JPH0817879A - Pull tester - Google Patents

Abstract

PURPOSE:To enable a pull tester to properly and efficiently evaluate fine wires even if they are narrow in pitch when a fine wire or a joint of a fine wire such as a lead or a wire used for a semiconductor device is evaluated in strength. CONSTITUTION:A hook 11 of a pull tester tool 10 which hooks a fine wire and pulls it up is formed of shape memory metal, and when the hook 11 is put in between the fine wires, it is turned linear together with a tool 10, and then the hook 11 is turned curved in a shape by a temperature control to be capable of hooking the wire after it is put in. Or, the hook 11 is curved from the start and turned by an angle of 90 degrees to be vertical in position to the fine wires after it is put in between the fine wires. Or, a belt-like plate thin enough and wide enough to its thickness is bent in a thicknesswise direction to serve as a thin-walled wide hook 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention evaluates the strength of a thin wire itself or the strength of a portion where the thin wire is connected to a chip, a package or the like by hooking and pulling up a thin wire such as a lead or a wire of a semiconductor device. It relates to a pull tester used in some cases.

[0002]

2. Description of the Related Art Various inspections are conducted during the development and design of semiconductor devices and during the manufacturing process. It is very important to properly and efficiently perform these inspections in order to guarantee the quality of semiconductor devices. is there.

Various mounting methods have been devised and put to practical use in the field of mounting semiconductor devices. For example, in the case of a chip level connection technology, the basic methods are a wire bonding (WB) method and a tape automated method. There are three types: bonding (TAB) system and control-collapse chip connection (C4) system. Among these, in the wire bonding method, the chip pad and the lead frame, the wiring board terminal, and the like are connected by a wire made of gold, copper, aluminum, or the like. In addition, the TAB method
The inner lead of the TAB tape is used as the chip bump electrode,
Alternatively, the bumped inner leads of the TAB tape are connected to the chip pad by applying heat, pressure, ultrasonic waves, or the like. Further, the outer leads of the TAB tape are soldered to the wiring board terminals and sometimes connected by wires.

A pull tester is used as one of the methods for evaluating the quality of a semiconductor device having a mounting structure using thin wires such as leads and wires. The pull tester is shown in Figure 1.
As shown in 0, by hooking the thin wire 8 on the U-shaped curved hook portion 11 of the tool 10 and pulling it up,
This is a testing machine for evaluating the strength of the thin wire 8 itself, the strength of the connecting portion 81 where the thin wire 8 is connected to a chip, a package, or the like.

In general, the tool unit 1 has a structure in which a tool 10 is suspended from a load cell 15 via a spring 14, and when the thin wire 8 is hooked on the hooking unit 11 to pull up the tool unit 1, the pulling force is increased. Is applied to the load cell 15 and the strength when the thin wire 8 breaks, or when the connecting portion 81 determines that the thin wire 8 does not break, the connecting portion 81
Is measured and evaluated.

[0006]

However, in recent years, the number of fine wires such as leads and wires has increased due to the progress of high integration of semiconductor devices, and the pitch has been narrowed. The gap between the thin wires becomes narrower, and when inserting the curved or bent hook part of the tool into it or hooking the thin wire and pulling it up, the hook part makes contact with or slides to the adjacent thin wire. Evaluation has become difficult.

Therefore, the following measures have been considered.

The evaluation target is only the outermost lead and the wire having a wide gap.

[0009] Some disturbing thin lines are removed in advance and then evaluated.

A tool with a small bent portion that is curved or bent is used.

A push type in which a thin wire is pushed down with a straight tool.

However, each of these countermeasures has some problems.

Since the method of (1) can evaluate only a few pieces per package, for example, in the case of developing and designing, when it is desired to evaluate the strength change in the environmental reliability test tank and to follow the test time, it is necessary to make a large number of samples. Will occur. Further, when a large number of TAB tape leads are collectively bonded, there is a tendency for the connection strength to vary depending on the positions, so that it cannot be said that proper evaluation is made only by measuring the outermost leads.

In the method (1), as shown in (a) to (e) of FIG.
o. 2, No. 4, No. 5) is removed, and the hook portion 11 of the tool 10 is passed through the widened gap,
Is moved laterally and then raised, and a thin wire (No. 3) to be evaluated is hooked and pulled up by the hook portion 11.

However, the work of removing the obstructing fine line requires a great deal of labor and is not efficient. In addition, the thin line (No. 3) to be evaluated is often damaged during the removal, which is a problem.

