JPS6269519A - Irradiation method for ultraviolet ray laser - Google Patents

Abstract

PURPOSE:To achieve uniform irradiation on an object plane and obtain an excellent picture image, by combining a rectangular plane reflection mirror and a rotating reflection mirror of polyhedron, and applying ultraviolet ray laser of parallel light. CONSTITUTION:Ultraviolet ray C from a ultraviolet ray layer 1 reflected horizontally by a rotating reflection mirror 2 of polyhedron, and irradiates a rectangular plane reflection mirror 3. On that occasion, ultraviolet ray C is deflected in the right and left directions by the rotating reflection mirror 2, and irradiates the A-A' plane of the plane reflection mirror 3 with a band whose width corresponds nearly with the spot diameter of ultraviolet ray C. The direction said ultraviolet ray is changed 90 deg. by the plane reflection mirror 3 being inclined to the angle of 45 deg., and then reflected downward in the vertical direction to irradiate a mask 4 being a surface to be irradiated. The band-like ultraviolet ray can be transferred on the surface of the mask 4 by making the plane reflection mirror 3 transfer in the direction from B to B'. A circuit pattern formed on then mask 4 can be printed on a printed circuit board 5, thereby.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention applies ultraviolet rays to an ultraviolet curing resist coated onto a printed circuit board or the like through a circuit pattern mask formed on a translucent film or the like. This relates to the ultraviolet laser irradiation method of exposure equipment and is used in fields where it is necessary to form fine images.

Furthermore, the irradiation method of the present invention can also be used in the printing of ultraviolet curing type mfil or printing ink.

BACKGROUND OF THE INVENTION In circuit board manufacturing and the like, there is a trend toward miniaturization of circuit patterns, and it is necessary to improve the resolution of exposure equipment. In order to expose and print a fine circuit pattern formed on a mask onto a printed circuit board coated with an ultraviolet curing resist, such as a soldering resist or solder resist, parallel light is required from the viewpoint of resolution. Conventionally, a lighting A4 method has been proposed in which parallel light is created by combining an ultra-high pressure discharge lamp, which is close to a point light source, and an optical system.

FIG. 2 shows an example of a conventional irradiation method of this type of exposure apparatus. In the figure, 6 is an ultra-high-pressure discharge lamp such as an ultra-high-pressure mercury lamp, 7 is an ellipsoidal mirror, 8 is a primary reflecting mirror, 9 is an inch grater, and 10 is a second-stage copper mirror, IN, on which a circuit pattern is formed. The mask 12 is a printed circuit board on which the resists 1 to 1 are coated. The ultraviolet light from the ultra-high pressure discharge lamp 6 is focused on the primary reflecting mirror 8 via the ellipsoidal mirror 7, and the light is reflected by changing the direction approximately 90 degrees, and is composed of a plurality of small lenses. The light passes through the inch grater 9 and is irradiated onto the secondary reflecting mirror 10. The secondary reflecting mirror 10 is installed with an inclination of approximately 45 degrees with respect to the printer 1 and the substrate 12, and the secondary reflecting mirror 10 is installed at an angle of approximately 45 degrees with respect to the printer 1 and the substrate 12. ) The light reflected by the J mirror 10 is irradiated onto the printed circuit board 12 through the mask 11, and the circuit pattern of the mask 11 is printed onto the lens coated on the printed circuit board 12.

A cold mirror is used as the primary reflecting mirror 8 in order to transmit the heat rays from the ultra-high pressure electric lamp 6. The inch grater 9 is constructed by combining small convex lenses made of quartz in order to improve the transmittance of ultraviolet light.

Problems to be Solved by the Invention Since the exposure time for printing an irradiated object such as a printed circuit board is determined by the minimum value of the ultraviolet intensity of the irradiated object,
It is necessary to uniformly irradiate at a value as high as possible.

However, in the conventional method described above, the degree of uniformity is improved by devising a part of the inch grater and the reflector at the final stage of R, but since the ultraviolet light that exits the part of the inch grater is spread out, The distribution of ultraviolet light intensity is higher at the center than at the edges.To improve the uniformity, the optical path length may be lengthened, or the irradiation area may be increased relative to the size of the object to be irradiated. However, in both cases, the intensity of ultraviolet rays decreased and the exposure time (printing time) became longer.Furthermore, in order to improve resolution, parallelism was improved.
．． > LJ would be fine, but there are ways to do this, such as changing the final stage reflecting mirror from a plane mirror to a parabolic mirror.
If the parabolic mirror (tJ:) is insufficient, the parallelism will deteriorate in some areas, which will affect the quality of products such as printed circuit boards.
The problem arises that Furthermore, if the mirror surface is finished to a high quality, there will be problems such as an extremely high price.

The present invention provides a method of irradiating ultraviolet light to an exposure apparatus, etc., which solves the problems described in (1) and (1) above.

A means to solve the problem, that is, the present invention, uses a parallel ultraviolet laser as a light source, improves resolution for miniaturization, and illuminates a wide irradiated surface without moving the irradiated object. In order to uniformly irradiate the ultraviolet light from the ultraviolet laser, two types of reflecting mirrors, a rectangular plane reflecting mirror and a polyhedral rotating reflecting mirror, are combined, and these two reflecting mirrors are arranged facing each other. By moving the flat reflecting mirror back and forth at right angles to the rotating reflecting mirror, the object to be irradiated can be uniformly irradiated with ultraviolet light from the ultraviolet laser.

