JP4838034B2 - Printed wiring board and manufacturing method thereof - Google Patents

Description

  The present invention relates to a printed wiring board having a shield conductive layer on one surface of an insulating substrate and a method for manufacturing the printed wiring board.

  When a microstrip transmission line is configured on a printed wiring board used as wiring in an electronic device, a conductive line portion is provided on one surface of the insulating substrate and a conductive layer for shielding is provided on the other surface (for example, , See Patent Document 1). The structure of this type of printed wiring board and the manufacturing method thereof will be described.

  As shown in FIG. 8, a conventional printed circuit board 100 </ b> A includes an insulating substrate 101, conductive line portions 102 a and 102 b that are provided on one surface of the insulating substrate 101, and include signal lines and ground lines, and an insulating substrate 101. Provided in the through hole 104 provided on the other surface and penetrating through the shield conductive layer 103 formed of a copper foil layer, the conductive line portion 102b serving as the ground line, the insulating substrate 101, and the shield conductive layer 103. And an interlayer conductive portion 105 formed by metal plating.

  Next, a method for manufacturing the printed wiring board 100A will be described. As shown in FIG. 9A, a double-sided copper-clad plate 112 in which copper foil layers 110 and 111 are attached to both sides of an insulating substrate 101 is prepared. First, as shown in FIG. 9B, in the double-sided copper-clad plate 112, a through hole 104 is opened with a drill at a position that finally becomes the conductive line portion 102b of the ground line. Next, as shown in FIG. 9C, metal conduction is applied in the through hole 104 to form the interlayer conductive portion 105. Next, as shown in FIG. 9D, the surface of the copper foil layer 110 on one side, and finally the surface to be the conductive line portions 102a and 102b, and the surface of the copper foil layer 111 on the other side A resist layer 113 is formed on each of the regions. Next, as shown in FIG. 9E, etching is performed using the resist layer 113 as a mask, and conductive line portions 102a and 102b to be signal lines and ground lines are formed by etching the copper foil layer 110 on one surface. To do. Finally, the resist films 113 on both sides are peeled off. The copper foil layer 111 on the other surface is not etched at all and becomes the conductive layer 103 for shielding.

  As another conventional printed wiring board 100B, as shown in FIG. 10, an insulating substrate 101, conductive line portions 102a and 102b which are provided on one surface of the insulating substrate 101 and are composed of signal lines and ground lines, The insulating cover layer 114 covering the conductive line portions 102a and 102b, the shield conductive layer 103 made of a conductive material bonded to the surface of the insulating cover layer 114, the conductive line portion 102b serving as a ground line, and the shield The conductive layer 103 is electrically connected to each other, and an interlayer conductive portion 116 formed of a conductive paste filled in the through hole 115 of the insulating cover layer 114 is formed.

  Next, a method for manufacturing the printed wiring board 100B will be described with reference to FIG. As shown in FIG. 11A, a single-sided copper-clad plate 121 in which a copper foil layer 120 is attached to one side of an insulating substrate 101 is prepared. First, as shown in FIG. 11 (b), a resist layer 113 is patterned on the surface of the copper foil layer 120 and at places where the conductive line portions 102a and 102b are finally formed. Next, as shown in FIG. 11C, etching is performed using the resist layer 113 as a mask, and the copper foil layer 120 is etched to form conductive line portions 102a and 102b that become signal lines and ground lines. Next, as shown in FIG. 11D, the resist layer 113 is peeled off. Next, as shown in FIG. 11E, an insulating cover layer 114 is formed so as to cover the conductive line portions 102a and 102b. Note that a through hole 115 is formed in the insulating cover layer 114 in advance, and the conductive line portion 102 b serving as a ground line is exposed through the through hole 115. Next, as shown in FIG. 11F, a conductive paste is filled into the through hole 115, and an interlayer conductive portion 116 is formed with the conductive paste. Next, as shown in FIG. 10, a shielding conductive layer 103 made of a conductive material is bonded to the surface of the insulating cover layer 114.

