JPH01282885A - Manufacture of printed wiring board - Google Patents

Abstract

PURPOSE:To obtain a printed wiring board having an aluminum wiring and a copper wiring by using ultraviolet ray hardening type etching resist ink wherein the hardening film has solubility to a particular solvent and acidproof and alkalineproof properties. CONSTITUTION:A substrate, wherein composite foils of an aluminium foil 4 and a copper foil 3 are connected on an aluminium plate 1 through an epoxy resin insulating layer 2 while holding the surface of the aluminium foil 4 upward, is obtained. The rear of the substrate is protected by a film 5 with an adhesive. Next, a prescribed pattern is continuously printed by using acidproof and alkalineproof acryl ultraviolet ray hardening type etching resist 6. Next, a strong base water solution is spray on the substrate and the aluminium foil 4 of the composite foils is etched in a pattern shape so as to obtain an aluminium wiring 8. A copper wiring 7 is formed by the similar process in order to finally obtain a printed wiring board consisting of an aluminium wiring 8 and a copper wiring 7.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention provides an ultraviolet curing type etching resist.
The present invention relates to a method of manufacturing a printed wiring board in which aluminum wiring and copper wiring coexist.

(Prior Art) Conventionally, printed wiring boards in which copper wiring is formed on an insulating substrate have been mainstream. However, with the recent trend toward high-density packaging of electronic components, printed wiring boards with aluminum wiring and copper wiring formed on the same substrate are now capable of connecting semiconductor bare chips by wire bonding and soldering other electronic components. Therefore, it attracted attention and began to be manufactured.

However, the conventional manufacturing method for printed wiring boards with copper wiring involves forming a heat-drying etching resist on a copper-clad laminate by screen printing, etching the copper, and then removing the etching resist. The method used to be rejected. However, in recent years, etching resist ink, which is cured by ultraviolet rays, is increasingly being introduced into the etching resist because it increases the productivity of printed wiring boards.

In addition, these heat-drying and ultraviolet curing type etching resists have traditionally been solvent-removable types, but in recent years alkali-removable inks have been increasingly adopted due to their low cleaning costs and pollution prevention. It looks like this. On the other hand, the manufacturing process for printed wiring boards with aluminum wiring and copper wiring includes: ■ resist formation, ■ aluminum etching, ■ copper etching, ■ resist removal, ■ resist formation, ■ aluminum etching, ■
There is resist removal.

Here, since a strong alkali is used for etching aluminum in (2), the above-mentioned alkali removal type ink cannot be used. Therefore, a solvent-removable heat-drying etching resist ink has usually been used.

However, the solvent-removable heat-drying etching resist ink that has been conventionally used as the etching resist in steps ① and ② contains a solvent, and the solvent in this ink evaporates during printing. The viscosity of the ink on the screen plate increases and the printed wiring width changes, and in more severe cases, the ink dries during printing, resulting in poor transfer due to screen clogging and screen abnormalities. This causes elongation, etc., which causes printing defects.

In order to suppress the evaporation of the solvent in the ink, the solvent in the ink is replaced with a high boiling point solvent, but this requires a high drying temperature and a long drying time.
There was a drawback that productivity decreased.

Ultraviolet curing type etching resist inks have been developed to solve these drawbacks, but since all of them are resist inks for copper etching, alkali-removable types are mainstream, and the alkali resistance of the above-mentioned process The required aluminum elatine brace) K could not be used.

In addition, UV-curable resist inks for plating have also been developed, but because emphasis is placed on chemical resistance, the cured ink is highly cross-linked, and even if it can be removed with methylene chloride, it is Commonly used 1, 1
, has drawbacks that cannot be removed by 1-trichloroethane.

(Problems to be Solved by the Invention) The present invention solves problems that could not be achieved by using such heat-dried etching resist ink and conventional ultraviolet curable ink.
A method of manufacturing a printed wiring board having aluminum wiring and copper wiring is provided.

The inventors of the present invention made extensive studies in view of the above drawbacks, and found that by using an ultraviolet curing etching resist ink, the cured resist ink has excellent acid resistance and alkali resistance and can be removed with 1.1.1-trichloroethane. We have invented a method for manufacturing printed wiring boards having aluminum wiring and copper wiring that has excellent productivity and fewer defects.

