JP6485774B2 - Back drill processing method and substrate processing apparatus for multilayer printed wiring board - Google Patents

Description

  The present invention relates to a back drill processing method for a multilayer printed wiring board and a substrate processing apparatus suitable for carrying out the processing method.

  2. Description of the Related Art Conventionally, with the demand for ultra-high speed control in electronic equipment, printed wiring boards have been made multilayered and densified. In such a multilayer printed wiring board, for example, in order to mount an electronic component or to connect between printed wirings that have become multilayered, a through hole (through hole) is provided, and a conductive plating having a predetermined thickness is provided there. Has been given. For example, as shown in FIG. 2, a front conductor layer 107 and a rear conductor layer 108 made of copper foil are provided on the upper and lower sides, and finally a wiring pattern is etched on the front conductor layer 107 and the rear conductor layer 108. In the substrate 101 to be applied, the first inner conductor layer 102 is provided between the first insulating layer 103 and the second insulating layer 104, and the second inner conductor layer 102 is provided between the second insulating layer 104 and the third insulating layer 105. When the first inner conductor layer 102 is used as a desired conductor layer and the back conductor layer 108 is connected, a through hole penetrating the upper and lower sides of the substrate 101 itself is provided, and conductive plating is provided there. As a result, a plated portion 110 having a predetermined thickness is formed in the hole portion 109 penetrating in the vertical direction of the substrate 101. The plated portion 110 connects the first interior conductor layer 102 that is required to be connected to the back conductor layer 108, but as it is, an excess length through hole portion (hereinafter referred to as “extra length portion”). Will remain to the surface conductor layer 107.

When the surplus portion remains, for example, in the case of high-speed transmission, the control frequency becomes several GHz or more, and reflection or attenuation occurs in the surplus length portion. Therefore, the substrate 101 itself is evaluated as a defective product. For this reason, when removing the surplus length portion, it is necessary to perform back drilling to remove the excess plating portion 110 and shorten the surplus length portion as much as possible.

  As described above, in this back drilling process, the remaining surplus portion causes problems such as noise, and therefore, the plated portion 110 can be removed to the maximum, that is, until the surplus length portion becomes zero. On the other hand, since the thickness of the first inner conductor layer 102 sandwiched between the insulating layers is 12 to 25 μm, it is possible to ensure the back conductor layer 108 and the first inner conductor layer 102. In order to maintain a smooth connection, it was necessary to stop the back drilling process immediately before the first interior conductor layer 102. For this reason, precise control of the depth of back drilling was required, but in reality, the tilting and bending of the processing table itself of the processing equipment, the error in the thickness of the individual lower plate used during processing, and the individual substrate It is difficult to accurately control the depth of the back drilling process due to a plurality of factors such as an error in the thickness of the substrate base plate before being cut out or a plurality of substrates and an error caused by the measuring apparatus. Therefore, when a substrate manufacturer requests a substrate processing company to process a substrate, taking into account errors that may occur during back drilling, the length of the remaining surplus portion is not set to zero, I asked for a little length as the remaining cost.

  In this way, although there is a slight allowable range as the length of the surplus portion remaining at the time of substrate processing, processing is performed as close to the numerical value as accurately as possible even within the slight allowable range. Therefore, a method using a probe has been used for accurate control of the depth of back drilling. That is, with the tip of the probe as a reference position (a point where the Z-axis coordinate position is 0), in the substrate processing apparatus incorporating the spindle, the tip position of the drill installed at the rotor tip of the spindle is the same as the tip position of the probe The height (M) from the reference position of the probe to the substrate is calculated by measuring the height position of the substrate placed on the processing table with the probe. In addition to the thickness of the substrate itself, the reference surplus length (Lnd), which is the design length of the plated portion from the desired conductor layer to the surface conductor layer 107, and the length of the remaining design allowance in the plated portion Since (td) is determined in advance as a design value by the board manufacturer, the reference back drill depth (L2d) is obtained by subtracting the remaining allowance length (td) from the reference surplus length (Lnd). The sum of the distance (M) from the reference position of the probe to the substrate measured by the probe and the reference back drill depth (L2d) is the drill moving distance. Therefore, back drilling has been performed by lowering the drill until the calculated moving distance is reached.

However, when the depth of back drilling is controlled by this method, accurate control has been difficult for the following reasons. That is, first, there is a positional deviation between the tip position of the probe and the drill tip position installed on the spindle. Since the probe is separate from the drill, it is extremely difficult to make the tip position completely coincide with each other, and generally an error of about ± 20 μm is unavoidable. Second, in the processing table of the substrate processing apparatus used for back drilling, the processing table height itself varies for each processing position. In many substrate processing apparatuses, when the height of the processing table was measured at a plurality of positions on the processing table, it was found that the processing table itself generally had a height variation of about ± 50 μm at each processing position. did. Third, the thickness of the lower plate used for processing also varies with respect to the set thickness. When the thickness of many lower plates was measured, it was found that there was a variation of about ± 20 μm. Fourth, the multilayer printed wiring board itself has variations with respect to the set thickness. In general, multilayer printed wiring boards are formed by alternately heating and compressing resin layers and conductor wiring layers, so there are design dimensions for the thickness of each layer and the overall plate thickness itself. However, in the substrate as an actual product, naturally, the thickness of each layer as well as the thickness of the substrate itself varies. Actually, when the error from the design value was measured in a large number of substrates, it was found that there was approximately ± 30 μm of variation in substrate thickness. In particular, in a multilayer printed wiring board, a conductor layer to be a wiring is not evenly arranged between all the resin layers, but, for example, 20 conductor layers are provided in a certain part of one board. On the other hand, in other parts, only eight conductor layers are arranged, and the conductor layers are unevenly arranged in one board, so that in the same one board, Even if it exists, there existed a tendency for the board | plate thickness to become thicker in the part in which the 20 conductor layers were provided compared with the part in which only the 8 conductor layers were provided.
As described above, at the time of back drilling, an error of maximum ± 120 μm is generated due to these variations. Therefore, in order to eliminate the variation, even if it is attempted to eliminate the variation in the height of the processing table, which occupies a large proportion of each variation, advanced and precise technology is required for maintenance and repair. In spite of excessive time and cost, the variation can be reduced only to an error of about ± 20 μm at most. As a result, even with that much time and cost, there is still an error of about ± 90 μm, and the depth control of back drilling can be accurately controlled with an error of about ± 50 μm with respect to the reference remaining amount that is the design value. It was difficult to answer the specifications required by customers (substrate manufacturers) who wanted to.

For this reason, in order to control the back drilling depth more accurately, a coupon that should be referred to as a test is provided outside the wiring area of the board as shown in JP 2014-33006 and is obtained by back drilling. Based on the obtained depth information, a method for controlling the processing depth of back drilling to a desired position has been proposed.

However, since a coupon must be installed separately from the through-hole that actually performs back drilling, it is still difficult to accurately and precisely control the processing depth of back drilling, and the substrate as a product There was a drawback of increasing the manufacturing cost.

On the other hand, as described above, when a probe is provided separately from the drill itself and the height of the substrate is measured, a positional deviation occurs between the probe tip position and the drill tip position installed on the spindle. When back drilling is performed on the substrate, an error of about ± 20 μm occurs only by the positional deviation. Therefore, in order to eliminate the error, a method for detecting the depth position in the substrate with a direct drill as shown in Japanese Patent Application Laid-Open No. 2014-187153 and controlling the processing depth of the back drilling process based on the position. Has been proposed.

However, in this method, since the voltage detection layer must be provided separately from the desired internal wiring layer, not only the processing depth of the back drilling process can be controlled accurately and precisely, but also the product As a result, the manufacturing cost of the substrate increases.

JP 2014-33006 A JP 2014-187153 A

  The problem to be solved is that in the back drill processing of a multilayer printed wiring board, the processing depth needs to be controlled accurately and precisely, and the processing is performed by a probe separate from the spindle drill in the substrate processing apparatus. The height position of the substrate at the position is measured, and the back drilling depth control is performed based on the thickness of the substrate itself, the reference extra length (Lnd), and the reference remaining margin (td) determined as design values. And the positional deviation between the position of the drill itself and the position of the probe and the difference between the design value of the substrate and the actual thickness makes accurate and precise control of the processing depth difficult. Depending on the method, it is not only difficult to accurately and precisely control the processing depth, but also increases the production cost of the substrate as a product. .

  The invention of the present application firstly minimizes measurement errors caused by the inclination and deflection of the processing table itself of the substrate processing apparatus, and the inclination and deflection of the lower plate itself used for processing, and multi-layer printed wiring. Processing during back drilling on the premise that there is a subtle difference in thickness and a difference in the height position of the conductor layer for each individual substrate in the substrate and also in a single substrate. Deviation of the actual height position with respect to the reference surplus length, which is the design value, and deviation of the actual thickness with respect to the design value, in the thickness of the substrate itself including the conductor layer, in the interior conductor layer subject to depth control Using this correlation, the descent distance information detection mechanism by the drill itself and the detected descent distance information are accumulated and calculated. It is intended to enable accurate and precise machining depth control in the back drilling. Secondly, the present invention provides a machining apparatus having a control mechanism that enables accurate and precise machining depth control in back drilling, and further provides a back drill machining control method using the machining apparatus. .

The present invention is a processing depth control mechanism using a computer for controlling a descending distance of a spindle drill during back drilling in a substrate processing apparatus capable of performing back drill processing on a multilayer printed wiring board. And
While having a descending distance information detection mechanism that detects descending distance information by the spindle drill coming into contact with the detection object,
It has a storage medium on which each of the following 1 to 5 position information is recorded,
1. Numerical information on the design substrate thickness, the reference surplus length and the design remaining allowance length, the predetermined thickness of the plated layer applied to the hole of the through hole, and the angle of the tip angle of the drill,
2. On the lower plate placed on the processing table of the substrate processing apparatus and having at least the upper surface as a conductor layer, the measurement points defined by the following settings and the coordinate position information on the plane of each area area,
A plurality of areas are divided in a grid pattern, and each measurement point defined by the same standard for each area, or each subarea divided into a grid pattern by the same standard for each area. One measurement point defined by the same standard.
3. Height position information for each measurement point measured by the descent distance information detection mechanism by lowering the spindle on which the drill for performing back drilling is lowered with respect to each measurement point,
4). Each of the multilayer printed wiring boards placed on the lower plate on the processing board of the substrate processing apparatus or each of the mother boards before cutting out the plurality of multilayer printed wiring boards (hereinafter simply referred to as “mother boards”). Coordinate position information on the plane of back drill processing position,
5. Height position information for each back drilling position measured by the descending distance information detection mechanism by lowering the spindle to each back drilling position of the substrate or mother board,
From the coordinate position information for each area and the coordinate position information of the back drilling position existing on the multilayer printed wiring board or its mother board, the multilayer printed wiring board or its mother board is placed on the lower board during back drilling. In this state, an extraction mechanism that extracts a back drilling position existing in each coordinate value range of each area of the lower plate,
Having a calculation mechanism for calculating the individual back drilling depth L2c based on the following formula,
Based on the calculated individual back drilling depth L2c, the processing depth of back drilling in the substrate processing apparatus is automatically controlled.
L2c = Lnd × (L2m−αave) / L2d−td + angle tan1
Lnd = design surplus length L2m = extracted as existing in the coordinate value area of each area of the lower board of the multilayer printed wiring board or its mother board placed on the lower board on the processing table Measured height at each back drilling position
αave = average value of measured heights of measurement points for each area of the lower plate on the processing table.
L2d = Designed multilayer printed wiring board thickness td = Left angle angle of design margin tan1 = Predetermined thickness of plated layer of through hole × tan {(180 degrees−angle of tip angle of drill) ÷ 2}

