JP2824281B2 - Method and apparatus for measuring insulation coating thickness of coated wire for bonding - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method and an apparatus for measuring the thickness of an insulation coating on a coated wire for bonding.

More specifically, the method for measuring the film thickness of the insulating coating film on the bonding wire in which the outer peripheral surface of the gold wire is coated with the insulating coating film made of the insulating resin is improved with respect to the measurement accuracy and the measurement efficiency. An apparatus suitable for performing the method.

[Prior art] Conventionally, as a method of measuring the thickness of an insulation coating of a coated wire for bonding, for example, a method of cutting the coated wire for bonding and measuring it with a microscope, or measuring the outer diameter of the coated wire for bonding with a micrometer There are known a method of calculating and measuring the difference from the outer diameter of the gold wire, and a method of measuring the weight of a unit length of the covering wire for bonding and calculating and measuring the difference from the weight of the same length of the gold wire.

[Problem to be Solved by the Invention] The above-mentioned conventional method for measuring the thickness of the insulating coating of the coated wire for bonding has the following problems.

That is, in the case of using a microscope, the measurement is troublesome and inefficient in order to cut the covering wire for bonding, and visual measurement becomes difficult when the thickness of the insulating coating film is 1 μm or less. . Also, in the case of using a micrometer, a measurement error occurs because an extremely fine covered wire for bonding having a diameter of about 30 μ is easily deformed. In the case of measuring the weight per unit length, measurement accuracy cannot be expected if the thickness of the insulating coating film is as thin as about 1 μm.

The present invention has been made in order to solve such problems, and an object of the present invention is to provide a bonding method capable of accurately and efficiently measuring the thickness of an insulating coating film of a coating wire for bonding even if the thickness is extremely thin. An object of the present invention is to provide a method for measuring the thickness of an insulation coating on a coated wire for use and an apparatus suitable for carrying out the method.

[Means for Solving the Problems] In order to achieve the above-mentioned object, a method for measuring the thickness of an insulating coating of a coated wire for bonding according to the present invention comprises coating an outer peripheral surface of a gold wire with an insulating coating. The covering wire for bonding is immersed in mercury to form a capacitor having a structure in which an insulating coating film of the covering wire for bonding is interposed between the gold wire side and the mercury side of the covering wire for bonding. Means is adopted in which the thickness of the insulating coating film of the coating wire for bonding is calculated and measured by detecting the capacitance.

In addition, the apparatus for measuring the thickness of the insulating coating of the coated wire according to the present invention is a roller that continuously winds the coated wire for bonding formed by coating the outer peripheral surface of the gold wire with the insulating coating film,
It has a mercury tank that stores mercury inside and allows the coated wire for bonding to sink and pass through the mercury, and a capacitor capacity meter connected between the mercury in the mercury tank and the gold wire of the coated wire for bonding. Adopt means.

[Operation] According to the above-mentioned means, the bonding wire is deposited in mercury by utilizing the structure of the bonding wire in which the outer peripheral surface of the gold wire is coated with an insulating coating film made of an insulating resin. When a capacitor is formed by immersion and the capacitance of the capacitor is detected, the thickness of the insulating coating film is calculated and measured from this capacitor capacity and other constant values such as the capacitor area and the dielectric constant of the material of the insulating coating film. Therefore, if the capacitance of the capacitor is accurately detected, regardless of the thickness of the insulating coating film, the measurement accuracy and the measurement accuracy are improved regardless of the thickness of the insulating coating film. An object of the present invention is to provide a method for measuring the thickness of an insulating coating of a coated wire for bonding which can be measured accurately, efficiently, and in a non-destructive manner even when the thickness is extremely thin.

In addition, as for the device, mercury is stored in a mercury tank, and the bonding wire wound by a roller is immersed and passed through the mercury. The line is measured continuously.

Hereinafter, an embodiment of a method and an apparatus for measuring the thickness of an insulating coating of a coated wire for bonding according to the present invention will be described with reference to the drawings.