In the method (1), as shown in FIG. 12, in order to make the tool 10 small, especially in order to shorten the bending edge length, the tool diameter (the tool is usually a bent wire) is made thin (see FIG. (C)), the degree of bending is reduced (Fig. (B)).

However, when the strength of the thin wire 8 is high, the rigidity of the tool 10 (hooking portion 11) when pulling up is low, or there is no space in the shape, so that FIG.
As shown in (g), the bending of the hook portion 11 is returned, and the thin wire 8
It is easy to get out of the way.

In the method (1), as shown in FIG. 13, the linear tool 10 is lowered (FIGS. (A1) and (a2)),
The thin wire 8 is abutted and further lowered to deform the thin wire 8 (Figs. (B1) and (b2)), and to be broken (Fig. (C).
1), (c2)). However, this method is effective when there is a sufficient space below the thin wire 8 with the wiring board 7, but there is a tendency for thinning in both the wire bonding method and the TAB method, and the space is insufficient. Because of this, the thin wire 8 comes into contact with the wiring board 7 before it is broken, and it is often impossible to evaluate.

The present invention was devised in view of such circumstances, and when evaluating the strength of a thin wire such as a lead or wire of a semiconductor device or the strength of a connecting portion of the thin wire, the thin wire has a narrow pitch. Even if there is, the purpose is to provide a pull tester that can be evaluated appropriately and efficiently.

[0020]

[Means for Solving the Problems]

(1) A pull tester according to claim 1 of the present invention is a pull tester for evaluating the strength of a thin wire such as a lead or wire of a semiconductor device by a hooking portion at the tip of a tool and pulling up the wire or its connecting portion. The hook portion of the tool is made of a shape memory material or a material in which a plurality of materials having different linear expansion coefficients are integrated, and when the hook portion is inserted between thin wires, the hook portion is straight or almost straight with the tool. It is characterized in that the hook portion is changed into a curved or bent shape with respect to the tool by adjusting the temperature after the insertion.

(2) A pull tester according to a second aspect of the present invention is a pull tester for assessing the strength of a thin wire such as a lead or wire of a semiconductor device by a hook portion at the tip of a tool and pulling it up or the strength of the connection portion. The hooking portion is curved or bent from the beginning with respect to the tool, and the hooking portion is inserted between the thin wires in parallel with the thin wire, and after inserting, at least one of the stages fixing the tool or the semiconductor device is inserted. It is characterized in that the hook portion is made to face the thin wire at a right angle by rotating.

(3) A pull tester according to a third aspect of the present invention is a pull tester for evaluating the strength of a thin wire such as a lead or a wire of a semiconductor device by a hooking portion at the tip of a tool and pulling it up or a connecting portion thereof. Therefore, at least the tip of the tool is in the form of a strip plate whose thickness is sufficiently thin and whose width is sufficiently larger than the thickness. The tip end of the strip plate shape is curved or bent in the plate thickness direction to make it thin and wide. It is characterized in that it is configured as a hook portion of.

[0023]

[Action]

(1) In the pull tester according to claim 1, since the hook portion is inserted between the thin wires in a state where the hook portion is in a straight shape or a substantially straight shape together with the tool, the narrow wire gap is slightly larger than the tool diameter at a narrow pitch. Even if there is, the hook can be inserted between the thin wires without abutting or sliding contact with the thin wires. Then, after the insertion, the temperature can be adjusted to change the hooking portion to a curved or bent shape with respect to the tool, that is, the original shape as the hooking portion, so that the hooking portion can be hooked on the thin wire.

(2) In the pull tester according to the second aspect, the hook portion is curved or bent with respect to the tool from the beginning, but since the hook portion is inserted parallel to the thin wire when it is inserted between the thin wires, Even if the fine wire gap has a narrow pitch that is slightly larger than the tool diameter, the fine wire can be inserted between the fine wires without abutting or sliding contact with the thin wires. Then, by rotating the tool and the stage relative to each other by 90 ° after the insertion, the hook portion can be made to face the thin wire at a right angle, and the hook portion can be hooked on the thin wire.

