JP4085925B2 - Printed circuit board manufacturing method - Google Patents

Description

The present invention relates to a method for manufacturing a printed circuit board having a positioning mark on a substrate surface.

  Conventionally, there is a case where a positioning mark for indicating a reference position is provided on the surface of an article, and processing or the like is performed based on the positioning mark. In general, the positioning mark is optically recognized based on the difference in intensity of reflected light between the positioning mark and the surrounding portion.

  However, depending on the materials and colors used for the positioning mark and its surrounding area, the difference in intensity of reflected light between the positioning mark and its surrounding area becomes small, and the positioning mark cannot be accurately recognized. There is.

In view of the above problems, an object of the present invention is to provide a method for manufacturing a printed circuit board capable of accurately recognizing a positioning mark.

In order to achieve the above object, a printed circuit board manufacturing method according to claim 1 includes: a pattern forming step of forming a conductor pattern on at least one surface of a resin film made of a thermoplastic resin as an insulating substrate; Laminating a plurality of resin films including a mark forming step for forming a positioning mark for indicating a reference position at a predetermined position and a resin film having a conductor pattern and a resin film having a positioning mark so that the positioning mark is a surface layer A laminate process for forming a laminate, and by applying pressure while heating the laminate using a hot press plate, the resin films are bonded to each other to form an insulating substrate in which conductor patterns are arranged in multiple layers. Heating / pressurizing process to embed positioning marks in the insulating substrate so that the surface is flush with the surface of the insulating substrate, and heating / pressurizing After that, at least a part of the positioning mark exposed from the insulating substrate and the surrounding portion are directly irradiated with a laser beam having a higher absorption rate in the peripheral portion of the insulating substrate surrounding the positioning mark than the positioning mark. And a roughening step for roughening the portion.

As described above, when laser light having a higher absorption rate in the peripheral portion of the printed board than the positioning mark is used, the peripheral portion can be selectively roughened. Therefore, by irradiating at least a part of the positioning mark together with the peripheral portion, the entire peripheral portion can be irradiated with laser light even if errors such as misalignment and warpage occur. And since the reflectance of a surrounding part can be reduced and the intensity difference of the reflected light of a positioning mark and a surrounding part can be enlarged, the positioning mark of a printed circuit board surface can be recognized optically accurately. In the case of laser light, the peripheral portion can be concave.

In addition, since the roughening step is performed after the heating / pressurizing step, when the hot press plate is used for heating / pressurization, the roughened surface of the surrounding portion is crushed by the hot press plate, and the effect of the roughening is reduced. There is no fear.

As described in claim 2, the mark forming process, you are preferably carried out in the pattern forming step in the same process. By making the manufacturing process the same, the manufacturing process can be simplified and the manufacturing cost can be reduced. In particular, when the constituent materials of the conductor pattern and the positioning mark are the same, it is more preferable because the materials can be unified and the equipment can be simplified.

As described in claim 3, the positioning marks are preferably formed in a region that does not provide an electrical connection function. When the peripheral portion is roughened with laser light, if the circuit portion (constituted by a conductor pattern or the like) that provides an electrical connection function is provided near or below the positioning mark, the circuit portion is heated by the laser light. May be affected. Therefore, the positioning mark is preferably provided in a region that does not provide an electrical connection function on the printed circuit board.

Further, as described in claim 4 , the roughening step may be performed in the same step as the product number marking on the printed circuit board surface. Generally, the product number marking on the surface of the printed circuit board is performed using a laser beam. Therefore, the manufacturing process can be simplified and the manufacturing cost can be reduced by using the same laser as the product number marking for the roughening process.

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

  First, as shown to Fig.1 (a), the pattern formation process which forms the conductor pattern 2 on the single side | surface of the resin film 1 is made. As the resin film 1, for example, a recyclable thermoplastic resin can be used, and in the present embodiment, a liquid crystal polymer (LCP) having a thickness of 25 to 100 μm is used. The conductor pattern 2 is formed, for example, by etching a conductor foil stuck on one side of the resin film 1 into a desired pattern. As the conductor foil, for example, a low resistance metal foil containing at least one of Au, Ag, Cu, and Al can be used. In this embodiment, a Cu foil that is inexpensive and does not cause migration is used. In addition, formation of the conductor pattern 2 may be performed using the printing method besides the etching of the conductor foil.