FIGS. 1 to 4 show a first embodiment of a method and an apparatus for measuring the thickness of an insulation coating on a coating wire for bonding according to the present invention.

In this embodiment, as shown in FIG. 1, slits 11 and 1 formed in a cylindrical shape with a tetrafluoroethylene resin or the like and facing the peripheral wall.
One mercury tank 1 provided with 2, mercury (Hg) 2 stored in the mercury tank 1 so as to reach the slits 11 and 12, and insulation of polyurethane or the like on the outer peripheral surface of the gold (Au) wire 31. Bonding coated wire 3 to be measured covered with resin insulating coating film 32
And a pair of guide rollers 4 and 5 which are guided into the slits 11 and 12 of the mercury tank 1 to be immersed in the mercury 2, and a gold wire 31 formed at the end of the bonding wire 3 made of a conductive material and to be measured. A roller 6 which is connected and winds the covering wire 3 for bonding;
Electrodes 7 provided in mercury tank 1 and in contact with mercury 2
The apparatus comprises a condenser capacity meter 8 connected to the roller 6 and the roller 6, and a recorder 9 connected to the capacitor capacity meter 8.

In this apparatus, when the roller 6 is rotated, the covering wire for bonding 3 is wound thereon. The covering wire for bonding 3 is guided by the guide rollers 4 and 5 during the winding and is slit by the slits 11 and 12 of the mercury tank 1. Immersed and passed through the mercury 2. Therefore, in the mercury tank 1, the third
As shown in the figure, an insulating coating film of the bonding wire 3 is provided between the gold wire 31 side and the mercury 2 side of the bonding wire 3.
A capacitor C having a structure in which 32 is interposed is formed.

Therefore, the capacitance of the capacitor C can be measured by applying a voltage from the capacitor capacitance meter 8 (see FIG. 4), and the insulation coating of the bonding wire 3 is determined based on the capacitance and the other constant value. The thickness of the film 32 can be calculated and measured.

 That is, the capacitor capacity (C) has the following relationship.

Here, ε ₀ is the dielectric constant of vacuum, and 8.854 × 10
^-12 (F / M).

Ε _r is the insulating coating film 32 of the bonding wire 3.
It is known that the dielectric constant is 3.79 when the material is polyurethane.

S is the area of the capacitor, and since the thickness of the insulating coating film 32 of the covering wire 3 for bonding is extremely thin, the gold wire 31 of the covering wire 3 for bonding constituting the capacitor C is formed.
Assuming that the area of the mercury 2 side is similar to that of the mercury 2 side, if the diameter of the gold wire 31 of the bonding wire 3 to be measured is 30 μm and the inner diameter of the mercury tank is 8 mm, π · 30μ × 10 ⁻⁶・ 8 mm × 10
^-3 = 0.754 x ^10-6 .

D is the thickness of the insulating coating film 32 of the bonding coating wire 3.

 The above equation (a) is converted as follows.

Substituting the constant values and the like into the equation (b) yields the following.

Therefore, the following equation is obtained.

For this reason, as long as it is disposed on the bonding wire 3 to be measured in the above-described apparatus configuration, the insulation of the bonding wire 3 can be easily obtained from the equation (c) simply by detecting the capacitor capacitance with the capacitor capacitance meter 8. The thickness of the coating film 32 can be calculated and measured. It should be noted that the numerical value of this calculation and measurement is considerably high if the accuracy of the capacitor capacitance meter 8 is precise.

Further, according to the embodiment of the above-described apparatus configuration, the measurement can be continuously performed over the entirety of the bonding covered wire 3 by the rotation of the roller 6, and a change in the measured value can be recorded in the recorder 9.

FIGS. 5 and 6 show a second embodiment of the method and the apparatus for measuring the thickness of the insulation coating of the coating wire for bonding according to the present invention.

In this embodiment, two large and small capacitors C ₁ and C _{2 are} connected in series with the capacitor C of the first embodiment.

