JPS61252693A - Detection for abnormal insertion of electronic component - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to an electronic component insertion machine that automatically inserts an electronic component into a printed circuit board, etc. The present invention relates to a method for detecting.

[Background of the invention]

In devices that use many electronic circuit parts, such as electronic computers,
There is a remarkable trend toward higher density printed circuit boards on which circuit components are mounted. Recently, electronic components with a terminal pin count of 1,000 to 2,000 are sometimes used, but it is impossible to manually insert components with such a large number of terminal pins, and the unit cost is extremely high. Therefore, it is unacceptable to make a defective product due to bent terminal pins, etc. Therefore, highly reliable insertion is required, and therefore K requires a technique to detect whether or not the terminal pin of the component cannot be inserted at the initial stage of insertion.

The present invention relates to a detection method for detecting whether a component pin can be inserted or not.

As described above, when an electronic component having a large number of terminal pins (hereinafter referred to as pins) is inserted into a hole provided in a printed circuit board using an electronic component insertion machine, the component 17 is inserted as shown in FIG. 5(a).
If the pin 18 is deformed, normal insertion will not be possible, and the pin 18 will be bent as shown in FIG. 5(A). In order to detect this abnormal insertion, after inserting the component 17, the board 19
There is a known method of detecting whether the tip of the pin 18 does not protrude from the back side of the pin using a photoelectric element or mechanical contact (Japanese Patent Laid-open No. 52-146861, No. 55-43837).
．． 58-37992). However, these methods
If a large number of pins are arranged at a small pitch, this becomes difficult to implement due to spatial table constraints.

Furthermore, since the detection is performed after insertion, abnormal insertion cannot be detected without damaging the pin.

Figure 6+4), (A) is an example of a part for which it is difficult to apply the above method.
First, they are lined up in a grid pattern on the package of parts 21 at a pitch of about 100 degrees. In order to insert the pins of such components into the board without damaging them, the following abnormal insertion detection method can be considered.

In normal insertion, as shown in FIG. 7(α), the board 2
If there is a pin in contact with the wall surface of the hole n of No. 2, the reaction force that the pin 2 receives becomes a frictional force as shown in FIG. 8(a).

However, if the tip of the pin is out of the hole 23 of the board 22 as shown in FIG. 7 (bl),
As shown in , a steep reaction force is generated from the board when the component is slightly lowered. It seems that the above objective can be achieved if this difference is utilized to accurately measure the change in the reaction force against the descent of the part. However, to the pin in the state shown in FIG. 7(A), it is impossible to apply a large force that would cause buckling deformation of the pin in order not to destroy the pin. On the other hand, if there are a large number of pins, the frictional forces will add up and become large. Therefore, since the magnitude of the reaction force in both cases is close, fs8 diagram (A) that should be detected
It becomes difficult to distinguish changes in the reaction force (Figure 8 (0)
(see 1).

Additionally, the present applicant has previously developed a method for detecting abnormal insertion by examining the characteristic vibration that occurs when a descending pin collides with a board, as a characteristic of pins that cannot be inserted.

FIG. 9 (αI, (A) is a configuration diagram when the principle is modeled. As shown in the figure, the part 5 to be inserted is held by the chuck 26 and attached to the insertion device main body 27 via the spring U. In this configuration, the attachment of the insertion device main body n is considered to be equivalent to being suspended by a spring J having an elastic modulus (JO) equivalent to the longitudinal elasticity of the structure.

Therefore, if the spring constant of spring 4 is 1 and the mass of the part that vibrates together with the parts is the wind, then as shown in Figure 9 (1!1
The natural frequency 9 of the imaging system is expressed by the following equation.

9=πB (1) Now, suppose that the component is lowered and the nine non-insertable pins come into contact with the top surface of the board 4. The pin has relatively high elasticity along its length. If we convert the elasticity into a spring constant and set it to 2, then the vibrating body including the component muscles will be as shown in Figure 9 (A).
As shown in K, it is equivalent to being supported by a plurality of springs at the top and bottom, and has a spring constant of 110 K2 in total.

