JP2777425B2 - Method of manufacturing pin grid array having multi-stage bonding terminal structure, apparatus for cutting out inner layer terminal thereof, and multilayer substrate for pin grid array - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a method for manufacturing a pin grid array in which bonding terminals are configured in multiple stages, and more particularly, to expose inner side bonding terminals by spot facing. Accordingly, the present invention relates to a method of manufacturing such a pin grid array having a multi-stage bonding terminal structure.

Further, the present invention relates to a device for cutting an inner layer bonding terminal of a pin grid array suitable for use in such a manufacturing method and a multilayer substrate for a pin grid array.

[Conventional technology]

In recent years, with higher integration and more functions of an IC chip, the number of pins on an IC package side on which the IC chip is mounted is also required to be larger. Pin grid array (PG) used as a type of IC package
A) can cope with such an increase in the number of pins.
Here, in this PGA, a surface bonding terminal circuit is formed on the surface, and by increasing the number of terminals of this terminal circuit, it is possible to cope with an increase in the number of pins. However, there is a limit in responding to the increase in the number of pins by the bonding terminal arrangement in one plane on such a plane. To this end, in addition to the surface bonding terminal arrangement formed on the surface, an inner layer bonding terminal arrangement is formed in the substrate, and such a multi-stage terminal arrangement structure is adopted to cope with the increase in the number of pins.

The manufacture of such a PGA having a multi-stage bonding terminal arrangement structure is generally performed by the following procedure. That is, as shown in FIG. 3 (A), a base layer 1 made of an organic insulating material or the like is prepared, and a copper foil layer 2 is formed on the back surface thereof.
On the front side, the IC chip mounting part 3 located at the center
Is formed on the outer peripheral portion of the substrate.
In addition, a surface layer material 6 having a copper foil layer 7 having a window 5 slightly larger than the above-mentioned chip mounting portion 3 is prepared.
A prepreg or an adhesive sheet 9 having a window 8 of the same size as the above-mentioned window 5 is prepared. The adhesive sheet 9 is sandwiched, and the base layer 1 and the surface material 6 are connected to the terminal portion of the inner layer bonding terminal circuit 4. 4a is superposed and bonded in a state where it is exposed. Thus, the laminated substrate 10 having the sectional structure shown in FIG. 3 (B) is formed. Thereafter, a plurality of pin insertion holes 11 extending through the laminated substrate are formed in a lattice shape at the outer peripheral position of the chip mounting portion 3 in the laminated substrate 10, and copper plating is applied to the inner peripheral surfaces of these holes. . Thereafter, the copper foil layer 7 on the surface is etched to form a surface bonding terminal circuit.
After the formation of 12, the terminal portion 12a of the terminal circuit 12 and the terminal portion 4a on the inner layer side are plated with gold, and the copper foil layer 2 on the rear surface side is etched to form a circuit pattern. Then, by mounting the pins 13, a PGA having a two-stage terminal arrangement structure shown in FIG. 3C is formed. Thereafter, the IC chip is mounted on the IC chip mounting portion 3, and the external terminals of the chip and the two-stage terminals on the PGA side are bonded by gold wires.

[Problems to be solved by the invention]

However, the following problem arises in the method of forming a multi-stage bonding terminal array by bonding the surface layer material which has been opened in advance for the chip mounting portion to the side of the base material layer using an adhesive sheet. There is a point.

First, when forming a laminated substrate, it is necessary to precisely position and bond the adhesive sheet and the surface layer material to the base material layer, but such a positioning operation is difficult. Also, when the base material layer and the surface material are bonded in a state where they are not accurately aligned, the terminal portion of the inner layer bonding terminal circuit formed on the surface of the base material layer is not exposed for a required length. Things happen.

In addition, the base material layer and the surface layer material are bonded by heating and melting the adhesive sheet therebetween, but when the adhesive sheet is excessively melted, the resin of the molten adhesive sheet is applied to the inner layer terminal portion. Effluent, and solidify while covering it. Conversely, when the adhesive sheet is insufficiently melted, a gap is formed between the base material layer and the surface material that is not filled with the adhesive, and the inner layer bonding terminal circuit formed on the surface of the base material layer is formed. A situation occurs in which the resin of the adhesive is not sufficiently filled between the circuit patterns to be formed.
When such a gap exists, during the gold plating process,
There is a possibility that the plating solution may enter the gaps and cause the insulation deterioration of the inner layer bonding terminal circuit.

