JP4526716B2 - Surface treatment equipment for printed circuit boards - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a surface treatment apparatus for performing surface treatment of a printed circuit board.
[0002]
[Prior art]
The printed circuit board is composed of an insulating layer made of a polymer or the like and a conductive layer made of metal or the like and having a planar circuit pattern formed in contact with the insulating layer. In particular, a multilayer printed board composed of a laminate in which conductive layers and insulating layers are alternately stacked and integrated is widely used in the industry. In this printed board, in order to form a three-dimensional electric circuit, an electrical conduction hole called a via hole is provided in the insulating layer, and the conductive layers are electrically connected. In the present application, the via hole is a hole called a blind via hole or the like that does not penetrate the substrate, and a through hole that penetrates the substrate is distinguished.
[0003]
In general, when forming a hole for a via hole in a printed circuit board, a residue containing a constituent material of an insulating layer called smear remains on the bottom surface or inner wall surface of the hole, or a metal burr forming a conductive layer is generated. Sometimes. Since smear prevents exposure of the conductive layer and causes poor conduction of the via hole, desmear treatment is performed to remove smear with an oxidizing agent solution such as a potassium permanganate solution. In addition, other wet processes such as a process for removing the oxide film from the conductive layer and a blackening process for roughening the inner surface of the hole to improve the plating may be performed. Thereafter, the conductive layers are electrically connected by coating the inside of the holes with a conductive plating such as metal, thereby completing the via holes.
[0004]
By the way, as the printed circuit board, particularly the multilayer printed circuit board, is mounted with a high density, the required via hole diameter has been reduced to about 50 μm, for example, and it has become impossible to remove smear sufficiently by conventional wet processing. Therefore, in place of the wet desmear process using an oxidant solution, a dry desmear process not using a solution or the like is being used. As dry desmear treatment, treatment using plasma discharge, treatment using corona discharge with needle-like or linear electrodes, and the like are known, and such treatment technology is disclosed in JP-A-8-215934. Japanese Laid-Open Patent Publication No. 3-268888, Japanese Laid-Open Patent Publication No. 3-281877, Japanese Patent No. 2625078, Japanese Patent No. 2500293, Japanese Patent No. 2572199, Japanese Patent Laid-Open No. 8-132392, Japanese Patent No. 2572201, Japanese Patent No. 2614697. No. 2618211, No. 2680986, No. 60-225493, No. 61-36991, No. 5-175069, No. 62-98798, and It is disclosed in JP-A-7-99378.
[0005]
[Problems to be solved by the invention]
On the other hand, in the conventional processing technique using corona discharge with needle-like electrodes as disclosed in the above-mentioned Japanese Patent No. 2625078, etc., the needle-like electrodes need to be accurately arranged in the vicinity of the holes. When the electrodes are regularly arranged, it is difficult to accurately align the needle electrodes. Further, in the conventional processing technique using the corona discharge by the linear electrode as disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 8-215934, the difficulty of alignment in the needle electrode is reduced, but the discharge is not good. There is a risk that current may be concentrated at one place and arc discharge may occur and the substrate surface may be damaged. Furthermore, when the thickness of the printed board is reduced and the area is increased, warping and distortion occur, and in this case, current concentration may easily occur in a portion where the distance between the electrode and the printed board is shortened.
[0006]
The present invention solves the above-mentioned problems of the conventional processing technology, eliminates the difficulty of alignment between the electrode and the corona discharge machining portion, and further stabilizes the discharge so that current concentration does not occur. An object of the present invention is to provide a surface treatment apparatus for a printed circuit board that can be processed.
[0007]
[Means for Solving the Problems]
A surface treatment apparatus for a printed circuit board according to the present invention is a surface treatment apparatus for a printed circuit board in which a hole for a via hole is formed in an insulating layer, and the surface of the printed circuit board having a conductive layer in contact with the insulating layer is processed by corona discharge. A suction means for sucking and fixing a surface opposite to the surface to be processed in which holes for via holes to be processed by corona discharge are formed; and a position opposite to the surface to be processed and parallel to the surface to be processed disposed, the rod-shaped electrode for generating a corona discharge between the conductive layer, a dielectric member disposed between the treated surface and the electrode, and the installation base for installing a printed circuit board The suction means is provided on the installation table, and the suction means is a groove formed on the installation table, and formed at least inside the outer periphery of the printed circuit board and forming a closed space with the printed circuit board. Have The planar shape of引溝is characterized substantially square shape der Rukoto.
[0008]
According to the present invention, by disposing a dielectric between the surface to be processed and the electrode, the dielectric functions as an aggregate of micro capacitors, so that corona discharge is stabilized and does not concentrate at a specific position. To do. In addition, by fixing the printed circuit board by suction with suction means, it corrects warping and distortion that occurs in the printed circuit board, and keeps the distance between the electrode and the printed circuit board constant so that the corona discharge is stabilized and not concentrated at a specific position. To. Further, according to the present invention, a suction means may be provided on the installation base for installing the printed circuit board, and in this way, the printed circuit board is installed on the installation base without warping or distortion. It is possible to stabilize the corona discharge so that it is not concentrated at a specific position. Further, according to the present invention, the printed circuit board can be sucked and fixed to the installation table by sucking the air in the suction groove and reducing the pressure while the printed circuit board is placed on the installation table. It can be installed without warping or distortion, and corona discharge can be made more stable and not concentrated at a specific position.
[0009]
Further, in the present invention, the electrode may be an electrode in which discharge points are continuous in a linear shape, and in this way, corona discharge can be caused simultaneously in a range having a one-dimensional extent, and the one-dimensional Therefore, it is not necessary to accurately position the electrodes with respect to the machining target holes irregularly present in a wide range.
[0010]
In the present invention, the electrode may be an electrode in which discharge points are continuous in a lattice shape or a planar shape, and in this way, a corona discharge can be caused in a range having a two-dimensional extent. There is no need to accurately position the electrodes with respect to holes to be processed that are irregularly present in a range having a dimensional extent.
[0011]
In the present invention, a plurality of electrodes may be provided, corona discharge machining can be performed over a wider range, and various machining forms can be accommodated by increasing or decreasing the number of electrodes installed.
[0012]
Further, in the present invention, an electrode in which the length of the discharge point in the longitudinal direction of the electrode is not less than the maximum linear dimension value of the surface to be processed may be used, and in this way, for example, the end of the electrode and the end of the printed circuit board Since the electrodes can always pass through the printed circuit board, the printed circuit board can be processed at a time even if the printed circuit board is not arranged exactly parallel to the electrodes.
[0013]
In the present invention, the dielectric member may be coated on at least a portion of the electrode facing the surface to be processed. In this way, the dielectric member and the electrode can be integrated, and the electrode or dielectric The installation and movement of members can be facilitated.
[0015]
In the present invention also, the suction means is an exhaust port for exhausting to the outside unit, and may further include a communication passage connecting the suction groove and the exhaust opening. In this way, with the printed circuit board placed on the installation base, a pressure reducing means such as a suction pump is connected to the exhaust port, and the printed circuit board is removed by sucking and reducing the air from the suction groove to the communication path. Since it can be sucked and fixed to the installation table, the printed circuit board can be installed on the installation table without warping or distortion, and corona discharge can be stabilized and not concentrated at a specific position.
[0017]
Further, in the present invention, a moving means for moving the electrode and the surface to be processed relative to each other may be further provided. In this way, even when a linear electrode is used as the electrode, for example, the surface to be processed Processing can be performed on the whole, and processing time can be shortened.
[0018]
Further, in the present invention, it may be further provided with a conveying means for conveying the printed board, and the suction means may be placed on the conveying means. In this way, for example, the printed board conveyed from the previous process or the like. The processing can be performed as it is, and the processing time can be shortened.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of a surface treatment apparatus for a printed circuit board according to the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same or equivalent elements will be denoted by the same reference numerals, and redundant description will be omitted.
[0020]
FIG. 1 is a perspective view for explaining a printed circuit board surface treatment apparatus according to the first embodiment, and FIG. 2 is a cross-sectional view of the vicinity of an electrode in FIG. On the base 11 of the surface treatment apparatus, a conveying means 12 is installed via a locking means (not shown). The conveying means 12 is composed of a plurality of roller-like members that can rotate at an arbitrary speed and timing, and the conveying object placed on the roller is rotated at a predetermined speed and by rotating the roller. It can be moved at the timing. A support member 13 for supporting a corona discharge electrode is further installed on the base 11 so as to straddle the conveying means 12. The support member 13 has a corona discharge electrode 23 (hereinafter referred to as a first electrode). Electrode) is suspended at a position facing the conveying means 12. The first electrode 23 is an electrode made of a metal round bar or pipe, and is covered with a dielectric member 24 made of glass, ceramics, rubber or the like over almost the entire width.
[0021]
The printed circuit board 200 to be subjected to the corona discharge treatment is placed on the installation table 100 on the second electrode 25 and conveyed on the conveying means 12. The distance between the printed circuit board 200 and the dielectric member 24 covered with the first electrode 23 is set to a (0.1 mm to 9 mm, more preferably 0.3 mm to 5 mm). The second electrode 25 is formed from a metal plate having a larger area than the printed circuit board 200, and may or may not be grounded. The first electrode 23 and the second electrode 25 are connected by an external circuit via the high-frequency power source 21 and the high-voltage high-frequency transformer 22. The high frequency power supply 21 controls the primary input voltage of the high voltage high frequency transformer 22. The output of the high-voltage high-frequency transformer 22 is connected to the first electrode 23, and an AC voltage of 4 kV to 20 kV is applied to the first electrode 23 and the second electrode 25 at a high frequency of 5 kHz to 500 kHz. Is possible. A suction pump 31 is connected to the installation table 100 via a connection hose 32, and the printed circuit board 200 is fixed to the installation table 100 by suction.
[0022]
FIG. 3 is a plan view of the installation table 100. The installation stand 100 will be described in detail with reference to FIGS. The installation table 100 includes a suction part 101 and a spacer 102. The suction portion 101 is provided with a triple first suction groove 103 in a substantially square shape, and a second suction groove 104 is further provided so as to connect the first suction grooves 103 to each other. It is connected to the port 107. The communication path 105 is formed by an air inlet 107, an L-shaped connector 108, and a hose 109. The suction port 107 is provided in a shape that opens a hole in the suction portion 101, and an L-shaped connector 108 is connected to the side opposite to the second suction groove 104. The L-shaped connector 108 is further connected to a hose 109, and the L-shaped connector 108 and the hose 109 are disposed in the spacer 102. The spacer 102 is provided with an exhaust port 106 for exhausting to the outside, and a hose 109 is connected thereto.
[0023]
The port on the opposite side of the exhaust port 106 to which the hose 109 is connected is connected to the suction pump 31 via the connecting hose 32. By operating the suction pump 31, the exhaust port 106 and the hose are connected. 109, the L-shaped connector 108, the suction port 107, the second suction groove 104, and the first suction groove 103, the internal air is sucked and depressurized to form a so-called vacuum state, and the printed circuit board 200 is brought into close contact with the installation table 100. And warp and distortion generated in the printed circuit board 200 can be corrected. If the printed circuit board 200 cannot cover the first suction groove 103 and the second suction groove 104, the portion that cannot be covered is covered with a thin plate, or the suction power of the suction pump 31 is increased so that the printed circuit board 200 is The suction is preferably performed to such an extent that it is in close contact with the installation table 100.
[0024]
Next, the dielectric member 24 will be described in detail. The dielectric member 24 functions as a set of minute capacitors 26a, 26b,..., 26n as shown in FIG. 4, and plays a role of preventing the corona discharge from being concentrated at a specific position. In other words, if a small capacitor is charged in the half cycle of the applied high-frequency voltage, current stops flowing at the position of the small capacitor, current flows at the position of the other small capacitor, and the small capacitor is charged. If so, the current flows at the position of another minute capacitor, and the position where the current flows changes sequentially. In the next half cycle, the minute capacitor is charged in the reverse direction, and the position where the reverse current flows sequentially changes. That is, a current I as shown in FIG. 5 flows every half cycle of the high-frequency voltage V. As described above, in the printed circuit board surface treatment apparatus according to this embodiment, the concentration of discharge at a specific position can be prevented and the transition to arc discharge can be suppressed, and the insulating layer 201 and the like may be damaged. Absent.
