JPH08227909A - Method and apparatus for measuring sliding resistance of thin metal wire - Google Patents

Abstract

PURPOSE: To evaluate the clogging frequency of capillary effectively by varying the angle between a capillary and a thin metal wire stretched upward from the tip of the capillary, sweeping the thin metal wire passing through the inner hole of the capillary and then measuring the tensile load by means of a load gauge fixed with one end of the thin metal wire. CONSTITUTION: A load gauge 1 for measuring tension has a hook 2 fixed with one end of a thin metal wire 6. The thin metal wire 6 is passed through the through hole of a capillary 3 and swept by means of a drive system 5 in order to measure the tensile strength. Sliding resistance is then determined based on the tensile strength thus measured. The angle between the capillary 3 and the thin metal wire 6 has a significant effect on the sliding resistance. Preferably, the angle between the capillary and the thin metal wire extending from the tip thereof is set in the range of 20-160 deg.. This arrangement facilitates evaluation of the loop of thin metal wire and clogging of the capillary.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to evaluation of use performance of thin metal wires used for semiconductor devices and the like.

[0002]

2. Description of the Related Art At present, a wire bonding method using a metal thin wire is the most common technique for connecting an electrode on a semiconductor element and an external lead, and a gold or gold alloy thin wire (wire diameter 20 to 50 μm). Is mainly used.
A ball bonding method is generally used as a method for bonding the thin gold wires. In the connection process, first, the ball portion formed by heating and melting the tip of the thin metal wire is pressure-bonded to the heated electrode of the semiconductor element while applying ultrasonic waves, and then the thin metal wire is guided to the external lead side. Then, ultrasonic bonding is performed on the lead. Here, a jig called a capillary is required to guide the thin metal wire and bond it to the electrode, which is usually made of alumina and ruby.

Due to the recent trend toward higher integration and thinner semiconductor devices, the characteristics to be satisfied by metal thin wires are also diversified. For example, the length of metal thin wires is increased to cope with high-density wiring and narrow pitch. There are demands for thinner lines, higher loops, and lower loops to enable thinner semiconductor devices. To meet these demands, the loop shape (height, linearity, sagging, etc.) of connected metal wires.
It is essential to control. Therefore, the development of the mechanical characteristics of the thin metal wire or the improvement of the bonding technique has been attempted to improve the loop shape.

[0004]

When thin metal wires are connected at a narrow pitch, problems often occur due to contact between adjacent thin metal wires, contact failure with a semiconductor element due to sagging, and variations in shape of several tens. It is required to suppress in the range of μm. Furthermore, when forced loop formation is repeated, problems such as clogging of the capillaries due to wear of the thin metal wires are considered a problem.

To determine the controllability of the thin metal wires during loop formation, a method is generally used in which a large amount of bonding is performed and the loop shape is measured, but it takes time to evaluate and good reproducibility is obtained. In order to obtain the results, it is necessary to maintain the bonding equipment and check the bonding conditions. Also, the judgment about the clogging of the capillaries,
There was no choice but to rely on the investigation of the clogging frequency as a result of a large amount of bonding of fine metal wires or the observation of capillaries.

From the current state of the art, a method for effectively evaluating the loop controllability and the clogging frequency of the capillaries is required, and the present invention provides an apparatus and method therefor.

[0007]

Means for Solving the Problems The present inventors have conducted an investigation to solve the above problems. In order to strictly control the loop shape of the thin metal wire within a range of several tens of μm and to suppress the clogging of the capillary hole, the resistance when sweeping the thin metal wire in the capillary (hereinafter referred to as sliding resistance) It was confirmed that there was a correlation, and a method for easily evaluating the sliding resistance between the thin metal wire and the capillary was found.

The present invention is based on such knowledge and has the following structures. That is, (1) a load meter having a jig for fixing a thin metal wire, a capillary through which a thin metal wire hangs down, an angle adjustment system capable of changing the angle of the capillary, and further the load meter or the capillary holding portion is driven. A sliding resistance measuring device for a thin metal wire, characterized in that it comprises a drive system that
(2) The angle between the thin metal wire pulled upward from the tip of the capillary and the capillary is set in the range of 20 to 160 degrees, and the thin metal wire penetrating the inner hole of the capillary is swept to fix one end of the thin metal wire. A method for measuring sliding resistance of a thin metal wire, which comprises measuring a tensile load with a load meter.

