JP2654152B2 - Article feed positioning device - Google Patents

Description

Description: Object of the Invention (Industrial application field) The present invention relates to an article feed positioning apparatus, and particularly to a highly accurate positioning of an article such as a lead frame when assembling a semiconductor device. The present invention relates to a device for positioning a feed of articles.

(Prior Art) In the process of assembling the semiconductor device, a process of mounting a semiconductor chip on a lead frame, a process of performing wire bonding on the mounted semiconductor chip, and a process of performing the wire bonding on a mold die In the step of setting chips, etc., it is required to transport and stop the lead frame and to control the stop position with high precision.

Conventionally, for example, positioning of the transport stop position of the lead frame 1 shown in FIG. 3 is performed by providing pilot holes 6, 6... At regular intervals along the length direction at the side end of the lead frame 1. This is commonly done by engaging a pilot pin (not shown) inside 6, 6,.

However, in this case, pilot pins corresponding to various lead frames 1 having different widths G and feed pitches E are required, and in the case of an assembling process using various lead frames 1, a pilot pin is required for each frame. Must be replaced, and the efficiency of the assembling work is significantly reduced.

In order to solve this drawback, not only can this positioning be performed accurately and at high speed when transferring and positioning an article such as a lead frame, it can also be adapted to various sizes and shapes, and can be manufactured at low cost. For the purpose of providing what is obtained, the applicant has previously filed Japanese Patent Application No. 62-252198.
No. proposed.

That is, as shown in FIG. 4, a lead frame (article)
1. A drive device, which comprises a drive roller 2, an opening / closing roller 3, a drive motor 4 with an encoder, and a timing belt 5 extending between the drive motor 4 and the drive roller 2, for carrying the drive frame 1 A passage detector 8 having a fiber sensor 7 for detecting that a pilot hole (detector) 6 of the lead frame 1 has passed during driving, and a feed amount of the article 1 before or after the passage timing. And a position pulse counter 11 for counting by counting the number of pulses generated by the feed position pulse generator 10 and setting the feed amount of the article 1 from the passing timing to the completion of the article transport driving and positioning. A feed amount setting unit including an additional feed amount setting unit 14 and an initial feed amount setting unit 12 connected to the error calculation unit 13,
And a feed amount control unit 9 for controlling the drive amount of the drive device based on the set feed amount of the article.

FIG. 5 shows a first time chart at this time, in which the initial feed amount setting section 12 sets the frame feed amount (E-C) smaller than the predetermined pitch E (FIG. 3) of the lead frame 1 by the distance C. ) Is set in advance, and the feed time T is set to the acceleration time t.
1, the drive motor 4 is driven at the maximum speed Vmax, divided into a constant speed time t2 and a deceleration time t3.

The center of the pilot hole (detection unit) 6 of the lead frame (article) 1 is the fiber sensor 7 of the passage detection unit 8.
Feed amount D of the article 1 after the timing of passing immediately above
The number of pulse trains P corresponding to the feed amount from the timing at which the detection signal S from the passage detection unit 8 is inverted and the timing at which the detection signal S is inverted again after the time TP until the drive motor 4 stops driving are respectively counted by the position pulse counter 11. , And are obtained by averaging both. The value obtained by multiplying the averaged number of pulses by the feed amount per pulse is the actual feed amount. At this time, the transport time is Δt. It is time to pass directly above.

The error calculator 13 calculates the error between the number of pulses corresponding to the distance D and the actually calculated average number of pulses, and indirectly calculates the error ± ΔD of the distance corresponding to this error.
The number of pulses corresponding to the value obtained by adding the distance C and the error ± ΔD is obtained by the feed amount setting unit 14, and additional feed corresponding to the number of pulses is performed over the additional feed time t4, whereby the read is performed. The feed amount (C + D) from the detection fiber sensor 7 for the frame 1 is always controlled to be constant, and the lead frame 1 is positioned at a predetermined positioning position B.

FIG. 6 shows a second time chart, in which a two-lens sensor in which two sensors are arranged along the transport direction is used as the fiber sensor 7 for detection, and the output of both photo tra outputs PTa and PTb is used. The difference outputs Sa and Sb at which the difference is the maximum are used as the detection signals of the passage detection unit 8, and the lead frame 1 is not stopped until it reaches the target stop position.

Here, from the middle timing of the signals Sa and Sb, the lead frame 1 is conveyed by a constant feed amount to perform this positioning. By increasing or decreasing the feed amount during the deceleration time t3, This is to deal with a change in the time Δt ′ from the middle between Sa and Sb to the end of the maximum speed. That is, the feed amount after the two-lens sensor is set in advance via the number of pulses, and the signals Sa, Sb
The feed amount after the intermediate timing is subtracted via the pulse, and the deceleration time from t3 to t5, that is, the feed amount is determined by the number of remaining pulses at the end of the time t2.

(Problems to be Solved by the Invention) However, in the above-mentioned Japanese Patent Application No. 62-252198, the passage detection unit 8 has a response transmission time, and the transmission position pulse generation unit 10 also has a response transmission time. In addition, the response sending time is not always constant, and has some variation depending on the ambient temperature and the like. Therefore, the amount of movement of the lead frame (article) 1 during the response sending time also varies.

For example, assuming that the moving speed of the lead frame 1 is 250 = / s, the response delay time is 1 ms, and the variation in the response transmission time is ± 10% (the response transmission time is 0.9 to 1.1 ms), the response transmission time is The maximum travel distance is 250 (mm / s) x 0.0011 (s) = 0.275 (mm) The minimum is 250 (mm / s) x 0.0009 (s) = 0.225 (mm), and the difference is 275 (μm)- 225 (μm) = 50 (μm), and the difference has a variation of 50 μm, which leads to the variation of the final positioning position.

Here, if the conveyance speed when the article passes through the passage detection unit is different, the moving amount of the article during the response sending time also changes in proportion to this conveyance speed.

In particular, in the conventional example shown in FIG. 5 described above, the variation of the final positioning position due to a change in the conveying speed when the article passes through the passage detecting unit is caused by the passage detecting unit in the conventional example shown in FIG. It has been found that variations in the final positioning positions due to the high transport speed of the articles when passing through the pods are most problematic.

Here, in a wire bonder in a semiconductor device, μ
Wire bonding accuracy on the order of m is required.
At present, it has been desired to develop a highly accurate feed positioning device without increasing the time spent for transporting articles such as a lead frame.

In view of the above, the present invention has been made by further improving the thing described in the above-mentioned Japanese Patent Application No. 62-252198, and providing a more accurate and high-speed positioning of an article such as a lead frame. Aim.

[Configuration of the invention]

(Means for Solving the Problems) In order to achieve the above object, an article feed / positioning apparatus according to the present invention includes a driving device for driving and transporting an article, and a detection unit of the article passing during the transport driving. A pass detection unit that detects by detecting edges at both ends of the detected portion, an article feed speed when the detected portion passes through the pass detection portion, and a distance from the pass detection portion to a stop position. A setting unit to be set in advance, and an article feeding speed before and after the detected part passes through the passage detecting unit, while maintaining a constant speed lower than the maximum conveying speed, and a feed amount of the article from the passage detecting unit to a constant value. And a feed amount control unit for controlling the feed amount.

Further, edge detection signals at both ends of the detected portion are obtained by the passage detection portion, and a center position of the detection portion serving as a reference position of the feed amount is obtained from these edge detection signals.

(Operation) According to the present invention configured as described above, the feed speed at which the article detection unit passes through the passage detection unit is set to be lower than the maximum transport speed, and the response speed of the detection sensor or control unit. In this case, the feed rate can be controlled to a constant value corresponding to the above, so that more accurate positioning with good reproducibility can be performed without lowering the maximum transport speed.

By controlling the article sending speed before and after the detected portion passes through the passage detecting portion to be constant, that is, when the detected portion passes through the passage detecting portion, the transport speed is higher than the maximum speed of conveyance. By moving the article at a constant speed at a low speed, it is possible to prevent the distortion of the detection signal waveform that may be caused by the movement with acceleration, and to detect the signal waveform within the response speed of the sensor or the like used. Edge detection at both ends of the section can be accurately performed, and the passage timing of the detection section can be accurately detected with good reproducibility.

Further, the center position of the detected portion is accurately obtained by using two edge detection signals at both ends of the detected portion.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

1 and 2 show an example in which the present invention is used for transporting a lead frame. In FIG. 1, a lead frame 1 to be transported is sandwiched between a driving roller 2 and an opening / closing roller 3. In rare cases, the drive roller 2 is connected to a drive motor 4 with an encoder by a timing belt 5, and with the rotation of the drive motor 4, both the drive roller 2 and the opening / closing roller 3 rotate to move the lead frame 1 in FIG. Are transported in the direction A.

