JP2005265949A - Method for exposing photosensitive recording medium and method for exposing blank for printed wiring board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To increase the fineness of a wiring pattern without reducing the mechanical strength of a tent membrane in a method for exposing a blank for a printed wiring board. <P>SOLUTION: A blank 30 for a printed wiring board is prepared by sequentially stacking a substrate layer 21, a metal layer 23 and a photosensitive layer 19 having sensitivity to light of a predetermined wavelength, wherein the photosensitive layer 19 is formed by sequentially stacking from the metal layer 23 side a high sensitivity photosensitive layer 13 having high sensitivity to light of the predetermined wavelength and a low sensitivity photosensitive layer 12 having lower sensitivity to light of the predetermined wavelength than the high sensitivity photosensitive layer 13 and having a larger thickness than the high sensitivity photosensitive layer 13. The blank 30 is irradiated with laser light Le having the above predetermined wavelength from the photosensitive layer 19 side while condensing the laser light Le on a position P in the high sensitivity photosensitive layer 13, whereby the photosensitive layer 19 is exposed and cured. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for exposing a photosensitive recording medium and a method for exposing a printed wiring board material, and more specifically, a method for exposing a photosensitive recording medium having a high-sensitivity photosensitive layer and a low-sensitivity photosensitive layer, and a method for exposing a printed wiring board material. It is about.

  In the printed wiring board manufacturing field, a wiring pattern of a printed wiring board is formed by using a photolithography technique using a dry film photoresist comprising a support and a photosensitive layer laminated on the support. Yes.

  For example, the production of a printed wiring board having a through hole is performed as follows. First, a through-hole is formed by opening a hole in a copper-clad laminate in which a copper thin film as a metal layer is laminated on a substrate layer made of an insulating material, and a metal film is laminated on the side wall surface in the through-hole, The photosensitive layer side of the dry film photoresist is attached to the surface of the metal layer to obtain a printed wiring board material which is a photosensitive recording medium in which a dry film photoresist is laminated on a copper clad laminate. Next, a predetermined pattern of light is irradiated from the dry film photoresist side to the wiring pattern formation region and the through hole opening portion region to cure the photosensitive layer. Next, the dry film photoresist support is peeled off, and the photosensitive layer cured in the wiring pattern formation region and the photosensitive layer (called a tent film) cured in the through-hole opening region. The uncured photosensitive layer located in the region is removed to expose the metal layer. Thereafter, the exposed metal layer region is etched, and the cured photosensitive layer is removed to produce a printed wiring board having a wiring pattern formed on the substrate layer. Such a process is disclosed in Patent Document 1, for example.

  It is effective to reduce the thickness of the photosensitive layer of the dry film photoresist for the miniaturization of the wiring pattern. However, since there is no substrate layer that supports the photosensitive layer in the through hole opening, reducing the thickness of the photosensitive layer increases the mechanical strength of the photosensitive layer (tent film) cured in the region of the through hole opening. Therefore, when the printed wiring board is manufactured, the tent film is easily broken. For example, if the tent film is torn during the etching process, the etchant enters the through hole, and the metal film constituting a part of the wiring laminated on the side wall surface in the through hole is removed. There is a fear.

  For this reason, development of a dry film photoresist capable of forming a fine wiring pattern and capable of curing the photosensitive layer so that the tent film at the opening of the through hole is difficult to be broken is underway.

  For example, a print having two photosensitive layers with different sensitivities formed by pasting a dry film photoresist formed by laminating a high-sensitivity photosensitive layer, a low-sensitivity photosensitive layer, and a support layer on the copper-clad laminate. A method of creating a printed wiring board using a wiring board material has been studied by the present applicant.

  This method hardens the high-sensitivity photosensitive layer and the low-sensitivity photosensitive layer in the region of the through-hole opening where mechanical strength is required, that is, increases the mechanical strength by increasing the thickness of the photosensitive layer to be cured. In the wiring pattern formation area, only the high-sensitivity photosensitive layer is cured, that is, the thickness of the cured photosensitive layer is reduced to enable the formation of a fine wiring pattern, and the fine wiring while suppressing the tent film breakage. A pattern is to be formed.

On the other hand, as a method for exposing a predetermined wiring pattern to the printed wiring board material, a laser beam is emitted by a digital micromirror device (hereinafter referred to as DMD) in which a number of micromirrors having variable reflection angles are arranged two-dimensionally. There is known a projection exposure apparatus that reflects a spatial light and modulates a spatial light, and irradiates a material for a printed wiring board with the spatial light modulated laser light to expose a two-dimensional wiring pattern on a photosensitive layer (Patent Document). 2).
JP-A-6-169146 JP 2003-345030 A

  When a single photosensitive layer is exposed with laser light, the laser light is focused on the surface of the photosensitive layer (the surface on the laser light incident side). Therefore, even in the case of a multi-layered photosensitive layer having a plurality of photosensitive layers having different sensitivities, exposure is performed in the same manner as described above by condensing laser light on the incident-side surface of the multi-layered photosensitive layer. However, in order to make the wiring pattern finer without reducing the mechanical strength of the tent film, the position where the laser beam is focused and the layer structure of multiple photosensitive layers with different sensitivities are made more desirable. There is a request to decide.

  The present invention has been made in view of the above circumstances, and an exposure method of a photosensitive recording medium and exposure of a printed wiring board material capable of further miniaturizing a wiring pattern without reducing the mechanical strength of the tent film. It is intended to provide a method.

