JP2008192993A - Method of manufacturing printed board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a printed board with which an electrolytic deposition process can be suitably performed on specific terminal electrodes while suppressing damage and generation of stubs in the specific terminal electrodes. <P>SOLUTION: The method includes; a pattern forming step for forming metallic terminal electrodes 16, 18 which extend toward an edge 12a of a laminated substrate 12, metallic wiring lines 104 for electrolytic deposition, wherein the wiring lines 104 start from the terminal electrodes 16 and reach to the edge 12a of the substrate 12, and metallic wiring patterns 26, 28 which extend, respectively from the terminal electrodes 16, 18, toward inside of the substrate 12, on the substrate 12; a short-circuiting step for short-circuiting the wiring patterns 26, 28 with conductive resin 106; an electroplating step for performing an electrolytic deposition process on the terminal electrodes 16, 18 by feeding a current to the terminal electrodes 16 via the wiring lines 104 for electrolytic deposition, and furthermore, feeding a current to the terminal electrodes 18 via the conductive resin 106; and a removing step for removing the conductive resin 106. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a printed circuit board.

  Some printed circuit boards have a card edge connector attached to a socket provided on another printed circuit board or the like. The card edge connector is provided with a plurality of terminal electrodes extending toward the edge of the printed circuit board. These terminal electrodes are electrically connected to terminal electrodes (socket electrodes) in the socket when the card edge connector is inserted into the socket.

The terminal electrode of the card edge connector is subjected to electrolytic plating such as Ni / Au for the purpose of reducing electrical resistance with the socket electrode and preventing rust. For this reason, wiring for supplying a current during electrolytic plating is required for the terminal electrode, but this electrolytic plating wiring is often removed after electrolytic plating. In general, the substrate surface excluding the electrolytic plating wiring is masked, and only the electrolytic plating wiring is removed by etching. Further, Patent Document 1 discloses a technique for invalidating a wiring by forming a through hole in a substrate using a drill and dividing the electrolytic plating wiring by the through hole.
US Patent Application Publication No. 2006/0118331

  For example, in the case of a printed circuit board used for high-speed communication, the terminal electrode of the card edge connector includes one through which a high-frequency signal passes. In such a case, the electrolytic plating wiring becomes a stub for the high-frequency signal wiring, and is desirably removed completely. However, with the method described in Patent Document 1, it is difficult to completely remove the electrolytic plating wiring from the limit of machining accuracy. Further, in the method of removing only the electroplating wiring by etching, if the masking is insufficient, the terminal electrode for high frequency signal may be damaged.

  The present invention has been made in view of the above-described problems, and is a printed circuit board that can suitably perform electrolytic plating on a specific terminal electrode while suppressing damage and occurrence of a stub in the specific terminal electrode. An object is to provide a manufacturing method.

  In order to solve the above-described problem, a printed circuit board manufacturing method according to the present invention includes a first and second terminal electrodes on a substrate, wiring for electrolytic plating reaching the edge of the substrate from the first terminal electrodes, A pattern forming step for forming first and second wiring patterns extending from the first and second terminal electrodes, a short-circuiting step for short-circuiting the first and second wiring patterns with a conductive resin, And a plating step of performing an electrolytic plating process on the second terminal electrode, and a removing step of removing the conductive resin.

  In this method of manufacturing a printed circuit board, a conductive resin connected to the first terminal electrode is used as a power supply means for electrolytic plating for the second terminal electrode. Although the conductive resin is dissolved in an organic solvent or the like, the first and second terminal electrodes and the first and second wiring patterns are not removed at all by the organic solvent. Thus, since the conductive resin can be selectively removed with respect to the first and second terminal electrodes and the first and second wiring patterns, the terminal electrodes and the wiring pattern are not damaged. The second terminal electrode can be completely removed without generating a stub. That is, according to the above-described printed circuit board manufacturing method, it is possible to perform the electrolytic plating process on the specific terminal electrode while suppressing the damage on the specific terminal electrode (second terminal electrode) and the generation of the stub.

  Further, the printed circuit board manufacturing method may be characterized in that after the pattern forming step, the solder resist is formed so that the portions where the conductive resin is provided in the first and second wiring patterns are exposed. Thereby, the mounting operation of the conductive resin on the first and second wiring patterns is facilitated. In this case, it is preferable that the part in the second wiring pattern is a pad part on which an electronic component is mounted.