[0009]

The structure of the present invention relating to the semiconductor device will be further described below. FIG. 1 shows an example of the configuration of the measurement system according to the present invention. The load cell 1 measures tension, and one end of a thin metal wire 6 is tied to the hook 2 thereof. The thin metal wire 6 passes through the through hole of the capillary 3,
Sweep the thin metal wire by the drive system 5 to measure the tensile strength,
The sliding resistance with the capillary is determined from the value. The sweep of the thin metal wire can be performed either by moving the load meter 1 or moving the fixed portion of the capillary 3.

The angle a formed by the capillary 3 and the thin metal wire 6
Has a great influence on the sliding resistance. At the time of measurement,
With respect to the angle a formed by the thin metal wire protruding from the tip of the capillary and the capillary, a suitable angle range is preferably 20 to 160 degrees. If it is less than 20 degrees, the measured resistance value is 0.1 gf or less and it is difficult to measure it accurately. If it exceeds 160 degrees, the resistance value is very large and the sliding resistance estimated in the actual bonding process is This is because the difference between Furthermore, the angle dependence of the sliding resistance varies greatly depending on the wire diameter, strength, surface condition of the thin metal wire, the material of the capillary, the tip shape, etc., but it is possible to measure the sliding resistance within the above angle range. is there. Further, during the measurement, it is preferable to perform the measurement while keeping it constant.

The friction resistance between the metal thin wire and the inner wall of the capillary, the deformation resistance of the metal thin wire, and the like are considered as factors of the sliding resistance at the time of bonding, and these resistances are the mechanical characteristics and surface condition of the metal thin wire, The shape of the tip of the capillary and the state of the inner wall affect each other,
It is difficult to separate and evaluate individual factors. The method according to the present invention comprehensively evaluates these factors and reproduces the behavior close to the sliding resistance during actual bonding.

[0012]

EXAMPLES Examples will be described below. As the metal fine wire, a high-purity gold wire having a purity of 99.9% by weight or more, and a gold thin wire drawn to a wire diameter of 30 μm was used. The tensile strength measured as the sliding resistance with the capillary by the method of the present invention was used. Two types of gold wires having significantly different strengths were prepared, and two types of capillaries A and B having different tip shapes and inner wall states were used.

Further, in order to investigate the relationship between the tensile strength and the looping characteristics measured as described above, a ball portion formed at the tip of the thin gold wire was bonded to the aluminum electrode and the lead frame, respectively, using a commercially available automatic bonding device. . Using a projector, the height of the highest part was measured as the loop height, and the deviation from the straight line connecting the joints was measured as the wire bending with 50 loops. In Table 1, those with a small loop height variation and a small loop bending are judged as having a good loop shape, and are displayed with a circle, while those with a loop variation and being unstable,
Alternatively, when the wire bend is not less than 50 μm and is remarkable, it is judged as defective and indicated by x.

The measurement results are shown in Table 1, and four types A, B, having different surface states and roughness as the gold fine wire,
C and D were compared, and two types of capillaries P and Q having different tip shapes and inner wall states were compared.

Examples 1 to 4 are comparisons using fine gold wires, and when the sliding resistance was low, the loop shape was good.
The thin metal wire of Example 4 had a high tensile strength, and the number of connections before the capillary clogging occurred was short even in the bonding experiment, and the defect due to the capillary clogging occurred about 30% less than in the case of Example 1. Example 5
However, if a capillary having a high resistance value is used, the loop shape also becomes defective. From these results, it was confirmed that the sliding resistance value measured by the method of the present invention has a correlation with the loop characteristics. Further, there is an appropriate range of the angle between the metal thin wire and the capillary in the resistance measurement, the resistance value is too small in Example 7, and the resistance value is too high in Examples 8 and 9, and the difference due to the gold wire is evaluated. It is not possible.

[0016]

[Table 1]

[0017]

As described above, according to the method of the present invention,
It is possible to measure the sliding resistance between the thin metal wire and the capillary, and it becomes easy to evaluate the loop shape of the thin metal wire and the clogging of the capillary.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a measuring device.

[Explanation of symbols] 1 load meter 2 wire fixing jig 3 capillary 4 angle adjuster 5 drive system 6 metal fine wire 7 recorder a angle between metal fine wire and capillary

Claims (2)

[Claims] 1. A load meter having a jig for fixing a thin metal wire, a capillary through which a thin metal wire hangs down, an angle adjusting system capable of changing the angle of the capillary, and further the load meter or the capillary holding portion is driven. A sliding resistance measuring device for a thin metal wire, which comprises a drive system. 2. The angle between the metal thin wire pulled upward from the tip of the capillary and the capillary is set in the range of 20 degrees to 160 degrees, and the metal thin wire penetrating through the inner hole of the capillary is swept so that one end of the metal thin wire is swept. A method for measuring sliding resistance of a thin metal wire, which comprises measuring a tensile load with a fixed load meter.