JP2013046026A - Collet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a long-life collet having a low-cost and simple configuration similar to the conventional one, which can solve the problem of bringing back a semiconductor chip without deteriorating the accuracy of mounting the semiconductor chip and can achieve high-speed mounting.SOLUTION: A collet 10 comprises: a cylindrical protrusion 14 of a hard material, which is fixed by pressing into a conventional semiconductor chip suction hole at the end of a shank 13 of a hard material; and a rubber chip 12 which is externally fit to the cylindrical protrusion 14 and fixed by a rubber-like fastening force. An end suction surface 14a of the cylindrical protrusion 14 is constituted on the same plane as an end suction surface 12a of the rubber chip 12 or in a shape in which the end suction surface 14a is drawn down by a height h or less with respect to the end suction surface 12a, so as not to protrude from the end suction surface 12a of the rubber chip 12. The height h is 0.2 mm or less.

Description

  The present invention relates to a collet for holding small IC chips divided from a wafer by an IC chip mounting machine one by one by vacuum suction, transporting them at high speed, and mounting them on a circuit board.

  Conventionally, a plurality of semiconductor chips (hereinafter also referred to as IC chips) have been created, and the IC chips are individually adsorbed and taken out from a wafer in which the plurality of IC chips are individually cut into boundaries. A collet is known in which the extracted IC chip is mounted on a printed circuit board.

  8 (a), (b), (c), and (d) show steps until a collet mounts an IC chip on a printed circuit board in a conventional IC chip mounting machine for an RFID (Radio Frequency Identification) tag, for example. It is a figure showing typically simply.

  In step 1 shown in FIG. 8A, the printed circuit board 3 provided with the conductive pattern is conveyed to a dispenser or the like as indicated by an arrow a. In the dispenser, for example, an anisotropic conductive adhesive 5 or a resist or a conductive film is applied to the circuit pattern of the printed circuit board 3 as shown in Step 2 of FIG.

  In step 3 shown in FIG. 8C, the printed circuit board 3 coated with an adhesive or the like is conveyed to the mounter. Here, the collet 1 carries the IC chip 2 taken out from the wafer and sucked, and the IC chip 2 is mounted on the IC chip mounting position of the printed circuit board 3. A plurality of bumps 4 are formed on the lower surface of the IC chip 2.

  In step 4 shown in FIG. 8 (d), the IC chip 2 bonded to a predetermined position of the printed circuit board 3 by mounting is pressed from above and below and irradiated with heat or ultraviolet rays to form an adhesive (or resist or conductive material). The film (5) is cured, and the bumps 4 of the IC chip 2 and the predetermined wiring of the printed circuit board 3 are electrically connected via the adhesive 5.

  FIG. 9A is a diagram showing the above step 3 in more detail. FIG. 4A shows steps A, B, C, and D in four partitions in the clockwise direction from the upper left. First, in step A, the IC chip picked up from the wafer is held by vacuum suction with a collet at the tip of the mounting head.

  Next, in step B, the IC chip is transported to the substrate by the mounting head. In step C, the IC chip is mounted on the substrate on which an adhesive, a resist, a conductive film or the like is applied, the vacuum suction is released, and the IC chip and the collet are separated.

Finally, in step D, the mounting head separated from the IC chip moves onto the wafer. Then, Step A to Step D described above are repeated.
By the way, among IC chips, in particular, an RFID tag is an IC chip that is frequently used until recently. Since it is used frequently, it is necessary to be inexpensive. In order to reduce the cost, the IC chip is miniaturized to 0.5 mm square or less. This dimension is becoming an industry standard.

  In addition, mass production is necessary for frequent use. That is, it is required to increase the speed of mounting the IC chip on the printer substrate. In the high-speed mounting of a small IC chip of 0.500 mm square or less, a problem that the IC chip is taken home or dropped frequently occurs in the mounting process.

  FIG. 9B is a diagram showing the steps C and D “at the time of a problem” when such a problem occurs. “Problem C” shown in FIG. 5B shows a state where the IC chip 2 cannot be released even if the collet 1 releases the vacuum suction.