When the component part descends and pin J collides with the board 29, the impact is quickly attenuated, but the natural vibration of this system, which is expressed by the frequency of the following equation, is as long as the pin 30 and the board 29 are in contact. , (2), it persists for a relatively long time.

f = − month (2) 2π This frequency is unique to the fact that the pin is in contact with the top surface of the board, so it is difficult to use the frequency shown in Figure 9 when the pin is not in contact with the board (in the case of tXS or a pin that cannot be inserted). There isn't, but
This can be distinguished from the case where the pin 3o is touching the wall of the hole.
is possible.

The power spectrum of the vibration in the case of FIG. 9 (4) and (A) is shown in FIG. 10 (α) and (A).

In Figure 1O (α), the pin and the board are not in contact, so
Although only the frequency of fo is detected, Figure 10 tA)
Then, depending on the number of contacting pins, fs = ft − fs・
... is detected.

In this detection method, the kinetic energy of the moving part of the insertion mechanism is converted into vibration of the pin in the form of a collision. In this case, it is desirable that the vibration energy given to the pin be large for the following two reasons.

For one thing, when the resolution of the acceleration detector is low or when there are many noise vibrations, vibrations with a large amplitude are desired in order to increase the accuracy of the 1-detection determination. Furthermore, if the attenuation rate of the signal to be detected is large, there may be cases where vibrations with a sufficient wave number cannot be obtained for analysis with an FFT analyzer. In this way, from the standpoint of measurement, it is advantageous to have a large amount of energy applied to the pin during a collision. However, with the above methods that generate vibrations through collisions, it is difficult to clarify whether the energy at the time of collision is converted into vibrational energy, so it is difficult to stably create the optimal vibrational state for measurement. It's steep.

Furthermore, if a strong frictional force is acting on the vibration system, the vibration to be detected will immediately attenuate, making vibration analysis impossible due to the sample time constraints of the FFT analyzer.

[Purpose of the invention]

The present invention has been made in view of the problems in the L1 prior art, and an object of the present invention is to provide a highly reliable component insertion abnormality detection method.

[Summary of the invention]

A feature of the present invention is that a vibrating device installed in a mechanical vibrating system that grips an inserted part forcibly applies vibration to the vibrating system, and a resonance phenomenon occurs with and without a pin that cannot be inserted. By creating a noticeable difference in the vibration amplitude due to
The point is that abnormal insertion of parts is detected.

[Embodiments of the invention]

An embodiment of the present invention will be described in detail below. FIG. 1 is a block diagram of a specific device for detecting abnormal component insertion according to the present invention.

In FIG. 1, reference numeral 1 indicates an insertion part having a large number of pins 2, which is fixed to a retainer 4 and can be slid vertically by a feed mechanism 7 and a slide guide 8 driven by a motor 6i/c. . The spring 5 connects the vibrating section including the component 1 and the insertion mechanism section with a relatively low spring constant for reasons explained later. 3 is the board, 7 is the feed screw, 8
9 is an acceleration detector, 1G is an amplifier that amplifies the output of the acceleration detector 9, 11 is an FFT analyzer, 12 is a control section, 13 is an excitation device installed in the component vibration system, and 14 is its excitation. an oscillator for controlling vibration of the device 13, 15;
is a photoelectric element, and 16 is a detector. In the device configuration shown in FIG. 1, parts are inserted according to the flowchart shown in FIG. 2, and the operation thereof will be explained below.

Now, in FIG. 1, let F be the maximum force that can be applied to one of the pins 2 of component l without breaking it. When the pin 2 and the board 3 come into contact, a reaction force is generated from the board, causing the barb 5 to be compressed. When the spring 5 contracts by an amount corresponding to the above-mentioned force FsK, the insertion force is such that the pin is on the top surface of the board. Either the pin is on the verge of buckling deformation, or the frictional force of the multiple pins in contact with the wall surface of the hole in the substrate is combined. In the former case, the insertion must be stopped, so perform the following operation to detect which of these cases is the case. That is, the oscillator 15 is activated to vibrate the vibration device 14 at a specific amplitude and frequency, which will also be explained later. After a certain period of time after vibration is applied to the vibrating section including the component 1, when the system enters a steady surface vibration state, the FFT analyzer 13 is activated. As a result of analysis by the FFT analyzer, when the energy of the vibration component of the frequency that characterizes the presence of an uninsertable pin is higher than a set threshold value, it is determined that there is an uninsertable pin, and insertion is stopped. FIG. 4 (AI is a frequency characteristic diagram showing the state.