(3) In the pull tester according to the third aspect, the thin and wide hook portion in which the strip-shaped tip portion is curved or bent can have a short bending length. Therefore, even if the fine wire gaps have a narrow pitch to some extent, the hook portions can be inserted between the fine wires without abutting or sliding contact with the thin wires. By moving the hook portion horizontally after insertion, the hook portion can be brought into a state in which it can be hooked on the thin wire. Even if the hook is thin, it is wide, so the rigidity is high enough for the short length of the foot,
Even when the strength of the thin wire is high to some extent, the bending of the hook portion is not returned when the wire is pulled up by the hook portion, and the thin wire does not come off.

[0026]

Embodiments of the pull tester according to the present invention will be described below in detail with reference to the drawings.

[First Embodiment] The first embodiment is claim 1
It is an example of the pull tester concerning. The first embodiment is a pull tester having a hook portion made of a shape memory material.
A process of pull-testing the inner lead of the B tape to test and evaluate the strength of the lead or the strength of the connecting portion of the lead will be described.

FIG. 1 is a front view showing the structure of the main part of the pull tester. A tip portion of the tool 10 protruding downward from the tool portion main body 13 is a hook portion 11 made of a highly rigid shape memory alloy. This shape memory alloy causes deformation at a temperature set slightly higher than room temperature,
At room temperature, the hook 11 maintains a straight shape as shown in FIG. 1A, and in the temperature region higher than the set temperature, it has a memorized shape, that is, a curved shape, as shown in FIG. 1B. Become. The shape memory alloy is preferably a Ni-Ti alloy, but is not limited to this. Although illustration is omitted, in the tool unit main body 13, the tool 10 is a spring 1
4 is hung from the load cell 15 via the load cell 4 (see FIG.
0). In addition, the pull tester includes a temperature controller including an infrared spot irradiator, an air jet cooler, and a temperature sensor for temperature control, and also has a mechanism for accurately and linearly forcing, a tool shape, a lead and a tool. It also has an image analysis system for understanding the positional relationship.

Next, the test process will be described step by step with reference to FIG.

FIG. 2A shows a state in which the bump 92 at the tip of the inner lead 8 extended from the film carrier 91 of the TAB tape 9 is bonded to the electrode pad 61 of the chip 6.

FIGS. 2B to 2E show only a part of the inner lead 8.

As shown in FIG. 2B, the tool 10 having a straight shape including the hook portion 11 is inserted into the gap between the leads 8. At this time, the temperature is set to room temperature in order to hold the hook portion 11 in a straight shape. Even if the lead 8 has a narrow pitch such that the diameter of the hook portion 11 is slightly smaller than the gap between the leads 8, the hook portion 11 can be inserted without abutting or sliding contact with the leads 8 adjacent on both sides. it can. The tool 10 is designed to stop when the proper length range is inserted.

Next, as shown in FIG. 2C, the infrared spot irradiator 4 heats the straight hooking portion 11 to transform the hooking portion 11 into a stored curved shape. Also at this time, the tool 10 and the hooking portion 11 do not come into contact with any of the leads 8.

The tip 12 of the hooking portion is located below the lower surface of the lead 8.

Then, as shown in FIG. 2D, the tool 1
0 starts to rise, and the lead 8 to be evaluated is hooked on the curved hooking portion 11. At this time, Tool 1
0 and the hook portion 11 do not contact the other leads 8. As the tool 10 further rises, the lead 8 is pulled up and is in a slightly deformed state.

Subsequently, as shown in FIG. 2E, the tool 10 further rises, and the hook 8 causes the lead 8 to be broken. The tensile force applied to the load cell at the moment of breaking is read and output. The value of this tensile force is taken as the lead breaking strength. After that, the curved hook portion 11 is returned to the straight shape as the temperature drops.

If the strength of the connecting portion 81 of the lead 8 is weaker than the strength of the lead 8, the lead 8 is not broken, but at the connecting portion 81, that is, at the interface between the bump 92 and the electrode pad 61. It will be broken at the interface between the lead 8 and the bump 92, and the similarly output value will be the inner lead bonding strength.

In the above example, the material of the hook portion 11 is a shape memory alloy, but instead of this, as shown in FIG. 3, a material which is generally called a bimetal and which has a plurality of different linear expansion coefficients is integrated. You may comprise. In the example of FIG. 3, the hook portion 11 is made of bimetal in which three kinds of materials 17, 18, and 19 are overlapped and integrated. The coefficient of linear expansion of the materials 17, 18 and 19 from the inside to the outside is α ₁ ,
Assuming α ₂ and α ₃ , α ₁ <α ₂ <α ₃ .