  The printed circuit board manufacturing method may be characterized in that the first wiring pattern has a portion branched toward a portion of the second wiring pattern on which the conductive resin is provided. Thereby, the space | interval of 1st and 2nd wiring patterns narrows, and the short circuit by conductive resin can be performed easily.

  The printed circuit board manufacturing method may be characterized in that the conductive resin includes an acrylic resin, and the conductive resin is removed by an organic solvent in the removing step. Thereby, a conductive resin can be removed suitably in a removal process.

  According to the method for manufacturing a printed circuit board according to the present invention, it is possible to suitably perform an electrolytic plating process on a specific terminal electrode while suppressing the occurrence of damage and stubs on the specific terminal electrode.

  Embodiments of a method for manufacturing a printed circuit board according to the present invention will be described below in detail with reference to the accompanying drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 1 is a plan view showing an embodiment of a printed board manufactured by the manufacturing method according to the present embodiment. 2 is an enlarged perspective view showing a portion A of the printed board shown in FIG. A printed circuit board 10 shown in FIGS. 1 and 2 is a heat-resistant glass-based epoxy resin laminated substrate (so-called FR-4, hereinafter simply referred to as a laminated substrate) 12, and is provided along an edge 12 a of the laminated substrate 12. The card edge connector portion 14 is provided.

  The card edge connector portion 14 has a plurality of terminal electrodes 16, 18, and 20 spaced apart from each other. These terminal electrodes 16, 18, and 20 are arranged side by side along the edge 12a of the laminated substrate 12, and extend toward the edge 12a (with the direction intersecting the edge 12a as the longitudinal direction). Yes. The card edge connector portion 14 is used by being inserted into a socket provided on another printed circuit board (not shown). The socket is provided with terminal electrodes corresponding to the terminal electrodes 16, 18, and 20, that is, socket electrodes. When the card edge connector portion 14 is inserted into the socket, each of the terminal electrodes 16, 18, and 20 comes into contact with the socket electrode, and is electrically connected. The terminal electrodes 16, 18, and 20 are made of metal, and for example, nickel plating and gold plating are performed on a metal such as copper.

  The terminal electrode 20 is wired to a circuit mounted in the central portion of the multilayer substrate 12, but in FIGS. 1 and 2, the diagrams are simplified and this wiring is not shown. In addition, in other portions, wiring other than portions necessary for describing the gist of the present invention may be omitted.

  Among the plurality of terminal electrodes 16, 18, and 20, the terminal electrode 16 is a ground (reference potential) electrode and is the first electrode in the present embodiment. The distance between the terminal electrode 16 and the edge 12a is smaller than that of the other terminal electrodes 18 and 20 so that the terminal edge 16 contacts the socket electrode as soon as the card edge connector portion 14 is inserted into the socket. The terminal electrode 18 is a high-frequency signal electrode, and is the second electrode in the present embodiment. The two terminal electrodes 18 are provided as a pair, and are arranged between the two ground terminal electrodes 16 in order to reduce noise to the high frequency signal. The terminal electrode 20 is an electrode for power supply to the printed circuit board 10, a control signal, a monitor signal, or the like. As shown in FIG. 2, the plating wiring 22 connected to each of the terminal electrodes 16 and 20 is formed in the inner layer of the multilayer substrate 12 through the through hole 24.

  Further, the printed circuit board 10 is electrically connected to the terminal electrode 16 and extends to the inside of the multilayer substrate 12, and the wiring pattern (first wiring pattern) 26 is electrically connected to the terminal electrode 18 to the inside of the multilayer substrate 12. It further has an extended wiring pattern (second wiring pattern) 28. The wiring patterns 26 and 28 are made of metal, and are formed of the same material (for example, copper foil or copper foil plated) except for the plated portions of the terminal electrodes 16, 18 and 20. . In the present embodiment, since the two terminal electrodes 18 are disposed between the two terminal electrodes 16, the wiring pattern 26 and the wiring pattern 28 are disposed adjacent to each other.

  As shown in FIG. 2, the wiring pattern 26 has a branched portion 26a. The branch portion 26 a branches off toward a certain portion 28 a of the wiring pattern 28. The part 28a is a part where a conductive resin is provided in the process of manufacturing the printed circuit board 10 described later, and is exposed without being covered with the solder resist so that the conductive resin can be easily formed. Similarly, the branch portion 26a is also provided with a conductive resin during the manufacturing process, and the branch portion 26a is exposed without being covered with the solder resist. Note that one end of the wiring pattern 28 opposite to the terminal electrode 18 is connected to the interlayer wiring of the multilayer substrate 12 through the through hole 28b. The two wiring patterns 26 are coupled to each other at one end opposite to the terminal electrode 16 and surround the two wiring patterns 28 to prevent noise to the high frequency signal.

