JP2005116945A - Multilayer printed-circuit board, and stub countersunk machine and method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multilayer printed-circuit board that can counter-sink a stub with high precision so as to make it short, its stub countersunk machine, and method. <P>SOLUTION: A current sensing layer 16 is provided for exclusive use that electrically connects a wiring layer of the multilayer printed-circuit board 1 and a penetrating via hole 3, and the countersunk depth of the penetrating via hole 3's stub 2 is controlled based on the point where an cutting edge of an electrical drill 11 gets in touch with the penetrating via hole 3. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a multilayer printed wiring board, a stub spot facing device, and a method thereof, and in particular, a current detection layer that conducts between a wiring layer and a via hole is provided, and a point where a cutting edge of a conductive drill is in contact with the via hole is used as a reference. The present invention relates to a multilayer printed wiring board, a stub counterboring device, and a method thereof, which can control a stub counterbore depth of a via hole to make the stub counterfeit with high accuracy.

  Conventionally, in this type of multilayer printed wiring board 101, as shown in FIG. 10, generally, a PKG 104 mounted with an LSI (Large Scale Integrated Circuit) 105 is mounted on the surface, and predetermined inner layers are connected to each other. A through via hole 103 is provided.

  A branch is caused by the stub 102 of the through via hole 103, and reflection occurs due to this branch, resulting in waveform rounding and signal delay. Further, reflection and waveform rounding also occur due to the capacitance of the through via hole 103. However, these two factors cause problems in high frequency transmission.

  In order to solve this problem, as shown in FIG. 11, a multilayer printed wiring board 101 is mounted on a stage 109 via a dummy plate 108 and penetrated by a drill 107 provided in an NC (numerical control) machine 106. There is a method of sitting on the stub 102 of the via hole 103.

  However, since the NC machine 106 controls the counterbore depth based on the distance H from the stage, the bending of the multilayer printed wiring board 101, warpage, variation in plate thickness, variation in plate thickness of the dummy plate 108, NC machine 106 There is a drawback that the stub 102 of the penetrating via hole 103 cannot be satisfactorily seated due to complex factors such as the origin error and the bit length variation of the drill 107.

  Therefore, a conductive drill, a control unit for controlling the conductive drill, an electrical connection member between the conductive layers of the multilayer wiring board, and a power source and current for detecting electrical continuity between the connection member and the conductive drill. A detector is provided, and based on a detection signal from a current detector electrically connected to a target conductive layer of the multilayer wiring board by the control unit, the conductive cutting from the upper surface side of the multilayer wiring board is detected. By controlling the process to stop the progress and form a half-through-hole to the target conductive layer, even if there is a variation in the thickness of each layer or overall thickness of the multilayer wiring board, an appropriate half-through-hole is formed. There is something that can be done (see, for example, Patent Document 1).

  In addition, a table for mounting a printed circuit board, a drill mounted on a spindle motor, a drive control unit for positioning and driving the cutting edge of the drill to cut an inner layer pattern, and an inner layer pattern for which one contact is to be cut from the printed circuit board A continuity detection unit connected to the lower layer conductor directly below and the other contact connected to the drill, and a numerical control data supply terminal storing the pattern cut conditions are provided, and the inner layer pattern of the multilayered printed circuit board is highly accurate Some perform pattern cutting with high reliability (see, for example, Patent Document 2).

Japanese Patent Laid-Open No. 07-015147 JP-A-10-135647

  The conventional multilayer printed wiring board has a through via hole capacitance for connecting each predetermined layer of the inner layer and a branch due to the through via hole stub, so that reflection, signal delay, and waveform rounding due to impedance mismatching occur. There is a problem in that it causes signal delay.

  Therefore, in order to shorten the stub of the through-via hole, a multilayer printed wiring board is mounted on the stage, and the NC machine drills the stub of the through-via hole by using the NC machine drill. In order to control the counterbore depth on the basis of the above, due to complex factors such as flexure of the multilayer printed wiring board, warpage, thickness variation, dummy plate thickness variation, NC machine origin error, drill bit length variation, There is a problem that the through-hole stub cannot be seated with high precision.

  Further, the progress of the conductive cutting from the upper surface side of the multilayer wiring board based on the detection signal from the current detector electrically connected to the target conductive layer of the multilayer wiring board described in Patent Document 1 described above. And the one of the contacts described in Patent Document 2 on the lower layer conductor (ground layer) directly under the inner layer pattern to be cut of the printed circuit board The technology to connect and connect the other contact to the drill to detect continuity and cut the inner layer pattern of the multilayer printed circuit board with high accuracy cannot be applied to shorten the stub of the through via hole. There is.

