JPH02132881A - Manufacture of circuit board - Google Patents

Abstract

PURPOSE:To manufacture a circuit board in a simple method and improve it in quality by a method wherein photosetting resin liquid thin layers, which ar used for the formation of an insulator and a conductor respectively, are irradiated with ultraviolet rays in required patterns to form an insulating pattern and a conductor pattern, and these layers are laminated. CONSTITUTION:A board 22 is horizontally immersed into a photosetting resin liquid 21 to form a thin film 21s of the liquid 21 on the board 22, and the film 21s is selectively irradiated with ultraviolet rays by an ultraviolet laser 23 to enable a required part of the film 21s to set for the formation of a hardened resin layer 24. Moreover, the board 22 is slightly immersed to form the layer 24 through the same process as above. The resin liquids 21 to form an insulator and a conductor respectively are provided, and the layers 24 are formed using these liquids alternately through a process as mentioned above, whereby a circuit board of stable quality, which is composed of an insulating board part and a circuit conductor part formed in one piece, can be easily manufactured.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing a circuit board, and particularly to a method suitable for manufacturing a multilayer circuit board.

[Conventional technology and its issues]

Figure 5 shows a conventional circuit board. This circuit board has four layers of conductor patterns lla to lid, and the conductor patterns lla and llb of the IN and second layers are through holes 1
2a, conduction is established between the conductor patterns IIC and lid of the third and fourth layers through the through hole 12b, and conduction is established between the conductor patterns 118 to lid of each layer through the through hole 12c. It is.

To manufacture such a circuit board, conductive patterns lla are formed on both sides of the insulating substrate 13a by etching W4 foil or the like.
After forming the through holes 12a and manufacturing the first circuit board 114a, the insulating substrate 13b is formed in the same manner.
A conductor pattern IIc is formed on both sides of the
After forming a through hole 12b and manufacturing a second circuit board 14b, these circuit boards 14a and 14b are bonded together via an adhesive layer 15, and a through hole 12c is further formed. Finally, a method is used in which solder resist layers 16a and 16b are printed on both sides.

However, this method has extremely low productivity, as it requires a large number of complex processes such as pattern etching, through-hole drilling, internal plating, lamination adhesion, and solder resist printing. There is also the problem that variations in quality tend to occur.

It is also known to manufacture multilayer circuit boards by alternately repeating the process of printing an insulating paste and heating and curing it, and the process of printing and heating and curing a conductor paste. It is difficult to accurately control the layer thickness due to sagging of the insulating paste or conductive paste, resulting in problems such as poor interlayer insulation, and as the number of layers increases, the surface becomes uneven and printing becomes impossible. ．． [Means for Solving the Problems and Their Effects] In order to solve the above-mentioned problems, the present invention provides a method for manufacturing a circuit board using a completely new method. A thin layer of photocurable resin liquid is irradiated with ultraviolet rays in a desired pattern, and only the irradiated areas are cured to form an insulation pattern. This process is repeated alternately by irradiating in a pattern and curing only the irradiated part to form a conductive pattern.
This method is characterized by laminating insulating patterns and conductive patterns to obtain a circuit board. The principle of this method will be explained with reference to FIG.

First, as shown in lal, a flat substrate 22 is horizontally submerged in a photocurable resin liquid 21, and a thin N21S of the photocurable resin liquid 21 is formed on the substrate 22. Next, as shown in Fig. 2, the thin layer 21s is selectively irradiated with ultraviolet light by an ultraviolet laser 23 to selectively harden only the necessary portions of the thin layer 21S. This ultraviolet irradiation is performed by laser 2
3 is moved in the X-Y direction to scan the thin layer 21S, and when the laser 23 passes through the part of the thin layer 21s that is to be cured, it emits ultraviolet rays, and when it passes through the part that is not to be cured, it emits ultraviolet rays. This can be done by stopping.

After the above curing process is completed, the substrate 22 is slightly submerged as shown in (Cl), and a photocurable resin liquid TtJ Fl2 1s is further formed on the cured resin layer 24.
As shown in dl, the ultraviolet laser 2 is applied to the thin layer 213.
3, the thin Ji21
3. Selectively harden only the necessary parts.

