JPH0728115B2 - Printed board and manufacturing method thereof - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a printed board, and more particularly to a printed board suitable for forming a fine circuit using a photosensitive resist and a method for manufacturing the same.

[Conventional technology]

In recent years, a demand for forming a fine circuit of a printed board has become stronger. Conventionally, a photographic method using a photosensitive resin has been applied as a method for forming a fine circuit. One known method is to form a circuit by laminating a photosensitive film on a substrate, performing exposure and development to form an image, and then etching the metal foil on the substrate or performing patterning. Has been. In addition, various methods have been proposed for increasing the adhesion between the photosensitive film and the base, aiming at further miniaturization. For example, JP-A-63-59517
As described in the publication, a method has been proposed in which a photosensitive film is laminated on a substrate and then re-pressed at a temperature higher than the laminating temperature. As a result, the photosensitive resist was strongly adhered to the substrate, and the image disappearance during the development after the exposure could be improved.

[Problems to be Solved by the Invention]

However, in the above-mentioned prior art, since the photosensitive film or the like is heated and re-compressed before exposure, there is a problem that the photosensitive material such as the photosensitive film is apt to cause thermal fogging and the resolution itself is apt to decrease. Therefore, it was not possible to expect a great effect due to restrictions such as re-pressing at high temperature. Further, since exposure and development are performed after pressure bonding, the image does not disappear, but the adhesiveness between the photosensitive material and the base material is reduced during development, and the liquid under the photosensitive material is removed during etching or plating afterwards. Go in,
Problems such as not playing a sufficient role are likely to occur. Furthermore, when the photosensitive material is used as a permanent resist or a permanent mask, there is a problem that the insulation resistance is likely to decrease due to the infiltration of liquid.

The object of the present invention is to improve the adhesion between the photosensitive material and the base substrate without impairing the original resolution of the photosensitive material, and to achieve a fine circuit in the circuit formation by etching or plating. And to prevent the problem of forming a fine circuit by preventing a decrease in insulation resistance when used as a permanent resist or a permanent mask.

[Means for Solving the Problems]

In order to achieve the above object, in the present invention, a photosensitive material layer is provided on a desired substrate surface, and a resist image is formed by performing image exposure and development to form a resist image. After forming an image, it is as a printed board which is heat-pressed on a substrate at a temperature at which the photosensitive material softens and flows, and in the method for producing the printed board, after forming a resist image, Is prepared by heating and pressing the resist image on a substrate at a temperature at which the photosensitive material softens and flows. Further, as a device for manufacturing the printed board, means for forming a photosensitive material layer on the surface of the substrate, and the formed photosensitive material Means for exposing and developing the photosensitive material layer to form a resist image, means for heat-pressing the resist image on the substrate at a temperature at which the photosensitive material softens and flows, and the obtained resist image. It is obtained by a device comprising a means for forming a circuit from the substrate.

Next, the present invention will be described in more detail.

The manufacturing method of the present invention is applicable to both subtractive and additive printed circuit board manufacturing methods. For example, it can be applied to a subtractive method in which a photosensitive film is laminated on a copper-clad laminate, exposed and developed to form an image, and then thermocompression-bonded, and etching is performed to remove copper leaving an image forming portion, that is, a circuit forming portion. . Particularly, in the case of a so-called tenting method for covering the through hole, it is possible to prevent the etching liquid from infiltrating into the through hole, which is effective in improving the reliability of the through hole.

Further, it can be applied as a plating resist of various additive methods. For example, applicable methods include a pattern electric plating method in the case where the entire surface of the base is copper, a pattern chemical plating method, a semi-additive method, or a part in which a circuit is preliminarily formed on the substrate surface and a through hole is mainly plated. There is an additive method. Further, there is a full additive method when the base is an insulating plate.

Of these, the present invention is more suitable when applied to a method for manufacturing a printed board mainly composed of chemical copper plating. This method is generally used for a long time, for example, 4 to 40 for chemical copper plating.
It takes time. Therefore, the plating solution permeates between the photosensitive material, which is the plating resist, and the underlying substrate, and the plating resist is likely to swell or peel off. In such a case, it becomes difficult to form a fine circuit. Further, in the case of the partly additive method or the full additive method, the insulation resistance is likely to decrease due to the penetration of the plating solution. The finer the circuit becomes, the more problematic the insulation resistance becomes, and the lower the base becomes, the more unacceptable. Furthermore, electrolytic penetration is more likely to occur due to the impregnation of the liquid.