If this is not the case, the component 1 is lowered by a safe lowering amount determined by the deformable shrinkage amount of one pin and the amplitude of the vibrating part when vibrated. Then, vibration is applied again, vibration analysis is performed using an FFT analyzer, and this operation is repeated thereafter to insert parts while making sure that the pins that cannot be inserted are not damaged.

If the frictional force decreases after the insertion reaches a certain point and the overall insertion force drops below F, then the insertion force will rise again to F or above and it will be necessary to detect the pin that cannot be inserted. Proceed with insertion.

Next, the principle of detecting a pin that cannot be inserted will be explained. The vibrating device 13 acts on the vibrating section as the force changes. Figure wc3 is a model drawing of the vibration device 13 and the vibrating section. The vibrating part including the component 1 to be inserted is supported by a spring 5 (spring constant: 1). Inside the vibration excitation device 13 there is a mass oscillator A, which determines the frequency! Suppose that when it is vibrated at , the amplitude is rl.

At this time, the fluctuating force W generated by the vibration device is expressed as in the following equation, where time is t.

f'=@, -del"(2πf)t, coz(2πf
t>=l', coI(2πft>...
...(3) When the pins and the board are not in contact, the natural frequency fos of the vibration system consisting of the vibrating part l and the thorns 5 and the spring constant of n pins (one per pin [2) Natural frequency when is in contact with the top surface of the board! , is expressed by the following formula.

The natural frequency is fnc Lou' * '#2 p...
.) When a fluctuating external force expressed by equation (3) is applied to a vibration system, the amplitude r of forced vibration caused in the vibration system is expressed by the following equation.

It is the reciprocal of the time constant. In Equation 141, the natural frequency f of the system,
It has been shown that the amplitude r reaches a maximum when the frequency f of the vibration excitation device and the vibration frequency f of the vibration excitation device are equal. If this relationship is represented in a diagram, it will be as shown in Figure 4). That is, while the amplitude increases rapidly near f=f, the amplitude is extremely small when %f and f are far apart. This resonance phenomenon is used for detection and determination as follows.

+1) When the system is vibrated at one of the frequencies shown in formula +21, it is observed as shown in Figure 4 (A), depending on whether the system is in the contact state corresponding to that frequency or not. A large difference in amplitude occurs.

Furthermore, instead of applying vibration with a waveform having a single frequency as described above, vibration is applied with a waveform that includes all frequency components when averaged over time. This kind of vibration I
If expressed as a worth vector, it will look like the waveform α in Figure 4 + CI. With respect to this human power, the gain of the system for vibrations other than natural vibrations is low, so only frequency components corresponding to the contact state existing in the system, such as waveforms, are left.

If vibrations occur due to the structure of the insertion mechanism or the entire device, the above measurements may be prevented. As a countermeasure for this, the spring constant of the spring 5 is made sufficiently lower than that of the pin 2.

Therefore, the natural frequency f of the vibrating part is much smaller than fs jt + . . . when the pins are in contact. Therefore, the gain against harmful vibrations having a frequency close to fs - fs - fs . . . generated in the insertion mechanism of the weak spring 7 is small.

These harmful vibrations will have a negligible effect on the measurements.

The amplitude r of the vibrating part when vibrated is theoretically calculated from the equation (4K) and also derived from the acceleration α measured by the acceleration detector 9 shown in FIG. 1 using the following equation.

α 2πf ”°°°°°°°° (5) The varying force applied by the vibrating device so that the amplitude r of this vibrating part does not become larger than the maximum amount of shrinkage that one pin can deflect without buckling deformation. must be controlled.

Next, we will discuss the case where many pins are in contact with the wall surface of the board hole and the influence of frictional force is large.

When the total frictional force becomes larger than the maximum force F that can be applied to a single pin, it is necessary to excite with a considerably large force in order to overcome the frictional force and vibrate. If there is a pin that cannot be inserted, there is a possibility that the pin will be destroyed by vibration, so it is necessary to gradually increase the excitation force. When the vibrating part overcomes the frictional force and starts vibrating in this way, the z4 worth vector for white noise as shown in the waveform diagram of FIG. 4(C) becomes as shown in FIG. 4 (41).

