. for 1 hour. The unexposed part was removed by spraying a 60% by weight aqueous solution of sodium carbonate for 60 seconds to open the terminal connection part of the component. Next, after washing the substrate with water for 1 minute, in order to remove the water contained in the resist, the heating atmosphere was replaced with argon gas and the oxygen concentration (volume ratio) was adjusted to about 2% with a box dryer at 90 ° C. It was heated for 10 minutes.

Next, in order to sufficiently cure the formed solder resist, a high pressure mercury lamp (manufactured by Toshiba Denshi Co., Ltd.) was used to obtain 3 J / cm
² exposure was carried out, and thereafter, while heating atmosphere was replaced with argon gas, heating was carried out at 150 ° C. for 45 minutes in a box dryer having an oxygen concentration (volume ratio) of about 2%.

Next, in order to perform plating, degreasing and washing with water were carried out for 1 minute, and the plate was immersed in a 250 g / liter ammonium persulfate aqueous solution for 2 minutes. After further washing with water for 1 minute, it was immersed in a 10% by weight sulfuric acid aqueous solution for 1 minute and again washed with water for 1 minute. Then nickel plating bath (nickel sulfate 3
40 g / liter, nickel chloride 45 g / liter, boric acid 45 g / liter, Nical pc-3 (product name manufactured by Meltex) 30
ml / liter and nickel cream NAW-4 (trade name of Meltex, 0.1 ml / liter), and nickel plating was performed at 50 ° C. and 3 A / dm ² for 10 minutes. Immediately after the completion of nickel plating, the plate was washed with water, and subsequently subjected to gold strike (Aurobond-TN, trade name of Nippon Electroplating Engineering Co., Ltd.) at 40 ° C. and 5 A / dm ² for 10 seconds. Immediately after the gold strike is finished, the plate is washed with water and then gold plated (Autoronex-CI, trade name of Nippon Electroplating Engineering Co., Ltd.) at 30 ° C. and 1 A / dm ²
It was performed for 0 minutes. After completion of gold plating, the plate was washed with water and left to dry at room temperature to obtain a printed circuit board.

Comparative Example 1 The same procedure as in Example 1 was carried out except that heating and drying after development and heating for sufficiently curing the resist were carried out in an atmospheric circulation type box dryer.

Comparative Example 2 The procedure of Example 2 was repeated, except that the heating and drying after development and the heating for sufficiently curing the resist were carried out in an air circulation type electric furnace.

In order to examine the plating resistance of the resists after gold plating in Examples 1 and 2 and Comparative Examples 1 and 2, cellophane tape was peeled off from the substrate and peeled in the vertical direction to check whether the resist peeled off. (90 ° peel test). After that, the presence or absence of chipping of the plating was observed with an optical microscope from above. In the case where the plating is removed, infiltration of the plating is observed under the resist through the resist. The results are shown in Table 1.

[0026]

[Table 1]

In the case of Examples 1 and 2, since nitrogen or argon gas was used in the heating step and the heating atmosphere was set to an oxygen concentration of 15% or less, oxidation of the copper surface can be prevented and plating resistance is good. Shown. On the other hand, in Comparative Examples 1 and 2, the copper surface was oxidized due to the effect of oxygen in the atmosphere, and the plating resistance was lowered. In Examples 1 and 2, other properties such as solderability after plating were also good.

[0028]

According to the method of manufacturing a printed circuit board of the present invention, it is possible to reduce defects caused by the chipping of plating and obtain a printed circuit board having high density, high accuracy and high reliability. Yes, this printed circuit board can be used for TV, audio, microcomputer, personal computer, facsimile,
It can be suitably used for various devices such as a communication device, a measuring device, a controller, an exchange, and a game machine.

Front page continuation (72) Inventor Satoshi Otomo 4-13-1, Higashimachi, Hitachi, Ibaraki Prefecture Hitachi Chemical Co., Ltd. Yamazaki Plant

Claims (4)

[Claims] 1. An oxygen concentration (volume ratio) is set to 1 after a step of forming a solder resist in a pattern on a circuit board.
A method of manufacturing a printed circuit board, comprising a step of heating in an atmosphere of 5% or less. 2. The step of forming a solder resist in a pattern includes a step of performing wet development after pattern exposure and heating and drying in an atmosphere having an oxygen concentration (volume ratio) of 15% or less after development. The method for manufacturing a printed circuit board according to claim 1, wherein 3. A printed circuit board manufactured by the method for manufacturing a printed circuit board according to claim 1. 4. A device using the printed circuit board according to claim 3.