  In high multi-layer boards, there are tens of thousands of pin through-holes, and it is necessary to conduct continuity tests on all through-holes. In order to inspect each continuity, it is necessary to contact the continuity detection pins with respect to all the through holes. In the techniques described in Patent Documents 1 and 2, the cost of the continuity inspection is large. There is a problem of becoming.

  An object of the present invention is to provide a current detection layer that conducts between a wiring layer of a multilayer printed wiring board and a through-via hole in order to solve the above-mentioned problems, and based on the point where the cutting edge of the conductive drill is in contact with the through-via hole. It is to provide a multilayer printed wiring board, a stub countersink device, and a method thereof that can control a stub counterbore depth of a penetrating via hole with high accuracy to counteract the stub and shorten the stub. .

  The multilayer printed wiring board of the present invention includes a substrate, a plurality of wiring layers formed on the substrate via an insulating layer, a via hole penetrating the substrate and provided with a conductive film, and a via hole in the wiring layer. A current detection layer that is conductive, and the current detection layer is provided exclusively for detecting contact between a tool that sits on a via hole stub and the via hole.

  The current detection layer is provided in any one or both of the wiring layer next to the top layer and the wiring layer in front of the bottom layer.

  The current detection layer is provided in a wiring layer adjacent to a power supply wiring layer or a ground wiring layer connected to the via hole.

  A multilayer printed wiring board stub spot facing device according to the present invention includes a stage on which a multilayer printed wiring board is mounted via a dummy plate, and a numerical control including a conductive drill for sitting on a stub in a via hole of the multilayer printed wiring board. A machine, a control unit that controls the numerical control machine, and a detection unit that detects contact between the conductive drill and the multilayer printed wiring board, and the detection unit includes means for detecting contact in the current detection layer. It is characterized by.

  The detection unit is connected to the control unit, the current detection layer, and the conductive drill.

  The detection unit includes current detection means or resistance detection means.

  The control unit has a means for determining a counterbore depth using the position where the detection unit detects contact between the conductive drill and the multilayer printed wiring board as a reference position in the counterbore direction of the stub, and a counterbore of the stub by a numerical control machine. And means for controlling the depth.

  A multilayer printed wiring board stub spot facing method according to the present invention is a numerical control comprising a stage on which a multilayer printed wiring board is mounted via a dummy plate, and a conductive drill for sitting on a via hole stub of the multilayer printed wiring board. A control unit that controls the machine, a numerical control machine, and a detection unit that detects contact between the conductive drill and the multilayer printed wiring board, and the detection unit includes a step of detecting contact with the current detection layer. It is characterized by.

  The detection unit is connected to the control unit, the current detection layer, and the conductive drill.

  The detection unit includes current detection means or resistance detection means.

  The control unit determines the counterbore depth using the position where the detection unit detects contact between the conductive drill and the multilayer printed wiring board as a reference position in the counterbore direction of the stub, and countersinks the stub by the numerical control machine. And a step of controlling the depth.

  The multilayer printed wiring board is characterized in that a via hole is formed, a circuit pattern is formed, a solder resist layer is provided, and then mounted on a stage, and a stub is spotted.

  The stub spot facing device of the multilayer printed wiring board of the present invention detects contact between the conductive drill and the current detection layer of the multilayer printed wiring board by the detection unit, and when the detection unit detects contact, the control unit automatically In order to calculate the offset value and control the countersink depth of the through-hole in the NC machine conductive drill, the stub countersink process is automated for all through-holes in the multilayer printed wiring board. There is an effect that can be done.

  In addition, since the stub of the through-hole is seated on the basis of where the cutting edge of the conductive drill comes into contact with the through-via hole of the multilayer printed wiring board, the accuracy is improved and the stub of the through-via hole can be shortened. effective.

  Next, the best mode for carrying out the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic configuration diagram showing a stub counterbore device 50 for a multilayer printed wiring board according to the present invention, and FIG. 2 shows details of connection between the ammeter 13, the conductive drill 11 and the multilayer printed wiring board 1 in FIG. 1. FIG. 3 is a view for explaining the contact between the conductive drill 11 and the multilayer printed wiring board 1 in FIG.

