JP2004037940A - Method for aligning photomask, exposing device and method for manufacturing printed wiring board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for aligning photomasks capable of inexpensively aligning two upper and lower photomasks with a high degree of accuracy. <P>SOLUTION: Two or more holes are pierced in each of the two photomasks, tapered pins machined to an outside diameter equal to the hole diameter are inserted in the holes in one of the photomasks, female pins each having an internal tapered pocket are inserted in the holes in the other, and the male pins are fitted in the female pins. <P>COPYRIGHT: (C)2004,JPO

Description

【００１８】
【発明の効果】
以上に説明したとおり、本発明によって、安価で上下２枚のフォトマスクを高精度に位置合せすることが可能な露光装置とその装置を用いたプリント配線板の製造方法を提供することができる。
また、本発明によると、高価なＣＣＤカメラを用いずに高精度の位置合せをすることが可能となるため、安価な露光装置を提供することができる。
【図面の簡単な説明】
【図１】本発明の上下フォトマスク穴あけ位置の一例を示す。
【図２】本発明のオスピン、メスピンの正面及び上視の一例を示す。
【図３】本発明の上下フォトマスク位置合せ状態の一例を示す断面図である。
【図４】本発明のオスピン、メスピンを用いた焼枠へのフォトマスク取付け方法の一例を示す断面図である。
【図５】本発明の上下焼枠の上視および断面図の一例である。
【図６】比較例で用いたストレートタイプのオスピン、メスピンの正面及び上視図である。
【符号の説明】
１０　上フォトマスク
１１、２１　パターン
１２　メスピン挿入穴
２０　下フォトマスク
２２　オスピン挿入穴
３０　オスピン
４０　メスピン
５０　上枠
６０　下枠
７０　カプセル
９０　バネ座金
１００　スプリング
１１０　メスピン固定用円盤
１２０　メスピン固定用円盤取付穴[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a photomask alignment method, a photomask exposure apparatus, and a method for manufacturing a printed wiring board.
[0002]
[Prior art]
Conventionally, the pattern formation of a printed wiring board is performed by attaching a photomask to a copper-clad laminate laminated with a dry film using a straight type male pin, aligning the pins with the pins, and applying a photomask to the copper-clad laminate. After the mask was brought into close contact with the vacuum, ultraviolet light was irradiated to form a pattern having the same shape as the photomask on the dry film. However, as the area of the grill increases, the amount of deformation such as warping of the grill member increases, so when using a straight type pin, it is more difficult to insert and remove the male pin unless the clearance of the male pin is increased. there were. Therefore, for example, it was necessary to make the cavity diameter of the mespin about 0.1 mm larger than the diameter of the male pin. Therefore, it is difficult to accurately align the two upper and lower photomasks only by using the straight type pins.
[0003]
Therefore, in addition to using the straight type pins, two or more alignment marks are provided on each of the two upper and lower photomasks, and the displacement of the two upper and lower photomasks is measured with a CCD camera, and the servomotor and the servomotor are used. A printed wiring board with high interlayer positional accuracy has been manufactured using an exposure apparatus that moves the printing frame in the X, Y, and θ directions using a ball screw and minimizes the displacement between the upper and lower photomasks. .
[0004]
[Problems to be solved by the invention]
However, in the above-described exposure apparatus that drives a printing frame by using a CCD camera, only one photomask can be aligned for each printing frame, and circuit forming of a large substrate that forms a multi-sided pattern can be performed. Couldn't. Further, an apparatus capable of forming a multi-sided pattern is expensive (JP-A-2000-066418).
[0005]
An object of the present invention is to provide a method for aligning a plurality of sets of photomasks with high accuracy at low cost, an exposure apparatus using the method, and a method for manufacturing a printed wiring board using the apparatus. Aim.
[0006]
[Means for Solving the Problems]
In the method for aligning a photomask of the present invention, two or more holes are formed in each of two upper and lower photomasks, and the holes formed in the first photomask have the same outer diameter as the hole diameter. Insert a tapered male pin in the part, insert a female pin having the same outer diameter as the hole diameter and a tapered cavity inside the hole drilled in the second photomask, and a female pin and male pin Is fitted.