(Means for solving the problem) 1. Step 2 of screen printing 1) acid-resistant and alkali-resistant ultraviolet curable etching resist ink on the aluminum foil surface of a printed wiring board laminated with aluminum/copper composite foil. ) Next, the resist ink is cured with ultraviolet rays, and then the aluminum/copper composite foil is etched. Step of forming a pattern 4) Screen printing an alkali-resistant ultraviolet curable etching resist ink on any part of the wiring pattern formed in steps 1) to 6) Step 5) Next, curing the resist ink with ultraviolet rays. After cleaning, the aluminum ie on the wiring pattern is etched with a strong alkaline etching solution.
6) Selective etching step 6) A method for producing a printed wiring board, further comprising at least six steps of removing the cured product of the etching resist ink with a chlorine-containing organic solvent having two carbon atoms as a main component. .

Next, the method for manufacturing a printed wiring board of the present invention will be explained in more detail.

In order to form the aluminum wiring according to the present invention, a printed wiring board in which aluminum/copper composite tubes are laminated is used. Examples of this aluminum/copper composite tube include clad foil of aluminum foil and copper foil, foil plated with copper on aluminum foil, and foil with a different metal plated between the aluminum foil and copper plated foil. .

Substrate materials to which these composite foils are bonded include organic materials such as phenol resin, epoxy resin, polyimide resin, and polyester resin, or composite materials in which these organic materials are filled with glass fiber or filler. The composite foil is bonded using an adhesive.

Furthermore, substrate materials include metal materials such as aluminum, iron, and stainless steel, and by bonding the aforementioned composite foils using an adhesive such as epoxy resin while maintaining insulation, printed wiring with laminated composite foils can be created. You can make a board.

Next, the first step in the present invention is to screen print an acid-resistant and alkali-resistant ultraviolet curing type etching resist onto the aluminum foil surface of the printed wiring board described above. Furthermore, it is preferable to perform a surface treatment on the aluminum foil surface by degreasing, puff polishing, etc. prior to screen printing in order to ensure reliability of adhesion with the etching resist. The degreasing method may be alkaline degreasing, acid degreasing, or solvent degreasing, which are usually used when degreasing aluminum surfaces.

The acid-resistant and alkali-resistant ultraviolet curable etching resist ink used in this process has two characteristics: (1) the cured resist can withstand the strong alkaline etching solution used in etching aluminum foil; The hardened resist can withstand copper etching liquid, and furthermore, the resist after being exposed to this aluminum etching liquid and copper etching liquid is often used industrially and has low toxicity.1.1
．． It is necessary to be able to remove it with 1-trichloroethane.

Examples of ultraviolet curable etching resist inks that can be used for this purpose include monofunctional oligoester acrylates (for example, ○H), where n is usually 1 to 6, but is not particularly limited. (Also, those having an alkyl substituent on the benzene nucleus can also be used.) and ■1゜1.1-1! Oligomers or polymers that are soluble in J chloroethane and are resistant to acid and alkali (for example, methyl methacrylate oligomers, alkyd resins, copolymers of styrene and acrylic esters, etc.); ■ Inorganic fillers such as talc; and ■ Some products contain at least four photosensitizer components as main components.

Next, the second step in the present invention is to cure the resist 1 ink with ultraviolet rays, and then to etch the aluminum foil into a wiring pattern using a strong alkaline etching solution.
Furthermore, this is a step of etching the copper foil other than the aluminum wiring using a selective etching agent that etches only the copper without removing the resist.

The ultraviolet curing in this step can be performed in a commercially available ultraviolet irradiation furnace equipped with an ultraviolet lamp such as a high-pressure mercury lamp, an ultrasonic mercury lamp, or a metalno-ride lamp. Further, the lamp is selected depending on the absorption wavelength of the photosensitizer contained in the ultraviolet curing type etching ink.

In addition, for the etching of aluminum foil in this process, an aqueous solution of inorganic strong alkaline compounds such as caustic soda and caustic potash containing various fi additives is used.The feature is selective etching that etches the aluminum foil but not copper. It's in the drug.

The concentration of this strongly alkaline inorganic compound used is 5 to 60% by weight. In addition, this etching solution is usually heated at 40° to 70°C to reduce the viscosity of the solution and make it easier to spray during etching, as well as to increase the etching speed.
It is used after being heated. If the concentration of this strongly alkaline inorganic compound is less than 5% by weight, the etching speed will be slow even when heated, and if it exceeds 60% by weight, the liquid will not have a high viscosity even when heated, making it difficult to spray uniformly. It becomes difficult.

Next, the aluminum foil used in this process is not etched,
As a selective etching agent for selectively etching only the copper foil, a sulfuric acid-hydrogen peroxide type etching agent or an aqueous solution of performate such as ammonium persulfate or sodium persulfate is used.