According to this embodiment, there is an advantage that measurement noise is eliminated and measurement accuracy is improved.

FIGS. 7 and 8 show a third embodiment of the method and the apparatus for measuring the thickness of the insulation coating of the coating wire for bonding according to the present invention.

In this embodiment, in addition to the capacitor C _1, C ₂ of the second embodiment, are further connected to the capacitor C ₃ of small parallel.

According to this embodiment, there is an advantage that the measurement noise is more effectively eliminated and the measurement accuracy is further improved.

As described above, in addition to the illustrated embodiment, in performing the method for measuring the thickness of the insulating coating of the coated wire for bonding according to the present invention, it is always necessary to continuously measure the winding of the coated wire 3 with the roller 6. Is not something.

Further, in the apparatus for measuring the thickness of the insulating coating of the coated wire for bonding according to the present invention, the connection of the coated wire 3 for bonding of the capacitor 8 to the gold wire 31 or the like can be performed by another connection structure. .

[Effects of the Invention] As described above, the method for measuring the thickness of the insulation coating of the coated wire for bonding according to the present invention uses the structure of the coated wire for bonding to form a capacitor, and detects the detected capacitor capacitance and the external capacitance. Calculate and measure the thickness of the insulation coating film of the bonding wire with the constant value of the above.If the capacitance of the capacitor is precisely detected, the measurement time and so on will be irrespective of the thickness of the insulation coating film. Since the measurement accuracy is improved without being applied, there is an effect that the measurement can be performed accurately and efficiently even when the thickness of the insulating coating film is extremely thin, and the measurement can be performed in a nondestructive manner.

Furthermore, in addition to contributing to the achievement of the effects of the above-described method, the measurement of the insulating coating film thickness of the bonding coated wire according to the present invention can be performed by winding the bonding coated wire with a roller. There is an effect that measurement can be continuously performed on all lines. Further, this effect produces an effect that the degree of uniformity of the film thickness of the insulating coating film of the coating wire for bonding can be grasped.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a first embodiment of a method and an apparatus for measuring the thickness of an insulation coating on a coating wire for bonding according to the present invention, FIG. 2 is an enlarged sectional view of a main part of FIG. 1, and FIG. FIG. 4 is a cross-sectional view showing the principle of the structure of another main part of FIG. 1, FIG. 4 is an electric circuit diagram of FIG. 3, and FIG. FIG. 6 is an electric circuit diagram of FIG. 5, and FIG. 7 is a third embodiment of a method and an apparatus for measuring the thickness of an insulation coating on a bonding wire according to the present invention. FIG. 8 is an electric circuit diagram of FIG. 1 ... Mercury tank 2 ... Mercury 3 ... Coating wire for bonding 31 ... Gold wire 32 ... Insulating coating film 6 ... Roller 8 ... Capacitor capacitance meter C ... Capacitor (capacitor capacity)

Continuation of the front page (56) References JP-B 27-4230 (JP, B1) (58) Fields investigated (Int. Cl. ⁶ , DB name) G01B 7/08

Claims (2)

(57) [Claims] 1. A bonding wire having an outer peripheral surface coated with an insulating coating film is immersed in mercury, and a bonding coating is provided between the gold wire side and the mercury side of the bonding wire. Forming a capacitor having a structure in which a wire insulating coating film is interposed, and calculating and measuring the thickness of the insulating coating film of the bonding coating wire by detecting the capacitance of the capacitor; Measurement method of insulation coating thickness of wire. A roller for continuously winding a bonding wire formed by coating an outer peripheral surface of a gold wire with an insulating coating film; a mercury stored inside the bonding wire; the bonding wire is immersed in the mercury; An apparatus for measuring the thickness of an insulated coating of a coated wire for bonding, comprising: a mercury tank that is enabled; and a capacitor capacitance meter connected between the mercury in the mercury tank and the gold wire of the coated wire for bonding.