JPH11190604A - Linearity measuring device and method for metal fine wire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To evaluate the linearity of a metal fine wire easily, objectively and quantitatively. SOLUTION: A linearity measuring device for a metal fine wire has a spool mounting part for mounting a spool 3 rotatably, a plane mirror vertically disposed below the spool mounting part, and transparent graduation 8 disposed in front of the plane mirror 6. The spool 3 wound with a metal fine wire 7 is mounted to the spool mounting part, and the metal fine wire 7 is wound out of the spool 3. A specified place of the metal fine wire 7 is hung down in front of the plane mirror 6, and the linearity of the metal fine wire 7 in that place is measured using the graduation 8 and the plane mirror 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a measuring apparatus for evaluating the linearity of a thin metal wire used as a bonding wire for connecting an IC chip electrode and an external lead when mounting a semiconductor device, and a measuring method using the same.

[0002]

2. Description of the Related Art At present, in mounting a semiconductor device, an IC is used.
The wire bonding method is widely used to connect the electrodes on the chip to the external leads. Among these methods, there is a ball bonding method using a thermocompression bonding method or a thermocompression bonding device combined with ultrasonic waves, or a method of forming a ball. In general, a wedge bonding method in which pressure bonding is performed without any pressure is used.

In each of these methods, the unwound metal wire is introduced into a capillary of a bonding tool, and then the ball is formed at the tip of the metal wire drawn out to the tool outlet side. Or directly press the tip of the thin metal wire on the IC chip electrode, move the capillary in the XYZ directions (front and rear, left and right, up and down directions) to form a predetermined loop shape and bond it to the external lead. A method of cutting and wire bonding is used.

[0004]

On the other hand, with the recent miniaturization and thinning of semiconductor devices, the performance required for fine metal wires has been increased in order to cope with narrow pitch and long loop bonding methods. It is one of the important bonding characteristics to stably form a predetermined loop shape in the required performance.

[0005] Factors affecting the loop shape include:
Among the physical and mechanical properties of the thin metal wire, a particularly important factor is the linearity of the thin metal wire used in the wire bonding method. If the linearity is poor, there is a danger that the loop shape will not be stable and will come into contact with adjacent loops or peripheral members to cause a short circuit accident. However, the fine metal wire used for the wire bonding method has a diameter of 20 to 50 μm and a diameter of 500 to 500 μm.
It is used by being wound around a spool in units of 2000 m, and there is no method for objectively evaluating the linearity.

The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to measure the linearity of a thin metal wire wound on a spool, and to simplify the linearity. Another object of the present invention is to provide a measuring device and a measuring method which can be quantitatively and objectively evaluated.

[0007]

As a result of intensive studies, the present inventor has found that the shape of a thin metal wire that inhibits stable loop formation has three contents: twist, large bend, and small bend. By paying attention, the present inventors have studied a measuring device and a measuring method capable of simply and quantitatively and objectively evaluating these contents, and completed the present invention.

That is, the present invention provides the following. (1) a spool mounting portion for rotatably mounting a spool, a plane mirror vertically disposed below the spool mounting portion, and a transparent scale disposed in front of the plane mirror; A spool wound with a thin wire is provided, a thin metal wire is unwound from the spool, a predetermined portion of the thin metal wire is hung in front of the plane mirror, and the linearity of the thin metal wire at that point is measured using the scale and the plane mirror. An apparatus for measuring the linearity of thin metal wires, which is characterized by measuring.

(2) The spool device and the plane mirror are covered with a windshield container, at least a portion of the windshield container in front of the plane mirror is made transparent, and the scale is formed in a transparent portion in front of the plane mirror. The linearity measuring apparatus for a fine gold wire according to the above (1), wherein the sprawl mounting section is driven by a motor. (3) The thin metal wire wound on the spool is sequentially dropped by rotating the spool, and the measuring point of the thin metal wire is positioned on the scale portion, and the linearity of the predetermined portion of the thin metal wire is measured using the scale of the scale portion. A method for measuring the linearity of a thin metal wire wound on a spool, wherein the measurement is performed.

(4) A flat mirror and a transparent scale are used as the scale portion, and a thin metal wire is positioned between the flat mirror and the scale. The method for measuring the linearity of a thin metal wire according to the above (3) to be measured. (5) The spool characterized in that the tip of the thin metal wire wound on the spool is bent into an L shape, the spool is rotated to drop the L-shaped tip of the thin metal wire, and the rotation angle of the tip per predetermined stroke is measured. Measurement method of twist of thin metal wire wound around.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION (Fine Metal Wire) The fine metal wire to be measured in the present invention mainly has a diameter of 10 to 100 μm used as a bonding wire.
It is used by being wound around a spool in units of 0 to 2000 m, but this tends to be longer. In general, Au, Al, Cu and alloys containing these as main components are used as the composition.