  For this reason, in the “problem D”, the so-called “take-away” in which the collet 1 moves to the process A that moves onto the wafer while the IC chip 2 that should have been released from vacuum suction is in close contact with the tip. Will occur.

  It is considered that this take-out malfunction occurs due to a combination of the following two problems. First, immediately after the collet mounts the IC chip on the printed circuit board, the IC chip is held on the printed circuit board only by the viscous resistance or surface tension of the adhesive. However, as the IC chip is miniaturized, the amount of the adhesive is also reduced, so that the holding power of the adhesive is reduced.

  Second, when the collet is an NBR rubber chip, which will be described later, the tip of the rubber chip is also miniaturized as the size of the IC chip is miniaturized, so that the wear resistance of the rubber chip is lowered. On the surface of the NBR that has deteriorated due to wear, the adhesive force increases and the IC chip becomes difficult to separate. These two problems are thought to be the cause.

By the way, as a collet that prevents the IC chip from being taken back as described above and that reliably supplies the IC chip to a predetermined location, a plurality of hemispherical protrusions are formed on the collet contact surface, and the IC chip is vacuum-adsorbed. When the protrusion is elastically deformed, the contact surface is brought into contact with the upper surface of the IC chip, and after the conveyance is finished, the vacuum suction is released to smoothly separate the contact surface and the IC chip by the restoring force of the protrusion. Things have been proposed. (For example, refer to Patent Document 1.)
Also, as a collet that does not damage the IC chip and improves the durability of the adsorption surface, the tapered tip of the collet body made of a conductive rubber material is formed in a cylindrical shape and is fitted and fixed in the center opening of the tip The thing which provided the adsorption | suction part currently formed in the cylindrical shape with a hook with a conductive resin material is proposed. (For example, see Patent Document 2.)
Generally, collets are classified into an integrated type as shown in Patent Document 1 and a separated type as shown in Patent Document 2.

  The conventional collet shown in FIG. 10 (a) shows an integrated collet in which the entire collet is made of a hard material such as metal or engineering plastic for improving durability. In such a collet, the frictional force of the contact surface between the IC chip and the collet is inferior to that of a rubber material. Therefore, there is a disadvantage that the holding posture of the IC chip is disturbed by the inertial force of high-speed operation and the mounting accuracy on the substrate is inferior.

  FIG. 10B is a view showing a separation type collet. The separation type collet 6 shown in FIG. 10B is divided into a shank (shaft portion) 8 and a chip (contact portion with the IC chip) 7. In many cases, NBR (nitrile rubber) is used as the material of the chip portion in order to reduce damage due to impact on the IC chip.

  For this reason, the tip portion of the separation type collet is often referred to as a rubber chip in order to distinguish it from an IC chip. In addition, such a separation type collet is widely used because it can cope with a change in the size of the IC chip to be sucked or the wear deterioration of the sucking part at the tip of the collet by replacing only the rubber chip part. ing. However, the edge of the rubber chip inner diameter side (suction hole) is likely to deteriorate, and the frequency of IC chip take-away problems tends to increase with the deterioration.

JP 2007-042684 A JP 2010-129588 A

  By the way, in Patent Document 1, a plurality of hemispherical microprojections are formed on the contact surface of the collet to prevent take-out and improve mounting accuracy. The collet is formed into a semiconductor chip of 0.500 mm square or less. In order to apply, it is necessary to form a microprotrusion with a size of about 10 μm.

  However, small protrusions with a small size of around 10 μm have low durability and cannot be used for mass production. In addition, the cost of the collet itself may increase due to special surface processing of the suction contact surface having minute protrusions.

  In Patent Document 2, only the tip of the collet is made of a resin material in order to improve the wear resistance. However, if the resin material is a flexible rubber, the wear resistance deteriorates as the wear resistance decreases. The surface increases the adhesive force, making it difficult for the semiconductor chip to come off and causing takeaway.

  Also, if the resin material is a hard resin, good wear resistance can be exhibited, but the frictional force between the semiconductor chip and the suction surface of the collet tip decreases, especially when the collet moves at high speed in the horizontal direction. There is a high risk that the mounting accuracy will be affected by the inertial force.