This machining depth control mechanism has the following advantages.
First, the lower plate is divided into areas, the measurement points are extracted for each area, and the average height of the area is calculated from the height position information of the measurement points. The back drilling position of the substrate existing at the position corresponding to the area is extracted, and the average value of the height of the lower plate in the area is subtracted from the measured height (that is, L2m− αave) can be used to accurately detect the thickness of the substrate itself at the backdrilling position. The relationship between the detected thickness of the substrate itself at the back drilling position and the design thickness of the substrate itself depends on the actual thickness position of the desired conductor layer on the substrate and the design thickness. Recognize by correcting the actual thickness position of the desired conductor layer, which cannot be measured without destroying the board itself, by correcting it according to the correlation because it is correlated with the relationship between the position and the difference. Therefore, more precise back drilling can be performed in accordance with different errors at each back drilling position. Furthermore, the height information of the back drilling position of the board is determined by the tip angle of the drill that performs back drilling, so that the inclined part of the drill is on the inside of the plated part applied to the hole part of the through hole with respect to the hole part. Detected by contact. On the other hand, the upper end of the remaining margin is cut with a long outer side and a shorter inner side with respect to the hole, and the length of the standard remaining margin for design is defined by the longer outer side. Is done. Therefore, the length of the plated portion that is the extra length to the desired conductor layer is calculated, and the position obtained by subtracting the length of the design reference remaining allowance from the length is defined outside the plated portion. It becomes. However, in order to perform back-drilling up to that position, there is an inclined part at the tip of the drill, and as described above, when measuring the height position of the substrate, the inclined part of the drill is applied to the hole of the through hole. Since it is detected that the plated portion is in contact with the inside of the hole portion, it is necessary to process the inside of the plated portion deeper than the position outside the plated portion. That is, a deviation of the height position between the inner side and the outer side with respect to the thickness of the plated portion occurs, and the deviation of the height is corrected by calculating the angle tan1. As a result, even if the remaining allowance as a design value that remains in the through hole after back drilling is set short, the length of the remaining allowance can be accurately realized. Therefore, it is no longer necessary to determine the remaining allowance based on a large error, and by setting the remaining allowance itself short and accurately realizing its dimensions, it is possible to suppress the occurrence of problems such as noise caused by the remaining excess length can do. In addition, this processing depth control mechanism can be configured by adding a storage medium, an extraction mechanism, and a calculation mechanism to a descent distance information detection mechanism using an existing spindle drill. A substrate processing apparatus having a detection mechanism can be modified at low cost.
Secondly, since it is a separate body from a drill such as a probe, it does not detect the descending distance information, but detects the descending distance information with the drill itself used for back drilling. It is possible to prevent the occurrence of an error due to the deviation of the position of the zero point that is the origin.
Third, since control is performed by a computer on the processing apparatus side, it is not necessary to perform a special coupon or wiring on the multilayer printed wiring board side, and the manufacturing cost of the board itself can be suppressed.

  In addition, the descent distance information detection mechanism specifically includes at least a high-frequency AC power source, a bypass circuit including a reactor, and a high-frequency current transformer, and one of the outputs of the high-frequency AC power source is connected to the casing, and the other Is connected to a spindle that is insulated from the casing through the input winding of the current transformer, and a bypass circuit having a reactor is connected between the spindle and the casing. When the spindle rotor drill contacts the object to be detected, which is a conductor, a high-frequency current from a high-frequency AC power source passes through the current transformer to the spindle, and further through a capacitance between the conductor and the conductor layer. By flowing into the high-frequency AC power source, a current is generated on the output side of the current transformer, and the change in the current is detected by the detector to recognize the descent distance information of the drill. They are intended.

  As a result, when determining whether the spindle tip of the spindle is in contact with the object to be detected, if a disturbance factor is unlikely to occur, or if the disturbance factor has little effect on the determination accuracy even if it occurs, such as a filter When a configuration for eliminating the disturbance factor is separately provided, a descent distance information detection mechanism having sufficient judgment accuracy is configured, and in addition to an intermediate connection between the current winding input winding and the spindle. In this case, by providing a bypass circuit connected to the housing, the spindle is no longer a so-called floating metal, and there is no need to provide a protective function for preventing electric shock. And further, current such as harmonic current flows to the housing through the drill, and damage to the metal surface of the drill and the coating on the drill surface due to the current can be prevented, and the drill can be used for a long time. .

Moreover, as a different configuration of the descending distance information detecting mechanism, the descending distance information detecting mechanism includes a high-frequency AC power source, a bypass circuit including a reactor, a cancel circuit, and an input winding connected in reverse winding with the same number of turns. The cancel circuit has a reverse bypass circuit having a reactor having the same capacitance as the bypass circuit, and a capacitor arranged in series. In addition, a plurality of sets of capacitors and switches are arranged in parallel to form a single simulation circuit, and when a spindle insulated from the housing is energized, each phase of the spindle motor is There are a plurality of sets of simulation circuits corresponding to the capacitance generated between the winding and the spindle main body and between the spindle main body and the casing, respectively, and the reverse bypass circuit and the plurality of simulation circuits are provided. Are arranged in parallel, and the detection object is fixed on a processing table in the housing of the substrate processing apparatus, and one of the outputs of the high-frequency AC power supply is connected to the housing, and the other is the current transformer. The other end of the input winding is connected to the spindle body and connected to the housing via a bypass circuit, and the other end of the cancellation winding is connected to the reverse bypass. One end of the circuit and one end of each simulation circuit are connected in parallel, the other end of the reverse bypass circuit is connected to the case, and the simulation corresponding to the capacitance generated between the case and the spindle insulated from the spindle body The other end of the circuit is connected to the housing, and the other end of the simulation circuit corresponding to the capacitance generated between the spindle body and the motor winding is connected to the winding of each phase of the spindle motor. Simulated circuit switch to be approximately equal to capacitance By adjusting, the direction of the magnetic flux generated in the current transformer is canceled by the current flowing in the input winding and the cancellation winding, so that the change in current caused by the contact between the drill tip of the spindle and the object to be detected can be reduced. By detecting the change in the current output from the current transformer with the detector, the descent distance information of the drill is recognized.

  Further, as a further different configuration of the descending distance information detecting mechanism, the descending distance information detecting mechanism includes a high frequency AC power source, a high frequency current transformer having two input windings and one or more output windings having the same number of turns. And having a simulated substrate circuit in which a plurality of capacitors and switches arranged in series are arranged in parallel, and one of the high-frequency AC power supply outputs is connected to the housing Are connected to one terminal of the simulated board circuit, and the other is connected to the detection object and the other terminal of the simulated board circuit via two input windings of the current transformer, respectively. By adjusting the switch of the simulated circuit board circuit so that the capacitance generated between the object to be detected and the object to be fixed on the processing table in the case is substantially equal to the input winding current, Magnetic field generated in current transformer By detecting the change in current caused by the contact between the spindle tip of the spindle and the object to be detected by the detector as the change in current output from the current transformer, Recognize

By using the descending distance information detection mechanism having these configurations, it becomes easier to accurately and precisely measure the height position by the spindle drill itself, thereby controlling the back drilling depth more precisely. Will be able to. As a result, the length of the remaining margin remaining in the through hole after back drilling can be minimized.

A substrate processing apparatus comprising the processing depth control mechanism described above.

On the other hand, as a back drill processing method to be performed using any one of the substrate processing apparatuses,
In addition to recording the position information and the like described in 1 to 5 below on a storage medium,
1. Numerical information on the design substrate thickness, the reference surplus length and the design remaining allowance length, the predetermined thickness of the plated layer applied to the hole of the through hole, and the angle of the tip angle of the drill,
2. In the lower plate placed on the processing table of the substrate processing apparatus and having at least the upper surface as a conductor, the measurement point determined by the following settings and the coordinate position information on the plane of each area area,
A plurality of areas are divided in a grid pattern, and each measurement point defined by the same standard for each area, or each subarea divided into a grid pattern by the same standard for each area. One measurement point defined by the same standard.
3. Height position information for each measurement point measured by the descent distance information detection mechanism by lowering the spindle on which the drill for performing back drilling is lowered with respect to each measurement point,
4). Each of the multilayer printed wiring boards placed on the lower plate on the processing board of the substrate processing apparatus or each of the mother boards before cutting out the plurality of multilayer printed wiring boards (hereinafter simply referred to as “mother boards”). Coordinate position information on the plane of back drill processing position,
5. Height position information for each back drilling position measured by the descending distance information detection mechanism by lowering the spindle to each back drilling position of the substrate or mother board,
From the coordinate position information for each area and the coordinate position information of the back drilling position existing on the multilayer printed wiring board or its mother board, the multilayer printed wiring board or its mother board is placed on the lower board during back drilling. In the state, after extracting the back drill processing position existing in each coordinate value area of each area of the lower plate,
Based on the individual back drill depth L2c automatically calculated based on the following formula, the processing depth of the back drill processing in the substrate processing apparatus is automatically controlled.
L2c = Lnd × (L2m−αave) / L2d−td + angle tan1
Lnd = design surplus length L2m = extracted as existing in the coordinate value area of each area of the lower plate of the multilayer blind wiring board mounted on the lower plate on the processing table or its mother board Measured height at each back drilling position αave = average value of measured height of measurement points for each area of the lower plate on the processing table L2d = design multilayer printed wiring board thickness td = remaining design margin Length angle tan1 = predetermined thickness of the plated portion layer of the through hole × tan {(180 degrees−angle of the tip angle of the drill) ÷ 2}

By using this substrate processing apparatus as described above, it becomes possible to perform more accurate and precise processing according to the back drill processing position of each substrate without incurring extra manufacturing cost, and in the through hole after back drill processing Even if the remaining allowance as the remaining design value is set short, the remaining allowance can be accurately realized. Therefore, it is no longer necessary to determine the remaining allowance based on large errors, and by setting the remaining allowance itself short and accurately realizing its dimensions, it is possible to suppress the occurrence of problems such as noise arising from the extra length. Can do.
Although the plated portion is cut as the tip of the drill advances through the hole of the through hole, it is the inclined portion that cuts the plated portion in the drill, not the top corner. Therefore, not only is there a gap between the position of the tip corner of the drill and the position of the inclined part of the drill that defines the remaining margin of the extra length, but the upper end of the remaining margin is outside the hole. Is longer and the inner side is shorter and cut. Therefore, the length of the reference remaining allowance is defined at the tip position on the outer side with respect to the hole portion. This is corrected by calculating the angle tan1 for a predetermined thickness. That is, the processing depth of back drilling is corrected by calculating the numerical value calculated by a predetermined thickness of the plated portion of the through hole × tan {(180 degrees−the angle of the tip angle of the drill) / 2}. This makes it possible to control the height more precisely.