  1 to 2, a stub spot facing device 50 for a multilayer printed wiring board includes a stage 9 on which the multilayer printed wiring board 1 is mounted via a dummy plate 8, and a through via hole 3 of the multilayer printed wiring board 1. Numerical control (NC) machine 6 equipped with conductive drill 11 for sitting on stub 2, control unit 12 for controlling numerical control machine 6, and contact between conductive drill 11 and multilayer printed wiring board 1 are detected. The ammeter 13 is connected to the control unit 12, the current detection layer 16 and the conductive drill 11, and is connected to the conductive drill 11 by the current detection layer 16 of the multilayer printed wiring board 1. Configured to detect contact.

  Needless to say, an ohmmeter may be provided instead of the ammeter 13.

  Further, the control unit 12 sets the counterbore depth as a reference position in the counterbore direction (Z direction 14) of the stub 2 where the ammeter 13 detects contact between the conductive drill 11 and the multilayer printed wiring board 1. It is determined and configured to control the counterbore depth of the stub 2 by the numerical control machine 6.

  Referring to FIG. 3, the contact between the conductive drill 11 and the multilayer printed wiring board 1 is detected by using the multilayer printed wiring board 1, the current detection layer 16 provided in the wiring layer next to the top layer 20, and the through via hole. 3 is made conductive (shorted), and when the through-via hole 3 and the cutting edge of the conductive drill 11 come into contact with each other, the current detection layer 16 and the through-via hole 3 are short-circuited. The control unit 12 determines the counterbore depth of the stub 2 by using the current position detected by the ammeter 13 as a reference position (offset value) in the counterbore direction (Z direction 14) of the stub 2. It is configured to control counterbore machining of the stub 2 by the NC machine 6.

  Here, the multilayer printed wiring board mounted on the stage 9 through the dummy plate 8 will be described with reference to the drawings.

  The multilayer printed wiring board 1 shown in FIG. 2 shows a case where the current detection layer 16 is provided in the wiring layer next to the top layer 20, and FIG. 5 shows the current detection layer 16 in the wiring layer next to the top layer 20. 7 shows a multilayer printed wiring board 31 provided on the wiring layer in front of the bottom layer 21. FIG. 7 shows the power detection wiring layer 22 connected to the through via hole 3 (or the ground wiring layer). The multilayer printed wiring board 35 provided in an adjacent wiring layer is shown.

  Next, the manufacturing process of a multilayer printed wiring board is demonstrated easily with reference to drawings.

  FIG. 9 is a diagram illustrating a manufacturing process of the multilayer printed wiring board 40.

  Referring to FIG. 9, an insulating plate on which a body circuit pattern is formed is laminated, heated, and pressurized to form a multilayered substrate (PWB: printed wired board) (step 1), and then a through hole is drilled at a predetermined location by a drill. (Step 2), copper plating treatment is performed on the entire surface including the through hole (Step 3), and a predetermined pattern is formed on the top layer and the bottom layer by etching to form a circuit (Step 4). A solder resist layer is applied and formed (step 5), and the multilayer printed wiring board 40 is manufactured.

  The multilayer printed wiring board 40 is mounted on the stage 9 and the NC machine 6 performs spot facing of the stub 42 of the through via hole 3 (step 6) to obtain the multilayer printed wiring board 40a having a short stub 42a. Can do.

  Next, the operation of the multilayer printed wiring board stub spot facing device 50 configured as described above will be described with reference to the drawings.

  Referring to FIG. 3, when the cutting edge of the conductive drill 11 comes into contact with the through via hole 3, the circuit between both terminals of the ammeter 13 is closed, the resistance value decreases, and the current path 17 is formed. Although the current is detected by the ammeter 13, when the ammeter 13 detects the current, the detection information is transmitted to the control unit 12, and the control unit 12 sets the detected position as a reference position in the spotting direction (Z direction 14). Then, the counterbore depth of the stub 2 is determined, and control is performed to advance the conductive drill 11 to a desired depth.

  As described above, since the current detection position is set as a reference position for spot facing of the stub 2, error factors such as a variation in the thickness of the multilayer printed wiring board 1, a variation in the thickness of the dummy plate 8, and an origin error of the NC machine 6 itself. 11 can be eliminated, and the stub 2 of the penetrating via hole 3 can be shortened with high accuracy compared to the case where the spot facing is performed on the basis of the distance H from the conventional stage 9 shown in FIG.