A technique for forming the interlayer conductive portion 116 by filling the through hole 115 with a conductive paste is disclosed in Patent Document 2, for example.
Japanese Patent No. 3617684 JP 2001-244609 A

  However, in the former conventional example, since the expensive double-sided copper-clad plate 112 is used, the material cost is high. In addition, when metal plating is performed, the metal plating is deposited not only in the through hole 104 but also on the surfaces of the copper foil layers 110 and 111. When the metal plating is deposited on the copper foil layers 110 and 111, the conductive line portions 102a and 102b become thick, so that the etching accuracy is deteriorated and the impedance control of the microstrip transmission line becomes difficult. Therefore, when performing the metal plating process, it is necessary to mask portions other than the through hole 104, which causes an increase in the number of man-hours and an increase in manufacturing cost accompanying the increase in the number of man-hours. As described above, the former conventional example has a problem that it takes man-hours and is expensive.

  In the latter conventional example, a single-sided copper-clad plate 121 is used, which is cheaper than when the double-sided copper-clad plate 112 is used. However, since a conductive material as the shielding conductive layer 103 is required, the material cost as a whole is reduced. Not cheap. Further, since a process for printing the conductive paste into the through hole 115 and a process for bonding the shielding conductive material 103 are necessary, the number of man-hours for manufacturing increases as in the former case. For this reason, the latter conventional example also has a problem that it takes man-hours and is expensive.

  Therefore, an object of the present invention is to solve such a problem, a printed wiring board capable of reducing the number of man-hours at the time of manufacture, and reducing both the material cost and the manufacturing cost, and its It is to provide a manufacturing method.

A printed wiring board according to the present invention is provided between an insulating substrate, a plurality of signal lines provided in parallel on one surface of the insulating substrate, and one surface of the insulating substrate, and between the plurality of signal lines. A ground line, an insulating cover layer covering the plurality of signal lines and the ground line by exposing the plurality of signal lines and the ground line located on a terminal connection side of the insulating substrate, and the insulating cover layer A conductive layer for shielding formed by a conductive paste, and the insulating cover layer is cut out in a U shape along the longitudinal direction of the ground line from the terminal connection side, and the ground the width in the direction perpendicular to the longitudinal direction of the line is larger than a width of the ground line, between one and a signal line adjacent to the ground line, and the other signal line adjacent to the ground line Have a smaller cutout portion, the formed by the notch in the conductive paste, and summarized in that with an interlayer conductive portion for conducting and said shielding conductive layer and the ground line.

In the method for manufacturing a printed wiring board according to the present invention, a plurality of signal lines are formed in parallel by performing etching on the copper foil layer of a single-sided copper-clad plate in which a copper foil layer is attached to an insulating substrate. Forming a ground line between the plurality of signal lines, exposing the plurality of signal lines and the ground line located on the terminal connection side of the insulating substrate, and covering the plurality of signal lines and the ground line. While providing an insulating cover layer, the insulating cover layer is notched in a U shape along the longitudinal direction of the ground line from the terminal connection side, the width in the direction orthogonal to the longitudinal direction of the ground line, greater than the width of the ground line, while the signal line adjacent to the ground line, forming a spacing smaller notch of the other signal line adjacent to the ground line, the insulating cover layer, A step of forming a conductive layer for shielding with an electrically conductive paste, and a step of forming an interlayer conductive portion for electrically connecting the ground line and the conductive layer for shielding with a conductive paste in the cutout portion. Is the gist.
In the method for manufacturing a printed wiring board according to the present invention, it is preferable that the step of forming the shielding conductive layer and the step of forming the interlayer conductive portion are performed in the same step by conductive paste printing.