  In the exposure method for a photosensitive recording medium of the present invention, a light beam having the predetermined wavelength is condensed on a photosensitive recording medium in which a substrate layer and a photosensitive layer sensitive to light of a predetermined wavelength are laminated in this order. An exposure method for a photosensitive recording medium in which the photosensitive layer is exposed and cured by irradiation, wherein the photosensitive layer has a high sensitivity photosensitive layer having a predetermined sensitivity to the light of the predetermined wavelength, and the light of the predetermined wavelength. A low-sensitivity photosensitive layer having a lower sensitivity than the sensitivity of the high-sensitivity photosensitive layer and a thickness greater than the thickness of the high-sensitivity photosensitive layer is laminated in this order from the substrate layer side. The light position is located.

  The substrate layer may be a glass substrate.

  The light beam having the predetermined wavelength may be irradiated from the glass substrate side.

  The method for exposing a printed wiring board material of the present invention is as follows. From the photosensitive layer side, the printed wiring board material is formed by laminating a substrate layer, a metal layer, and a photosensitive layer sensitive to light of a predetermined wavelength in this order. An exposure method for a printed wiring board material in which a photosensitive layer is exposed and cured while condensing a light beam having a predetermined wavelength, wherein the photosensitive layer has a predetermined sensitivity to light of the predetermined wavelength. A low-sensitivity photosensitive layer having a sensitivity lower than the sensitivity of the high-sensitivity photosensitive layer and greater than the thickness of the high-sensitivity photosensitive layer in this order from the metal layer side. It is laminated, and the light beam condensing position is located in the high-sensitivity photosensitive layer.

  The photosensitive recording medium exposure method of the present invention comprises a high-sensitivity photosensitive layer having a predetermined sensitivity to light of a predetermined wavelength, a sensitivity to light of a predetermined wavelength is lower than the sensitivity of the high-sensitivity photosensitive layer, and this high sensitivity. Since the light condensing position where the thickness of the light beam of the light beam is the thinnest position is positioned in the high sensitivity photosensitive layer of the photosensitive layer laminated in this order with the low sensitivity photosensitive layer thicker than the thickness of the photosensitive layer, A finer wiring pattern can be exposed to this highly sensitive photosensitive layer. In addition to this, even if the condensing position of the light beam fluctuates in the thickness direction of the high-sensitivity photosensitive layer due to warpage or unevenness of the photosensitive recording medium, or vibration of the exposure apparatus that irradiates the light beam, the high-sensitivity photosensitive layer Fluctuation in the thickness of the light beam of the light beam located inside can be reduced compared to the case where the light beam is focused outside the high-sensitivity photosensitive layer, that is, in the vicinity of the beam waist of the light beam. Since the variation in the thickness of the light beam in the optical axis direction is small, a fine wiring pattern can be recorded more reliably on the high-sensitivity photosensitive layer.

  Further, if the substrate layer is a glass substrate and the light beam having a predetermined wavelength is irradiated from the glass substrate side, the degree of freedom in setting the light beam irradiation position can be increased.

  The exposure method for a printed wiring board material of the present invention includes a high-sensitivity photosensitive layer having a predetermined sensitivity to light of a predetermined wavelength, and a sensitivity to light of a predetermined wavelength is lower than the sensitivity of the high-sensitivity photosensitive layer. A light condensing position where the thickness of the light beam of the light beam is the thinnest in the high sensitivity photosensitive layer of the photosensitive layer in which the low sensitivity photosensitive layer thicker than the thickness of the high sensitivity photosensitive layer is laminated in this order from the metal layer side. Since it is positioned, a finer wiring pattern can be exposed on the high-sensitivity photosensitive layer. In addition to this, even if the condensing position of the light beam fluctuates in the thickness direction of the high-sensitivity photosensitive layer due to warpage or unevenness of the material for the printed wiring board or vibration of the exposure apparatus that irradiates the light beam, the high sensitivity Fluctuation in the thickness of the light beam located in the photosensitive layer can be suppressed to be smaller than that in the case where the light beam condensing position is located outside the high-sensitivity photosensitive layer, that is, the beam waist of the light beam. Since there is little variation in the thickness of the light beam in the optical axis direction, a fine wiring pattern can be recorded more reliably on the high-sensitivity photosensitive layer.

  On the other hand, in areas where there are openings such as through holes or via holes, in addition to the high-sensitivity photosensitive layer, a low-sensitivity photosensitive layer thicker than the thickness of the high-sensitivity photosensitive layer can be cured. The tent film formed in this way can have high mechanical strength and is difficult to break.

  As described above, the exposure to the photosensitive recording medium and the exposure to the printed wiring board material can be performed so that the wiring pattern can be made finer without reducing the mechanical strength of the tent film.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a conceptual diagram showing a method for exposing a printed wiring board material according to an embodiment of the present invention. A state in which laser light is irradiated on the printed wiring board material is shown in the thickness direction of the printed wiring board material. It is the figure seen from the orthogonal direction. FIG. 2 is a view of a dry film photoresist in which a protective film, a high-sensitivity photosensitive layer, a low-sensitivity photosensitive layer, and a flexible transparent film support are laminated in this order as seen from a direction perpendicular to the thickness direction. FIG. 4 is a diagram showing a relationship between an irradiation light amount (recording energy) when a photosensitive layer is irradiated with light of a predetermined wavelength and a thickness of a layer cured by the light irradiation.

