JPH0659622B2 - Polishing equipment - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a polishing apparatus for performing polishing finish on an object to be processed, which is made of metal, ceramics, semiconductor material, etc., with extremely high precision of, for example, micron order. .

[Conventional technology]

As a head chip used for a magnetic head of a VTR,
As shown in FIG. 3, attention has been paid to a sendust head chip (91) in which a pair of chip halves (90) (90) made of sendust are bonded and integrated with each other.

The head chip (91) has a high accuracy (approximately ± 0.5 μm) because the thickness B (for example, 24 μm) is the track width of the magnetic head.
m or less). For this purpose, conventionally, unfinished chips (9) sliced in advance to a desired thickness (for example, a thickness of 160 to 180 μm) using a polishing apparatus as shown in FIGS. 10 to 12 are used. Was subjected to lap polishing to obtain a predetermined accuracy (for example, a tolerance of 24 ± 0.5 μm).

First, as shown in Fig. 10, a large number of chips to be polished (9)
Is attached to the surface of the ferrite substrate (21) having a constant thickness by using an adhesive.

After attaching a large number of chips (9) to a plurality of ferrite substrates (21), these ferrite substrates (21) are mounted on the mounting surface (10) of the disc-shaped holder (1) as shown in FIG. Fix at equal intervals. The mounting surface (10) has a high flatness. Each ferrite substrate (21) is fixed on the mounting surface (10) by fixing wax (not shown) formed by heating and melting pine and paraffin to the periphery.

As shown in FIG. 12, the holder (1) has a plurality of stoppers (6) having a diamond tip (60) at the tip.
However, it is equipped with the tip protruding from the mounting surface (10). The protrusion amount can be adjusted by rotating the stopper (6).

The holder (1), ferrite substrate (21) and stopper
The jig consisting of (6) is turned upside down as shown in FIG. 11, and a large number of chips to be mounted face down, and the flat lapping machine.
Equipped to (4). The flat lapping machine (4) is in contact with the outer peripheral surface of the holder (1) mounted on the lapping disc (40) above the lapping disc (40) which is rotationally driven by the motor (41). A drive device (7) including a pair of drive rollers (70) (70) for rotating by rotating is provided.

The holder (1) is held at a fixed position by the rotation of the lap disc (40) and the rollers (70), (70), and revolves relative to the lap disc (40) and rotates at the same time. Free abrasive grains are supplied between the large number of chips (9) held by the holder (1) and the lap disc (40). As a result, the tip (9) is brought into floating contact with the lapping disc (40) and the surface thereof is polished, so that the thickness thereof is gradually reduced. At this time, adjust the amount of protrusion of the stopper (6)
By setting the total value of the thickness of 1) and the thickness of the target chip, a chip having a desired thickness can be obtained.

[Problems to be solved by the invention]

In the above polishing apparatus, the time when the tip (9) is polished to a predetermined thickness is not known, and the polishing is terminated after the empirically determined processing time has elapsed. However, variation in the thickness of the unfinished chip (9) is unavoidable, so the set value of the processing time must be increased. As a result, the chip having a small thickness before processing is continued to be polished even after being polished to a predetermined thickness. This not only wastes the processing time, but also causes a problem that a processing error occurs in the object to be processed (92) whose value increases as the distance from the stopper (6) increases as shown in FIG. 12 due to excessive polishing. .

[Means for solving problems]

The polishing apparatus according to the present invention has at least one ceramic gauge plate (3) as a polishing amount control tool, and the gauge plate (3) has a constant thickness according to the finished thickness of the workpiece. And is detachably fixed on the mounting surface (10) of the holder (1) close to the object to be processed.

Further, a polishing amount detecting device that emits a laser beam toward the upper surface of the holder (1) and detects the laser beam reflected on the holder (1) to detect the vertical movement amount of the holder (1). (5) includes a signal processing circuit that issues a polishing stop command to the polishing machine when the change in the movement amount of the holder (1) converges to a predetermined value or less.

[Action]

Mount the object to be processed on the mounting surface (10) of the holder (1) equipped with the polishing amount control tool, place the holder (1) on the polishing surface of the polishing machine, and polish the surface of the object to be processed. Give.

The holder (1) is lowered by the polishing amount as the polishing of the object to be processed progresses.

The polishing amount detection device detects the amount of movement of the holder (1) that is moving down with time with extremely high accuracy, for example, on the order of microns.

When the object to be machined is ground to a predetermined thickness, the polishing amount control tool is brought into sliding contact with the polishing surface of the polishing machine, which increases the polishing resistance and sharply reduces the polishing speed.

Since the decrease in the polishing speed appears as a decrease in the descending speed of the holder (1), the polishing is stopped when the change rate of the movement amount of the holder (1) detected by the polishing amount detection device converges to a predetermined value or less. By doing so, the object to be machined is finished to a thickness corresponding to the amount of protrusion from the mounting surface (10) of the polishing amount control tool.

〔The invention's effect〕

By presetting the amount of protrusion from the mounting surface (10) of the polishing amount control tool to the thickness of the processing object to be finished, it is possible to polish the processing object to the specified thickness without dead time. However, there is no processing error due to excessive polishing.

〔Example〕

FIG. 1 shows an example in which the polishing apparatus according to the present invention is applied to the magnetic head chip polishing apparatus shown in FIG.

The base (8) is equipped with a flat lapping machine (4) and a drive unit (7) having the same structure as shown in FIG. Further, a polishing amount detecting device (5) described later is arranged on the side of the device (7).

The holder (1) placed on the lap disc (40) of the flat lapping machine (4) has substantially the same structure as the conventional one shown in FIGS. 10 and 11, but FIG. As shown, a plurality of through holes (11) are formed at equal intervals on the circumference of the circumference.

The substrate (2) to which the chip (9) is attached has the same shape as the conventional one as shown in FIG. 4, but is made of ceramic material.

As shown in FIG. 2, the substrate (2) is a through hole of the holder (1).
The screw (80) is inserted into (11), and the tip of the screw (80) is screwed onto the back surface of the substrate to be fixed. Therefore, it is not necessary to fix with wax as in the prior art. As a result, the plurality of substrates (2) are accurately positioned on the mounting surface (10) of the holder (1).

In the present embodiment, a plurality of gauge plates (3) having a predetermined thickness are used as the polishing amount regulating tool (described below).
(See FIGS. 8 and 9). These gauge plates (3)
The ceramic plate is formed into a trapezoidal shape and the thickness is evenly finished with high accuracy. Each gauge plate (3) is a screw inserted into the through hole (11) of the holder, like the board (2).
It is fixed on the mounting surface (10) at regular intervals by (80). As a result, the gauge plates (3) are arranged with almost no space between the substrates (2) on the mounting surface (10).

The polishing amount detector (5) is a laser generator as shown in FIG.
(50) and a reflector mounted in the center of the top of the holder (1)
(52) and a laser beam (incident beam) (54) emitted from the laser generator (50) as shown in FIG.
It is deflected in the vertical direction toward and the reflecting mirror (52)
An interferometer (51) for receiving the laser beam (reflected beam) (56) reflected by the interferometer and interfering the incident beam and the reflected beam with each other, and an interference beam (55) emitted from the interferometer (51) And a receiver 53 which outputs a signal indicating the amount of movement of the holder 1 by sensing the signal (above, manufactured by YHP).

The output signal from the receiver (53) is connected to a signal processing circuit (not shown). Specifically, the circuit is composed of a microcomputer, which performs arithmetic processing described later on the output signal and issues a polishing stop command to the polishing machine when the movement amount of the holder (1) converges to a predetermined value or less. is there.

First, as shown in FIG. 2, the ceramic substrate (2) having a sliced chip (9) having a thickness of 160 to 180 μm is fixed to the holder (1), and the ceramic substrate (2) is fixed to the holder (1).
Is mounted on a flat lapping machine (3), and one side of the tip (9) is subjected to rough polishing for a certain time. At this time, the polishing amount may be about 30 μm, for example. After the rough polishing is completed, the ceramic substrate (2) is once removed from the holder (1) and immersed in an organic solvent to peel off the chip (9). Next, after washing the chip, it is turned over and again fixed to the ceramic substrate (2) by adhesion, and the ceramic substrate (2) is mounted on the holder (1).

Next, the gauge plate (3) is used to finish polish the tip (9) which has been subjected to rough polishing.

The gauge plate (3) is formed to have a thickness A that matches the total value of the thickness C of the ceramic substrate (2) and the thickness B of the head chip (91) as a product shown in FIG. (See FIGS. 8 and 9), the surface of the gauge plate (3) is slightly lower than the surface of the tip (9) having the thickness B ₀ after the rough polishing when mounted on the holder (1). .

Ceramic board (2) with chip (9) attached and gauge plate
The holder (1) having (3) and (3) is placed on the flat lapping machine (4) with the chip (9) facing down. The holder (1) is rotationally driven by the driving device (7), and the tip (9) is polished.

As shown in FIG. 5, the laser beam (54) emitted from the laser generator (50) first enters the interferometer (51) and is dispersed therein, and one of the spectral beams is received by the receiver (53). The other spectroscopic beam is reflected toward the reflecting mirror (52) mounted on the holder (1). The spectroscopic beam is reflected by a reflecting mirror (52), and the reflected beam (56) enters an interferometer (51) and merges with the other spectroscopic beam,
It becomes an interference beam (55) and returns to the receiver (53). holder
When (1) moves up and down, Doppler frequency modulation occurs in the reflected beam (56), so the movement amount of the holder (1), that is, the polishing amount, can be calculated by performing frequency analysis on the interference beam (55). Can be done.

Since the holder (1) revolves around the lap disc at the same time as it rotates as described above, it is inevitable that the holder (1) vibrates vertically to some extent. Therefore, the measurement data of the above polishing amount detection device (5) should be
The error based on the vibration of (1) will be included. In this embodiment, in order to remove the error and automatically stop the polishing apparatus immediately after the polishing, the data processing as shown in FIG. 6 is performed by using the signal processing circuit.

First, initial data necessary for calculation, such as a sampling period and a sampling interval described later, are input (91) to the signal processing circuit.