Furthermore, as a back drill processing method to be performed using any one of the substrate processing apparatuses,
In addition to recording the location information described in 1 to 5 below on a storage medium,
1. Numerical information on the design substrate thickness, reference surplus length and design remaining allowance length, and the radius of the hole of the through hole and the tip angle of the drill hole for back drilling before the plating portion is provided,
2. In the lower plate placed on the processing table of the substrate processing apparatus and having at least the upper surface as a conductor, the measurement point determined by the following settings and the coordinate position information on the plane of each area area,
A plurality of areas are divided in a grid pattern, and each measurement point defined by the same standard for each area, or each subarea divided into a grid pattern by the same standard for each area. One measurement point defined by the same standard.
3. Height position information for each measurement point measured by the descent distance information detection mechanism by lowering the spindle on which the drill for performing back drilling is lowered with respect to each measurement point,
4). Each of the multilayer printed wiring boards placed on the lower plate on the processing board of the substrate processing apparatus or each of the mother boards before cutting out the plurality of multilayer printed wiring boards (hereinafter simply referred to as “mother boards”). Coordinate position information on the plane of back drill processing position,
5. With the aluminum upper plate having a known thickness being placed on the substrate or the mother plate, each spindle measured by the descending distance information detection mechanism is lowered by lowering the spindle to its back drilling position. Height position information for each back drilling position,
From the coordinate position information for each area and the coordinate position information of the back drilling position existing on the multilayer printed wiring board or its mother board, the multilayer printed wiring board or its mother board is placed on the lower board during back drilling. In the state, after extracting the back drill processing position existing in each coordinate value area of each area of the lower plate,
Based on the individual back drill depth L2c automatically calculated based on the following formula, the processing depth of the back drill processing in the substrate processing apparatus is automatically controlled.
L2c = Lnd × (L2m1-αave-tAL) / L2d-td + tAL + angle tan2
Lnd = design surplus length L2m1 = a state in which an aluminum upper plate having a known thickness is placed and fixed on the multilayer printed wiring board placed on the lower plate on the processing table or its mother plate. , Measured height at each back drilling position extracted as existing in the coordinate value range for each area of the lower plate αave = the measured height of the measurement point for each area of the lower plate on the processing table Average value L2d = Designed multilayer printed wiring board thickness td = Left length of design tAL = Specified thickness angle of aluminum upper plate tan2 = Radius of through hole before plating portion × tan {(180 Degree-angle of drill tip angle) ÷ 2}

This prevents the following errors from occurring and enables precise back drilling. That is, first, since the hole portion of the through hole exists and is opened at the back drilling position, the conductor layer no longer exists in the hole portion portion of the surface of the substrate. Since the tip is a tip corner apex having a tip angle, there is a possibility that a misalignment between the center of the hole of the through hole and the center of the drill that performs the back drilling may occur when starting back drilling. And if the misalignment occurs, the substrate height at the back drilling position will not be measured accurately, so the actual height position and error will occur in the numerical value itself, and the calculation is based on that numerical value. An error is caused in the processing depth of each individual back drill. Therefore, even if the misalignment occurs, in order not to generate such errors, the height position including the aluminum upper plate placed on the substrate is measured, and finally the aluminum upper plate The thickness is corrected by calculation. Secondly, as described above, since the through-hole hole portion exists and opens at the back drilling position, the drill may skew and cause misalignment even during back drilling. is there. If the misalignment occurs, when the back drilling depth is controlled, the length of the remaining portion of the plated portion does not conform to the control and an error occurs. Therefore, in order to prevent the skew of the drill during the back drilling process, the back drilling process is performed with the aluminum upper plate placed on the substrate. Thirdly, the height of the drill including the aluminum top plate placed on the substrate is measured by contacting the top corner of the drill with the aluminum top plate, whereas the tip of the drill is a through hole. Although the plated portion is cut by advancing the hole portion, the plated portion is cut in the drill by the inclined portion, not the tip corner apex. Therefore, the position of the tip corner of the drill and the remaining allowance of the extra length (the upper end of the remaining allowance is cut with the outer side being longer and the inner side being inclined at a shorter angle. This is defined at the tip position on the outer side with respect to the hole portion). This deviation corresponds to the angle tan2, that is, the radius of the through hole before providing the plated portion × tan {(180 degrees−the angle of the tip angle of the drill) ÷ 2}. In the above method, the deviation is calculated. By correcting, the processing depth of back drilling can be controlled accurately and precisely.

Furthermore, in addition to the back drilling method, an aluminum upper plate having a known thickness is mounted on the multilayer printed wiring board or the mother board placed on the lower board on the processing table of the board processing apparatus. In addition, an insulating upper plate that can be cut by a spindle is placed thereon.

This prevents the occurrence of errors as described below, and enables continuous and more accurate back drilling. In other words, the inner surface of the through-hole for back drilling is plated to form a plated portion, so when back drilling is performed, thread-like facets are generated from the conductive plated portion and It will adhere. Therefore, when the height of the lower plate or the substrate is measured as a pre-preparation for back drilling using the drill to which the face is attached, the attached conductive face causes a measurement error. . When the insulating upper plate is placed on the aluminum upper plate, in the next back drilling process, a face is generated from the insulating upper board, and the conductive face attached to the drill is pushed up from the drill. It will automatically leave. Thereby, even if the height of the lower plate or the substrate is continuously measured with this drill, it is possible to prevent the occurrence of an error due to the facets of the plated portion.

  The processing depth control mechanism for back drilling according to the first aspect of the invention can accurately and precisely control the back drilling processing depth for the substrate at a low cost. In addition to eliminating the problems, the substrate itself can be manufactured at a low cost. In addition, the processing depth control mechanism can be added to a substrate processing apparatus having an existing descent distance information detection mechanism, and a substrate processing apparatus that enables accurate and precise back drill processing at low cost. It also has the effect that it can be provided.

  The machining depth control mechanism for back drilling according to the invention described in claim 2 enables precise machining depth control by a descent distance information detection mechanism with a simple configuration and at the same time ensuring safety against electric shock. The drill will not lose its life.

The machining depth control mechanism for back drilling according to the invention described in claims 3 and 4 eliminates disturbance factors in the descending distance information detection mechanism, and enables more precise machining depth control. It has an excellent effect.

  The substrate drilling apparatus according to the invention of claim 5 and the back drilling method according to the invention of claim 6 both control the processing depth of the back drilling process on the substrate at low cost accurately and precisely, In addition to eliminating problems such as noise caused by the processed substrate, the substrate itself can be manufactured at low cost.

  The back drilling method according to the seventh aspect of the invention has an excellent effect of reducing the measurement error caused by the misalignment at low cost and enabling more precise processing depth control more easily.

  The back drilling method according to the invention described in claim 8 has an excellent effect that enables precise back drilling to be continuously performed at low cost.

FIG. 1 is a schematic diagram showing a configuration of a substrate processing apparatus including the processing depth control mechanism shown in Embodiment 1 of the present invention. FIG. 2 is a schematic diagram showing a structure of a substrate as a detection target. FIG. 3 is a schematic diagram illustrating a division state of areas and the like by virtual lines on the lower plate. FIG. 4 is a partially enlarged view of the drill tip portion in the back drilling process according to the first embodiment, and is a schematic diagram illustrating a dimensional situation. FIG. 5 is a further enlarged view of FIG. FIG. 6 is a schematic diagram illustrating a dimensional situation during back drilling in the second embodiment. FIG. 7 is a partially enlarged view of FIG. It is a schematic diagram which shows the circuit of a spindle and a descent | fall distance information detection mechanism except the CNC control circuit in the board | substrate processing apparatus which comprises the processing depth control mechanism shown in the present Example 3. It is a schematic diagram which shows the circuit of a spindle and a descent | fall distance information detection mechanism except the CNC control circuit in the board | substrate processing apparatus which comprises the processing depth control mechanism shown in the present Example 4.

The drill itself detects descent distance information for the purpose of back drilling at low cost and improving the control accuracy of the processing depth to minimize the remaining allowance of the through hole that causes problems such as noise. In addition to using the descent distance information detection mechanism, the measurement location is determined so as to eliminate the effects of errors caused by tilting and bending of the work table itself and the lower plate, and further errors with design values existing on the individual substrates themselves, Realized by more accurately grasping the position of the desired conductor layer by applying the measured numerical value to a certain formula and controlling the back drilling distance accurately and precisely to the calculated processing depth It is. And this formula says that the relationship between the design thickness position of the desired conductor layer inside the substrate and the actual thickness position correlates with the relationship between the design thickness of the substrate itself and the actual thickness. Based on knowledge. In this case, if the accuracy in processing depth control is to be increased, the height position of the position where the back drilling of the substrate is performed and the position of the lower plate vertically below the position where the back drilling is performed are measured. Therefore, it is sufficient to calculate the thickness of the substrate at the back-drilling position, but it takes time and cost unnecessarily. Therefore, the lower plate is divided into certain areas, and the average value is calculated. By determining the thickness of the substrate, the thickness of the substrate is calculated. This is intended to balance time and cost with accuracy.
Also, the purpose of preventing errors due to misalignment is achieved by back drilling the aluminum upper plate placed on the substrate, and the aluminum upper plate placed on the substrate. Thus, the problem that occurs when the back drilling is continuously performed is eliminated by placing an insulating upper plate on the aluminum upper plate.

  FIG. 1 is a schematic view showing a substrate processing apparatus A provided with a descending distance information detection mechanism K which is an embodiment according to the present invention. a is a spindle, provided on the upper side of the substrate 101 to be detected, and supported by the spindle body 1, the rotor 2 supported by the ceramic body with ceramic bearings, and the back drill supported by the rotor 2; It consists of a drill 3 used for processing. In the spindle, an air bearing may be used instead of the ceramic bearing. A is a substrate processing apparatus that performs back drilling with the spindle a. The descending distance information detection mechanism K of the spindle a (hereinafter referred to as the detection mechanism K) detects height position information of the spindle a with respect to the substrate 101 as a detection target, and is connected to the spindle a by an electric circuit. The detection device 4 is embodied. Although the present embodiment shows a case where there is one spindle a, the substrate processing apparatus is generally equipped with a plurality of spindles so that a plurality of similar substrates can be processed simultaneously. For this reason, the same number of detection devices 4 are provided corresponding to the number of the plurality of spindles. By the way, the spindle a is fixed to the beam 29 via an insulator 30, and the beam 29 is movable with respect to the casing 27 by a driving device (not shown). It is fixed to the casing 27 of the apparatus A so as to be movable in the X-axis direction (lateral direction on the paper). In the Z-axis direction (up and down direction in the drawing), the Z-axis drive device 31 can be individually driven. On the other hand, in the Y-axis direction (the depth direction of the drawing), the processing table 26 is movable by a driving device (not shown), so that the substrate 101 fixed thereto moves in conjunction with it. . Further, the beam 29 is electrically connected to the casing 27, and the processing base 26 is also electrically connected to the casing 27 (the conduction relationship is indicated by a dotted line connection in FIG. 1).

The spindle a incorporates a three-phase motor 22, and the three-phase motor 22 is connected to each phase via a three-phase 200 V commercial power supply V and an inverter 28.
The spindle a is connected to the housing via the bypass circuit 5 in the descending distance information detection mechanism K, and is electrically low with respect to the housing 27 with respect to the harmonics of the commercial frequency and the output voltage of the inverter 28. In contrast to the impedance, the impedance is high with respect to the frequency of the current from the high-frequency oscillator 6. Since the rotor 2 of the spindle a is supported by a ceramic bearing with respect to the spindle body 1, the spindle body 1 and the rotor 2 are insulated from each other. However, since there is a capacitance CR between each spindle body 1 and the rotor 2, it can be said that they are conducting at high frequencies (in order to show the presence of the capacitance CR in FIG. 1). The spindle main body 1 and the rotor 2 are shown by dotted lines so that they are connected via a capacitor. However, this description simply shows that a capacitance CR exists between the spindle main body 1 and the rotor 2. It is only described for the purpose of schematically representing the above, and does not mean that there are actually any connections or parts.) Similarly, there is an electrostatic capacity CS between the spindle body 1 and the beam 29 (note that the beam 29 is electrically connected to the casing 27, and therefore has the same potential as the casing 27. The electrostatic capacity CS is described between the spindle body 1 and the casing 27.) Also, the electrostatic capacity CU, CV, and CW are provided between the spindle body 1 and the motor windings 23, 24, and 25. Further, there is a capacitance CP between the lower plate upper surface copper foil layer 112 of the lower plate 111, which will be described later, and the processing table 26.
On the other hand, in the spindle a, the rotor 2 and the drill 3 are electrically connected. The casing 27 itself is grounded 32.