By repeating such operations, cured resin layers 24 each having a different planar pattern are laminated, and an integrated resin molded body can be obtained. At that time, a photocurable resin liquid for forming an insulator and a photocurable resin liquid for forming a conductor are prepared, and the former resin liquid forms an insulating cured resin layer, and the latter resin liquid forms a conductive resin layer. By alternately forming the hardening resin layer, it is possible to manufacture a circuit board in which the insulating substrate portion and the circuit conductor portion are integrated. In addition, as the photocurable resin, photocurable epoxy resin,
Photocurable polyimide, photocurable polyurethane acrylate, photocurable silicone resin, etc. can be used. In order to make these resins conductive, conductive powder may be mixed into these resins. It is also possible to use photocurable resins whose resin itself is electrically conductive. [Example] Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

Figure 1 shows an embodiment of the manufacturing method of the present invention, and Figure 2 shows a circuit board obtained by the method. First, Figure 1 (a
), the substrate 22 is submerged in a photocurable resin liquid for forming an insulator, a thin FJ31 of the same resin liquid is formed on it, and the thin JIF31 is selectively cured by irradiation with ultraviolet rays. The insulation pattern 32 is formed as shown in the same figure (bl).This forms the insulation pattern 32 of the first layer in Figure 2.
is formed.

Next, submerge the substrate 22 slightly, and apply a thin N3 layer of the same photocurable resin liquid as above on the insulating pattern 32 as shown in Figure 1 (Cl).
1 is formed, and the thin layer 31 is selectively cured by irradiation with ultraviolet rays to form an insulating pattern 32 as shown in the figure (dl). As a result, the 2Nth insulating pattern 32 in Fig. 2 is formed. Next, the whole was taken out of the photocurable resin liquid, the uncured resin liquid was removed by washing, and then it was immersed in a photocurable resin liquid for forming a conductor, as shown in Figure 2(e). As shown, a thin layer 33 of the same resin liquid is applied so that the surface is aligned with the insulating pattern 32.
The thin N33 is cured by irradiation with ultraviolet rays to form a conductor pattern 34 as shown in the same figure (fl).Thus, the second layer conductor pattern 34 shown in Figure 2 is formed.Next, The substrate 22 is slightly submerged, and a thin layer 33 of the same photocurable resin liquid as above is formed on the insulating pattern 32 and the conductive pattern 34 as shown in Figure N&, and the thin layer 33 is selectively irradiated with ultraviolet rays. After curing, a conductive pattern 34 is formed as shown in the same figure (hl).
A third layer of conductor pattern 34 is formed. Similarly, the insulation pattern of the third layer and the fourth layer of FIG.
Nth insulation pattern, fourth layer conductor pattern, fifth layer conductor pattern, 5Nth insulation pattern, etc.
By forming these in sequence, a circuit board as shown in Figure 2 can be obtained. Note that the ultraviolet irradiation pattern for each layer can be easily produced by, for example, designing a model of the circuit board using three-dimensional CAD and slicing the model into the required number of layers. Although the above embodiment is a case of manufacturing a flat circuit board, according to the method of the present invention, it is also possible to manufacture a three-dimensional circuit board as shown in FIG. In Figure 3, the same parts as in Figure 2 are given the same symbols. [Effects of the Invention] As explained above, according to the present invention, a multilayer circuit board can be easily manufactured by repeating extremely simple steps, and the quality of the circuit board is therefore stable.

[Brief explanation of the drawing]

Figures 1 (a) to (hl are cross-sectional views showing the method for manufacturing a circuit board according to an embodiment of the present invention in the order of steps, Figure 2 is a cross-sectional view of a circuit board manufactured by the method, and Figure 3 is a cross-sectional view of the circuit board manufactured by this method. A sectional view showing another example of a circuit board obtained by the method of the invention,
Figures 4 (a) to (d+ are cross-sectional views showing the principle of the method of the present invention in the order of steps, and Figure 5 is a cross-sectional view of a circuit board manufactured by a conventional method. 31: Photocuring for forming an insulator 32: Insulating pattern, 33: Thin layer of photocurable resin liquid for conductor formation, 34: Conductor pattern. Fig. 1 Fig. 3 Fig. 5 Fig. 4

Claims (1)

[Claims] 1. A thin layer of photocurable resin liquid for forming an insulator is irradiated with ultraviolet rays in a desired pattern, and only the irradiated area is cured to form an insulation pattern, and a photocurable resin liquid for forming a conductor is used. A thin layer of ultraviolet rays is irradiated in a desired pattern to form a conductor pattern by curing only the irradiated area, and this process is repeated alternately to form a conductor pattern, thereby laminating an insulating pattern and a conductor pattern to obtain a circuit board. A method for manufacturing a circuit board, characterized by: