JP5455576B2 - Multi-wire saw prevention method - Google Patents

Description

The present invention relates to a method for preventing narrowing or spreading of a pitch between a large number of parallel wires in a multi-wire saw due to surface tension of a working fluid.

In the multi-wire saw, a workpiece such as a silicon ingot or a silicon block is brought into contact with a large number of parallel wires in a running state, and the workpiece is cut into a large number of thin wafers. At the time of cutting, a machining fluid such as coolant or slurry is supplied to a number of wires.

The wire is wound in multiple between a plurality of main rollers, and is parallel in a cutting area corresponding to the workpiece. Since the pitch between the wires in the cutting area is regulated by the groove pitch of the main roller with multiple grooves, the thickness of the wafer after cutting is determined by the groove pitch of the main roller and the wire diameter.

In the wafer cutting process for solar cells, thinning is progressing, and as the thinning progresses, the interval between the wires is narrowed. If the machining fluid does not adhere evenly to the wire in the cutting area but partially adheres, the wire partly approaches due to the surface tension of the machining fluid, so the wire pitch at that part may be narrower than the specified pitch. , Expand. Such a wire shift appears remarkably at an intermediate position between the main rollers in the wire cutting area corresponding to the workpiece.

The above-mentioned wire deviation generally starts to appear at a wire pitch of 0.5 mm or less, particularly easily around 0.3 mm, although it depends on the viscosity of the machining fluid. When cutting into the workpiece is started with such a wire shift occurring, irregular cut grooves are formed in the workpiece at the initial stage of cutting, and the wire continues cutting following the irregular cut grooves. Become. Therefore, the thickness of the wafer varies, and the products after the cutting process become uneven.

On the other hand, in Patent Document 1, Patent Document 2 and Patent Document 3, in order to uniformly apply the machining liquid to a large number of wires, a large number of areas on both sides in the traveling direction of the wire are removed from the cutting area below the workpiece. A horizontal plate (a working fluid receiving plate member, a fluid receiving member, and a slurry receiving plate) is disposed under the wire so as to approach the wire, and the working fluid is supplied to the upper surface of the plate. All of these technologies aim to evenly apply the machining fluid to a large number of wires, and temporarily collect the machining fluid on the upper surface of the plate before the wire enters the cutting area below the workpiece. Therefore, it cannot be applied to the cutting area below the workpiece, particularly the prevention of wire displacement due to the surface tension of the working fluid at the intermediate position between the main rollers, that is, the prevention of narrowing or spreading of the wire pitch.

JP-A-9-183118 JP-A-11-188601 JP-A-11-207596

Accordingly, an object of the present invention is to prevent the wire from being displaced due to the surface tension of the working fluid partially adhered to a large number of wires in a multi-wire saw.

Based on the above problems, the present invention is a multi-machine that cuts a workpiece into a plurality of thin wafers by bringing the workpiece into contact with the traveling wire while supplying the machining liquid to the plurality of wires parallel to each other at a predetermined pitch. In a wire saw, a liquid holding plate is arranged in the generation area near the wire under the cutting area of the wire, the processing liquid is filled on the liquid holding plate, and the entire wire in the generation area near the wire is immersed in the processing liquid. By preventing the machining liquid from partially adhering to the wire , it is possible to prevent the wire from being displaced due to partial surface tension of the machining liquid .

Here, the generation area near the wire means that in a cutting area of a large number of wires, when the processing liquid is partially attached to the wires and the surface tension of the processing liquid acts between the wires, the processing liquid This refers to the area where the wire is moved by the partial surface tension. As described above, the position of the pitch between the multiple wires is regulated by the grooves of the main roller, but in particular, at the intermediate position between the two main rollers, that is, at the cutting area of the wire located below the workpiece, Since it is away from the groove of the main roller, the position is hardly regulated, and the wire is likely to be shifted by a small force in the orthogonal direction to each wire. When a wire shift occurs in the wire cutting region, the wire shift phenomenon at that position spreads near the groove of each main roller while gradually decreasing the displacement amount of the wire. Therefore, the generation area near the wire is originally a cutting area of the wire located below the workpiece, that is, an intermediate position between both main rollers. Preferably, it can be said to be the entire area between both main rollers.