  According to this invention, while being able to manufacture using an inexpensive single-sided copper-clad board, since the shielding conductive layer is formed of an inexpensive conductive paste, the material cost can be reduced. In addition, when printing the conductive paste, a masking step as in the case of performing metal plating is unnecessary, and in addition, since the interlayer conductive portion and the conductive layer for shielding can be formed by a single conductive paste printing, Processes can be reduced. From the above, man-hours during manufacturing can be reduced, and both material costs and manufacturing costs can be reduced.

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

(First embodiment)
1 and 2 show a first embodiment of the present invention. FIG. 1 is a cross-sectional view of a printed wiring board, and FIGS. 2A to 2E are cross-sectional views of manufacturing processes of the printed wiring board.

  As shown in FIG. 1, a printed wiring board 1A includes an insulating substrate 2, conductive line portions 3a and 3b, which are provided on one surface of the insulating substrate 2, and are composed of signal lines and ground lines, and conductive line portions 3a and 3b. An insulating cover layer 4 covering the upper surface, a shield conductive layer 5 provided on one surface of the insulating cover layer 4 and formed of a conductive paste, a conductive line portion 3b serving as a ground line, and a shield conductive layer 5 And an interlayer conductive portion 6 formed of a conductive paste.

  Next, a method for manufacturing the printed wiring board 1A will be described. As shown in FIG. 2A, a single-sided copper-clad plate 11 in which a copper foil layer 10 is attached to one side of an insulating substrate 2 is used. First, as shown in FIG. 2 (b), a resist film 12 is formed on the surface of the copper foil layer 10 and at places where the conductive line portions 3a and 3b are finally formed. Next, as shown in FIG. 2C, etching is performed and the copper foil layer 10 is etched to form the conductive line portions 3a and 3b that become signal lines and ground lines. Next, as shown in FIG. 2D, the resist film 12 is peeled off. Next, as shown in FIG. 2E, the insulating cover layer 4 is formed so as to cover the conductive line portions 3a and 3b. At this time, the insulating cover layer 4 is formed so as to open the through holes 13 which are interlayer conductive spaces. The through-hole 13 exposes the conductive line portion 3b serving as a ground line. Next, the conductive paste is printed in the through hole 13 and on the surface of the insulating cover layer 4. Then, as shown in FIG. 1, the interlayer conductive portion 6 is formed by the conductive paste filled in the through hole 13, and the shield conductive layer 5 is formed by the conductive paste printed on the surface of the insulating cover layer 4. Is done. Thus, the manufacture of the printed wiring board 1A is completed.

  In addition, when setting it as 1 A of printed wiring boards excellent in heat resistance, a protective resist layer (not shown) is formed after conductive paste printing.

  As described above, according to the printed wiring board 1 </ b> A and the manufacturing method thereof according to the first embodiment, the shield conductive layer 5 can be formed with an inexpensive conductive paste while being manufactured using the inexpensive single-sided copper-clad plate 11. Therefore, material costs can be kept low. In addition, when printing the conductive paste, a masking step as in the case of performing metal plating is unnecessary, and in addition, the interlayer conductive portion 6 and the shield conductive layer 5 can be formed by a single conductive paste printing. Therefore, the process can be reduced. From the above, man-hours during manufacturing can be reduced, and both material costs and manufacturing costs can be reduced.

  In the first embodiment, the interlayer conductive portion 6 is formed using the through hole 13 of the insulating cover layer 4, so that a desired position and number of interlayer conductive portions 6 can be formed.

(Second Embodiment)
3 and 4 show a second embodiment of the present invention. 3 is a cross-sectional view of the printed wiring board, and FIGS. 4A to 4E are cross-sectional views of manufacturing processes of the printed wiring board.

  As shown in FIG. 3, the printed wiring board 1B includes an insulating substrate 2, conductive line portions 3a and 3b, which are provided on one surface of the insulating substrate 2, and are composed of signal lines and ground lines, and conductive line portions 3a and 3b. An insulating cover layer 4 covering the upper surface; a shield conductive layer 5 provided on one surface of the insulating substrate 2 and formed of a conductive paste; a conductive line portion 3b serving as a ground line; and a shield conductive layer 5; And an interlayer conductive portion 6 formed of a conductive paste.