  Further, when the frictional force is low, a problem that the semiconductor chip is dropped before mounting by high-speed movement in the horizontal direction is likely to occur. Furthermore, there remains a problem that impact damage occurs on the semiconductor chip due to the hard material of the suction surface.

Moreover, the collet of Patent Document 2 has a problem to be solved in that the internal structure of the collet body is complicated and its production requires high technology and high cost.
In other words, in the manufacture of small semiconductor chips such as RFID tags, the problem of “semiconductor chip take-back” is a problem that must be solved at a low cost without deteriorating the mounting accuracy on the premise of high-speed mounting operation. .

  The present invention solves the above-described conventional problems, and in a collet that sucks a small semiconductor chip and mounts it on a printed circuit board at high speed, the mounting accuracy of the semiconductor chip is deteriorated with the same low cost and simple configuration as before. An object of the present invention is to provide a collet that eliminates the problem of taking a semiconductor chip without causing it to be removed and can be mounted at high speed and has a long life.

  In order to solve the above problems, a collet of the present invention is provided in a collet that adsorbs a semiconductor chip, and is provided by a hard projection of a hard material provided at the tip of a hard shank and an external fit to the cylindrical projection. A rubber tip, and the tip of the cylindrical projection is configured not to protrude from the tip of the rubber tip.

In this collet, for example, the hard material forming the shank or the cylindrical protrusion is an engineering plastic or a metal.
In addition, for example, a step difference between the tip of the cylindrical projection and the tip of the rubber tip where the tip of the cylindrical projection does not protrude from the tip of the rubber tip is 0.0 mm to 0.2 mm.

  Further, for example, when the suction surface of the semiconductor chip is a square of 0.500 mm × 0.500 mm, the outer diameter of the cylindrical protrusion is OD, the inner diameter is ID, and the outer diameter of the tip of the rubber chip is Oφ. The inner diameter is Iφ, and OD = 0.400 mm, ID = 0.200 mm, Oφ = 0.700 mm, and Iφ = 0.360 mm.

  The present invention provides a collet that eliminates the problem of take-back of a semiconductor chip without deteriorating the mounting accuracy of the semiconductor chip with a low-cost and simple configuration similar to the conventional one, can be mounted at high speed, has excellent durability, and has a long life. be able to.

It is a figure which shows the structure of the collet which concerns on Example 1 of this invention. (a), (b) is an expanded sectional view which shows the structure of the front-end | tip part of the collet which concerns on Example 1, (c) is a figure which shows a structure in the case of becoming the malfunction. (a), (b) is the tip suction surface of the cylindrical protrusion of the collet and the rubber chip when the surface to be attracted of the semiconductor chip to be attracted by the collet according to the first embodiment is a square with one side L = 0.500 mm. It is a figure which shows the dimensional relationship with the front-end | tip adsorption | suction surface. (a) is a solid graph obtained by plotting the probability density in the range of ± 5σ in equation (2), and (b) is a simulation of the change in the contact area between the IC chip and the collet when the center difference varies. It is a figure which shows the model for doing. FIG. 5 is a diagram illustrating a result obtained when one side L of an IC chip is set to L = 0.500 mm in the simulation of FIG. (a)-(d) is a figure which shows the shape of an IC chip, and the designation | designated location of the dimension L. FIG. It is a table | surface which shows the mounting experiment value by the collet of the conventional collet and a present Example. (a), (b), (c), and (d) schematically show the process until the collet mounts the IC chip on the printed circuit board in the conventional IC chip mounting machine for RFID (Radio Frequency Identification) tags, for example. It is a figure shown simply. 8A is a diagram showing the process 3 of FIG. 8 in more detail, subdivided into processes A to D, and FIG. 8B is a “problem C” and “problem” when a problem occurs in the processes C and D. It is a figure which shows process D of time. (a) is a diagram showing a collet in which the entire collet is composed of a hard material such as metal or engineering plastic for improving durability, and (b) is a separation consisting of a conventional shank and rubber chip. It is a figure which shows the collet of a type | mold.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The collet of the present invention is a collet used when, for example, a small IC chip (especially a size of 0.5 mm × 0.5 mm or less) is mounted at a high speed (especially 0.5 seconds / piece or less) with an IC chip mounting machine. Is assumed.