In the present invention, a photosensitive material is formed, and an image is formed by the photosensitive material by exposure and development, and then thermocompression bonding is performed. The conditions for thermocompression bonding vary depending on the photosensitive material to be applied and the condition of the surface of the base substrate. The heating temperature is based on the softening temperature of the photosensitive material to be applied. If the unevenness of the substrate surface is small, the flow rate of the photosensitive material is small, and the adhesion can be increased at a relatively low temperature. Generally, the adhesion is increased by heating at a high temperature for a long period of time and increasing the pressure for pressure bonding. However, if the appropriate conditions are exceeded,
Care must be taken because the image formed by the photosensitive material is deformed and distorted. In the case of a photosensitive material containing an ordinary acrylic acid ester, methacrylic acid ester or the like, the conditions for thermocompression bonding are preferably 100 to 160 ° C., several seconds to 30 min, and about ² to 50 kgf / cm ² . Heating can be performed with a hot plate press, a single-stage or multi-stage heating roll, or the like. In the case of a heating roll, since it is difficult to maintain the pressure bonding time, it can be achieved by heating and pressure bonding at a relatively high temperature for a short time.

Next, the present invention will be described in more detail with reference to the manufacturing process chart of FIG. 1 in the case of the pattern chemical copper plating method. FIG. 1A shows a state where the copper surface is roughened. This is to increase the surface area in order to enhance the adhesion between the photosensitive material as the plating resist and the base. A highland method can be used as a roughening method. For example, after roughening with an aqueous solution of cupric chloride or ammonium persulfate, it is treated with an alkaline aqueous solution containing chlorite to form an oxide film with fine irregularities, and finally with a reducing agent such as dimethylamine borane. It is a method of reduction.

FIG. 1B shows a state in which a metal layer such as nickel is provided.
The metal layer 3 is not always necessary, but it is advantageous for increasing the adhesion with the photosensitive plating resist 4.
Those having a lower oxide film reduction potential than the metal layer plating reaction potential are preferable, and zinc, tin, and the like can be used in addition.

FIG. 1C shows a state in which a photosensitive material is formed on the metal layer 3 and the photosensitive material in the circuit forming portion is removed, and the remaining photosensitive material is shown as a plating resist 4. The photosensitive material is generally a dry film type which is easy to use and is laminated on the substrate surface. Lamination can be performed by a general hot roll at 100 to 120 ° C. Further, vacuum laminating can be performed if necessary.
Excessive high temperature heating at this stage accelerates thermal polymerization of the photosensitive material and lowers resolution, which is not preferable. Exposure and development can also be performed by a general method. For example, a negative mask of a desired circuit is brought into close contact, exposed with ultraviolet rays, and subsequently developed with a developer such as chlorocene.

The photosensitive material that is the plating resist 4 can be applied as long as it has resistance to plating to some extent. For example, photosensitive materials that can be used include Hitachi Chemical's photosensitive dry film, Phototec SR-3200, Phototec SR-3000, Deupon's photosensitive dry film, and Liston film.

After FIG. 1C, thermocompression bonding, which is a feature of the present invention, is performed.
A suitable pressure condition is around 5 kgf / cm ^2, and a suitable heating condition is a temperature 10 to 50 ° C higher than the temperature during lamination. The reason for raising the temperature is that the photosensitive material reacts and cures upon exposure. The thermocompression bonding is a temperature at which the photosensitive material softens and flows, and the time required for filling the gap is usually about 10 minutes. As described above, by sufficiently biting the plating resist 4 on the substrate surface, it is possible to substantially prevent swelling, peeling and the like in the subsequent plating step.

FIG. 1D shows a state in which the metal layer in the planned circuit portion where the patterned chemical copper plating is performed is selectively removed. This step is not always necessary, but it is more reliable in terms of reliability if the metal layer is zinc or tin.

