JPH04174591A - Printed wiring board and its manufacture - Google Patents

Abstract

PURPOSE:To print small-sized characters and symbols so that a larger amount of information can be printed on a printed wiring board by printing a pattern containing the characters and symbols on the surface of a solder resist by a dye burying method. CONSTITUTION:After printed conductors 3 are formed on a substrate 2, solder resist 4 is formed and left unbaked. Then characters or parts marks to be printed on a printed wiring board 1 are printed on a sheet of paper 5 with dye powder 6 and the paper 5 is thermally press-fixed to the substrate 2, so as to bury the dye powder 6 in the resist 4. After burying the dye powder 6, the substrate 2 is heated and the resist 4 is baked. Therefore, the amount of the information described on the printed wiring board 1 is increased, since small characters and symbols of 1mm can be printed on the board 1.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a printed wiring board, and particularly to a printed wiring board on which characters and symbols are printed.

[Conventional technology]

Conventionally, printed wiring boards have had a printing body formed thereon, covered with a solder resist, and characters and symbols printed thereon.

In particular, as a method for printing characters and symbols, a method of screen printing thermosetting ink and then heating and drying it to print it has been widely used. The reason for screen printing is that printed wiring boards have irregularities of approximately 100 micrometers in the printed conductor and solder resist, and this printing method is not affected by this.

Recently, methods have been developed in which a latent image is formed by applying photosensitive ink, applying a patterned mask to it, and exposing it to light, which is then developed to form a character symbol pattern and printed.

[The problem that the invention attempts to solve]

However, in the screen printing method, ink is printed at a thickness of several tens of microns, but the ink tends to become round due to surface tension. Therefore, printing fine characters and symbols with dimensions of 2 mm or less is difficult because the line width is 100 microns or less, which is affected by surface tension. For this reason, printed wiring boards have a drawback in that it is difficult to write a lot of information such as detailed specifications of components or cautionary notes.

In addition, in the method of transferring a mask pattern to photosensitive ink, the fineness of printed characters and symbols is determined by the thickness of the ink applied. It is difficult to print ink thinly and uniformly, and if it is applied thickly, it becomes difficult to print fine letters and symbols with dimensions of 2 mm2 or less.

An object of the present invention is to provide a printed wiring board on which fine-sized characters and symbols can be printed and on which a large amount of information can be written, and a method for manufacturing the same.

[Means to solve the problem]

The printed wiring board of the present invention is characterized in that a pattern including characters and symbols is embedded and printed with dye on the surface of the solder resist.

The method for producing a printed wiring board of the present invention includes closely adhering a thin film to which pigment powder is attached to a solder resist on a base material, and printing a pattern including characters and symbols by heat-pressing the pigment powder onto the solder resist. It has a process.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

Section 1 (a) to (e) are sectional views shown in order of steps to explain the manufacturing method of the first embodiment of the present invention.

In the first embodiment, first, a printed conductor 3 is formed on a base material 2, as shown in FIG. 1(a).

Next, as shown in FIG. 1(b), a solder resist 4 is formed on the base material 2 without being baked.

Next, as shown in FIG. 1(c), characters or part marks to be printed on the printed wiring board are formed by printing pigment powder 6 on paper 5. The method of printing the pigment powder 6 on the paper 5 is, for example,
Conventional techniques are used, such as transferring the image on the original film to a photosensitive medium as an electrostatic image, adsorbing toner containing pigment powder 6 wrapped in resin on the photosensitive medium, transferring the toner to paper 5, and fixing it by heating. .

Next, as shown in FIG. 1(d), the paper on which the pigment powder 6 has been printed is brought into close contact with the base material 2 and heat-pressed, thereby embedding the pigment powder 6 into the solder resist 4.

Next, as shown in FIG. 1(e), the base material 2 is heated at over 100 degrees Celsius for several tens of minutes to bake the solder resist 4.

Here, instead of the paper 5, a film made of silicone resin or the like may be used.

The transfer accuracy of these characters and symbols depends on the roughness of the pigment powder 6, but characters and symbols with a width of several tens of microns and a width of 1 square millimeter or less can be printed.

FIGS. 2(a) to 2(f) are cross-sectional views showing the manufacturing method of the second embodiment of the present invention in the order of steps.

In the second embodiment, first, as shown in Section 2 (a), a printed conductor 3 is formed on a base material 2.

Next, as shown in 2nd IN(b), the entire surface of the base material 2 is coated with a photosensitive solder resist 7, and a solder resist pattern is exposed to form a latent image, which is not developed.

Next, as shown in FIG. 2(c), the first
Characters or part marks are formed on paper 5 using pigment powder 6 in the same manner as in the embodiment.

Next, as shown in FIG. 2(d), the paper 5 printed with the pigment powder 6 is closely attached to the base material 2.

Next, as shown in FIG. 2(e), the paper 5 is heated and pressed onto the base material 2, and the pigment powder 6 is transferred to the photosensitive sorter resist.

Next, as shown in FIG. 2(f), the photosensitive Sorter resist is developed and baked.

In this embodiment, since the pigment powder 6 on the parts other than the photosensitive tsuruta resist 7 is removed when the photosensitive solder resist is formed by development, there is an advantage that the surface of the printed conductor 3 is not contaminated. Since the surface of the photosensitive solder resist 7 has not yet been developed, it has the advantage of having fewer irregularities and allowing for highly accurate printing.6 [Effects of the Invention] As explained above, the present invention has the advantage of transferring pigment powder to the solder resist. By doing so, it is possible to print fine characters and symbols of 1 millimeter or less, which has the advantage of increasing the amount of information written on the printed wiring board.

FIG. 3 is a cross-sectional view showing the process order for explaining the method.

DESCRIPTION OF SYMBOLS 1... Printed wiring board, 2... Base material, 3... Printed conductor, 4... Solder resist, 5... Paper, 6... Pigment particles, 7... Photosensitive solder resist .

Claims (2)

[Claims] 1. A printed wiring board characterized by printing a pattern containing characters and symbols on the surface of a solder resist by embedding it with dye. 2. A printed wiring board characterized by comprising the steps of: adhering a thin film to which pigment powder is attached to a solder resist on a base material; and printing a pattern including characters and symbols by heat-pressing the pigment powder to the solder resist. manufacturing method.