Further, as described above, after forming the laminated substrate in a state where the terminal portion of the inner layer bonding terminal circuit is exposed,
Since copper plating and patterning are performed on the laminated substrate, it is necessary to protect the exposed inner layer side terminal portions in each of these working steps. For this reason, work becomes difficult, and the yield tends to decrease.

As described above, according to the conventional manufacturing method, there is a problem that the manufacturing cost is high and the reliability of the product is low.

An object of the present invention is to provide a multi-stage bonding terminal array structure without passing through a step of bonding a window-opened surface layer material to a base material layer side with an adhesive sheet in view of the drawbacks of the conventional manufacturing method. It is an object of the present invention to propose a method capable of manufacturing a pin grid array having the same. Another object of the present invention is to propose a manufacturing apparatus and a substrate suitable for performing the novel method.

[Means for solving the problem]

In order to solve the above problems, in the method of manufacturing a pin grid array having a multi-stage bonding terminal structure of the present invention, a laminated substrate having a layer configuration in which an inner layer bonding terminal circuit is sandwiched between insulating layers is prepared in advance. After forming the surface bonding terminal circuit on the surface of the laminated substrate, the laminated substrate is counterbored from the surface side using a machine tool such as an NC router machine so that the terminal portion of the inner layer bonding terminal circuit is exposed. I have.

Here, there is conventionally known an NC router machine configured to measure the thickness of the entire laminated substrate and calculate the cutting depth so as to cut out the terminal portion of the inner layer bonding terminal circuit using a machine tool. However, in the laminated board, the distance between the inner layer bonding terminal circuit and the surface layer bonding terminal circuit formed on the surface is about ± 25 μ
There is a variation of about ± 60 μ, whereas the layer thickness of the inner bonding terminal circuit is very thin, about 18 μ to 70 μ. For this reason, by simply setting the cutting depth using a conventional machine tool and cutting the laminated board to this depth, the laminated board is accurately cut down to the inner layer bonding terminal circuit, and It is not possible to always expect a cutting that can leave a layer thickness of the inner layer bonding terminal circuit having a large thickness.

Therefore, in the manufacturing method of the present invention, an eddy current is generated in an inner layer bonding terminal circuit or the like of the laminated substrate by bringing a height detection probe to which a high-frequency current is applied close to the surface side of the laminated substrate. The strength of the high-frequency magnetic field generated by the generated eddy current is measured from the surface layer side of the laminated substrate, and the main shaft of the machine tool is fed based on the measured data, and the lamination is performed by the rotary cutting blade supported at the tip of the main shaft. A counterbore cutting process is performed on the substrate from the surface layer side, and the inner-layer bonding terminal circuit is exposed by controlling the feed amount of the main shaft of the machine tool based on the fluctuation of the high-frequency magnetic field.

Further, the apparatus for cutting out the inner layer bonding terminal used in the above manufacturing method of the present invention includes a counterbore rotary cutting blade supported by a spindle support mechanism and a feed direction of the spindle with respect to the spindle support mechanism. A movable probe,
An eddy current generating means for applying a high-frequency current to the probe to generate an eddy current below or near the cut portion, a detecting means for detecting the strength of the high-frequency magnetic field due to the generated eddy current, and a detected high-frequency magnetic field And a feed control means for calculating a distance between the rotary cutting blade and the portion to be cut based on the calculated value, and controlling a feed amount of the spindle based on the calculated value.

In order to measure the thickness of the insulating layer, it is necessary to generate an eddy current.However, although the inner layer bonding terminal circuit itself can be used as the conductive part where the eddy current is generated, it is effective because the circuit wiring is extremely fine. It is difficult to expect generation of eddy current.
Therefore, on the inner layer bonding terminal circuit forming surface, 1 or 2 formed in an isolated or island shape with respect to this circuit.
By using the multi-layer substrate for the pin grid array provided with the above-mentioned conductive layer for eddy current generation in advance, high-precision shaving is realized.