Further, the sixth step according to the present invention is to wash the substrate with the etching resist after the second step with a chlorine-containing organic solvent having two carbon atoms as a main component to remove the resist ink. It is in. Here, the chlorine-containing organic solvent having two carbon atoms includes 1.1.1-trichloroethane, trichloroethylene, tetrachloroethylene, etc., and 1.1.1-trichloroethane is preferable from the viewpoint of toxicity.

The fourth step in the present invention is a step of screen printing an ultraviolet curable etching resist ink having at least alkali resistance on the wiring pattern formed in steps 1 to 6. The UV-curable etching resist ink used here can be the same as the acid- and alkali-resistant UV-curable etching resist ink used in step (1), or it can be an alkali-resistant UV-curable etching resist ink. You can.

In the fifth step of the present invention, after the resist ink is cured with ultraviolet rays, the aluminum foil of the wiring pattern is selectively etched in a pattern as necessary using the strong alkaline aluminum etching liquid used in the second step. be. Through this process, the copper foil is formed into a pattern, and a copper wiring portion that can be used as a soldering portion is formed.

Furthermore, the sixth step in the present invention is to remove the etching resist ink with a chlorine-containing organic solvent having two carbon atoms as a main component, and is the same resist removal step as in the sixth right of the present invention. be.

The printed wiring board in the present invention is usually subjected to mechanical processing such as solder resist formation and press punching as post-processing.

(Example) Next, the present invention will be explained in detail.

Example 1 The size shown in Fig. 1 is 200 x 200 mm, and the thickness is 1.01 mm.
A composite foil of 40 μm aluminum foil 4 and 10 μm copper foil 3 is placed on aluminum plate 1 of 11 through an 80 μm thick epoxy resin insulating layer 2.
200 substrates were used, which were bonded with their sides facing up.

First, the aluminum on the back side of the substrate was protected with an adhesive film 5 to prevent it from being attacked by the etching solution (FIG. 1).

After degreasing four sides of the aluminum foil with an alkaline degreaser, 200 sheets were continuously printed using an automatic printing machine using an acid-resistant and alkali-resistant acrylic ultraviolet curing etching resist ink 6 (FIG. 2). The screen plate used for this printing was a 600 mesh polyester screen, and the pattern used was 5014 with a minimum line width of 50 μm).
), four L-shaped wirings with the same line width and line spacing are arranged in 10 rows and 10 columns in a size of 200 x 200jljtO (maximum line width is 600 μm).

The viscosity increase of the ink was about 10% after printing 200 sheets.

The printed board is immediately 4. The material was cured by being placed in an ultraviolet irradiation device having a conveyor speed of 0.0 m/m and equipped with an 80W 5-light high-pressure mercury lamp. The time required from printing to curing of the resist was 40 minutes.

When the substrate on which the resist had been cured was examined under a microscope, it was found that the resolution of the pattern was very good, with lines of 150 μm being able to be resolved. Furthermore, there were no defects such as clogging of the screen. The line width of the design @ 250 μm was measured every 50th sheet.
However, it was within the range of 270 μm±15 μm, and stable printing was possible.

Next, a strong alkaline aqueous solution containing 20% by weight of caustic soda was applied to the ultraviolet-cured etching resin substrate.
Spray for 2 minutes at 0°C and remove the composite foil aluminum foil 4.
was etched into a pattern to obtain aluminum wiring 8 (FIG. 6). Thereafter, the substrate was washed with water and dried, and then 20 volumes of sulfuric acid, which is a selective etching agent for steel, and 10 volumes t% of Perma-Etch (trade name of Ebara Electric Corporation, containing 50 volumes of hydrogen peroxide) were added. Mixed etching solution at 54°C1
The copper wiring 7 was obtained by spray etching for a minute, and then washed with water and dried (FIG. 4).

Thereafter, in the sixth step of the present invention, 1,1°1-trichloroethane was sprayed at room temperature to peel off the etching resist 6 (FIG. 5). A microscopic examination of the resulting aluminum wiring 8 with a wiring width of 250 μm revealed no traces of harmful resist peeling during etching, and no resist remaining on the wiring.

Next, as the fourth step, the completed aluminum wiring 8
Using the same screen plate, the same wiring pattern, and the same ultraviolet curing type etching resist ink 6, the etching resist ink 6 was continuously printed on 200 substrates so that the wiring patterns were partially perpendicular to each other (Fig. 6). ).

