KR200174667Y1 - Apparatus for measuring height of wire loop - Google Patents

Abstract

Disclosed is a height measuring device of a wire loop. According to the present invention, a closed circuit formed by connecting a part of the wire from the wire clamp installed in the wire bonding device to the lower end of the capillary, and a part of the wire loop in which the wire bonding is made, detecting the current flowing through the closed circuit. A detector, an amplifier for amplifying the current detected by the detector, a comparator for comparing the measured current value transmitted from the amplifying unit with a preset reference current value, and operating the capacitor according to the measured current value transmitted from the comparator There is provided a height measuring apparatus of a wire loop including a control unit for controlling the control unit, and a central processing unit for calculating and displaying a value compared to the comparator in real length. Since the height measuring device of the wire loop according to the present invention is used in connection with the wire bonding device, the measuring operation can be performed immediately at the wire bonding position.

Description

Height measuring device of wire loop

The present invention relates to a device for measuring a height of a wire loop, and more particularly, a measurement capable of measuring a height of a gold wire loop wire-bonded between an electrode of a semiconductor chip and an inner lead of a lead frame during a manufacturing process of a semiconductor package. Relates to a device.

In general, the manufacturing process of the semiconductor package includes a wire bonding operation. The wire bonding operation is an operation for making an electrical connection by interconnecting a predetermined portion of the inner lead and the electrode of the semiconductor chip die supported by the pad of the lead frame with a gold wire. Wire bonding operations are typically performed by a capillary driven by a transducer, which is a device having a through hole through which a gold wire can pass. The capillary bonds one end of the wire to the first target point (e.g., the electrode of the chip) using ultrasonic waves, heat, and a bonding force, and forms a loop by bending the wire to a predetermined shape. Bond the other end of the wire to a second target point (eg the end of the inner lead). After the bonding operation is finished, the wire is cut.

1A to 1F are explanatory views schematically illustrating performing wire bonding operations using a conventional wire bonding apparatus.

Referring to FIG. 1A, the capital 12 moving by a transducer (not shown) has a gold wire 14 extending in a hollow formed therein, and a ball 15 at an end of the gold wire 14. Is formed. The ball 15 is formed by hanging a molten material like drops when heat is applied to the end of the gold wire 14 by using a high pressure current, and the diameter of the ball 15 may pass through the hollow portion of the capillary 12. It is formed to the extent that it is not. At this time, the clamp 13 is provided in the extension part of the wire 14, and the clamp 13 has a function which fixes the extension part of the wire 14 as needed.

Referring to FIG. 1B, the capacitor 12 is disposed to descend to the surface of the chip die 11 to coincide with the electrode of the first target point, for example, the chip die 11. At this time, the ultrasonic energy B and the mechanical bonding force are transmitted to the capillary 12, and heat A is applied from the bottom of the chip 11 to the electrode portion on the surface of the chip die 11. Bonding is made.

1C shows a state in which the capacitive 12 is rising. One end of the gold wire 14 is held on the surface of the chip 11 when the capital 12 rises.

FIG. 1D shows that the curved portion 14a is formed in a portion of the gold wire 14 by the vertical and horizontal movement of the capillary 12. Vertical and horizontal movement of the capillary 12 curves the gold wire extending from the bottom of the capillary 12 to the surface of the chip 11 as shown in the figure.

Shown in FIG. 1E shows that the capillary 12 descends again to bond the gold wire to the second target point. Capillary 12 approaches a second target point at which the wire is to be bonded, for example a lead frame inner lead, whereby the gold wire 14 located at the end of the capillary 12 has a second target point 16. ) Is placed. At this time, a loop of gold wire 14b is formed between the first target point and the second target point 16 on the surface of the chip 11. In addition, as described with reference to FIG. 1B, the bonding force and the ultrasonic energy are applied to the capillary 12, and heat is applied to the inner lead portion to thereby wire bond the second target point 16.

FIG. 1F shows the state where the gold wire is cut after the wire bonding to the second target point 16 is finished. Once wire bonding to the second target point 16 is made, the capillary 12 rises, with the cross-sectional area of the gold wire 14 between the lower end of the capillary 12 and the second target point 16. Neck areas with reduced diameter are formed. After the neck is formed, the clamp 13 fixes the wire 14, and the wire 14 is cut when the capillary 12 is further raised in that state.