  As shown in FIG. 1, the printed wiring board material exposure method of the present invention, which is an example of a photosensitive recording medium exposure method, includes a substrate layer 21, a metal layer 23, and a photosensitive layer 19 sensitive to light of a predetermined wavelength. The printed wiring board material 30 laminated in this order is irradiated with the laser beam Le, which is an example of the light beam having the predetermined wavelength, from the photosensitive layer 19 side while being condensed to expose the photosensitive layer 19. In this exposure method, the photosensitive layer 19 has a high-sensitivity photosensitive layer 13 having a predetermined sensitivity to light of the predetermined wavelength, and the sensitivity to the light of the predetermined wavelength is higher than the sensitivity of the high-sensitivity photosensitive layer 13. A low-sensitivity photosensitive layer 12 that is lower and thicker than the high-sensitivity photosensitive layer 13 is laminated in this order from the metal layer 23 side, and the condensing position P of the laser beam Le in the high-sensitivity photosensitive layer 13. (The thinnest luminous flux ) And it is to position the. In addition, the printed wiring board material 30 described here is one in which the flexible transparent film support 11 is laminated on the photosensitive layer 19 in addition to the above layer configuration. The flexible transparent film support 11 may be omitted.

  Here, “the sensitivity of the low-sensitivity photosensitive layer is lower than the sensitivity of the high-sensitivity photosensitive layer” means that the curing of the high-sensitivity photosensitive layer 13 is less than the low-sensitivity photosensitive layer 12 and the irradiation light quantity (recording energy) of laser light. Means that it starts with.

  As shown in FIG. 2, the dry film photoresist 10 including the photosensitive layer 19 and the flexible transparent film support 11 used to make the printed wiring board material 30 is a protective film. 14. The high-sensitivity photosensitive layer 13, the low-sensitivity photosensitive layer 12 whose sensitivity to light of the predetermined wavelength is lower than the sensitivity of the high-sensitivity photosensitive layer and thicker than the thickness of the high-sensitivity photosensitive layer, and the flexible transparent film support The body 11 is laminated in this order.

  Referring to FIG. 3, the recording energy of the light having the predetermined wavelength irradiated to the photosensitive layer 19 and the amount of curing of the photosensitive layer 19, that is, the light is cured by irradiation with the light having the predetermined wavelength in the photosensitive layer 19. The relationship with the thickness to be obtained will be described. In FIG. 3, the horizontal axis is a logarithmic scale and indicates recording energy when irradiated with light of a predetermined wavelength, and the vertical axis indicates the thickness of the photosensitive layer cured by irradiation with light of a predetermined wavelength. The value 0 to value D on the vertical axis indicates the high-sensitivity photosensitive layer 13, the value D to value E indicates the low-sensitivity photosensitive layer 12, and the value 0 to value E indicates the total thickness of the photosensitive layer 19. .

  The light of a predetermined wavelength irradiated from the low-sensitivity photosensitive layer 12 propagates in the order of the low-sensitivity photosensitive layer 12 and the high-sensitivity photosensitive layer 13, but the high-sensitivity photosensitive layer 13 precedes the low-sensitivity photosensitive layer 12. Curing begins.

The value S of the amount of light (recording energy) at which curing of the high-sensitivity photosensitive layer 13 begins is in the range of 0.31 to 0.63 (mJ / cm ² ), and the amount of curing of the high-sensitivity photosensitive layer 13 is the recording energy. As the number increases, the entire photosensitive layer 13 is cured. The value A of the amount of light (recording energy) necessary for curing the entire high-sensitivity photosensitive layer 13 is 0.94 (mJ / cm ² ) or more.

After the entire high-sensitivity photosensitive layer 13 is cured, if the amount of light is increased, curing of the low-sensitivity photosensitive layer 12 starts with a light amount (recording energy) value C, and if the amount of light is further increased, the amount of light (recording energy) is increased. When the value B is not less than B, the entire low-sensitivity photosensitive layer 12 is cured. The light intensity (recording energy) value C is 2.5 (mJ / cm ² ), and the light intensity (recording energy) value B is 5.0 (mJ / cm ² ).

  Each of the high-sensitivity photosensitive layer 13 and the low-sensitivity photosensitive layer 12 constituting the photosensitive layer 19 having such a photosensitivity curve is a photosensitive resin composition containing a binder polymer, an ethylenically unsaturated bond-containing monomer, and a photopolymerization initiator. For example, the content of the photopolymerization initiator in the high-sensitivity photosensitive layer 13 is greater than that of the low-sensitivity photosensitive layer 12 or the high-sensitivity photosensitive layer 13. It can be obtained by adding a sensitizer. In addition, as the flexible transparent film support 11, a PET resin (with a refractive index of about 1.57) is usually used.

  Next, a method for manufacturing a printed wiring board using a material for a printed wiring board having a through hole, which is created using the dry film photoresist 10, will be described with reference to FIG. FIG. 4 is a diagram showing each step of a method for manufacturing a printed wiring board using a printed wiring board material.

  As shown in FIG. 4A, a printed circuit board manufacturing substrate 25 having a through hole 22 and having a metal layer 23 laminated on the substrate layer 21 is prepared. As a printed wiring board manufacturing substrate 25, a copper-clad laminate in which a metal layer that is a copper thin film is laminated on a substrate layer made of an insulating material, a copper plating layer on a substrate layer made of an green base material such as glass-epoxy In addition to the above-described layer structure, a layer in which a layer insulating film is stacked between a substrate layer and a metal layer (not shown) or the like can be used.

  Next, the protective film 14 is peeled from the dry film photoresist 10, and the high-sensitivity photosensitive layer 13 side of the dry film photoresist 10 is placed on the printed circuit board forming substrate 25 as shown in FIG. The dry film photoresist 10 and the printed wiring board forming substrate 25 are pressure-bonded using the pressure roller 31 so as to be positioned on the metal layer 23 side (lamination process). As a result, the printed wiring board material 30 in which the substrate layer 21, the metal layer 23, the high-sensitivity photosensitive layer 13, the low-sensitivity photosensitive layer 12, and the flexible transparent film support 11 are laminated in this order is obtained. Note that the printed wiring board material 30 is not necessarily provided with the flexible transparent film support 11, and may be one in which the flexible transparent film support 11 is omitted.

Next, as shown in FIG. 4C, the photosensitive layer 19 is cured by irradiating the laser beam having the predetermined wavelength from the portable transparent film support 11 side of the printed wiring board material 30. Laser light of a light amount (for example, 1.5 (mJ / cm ² ): see value G in FIG. 3) for curing the high-sensitivity photosensitive layer 13 is applied to the wiring pattern forming region of the printed wiring board forming substrate 21. By irradiating with a predetermined wiring pattern, a hardened region 15 showing the wiring pattern is formed in the high-sensitivity photosensitive layer 13 (wiring portion exposure step).

Subsequently, at the opening portion of the through hole 22 of the printed wiring board forming substrate 25 and in the vicinity thereof, a light amount (for example, 8.0 (mJ / cm) for curing both the low-sensitivity photosensitive layer 12 and the high-sensitivity photosensitive layer 13. ² ): Refer to the value H in FIG. 3) to irradiate the photosensitive layer 19 (the low-sensitivity photosensitive layer 12 and the high-sensitivity photosensitive layer 13) with a predetermined pattern for protecting the metal layer, thereby protecting the metal layer. A hardened region 16 (tent film) showing a pattern for use is formed. (Through hole exposure process). The wiring portion exposure step and the through hole portion exposure step may be performed independently or in parallel.

  The exposure is performed by laser light irradiation using a projection exposure apparatus described later.

  Next, as shown in FIG. 4D, the flexible transparent film support 11 is peeled from the printed wiring board material 30 (support peeling process).

  Subsequently, as shown in FIG. 4E, the uncured layer in the low-sensitivity photosensitive layer 12 or the high-sensitivity photosensitive layer 13 in the printed wiring board material 30 from which the flexible transparent film support 11 has been peeled off. The region is dissolved and removed with an appropriate developer (weak alkaline aqueous solution), and the metal layer 23 is removed in the region 17 other than the cured region 15 for wiring pattern formation and the cured region 16 for protecting the metal layer in the vicinity of the through hole 22. Expose (development process).

  Next, as shown in FIG. 4F, the metal layer 23 in the exposed region 17 is dissolved and removed with an etching solution (etching process). As a result, a wiring pattern 24 is formed in the metal layer 23.

  Next, as shown in FIG. 4G, a highly sensitive photosensitive layer piece 13 ′ cured in the cured region 15 and a photosensitive material cured in the cured region 16 with a strong alkaline aqueous solution such as sodium hydroxide or potassium hydroxide. The layer piece 19 ′ is removed (cured product removing step).

  As described above, according to the method for exposing a printed wiring board material of the present invention, a cured region made of a thin high-sensitivity photosensitive layer can be formed in a region where a wiring pattern is formed, and a through-hole opening and its A cured region composed of a low-sensitivity photosensitive layer and a high-sensitivity photosensitive layer that are relatively thick and difficult to tear can be formed in a nearby region. Needless to say, the exposure method of the printed wiring board material can be applied to the production of a printed wiring board having via holes in addition to through holes.

  Here, the setting for positioning the condensing position P of the laser beam Le in the high-sensitivity photosensitive layer 13 will be described. FIG. 5 is a view showing a state in which the condensing position of the laser light is set in the high sensitivity photosensitive layer.

  As shown in FIG. 5, the printed circuit board material 30 is placed on a flat moving stage 152 of a projection exposure apparatus, which will be described later, and the condensing position P of the laser beam Le emitted from the projection exposure apparatus is a highly sensitive photosensor. Coarse adjustment is performed so as to be located in the vicinity of the layer 13, and this position is set as a temporary origin Po. Here, the temporary origin Po is not necessarily limited to being located in the high sensitivity photosensitive layer 13. Then, the condensing position P of the laser beam Le is changed from −100 μm (the metal layer 23 side is the condensing position) to +100 μm (the low-sensitivity photosensitive layer 12 side is the condensing position) from the temporary origin in the thickness direction of the photosensitive layer 19. For each printed circuit board at each position P (P-100, P-99, P-98... P-1, Po, P + 1, P + 2... P + 100). A predetermined wiring pattern is recorded in a different area on the material 30 with a predetermined recording energy.