  Next, a method for manufacturing the printed wiring board 1B will be described. As shown in FIG. 4A, a single-sided copper-clad plate 11 in which a copper foil layer 10 is attached to one side of an insulating substrate 2 is used. First, as shown in FIG. 4B, a resist film 12 is formed on the surface of the copper foil layer 10 and at places where the conductive line portions 3a and 3b are finally formed. Next, as shown in FIG. 4C, etching is performed, and the copper foil layer 10 is etched to form the conductive line portions 3a and 3b serving as signal lines and ground lines. Next, as shown in FIG. 4D, the resist film 12 is peeled off. Next, as shown in FIG. 4E, the insulating cover layer 4 is formed so as to cover the conductive line portions 3a and 3b. Further, a through hole 13 which is an interlayer conduction space is opened in the insulating substrate 2 by a laser. The through-hole 13 exposes the conductive line portion 3b serving as a ground line. Next, the conductive paste is printed in the through hole 13 and on the surface of the insulating substrate 2. Then, as shown in FIG. 3, the interlayer conductive portion 6 is formed by the conductive paste filled in the through hole 13, and the shield conductive layer 5 is formed by the conductive paste printed on the surface of the insulating substrate 2. The This completes the production of the printed wiring board 1B.

  In addition, when setting it as the printed wiring board 1B excellent in heat resistance, a protective resist layer (not shown) is formed after conductive paste printing.

  That is, in the printed wiring board 1A of the first embodiment, the shield conductive layer 5 is formed on the surface of the insulating cover layer 4, but the printed wiring board 1B of the second embodiment is The difference is that the shield conductive layer 5 is formed on the surface.

  Also in the second embodiment, for the same reason as in the first embodiment, the number of man-hours for manufacturing can be reduced, and both the material cost and the manufacturing cost can be reduced.

(Third embodiment)
5 to 7 show a third embodiment of the present invention. 5 is a plan view of the printed wiring board, FIG. 6 is a sectional view taken along line AA in FIG. 5, and FIG. 7 is a sectional view taken along line BB in FIG.

  As shown in FIGS. 5 to 7, the printed wiring board 1 </ b> C according to the third embodiment is different from the printed wiring board 1 </ b> A according to the first embodiment in the structure of the interlayer conductive portion 20. . That is, the insulating cover layer 4 does not completely cover the surface of the insulating substrate 2, and the conductive line portions 3a and 3b of the signal line and the ground line are exposed at the position of the terminal connection portion 21. The insulating cover 4 in the vicinity of the terminal connection portion 21 is formed with a notch 22 that is an interlayer conductive space that further exposes the conductive line portion 3b of the ground line. An interlayer conductive portion 20 is formed by printing a conductive paste in the notch 22. In the conductive paste printing step, the interlayer conductive portion 20 and the shield conductive portion 5 are formed at the same time as in the first embodiment.

  A reinforcing plate 23 is bonded to the back surface of the connection terminal portion 21 of the insulating substrate 2. The strength of the printed wiring board 1 </ b> C is increased by the reinforcing plate 23.

  Since other configurations are the same as those of the first embodiment, the same components in the drawings are denoted by the same reference numerals, and the description thereof is omitted.

  Also in the third embodiment, for the same reason as in the first embodiment, the number of man-hours during manufacturing can be reduced, and both the material cost and the manufacturing cost can be reduced.

  In the third embodiment, the interlayer conductive portion 20 is formed using the cutout portion 22 of the insulating cover layer 4, so that a through hole is formed as in the first and second embodiments. Since no process is required, the man-hours are further reduced.