As the spool, an aluminum spool having a trunk and a flange at one or both ends and having a trunk outer diameter of about 50 mm and a trunk length of about 25 to 50 mm is generally used, but is not particularly limited. An object of the present invention is to objectively and efficiently measure the linearity of a thin gold wire wound on such a spool. The metal thin wire to be measured in the present invention basically has a property that when unwound from a spool, it hangs down under its own weight and plastically deforms to become a straight line. Therefore, it is intended to unwind the thin metal wire from the spool, measure the linearity of an appropriate location, and measure the linearity of the thin metal wire wound on the spool by averaging and integrating the measured values.

(Measuring Apparatus) An apparatus and a measuring method for measuring the linearity of a thin metal wire according to the present invention will be described with reference to the drawings. FIG. 1 shows an example of the apparatus. 1 is a windshield container and 2 is a front door. At least the lower part of the front part is a transparent material. 3 is a spool wound with a thin metal wire,
Reference numeral 4 denotes a feeding motor, reference numeral 5 denotes a controller, reference numeral 6 denotes a plane mirror provided below the front portion, reference numeral 7 denotes a thin metal wire, and reference numeral 8 denotes a transparent scale portion provided outside the front door 2 at a plane mirror height. A spool 3 around which a thin metal wire is wound is mounted on a spool mounting portion connected to a rotation shaft of a feeding motor 4 above the device, a flat mirror 6 is disposed below the mounting portion, and a transparent scale portion 8 is provided on a front surface thereof. Have been placed.

The spool wound with a thin metal wire is rotatably mounted on a spool mounting portion. The spool mounting portion may be a shaft that can rotate and can fix the spool. Preferably, the spool mounting portion may be a motor-driven type, and the spool 3 may be simply mounted directly on the rotation shaft of the motor 4. When the motor 4 is driven by using the controller 5 and the spool 3 is rotated, the thin metal wire 7 is fed from the spool 3.

The length of the thin metal wire wound on the spool is as long as, for example, 10 m. Since the linearity is measured at, for example, about 10 locations, the thin metal wire until the measurement location is extended is wound by another spool below. You may take it. In that case, the motor may be driven not on the upper spool but on the lower spool. The thin metal wire 7 fed from the spool falls in front of the plane mirror 6, but when the front door 2 is closed in the apparatus shown in FIG. And becomes parallel to the plane mirror 6. Therefore, the transparent scale 8
Referring to FIG. 2 while looking at the thin metal wire 7 through the lens, an image 9 of the thin metal wire reflected on the plane mirror 6 is observed from a position coinciding with the thin metal wire 7, and a straight line of the thin metal wire described below using the scale 8. Measure gender.

The measurement of the torsion of the thin metal wire does not require a plane mirror or a scale, and it is only necessary to measure the rotation angle of the tip of the thin metal wire which is unreeled from the spool and falls from the spool. The measurement is performed using a plane mirror and a scale. For this reason, the plane mirror and the scale are arranged vertically below the spool mounting portion.After the predetermined position of the thin metal wire is extended from the spool, the thin metal wire is cut out by a predetermined length, and the cut thin metal wire is used as the flat mirror and the scale. It is also possible to measure the linearity of the thin metal wire by hanging it down.

The use of a plane mirror and a transparent graduation is most suitable for measuring the linearity of a thin metal wire because simple and accurate measurements can be made. However, the measurement of linearity itself is, for example, an opaque graduation. It is also possible to measure simply by hanging a thin metal wire forward. The transparent scale part can be used with a scale made of a transparent material. In order to increase the measurement accuracy, it is preferable that the scale portion is formed in a flat plate shape so that it can be moved up and down, left and right, and inclined. As an example, it can be exemplified that the scale of the graph paper is copied to a transparent thin plate and used as a flat plate. A magic tape or an adhesive tape may be used for the movement of the flat scale portion, or a structure by crimping using a screw may be used.

Since the measuring device of the present invention is a thin metal wire to be measured, it is preferable to use the measuring device covered with a windshield container capable of preventing the influence of wind such as movement of a person or air conditioning. As shown in FIG. 1, the shape is preferably a rectangular parallelepiped structure in which a door is provided on the front surface because it can be easily manufactured. In addition, a container having only the lower part opened may be taken down from the upper part to be used as a windshield container, or may be formed in another shape according to the need for downsizing the apparatus. In addition, the material of the container needs to have at least a portion having a transparent scale portion formed of a transparent material. However, forming the entire container with a transparent material can be easily manufactured and the inside can be visually recognized. It is preferable in terms of measurement work.