  Development, etching, and hardened product removal treatment for the printed circuit board material 30 on which wiring patterns are recorded at different positions each time the substrate is moved at a pitch of 5 μm from −100 μm to +100 μm with respect to the temporary origin Po. Thus, a printed wiring board on which a wiring pattern is recorded at the condensing position of each laser beam is obtained.

  When the thinnest line is obtained among the wiring patterns formed at the respective condensing positions of the laser beams in the printed wiring board thus obtained, the light condensing is performed in the high-sensitivity photosensitive layer 13. Assuming that the position P is located, a setting for determining the condensing position P of the laser beam Le in the high-sensitivity tourist layer 13 is performed.

  On the other hand, the condensing position P of the laser beam Le is located at a position P + 37 that is a boundary between the low-sensitivity photosensitive layer 12 and the flexible transparent film support 11, for example, deviated from the high-sensitivity photosensitive layer 13. In this case, the light beam of the laser beam Le becomes thick in the high-sensitivity photosensitive layer 13, and the above thin line cannot be obtained, so that a fine wiring pattern cannot be formed.

  Further, by positioning the condensing position P (which is also the position of the beam waist) of the laser beam Le in the high-sensitivity photosensitive layer 13, the condensing position P is displaced in the thickness direction of the high-sensitivity tourist layer 13. The variation in the thickness of the laser beam Le passing through the high-sensitivity photosensitive layer is, for example, the variation in the thickness of the laser beam Le when the condensing position P of the laser beam Le is displaced at the condensing position P + 37. Can be reduced compared to

  The wiring pattern recorded on the printed circuit board material for positioning the light condensing position P includes a wiring pattern extending in at least two vertical and horizontal directions. Furthermore, in the combination of the printed circuit board material and the projection exposure apparatus, the line width / space width (line and space) when recording the thinnest wiring pattern is finer than, for example, 15 μm / 15 μm, for example, the line width A wiring pattern that includes a wiring pattern with a space width of 5 μm / 5 μm and can be recorded with a margin in the combination of the printed circuit board material and the projection exposure apparatus, for example, a wiring pattern with a line width / space width of 50 μm / 50 μm It is desirable to include.

  In the above-described embodiment, the photosensitive layer has a two-layer configuration including a high-sensitivity photosensitive layer and a low-sensitivity photosensitive layer. However, the photosensitive layer is not limited to such a case, and the photosensitive layer has three or more layers having different sensitivities. It may be constituted by. Further, the photosensitive layer may be formed by laminating a separating layer that prevents the components of both from crossing between the high-sensitivity photosensitive layer and the low-sensitivity photosensitive layer. In the case of using a photosensitive layer composed of three or more layers, the same as described above is established by defining a layer corresponding to the high-sensitivity photosensitive layer and a layer corresponding to the low-sensitivity photosensitive layer among the layers. The exposure of the photosensitive layer can be carried out.

  The following projection exposure apparatus can be used as an example of an apparatus that records a wiring pattern or the like by irradiating the printed board material 30 with a laser beam.

  As disclosed in Japanese Patent Laid-Open No. 2003-345030, this projection exposure apparatus directly draws a wiring pattern on an exposure surface with a laser beam modulated by a spatial light modulation element. This device is a digital micromirror device (registered trademark of Texas Instruments) in which a number of micromirrors constituting one pixel are arranged in a grid (for example, 1024 × 768) as a spatial light modulator. (Hereinafter referred to as DMD). In this apparatus, each micromirror is individually controlled based on the value of each pixel data indicating a wiring pattern, and the laser light incident on each micromirror is reflected in one of two directions. Laser light reflected in one of the two directions (laser light when the micromirror is turned on) is applied to the printed wiring board material through a predetermined optical system. Thereby, a laser beam can be irradiated on the printed wiring board material, and the photosensitive layer in the printed wiring board material can be exposed to the shape of the wiring pattern. In addition, the irradiation light quantity of a laser beam can be adjusted by managing the time which a micro mirror is kept ON.

  As shown in FIG. 6, the projection exposure apparatus 200 includes a flat plate-like moving stage 152 that holds the printed wiring board material 30 by adsorbing it to the surface. Two guides 158 extending along the stage moving direction are installed on the upper surface of the thick plate-shaped installation table 156 supported by the four legs 154. The stage 152 is arranged so that the longitudinal direction thereof faces the stage moving direction, and is supported by a guide 158 so as to be reciprocally movable. The projection exposure apparatus is provided with a stage driving device (not shown) that drives a stage 152 as sub-scanning means along a guide 158.

  A U-shaped gate 160 is provided at the center of the installation table 156 so as to straddle the movement path of the stage 152. Each of the ends of the U-shaped gate 160 is fixed to both side surfaces of the installation table 156. A scanner 162 is provided on one side of the gate 160, and a plurality of (for example, two) sensors 164 for detecting the front and rear ends of the printed wiring board material 30 are provided on the other side. . The scanner 162 and the sensor 164 are respectively attached to the gate 160 and fixedly arranged above the moving path of the stage 152. The scanner 162 and the sensor 164 are connected to a controller (not shown) that controls them.

As shown in FIGS. 7 and 8B, the scanner 162 includes a plurality of (for example, 14) exposure heads 166 arranged in a substantially matrix of m rows and n columns (for example, 3 rows and 5 columns). . In this example, four exposure heads 166 are arranged in the third row in relation to the width of the printed wiring board material 30. In addition, when showing each exposure head arranged in the m-th row and the n-th column, it is expressed as an exposure head 166 _mn .