More specifically, the multi-wire saw wire misalignment prevention method according to the present invention brings a workpiece into contact with a number of traveling wires while supplying a machining fluid to a number of wires parallel to each other at a predetermined pitch. In a multi-wire saw that cuts into a large number of thin wafers, a liquid holding plate is placed in the generation area near the wire below the large number of wires corresponding to the workpiece, and a gap for liquid holding is provided between the large number of wires and the liquid holding plate. When a workpiece is started to be cut by running a large number of wires , the processing liquid is supplied onto the liquid holding plate from a dedicated nozzle formed on the liquid holding plate, and the processing liquid is supplied onto the liquid holding plate. And the entire wire above the liquid holding plate is immersed in the machining liquid to prevent the wire from being displaced due to the surface tension of the machining liquid partially attached to the wire.

Wire skew correcting method of the multi-wire saw according to the present invention, by each wire Wa over click cutting start after the cut-forming of the workpiece, and moving the liquid holding plate to the retracted position (claim 2).

Further, the wire skew correcting method of the multi-wire saw according to the present invention is a pressurized coating liquid was supplied from above the nozzle in the liquid-holding-plate (claim 3).

Furthermore, in the multi-wire saw wire misalignment prevention method according to the present invention, the liquid holding plate is constituted by a single plate, and the liquid holding plate is moved to the retracted position after forming the cut at the start of workpiece cutting by each wire (claim) Item 4 ), or the liquid holding plate is configured as a connecting body of a plurality of divided plates, and after the cuts are formed at the start of workpiece cutting by the respective wires , the divided plates are rotated and moved to the retracted position (claims). Item 5 ).

According to the multi-wire saw wire slip prevention method according to the present invention, the processing liquid is filled at least on the liquid holding plate in the generation area near the wire with respect to many horizontal wires in the cutting area, and the entire wire is immersed in the processing liquid. In addition, since the machining fluid does not partially adhere to the wire and the surface tension of the partial machining fluid does not affect other wires, a large number of wires in the cutting area do not generate partial wire deviation. For this reason, there is no need for special considerations such as lowering the wire speed at the start of workpiece processing, and thin wafer cutting can be performed with no variation in thickness without special measures on the workpiece side. (Claim 1). In particular, since the processing liquid is supplied onto the liquid holding plate from a dedicated nozzle formed on the liquid holding plate, the film of the processing liquid in which the entire wire is immersed on the liquid holding plate is good even when the viscosity of the processing liquid is low. It can be reliably formed as a state (Claim 1).

By each wire Wa over click cutting start after the cut-forming of the workpiece, since the liquid holding plate is moved to the retracted position, the cutting machining of the workpiece can continue without being impaired in the liquid holding plate (claim 2).

Pressurized coating liquid can be supplied from above the existing nozzles on the liquid holding plate (claim 3).

Further, by forming the liquid holding plate by one plate, the configuration is simplified, after cut-forming at the start of the work cut by the wire, it is easy to move to the retracted position of the liquid holding plate (claim 4 ). In addition, in the configuration in which the liquid holding plate is configured as a connecting body of a plurality of divided plates and each divided plate is rotated and moved to the retracted position after the cut is formed at the start of workpiece cutting by each wire, the rotation of each divided plate is performed. since it is retracting operation by movement, their supporting means and evacuation operation can be simplified (claim 5).

It is a side view of the principal part of a multi-wire saw based on the multi-wire saw wire slip prevention method. In a multi-wire saw, it is a fragmentary sectional view of the relation between the groove of a main roller and a wire. It is a partial expanded sectional view of the state where the processing liquid was filled on the liquid holding plate based on the multi-wire saw wire slip prevention method. It is a partial expanded sectional view of the state where a machining fluid was partially attached to a large number of wires and the wire was raised. It is a side view of the principal part of the example which comprises a liquid holding plate as a connection body of a some division | segmentation board, and rotates each division | segmentation board and moves to a retracted position. FIG. 6 is a partial enlarged cross-sectional view of an example in which a dedicated nozzle is formed on the liquid holding plate, and each divided plate is rotated and moved to a retracted position.