  The printed wiring boards 1A to 1C according to the present invention in which the interlayer conductive portions 6 and 20 and the shield conductive layer 5 are both formed of a conductive paste, and other conventional examples in which the shield conductive layer is formed of a copper foil. The impedance of the microstrip transmission line with the printed wiring board was measured. For a single-ended transmission signal, the current return path is the shield conductive layer (ground surface) 5, so that the shield conductive layer 5 made of conductive paste has a direct current resistance value compared to the shield conductive layer made of copper foil. Get higher. Therefore, in the printed wiring boards 1A to 1C of the present invention, the characteristic impedance is increased as the transmission line length is increased as compared with the other conventional examples. However, the differential transmission signal is hardly affected by the DC resistance value of the shield conductive layer 5 because the current return path is a complementary input / output. Therefore, good impedance characteristics were obtained. As mentioned above, in this invention, when transmitting a differential signal, the transmission characteristic similar to the case where it produces using a double-sided copper clad board is acquired.

It is sectional drawing of the printed wiring board concerning 1st Embodiment. (A)-(e) is sectional drawing of each manufacturing process of the printed wiring board concerning 1st Embodiment. It is sectional drawing of the printed wiring board concerning 2nd Embodiment. (A)-(e) is sectional drawing of each manufacturing process of the printed wiring board concerning 2nd Embodiment. It is a top view of the printed wiring board concerning a 3rd embodiment. It is the sectional view on the AA line of FIG. FIG. 6 is a sectional view taken along line B-B in FIG. 5. It is sectional drawing of the printed wiring board of a prior art example. (A)-(e) is sectional drawing of each manufacturing process of the printed wiring board of a prior art example. It is sectional drawing of the printed wiring board of another prior art example. (A)-(f) is sectional drawing of each manufacturing process of the printed wiring board of another prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1A, 1B, 1C Printed wiring board 2 Insulation board 3a, 3b Conductive line part 4 Insulation cover layer 5 Shielding conductive layer 6 Interlayer conduction part 10 Copper foil layer 11 Single-sided copper-clad board 13 Through hole (interlayer conduction space)
20 Interlayer conductive part 22 Notch (interlayer conductive space)

Claims (3)

An insulating substrate;
A plurality of signal lines provided in parallel on one surface of the insulating substrate;
Provided on one surface of the insulating substrate, and a ground line provided between the plurality of signal lines,
An insulating cover layer that exposes the plurality of signal lines and the ground lines by exposing the plurality of signal lines and the ground lines located on the terminal connection side of the insulating substrate;
A shielding conductive layer provided on the insulating cover layer and formed of a conductive paste;
With
The insulating cover layer is notched in a U shape along the longitudinal direction of the ground line from the terminal connection side, and the width in the direction orthogonal to the longitudinal direction of the ground line is larger than the width of the ground line. large, a one and a signal line adjacent to the ground line, an interval smaller notch of the other signal line adjacent to the ground line,
A printed wiring board, comprising: an interlayer conductive portion that is formed of a conductive paste in the cutout portion and that connects the ground line and the conductive layer for shielding. Etching the copper foil layer of a single-sided copper-clad plate with a copper foil layer attached to an insulating substrate to form a plurality of signal lines in parallel and forming a ground line between the plurality of signal lines When,
Exposing the plurality of signal lines and the ground line located on the terminal connection side of the insulating substrate to provide an insulating cover layer covering the plurality of signal lines and the ground line, and in the insulating cover layer, A U-shaped notch is formed along the longitudinal direction of the ground line from the terminal connection side, and the width in the direction orthogonal to the longitudinal direction of the ground line is larger than the width of the ground line and is adjacent to the ground line. and one of the signal lines, forming a spacing smaller notch of the other signal line adjacent to the ground line,
Forming a shielding conductive layer on the insulating cover layer with a conductive paste;
Forming a conductive layer in the cutout portion with an electrically conductive paste to connect the ground line and the conductive layer for shielding;
A method of manufacturing a printed wiring board, comprising: It is a manufacturing method of the printed wiring board according to claim 2 ,
The method of manufacturing a printed wiring board, wherein the step of forming the conductive layer for shielding and the step of forming the interlayer conductive portion are performed in the same step by conductive paste printing.

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