An exposure area 168 by the exposure head 166 has a rectangular shape with a short side in the sub-scanning direction. Accordingly, as the stage 152 moves, a strip-shaped exposed region 170 is formed for each exposure head 166 in the printed wiring board material 30. In addition, when showing the exposure area by each exposure head arranged in the m-th row and the n-th column, it is expressed as an exposure area 168 _mn .

Further, as shown in FIGS. 8A and 8B, each of the exposure heads in each row arranged in a line so that the strip-shaped exposed regions 170 are arranged without gaps in the direction orthogonal to the sub-scanning direction. These are arranged with a predetermined interval (natural number times the long side of the exposure area, twice in this example) in the arrangement direction. Therefore, can not be exposed portion between the exposure area 168 ₁₁ in the first row and the exposure area 168 _12, it can be exposed by the second row of the exposure area 168 ₂₁ and the exposure area 168 ₃₁ in the third row.

Each of the exposure heads 166 _{11 to} 166 _mn includes a DMD 50 as a spatial light modulation element that modulates incident laser light for each pixel in accordance with image data, as shown in FIGS. The DMD 50 is connected to a controller that includes a data processing unit and a mirror drive control unit. The data processing unit of the controller generates a control signal for driving and controlling each micromirror in the region to be controlled by the DMD 50 for each exposure head 166 based on the input image data. Further, the mirror drive control unit controls the angle of the reflection surface of each micromirror of the DMD 50 for each exposure head 166 based on the control signal generated by the image data processing unit.

    On the incident side of the DMD 50, a fiber array light source 66 having a laser emitting portion in which an emission end portion of the optical fiber is arranged in a line along a direction corresponding to the long side direction of the exposure area 168 is emitted from the fiber array light source 66. A lens system 67 for correcting the collected laser light and condensing it on the DMD 50 and a mirror 69 for reflecting the laser light transmitted through the lens system 67 toward the DMD 50 are arranged in this order. In FIG. 9, the lens system 67 is schematically shown.

  As shown in detail in FIG. 10, the lens system 67 includes a condensing lens 71 that condenses the laser light Le emitted from the fiber array light source 66, and a rod that is inserted into the optical path of the light that has passed through the condensing lens 71. It is composed of an integrator 72 and an imaging lens 74 arranged in front of the rod integrator 72, that is, on the mirror 69 side. The rod integrator 72 causes the laser light emitted from the fiber array light source 66 to enter the DMD 50 as a light beam that is close to parallel light and has a uniform light intensity within the beam cross section.

  The laser beam Le emitted from the lens system 67 is reflected by the mirror 69 and is irradiated to the DMD 50 via the TIR (total reflection) prism 70.

  On the light reflection side of the DMD 50, an imaging optical system 51 that images the laser light Le reflected by the DMD 50 on the printed wiring board material 30 for recording a pattern is disposed. Although this imaging optical system 51 is schematically shown in FIG. 9, as shown in detail in FIG. 10, a first imaging optical system comprising lens systems 52 and 54 and a first imaging system comprising lens systems 57 and 58 are provided. The image forming optical system includes two image forming optical systems, a microlens array 55 inserted between these image forming optical systems, and an aperture array 59. The microlens array 55 includes a large number of microlenses 55a corresponding to the pixels of the DMD 50. As an example, the micro lens 55a has a focal length of 0.19 mm and an NA (numerical aperture) of 0.11. The aperture array 59 is formed by forming a large number of apertures 59a corresponding to the microlenses 55a of the microlens array 55.

  The first image-forming optical system forms an image on the microlens array 55 by enlarging the image by the DMD 50 three times. The second imaging optical system enlarges the image that has passed through the microlens array 55 to 1.67 times, and forms and projects the image on the printed wiring board material 30. Therefore, as a whole, the image formed by the DMD 50 is enlarged and projected on the printed wiring board material 30 by a factor of five.

  In this example, a prism pair 73 is disposed between the second imaging optical system and the printed wiring board material 30, and the prism pair 73 is moved to collect light on the printed wiring board material 30. The focusing position of the laser beam, that is, the focus of the image to be formed can be adjusted. In the figure, the printed wiring board material 30 is sub-scanned in the arrow Y direction.

  As shown in FIG. 11, the DMD 50 is configured such that a micromirror 62 is supported on a SRAM cell (memory cell) 60 by a support, and a large number of pixels (pixels) (for example, (1024 × 768) micromirrors arranged in a lattice pattern. Each pixel is provided with a micromirror 62 supported by a support column at the top, and a material having a high reflectance such as aluminum is deposited on the surface of the micromirror 62. The reflectance of the micromirror 62 is 90% or more. A silicon gate CMOS SRAM cell 60 manufactured in a normal semiconductor memory manufacturing line is disposed directly below the micromirror 62 via a support including a hinge and a yoke, and the entire structure is monolithic. ing.