[0007]
When fitting the male pin or the female pin, the male pin or the female pin may be weighted.
[0008]
Further, the exposure apparatus for a printed wiring board according to the present invention may further comprise an upper photomask having a tapered male pin, a female pin having a tapered cavity therein and fitted with the male pin, and a plurality of capsules for accommodating the female pin. And a grilling frame for attaching a lower photomask (hereinafter, referred to as a lower frame).
Further, the photomask exposure method of the present invention, the photomask is attached to the upper frame and the lower frame, respectively, the photocurable film is formed on both sides of the substrate, and fixed between the upper frame and the lower frame, A method of irradiating an exposure light beam from above and below, using a male pin having a tapered male pin and a tapered cavity when attaching the photomask, and using the male pin and the female pin of the above-mentioned photomask when fixing the photomask. Are positioned by fitting them.
[0009]
Further, the method for manufacturing a printed wiring board of the present invention may use such an exposure apparatus for printed wiring boards.
Further, the photomask alignment method of the present invention using a tapered male pin and a tapered female pin may be applied to other devices, for example, a mounting device (thermocompression device) and a laminating device.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
(Photomask alignment method)
In the method of aligning two upper and lower photomasks according to the present invention, two or more holes are formed in each photomask, and the holes formed in the first photomask have the same outer diameter as the hole diameter. Insert a tapered male pin that has a part, insert a female pin having the same outer diameter as the hole diameter and a tapered cavity inside the hole drilled in the second photomask, and Is fitted.
The photomask alignment method of the present invention will be described below with reference to the drawings. FIG. 1A shows a specific example of the upper photomask 10 and FIG. 1B shows a specific example of the lower photomask 20. These photomasks have patterns 11 and 21 in the center, and have pin insertion holes, that is, female pin insertion holes 12 or male pin insertion holes 22. The diameter of these holes is the same as the diameter of the male pin to be inserted and the same as the outer diameter of the female pin. Here, the same or the same diameter means substantially the same diameter, and includes a case where the hole diameter is slightly larger than the pin diameter so that accurate positioning can be performed.
The number of holes per photomask may be at least two or more, but it is preferable to provide three or more holes in order to increase reliability. There is no problem if the hole position is a position other than the pattern drawn on the upper and lower photomasks, but it is preferable to arrange the hole positions at the corners of the photomask.
FIG. 2A shows an example of the male pin 30 used in the present invention, and FIG.
The male pin 30 shown in FIG. 2A has a photomask mounting portion 31 for insertion into the male pin insertion hole 22 (FIG. 1), and the upper portion thereof prevents the photomask from coming off upward. And a conical male pin portion 33 on the upper portion thereof. The male pin 30 preferably does not have to include a seat 32, but may. Although not shown, a means for fixing the male pin 30 to the lower frame may be provided below the photomask attaching portion 31. The male pin used in the present invention is a tapered male pin, and the “tapered male pin” refers to an male pin having an male pin portion whose cross-sectional area decreases as the distance from the bottom surface increases. Such male pin portions include, for example, cones, truncated cones, polygonal pyramids, hemispheres, parts of spheres, and cones and polygonal pyramids with rounded tips. The male pin portion preferably has a conical shape as shown in FIG. When the male pin portion has a conical shape, a straight line connecting the center point and the vertex of the bottom of the cone and a straight line connecting the points and vertices on the bottom circumference of the cone when the cone is cut along a plane including the central axis of the cone. The angle formed by the above, the optimal value is determined in advance by experiment in consideration of the required alignment accuracy and the size of the laminated plate, preferably 10 to 60 °, more preferably 10 to 45 ° And more preferably 10 to 30 °. The outer diameter of the bottom surface of the male pin is determined in the same manner as above, but is preferably 3 to 50 mm, more preferably 5 to 30 mm, and still more preferably 5 to 20 mm.