FIG. 3 shows reference lines 10, 11, 12 at the scale.
Is shown. 10 and 11 are reference lengths L
1 is determined, and the bending in this range is measured.
11 and 12 determine the reference lengths 11 and 12,
Cut the lower end of the thin metal wire 7 using scissors, and
2 position. By doing this,
The force at which the thin metal wire is pulled downward at the reference length L2 position can be made small and constant, and the spring width of the end of the thin metal wire at the L2 position can be measured without being affected by its own weight.

The reference length L1 between 10, 11 is 10 to 50.
It is preferable that the reference length L2 between about 11 cm and 11 cm is selected and set from about 1 to 20 cm. (Measurement Items) In the present invention, the linearity of the thin metal wire for stabilizing the loop shape can be evaluated by selecting at least the following measurement items.

Twist -1 The size of the bending of the fine metal wire (hereinafter referred to as "meandering width") -2 Number of bending of the fine metal wire (hereinafter referred to as "number of meandering") -3The amount of bending at the end of the fine metal wire (hereinafter " In the following bending measurements, the meandering width mainly shows the situation of large bends, and the number of meandering shows the situation of small bends even when there is no large bend, and the spring width is not affected by its own weight at all. You can grasp the turning situation. For this reason, there is an advantage that a measure for preventing bending can be easily taken when there is an abnormality in a specific measurement item.

(Measuring Method) The measuring method of the present invention will be described with reference to FIG. The spool 3 around which the thin metal wire 7 is wound is mounted on a spool mounting portion connected to a motor rotation shaft, and the controller 5 is operated to drive the motor 4 to draw out the thin metal wire.

Twist Measurement Method Before the metal wire 7 is extended downward, the tip of the metal wire is formed in an L-shape, the movement of the L-shape is visually observed, and the tip rotation number per predetermined stroke and Measure the angle. Bending measurement method A flat mirror 6 is arranged below the spool 3, and a thin metal wire 7 is drawn out and dropped on the front surface thereof, a motor is stopped at an arbitrary position, and the thin metal wire 7 is cut at a lower position of the flat mirror. Further, a transparent scale 8 is arranged on the front surface of the plane mirror. When the windshield container shown in FIG. 1 is used, the transparent scale portion 8 is arranged as described above by closing the front door 2. It is preferable that the scale portion is formed in a flat plate shape and movably disposed outside the front door 2.

Next, as shown in FIG. 3, the position of the transparent scale is adjusted so that the lower end position of the thin metal wire 7 becomes the reference line 12, and the estimated center line of the thin metal wire 7 and the vertical length of the scale. Make sure the lines match. Next, the position of the line of sight at the time of measurement will be described. FIG. 2 shows a state in which the thin metal wire 7 is shown on the plane mirror 6 as its image 9. The measurement accuracy can be stabilized by fixing the position of the eye of the measurer at the position where 7 and 9 coincide.

After preparing and measuring the sample of the thin metal wire wound on the spool as described above, the same measurement is performed by further extending the wire by a predetermined length. In order to improve the measurement accuracy, it is preferable to measure at least 5 to 10 times. -1 Measurement of meandering width The maximum width W within the reference length L1 between the reference lines 10 and 11 shown in FIG.

-2 Measurement of the number of meandering The number of meandering widths of 1 mm or more among the predetermined number of measurement is defined as the number of meandering. -3 Measurement of spring width The amount of displacement of the end within the reference length L2 between the reference lines 11 and 12 shown in FIG.

[0027]

According to the apparatus and dimensions of the present invention, it is possible to easily, objectively and quantitatively evaluate the linearity of a thin metal wire wound on a spool. Therefore, the loop bending in the wire bonding of the LSI is effectively controlled,
As a result, the mounting density of the LSI can be increased.

According to the present invention, the thin metal wire of which the linearity is evaluated is not only simply selected, but also the evaluation is objectively and quantified. It is also effective for providing a fine metal wire with improved properties.

[0029]

EXAMPLES (Preparation of Fine Metal Wires) Five kinds of 99.99% by weight Au wires of A to D were drawn to a diameter of 30 μm by adjusting the steps which affect the linearity of the fine metal wires. Annealing was performed so as to obtain an elongation of 4%, and a lubricant was applied to the surface thereof, and then two sets of samples were wound on an aluminum spool by 1000 m.

(Measurement of Linearity) For a sample wound around a set of five types of spools A to D, twisting and bending of a thin metal wire were performed using a measuring device shown in FIG. 1 having a scale portion shown in FIG. Was measured by the method described above. The first twist measurement and then the bending measurement were performed by cutting the inner end 50 m of the spool winding 1000 m, and the measurement was repeated every 80 m thereafter, for a total of 10 measurements.