  FIGS. 1A, 1B, and 1C are diagrams showing a configuration of a collet according to Embodiment 1 of the present invention. In FIGS. 1A, 1B and 1C, the collet is shown facing upward for convenience. As shown in FIG. 1A, the collet 10 of this example includes a shank 11 and a rubber chip 12 attached to the tip of the shank 11.

  FIG. 1B is an exploded view of the collet 10. As shown in FIG. 1 (b), the shank 11 has a cylindrical projection 14 of a hard material, which is a custom made in this example, attached to the tip of a conventional shank 13. The rubber chip 12 is a rubber chip similar to the conventional one except that there are dimensional restrictions.

  The shape of the shank 11 can also be formed by cutting all. In the case of this example, as shown in FIG. 1 (c), the cylinder that becomes the cylindrical protrusion 14 is fixed to the conventional shank 13 by press-fitting or an adhesive as indicated by an arrow a.

  Thus, in the collet of this example, the inner diameter side of the tip adsorbing portion of the rubber tip 12 is reinforced with a hard material such as engineering plastic or metal, so that the deterioration of the rubber tip can be prevented.

  In this case, the metal as the hard material of the cylindrical protrusion 14 may generally be SUS. However, if the durability is taken into consideration, the above tungsten carbide or ceramic can also be used.

2A is an enlarged cross-sectional view of the tip of the collet 10, and FIGS. 2B and 2C are views showing the protruding relationship between the tip of the cylindrical protrusion 14 and the tip of the rubber chip 12. FIG.
As shown in FIG. 2 (a), the cylindrical protrusion 14 of the shank 11 of the present example is fixed by press-fitting the lower end portion into the tip opening hole (conventional semiconductor chip suction hole) of the conventional shank 13. A rubber chip 12 is externally fitted so as to cover from above, and is fixed by a rubber-like tightening force.

  Thus, by using the outer peripheral portion of the suction surface at the tip of the collet as a rubber material, the frictional force that can withstand the inertial force of high-speed movement is maintained, and the mounting accuracy does not deteriorate. Furthermore, a conventional rubber chip can be used as it is.

  In FIG. 2A, the tip suction surface 14a of the cylindrical protrusion 14 and the tip suction surface 12a of the rubber chip 12 form the same plane. This shape is the most ideal shape for the semiconductor chip to be sucked and mounted on a printed circuit board or the like by the tip suction surface 14a of the cylindrical protrusion 14 and the tip suction surface 12a of the rubber chip 12 working together.

  In FIG. 2 (b), the tip suction surface 14 a of the cylindrical protrusion 14 is retracted more than the tip suction surface 12 a of the rubber chip 12. In other words, the tip suction surface 14 a of the cylindrical protrusion 14 has a shape that does not protrude from the tip suction surface 12 a of the rubber chip 12.

  Even in this shape, the suction function for the semiconductor chip works normally, but if the protrusion degree of the tip suction surface 12a of the rubber chip 12 is large, the mounting accuracy is adversely affected. The step h between the tip suction surface 14a of the cylindrical protrusion 14 and the tip suction surface 12a of the rubber chip 12 is preferably 0.2 mm or less.

  When the step h is 0.2 mm or less, even if the tip suction surface 12a is crushed when the tip suction surface 12a of the rubber chip 12 abuts against the suction target surface of the semiconductor chip, the crushed portion is the central axis. On the other hand, since it expands outward in the radiation direction, the mounting function of the cylindrical protrusion 14 is not adversely affected.

  However, when the level difference h exceeds 0.2 mm, when the tip suction surface 12a of the rubber chip 12 abuts against the suction target surface of the semiconductor chip and is crushed, it is not only radially outward but also inside the center axis. Since it expands, it rides on the edge of the tip suction surface 14a of the cylindrical projection 14 and impairs the mounting function of the cylindrical projection 14.

  In summary, the step h between the tip suction surface 14a of the cylindrical protrusion 14 and the tip suction surface 12a of the rubber tip 12 is 0.0 mm as shown in FIG. It can be said that 2 mm or less, that is, the step h = 0.0 mm to 0.2 mm is desirable.