The material is not limited to metal, and may be ceramic or polymer material as long as the shape can be controlled and the hook has suitable rigidity and workability. As a heat source for changing the shape, infrared rays are applied to the tool, but an electron beam or hot air may be used instead. In addition, although the temperature that causes deformation is above room temperature, if the strength changes drastically with temperature, change to a tool that uses a material whose temperature at which deformation occurs is below room temperature and insert a tool that is straight in the cooled state. Alternatively, the strength may be evaluated by returning to normal temperature and using a curved tool. On the contrary, a type in which the curved shape becomes straight when heated to a high temperature may be used.

[Second Embodiment] This second embodiment is claimed in claim 2.
It is an example of the pull tester concerning. The second embodiment is a pull tester having a mechanism for rotating a tool, and will explain a process of pull-testing the outer lead of the TAB tape and performing test evaluation of the strength of the lead or the strength of the connecting portion of the lead.

FIG. 4 is a perspective view showing the structure of the main part of the pull tester. The drive unit 16 that connects the tool unit 1 to the pull tester main body 2 can rotate about the vertical direction of the tool 10. The hook portion 11 at the tip of the tool 10 has a U-shaped curved shape from the beginning.
Although illustration is omitted, in the tool body 13, the tool 10 is suspended by the load cell 15 via the spring 14 (see FIG. 10). The pull tester also includes an image analysis system for grasping the orientation of the tool 10 and the positional relationship between the lead and the tool.

Next, the test process will be described step by step with reference to FIG.

FIG. 5A shows a state in which the connecting portion 81 at the tip of the outer lead 8 extended from the film carrier 91 of the TAB tape 9 is bonded to the terminal 71 of the wiring board 7 via solder. There is.

FIGS. 5B to 5E show only a part of the outer lead 8.

As shown in FIG. 5B, the tool 10 is lowered with the direction of the hook portion 11 parallel to the lead 8 to insert the hook portion 11 into the gap between the leads 8. Hook part 11
The diameter of the lead 8 is slightly smaller than the gap of the lead 8
Even with a narrow pitch, the hook portions 11 can be inserted without abutting or sliding contact with the leads 8 adjacent on both sides. The tool 10 is designed to stop when a suitable length range is inserted such that the tip 12 of the hooking portion is below the lower surface of the lead 8.

Next, as shown in FIG. 5C, the hook portion 11
Tool 10 so that it faces the lead 8 at a right angle.
The drive unit 16 holding the tool through the tool body 13 is rotated by 90 °. The lead 8 remains fixed to the stage 3 that fixes the semiconductor device.

Then, as shown in FIG. 5D, the hooking portion 1
Tool 1 with 1 facing the lead 8 at right angles
0 starts to rise, and the lead 8 to be evaluated is hooked on the curved hooking portion 11. At this time, Tool 1
0 and the hook portion 11 do not contact the other leads 8. As the tool 10 further rises, the lead 8 is pulled up and is in a slightly deformed state.

Subsequently, as shown in FIG. 5E, the tool 10 is further raised, and the lead 8 is broken by the hook portion 11. The tensile force applied to the load cell at the moment of breaking is read and output. The value of this tensile force is taken as the lead breaking strength. After that, the driving unit 16 is rotated in the opposite direction by 90 °, and the hooking unit 11 is returned to the state parallel to the lead 8.

If the strength of the connecting portion 81 of the lead 8 is weaker than that of the lead 8, the lead 8 is not broken but the connecting portion 81, that is, the connecting portion which is a soldered outer lead bonding portion. It breaks at 81, and the value similarly output is the outer lead bonding strength.

Although the tool 10 side is rotated in the above example, the stage 3 side for fixing the semiconductor device may be rotated as shown in FIG. 6 instead. Also,
In the above example, the rotation angle is 90 °, but if the lead 8 and the tool hooking portion 11 face each other at a right angle, they may be rotated by 270 °, or both the tool 10 side and the lead 8 may be rotated. Both may be rotated.

[Third Embodiment] The third embodiment is claimed in claim 3.
It is an example of the pull tester concerning. The third embodiment is a pull tester in which a wide band plate is curved in a direction parallel to the longitudinal direction of the thin wire and used as a hooking portion, and a process for testing and evaluating the wire strength connecting the chip pad and the wiring board terminal is described. explain.

