JPS583400B2 - Printed Cairo Banno Seizouhouhou - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for forming circuits directly on a substrate by cluster ion plating and electrolytic plating.

More specifically, the circuit is formed on the substrate by cluster ion plating and electrolytic plating through a resist circuit pattern and a mask with a reverse pattern, which eliminates the etching process, which is rational, simple, and non-polluting. The purpose of the present invention is to provide a resource-saving, high-performance printed circuit board manufacturing method.

Conventionally, commonly used printed circuit boards are made by bonding 35 μm to 70 μm copper foil to a plastic board using an adhesive by pressing or laminating, and then attaching the copper foil to the copper foil surface of the printed circuit board. It is created by printing a pattern using a resist using a photo method or a screen method, and then removing copper other than the circuit by etching.

However, with this method, it is impossible to create highly accurate fine circuits because the copper foil is thick, it is impossible to create thin and light printed circuit boards such as those used for vibrating parts, and it is difficult to create printed circuit boards that are thin and light such as those used in vibrating parts. Disadvantages include that it is inconvenient to create composite circuits, that most of the copper foil is discarded by etching, resulting in a waste of resources, and that the etching process requires pollution prevention equipment.

Furthermore, various methods have recently been attempted in which circuits are formed directly on a substrate by vapor deposition methods such as vacuum vapor deposition and sputtering.

However, even with these newly attempted methods, the adhesion strength between the vapor-deposited metal film and the substrate is generally weak, at a beer strength of 0.3 kg/cm or less, making it unreliable as a circuit board. In this case, it is difficult to create thick microcircuits because the vapor-deposited metal wraps around the back side of the mask, and when resist ink is used for the mask, the adhesive strength between the vapor-deposited film and the substrate is weak, so there is a process of removing the resist. The disadvantage is that the vapor deposited pattern on the circuit portion tends to peel off, and this phenomenon becomes more pronounced as the thickness of the vapor deposited film increases.

The present inventors solved the shortcomings of conventional methods and studied a method for manufacturing printed circuit boards rationally and easily.As a result, the cluster ion plating method produces a film with good film quality and strong adhesion strength on a substrate. The inventors discovered that it was possible to create a metal film with a high level of elasticity, and after further investigation, they came up with the present invention.

That is, in the present invention, a mask is formed by printing a reverse pattern of a circuit pattern using a resist using photo printing or screen printing on a substrate, a metal is vapor deposited on the mask using a cluster ion plating method, and a second pattern is formed using a resist. After forming a mask that is synchronized with the first layer mask and thickening only the circuit portion by electrolytic plating, the first and second layer resists and the metal film on the first layer resist are peeled off to form a printed circuit. It consists of getting a board.

Next, an example of the present invention will be explained with reference to the drawings.

First, a substrate 1 is cleaned, and a reverse pattern 2 of a desired circuit pattern is printed on it using a resist using a method such as screen printing, photo printing, or offset printing (FIG. 1).

In the case of screen printing, it is printed using a silk screen or stainless steel screen and dried in a vacuum to the extent that a large amount of gas is not generated.

In the case of photo printing, a photoresist is applied to the entire surface of the substrate to a thickness of about 20 μm using a roll coater or spray, and once dried.

Next, a positive film is placed on the resist and exposed, and the circuit portions that are not exposed to light are removed with a solvent such as trichlene and dried.

Offset printing is used especially for fine patterns, but it still requires appropriate drying after printing.

Next, metal is deposited over the entire surface from the resist side by cluster ion plating to form metal film layers 3 and 3' (FIG. 2).

Thereafter, using a resist, a pattern 4 identical to the button originally printed on the substrate is printed in the same manner on the metal film deposited so as to match the position of the first layer button (FIG. 3).

Thereafter, the circuit pattern portion 3' not covered with the second layer resist is thickened by electrolytic plating 5 (FIG. 4).

Next, the first layer resist 2, the metal vapor deposited film 3 on the first layer resist, and the second layer resist 4 are removed using a resist stripping solution, and as a result, the desired thickness thickened by electrolytic plating is removed. A printed circuit board can be obtained (Figure 5).

A preferred method for removing the resist and the metal vapor deposited film on the resist is, for example, a method in which the formed product is immersed in a resist removal solution and then gradually removed using a brush, brush, cloth, or the like.