  When a digital signal is written in the SRAM cell 60 of the DMD 50, the micromirror 62 supported by the support is inclined within a range of ± α degrees (for example, ± 10 degrees) with respect to the substrate side on which the DMD 50 is disposed with the diagonal line as the center. It is done. 12A shows a state in which the micromirror 62 is tilted to + α degrees when the micromirror 62 is in the on state, and FIG. 12B shows a state in which the micromirror 62 is tilted to −α degrees when the micromirror 62 is in the off state. Therefore, by controlling the tilt of the micromirror 62 in each pixel of the DMD 50 according to the image signal as shown in FIG. 11, the laser light Le incident on the DMD 50 is reflected in the tilt direction of each micromirror 62. The

  FIG. 11 shows an example of a state in which a part of the DMD 50 is enlarged and the micromirror 62 is controlled to + α degrees or −α degrees. The on / off control of each micromirror 62 is performed by the controller connected to the DMD 50. A light absorber (not shown) is disposed in the direction in which the laser beam Le reflected by the micromirror 62 in the off state travels.

  Next, the electrical configuration of the projection exposure apparatus 200 will be described with reference to FIG. As shown in the figure, a modulation circuit 301 is connected to the overall control unit 300. The modulation circuit 301 acquires binary image data that has undergone pixel value replacement processing from the pixel value replacement unit 15 in FIG. 4. A controller 302 that controls the DMD 50 is connected to the modulation circuit 301. Further, an LD (Laser Diode) drive circuit 303 that drives the laser module 64 is connected to the overall control unit 300. The overall controller 300 is connected to a stage driving device 304 that drives the stage 152.

  Next, the operation of the projection exposure apparatus 200 will be described. In each exposure head 166 of the scanner 162, each of the laser beams emitted in a divergent light state from each of the GaN-based semiconductor lasers constituting the combined laser light source of the fiber array light source 66 is collimated by a corresponding collimator lens. The The collimated laser beam is collected by a condenser lens and converged on the incident end face of the core of the multimode optical fiber.

  In this example, a condensing optical system is composed of a collimator lens and a condensing lens, and a multiplexing optical system is composed of the condensing optical system and a multimode optical fiber. That is, the laser light condensed by the condensing lens is incident on the core of the multimode optical fiber, propagates in the optical fiber, is combined with one laser light, and is exited from the multimode optical fiber. It is emitted from an optical fiber coupled to the.

  In each laser module, when the coupling efficiency of laser light to the multimode optical fiber is 0.85 and each output of the GaN-based semiconductor laser is 30 mW, the output is 180 mW for each of the optical fibers arranged in an array. A combined laser beam of (= 30 mW × 0.85 × 7) can be obtained. Therefore, a laser beam with an output of 2.52 W (= 0.18 W × 17) can be obtained with the entire 14 multimode optical fibers.

  At the time of image exposure, the image data subjected to the pixel value replacement process described above is input from the modulation circuit 301 shown in FIG. 13 to the controller 302 of the DMD 50 and temporarily stored in the frame memory.

  The stage 152 that adsorbs the printed wiring board material 30 to the surface is moved at a constant speed from the upstream side to the downstream side of the gate 160 along the guide 158 by the stage driving device 304 shown in FIG. When the leading edge of the printed wiring board material 30 is detected by the sensor 164 attached to the gate 160 while the stage 152 passes under the gate 160, the image data stored in the frame memory is read sequentially for a plurality of lines. A control signal is generated for each exposure head 166 based on the image data read out and read out by the data processing unit. Then, each of the micromirrors of the DMD 50 is controlled on and off for each exposure head 166 based on the generated control signal by the mirror drive control unit. In the case of this example, the size of the micromirror that becomes one pixel is 14 μm × 14 μm.

  When the DMD 50 is irradiated with laser light from the fiber array light source 66, the laser light reflected when the micromirror of the DMD 50 is in the on state is imaged on the printed wiring board material 30 by the lens systems 54 and 58. . In this manner, the laser light emitted from the fiber array light source 66 is turned on and off for each pixel, and the printed wiring board material 30 is exposed in a pixel unit (exposure area 168) that is substantially the same as the number of pixels used in the DMD 50. . Further, the printed wiring board material 30 is moved at a constant speed together with the stage 152, whereby the printed wiring board material 30 is sub-scanned in the direction opposite to the stage moving direction by the scanner 162, and a strip-like pattern is formed for each exposure head 166. An exposed area 170 is formed.

  When the sub-scan of the printed wiring board material 30 by the scanner 162 is completed and the rear end of the printed wiring board material 30 is detected by the sensor 164, the stage 152 is gated along the guide 158 by the stage driving device 304. It returns to the origin on the most upstream side of 160 and is moved again along the guide 158 from the upstream side to the downstream side of the gate 160 at a constant speed.

  The operation of the projection exposure apparatus 200 has been described above. In the present embodiment, the light source used in the projection exposure apparatus 200 may be selected so as to have the predetermined wavelength determined based on the wavelength sensitivity characteristic of the photosensitive layer.

The projection exposure apparatus 200 may include a plurality of types of light sources so that light beams with various wavelengths of 300 to 10600 nm can be selected as exposure light beams. As a light source, in addition to a semiconductor laser, a solid-state laser, a gas laser, or the like can be employed. Specifically, a semiconductor laser having a wavelength of about 650 nm, a laser combining a YAG laser having a wavelength of about 532 nm and SHG, a laser combining a YAG laser having a wavelength of about 355 nm and SHG, and a laser combining a YLF laser having a wavelength of about 355 nm and SHG. Candidates include a combination of a YAG laser having a wavelength of about 266 nm and SHG, an excimer laser having a wavelength of about 248 nm, an excimer laser having a wavelength of about 193 nm, and a CO ₂ laser having a wavelength of about 10600 nm. Furthermore, a mercury lamp or the like that emits light of a specific wavelength can be employed as the light source.