The female pin 40 shown in FIG. 2B has a columnar portion 44 for insertion into the insertion hole of the photomask, and a seat 41 therebelow for preventing the photomask from falling down. The inside of the female pin has a female pin portion 43 which is a tapered cavity. The mespin used in the present invention is a mespin having a mespin portion 43 which is a tapered cavity therein, and a “tapered cavity” is a cavity in which the cross-sectional area of the cavity becomes smaller as it enters the cavity from the entrance of the cavity. In addition, it refers to the shape in close contact with the above-mentioned male pin. The shape of the female pin is preferably conical.
FIG. 3 shows a specific example of the alignment of the upper and lower photomasks. First, the female pin 40 is inserted into the upper photomask 10, and the male pin 30 is inserted into the lower photomask 20. Next, by fitting the female pin 40 inserted into the upper photomask 10 with the male pin 30 inserted into the lower photomask 20, the positioning between the photomasks can be performed with high precision.
At this time, if the positions of the tops of all the male pins inserted in the lower photomask are within a circle formed by projecting the shape of the bottom outer shape of the mespin in parallel from the upper part of the lower photomask onto the lower photomask surface, alignment is performed. The weighting causes a so-called self-alignment function in which the top of the male pin travels along the side surface inside the cavity of the mespin and reaches the top of the female pin. Therefore, high-accuracy alignment can be performed without requiring accurate alignment using a CCD camera, which has been conventionally performed in a subsequent step.
[0011]
In order to fit the male pin 30 and the female pin 40, the male pin 30 or the female pin 40 may be weighted. The weight may be applied by, for example, pressing the pin from above or below with a spring or an air cylinder.
[0012]
(Exposure equipment for printed wiring boards)
4A and 4B show an example of a printed wiring board exposure apparatus of the present invention. This apparatus is an exposure apparatus that irradiates, via a photomask, exposure light beams from above and below to photocurable films formed on both surfaces of a substrate. FIG. 4 shows an example in which an upper photomask 10 and a lower photomask 20 are mounted on an exposure apparatus. This exposure apparatus includes a female pin 40, a capsule 70 for storing the female pin, an upper frame 50 to which the capsule 70 is attached, an male pin 30 fitted to the female pin 40, and a lower frame 60. The capsule 70 includes a spring 100 for pressing the female pin from above, a spring washer 90 located between the spring and the female pin for transmitting the pressure of the spring to the female pin, and a female pin for fixing and stabilizing the female pin inside the capsule. A fixing disk 110 and a female pin fixing disk mounting hole 120 for mounting the female pin fixing disk in the capsule with screws are provided. As such an apparatus, a commercially available exposure apparatus for printed wiring boards may be used. For example, an ultraviolet ray is used as the exposure light beam, and a mercury lamp can be used as the light emission source.
FIGS. 5A and 5B show an upper frame 50 and a lower frame 60 of the present invention. A plurality of capsules 70 for storing female pins are attached to the upper frame 50. The number and position of the capsules attached to the upper frame are determined in consideration of the number, position and shape of the pin insertion holes formed in the photomask, the number of photomasks to be aligned, and the number of laminates to be patterned. . The lower frame 60 may be provided with a bank rubber 61 along the periphery of the lower frame so as to be in vacuum contact with the upper frame 50, and a suction port for vacuum adhesion is provided inside the bank rubber at four corners of the lower frame. May be provided.
By using the photomask alignment method of the present invention and the exposure apparatus of the present invention, a printed wiring board with high interlayer positional accuracy can be manufactured.
[0013]
(Method of manufacturing printed wiring boards)
Among the base materials used in the method for manufacturing a printed wiring board of the present invention, commercially available double-sided copper-clad laminates having copper foils bonded to both surfaces thereof can be used. Examples of commercially available copper-clad laminates include MCL-E-67 (trade name, manufactured by Hitachi Chemical Co., Ltd.) and MCL-E-679 (trade name, manufactured by Hitachi Chemical Co., Ltd.).