  Here, in the present embodiment, the mark forming process for forming the positioning mark is performed in the same process as the pattern forming process. The positioning mark is a mark that indicates a reference position on the printed circuit board, and component mounting, electrical inspection, and the like are performed based on the distance from the mark.

  As shown in FIG. 1A, a positioning mark 3 is simultaneously formed with the same material as the conductor pattern 2 at a predetermined position on the surface of the resin film 1 on which the conductor pattern 2 is formed. Accordingly, since the conductor pattern 2 and the positioning mark 3 can be formed at a time, the manufacturing process can be simplified and the manufacturing cost can be reduced. In the present embodiment, the example in which the positioning mark 3 is formed in the same process as the conductor pattern 2 has been described. However, the positioning mark 3 may be formed at a timing different from the formation of the conductor pattern 2. Moreover, the conductor pattern 2 and the positioning mark 3 may be formed using different materials. Even with different materials, the conductor pattern 2 and the positioning mark 3 can be formed in the same process. For example, when the conductor pattern 2 and the positioning mark 3 are provided at positions separated from each other, different pastes and different squeegees are used for the respective areas corresponding to the conductor pattern 2 and the positioning mark 3 provided on one screen. Thus, the conductor pattern 2 and the positioning mark 3 may be simultaneously formed on the surface of the resin film 1.

  After the formation of the conductor pattern 2 and the positioning mark 3, as shown in FIG. 1A, the resin film 1 is irradiated with, for example, a carbon dioxide laser from the back side of the conductor pattern 2, and the bottom having the conductor pattern 2 as the bottom surface. A hole via hole 4 is formed. For the formation of the via hole 4, it is possible to use a UV-YAG laser, an excimer laser or the like in addition to the carbon dioxide laser. In addition, it is possible to form via holes mechanically by drilling etc., but since it is necessary to process so as not to damage the conductor pattern 2 with a small diameter, the processing method by laser should be selected. Is preferred.

  When the formation of the via hole 4 is completed, the via hole 4 is filled with a conductive paste 5 that is an interlayer connection material. The conductive paste 5 is a paste obtained by adding an organic solvent to metal particles such as Cu, Ag, Sn, and kneading them. In addition, the conductive paste 5 may be additionally mixed with a low melting point glass frit, an organic resin, or an inorganic filler as appropriate. The conductive paste 5 is filled into the via hole 4 using a screen printing machine, a dispenser or the like (not shown). By the above process, the 1st single-sided conductor pattern film 10 which has the conductor pattern 2 and the positioning mark 3 on the single side | surface of the resin film 1 is formed.

  In parallel with the formation of the first single-sided conductor pattern film 10, the second single-sided conductor pattern film 11 shown in FIG. 1B is also formed. The second single-sided conductor pattern film 11 is formed using the same material as the first single-sided conductor pattern film 10 and does not have the positioning mark 3 on the surface of the resin film 1. Therefore, it is carried out in the same process as the formation of the first single-sided conductor pattern film 10 except for the mark forming process.

  When the formation of the first and second single-sided conductor pattern films 10 and 11 is completed, as shown in FIG. 1C, a plurality of first and second single-sided conductor pattern films 10 and 11 (in this example, the first One single-sided conductor pattern film 10 and three second single-sided conductor pattern films 11 are positioned and laminated to form a laminate 20. At this time, the second single-sided conductor pattern film 11 is arranged on the surface layer of the multilayer body 20 so that the positioning mark 3 is exposed on the surface of the multilayer body 20. Of the four single-sided conductor pattern films 10 and 11, with the center of lamination as the boundary, the upper two layers have the conductor pattern 2 formed on the upper side, and the lower two layers have the conductor pattern 2 Laminate so that the formed surface is on the lower side. In addition, in FIG.1 (c), each single-sided conductor pattern film 10 and 11 is separated and shown for convenience.

  Thus, in this Embodiment, a multilayer printed circuit board is comprised only by the single-sided conductor pattern films 10 and 11. FIG. Therefore, the manufacturing equipment and the manufacturing process can be simplified, and the manufacturing cost can be reduced. In addition, since the electrodes of the conductor pattern 2 are formed on both the upper and lower surfaces of the printed board, high-density mounting or downsizing of the printed board can be achieved. In addition, the conductor pattern 2 may be laminated so that only one surface of the laminate 20 is exposed.