FIG. 7 is a perspective view showing the tip of the tool. As shown in FIG. 7A, the tool 10 is in the form of a strip plate having a thickness t that is sufficiently thin and a width w that is sufficiently larger than the thickness t, as shown in FIG. 7B. In addition, the strip plate-shaped tip portion is curved in a U-shape in the plate thickness direction to form a thin and wide hook portion 11. The thickness t is smaller than the diameter of the tool of the conventional pull tester. However, since the shape is curved in a U shape and the width w is sufficiently large, the rigidity is much higher than that of a bent round bar (wire) having the same diameter as the strip thickness t. There is. Although not shown, the pull tester also includes an image analysis system for grasping the positional relationship between the wire and the tool.

Next, the test process will be described step by step with reference to FIG.

FIG. 8A shows a state in which the chip 6 is die-bonded face-up to the wiring board 7, and the electrode pad 61 and the wiring board terminal 71 are wire-bonded with the Au wire 8.

As shown in FIG. 8B, the thin and wide hook portion 11 at the tip of the tool 10 is inserted into the gap between the wires 8 arranged at a narrow pitch and stopped at an appropriate position. At this time,
Thin and wide hook 1 for narrow pitches to some extent
Since the bending length of 1 is short, it can be inserted without abutting or sliding contact with the adjacent wire 8.

Next, as shown in FIG. 8C, the tool side or the stage side moves in parallel and the wire 8 to be evaluated and the tool 10 come close to each other, and the curved hooking portion 11 and the wire 8 are at right angles. The tool 10 starts to move upward while crossing. At this time, the tool 10 and the hook portion 11 do not contact the other wire 8.

Subsequently, as shown in FIG. 8D, the tool 10 is further raised, and the wire 8 pulled up by the hooking portion 11 is deformed.

As shown in FIG. 8E, the tool 10 is further raised and the wire 8 is broken. The tensile force applied to the load cell at the moment of breaking is read and output. The value of this tensile force is taken as the wire breaking strength. In some cases, fracture may occur at the interface where the wire 8 is ball-bonded to the electrode pad 61, the interface where the wire 8 is wedge-bonded to the wiring board terminal 71, or the ball upper neck portion.

In the above-mentioned example, as shown in FIG. 9A, the hook portion 11 having the width w suppressed to a certain value or less is used to evaluate the curved wire 8. This is because if the hooking portion 11 has a larger width w ₁ as shown in FIG. 9B, it is not surface contact but two-point support at both ends, which is not preferable in measuring the breaking strength. As shown in (c) of FIG. 9, in the case of a straight thin wire 8 such as an inner lead of a TAB tape, a hooking portion 11 having a larger width w ₁ may be used.

When the strength of the thin wire or the strength of the connection portion thereof is evaluated in the development designing and manufacturing process of the semiconductor device as in the above embodiments, almost all thin wires are irrelevant regardless of the position of the thin wire. , The adjacent thin wire is not required to be removed, and the hooking part has a relatively large diameter and has sufficient rigidity so that the bending does not return when the wire is pulled up and it does not come off the thin wire. Even under the condition that there is not enough space underneath, the strength of the thin wire or its connection can be evaluated properly, accurately, efficiently and easily.

Although the first to third embodiments have been described above, the present invention is not limited to these.
Each of them may be used alone, or a pull tester having a combined configuration may be used. In each embodiment, the tool side is moved up and down, left and right, and rotated, but instead of this, the stage side may be driven.

[0062]

【The invention's effect】

(1) According to the pull tester of claim 1, since the straight hooking portions of the tool are inserted between the thin wires, even if the fine wire gap has a narrow pitch such that the gap is slightly larger than the tool diameter, the hooking portions are inserted between the thin wires. The hooking portion can be hooked to the thin wire because the hooking portion can be changed to a curved or bent shape by adjusting the temperature after the insertion. Therefore, regardless of the position of the thin wire, almost all thin wires, without the trouble of removing the adjacent thin wires, and because the hook has a relatively large diameter and sufficient rigidity, it can be pulled up. The bending does not return to the fine line and the strength of the fine line or its connection can be evaluated appropriately and efficiently even under the condition that there is not enough space below the fine line.