As a photocurable film formed on the surface, a thermosetting resin such as an epoxy resin and a photocuring agent, a curing accelerator, and if necessary, a pigment, a fluidity adjusting agent, a viscosity adjusting agent, etc. A varnish that has been mixed and dispersed can be directly applied to the surface of a substrate and dried to form a varnish. Alternatively, the varnish may be applied to a carrier film and dried, and a semi-cured dry film may be laminated on a substrate to be used as a photocurable film.
As such a varnish-like etching resist material, a commercially available one may be used. As a commercially available varnish-like etching resist material, for example, Opto ERN-350 (trade name, manufactured by Nippon Paint Co., Ltd.) can be mentioned. A commercially available dry film-shaped etching resist material may be used. As a commercially available dry film-shaped etching resist material, for example, PHOTEC H-930 (trade name, manufactured by Hitachi Chemical Co., Ltd.) can be mentioned.
After forming the etching resist, an etching solution is used to remove the etching of the uncured portion of the etching resist. Examples of the etchant include a ferric chloride solution and a cupric chloride solution. By spraying and spraying these etching liquids, the uncured portions of the etching resist can be removed by corrosion to obtain printed wiring boards.
[0014]
【Example】
As the upper photomask 10 and the lower photomask 20, of the shape shown in FIG. 1, holes having an inner diameter of 8.00 mm were formed at a pitch of 715 mm, and two pin insertion holes 12 and 22 were formed at the center of the width of the photomask. A photomask was prepared.
As shown in FIG. 2, a pin used for positioning the photomask has a photomask mounting portion 31 having an outer diameter of 8.00 mm and a thickness of 0.2 mm, and a photomask having an outer diameter of 12 mm and a thickness of 0.2 mm. A male pin having a seat 32 for preventing the falling off, and further having a tapered male pin portion 33 having a lower outer diameter of 6.00 mm and a height of 6.00 mm was prepared thereon. The female pin 40 has a seat 41 having an outer diameter of 12 mm and a thickness of 0.2 mm for preventing the photomask from coming off, and a columnar portion 44 having an outer diameter of 8.00 mm and a height of 8 mm is provided thereon. A female pin having a female pin portion 43 having a tapered cavity with a lower outer diameter φ6.00 mm and a height of 6.00 mm inside the female pin 40 was prepared.
As the upper frame of the baking frame of the exposure apparatus, as shown in FIG. 5A, a through hole of 8 mm thick acrylic and having a diameter of 40 mm at a pitch of 715 mm is formed in two places at the center of the width. An acrylic having a thickness of 20 mm and an outer diameter of φ60 mm was prepared as a capsule 70 having a counterbore of φ50 mm and depth of 7 mm so as to be aligned with the center of a through hole provided in the upper frame 50. A lower frame 60 made of acrylic having a thickness of 8 mm and having a bank rubber 61 having a width of 20 mm and a height of 5 mm disposed therearound was prepared.
An exposure apparatus for irradiating a photocurable film formed on both surfaces of a substrate with upper and lower exposure light beams through a photomask as an exposure apparatus, which is commercially available as a printed wiring board manufacturing apparatus. 501 (Oak Manufacturing Co., Ltd., trade name) was used. In this apparatus, the exposure light is ultraviolet light and the light source is a mercury lamp.
The lower photomask was attached to the lower frame by the following method. As shown in FIG. 4B, the photomask mounting portion of the male pin 30 was inserted from above the photomask into two male pin holes of φ8.00 mm formed in the lower photomask. The male pin is fixed to the photomask in the lower frame such that the center of the capsule 70 in the upper frame coincides with the center of the male pin 30 so that distortion of the photomask does not occur. The photomask was fixed to the lower frame with a mylar tape (trade name: polyester adhesive tape # 25 × 30 × 30, manufactured by Teraoka Seisakusho) so as not to cause distortion at the four corners of the photomask.