  After the laminating process is performed, a heating / pressurizing process is performed in which the laminated body 20 is heated and pressurized from both the upper and lower surfaces by a heating press. And the multilayer printed circuit board 30 shown by FIG.1 (d) is formed through the cooling process after a heat press. The printed circuit board 30 is managed so as to be cooled with a predetermined temperature gradient by a heating press.

  Then, on the formed printed circuit board 30, the positioning mark 3 is optically recognized, and electrical inspection, component mounting, and the like are performed using the recognized positioning mark 3 as a reference position.

  Here, binarization by image processing is generally used as an optical means. Also in the present embodiment, the positioning mark 3 and its peripheral part are binarized to 256 gradations by image processing, and the positioning mark 3 is recognized. However, in the case of an optical recognition method such as image processing, the difference in intensity of reflected light between the positioning mark 3 and the surrounding portion (depending on the material, color, etc. used for the positioning mark 3 and the surrounding portion (resin film 1) ( (Difference in reflectance) may be small. In this case, the contrast between the positioning mark 3 and the peripheral portion becomes unclear, and the positioning mark 3 cannot be recognized with high accuracy.

  Therefore, in the present embodiment, a roughening process is performed on the printed circuit board 30 formed by heating and pressurizing by using the roughening means to roughen the periphery of the positioning mark 3. The roughening process will be described below with reference to FIGS. 2 and 3A, 3B. FIG. 2 is a cross-sectional view showing the roughening process. FIG. 3A and FIG. 3B are plan views of the positioning mark 3 and the surrounding portion showing an example of the irradiation path of the laser beam which is a roughening means. The peripheral portion refers to a portion (configured by the resin film 1) surrounding the positioning mark 3 on the printed circuit board 30, and the range thereof is not particularly limited, but the positioning mark in optical recognition (image recognition). It is preferable to set the size effective for recognizing 3 (with respect to the positioning mark 3) as the range. For example, a 1 mm square range in which the φ 0.5 mm positioning mark 3 is centered may be used as the peripheral portion.

  As shown in FIG. 2, in this embodiment, the peripheral portion 31 is roughened by irradiating laser light 40 as the roughening means.

  Here, the laser beam 40 may be any laser beam that can roughen the peripheral portion 31 and may be irradiated only to the peripheral portion 31. However, the position at which the laser beam 40 is irradiated on the printed circuit board 30 is determined using, for example, the corner of the printed circuit board 30 or the distance on the drawing from the positioning pin as a reference value. Accordingly, the reference value and the actual printed board 30 for each printed board 30 due to error factors such as dimensional variation of each resin film 1, positional deviation in the laminating process, and warping of the printed board 30 during cooling after heating and pressurization. Variation occurs in the difference from the actual measurement value at. In this case, even if the reference value is set so that only the peripheral portion 31 is irradiated with the laser light 40, due to the error, the region where the peripheral portion 31 is not irradiated with the laser light 40 (particularly in the boundary region with the positioning mark 3). Or the positioning mark 3 may be roughened.

  However, if the laser beam 40 having a higher absorptance at the peripheral portion 31 than the positioning mark 3 is appropriately selected according to the material of the positioning mark 3 and the peripheral portion 31, the positioning mark 3 is irradiated together with the peripheral portion 31. However, the peripheral portion 31 can be selectively roughened. Further, if the laser light 40 is capable of such selective roughening, not only the peripheral portion 31 but also the positioning mark 3 so that the laser light 40 is irradiated to the entire peripheral portion 31 even if the error occurs. Also, the laser beam 40 can be irradiated.

  In this embodiment, a carbon dioxide laser or an Nd: YAG laser is used. Since both lasers have a higher absorptance at the peripheral portion 31 (LCP) than the positioning mark 3 (copper), the laser settings such as the output can be set so that the peripheral portion 31 can be roughened (for example, an oscillation frequency of 2000 Hz in a carbon dioxide laser) The peripheral portion 31 can be selectively roughened by irradiating with a spot diameter of φ200 μm and an output of 0.6 mJ / p. That is, the reflectance of the peripheral portion 31 is reduced and the difference in intensity of reflected light between the positioning mark 3 and the peripheral portion 31 is increased, so that the recognition accuracy of the positioning mark 3 is improved.