FIG. 1E shows a state in which the patterned chemical copper plating 5 is performed. Since the circuit thickness is usually required to be about 30 to 80 μm, it takes 10 to 80 hours to deposit the chemical copper. During this period, the immersion liquid soaking into the underside of the plating resist can be prevented by the above-mentioned thermocompression bonding of the resist. The metal layer 3 can suppress the reaction that causes peeling even when the plating solution penetrates, but it is difficult to completely cover the copper layer 2 with the metal layer 3, especially for more than 15 hours. If the plating is applied for a long time, some resist peeling may occur. It is considered that this is because the surface of the copper layer 2 is roughened and fine irregularities are formed, so that it is difficult to cover the copper layer 2 with the metal layer 3 everywhere. By the thermocompression bonding, such swelling and peeling of the resist can be reduced to a level without a problem. The chemical copper plating 5 shown in FIG. 1E can be replaced with electrolytic copper plating.

The important part of the present invention has been described above. Hereinafter, FIGS. 1F to 1I can be performed by a conventional known technique. That is, FIG. 1F shows a state in which the soldering layer 6 is formed as an etching resist, FIG. 1G shows a state in which the soldering resist is peeled off, and FIG. 1H shows a state in which a copper layer other than the circuit is removed by etching. FIG. 1I shows a state in which the soldering of the etching resist is removed.

[Action]

In the printed board of the present invention, the photosensitive material is subjected to thermocompression bonding after exposure reduction. Therefore, in the obtained resist image, the decrease in adhesion generated during development is recovered by thermocompression bonding or the adhesion is significantly improved, so that the etching solution or the etching solution under the photosensitive material may be removed by etching or plating in the next step. Penetration can be prevented and a fine circuit can be formed. Since the image formation has already been completed, even if the heating temperature is raised, there is no reduction in resolution due to the thermal polymerization reaction. Further, since the heating temperature can be made sufficiently high, the softening flow of the photosensitive material is sufficient, the gap between the photosensitive material and the underlying substrate can be substantially eliminated, and the adhesive force can be significantly improved. Will be easier.

〔Example〕

Next, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples.

Example 1 Double-sided copper-clad glass epoxy laminate with a thickness of 1.6 mm (copper foil thickness 18 μ
m) was drilled with a 0.4 mm diameter drill. After the surface was brush-polished, the inside of the hole was washed with high pressure water. After performing soft etching of copper with an aqueous solution of ammonium persulfate, it is pickled and then a catalyst for chemical copper plating (Hitachi Chemical Co., Ltd.
It was immersed in HS101B) for treatment. Next, chemical copper plating 3
The thickness was about 1 μm, and the entire surface including the inside of the hole was plated with copper electrolytic copper having an average thickness of 30 μm. Subsequently, the surface was adjusted by sequentially performing buff polishing and permis polishing of the surface.

Next, a dry film made of Dyupon Co., Ltd., LISTON 1220, was laminated on the substrate by a hot roll heated to 110 ° C. An image having a pad with a diameter of 0.4 mm and a width of 0.12 mm was then formed by exposure and development. Next, hot pressing was performed at 140 ° C. for 10 minutes at a pressure of 5 kgf / cm ² . Next, spray etching was performed with an etching liquid containing cupric chloride to form conductor circuits on both surfaces of the substrate. The etching resist remaining on the surface was removed with methylene chloride to finally prepare a printed board.

Example 2 Step 1: A 1.6 mm thick double-sided copper clad glass epoxy laminate (copper foil thickness 18 μm) was drilled with a 0.4 mm diameter drill. After polishing the surface with a brush, the inside of the hole was washed with high pressure water. Then, the surface was soft-etched with an aqueous solution of ammonium persulfate, and further pickled. Subsequently, it was activated by immersion in a catalyst for chemical copper plating (sensitizer HS101B manufactured by Hitachi Chemical Co., Ltd.). Next, after pickling, soaking in a chemical copper plating solution of the following composition for 2 hours at 70 ° C. A chemical copper plating layer having a thickness of about 6 μm was formed.

Step 2: After completing Step 1, the surface was pickled and lightly roughened with an aqueous solution of ammonium persulfate (200 g / l). Then, the liquid having the following composition was treated at 70 ° C. for 2 minutes to form an oxide film layer having fine irregularities.

Further, the above oxide film was reduced with a treatment liquid having the following composition.

After washing with water to thoroughly clean the surface, it was plated with a matte electric nickel plating solution for 4 minutes at 0.05 A / dm ² . After washing with water and drying, a photosensitive dry film, Liston 1220, manufactured by Dyupon Co. was laminated with a hot roll heated to 110 ° C. Further, by exposing and developing, a plating resist was formed on portions other than the circuit forming portion. Then 140
Aged by heating at 0 ° C for 1 hour.