  Further, in FIG. 2C, the tip suction surface 14 a of the cylindrical protrusion 14 has a shape protruding from the tip suction surface 12 a of the rubber chip 12. This is the same as the suction surface of a conventional integrated collet made of only hard material, meaning that the meaning using the rubber chip 12 is lost, and there is a possibility that the suction of the semiconductor chip cannot be maintained during high-speed horizontal movement.

  As shown in FIGS. 1A and 1B and FIGS. 2A and 2B, the collet 10 of this example has an inner diameter of a suction portion at the tip of a conventional rubber chip, such as metal or engineering plastic. Since it is reinforced with a cylinder of hard material, the deterioration of the rubber chip can be greatly delayed.

  Moreover, in the collet of this example, the outer peripheral portion of the suction hole is made of a rubber material. Therefore, it is possible to maintain a frictional force that can withstand the inertial force when the collet moves at high speed in the vertical and horizontal directions with respect to the semiconductor chip. As a result, the mounting accuracy of the semiconductor chip does not deteriorate even after high-speed movement.

  Furthermore, the shank is simply a process of attaching a hard cylinder to a conventional shank, and the rubber tip can be a conventional rubber tip as it is. Further, since the inner diameter of the suction hole of the rubber chip is reinforced with a cylinder, the load on the rubber chip is reduced, and the life of the rubber chip is longer than before.

  Therefore, the collet of this example has an initial cost for manufacturing a shank, but can be used at a running cost lower than the running cost required for a conventional collet. Further, since the shape is simple and not complicated, the shank can be easily manufactured.

  FIGS. 3A and 3B show a cylinder when the surface to be attracted of the semiconductor chip to be attracted by the collet 10 of this example is a square, and one side L of the square is L = 0.500 mm. 4 is a diagram showing a dimensional relationship between a tip suction surface 14a of a protrusion 14 and a tip suction surface 12a of a rubber chip 12. FIG.

  As shown in FIG. 3A, the dimensional relationship described above is OD = 0.400 mm and ID = 0.200 mm, where OD is the outer diameter of the tip suction surface 14 a of the cylindrical protrusion 14 and ID is the inner diameter. Further, as shown in FIG. 3B, Oφ = 0.700 mm and Iφ = 0.360 mm, where Oφ is the outer diameter of the tip suction surface 12 a of the rubber chip 12 and Iφ is the inner diameter.

  Further, as shown in FIGS. 3A and 3B, when the height of the cylindrical protrusion 14 (the portion where the rubber chip is fitted) is 3.60 mm, the height of the rubber chip 12 itself is 3.70 ±. 0.10 mm.

  This dimensional relationship is due to the following reason. First, from the viewpoint of fixing the rubber tip 12 to the shank 11 by rubber expansion and contraction, the inner diameter Iφ of the tip suction surface 12a of the rubber tip 12 (hereinafter simply referred to as rubber tip 12) is the tip suction surface 14a of the shank 11 (hereinafter referred to as “following”). It is desirable that the outer diameter OD of the shank 11) be smaller by about 0.040 mm.

  Further, in accordance with the gist of the present invention that the deterioration of mounting accuracy is prevented by the peripheral rubber material of the cylindrical protrusion 14, it is necessary that the tip suction surface 12a of the rubber rubber chip 12 be in contact with the surface to be suctioned of the semiconductor chip. .

  That is, it is also the gist of the present invention that only the tip of the shank 11 made of a hard material is held in contact with the semiconductor chip. For this reason, the outer diameter OD of the shank 11 disposed on the inner side of the tip suction surface 12a of the rubber chip 12 is required to be smaller than one side L of the square semiconductor chip.

  Next, the outer diameter Oφ of the rubber chip 12 and the inner diameter ID of the shank 11 must take into account variations in the semiconductor chip holding position by the collet 10. This variation occurs because the collet 10 of this example is a mounting-side collet that takes over the holding of the semiconductor chip from the extraction-side collet that accurately takes out the semiconductor chip from the wafer.