In the torsion measurement, the number of rotations at a length of 0.5 m was measured, and the average value is shown in Table 1. The bending measurement is performed by setting the meandering width reference length L1 (length between 10 and 11) shown in FIG. 3 to 30 cm, and measuring the splashing width reference length (length between 11 and 12) L2 to 10 cm. The width is an average value, the number of meanders is 1 mm meander width
The above numbers are shown in Table 1. (Measurement of Loop Bending Amount of Wire Bonding) Using another set of five kinds of metal fine wire samples A to E, loop bending measurement was performed. First, an IC chip electrode and external leads were wired by a ball bonding method using a UTC200 type bonding machine manufactured by Shinkawa Co., Ltd. equipped with a spool around which a thin metal wire was wound to prepare a wire bonding sample. At this time, loop length 5mm, loop height 20
96 μm wiring in 4 directions was set to 0 μm to obtain a bonding sample. The sample was cut at a tip of 50 m in a 1000 m thin metal wire in the same manner as in the measurement of wire bending, and thereafter, a total of 10 wire bonding samples were prepared for each type using portions at intervals of 80 m.

Next, in the measurement of the loop bending, the amount of loop bending was measured by observing the wired bonding sample from directly above using a length measuring microscope. This situation will be described with reference to FIG. 13 is a ball bonding portion on the IC chip electrode,
Reference numeral 14 denotes a bonding portion on an external lead, and reference numeral 15 denotes a loop formed by using a thin metal wire, which shows a situation observed from directly above. The distance W3 from the center line 16 of 13 and 14 to the center axis of the bent thin metal wire was defined as the amount of loop bending. Of the 96-pin wire bonding sample,
Four corners were measured, and the average value of 40 corners per type was shown in Table 1 as loop bending.

[0033]

[Table 1]

(Measurement Results) Five kinds of gold wires A to E were manufactured by changing the steps affecting the bending of the wire during the manufacturing process so that the amount of bending gradually increased. It can be seen that the torsion and the meandering width match well when compared with the loop bending, which directly affects the amount of line bending. It can be said that the meandering frequency and the spring width qualitatively show the same tendency.

By using the measuring apparatus and the measuring method of the present invention, it is possible to obtain a lot of information about the line bending, and it is possible to evaluate the line bending effectively. For this reason, it can be used effectively when detecting abnormalities in the manufacturing process and performing quality assurance.

[Brief description of the drawings]

FIG. 1 shows an embodiment of an apparatus for measuring the linearity of a thin metal wire according to the present invention.

FIG. 2 shows the relationship between a thin metal wire and a plane mirror.

FIG. 3 shows an example of a scale portion on which a reference line for measuring a fine metal wire is entered.

FIG. 4 is a diagram illustrating a loop bending amount of a bonding wire.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Windshield container 2 ... Door 3 ... Spool 4 ... Motor 5 ... Controller 6 ... Plane mirror 7 ... Fine metal wire 8 ... Scale part

Claims (5)

[Claims] 1. A spool mounting portion for rotatably mounting a spool, a plane mirror vertically disposed below the spool mounting portion, and a transparent scale disposed in front of the plane mirror, wherein the spool device portion is provided. A spool having a thin metal wire wound thereon, unwinding the thin metal wire from the spool, hanging a predetermined portion of the thin metal wire in front of the flat mirror, and using the scale and the flat mirror to determine the linearity of the thin metal wire at that location. An apparatus for measuring the linearity of a thin metal wire, wherein the linearity is measured. 2. A method according to claim 1, wherein said spool device and said plane mirror are covered with a windshield container, at least a portion of said windshield container in front of said plane mirror is transparent, and said scale is formed in a transparent portion in front of said plane mirror; The linearity measuring apparatus for a thin gold wire according to claim 1, wherein the spool mounting portion is driven by a motor. 3. A thin metal wire wound on a spool is sequentially dropped by rotating the spool to position a measurement point of the thin metal wire on the scale portion, and a straight line of a predetermined portion of the thin metal wire is utilized using the scale of the scale portion. A method for measuring the linearity of a thin metal wire wound on a spool, wherein the linearity is measured. 4. A flat mirror and a transparent scale are used as said graduation portion, and a thin metal wire is positioned therebetween, and the linearity of the thin metal wire is measured at a position where an image of the thin metal wire shown on the front mirror can be seen to coincide with the thin metal wire. The method for measuring linearity of a thin metal wire according to claim 3. 5. The tip of a thin metal wire wound on a spool is L
A method for measuring the torsion of a thin metal wire wound on a spool, comprising bending the die into a mold, rotating the spool to drop the L-shaped tip of the thin metal wire, and measuring the rotation angle of the tip per predetermined stroke.