(2) According to the pull tester of claim 2,
Since the hooks that are curved or bent with respect to the tool from the beginning are inserted parallel to the thin wires, they are inserted parallel to the thin wires, so even if the narrow wire gap is slightly larger than the tool diameter, the hooks will be hooked. The part can be easily inserted between the thin wires, and after inserting the tool, the tool and the stage are rotated relative to each other by 90 ° so that the hooking part faces the thin wire at a right angle and the hooking part can be hooked on the thin wire. You can do it. Therefore, regardless of the position of the thin wire, almost all thin wires, without the trouble of removing the adjacent thin wires, and because the hook has a relatively large diameter and sufficient rigidity, it can be pulled up. The bending does not return to the fine line and the strength of the fine line or its connection can be evaluated appropriately and efficiently even under the condition that there is not enough space below the fine line.

(3) According to the pull tester of claim 3,
The thin and wide hooking part with the strip-shaped tip bent or bent can shorten the length of the bending edge, and the hooking part can be easily inserted between the thin wires even if the thin wire gap is a narrow pitch to some extent. It is possible to move the hook portion horizontally after the insertion, so that the hook portion can be hooked on the thin wire. Therefore, the same effects as those of claims 1 and 2 can be obtained. In particular, the hook is wide even if it is thin, so the rigidity is high enough for the short length of the foot, so even if the strength of the thin wire is high to some extent, it will be hooked when pulled up. It is possible to prevent the bending of the part from being returned and coming off the thin wire.

[Brief description of drawings]

FIG. 1 is a front view showing a configuration of a main part of a pull tester according to a first embodiment of the present invention.

FIG. 2 is a perspective view illustrating a test process of the first embodiment.

FIG. 3 is a front view showing a configuration of a main part of a pull tester of a modified example of the first embodiment.

FIG. 4 is a perspective view showing a configuration of a main part of a pull tester according to a second embodiment of the present invention.

FIG. 5 is a perspective view illustrating a test process of the second embodiment.

FIG. 6 is a perspective view showing a configuration of a main part of a pull tester according to a modification of the second embodiment.

FIG. 7 is a perspective view showing a tip end portion of a tool of a pull tester according to a third embodiment of the present invention.

FIG. 8 is a perspective view illustrating a test process of the third embodiment.

FIG. 9 is a side view showing a wider hook portion as a modified example of the third embodiment.

FIG. 10 is a front view showing a general configuration of a conventional pull tester.

FIG. 11 is an explanatory diagram showing a state in which a test is performed by removing a fine line that interferes with a conventional pull tester.

FIG. 12 is an explanatory diagram showing a tool in which a pocket length of a hook portion is shortened as a modification of the conventional pull tester and a test is performed using the tool.

FIG. 13 is an explanatory diagram showing a state in which a straight tool is descended to break a thin wire in the related art.

[Explanation of symbols]

 1 ... Tool part 2 ... Pull tester main body 3 ... Stage 4 ... Infrared spot irradiator 6 ... Chip 7 ... Wiring board 8 ... Fine wire (lead, wire) 9 ... TAB tape 10 ... Tool 11 ... … Hooking part 12 …… Hooking part tip 13 …… Tool part body 14 …… Spring 15 …… Load cell 16 …… Drive part

Claims (3)

[Claims] 1. A pull tester for assessing the strength of a thin wire such as a lead or a wire of a semiconductor device by a hook portion at the tip of a tool to pull up and evaluate the strength of the thin wire or its connection portion, wherein the hook portion of the tool is a shape memory material. Or, it is composed of a material that integrates multiple materials with different linear expansion coefficients.When inserting the hooking part between the thin wires, the hooking part is straight or almost straight with the tool, and after inserting the temperature adjustment The pull tester is characterized in that the hook portion is changed into a curved or bent shape with respect to the tool. 2. A pull tester for pulling up a thin wire such as a lead or wire of a semiconductor device with a hooking portion at the tip of a tool to evaluate the strength of the thin wire or its connecting portion, wherein the hooking portion is initially attached to the tool. It is curved or bent from, and the hooks are inserted between the thin wires in parallel with the wires, and after inserting, at least one of the stage fixing the tool or the semiconductor device is rotated to make the hooks perpendicular to the wires. A pull tester characterized by being opposed to. 3. A pull tester for evaluating the strength of a thin wire such as a lead or a wire of a semiconductor device by a hook portion at the tip of the tool and pulling it up to evaluate the strength of the thin wire or its connection portion. It is characterized in that it is formed into a strip plate shape that is sufficiently thin and has a width that is sufficiently larger than the thickness, and that the tip end portion of the strip plate shape is curved or bent in the plate thickness direction to form a thin and wide hook portion. A pull tester.