A polyhedral rotating reflector installed on the surface of the object to be irradiated, such as a printed circuit board, receives ultraviolet light from an ultraviolet laser and directs the ultraviolet light to a rectangular plane placed opposite the rotating reflector. Reflect it towards the reflector. In this way, the entire surface of the flat reflecting mirror is irradiated with the ultraviolet light scattered left and right by the rotating reflecting mirror in a band shape with a width of 16, which corresponds to the spot diameter of the ultraviolet laser. Furthermore, a flat reflecting mirror is placed on the surface of the irradiated object at an angle of about 45 degrees with respect to the irradiated object, and rotated in the opposite direction! Avoid moving back and forth on the surface of the irradiated object at right angles to the iJ4 mirror. In this way, the ultraviolet light irradiated onto the flat reflecting mirror in a band-like manner is reflected downward by the flat reflecting mirror and is irradiated onto the surface of the irradiated object in a band-like manner, and Since the ultraviolet light moves over the irradiated surface as the mirror moves, the entire surface of the fixed object can be uniformly irradiated with highly parallel ultraviolet light from the ultraviolet laser. .

Example An embodiment of the present invention will be described below with reference to FIG.

In the figure, 1 is an ultraviolet laser, 2 is a rotating inverse IJ1iff of a polyhedron that reflects the incident light C from the ultraviolet laser 1 in the front direction while swinging it from side to side, and 3 is the width formed by the rotating reflector 2 of the ultraviolet laser. A rectangular plane reflecting mirror reflects a band of ultraviolet light approximately equivalent to the spot diameter vertically downward by approximately 90 degrees, 4 is a mask with a circuit pattern for a printed circuit board, and 5 is a printed circuit board coated with resist. Further, the polyhedral rotary reflecting mirror 2 and the rectangular plane reflecting mirror 3 are arranged opposite to the mask 40, and the plane reflecting mirror 3 is inclined at an angle of 45 degrees C with respect to the mask 4, and B in a perpendicular relationship with the rotating reflector 2
It is designed to move back and forth in the -8' direction.

In this embodiment of the present invention, the ultraviolet light C emitted from the ultraviolet laser 1 is reflected in the horizontal direction by a polyhedral rotating reflector 2, and is then illuminated by a rectangular plane reflector 3. At this time, the ultraviolet light C is swung left and right by the polyhedral rotating reflecting mirror 2, and is irradiated onto the surface of the plane reflection 813 in the form of a band with a width approximately corresponding to the spot diameter of the ultraviolet light C. The band-shaped ultraviolet light irradiated onto the flat reflecting mirror 3 is reflected by the flat reflecting mirror 3 tilted at 45 degrees at 90r! The direction of the light is changed, the light is reflected vertically downward, and the light is irradiated onto the mask 4, which is the surface to be irradiated. Further, by moving the flat reflecting mirror 3 in the force direction from B to B', it is possible to move the band-shaped ultraviolet light onto the face of the mask 4, thereby transferring the circuit pattern formed on the mask 4 to the printed circuit board 1 to the substrate 5. It can be burned into.

Further, the rotational position Ij1 of the roof 2 and the raising of the mirror surface t1 of the I-plane reflecting mirror 3 can be efficiently reflected by using a beam that matches the wavelength of ultraviolet rays. Further, in order to greatly reduce the intensity of ultraviolet rays and light beams, the moving speed of the plane reflecting mirror 3 is reduced, or the plane reflecting mirror 3 is moved repeatedly between n-8'. In addition, whether the mask 4 and the resist-coated prints 1 to 5 are in close contact or not, the ultraviolet laser can perform high-power printing using high-quality parallel light. Further, by placing a device having the same configuration at −V below the printed circuit board 5, double-sided exposure can be performed.

The method of the present invention can be applied to fine image formation on printed boards, screen printing boards, etching, etc., and can also be used for printing paints, inks, etc. by irradiating the entire surface.

Effects of the Invention As mentioned above, by using the ultraviolet laser irradiation method according to the present invention, the parallel rays that are a characteristic of ultraviolet lasers can be used as they are, and the degree of parallelism is 4.
The resolution has been improved, making it easier to manufacture printed circuit boards with minute circuits, etc., making it possible to form uniform images on the irradiated surface, and forming high-quality images. As a result, the printing speed can be increased and the exposure time can be shortened, which has great practical effects.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a three-dimensional view showing an embodiment of the ultraviolet laser irradiation method of the present invention, and FIG. 2 is a sectional view showing an example of a conventional irradiation method. 1... Ultraviolet laser, 2... Polyhedral rotating reflector, 3... Rectangular plane reflector, 4... Mask, 5...
··Printed board

Claims (1)

[Claims] In an ultraviolet laser irradiation method in an exposure device or the like that irradiates ultraviolet rays from an ultraviolet laser, a rectangular plane reflecting mirror and a polyhedral rotating reflecting mirror are arranged facing each other, and the rectangular plane reflecting mirror is opposed to the rotating reflecting mirror. An ultraviolet laser irradiation method that irradiates the object uniformly by moving it back and forth at right angles, without moving the object.