A pilot hole 6, 6... Used as a detecting portion of the lead frame 1 in this embodiment is formed at an end portion of the lead frame 1 in the longitudinal direction at a predetermined pitch E. A chip (not shown) is mounted, and a bonding wire (not shown) is bonded by a wire bonder.

In front of the transport positioning position B of the lead frame 1, a distance (C + D) between the position B and the distance C and the distance D is set in the transport direction for detecting the passage of the detection unit, that is, the pilot hole 6. A two-lens sensor 7 including two sensors is provided along the path, and a passage detection unit 8 connected to the two-lens sensor 7 causes a knitting difference output Sa, in which the output difference between the two photocutler outputs PTa and PTb becomes maximum. Sb is used as a test signal. Here, the description will be made using the display of the distance (C + D) from the position B to the distance C and the distance D. However, the display is made in this way for the description using the display of the distance C introduced in the section of the prior art. Therefore, there is no essential reason to distinguish the distance C from the distance D, and therefore, the interval (C + D) may be indicated as a new interval C ′.

The drive motor with encoder 4 is driven at a speed V by a signal from a feed amount control unit 9, and the output of the encoder is converted by a position pulse generation unit 10 into a pulse train P (see FIG. 5) corresponding to the frame feed amount. It is sent to the position pulse counter 11 after being aligned.

FIG. 2 is a time chart of the present embodiment, and FIG. 3 is a plan view of the lead frame 1.

The transport positioning of the lead frame 1 is to transport the island 15 on which the semiconductor chip is mounted by a predetermined pitch E, and the pilot hole 6 serves as a reference for the island 15 and the inner lead 16.

The E ′ setting unit 17 connected to the feed amount control unit 9 performs the frame feed by subtracting the distance C + D from the predetermined pitch E and the error range α in which the pilot hole 6 is considered to pass the twin-lens sensor 7 in advance. An amount E ', that is, a feed amount for a distance of E' = E- (C + D) -α is set in advance. This feed time is divided into an acceleration time t1, a constant speed time t2, and a deceleration time t3. Then, the drive motor 4 is driven at the maximum speed Vmax at the constant speed time t2.

Here, the frame feed amount E 'indicates a range in which the sheet may be conveyed at the highest speed or a range in which the sheet may be conveyed at an accelerated speed instead of at a constant speed. The error range α is an error range that can be assumed due to a variation in the size of the pilot hole 6 or a conveyance slip. Since the error range α is subtracted from the predetermined pitch E, even if there is a variation in the size of the pilot hole 6, the pilot hole to be detected after being transported by the frame feed amount E ′ is surely detected. 6 passes through the twin-lens sensor 7.

In addition, the feed amount control unit 9 presets a constant feed speed VS that is lower than the maximum speed Vmax of the lead frame 1 and that matches the response speed of the binocular sensor 7 and the feed amount control unit 9. VS is connected to the search speed setting unit 18 for sending the lead frame 1 to detect the pilot hole 6 by the VS,
After the lead frame 1 is fed by the feed amount E ', the lead frame 1 is fed at the feed speed VS.

Further, the feed amount control unit 9 arbitrarily sets a distance C + D from when the vehicle passes through the passage detection unit 8 to when the vehicle stops.
D) Connected to the setting unit 19, and by keeping this distance (C + D) constant, accurate positioning with good reproducibility is performed.

The position pulse counter 11 is connected to the passage detection unit 8 and the feed position pulse generation unit 10, and detects the detection signal S from the passage detection unit 8, that is, the first knitting difference signal Sa and the following knitting difference signal Sb. This is for counting the number of pulses between them. A time Tp between the knitting difference signals Sa and Sb at this time is a time required for the one pilot hole 6 to pass above the detection twin-lens sensor 7 and is a feed speed and a hole size. And the position of the hole, etc., and this change also changes the number of the pulse trains.

The position pulse counter 11 is connected to a hole center line calculation unit 20, and the calculation unit 20 calculates 1/2 of the number of pulses between the two stitch difference signals Sa and Sb. 1/2 of this position pulse number
Is the timing at which the center line of the pilot hole 6 passes just above the two-lens sensor 7 of the passage detection unit 8. By controlling the feed position pulse from this timing to the stop, the positioning accuracy with good reproducibility is obtained. Is obtained.

That is, the time tp from the first knitting signal Sa to the stop is tp
The average of the number P1 of pulse trains counted during 1 and the number P2 of pulse trains counted during the time tp2 from the subsequent knitting difference signal Sb to the stop, (P1 + P2) / 2 is the center of the pilot hole 6. Is the number of pulses corresponding to the distance that has passed the detection twin-lens sensor 7, and the value obtained by multiplying this value by the feed amount per pulse is the distance that has actually passed. Also,
The time required for this is Δt ″.

The hole center calculation unit 19 is connected to the (C + D) setting unit 18 and conveys the lead frame 1 until the number of pulses is equal to the number of pulses preset in the (C + D) setting unit 18. As a result, positioning accuracy with good reproducibility can be obtained.

Here, the time Δt ′ between the time when the lead frame 1 is transported at the predetermined search speed VS and the center of the pilot hole 6 reaches immediately above the twin-lens sensor 7 changes due to a feed error,
Time Δt ″ from the passage of this center to the stop
Is the set search speed VS and the set feed amount (C + D)
It is the time determined by

Between these two times Δt ′ + Δt ″, the lead frame 1
Is transported for a distance of (C + D + α + ΔD). Here, α is an error range in which the pilot hole 6 is considered to pass immediately above the twin-lens sensor 7 in advance as described above.
D is the actual feed error. As described above, the search speed when the pilot hole 6 passes through the twin-lens sensor 7 is lower than the maximum speed of conveyance, and is a constant speed corresponding to the response speed of the sensor and the control unit. By the above-mentioned control, only the transfer position control of the conventional example described above has a position variation of, for example, 70 μm, and a positioning accuracy variation including a variation of other factors of 100 μm.
In the present embodiment, it has been confirmed that the accuracy can be improved to a position variation of only the transfer position control of about 25 μm.

In the above-described embodiment, the transport system using the rollers and the drive motor with the encoder is adopted, but it is needless to say that the present invention can be applied to a combination of a reciprocating frame clamp and a pulse motor.

Further, not only a laser sensor can be considered as a detection sensor, but also a CCD line sensor can be applied. Further, an appropriate portion other than the pilot hole may be detected as the detection unit.

〔The invention's effect〕

Since the present invention is configured as described above, it is possible to minimize the delay of the required transportation time and the decrease in the positioning reproduction accuracy due to the response speed of the sensor and the control unit, and to reduce the cost of the device for positioning the article with high positioning accuracy at a low cost. Can be provided.

In addition, it is possible to deal with articles such as lead frames having different sizes and shapes with a small change of setting data without increasing the memory capacity.

Further, for example, lead frames have dimensional errors, and there are variations in the pilot hole diameter, the position of the pilot hole, etc., but since the center in the feed direction is not affected by the variations, accurate positioning can be performed, and the inner lead A pilot hole, which is less deformed by external force or heat, can be used as a reference, so that reliability is improved.

In addition, it is possible to eliminate the effects of lost motion and backlash by always moving an article such as a lead frame in the transport direction.

[Brief description of the drawings]

1 and 2 show an embodiment of the present invention. FIG. 1 is a schematic diagram of the present apparatus, FIG. 2 is a time chart showing a conveying speed on the vertical axis, time on the horizontal axis, and FIG. FIG. 4 is a plan view showing a lead frame, FIG. 4 is a schematic diagram showing a conventional example, and FIGS. 5 and 6 are time charts corresponding to FIG. 2 of a different conventional example. 1 ... lead frame (article), 4 ... drive motor with encoder, 6 ... pilot hole (detection section), 7 ... sensor, 8 ... passage detection section, 9 ... feed amount control section, 10 ...
Position pulse generator, 11 ... Position pulse counter, 17 ...
E 'setting section, 18: Search speed setting section, 19: (C +
D) setting section, 20: hole center line calculation section, A: transport direction,
B: positioning position, C, D: distance, E: predetermined pitch, V: conveyance speed, P: pulse train, S: passage detection signal.

Claims (2)

(57) [Claims] A driving device for driving the transport of the article; a passage detecting section for detecting that the detected section of the article has passed during the transport by detecting edges at both ends of the detected section; A setting unit that presets an article feeding speed when a detection unit passes through the passage detection unit and a distance from the passage detection unit to a stop position; and an article before and after the detected unit passes through the passage detection unit. An article feed positioning device, comprising: a feed amount control unit that maintains a feed speed at a constant speed lower than the maximum transport speed and controls a feed amount of the article from the passage detection unit to a constant value. 2. The apparatus according to claim 1, wherein said pass detection section obtains edge detection signals at both ends of said detected section, and obtains a center position of said detection section which is a reference position of said feed amount based on said edge detection signals. An apparatus according to claim 1, further comprising: