JPS6351396B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a printed circuit board, and its purpose is to provide a method for manufacturing a printed circuit board, particularly a three-dimensional printed circuit board, with easy steps and good workability. It's there.

Conventionally, a printing method has been adopted for producing printed circuit boards for electric circuits. For example, a printing paste containing a conductor as the main component is printed directly onto a substrate such as insulating ceramic using a screen printing method, baked at a predetermined temperature, and then a printing paste containing a resistor as the main component is printed directly onto a substrate such as insulating ceramic using a screen printing method. There is a method of producing a printed circuit board by printing and re-baking.
However, this method can only be applied to substrates that can be directly printed, such as planar substrates for printed circuit boards. Furthermore, since the printing and baking of a printing paste containing a conductor as a main component onto a base material and the printing and baking of a printing paste containing a resistor as a main component must be performed in separate processes, it is difficult to conduct a conductive material in a complex circuit pattern. This method has the disadvantage of causing a decrease in accuracy such as misalignment between the resistor and the resistor, and as a result, the number of defective printed circuit boards has increased. Furthermore, when directly printing on a perforated base material, there are disadvantages in that the printing paste bleeds through the holes onto the base material, stains the plate, and stains the base material, and there is also a large loss of expensive printing paste made of precious metals. Was.

In order to solve the drawbacks of the direct printing method,
A wet slide-off transfer method has been proposed. This method uses a transfer paper in which conductor or resistor figures are printed on a transparent or translucent plastic sheet with mold releasability, and the transfer paper is moistened with water or alcoholic water. There is a method in which the plastic sheet is placed on top of the paper for alignment, dried, peeled off, and then fired (see Japanese Patent Publication No. 16387/1987), and a method in which a water-soluble glue layer is provided on water-absorbing paper. A circuit pattern printing layer formed by printing a printing paste containing a conductor or a resistor as a main component is provided on top of the transfer paper, and a removable cover coat is provided on the transfer paper, and the transfer paper is immersed in water or hot water. After dipping the paper to dissolve the water-soluble adhesive layer and separating the paper, the cover coat and the base material for the printed circuit board are overlapped and aligned, and the cover coat is peeled off after drying. (Refer to Publication No. 16388/1983). The wet slide-off transfer method using these transfer papers can also be applied to three-dimensional printing board substrates, and if a circuit pattern is formed on the transfer paper, conductors and resistors can be transferred at the same time. Since it is possible to print on the printed circuit board, even in complex circuit patterns, there is no risk of deterioration in accuracy such as misalignment between the conductor and the resistor. Furthermore, even when applied to perforated substrates, since the printing paste is printed on paper or plastic sheets, there is no possibility of the printing paste transferring to the substrate, staining the plate, or staining the substrate. There is also less loss of printing paste. However, this wet slide-off transfer method requires most of the steps to be carried out manually, and therefore has drawbacks such as poor workability and inability to mass-produce. That is, in these inventions, when a circuit pattern is formed on a base material for a printed circuit board, it is necessary to align a transfer paper on which a very precise circuit pattern is formed by superimposing it on the base material in a wet state. Furthermore, when performing slide-off transfer onto a three-dimensional printing board base material, there is a risk that the transfer paper may sag, resulting in overlapping circuits or breakage.
It has the disadvantage that it is not possible to form complex circuit patterns.

In view of the above-mentioned current situation, the present inventors have conducted various research experiments and have found a method for solving all of the above-mentioned drawbacks and producing a printed circuit board with easy steps and good workability. That is, the present invention is a circuit pattern printed on a non-stretchable base sheet 1, which is composed of an elastomer film 2 and a water-soluble and adhesive printing paste mainly composed of a conductor, a resistor, or a dielectric. Peeling the base sheet 1 from the transfer material 5 formed by laminating the transfer layer 4 consisting of the layer 3,
After humidifying the transfer layer 4, the circuit pattern printing layer 3 is placed in contact with the surface of the printed circuit board base material 6, and then an elastic body 7 is pressed from the elastomer film 2 side of the transfer layer 4 to remove the printing. A printed circuit board characterized in that the base material 6 for a circuit board and the transfer layer 4 are brought into pressure contact with each other, a circuit pattern is formed on the surface of the base material 6 for a printed circuit board, the elastomer film 2 is peeled off, and the elastomer film 2 is then fired. This is a manufacturing method.

The present invention will be explained in more detail below. The transfer materials used in the present invention include a base sheet 1, an elastomer film 2, and a circuit pattern printed layer 3.
(See Figure 1). As the base sheet 1, a film that does not expand or contract due to heat, tension, etc. is used. This is elastomer film 2
When printing the circuit pattern printing layer 3 on top, misregistration and misalignment of the circuit pattern caused by the expansion and contraction of the elastomer film 2 are prevented by supporting it with the base sheet 1, which is complicated and requires precision. This is to ensure that the circuit pattern to be used can be accurately obtained. Examples of such materials include plastic films such as polyethylene terephthalate, polypropylene, vinyl chloride, and nylon;
Examples include paper such as release paper, glassine paper, cellophane, and the like. As the elastomer film 2, one is used that is peelable from the base sheet 1, has ductility, has printability, and has excellent mold releasability for printing paste. This elastomer film 2 must be able to stretch without breaking when pressed by the elastic body 7 and be in close contact with the surface of the printed circuit board base material 6. Examples of such resins include polyurethane resins, polyester resins, and styrene-butadiene block copolymer resins. These resins are applied to the entire surface of the base sheet 1 by an extrusion method, a roll coating method, a reverse coating method, a bar coating method, or the like. The circuit pattern printed layer 3 is formed by a method such as gravure printing, screen printing, offset printing, etc. using a water-soluble and adhesive printing paste that is mainly composed of a conductor, a resistor, or a dielectric. Printing pastes whose main components are conductors include silver, gold, platinum, palladium,
A material made by dispersing a metal such as copper or nickel and glass powder in an organic binder and a solvent is used.
Printing pastes containing resistors as main components include silver,
A material made by dispersing a metal such as palladium or ruthenium oxide and glass powder in an organic binder and a solvent is used. By using such a printing paste, its sheet resistance value will be 10Ω/□ to 10Ω/□ depending on the mixing ratio of the metal to the printing paste.
It can be arbitrarily selected within the range of 100MΩ/□. Furthermore, as the printing paste whose main component is a dielectric material, one which is made mainly of glass powder and dispersed in an organic binder and a solvent may be used. The binder must be water-soluble and adhesive. Examples of such materials include acrylic resins, vinyl acetate resins, etc.
There are various types of resin.

In addition, when the binder has elastomer properties, there is no risk that the binder will stretch like the elastomer film 2 and overlap the circuit pattern or break when pressed by the elastic body 7, which is more desirable. .

Next, a method for producing a printed circuit board using the transfer material 5 having the above structure will be described.

First, the base sheet 1 is peeled off from the transfer material 5. Peeling of the base sheet 1 may be performed during or after humidification of the transfer layer 4, but it is preferably performed before humidification because the transfer process must be performed quickly while the water-soluble adhesive is in an activated state. Immediately before transfer, a solvent is used to moisturize the water-soluble adhesive in order to activate it. Here, the solvent is used to swell the adhesive to some extent and make it adhesive, and since the adhesive used in the present invention is water-soluble, water, alcohol, etc. can be used. The humidification method is carried out by printing and applying a solvent to the circuit pattern printed layer 3 side of the transfer layer 4 by a gravure coating method, an offset method, a roll coating method, a bar coating method, a spray method, or the like. The amount of solvent used during humidification is adjusted to be sufficient to activate the adhesive. Further, care must be taken to ensure that the solvent does not have an adverse effect on the substrate, which is the object to be transferred.

The transfer layer 4 moistened by the above-mentioned method allows the circuit pattern printed layer 3 side of the transfer layer to lie along the surface of the printed circuit board base material 6 to a certain extent (see FIG. 2).
At this stage, the transfer layer 4 is placed on the surface of the printed circuit board base material 6 and is not in close contact with it. Thereafter, the circuit pattern is transferred by pressing with the elastic body 7 to completely adhere to the surface of the base material (third and fourth steps).
(see figure). As the material of the elastic body 7, for example, an elastic body such as silicone rubber is used.