Substrates used in the present invention include thermosetting resin laminates such as phenol-based laminates, epoxy resin laminates, and imide resin laminates, thermoplastic resin laminates such as polyester, polypropylene, polyimide, polystyrene, Tefrene, and polyvinylidene fluoride. It can be applied to sheets or films made of resin and plate-shaped objects made of various ceramics, and the thickness of these is not particularly limited, but is generally between 1 μm and 1 μm.
0 mm is appropriate.

In addition, the resist used here is preferably a water-soluble or oil-soluble resist, and in the case of a water-soluble resist, a 25°C caustic soda 35 aqueous solution is used, and in the case of an oil-soluble resist, a solvent such as triclene, MEK, perchlorethylene, etc. at 25°C is used. When a 20 μm thick resist that has been dried at 100° C. for 30 minutes is immersed in a resist stripping agent containing these as main ingredients, it is preferable that it dissolves in 60 seconds or less.

Examples of water-soluble resists include polyvinyl alcohol,
There are those whose main components are casein, glue, etc., and oil-soluble resists whose main components are rubber, vegetable oil, mineral oil, acetate, vinyl compounds, etc., and mixtures thereof.

Of course, a photosensitizer or the like may be added to the resist used for photographic printing depending on the purpose.

An example of the outline of the cluster ion plating method used here is as follows (FIG. 6).

In a vacuum chamber 7 at a pressure of 10-3 to 10-6 Torr, a crucible 12 with a small hole is placed in which metal used for vapor deposition is placed.
The crucible is heated to 00 to 2000°C and metal vapor is ejected from the small holes of the crucible.

The ejected metal vapor expands adiabatically due to the pressure difference inside and outside the crucible and is rapidly cooled, forming clusters (clusters of weakly bonded atoms) and traveling upwards, where they are ionized by the impact of electrons generated from the ionization heater 9. Ionizing anode 1
It is drawn out to the accelerating electrode 8 which is at a negative potential with respect to 0, and as a result, it is accelerated and reaches the substrate, forming a metal film together with non-ionized clusters.

According to this method, the cluster ions in the metal cluster reach the substrate with energy corresponding to the acceleration voltage applied to the ionization anode and the acceleration electrode and form a nucleus.
Strong adhesion strength can be obtained.

Generally, the adhesion strength is 0.8 kg/cm or more in terms of peel strength.

Also, according to this method, cluster ions are accelerated, so
In addition, since the non-ionized clusters move straight toward the substrate due to the kinetic energy obtained when ejected from the crucible, when masking is performed, there is little wraparound and the boundary between the mask and the metal film is sharp.

Of course, various methods can be selected as appropriate for the crucible heating method, cluster ionization method, cluster ion acceleration method, etc. depending on the purpose, type of metal, etc.

The electrolytic plating method used here is not particularly limited and may be any commonly used electrolytic plating method.

For example, as a method for electrolytic plating of copper, there is a method using an aqueous copper sulfate solution or an aqueous copper pyrophosphate solution as an electrolytic plating solution.

Here, the plating speed should be selected according to the purpose in order to improve the crystallinity of the plating film and reduce the plating stress, but it is generally better to set it as slow as possible.

Next, the thickness of the first and second resist layers, the metal film formed by cluster ion plating, and the electroplated film may be selected appropriately depending on the type of substrate, the purpose of the circuit board, the density of the circuit, etc. Although not limited, in order to efficiently obtain a sharp and accurate circuit, the thickness of the metal pattern formed by cluster ion plating should be approximately the same to 1/30 of that of the first layer resist, and more preferably 1/3 to 1/3. 30
Good quality, thickness 0.01μm to 20μm,
More preferably, the thickness is from 0.01 μm to 5 μm.

The thickness of the first layer resist depends on the printing method and the type of resist, but is preferably 5 μm to 50 μm.

Further, in order to maintain the dimensional accuracy of the pattern, the thickness of the second layer resist is preferably equal to or greater than the thickness of the electrolytic plating film, and preferably 5 μm to 50 μm.

The method of manufacturing printed circuit boards according to the present invention has many advantages over conventional methods.

That is, (1) the etching process is not necessary, so the process is shortened.

Moreover, it is a non-polluting manufacturing method, and no pollution prevention equipment is required.

(2) Since a metal film with stronger adhesion to the substrate is formed compared to other vapor deposition methods, in the process of removing the resist,
It is possible to create highly accurate, reliable, and high-performance printed circuits without damaging the metal film of the circuit part.