  FIG. 4 shows a multilayer printed wiring board 1a in which the stub 2 is counterbored on the multilayer printed wiring board 1 of FIG. 3, but all the stubs 2a are processed in a short state.

  Next, with reference to FIG. 5 and FIG. 6, the case where the stub 32 of the penetration via hole 3 is countersunk from both sides of the multilayer printed wiring board 31 will be described.

  Referring to FIG. 5, the multilayer printed wiring board 31 is provided with the current detection layer 16 in the wiring layer next to the top layer 20 and the wiring layer in front of the bottom layer 21, thereby counter boring from the top layer 20 side. And a counterbore process from the bottom layer 21 side, a multilayer printed wiring board 31a having a short stub 32a as shown in FIG. 6 can be manufactured.

  In general, as the depth of sitting is increased due to the perpendicularity of the conductive drill 11 with respect to the workpiece, the eccentricity due to the mounting of the conductive drill 11, and shooting at the time of drilling, the amount of displacement with respect to the center increases. In some cases, the connection between the detection layer 16 and the through-via hole 3 cannot be disconnected (the phenomenon that the plating layer remaining in the through-via hole 3 remains), but the current detection layer 16 is placed next to the top layer as shown in FIGS. By providing each of the layer and the layer in front of the bottom layer 21, the influence of the deviation due to shooting is reduced, and the stub 32 of the through via hole 3 is countersunk from both sides of the multilayer printed wiring board 31, There is an advantage that it is possible to eliminate the occurrence of a problem that the detection layer 16 and the through via hole 3 are short-circuited.

  Next, a multilayer printed wiring board 35 that can more precisely control the counterbore depth of the stub 32 of the through via hole 3 will be described with reference to FIGS.

  Referring to FIG. 7, in the multilayer printed wiring board 35, the current detection layer 16 is provided in each wiring layer adjacent to the power supply wiring layer 22 connected to the through via hole 3.

  With reference to FIGS. 7 and 8, the case where the through-via hole 3-1 is spotted and the stub 35-1 is shortened will be described.

  When the cutting edge of the conductive drill 11 comes into contact with the through-via hole 3, the ammeter 13 detects a current. After the current is detected, the cutting edge moves to the current detection layer 16- 1, the current detection layer 16-1 is spotted, and the connection between the current detection layer 16-1 and the through via hole 3-1 is disconnected. The control unit 12 performs control for determining the counterbore depth and causing the conductive drill 11 to advance to a desired depth, so that variations in the counterbore depth between the layers can be absorbed, and the counterbore depth can be increased with high accuracy. You can control it.

  The disconnection can be detected by a change in current value, a change in resistance value, or the like.

  A multi-layer printed wiring board 35a having a short stub 35-2 as shown in FIG. 8 can be manufactured by sitting on the through via hole 3-1 by the above-described method.

  Further, by setting the reference position (offset value) of the conductive drill 11 as a point in contact with the through via hole 3, the current detection layer 16 can be used as a plating remaining detection layer of the through via hole 3.

  This is because, in the process after passing through the through via hole 3, the electrical connection between the current detection layer 16 and the through via hole 3 is measured using an inspection jig, a flying probe tester, or the like, and a short state is detected. This is because it becomes proof that the plating residue exists.

  As described above, the multilayer printed wiring board 1, 31, 35 is provided with the current detection layer 16 dedicated to the conduction between the wiring layer and the through via hole 3, and the cutting edge of the conductive drill 11 is conducted to the current detection layer 16. By controlling the counterbore depth of the stubs 2, 32, 35-1 of the through-via hole 3 on the basis of the contact with the through-via hole 3, the stub can be seated with high accuracy. The capacitance due to the length of the stub of the through via hole 3 for connecting each predetermined layer of the inner layer can be shortened, so that reflection due to impedance mismatch, signal delay, waveform rounding Can be prevented.