The printed substrate was immediately passed through an ultraviolet curing device to cure the resist ink 6. The cured resist ink 6 is
As a result of microscopic examination, there was no harmful disconnection or bleeding in the part of the resist ink 6 perpendicular to the aluminum wiring 8 having a thickness of 40 μm.

Next, the ultraviolet-cured etching resist 6 substrate was coated with a strong alkaline aqueous solution containing 20% by weight of caustic soda.
Spray for 2 minutes at °C and composite foil aluminum wiring 8
was etched into a pattern (Figure 7). Thereafter, the substrate was washed with water and dried, and 1,1°1-trichloroethane was sprayed at room temperature to peel off the etching resist 6 (FIG. 8).

A microscopic examination of the finally obtained mixed wiring consisting of the aluminum wiring 8 and the copper wiring γ with a wiring width of 250 μm revealed that there was no harmful peeling of the resist during etching, and no resist remained on the wiring.

Comparative Example 1 Using the same substrate as in Example 1, the first step was to use a heat-drying resist ink with strong alkali-resistant MR-500 (
When screen printing was performed on 200 sheets consecutively in the same manner as in Example 1 using Asahi Kakensha Rifu), ink flow was poor after printing up to the 10th sheet. Another 50-1
Good printing was achieved on the 00th page, but after the 100th page, the ink began to fade. The increase in ink viscosity after printing was about 200%.

Next, after drying in a blower dryer at 110°C for 10 minutes, the printed wiring was inspected under a microscope. Even on a well-printed board, the minimum wiring width that could be resolved was 200 μm. There were many scratches, and even broken wiring on a bad board was marked W7.

The time required from printing to drying was 60 minutes, but in actual manufacturing of printed wiring boards, if the ink fades, the product cannot be produced, so we stopped printing and
Wiping the plate with a solvent significantly increases work time and reduces productivity. .

Note that aluminum etching and copper etching were performed under the same conditions as in Example 1. Inspection after removing the resist with i-tricrocoethane did not reveal any abnormal resist peeling during etching.

Next, in the same manner as in the fourth step of Example 1, ultraviolet curing type etching resist ink was added to heat drying type resist ink M.
R-500 (manufactured by Asahi Kaken Co., Ltd.) was used instead. As a result, as in the first step, an increase in the viscosity of the ink was observed, and partial blurring was observed in the wiring pattern formed by the printed resist ink. Thereafter, as a fifth step, the aluminum foil was etched in the same manner as in Example 1, and further 1,1.1-
The resist was removed with trichloroethane. The aluminum foil was etched in the areas where the resist was faded, resulting in a defective board.

(Effects of the Invention) As described above, the present invention provides a printed wiring board having aluminum wiring and copper wiring using an ultraviolet curable etching resist ink that has acid resistance, alkali resistance, and solubility in special solvents. This is a manufacturing method that is characterized by both high productivity and reliability.

[Brief explanation of the drawing]

Figures 1 to 8 are schematic diagrams for explaining the manufacturing process of the printed wiring board in Example 1. Figures 1 to 5 are partially enlarged sectional views, and Figures 6 to 8 are partial views. This is an enlarged plan view. Code 1. Aluminum plate 2, insulating layer 3, copper foil 4, aluminum foil 5, protective film 6, etching resist ink 7, copper wiring 8, aluminum wiring patent applicant Denki Kagaku Kogyo Co., Ltd.

Claims (2)

[Claims] 1. 1) Screen printing an acid-resistant and alkali-resistant ultraviolet curable etching resist ink on the aluminum foil surface of a printed wiring board laminated with aluminum/copper composite foil. 2) Next, the resist ink is cured with ultraviolet rays. After that, a step of etching the aluminum/copper composite foil 3) A step of removing the cured product of the etching resist ink with a chlorine-containing organic solvent having two carbon atoms as a main component to form a wiring pattern 4) The step of the step 1) Step 5) of screen printing an alkali-resistant ultraviolet curable etching resist ink on any part of the wiring pattern formed in steps 3) to 5) Then, after curing the resist ink with ultraviolet rays, A print characterized by comprising at least six steps of selectively etching the aluminum foil on the wiring pattern; and (6) further removing the cured product of the etching resist ink with a chlorine-containing organic solvent having two carbon atoms as a main component. Method of manufacturing wiring boards. 2. 2. The method of manufacturing a printed wiring board according to claim 1, wherein the printed wiring board is laminated on at least one principal surface of a metal plate with an insulating layer interposed therebetween.