(3) The metal film formed by the cluster ion plating method has good film quality, so electrolytic plating adheres well. In many cases, there is no need to treat by physical or physical means.

(4) Since the circuit portion is thickened by electrolytic plating, the metal film formed by the cluster ion plating method can be extremely thin, and printed circuits can be produced efficiently and at low cost.

Furthermore, circuits can be made thicker with various metals that can be electrolytically plated depending on the purpose, and distinctive printed circuits can be created.

(5) With other vapor deposition methods, the boundary between the metal film on the mask and the substrate is unclear, and it is difficult to obtain a sharp circuit even if the resist of the mask and the metal film on the mask are removed. Due to the straightness of the cluster, the metal film 3' that forms the circuit and the metal film 3 on the resist can be easily cut and the adhesion strength is strong, so that the resist is removed smoothly and is highly reliable. , a sharp printed circuit can be obtained.

As described above, the method for producing a printed circuit board according to the present invention has excellent characteristics, and is a simple, highly accurate, and industrially extremely effective method.

Example 1 A 10 μm thick inverse pattern of the circuit pattern was printed on a 75 μm thick polyimide film by photo printing using an oil-soluble resist, and after air drying, it was dried in the open at 80° C. for 30 minutes.

Thereafter, copper is deposited on the entire surface by cluster ion plating to a thickness of about 1 μm.

This vapor deposition by cluster ion plating is performed at an ionization power of 100 W, an accelerating voltage of 3 KV, and a vapor deposition rate of 500 A.
The deposition was performed under the vapor deposition conditions of /min.

Furthermore, a second resist layer is formed on this copper film in synchronization with the first resist layer.
The resist layer of the layer was printed to a thickness of 20 μm by photo printing using an oil-soluble resist, and was heated in the open at 80°C for 30 minutes.
Drying was performed for 0 minutes.

Next, copper was plated to a thickness of about 15 μm by electrolytic plating to thicken the batten part, and then the first and second resist layers and the copper film layer by ion plating in areas other than the pattern were lightly plated in Triclean. As a result of peeling using a brush, a high-density flexible printed circuit board with excellent adhesion and precision was obtained.

If vacuum evaporation and sputtering are used instead of cluster ion plating in the same manner as above,
Due to the weak adhesion strength, the circuit part peeled off during the final peeling process, making it impossible to obtain a printed circuit board that could withstand practical use.

Example 2 Using a water-soluble resist mainly composed of polyvinyl alcohol on a 0.8 mm thick glass cloth base epoxy resin laminate, a 5 μm thick reverse pattern of the circuit pattern was printed using photo printing, and opened after air drying. Drying was performed at 80° C. for 30 minutes.

After that, copper was deposited on the entire surface to a thickness of about 0.5 μm using cluster ion plating, and a second resist layer was applied on top of it by screen printing using a water-soluble resist in synchronization with the first resist layer. , was printed to a thickness of about 25 μm and dried.

Next, copper is plated to a thickness of about 20 μm by electrolytic plating to thicken the batten part, and then the copper film is formed by ion plating the first and second resist layers and parts other than the batten in a 10% caustic soda aqueous solution. By gently peeling off the layers using a brush, we were able to obtain a high-density printed circuit board with excellent adhesion strength that can withstand practical use.

[Brief explanation of the drawing]

1 to 5 are process schematic diagrams of an embodiment of the method of the present invention. FIG. 6 is a schematic diagram of a cluster ion plating apparatus. In the figure, 1 is the substrate, 2 is the first layer mask made of resist,
3 is a metal film on the resist, 3' is a metal film on the substrate, 4 is a mask for the second layer of resist, 5 is a plated part by electrolytic plating, 6 is a substrate electrode, 7 is a vacuum chamber, and 8 is an accelerating electrode. , 9 is an ionization heater, 10 is an ionization anode, 1
1 is a heater for heating the crucible, 12 is a crucible, and 13 is a metal to be vapor-deposited.

Claims (1)

[Claims] 1 Form a mask by printing a reverse pattern of the circuit pattern with resist on the substrate, then deposit a metal film on the substrate and resist using cluster ion plating method, and then align the position with the first layer mask. A second layer of mask is formed by printing a resist as shown in FIG. 1. A method for manufacturing a printed circuit board, the method comprising: creating a circuit by peeling off a metal film and a second layer of resist.