Thereafter, the elastomer film 2 is peeled off and fired at a predetermined temperature to obtain a printed circuit board.

The base material 6 for the printed circuit board may be a ceramic base material such as alumina, a glass base material, a metal base material, or the like.

Since the present invention is a method of manufacturing a printed circuit board as described above, the following effects can be obtained. First, a conductor,
If a circuit pattern is formed on a transfer material using a printing paste whose main components are resistors and dielectrics,
They can be simultaneously transferred onto the substrate and easily transferred onto the substrate in a reliable and accurate position. Furthermore, since the transfer process is performed by humidifying the transfer material and pressing it once with an elastic body, the workability is good and the productivity is excellent. Another feature of the present invention is that the elastomer film used as the transfer material is stretchable, so even if it is applied to a three-dimensional printed board, especially a printed board with an uneven surface, the circuits will not overlap. There is no risk of the circuit breaking.

Therefore, the manufacturing method of the present invention is very useful for manufacturing printed circuit boards having complex and precise circuit patterns, especially three-dimensional printed circuit boards.

Examples of the present invention will be described below.

Example 1 On a non-stretchable silicone release paper, approximately
A thermoplastic polyurethane elastomer film with a thickness of 15 μm was formed, and a printed paste having the composition shown below was used as a conductor on the elastomer film, a printed paste having the composition shown below was used as a resistor, and a printed paste having the composition shown below was used as a dielectric material. Transfer materials were obtained by forming a printed layer with a predetermined circuit pattern by screen printing using printing pastes having the respective compositions.

(Parts by weight) Silver powder 60 parts Palladium powder 10 parts Lead borosilicate glass frit powder 10 parts Polyvinyl alcohol (Gohsenol, Nippon Gosei Kagaku Kogyo) 40 parts Solvent (water + isopropyl alcohol) 20 parts Ruthenium oxide powder 80 parts Lead borosilicate glass frit Powder 10 parts Polyvinyl alcohol (Gohsenol Nippon Gohsei) 45 parts Solvent (water + isopropyl alcohol) 20 parts Lead borosilicate glass frit powder 80 parts Polyvinyl alcohol (Gohsenol Nippon Gohsei) 40 parts Solvent (water + isopropyl alcohol) 20 Section Next, peel off the silicone release paper from the above transfer sheet, spray water on the circuit pattern printing layer,
After the circuit pattern printed layer is softened and activated, it is placed on the surface of the concave alumina substrate so that the surface of the circuit pattern printed layer is in contact with it, and then pressed from the elastomer film side with an elastic body made of silicone rubber to form a circuit. Transferred the pattern. When the elastomer film was then peeled off, a circuit pattern was obtained on the surface of the alumina substrate. When the thus obtained alumina substrate was fired at 850°C for 20 minutes, an electric circuit could be constructed on the concave alumina substrate surface.

[Brief explanation of the drawing]

FIG. 1 is an enlarged cross-sectional view of a transfer material used in the present invention, and FIGS. 2 to 4 are enlarged cross-sectional views of the transfer process in the present invention. In the figure, 1... Base sheet, 2... Elastomer film, 3... Circuit pattern printing layer, 4... Transfer layer, 5... Transfer material, 6... Base material for printed board, 7
...Elastic body.

Claims (1)

[Claims] 1. On a non-stretchable base sheet 1, an elastomer film 2 and a circuit pattern printed layer 3 composed of a water-soluble and adhesive printing paste mainly composed of a conductor, a resistor, or a dielectric. The base sheet 1 is peeled off from the transfer material 5 formed by laminating the transfer layer 4, the transfer layer 4 is humidified, and then the circuit pattern printed layer 3 is placed in contact with the surface of the printed circuit board base material 6, After that, the elastic body 7 is pressed from the elastomer film 2 side of the transfer layer 4, and the printing board base material 6 and the transfer layer 4 are pressed together.
A method for manufacturing a printed circuit board, which comprises: forming a circuit pattern on the surface of the printed circuit board base material 6 by pressing the two together, then peeling off the elastomer film 2, and then baking it.