[Action]

In the method and the apparatus according to the present invention, a probe is arranged close to the surface of the laminated substrate, and a high-frequency current is applied to the probe. When a high-frequency current is applied to the probe, an eddy current is generated in the inner layer bonding terminal circuit and the like on the side of the laminated substrate. This eddy current generates a high-frequency magnetic field. Here, the high-frequency magnetic field varies depending on the insulating film thickness from the inner layer bonding terminal circuit to the surface of the laminated substrate.
Therefore, based on the strength of the high-frequency magnetic field measured at the tip of the probe, the distance from the tip of the probe to the inner layer bonding terminal circuit of the laminated substrate is calculated. Therefore, the distance from the tip position of the rotary cutting blade sent in the main axis direction to the inner layer bonding terminal circuit of the laminated substrate is also calculated. In this case, the accuracy error of the calculated distance is about 5
It is a small amount less than μ. Based on the calculated distance, the feed amount of the rotary cutting blade in the main spindle direction is controlled,
The surface material of the laminated substrate is spotted by the rotary cutting blade, and the terminal portion of the inner bonding terminal circuit is cut out.

In this manner, according to the manufacturing method and apparatus of the present example, it is possible to perform the counterbore of the laminated substrate with high accuracy of less than about 5 μm.
It can be cut out with the required layer thickness.

〔Example〕

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

FIG. 1 shows the entire configuration of a cutting device suitable for use in the manufacturing method of the present invention. This device 21 is composed of a generally known NC router machine,
In the figure, only the configuration of the main parts related to the present invention is shown. In the figure, reference numeral 22 denotes a spindle, and this spindle is
A spindle motor 23 is connected to the base end side of the spindle 22, and the rotation of the motor causes the spindle 22 to reciprocate in its axial direction, that is, in the Z-axis direction. A router blade (carbide or diamond) 24, which is a rotary cutting blade, is fixed to the tip of the main shaft via a chuck, and the router blade is rotated by a drive motor (not shown) to rotate the work 31. Counterboring of the area to be cut 32 is performed.

Here, the work 31 is a PGA substrate having a multi-stage terminal arrangement structure including a surface layer bonding terminal and an inner layer bonding terminal. In this PGA substrate, a rectangular concave portion is formed in the central portion on the surface layer side by the device 21 of the present example. After the concave portion is formed, the IC chip is mounted in the concave portion, and thereafter, the external terminal of the chip is bonded to the surface layer and the inner layer bonding terminal on the side of the PCA substrate.

Next, a probe 41 is installed at a position adjacent to the router blade 24 described above. The probe 41 is supported by a bracket 42 so as to be able to move up and down with respect to a servo mechanism 30a attached to the spindle support mechanism 30. That is, the probes 41 are arranged in parallel with the main axis, and like the router blade 24, are moved in the main axis direction.

That is, when measuring the height, the router blade 24 is raised and the probe 41 is moved down for measurement, and when cutting, the probe 41 is raised and the router blade 24 is moved down for cutting. In addition, a method of calculating the height insulation value of the inner copper foil by measuring the position from the probe tip to the inner copper foil while keeping the height position of the probe 41 constant, and lowering and insulating the probe 41 until it comes into contact with the surface layer There is a method of measuring the thickness of the layer and calculating the absolute value of the height of the inner layer copper foil.

The probe 41 can apply a high-frequency current by a high-frequency current generation source 43. By applying the high-frequency current to the probe 41, an eddy current is generated in the inner bonding terminal circuit, which is a conductive layer formed on the work 31 side. I do. Also,
The probe 41 also functions as a detection terminal for detecting the intensity of the high-frequency magnetic field on the workpiece cutting region caused by the eddy current as a change in current value. The current due to the high-frequency magnetic field detected by the probe 41 is detected as a voltage value from both ends of the resistor 44, and this voltage value is supplied to the input processing circuit 51. The voltage input to the input processing circuit 51 is amplified and digitized here,
Central processing unit (CPU) 5 via input interface 52
Supplied to 3. The CPU 53 calculates the distance from the position of the tip of the router blade 24 to the conductive layer in the work 31 from a look-up table stored in advance in a fixed storage device (ROM) 54 based on the supplied digital signal. . The feed amount of the spindle is calculated based on the calculated value, and the calculated value is output from the CPU 53 to the drive circuit 56 via the output interface 55 as a feed control signal of the spindle. In the drive circuit 56, the spindle feed motor 23 is driven based on the feed control signal of the spindle, and the router blade 24 supported at the tip of the spindle is sent a fixed distance toward the work or in the opposite direction.

Next, with reference to FIG. 2, a method of manufacturing a PGA substrate having a multi-stage bonding terminal using the above-described scraping device will be described.