  Further, according to this apparatus, the recording energy to the printed wiring board material 30 can be increased by increasing the ratio of the ON time of the micromirror that is turned ON / OFF. Laser beams having different recording energies can be irradiated onto the photosensitive layer.

  Instead of the printed wiring board material, the following exposure may be performed on the following photosensitive recording medium. FIG. 14 is a conceptual diagram showing a method for exposing a photosensitive recording medium, and shows a state in which the photosensitive recording medium is irradiated with laser light as viewed from a direction perpendicular to the thickness direction of the photosensitive recording medium.

  As shown in FIG. 14, this photosensitive recording medium is exposed to a photosensitive recording medium 130 in which a substrate layer 121 made of a transparent glass plate and a photosensitive layer 119 sensitive to light of a predetermined wavelength are laminated in this order. An exposure method in which the photosensitive layer 119 is exposed and cured by condensing the laser beam Le having the predetermined wavelength from the photosensitive layer 119 side or the substrate layer 121 side. A high-sensitivity photosensitive layer 113 having a predetermined sensitivity to light of a predetermined wavelength, and a low sensitivity whose sensitivity to light of the predetermined wavelength is lower than the sensitivity of the high-sensitivity photosensitive layer 113 and thicker than the thickness of the high-sensitivity photosensitive layer 113 The photosensitive layer 112 is laminated in this order from the substrate layer 121 side, and the condensing position P of the laser beam Le (the position where the thickness of the light beam is the thinnest) is positioned in the high sensitivity photosensitive layer 113. It is intended to so that. Note that the photosensitive recording medium 130 described here is one in which a flexible transparent film support 111 is laminated on the photosensitive layer 119 in addition to the above layer structure. The transparent transparent film support 111 may be omitted. In addition, the substrate layer 121 in the photosensitive recording medium 130 can be handled as corresponding to the printed wiring board manufacturing substrate 25 in the printed wiring board material 30 described above. The operation and the like are the same as in the above-described exposure method for the printed wiring board material.

The conceptual diagram which shows the exposure method of the material for printed wiring boards of embodiment of this invention View of dry film photoresist viewed from the direction perpendicular to the thickness direction The figure which shows the relationship between the irradiation light quantity to a photosensitive layer, and the thickness of the layer hardened | cured by irradiation of this light The figure which shows each process of the manufacturing method of a printed wiring board The figure which shows a mode that it sets so that the condensing position of a laser beam may be located in a highly sensitive photosensitive layer Perspective view showing the external appearance of the projection exposure apparatus The perspective view which shows the structure of the scanner of a projection exposure apparatus (A) is a plan view showing an exposed area formed on a photosensitive material, and (B) is a view showing an arrangement of exposure areas by each exposure head. The perspective view which shows schematic structure of the exposure head of a projection exposure apparatus Cross section of the exposure head in the sub-scanning direction along the optical axis Partial enlarged view showing the structure of a digital micromirror device (DMD) (A) And (B) is explanatory drawing for demonstrating operation | movement of DMD. Block diagram showing the electrical configuration of the projection exposure apparatus The conceptual diagram which shows the exposure method of a photosensitive recording medium.

Explanation of symbols

12 Low Sensitive Photosensitive Layer 13 High Sensitive Photosensitive Layer 19 Photosensitive Layer 21 Substrate Layer 23 Metal Layer 30 Printed Wiring Board Material Le Laser Light P Condensing Position

Claims (4)

A photosensitive recording medium in which a substrate layer and a photosensitive layer sensitive to light of a predetermined wavelength are laminated in this order is irradiated with a light beam having the predetermined wavelength while being condensed to expose and cure the photosensitive layer. A method for exposing a photosensitive recording medium, comprising:
The photosensitive layer has a high-sensitivity photosensitive layer having a predetermined sensitivity to light of the predetermined wavelength, and the sensitivity to the light of the predetermined wavelength is lower than the sensitivity of the high-sensitivity photosensitive layer, and the thickness of the high-sensitivity photosensitive layer. A method of exposing a photosensitive recording medium, wherein a light-sensitive light-sensitive layer thicker than the substrate layer is laminated in this order from the substrate layer side, and the light beam condensing position is positioned in the high-sensitivity light-sensitive layer. . 2. The method for exposing a photosensitive recording medium according to claim 1, wherein the substrate layer is a glass substrate. 3. The method of exposing a photosensitive recording medium according to claim 2, wherein the light beam is irradiated from the glass substrate side. While condensing the light beam having the predetermined wavelength from the photosensitive layer side to the printed wiring board material in which the substrate layer, the metal layer, and the photosensitive layer having sensitivity to light of the predetermined wavelength are laminated in this order, It is an exposure method for a printed wiring board material that irradiates and exposes and cures the photosensitive layer,
The photosensitive layer has a high-sensitivity photosensitive layer having a predetermined sensitivity to light of the predetermined wavelength, and the sensitivity to the light of the predetermined wavelength is lower than the sensitivity of the high-sensitivity photosensitive layer, and the thickness of the high-sensitivity photosensitive layer. And a thicker low-sensitivity photosensitive layer in this order from the metal layer side, and the light-beam condensing position is positioned in the high-sensitivity photosensitive layer. Exposure method.

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