The upper photomask was attached to the upper frame by the following method. As shown in FIG. 4A, a female pin 40 is inserted from below the upper photomask 10 into two female pin insertion holes 12 of φ8.00 mm formed in the upper photomask 10, and After inserting the female pin fixing disk 110 from above, the spring washer 90 is fixed on the female pin 40, and the spring 100 is placed on the spring washer 90. After that, the upper frame 50 is lowered, the female pin 40 is weighted by the spring 100 and positioned with the male pin 30, and the upper and lower frames are brought into vacuum contact with each other by suction from suction ports provided at four corners of the lower frame 50. Maintain the fitted state. After the upper and lower frames are brought into vacuum contact, a screw is inserted into the female pin fixing disk mounting hole 120 and the screw is tightened, thereby fixing the female pin fixing disk 110 to the capsule 70. Thus, the upper photomask 10 was fixed to the upper frame 50.
After the photomask was attached and alignment was performed by the above-described method, a double-sided copper-clad laminate in which a dry film-shaped etching resist material was laminated was inserted between the upper and lower firing frames, and vacuum-adhered, followed by irradiation with ultraviolet rays. Insertion of the substrate and irradiation of ultraviolet rays were continuously performed on 120 sheets, and thereafter, a total of 12 double-sided copper-clad laminates were etched every 10 exposures to obtain printed wiring boards.
[0015]
[Comparative example]
FIGS. 6A and 6B show the male pin and the female pin used in the comparative example. In the comparative example, a printed wiring board was manufactured using the straight pin male pin 130 and the female pin 140 in the same manner as in the example.
The inner diameter of the female pin 140 used was φ5.00 mm. The outer diameter of the fitting portion of the male pin 130 with the female pin 140 is set to φ4.95 mm because unless it is smaller than the female pin 140, it becomes impossible to drive the upper and lower portions of the grill.
[0016]
Table 1 shows the results of measuring the positional accuracy of the front and back patterns of the printed wiring boards obtained in the examples and the comparative examples. It was confirmed that the positional accuracy of the front and back patterns obtained by the present invention was superior to that of the comparative example.
[0017]
[Table 1]

[0018]
【The invention's effect】
As described above, according to the present invention, it is possible to provide an exposure apparatus which is inexpensive and capable of aligning two upper and lower photomasks with high accuracy, and a method for manufacturing a printed wiring board using the exposure apparatus.
Further, according to the present invention, it is possible to perform high-accuracy alignment without using an expensive CCD camera, so that an inexpensive exposure apparatus can be provided.
[Brief description of the drawings]
FIG. 1 shows an example of a position for drilling upper and lower photomasks according to the present invention.
FIG. 2 shows an example of a front view and a top view of a male pin and a female pin of the present invention.
FIG. 3 is a cross-sectional view showing an example of an upper and lower photomask alignment state of the present invention.
FIG. 4 is a cross-sectional view showing an example of a method of attaching a photomask to a burning frame using male pins and female pins according to the present invention.
FIG. 5 is an example of a top view and a sectional view of the upper and lower grilling frames of the present invention.
FIG. 6 is a front view and a top view of a straight type male pin and a female pin used in a comparative example.
[Explanation of symbols]
Reference Signs List 10 Upper photomask 11, 21 Pattern 12 Female pin insertion hole 20 Lower photomask 22 Male pin insertion hole 30 Male pin 40 Female pin 50 Upper frame 60 Lower frame 70 Capsule 90 Spring washer 100 Spring 110 Disk for female pin fixing 120 Disk mounting hole for female pin fixing

Claims (4)

In the method of aligning the upper and lower two photomasks, two or more holes are formed in each photomask, and the holes formed in the first photomask partially have the same outer diameter as the hole diameter. Insert a tapered male pin, insert a female pin having the same outer diameter as the hole diameter and a tapered cavity inside the hole drilled in the second photomask, and combine the male pin with the female pin. A method for aligning a photomask, which comprises fitting. A method of aligning a photomask, comprising: weighting the male pin or the female pin when fitting the male pin and the female pin. Tapered male pin;
A female pin having a tapered cavity therein and capable of fitting with the male pin;
An exposure apparatus for a photomask, comprising: an upper frame on which a plurality of capsules for accommodating the female pin are formed; an upper frame for attaching an upper photomask; and a lower frame for attaching a lower photomask. A method for manufacturing a printed wiring board, wherein the manufacturing method is performed using the photomask exposure apparatus according to claim 3.

Images