1 and 2 show a main part of a multi-wire saw 1 which is a premise of the multi-wire saw wire slip prevention method of the present invention. As illustrated in FIG. 1, the multi-wire saw 1, as an example, runs multiple wires 3 wound between two parallel grooved main rollers 2, and a silicon ingot or silicon is cut in the cutting region of the wires 3. By pressing the workpiece 4 such as a block, the workpiece 4 is cut into a large number of thin wafers. The workpiece 4 is held by the base plate 5 and is moved in the direction of machining feeding indicated by an arrow.

As shown in FIG. 2, each groove 2 a of the main roller 2 is a V-shaped annular groove, and is formed independently on the outer peripheral surface of the main roller 2 corresponding to the wire pitch P. The wire 3 is placed in the corresponding groove 2a of the two main rollers 2 in the cutting area facing the work 4, that is, the upper area in FIG. Is displaced by one pitch from the groove 2a of one main roller 2 to the groove 2a of the other main roller 2 in a non-cutting region that does not face the workpiece 4, that is, the lower region in the example of FIG. Therefore, it is slightly crossed with respect to the center line (axial core) of the main roller 2.

At the time of processing the workpiece 4, the multi-wire saw 1 supplies the workpiece 4 to the cutting region of the wire 3 while supplying a processing liquid 7 such as coolant or slurry from one or more nozzles 6 provided above the wire 3. By pressing, the workpiece 4 is cut into thin pieces and processed as a large number of thin wafers. The thickness t of the wafer after cutting corresponds to the distance between the adjacent wires 3 as shown in FIG.

In the multi-wire saw according to the present invention, the liquid holding plate 8 is provided in the above-described multi-wire saw 1 in a region near the wires below the numerous wires 3 corresponding to the workpiece 4 as shown in FIG. The liquid holding gap is formed between the numerous wires 3 and the liquid holding plate 8, and when the workpiece 4 is started to be cut by the traveling of the numerous wires 3, The whole of the wire 3 above the liquid holding plate 8 is filled with the machining liquid 7 and immersed in the machining liquid 7 to prevent the wire from being displaced due to the surface tension of the machining liquid 7 partially attached to the wire 3 .

The liquid holding plate 8 is configured as a flat plate or a top-opening basin-shaped container, and is usually arranged in a state parallel to a large number of horizontal wires 3 in a cutting area. However, even if the liquid holding plate 8 is slightly inclined, when the processing liquid 7 is supplied from the upper nozzle 6 and the processing liquid 7 is filled on the upper surface of the liquid holding plate 8, the upper surface of the processing liquid 7 is It rises and becomes a film-like horizontal liquid surface. At this time, a large number of horizontal wires 3 are immersed in the machining liquid 7 under the same conditions, and therefore the surface tension of the machining liquid 7 does not reach the numerous wires 3.

Thus, at the start of cutting, the machining liquid 7 is filled on the liquid holding plate 8 at least in the generation area near the wires with respect to a large number of wires 3 that are horizontal in the cutting area, and the entire wire 3 is filled in the machining liquid 7. Since the influence of the surface tension of the working fluid 7 on the wire 3 is eliminated by being immersed, in the cutting area as shown in FIG. P remains. As a result, at the start of cutting of the workpiece 4 with a large number of wires 3, slits of equal pitch P are formed in the workpiece 4, and each wire 3 continues cutting following the slits of the same wire pitch P. Therefore, after the cutting process, the thickness t of a large number of thin wafers can be processed (cut) with high accuracy to the target dimension. Therefore, when starting the processing of the workpiece 4, there is no need for special considerations such as lowering the speed of the wire 3, and thin wafer processing can be performed without special measures on the workpiece 4 side.