By the way, since the lower plate 111 itself is an insulator, it is electrically insulated from the surface of the processing table 26, but the upper surface side of the lower plate 111 is coated with a copper foil and the lower plate upper surface copper foil layer. 112, and generally the area of the lower plate upper surface copper foil layer 112 is large and the lower plate 111 is thin. Has a very large capacitance CP and becomes conductive at high frequencies.
Incidentally, in this embodiment, the lower plate 111 itself is a glass epoxy resin plate and an insulator as will be described later, but the lower plate 111 itself may be made of an aluminum plate. In that case, when detecting the descent distance information of the drill, if the tip of the drill 3 of the spindle a comes into contact with a detection target object such as a conductor, for example, the surface conductor layer 107 of the substrate 101, it occurs on the output winding 16 side of the current transformer 7. The fact that the detector 9 detects a change in current only by increasing the current is the same as when the lower plate 111 itself is an insulator.
Details of the internal structure of the substrate 101 have a multilayer structure as shown in FIG. However, in the present embodiment, the internal conductor layers and the insulating layers are two layers and three layers for the sake of simplicity of explanation, but the number of substrates that actually require back drilling is ten or more. The substrate 101 is sandwiched between three insulating layers 103, 104, 105 and the front and back conductor layers 107, 108, and a part between the first insulating layer 103 and the second insulating layer 104. The first inner conductor layer 102 and the second inner conductor layer 106 sandwiched in part between the second insulating layer 104 and the third insulating layer 105. The conductor layers 102, 106, 107 and 108 are all copper foils, and the thickness thereof is 12 to 25 μm. Each of the insulating layers 103, 104, and 105 is made of a thermoplastic resin and has a thickness of 50 to 100 μm. A through-hole 109 is formed through the surface conductor layer 107 to the back conductor layer 108, and the inner peripheral surface is a plated portion 110 plated with copper. Then, using the first inner layer conductor layer 102 as a desired inner layer conductor layer, back-drilling is performed on the hole 109 of the through hole up to the first inner layer conductor layer 102, that is, from the surface conductor layer 107 side to the first. In this case, the copper plating of the plated portion 110 provided in the hole portion 109 is scraped off by a drill having a diameter slightly larger than the diameter of the hole portion 109 of the through hole up to the immediate vicinity of the inner conductor layer 102. The purpose is to accurately and precisely control the processing depth.
In back drilling, the lower plate 111 is placed and fixed on the processing table 26, and the substrate 101 is placed and fixed thereon. The lower plate 111 is a plate made of glass epoxy resin having a thickness of 1500 μm, and a lower plate upper surface copper foil layer 112 is provided on the upper surface. Although copper foil layers may be provided on the upper and lower surfaces of the lower plate 111 or the lower plate 111 itself may be made of an aluminum plate, at least the upper surface of the lower plate 111 needs to be a conductor layer.

  On the other hand, reference numeral 4 denotes a detection device, which includes a high-frequency oscillator 6, a current transformer 7, a detection circuit 8 and a detector 9, and further includes a bypass circuit 5 and a cancellation circuit 10. The high-frequency oscillator 6 is 0.3W and is substantially zero. It is appropriate to oscillate a high frequency alternating current of 5 to 2 MHz, but here, a high frequency of 1 MHz is oscillated. The output high-frequency alternating current is connected to the casing 27 via the GND line 11, and the other output line 12 is connected between the input winding 13 and the cancel winding 14 of the current transformer 7. In the current transformer 7, the windings 13 and 14 are wound in the clockwise direction from the side designated m, and the winding end of the input winding 13 and the winding start of the cancel winding 14 are connected. . Then, both ends of the output winding 16 provided across the iron core 15 are connected to a detection circuit 8 composed of four diodes, and the detection circuit 8 is connected to a detector 9.

  On the other hand, the bypass circuit 5 is configured by connecting a reactor L and a resistor R in parallel, and one end of the circuit 5 is intermediate between the winding start end of the input winding 13 and the spindle body 1 and the other end. Is connected to the housing 27. The bypass circuit 5 has a high impedance with respect to the high-frequency current from the high-frequency oscillator 6 used for detecting the descending distance information, and is connected to the commercial power source V to be added to the inverter 28 that operates the spindle a. In order to set the wave current to have a low impedance, the inductance of the reactor L is set in the range of 50 to 100 μH. If the inductance of the reactor L is less than 50 μH, a high-frequency current used for detection flows into the bypass circuit 5, making it difficult to accurately detect contact between the drill 3 and a desired conductor layer, and conversely, 100 μH. This is because harmonic current or the like from the inverter 28 does not flow, and the effect of grounding the spindle a is reduced and it is difficult to maintain safety. In this embodiment, the inductance of the reactor L is set to 75 μH, the resistance component is set to about 0Ω, the resistance value of the resistor R is set to 200Ω, and the inductance component is set to about 0 μH.

The cancel circuit 10 includes four simulation circuits 17-1, 17-2, 17-3, 17-4 and one reverse bypass circuit 18. In each of the simulation circuits 17-1, 17-2, 17-3, 17-4, eight capacitors 20 and eight dip switches 21 are respectively arranged in series, and the capacitors 20 and dip arranged in series are connected. The switch 21 is one set, and these eight sets are arranged in parallel. These capacitors 20 have different capacities, and here, capacitors having capacities of 10 pF, 20 pF, 40 pF, 80 pF, 160 pF, 320 pF, 640 pF, and 1280 pF are used (in FIG. (The simulated circuit capacitor 20 and dip switch 21 are omitted, and only two sets are shown). One end of the simulation circuit 17-1 is connected to the winding end of the cancel winding 14 of the current transformer 7, and the other end is connected to the casing 27. One end of each of the simulation circuits 17-2 to 17-4 is connected to the U phase, V phase, and W phase of the three-phase motor 22 built in the spindle body 1, and the other end is connected to the current transformer 7. It is connected to the winding end of the cancel winding 14. The capacitance of the simulation circuit 17-1 is built in the capacitance CS between the spindle body 1 and the housing 27, and the capacitance of each simulation circuit 17-2 to 17-4 is built in the spindle body 1. The electrostatic capacities CU, CW, CV between the windings 23, 25, 24 of the three-phase motor 22 and the spindle body 1 are set so that they can be set by the dip switch 21 so as to be substantially the same. In advance, the detection target is fixed on the processing table 26 of the substrate processing apparatus A, and the capacitance CS between the spindle main body 1 and the casing 27 is set, and the three-phase motor 22 built in the spindle main body 1 is also provided. The capacitances CU, CV, and CW between the windings 23, 24, and 25 of each phase and the spindle body 1 are respectively measured, and the simulation circuits 17-1, Eight dip switches 21 of 17-2, 17-3, and 17-4 are appropriately energized. The capacitances CS, CU, CV, and CW are approximately 200 to 500 pF. In this embodiment, since a ceramic bearing is used between the spindle body 1 and the rotor 2, the electrostatic capacitance CR between them is about 200 pF, and the lower plate upper surface copper foil layer 112 and the work table on the lower plate 111. The capacitance CP between them is approximately 500 to 1000 pF although it depends on the size of the substrate 101, and in this embodiment, the one having 1000 pF was used.
On the other hand, the reverse bypass circuit 18 is formed by connecting the same reactor L ′ and resistor R ′ in the same manner as the bypass circuit 5 in parallel, and one end of the circuit 18 is at the end of the cancel winding 14 of the current transformer 7. The other end is connected to the housing 27.

In this configuration, since the drill 3 and the surface conductor layer 107 of the substrate 101 or the lower plate upper surface copper foil layer 112 of the lower plate 111 are not in contact during non-detection, the spindle motor windings 23, 24, and 25 are not in contact with each other. Even if the harmonic voltage from the inverter 28 is applied, the current flows into the casing 27 through the bypass circuit 5, so that the spindle body 1 is similar to the ground, and it is not necessary to provide a safety measure against electric shock. Therefore, when detecting the descent distance information, even if the drill 3 and the surface conductor layer 107 of the substrate 101 or the lower plate upper surface copper foil layer 112 of the lower plate 111 come into contact with each other, harmonic current flows through the drill 3 and The service life of the drill 3 is not impaired, such as damaging the coating.

Also, the detection accuracy of the descending distance information is highly accurate as follows. That is, during non-detection, current due to the high-frequency voltage from the high-frequency oscillator 6 of the detection device 4 flows to the input winding 13 of the current transformer 7, and at the same time, the capacitances CS, CU, CV, CW and the bypass circuit 5 A current flows into the input winding 13 via the reactor L, but the capacitance generated in each of the simulation boards 17-1, 17-2, 17-3, 17-4 of the cancel circuit 10 is static. Since each switch 21 has been operated in advance so as to be substantially equal to the electric capacity CS, CU, CV, CW, each static circuit board 17-1, 17-2, 17-3, 17-4 has its own static electricity. An electrostatic capacity substantially equal to the electric capacity is generated, and further, the reverse bypass circuit 18 provided with the same reactor L ′ as the reactor L in the bypass circuit 5 is provided. -2, 17 3,17-4 and through the reactor L'reverse the bypass circuit 18, the input winding 13 to flow into current and substantially the same current flows into the cancellation winding 14. Therefore, the magnetic fluxes generated in the input winding 13 and the cancel winding 14 cancel each other, the iron core 15 of the current transformer is not excited, no output current flows in the output winding 16, and the detector 9 There is no false detection of changes in current.
On the other hand, when the detection of the descending distance information is started, the spindle a is pushed down by the Z-axis drive device 31. For example, when the drill 3 comes into contact with the surface conductor layer 107 of the substrate 101, the drill 3 Using the high-frequency oscillator 6 as a power source, the electrostatic capacitance CR generated between the spindle body 1 and the rotor 2 and the lower plate 111 that conducts from the surface conductor layer 107 of the substrate 101 through the plated portion 110 of the hole portion 109 of the through hole. A high frequency current of approximately 1 MHz flows through the capacitance CP generated between the copper foil layer 112 on the plate upper surface and the processing table 26, but the current flows only in the input winding 13 and does not flow in the cancel winding 14. Since the iron core 15 of the current transformer 7 is excited by the new current and an output current is generated on the output winding 16 side, the change in the current is detected by four diodes. By detected by the detector 9 through the circuit 8, the drill 3 of the spindle a is able to find that in contact with the desired surface conductive layer 107 is a conductive layer of the substrate 101. Of course, when detecting the descending distance information, even if the drill 3 and the surface conductor layer 107 of the substrate 101 come into contact with each other, no harmonic current flows through the drill 3 and damages the coating on the surface of the drill 3. The life of the drill is not impaired.
In the case of detection of the height position of the substrate 101 placed / fixed on the lower plate 111 placed / fixed on the processing table 26 and the drill 3 for the lower plate upper surface copper foil layer 112 of the lower plate 111 When the height position is detected by contact, the mechanism for enabling accurate detection is the same as described above except that the object to be detected is different.

Thus, by providing the cancel circuit 10, the capacitances CU, CV, CW generated between the windings 23, 24, 25 of each phase of the three-phase motor 22 and the spindle body 1, and the spindle body 1 and the housing 27, a current of approximately the same amount as the current flowing into the input winding 1 of the current transformer 7 via the capacitance CS generated between the simulated currents 17-1, 17-2, 17-3, 17-4. About the current flowing into the input winding 13 by the reactor L of the bypass circuit 5 provided to prevent the harmonic current from flowing into the drill 3 of the spindle a. However, the direction of the magnetic flux generated in the current transformer 7 having the input winding 13 and the cancel winding 14 is canceled out by causing substantially the same amount of current to flow into the cancel winding 14 by the reverse bypass circuit 18. Iron core 15 of the current transformer 7 is not energized, the output winding 16 output current does not flow. In this way, by canceling out the magnetic flux generated by the current flowing into the input winding 13 of the current transformer 7, the disturbance factor to the output winding 16 side of the current transformer 7 that occurs before the detection of the descending distance information is obtained. Can be canceled. Thus, the presence or absence of contact between the drill 3 of the spindle a and the desired conductor is not a change in current, but the capacitance CR between the rotor 2 and the spindle body 1 and the lower plate upper surface copper foil layer 112 of the lower plate 111. Therefore, it can be detected by a signal “1” or “0” indicating whether or not a current has flowed through the series circuit of the capacitance CP between the machining table 26 and the determination, which facilitates the determination.