It is a schematic block diagram which shows the stub spot facing apparatus of the multilayer printed wiring board of this invention. It is a figure which shows the detail of a connection with the ammeter in FIG. 1, an electroconductive drill, and a multilayer printed wiring board. It is a figure for demonstrating the contact with the electroconductive drill and multilayer printed wiring board in FIG. It is a figure which shows the multilayer printed wiring board of the state which gave the stub counterbore process to the multilayer printed wiring board shown in FIG. It is a figure which shows the multilayer printed wiring board which provided the electric current detection layer in the wiring layer following the top layer, and the wiring layer before a bottom layer. It is a figure which shows the multilayer printed wiring board of the state which gave the stub counterbore process from the top layer side and the bottom layer side to the multilayer printed wiring board shown in FIG. It is a figure which shows the multilayer printed wiring board provided in each wiring layer adjacent to the power supply wiring layer connected to a penetration via hole with a current detection layer. It is a figure which shows the multilayer printed wiring board of the state which gave the stub counterbore process to the multilayer printed wiring board shown in FIG. It is a figure which shows the manufacturing process of a multilayer printed wiring board. It is a figure which shows the conventional multilayer printed wiring board. It is a schematic block diagram which shows the stub counterbore apparatus of the conventional multilayer printed wiring board.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 1a Multilayer printed wiring board 2, 2a Stub 3, 3-1 Through-via hole 6, 106 NC machine 8, 108 Dummy plate 9, 109 Stage 11 Conductive drill 12 Control part 13 Ammeter 14 Z direction 16, 16- DESCRIPTION OF SYMBOLS 1 Current detection layer 17 Current path 20 Top layer 21 Bottom layer 31, 31a Multilayer printed wiring board 32, 32a Stub 35, 35a Multilayer printed wiring board 35-1, 35-2 Stub 40, 40a Multilayer printed wiring board 42, 42a Stub 50 Stub counterbore device for multilayer printed wiring board 101 Multilayer printed wiring board 102 Stub 103 Through-via hole 104 PKG
105 LSI (Large Scale Integrated Circuit)
107 Drill H Distance from stage

Claims (12)

A substrate; a plurality of wiring layers formed on the substrate via an insulating layer; a via hole penetrating the substrate and provided with a conductive film; and a current detection layer electrically connected to the via hole in the wiring layer And the current detection layer is provided exclusively for detecting contact between the tool that sits on the stub of the via hole and the via hole. 2. The multilayer printed wiring board according to claim 1, wherein the current detection layer is provided on one or both of a wiring layer next to the top layer and a wiring layer before the bottom layer. 2. The multilayer printed wiring board according to claim 1, wherein the current detection layer is provided in a wiring layer adjacent to a power supply wiring layer or a ground wiring layer connected to the via hole. Numerical control provided with the stage which mounts the multilayer printed wiring board of any one of Claim 1 thru | or 3 via a dummy plate, and the conductive drill for sitting down the stub of the said via hole of the said multilayer printed wiring board A control unit that controls the numerical control machine, and a detection unit that detects contact between the conductive drill and the multilayer printed wiring board, and the detection unit detects contact at the current detection layer. A stub counterbore device for a multilayer printed wiring board, characterized by comprising: 5. The multilayer printed wiring board stub spot facing device according to claim 4, wherein the detection unit is connected to the control unit, the current detection layer, and the conductive drill. 6. The multilayer printed wiring board stub spot facing device according to claim 4, wherein the detection unit includes a current detection unit or a resistance detection unit. The control unit is configured to determine a counterbore depth using the position where the detection unit detects contact between the conductive drill and the multilayer printed wiring board as a reference position in the counterbore direction of the stub, and the numerical control machine 5. The stub counterbore device for a multilayer printed wiring board according to claim 4, further comprising means for controlling the counterbore depth of the stub. Numerical control provided with the stage which mounts the multilayer printed wiring board of any one of Claim 1 thru | or 3 via a dummy plate, and the conductive drill for sitting down the stub of the said via hole of the said multilayer printed wiring board A control unit that controls the numerical control machine, and a detection unit that detects contact between the conductive drill and the multilayer printed wiring board, and the detection unit detects contact at the current detection layer. A stub spot facing method for a multilayer printed wiring board. 9. The method according to claim 8, wherein the detection unit is connected to the control unit, the current detection layer, and the conductive drill. The stub spotting method for a multilayer printed wiring board according to claim 8 or 9, wherein the detection unit includes current detection means or resistance detection means. The control unit determines a counterbore depth using the position where the detection unit detects contact between the conductive drill and the multilayer printed wiring board as a reference position in the counterbore direction of the stub; and the numerical control machine And a step of controlling a counterbore depth of the stub according to claim 9. 9. The multilayer printed wiring board according to claim 8, wherein the via hole is formed, a circuit pattern is formed, a solder resist layer is provided, the multilayer printed wiring board is mounted on the stage, and a stub is spotted. Stub spot facing method for multilayer printed wiring boards.

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