  Therefore, the center of the semiconductor chip and the center of the collet 10 do not always coincide. There is a center difference under certain variations. This variation is generally considered to follow a normal distribution with a standard deviation σ.

Here, the probability density function in the one-dimensional direction x is expressed as
Given in.

In the case of this example, the surface to be adsorbed of the semiconductor chip, that is, a two-dimensional plane.
Is used.

  In this equation (2), it can be seen that a line connecting the same probability density becomes a locus of a circle so that “x ^ 2 + y ^ 2” is constant. When the probability density is plotted in the range of ± 5σ in this equation (2), a solid graph as shown in FIG. In this solid graph, the probability density has a base that extends to about ± 3σ. In other words, there is a possibility that a center difference will occur in the range of “(x ^ 2 + y ^ 2) ^ 1/2 ≦ 3σ”.

  Within this range, the contact area between the IC chip and the collet must be kept small. This is because, when the contact area is small, the IC chip is dropped or the mounting accuracy is deteriorated by high-speed operation.

  Here, using the model shown in FIG. 4B, a change in the contact area between the IC chip and the collet when the center difference varies is simulated. When the IC chip is a square of one side L, the collet inner diameter is the shank inner diameter ID, and the collet outer diameter is the rubber chip outer diameter Oφ, the contact area is the portion shown by hatching.

  The center difference x, y is changed within a range of ± 5σ, and the contact area is plotted. The contact area is preferably 60% or more of the IC chip area (= L ^ 2) in the range of “(x ^ 2 + y ^ 2) ^ 1/2 ≦ 3σ” where the center difference may occur.

  FIG. 5 is a diagram showing a result obtained when one side L of the IC chip is set to L = 0.500 mm in the above simulation. This figure shows the simulation results when the conditions are different in three stages from condition (1), condition (2), condition (3) from top to bottom.

  In the right column of the conditions (1), (2), (3), the contents of the conditions (1), (2), (3) are unchanged as one side L = 0.500 mm of the IC chip. In this case, the conditions ID, Oφ, and σ are changed.

  In the column to the right of the condition contents, a three-dimensional graph as a result of simulation with the condition contents is shown. In the right column of the solid graph, the vertical axis indicates the contact area when L ^ 2 = 1, and the horizontal axis indicates the coordinates indicating the variation in the range of −5σ to + 5σ of Y (= X). The cross section of y = x of the solid graph is indicated by a solid line, and the range of “(x ^ 2 + y ^ 2) ^ 1/2 ≦ 3σ” is indicated by a broken line.

  In condition (1) shown in the figure, the contact area exceeds 60% within the range of “(x ^ 2 + y ^ 2) ^ 1/2 ≦ 3σ”, which is a desirable state. On the other hand, in the conditions (2) and (3), since the contact area is less than 60%, there is a concern that problems such as deterioration in mounting accuracy and dropping of the IC chip may occur.

Thus, the outer diameter Oφ of the rubber chip and the inner diameter ID of the shank must be determined by the size of the IC chip and the balance of the variation σ.
Generalized under the condition of y = x and (x ^ 2 + y2) ^ 1/2 = 3σ, that is, the condition where the contact area is minimized in the range of (x ^ 2 + y ^ 2) ^ 1/2 ≦ 3σ Then, the contact area S for L ^ 2 is
Can be approximated by Note that S can be classified into an ID effect, an Oφ effect, and a σ effect, and can be approximated by a quadratic function, a sigmoid function, and a linear function, respectively. Therefore, the above approximate expression is used.

  Here, using equation (3), ID and Oφ may be determined so that S is 0.6 or more according to L and σ. For example, when S is calculated in the conditions (1), (2), and (3) shown in FIG. 5, S is 0.6 or more only in the case of the condition (1).

  For example, in Equation (3), the coefficient conditions are ID / L = 0.1 to 0.7, Oφ / L = 0.2 to 2.2, and σ / L = 0.01 to 0.25. If calculated, S≈0.71 for condition (1) in FIG. 5, S≈0.29 for condition (2), and S≈0.45 for condition (3).

  The dimensions of the shank and rubber tip of the collet of this example shown in FIG. 3 are determined from the above viewpoint. Note that the IC chip is not necessarily limited to a square, but can be variously rectangular, circular, and elliptical.