  Hereinafter, the manufacturing method of the printed circuit board 10 provided with the said structure is demonstrated. FIG. 3 is a flowchart showing a method for manufacturing the printed circuit board 10 according to the present embodiment. As shown in FIG. 3, the manufacturing method includes a pattern formation step S1, a short-circuit step S2, a plating step S3, and a removal step S4.

<Pattern formation process>
FIG. 4 is a plan view showing the pattern forming process, and FIG. 5 is an enlarged perspective view showing a part of FIG. First, as shown in FIG. 4, a substrate product 100 including a plurality of regions to be the substrates 12 is manufactured, and terminal electrodes 16, 18, and 20 and wiring patterns 26 and 28 are formed on each substrate 12. . At this time, a branch portion 26a (see FIG. 5) of the wiring pattern 26 is also formed at the same time. Further, the power supply pattern 102 for electrolytic plating is formed outside the region to be the laminated substrate 12 using the same metal material as these terminal electrodes and wiring patterns. At this time, the power supply pattern 102 is formed along the edge 12 a that becomes the card edge connector portion of the multilayer substrate 12.

  At the same time, the electrolytic plating wiring 104 is formed. The electroplating wiring 104 reaches the edge 12 a of the multilayer substrate 12 from the terminal electrodes 16, 20 and is connected to the power supply pattern 102. As shown in FIG. 5, the electrolytic plating wiring 104 extends in the direction intersecting the edge 12 a through the inner layer of the substrate 12, and connects the terminal electrodes 16 and 20 and the power supply pattern 102. . The electrolytic plating wiring 104 is formed of the same metal material (copper foil) as the terminal electrodes 16, 18 and 20 and the wiring patterns 26 and 28, and the width thereof is narrower than that of the terminal electrodes 16 and 20. Note that such electrolytic plating wiring is not formed on the terminal electrode 18.

  Then, a solder resist is formed on the substrate 12 after the pattern forming process described above. At this time, the portions of the wiring patterns 26 and 28 where the conductive resin is provided (the branch portion 26a of the wiring pattern 26 and the portion 28a of the wiring pattern 28) and the terminal electrodes 16, 18, and 20 are exposed from the solder resist. After the solder resist is formed, silk printing is performed on the surface of the substrate 12.

<Short-circuit process>
As shown in FIG. 6, the wiring pattern 26 and the wiring pattern 28 are short-circuited with a conductive resin (conductive paste) 106. Specifically, the conductive resin 106 is disposed so as to straddle the branch portion 26 a of the wiring pattern 26 and the portion 28 a of the wiring pattern 28. As the conductive resin 106, for example, a mixture of silver filler and acrylic resin (such as Dotite (registered trademark) manufactured by Fujikura Kasei Co., Ltd.) is used. The base material may be an epoxy resin or a vinyl resin. As a method for mounting the conductive resin 106, there are various methods such as a method of supplying the paste-like conductive resin 106 with a dispenser, a method using a metal mask, or a method using screen printing. After supplying the conductive resin 106, the conductive resin 106 is solidified by being left at room temperature or heating.

<Plating process>
Electrolytic plating is performed on the terminal electrodes 16, 18 and 20. Specifically, after masking the portions other than the terminal electrode portion and cleaning the surfaces of the terminal electrodes 16, 18, and 20, the substrate product 100 shown in FIG. Supply. This current flows to the terminal electrodes 16 and 20 via the electrolytic plating wiring 104 and further flows to the terminal electrode 18 via the conductive resin 106. In this state, the terminal electrodes 16, 18, and 20 are first subjected to nickel plating, and then subjected to gold plating. At this time, nickel plating may be formed to a thickness of 3 μm, for example, and gold plating may be formed to a thickness of 1.3 μm, for example.

<Removal process>
After the electrolytic plating process is completed, the conductive resin 106 is removed. That is, the conductive resin 106 is removed using an organic solvent that dissolves a resin (acrylic resin, epoxy resin, vinyl resin, or the like) that is a base material of the conductive resin 106, for example, acetone. At this time, since the terminal electrodes 16, 18, and 20 are made of metal, they hardly react with such an organic solvent, and only the conductive resin 106 is selectively removed.

  Finally, the substrate 12 is removed from the substrate product 100. In this way, the printed circuit board 10 shown in FIGS. 1 and 2 is obtained.