  At that time, the irradiation path of the laser beam 40 is not particularly limited. For example, as shown in FIG. 3A, the laser beam 40 may be scanned from one end of the peripheral portion 31 to the other opposite end so that the entire positioning mark 3 is irradiated with the peripheral portion 31. . Further, as shown in FIG. 3B, even when the laser beam 40 is scanned in the direction along the outer periphery of the positioning mark 3 so that the laser beam 41 is irradiated to a part of the positioning mark 3 together with the peripheral portion 31. good. In FIGS. 3A and 3B, the irradiation path of the laser beam 40 is indicated by a chain line arrow in the drawing.

  Then, the resin film 1 in the peripheral portion 31 is burned out by the irradiation of the laser light 40, and the peripheral portion 31 in the printed circuit board 30 is applied to another part (substrate surface) of the printed circuit board 30 as shown in FIG. In contrast to the concave shape, as shown in FIG. 4B, the bottom surface of the peripheral portion 31 having the concave shape is roughened. 4A and 4B are diagrams for explaining the state after the roughening process, in which FIG. 4A is a cross-sectional view of the printed circuit board 30, and FIG. 4B is an enlarged cross-sectional view of a portion surrounded by a broken line in FIG. is there.

  As described above, the peripheral portion 31 can be roughened by irradiating the peripheral portion 31 (and the positioning mark 3) of the printed circuit board 30 with the laser light 40 as the roughening means. Therefore, since the reflectance of the surrounding part 31 is reduced by roughening, the intensity difference of the reflected light of the positioning mark 3 and the surrounding part 31 becomes large. That is, since the contrast between the positioning mark 3 and the peripheral portion 31 becomes clear, the positioning mark 3 can be recognized optically with high accuracy.

  Further, in manufacturing the printed circuit board 30, there is a step of performing product number marking on the surface of the printed circuit board 30. This product number marking is usually performed using a laser marker (for example, an Nd: YAG laser). Therefore, when the roughening process is performed by the laser beam 40, the same process as the part number marking process can be performed. In this case, the manufacturing process can be simplified, and it is not necessary to prepare equipment separately, so that the manufacturing cost can be reduced.

  In the present embodiment, the positioning mark 3 is formed in an area on the printed circuit board 30 that does not provide an electrical connection function. When the peripheral portion 31 is roughened by the laser light 40, the circuit portion (including the conductor pattern 2 and the interlayer connection material 5) that provides an electrical contact function in the vicinity of the positioning mark 3 or in the lower layer is provided. The part may be affected by the heat of the laser beam 40. Therefore, as shown in FIG. 2, it is preferable that the positioning mark 3 is provided in a region that does not provide an electrical connection function in the printed circuit board 30.

  Moreover, in this Embodiment, the roughening process showed the example implemented after a heating and pressurizing process. However, it may be performed after the mark forming process for forming the positioning mark 3 and before the heating / pressurizing process. However, when the roughening step is performed before the heating / pressurizing step, the roughening surface of the peripheral portion 31 may be crushed by the hot press plate during heating / pressurization, and the effect of the roughening may be reduced. Therefore, in order to exhibit the effect of roughening, it is better to carry out the roughening step after the heating / pressurizing step.

  Moreover, in this embodiment, the example which irradiates the laser beam 40 as a roughening means and roughens the surrounding part 31 was shown. However, the roughening means is not limited to the laser beam 40. Any roughing means that can selectively roughen the peripheral portion 31 and, as a result, reduce the reflectance of the peripheral portion 31 and increase the intensity difference of reflected light between the positioning mark 3 and the peripheral portion 31 is applicable. Is possible. For example, the roughening process may be performed by mechanical processing, plasma irradiation, chemical solution application, or the like in which there is a processing difference between the positioning mark 3 and the peripheral portion 31.

  The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and various modifications can be made.

  In this embodiment mode, an example is shown in which a liquid crystal polymer (LCP) that is a thermoplastic resin is used as an insulating substrate. However, other than that, a thermoplastic resin film composed of 65 to 35% of polyetheretherketone (PEEK) and 35 to 65% of polyetherimide (PEI) may be used, or PEEK and PEI are used alone. May be. Furthermore, polyethersulfone (PES), polyphenylene ether (PPE), polyethylene naphthalate (PEN), styrenic resin having a syndiotactic structure, etc. may be used alone, or each of them including PEEK and PEI. Any one of them may be mixed and used. In short, in the heating / pressurizing step, resin films can be bonded to each other, and any resin film having heat resistance necessary for soldering or the like, which is a subsequent step, can be suitably used.