On the other hand, as described in the background art section, when the machining liquid 7 partially adheres to the wire 3 in the cutting area, as illustrated in FIG. The second two wires 3 are attached so as to connect to each other, but eventually approach each other like the third and fourth two wires 3 from the left side in an attempt to shrink to a small liquid level due to the surface tension. As described above, according to the partial adhesion of the machining liquid 7, the machining liquid 7 between the wires 3 attracts the wire 3 due to the surface tension, so that the interval between the wires 3 is narrower or wider than a predetermined dimension. .

At the start of cutting of the workpiece 4, if the cuts into the workpiece 4 by the respective wires 3 are formed at intervals corresponding to the prescribed thickness t, the liquid holding plate 8 is moved to a retracted position indicated by an imaginary line, for example, It moves down to the inner bottom position of the end material box 9, or moves horizontally in the direction of the front or back side of the paper surface in FIG. . Due to the movement of the liquid holding plate 8, the lower end of the workpiece 4 being cut (the lower end of the wafer) does not interfere with the liquid holding plate 8 and does not hinder processing.

The liquid holding plate 8 in FIG. 1 is composed of a single plate material, but the liquid holding plate 8 is composed of a plurality of, for example, two divided plates 11 as shown in FIG. It is configured as a single connecting body, and each divided plate 11 is rotatably supported by a support shaft 12 near each main roller 2, and after each workpiece 3 is cut by each wire 3, each divided plate 11 is moved. It can also be moved to the retracted position by rotating in the dropping direction.

As described above, although the machining liquid 7 from above the nozzle 6 is supplied, when the viscosity of the pressurized coating solution 7 is lowered, the wire 3 is sufficient film can not be formed which can be immersed by the machining liquid 7 onto the liquid holding plate 8, As shown in FIG. 6, a number of dedicated nozzles 10 are formed on the liquid holding plate 8 at equal intervals toward the upper surface of the liquid holding plate 8, and the processing liquid 7 is placed on the liquid holding plate 8 from these dedicated nozzles 10. you supply.

The wire misalignment prevention method of the multi-wire saw of the present invention is not limited to a silicon ingot or a silicon block, but can be used when thinly cutting a workpiece 4 made of other materials.

DESCRIPTION OF SYMBOLS 1 Multi-wire saw 2 Main roller 2a Groove 3 Wire 4 Work 5 Base plate 6 Nozzle 7 Processing liquid 8 Liquid holding plate 9 End material box 10 Dedicated nozzle 11 Divided plate 12 Spindle P Wire pitch t Thickness

Claims (5)

In a multi-wire saw that cuts a workpiece into a large number of thin wafers by contacting a workpiece with a large number of traveling wires while supplying a machining fluid to a large number of wires parallel to each other at a predetermined pitch.
A liquid holding plate is arranged below the many wires corresponding to the workpiece in the generation area near the wire, and a gap for holding the liquid is formed between the many wires and the liquid holding plate. When starting to cut the workpiece , the processing liquid is supplied onto the liquid holding plate from the dedicated nozzle formed on the liquid holding plate, the processing liquid is filled on the liquid holding plate, and the entire wire above the liquid holding plate A method for preventing a wire from being displaced in a multi-wire saw, wherein the wire is prevented from being displaced by surface tension of the working fluid partially adhering to the wire. By each wire Wa over click cutting start after the cut-forming of the workpiece, moving the liquid holding plate to the retracted position, multi-wire saw wire skew correcting method according to claim 1, wherein a. Pressurizing the coating solution to be supplied from the upper nozzle on the liquid holding plate, according to claim 1 or claim 2 multi-wire saw wire skew correcting method, wherein the. The liquid holding plate is constituted by one plate, after cutting Write-shape formed at the start of the work cut by the wire, moving the liquid holding plate to the retracted position, according to claim 1, characterized in that, according to claim 2 or 4. The method of preventing wire misalignment of a multi-wire saw according to claim 3 . The liquid holding plate is configured as a connecting body of a plurality of divided plates, and after the cut is formed at the start of workpiece cutting by each wire , each divided plate is rotated and moved to the retracted position. 4. The method of preventing wire misalignment of a multi-wire saw according to claim 2 or claim 3 .

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