The quality of the wire bonding operation as described above is achieved through the control of various variables. That is, the quality of the bonding may be changed through the control of the bonding force, heat, and ultrasonic energy applied during bonding to the first target point and the second target point, and the loop is formed through the control of the vertical and horizontal motion of the capillary. The quality of can vary. Therefore, by measuring and feeding back these work variables, adjustment and improvement of the work must be made.

According to the prior art, the measurement of the height of the wire loop has been performed using separate measuring equipment. That is, the lead frame after the wire bonding work is carried to a separate measuring equipment to perform the measurement, and the work must be repeated when changing the work variable based on the measured value. However, this method was not only a waste of time, but had a problem of purchasing a separate measurement equipment.

The present invention has been made to solve the above problems, an object of the present invention is to provide an apparatus for measuring the height of the wire loop formed by wire bonding.

Another object of the present invention is to provide a device for measuring the height of the wire loop by configuring a circuit in the existing wire bonding device.

1A to 1F are explanatory views schematically illustrating performing a wire bonding operation using a conventional wire bonding apparatus.

2 is a schematic configuration diagram of a height measuring device of a wire loop according to the present invention.

Brief description of the main symbols in the drawings

Semiconductor Chip Dies 12. Capitol

13. Clamp 14. Gold wire

15. Ball 21. Semiconductor chip die

22.Capillary 23. clamp

24 gold wire Detector

32. Amplification unit 33. Comparator

34. Control unit 35. Closed circuit

In order to achieve the above object, according to the present invention, a closed circuit formed by connecting a part of the wire from the wire clamp installed in the wire bonding device to the lower end of the capillary, and a part of the wire loop in which the wire bonding is made, the closed circuit A detector for detecting a current flowing through the amplifier, an amplifier for amplifying the current detected by the detector, a comparator for comparing the measured current value transmitted from the amplifier and a preset reference current value, and a measured current value transmitted from the comparator According to the present invention, there is provided a height measuring apparatus for a wire loop including a control unit for controlling the operation of the capillary and a central processing unit for calculating and displaying a value compared to the comparator in actual length.

According to one aspect of the invention, the length of the wire from the clamp to the lower end of the capacities is maintained at a predetermined value so that the resistance by the wire from the clamp to the lower end of the capacities becomes a predetermined value. do.

According to another feature of the present invention, the control unit stops the descending of the capillary when the end of the wire held at the lower end of the capillary contacts the wire loop.

Hereinafter, the present invention will be described with reference to an embodiment shown in the accompanying drawings.

2 is a schematic explanatory diagram of a wire loop height measuring apparatus according to the present invention.

Referring to the drawings, the electrode of the semiconductor chip die 21 supported on the pad of the lead frame and the predetermined position of the inner lead 25 are interconnected by a loop 26 of gold wire, that is, wire bonding operation. This has already been done and completed. Loop 26 of gold wire is formed as described above with reference to FIGS. 1A-1F. The highest height of the wire loop 26 is indicated by the letter H in FIG. 2, which is the highest point of the portion where the wire loop 26 is curved from one end of the wire loop 26 bonded to the electrode on the chip die 21. Is the height to.

According to a feature of the present invention, the height measurement device of the wire loop is configured in connection with the wire bonding device. That is, the measuring device of the wire loop includes a capillary 22 which performs wire bonding and a wire clamp device 23 capable of clamping the wire 23 extending from the capillary 22 as necessary. . A closed circuit 35 is also formed that includes a portion of the wire loop 26 that is wire bonded and a portion of the wire 24 held in the capillary 22. In more detail, the closed circuit 35 includes a wire clamp 35, a portion of the wire 24 extending from the wire clamp 35 to the lower end of the capacitor 22, and the chip die 21. ) A portion of the wire loop 26 extending to a height H from the electrode on the surface. Power is applied to this closed circuit by a power applying means (not shown).

The current flowing through the closed circuit 35 may be detected by the detector 31. The current signal flowing through the closed circuit 35 will depend on the height H of the wire loop 26. That is, when power of the same voltage is applied, if the height H of the wire loop 26 is high, the resistance will increase to reduce the magnitude of the current, and vice versa. Since the current detected by the detector 31 is a very fine current signal, it is amplified by the amplifier 32. Next, the amplified current signal is transmitted to the controller 34 through the comparator 33. A preset reference value is input to the comparator 33, which may be, for example, a value of current with respect to the height of the wire loop 26. The amplified signal is compared with a reference value in the comparator 33. The controller 34 receives the current signal to control the operation of the capillary 22, and transmits the current signal to the central processing unit (not shown). In the central processing unit, the measured current value compared to the reference current value in the comparator 33 may be calculated and displayed at the actual height.