  In the printed circuit board manufacturing method of the present embodiment, the conductive resin 106 is used as a power supply means for electrolytic plating of the terminal electrode 18. Although the conductive resin 106 is dissolved in an organic solvent or the like, the terminal electrodes 16, 18 and 20 and the wiring patterns 26 and 28 are made of metal and are not removed at all by the organic solvent. Thus, since the conductive resin 106 can be selectively removed with respect to the terminal electrodes 16, 18, and 20 and the wiring patterns 26, 28, the stub can be removed without damaging these terminal electrodes and wiring patterns. It can be completely removed without generating. That is, according to the method for manufacturing a printed circuit board of the present embodiment, it is possible to suitably perform electrolytic plating on the terminal electrode 18 while suppressing the occurrence of damage and stubs in the specific terminal electrode 18.

  Further, as in the present embodiment, when forming the solder resist, the solder resist is formed so that the portions (the branch portions 26a and the portions 28a) where the conductive resin 106 is provided in the wiring patterns 26 and 28 are exposed. It is preferable. Thereby, the mounting operation of the conductive resin 106 on the wiring patterns 26 and 28 is facilitated.

  Further, as in the present embodiment, the wiring pattern 26 preferably has a branched portion 26 a that branches toward the portion 28 a of the wiring pattern 28. Thereby, the space | interval of wiring patterns 26 and 28 becomes narrow, and the short circuit by the conductive resin 106 can be made easy.

  FIG. 7 is a diagram for explaining a modification of the embodiment. FIG. 7 shows a state in which the conductive resin 106 is mounted on the substrate 12 in the short-circuit process. In this modification, a wiring pattern 38 is formed on the substrate 12 in place of the wiring pattern 28 shown in FIG. The wiring pattern 38 is a second wiring pattern that is electrically connected to the terminal electrode 18 and extends to the inside of the substrate 12. The wiring pattern 38 has a pad portion 38 a at one end opposite to the edge 12 a of the substrate 12. The pad portion 38a is a part where electronic components are mounted, and for example, a coupling capacitor or the like is mounted. Accordingly, the pad portion 38a is exposed without being covered with the solder resist.

  In this modification, the pad portion 38a is used as a portion where the conductive resin 106 is provided. That is, in the short circuit process, as shown in FIG. 7, the conductive resin 106 is disposed so as to straddle the branch portion 26 a of the wiring pattern 26 and the pad portion 38 a of the wiring pattern 38.

  In the form shown in FIG. 5, the conductive resin 106 is provided by exposing a part (part 28a) of the wiring pattern 28 for high-frequency signals from the solder resist, but the part 28a is not protected by the solder resist. There are concerns about local variations in characteristic impedance and environmental resistance (reliability). On the other hand, by providing the conductive resin 106 on the pad portion 38a on which the electronic component is mounted, the plating process can be suitably performed without increasing the exposed portion of the high-frequency signal wiring pattern.

  Subsequently, an application example of the printed circuit board 10 manufactured by the manufacturing method described above will be described. 8-10 is a figure which shows the structure of the optical module 1 provided with the printed circuit board 10. FIG. FIG. 8 is a perspective view showing the appearance of the optical module 1. FIG. 9 is a cross-sectional view showing a side cross-section along the longitudinal direction of the optical module 1 shown in FIG. FIG. 10 is a plan sectional view of the optical module 1. 8 to 10 show an XYZ orthogonal coordinate system for explanation.

  The optical module 1 is an optical transceiver that forms a part of an optical communication device and can be inserted into and removed from the optical communication device main body. Referring to FIGS. 8 to 10, the optical module 1 has a substantially rectangular parallelepiped shape having a certain direction (X-axis direction in the present embodiment) as a longitudinal direction, and includes a housing 3, a light emitting unit 4, and a light receiving unit 5. , And a printed circuit board 10. FIG. 9 also shows the socket 202 on the optical communication apparatus main body side.

  The light emitting unit 4 converts an electrical transmission signal into an optical signal and transmits it to the outside of the optical communication device. The light emitting unit 4 is disposed at the front edge of the printed circuit board 10. The light emitting unit 4 includes a laser diode, a ferrule through which an optical fiber is inserted, a sleeve for holding the ferrule, and the like. A plurality of lead pins extend from the base of the light emitting unit 4 and are connected to the printed circuit board 10 via a flexible printed circuit board (FPC) 4a. The light receiving unit 5 converts the optical signal sent to the optical communication device into an electrical reception signal. The light receiving unit 5 is arranged alongside the light emitting unit 4 at the front edge of the printed circuit board 10. The light receiving unit 5 includes a photodiode, a preamplifier, a ferrule through which an optical fiber is inserted, a sleeve for holding the ferrule, and the like. A plurality of lead pins extend from the light receiving unit 5 and are connected to the printed circuit board 10 via a flexible printed circuit board (FPC) 5a.