[0025]
Next, a method for performing corona discharge machining using the printed circuit board surface treatment apparatus according to the present embodiment will be described with reference to FIGS. First, the printed circuit board 200 is placed on the installation table 100 and sucked to bring the printed circuit board 200 into close contact with the installation table 100 to correct warping and distortion of the printed circuit board 200. The installation table 100 is placed on the transport means 12 via the second electrode 25 and is transported so as to pass under the first electrode 23 after suction. Next, when a voltage is applied to the first electrode 23 and the second electrode 25 by the high-frequency power source 21 and the high-voltage high-frequency transformer 22, the electric field between the electrodes increases, and when the electric field reaches a certain critical value. Corona discharge occurs. At this time, the discharge generated from the first electrode 23 concentrates on the conductive layer 202 exposed in the hole 204 for the via hole. Thus, the smear 205 remaining at the bottom of the via hole 204 can be removed by being decomposed or evaporated. In addition, a part of the discharge generated from the first electrode 23 is irradiated onto the surface to be processed on which the hole 204 of the printed board 200 is formed, so that the surface to be processed can be quickly made hydrophilic. Such corona discharge treatment is performed while the printed circuit board 200 is moved in the direction orthogonal to the longitudinal direction of the first electrode 23 by the conveying means 12, thereby removing the smear 205 remaining at the bottom of all the via hole holes 204. At the same time, the entire surface to be processed can be made hydrophilic. Further, a hole for a via hole may be further formed on the surface opposite to the surface to be processed in which the hole 204 is formed. When the surface on which the hole for the via hole is formed is surface-treated, the printed board 200 is turned over and the surface treatment is similarly performed.
[0026]
When the conductive layer 202 is made of copper, copper is oxidized if the time of the corona discharge treatment is long. Therefore, it is preferable to limit the time of the corona discharge treatment to about 1 to 5 seconds in order to prevent oxidation. As described above, when the corona discharge treatment is performed on the entire surface by moving the printed board 200 in the direction orthogonal to the longitudinal direction of the first electrode 23, the moving speed of the printed board 200 is changed. The discharge treatment time can be adjusted and oxidation of the conductive layer 202 can be prevented. For example, when the first electrode 23 is a round bar having a diameter of 5 mm, the moving speed of the printed circuit board 200 may be about 10 mm / second. Here, an example in which processing is performed on the entire surface to be processed by moving the substrate 200 in a direction perpendicular to the longitudinal direction of the first electrode 23 has been described, but instead of moving the printed circuit board 200, the first electrode It is good also as processing to the whole to-be-processed surface by moving 23. FIG.
[0027]
When the printed circuit board 200 is rectangular, if the length of the first electrode 23 is equal to or longer than the length of the short side of the circuit board 200, a plurality of via hole holes formed in a one-dimensional shape on the printed circuit board 200 are used. 204 can be processed at a time, which is preferable. Furthermore, if the length of the first electrode 23 is equal to or greater than the length of the diagonal line that is the maximum linear dimension value of the printed circuit board 200, one side of the printed circuit board 200 and the longitudinal direction of the first electrode 23 are accurately parallel to each other. Even if it is not arranged, it is more preferable because the processing can be performed up to the end of the printed circuit board 200 at a time.
[0028]
In the present embodiment, the first suction grooves 103 are provided in a triple manner, but this can be changed as appropriate depending on the size of the printed circuit board 200 to be placed and the situation such as warpage. Further, although the shape is also substantially rectangular in this embodiment, this is in accordance with the shape of the printed circuit board 200 to be placed (indicated by a two-dot chain line in FIG. 3). It is preferable to design the groove to be circular, for example, the grooves may be formed radially.