Then, the detected descent distance information and the like are recorded and extracted in the CNC control circuit S of the substrate processing apparatus A as follows, and the depth of the back drilling process is determined through the steps of further calculation. It will be controlled accurately and precisely.
That is, first, since the substrate 101 is manufactured with a certain designed thickness, the designed substrate thickness L2d exists. In addition, a plated portion connecting the back conductor layer 108 and the first interior conductor layer 102 in a through hole penetrating the front conductor layer 107 and the back conductor layer 108 using the first interior conductor layer 102 as a desired conductor layer. In the case of performing back drilling to remove the remaining plated portion 110 while leaving 110, the length from the surface conductor layer 107 to the first interior conductor layer 102 which is a desired conductor layer is referred to as a reference surplus length L2d. Since how the insulating layer and the conductor layer are formed in manufacturing the substrate 101 is determined in advance, if the desired conductor layer is specified, the reference surplus length Lnd is determined in the substrate 101. It is specified as a numerical value in design in (see FIG. 4).
The plated portion 110 is scraped off by back drilling. In this case, it is theoretically most desirable that the length to be the remaining margin 110-1 of the plated portion 110 is zero.
On the other hand, as described above, when the back drilling process is performed to remove the remaining plated portion 110 while leaving the plated portion 110 that connects the back conductor layer 108 and the first interior conductor layer 102 that is the desired conductor layer. Since a processing error inevitably occurs, a predetermined dimension td as a design margin is determined in advance (see FIG. 4).
The numerical values of the reference surplus length L2d and the remaining design length td are recorded in the storage medium S1 of the CNC control circuit S.
Further, the numerical value of the predetermined thickness q of the layer of the plated portion 110 applied to the hole portion 109 of the through hole and the angle θ of the tip angle of the drill 3 is recorded in the storage medium S1 of the CNC control circuit S.

Secondly, since the lower plate 111 used when the back drilling is performed on the substrate 101 is a quadrangle, a total of 16 areas are divided into four equal parts in the vertical and horizontal directions in a state where the lower plate 111 is placed and fixed on the processing table 26. A virtual line to be divided into 201 is drawn, and a virtual line that divides each area into two sub-areas 202 in total, which is divided into two equal parts, is drawn (see FIG. 3). For each subarea 202, the intersection of the diagonal lines, that is, the center of each subarea 202 is set as a measurement point 203 of the lower plate 111. That is, 64 measurement points 203 are set on the lower plate 111. The measurement point 203 is a position at which the actual thickness of the substrate 101 is measured, and a numerical value that is a basis for calculating the actual position of the desired conductor layer is measured. Since the average value of the measured values for the lower plate 111 is used, it is necessary that the average value be determined with a certain regularity so as not to be unevenly distributed on the lower plate 111. In general, since the lower plate 111 is a square of 33.5 cm × 50 cm in length and width, the area 201 is divided into 16 equal parts, and the sub-area 202 is further divided into four equal parts. However, depending on the size of the lower plate 111, it is conceivable to appropriately adjust the sizes of the area 201 and the sub-area 202, such as increasing the number of divisions.
Further, for example, when 100 through holes are provided in one substrate 101 and back drilling is performed on each of the 100 through holes, here, measurement points 203 for each area 201 (in this embodiment, The average value of four measurement points 203 exists in one area 201.) If the average value of speed is more accurate than speed or economy, When the substrate 101 is placed on and fixed to the lower plate 111 on the processing table 26, the position of the lower plate 111 corresponding to each of the 100 holes 109 serving as the back drilling positions is specified, and each position is determined. To be the measurement point 203. However, in this method, since the positions corresponding to each of the 100 holes 109 of the substrate 101 must be specified on the lower plate 111, a considerable amount of work is required, resulting in an increase in time and cost. It becomes. Here, as the average value of the height position of the lower plate 111 for each area 201 is obtained, both quickness, economic efficiency and accuracy are achieved. Therefore, the size of the base plate 101 or the base plate before cutting out the base plate 101, the number of holes 110 that require back drilling, and the like, and the accuracy required for the lower plate 111, The number of areas 201 and sub areas 202 to be provided may be determined as appropriate.
Then, a specific position in the lower plate 111 is defined as an origin (that is, a position that becomes (0, 0) as vertical and horizontal XY coordinates), and a number for identifying it is assigned to each area 201. The range of 201 is specified by coordinates, and the coordinate position of each measurement point 203 is also specified. As described above, in this embodiment, four subareas 202 are provided in one area 201, and the center of each subarea 202 is a measurement point 203. Therefore, four areas are provided in one area 201. A measurement point 203 exists. For example, the first to fourth measurement points 203 are assigned to the area 201 assigned with the identification number 1 and the fifth to eighth measurement points 203 are assigned to the area 201 assigned the identification number 2. Will exist. Therefore, for each area 201, the measurement points 203 existing in the area 201 are classified and recorded in the storage medium S1 of the CNC control circuit S.

Thirdly, with the lower plate 111 placed and fixed on the processing table 26, the height position of each measurement point 203 is measured using the descent distance information detection mechanism K of the substrate processing apparatus A described above. Since the upper surface of the lower plate 111 is the lower plate upper surface copper foil layer 112, if the tip of the drill 3 of the rotor 2 of the spindle a comes into contact with the lower plate upper surface copper foil layer 112, a change in current occurs in the detector 9. Is detected and contacted. Then, the height position at the time when the change in the current is detected is measured. This measurement operation is performed at all the measurement points 203, and the measurement results at each measurement point 203, that is, the height position information is automatically recorded in the storage medium S1 of the CNC control circuit S. Then, the calculation mechanism S3 in the CNC control circuit S calculates the average value αave of the height position information of the measurement points 203 classified for each area 201, and the average value αave is the height of the area 201. It is recorded in the storage medium S1 as position information. For example, since there are measurement points 203 from No. 1 to No. 4 in the area 201 with the identification number of No. 1, the average value αave of the height position information of the No. 1 to No. 4 measurement points 203 is obtained. It is calculated and recorded in the storage medium S1 as height position information of the first area 201. As a result, since the area is divided into 16 areas 201 in this embodiment, the areas 201 to 16 exist as identification numbers, and the average value αave is calculated for each of them. Become. The calculation of the average value αave of the height position information of the measurement point 203 performed for each area 201 may be performed when calculating the back drilling depth L2c described later.

Fourth, the XY coordinate position of each hole 109 of the substrate 101 is recorded in the storage medium S1 of the CNC control circuit S. For example, in one substrate 101 provided with 100 through-hole portions 109, a specific position of the substrate 101 is set to the origin (that is, (0, 0), and the coordinate positions of the 100 holes 109 are specified. For example, the coordinate position of the first hole 109-1 is (1, 1), and the coordinate position of the second hole 109-2 is (1, 2). Then, a number for identifying each of the 100 holes 109 is given, and the coordinate position is recorded in the storage medium S1 of the CNC control circuit S.

Fifth, the substrate 101 for performing the backdle processing is placed and fixed on the lower plate 111 placed and fixed on the processing table 26, and the extraction mechanism S2 in the CNC control circuit S is in that state. The position on the XY coordinate of each hole 109 subjected to back drilling is compared with the XY coordinate position of each area 201 provided on the lower plate, and the corresponding hole 109 is extracted for each area 201. At that time, if the position of the origin of the lower plate 111 and the position of the origin of the substrate 101 overlap in the vertical direction when the substrate 101 is placed and fixed on the lower plate 111, the hole 109 It is possible to collate and extract by simply comparing the coordinate position with the coordinate position of the area 201, but if the position of the origin of both of them is misaligned, the misalignment amount is calculated and one coordinate numerical value is corrected. Thus, the correspondence is collated and extracted. For example, when the position of the origin (0, 0) of the lower plate 111 and the position of the origin (0, 0) of the substrate 101 overlap in the vertical direction, the first area 201 is (0, 0). When it is within the range of the square delimited by (4, 0), (4, 4), (0, 4), the coordinate position of the first hole 109-1 of the substrate 101 is (2, 2). If there is, it is clear that the hole 109-1 exists in the first area 201, but the position of the origin (0, 0) of the lower plate 111 is relative to the substrate 101 in the X-axis direction. In other words, when the position of the origin (0, 0) of the lower plate 111 overlaps the position of (10, 0) of the substrate 101 in the vertical direction, the first area 201 is (0,0) (4,0) (4,4) (0,0) as coordinate positions based on the position of the origin on the lower plate 111 That) in which, when this is converted into coordinate position relative to the position of the origin of the substrate 101, it comes to (10,0) (14,0) (14,4) (10,4). Then, since the coordinate position of the first hole 109-1 is (2, 2) with reference to the position of the origin of the substrate 101, the first hole 109-1 is the lower plate. 111 does not exist in the first area 201. Needless to say, if there is a deviation at each origin position between the lower plate 111 and the substrate 101, a function for measuring the deviation and correcting the coordinate value according to the deviation amount is necessary. .

Sixth, the height position of each hole 109 of the substrate 101 placed / fixed on the lower plate 111 placed / fixed on the processing table 26 is determined based on the descending distance information detection mechanism K of the substrate processing apparatus A described above. Use to measure. Each hole 109 is a plated portion 110 including the inner peripheral surface from the front surface side to the back surface side of the substrate 101, and the surface conductor layer 107 exists around the plated portion 110 on the front surface side. If the tip of the drill 3 of the rotor 2 of the spindle a comes into contact with the plated portion 110 and the surface conductor layer 107, the change in current is detected by the detector 9, and it becomes clear that the contact is made. Then, the height position at the time when the change in the current is detected is measured. This measurement operation is performed in all the holes 109, and the measurement result in each hole 109, that is, the height position information is automatically recorded in the storage medium S1 of the CNC control circuit S for each hole 109.

Seventh, based on the correspondence relationship between each area 201 of the lower plate 111 described in the fifth and the hole 109 of the substrate 101, each calculation unit S3 of the CNC control circuit S measures each of the values measured in the sixth. The average height αave of the area 201 of the lower plate 111 corresponding to the hole 109 calculated in the third is subtracted from the height of the hole 109, and the numerical value after the subtraction is the substrate 101 in the hole 109. The actual thickness is automatically recorded in the storage medium S1 of the CNC control circuit S. For example, as described above, when the position of the origin (0, 0) of the lower plate 111 and the position of the origin (0, 0) of the substrate 101 overlap in the vertical direction, the first area 201 is ( The coordinate position of the first hole portion 109-1 of the substrate 101 is (2) when it is within a square range delimited by (0,0) (4,0) (4,4) (0,4). , 2), the hole 109-1 is present in the first area 201. Therefore, the numerical value of the height position measured in the first hole 109-1 is The average value αave of the height of one area 201 is subtracted, and the numerical value after the subtraction is taken as the thickness of the substrate 101 at the position of the first hole 109-1, and the storage medium S1 of the CNC control circuit S To record. This calculation is performed in the same manner for all the holes 109. This calculation may be performed when calculating the back drilling depth L2c, which will be described later, as in the case of calculating the average height αave of the area 201 described in the third embodiment.
By this formula that the average value of the height position for each area 201 of the lower plate 111 is subtracted from the numerical value of the height position at the position of each hole 109, the inclination and deflection existing in the processing table 26 itself, Furthermore, various factors that cause the displacement of the height position of the lower plate, such as the inclination and the bending existing in the lower plate 111 itself, are eliminated, and maintenance and precision for eliminating the horizontal and bending of the work table 26 are eliminated. The fine adjustment procedure can be omitted, and the precision of the thickness of the lower plate 111 itself is not required. In particular, the inclination and the bending of the processing table 26 generally appear as an error of about ± 50 μm in the processing range of the substrate 101, and further, the inclination and the bending of the lower plate 111 placed thereon, as well as the lower plate 111 itself. Since there is an error derived from the manufacturing, the error of the working table 26 itself and the error of the lower plate 111 itself are combined, which has conventionally been a factor causing a large error in the depth control of the back drilling process. It was. However, in the present embodiment, as described above, the formula of subtracting the average value of the height position for each area 201 of the lower plate 111 from the numerical value of the height position at the position of each hole 109 is applied. Therefore, as a measurement error by the descending distance information detection mechanism K using the drill 3, there is an error of about ± 5 μm for each height position of the lower plate 111 and the substrate 101 (actually, each hole 109 of the substrate 101). Although it is unavoidable that it can occur, even if the errors of the two are summed, the error can be kept within about ± 10 μm.
As a result, not only the processing depth control error during back drilling is reduced, but also maintenance and fine adjustment procedures for strictly correcting the inclination and deflection of the surface of the processing table 26 become unnecessary.