The polishing device is started and processing is started (92).

The measured data, that is, the polishing amount detected by the receiver (53) of the polishing amount detection device (5) is taken in at a set sampling interval (for example, 50 msec) (93).

Data acquisition continues until the set sampling period (for example, 50 seconds) elapses (94).

Next, the N pieces of data taken within the sampling period are arithmetically averaged (95), and the calculation result is stored.

For each sampling cycle, the difference from the previous cycle or the calculation result in the previous cycle is calculated, and it is judged (96) whether or not the polishing amount has converged.

When the difference between the calculation results converges to a predetermined value (for example, 0.5 μm) or less, a stop command (97) is issued to the flat lapping machine (4) and the driving device (7).

By the above arithmetic processing, the error due to the vibration of the holder (1) is canceled out, and the accurate polishing amount calculation result can be obtained.

In the above polishing apparatus, a polishing amount detecting device (5) is mounted on a base (8) equipped with a flat lapping machine (4) and a driving device (7).
Are integrally arranged, the vibration generated in the base (8) during processing does not directly affect the measurement data.

FIG. 7 shows the time change of the accumulated polishing amount. At the initial stage of polishing, as shown in FIG. 8, since only the surface of the tip (9) is in sliding contact with the lap disc (40), the tip polishing speed (μm / min) is relatively fast and It is constant. As the polishing progresses and the surface of the gauge plate (3) begins to come into sliding contact with the lapping disc (40) as shown in FIG. 9, the gauge plate (3) is made of ceramic and has high wear resistance. Therefore, the polishing rate drops sharply and approaches zero. At this time, the polishing is automatically stopped as described above.

In addition, even if uneven load is applied to the tip during polishing of the tip and the amount of polishing becomes uneven, one end of the tip is
At the same time as being ground to the same thickness as (3), the gauge plate (3)
Corresponds to the polishing surface of the polishing apparatus, and the polishing thereafter proceeds to the thick portion of the chip. Therefore gauge plate
When (3) comes into close contact with the polishing surface of the polishing apparatus and polishing is stopped, the chip is finished to have a uniform thickness B as shown in FIG.

Since the gauge plate (3) is removable, it can be replaced if the thickness changes due to long-term use. or,
By using a plurality of types of gauge plates (3) having different thicknesses, the chips can also be polished in stages.

It goes without saying that the polishing apparatus according to the present invention is not limited to the illustrated embodiment and can be variously modified within the technical scope described in the claims.

[Brief description of drawings]

FIG. 1 is a perspective view of a polishing apparatus according to the present invention, FIG. 2 is a perspective view of a jig used in the polishing apparatus, FIG. 3 is a perspective view of a sendust chip, and FIG. 4 is a slope of a substrate to which a chip is attached. Figure,
FIG. 5 is an optical path diagram of the polishing amount detecting device, FIG. 6 is a flowchart, FIG. 7 is a graph showing changes in the polishing amount, FIGS. 8 and 9 are explanatory diagrams of the polishing process, and FIG. FIG. 11 is a perspective view of a jig, FIG. 11 is a perspective view of a conventional polishing apparatus, and FIG. 12 is a front view of a conventional polishing amount control tool. (1) …… Holder, (2) …… Ceramic substrate (3) …… Gauge plate, (4) …… Flat lapping machine (5) …… Abrasion amount detector, (9) …… Chip

Claims (4)

[Claims] 1. A polishing machine having a polishing surface on its upper surface for polishing an object to be machined, and a mounting surface on which the object to be machined is mounted and fixed so as to face the polishing surface above the machine. A holder (1) having a lower surface (10) capable of moving up and down, a polishing amount restricting tool protruding from a mounting surface (10) of the holder (1), and a laser beam directed toward the upper surface of the holder (1). With the holder
(1) A holder that senses the laser beam reflected above
Equipped with a polishing amount detection device (5) that detects the amount of vertical movement of (1), the workpiece fixed to the mounting surface (10) of the holder (1) faces the polishing surface of the polishing machine. In a polishing apparatus in which polishing is carried out by sliding slidingly, the polishing amount regulating tool is at least 1
Consisting of a ceramic gauge plate (3), the gauge plate (3)
Has a constant thickness according to the finished thickness of the object to be processed and is detachably fixed on the mounting surface (10) of the holder (1) close to the object to be processed. 5) A polishing machine characterized by comprising a signal processing circuit for issuing a polishing stop command to the polishing machine when the change in the movement amount of the holder (1) converges to a predetermined value or less. 2. The object to be processed comprises a chip (1) to be ground to a predetermined thickness, which is adhered to a substrate (2) having a constant thickness. The substrate (2) has a holder (1) with the chip facing downward. ) The polishing device according to claim 1, which is detachably fixed to the polishing device. 3. A patent in which the holder (1) is disc-shaped, and a plurality of substrates (2) and gauge plates (3) are alternately arranged close to each other on the circumference of the mounting surface (10). The polishing device according to claim 2. 4. The polishing apparatus according to claim 2 or 3, wherein the substrate (2) is made of ceramic.