  In this embodiment, an example in which the positioning mark is made of copper and the article is made of a resin film of a printed board is shown. However, the material structure is not limited to this example. According to a predetermined roughening means, a positioning mark and an article having a difference in workability can be selected and combined, or an article can be selectively roughened with respect to a predetermined combination of positioning mark and article. A roughening means may be selected and used. For example, the article (peripheral portion) may be selectively roughened by irradiating a laser beam onto glass as a positioning mark and a thermoplastic resin as an article.

  Moreover, in this Embodiment, the example which laminates | stacks the 1st and 2nd single-sided conductor pattern film in which the conductor pattern was formed in the single side | surface was shown as a resin film. However, other than that, the core substrate is used, and the first single-sided conductor pattern film and / or the second single-sided conductor pattern film are arranged on the top and bottom of the core substrate, or the conductor pattern is formed on both sides instead of the core substrate. A processed resin film made of a resin may be used. Moreover, in the resin film laminated | stacked, you may include the resin film which does not have a conductor pattern on the surface.

  In the present embodiment, an example of a printing method in which a conductive paste is filled in a via hole is shown. However, electroless plating, electrolytic plating, vapor deposition, metal coating, or the like may be used.

  Further, in the present embodiment, a bottomed via hole is formed, and the bottomed via hole is filled with a conductive paste which is an interlayer connection material. A through hole is formed at the time of forming the via hole, and the interlayer connection material is formed in the through via hole. May be used.

  Moreover, in this Embodiment, although the example which laminates | stacks a total of four 1st and 2nd single-sided conductor pattern films was shown, it cannot be overemphasized that the number of layers is not limited.

  Moreover, in this Embodiment, the example in which a conductor pattern is also formed in the resin film which has a positioning mark was shown. However, only the positioning mark may be formed on the resin film having the positioning mark.

It is sectional drawing according to process which shows the manufacturing method of the printed circuit board which has the positioning mark in the 1st Embodiment of this invention, (a) is 1st single-sided conductor pattern film formation, (b) is 2nd single-sided conductor pattern. Film formation, (c) is the lamination process, (d) is after the heating and pressurizing process It is sectional drawing for demonstrating a roughening process. (A), (b) is the top view of the positioning mark which shows an example of the irradiation path | route of a laser beam, and a surrounding part. It is a figure which shows the state after a roughening process, (a) is sectional drawing of a printed circuit board, (b) is an expanded sectional view of the part enclosed with the broken line of (a).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Resin film 2 ... Conductor pattern 3 ... Positioning mark 30 ... Printed circuit board 31 ... Peripheral part 40 ... Laser beam

Claims (4)

A pattern forming step of forming a conductor pattern on at least one surface of a resin film made of a thermoplastic resin as an insulating substrate;
A mark forming step of forming a positioning mark indicating a reference position at a predetermined position on the surface of the resin film;
A laminating step of laminating a plurality of resin films including the resin film having the conductor pattern and the resin film having the positioning mark so that the positioning mark becomes a surface layer, and forming a laminate ,
By applying pressure while heating the laminated body using a hot press plate, the resin films are bonded to each other to form the insulating substrate in which the conductor patterns are arranged in multiple layers, and one surface is the surface of the insulating substrate A heating / pressurizing step of burying the positioning mark in the insulating substrate so as to be flush with
After the heating / pressurizing step, at least a part of the positioning mark exposed from the insulating substrate and the surrounding area are irradiated with laser light having a higher absorption rate in the peripheral portion of the insulating substrate surrounding the positioning mark than the positioning mark. And a roughening step of roughening the peripheral portion by directly irradiating the portion. The method for manufacturing a printed circuit board according to claim 1, wherein the mark forming step is performed in the same step as the pattern forming step. The printed circuit board manufacturing method according to claim 1, wherein the positioning mark is formed in a region that does not provide an electrical connection function in the printed circuit board. The printed circuit board manufacturing method according to claim 1, wherein the roughening process is performed in the same process as the product number marking on the surface of the printed circuit board.

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