Eighth, in the calculation mechanism S3 of the CNC control circuit S, the following calculation is performed for each hole 109 to calculate the individual back drilling depth L2c.
L2c = Lnd × (L2m−αave) / L2d−td + angle tan1
Lnd = standard length for design.
The numerical value of L2m-αave is calculated and recorded in the seventh step.
L2d = designed thickness of the substrate 101.
td = the length of the design margin.
Angle tan1 = Thickness of the layer of the plated part 110 applied to the hole 109 of the through hole q × tan {(180 degrees−angle θ of the tip angle of the drill 3) / 2}
In this formula, the ratio between the designed substrate 101 thickness and the actual substrate 101 thickness at the position of each hole 109 where back drilling is performed is calculated by (L2m−αave) / L2d. On the other hand, since the height position in the substrate 101 of the first interior conductor layer 102 which is a desired conductor layer is determined by design, the distance from the surface of the substrate 101 to the first interior conductor layer 102 is also determined. Of course, it is determined by design. This design distance is the reference surplus length Lnd. The ratio between the design thickness L2d of the substrate 101 itself and the actual thickness L2m-αave of the substrate 101 in each hole 109 is within the substrate 101 of the first interior conductor layer 102 which is a desired conductor layer. From the surface of the substrate 101 obtained by subtracting the actual height position of the first interior conductor layer 102 from the designed height position, ie, the reference surplus length Lnd, and the actual height position of the substrate 101 in the hole 109. It was found that the relationship was equal to the ratio to the actual distance to the first interior conductor layer 102. Therefore, the design substrate 101 thickness L2d calculated by the formula of (L2m−αave) / L2d and the actual substrate 101 thickness at the position of each hole 109 where back drilling is performed are calculated as the reference surplus length Lnd. The actual height position in the substrate 101 of the first interior conductor layer 102, which is a desired conductor layer, that is, the actual length of the extra length portion is calculated.
As described above, αave is a numerical value indicating the average height of each area 201 of the lower plate 111 in which each of the holes 109 exists, and thus may not be completely accurate, but it is economical and quick. Although it is more reasonable than measuring and calculating the height position of the lower plate 111 at a position corresponding to each hole 109 from the balance with the average, In other words, there is a problem of measurement accuracy, and there is no error in the actual distance from the surface of the substrate 101 to the desired conductor layer in the calculated hole 109. I can't. Therefore, a certain remaining margin is required as a so-called safety factor, but the objective actual distance from the surface of the substrate 101 to the desired conductor layer in the hole 109 is calculated as in the present embodiment. If there is little error with the distance, the safety factor can be estimated low, that is, the length of the remaining allowance can be set short. In this sense, the preset remaining allowance is referred to as a reference remaining allowance td, and the reference remaining allowance td is subtracted from the calculated actual distance from the surface of the substrate 101 to the desired conductor layer in the hole 109. Will be.

By the way, the drill 3 that performs back drilling has a tip angle θ, and the tip forms a tip corner apex 3-1. Therefore, when the drill 3 descends to measure the height position of the substrate 101 at the position where the through hole is provided, the tip apex 3-1 of the drill 3 advances into the hole 109. The contact between the tip of the drill 3 and the substrate 101 is measured by the descending distance information detection mechanism K when the inclined portion 3-2 contacts the inside of the plated portion 110 extending to the surface side of the substrate 101. Become. That is, at that time, the tip corner apex portion 3-1 of the drill 3 has reached a position lower than the actual height position of the substrate 101. When the back drilling is performed, the plated part 110 is cut by the tip of the drill 3 being advanced through the hole 109 of the through hole. However, the plated part 110 is cut by the inclined part 3-2 in the drill 3. Since it is not the tip corner apex portion 3-1, the inclined portion 3 of the drill 3 that defines the position of the tip apex portion 3-1 of the drill 3 and the length of the remaining margin 110-1 of the extra length portion. −2 is not only displaced, but also the upper end of the remaining margin 110-1 is cut with an inclination that the outside is long and the inside is short with respect to the hole 109 (FIG. 5). reference). On the other hand, the length td of the remaining allowance in the design is defined by the tip portion that is longer on the outside with respect to the hole 109 of the remaining allowance 110-1. Therefore, the plated portion that becomes the remaining allowance 110-1 The deviation of the height between the inner side and the outer side of 110 is corrected by calculating the angle tan1 with respect to the thickness of the plated portion 110. That is, the depth of the back drilling process is corrected by a numerical value calculated by the thickness of the through-hole plated portion 110 × tan {(180 degrees−the angle of the tip angle θ of the drill) / 2}. The control of the height can be performed accurately and precisely.

As a result, the height position of the surface of the substrate 101 in the hole 109 is measured from the fixed point where the drill 3 of the rotor 2 of the spindle a is not in contact with the substrate 101 as the origin in the height direction. When the back drilling is stopped when it is detected that the drill 3 has moved by a distance that is the sum of the distance to the surface of the substrate 101 and the processing depth L2c of the back drilling process, the accurate depth can be obtained. Back drilling can be performed.

In this way, the recording, extraction, and calculation steps are automatically performed by the CNC control circuit S, and the back drilling depth of each hole 109 can be controlled accurately and precisely in a short time. it can.
It should be noted that the order of the steps is merely an example, and of course, a step having a logical prior relationship, that is, for example, calculation in the eighth step, each numerical value used for the calculation is recorded, extracted or calculated in advance. In the sense that it must be done, it is constrained by its predecessor relationship, but conversely, those that do not have a logical predecessor relationship, such as the first step and the second step, are described in this embodiment. It is not restricted by the pre- and post-step relationships, and the pre- and post-relationships can be interchanged.

As described above, the substrate processing apparatus A according to the present embodiment has the descending distance information detection mechanism K that can detect the descending distance information by the drill 3 itself, and the height of the lower plate 111 and the substrate 101 measured by the drill 3. A CNC control circuit S having a storage medium S1, an extraction mechanism S2, and a calculation mechanism S3 that calculates the processing depth of back drilling processing according to the above formula based on the position information is provided. Further, by using the back drilling method in the present embodiment, the back drilling can be performed by accurately and precisely controlling the processing distance of the drill 3 of the spindle a based on the calculated processing depth. Therefore, the back drilling is precisely performed according to the actual thickness of the substrate 101 and the actual distance from the surface of the substrate 101 to the desired conductor layer in each hole 109 where the back drilling is performed quickly and economically. It becomes possible to do. As a result, it is possible to minimize the length td of the remaining allowance in design, and it is possible to provide a processed substrate 101 that is low in cost and has few occurrences of problems such as noise.

Incidentally, as described in the seventh step, an error of about ± 10 μm is unavoidable as a measurement error, and in addition, variations in each area 201, thermal displacement during processing of the substrate 101, and the like cause errors. Therefore, even if they are taken into account, in this embodiment, it was considered that the error of the length of the remaining allowance due to the processing depth of bagrill processing can be kept within a range of about ± 40 μm. Therefore, after providing 100 through holes in the following test substrate, the substrate processing apparatus A of this example performs back drilling on the holes of these 100 through holes by the method shown in this example. went. And after cutting each hole of the specimen, the actual length of the remaining allowance was measured under a microscope and compared with the length of the reference remaining allowance, and it was confirmed that there was no difference within ± 25μm. did it.
Specimen and setting contents Vertical and horizontal 33.5cm x 50cm
Insulating layer A three-layer structure (first to third insulating layers from the back side) made of a glass epoxy resin, which is a thermoplastic resin, has a thickness of 75 μm.
Conductor layer With copper foil, the first interior conductor layer is provided between the first and second insulation layers, and the second interior conductor layer is provided between the second insulation layer and the third insulation layer. And each thickness is 20 μm.
Lnd 170μm
L2d 265 μm
td 50μm
Thickness of the plated part of the through hole 40μm
Drill tip angle 130 degrees Contents of lower plate Vertical and horizontal thickness 33.5cm x 50cm x 1.5mm
Material Glass epoxy resin Lower plate top copper foil layer thickness 20μm

FIG. 6 shows that an aluminum upper plate 301 having a known thickness is placed on the substrate 101 when the substrate 101 is placed and fixed on the processing table 26 via the lower plate 111 during back drilling. Fig. 3 shows a state in which a bakelite-made bake upper plate 302 is mounted and fixed thereon.
As described above, in the embodiment in which the upper plates 301 and 302 are used, the following points differ only in the measurement and formula for controlling the processing depth of the back drilling process.
That is, first, the aluminum upper plate 301 is conductive, but the bake upper plate 302 is insulative. Therefore, the lower plate 111 is placed and fixed on the processing table 26, and the substrate 101 is placed thereon. In the state where the aluminum upper plate 301 and the bake upper plate 302 are further placed and fixed, the height position of the aluminum upper plate 301 at the position of the XY coordinate corresponding to each hole 109 of the substrate 101. L2m1 is detected by the descending distance information detection mechanism K using the drill 3. That is, in the first embodiment, instead of detecting the height position of each hole 109 of the substrate 101 placed and fixed on the lower plate 111 by the descending distance information detection mechanism K, each hole 109 Based on the XY coordinate position, the height position of the XY coordinate position corresponding to each hole 109 is measured in a state where the aluminum upper plate 301 is placed and fixed on the substrate 101. At this time, since the bake upper plate 302 is non-conductive, the position information is not detected by the descending distance information detection mechanism K even if the drill 3 comes into contact, and the tip of the drill 3 is placed on the aluminum upper plate 301. The position information is not detected by the descending distance information detection mechanism K until the apex 3-1 contacts. This height position is used in the formula instead of the height position of each hole 109 of the substrate 101 placed and fixed on the lower plate 111 on the processing table 26 in the first embodiment. Understanding the correspondence between the measurement position on the aluminum upper plate 301 and the area 201 of the lower plate 111, subtracting the average height of the lower plate 111 of the area 201 in the correspondence relationship, etc. Same as Example 1.

Second, in this embodiment, the height position L2m1 of the aluminum upper plate 301 at the position of the XY coordinate corresponding to each hole 109 of the substrate 101 is not the height position of each hole 109 of the substrate 101. Since it is measured, when calculating the thickness of the substrate 101, it is necessary to subtract the thickness of the aluminum upper plate 301,
L2m1-αave-tAL
Thus, the thickness of the substrate 101 is calculated. Note that tAL is the thickness of the aluminum upper plate 301, and this thickness is set by design as will be described later.