  FIGS. 6A to 6D are diagrams showing the shape of the IC chip and the designated portion of the dimension L. FIG. FIG. 4A shows the case of a square, FIG. 4B shows the case of a rectangle, FIG. 4C shows the case of a circle, and FIG. 4D shows the case of an ellipse. In any case, L is a straight line in which the dimension between the intersection points where the straight line passing through the center of the shape intersects the outer circumference is the smallest.

As shown in FIGS. 6B to 6D, even when the IC chip is not square, an appropriate collet dimension can be calculated using the above-described equation (3) as in the case of the first embodiment. Yes. In this case, the dimensional condition is
OD (outer diameter of shank protrusion) ≤ L,
Iφ (rubber tip inner diameter) = OD−0.040 mm,
Conditions satisfying ID (inner diameter of shank protrusion) = * 1
Conditions satisfying Oφ (rubber chip outline) = * 1
However, * 1 is a value that satisfies ID and Oφ where S ≧ 0.6 in Equation (3) when the center difference between the collet and the IC chip is given by the standard deviation σ. further,
ID / L = 0.1 to 0.7
Oφ / L = 0.2-2.2,
σ / L = 0.01-0.25,
It is necessary to satisfy the following conditions.

  FIG. 7 shows a conventional collet, a cylindrical protrusion and a rubber chip created under the condition of S = 0.6 or more obtained by an equation obtained by substituting an appropriate coefficient satisfying the above condition in Equation (3). It is a table | surface which shows the mounting experimental value by the collet provided with the relationship.

  In this experiment, a semiconductor chip having a square with an adsorbed surface of 0.450 mm on a side was mounted on a mounting substrate at a speed of 0.5 seconds per piece. In the conventional collet, as shown in the chart of FIG. 7, 200,000 semiconductor chips were mounted, and 0.2% takeout failure occurred.

  On the other hand, in the collet of the present invention, even when 500,000 semiconductor chips are mounted, only 0.02% of takeout failure occurs. That is, the take-out defect rate can be reduced to 1/10 even under the use conditions of 2.5 times the conventional ratio. Of course, the mounting accuracy has not deteriorated compared to the conventional collet.

  From the above results, it is considered that the collet of the present invention functions sufficiently effectively for high-speed mounting of a small semiconductor chip, although it depends on the dimensions and mounting conditions of the semiconductor chip.

  The present invention is used in a semiconductor chip mounting machine, for example, a collet used when a small semiconductor chip having a size of 0.5 mm × 0.5 mm or less is mounted on a printed circuit board at a high speed of 0.5 seconds or less, for example. Can be used.

1 Collet 2 Semiconductor chip (IC chip)
3 Printed circuit board 4 Bump 5 Adhesive 6 Collet 7 Chip (contact part with IC chip, rubber lip)
8 Shank (shaft part)
10 Collet 11 Shank 12 Rubber tip 12a Tip suction surface 13 Conventional shank 14 Cylindrical protrusion 14a Tip suction surface

Claims (4)

In a collet that adsorbs semiconductor chips,
A hard cylindrical projection provided at the tip of the hard shank;
A rubber chip provided to be fitted around the cylindrical protrusion;
Have
The tip of the cylindrical protrusion is configured not to protrude from the tip of the rubber tip,
A collet characterized by that.   2. The collet according to claim 1, wherein the hard material forming the shank or the cylindrical protrusion is engineering plastic or metal.   2. The collet according to claim 1, wherein the step between the tip of the cylindrical projection and the tip of the rubber tip where the tip of the cylindrical projection does not protrude from the tip of the rubber tip is 0.0 mm to 0.2 mm. .   When the suction surface of the semiconductor chip is a square of 0.500 mm × 0.500 mm, the outer diameter of the cylindrical protrusion is OD, the inner diameter is ID, the outer diameter of the tip of the rubber chip is Oφ, and the inner diameter is Iφ. The collet according to claim 1, wherein: OD = 0.400 mm, ID = 0.200 mm, Oφ = 0.700 mm, Iφ = 0.360 mm.