Process 3: After the completion of Process 2, the substrate is heated to 100 by hot plate pressing.
It was thermocompression bonded at 5 ° C. for 30 minutes at 5 kgf / cm ² .

Step 4: Next, it was immersed in an aqueous solution of ammonium persulfate (200 g / l), and the nickel plating layer exposed on the surface was removed by etching together with copper. After pickling and rinsing, soak it in a chemical copper plating solution of the following composition for 25 hours at 72 ℃
The thickness of the pattern was made by chemical copper plating.

After the plating was completed, the plate was thoroughly washed with water to complete the steps up to pattern chemical copper plating.

Example 3 In step 3 of Example 2, the substrate was heated at 120 ° C. for 30 minutes by hot plate pressing.
The steps up to the pattern chemical copper plating were completed in the same manner as in Example 2 except that heating and pressure bonding was performed at 5 kgf / cm ² .

Example 4 In the step 3 of Example 2, the substrate was heated to 140 ° C. at 10 ° C. by a hot plate press.
The steps up to the pattern chemical copper plating were completed in the same manner as in Example 2 except that heating and pressure bonding was performed at 5 kgf / cm ² .

Example 5 In the step 3 of Example 2, the substrate was heated at 160 ° C. for 2 times with a hot plate press.
The steps up to the pattern chemical copper plating were completed in the same manner as in Example 2 except that heating and pressure bonding was performed at 5 kgf / cm ² .

Example 6 In the step 3 of Example 2, the substrate was heated to 140 ° C. for 5 hours by hot plate pressing.
The process up to pattern chemical copper plating was completed in exactly the same manner as in Example 2 except that heating and pressure bonding was performed at 10 kgf / cm ² .

Example 7 In step 3 of Example 2, the substrate was heated at 160 ° C. for 20 minutes with a heat roll.
Secondly, the steps up to the pattern chemical copper plating were completed in the same manner as in Example 2 except that 3 kgf / cm ^{2 of} heat and pressure was applied.

Example 8 A thermosetting adhesive containing an acrylonitrile butadiene rubber-modified phenol resin as a main component was applied to both surfaces of a 0.8 mm-thick glass epoxy laminate and cured at 160 ° C. for 2 hours. After making holes of 0.4 mm diameter at the required places, the surface of the adhesive was roughened with chrome sulfuric acid. Then, after being treated with an aqueous sodium hydroxide solution, it was immersed in 15% hydrochloric acid and immediately thereafter immersed in a catalyst solution (sensitizer HS101B manufactured by Hitachi Chemical Co., Ltd.). After washing with water, it was treated with 3% hydrochloric acid and further washed with water. Allow to air dry and then 3 at 120 ° C
Dry for 0 minutes.

Then, a photosensitive drum film, FOTECK SR-3200, manufactured by Hitachi Chemical Co., Ltd. was laminated by a hot roll heated to 110 ° C. Further, by exposing and developing, an image was formed by the plating resist except the circuit forming portion. Then, the substrate was thermocompression-bonded at 140 ° C. for 15 minutes at a pressure of 7 kgf / cm ² using a hot plate. Then, after treating with an aqueous solution containing a surfactant and washing with water, a chemical copper plating solution having the following composition is used at 72 ° C,
After immersion for 12 hours, a plated film having a thickness of about 30 μm was obtained.

After completion of plating, the plate was washed thoroughly with water and dried to prepare a double-sided through-hole printed board.

Comparative Example 1 A printed board was prepared in the same manner as in Example 1 except that the photosensitive dry film was exposed and developed in Example 1 and no heat pressing was performed.

Comparative Example 2 The steps up to patterned chemical copper plating were completed in the same manner as in Example 2 except that step 3 in Example 2 was not performed.

Comparative Example 3 A printed board was produced in the same manner as in Example 8 except that the plating resist was not heat-pressed in Example 8.

The results obtained by the above-described examples and comparative examples will be described below. The printed board obtained according to Example 1 had no abnormalities in 20,000 through holes. On the other hand, in the printed board obtained in Comparative Example 1, the etching liquid penetrated into the through holes at three places out of 20,000, and copper was locally etched. As a result of observing the pad portion of the through hole where the etching liquid had penetrated, it was found that foreign matter was attached. In Example 1 as well, foreign matter was found to have adhered to seven places, but the etching liquid did not soak.