Thirdly, after calculating the length of the actual surplus portion based on the design surplus length in the desired conductor layer from the ratio of the measured thickness of the substrate 101 to the design thickness, In calculating the processing depth L2c of the back drilling process by subtracting the above remaining allowance length td, not only the thickness of the aluminum upper plate 301 but also the tip of the drill 3 generated by the tip angle θ of the drill 3 Difference in height position between the position of the corner apex 3-1 and the inclined portion 3-2 of the drill 3 that contacts the plated portion 110 applied to the hole 109 (hereinafter, this distance is referred to as "corner tan2") .) Is required.
That is, when the descending distance from the position (position that becomes 0 in the Z coordinate indicating the height) to the origin of the drill 3 of the spindle a before starting the back drilling process to the aluminum upper plate 301 is P, This distance P is obtained by placing / fixing the lower plate 111 on the processing table 26, placing / fixing the substrate 101 thereon, and further placing / fixing the aluminum upper plate 301 thereon. When the tip corner apex 3-1 of the drill 3 comes into contact with the aluminum upper plate 301, it is detected by the descending distance information detection mechanism K. At that time, the tip corner apex 3-1 of the drill 3 is at the same height as the actual height of the aluminum upper plate 301. When the back drilling is performed, the plated part 110 is cut by the tip of the drill 3 being advanced through the hole 109 of the through hole. However, the plated part 110 is cut by the inclined part 3-2 in the drill 3. Since it is not the tip corner apex portion 3-1, the position of the tip corner apex portion 3-1 of the drill 3 and the inclined portion 3-2 of the drill 3 that defines the remaining margin 110-1 of the extra length portion are defined. In addition to the deviation from the position, the upper end of the remaining margin 110-1 is cut with the outer side being longer and the inner side being inclined with respect to the hole 109. On the other hand, the length td of the design margin is defined by the tip portion of the margin 110-1 whose outside is longer than the hole portion 109. The deviation between the position and the height of the outside of the plated portion 110 that becomes the remaining allowance 110-1 is the radius of the through hole when the through hole is processed (the radius of the hole 109 and the thickness of the plated portion 110). It is corrected by calculating an angle tan2 with respect to (added) (see FIG. 7).
In other words, as described in the first embodiment, the upper end portion of the remaining margin 110-1 of the plating portion 110 is cut with an inclination that the outside is long and the inside is short with respect to the hole 109. Therefore, the design remaining allowance length td is measured at the tip position on the outer side with respect to the hole 109. Then, based on the measured value, the numerical value obtained by subtracting the design remaining length td from the actual extra length calculated by the formula of Lnd × (L2m1-αave-tAL) / L2d is obtained by plating. Although the distance at which the back drilling process is performed in the portion 110 is shown, the drill that is actually required from the point at which the tip apex 3-1 of the drill 3 contacts the aluminum upper plate 301 to the end point of the back drilling process. This means that the moving distance of 3 is not shown. In order to calculate the movement distance of the drill 3 that is actually required, the position of the tip corner apex portion 3-1 of the drill 3 and the position where the inclined portion 3-2 of the drill 3 is in contact with the plating portion 110 ( As described above, since the length of the remaining margin 110-1 is measured at a position outside the hole portion 109, it is necessary to correct the deviation from the plating portion 110 which is the remaining margin 110-1). Yes, it is necessary to add a numerical value derived from the following formula (this numerical value is the angle tan2).
Angle tan2 = β × tan {(180 degrees−angle θ of drill tip angle) / 2}
β = radius of through hole when processing through hole (added radius of hole 109 and thickness of plated part 110)
As a result, each processing depth L2c of back drill processing in each hole 109 is calculated by the following calculation formula.
L2c = Lnd × (L2m1-αave-tAL) / L2d-td + tAL + angle tan2
Lnd = standard length for design.
L2m1 = Each area 201 of the lower plate 111 in a state where an aluminum upper plate 301 having a known thickness is further placed and fixed on the substrate 101 placed on the lower plate 111 on the processing table 26. Measured height at each back drilling position extracted as existing in the coordinate value range.
αave = average value of the actually measured heights of the measurement points 203 for each area 201 of the lower plate 111 on the processing table 26.
L2d = design thickness of the substrate 101.
td = the length of the design margin.
tAL = the thickness of the aluminum upper plate 301.

  In this case, it is sufficient that the thickness of the aluminum plate used as the aluminum upper plate 301 is known. However, in consideration of the ease of handling at the time of use and the range of error in the thickness of the generated aluminum upper plate 301 itself, etc. In this case, it is appropriate to use a thickness of about 0.15 mm. In this case, although an error of about ± 10 μm occurs as a variation in the thickness, when the aluminum upper plate 301 is not used, the center line of the hole 109 for performing back drilling and the drill 3 for performing back drilling are used. And the center line of the drill 3 need to be closely matched with each other, and the drill 3 is required to be held firmly during back drilling so that the core 3 is not skewed and misaligned. In consideration of the back drilling processing depth error caused by the center line misalignment or core misalignment, it is meaningful to prevent the error due to the center line misalignment by using the aluminum upper plate 301. That is.

  On the other hand, when the hole 109 having the plated portion 110 is back-drilled by the drill 3, the plated portion 110 is cut by the drill 3 to generate a specific thread-like facet. When the aluminum upper plate 301 is placed on the substrate 101, the thread-shaped facet is in contact with the aluminum upper plate 301 in a state where it is attached to the tip of the drill 3. When detecting the descending distance information of the hole portion 109 of the hole, the thread-shaped facet becomes a disturbance factor, which hinders accurate detection of the descending distance information. Therefore, it is only necessary to frequently remove the facet adhering to the tip of the drill 3. However, when many back drills are continuously performed on a large number of substrates, the time and labor required for the removal reduce the cost of substrate processing. Will be increased. Therefore, a bakelite-made bake upper plate 302 is further placed and fixed on the aluminum upper plate 301 when performing back drilling as a method for easily and quickly removing the thread-like facet attached to the tip of the drill 3. Is. As a result, when it is attempted to detect the descending distance information of the hole portion 109 of the next through hole in a state where the thread-shaped face is attached to the tip of the drill 3, the tip of the drill 3 first comes into contact with the bake upper plate 302 and then the bake upper plate. Since the holes 302 are drilled, the facet of the bake upper plate 302 that is an insulator pushes and removes the thread-like facets of the plated portion 110 attached to the tip of the drill 3. Accordingly, it is possible to detect the descending distance information with respect to the continuous through-hole portion 109 without taking any special removing means.

  Incidentally, in this example using the aluminum upper plate 301 (thickness 0.15 mm) and the bake upper plate 302 (thickness 1 mm), 100 through-holes with the same specimens and conditions as in the first example were used. Back drilling was performed on the hole. And after cutting each hole of the specimen, the actual length of the remaining allowance was measured under a microscope and compared with the length of the reference remaining allowance, and it was confirmed that there was no difference within ± 25μm. did it.

  By the way, as a descending distance information detection mechanism in the substrate processing apparatus, in the first embodiment, the cancel circuit 10 and the bypass circuit 5 are provided in order to remove the disturbance factor when detecting the change of the current in the detector 9. As a more simplified descent distance information detection mechanism K1, it may be formed of a high frequency oscillator 6, a current transformer 7a, a detection circuit 8, a detector 9, and a bypass circuit. That is, as shown in FIG. 8, the GDN line 11 is connected to the casing 27 of the substrate processing apparatus B from the high frequency oscillator 6 which is a high frequency power supply, and the output line 12 is one end of the input winding 3 of the current transformer 7a. In addition, the other end of the input winding 13 and the spindle body 1 are connected. A bypass circuit 5 is provided in the middle of the connection between the input winding 3 and the spindle body 1 of the current transformer 7a. In other words, in the descending distance information detection mechanism K shown in the first embodiment, the cancel circuit 10 is omitted, and therefore the current transformer 7a without the cancel winding 14 is used as the current transformer. The only difference is that.

In the descending distance information detection mechanism K1 in this embodiment, the mechanism K1 itself is not provided with an allowance for eliminating a disturbance factor. Therefore, as in the case where the bearing used between the spindle body 1 and the rotor 2 is an air bearing, the electrostatic capacitance CR between the spindle body 1 and the rotor 2 is increased to 1000 pF or more. A filter that restricts the current that flows through the input winding of the current transformer to a specific frequency that flows from the high-frequency oscillator only when the decrease in the accuracy of determining whether or not the contact is sufficiently acceptable. When provided, the descending distance information detection mechanism K1 can be provided at a low cost with a simple configuration. In addition, since the bypass circuit 5 connected to the housing 27 is provided in the middle of the connection connecting the input winding 13 of the current transformer 7a and the spindle body 1, the spindle a is a so-called floating metal. Therefore, it is not necessary to provide a protective function for preventing electric shock, and current such as harmonic current flows to the casing 27 through the drill 3, and the metal surface of the drill 3 and the surface of the drill 3 are coated by the current. Is prevented, and the drill 3 can be used for a long time.
Since at least the descending distance information detection mechanism K1 in the present embodiment is the conventionally used descending distance information detection mechanism K1, this descending distance information detection mechanism K1 is used to explain it in the first embodiment. By incorporating the CNC control circuit S having the storage, extraction, and calculation mechanism, the conventional substrate processing apparatus can be made into a substrate processing apparatus that can accurately and precisely control the processing depth of back drilling. .
In addition, when another mechanism is provided for preventing an electric shock and it is not necessary to consider the damage of the drill or the like, it is conceivable to use a descending distance information detecting mechanism in which even the bypass circuit 5 is omitted.

A fourth embodiment is shown in FIG. In the first embodiment shown in FIG. 1, since the spindle 1 is insulated from the beam 29 (the same potential as the casing 27), the substrate 101 can be either insulated or non-insulated with respect to the processing table 26. In contrast, in this example, the spindle 1 is directly attached without being insulated from a beam (not shown) (the same potential as the casing 27), whereas the substrate 101 is insulated from the processing table 26. , Is placed on the processing table 26. In this embodiment, since the lower plate 111 is used for this insulation, the aluminum lower plate 111 cannot be used.
As shown in FIG. 9, the descending distance information detection mechanism K2 in the present embodiment is a simulated substrate formed by arranging a capacitor 50 and a dip switch 51 arranged in series as one set, and a plurality of capacitors and switches arranged in parallel. A circuit 52 is provided. That is, the substrate 101 as a detection target is insulated from the casing 27 of the substrate processing apparatus C, and the lower plate 111 made of glass epoxy resin having the lower plate upper surface copper foil layer 112 on the processing table 26 in the casing 27. In addition, the high frequency oscillator 6 is connected to the casing 27 from the GND line 11 and connected to one terminal of the simulated substrate circuit 52, and the other output line 12 is connected in the same direction. By connecting the end of winding and the beginning of winding as the same number of turns in the middle of the two input windings 13 and 13a of the current transformer 7b, each of the input windings 13 and 13a is a coil with the same number of reverse turns. Thus, when the same amount of current flows through each of the input windings 13 and 13a, the directions of the magnetic flux generated in the iron core 15 of the current transformer 7b cancel each other, and current is generated on the output winding 16 side. Will not. The other end of each of the two input windings 13 and 13a of the current transformer 7b is connected to the surface conductor layer 107 of the substrate 101, which is a detection target, and to the other terminal of the simulated substrate circuit 52. Has been. Then, by adjusting the dip switch 51 of the simulated substrate circuit 52 so as to be substantially equal to the capacitance generated between the surface conductor layer 107 of the substrate 101 that is the detection target and the housing 27, each input winding 13, 13a is adjusted. When the same amount of current flows, the direction of the magnetic flux generated in the current transformer 7a cancels each other, and the contact between the tip of the drill 3 of the spindle a and the surface conductor layer 107 of the substrate 101 serving as the detection target object. This is a descending distance information detection mechanism K3 that is detected by the detector 9 as a change in the current output from the current transformer 7a.

The descending distance information detection mechanism K2 shown in the fourth embodiment is capable of eliminating disturbance factors when detecting the descending distance information. As in the case of No. 3, by using the descending distance information detection mechanism K2, and incorporating the CNC control circuit S having the storage, extraction and calculation mechanisms described in the first embodiment, the conventional substrate processing apparatus can be obtained. It is possible to provide a substrate processing apparatus that can accurately and precisely control the processing depth of back drilling.

  The substrate processing apparatus incorporating the descending distance information detection mechanism and the method of using the substrate processing apparatus according to the present invention include a thickness error or deflection of the substrate itself or back plate processing when back drilling the substrate through hole. It is possible to prevent the occurrence of errors in the processing depth caused by a number of factors such as the thickness error and the inclination and bending of the processing table itself of the substrate processing apparatus, and the processing depth can be controlled accurately and precisely. In other words, since the length of the design allowance can be set short, it is possible to realize substrate processing that can prevent problems such as noise generation at low cost. In addition to drilling, it is possible to accurately and precisely control the processing depth even in drilling to a certain depth with respect to the substrate.