First, as a PGA substrate serving as the work 31, a laminated substrate having a layer configuration in which an inner layer bonding terminal circuit is formed between insulating layers is manufactured. That is, as shown in FIG. 2A, the inner bonding terminal circuit 64 is provided between the base material layer 61 and the surface material 66.
The laminated substrate 31 on which is formed is manufactured. Next, a copper foil layer 67 for a surface layer bonding terminal circuit is formed on the surface of the laminated substrate 31, and a copper foil layer 62 is also formed on the back surface. Here, in the inner layer bonding terminal circuit 64, a rectangular window 64a is opened in a central portion, and a portion facing the outer peripheral edge of the window 64a is used as an inner layer bonding terminal 64b. In the present example, a target conductive layer 64c, which is an eddy current generation region isolated from other inner layer bonding terminal circuit portions, is formed at the center of the window 64a.

Next, as shown in FIG. 2 (B), through holes 71 for mounting pins are formed in the laminate 31 and copper plating (through hole plating) is applied to the inner peripheral surface thereof. After this, the copper foil layer on the front side
The surface bonding terminal circuit 67a is formed by etching the 67, and the copper foil layer 62 on the back side is also etched to form a circuit pattern. The formed surface bonding terminal circuit 67a has a circuit pattern in which a rectangular window 67b is opened at the center thereof, and a portion facing the outer peripheral edge of the window 67b is a surface bonding terminal 67c. Here, the size of the window 67b is set to be slightly larger than the size of the window 64a formed in the inner layer bonding terminal circuit.

Next, the tip 41a of the probe 41 is set so as to be located immediately above the center of the multilayer body 31. When a high-frequency current is applied to the probe 41 in this state, an eddy current is generated in the target conductive layer 64c inside the multilayer body. The high-frequency magnetic field generated by the eddy current is detected by the probe 41, and a voltage value corresponding to the strength of the detected high-frequency magnetic field is input to the CPU 53 as a digital value. The CPU 53 calculates the distance from the probe tip 41a to the target conductive layer 64c based on the digital value input as described above. Here, since the distance between the probe tip 41a and the router blade tip is always held by the same support mechanism 30, the distance from the surface of the laminated substrate 31 to the target conductive layer 64c can be calculated based on the calculated distance. .

In this way, the target conductive layer 64
After measuring the distance to c, counterboring with the router blade 24 is performed.

Accordingly, the depth of the counterbore can be accurately controlled so as to reach just the position where the inner layer bonding terminal 64b is exposed.

Thereafter, as shown in FIG. 2 (D), the inside portion of the window 64a of the inner layer bonding terminal circuit is seated at a certain depth to form a recess 61a for mounting an IC chip. In the spot facing in this case, the target conductive layer is also cut together. However, after the inner bonding terminal 64b is exposed, it is not necessary to control the counterbore depth so accurately, so that the counterbore depth control may be performed in a control mode generally performed conventionally.

Next, after the counterbore processing is completed, the surface layer bonding terminal 67c and the inner layer bonding terminal circuit 64b are plated with gold. In this way, a PGA substrate having multi-stage bonding terminals is formed. Thereafter, the IC chip 74 is mounted, and the external terminals and the terminals on the substrate are bonded by gold wires.

Other Embodiments In the above example, the case of counterbore processing of the PGA substrate was described, but the cutting device of the present invention is used for exposing a circuit portion formed inside other multilayer boards. Can be used. It can also be used for drilling blind holes. In short, the shaving apparatus of the present invention can be applied to the case where shaving at an accurate depth is required.

Further, in the above example, the PGA substrate as the work used was a substrate in which the target conductive layer 64c was previously arranged, but even when such a conductive layer 64c was not used, the inner layer bonding of the PGA substrate was performed. The cutting depth can be controlled based on the overcurrent generated in the terminal circuit.

It goes without saying that a multi-axis shaving apparatus can be constructed which has a number of sets of such a measuring probe and a main shaft for the shaving blade and can control the height for each axis.

〔The invention's effect〕

As described above, in the present invention, a counterboring process is performed on a PGA laminated substrate on which an inner layer bonding terminal circuit is formed in advance, so that the inner layer bonding terminals are exposed, and in the counterboring process, Move the probe to which the high-frequency current is applied close to the laminated substrate,
The strength of the high-frequency magnetic field due to the eddy current generated in the inner bonding terminal circuit portion in the substrate is measured, and the spot facing depth is controlled based on the measured value. Therefore, compared to the conventional method of forming a multi-stage bonding terminal by laminating a surface layer material that has been previously opened with a window on a base material layer with an adhesive, the positioning work at the time of lamination becomes unnecessary, and bonding No adverse effects due to excessive melting or insufficient melting of the material occur.

Further, according to the present invention, since the position of the inner layer bonding terminal circuit in the laminated substrate can be accurately measured as compared with the conventional counterbore depth control method, the inner layer bonding terminal portion is exposed in an appropriate state. be able to.

Further, according to the present invention, it is possible to obtain not only the above-described counterboring of the PGA laminated substrate, but also the effect that the counterboring of the work having the conductive layer portion and the boring of the blind hole can be performed with high accuracy. .

[Brief description of the drawings]

FIG. 1 is a schematic block diagram showing a main configuration of a cutting apparatus according to one embodiment of the present invention, and FIGS. 2 (A) to 2 (D) show a method of manufacturing a PGA laminated substrate using the apparatus of FIG. FIG. 3A to FIG. 3C are cross-sectional views illustrating a conventional method for manufacturing a PGA laminated substrate. [Explanation of Signs] 21: Cutting machine 22: Spindle 24: Router blade 30: Spindle support mechanism 31: Work (PGA laminated board) 41: Probe 43: High-frequency current source 53: CPU 54 ROM 61 Base layer 64 Inner bonding terminal circuit 64a Window part 64b Inner bonding terminal 64c Target conductive layer 66 Surface material 67a Surface bonding terminal circuit 67b Window 67c Surface bonding terminal 71 Through hole 73 Pin.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI H01L 23/12 N

Claims (4)

(57) [Claims] 1. A laminated substrate having a layer structure in which an inner layer bonding terminal circuit is sandwiched between insulating layers, a surface layer bonding terminal circuit is formed on the surface of the laminated substrate, and a high-frequency current is applied to the surface side of the laminated substrate. By bringing the height detection probe approached, an eddy current is generated in the inner layer bonding terminal circuit and the like of the laminated substrate, and the intensity of a high-frequency magnetic field generated by the generated eddy current from the surface layer side of the laminated substrate is measured. Then, based on the measurement data, a counterbore cutting process is performed on the laminated substrate from the surface side thereof by a rotary cutting blade supported at the tip of the main shaft, so that the inner layer bonding terminal circuit is exposed. A method for manufacturing a pinglit array having a multi-stage bonding terminal structure. 2. An apparatus for cutting the inner layer bonding terminal used in the method according to claim 1, wherein the cutting apparatus comprises a counterbore rotary cutting blade supported by a spindle support mechanism; A probe movable with respect to the spindle support mechanism in the feed direction of the spindle, an eddy current generating means for applying a high-frequency current to the probe to generate an eddy current in the inner layer bonding terminal circuit and the like; Detecting means for detecting a high-frequency magnetic field due to eddy current; calculating a distance between the rotary cutting blade and the cut portion based on the strength of the detected high-frequency magnetic field; and controlling a feed amount of the main spindle based on the calculated value. And a feed control means for cutting the inner layer bonding terminals of the pin grid array. 3. A shaving method for shaving a work in which a conductive layer is formed on at least a part of an inner layer, wherein a high-frequency current is applied to a surface side of the work, and a height detecting probe is provided. , An eddy current is generated in the conductive layer, the strength of a high-frequency magnetic field generated by the generated eddy current is measured from the surface side of the work, and based on the measured data, a work shaving device is used. The distance between the rotary cutting blade supported at the spindle tip and the conductive layer of the work is calculated, and based on the calculated value, the feed amount of the main spindle is controlled, and the rotary cutting blade controls the feed amount for the work. A method for shaving a work having a conductive layer, characterized by shaving from the front side. 4. An apparatus for cutting out a workpiece using the method according to claim 3, wherein the workpiece is provided with a conductive layer on at least a part of an inner layer. A device,
The shaving apparatus includes a rotary cutting blade supported by a spindle support mechanism, a probe movable in a feed direction of the spindle with respect to the spindle support mechanism, and applying a high-frequency current to the probe to apply the workpiece to the workpiece. A high-frequency current applying means for generating an eddy current in the conductive layer, a detecting means for detecting the strength of the high-frequency magnetic field due to the eddy current generated in the conductive layer of the work, and Cutting a work having a conductive layer, comprising: a feed control unit that calculates a distance between the rotary cutting blade and the conductive layer of the work, and controls a feed amount of the spindle based on the calculated value. apparatus.