[0029]
The printed circuit board surface treatment apparatus according to the second embodiment is obtained by replacing the installation table 100 of the first embodiment with an installation table 300 shown in FIG. 6 is a plan view of the installation table 300, and FIG. 7 is a cross-sectional view taken along the line AA of FIG. Since the configuration other than the installation table 300 is the same as that of the first embodiment, the installation table 300 will be described in detail. The installation table 300 includes a suction part 301 and a spacer 302. A large number of suction holes 303 are provided in the suction part 301 so as to penetrate the suction part 301. The spacer 302 is provided with a space 304 provided so as to be connected to the suction hole 303 and a passage 305 connected to the space 304, thereby forming a communication passage 306. Further, the spacer 302 is provided with an exhaust port 307 for exhausting to the outside, and a passage 305 is connected thereto.
[0030]
The port on the opposite side of the exhaust port 307 to which the passage 305 is connected is connected to the suction pump 31 via the connecting hose 32. By operating the suction pump 31, the exhaust port 307 and the passage are connected. The internal air is sucked through the space 305, the space 304, and the suction hole 303 to be in a vacuum state, the printed circuit board 200 can be brought into close contact with the installation base 300, and the warp and distortion generated in the printed circuit board 200 can be corrected. Can do. If the printed circuit board 200 cannot cover the suction hole 302, the portion that cannot be covered is covered with a thin plate, or the suction force of the suction pump 31 is increased so that the printed circuit board 200 is in close contact with the installation table 300. Is preferred.
[0031]
The surface treatment apparatus for a printed circuit board according to the third embodiment uses the first electrode 23 and the dielectric member 24 of the first embodiment as the first electrode 61 and a plate-like insulator member made of a grid-like metal member. This is replaced with 62. FIG. 8 is a perspective view for explaining the surface treatment apparatus for a printed circuit board according to the third embodiment. Since the configuration other than the vicinity of the electrode is the same as that of the first embodiment, the vicinity of the electrode will be described in detail. The first electrode 61 made of a grid-like metal member is deposited on the plate-like insulator member 62, and the output from the high-frequency transformer 22 is similarly connected to the first electrode 61. In this way, since the discharge points can be formed in a lattice shape, the discharge machining can be performed simultaneously in a range having a two-dimensional spread, and the processing time can be shortened. Moreover, if a grid-like metal member is used as a planar metal member to form an electrode for discharge, electric discharge machining can be performed with a higher density.
[0032]
The surface treatment apparatus for a printed circuit board according to the fourth embodiment has a plurality of first electrodes 23 and dielectric members 24 according to the first embodiment. FIG. 9 is a perspective view for explaining a surface treatment apparatus for a printed circuit board according to the fourth embodiment, and FIG. 10 is a cross-sectional view of the vicinity of the center of the apparatus as viewed from the direction P in FIG. Since the configuration other than the vicinity of the electrode is the same as that of the first embodiment, the vicinity of the electrode will be described in detail. In the present embodiment, three first electrodes 71a, 71b, 71c covered with insulator members 72a, 72b, 72c are used. As shown in FIG. 10, these are supported by the support member 13 at the same position in the vertical direction at equal intervals. In this way, since the discharge points formed in a linear shape can be continuously formed at a predetermined interval, electric discharge machining can be performed simultaneously in a range having a two-dimensional spread, Time can be shortened. In addition, the number of the first electrodes can be appropriately set according to the size of the printed circuit board 200 to be processed and the processing speed, which is more efficient.
[0033]
The embodiment is not limited to the above-described embodiment, and various modifications can be made according to other conditions. For example, the second electrode 25 does not need to be disposed in contact with the installation table 100, and a separate dielectric member may be disposed between the installation table 100 and the second electrode 25. Alternatively, the first electrode 23 and the installation base 100 may be connected by the high frequency power source 21 and the high voltage high frequency transformer 22 so that the installation base 100 plays the role of the second electrode 25.
[0034]
【The invention's effect】
According to the surface treatment apparatus for a printed circuit board according to the present invention, it is possible to solve the problems of the conventional treatment technique and to perform the surface treatment quickly and effectively. That is, by disposing a dielectric member between the surface to be processed and the electrode for generating corona discharge, the dielectric member functions as an aggregate of micro capacitors and does not concentrate the discharge at a specific position. To play a role. Therefore, the transition to arc discharge as in the conventional processing technique using corona discharge by linear electrodes can be suppressed, and smear inside the hole for the via hole is removed without damaging the surface to be processed. It becomes possible. In addition, since the surface to be treated can be hydrophilized by corona discharge, it is possible to easily perform wet treatment, plating treatment, etc. even for small-diameter holes, and as a result, via holes with sufficient electrical conduction. Can be formed. Furthermore, since the printed circuit board is sucked and fixed by the suction means to correct the warp and distortion, the distance between the board and the electrode is kept constant, and the corona discharge is stabilized.