A, B, C Substrate processing device K, K1, K2 Descent distance information detection mechanism a Spindle 1 Spindle body 2 Rotor 3 Drill 3-1 Tip angle apex 3-2 Inclined portion 4 Detection device 5 Bypass circuit 6 High-frequency oscillators 7, 7a 7b Current transformer 8 Detector circuit 9 Detector 10 Cancel circuit 11 GND line 12 Output line 13, 13a Input winding 14 Cancel winding 15 Iron core 16 Output winding 17-1 Simulation circuit 17-2 Simulation circuit 17-3 Simulated circuit 17-4 Simulated circuit 18 Reverse bypass circuit 20 Capacitor 21 Dip switch 22 Three-phase motor 23 U-phase winding 24 V-phase winding 25 W-phase winding 26 Work table 27 Housing 28 Inverter
29 Beam 30 Insulator 31 Z-axis drive device 32 Ground
50 Capacitor 51 Dip Switch 52 Simulated Substrate Circuit 101 Substrate 102 First Inner Conductor Layer 103 First Insulating Layer 104 Second Insulating Layer 105 Third Insulating Layer 106 Second Interior Conductor Layer 107 Surface Conductor Layer 108 Back Conductor Layer 109, 109-1, 109-2 Hole 110 Plating 110-1 Remaining allowance 111 Lower plate 112 Lower plate upper surface copper foil layer 201 Area 202 Subarea 203 Measurement point 301 Aluminum upper plate 302 Bake upper plate V Commercial power supply L Reactor L 'Reactor R Resistance R' Resistance S CNC control circuit S1 Storage medium S2 Extraction mechanism S3 Calculation mechanism q Predetermined thickness of plated layer θ Angle of tip angle of drill

Claims (8)

A processing depth control mechanism using a computer for controlling a descending distance of a spindle drill in back drill processing in a substrate processing apparatus capable of performing back drill processing on a multilayer printed wiring board,
While having a descending distance information detection mechanism that detects descending distance information by the spindle drill coming into contact with the detection object,
It has a storage medium on which each of the following 1 to 5 position information is recorded,
1. Numerical information on the design substrate thickness, the reference surplus length and the design remaining allowance length, the predetermined thickness of the plated layer applied to the hole of the through hole, and the angle of the tip angle of the drill,
2. On the lower plate placed on the processing table of the substrate processing apparatus and having at least the upper surface as a conductor layer, the measurement points defined by the following settings and the coordinate position information on the plane of each area area,
A plurality of areas are divided in a grid pattern, and each measurement point defined by the same standard for each area, or each subarea divided into a grid pattern by the same standard for each area. One measurement point defined by the same standard.
3. Height position information for each measurement point measured by the descent distance information detection mechanism by lowering the spindle on which the drill for performing back drilling is lowered with respect to each measurement point,
4). Each of the multilayer printed wiring boards placed on the lower plate on the processing board of the substrate processing apparatus or each of the mother boards before cutting out the plurality of multilayer printed wiring boards (hereinafter simply referred to as “mother boards”). Coordinate position information on the plane of back drill processing position,
5. Height position information for each back drilling position measured by the descending distance information detection mechanism by lowering the spindle to each back drilling position of the substrate or mother board,
From the coordinate position information for each area and the coordinate position information of the back drilling position existing on the multilayer printed wiring board or its mother board, the multilayer printed wiring board or its mother board is placed on the lower board during back drilling. In this state, an extraction mechanism that extracts a back drilling position existing in each coordinate value range of each area of the lower plate,
Having a calculation mechanism for calculating the individual back drilling depth L2c based on the following formula,
A processing depth control mechanism that automatically controls the processing depth of back drill processing in the substrate processing apparatus based on the calculated individual back drill processing depth L2c.
L2c = Lnd × (L2m−αave) / L2d−td + angle tan1
Lnd = design surplus length L2m = extracted as existing in the coordinate value area of each area of the lower board of the multilayer printed wiring board or its mother board placed on the lower board on the processing table Measured height at each back drilling position
αave = average value of measured heights of measurement points for each area of the lower plate on the processing table.
L2d = Designed multilayer printed wiring board thickness td = Left angle angle of design margin tan1 = Predetermined thickness of plated layer of through hole × tan {(180 degrees−angle of tip angle of drill) ÷ 2} The descent distance information detection mechanism has at least a high-frequency AC power source, a bypass circuit including a reactor, and a high-frequency current transformer, and one of the outputs of the high-frequency AC power source is connected to the housing, and the other is the current transformer. Is connected to a spindle that is insulated from the casing, and a bypass circuit having a reactor is provided between the connection to the spindle and the casing, and the drill of the rotor of the spindle is connected to the spindle. By contacting the object to be detected, which is a conductor, high-frequency current from the high-frequency AC power supply flows into the spindle via the current transformer, and further flows into the high-frequency AC power supply via the capacitance between the conductor and the conductor layer. Thus, a current is generated on the output side of the current transformer, and a change in the current is detected by the detector, thereby providing a descending distance information detecting mechanism for recognizing the descending distance information of the drill. And, machining depth control mechanism according to claim 1, wherein.   The descending distance information detection mechanism includes a high-frequency AC power supply, a bypass circuit including a reactor, a cancel circuit, an input winding, a cancel winding, and one or more output windings that are connected in reverse turns with the same number of turns. The cancel circuit has a reverse bypass circuit having a reactor having the same capacitance as the bypass circuit, a capacitor and a switch arranged in series, and the capacitor And a plurality of switches arranged in parallel as one simulation circuit, when the spindle isolated from the housing is energized, between the winding of each phase of the spindle motor and the spindle body, and the spindle body A plurality of sets of simulation circuits corresponding to the capacitance generated between the casings are provided, and the reverse bypass circuit and the plurality of simulation circuits are arranged in parallel, and the object to be detected is mounted on the substrate processing apparatus. One of the outputs of the high-frequency AC power supply is connected to the casing, and the other is connected between the input winding and the cancel winding of the current transformer, The other end of the input winding is connected to the spindle body and connected to the housing via a bypass circuit, and the other end of the cancel winding is connected in parallel with one end of the reverse bypass circuit and one end of each simulation circuit, The other end of the reverse bypass circuit is connected to the housing, and the other end of the simulation circuit corresponding to the capacitance generated between the housing insulated from the spindle body and the spindle is connected to the housing. By connecting the other end of the simulation circuit corresponding to the capacitance generated between the motor and the winding of each phase of the spindle motor, and adjusting the switch of the simulation circuit to be approximately equal to the corresponding capacitance. , Input winding and cancellation winding By canceling out the direction of the magnetic flux generated in the current transformer by the current flowing in the current flow, the change in current caused by the contact between the drill tip of the spindle and the detection target is changed as the current output from the current transformer. The machining depth control mechanism according to claim 1, wherein the machining depth control mechanism is configured as a descending distance information detecting mechanism that recognizes the descending distance information of the drill by detecting with a detector. The descent distance information detection mechanism consists of a high-frequency AC power source, a high-frequency current transformer having two input windings and one or more output windings with the same number of turns, and a capacitor and switch arranged in series. And having a simulated substrate circuit in which a plurality of sets of capacitors and switches are arranged in parallel, and one of the high-frequency AC power supply outputs is connected to the housing and connected to one terminal of the simulated substrate circuit, and the other Is connected to the object to be detected and the other terminal of the simulated substrate circuit via the two input windings of the current transformer, insulated from the case of the substrate processing apparatus, and on the processing table in the case By adjusting the switch of the simulation board circuit so that the capacitance generated between the fixed detection object and the housing is substantially equal, the magnetic fluxes generated by the current transformers by the input winding currents cancel each other. Spindle drill It is a descent distance information detection mechanism that recognizes the descent distance information of the drill by detecting the change in current caused by the contact between the tip and the detection target as the change in current output from the current transformer. The processing depth control mechanism according to claim 1. A substrate processing apparatus comprising the processing depth control mechanism according to claim 1. A back drilling method performed using the substrate processing apparatus according to claim 5,
In addition to recording the position information and the like described in 1 to 5 below on a storage medium,
1. Numerical information on the design substrate thickness, the reference surplus length and the design remaining allowance length, the predetermined thickness of the plated layer applied to the hole of the through hole, and the angle of the tip angle of the drill,
2. In the lower plate placed on the processing table of the substrate processing apparatus and having at least the upper surface as a conductor layer, the measurement point determined by the following settings and the coordinate position information on the plane of each area area,
A plurality of areas are divided in a grid pattern, and each measurement point defined by the same standard for each area, or each subarea divided into a grid pattern by the same standard for each area. One measurement point defined by the same standard.
3. Height position information for each measurement point measured by the descent distance information detection mechanism by lowering the spindle on which the drill for performing back drilling is lowered with respect to each measurement point,
4). Each of the multilayer printed wiring boards placed on the lower plate on the processing board of the substrate processing apparatus or each of the mother boards before cutting out the plurality of multilayer printed wiring boards (hereinafter simply referred to as “mother boards”). Coordinate position information on the plane of back drill processing position,
5. Height position information for each back drilling position measured by the descending distance information detection mechanism by lowering the spindle to each back drilling position of the substrate or mother board,
From the coordinate position information for each area and the coordinate position information of the back drilling position existing on the multilayer printed wiring board or its mother board, the multilayer printed wiring board or its mother board is placed on the lower board during back drilling. In the state, after extracting the back drill processing position existing in each coordinate value area of each area of the lower plate,
A back-drilling method that automatically controls the back-drilling depth in the substrate processing apparatus based on the individual back-drill depth L2c automatically calculated based on the following formula.
L2c = Lnd × (L2m−αave) / L2d−td + angle tan1
Lnd = design surplus length L2m = extracted as existing in the coordinate value area of each area of the lower plate of the multilayer blind wiring board mounted on the lower plate on the processing table or its mother board Measured height at each back drilling position αave = average value of measured height of measurement points for each area of the lower plate on the processing table L2d = design multilayer printed wiring board thickness td = remaining design margin Length angle tan1 = predetermined thickness of the plated portion layer of the through hole × tan {(180 degrees−angle of the tip angle of the drill) ÷ 2} A back drilling method performed using the substrate processing apparatus according to claim 5,
In addition to recording the location information described in 1 to 5 below on a storage medium,
1. Numerical information on the design substrate thickness, reference surplus length and design remaining allowance length, and the radius of the hole of the through hole and the tip angle of the drill hole for back drilling before the plating portion is provided,
2. In the lower plate placed on the processing table of the substrate processing apparatus and having at least the upper surface as a conductor layer, the measurement point determined by the following settings and the coordinate position information on the plane of each area area,
A plurality of areas are divided in a grid pattern, and each measurement point defined by the same standard for each area, or each subarea divided into a grid pattern by the same standard for each area. One measurement point defined by the same standard.
3. Height position information for each measurement point measured by the descent distance information detection mechanism by lowering the spindle on which the drill for performing back drilling is lowered with respect to each measurement point,
4). Each of the multilayer printed wiring boards placed on the lower plate on the processing board of the substrate processing apparatus or each of the mother boards before cutting out the plurality of multilayer printed wiring boards (hereinafter simply referred to as “mother boards”). Coordinate position information on the plane of back drill processing position,
5. With the aluminum upper plate having a known thickness being placed on the substrate or the mother plate, each spindle measured by the descending distance information detection mechanism is lowered by lowering the spindle to its back drilling position. Height position information for each back drilling position,
From the coordinate position information for each area and the coordinate position information of the back drilling position existing on the multilayer printed wiring board or its mother board, the multilayer printed wiring board or its mother board is placed on the lower board during back drilling. In the state, after extracting the back drill processing position existing in each coordinate value area of each area of the lower plate,
A back-drilling method that automatically controls the back-drilling depth in the substrate processing apparatus based on the individual back-drill depth L2c automatically calculated based on the following formula.
L2c = Lnd × (L2m1-αave-tAL) / L2d-td + tAL + angle tan2
Lnd = design surplus length L2m1 = a state in which an aluminum upper plate having a known thickness is placed and fixed on the multilayer printed wiring board placed on the lower plate on the processing table or its mother plate. , Measured height at each back drilling position extracted as existing in the coordinate value range for each area of the lower plate αave = the measured height of the measurement point for each area of the lower plate on the processing table Average value L2d = Designed multilayer printed wiring board thickness td = Left length of design tAL = Specified thickness angle of aluminum upper plate tan2 = Radius of through hole before plating portion × tan {(180 Degree-angle of drill tip angle) ÷ 2} In the back drilling process, a multilayer printed wiring board placed on a lower board on a processing board of a board processing apparatus or an aluminum upper board having a known thickness is placed on a mother board, and further thereon. 8. The back drilling method according to claim 7, wherein an insulating upper plate that can be cut by a spindle is placed.

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