Hereinafter, the operation of the height measuring device of the wire loop according to the present invention will be described.

The basic principle for the height measurement of the wire loop is to calculate the actual height by calculating the current value as the height of the wire loop by detecting the current value flowing through the closed circuit configured as described above. That is, if the length of the wire 24 from the wire clamp 23 to the bottom of the capillary 22 can be kept constant, the value of the current flowing through the closed circuit 35 depends on the height H. This is because the change in resistance value for a part of the loop 26 will be changed.

The height measurement of the wire loop should be performed while clamping a part of the wire 24 with the wire clamp 23, where the length of the wire 24 from the wire clamp 23 to the lower end of the capillary 22 is determined. Must match the preset value. That is, the length must match the preset length so that the resistance value of the wire 24 of the corresponding portion can have a preset value. To match the length of the wire 24 to a preset value, lower the capillary 22 to a predetermined position with the wire 24 held vertically, and clamp the wire 24 at that position. Clamp with. Also, in order to perform a subsequent measurement operation, since the capital 22 must be lowered while the wire 24 is clamped to the clamp 23, the wire 22 is lowered by the lowering operation of the capital 22. In the portion of the wire 24 leading to the lower end of the capillary 22, a sufficient length must be secured so that a necking phenomenon in which the cross-sectional area of the portion is reduced does not occur.

In the state where the wire 24 is clamped to the clamp 23, the capacitor 22 moves to the upper portion of the wire loop 26 positioned on the electrode of the chip die 21. At this time, since the capacitor 22 is not yet in contact with the wire loop 26, the closed circuit 35 is not formed.

Capillary 22 then begins to descend toward wire loop 26. The lowering of the capillary 22 is stopped by its end contacting the wire loop 26, whereby the closed circuit 35 described above is formed. That is, a part of the wire 35 from the clamp 23 to the lower end of the capacitor 22 and a part of the wire loop 26 from the lower end of the capacitor 22 to the electrode of the chip die 21. A circuit comprising a is formed. The value of the current flowing through the closed circuit 35 thus formed will vary depending on the value of H, the height of the wire loop 26 shown in FIG. 2. That is, the resistance value varies depending on the length of the wire loop 26 from the lower end of the capillary 22 to the electrode of the chip die 21, and the current signal is detected by the detector 31. After that, as described above, it is transmitted through the amplifier 32, the comparator 33, and the controller 34. When the current detection is transmitted to the control unit 34, the descending of the capillary 22 is stopped. The current signal detected as described above may be displayed at the actual height through the central processing unit.

Since the height measuring device of the wire loop according to the present invention is used in connection with the wire bonding device, the measuring operation can be performed immediately at the same work position after the wire bonding work is performed. In addition, there is an advantage that the operation can be easily performed without having to provide a separate measuring device.

The present invention has been described with reference to one embodiment shown in the accompanying drawings, which is illustrative, and those skilled in the art may understand that various modifications and equivalent other embodiments are possible. will be. Therefore, the true scope of protection of the present invention should be defined by the appended claims.

Claims (3)

A closed circuit formed by connecting a part of the wire from the wire clamp installed in the wire bonding device to the lower end of the capillary, and a part of the wire loop in which the wire bonding is made, A detector for detecting a current flowing through the closed circuit; An amplifier for amplifying the current detected by the detector; A comparator for comparing the measured current value transmitted from the amplifier with a preset reference current value; A controller for controlling the operation of the capacitor according to the measured current value transmitted from the comparator; And a central processing unit which calculates the values compared by the comparator and displays them in actual length. The method of claim 1, wherein the length of the wire from the clamp to the lower end of the capacities is maintained at a predetermined value so that the resistance by the wire from the clamp to the lower end of the capacities becomes a predetermined value. A device for measuring the height of a wire loop. The height measuring apparatus of claim 1, wherein the control unit stops the descending of the capillary when the end of the wire held at the lower end of the capillary contacts the wire loop.