Further, in Examples 2 to 7, in spite of the chemical copper plating for 25 hours, the swelling and peeling of the resist were very small,
There was no problem in pattern formation. Moreover, almost no deformation of the resist due to thermocompression bonding was observed.

On the other hand, in the case of Comparative Example 2, peeling or blistering of the resist was locally observed. As a result of soldering in the next step, it was found that the peeled-off part of the resist was also plated, causing a problem in circuit formation. Circuit spacing in Example 3
In both cases of 0.3 mm and 0.1 mm, the insulation resistance after 10 hours at 40 ° C and 95% humidity was 10 ¹⁴ Ω / □ (DC100V applied). On the other hand, in Comparative Example 3, the circuit interval was 0.34 mm, which was 10 ¹⁴ Ω / □, but when the circuit interval was 0.1 mm, it was reduced to 10 ¹³ Ω / □.

〔The invention's effect〕

According to the present invention, it is possible to improve the adhesion to the underlying substrate without impairing the resolution of the photosensitive material. As a result, the subtractive method can prevent the etching liquid from soaking into the through-holes, etc., so that a fine and highly reliable printed board can be produced. Also,
By the pattern plating method and the partly additive method, it is possible to manufacture a fine and precise printed board. Further, the full additive method has an effect that the insulation resistance does not decrease even if the circuit gap is close.

[Brief description of drawings]

FIG. 1 is a manufacturing process diagram of a printed wiring board according to an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1 ... Insulating plate, 2 ... Copper layer, 3 ... Metal layer, 4 ... Plating resist, 5 ... Chemical copper plating, 6 ... Soldering plating

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Mineo Kawamoto 4026 Kuji Town, Hitachi City, Ibaraki Prefecture Hitachi Research Laboratory Ltd. (72) Inventor Ritsuji Toba 1 Horiyamashita, Hadano City, Kanagawa Prefecture Inside the Kanagawa Plant (72) Inventor Motoyo Wajima 1 Horiyamashita, Hadano City, Kanagawa Prefecture Hiritsu Manufacturing Co., Ltd.Inside the Kanagawa Plant (72) Inventor Masashi Miyazaki 1 Horiyamashita, Hadano City, Kanagawa Prefecture (72) Inventor Toshiaki Ishimaru 4-13-1, Higashi-machi, Hitachi City, Ibaraki Prefecture Hitachi Chemical Co., Ltd. Ibaraki Research Laboratory (72) Inventor Akio Nakano 4-1-1, Higashi Town, Hitachi City, Ibaraki Prefecture Ibaraki Research Institute Co., Ltd. (56) Reference JP-A-50-118674 (JP, A) JP-A-62-93994 (JP, A)

Claims (6)

[Claims] 1. A photosensitive material layer is provided on a desired substrate surface,
After performing image exposure and development to form a resist image,
In the printed board on which the circuit is formed, the resist image is
A printed board, which is heat-pressed on a substrate at a temperature at which the photosensitive material softens and flows after forming a resist image. 2. A photosensitive material layer is provided on a desired substrate surface,
In a method of manufacturing a printed circuit board, in which a resist image is formed by performing image exposure and development and then a circuit is formed, after the resist image is formed, the resist image is heated and pressure-bonded onto a substrate at a temperature at which the photosensitive material softens and flows. A method for manufacturing a printed board, which is characterized by the above. 3. The method for manufacturing a printed board according to claim 2, wherein the resist image is an etching resist image or a plating resist image. 4. The method for manufacturing a printed board according to claim 2, wherein the photosensitive material is a photosensitive dry film. 5. A means for forming a photosensitive material layer on the surface of a substrate,
Means for forming a resist image by exposing and developing the formed photosensitive material layer, means for thermocompression bonding the resist image on a substrate at a temperature at which the photosensitive material softens and flows, and a circuit from the substrate having the obtained resist image An apparatus for manufacturing a printed board, which comprises a means for forming a board. 6. The printed board manufacturing apparatus according to claim 5, wherein the means for thermocompression bonding is a hot plate press or a single-stage or multi-stage heating roll.