[Brief description of the drawings]
FIG. 1 is a diagram for explaining a printed circuit board surface treatment apparatus according to a first embodiment;
FIG. 2 is a diagram illustrating a surface treatment apparatus for a printed circuit board according to the first embodiment.
FIG. 3 is a diagram for explaining a printed circuit board installation base according to the first embodiment;
FIG. 4 is a perspective view for explaining processing of the first embodiment.
FIG. 5 is a graph for explaining processing in the first embodiment;
FIG. 6 is a diagram illustrating a printed circuit board installation table according to the second embodiment.
FIG. 7 is a cross-sectional view illustrating a printed circuit board installation base according to a second embodiment.
FIG. 8 is a view for explaining a surface treatment apparatus for a printed circuit board according to a third embodiment.
FIG. 9 is a diagram for explaining a printed circuit board surface treatment apparatus according to a fourth embodiment;
FIG. 10 is a diagram for explaining a printed circuit board surface treatment apparatus according to a fourth embodiment;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 100 ... Installation stand, 101 ... Adsorption stand, 102 ... Spacer, 103 ... 1st intake groove, 104 ... 2nd intake groove, 105 ... Communication path, 106 ... Exhaust port, 200 ... Printed circuit board, 201 ... Insulating layer 202 ... conductive layer, 203 ... insulating layer, 204 ... hole, 205 ... smear, 21 ... high frequency power source, 22 ... high voltage high frequency transformer, 23 ... first electrode, 24 ... dielectric member, 25 ... second electrode , 26 ... Micro capacitor

Claims (9)

A surface treatment apparatus for a printed circuit board in which a hole for a via hole is formed in an insulating layer, and the surface of the printed circuit board having a conductive layer in contact with the insulating layer is processed by corona discharge,
A suction means for sucking and fixing a surface of the printed circuit board opposite to the surface to be processed in which holes for via holes to be processed by the corona discharge are formed;
A rod-shaped electrode disposed at a position facing the surface to be processed and parallel to the surface to be processed, and for generating corona discharge between the conductive layer;
A dielectric member disposed between the surface to be processed and the electrode;
An installation base for installing the printed circuit board ;
The suction means is provided on the installation table;
The suction means is a groove formed in the installation table, and has at least a suction groove formed inside the outer periphery of the printed board and forming a closed space with the printed board;
The surface treatment apparatus for a printed circuit board, wherein the suction groove has a substantially square planar shape .   The surface treatment apparatus for a printed circuit board according to claim 1, wherein the electrode is an electrode having a continuous discharge point in a linear shape.   The surface treatment apparatus for a printed circuit board according to claim 1, wherein the electrodes are electrodes in which discharge points are continuous in a lattice shape or a planar shape.   The surface treatment apparatus for a printed circuit board according to claim 2, comprising a plurality of the electrodes.   5. The surface treatment apparatus for a printed circuit board according to claim 1, wherein a length of a discharge point in a longitudinal direction of the electrode is equal to or greater than a maximum linear dimension value of the surface to be treated.   6. The surface treatment apparatus for a printed circuit board according to claim 1, wherein the dielectric member is coated on at least a portion of the electrode facing the surface to be processed. It said suction means, an exhaust port for exhausting to the outside unit, and, of the printed circuit board according to any one of claims 1 to 6, further comprising a communicating path which connects the inlet groove and the outlet Surface treatment equipment. Further, the surface treatment apparatus of the printed circuit board according to any one of claims 1 to 7, characterized in that it comprises a moving means for relatively moving the said and the electrode surface to be processed together. Furthermore, a transport means for transporting the printed circuit board is provided,
The suction means, the surface treatment apparatus of the printed circuit board according to any one of claims 1 to 8, characterized in that it is placed on the conveying means.

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