  Both the front surface 10a and the back surface 10b of the printed circuit board 10 are electrically connected to the lead pin 4a of the light emitting unit 4 and electrically connected to the lead pin 5a of the light receiving unit 5 and the driver IC that controls the driving of the light emitting unit 4. A plurality of electronic components 6 including an IC for processing a signal received from the light receiving unit 5 are mounted. The rear edge portion of the printed circuit board 10 is a card edge connector portion 14, and terminal electrodes 16, 18, and 20 are provided as shown in FIG.

  As shown in FIG. 9, the card edge connector portion 14 of the printed circuit board 10 is inserted into and extracted from a socket 202 provided on the mounting substrate 200 of the optical communication apparatus main body. The socket 202 has a recess 202a that fits into the card edge connector portion 14, and a plurality of socket terminals 202b that are in electrical contact with the terminal electrodes 16, 18, and 20 of the card edge connector portion 14 are provided in the recess 202a. Is provided. Therefore, when the card edge connector portion 14 is inserted into the socket 202, the terminal electrodes 16, 18, and 20 are electrically connected to the plurality of socket terminals 202b.

  Since the optical module 1 includes the printed circuit board 10 according to the above-described embodiment, the occurrence of damage and stubs in the high-frequency signal terminal electrode 18 is suppressed. Therefore, a high-frequency transmission signal can be received from the mounting substrate 200 of the optical communication apparatus body with low noise, and a high-frequency reception signal can be transmitted to the mounting substrate 200 with low noise.

  The method for manufacturing a printed circuit board according to the present invention is not limited to the above-described embodiment, and various other modifications are possible. For example, in the above-described embodiment, power is supplied to the terminal electrode for high-frequency signals by the conductive resin, but power may be supplied to the terminal electrode for other uses using the conductive resin.

FIG. 1 is a plan view showing an embodiment of a printed board. FIG. 2 is a partially enlarged view of the printed circuit board shown in FIG. FIG. 3 is a flowchart showing a method for manufacturing a printed circuit board. FIG. 4 is a plan view showing a pattern forming process. FIG. 5 is a partially enlarged view of FIG. FIG. 6 is a diagram illustrating a short-circuit process. FIG. 7 is a diagram for explaining a modification. FIG. 8 is a perspective view illustrating an appearance of an optical module including a printed circuit board. FIG. 9 is a side sectional view along the longitudinal direction of the optical module shown in FIG. 10 is a cross-sectional plan view of the optical module shown in FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Optical module, 3 ... Housing | casing, 4 ... Light emitting unit, 5 ... Light receiving unit, 6 ... Electronic component, 10 ... Printed circuit board, 12 ... Board | substrate, 14 ... Card edge connector part, 16, 18, 20 ... Terminal electrode, DESCRIPTION OF SYMBOLS 26,28,38 ... Wiring pattern, 26a ... Branch part, 38a ... Pad part, 100 ... Substrate product, 102 ... Feeding pattern, 104 ... Electrolytic plating wiring, 106 ... Conductive resin.

Claims (5)

On the substrate, first and second terminal electrodes, wiring for electrolytic plating reaching the edge of the substrate from the first terminal electrode, and the first and second terminals extending from the first and second terminal electrodes, respectively. A pattern forming step of forming two wiring patterns;
A short-circuiting step of short-circuiting the first and second wiring patterns with a conductive resin;
A plating step of performing electrolytic plating on the first and second terminal electrodes;
And a removing step of removing the conductive resin.   2. The printed circuit board according to claim 1, wherein after the pattern formation step, a solder resist is formed so as to expose a portion where the conductive resin is provided in the first and second wiring patterns. Production method.   The method for manufacturing a printed circuit board according to claim 2, wherein the portion of the second wiring pattern is a pad portion on which an electronic component is mounted.   The said 1st wiring pattern has a part branched toward the site | part of the said 2nd wiring pattern in which the said conductive resin is provided, The Claim 1 characterized by the above-mentioned. The manufacturing method of the printed circuit board of description. The conductive resin includes an acrylic resin,
The method for manufacturing a printed circuit board according to any one of claims 1 to 4, wherein the conductive resin is removed by an organic solvent in the removing step.

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