The number of pins in friction is very large, and the spring constant that is the result of combining them is also multiplied by the number of pins. Therefore, the natural frequency of the pin supporting the frictional force is fs −7t−f
It is considerably higher than s... In FIG. 4(d), a group of six peaks corresponds to vibrations caused by frictional force, and if there is a pin that cannot be inserted, a peak appears in a lower frequency range as shown by waveform α.

Therefore, when a peak appears in the waveform region a of FIG. 4(d), it can be determined that there is an insertable pin.

〔Effect of the invention〕

As is clear from the above-mentioned embodiments, according to the present invention, even when a component has a large number of terminal pins, abnormal conditions such as the terminal pins not entering the holes in the board can be prevented by reducing the vibration amplitude due to the resonance phenomenon. Since it is designed to be able to be detected by creating a difference, there is no risk of deforming the terminal pin and making the part defective during the initial stage of component insertion, and it is economical when inserting this type of expensive component. The effect is great.

[Brief explanation of the drawing]

Figure 1 is a block diagram of a specific automatic component insertion device for realizing the electronic component abnormal insertion detection method of the present invention, and Figure 2 is a
W, a flowchart explaining the procedure for inserting parts into the device shown in Figure 1, Figure 3 is a modem diagram showing the dynamic configuration of the insertion device when a vibration device is added, and Figure 4 ( α
) is a diagram showing the change in the amplitude of the forced vibration with respect to the frequency flfc of the applied vibration, and Figure 4 (41 to Figure 4 (di is the power spectrum, and Figure 4 (Al is the excitation frequency and the characteristic Figure 4 shows the difference between when the frequencies match and when they do not match (C1 is a diagram showing the vibration state when white noise is applied to the system, and Figure 4 (d) shows the effect of strong frictional force. A diagram showing the vibration state of time, Figure 5 (a),
(b) is a diagram showing the state before and after inserting the component into the printed circuit board, FIG. 6 (αl, t3) is a front and side view of the component having a large number of terminal pins, and FIGS.
) is a diagram showing the contact state of the terminal pin and the printed circuit board, No. 8
Figure (α), (AI is Figure 7 (a). Figure 8 (c) is a diagram showing the relationship between the insertion stroke and insertion force in the state of (A). Diagram showing the relationship between insertion stroke and insertion force, No. 9
Figures (4) and (b) are dynamic models of the component insertion device; Figure 10 (α1 is the power spectrum representing the vibration energy for each frequency component when no terminal pin that cannot be inserted is detected; FIG. 10(A) is a diagram showing an example of the power spectrum when a terminal pin that cannot be inserted is detected. 1... Component 2... Terminal pin 3...
Printed circuit board 4... Holding device 5... Spring
6...Motor 7...Feed screw
8...Sliding guide 9...Acceleration detector 1
0... Amplifier l]... FFT analyzer 12... Control section 13... Vibration device 14
...Oscillator 15...Photoelectric element 16...
・Detector A... Vibrating body 4 excluded Patent attorney Masaru Ogawa ￥] j+', 4+-j7
Shizuku 10 Figure 2 Figure 3 Figure 4 (OL) Figure 4 (b) n Outer #AS diagram (OL) Figure 7 (α) Figure 7 (b) Figure 8 (α) Shizuku 8 (b) Inserted straw-7 o Inserted straw o-7 Fig. 9 (α) Fig. 7 (b) Fig. 1 O (L)

Claims (1)

[Claims] In a method for detecting abnormal insertion of an electronic component when automatically inserting an electronic component having a terminal pin into a component insertion hole formed in a board, a vibrating device provided in a mechanical vibration system that grips the inserted electronic component is used. , by forcibly applying natural vibration to the vibration system including the inserted electronic component, and creating a difference in vibration amplitude due to the resonance phenomenon between when there is a terminal pin that cannot be inserted into the component insertion hole and when there is no terminal pin that cannot be inserted into the component insertion hole. A method for detecting abnormal insertion of electronic components to detect abnormal insertion of parts.